Hindawi Publishing CorporationThe Scientific World JournalVolume 2013 Article ID 123160 12 pageshttpdxdoiorg1011552013123160

Research ArticleA Technical Economic and EnvironmentalPerformance of Grid-Connected Hybrid (Photovoltaic-Wind)Power System in Algeria

Djohra Saheb-Koussa Mustapha Koussa and Nourredine Said

Centre de Developpement des Energies Renouvelables BP62 Route de lrsquoObservatoire Bouzareah 16340 Alger Algeria

Correspondence should be addressed to Djohra Saheb-Koussa dkoussacderdz

Received 5 August 2013 Accepted 3 October 2013

Academic Editors N F Atta M Q Fan and M Yari

Copyright copy 2013 Djohra Saheb-Koussa et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

This paper studies the technical economic and environmental analysis of wind and photovoltaic power systems connected to aconventional gridThemain interest in such systems is on-site consumption of the produced energy system hybridization poolingof resources and contribution to the environment protection To ensure a better management of system energy models have beenused for determining the power that the constituting subsystems can deliver under specific weather conditions Simulation isperformed using MATLAB-SIMULINK While the economic and environmental study is performed using HOMER softwareFrom an economic point of view this allows to compare the financial constraints on each part of the system for the case of Adrarsite which is located to the northern part of the south of Algeria It also permits to optimally size and select the system presentingthe best features on the basis of two parameters that is cost and effectiveness From an environmental point of view this studyallows highlighting the role of renewable energy in reducing gas emissions related to greenhouse effects In addition through aset of sensitivity analysis it is found that the wind speed has more effects on the environmental and economic performances ofgrid-connected hybrid (photovoltaic-wind) power systems

1 Introduction

Recently a growing number of organizations have begun toconsider renewable energy and industries related to theirproduction distribution and services as opportunities totake rather than regulations [1ndash6] Several factors includingKyoto Protocol alarming reports from the IntergovernmentalPanel on Climate Change (IPCC) and Copenhagen climatechange conference (COP15) have contributed to this changein opinion and many countries believe that the trend willcontinue such that it is very important for them to immedi-ately prepare for the ldquogreen racerdquo The Algerian governmentand companies are not exceptions indeed they have recentlyintensified their efforts towards promoting the economicgrowth via supporting green industries Examples showingsuch efforts include plans for establishing numerous energyclusters in many areas like the proposed wind farm (project)with a capacity of 10 megawatts launched in Adrar and

the hybrid plant in the region of Hassi RrsquoMel (Laghouat) builtand made operational in February 2011 Similar projectsenvironmentally friendly and producing clean and renewableenergy are scheduled for the areas of Timimoun and KuntaZaouiet encouraging the use of renewable energy [7 8]

Electrical energy generation from wind and PV sourcesis considered as being the most promising renewable energyand is therefore to be developed to replace coal oil gasand even nuclear based production However any process oftransforming energy from one form into another usable formis complex and naturally includes a certain number of eco-nomic and environmental features of different kinds (oper-ation of large-scale renewable energy requires space wherethe resource is available that requires a ldquogoodrdquo managementplanning and the electrical networks will also be adapted andmanaged so as to promote decentralized production) Theobtained technoeconomic and environmental results allowreaching an objective judgment regarding the studied system

2 The Scientific World Journal

2 Presentation of the DifferentSystems of Distributed Generation fromRenewable Energy

Standalone Systems For standalone installations the energyproduced employing photovoltaic solar panels or wind gener-ators is either immediately consumed (pumping ventilationlighting refrigerator etc) or stored in batteries for later useThe produced current is either directly fed to the consumingequipment or converted using an inverter to supply devicesthat require AC power [10 11]

Multisource Hybrid Systems These systems supply electricitythat is often used at remote sites and are built couplingdifferent sources of production of electrical energy such aswind solar and othersThey also allow amore reliable supplyof electricity Nearly two billion people are not connectedto the utility grid (44 of the world population) Thusthe development of hybrid systems for renewable energyconversion will undoubtedly help to solve many socialproblems especially in poor countries and open up vastcommercial markets [10 12ndash15]

Distributed Systems Connected to the Grid These are usuallymedium and large systems which are grid connected [16ndash19]and which in general produce electrical energy amountsdepending on sunshine and wind conditions (Figure 1)

3 Characteristics of the PV-WindSystems Considered

The architecture presented in Figure 1 is the one upon whichthis paper is based With this type of PV-wind system for thegeneration of electrical energy the objective is to inject intothe grid the energy thus generated

For the design the power production of the differentsources becomes freely controllablewithout affecting the statevalues of the grid Decoupling the state values means that thevariations of the renewable resources like the velocity of thewind and the intensity of the solar radiationwill not influencethe state values of the electrical grid as the harmonicsgeneration flickers frequency fluctuation under voltage andover voltage These values are only controlled by the inverterfor the photovoltaic generator and by the microprocessor-controlledOptiTip pitch regulation ensuring continuous andoptimal adjustment of the angles of the blades in relation tothe prevailing wind for the wind generator On the otherhand changes in the loads which influence the state valuesof the grid will not affect the generation side

A controlmanagement strategy is developed for thisarchitecture to operate it in the highest efficient way Theefficiency here means the most utilization of the renewableenergy sources in order to minimize the cost of the producedenergy while preserving the reliability of the system

4 Methodology

41 Theoretical Aspect of the Modeling

411 Modeling of the PV System For each hour h in a yearthe power delivered by a PV generator 119875pv-h (W) is describedby the IV characteristic which varies with the hourly solarradiation119866h and the hourly dry temperature119879hThis is givenin algebraic form by

119868pv-h = 119891 (119881ph-h 119866h 119879h) (1)

Singer model [20 21] has been used and MATLAB-SIMULINK program was developed for this purpose

MPPT Algorithm In MPPT (maximum power point track-ing) operation the PV array produces maximum powerunder variable conditions of solar radiation and ambienttemperatureTheMPPT algorithmwhich is used in this workis the incremental conductance algorithm (IC) Conductancealgorithm is based on the differentiation of PV power and oncondition of zero slope of PV curveTheMPPTcan be trackedby comparing the incremental conductance 119889119868pv-h119889119881pv-h tothe instantaneous conductance 119868119881 Therefore the sign ofthe quantity 119889119868pv-h119889119881pv-h + 119868pv-h119881pv-h indicates the correctdirection of perturbation leading to the MPPT When MPPThas been reached the operation of the PV is held at this pointand perturbation is stopped If a change in 119889119868 is presented thealgorithm increments or decrements the 119881 to track the newMPPT the increment (or decrement) size determines how fastthe MPPT is tracked

When the optimum operation point of PV curve is to theleft of the MPPT we have 119889119868pv-h119889119881pv-h + 119868pv-h119881pv-h ≺ 0 thusa reduction in PVrsquos voltage is essential to achieve MPPT

Similarly when the optimum point is to the left ofthe MPPT we have 119889119868pv-h119889119881pv-h + 119868pv-h119881pv-h ≻ 0 thusan increase in PVrsquos voltage is essential to achieve MPPTTraditionally these changes in PVrsquos voltage may be done bycoupling a DCDC converter to PV and controlling properlyits duty cycle In the present study the used DCDC converterin MPPT is the boost due to easy way of duty cycle control[22]

Inverter In this paper the connection of PV system to the gridtakes place in one stage using a voltage source inverter InFigure 2 we can see that between the PV generator and theinverter only one capacitor exists Based on the IC algorithmwhen the output voltage of PV generator is changed theMPPT changes simultaneously For the implementation ofIC algorithm directly to the inverter the switching elementsof the inverter must be appropriately pulsed so that everymoment the voltage capacitor of the DC bus is equal to thereference voltage which is given by MPPT algorithm (VDC-ref) Therefore the algorithm brings in the capacitor voltageand the PVrsquos current as inputs and the desirable PVrsquos voltage(which is capacitors new reference voltage) as output [22]

Control and Synchronization with the Grid In all the powerconversion chains it should be noticed that the inverter

The Scientific World Journal 3

DCAC

Managementsystem

Transformer

DC BUS

Photovoltaic generator

Wind generator

Grid

Figure 1 Decentralized installation connected to the grid

C

VDC

MPPTalgorithm PWM

Park

PV array

VDC-ref

VDC-ref

Park

PI PI

WL WL

+

++

++

+

+ +

minus minus

PLL

PI

VDC IDC

Powercontrol

+

+

minus

Grid

IabcL

120579

120579

Vd

Id-refIq-ref

Iq-ref

Id-ref

Vq

Vq

Vd

Abc120572120573

A120573dq

Qref

Figure 2 Schematic diagram of a connected PV-grid [9]

output voltages must be synchronized with the distributiongrid [23] For that purpose we introduced and turned aphase locked loop (PLL) which delivers the angle 120579 = 120596119905

mandatory for the Park transformation (translation into thesynchronous frame) Figure 3 shows the block diagramof thisPLL algorithm While supplying to the load or the grid acurrent corresponding to the real power reference a swingis created between voltages and currents in order to deliver areactive power according to the command

A proportional integral controller is used to control theactive and reactive power flowing

412 Modeling of the Wind System

Wind Speed Variation with Height [24] To calculate theoutput of the wind turbine in each of the 8760 hours in a yearthe hourly values of measured wind speed in the Adrar site atthe hub height of the machine is calculated by using

Vhub-h = Vln (119911hub1199110)ln (119911data1199110)

(2)

where 119911hub is the hub height of the wind turbine (m) 119911datais the anemometer height (m) 119911

0is the surface roughness

4 The Scientific World Journal

Gridtransform transform PI

Va

VqVb

Vd

Vc

V120572

V120573 120596int 120579

Abcdq 120572120573dq

Figure 3 Transport delay-based PLL algorithm

Wound rotorinduction generator

Gear box

Batteries

Gridconnection

point

Electricity

Figure 4 Wind system block diagram

length (m) [25] and the Vhub-h is the wind speed at theanemometer height during the hour h (ms)

Dynamic Model The types of wind turbine generators mayvary from wind generator to wind generator due to differentgenerator types (asynchronous synchronous) especially thecircuitry connecting the wind generator to the three-phasegrid which can have two different forms (direct or indirectgrid connection)

In the studied case the generator has been connecteddirectly to the three-phase alternating current grid Theresulting configuration is simple and according to the litera-ture [26 27] is widely used in practice (Figure 4)

Wind Turbine Dynamics Model The mechanical powerextracted from the wind [28 29] is given by the followingrelation

119875119905=1

2120588119862119901(120582 120573)119878V3 (3)

with

119878 = 1205871198772

119905 (4)

where 119878 is the area swept by thewind inm2 120588 is the air densityequal at standard conditions 1294 kgmminus3 V is the wind speedin ms 119877

119905is the radius in m

The power coefficient 119862119901depends on the tip speed ratio

(120582) and the blade angle (120573) In the case of turbines withoutpitch control the blade angle is constant and 119862

119901values only

depend on those of 120582 the tip speed ratio being expressed asfollows

120582 =Ω119905119877119905

V (5)

Also the mechanical torque produced by the wind isexpressed in the following relation

119879119905=119875119905

Ω119905

(6)

The VESTAS 47-660 wind generator experimental poweroutput data given by themanufacturer as well as the119862

119901curve

[30] have been approximated by using a simple MATLABpolynomial interpolation available as polyfit polynomialfunction and the obtained correlations are expressed asfollows

119875 (V) = 4240 minus 4727V minus 2194V2 minus 562V3

+ 885V4minus891V5 + 0585V6

minus 00249V7 + 664 sdot 10minus4V8

119862119901(V) = 11072 minus 12698V minus 04931V2

minus 000084V3 + 00781V4 minus 427 sdot 10minus4V5

+ 137 sdot 10minus5V6 minus 244 sdot 10minus7V7 + 183 sdot 10minus9V8

(7)

Then the operation of the wind turbine system is sim-ulated using the wind turbine equations which evaluate themechanical torque (119879

119905) and requires the turbine angular

speed (Ω119905) and the wind speed (V) as data

Drive Drain Dynamics Model To evaluate the generatorspeed (Ωam) the generator torque (119879am) and the turbinetorque (1198791015840

119905) are required as data The dynamic behaviour of

the mechanical system is determined by using the classicalrotational dynamics equations The inertia is considered asconcentrated in one lumped mass including the contributionof blades generator shafts and gear box The dynamicmotion equation of the mechanical system has the followingexpression

119869119889Ωam119889119905

+ 119891VΩam = 1198791015840

119905minus 119879am (8)

The turbine torque and generator speed (1198791015840119905andΩam) and

themechanical torque and turbine speed (119879119905andΩ

119905) supplied

to the wind turbine block simulation have been linked bymeans of the gear box whose ratio is 119896 (119896 = 505) for theVESTAS 660-47 wind generator

Asynchronous Machine Dynamics Model The asynchronousmachine equations permit to calculate the electrical power

The Scientific World Journal 5

generation of the system and return the generator torque119879amthe active and reactive power The generator speed Ωas andvoltage 119881

119889119902are the required input parameters obtained by

using the Park transform block PT of the three-phase systeminto the two-phase system [31]

(a) Electric and Magnetic Equations The voltage equationsrepresenting an induction machine [29 32] in an arbitraryreference frame can bewritten in terms of the phase currentsas given by [32]

In the present model the stator and rotor voltages alongthe 119889 and 119902 axes are given by [32]

Using these last ones a model for wound rotor generatorscan be developed This latter has short circuited windingsand as a consequence rotor voltages evaluate to zero (119881

119889119903= 0

and119881119902119903= 0) in this caseTherefore the representative wound

rotor generator equations are

119904120593119889119904= 119881119889119904minus 119877119904119868119889119904+ 120596119904sdot 120593119902119904

119904120593119902119904= 119881119902119904minus 119877119904sdot 119868119902119904minus 120596119904sdot 120593119889119904

119904120593119889119903= minus119877119903sdot 119868119889119903+ (120596119904minus 120596119903) sdot 120593119902119903

119904120593119902119903= minus119877119903sdot 119868119902119903minus (120596119904minus 120596119903)119904119903sdot 120593119889119903

(9)

where

120593119889119904= 119871119904sdot 119868119889119904+ 119871119904119903sdot 119868119889119903

120593119902119904= 119871119904sdot 119868119902119904+ 119871119904119903sdot 119868119902119903

120593119889119903= 119871119903sdot 119868119889119903+ 119871119904119903sdot 119868119889119904

120593119902119903= 119871119903sdot 119868119902119903+ 119871119904119903sdot 119868119902119904

(10)

(b) Evaluation of the Electromagnetic TorqueThe electromag-netic torque has been calculated by employing (11) proposedby [29 32]

Consider

119879am = (3

2)119875 sdot 119871

119904119903(119868119904119902sdot 119868119903119902minus 119868119904119889sdot 119868119903119902) (11)

(c) Evaluation of Real and Reactive Power The active (119875)and reactive (119876) power have been calculated by using thefollowing equations

119875 = 119881

119889119904119868119889119904+ 119881119902119904119868119902119904

119876 = 119881119902119904119868119889119904minus 119881119889119904119868119902119904

(12)

119875119903= minus (119881

119889119903119868119889119903+ 119881119902119903119868119902119903)

119876119903= minus (119881

119902119903119868119889119903+ 119881119889119903119868119902119903) (13)

Using these equations a model for wound rotor gen-erators can be developed This type of generator has shortcircuited windings thus the corresponding rotor voltages goto zero (119881

119889119903= 0 119881

119902119903= 0) Taking into account these

conditions (13) give 119875119903= 0 and 119876

119903= 0

5 Simulation

The energy system components are photovoltaic moduleswind turbine grid and power converter This study developsa suitable assembly of the key parameters such as photovoltaicarray power wind turbine power curve battery storageand converter capacity to match the predefined load Foreconomic analysis the cost including the initial capitalreplacement cost and operating and maintenance cost areconsidered as simulating conditions

Photovoltaic Arrays The initial cost of photovoltaic arraysmay vary from $400 to $500 per watt Considering a moreoptimistic system the costs of installation replacement andmaintenance of a 1 kW solar energy system are taken as $5000and $4000 Sizes of the photovoltaic arrays are varied between0 100 200 300 400 500 600 and 700 kW

Wind Turbine Energy generation formwind turbine dependson wind speed variations The wind turbine rated powershould be greater than average electrical load Thereforeaccording to the load data discussed above the average loadis around a 77MW Therefore a VESTAS 47ndash660 turbinemanufactured by VESTAS wind power is used Its ratedpower is 660 kWAC

Grid Grid exists as themain power component in this hybridrenewable energy system Moreover grid has the functionsas a storage system so a grid power system does not need abattery

Power Converter A converter is required for systems inwhichDC components serve an AD load or vice versa For a 1 kWsystem the installation and replacement costs are taken as$800 and $750 respectively Lifetime of a unit is consideredto be 25 years with an efficiency of 90

For the considered system it is necessary to simulateduring all the hours in a complete year all the possibledesigns Variables are considered hourly and therefore therewill be 8760 in a year At the end of the simulation we willknow the quantity of electrical energy from a PV generatorinjected to the grid in the year and the electrical energy fromwind turbines that is also injected [24]

As a sample site the Adrar site has been chosen and thefollowing data are used as input

(i) the hourly global and diffuse radiationmeasured on ahorizontal plane and the ambient temperature Fromthe data collected on a horizontal plane the compo-nents of the solar irradiance have been projected ontothe surface of a PV panel Moreover the inclinationof the used solar panel corresponds to the yearlyoptimum slope as indicated in [33]

(ii) the measured wind speeds and the electromechanicalcharacteristics of a wind turbine of the VESTAS47ndash660 type This is a three-blade model with adiameter of 46m a speed multiplier ratio of 505and a hub height of 100m [30] Moreover the power

6 The Scientific World Journal

0 5 10 15 20 25 300

100200300400500600700

Wind speed (ms)

Pow

er o

utpu

t (kW

)

Figure 5 Typical wind turbine power curve

produced by this wind turbine has been calculatedusing the power curve (Figure 5) provided by themanufacturer

51 Power Produced by the Photovoltaic Generator For calcu-lating the output characteristics of the photovoltaic systema program has been developed which requires the globalincident radiation and the air temperature as main inputdata So the research unit in renewable energy URER ofAdrar provided hourly measured values over a full year ofglobal and diffuse irradiation on a horizontal plane togetherwith those related to the ambient temperature From theglobal radiations on the horizontal plane collected data andbased on the equations given in [21] the developed programcalculates the overall incident irradiations on the surface ofthe PV panel These latter and the ambient temperatures areused to calculate the power and current delivered by the PVgenerator

The obtained results are presented in Figure 6

52 Power Produced by the Wind Generator Generally tocalculate the power generated by a wind turbine we use thedata drawn from the main characteristic 119901 = 119891(V) related tothe turbine and supplied by the manufacturer (Figure 5) Inthis study using the equations given in [34] the hourly valuesof the wind turbine are read from a file in which the windspeed for each hour of the year is given

By using the power curve of the wind turbine the outputpower is calculated With the speed at the hub of the windturbine and using its power curve the power that the windturbine provides in an hour h Pwminush (W) is obtained If thereare 119873

119908wind turbine connected in parallel this amount is

multiplied by119873119908[24] The obtained results are as follows

(i) Figure 7(a) shows the evolution of hourly windspeeds

(ii) Figure 7(b) shows the plots of the active power devel-oped at the asynchronous machine terminals

(iii) Figure 7(c) shows the plots of the reactive powerdeveloped at the asynchronous machine terminals

(iv) Figure 7(d) shows the current delivered by the windgenerator

0 1000 2000 3000 4000 5000 6000 7000 8000 900005

101520253035404550

Time (h)

Tem

pera

ture

(∘C)

(a)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

200400600800

10001200

Time (h)

Incli

ned

glob

al

radi

atio

n (w

m2)

(b)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

20406080

100120140160180

Time (h)

Pow

er p

rodu

ced

by th

ePV

gen

erat

or (W

)

(c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

012345

Time (h)

minus5minus4minus3minus2minus1

Thre

e-ph

ase c

urre

nts p

rodu

ced

by th

e PV

gen

erat

or (A

)

(d)

Figure 6 Representation of climatic characteristics power andcurrent produced by the photovoltaic module BP SX 150 S installedon the Adrar site

53 Management of the System [24] Figure 8 presents theMATLAB-SIMULINK program diagram of the hybrid sys-tem In this system the power delivered by each of the systemdevices (PV or wind) should be managed in such a way thatthe surplus of power produced by any of them is conductedto the grid without giving rise to any phenomena leading to

The Scientific World Journal 7

0 1000 2000 3000 4000 5000 6000 7000 8000 900005

10152025

Time (h)

Win

d sp

eed

(ms

)

(a)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0

Time (h)

Activ

e pow

er (k

W)

minus6

minus5

minus4

minus3

minus2

minus1

times105

(b)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

051

152

253

354

Time (h)

Reac

tive p

ower

(kVA

)

times105

(c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0200400600800

Time (h)

Thre

e-ph

ase s

tato

r cur

rent

s (A

)

minus800

minus600

minus400

minus200

(d)

Figure 7 Simulation results

a disturbance of any of these devices These last ones dis-turbed by generating harmonics that may distort the gridwaveform flickers high frequency wave frequency fluctua-tion under voltage and over voltage

Thus for each hour of the year h the amount of electricalenergy available at the transformer connected to the grid isevaluated by [24]

119875AC-h = (119875pv-h120578INV + 119875w-h)120578TR (14)

where 120578INV is the inverter efficiency rate modeled as avariable depending on the power delivered by the inverter120578TR is the efficiency rate of the transformer connected tothe electrical grid including the losses of power in thetransmission lines 119875w-h is the power (W) generated by thewind generator within an hour time and 119875pv-h is the power(W) generated by the PV generator within an hour time

However the amount of power that can be injected eachhour into the grid 119875EE-h (W) cannot be higher than theallowed evacuation capacity at the point of connection to thegrid 119875MAX-GRID (W) [24]

119875EE-h = min (119875MAX-GRID 119875AC-h) (15)

Where 119875MAX-GRID (W) is the maximum power evacuationvalue allowed which the Algerian law fixes for 20 to 30 ofthe line thermal limit at the point of connection

The amount of energy to be injected into the grid obtainedfrom the PV generator (119875EE-PV-h) and the wind generator119875EE-w-h will be calculated as indicated by Figure 9

The results obtained in the case of the previouslydescribed scenario are represented in Figure 10 which showsthat the hourly produced power injected into the grid is lowerthan 119875MAX-GRID

54 Total Annual Production The contribution of each partof the hybrid system (PV-wind-grid) to satisfy a specificload of the 34815MWhyr is shown in Figure 11 It is to benoted that the PV generator produces only 365MWhyearand covers only 1 of the load The wind generator inturn produces 7225MWhyear which constitute nearly 21of load requirements against a covered load rate of 78(27225MWhyear) provided by the conventional electricitygrid [35]These results are explained by the fact that HOMERsoftware promotes the wind system because of itrsquos efficiencywhich is very higher than that of PV system

55 Hours of Operation Figure 12 represents the durationof the operation (in hours) of each of the renewable energyequipment of the hybrid PV-wind-Grid system It is foundthat the wind generator works over the longest time intervalwith a 48 rate of the total period followed by the PVgenerator and inverter with a rate of 26 for each

56 Economic Aspects The HOMER optimization model[24] uses relatively simple strategies based on the ones studiedby Barley et al [36] and it is able to obtain an optimal designof a hybrid system by selecting the most appropriate strategy

Thus from an economic point of view it is found thatthe system composed of a 200 kW rated PV system andthree 660 kW rated wind turbines can cover 22 of theelectrical energy demand and has a net present cost (NPC)of $177 million and a cost of energy per kilowatt hour(COE) of $0399kWh A comparative economic analysisbetween the conventional and the optimized system (PV-wind system) employing HOMER software package [35] hasbeen performed and the results are presented in Table 1From these results it is noticed that the hybrid system (PV-wind-grid) is more economical than the conventional system

8 The Scientific World Journal

Yearly day number

Yearly day number 1

Tsvtsv

09

Transform

Preflight

09Convert

-C-

In1 cem

Wind system

vvvWind velocity

Scope

Result PV

Result

In1

In2

In3

In4

PV system

GHR

Global horiz rad

In1

In2

In3

PE1

PPV1

Out1

Gestion

difHR

Diffuse horiz rad1

Iabc

AP

AP

RP

Tt

Wt

Wmas

Iabc

Isabc

Isabc

Figure 8 Management of the system

PV system priority

No

No

NoNo Yes

Yes

Yes

Yes

Ppv-h Pw-h

Ppv-h Pw-h 120578inv 120578TR

PEE-h lt PMAX-GRID

PEE-h = Ppv-h120578INV 120578TR

120578inv 120578TR = Pmax-grid

Pw-h120578TR = PMAX-GRID

PEE-w-h = PMAX-GRIDPEE-PV-h = 0 PEE-PV-h = PMAX-GRIDPw-h120578TR

PEE-PV-h = PMAX-GRID

PEE-w-h = 0

PEE-w-h = 0 PEE-w-h = 0

PEE-w-h = 0

PEE-h = PEE-PV-h + PEE-w-h

PEE-PV-h = PPV-h120578INV120578TR

PEE-w-h = Pw-h TR120578middot

Figure 9 Flowchart for calculating the amount of power to be inject into the grid

The Scientific World Journal 9

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

500

1000

1500

2000

2500

3000

Time (h)

Pow

er (k

W)

Injected power into the gridPMAX-GRID

Figure 10 Power injected into the grid

1365 MWhyr

7225 MWhyr21

27225 MWhyr78

Photovoltaic systemWind systemGrid

Figure 11 Structure of the production system (PV-wind-grid)

26

48

26

Photovoltaic systemWind systemConverter

Figure 12 Distribution of operation hours of each of the renewableenergy equipment of the hybrid PV-wind-Grid system

05 1 15 2 25 3 35 4 450

20406080

100120140

Photovoltaic systemWind system

GridConverter

106$

Figure 13 Net present cost

05 1 15 2 25 3 35 4 4502468

1012

Photovoltaic systemWind system

GridConverter

106$yr

Figure 14 Annual net cost

Table 1 Cost comparison between a standard system (grid) and ahybrid system (PV-wind-grid)

Cost Conventional systemgrid

Hybrid systemPV-wind-grid

NPC ($yr) 177714200 177090600COE ($kWh) 04 0399

Table 2 Emissions comparison between a standard system (grid)and a hybrid system (PV-wind-grid)

Pollutant Kgyr Conventional systemgrid

Hybrid systemPV-wind-grid

CO2 21965160 17199524SO2 95229 74568NO119909

46572 36467

if the price per produced kWh of the latter is set to $04kWhHowever the net present cost is calculated for a projectlifetime period of 25 years and on the basis of an interest rateof 6 Figures 13 and 14 show the details of the correspondingcosts to each of the systems and the related annual costs [37]

57 Environmental Aspects The results regarding the effectsof each system configuration that is the conventional gridand the hybrid system (PV-wind-grid) on the environmentobtained by again using HOMER software in the caseof the Adrar site are shown in Table 2 [37] In this tablethe quantities of the main gases that are harmful to theenvironment including CO

2 SO2 and NOx are presented

10 The Scientific World Journal

160

165

170

175

180

72 76 80 84 88036

037

038

039

040

041

Leve

lized

cost

of en

ergy

($k

Wh)

Levelized cost of energy versus wind speed

Wind speed (ms)

Tota

l net

pre

sent

cost

($)

Levelized cost of energyTotal net present cost

Fixed

times106

Global solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 15 The relationship between cost and wind speed

72 76 80 84 88000

005

010

015

020

025

Rene

wab

le fr

actio

n

Renewable fraction versus wind speed

Wind speed (ms)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 16 The relationship between RF and wind speed

From these results it is found that the PV-wind-grid hybridsystem produces a reduction in the carbon dioxide gassulfur dioxide and nitrogen oxide rates by respectively 2022 and 22 as compared to the quantities produced by theconventional system [37]

58 Sensitivity Results In this study sensitivity analysis wasdone to study the effects of variation in the solar irradiationand wind speed The simulation software simulates thelong-term implementation of the hybrid system based ontheir respective search size for the predefined sensitivityvalues of the componentsThe emissions renewable fractionNPC and COE are simulated based on the three sensitivityvariables wind speed (ms) solar irradiation (kWm2day)and grid electricity price ($kWh) A long-term simulationfor every possible system combination and configurationwas done for a one year period (from January 1st 2005 toDecember 31st 2005) In the present case solar irradiationis set as sensitivity variables 119866 = 35 45 5 55 572 788 kWm2day while wind speed are V = 69 7 75 78 888msMoreover the grid electricity price is also defined as asensitivity variable (119901 = 01 02 03 04 $kWh) A total of 192

72 76 80 84 8816171819202122

Wind speed (ms)

times106

CO2

emiss

ions

(kg

yr)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

CO2 emissions versus wind speed

Figure 17The relationship betweenCO2emissions andwind speed

72 76 80 84 8830405060708090

100

Wind speed (ms)SO

2em

issio

ns (k

gyr

) SO2 emissions versus wind speed

SO2 emissionsNOx emissions

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 18 The relationship between sulfur dioxide and nitrogenoxide emissions and wind speed

sensitivity cases were tried for each system configurationThesimulation timewas 23minutes and 46 seconds on a personalcomputer with Intel CORE Intel Core Duo Processor of253GHz and a RAM of 2GBThe sensitivity results in termsof solar irradiation wind speed and grid electricity priceanalyze the feasibility of each system Here the feasibilityof hybrid renewable energy system is analyzed based onemission reduction and cost saving This type of sensitivityanalysis of the systems provides information that a particularsystem would be optimal at certain sensitivity variables [19]The PV-wind system is feasible when the grid electricityprice is more than $04 kWh Under this condition the RFcan be between 021 and 022 A PV-wind system is feasiblewhen global solar irradiation is more than 572 kWhm2 perday and the grid electricity price is more expensive than$04 kWh Based on the optimization results wind energyproduction shows a bigger proportion of energy generationthan solar While the solar power occupies less than 1 of thetotal energy generation wind power occupies approximatelya quarter

Therefore the wind energy resource has more impact onthe implementation Figures 15ndash18 reflect the cost renewablefraction and emission variation dependent on the sensitivityvariable wind speed The NPC and COE of the hybrid power

The Scientific World Journal 11

system reduce when the wind speed increases from 69ms to88ms Figure 15

Simultaneously as seen in Figure 16 renewable fractionrises sharply from 0 to 16 (when wind speed increases from69 to 7ms) and then steadily increases to 24 at a slowerrate In addition as shown in Figures 17 and 18 the mainemissions of carbon dioxide sulfur dioxide and nitrogenoxide persistently decrease 22

6 Problems Encountered in DecentralizedSystems [37]

The major difficulty associated with decentralized energysources is that they generally do not participate in ancillaryservices (voltage control frequency ability to operate instandalone mode etc) This is especially true for renewableenergy sources whose power flow is unpredictable and veryvolatile The integration of decentralized energy generationinto power networks raises the following problems

(i) random and unpredictable energy production (windsolar)

(ii) lack of power-frequency control(iii) no voltage adjustment performed(iv) sensitivity to voltage dips(v) significant sensitivity to changes in primary source

(wind solar) energy levels

The failure to take part in system services makes thistype of sources behave as passive generators from theelectrical energy generation point of view The penetrationof distributed energy generation must be limited from 20 to30 of the consumed power in order to guarantee acceptablesystem stability [19]

7 Conclusion

This study is related to the technical economic and envi-ronmental impact of grid-connected decentralized systems towhich an appropriatemanagement of energy is applied andbymeans of which are developed models of the different partsThe solar and wind energy resource data are collected fromthe weather station of Adrar which is a typical arid regionThe most significant results are as follows

The power that any subsystem can deliver depends on theweather conditions of the considered site

The PV based system only covers 1 of the total loadconsumption On the other hand the wind generator con-tribution amounts to about 21 of the energy productionwhile the remaining 78 are supplied by the conventionalelectricity grid

From an economic point of view it is found that for theAdrar site which is characterized by a high wind potentialthe hybrid system is competitive compared with the conven-tional system with a cost of the energy COE produced by thenetwork equal to $04kWh since the estimated COE relatedto the hybrid system is equal to $0399kWh based on anaverage wind speed greater than or equal to 6ms

From an environmental standpoint the rates of green-house gases (CO

2 SO2 andNOx) emissions are reduced from

20 to 22 in the case of a hybrid system compared with theconventional system

The sensitivity analysis indicates that PV-wind hybridsystem is feasible under the meteorological conditions inAdrar region With the increasing wind speed the NPCCOE and emissions of the hybrid renewable energy systemreduce and renewable fraction grows up

Conflict of Interests

None of the authors of this paper has a financial or personalrelationship with other people or organisations that couldinappropriately influence or bias the content of the paper

References

[1] J Koo K Park D Shin and E S Yoon ldquoEconomic evaluationof renewable energy systems under varying scenarios and itsimplications to Korearsquos renewable energy planrdquo Applied Energyvol 88 no 6 pp 2254ndash2260 2011

[2] World Energy Outlook IEA Paris France 2008[3] KHofman andX Li ldquoCanadarsquos energy perspectives andpolicies

for sustainable developmentrdquo Applied Energy vol 86 no 4 pp407ndash415 2009

[4] H Weigt ldquoGermanyrsquos wind energy the potential for fossilcapacity replacement and cost savingrdquo Applied Energy vol 86no 10 pp 1857ndash1863 2009

[5] S A Khan R Rashmi M Z Hussain S Prasad and U CBanerjee ldquoProspects of biodiesel production from microalgaein Indiardquo Renewable and Sustainable Energy Reviews vol 13 no9 pp 2361ndash2372 2009

[6] E S Yoon ldquoA review on sustainable energy recent devel-opments and future prospects of dimethyl ether (DME)rdquo inProceedings of the 10th International Symposium on ProcessSystems Engineering (PSE rsquo09) Bahia Brazil 2009

[7] ldquoAdrar lancement des travaux du projet de la ferme eoliennerdquo2011 httpwwwalgerie360comalgerieadrar-lancement-des-travaux-du-projet-de-la-ferme-eolienne

[8] A Ducluzaux ldquoLrsquoenergie electrique drsquoorigine eoliennerdquo in Con-ference sur lrsquoEnergie Grenoble France 2004

[9] S Nguefeu M Arab X Waymel and F Costa ldquoPWM invertersin decentralized generation systems characterization of thedynamic behavior under utility fault conditionsrdquo InternationalJournal of Distributed Energy Resources vol 2 no 2 pp 101ndash1142006

[10] G Panayiotou S Kalogirou and S Tassou ldquoDesign andsimulation of a PV and a PV-Wind standalone energy systemto power a household applicationrdquo Renewable Energy vol 37no 1 pp 355ndash363 2012

[11] S M Shaahid ldquoReview of research on autonomous wind farmsand solar parks and their feasibility for commercial loads in hotregionsrdquo Renewable and Sustainable Energy Reviews vol 15 no8 pp 3877ndash3887 2011

[12] M A Elhadidy and S M Shaahid ldquoParametric study of hybrid(wind + solar + diesel) power generating systemsrdquo RenewableEnergy vol 21 no 2 pp 129ndash139 2000

12 The Scientific World Journal

[13] S M Shaahid and M A Elhadidy ldquoTechnical and economicassessment of grid-independent hybrid photovoltaic-diesel-battery power systems for commercial loads in desert environ-mentsrdquo Renewable and Sustainable Energy Reviews vol 11 no8 pp 1794ndash1810 2007

[14] D Saheb-Koussa M Haddadi and M Belhamel ldquoEconomicand technical study of a hybrid system (wind-photovoltaic-diesel) for rural electrification in Algeriardquo Applied Energy vol86 no 7-8 pp 1024ndash1030 2009

[15] G J Dalton D A Lockington and T E Baldock ldquoFeasibilityanalysis of stand-alone renewable energy supply options for alarge hotelrdquo Renewable Energy vol 33 no 7 pp 1475ndash14902008

[16] ANCelik ldquoPresent status of photovoltaic energy inTurkey andlife cycle techno-economic analysis of a grid-connected pho-tovoltaic-houserdquo Renewable and Sustainable Energy Reviewsvol 10 no 4 pp 370ndash387 2006

[17] M A H Mondal and M Denich ldquoAssessment of renew-able energy resources potential for electricity generation inBangladeshrdquoRenewable and Sustainable Energy Reviews vol 14no 7 pp 2401ndash2413 2010

[18] D Saheb-Koussa M Haddadi M Belhamel S Hadji and SNouredine ldquoModeling and simulation of the fixed-speedWECS(wind energy conversion system) application to the AlgerianSahara areardquo Energy vol 35 no 10 pp 4116ndash4125 2010

[19] S Rehman I M El-Amin F Ahmad et al ldquoFeasibility studyof hybrid retrofits to an isolated off-grid diesel power plantrdquoRenewable and Sustainable Energy Reviews vol 11 no 4 pp635ndash653 2007

[20] S Singer B Rozenshtein and S Surazi ldquoCharacterization of PVarray output using a small number of measured parametersrdquoSolar Energy vol 32 no 5 pp 603ndash607 1984

[21] D Saheb-Koussa ldquoContribution a lrsquoetude theorique du com-portement drsquoun systeme hybride (eolien- photovoltaıque-diesel) de production drsquoelectricite sans interruptionrdquo Memoirede magister Blida Septembre 2005

[22] G Tsengenes and G Adamidis ldquoInvestigation of the behaviorof a three phase grid-connected photovoltaic system to controlactive and reactive powerrdquo Electric Power Systems Research vol81 no 1 pp 177ndash184 2011

[23] S-K Chung ldquoA phase tracking system for three phase utilityinterface invertersrdquo IEEE Transactions on Power Electronics vol15 no 3 pp 431ndash438 2000

[24] R Dufo-Lopez J L Bernal-Agustın and F Mendoza ldquoDesignand economical analysis of hybrid PV-wind systems connectedto the grid for the intermittent production of hydrogenrdquo EnergyPolicy vol 37 no 8 pp 3082ndash3095 2009

[25] T Burton D Sharpe N Jenkins and E BossanyiWind EnergyHandbook John Wiley amp Sons West Sussex UK 2001

[26] Union for Coordination of Transmission of Electricity ldquoWindPower in the UCTE interconnected Systemrdquo November2004 httpswwwentsoeeufileadminuser upload librarypublicationsceotherreportsWind Power 20041125pdf

[27] E Spooner and A C Williamson ldquoDirect coupled permanentmagnet generators for wind turbine applicationsrdquo IEE Proceed-ings Electric Power Applications vol 143 no 1 pp 1ndash8 1996

[28] N Laverdure S Bacha D Roye B Raison and F DumasldquoElements of modelling of wind power systems with energymanagement two structures in comparisonrdquo in Proceedings ofthe 28th IEEE Annual Conference of the Industrial ElectronicsSociety vol 2 pp 1083ndash1088 November 2002

[29] L Krichen B Francois and A Ouali ldquoA fuzzy logic supervisorfor active and reactive power control of a fixed speed windenergy conversion systemrdquo Electric Power Systems Research vol78 no 3 pp 418ndash424 2008

[30] The Cres Wind Farm ldquo301 MW Demonstration wind farmin Greece Various wind energy technologies in complex Ter-rain topographyrdquo httpwwwcreswindfarmgrsite1ArticlesV47 USpdf

[31] T AckermannWind Power in Power Systems Royal Institute ofTechnology John Wiley amp Sons Stockholm Sweden 2005

[32] F Poitiers Asynchronous generator study and control for thewind energy use [PhD thesis] University of Nantes NantesFrance 2003

[33] M Kacira M Simsek Y Babur and S Demirkol ldquoDeterminingoptimum tilt angles and orientations of photovoltaic panels inSanliurfa Turkeyrdquo Renewable Energy vol 29 no 8 pp 1265ndash1275 2004

[34] D Saheb-Koussa M Belhamel and K Benferhat ldquoContribu-tion a lrsquoetude theorique du comportement drsquoun systeme hybride(eolien- photovoltaıque- diesel) de production drsquoelectricite sansinterruptionrdquo Afrique Science vol 5 no 1 2009

[35] HOMERmdashGetting Started Guide for HOMER Version 21National Renewable Energy Laboratory US Department ofEnergyOffice of EnergyEfficiency andRenewable Energy 2005

[36] C D Barley C B Winn L Flowers and H J Green ldquoOptimalcontrol of remote hybrid power systemsmdashpart I simplifiedmodelrdquo in Proceedings of National Avian-Wind Power PlanningMeeting Washington DC USA 1995

[37] D Saheb-Koussa ldquoEtude technique economique et environ-nementale des systemes decentralises connectes au reseauelectriquerdquo Bulletin des Energies Renouvelables vol 23 pp 15ndash17 2012

[38] V Courtecuisse Supervision drsquoune centrale multi sources a basedrsquoeoliennes et de stockage drsquoenergie connectee au reseau electrique[These de doctorat] Ecole Nationale des Arts et Metiers 2008

TribologyAdvances in

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International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Industrial EngineeringJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Renewable Energy

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StructuresJournal of

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear InstallationsScience and Technology of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Solar EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Wind EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear EnergyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

2 The Scientific World Journal

2 Presentation of the DifferentSystems of Distributed Generation fromRenewable Energy

Standalone Systems For standalone installations the energyproduced employing photovoltaic solar panels or wind gener-ators is either immediately consumed (pumping ventilationlighting refrigerator etc) or stored in batteries for later useThe produced current is either directly fed to the consumingequipment or converted using an inverter to supply devicesthat require AC power [10 11]

Multisource Hybrid Systems These systems supply electricitythat is often used at remote sites and are built couplingdifferent sources of production of electrical energy such aswind solar and othersThey also allow amore reliable supplyof electricity Nearly two billion people are not connectedto the utility grid (44 of the world population) Thusthe development of hybrid systems for renewable energyconversion will undoubtedly help to solve many socialproblems especially in poor countries and open up vastcommercial markets [10 12ndash15]

Distributed Systems Connected to the Grid These are usuallymedium and large systems which are grid connected [16ndash19]and which in general produce electrical energy amountsdepending on sunshine and wind conditions (Figure 1)

3 Characteristics of the PV-WindSystems Considered

The architecture presented in Figure 1 is the one upon whichthis paper is based With this type of PV-wind system for thegeneration of electrical energy the objective is to inject intothe grid the energy thus generated

For the design the power production of the differentsources becomes freely controllablewithout affecting the statevalues of the grid Decoupling the state values means that thevariations of the renewable resources like the velocity of thewind and the intensity of the solar radiationwill not influencethe state values of the electrical grid as the harmonicsgeneration flickers frequency fluctuation under voltage andover voltage These values are only controlled by the inverterfor the photovoltaic generator and by the microprocessor-controlledOptiTip pitch regulation ensuring continuous andoptimal adjustment of the angles of the blades in relation tothe prevailing wind for the wind generator On the otherhand changes in the loads which influence the state valuesof the grid will not affect the generation side

A controlmanagement strategy is developed for thisarchitecture to operate it in the highest efficient way Theefficiency here means the most utilization of the renewableenergy sources in order to minimize the cost of the producedenergy while preserving the reliability of the system

4 Methodology

41 Theoretical Aspect of the Modeling

411 Modeling of the PV System For each hour h in a yearthe power delivered by a PV generator 119875pv-h (W) is describedby the IV characteristic which varies with the hourly solarradiation119866h and the hourly dry temperature119879hThis is givenin algebraic form by

119868pv-h = 119891 (119881ph-h 119866h 119879h) (1)

Singer model [20 21] has been used and MATLAB-SIMULINK program was developed for this purpose

MPPT Algorithm In MPPT (maximum power point track-ing) operation the PV array produces maximum powerunder variable conditions of solar radiation and ambienttemperatureTheMPPT algorithmwhich is used in this workis the incremental conductance algorithm (IC) Conductancealgorithm is based on the differentiation of PV power and oncondition of zero slope of PV curveTheMPPTcan be trackedby comparing the incremental conductance 119889119868pv-h119889119881pv-h tothe instantaneous conductance 119868119881 Therefore the sign ofthe quantity 119889119868pv-h119889119881pv-h + 119868pv-h119881pv-h indicates the correctdirection of perturbation leading to the MPPT When MPPThas been reached the operation of the PV is held at this pointand perturbation is stopped If a change in 119889119868 is presented thealgorithm increments or decrements the 119881 to track the newMPPT the increment (or decrement) size determines how fastthe MPPT is tracked

When the optimum operation point of PV curve is to theleft of the MPPT we have 119889119868pv-h119889119881pv-h + 119868pv-h119881pv-h ≺ 0 thusa reduction in PVrsquos voltage is essential to achieve MPPT

Similarly when the optimum point is to the left ofthe MPPT we have 119889119868pv-h119889119881pv-h + 119868pv-h119881pv-h ≻ 0 thusan increase in PVrsquos voltage is essential to achieve MPPTTraditionally these changes in PVrsquos voltage may be done bycoupling a DCDC converter to PV and controlling properlyits duty cycle In the present study the used DCDC converterin MPPT is the boost due to easy way of duty cycle control[22]

Inverter In this paper the connection of PV system to the gridtakes place in one stage using a voltage source inverter InFigure 2 we can see that between the PV generator and theinverter only one capacitor exists Based on the IC algorithmwhen the output voltage of PV generator is changed theMPPT changes simultaneously For the implementation ofIC algorithm directly to the inverter the switching elementsof the inverter must be appropriately pulsed so that everymoment the voltage capacitor of the DC bus is equal to thereference voltage which is given by MPPT algorithm (VDC-ref) Therefore the algorithm brings in the capacitor voltageand the PVrsquos current as inputs and the desirable PVrsquos voltage(which is capacitors new reference voltage) as output [22]

Control and Synchronization with the Grid In all the powerconversion chains it should be noticed that the inverter

The Scientific World Journal 3

DCAC

Managementsystem

Transformer

DC BUS

Photovoltaic generator

Wind generator

Grid

Figure 1 Decentralized installation connected to the grid

C

VDC

MPPTalgorithm PWM

Park

PV array

VDC-ref

VDC-ref

Park

PI PI

WL WL

+

++

++

+

+ +

minus minus

PLL

PI

VDC IDC

Powercontrol

+

+

minus

Grid

IabcL

120579

120579

Vd

Id-refIq-ref

Iq-ref

Id-ref

Vq

Vq

Vd

Abc120572120573

A120573dq

Qref

Figure 2 Schematic diagram of a connected PV-grid [9]

output voltages must be synchronized with the distributiongrid [23] For that purpose we introduced and turned aphase locked loop (PLL) which delivers the angle 120579 = 120596119905

mandatory for the Park transformation (translation into thesynchronous frame) Figure 3 shows the block diagramof thisPLL algorithm While supplying to the load or the grid acurrent corresponding to the real power reference a swingis created between voltages and currents in order to deliver areactive power according to the command

A proportional integral controller is used to control theactive and reactive power flowing

412 Modeling of the Wind System

Wind Speed Variation with Height [24] To calculate theoutput of the wind turbine in each of the 8760 hours in a yearthe hourly values of measured wind speed in the Adrar site atthe hub height of the machine is calculated by using

Vhub-h = Vln (119911hub1199110)ln (119911data1199110)

(2)

where 119911hub is the hub height of the wind turbine (m) 119911datais the anemometer height (m) 119911

0is the surface roughness

4 The Scientific World Journal

Gridtransform transform PI

Va

VqVb

Vd

Vc

V120572

V120573 120596int 120579

Abcdq 120572120573dq

Figure 3 Transport delay-based PLL algorithm

Wound rotorinduction generator

Gear box

Batteries

Gridconnection

point

Electricity

Figure 4 Wind system block diagram

length (m) [25] and the Vhub-h is the wind speed at theanemometer height during the hour h (ms)

Dynamic Model The types of wind turbine generators mayvary from wind generator to wind generator due to differentgenerator types (asynchronous synchronous) especially thecircuitry connecting the wind generator to the three-phasegrid which can have two different forms (direct or indirectgrid connection)

In the studied case the generator has been connecteddirectly to the three-phase alternating current grid Theresulting configuration is simple and according to the litera-ture [26 27] is widely used in practice (Figure 4)

Wind Turbine Dynamics Model The mechanical powerextracted from the wind [28 29] is given by the followingrelation

119875119905=1

2120588119862119901(120582 120573)119878V3 (3)

with

119878 = 1205871198772

119905 (4)

where 119878 is the area swept by thewind inm2 120588 is the air densityequal at standard conditions 1294 kgmminus3 V is the wind speedin ms 119877

119905is the radius in m

The power coefficient 119862119901depends on the tip speed ratio

(120582) and the blade angle (120573) In the case of turbines withoutpitch control the blade angle is constant and 119862

119901values only

depend on those of 120582 the tip speed ratio being expressed asfollows

120582 =Ω119905119877119905

V (5)

Also the mechanical torque produced by the wind isexpressed in the following relation

119879119905=119875119905

Ω119905

(6)

The VESTAS 47-660 wind generator experimental poweroutput data given by themanufacturer as well as the119862

119901curve

[30] have been approximated by using a simple MATLABpolynomial interpolation available as polyfit polynomialfunction and the obtained correlations are expressed asfollows

119875 (V) = 4240 minus 4727V minus 2194V2 minus 562V3

+ 885V4minus891V5 + 0585V6

minus 00249V7 + 664 sdot 10minus4V8

119862119901(V) = 11072 minus 12698V minus 04931V2

minus 000084V3 + 00781V4 minus 427 sdot 10minus4V5

+ 137 sdot 10minus5V6 minus 244 sdot 10minus7V7 + 183 sdot 10minus9V8

(7)

Then the operation of the wind turbine system is sim-ulated using the wind turbine equations which evaluate themechanical torque (119879

119905) and requires the turbine angular

speed (Ω119905) and the wind speed (V) as data

Drive Drain Dynamics Model To evaluate the generatorspeed (Ωam) the generator torque (119879am) and the turbinetorque (1198791015840

119905) are required as data The dynamic behaviour of

the mechanical system is determined by using the classicalrotational dynamics equations The inertia is considered asconcentrated in one lumped mass including the contributionof blades generator shafts and gear box The dynamicmotion equation of the mechanical system has the followingexpression

119869119889Ωam119889119905

+ 119891VΩam = 1198791015840

119905minus 119879am (8)

The turbine torque and generator speed (1198791015840119905andΩam) and

themechanical torque and turbine speed (119879119905andΩ

119905) supplied

to the wind turbine block simulation have been linked bymeans of the gear box whose ratio is 119896 (119896 = 505) for theVESTAS 660-47 wind generator

Asynchronous Machine Dynamics Model The asynchronousmachine equations permit to calculate the electrical power

The Scientific World Journal 5

generation of the system and return the generator torque119879amthe active and reactive power The generator speed Ωas andvoltage 119881

119889119902are the required input parameters obtained by

using the Park transform block PT of the three-phase systeminto the two-phase system [31]

(a) Electric and Magnetic Equations The voltage equationsrepresenting an induction machine [29 32] in an arbitraryreference frame can bewritten in terms of the phase currentsas given by [32]

In the present model the stator and rotor voltages alongthe 119889 and 119902 axes are given by [32]

Using these last ones a model for wound rotor generatorscan be developed This latter has short circuited windingsand as a consequence rotor voltages evaluate to zero (119881

119889119903= 0

and119881119902119903= 0) in this caseTherefore the representative wound

rotor generator equations are

119904120593119889119904= 119881119889119904minus 119877119904119868119889119904+ 120596119904sdot 120593119902119904

119904120593119902119904= 119881119902119904minus 119877119904sdot 119868119902119904minus 120596119904sdot 120593119889119904

119904120593119889119903= minus119877119903sdot 119868119889119903+ (120596119904minus 120596119903) sdot 120593119902119903

119904120593119902119903= minus119877119903sdot 119868119902119903minus (120596119904minus 120596119903)119904119903sdot 120593119889119903

(9)

where

120593119889119904= 119871119904sdot 119868119889119904+ 119871119904119903sdot 119868119889119903

120593119902119904= 119871119904sdot 119868119902119904+ 119871119904119903sdot 119868119902119903

120593119889119903= 119871119903sdot 119868119889119903+ 119871119904119903sdot 119868119889119904

120593119902119903= 119871119903sdot 119868119902119903+ 119871119904119903sdot 119868119902119904

(10)

(b) Evaluation of the Electromagnetic TorqueThe electromag-netic torque has been calculated by employing (11) proposedby [29 32]

Consider

119879am = (3

2)119875 sdot 119871

119904119903(119868119904119902sdot 119868119903119902minus 119868119904119889sdot 119868119903119902) (11)

(c) Evaluation of Real and Reactive Power The active (119875)and reactive (119876) power have been calculated by using thefollowing equations

119875 = 119881

119889119904119868119889119904+ 119881119902119904119868119902119904

119876 = 119881119902119904119868119889119904minus 119881119889119904119868119902119904

(12)

119875119903= minus (119881

119889119903119868119889119903+ 119881119902119903119868119902119903)

119876119903= minus (119881

119902119903119868119889119903+ 119881119889119903119868119902119903) (13)

Using these equations a model for wound rotor gen-erators can be developed This type of generator has shortcircuited windings thus the corresponding rotor voltages goto zero (119881

119889119903= 0 119881

119902119903= 0) Taking into account these

conditions (13) give 119875119903= 0 and 119876

119903= 0

5 Simulation

The energy system components are photovoltaic moduleswind turbine grid and power converter This study developsa suitable assembly of the key parameters such as photovoltaicarray power wind turbine power curve battery storageand converter capacity to match the predefined load Foreconomic analysis the cost including the initial capitalreplacement cost and operating and maintenance cost areconsidered as simulating conditions

Photovoltaic Arrays The initial cost of photovoltaic arraysmay vary from $400 to $500 per watt Considering a moreoptimistic system the costs of installation replacement andmaintenance of a 1 kW solar energy system are taken as $5000and $4000 Sizes of the photovoltaic arrays are varied between0 100 200 300 400 500 600 and 700 kW

Wind Turbine Energy generation formwind turbine dependson wind speed variations The wind turbine rated powershould be greater than average electrical load Thereforeaccording to the load data discussed above the average loadis around a 77MW Therefore a VESTAS 47ndash660 turbinemanufactured by VESTAS wind power is used Its ratedpower is 660 kWAC

Grid Grid exists as themain power component in this hybridrenewable energy system Moreover grid has the functionsas a storage system so a grid power system does not need abattery

Power Converter A converter is required for systems inwhichDC components serve an AD load or vice versa For a 1 kWsystem the installation and replacement costs are taken as$800 and $750 respectively Lifetime of a unit is consideredto be 25 years with an efficiency of 90

For the considered system it is necessary to simulateduring all the hours in a complete year all the possibledesigns Variables are considered hourly and therefore therewill be 8760 in a year At the end of the simulation we willknow the quantity of electrical energy from a PV generatorinjected to the grid in the year and the electrical energy fromwind turbines that is also injected [24]

As a sample site the Adrar site has been chosen and thefollowing data are used as input

(i) the hourly global and diffuse radiationmeasured on ahorizontal plane and the ambient temperature Fromthe data collected on a horizontal plane the compo-nents of the solar irradiance have been projected ontothe surface of a PV panel Moreover the inclinationof the used solar panel corresponds to the yearlyoptimum slope as indicated in [33]

(ii) the measured wind speeds and the electromechanicalcharacteristics of a wind turbine of the VESTAS47ndash660 type This is a three-blade model with adiameter of 46m a speed multiplier ratio of 505and a hub height of 100m [30] Moreover the power

6 The Scientific World Journal

0 5 10 15 20 25 300

100200300400500600700

Wind speed (ms)

Pow

er o

utpu

t (kW

)

Figure 5 Typical wind turbine power curve

produced by this wind turbine has been calculatedusing the power curve (Figure 5) provided by themanufacturer

51 Power Produced by the Photovoltaic Generator For calcu-lating the output characteristics of the photovoltaic systema program has been developed which requires the globalincident radiation and the air temperature as main inputdata So the research unit in renewable energy URER ofAdrar provided hourly measured values over a full year ofglobal and diffuse irradiation on a horizontal plane togetherwith those related to the ambient temperature From theglobal radiations on the horizontal plane collected data andbased on the equations given in [21] the developed programcalculates the overall incident irradiations on the surface ofthe PV panel These latter and the ambient temperatures areused to calculate the power and current delivered by the PVgenerator

The obtained results are presented in Figure 6

52 Power Produced by the Wind Generator Generally tocalculate the power generated by a wind turbine we use thedata drawn from the main characteristic 119901 = 119891(V) related tothe turbine and supplied by the manufacturer (Figure 5) Inthis study using the equations given in [34] the hourly valuesof the wind turbine are read from a file in which the windspeed for each hour of the year is given

By using the power curve of the wind turbine the outputpower is calculated With the speed at the hub of the windturbine and using its power curve the power that the windturbine provides in an hour h Pwminush (W) is obtained If thereare 119873

119908wind turbine connected in parallel this amount is

multiplied by119873119908[24] The obtained results are as follows

(i) Figure 7(a) shows the evolution of hourly windspeeds

(ii) Figure 7(b) shows the plots of the active power devel-oped at the asynchronous machine terminals

(iii) Figure 7(c) shows the plots of the reactive powerdeveloped at the asynchronous machine terminals

(iv) Figure 7(d) shows the current delivered by the windgenerator

0 1000 2000 3000 4000 5000 6000 7000 8000 900005

101520253035404550

Time (h)

Tem

pera

ture

(∘C)

(a)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

200400600800

10001200

Time (h)

Incli

ned

glob

al

radi

atio

n (w

m2)

(b)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

20406080

100120140160180

Time (h)

Pow

er p

rodu

ced

by th

ePV

gen

erat

or (W

)

(c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

012345

Time (h)

minus5minus4minus3minus2minus1

Thre

e-ph

ase c

urre

nts p

rodu

ced

by th

e PV

gen

erat

or (A

)

(d)

Figure 6 Representation of climatic characteristics power andcurrent produced by the photovoltaic module BP SX 150 S installedon the Adrar site

53 Management of the System [24] Figure 8 presents theMATLAB-SIMULINK program diagram of the hybrid sys-tem In this system the power delivered by each of the systemdevices (PV or wind) should be managed in such a way thatthe surplus of power produced by any of them is conductedto the grid without giving rise to any phenomena leading to

The Scientific World Journal 7

0 1000 2000 3000 4000 5000 6000 7000 8000 900005

10152025

Time (h)

Win

d sp

eed

(ms

)

(a)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0

Time (h)

Activ

e pow

er (k

W)

minus6

minus5

minus4

minus3

minus2

minus1

times105

(b)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

051

152

253

354

Time (h)

Reac

tive p

ower

(kVA

)

times105

(c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0200400600800

Time (h)

Thre

e-ph

ase s

tato

r cur

rent

s (A

)

minus800

minus600

minus400

minus200

(d)

Figure 7 Simulation results

a disturbance of any of these devices These last ones dis-turbed by generating harmonics that may distort the gridwaveform flickers high frequency wave frequency fluctua-tion under voltage and over voltage

Thus for each hour of the year h the amount of electricalenergy available at the transformer connected to the grid isevaluated by [24]

119875AC-h = (119875pv-h120578INV + 119875w-h)120578TR (14)

where 120578INV is the inverter efficiency rate modeled as avariable depending on the power delivered by the inverter120578TR is the efficiency rate of the transformer connected tothe electrical grid including the losses of power in thetransmission lines 119875w-h is the power (W) generated by thewind generator within an hour time and 119875pv-h is the power(W) generated by the PV generator within an hour time

However the amount of power that can be injected eachhour into the grid 119875EE-h (W) cannot be higher than theallowed evacuation capacity at the point of connection to thegrid 119875MAX-GRID (W) [24]

119875EE-h = min (119875MAX-GRID 119875AC-h) (15)

Where 119875MAX-GRID (W) is the maximum power evacuationvalue allowed which the Algerian law fixes for 20 to 30 ofthe line thermal limit at the point of connection

The amount of energy to be injected into the grid obtainedfrom the PV generator (119875EE-PV-h) and the wind generator119875EE-w-h will be calculated as indicated by Figure 9

The results obtained in the case of the previouslydescribed scenario are represented in Figure 10 which showsthat the hourly produced power injected into the grid is lowerthan 119875MAX-GRID

54 Total Annual Production The contribution of each partof the hybrid system (PV-wind-grid) to satisfy a specificload of the 34815MWhyr is shown in Figure 11 It is to benoted that the PV generator produces only 365MWhyearand covers only 1 of the load The wind generator inturn produces 7225MWhyear which constitute nearly 21of load requirements against a covered load rate of 78(27225MWhyear) provided by the conventional electricitygrid [35]These results are explained by the fact that HOMERsoftware promotes the wind system because of itrsquos efficiencywhich is very higher than that of PV system

55 Hours of Operation Figure 12 represents the durationof the operation (in hours) of each of the renewable energyequipment of the hybrid PV-wind-Grid system It is foundthat the wind generator works over the longest time intervalwith a 48 rate of the total period followed by the PVgenerator and inverter with a rate of 26 for each

56 Economic Aspects The HOMER optimization model[24] uses relatively simple strategies based on the ones studiedby Barley et al [36] and it is able to obtain an optimal designof a hybrid system by selecting the most appropriate strategy

Thus from an economic point of view it is found thatthe system composed of a 200 kW rated PV system andthree 660 kW rated wind turbines can cover 22 of theelectrical energy demand and has a net present cost (NPC)of $177 million and a cost of energy per kilowatt hour(COE) of $0399kWh A comparative economic analysisbetween the conventional and the optimized system (PV-wind system) employing HOMER software package [35] hasbeen performed and the results are presented in Table 1From these results it is noticed that the hybrid system (PV-wind-grid) is more economical than the conventional system

8 The Scientific World Journal

Yearly day number

Yearly day number 1

Tsvtsv

09

Transform

Preflight

09Convert

-C-

In1 cem

Wind system

vvvWind velocity

Scope

Result PV

Result

In1

In2

In3

In4

PV system

GHR

Global horiz rad

In1

In2

In3

PE1

PPV1

Out1

Gestion

difHR

Diffuse horiz rad1

Iabc

AP

AP

RP

Tt

Wt

Wmas

Iabc

Isabc

Isabc

Figure 8 Management of the system

PV system priority

No

No

NoNo Yes

Yes

Yes

Yes

Ppv-h Pw-h

Ppv-h Pw-h 120578inv 120578TR

PEE-h lt PMAX-GRID

PEE-h = Ppv-h120578INV 120578TR

120578inv 120578TR = Pmax-grid

Pw-h120578TR = PMAX-GRID

PEE-w-h = PMAX-GRIDPEE-PV-h = 0 PEE-PV-h = PMAX-GRIDPw-h120578TR

PEE-PV-h = PMAX-GRID

PEE-w-h = 0

PEE-w-h = 0 PEE-w-h = 0

PEE-w-h = 0

PEE-h = PEE-PV-h + PEE-w-h

PEE-PV-h = PPV-h120578INV120578TR

PEE-w-h = Pw-h TR120578middot

Figure 9 Flowchart for calculating the amount of power to be inject into the grid

The Scientific World Journal 9

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

500

1000

1500

2000

2500

3000

Time (h)

Pow

er (k

W)

Injected power into the gridPMAX-GRID

Figure 10 Power injected into the grid

1365 MWhyr

7225 MWhyr21

27225 MWhyr78

Photovoltaic systemWind systemGrid

Figure 11 Structure of the production system (PV-wind-grid)

26

48

26

Photovoltaic systemWind systemConverter

Figure 12 Distribution of operation hours of each of the renewableenergy equipment of the hybrid PV-wind-Grid system

05 1 15 2 25 3 35 4 450

20406080

100120140

Photovoltaic systemWind system

GridConverter

106$

Figure 13 Net present cost

05 1 15 2 25 3 35 4 4502468

1012

Photovoltaic systemWind system

GridConverter

106$yr

Figure 14 Annual net cost

Table 1 Cost comparison between a standard system (grid) and ahybrid system (PV-wind-grid)

Cost Conventional systemgrid

Hybrid systemPV-wind-grid

NPC ($yr) 177714200 177090600COE ($kWh) 04 0399

Table 2 Emissions comparison between a standard system (grid)and a hybrid system (PV-wind-grid)

Pollutant Kgyr Conventional systemgrid

Hybrid systemPV-wind-grid

CO2 21965160 17199524SO2 95229 74568NO119909

46572 36467

if the price per produced kWh of the latter is set to $04kWhHowever the net present cost is calculated for a projectlifetime period of 25 years and on the basis of an interest rateof 6 Figures 13 and 14 show the details of the correspondingcosts to each of the systems and the related annual costs [37]

57 Environmental Aspects The results regarding the effectsof each system configuration that is the conventional gridand the hybrid system (PV-wind-grid) on the environmentobtained by again using HOMER software in the caseof the Adrar site are shown in Table 2 [37] In this tablethe quantities of the main gases that are harmful to theenvironment including CO

2 SO2 and NOx are presented

10 The Scientific World Journal

160

165

170

175

180

72 76 80 84 88036

037

038

039

040

041

Leve

lized

cost

of en

ergy

($k

Wh)

Levelized cost of energy versus wind speed

Wind speed (ms)

Tota

l net

pre

sent

cost

($)

Levelized cost of energyTotal net present cost

Fixed

times106

Global solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 15 The relationship between cost and wind speed

72 76 80 84 88000

005

010

015

020

025

Rene

wab

le fr

actio

n

Renewable fraction versus wind speed

Wind speed (ms)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 16 The relationship between RF and wind speed

From these results it is found that the PV-wind-grid hybridsystem produces a reduction in the carbon dioxide gassulfur dioxide and nitrogen oxide rates by respectively 2022 and 22 as compared to the quantities produced by theconventional system [37]

58 Sensitivity Results In this study sensitivity analysis wasdone to study the effects of variation in the solar irradiationand wind speed The simulation software simulates thelong-term implementation of the hybrid system based ontheir respective search size for the predefined sensitivityvalues of the componentsThe emissions renewable fractionNPC and COE are simulated based on the three sensitivityvariables wind speed (ms) solar irradiation (kWm2day)and grid electricity price ($kWh) A long-term simulationfor every possible system combination and configurationwas done for a one year period (from January 1st 2005 toDecember 31st 2005) In the present case solar irradiationis set as sensitivity variables 119866 = 35 45 5 55 572 788 kWm2day while wind speed are V = 69 7 75 78 888msMoreover the grid electricity price is also defined as asensitivity variable (119901 = 01 02 03 04 $kWh) A total of 192

72 76 80 84 8816171819202122

Wind speed (ms)

times106

CO2

emiss

ions

(kg

yr)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

CO2 emissions versus wind speed

Figure 17The relationship betweenCO2emissions andwind speed

72 76 80 84 8830405060708090

100

Wind speed (ms)SO

2em

issio

ns (k

gyr

) SO2 emissions versus wind speed

SO2 emissionsNOx emissions

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 18 The relationship between sulfur dioxide and nitrogenoxide emissions and wind speed

sensitivity cases were tried for each system configurationThesimulation timewas 23minutes and 46 seconds on a personalcomputer with Intel CORE Intel Core Duo Processor of253GHz and a RAM of 2GBThe sensitivity results in termsof solar irradiation wind speed and grid electricity priceanalyze the feasibility of each system Here the feasibilityof hybrid renewable energy system is analyzed based onemission reduction and cost saving This type of sensitivityanalysis of the systems provides information that a particularsystem would be optimal at certain sensitivity variables [19]The PV-wind system is feasible when the grid electricityprice is more than $04 kWh Under this condition the RFcan be between 021 and 022 A PV-wind system is feasiblewhen global solar irradiation is more than 572 kWhm2 perday and the grid electricity price is more expensive than$04 kWh Based on the optimization results wind energyproduction shows a bigger proportion of energy generationthan solar While the solar power occupies less than 1 of thetotal energy generation wind power occupies approximatelya quarter

Therefore the wind energy resource has more impact onthe implementation Figures 15ndash18 reflect the cost renewablefraction and emission variation dependent on the sensitivityvariable wind speed The NPC and COE of the hybrid power

The Scientific World Journal 11

system reduce when the wind speed increases from 69ms to88ms Figure 15

Simultaneously as seen in Figure 16 renewable fractionrises sharply from 0 to 16 (when wind speed increases from69 to 7ms) and then steadily increases to 24 at a slowerrate In addition as shown in Figures 17 and 18 the mainemissions of carbon dioxide sulfur dioxide and nitrogenoxide persistently decrease 22

6 Problems Encountered in DecentralizedSystems [37]

The major difficulty associated with decentralized energysources is that they generally do not participate in ancillaryservices (voltage control frequency ability to operate instandalone mode etc) This is especially true for renewableenergy sources whose power flow is unpredictable and veryvolatile The integration of decentralized energy generationinto power networks raises the following problems

(i) random and unpredictable energy production (windsolar)

(ii) lack of power-frequency control(iii) no voltage adjustment performed(iv) sensitivity to voltage dips(v) significant sensitivity to changes in primary source

(wind solar) energy levels

The failure to take part in system services makes thistype of sources behave as passive generators from theelectrical energy generation point of view The penetrationof distributed energy generation must be limited from 20 to30 of the consumed power in order to guarantee acceptablesystem stability [19]

7 Conclusion

This study is related to the technical economic and envi-ronmental impact of grid-connected decentralized systems towhich an appropriatemanagement of energy is applied andbymeans of which are developed models of the different partsThe solar and wind energy resource data are collected fromthe weather station of Adrar which is a typical arid regionThe most significant results are as follows

The power that any subsystem can deliver depends on theweather conditions of the considered site

The PV based system only covers 1 of the total loadconsumption On the other hand the wind generator con-tribution amounts to about 21 of the energy productionwhile the remaining 78 are supplied by the conventionalelectricity grid

From an economic point of view it is found that for theAdrar site which is characterized by a high wind potentialthe hybrid system is competitive compared with the conven-tional system with a cost of the energy COE produced by thenetwork equal to $04kWh since the estimated COE relatedto the hybrid system is equal to $0399kWh based on anaverage wind speed greater than or equal to 6ms

From an environmental standpoint the rates of green-house gases (CO

2 SO2 andNOx) emissions are reduced from

20 to 22 in the case of a hybrid system compared with theconventional system

The sensitivity analysis indicates that PV-wind hybridsystem is feasible under the meteorological conditions inAdrar region With the increasing wind speed the NPCCOE and emissions of the hybrid renewable energy systemreduce and renewable fraction grows up

Conflict of Interests

None of the authors of this paper has a financial or personalrelationship with other people or organisations that couldinappropriately influence or bias the content of the paper

References

[1] J Koo K Park D Shin and E S Yoon ldquoEconomic evaluationof renewable energy systems under varying scenarios and itsimplications to Korearsquos renewable energy planrdquo Applied Energyvol 88 no 6 pp 2254ndash2260 2011

[2] World Energy Outlook IEA Paris France 2008[3] KHofman andX Li ldquoCanadarsquos energy perspectives andpolicies

for sustainable developmentrdquo Applied Energy vol 86 no 4 pp407ndash415 2009

[4] H Weigt ldquoGermanyrsquos wind energy the potential for fossilcapacity replacement and cost savingrdquo Applied Energy vol 86no 10 pp 1857ndash1863 2009

[5] S A Khan R Rashmi M Z Hussain S Prasad and U CBanerjee ldquoProspects of biodiesel production from microalgaein Indiardquo Renewable and Sustainable Energy Reviews vol 13 no9 pp 2361ndash2372 2009

[6] E S Yoon ldquoA review on sustainable energy recent devel-opments and future prospects of dimethyl ether (DME)rdquo inProceedings of the 10th International Symposium on ProcessSystems Engineering (PSE rsquo09) Bahia Brazil 2009

[7] ldquoAdrar lancement des travaux du projet de la ferme eoliennerdquo2011 httpwwwalgerie360comalgerieadrar-lancement-des-travaux-du-projet-de-la-ferme-eolienne

[8] A Ducluzaux ldquoLrsquoenergie electrique drsquoorigine eoliennerdquo in Con-ference sur lrsquoEnergie Grenoble France 2004

[9] S Nguefeu M Arab X Waymel and F Costa ldquoPWM invertersin decentralized generation systems characterization of thedynamic behavior under utility fault conditionsrdquo InternationalJournal of Distributed Energy Resources vol 2 no 2 pp 101ndash1142006

[10] G Panayiotou S Kalogirou and S Tassou ldquoDesign andsimulation of a PV and a PV-Wind standalone energy systemto power a household applicationrdquo Renewable Energy vol 37no 1 pp 355ndash363 2012

[11] S M Shaahid ldquoReview of research on autonomous wind farmsand solar parks and their feasibility for commercial loads in hotregionsrdquo Renewable and Sustainable Energy Reviews vol 15 no8 pp 3877ndash3887 2011

[12] M A Elhadidy and S M Shaahid ldquoParametric study of hybrid(wind + solar + diesel) power generating systemsrdquo RenewableEnergy vol 21 no 2 pp 129ndash139 2000

12 The Scientific World Journal

[13] S M Shaahid and M A Elhadidy ldquoTechnical and economicassessment of grid-independent hybrid photovoltaic-diesel-battery power systems for commercial loads in desert environ-mentsrdquo Renewable and Sustainable Energy Reviews vol 11 no8 pp 1794ndash1810 2007

[14] D Saheb-Koussa M Haddadi and M Belhamel ldquoEconomicand technical study of a hybrid system (wind-photovoltaic-diesel) for rural electrification in Algeriardquo Applied Energy vol86 no 7-8 pp 1024ndash1030 2009

[15] G J Dalton D A Lockington and T E Baldock ldquoFeasibilityanalysis of stand-alone renewable energy supply options for alarge hotelrdquo Renewable Energy vol 33 no 7 pp 1475ndash14902008

[16] ANCelik ldquoPresent status of photovoltaic energy inTurkey andlife cycle techno-economic analysis of a grid-connected pho-tovoltaic-houserdquo Renewable and Sustainable Energy Reviewsvol 10 no 4 pp 370ndash387 2006

[17] M A H Mondal and M Denich ldquoAssessment of renew-able energy resources potential for electricity generation inBangladeshrdquoRenewable and Sustainable Energy Reviews vol 14no 7 pp 2401ndash2413 2010

[18] D Saheb-Koussa M Haddadi M Belhamel S Hadji and SNouredine ldquoModeling and simulation of the fixed-speedWECS(wind energy conversion system) application to the AlgerianSahara areardquo Energy vol 35 no 10 pp 4116ndash4125 2010

[19] S Rehman I M El-Amin F Ahmad et al ldquoFeasibility studyof hybrid retrofits to an isolated off-grid diesel power plantrdquoRenewable and Sustainable Energy Reviews vol 11 no 4 pp635ndash653 2007

[20] S Singer B Rozenshtein and S Surazi ldquoCharacterization of PVarray output using a small number of measured parametersrdquoSolar Energy vol 32 no 5 pp 603ndash607 1984

[21] D Saheb-Koussa ldquoContribution a lrsquoetude theorique du com-portement drsquoun systeme hybride (eolien- photovoltaıque-diesel) de production drsquoelectricite sans interruptionrdquo Memoirede magister Blida Septembre 2005

[22] G Tsengenes and G Adamidis ldquoInvestigation of the behaviorof a three phase grid-connected photovoltaic system to controlactive and reactive powerrdquo Electric Power Systems Research vol81 no 1 pp 177ndash184 2011

[23] S-K Chung ldquoA phase tracking system for three phase utilityinterface invertersrdquo IEEE Transactions on Power Electronics vol15 no 3 pp 431ndash438 2000

[24] R Dufo-Lopez J L Bernal-Agustın and F Mendoza ldquoDesignand economical analysis of hybrid PV-wind systems connectedto the grid for the intermittent production of hydrogenrdquo EnergyPolicy vol 37 no 8 pp 3082ndash3095 2009

[25] T Burton D Sharpe N Jenkins and E BossanyiWind EnergyHandbook John Wiley amp Sons West Sussex UK 2001

[26] Union for Coordination of Transmission of Electricity ldquoWindPower in the UCTE interconnected Systemrdquo November2004 httpswwwentsoeeufileadminuser upload librarypublicationsceotherreportsWind Power 20041125pdf

[27] E Spooner and A C Williamson ldquoDirect coupled permanentmagnet generators for wind turbine applicationsrdquo IEE Proceed-ings Electric Power Applications vol 143 no 1 pp 1ndash8 1996

[28] N Laverdure S Bacha D Roye B Raison and F DumasldquoElements of modelling of wind power systems with energymanagement two structures in comparisonrdquo in Proceedings ofthe 28th IEEE Annual Conference of the Industrial ElectronicsSociety vol 2 pp 1083ndash1088 November 2002

[29] L Krichen B Francois and A Ouali ldquoA fuzzy logic supervisorfor active and reactive power control of a fixed speed windenergy conversion systemrdquo Electric Power Systems Research vol78 no 3 pp 418ndash424 2008

[30] The Cres Wind Farm ldquo301 MW Demonstration wind farmin Greece Various wind energy technologies in complex Ter-rain topographyrdquo httpwwwcreswindfarmgrsite1ArticlesV47 USpdf

[31] T AckermannWind Power in Power Systems Royal Institute ofTechnology John Wiley amp Sons Stockholm Sweden 2005

[32] F Poitiers Asynchronous generator study and control for thewind energy use [PhD thesis] University of Nantes NantesFrance 2003

[33] M Kacira M Simsek Y Babur and S Demirkol ldquoDeterminingoptimum tilt angles and orientations of photovoltaic panels inSanliurfa Turkeyrdquo Renewable Energy vol 29 no 8 pp 1265ndash1275 2004

[34] D Saheb-Koussa M Belhamel and K Benferhat ldquoContribu-tion a lrsquoetude theorique du comportement drsquoun systeme hybride(eolien- photovoltaıque- diesel) de production drsquoelectricite sansinterruptionrdquo Afrique Science vol 5 no 1 2009

[35] HOMERmdashGetting Started Guide for HOMER Version 21National Renewable Energy Laboratory US Department ofEnergyOffice of EnergyEfficiency andRenewable Energy 2005

[36] C D Barley C B Winn L Flowers and H J Green ldquoOptimalcontrol of remote hybrid power systemsmdashpart I simplifiedmodelrdquo in Proceedings of National Avian-Wind Power PlanningMeeting Washington DC USA 1995

[37] D Saheb-Koussa ldquoEtude technique economique et environ-nementale des systemes decentralises connectes au reseauelectriquerdquo Bulletin des Energies Renouvelables vol 23 pp 15ndash17 2012

[38] V Courtecuisse Supervision drsquoune centrale multi sources a basedrsquoeoliennes et de stockage drsquoenergie connectee au reseau electrique[These de doctorat] Ecole Nationale des Arts et Metiers 2008

TribologyAdvances in

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International Journal of

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FuelsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Industrial EngineeringJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

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Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Renewable Energy

Submit your manuscripts athttpwwwhindawicom

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RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EnergyJournal of

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Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

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Solar EnergyJournal of

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Wind EnergyJournal of

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Nuclear EnergyInternational Journal of

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High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

The Scientific World Journal 3

DCAC

Managementsystem

Transformer

DC BUS

Photovoltaic generator

Wind generator

Grid

Figure 1 Decentralized installation connected to the grid

C

VDC

MPPTalgorithm PWM

Park

PV array

VDC-ref

VDC-ref

Park

PI PI

WL WL

+

++

++

+

+ +

minus minus

PLL

PI

VDC IDC

Powercontrol

+

+

minus

Grid

IabcL

120579

120579

Vd

Id-refIq-ref

Iq-ref

Id-ref

Vq

Vq

Vd

Abc120572120573

A120573dq

Qref

Figure 2 Schematic diagram of a connected PV-grid [9]

output voltages must be synchronized with the distributiongrid [23] For that purpose we introduced and turned aphase locked loop (PLL) which delivers the angle 120579 = 120596119905

mandatory for the Park transformation (translation into thesynchronous frame) Figure 3 shows the block diagramof thisPLL algorithm While supplying to the load or the grid acurrent corresponding to the real power reference a swingis created between voltages and currents in order to deliver areactive power according to the command

A proportional integral controller is used to control theactive and reactive power flowing

412 Modeling of the Wind System

Wind Speed Variation with Height [24] To calculate theoutput of the wind turbine in each of the 8760 hours in a yearthe hourly values of measured wind speed in the Adrar site atthe hub height of the machine is calculated by using

Vhub-h = Vln (119911hub1199110)ln (119911data1199110)

(2)

where 119911hub is the hub height of the wind turbine (m) 119911datais the anemometer height (m) 119911

0is the surface roughness

4 The Scientific World Journal

Gridtransform transform PI

Va

VqVb

Vd

Vc

V120572

V120573 120596int 120579

Abcdq 120572120573dq

Figure 3 Transport delay-based PLL algorithm

Wound rotorinduction generator

Gear box

Batteries

Gridconnection

point

Electricity

Figure 4 Wind system block diagram

length (m) [25] and the Vhub-h is the wind speed at theanemometer height during the hour h (ms)

Dynamic Model The types of wind turbine generators mayvary from wind generator to wind generator due to differentgenerator types (asynchronous synchronous) especially thecircuitry connecting the wind generator to the three-phasegrid which can have two different forms (direct or indirectgrid connection)

In the studied case the generator has been connecteddirectly to the three-phase alternating current grid Theresulting configuration is simple and according to the litera-ture [26 27] is widely used in practice (Figure 4)

Wind Turbine Dynamics Model The mechanical powerextracted from the wind [28 29] is given by the followingrelation

119875119905=1

2120588119862119901(120582 120573)119878V3 (3)

with

119878 = 1205871198772

119905 (4)

where 119878 is the area swept by thewind inm2 120588 is the air densityequal at standard conditions 1294 kgmminus3 V is the wind speedin ms 119877

119905is the radius in m

The power coefficient 119862119901depends on the tip speed ratio

(120582) and the blade angle (120573) In the case of turbines withoutpitch control the blade angle is constant and 119862

119901values only

depend on those of 120582 the tip speed ratio being expressed asfollows

120582 =Ω119905119877119905

V (5)

Also the mechanical torque produced by the wind isexpressed in the following relation

119879119905=119875119905

Ω119905

(6)

The VESTAS 47-660 wind generator experimental poweroutput data given by themanufacturer as well as the119862

119901curve

[30] have been approximated by using a simple MATLABpolynomial interpolation available as polyfit polynomialfunction and the obtained correlations are expressed asfollows

119875 (V) = 4240 minus 4727V minus 2194V2 minus 562V3

+ 885V4minus891V5 + 0585V6

minus 00249V7 + 664 sdot 10minus4V8

119862119901(V) = 11072 minus 12698V minus 04931V2

minus 000084V3 + 00781V4 minus 427 sdot 10minus4V5

+ 137 sdot 10minus5V6 minus 244 sdot 10minus7V7 + 183 sdot 10minus9V8

(7)

Then the operation of the wind turbine system is sim-ulated using the wind turbine equations which evaluate themechanical torque (119879

119905) and requires the turbine angular

speed (Ω119905) and the wind speed (V) as data

Drive Drain Dynamics Model To evaluate the generatorspeed (Ωam) the generator torque (119879am) and the turbinetorque (1198791015840

119905) are required as data The dynamic behaviour of

the mechanical system is determined by using the classicalrotational dynamics equations The inertia is considered asconcentrated in one lumped mass including the contributionof blades generator shafts and gear box The dynamicmotion equation of the mechanical system has the followingexpression

119869119889Ωam119889119905

+ 119891VΩam = 1198791015840

119905minus 119879am (8)

The turbine torque and generator speed (1198791015840119905andΩam) and

themechanical torque and turbine speed (119879119905andΩ

119905) supplied

to the wind turbine block simulation have been linked bymeans of the gear box whose ratio is 119896 (119896 = 505) for theVESTAS 660-47 wind generator

Asynchronous Machine Dynamics Model The asynchronousmachine equations permit to calculate the electrical power

The Scientific World Journal 5

generation of the system and return the generator torque119879amthe active and reactive power The generator speed Ωas andvoltage 119881

119889119902are the required input parameters obtained by

using the Park transform block PT of the three-phase systeminto the two-phase system [31]

(a) Electric and Magnetic Equations The voltage equationsrepresenting an induction machine [29 32] in an arbitraryreference frame can bewritten in terms of the phase currentsas given by [32]

In the present model the stator and rotor voltages alongthe 119889 and 119902 axes are given by [32]

Using these last ones a model for wound rotor generatorscan be developed This latter has short circuited windingsand as a consequence rotor voltages evaluate to zero (119881

119889119903= 0

and119881119902119903= 0) in this caseTherefore the representative wound

rotor generator equations are

119904120593119889119904= 119881119889119904minus 119877119904119868119889119904+ 120596119904sdot 120593119902119904

119904120593119902119904= 119881119902119904minus 119877119904sdot 119868119902119904minus 120596119904sdot 120593119889119904

119904120593119889119903= minus119877119903sdot 119868119889119903+ (120596119904minus 120596119903) sdot 120593119902119903

119904120593119902119903= minus119877119903sdot 119868119902119903minus (120596119904minus 120596119903)119904119903sdot 120593119889119903

(9)

where

120593119889119904= 119871119904sdot 119868119889119904+ 119871119904119903sdot 119868119889119903

120593119902119904= 119871119904sdot 119868119902119904+ 119871119904119903sdot 119868119902119903

120593119889119903= 119871119903sdot 119868119889119903+ 119871119904119903sdot 119868119889119904

120593119902119903= 119871119903sdot 119868119902119903+ 119871119904119903sdot 119868119902119904

(10)

(b) Evaluation of the Electromagnetic TorqueThe electromag-netic torque has been calculated by employing (11) proposedby [29 32]

Consider

119879am = (3

2)119875 sdot 119871

119904119903(119868119904119902sdot 119868119903119902minus 119868119904119889sdot 119868119903119902) (11)

(c) Evaluation of Real and Reactive Power The active (119875)and reactive (119876) power have been calculated by using thefollowing equations

119875 = 119881

119889119904119868119889119904+ 119881119902119904119868119902119904

119876 = 119881119902119904119868119889119904minus 119881119889119904119868119902119904

(12)

119875119903= minus (119881

119889119903119868119889119903+ 119881119902119903119868119902119903)

119876119903= minus (119881

119902119903119868119889119903+ 119881119889119903119868119902119903) (13)

Using these equations a model for wound rotor gen-erators can be developed This type of generator has shortcircuited windings thus the corresponding rotor voltages goto zero (119881

119889119903= 0 119881

119902119903= 0) Taking into account these

conditions (13) give 119875119903= 0 and 119876

119903= 0

5 Simulation

The energy system components are photovoltaic moduleswind turbine grid and power converter This study developsa suitable assembly of the key parameters such as photovoltaicarray power wind turbine power curve battery storageand converter capacity to match the predefined load Foreconomic analysis the cost including the initial capitalreplacement cost and operating and maintenance cost areconsidered as simulating conditions

Photovoltaic Arrays The initial cost of photovoltaic arraysmay vary from $400 to $500 per watt Considering a moreoptimistic system the costs of installation replacement andmaintenance of a 1 kW solar energy system are taken as $5000and $4000 Sizes of the photovoltaic arrays are varied between0 100 200 300 400 500 600 and 700 kW

Wind Turbine Energy generation formwind turbine dependson wind speed variations The wind turbine rated powershould be greater than average electrical load Thereforeaccording to the load data discussed above the average loadis around a 77MW Therefore a VESTAS 47ndash660 turbinemanufactured by VESTAS wind power is used Its ratedpower is 660 kWAC

Grid Grid exists as themain power component in this hybridrenewable energy system Moreover grid has the functionsas a storage system so a grid power system does not need abattery

Power Converter A converter is required for systems inwhichDC components serve an AD load or vice versa For a 1 kWsystem the installation and replacement costs are taken as$800 and $750 respectively Lifetime of a unit is consideredto be 25 years with an efficiency of 90

For the considered system it is necessary to simulateduring all the hours in a complete year all the possibledesigns Variables are considered hourly and therefore therewill be 8760 in a year At the end of the simulation we willknow the quantity of electrical energy from a PV generatorinjected to the grid in the year and the electrical energy fromwind turbines that is also injected [24]

As a sample site the Adrar site has been chosen and thefollowing data are used as input

(i) the hourly global and diffuse radiationmeasured on ahorizontal plane and the ambient temperature Fromthe data collected on a horizontal plane the compo-nents of the solar irradiance have been projected ontothe surface of a PV panel Moreover the inclinationof the used solar panel corresponds to the yearlyoptimum slope as indicated in [33]

(ii) the measured wind speeds and the electromechanicalcharacteristics of a wind turbine of the VESTAS47ndash660 type This is a three-blade model with adiameter of 46m a speed multiplier ratio of 505and a hub height of 100m [30] Moreover the power

6 The Scientific World Journal

0 5 10 15 20 25 300

100200300400500600700

Wind speed (ms)

Pow

er o

utpu

t (kW

)

Figure 5 Typical wind turbine power curve

produced by this wind turbine has been calculatedusing the power curve (Figure 5) provided by themanufacturer

51 Power Produced by the Photovoltaic Generator For calcu-lating the output characteristics of the photovoltaic systema program has been developed which requires the globalincident radiation and the air temperature as main inputdata So the research unit in renewable energy URER ofAdrar provided hourly measured values over a full year ofglobal and diffuse irradiation on a horizontal plane togetherwith those related to the ambient temperature From theglobal radiations on the horizontal plane collected data andbased on the equations given in [21] the developed programcalculates the overall incident irradiations on the surface ofthe PV panel These latter and the ambient temperatures areused to calculate the power and current delivered by the PVgenerator

The obtained results are presented in Figure 6

52 Power Produced by the Wind Generator Generally tocalculate the power generated by a wind turbine we use thedata drawn from the main characteristic 119901 = 119891(V) related tothe turbine and supplied by the manufacturer (Figure 5) Inthis study using the equations given in [34] the hourly valuesof the wind turbine are read from a file in which the windspeed for each hour of the year is given

By using the power curve of the wind turbine the outputpower is calculated With the speed at the hub of the windturbine and using its power curve the power that the windturbine provides in an hour h Pwminush (W) is obtained If thereare 119873

119908wind turbine connected in parallel this amount is

multiplied by119873119908[24] The obtained results are as follows

(i) Figure 7(a) shows the evolution of hourly windspeeds

(ii) Figure 7(b) shows the plots of the active power devel-oped at the asynchronous machine terminals

(iii) Figure 7(c) shows the plots of the reactive powerdeveloped at the asynchronous machine terminals

(iv) Figure 7(d) shows the current delivered by the windgenerator

0 1000 2000 3000 4000 5000 6000 7000 8000 900005

101520253035404550

Time (h)

Tem

pera

ture

(∘C)

(a)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

200400600800

10001200

Time (h)

Incli

ned

glob

al

radi

atio

n (w

m2)

(b)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

20406080

100120140160180

Time (h)

Pow

er p

rodu

ced

by th

ePV

gen

erat

or (W

)

(c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

012345

Time (h)

minus5minus4minus3minus2minus1

Thre

e-ph

ase c

urre

nts p

rodu

ced

by th

e PV

gen

erat

or (A

)

(d)

Figure 6 Representation of climatic characteristics power andcurrent produced by the photovoltaic module BP SX 150 S installedon the Adrar site

53 Management of the System [24] Figure 8 presents theMATLAB-SIMULINK program diagram of the hybrid sys-tem In this system the power delivered by each of the systemdevices (PV or wind) should be managed in such a way thatthe surplus of power produced by any of them is conductedto the grid without giving rise to any phenomena leading to

The Scientific World Journal 7

0 1000 2000 3000 4000 5000 6000 7000 8000 900005

10152025

Time (h)

Win

d sp

eed

(ms

)

(a)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0

Time (h)

Activ

e pow

er (k

W)

minus6

minus5

minus4

minus3

minus2

minus1

times105

(b)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

051

152

253

354

Time (h)

Reac

tive p

ower

(kVA

)

times105

(c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0200400600800

Time (h)

Thre

e-ph

ase s

tato

r cur

rent

s (A

)

minus800

minus600

minus400

minus200

(d)

Figure 7 Simulation results

a disturbance of any of these devices These last ones dis-turbed by generating harmonics that may distort the gridwaveform flickers high frequency wave frequency fluctua-tion under voltage and over voltage

Thus for each hour of the year h the amount of electricalenergy available at the transformer connected to the grid isevaluated by [24]

119875AC-h = (119875pv-h120578INV + 119875w-h)120578TR (14)

where 120578INV is the inverter efficiency rate modeled as avariable depending on the power delivered by the inverter120578TR is the efficiency rate of the transformer connected tothe electrical grid including the losses of power in thetransmission lines 119875w-h is the power (W) generated by thewind generator within an hour time and 119875pv-h is the power(W) generated by the PV generator within an hour time

However the amount of power that can be injected eachhour into the grid 119875EE-h (W) cannot be higher than theallowed evacuation capacity at the point of connection to thegrid 119875MAX-GRID (W) [24]

119875EE-h = min (119875MAX-GRID 119875AC-h) (15)

Where 119875MAX-GRID (W) is the maximum power evacuationvalue allowed which the Algerian law fixes for 20 to 30 ofthe line thermal limit at the point of connection

The amount of energy to be injected into the grid obtainedfrom the PV generator (119875EE-PV-h) and the wind generator119875EE-w-h will be calculated as indicated by Figure 9

The results obtained in the case of the previouslydescribed scenario are represented in Figure 10 which showsthat the hourly produced power injected into the grid is lowerthan 119875MAX-GRID

54 Total Annual Production The contribution of each partof the hybrid system (PV-wind-grid) to satisfy a specificload of the 34815MWhyr is shown in Figure 11 It is to benoted that the PV generator produces only 365MWhyearand covers only 1 of the load The wind generator inturn produces 7225MWhyear which constitute nearly 21of load requirements against a covered load rate of 78(27225MWhyear) provided by the conventional electricitygrid [35]These results are explained by the fact that HOMERsoftware promotes the wind system because of itrsquos efficiencywhich is very higher than that of PV system

55 Hours of Operation Figure 12 represents the durationof the operation (in hours) of each of the renewable energyequipment of the hybrid PV-wind-Grid system It is foundthat the wind generator works over the longest time intervalwith a 48 rate of the total period followed by the PVgenerator and inverter with a rate of 26 for each

56 Economic Aspects The HOMER optimization model[24] uses relatively simple strategies based on the ones studiedby Barley et al [36] and it is able to obtain an optimal designof a hybrid system by selecting the most appropriate strategy

Thus from an economic point of view it is found thatthe system composed of a 200 kW rated PV system andthree 660 kW rated wind turbines can cover 22 of theelectrical energy demand and has a net present cost (NPC)of $177 million and a cost of energy per kilowatt hour(COE) of $0399kWh A comparative economic analysisbetween the conventional and the optimized system (PV-wind system) employing HOMER software package [35] hasbeen performed and the results are presented in Table 1From these results it is noticed that the hybrid system (PV-wind-grid) is more economical than the conventional system

8 The Scientific World Journal

Yearly day number

Yearly day number 1

Tsvtsv

09

Transform

Preflight

09Convert

-C-

In1 cem

Wind system

vvvWind velocity

Scope

Result PV

Result

In1

In2

In3

In4

PV system

GHR

Global horiz rad

In1

In2

In3

PE1

PPV1

Out1

Gestion

difHR

Diffuse horiz rad1

Iabc

AP

AP

RP

Tt

Wt

Wmas

Iabc

Isabc

Isabc

Figure 8 Management of the system

PV system priority

No

No

NoNo Yes

Yes

Yes

Yes

Ppv-h Pw-h

Ppv-h Pw-h 120578inv 120578TR

PEE-h lt PMAX-GRID

PEE-h = Ppv-h120578INV 120578TR

120578inv 120578TR = Pmax-grid

Pw-h120578TR = PMAX-GRID

PEE-w-h = PMAX-GRIDPEE-PV-h = 0 PEE-PV-h = PMAX-GRIDPw-h120578TR

PEE-PV-h = PMAX-GRID

PEE-w-h = 0

PEE-w-h = 0 PEE-w-h = 0

PEE-w-h = 0

PEE-h = PEE-PV-h + PEE-w-h

PEE-PV-h = PPV-h120578INV120578TR

PEE-w-h = Pw-h TR120578middot

Figure 9 Flowchart for calculating the amount of power to be inject into the grid

The Scientific World Journal 9

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

500

1000

1500

2000

2500

3000

Time (h)

Pow

er (k

W)

Injected power into the gridPMAX-GRID

Figure 10 Power injected into the grid

1365 MWhyr

7225 MWhyr21

27225 MWhyr78

Photovoltaic systemWind systemGrid

Figure 11 Structure of the production system (PV-wind-grid)

26

48

26

Photovoltaic systemWind systemConverter

Figure 12 Distribution of operation hours of each of the renewableenergy equipment of the hybrid PV-wind-Grid system

05 1 15 2 25 3 35 4 450

20406080

100120140

Photovoltaic systemWind system

GridConverter

106$

Figure 13 Net present cost

05 1 15 2 25 3 35 4 4502468

1012

Photovoltaic systemWind system

GridConverter

106$yr

Figure 14 Annual net cost

Table 1 Cost comparison between a standard system (grid) and ahybrid system (PV-wind-grid)

Cost Conventional systemgrid

Hybrid systemPV-wind-grid

NPC ($yr) 177714200 177090600COE ($kWh) 04 0399

Table 2 Emissions comparison between a standard system (grid)and a hybrid system (PV-wind-grid)

Pollutant Kgyr Conventional systemgrid

Hybrid systemPV-wind-grid

CO2 21965160 17199524SO2 95229 74568NO119909

46572 36467

if the price per produced kWh of the latter is set to $04kWhHowever the net present cost is calculated for a projectlifetime period of 25 years and on the basis of an interest rateof 6 Figures 13 and 14 show the details of the correspondingcosts to each of the systems and the related annual costs [37]

57 Environmental Aspects The results regarding the effectsof each system configuration that is the conventional gridand the hybrid system (PV-wind-grid) on the environmentobtained by again using HOMER software in the caseof the Adrar site are shown in Table 2 [37] In this tablethe quantities of the main gases that are harmful to theenvironment including CO

2 SO2 and NOx are presented

10 The Scientific World Journal

160

165

170

175

180

72 76 80 84 88036

037

038

039

040

041

Leve

lized

cost

of en

ergy

($k

Wh)

Levelized cost of energy versus wind speed

Wind speed (ms)

Tota

l net

pre

sent

cost

($)

Levelized cost of energyTotal net present cost

Fixed

times106

Global solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 15 The relationship between cost and wind speed

72 76 80 84 88000

005

010

015

020

025

Rene

wab

le fr

actio

n

Renewable fraction versus wind speed

Wind speed (ms)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 16 The relationship between RF and wind speed

From these results it is found that the PV-wind-grid hybridsystem produces a reduction in the carbon dioxide gassulfur dioxide and nitrogen oxide rates by respectively 2022 and 22 as compared to the quantities produced by theconventional system [37]

58 Sensitivity Results In this study sensitivity analysis wasdone to study the effects of variation in the solar irradiationand wind speed The simulation software simulates thelong-term implementation of the hybrid system based ontheir respective search size for the predefined sensitivityvalues of the componentsThe emissions renewable fractionNPC and COE are simulated based on the three sensitivityvariables wind speed (ms) solar irradiation (kWm2day)and grid electricity price ($kWh) A long-term simulationfor every possible system combination and configurationwas done for a one year period (from January 1st 2005 toDecember 31st 2005) In the present case solar irradiationis set as sensitivity variables 119866 = 35 45 5 55 572 788 kWm2day while wind speed are V = 69 7 75 78 888msMoreover the grid electricity price is also defined as asensitivity variable (119901 = 01 02 03 04 $kWh) A total of 192

72 76 80 84 8816171819202122

Wind speed (ms)

times106

CO2

emiss

ions

(kg

yr)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

CO2 emissions versus wind speed

Figure 17The relationship betweenCO2emissions andwind speed

72 76 80 84 8830405060708090

100

Wind speed (ms)SO

2em

issio

ns (k

gyr

) SO2 emissions versus wind speed

SO2 emissionsNOx emissions

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 18 The relationship between sulfur dioxide and nitrogenoxide emissions and wind speed

sensitivity cases were tried for each system configurationThesimulation timewas 23minutes and 46 seconds on a personalcomputer with Intel CORE Intel Core Duo Processor of253GHz and a RAM of 2GBThe sensitivity results in termsof solar irradiation wind speed and grid electricity priceanalyze the feasibility of each system Here the feasibilityof hybrid renewable energy system is analyzed based onemission reduction and cost saving This type of sensitivityanalysis of the systems provides information that a particularsystem would be optimal at certain sensitivity variables [19]The PV-wind system is feasible when the grid electricityprice is more than $04 kWh Under this condition the RFcan be between 021 and 022 A PV-wind system is feasiblewhen global solar irradiation is more than 572 kWhm2 perday and the grid electricity price is more expensive than$04 kWh Based on the optimization results wind energyproduction shows a bigger proportion of energy generationthan solar While the solar power occupies less than 1 of thetotal energy generation wind power occupies approximatelya quarter

Therefore the wind energy resource has more impact onthe implementation Figures 15ndash18 reflect the cost renewablefraction and emission variation dependent on the sensitivityvariable wind speed The NPC and COE of the hybrid power

The Scientific World Journal 11

system reduce when the wind speed increases from 69ms to88ms Figure 15

Simultaneously as seen in Figure 16 renewable fractionrises sharply from 0 to 16 (when wind speed increases from69 to 7ms) and then steadily increases to 24 at a slowerrate In addition as shown in Figures 17 and 18 the mainemissions of carbon dioxide sulfur dioxide and nitrogenoxide persistently decrease 22

6 Problems Encountered in DecentralizedSystems [37]

The major difficulty associated with decentralized energysources is that they generally do not participate in ancillaryservices (voltage control frequency ability to operate instandalone mode etc) This is especially true for renewableenergy sources whose power flow is unpredictable and veryvolatile The integration of decentralized energy generationinto power networks raises the following problems

(i) random and unpredictable energy production (windsolar)

(ii) lack of power-frequency control(iii) no voltage adjustment performed(iv) sensitivity to voltage dips(v) significant sensitivity to changes in primary source

(wind solar) energy levels

The failure to take part in system services makes thistype of sources behave as passive generators from theelectrical energy generation point of view The penetrationof distributed energy generation must be limited from 20 to30 of the consumed power in order to guarantee acceptablesystem stability [19]

7 Conclusion

This study is related to the technical economic and envi-ronmental impact of grid-connected decentralized systems towhich an appropriatemanagement of energy is applied andbymeans of which are developed models of the different partsThe solar and wind energy resource data are collected fromthe weather station of Adrar which is a typical arid regionThe most significant results are as follows

The power that any subsystem can deliver depends on theweather conditions of the considered site

The PV based system only covers 1 of the total loadconsumption On the other hand the wind generator con-tribution amounts to about 21 of the energy productionwhile the remaining 78 are supplied by the conventionalelectricity grid

From an economic point of view it is found that for theAdrar site which is characterized by a high wind potentialthe hybrid system is competitive compared with the conven-tional system with a cost of the energy COE produced by thenetwork equal to $04kWh since the estimated COE relatedto the hybrid system is equal to $0399kWh based on anaverage wind speed greater than or equal to 6ms

From an environmental standpoint the rates of green-house gases (CO

2 SO2 andNOx) emissions are reduced from

20 to 22 in the case of a hybrid system compared with theconventional system

The sensitivity analysis indicates that PV-wind hybridsystem is feasible under the meteorological conditions inAdrar region With the increasing wind speed the NPCCOE and emissions of the hybrid renewable energy systemreduce and renewable fraction grows up

Conflict of Interests

None of the authors of this paper has a financial or personalrelationship with other people or organisations that couldinappropriately influence or bias the content of the paper

References

[1] J Koo K Park D Shin and E S Yoon ldquoEconomic evaluationof renewable energy systems under varying scenarios and itsimplications to Korearsquos renewable energy planrdquo Applied Energyvol 88 no 6 pp 2254ndash2260 2011

[2] World Energy Outlook IEA Paris France 2008[3] KHofman andX Li ldquoCanadarsquos energy perspectives andpolicies

for sustainable developmentrdquo Applied Energy vol 86 no 4 pp407ndash415 2009

[4] H Weigt ldquoGermanyrsquos wind energy the potential for fossilcapacity replacement and cost savingrdquo Applied Energy vol 86no 10 pp 1857ndash1863 2009

[5] S A Khan R Rashmi M Z Hussain S Prasad and U CBanerjee ldquoProspects of biodiesel production from microalgaein Indiardquo Renewable and Sustainable Energy Reviews vol 13 no9 pp 2361ndash2372 2009

[6] E S Yoon ldquoA review on sustainable energy recent devel-opments and future prospects of dimethyl ether (DME)rdquo inProceedings of the 10th International Symposium on ProcessSystems Engineering (PSE rsquo09) Bahia Brazil 2009

[7] ldquoAdrar lancement des travaux du projet de la ferme eoliennerdquo2011 httpwwwalgerie360comalgerieadrar-lancement-des-travaux-du-projet-de-la-ferme-eolienne

[8] A Ducluzaux ldquoLrsquoenergie electrique drsquoorigine eoliennerdquo in Con-ference sur lrsquoEnergie Grenoble France 2004

[9] S Nguefeu M Arab X Waymel and F Costa ldquoPWM invertersin decentralized generation systems characterization of thedynamic behavior under utility fault conditionsrdquo InternationalJournal of Distributed Energy Resources vol 2 no 2 pp 101ndash1142006

[10] G Panayiotou S Kalogirou and S Tassou ldquoDesign andsimulation of a PV and a PV-Wind standalone energy systemto power a household applicationrdquo Renewable Energy vol 37no 1 pp 355ndash363 2012

[11] S M Shaahid ldquoReview of research on autonomous wind farmsand solar parks and their feasibility for commercial loads in hotregionsrdquo Renewable and Sustainable Energy Reviews vol 15 no8 pp 3877ndash3887 2011

[12] M A Elhadidy and S M Shaahid ldquoParametric study of hybrid(wind + solar + diesel) power generating systemsrdquo RenewableEnergy vol 21 no 2 pp 129ndash139 2000

12 The Scientific World Journal

[13] S M Shaahid and M A Elhadidy ldquoTechnical and economicassessment of grid-independent hybrid photovoltaic-diesel-battery power systems for commercial loads in desert environ-mentsrdquo Renewable and Sustainable Energy Reviews vol 11 no8 pp 1794ndash1810 2007

[14] D Saheb-Koussa M Haddadi and M Belhamel ldquoEconomicand technical study of a hybrid system (wind-photovoltaic-diesel) for rural electrification in Algeriardquo Applied Energy vol86 no 7-8 pp 1024ndash1030 2009

[15] G J Dalton D A Lockington and T E Baldock ldquoFeasibilityanalysis of stand-alone renewable energy supply options for alarge hotelrdquo Renewable Energy vol 33 no 7 pp 1475ndash14902008

[16] ANCelik ldquoPresent status of photovoltaic energy inTurkey andlife cycle techno-economic analysis of a grid-connected pho-tovoltaic-houserdquo Renewable and Sustainable Energy Reviewsvol 10 no 4 pp 370ndash387 2006

[17] M A H Mondal and M Denich ldquoAssessment of renew-able energy resources potential for electricity generation inBangladeshrdquoRenewable and Sustainable Energy Reviews vol 14no 7 pp 2401ndash2413 2010

[18] D Saheb-Koussa M Haddadi M Belhamel S Hadji and SNouredine ldquoModeling and simulation of the fixed-speedWECS(wind energy conversion system) application to the AlgerianSahara areardquo Energy vol 35 no 10 pp 4116ndash4125 2010

[19] S Rehman I M El-Amin F Ahmad et al ldquoFeasibility studyof hybrid retrofits to an isolated off-grid diesel power plantrdquoRenewable and Sustainable Energy Reviews vol 11 no 4 pp635ndash653 2007

[20] S Singer B Rozenshtein and S Surazi ldquoCharacterization of PVarray output using a small number of measured parametersrdquoSolar Energy vol 32 no 5 pp 603ndash607 1984

[21] D Saheb-Koussa ldquoContribution a lrsquoetude theorique du com-portement drsquoun systeme hybride (eolien- photovoltaıque-diesel) de production drsquoelectricite sans interruptionrdquo Memoirede magister Blida Septembre 2005

[22] G Tsengenes and G Adamidis ldquoInvestigation of the behaviorof a three phase grid-connected photovoltaic system to controlactive and reactive powerrdquo Electric Power Systems Research vol81 no 1 pp 177ndash184 2011

[23] S-K Chung ldquoA phase tracking system for three phase utilityinterface invertersrdquo IEEE Transactions on Power Electronics vol15 no 3 pp 431ndash438 2000

[24] R Dufo-Lopez J L Bernal-Agustın and F Mendoza ldquoDesignand economical analysis of hybrid PV-wind systems connectedto the grid for the intermittent production of hydrogenrdquo EnergyPolicy vol 37 no 8 pp 3082ndash3095 2009

[25] T Burton D Sharpe N Jenkins and E BossanyiWind EnergyHandbook John Wiley amp Sons West Sussex UK 2001

[26] Union for Coordination of Transmission of Electricity ldquoWindPower in the UCTE interconnected Systemrdquo November2004 httpswwwentsoeeufileadminuser upload librarypublicationsceotherreportsWind Power 20041125pdf

[27] E Spooner and A C Williamson ldquoDirect coupled permanentmagnet generators for wind turbine applicationsrdquo IEE Proceed-ings Electric Power Applications vol 143 no 1 pp 1ndash8 1996

[28] N Laverdure S Bacha D Roye B Raison and F DumasldquoElements of modelling of wind power systems with energymanagement two structures in comparisonrdquo in Proceedings ofthe 28th IEEE Annual Conference of the Industrial ElectronicsSociety vol 2 pp 1083ndash1088 November 2002

[29] L Krichen B Francois and A Ouali ldquoA fuzzy logic supervisorfor active and reactive power control of a fixed speed windenergy conversion systemrdquo Electric Power Systems Research vol78 no 3 pp 418ndash424 2008

[30] The Cres Wind Farm ldquo301 MW Demonstration wind farmin Greece Various wind energy technologies in complex Ter-rain topographyrdquo httpwwwcreswindfarmgrsite1ArticlesV47 USpdf

[31] T AckermannWind Power in Power Systems Royal Institute ofTechnology John Wiley amp Sons Stockholm Sweden 2005

[32] F Poitiers Asynchronous generator study and control for thewind energy use [PhD thesis] University of Nantes NantesFrance 2003

[33] M Kacira M Simsek Y Babur and S Demirkol ldquoDeterminingoptimum tilt angles and orientations of photovoltaic panels inSanliurfa Turkeyrdquo Renewable Energy vol 29 no 8 pp 1265ndash1275 2004

[34] D Saheb-Koussa M Belhamel and K Benferhat ldquoContribu-tion a lrsquoetude theorique du comportement drsquoun systeme hybride(eolien- photovoltaıque- diesel) de production drsquoelectricite sansinterruptionrdquo Afrique Science vol 5 no 1 2009

[35] HOMERmdashGetting Started Guide for HOMER Version 21National Renewable Energy Laboratory US Department ofEnergyOffice of EnergyEfficiency andRenewable Energy 2005

[36] C D Barley C B Winn L Flowers and H J Green ldquoOptimalcontrol of remote hybrid power systemsmdashpart I simplifiedmodelrdquo in Proceedings of National Avian-Wind Power PlanningMeeting Washington DC USA 1995

[37] D Saheb-Koussa ldquoEtude technique economique et environ-nementale des systemes decentralises connectes au reseauelectriquerdquo Bulletin des Energies Renouvelables vol 23 pp 15ndash17 2012

[38] V Courtecuisse Supervision drsquoune centrale multi sources a basedrsquoeoliennes et de stockage drsquoenergie connectee au reseau electrique[These de doctorat] Ecole Nationale des Arts et Metiers 2008

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The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

4 The Scientific World Journal

Gridtransform transform PI

Va

VqVb

Vd

Vc

V120572

V120573 120596int 120579

Abcdq 120572120573dq

Figure 3 Transport delay-based PLL algorithm

Wound rotorinduction generator

Gear box

Batteries

Gridconnection

point

Electricity

Figure 4 Wind system block diagram

length (m) [25] and the Vhub-h is the wind speed at theanemometer height during the hour h (ms)

Dynamic Model The types of wind turbine generators mayvary from wind generator to wind generator due to differentgenerator types (asynchronous synchronous) especially thecircuitry connecting the wind generator to the three-phasegrid which can have two different forms (direct or indirectgrid connection)

In the studied case the generator has been connecteddirectly to the three-phase alternating current grid Theresulting configuration is simple and according to the litera-ture [26 27] is widely used in practice (Figure 4)

Wind Turbine Dynamics Model The mechanical powerextracted from the wind [28 29] is given by the followingrelation

119875119905=1

2120588119862119901(120582 120573)119878V3 (3)

with

119878 = 1205871198772

119905 (4)

where 119878 is the area swept by thewind inm2 120588 is the air densityequal at standard conditions 1294 kgmminus3 V is the wind speedin ms 119877

119905is the radius in m

The power coefficient 119862119901depends on the tip speed ratio

(120582) and the blade angle (120573) In the case of turbines withoutpitch control the blade angle is constant and 119862

119901values only

depend on those of 120582 the tip speed ratio being expressed asfollows

120582 =Ω119905119877119905

V (5)

Also the mechanical torque produced by the wind isexpressed in the following relation

119879119905=119875119905

Ω119905

(6)

The VESTAS 47-660 wind generator experimental poweroutput data given by themanufacturer as well as the119862

119901curve

[30] have been approximated by using a simple MATLABpolynomial interpolation available as polyfit polynomialfunction and the obtained correlations are expressed asfollows

119875 (V) = 4240 minus 4727V minus 2194V2 minus 562V3

+ 885V4minus891V5 + 0585V6

minus 00249V7 + 664 sdot 10minus4V8

119862119901(V) = 11072 minus 12698V minus 04931V2

minus 000084V3 + 00781V4 minus 427 sdot 10minus4V5

+ 137 sdot 10minus5V6 minus 244 sdot 10minus7V7 + 183 sdot 10minus9V8

(7)

Then the operation of the wind turbine system is sim-ulated using the wind turbine equations which evaluate themechanical torque (119879

119905) and requires the turbine angular

speed (Ω119905) and the wind speed (V) as data

Drive Drain Dynamics Model To evaluate the generatorspeed (Ωam) the generator torque (119879am) and the turbinetorque (1198791015840

119905) are required as data The dynamic behaviour of

the mechanical system is determined by using the classicalrotational dynamics equations The inertia is considered asconcentrated in one lumped mass including the contributionof blades generator shafts and gear box The dynamicmotion equation of the mechanical system has the followingexpression

119869119889Ωam119889119905

+ 119891VΩam = 1198791015840

119905minus 119879am (8)

The turbine torque and generator speed (1198791015840119905andΩam) and

themechanical torque and turbine speed (119879119905andΩ

119905) supplied

to the wind turbine block simulation have been linked bymeans of the gear box whose ratio is 119896 (119896 = 505) for theVESTAS 660-47 wind generator

Asynchronous Machine Dynamics Model The asynchronousmachine equations permit to calculate the electrical power

The Scientific World Journal 5

generation of the system and return the generator torque119879amthe active and reactive power The generator speed Ωas andvoltage 119881

119889119902are the required input parameters obtained by

using the Park transform block PT of the three-phase systeminto the two-phase system [31]

(a) Electric and Magnetic Equations The voltage equationsrepresenting an induction machine [29 32] in an arbitraryreference frame can bewritten in terms of the phase currentsas given by [32]

In the present model the stator and rotor voltages alongthe 119889 and 119902 axes are given by [32]

Using these last ones a model for wound rotor generatorscan be developed This latter has short circuited windingsand as a consequence rotor voltages evaluate to zero (119881

119889119903= 0

and119881119902119903= 0) in this caseTherefore the representative wound

rotor generator equations are

119904120593119889119904= 119881119889119904minus 119877119904119868119889119904+ 120596119904sdot 120593119902119904

119904120593119902119904= 119881119902119904minus 119877119904sdot 119868119902119904minus 120596119904sdot 120593119889119904

119904120593119889119903= minus119877119903sdot 119868119889119903+ (120596119904minus 120596119903) sdot 120593119902119903

119904120593119902119903= minus119877119903sdot 119868119902119903minus (120596119904minus 120596119903)119904119903sdot 120593119889119903

(9)

where

120593119889119904= 119871119904sdot 119868119889119904+ 119871119904119903sdot 119868119889119903

120593119902119904= 119871119904sdot 119868119902119904+ 119871119904119903sdot 119868119902119903

120593119889119903= 119871119903sdot 119868119889119903+ 119871119904119903sdot 119868119889119904

120593119902119903= 119871119903sdot 119868119902119903+ 119871119904119903sdot 119868119902119904

(10)

(b) Evaluation of the Electromagnetic TorqueThe electromag-netic torque has been calculated by employing (11) proposedby [29 32]

Consider

119879am = (3

2)119875 sdot 119871

119904119903(119868119904119902sdot 119868119903119902minus 119868119904119889sdot 119868119903119902) (11)

(c) Evaluation of Real and Reactive Power The active (119875)and reactive (119876) power have been calculated by using thefollowing equations

119875 = 119881

119889119904119868119889119904+ 119881119902119904119868119902119904

119876 = 119881119902119904119868119889119904minus 119881119889119904119868119902119904

(12)

119875119903= minus (119881

119889119903119868119889119903+ 119881119902119903119868119902119903)

119876119903= minus (119881

119902119903119868119889119903+ 119881119889119903119868119902119903) (13)

Using these equations a model for wound rotor gen-erators can be developed This type of generator has shortcircuited windings thus the corresponding rotor voltages goto zero (119881

119889119903= 0 119881

119902119903= 0) Taking into account these

conditions (13) give 119875119903= 0 and 119876

119903= 0

5 Simulation

The energy system components are photovoltaic moduleswind turbine grid and power converter This study developsa suitable assembly of the key parameters such as photovoltaicarray power wind turbine power curve battery storageand converter capacity to match the predefined load Foreconomic analysis the cost including the initial capitalreplacement cost and operating and maintenance cost areconsidered as simulating conditions

Photovoltaic Arrays The initial cost of photovoltaic arraysmay vary from $400 to $500 per watt Considering a moreoptimistic system the costs of installation replacement andmaintenance of a 1 kW solar energy system are taken as $5000and $4000 Sizes of the photovoltaic arrays are varied between0 100 200 300 400 500 600 and 700 kW

Wind Turbine Energy generation formwind turbine dependson wind speed variations The wind turbine rated powershould be greater than average electrical load Thereforeaccording to the load data discussed above the average loadis around a 77MW Therefore a VESTAS 47ndash660 turbinemanufactured by VESTAS wind power is used Its ratedpower is 660 kWAC

Grid Grid exists as themain power component in this hybridrenewable energy system Moreover grid has the functionsas a storage system so a grid power system does not need abattery

Power Converter A converter is required for systems inwhichDC components serve an AD load or vice versa For a 1 kWsystem the installation and replacement costs are taken as$800 and $750 respectively Lifetime of a unit is consideredto be 25 years with an efficiency of 90

For the considered system it is necessary to simulateduring all the hours in a complete year all the possibledesigns Variables are considered hourly and therefore therewill be 8760 in a year At the end of the simulation we willknow the quantity of electrical energy from a PV generatorinjected to the grid in the year and the electrical energy fromwind turbines that is also injected [24]

As a sample site the Adrar site has been chosen and thefollowing data are used as input

(i) the hourly global and diffuse radiationmeasured on ahorizontal plane and the ambient temperature Fromthe data collected on a horizontal plane the compo-nents of the solar irradiance have been projected ontothe surface of a PV panel Moreover the inclinationof the used solar panel corresponds to the yearlyoptimum slope as indicated in [33]

(ii) the measured wind speeds and the electromechanicalcharacteristics of a wind turbine of the VESTAS47ndash660 type This is a three-blade model with adiameter of 46m a speed multiplier ratio of 505and a hub height of 100m [30] Moreover the power

6 The Scientific World Journal

0 5 10 15 20 25 300

100200300400500600700

Wind speed (ms)

Pow

er o

utpu

t (kW

)

Figure 5 Typical wind turbine power curve

produced by this wind turbine has been calculatedusing the power curve (Figure 5) provided by themanufacturer

51 Power Produced by the Photovoltaic Generator For calcu-lating the output characteristics of the photovoltaic systema program has been developed which requires the globalincident radiation and the air temperature as main inputdata So the research unit in renewable energy URER ofAdrar provided hourly measured values over a full year ofglobal and diffuse irradiation on a horizontal plane togetherwith those related to the ambient temperature From theglobal radiations on the horizontal plane collected data andbased on the equations given in [21] the developed programcalculates the overall incident irradiations on the surface ofthe PV panel These latter and the ambient temperatures areused to calculate the power and current delivered by the PVgenerator

The obtained results are presented in Figure 6

52 Power Produced by the Wind Generator Generally tocalculate the power generated by a wind turbine we use thedata drawn from the main characteristic 119901 = 119891(V) related tothe turbine and supplied by the manufacturer (Figure 5) Inthis study using the equations given in [34] the hourly valuesof the wind turbine are read from a file in which the windspeed for each hour of the year is given

By using the power curve of the wind turbine the outputpower is calculated With the speed at the hub of the windturbine and using its power curve the power that the windturbine provides in an hour h Pwminush (W) is obtained If thereare 119873

119908wind turbine connected in parallel this amount is

multiplied by119873119908[24] The obtained results are as follows

(i) Figure 7(a) shows the evolution of hourly windspeeds

(ii) Figure 7(b) shows the plots of the active power devel-oped at the asynchronous machine terminals

(iii) Figure 7(c) shows the plots of the reactive powerdeveloped at the asynchronous machine terminals

(iv) Figure 7(d) shows the current delivered by the windgenerator

0 1000 2000 3000 4000 5000 6000 7000 8000 900005

101520253035404550

Time (h)

Tem

pera

ture

(∘C)

(a)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

200400600800

10001200

Time (h)

Incli

ned

glob

al

radi

atio

n (w

m2)

(b)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

20406080

100120140160180

Time (h)

Pow

er p

rodu

ced

by th

ePV

gen

erat

or (W

)

(c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

012345

Time (h)

minus5minus4minus3minus2minus1

Thre

e-ph

ase c

urre

nts p

rodu

ced

by th

e PV

gen

erat

or (A

)

(d)

Figure 6 Representation of climatic characteristics power andcurrent produced by the photovoltaic module BP SX 150 S installedon the Adrar site

53 Management of the System [24] Figure 8 presents theMATLAB-SIMULINK program diagram of the hybrid sys-tem In this system the power delivered by each of the systemdevices (PV or wind) should be managed in such a way thatthe surplus of power produced by any of them is conductedto the grid without giving rise to any phenomena leading to

The Scientific World Journal 7

0 1000 2000 3000 4000 5000 6000 7000 8000 900005

10152025

Time (h)

Win

d sp

eed

(ms

)

(a)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0

Time (h)

Activ

e pow

er (k

W)

minus6

minus5

minus4

minus3

minus2

minus1

times105

(b)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

051

152

253

354

Time (h)

Reac

tive p

ower

(kVA

)

times105

(c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0200400600800

Time (h)

Thre

e-ph

ase s

tato

r cur

rent

s (A

)

minus800

minus600

minus400

minus200

(d)

Figure 7 Simulation results

a disturbance of any of these devices These last ones dis-turbed by generating harmonics that may distort the gridwaveform flickers high frequency wave frequency fluctua-tion under voltage and over voltage

Thus for each hour of the year h the amount of electricalenergy available at the transformer connected to the grid isevaluated by [24]

119875AC-h = (119875pv-h120578INV + 119875w-h)120578TR (14)

where 120578INV is the inverter efficiency rate modeled as avariable depending on the power delivered by the inverter120578TR is the efficiency rate of the transformer connected tothe electrical grid including the losses of power in thetransmission lines 119875w-h is the power (W) generated by thewind generator within an hour time and 119875pv-h is the power(W) generated by the PV generator within an hour time

However the amount of power that can be injected eachhour into the grid 119875EE-h (W) cannot be higher than theallowed evacuation capacity at the point of connection to thegrid 119875MAX-GRID (W) [24]

119875EE-h = min (119875MAX-GRID 119875AC-h) (15)

Where 119875MAX-GRID (W) is the maximum power evacuationvalue allowed which the Algerian law fixes for 20 to 30 ofthe line thermal limit at the point of connection

The amount of energy to be injected into the grid obtainedfrom the PV generator (119875EE-PV-h) and the wind generator119875EE-w-h will be calculated as indicated by Figure 9

The results obtained in the case of the previouslydescribed scenario are represented in Figure 10 which showsthat the hourly produced power injected into the grid is lowerthan 119875MAX-GRID

54 Total Annual Production The contribution of each partof the hybrid system (PV-wind-grid) to satisfy a specificload of the 34815MWhyr is shown in Figure 11 It is to benoted that the PV generator produces only 365MWhyearand covers only 1 of the load The wind generator inturn produces 7225MWhyear which constitute nearly 21of load requirements against a covered load rate of 78(27225MWhyear) provided by the conventional electricitygrid [35]These results are explained by the fact that HOMERsoftware promotes the wind system because of itrsquos efficiencywhich is very higher than that of PV system

55 Hours of Operation Figure 12 represents the durationof the operation (in hours) of each of the renewable energyequipment of the hybrid PV-wind-Grid system It is foundthat the wind generator works over the longest time intervalwith a 48 rate of the total period followed by the PVgenerator and inverter with a rate of 26 for each

56 Economic Aspects The HOMER optimization model[24] uses relatively simple strategies based on the ones studiedby Barley et al [36] and it is able to obtain an optimal designof a hybrid system by selecting the most appropriate strategy

Thus from an economic point of view it is found thatthe system composed of a 200 kW rated PV system andthree 660 kW rated wind turbines can cover 22 of theelectrical energy demand and has a net present cost (NPC)of $177 million and a cost of energy per kilowatt hour(COE) of $0399kWh A comparative economic analysisbetween the conventional and the optimized system (PV-wind system) employing HOMER software package [35] hasbeen performed and the results are presented in Table 1From these results it is noticed that the hybrid system (PV-wind-grid) is more economical than the conventional system

8 The Scientific World Journal

Yearly day number

Yearly day number 1

Tsvtsv

09

Transform

Preflight

09Convert

-C-

In1 cem

Wind system

vvvWind velocity

Scope

Result PV

Result

In1

In2

In3

In4

PV system

GHR

Global horiz rad

In1

In2

In3

PE1

PPV1

Out1

Gestion

difHR

Diffuse horiz rad1

Iabc

AP

AP

RP

Tt

Wt

Wmas

Iabc

Isabc

Isabc

Figure 8 Management of the system

PV system priority

No

No

NoNo Yes

Yes

Yes

Yes

Ppv-h Pw-h

Ppv-h Pw-h 120578inv 120578TR

PEE-h lt PMAX-GRID

PEE-h = Ppv-h120578INV 120578TR

120578inv 120578TR = Pmax-grid

Pw-h120578TR = PMAX-GRID

PEE-w-h = PMAX-GRIDPEE-PV-h = 0 PEE-PV-h = PMAX-GRIDPw-h120578TR

PEE-PV-h = PMAX-GRID

PEE-w-h = 0

PEE-w-h = 0 PEE-w-h = 0

PEE-w-h = 0

PEE-h = PEE-PV-h + PEE-w-h

PEE-PV-h = PPV-h120578INV120578TR

PEE-w-h = Pw-h TR120578middot

Figure 9 Flowchart for calculating the amount of power to be inject into the grid

The Scientific World Journal 9

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

500

1000

1500

2000

2500

3000

Time (h)

Pow

er (k

W)

Injected power into the gridPMAX-GRID

Figure 10 Power injected into the grid

1365 MWhyr

7225 MWhyr21

27225 MWhyr78

Photovoltaic systemWind systemGrid

Figure 11 Structure of the production system (PV-wind-grid)

26

48

26

Photovoltaic systemWind systemConverter

Figure 12 Distribution of operation hours of each of the renewableenergy equipment of the hybrid PV-wind-Grid system

05 1 15 2 25 3 35 4 450

20406080

100120140

Photovoltaic systemWind system

GridConverter

106$

Figure 13 Net present cost

05 1 15 2 25 3 35 4 4502468

1012

Photovoltaic systemWind system

GridConverter

106$yr

Figure 14 Annual net cost

Table 1 Cost comparison between a standard system (grid) and ahybrid system (PV-wind-grid)

Cost Conventional systemgrid

Hybrid systemPV-wind-grid

NPC ($yr) 177714200 177090600COE ($kWh) 04 0399

Table 2 Emissions comparison between a standard system (grid)and a hybrid system (PV-wind-grid)

Pollutant Kgyr Conventional systemgrid

Hybrid systemPV-wind-grid

CO2 21965160 17199524SO2 95229 74568NO119909

46572 36467

if the price per produced kWh of the latter is set to $04kWhHowever the net present cost is calculated for a projectlifetime period of 25 years and on the basis of an interest rateof 6 Figures 13 and 14 show the details of the correspondingcosts to each of the systems and the related annual costs [37]

57 Environmental Aspects The results regarding the effectsof each system configuration that is the conventional gridand the hybrid system (PV-wind-grid) on the environmentobtained by again using HOMER software in the caseof the Adrar site are shown in Table 2 [37] In this tablethe quantities of the main gases that are harmful to theenvironment including CO

2 SO2 and NOx are presented

10 The Scientific World Journal

160

165

170

175

180

72 76 80 84 88036

037

038

039

040

041

Leve

lized

cost

of en

ergy

($k

Wh)

Levelized cost of energy versus wind speed

Wind speed (ms)

Tota

l net

pre

sent

cost

($)

Levelized cost of energyTotal net present cost

Fixed

times106

Global solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 15 The relationship between cost and wind speed

72 76 80 84 88000

005

010

015

020

025

Rene

wab

le fr

actio

n

Renewable fraction versus wind speed

Wind speed (ms)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 16 The relationship between RF and wind speed

From these results it is found that the PV-wind-grid hybridsystem produces a reduction in the carbon dioxide gassulfur dioxide and nitrogen oxide rates by respectively 2022 and 22 as compared to the quantities produced by theconventional system [37]

58 Sensitivity Results In this study sensitivity analysis wasdone to study the effects of variation in the solar irradiationand wind speed The simulation software simulates thelong-term implementation of the hybrid system based ontheir respective search size for the predefined sensitivityvalues of the componentsThe emissions renewable fractionNPC and COE are simulated based on the three sensitivityvariables wind speed (ms) solar irradiation (kWm2day)and grid electricity price ($kWh) A long-term simulationfor every possible system combination and configurationwas done for a one year period (from January 1st 2005 toDecember 31st 2005) In the present case solar irradiationis set as sensitivity variables 119866 = 35 45 5 55 572 788 kWm2day while wind speed are V = 69 7 75 78 888msMoreover the grid electricity price is also defined as asensitivity variable (119901 = 01 02 03 04 $kWh) A total of 192

72 76 80 84 8816171819202122

Wind speed (ms)

times106

CO2

emiss

ions

(kg

yr)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

CO2 emissions versus wind speed

Figure 17The relationship betweenCO2emissions andwind speed

72 76 80 84 8830405060708090

100

Wind speed (ms)SO

2em

issio

ns (k

gyr

) SO2 emissions versus wind speed

SO2 emissionsNOx emissions

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 18 The relationship between sulfur dioxide and nitrogenoxide emissions and wind speed

sensitivity cases were tried for each system configurationThesimulation timewas 23minutes and 46 seconds on a personalcomputer with Intel CORE Intel Core Duo Processor of253GHz and a RAM of 2GBThe sensitivity results in termsof solar irradiation wind speed and grid electricity priceanalyze the feasibility of each system Here the feasibilityof hybrid renewable energy system is analyzed based onemission reduction and cost saving This type of sensitivityanalysis of the systems provides information that a particularsystem would be optimal at certain sensitivity variables [19]The PV-wind system is feasible when the grid electricityprice is more than $04 kWh Under this condition the RFcan be between 021 and 022 A PV-wind system is feasiblewhen global solar irradiation is more than 572 kWhm2 perday and the grid electricity price is more expensive than$04 kWh Based on the optimization results wind energyproduction shows a bigger proportion of energy generationthan solar While the solar power occupies less than 1 of thetotal energy generation wind power occupies approximatelya quarter

Therefore the wind energy resource has more impact onthe implementation Figures 15ndash18 reflect the cost renewablefraction and emission variation dependent on the sensitivityvariable wind speed The NPC and COE of the hybrid power

The Scientific World Journal 11

system reduce when the wind speed increases from 69ms to88ms Figure 15

Simultaneously as seen in Figure 16 renewable fractionrises sharply from 0 to 16 (when wind speed increases from69 to 7ms) and then steadily increases to 24 at a slowerrate In addition as shown in Figures 17 and 18 the mainemissions of carbon dioxide sulfur dioxide and nitrogenoxide persistently decrease 22

6 Problems Encountered in DecentralizedSystems [37]

The major difficulty associated with decentralized energysources is that they generally do not participate in ancillaryservices (voltage control frequency ability to operate instandalone mode etc) This is especially true for renewableenergy sources whose power flow is unpredictable and veryvolatile The integration of decentralized energy generationinto power networks raises the following problems

(i) random and unpredictable energy production (windsolar)

(ii) lack of power-frequency control(iii) no voltage adjustment performed(iv) sensitivity to voltage dips(v) significant sensitivity to changes in primary source

(wind solar) energy levels

The failure to take part in system services makes thistype of sources behave as passive generators from theelectrical energy generation point of view The penetrationof distributed energy generation must be limited from 20 to30 of the consumed power in order to guarantee acceptablesystem stability [19]

7 Conclusion

This study is related to the technical economic and envi-ronmental impact of grid-connected decentralized systems towhich an appropriatemanagement of energy is applied andbymeans of which are developed models of the different partsThe solar and wind energy resource data are collected fromthe weather station of Adrar which is a typical arid regionThe most significant results are as follows

The power that any subsystem can deliver depends on theweather conditions of the considered site

The PV based system only covers 1 of the total loadconsumption On the other hand the wind generator con-tribution amounts to about 21 of the energy productionwhile the remaining 78 are supplied by the conventionalelectricity grid

From an economic point of view it is found that for theAdrar site which is characterized by a high wind potentialthe hybrid system is competitive compared with the conven-tional system with a cost of the energy COE produced by thenetwork equal to $04kWh since the estimated COE relatedto the hybrid system is equal to $0399kWh based on anaverage wind speed greater than or equal to 6ms

From an environmental standpoint the rates of green-house gases (CO

2 SO2 andNOx) emissions are reduced from

20 to 22 in the case of a hybrid system compared with theconventional system

The sensitivity analysis indicates that PV-wind hybridsystem is feasible under the meteorological conditions inAdrar region With the increasing wind speed the NPCCOE and emissions of the hybrid renewable energy systemreduce and renewable fraction grows up

Conflict of Interests

None of the authors of this paper has a financial or personalrelationship with other people or organisations that couldinappropriately influence or bias the content of the paper

References

[1] J Koo K Park D Shin and E S Yoon ldquoEconomic evaluationof renewable energy systems under varying scenarios and itsimplications to Korearsquos renewable energy planrdquo Applied Energyvol 88 no 6 pp 2254ndash2260 2011

[2] World Energy Outlook IEA Paris France 2008[3] KHofman andX Li ldquoCanadarsquos energy perspectives andpolicies

for sustainable developmentrdquo Applied Energy vol 86 no 4 pp407ndash415 2009

[4] H Weigt ldquoGermanyrsquos wind energy the potential for fossilcapacity replacement and cost savingrdquo Applied Energy vol 86no 10 pp 1857ndash1863 2009

[5] S A Khan R Rashmi M Z Hussain S Prasad and U CBanerjee ldquoProspects of biodiesel production from microalgaein Indiardquo Renewable and Sustainable Energy Reviews vol 13 no9 pp 2361ndash2372 2009

[6] E S Yoon ldquoA review on sustainable energy recent devel-opments and future prospects of dimethyl ether (DME)rdquo inProceedings of the 10th International Symposium on ProcessSystems Engineering (PSE rsquo09) Bahia Brazil 2009

[7] ldquoAdrar lancement des travaux du projet de la ferme eoliennerdquo2011 httpwwwalgerie360comalgerieadrar-lancement-des-travaux-du-projet-de-la-ferme-eolienne

[8] A Ducluzaux ldquoLrsquoenergie electrique drsquoorigine eoliennerdquo in Con-ference sur lrsquoEnergie Grenoble France 2004

[9] S Nguefeu M Arab X Waymel and F Costa ldquoPWM invertersin decentralized generation systems characterization of thedynamic behavior under utility fault conditionsrdquo InternationalJournal of Distributed Energy Resources vol 2 no 2 pp 101ndash1142006

[10] G Panayiotou S Kalogirou and S Tassou ldquoDesign andsimulation of a PV and a PV-Wind standalone energy systemto power a household applicationrdquo Renewable Energy vol 37no 1 pp 355ndash363 2012

[11] S M Shaahid ldquoReview of research on autonomous wind farmsand solar parks and their feasibility for commercial loads in hotregionsrdquo Renewable and Sustainable Energy Reviews vol 15 no8 pp 3877ndash3887 2011

[12] M A Elhadidy and S M Shaahid ldquoParametric study of hybrid(wind + solar + diesel) power generating systemsrdquo RenewableEnergy vol 21 no 2 pp 129ndash139 2000

12 The Scientific World Journal

[13] S M Shaahid and M A Elhadidy ldquoTechnical and economicassessment of grid-independent hybrid photovoltaic-diesel-battery power systems for commercial loads in desert environ-mentsrdquo Renewable and Sustainable Energy Reviews vol 11 no8 pp 1794ndash1810 2007

[14] D Saheb-Koussa M Haddadi and M Belhamel ldquoEconomicand technical study of a hybrid system (wind-photovoltaic-diesel) for rural electrification in Algeriardquo Applied Energy vol86 no 7-8 pp 1024ndash1030 2009

[15] G J Dalton D A Lockington and T E Baldock ldquoFeasibilityanalysis of stand-alone renewable energy supply options for alarge hotelrdquo Renewable Energy vol 33 no 7 pp 1475ndash14902008

[16] ANCelik ldquoPresent status of photovoltaic energy inTurkey andlife cycle techno-economic analysis of a grid-connected pho-tovoltaic-houserdquo Renewable and Sustainable Energy Reviewsvol 10 no 4 pp 370ndash387 2006

[17] M A H Mondal and M Denich ldquoAssessment of renew-able energy resources potential for electricity generation inBangladeshrdquoRenewable and Sustainable Energy Reviews vol 14no 7 pp 2401ndash2413 2010

[18] D Saheb-Koussa M Haddadi M Belhamel S Hadji and SNouredine ldquoModeling and simulation of the fixed-speedWECS(wind energy conversion system) application to the AlgerianSahara areardquo Energy vol 35 no 10 pp 4116ndash4125 2010

[19] S Rehman I M El-Amin F Ahmad et al ldquoFeasibility studyof hybrid retrofits to an isolated off-grid diesel power plantrdquoRenewable and Sustainable Energy Reviews vol 11 no 4 pp635ndash653 2007

[20] S Singer B Rozenshtein and S Surazi ldquoCharacterization of PVarray output using a small number of measured parametersrdquoSolar Energy vol 32 no 5 pp 603ndash607 1984

[21] D Saheb-Koussa ldquoContribution a lrsquoetude theorique du com-portement drsquoun systeme hybride (eolien- photovoltaıque-diesel) de production drsquoelectricite sans interruptionrdquo Memoirede magister Blida Septembre 2005

[22] G Tsengenes and G Adamidis ldquoInvestigation of the behaviorof a three phase grid-connected photovoltaic system to controlactive and reactive powerrdquo Electric Power Systems Research vol81 no 1 pp 177ndash184 2011

[23] S-K Chung ldquoA phase tracking system for three phase utilityinterface invertersrdquo IEEE Transactions on Power Electronics vol15 no 3 pp 431ndash438 2000

[24] R Dufo-Lopez J L Bernal-Agustın and F Mendoza ldquoDesignand economical analysis of hybrid PV-wind systems connectedto the grid for the intermittent production of hydrogenrdquo EnergyPolicy vol 37 no 8 pp 3082ndash3095 2009

[25] T Burton D Sharpe N Jenkins and E BossanyiWind EnergyHandbook John Wiley amp Sons West Sussex UK 2001

[26] Union for Coordination of Transmission of Electricity ldquoWindPower in the UCTE interconnected Systemrdquo November2004 httpswwwentsoeeufileadminuser upload librarypublicationsceotherreportsWind Power 20041125pdf

[27] E Spooner and A C Williamson ldquoDirect coupled permanentmagnet generators for wind turbine applicationsrdquo IEE Proceed-ings Electric Power Applications vol 143 no 1 pp 1ndash8 1996

[28] N Laverdure S Bacha D Roye B Raison and F DumasldquoElements of modelling of wind power systems with energymanagement two structures in comparisonrdquo in Proceedings ofthe 28th IEEE Annual Conference of the Industrial ElectronicsSociety vol 2 pp 1083ndash1088 November 2002

[29] L Krichen B Francois and A Ouali ldquoA fuzzy logic supervisorfor active and reactive power control of a fixed speed windenergy conversion systemrdquo Electric Power Systems Research vol78 no 3 pp 418ndash424 2008

[30] The Cres Wind Farm ldquo301 MW Demonstration wind farmin Greece Various wind energy technologies in complex Ter-rain topographyrdquo httpwwwcreswindfarmgrsite1ArticlesV47 USpdf

[31] T AckermannWind Power in Power Systems Royal Institute ofTechnology John Wiley amp Sons Stockholm Sweden 2005

[32] F Poitiers Asynchronous generator study and control for thewind energy use [PhD thesis] University of Nantes NantesFrance 2003

[33] M Kacira M Simsek Y Babur and S Demirkol ldquoDeterminingoptimum tilt angles and orientations of photovoltaic panels inSanliurfa Turkeyrdquo Renewable Energy vol 29 no 8 pp 1265ndash1275 2004

[34] D Saheb-Koussa M Belhamel and K Benferhat ldquoContribu-tion a lrsquoetude theorique du comportement drsquoun systeme hybride(eolien- photovoltaıque- diesel) de production drsquoelectricite sansinterruptionrdquo Afrique Science vol 5 no 1 2009

[35] HOMERmdashGetting Started Guide for HOMER Version 21National Renewable Energy Laboratory US Department ofEnergyOffice of EnergyEfficiency andRenewable Energy 2005

[36] C D Barley C B Winn L Flowers and H J Green ldquoOptimalcontrol of remote hybrid power systemsmdashpart I simplifiedmodelrdquo in Proceedings of National Avian-Wind Power PlanningMeeting Washington DC USA 1995

[37] D Saheb-Koussa ldquoEtude technique economique et environ-nementale des systemes decentralises connectes au reseauelectriquerdquo Bulletin des Energies Renouvelables vol 23 pp 15ndash17 2012

[38] V Courtecuisse Supervision drsquoune centrale multi sources a basedrsquoeoliennes et de stockage drsquoenergie connectee au reseau electrique[These de doctorat] Ecole Nationale des Arts et Metiers 2008

TribologyAdvances in

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International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Industrial EngineeringJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Renewable Energy

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StructuresJournal of

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear InstallationsScience and Technology of

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Solar EnergyJournal of

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Wind EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear EnergyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

The Scientific World Journal 5

generation of the system and return the generator torque119879amthe active and reactive power The generator speed Ωas andvoltage 119881

119889119902are the required input parameters obtained by

using the Park transform block PT of the three-phase systeminto the two-phase system [31]

(a) Electric and Magnetic Equations The voltage equationsrepresenting an induction machine [29 32] in an arbitraryreference frame can bewritten in terms of the phase currentsas given by [32]

In the present model the stator and rotor voltages alongthe 119889 and 119902 axes are given by [32]

Using these last ones a model for wound rotor generatorscan be developed This latter has short circuited windingsand as a consequence rotor voltages evaluate to zero (119881

119889119903= 0

and119881119902119903= 0) in this caseTherefore the representative wound

rotor generator equations are

119904120593119889119904= 119881119889119904minus 119877119904119868119889119904+ 120596119904sdot 120593119902119904

119904120593119902119904= 119881119902119904minus 119877119904sdot 119868119902119904minus 120596119904sdot 120593119889119904

119904120593119889119903= minus119877119903sdot 119868119889119903+ (120596119904minus 120596119903) sdot 120593119902119903

119904120593119902119903= minus119877119903sdot 119868119902119903minus (120596119904minus 120596119903)119904119903sdot 120593119889119903

(9)

where

120593119889119904= 119871119904sdot 119868119889119904+ 119871119904119903sdot 119868119889119903

120593119902119904= 119871119904sdot 119868119902119904+ 119871119904119903sdot 119868119902119903

120593119889119903= 119871119903sdot 119868119889119903+ 119871119904119903sdot 119868119889119904

120593119902119903= 119871119903sdot 119868119902119903+ 119871119904119903sdot 119868119902119904

(10)

(b) Evaluation of the Electromagnetic TorqueThe electromag-netic torque has been calculated by employing (11) proposedby [29 32]

Consider

119879am = (3

2)119875 sdot 119871

119904119903(119868119904119902sdot 119868119903119902minus 119868119904119889sdot 119868119903119902) (11)

(c) Evaluation of Real and Reactive Power The active (119875)and reactive (119876) power have been calculated by using thefollowing equations

119875 = 119881

119889119904119868119889119904+ 119881119902119904119868119902119904

119876 = 119881119902119904119868119889119904minus 119881119889119904119868119902119904

(12)

119875119903= minus (119881

119889119903119868119889119903+ 119881119902119903119868119902119903)

119876119903= minus (119881

119902119903119868119889119903+ 119881119889119903119868119902119903) (13)

Using these equations a model for wound rotor gen-erators can be developed This type of generator has shortcircuited windings thus the corresponding rotor voltages goto zero (119881

119889119903= 0 119881

119902119903= 0) Taking into account these

conditions (13) give 119875119903= 0 and 119876

119903= 0

5 Simulation

The energy system components are photovoltaic moduleswind turbine grid and power converter This study developsa suitable assembly of the key parameters such as photovoltaicarray power wind turbine power curve battery storageand converter capacity to match the predefined load Foreconomic analysis the cost including the initial capitalreplacement cost and operating and maintenance cost areconsidered as simulating conditions

Photovoltaic Arrays The initial cost of photovoltaic arraysmay vary from $400 to $500 per watt Considering a moreoptimistic system the costs of installation replacement andmaintenance of a 1 kW solar energy system are taken as $5000and $4000 Sizes of the photovoltaic arrays are varied between0 100 200 300 400 500 600 and 700 kW

Wind Turbine Energy generation formwind turbine dependson wind speed variations The wind turbine rated powershould be greater than average electrical load Thereforeaccording to the load data discussed above the average loadis around a 77MW Therefore a VESTAS 47ndash660 turbinemanufactured by VESTAS wind power is used Its ratedpower is 660 kWAC

Grid Grid exists as themain power component in this hybridrenewable energy system Moreover grid has the functionsas a storage system so a grid power system does not need abattery

Power Converter A converter is required for systems inwhichDC components serve an AD load or vice versa For a 1 kWsystem the installation and replacement costs are taken as$800 and $750 respectively Lifetime of a unit is consideredto be 25 years with an efficiency of 90

For the considered system it is necessary to simulateduring all the hours in a complete year all the possibledesigns Variables are considered hourly and therefore therewill be 8760 in a year At the end of the simulation we willknow the quantity of electrical energy from a PV generatorinjected to the grid in the year and the electrical energy fromwind turbines that is also injected [24]

As a sample site the Adrar site has been chosen and thefollowing data are used as input

(i) the hourly global and diffuse radiationmeasured on ahorizontal plane and the ambient temperature Fromthe data collected on a horizontal plane the compo-nents of the solar irradiance have been projected ontothe surface of a PV panel Moreover the inclinationof the used solar panel corresponds to the yearlyoptimum slope as indicated in [33]

(ii) the measured wind speeds and the electromechanicalcharacteristics of a wind turbine of the VESTAS47ndash660 type This is a three-blade model with adiameter of 46m a speed multiplier ratio of 505and a hub height of 100m [30] Moreover the power

6 The Scientific World Journal

0 5 10 15 20 25 300

100200300400500600700

Wind speed (ms)

Pow

er o

utpu

t (kW

)

Figure 5 Typical wind turbine power curve

produced by this wind turbine has been calculatedusing the power curve (Figure 5) provided by themanufacturer

51 Power Produced by the Photovoltaic Generator For calcu-lating the output characteristics of the photovoltaic systema program has been developed which requires the globalincident radiation and the air temperature as main inputdata So the research unit in renewable energy URER ofAdrar provided hourly measured values over a full year ofglobal and diffuse irradiation on a horizontal plane togetherwith those related to the ambient temperature From theglobal radiations on the horizontal plane collected data andbased on the equations given in [21] the developed programcalculates the overall incident irradiations on the surface ofthe PV panel These latter and the ambient temperatures areused to calculate the power and current delivered by the PVgenerator

The obtained results are presented in Figure 6

52 Power Produced by the Wind Generator Generally tocalculate the power generated by a wind turbine we use thedata drawn from the main characteristic 119901 = 119891(V) related tothe turbine and supplied by the manufacturer (Figure 5) Inthis study using the equations given in [34] the hourly valuesof the wind turbine are read from a file in which the windspeed for each hour of the year is given

By using the power curve of the wind turbine the outputpower is calculated With the speed at the hub of the windturbine and using its power curve the power that the windturbine provides in an hour h Pwminush (W) is obtained If thereare 119873

119908wind turbine connected in parallel this amount is

multiplied by119873119908[24] The obtained results are as follows

(i) Figure 7(a) shows the evolution of hourly windspeeds

(ii) Figure 7(b) shows the plots of the active power devel-oped at the asynchronous machine terminals

(iii) Figure 7(c) shows the plots of the reactive powerdeveloped at the asynchronous machine terminals

(iv) Figure 7(d) shows the current delivered by the windgenerator

0 1000 2000 3000 4000 5000 6000 7000 8000 900005

101520253035404550

Time (h)

Tem

pera

ture

(∘C)

(a)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

200400600800

10001200

Time (h)

Incli

ned

glob

al

radi

atio

n (w

m2)

(b)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

20406080

100120140160180

Time (h)

Pow

er p

rodu

ced

by th

ePV

gen

erat

or (W

)

(c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

012345

Time (h)

minus5minus4minus3minus2minus1

Thre

e-ph

ase c

urre

nts p

rodu

ced

by th

e PV

gen

erat

or (A

)

(d)

Figure 6 Representation of climatic characteristics power andcurrent produced by the photovoltaic module BP SX 150 S installedon the Adrar site

53 Management of the System [24] Figure 8 presents theMATLAB-SIMULINK program diagram of the hybrid sys-tem In this system the power delivered by each of the systemdevices (PV or wind) should be managed in such a way thatthe surplus of power produced by any of them is conductedto the grid without giving rise to any phenomena leading to

The Scientific World Journal 7

0 1000 2000 3000 4000 5000 6000 7000 8000 900005

10152025

Time (h)

Win

d sp

eed

(ms

)

(a)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0

Time (h)

Activ

e pow

er (k

W)

minus6

minus5

minus4

minus3

minus2

minus1

times105

(b)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

051

152

253

354

Time (h)

Reac

tive p

ower

(kVA

)

times105

(c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0200400600800

Time (h)

Thre

e-ph

ase s

tato

r cur

rent

s (A

)

minus800

minus600

minus400

minus200

(d)

Figure 7 Simulation results

a disturbance of any of these devices These last ones dis-turbed by generating harmonics that may distort the gridwaveform flickers high frequency wave frequency fluctua-tion under voltage and over voltage

Thus for each hour of the year h the amount of electricalenergy available at the transformer connected to the grid isevaluated by [24]

119875AC-h = (119875pv-h120578INV + 119875w-h)120578TR (14)

where 120578INV is the inverter efficiency rate modeled as avariable depending on the power delivered by the inverter120578TR is the efficiency rate of the transformer connected tothe electrical grid including the losses of power in thetransmission lines 119875w-h is the power (W) generated by thewind generator within an hour time and 119875pv-h is the power(W) generated by the PV generator within an hour time

However the amount of power that can be injected eachhour into the grid 119875EE-h (W) cannot be higher than theallowed evacuation capacity at the point of connection to thegrid 119875MAX-GRID (W) [24]

119875EE-h = min (119875MAX-GRID 119875AC-h) (15)

Where 119875MAX-GRID (W) is the maximum power evacuationvalue allowed which the Algerian law fixes for 20 to 30 ofthe line thermal limit at the point of connection

The amount of energy to be injected into the grid obtainedfrom the PV generator (119875EE-PV-h) and the wind generator119875EE-w-h will be calculated as indicated by Figure 9

The results obtained in the case of the previouslydescribed scenario are represented in Figure 10 which showsthat the hourly produced power injected into the grid is lowerthan 119875MAX-GRID

54 Total Annual Production The contribution of each partof the hybrid system (PV-wind-grid) to satisfy a specificload of the 34815MWhyr is shown in Figure 11 It is to benoted that the PV generator produces only 365MWhyearand covers only 1 of the load The wind generator inturn produces 7225MWhyear which constitute nearly 21of load requirements against a covered load rate of 78(27225MWhyear) provided by the conventional electricitygrid [35]These results are explained by the fact that HOMERsoftware promotes the wind system because of itrsquos efficiencywhich is very higher than that of PV system

55 Hours of Operation Figure 12 represents the durationof the operation (in hours) of each of the renewable energyequipment of the hybrid PV-wind-Grid system It is foundthat the wind generator works over the longest time intervalwith a 48 rate of the total period followed by the PVgenerator and inverter with a rate of 26 for each

56 Economic Aspects The HOMER optimization model[24] uses relatively simple strategies based on the ones studiedby Barley et al [36] and it is able to obtain an optimal designof a hybrid system by selecting the most appropriate strategy

Thus from an economic point of view it is found thatthe system composed of a 200 kW rated PV system andthree 660 kW rated wind turbines can cover 22 of theelectrical energy demand and has a net present cost (NPC)of $177 million and a cost of energy per kilowatt hour(COE) of $0399kWh A comparative economic analysisbetween the conventional and the optimized system (PV-wind system) employing HOMER software package [35] hasbeen performed and the results are presented in Table 1From these results it is noticed that the hybrid system (PV-wind-grid) is more economical than the conventional system

8 The Scientific World Journal

Yearly day number

Yearly day number 1

Tsvtsv

09

Transform

Preflight

09Convert

-C-

In1 cem

Wind system

vvvWind velocity

Scope

Result PV

Result

In1

In2

In3

In4

PV system

GHR

Global horiz rad

In1

In2

In3

PE1

PPV1

Out1

Gestion

difHR

Diffuse horiz rad1

Iabc

AP

AP

RP

Tt

Wt

Wmas

Iabc

Isabc

Isabc

Figure 8 Management of the system

PV system priority

No

No

NoNo Yes

Yes

Yes

Yes

Ppv-h Pw-h

Ppv-h Pw-h 120578inv 120578TR

PEE-h lt PMAX-GRID

PEE-h = Ppv-h120578INV 120578TR

120578inv 120578TR = Pmax-grid

Pw-h120578TR = PMAX-GRID

PEE-w-h = PMAX-GRIDPEE-PV-h = 0 PEE-PV-h = PMAX-GRIDPw-h120578TR

PEE-PV-h = PMAX-GRID

PEE-w-h = 0

PEE-w-h = 0 PEE-w-h = 0

PEE-w-h = 0

PEE-h = PEE-PV-h + PEE-w-h

PEE-PV-h = PPV-h120578INV120578TR

PEE-w-h = Pw-h TR120578middot

Figure 9 Flowchart for calculating the amount of power to be inject into the grid

The Scientific World Journal 9

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

500

1000

1500

2000

2500

3000

Time (h)

Pow

er (k

W)

Injected power into the gridPMAX-GRID

Figure 10 Power injected into the grid

1365 MWhyr

7225 MWhyr21

27225 MWhyr78

Photovoltaic systemWind systemGrid

Figure 11 Structure of the production system (PV-wind-grid)

26

48

26

Photovoltaic systemWind systemConverter

Figure 12 Distribution of operation hours of each of the renewableenergy equipment of the hybrid PV-wind-Grid system

05 1 15 2 25 3 35 4 450

20406080

100120140

Photovoltaic systemWind system

GridConverter

106$

Figure 13 Net present cost

05 1 15 2 25 3 35 4 4502468

1012

Photovoltaic systemWind system

GridConverter

106$yr

Figure 14 Annual net cost

Table 1 Cost comparison between a standard system (grid) and ahybrid system (PV-wind-grid)

Cost Conventional systemgrid

Hybrid systemPV-wind-grid

NPC ($yr) 177714200 177090600COE ($kWh) 04 0399

Table 2 Emissions comparison between a standard system (grid)and a hybrid system (PV-wind-grid)

Pollutant Kgyr Conventional systemgrid

Hybrid systemPV-wind-grid

CO2 21965160 17199524SO2 95229 74568NO119909

46572 36467

if the price per produced kWh of the latter is set to $04kWhHowever the net present cost is calculated for a projectlifetime period of 25 years and on the basis of an interest rateof 6 Figures 13 and 14 show the details of the correspondingcosts to each of the systems and the related annual costs [37]

57 Environmental Aspects The results regarding the effectsof each system configuration that is the conventional gridand the hybrid system (PV-wind-grid) on the environmentobtained by again using HOMER software in the caseof the Adrar site are shown in Table 2 [37] In this tablethe quantities of the main gases that are harmful to theenvironment including CO

2 SO2 and NOx are presented

10 The Scientific World Journal

160

165

170

175

180

72 76 80 84 88036

037

038

039

040

041

Leve

lized

cost

of en

ergy

($k

Wh)

Levelized cost of energy versus wind speed

Wind speed (ms)

Tota

l net

pre

sent

cost

($)

Levelized cost of energyTotal net present cost

Fixed

times106

Global solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 15 The relationship between cost and wind speed

72 76 80 84 88000

005

010

015

020

025

Rene

wab

le fr

actio

n

Renewable fraction versus wind speed

Wind speed (ms)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 16 The relationship between RF and wind speed

From these results it is found that the PV-wind-grid hybridsystem produces a reduction in the carbon dioxide gassulfur dioxide and nitrogen oxide rates by respectively 2022 and 22 as compared to the quantities produced by theconventional system [37]

58 Sensitivity Results In this study sensitivity analysis wasdone to study the effects of variation in the solar irradiationand wind speed The simulation software simulates thelong-term implementation of the hybrid system based ontheir respective search size for the predefined sensitivityvalues of the componentsThe emissions renewable fractionNPC and COE are simulated based on the three sensitivityvariables wind speed (ms) solar irradiation (kWm2day)and grid electricity price ($kWh) A long-term simulationfor every possible system combination and configurationwas done for a one year period (from January 1st 2005 toDecember 31st 2005) In the present case solar irradiationis set as sensitivity variables 119866 = 35 45 5 55 572 788 kWm2day while wind speed are V = 69 7 75 78 888msMoreover the grid electricity price is also defined as asensitivity variable (119901 = 01 02 03 04 $kWh) A total of 192

72 76 80 84 8816171819202122

Wind speed (ms)

times106

CO2

emiss

ions

(kg

yr)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

CO2 emissions versus wind speed

Figure 17The relationship betweenCO2emissions andwind speed

72 76 80 84 8830405060708090

100

Wind speed (ms)SO

2em

issio

ns (k

gyr

) SO2 emissions versus wind speed

SO2 emissionsNOx emissions

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 18 The relationship between sulfur dioxide and nitrogenoxide emissions and wind speed

sensitivity cases were tried for each system configurationThesimulation timewas 23minutes and 46 seconds on a personalcomputer with Intel CORE Intel Core Duo Processor of253GHz and a RAM of 2GBThe sensitivity results in termsof solar irradiation wind speed and grid electricity priceanalyze the feasibility of each system Here the feasibilityof hybrid renewable energy system is analyzed based onemission reduction and cost saving This type of sensitivityanalysis of the systems provides information that a particularsystem would be optimal at certain sensitivity variables [19]The PV-wind system is feasible when the grid electricityprice is more than $04 kWh Under this condition the RFcan be between 021 and 022 A PV-wind system is feasiblewhen global solar irradiation is more than 572 kWhm2 perday and the grid electricity price is more expensive than$04 kWh Based on the optimization results wind energyproduction shows a bigger proportion of energy generationthan solar While the solar power occupies less than 1 of thetotal energy generation wind power occupies approximatelya quarter

Therefore the wind energy resource has more impact onthe implementation Figures 15ndash18 reflect the cost renewablefraction and emission variation dependent on the sensitivityvariable wind speed The NPC and COE of the hybrid power

The Scientific World Journal 11

system reduce when the wind speed increases from 69ms to88ms Figure 15

Simultaneously as seen in Figure 16 renewable fractionrises sharply from 0 to 16 (when wind speed increases from69 to 7ms) and then steadily increases to 24 at a slowerrate In addition as shown in Figures 17 and 18 the mainemissions of carbon dioxide sulfur dioxide and nitrogenoxide persistently decrease 22

6 Problems Encountered in DecentralizedSystems [37]

The major difficulty associated with decentralized energysources is that they generally do not participate in ancillaryservices (voltage control frequency ability to operate instandalone mode etc) This is especially true for renewableenergy sources whose power flow is unpredictable and veryvolatile The integration of decentralized energy generationinto power networks raises the following problems

(i) random and unpredictable energy production (windsolar)

(ii) lack of power-frequency control(iii) no voltage adjustment performed(iv) sensitivity to voltage dips(v) significant sensitivity to changes in primary source

(wind solar) energy levels

The failure to take part in system services makes thistype of sources behave as passive generators from theelectrical energy generation point of view The penetrationof distributed energy generation must be limited from 20 to30 of the consumed power in order to guarantee acceptablesystem stability [19]

7 Conclusion

This study is related to the technical economic and envi-ronmental impact of grid-connected decentralized systems towhich an appropriatemanagement of energy is applied andbymeans of which are developed models of the different partsThe solar and wind energy resource data are collected fromthe weather station of Adrar which is a typical arid regionThe most significant results are as follows

The power that any subsystem can deliver depends on theweather conditions of the considered site

The PV based system only covers 1 of the total loadconsumption On the other hand the wind generator con-tribution amounts to about 21 of the energy productionwhile the remaining 78 are supplied by the conventionalelectricity grid

From an economic point of view it is found that for theAdrar site which is characterized by a high wind potentialthe hybrid system is competitive compared with the conven-tional system with a cost of the energy COE produced by thenetwork equal to $04kWh since the estimated COE relatedto the hybrid system is equal to $0399kWh based on anaverage wind speed greater than or equal to 6ms

From an environmental standpoint the rates of green-house gases (CO

2 SO2 andNOx) emissions are reduced from

20 to 22 in the case of a hybrid system compared with theconventional system

The sensitivity analysis indicates that PV-wind hybridsystem is feasible under the meteorological conditions inAdrar region With the increasing wind speed the NPCCOE and emissions of the hybrid renewable energy systemreduce and renewable fraction grows up

Conflict of Interests

None of the authors of this paper has a financial or personalrelationship with other people or organisations that couldinappropriately influence or bias the content of the paper

References

[1] J Koo K Park D Shin and E S Yoon ldquoEconomic evaluationof renewable energy systems under varying scenarios and itsimplications to Korearsquos renewable energy planrdquo Applied Energyvol 88 no 6 pp 2254ndash2260 2011

[2] World Energy Outlook IEA Paris France 2008[3] KHofman andX Li ldquoCanadarsquos energy perspectives andpolicies

for sustainable developmentrdquo Applied Energy vol 86 no 4 pp407ndash415 2009

[4] H Weigt ldquoGermanyrsquos wind energy the potential for fossilcapacity replacement and cost savingrdquo Applied Energy vol 86no 10 pp 1857ndash1863 2009

[5] S A Khan R Rashmi M Z Hussain S Prasad and U CBanerjee ldquoProspects of biodiesel production from microalgaein Indiardquo Renewable and Sustainable Energy Reviews vol 13 no9 pp 2361ndash2372 2009

[6] E S Yoon ldquoA review on sustainable energy recent devel-opments and future prospects of dimethyl ether (DME)rdquo inProceedings of the 10th International Symposium on ProcessSystems Engineering (PSE rsquo09) Bahia Brazil 2009

[7] ldquoAdrar lancement des travaux du projet de la ferme eoliennerdquo2011 httpwwwalgerie360comalgerieadrar-lancement-des-travaux-du-projet-de-la-ferme-eolienne

[8] A Ducluzaux ldquoLrsquoenergie electrique drsquoorigine eoliennerdquo in Con-ference sur lrsquoEnergie Grenoble France 2004

[9] S Nguefeu M Arab X Waymel and F Costa ldquoPWM invertersin decentralized generation systems characterization of thedynamic behavior under utility fault conditionsrdquo InternationalJournal of Distributed Energy Resources vol 2 no 2 pp 101ndash1142006

[10] G Panayiotou S Kalogirou and S Tassou ldquoDesign andsimulation of a PV and a PV-Wind standalone energy systemto power a household applicationrdquo Renewable Energy vol 37no 1 pp 355ndash363 2012

[11] S M Shaahid ldquoReview of research on autonomous wind farmsand solar parks and their feasibility for commercial loads in hotregionsrdquo Renewable and Sustainable Energy Reviews vol 15 no8 pp 3877ndash3887 2011

[12] M A Elhadidy and S M Shaahid ldquoParametric study of hybrid(wind + solar + diesel) power generating systemsrdquo RenewableEnergy vol 21 no 2 pp 129ndash139 2000

12 The Scientific World Journal

[13] S M Shaahid and M A Elhadidy ldquoTechnical and economicassessment of grid-independent hybrid photovoltaic-diesel-battery power systems for commercial loads in desert environ-mentsrdquo Renewable and Sustainable Energy Reviews vol 11 no8 pp 1794ndash1810 2007

[14] D Saheb-Koussa M Haddadi and M Belhamel ldquoEconomicand technical study of a hybrid system (wind-photovoltaic-diesel) for rural electrification in Algeriardquo Applied Energy vol86 no 7-8 pp 1024ndash1030 2009

[15] G J Dalton D A Lockington and T E Baldock ldquoFeasibilityanalysis of stand-alone renewable energy supply options for alarge hotelrdquo Renewable Energy vol 33 no 7 pp 1475ndash14902008

[16] ANCelik ldquoPresent status of photovoltaic energy inTurkey andlife cycle techno-economic analysis of a grid-connected pho-tovoltaic-houserdquo Renewable and Sustainable Energy Reviewsvol 10 no 4 pp 370ndash387 2006

[17] M A H Mondal and M Denich ldquoAssessment of renew-able energy resources potential for electricity generation inBangladeshrdquoRenewable and Sustainable Energy Reviews vol 14no 7 pp 2401ndash2413 2010

[18] D Saheb-Koussa M Haddadi M Belhamel S Hadji and SNouredine ldquoModeling and simulation of the fixed-speedWECS(wind energy conversion system) application to the AlgerianSahara areardquo Energy vol 35 no 10 pp 4116ndash4125 2010

[19] S Rehman I M El-Amin F Ahmad et al ldquoFeasibility studyof hybrid retrofits to an isolated off-grid diesel power plantrdquoRenewable and Sustainable Energy Reviews vol 11 no 4 pp635ndash653 2007

[20] S Singer B Rozenshtein and S Surazi ldquoCharacterization of PVarray output using a small number of measured parametersrdquoSolar Energy vol 32 no 5 pp 603ndash607 1984

[21] D Saheb-Koussa ldquoContribution a lrsquoetude theorique du com-portement drsquoun systeme hybride (eolien- photovoltaıque-diesel) de production drsquoelectricite sans interruptionrdquo Memoirede magister Blida Septembre 2005

[22] G Tsengenes and G Adamidis ldquoInvestigation of the behaviorof a three phase grid-connected photovoltaic system to controlactive and reactive powerrdquo Electric Power Systems Research vol81 no 1 pp 177ndash184 2011

[23] S-K Chung ldquoA phase tracking system for three phase utilityinterface invertersrdquo IEEE Transactions on Power Electronics vol15 no 3 pp 431ndash438 2000

[24] R Dufo-Lopez J L Bernal-Agustın and F Mendoza ldquoDesignand economical analysis of hybrid PV-wind systems connectedto the grid for the intermittent production of hydrogenrdquo EnergyPolicy vol 37 no 8 pp 3082ndash3095 2009

[25] T Burton D Sharpe N Jenkins and E BossanyiWind EnergyHandbook John Wiley amp Sons West Sussex UK 2001

[26] Union for Coordination of Transmission of Electricity ldquoWindPower in the UCTE interconnected Systemrdquo November2004 httpswwwentsoeeufileadminuser upload librarypublicationsceotherreportsWind Power 20041125pdf

[27] E Spooner and A C Williamson ldquoDirect coupled permanentmagnet generators for wind turbine applicationsrdquo IEE Proceed-ings Electric Power Applications vol 143 no 1 pp 1ndash8 1996

[28] N Laverdure S Bacha D Roye B Raison and F DumasldquoElements of modelling of wind power systems with energymanagement two structures in comparisonrdquo in Proceedings ofthe 28th IEEE Annual Conference of the Industrial ElectronicsSociety vol 2 pp 1083ndash1088 November 2002

[29] L Krichen B Francois and A Ouali ldquoA fuzzy logic supervisorfor active and reactive power control of a fixed speed windenergy conversion systemrdquo Electric Power Systems Research vol78 no 3 pp 418ndash424 2008

[30] The Cres Wind Farm ldquo301 MW Demonstration wind farmin Greece Various wind energy technologies in complex Ter-rain topographyrdquo httpwwwcreswindfarmgrsite1ArticlesV47 USpdf

[31] T AckermannWind Power in Power Systems Royal Institute ofTechnology John Wiley amp Sons Stockholm Sweden 2005

[32] F Poitiers Asynchronous generator study and control for thewind energy use [PhD thesis] University of Nantes NantesFrance 2003

[33] M Kacira M Simsek Y Babur and S Demirkol ldquoDeterminingoptimum tilt angles and orientations of photovoltaic panels inSanliurfa Turkeyrdquo Renewable Energy vol 29 no 8 pp 1265ndash1275 2004

[34] D Saheb-Koussa M Belhamel and K Benferhat ldquoContribu-tion a lrsquoetude theorique du comportement drsquoun systeme hybride(eolien- photovoltaıque- diesel) de production drsquoelectricite sansinterruptionrdquo Afrique Science vol 5 no 1 2009

[35] HOMERmdashGetting Started Guide for HOMER Version 21National Renewable Energy Laboratory US Department ofEnergyOffice of EnergyEfficiency andRenewable Energy 2005

[36] C D Barley C B Winn L Flowers and H J Green ldquoOptimalcontrol of remote hybrid power systemsmdashpart I simplifiedmodelrdquo in Proceedings of National Avian-Wind Power PlanningMeeting Washington DC USA 1995

[37] D Saheb-Koussa ldquoEtude technique economique et environ-nementale des systemes decentralises connectes au reseauelectriquerdquo Bulletin des Energies Renouvelables vol 23 pp 15ndash17 2012

[38] V Courtecuisse Supervision drsquoune centrale multi sources a basedrsquoeoliennes et de stockage drsquoenergie connectee au reseau electrique[These de doctorat] Ecole Nationale des Arts et Metiers 2008

TribologyAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Industrial EngineeringJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Renewable Energy

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StructuresJournal of

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear InstallationsScience and Technology of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Solar EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Wind EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear EnergyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

6 The Scientific World Journal

0 5 10 15 20 25 300

100200300400500600700

Wind speed (ms)

Pow

er o

utpu

t (kW

)

Figure 5 Typical wind turbine power curve

produced by this wind turbine has been calculatedusing the power curve (Figure 5) provided by themanufacturer

51 Power Produced by the Photovoltaic Generator For calcu-lating the output characteristics of the photovoltaic systema program has been developed which requires the globalincident radiation and the air temperature as main inputdata So the research unit in renewable energy URER ofAdrar provided hourly measured values over a full year ofglobal and diffuse irradiation on a horizontal plane togetherwith those related to the ambient temperature From theglobal radiations on the horizontal plane collected data andbased on the equations given in [21] the developed programcalculates the overall incident irradiations on the surface ofthe PV panel These latter and the ambient temperatures areused to calculate the power and current delivered by the PVgenerator

The obtained results are presented in Figure 6

52 Power Produced by the Wind Generator Generally tocalculate the power generated by a wind turbine we use thedata drawn from the main characteristic 119901 = 119891(V) related tothe turbine and supplied by the manufacturer (Figure 5) Inthis study using the equations given in [34] the hourly valuesof the wind turbine are read from a file in which the windspeed for each hour of the year is given

By using the power curve of the wind turbine the outputpower is calculated With the speed at the hub of the windturbine and using its power curve the power that the windturbine provides in an hour h Pwminush (W) is obtained If thereare 119873

119908wind turbine connected in parallel this amount is

multiplied by119873119908[24] The obtained results are as follows

(i) Figure 7(a) shows the evolution of hourly windspeeds

(ii) Figure 7(b) shows the plots of the active power devel-oped at the asynchronous machine terminals

(iii) Figure 7(c) shows the plots of the reactive powerdeveloped at the asynchronous machine terminals

(iv) Figure 7(d) shows the current delivered by the windgenerator

0 1000 2000 3000 4000 5000 6000 7000 8000 900005

101520253035404550

Time (h)

Tem

pera

ture

(∘C)

(a)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

200400600800

10001200

Time (h)

Incli

ned

glob

al

radi

atio

n (w

m2)

(b)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

20406080

100120140160180

Time (h)

Pow

er p

rodu

ced

by th

ePV

gen

erat

or (W

)

(c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

012345

Time (h)

minus5minus4minus3minus2minus1

Thre

e-ph

ase c

urre

nts p

rodu

ced

by th

e PV

gen

erat

or (A

)

(d)

Figure 6 Representation of climatic characteristics power andcurrent produced by the photovoltaic module BP SX 150 S installedon the Adrar site

53 Management of the System [24] Figure 8 presents theMATLAB-SIMULINK program diagram of the hybrid sys-tem In this system the power delivered by each of the systemdevices (PV or wind) should be managed in such a way thatthe surplus of power produced by any of them is conductedto the grid without giving rise to any phenomena leading to

The Scientific World Journal 7

0 1000 2000 3000 4000 5000 6000 7000 8000 900005

10152025

Time (h)

Win

d sp

eed

(ms

)

(a)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0

Time (h)

Activ

e pow

er (k

W)

minus6

minus5

minus4

minus3

minus2

minus1

times105

(b)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

051

152

253

354

Time (h)

Reac

tive p

ower

(kVA

)

times105

(c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0200400600800

Time (h)

Thre

e-ph

ase s

tato

r cur

rent

s (A

)

minus800

minus600

minus400

minus200

(d)

Figure 7 Simulation results

a disturbance of any of these devices These last ones dis-turbed by generating harmonics that may distort the gridwaveform flickers high frequency wave frequency fluctua-tion under voltage and over voltage

Thus for each hour of the year h the amount of electricalenergy available at the transformer connected to the grid isevaluated by [24]

119875AC-h = (119875pv-h120578INV + 119875w-h)120578TR (14)

where 120578INV is the inverter efficiency rate modeled as avariable depending on the power delivered by the inverter120578TR is the efficiency rate of the transformer connected tothe electrical grid including the losses of power in thetransmission lines 119875w-h is the power (W) generated by thewind generator within an hour time and 119875pv-h is the power(W) generated by the PV generator within an hour time

However the amount of power that can be injected eachhour into the grid 119875EE-h (W) cannot be higher than theallowed evacuation capacity at the point of connection to thegrid 119875MAX-GRID (W) [24]

119875EE-h = min (119875MAX-GRID 119875AC-h) (15)

Where 119875MAX-GRID (W) is the maximum power evacuationvalue allowed which the Algerian law fixes for 20 to 30 ofthe line thermal limit at the point of connection

The amount of energy to be injected into the grid obtainedfrom the PV generator (119875EE-PV-h) and the wind generator119875EE-w-h will be calculated as indicated by Figure 9

The results obtained in the case of the previouslydescribed scenario are represented in Figure 10 which showsthat the hourly produced power injected into the grid is lowerthan 119875MAX-GRID

54 Total Annual Production The contribution of each partof the hybrid system (PV-wind-grid) to satisfy a specificload of the 34815MWhyr is shown in Figure 11 It is to benoted that the PV generator produces only 365MWhyearand covers only 1 of the load The wind generator inturn produces 7225MWhyear which constitute nearly 21of load requirements against a covered load rate of 78(27225MWhyear) provided by the conventional electricitygrid [35]These results are explained by the fact that HOMERsoftware promotes the wind system because of itrsquos efficiencywhich is very higher than that of PV system

55 Hours of Operation Figure 12 represents the durationof the operation (in hours) of each of the renewable energyequipment of the hybrid PV-wind-Grid system It is foundthat the wind generator works over the longest time intervalwith a 48 rate of the total period followed by the PVgenerator and inverter with a rate of 26 for each

56 Economic Aspects The HOMER optimization model[24] uses relatively simple strategies based on the ones studiedby Barley et al [36] and it is able to obtain an optimal designof a hybrid system by selecting the most appropriate strategy

Thus from an economic point of view it is found thatthe system composed of a 200 kW rated PV system andthree 660 kW rated wind turbines can cover 22 of theelectrical energy demand and has a net present cost (NPC)of $177 million and a cost of energy per kilowatt hour(COE) of $0399kWh A comparative economic analysisbetween the conventional and the optimized system (PV-wind system) employing HOMER software package [35] hasbeen performed and the results are presented in Table 1From these results it is noticed that the hybrid system (PV-wind-grid) is more economical than the conventional system

8 The Scientific World Journal

Yearly day number

Yearly day number 1

Tsvtsv

09

Transform

Preflight

09Convert

-C-

In1 cem

Wind system

vvvWind velocity

Scope

Result PV

Result

In1

In2

In3

In4

PV system

GHR

Global horiz rad

In1

In2

In3

PE1

PPV1

Out1

Gestion

difHR

Diffuse horiz rad1

Iabc

AP

AP

RP

Tt

Wt

Wmas

Iabc

Isabc

Isabc

Figure 8 Management of the system

PV system priority

No

No

NoNo Yes

Yes

Yes

Yes

Ppv-h Pw-h

Ppv-h Pw-h 120578inv 120578TR

PEE-h lt PMAX-GRID

PEE-h = Ppv-h120578INV 120578TR

120578inv 120578TR = Pmax-grid

Pw-h120578TR = PMAX-GRID

PEE-w-h = PMAX-GRIDPEE-PV-h = 0 PEE-PV-h = PMAX-GRIDPw-h120578TR

PEE-PV-h = PMAX-GRID

PEE-w-h = 0

PEE-w-h = 0 PEE-w-h = 0

PEE-w-h = 0

PEE-h = PEE-PV-h + PEE-w-h

PEE-PV-h = PPV-h120578INV120578TR

PEE-w-h = Pw-h TR120578middot

Figure 9 Flowchart for calculating the amount of power to be inject into the grid

The Scientific World Journal 9

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

500

1000

1500

2000

2500

3000

Time (h)

Pow

er (k

W)

Injected power into the gridPMAX-GRID

Figure 10 Power injected into the grid

1365 MWhyr

7225 MWhyr21

27225 MWhyr78

Photovoltaic systemWind systemGrid

Figure 11 Structure of the production system (PV-wind-grid)

26

48

26

Photovoltaic systemWind systemConverter

Figure 12 Distribution of operation hours of each of the renewableenergy equipment of the hybrid PV-wind-Grid system

05 1 15 2 25 3 35 4 450

20406080

100120140

Photovoltaic systemWind system

GridConverter

106$

Figure 13 Net present cost

05 1 15 2 25 3 35 4 4502468

1012

Photovoltaic systemWind system

GridConverter

106$yr

Figure 14 Annual net cost

Table 1 Cost comparison between a standard system (grid) and ahybrid system (PV-wind-grid)

Cost Conventional systemgrid

Hybrid systemPV-wind-grid

NPC ($yr) 177714200 177090600COE ($kWh) 04 0399

Table 2 Emissions comparison between a standard system (grid)and a hybrid system (PV-wind-grid)

Pollutant Kgyr Conventional systemgrid

Hybrid systemPV-wind-grid

CO2 21965160 17199524SO2 95229 74568NO119909

46572 36467

if the price per produced kWh of the latter is set to $04kWhHowever the net present cost is calculated for a projectlifetime period of 25 years and on the basis of an interest rateof 6 Figures 13 and 14 show the details of the correspondingcosts to each of the systems and the related annual costs [37]

57 Environmental Aspects The results regarding the effectsof each system configuration that is the conventional gridand the hybrid system (PV-wind-grid) on the environmentobtained by again using HOMER software in the caseof the Adrar site are shown in Table 2 [37] In this tablethe quantities of the main gases that are harmful to theenvironment including CO

2 SO2 and NOx are presented

10 The Scientific World Journal

160

165

170

175

180

72 76 80 84 88036

037

038

039

040

041

Leve

lized

cost

of en

ergy

($k

Wh)

Levelized cost of energy versus wind speed

Wind speed (ms)

Tota

l net

pre

sent

cost

($)

Levelized cost of energyTotal net present cost

Fixed

times106

Global solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 15 The relationship between cost and wind speed

72 76 80 84 88000

005

010

015

020

025

Rene

wab

le fr

actio

n

Renewable fraction versus wind speed

Wind speed (ms)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 16 The relationship between RF and wind speed

From these results it is found that the PV-wind-grid hybridsystem produces a reduction in the carbon dioxide gassulfur dioxide and nitrogen oxide rates by respectively 2022 and 22 as compared to the quantities produced by theconventional system [37]

58 Sensitivity Results In this study sensitivity analysis wasdone to study the effects of variation in the solar irradiationand wind speed The simulation software simulates thelong-term implementation of the hybrid system based ontheir respective search size for the predefined sensitivityvalues of the componentsThe emissions renewable fractionNPC and COE are simulated based on the three sensitivityvariables wind speed (ms) solar irradiation (kWm2day)and grid electricity price ($kWh) A long-term simulationfor every possible system combination and configurationwas done for a one year period (from January 1st 2005 toDecember 31st 2005) In the present case solar irradiationis set as sensitivity variables 119866 = 35 45 5 55 572 788 kWm2day while wind speed are V = 69 7 75 78 888msMoreover the grid electricity price is also defined as asensitivity variable (119901 = 01 02 03 04 $kWh) A total of 192

72 76 80 84 8816171819202122

Wind speed (ms)

times106

CO2

emiss

ions

(kg

yr)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

CO2 emissions versus wind speed

Figure 17The relationship betweenCO2emissions andwind speed

72 76 80 84 8830405060708090

100

Wind speed (ms)SO

2em

issio

ns (k

gyr

) SO2 emissions versus wind speed

SO2 emissionsNOx emissions

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 18 The relationship between sulfur dioxide and nitrogenoxide emissions and wind speed

sensitivity cases were tried for each system configurationThesimulation timewas 23minutes and 46 seconds on a personalcomputer with Intel CORE Intel Core Duo Processor of253GHz and a RAM of 2GBThe sensitivity results in termsof solar irradiation wind speed and grid electricity priceanalyze the feasibility of each system Here the feasibilityof hybrid renewable energy system is analyzed based onemission reduction and cost saving This type of sensitivityanalysis of the systems provides information that a particularsystem would be optimal at certain sensitivity variables [19]The PV-wind system is feasible when the grid electricityprice is more than $04 kWh Under this condition the RFcan be between 021 and 022 A PV-wind system is feasiblewhen global solar irradiation is more than 572 kWhm2 perday and the grid electricity price is more expensive than$04 kWh Based on the optimization results wind energyproduction shows a bigger proportion of energy generationthan solar While the solar power occupies less than 1 of thetotal energy generation wind power occupies approximatelya quarter

Therefore the wind energy resource has more impact onthe implementation Figures 15ndash18 reflect the cost renewablefraction and emission variation dependent on the sensitivityvariable wind speed The NPC and COE of the hybrid power

The Scientific World Journal 11

system reduce when the wind speed increases from 69ms to88ms Figure 15

Simultaneously as seen in Figure 16 renewable fractionrises sharply from 0 to 16 (when wind speed increases from69 to 7ms) and then steadily increases to 24 at a slowerrate In addition as shown in Figures 17 and 18 the mainemissions of carbon dioxide sulfur dioxide and nitrogenoxide persistently decrease 22

6 Problems Encountered in DecentralizedSystems [37]

The major difficulty associated with decentralized energysources is that they generally do not participate in ancillaryservices (voltage control frequency ability to operate instandalone mode etc) This is especially true for renewableenergy sources whose power flow is unpredictable and veryvolatile The integration of decentralized energy generationinto power networks raises the following problems

(i) random and unpredictable energy production (windsolar)

(ii) lack of power-frequency control(iii) no voltage adjustment performed(iv) sensitivity to voltage dips(v) significant sensitivity to changes in primary source

(wind solar) energy levels

The failure to take part in system services makes thistype of sources behave as passive generators from theelectrical energy generation point of view The penetrationof distributed energy generation must be limited from 20 to30 of the consumed power in order to guarantee acceptablesystem stability [19]

7 Conclusion

This study is related to the technical economic and envi-ronmental impact of grid-connected decentralized systems towhich an appropriatemanagement of energy is applied andbymeans of which are developed models of the different partsThe solar and wind energy resource data are collected fromthe weather station of Adrar which is a typical arid regionThe most significant results are as follows

The power that any subsystem can deliver depends on theweather conditions of the considered site

The PV based system only covers 1 of the total loadconsumption On the other hand the wind generator con-tribution amounts to about 21 of the energy productionwhile the remaining 78 are supplied by the conventionalelectricity grid

From an economic point of view it is found that for theAdrar site which is characterized by a high wind potentialthe hybrid system is competitive compared with the conven-tional system with a cost of the energy COE produced by thenetwork equal to $04kWh since the estimated COE relatedto the hybrid system is equal to $0399kWh based on anaverage wind speed greater than or equal to 6ms

From an environmental standpoint the rates of green-house gases (CO

2 SO2 andNOx) emissions are reduced from

20 to 22 in the case of a hybrid system compared with theconventional system

The sensitivity analysis indicates that PV-wind hybridsystem is feasible under the meteorological conditions inAdrar region With the increasing wind speed the NPCCOE and emissions of the hybrid renewable energy systemreduce and renewable fraction grows up

Conflict of Interests

None of the authors of this paper has a financial or personalrelationship with other people or organisations that couldinappropriately influence or bias the content of the paper

References

[1] J Koo K Park D Shin and E S Yoon ldquoEconomic evaluationof renewable energy systems under varying scenarios and itsimplications to Korearsquos renewable energy planrdquo Applied Energyvol 88 no 6 pp 2254ndash2260 2011

[2] World Energy Outlook IEA Paris France 2008[3] KHofman andX Li ldquoCanadarsquos energy perspectives andpolicies

for sustainable developmentrdquo Applied Energy vol 86 no 4 pp407ndash415 2009

[4] H Weigt ldquoGermanyrsquos wind energy the potential for fossilcapacity replacement and cost savingrdquo Applied Energy vol 86no 10 pp 1857ndash1863 2009

[5] S A Khan R Rashmi M Z Hussain S Prasad and U CBanerjee ldquoProspects of biodiesel production from microalgaein Indiardquo Renewable and Sustainable Energy Reviews vol 13 no9 pp 2361ndash2372 2009

[6] E S Yoon ldquoA review on sustainable energy recent devel-opments and future prospects of dimethyl ether (DME)rdquo inProceedings of the 10th International Symposium on ProcessSystems Engineering (PSE rsquo09) Bahia Brazil 2009

[7] ldquoAdrar lancement des travaux du projet de la ferme eoliennerdquo2011 httpwwwalgerie360comalgerieadrar-lancement-des-travaux-du-projet-de-la-ferme-eolienne

[8] A Ducluzaux ldquoLrsquoenergie electrique drsquoorigine eoliennerdquo in Con-ference sur lrsquoEnergie Grenoble France 2004

[9] S Nguefeu M Arab X Waymel and F Costa ldquoPWM invertersin decentralized generation systems characterization of thedynamic behavior under utility fault conditionsrdquo InternationalJournal of Distributed Energy Resources vol 2 no 2 pp 101ndash1142006

[10] G Panayiotou S Kalogirou and S Tassou ldquoDesign andsimulation of a PV and a PV-Wind standalone energy systemto power a household applicationrdquo Renewable Energy vol 37no 1 pp 355ndash363 2012

[11] S M Shaahid ldquoReview of research on autonomous wind farmsand solar parks and their feasibility for commercial loads in hotregionsrdquo Renewable and Sustainable Energy Reviews vol 15 no8 pp 3877ndash3887 2011

[12] M A Elhadidy and S M Shaahid ldquoParametric study of hybrid(wind + solar + diesel) power generating systemsrdquo RenewableEnergy vol 21 no 2 pp 129ndash139 2000

12 The Scientific World Journal

[13] S M Shaahid and M A Elhadidy ldquoTechnical and economicassessment of grid-independent hybrid photovoltaic-diesel-battery power systems for commercial loads in desert environ-mentsrdquo Renewable and Sustainable Energy Reviews vol 11 no8 pp 1794ndash1810 2007

[14] D Saheb-Koussa M Haddadi and M Belhamel ldquoEconomicand technical study of a hybrid system (wind-photovoltaic-diesel) for rural electrification in Algeriardquo Applied Energy vol86 no 7-8 pp 1024ndash1030 2009

[15] G J Dalton D A Lockington and T E Baldock ldquoFeasibilityanalysis of stand-alone renewable energy supply options for alarge hotelrdquo Renewable Energy vol 33 no 7 pp 1475ndash14902008

[16] ANCelik ldquoPresent status of photovoltaic energy inTurkey andlife cycle techno-economic analysis of a grid-connected pho-tovoltaic-houserdquo Renewable and Sustainable Energy Reviewsvol 10 no 4 pp 370ndash387 2006

[17] M A H Mondal and M Denich ldquoAssessment of renew-able energy resources potential for electricity generation inBangladeshrdquoRenewable and Sustainable Energy Reviews vol 14no 7 pp 2401ndash2413 2010

[18] D Saheb-Koussa M Haddadi M Belhamel S Hadji and SNouredine ldquoModeling and simulation of the fixed-speedWECS(wind energy conversion system) application to the AlgerianSahara areardquo Energy vol 35 no 10 pp 4116ndash4125 2010

[19] S Rehman I M El-Amin F Ahmad et al ldquoFeasibility studyof hybrid retrofits to an isolated off-grid diesel power plantrdquoRenewable and Sustainable Energy Reviews vol 11 no 4 pp635ndash653 2007

[20] S Singer B Rozenshtein and S Surazi ldquoCharacterization of PVarray output using a small number of measured parametersrdquoSolar Energy vol 32 no 5 pp 603ndash607 1984

[21] D Saheb-Koussa ldquoContribution a lrsquoetude theorique du com-portement drsquoun systeme hybride (eolien- photovoltaıque-diesel) de production drsquoelectricite sans interruptionrdquo Memoirede magister Blida Septembre 2005

[22] G Tsengenes and G Adamidis ldquoInvestigation of the behaviorof a three phase grid-connected photovoltaic system to controlactive and reactive powerrdquo Electric Power Systems Research vol81 no 1 pp 177ndash184 2011

[23] S-K Chung ldquoA phase tracking system for three phase utilityinterface invertersrdquo IEEE Transactions on Power Electronics vol15 no 3 pp 431ndash438 2000

[24] R Dufo-Lopez J L Bernal-Agustın and F Mendoza ldquoDesignand economical analysis of hybrid PV-wind systems connectedto the grid for the intermittent production of hydrogenrdquo EnergyPolicy vol 37 no 8 pp 3082ndash3095 2009

[25] T Burton D Sharpe N Jenkins and E BossanyiWind EnergyHandbook John Wiley amp Sons West Sussex UK 2001

[26] Union for Coordination of Transmission of Electricity ldquoWindPower in the UCTE interconnected Systemrdquo November2004 httpswwwentsoeeufileadminuser upload librarypublicationsceotherreportsWind Power 20041125pdf

[27] E Spooner and A C Williamson ldquoDirect coupled permanentmagnet generators for wind turbine applicationsrdquo IEE Proceed-ings Electric Power Applications vol 143 no 1 pp 1ndash8 1996

[28] N Laverdure S Bacha D Roye B Raison and F DumasldquoElements of modelling of wind power systems with energymanagement two structures in comparisonrdquo in Proceedings ofthe 28th IEEE Annual Conference of the Industrial ElectronicsSociety vol 2 pp 1083ndash1088 November 2002

[29] L Krichen B Francois and A Ouali ldquoA fuzzy logic supervisorfor active and reactive power control of a fixed speed windenergy conversion systemrdquo Electric Power Systems Research vol78 no 3 pp 418ndash424 2008

[30] The Cres Wind Farm ldquo301 MW Demonstration wind farmin Greece Various wind energy technologies in complex Ter-rain topographyrdquo httpwwwcreswindfarmgrsite1ArticlesV47 USpdf

[31] T AckermannWind Power in Power Systems Royal Institute ofTechnology John Wiley amp Sons Stockholm Sweden 2005

[32] F Poitiers Asynchronous generator study and control for thewind energy use [PhD thesis] University of Nantes NantesFrance 2003

[33] M Kacira M Simsek Y Babur and S Demirkol ldquoDeterminingoptimum tilt angles and orientations of photovoltaic panels inSanliurfa Turkeyrdquo Renewable Energy vol 29 no 8 pp 1265ndash1275 2004

[34] D Saheb-Koussa M Belhamel and K Benferhat ldquoContribu-tion a lrsquoetude theorique du comportement drsquoun systeme hybride(eolien- photovoltaıque- diesel) de production drsquoelectricite sansinterruptionrdquo Afrique Science vol 5 no 1 2009

[35] HOMERmdashGetting Started Guide for HOMER Version 21National Renewable Energy Laboratory US Department ofEnergyOffice of EnergyEfficiency andRenewable Energy 2005

[36] C D Barley C B Winn L Flowers and H J Green ldquoOptimalcontrol of remote hybrid power systemsmdashpart I simplifiedmodelrdquo in Proceedings of National Avian-Wind Power PlanningMeeting Washington DC USA 1995

[37] D Saheb-Koussa ldquoEtude technique economique et environ-nementale des systemes decentralises connectes au reseauelectriquerdquo Bulletin des Energies Renouvelables vol 23 pp 15ndash17 2012

[38] V Courtecuisse Supervision drsquoune centrale multi sources a basedrsquoeoliennes et de stockage drsquoenergie connectee au reseau electrique[These de doctorat] Ecole Nationale des Arts et Metiers 2008

TribologyAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Industrial EngineeringJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Renewable Energy

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StructuresJournal of

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear InstallationsScience and Technology of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Solar EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Wind EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear EnergyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

The Scientific World Journal 7

0 1000 2000 3000 4000 5000 6000 7000 8000 900005

10152025

Time (h)

Win

d sp

eed

(ms

)

(a)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0

Time (h)

Activ

e pow

er (k

W)

minus6

minus5

minus4

minus3

minus2

minus1

times105

(b)

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

051

152

253

354

Time (h)

Reac

tive p

ower

(kVA

)

times105

(c)

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

0200400600800

Time (h)

Thre

e-ph

ase s

tato

r cur

rent

s (A

)

minus800

minus600

minus400

minus200

(d)

Figure 7 Simulation results

a disturbance of any of these devices These last ones dis-turbed by generating harmonics that may distort the gridwaveform flickers high frequency wave frequency fluctua-tion under voltage and over voltage

Thus for each hour of the year h the amount of electricalenergy available at the transformer connected to the grid isevaluated by [24]

119875AC-h = (119875pv-h120578INV + 119875w-h)120578TR (14)

where 120578INV is the inverter efficiency rate modeled as avariable depending on the power delivered by the inverter120578TR is the efficiency rate of the transformer connected tothe electrical grid including the losses of power in thetransmission lines 119875w-h is the power (W) generated by thewind generator within an hour time and 119875pv-h is the power(W) generated by the PV generator within an hour time

However the amount of power that can be injected eachhour into the grid 119875EE-h (W) cannot be higher than theallowed evacuation capacity at the point of connection to thegrid 119875MAX-GRID (W) [24]

119875EE-h = min (119875MAX-GRID 119875AC-h) (15)

Where 119875MAX-GRID (W) is the maximum power evacuationvalue allowed which the Algerian law fixes for 20 to 30 ofthe line thermal limit at the point of connection

The amount of energy to be injected into the grid obtainedfrom the PV generator (119875EE-PV-h) and the wind generator119875EE-w-h will be calculated as indicated by Figure 9

The results obtained in the case of the previouslydescribed scenario are represented in Figure 10 which showsthat the hourly produced power injected into the grid is lowerthan 119875MAX-GRID

54 Total Annual Production The contribution of each partof the hybrid system (PV-wind-grid) to satisfy a specificload of the 34815MWhyr is shown in Figure 11 It is to benoted that the PV generator produces only 365MWhyearand covers only 1 of the load The wind generator inturn produces 7225MWhyear which constitute nearly 21of load requirements against a covered load rate of 78(27225MWhyear) provided by the conventional electricitygrid [35]These results are explained by the fact that HOMERsoftware promotes the wind system because of itrsquos efficiencywhich is very higher than that of PV system

55 Hours of Operation Figure 12 represents the durationof the operation (in hours) of each of the renewable energyequipment of the hybrid PV-wind-Grid system It is foundthat the wind generator works over the longest time intervalwith a 48 rate of the total period followed by the PVgenerator and inverter with a rate of 26 for each

56 Economic Aspects The HOMER optimization model[24] uses relatively simple strategies based on the ones studiedby Barley et al [36] and it is able to obtain an optimal designof a hybrid system by selecting the most appropriate strategy

Thus from an economic point of view it is found thatthe system composed of a 200 kW rated PV system andthree 660 kW rated wind turbines can cover 22 of theelectrical energy demand and has a net present cost (NPC)of $177 million and a cost of energy per kilowatt hour(COE) of $0399kWh A comparative economic analysisbetween the conventional and the optimized system (PV-wind system) employing HOMER software package [35] hasbeen performed and the results are presented in Table 1From these results it is noticed that the hybrid system (PV-wind-grid) is more economical than the conventional system

8 The Scientific World Journal

Yearly day number

Yearly day number 1

Tsvtsv

09

Transform

Preflight

09Convert

-C-

In1 cem

Wind system

vvvWind velocity

Scope

Result PV

Result

In1

In2

In3

In4

PV system

GHR

Global horiz rad

In1

In2

In3

PE1

PPV1

Out1

Gestion

difHR

Diffuse horiz rad1

Iabc

AP

AP

RP

Tt

Wt

Wmas

Iabc

Isabc

Isabc

Figure 8 Management of the system

PV system priority

No

No

NoNo Yes

Yes

Yes

Yes

Ppv-h Pw-h

Ppv-h Pw-h 120578inv 120578TR

PEE-h lt PMAX-GRID

PEE-h = Ppv-h120578INV 120578TR

120578inv 120578TR = Pmax-grid

Pw-h120578TR = PMAX-GRID

PEE-w-h = PMAX-GRIDPEE-PV-h = 0 PEE-PV-h = PMAX-GRIDPw-h120578TR

PEE-PV-h = PMAX-GRID

PEE-w-h = 0

PEE-w-h = 0 PEE-w-h = 0

PEE-w-h = 0

PEE-h = PEE-PV-h + PEE-w-h

PEE-PV-h = PPV-h120578INV120578TR

PEE-w-h = Pw-h TR120578middot

Figure 9 Flowchart for calculating the amount of power to be inject into the grid

The Scientific World Journal 9

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

500

1000

1500

2000

2500

3000

Time (h)

Pow

er (k

W)

Injected power into the gridPMAX-GRID

Figure 10 Power injected into the grid

1365 MWhyr

7225 MWhyr21

27225 MWhyr78

Photovoltaic systemWind systemGrid

Figure 11 Structure of the production system (PV-wind-grid)

26

48

26

Photovoltaic systemWind systemConverter

Figure 12 Distribution of operation hours of each of the renewableenergy equipment of the hybrid PV-wind-Grid system

05 1 15 2 25 3 35 4 450

20406080

100120140

Photovoltaic systemWind system

GridConverter

106$

Figure 13 Net present cost

05 1 15 2 25 3 35 4 4502468

1012

Photovoltaic systemWind system

GridConverter

106$yr

Figure 14 Annual net cost

Table 1 Cost comparison between a standard system (grid) and ahybrid system (PV-wind-grid)

Cost Conventional systemgrid

Hybrid systemPV-wind-grid

NPC ($yr) 177714200 177090600COE ($kWh) 04 0399

Table 2 Emissions comparison between a standard system (grid)and a hybrid system (PV-wind-grid)

Pollutant Kgyr Conventional systemgrid

Hybrid systemPV-wind-grid

CO2 21965160 17199524SO2 95229 74568NO119909

46572 36467

if the price per produced kWh of the latter is set to $04kWhHowever the net present cost is calculated for a projectlifetime period of 25 years and on the basis of an interest rateof 6 Figures 13 and 14 show the details of the correspondingcosts to each of the systems and the related annual costs [37]

57 Environmental Aspects The results regarding the effectsof each system configuration that is the conventional gridand the hybrid system (PV-wind-grid) on the environmentobtained by again using HOMER software in the caseof the Adrar site are shown in Table 2 [37] In this tablethe quantities of the main gases that are harmful to theenvironment including CO

2 SO2 and NOx are presented

10 The Scientific World Journal

160

165

170

175

180

72 76 80 84 88036

037

038

039

040

041

Leve

lized

cost

of en

ergy

($k

Wh)

Levelized cost of energy versus wind speed

Wind speed (ms)

Tota

l net

pre

sent

cost

($)

Levelized cost of energyTotal net present cost

Fixed

times106

Global solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 15 The relationship between cost and wind speed

72 76 80 84 88000

005

010

015

020

025

Rene

wab

le fr

actio

n

Renewable fraction versus wind speed

Wind speed (ms)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 16 The relationship between RF and wind speed

From these results it is found that the PV-wind-grid hybridsystem produces a reduction in the carbon dioxide gassulfur dioxide and nitrogen oxide rates by respectively 2022 and 22 as compared to the quantities produced by theconventional system [37]

58 Sensitivity Results In this study sensitivity analysis wasdone to study the effects of variation in the solar irradiationand wind speed The simulation software simulates thelong-term implementation of the hybrid system based ontheir respective search size for the predefined sensitivityvalues of the componentsThe emissions renewable fractionNPC and COE are simulated based on the three sensitivityvariables wind speed (ms) solar irradiation (kWm2day)and grid electricity price ($kWh) A long-term simulationfor every possible system combination and configurationwas done for a one year period (from January 1st 2005 toDecember 31st 2005) In the present case solar irradiationis set as sensitivity variables 119866 = 35 45 5 55 572 788 kWm2day while wind speed are V = 69 7 75 78 888msMoreover the grid electricity price is also defined as asensitivity variable (119901 = 01 02 03 04 $kWh) A total of 192

72 76 80 84 8816171819202122

Wind speed (ms)

times106

CO2

emiss

ions

(kg

yr)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

CO2 emissions versus wind speed

Figure 17The relationship betweenCO2emissions andwind speed

72 76 80 84 8830405060708090

100

Wind speed (ms)SO

2em

issio

ns (k

gyr

) SO2 emissions versus wind speed

SO2 emissionsNOx emissions

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 18 The relationship between sulfur dioxide and nitrogenoxide emissions and wind speed

sensitivity cases were tried for each system configurationThesimulation timewas 23minutes and 46 seconds on a personalcomputer with Intel CORE Intel Core Duo Processor of253GHz and a RAM of 2GBThe sensitivity results in termsof solar irradiation wind speed and grid electricity priceanalyze the feasibility of each system Here the feasibilityof hybrid renewable energy system is analyzed based onemission reduction and cost saving This type of sensitivityanalysis of the systems provides information that a particularsystem would be optimal at certain sensitivity variables [19]The PV-wind system is feasible when the grid electricityprice is more than $04 kWh Under this condition the RFcan be between 021 and 022 A PV-wind system is feasiblewhen global solar irradiation is more than 572 kWhm2 perday and the grid electricity price is more expensive than$04 kWh Based on the optimization results wind energyproduction shows a bigger proportion of energy generationthan solar While the solar power occupies less than 1 of thetotal energy generation wind power occupies approximatelya quarter

Therefore the wind energy resource has more impact onthe implementation Figures 15ndash18 reflect the cost renewablefraction and emission variation dependent on the sensitivityvariable wind speed The NPC and COE of the hybrid power

The Scientific World Journal 11

system reduce when the wind speed increases from 69ms to88ms Figure 15

Simultaneously as seen in Figure 16 renewable fractionrises sharply from 0 to 16 (when wind speed increases from69 to 7ms) and then steadily increases to 24 at a slowerrate In addition as shown in Figures 17 and 18 the mainemissions of carbon dioxide sulfur dioxide and nitrogenoxide persistently decrease 22

6 Problems Encountered in DecentralizedSystems [37]

The major difficulty associated with decentralized energysources is that they generally do not participate in ancillaryservices (voltage control frequency ability to operate instandalone mode etc) This is especially true for renewableenergy sources whose power flow is unpredictable and veryvolatile The integration of decentralized energy generationinto power networks raises the following problems

(i) random and unpredictable energy production (windsolar)

(ii) lack of power-frequency control(iii) no voltage adjustment performed(iv) sensitivity to voltage dips(v) significant sensitivity to changes in primary source

(wind solar) energy levels

The failure to take part in system services makes thistype of sources behave as passive generators from theelectrical energy generation point of view The penetrationof distributed energy generation must be limited from 20 to30 of the consumed power in order to guarantee acceptablesystem stability [19]

7 Conclusion

This study is related to the technical economic and envi-ronmental impact of grid-connected decentralized systems towhich an appropriatemanagement of energy is applied andbymeans of which are developed models of the different partsThe solar and wind energy resource data are collected fromthe weather station of Adrar which is a typical arid regionThe most significant results are as follows

The power that any subsystem can deliver depends on theweather conditions of the considered site

The PV based system only covers 1 of the total loadconsumption On the other hand the wind generator con-tribution amounts to about 21 of the energy productionwhile the remaining 78 are supplied by the conventionalelectricity grid

From an economic point of view it is found that for theAdrar site which is characterized by a high wind potentialthe hybrid system is competitive compared with the conven-tional system with a cost of the energy COE produced by thenetwork equal to $04kWh since the estimated COE relatedto the hybrid system is equal to $0399kWh based on anaverage wind speed greater than or equal to 6ms

From an environmental standpoint the rates of green-house gases (CO

2 SO2 andNOx) emissions are reduced from

20 to 22 in the case of a hybrid system compared with theconventional system

The sensitivity analysis indicates that PV-wind hybridsystem is feasible under the meteorological conditions inAdrar region With the increasing wind speed the NPCCOE and emissions of the hybrid renewable energy systemreduce and renewable fraction grows up

Conflict of Interests

None of the authors of this paper has a financial or personalrelationship with other people or organisations that couldinappropriately influence or bias the content of the paper

References

[1] J Koo K Park D Shin and E S Yoon ldquoEconomic evaluationof renewable energy systems under varying scenarios and itsimplications to Korearsquos renewable energy planrdquo Applied Energyvol 88 no 6 pp 2254ndash2260 2011

[2] World Energy Outlook IEA Paris France 2008[3] KHofman andX Li ldquoCanadarsquos energy perspectives andpolicies

for sustainable developmentrdquo Applied Energy vol 86 no 4 pp407ndash415 2009

[4] H Weigt ldquoGermanyrsquos wind energy the potential for fossilcapacity replacement and cost savingrdquo Applied Energy vol 86no 10 pp 1857ndash1863 2009

[5] S A Khan R Rashmi M Z Hussain S Prasad and U CBanerjee ldquoProspects of biodiesel production from microalgaein Indiardquo Renewable and Sustainable Energy Reviews vol 13 no9 pp 2361ndash2372 2009

[6] E S Yoon ldquoA review on sustainable energy recent devel-opments and future prospects of dimethyl ether (DME)rdquo inProceedings of the 10th International Symposium on ProcessSystems Engineering (PSE rsquo09) Bahia Brazil 2009

[7] ldquoAdrar lancement des travaux du projet de la ferme eoliennerdquo2011 httpwwwalgerie360comalgerieadrar-lancement-des-travaux-du-projet-de-la-ferme-eolienne

[8] A Ducluzaux ldquoLrsquoenergie electrique drsquoorigine eoliennerdquo in Con-ference sur lrsquoEnergie Grenoble France 2004

[9] S Nguefeu M Arab X Waymel and F Costa ldquoPWM invertersin decentralized generation systems characterization of thedynamic behavior under utility fault conditionsrdquo InternationalJournal of Distributed Energy Resources vol 2 no 2 pp 101ndash1142006

[10] G Panayiotou S Kalogirou and S Tassou ldquoDesign andsimulation of a PV and a PV-Wind standalone energy systemto power a household applicationrdquo Renewable Energy vol 37no 1 pp 355ndash363 2012

[11] S M Shaahid ldquoReview of research on autonomous wind farmsand solar parks and their feasibility for commercial loads in hotregionsrdquo Renewable and Sustainable Energy Reviews vol 15 no8 pp 3877ndash3887 2011

[12] M A Elhadidy and S M Shaahid ldquoParametric study of hybrid(wind + solar + diesel) power generating systemsrdquo RenewableEnergy vol 21 no 2 pp 129ndash139 2000

12 The Scientific World Journal

[13] S M Shaahid and M A Elhadidy ldquoTechnical and economicassessment of grid-independent hybrid photovoltaic-diesel-battery power systems for commercial loads in desert environ-mentsrdquo Renewable and Sustainable Energy Reviews vol 11 no8 pp 1794ndash1810 2007

[14] D Saheb-Koussa M Haddadi and M Belhamel ldquoEconomicand technical study of a hybrid system (wind-photovoltaic-diesel) for rural electrification in Algeriardquo Applied Energy vol86 no 7-8 pp 1024ndash1030 2009

[15] G J Dalton D A Lockington and T E Baldock ldquoFeasibilityanalysis of stand-alone renewable energy supply options for alarge hotelrdquo Renewable Energy vol 33 no 7 pp 1475ndash14902008

[16] ANCelik ldquoPresent status of photovoltaic energy inTurkey andlife cycle techno-economic analysis of a grid-connected pho-tovoltaic-houserdquo Renewable and Sustainable Energy Reviewsvol 10 no 4 pp 370ndash387 2006

[17] M A H Mondal and M Denich ldquoAssessment of renew-able energy resources potential for electricity generation inBangladeshrdquoRenewable and Sustainable Energy Reviews vol 14no 7 pp 2401ndash2413 2010

[18] D Saheb-Koussa M Haddadi M Belhamel S Hadji and SNouredine ldquoModeling and simulation of the fixed-speedWECS(wind energy conversion system) application to the AlgerianSahara areardquo Energy vol 35 no 10 pp 4116ndash4125 2010

[19] S Rehman I M El-Amin F Ahmad et al ldquoFeasibility studyof hybrid retrofits to an isolated off-grid diesel power plantrdquoRenewable and Sustainable Energy Reviews vol 11 no 4 pp635ndash653 2007

[20] S Singer B Rozenshtein and S Surazi ldquoCharacterization of PVarray output using a small number of measured parametersrdquoSolar Energy vol 32 no 5 pp 603ndash607 1984

[21] D Saheb-Koussa ldquoContribution a lrsquoetude theorique du com-portement drsquoun systeme hybride (eolien- photovoltaıque-diesel) de production drsquoelectricite sans interruptionrdquo Memoirede magister Blida Septembre 2005

[22] G Tsengenes and G Adamidis ldquoInvestigation of the behaviorof a three phase grid-connected photovoltaic system to controlactive and reactive powerrdquo Electric Power Systems Research vol81 no 1 pp 177ndash184 2011

[23] S-K Chung ldquoA phase tracking system for three phase utilityinterface invertersrdquo IEEE Transactions on Power Electronics vol15 no 3 pp 431ndash438 2000

[24] R Dufo-Lopez J L Bernal-Agustın and F Mendoza ldquoDesignand economical analysis of hybrid PV-wind systems connectedto the grid for the intermittent production of hydrogenrdquo EnergyPolicy vol 37 no 8 pp 3082ndash3095 2009

[25] T Burton D Sharpe N Jenkins and E BossanyiWind EnergyHandbook John Wiley amp Sons West Sussex UK 2001

[26] Union for Coordination of Transmission of Electricity ldquoWindPower in the UCTE interconnected Systemrdquo November2004 httpswwwentsoeeufileadminuser upload librarypublicationsceotherreportsWind Power 20041125pdf

[27] E Spooner and A C Williamson ldquoDirect coupled permanentmagnet generators for wind turbine applicationsrdquo IEE Proceed-ings Electric Power Applications vol 143 no 1 pp 1ndash8 1996

[28] N Laverdure S Bacha D Roye B Raison and F DumasldquoElements of modelling of wind power systems with energymanagement two structures in comparisonrdquo in Proceedings ofthe 28th IEEE Annual Conference of the Industrial ElectronicsSociety vol 2 pp 1083ndash1088 November 2002

[29] L Krichen B Francois and A Ouali ldquoA fuzzy logic supervisorfor active and reactive power control of a fixed speed windenergy conversion systemrdquo Electric Power Systems Research vol78 no 3 pp 418ndash424 2008

[30] The Cres Wind Farm ldquo301 MW Demonstration wind farmin Greece Various wind energy technologies in complex Ter-rain topographyrdquo httpwwwcreswindfarmgrsite1ArticlesV47 USpdf

[31] T AckermannWind Power in Power Systems Royal Institute ofTechnology John Wiley amp Sons Stockholm Sweden 2005

[32] F Poitiers Asynchronous generator study and control for thewind energy use [PhD thesis] University of Nantes NantesFrance 2003

[33] M Kacira M Simsek Y Babur and S Demirkol ldquoDeterminingoptimum tilt angles and orientations of photovoltaic panels inSanliurfa Turkeyrdquo Renewable Energy vol 29 no 8 pp 1265ndash1275 2004

[34] D Saheb-Koussa M Belhamel and K Benferhat ldquoContribu-tion a lrsquoetude theorique du comportement drsquoun systeme hybride(eolien- photovoltaıque- diesel) de production drsquoelectricite sansinterruptionrdquo Afrique Science vol 5 no 1 2009

[35] HOMERmdashGetting Started Guide for HOMER Version 21National Renewable Energy Laboratory US Department ofEnergyOffice of EnergyEfficiency andRenewable Energy 2005

[36] C D Barley C B Winn L Flowers and H J Green ldquoOptimalcontrol of remote hybrid power systemsmdashpart I simplifiedmodelrdquo in Proceedings of National Avian-Wind Power PlanningMeeting Washington DC USA 1995

[37] D Saheb-Koussa ldquoEtude technique economique et environ-nementale des systemes decentralises connectes au reseauelectriquerdquo Bulletin des Energies Renouvelables vol 23 pp 15ndash17 2012

[38] V Courtecuisse Supervision drsquoune centrale multi sources a basedrsquoeoliennes et de stockage drsquoenergie connectee au reseau electrique[These de doctorat] Ecole Nationale des Arts et Metiers 2008

TribologyAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Industrial EngineeringJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Renewable Energy

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StructuresJournal of

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear InstallationsScience and Technology of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Solar EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Wind EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear EnergyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

8 The Scientific World Journal

Yearly day number

Yearly day number 1

Tsvtsv

09

Transform

Preflight

09Convert

-C-

In1 cem

Wind system

vvvWind velocity

Scope

Result PV

Result

In1

In2

In3

In4

PV system

GHR

Global horiz rad

In1

In2

In3

PE1

PPV1

Out1

Gestion

difHR

Diffuse horiz rad1

Iabc

AP

AP

RP

Tt

Wt

Wmas

Iabc

Isabc

Isabc

Figure 8 Management of the system

PV system priority

No

No

NoNo Yes

Yes

Yes

Yes

Ppv-h Pw-h

Ppv-h Pw-h 120578inv 120578TR

PEE-h lt PMAX-GRID

PEE-h = Ppv-h120578INV 120578TR

120578inv 120578TR = Pmax-grid

Pw-h120578TR = PMAX-GRID

PEE-w-h = PMAX-GRIDPEE-PV-h = 0 PEE-PV-h = PMAX-GRIDPw-h120578TR

PEE-PV-h = PMAX-GRID

PEE-w-h = 0

PEE-w-h = 0 PEE-w-h = 0

PEE-w-h = 0

PEE-h = PEE-PV-h + PEE-w-h

PEE-PV-h = PPV-h120578INV120578TR

PEE-w-h = Pw-h TR120578middot

Figure 9 Flowchart for calculating the amount of power to be inject into the grid

The Scientific World Journal 9

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

500

1000

1500

2000

2500

3000

Time (h)

Pow

er (k

W)

Injected power into the gridPMAX-GRID

Figure 10 Power injected into the grid

1365 MWhyr

7225 MWhyr21

27225 MWhyr78

Photovoltaic systemWind systemGrid

Figure 11 Structure of the production system (PV-wind-grid)

26

48

26

Photovoltaic systemWind systemConverter

Figure 12 Distribution of operation hours of each of the renewableenergy equipment of the hybrid PV-wind-Grid system

05 1 15 2 25 3 35 4 450

20406080

100120140

Photovoltaic systemWind system

GridConverter

106$

Figure 13 Net present cost

05 1 15 2 25 3 35 4 4502468

1012

Photovoltaic systemWind system

GridConverter

106$yr

Figure 14 Annual net cost

Table 1 Cost comparison between a standard system (grid) and ahybrid system (PV-wind-grid)

Cost Conventional systemgrid

Hybrid systemPV-wind-grid

NPC ($yr) 177714200 177090600COE ($kWh) 04 0399

Table 2 Emissions comparison between a standard system (grid)and a hybrid system (PV-wind-grid)

Pollutant Kgyr Conventional systemgrid

Hybrid systemPV-wind-grid

CO2 21965160 17199524SO2 95229 74568NO119909

46572 36467

if the price per produced kWh of the latter is set to $04kWhHowever the net present cost is calculated for a projectlifetime period of 25 years and on the basis of an interest rateof 6 Figures 13 and 14 show the details of the correspondingcosts to each of the systems and the related annual costs [37]

57 Environmental Aspects The results regarding the effectsof each system configuration that is the conventional gridand the hybrid system (PV-wind-grid) on the environmentobtained by again using HOMER software in the caseof the Adrar site are shown in Table 2 [37] In this tablethe quantities of the main gases that are harmful to theenvironment including CO

2 SO2 and NOx are presented

10 The Scientific World Journal

160

165

170

175

180

72 76 80 84 88036

037

038

039

040

041

Leve

lized

cost

of en

ergy

($k

Wh)

Levelized cost of energy versus wind speed

Wind speed (ms)

Tota

l net

pre

sent

cost

($)

Levelized cost of energyTotal net present cost

Fixed

times106

Global solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 15 The relationship between cost and wind speed

72 76 80 84 88000

005

010

015

020

025

Rene

wab

le fr

actio

n

Renewable fraction versus wind speed

Wind speed (ms)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 16 The relationship between RF and wind speed

From these results it is found that the PV-wind-grid hybridsystem produces a reduction in the carbon dioxide gassulfur dioxide and nitrogen oxide rates by respectively 2022 and 22 as compared to the quantities produced by theconventional system [37]

58 Sensitivity Results In this study sensitivity analysis wasdone to study the effects of variation in the solar irradiationand wind speed The simulation software simulates thelong-term implementation of the hybrid system based ontheir respective search size for the predefined sensitivityvalues of the componentsThe emissions renewable fractionNPC and COE are simulated based on the three sensitivityvariables wind speed (ms) solar irradiation (kWm2day)and grid electricity price ($kWh) A long-term simulationfor every possible system combination and configurationwas done for a one year period (from January 1st 2005 toDecember 31st 2005) In the present case solar irradiationis set as sensitivity variables 119866 = 35 45 5 55 572 788 kWm2day while wind speed are V = 69 7 75 78 888msMoreover the grid electricity price is also defined as asensitivity variable (119901 = 01 02 03 04 $kWh) A total of 192

72 76 80 84 8816171819202122

Wind speed (ms)

times106

CO2

emiss

ions

(kg

yr)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

CO2 emissions versus wind speed

Figure 17The relationship betweenCO2emissions andwind speed

72 76 80 84 8830405060708090

100

Wind speed (ms)SO

2em

issio

ns (k

gyr

) SO2 emissions versus wind speed

SO2 emissionsNOx emissions

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 18 The relationship between sulfur dioxide and nitrogenoxide emissions and wind speed

sensitivity cases were tried for each system configurationThesimulation timewas 23minutes and 46 seconds on a personalcomputer with Intel CORE Intel Core Duo Processor of253GHz and a RAM of 2GBThe sensitivity results in termsof solar irradiation wind speed and grid electricity priceanalyze the feasibility of each system Here the feasibilityof hybrid renewable energy system is analyzed based onemission reduction and cost saving This type of sensitivityanalysis of the systems provides information that a particularsystem would be optimal at certain sensitivity variables [19]The PV-wind system is feasible when the grid electricityprice is more than $04 kWh Under this condition the RFcan be between 021 and 022 A PV-wind system is feasiblewhen global solar irradiation is more than 572 kWhm2 perday and the grid electricity price is more expensive than$04 kWh Based on the optimization results wind energyproduction shows a bigger proportion of energy generationthan solar While the solar power occupies less than 1 of thetotal energy generation wind power occupies approximatelya quarter

Therefore the wind energy resource has more impact onthe implementation Figures 15ndash18 reflect the cost renewablefraction and emission variation dependent on the sensitivityvariable wind speed The NPC and COE of the hybrid power

The Scientific World Journal 11

system reduce when the wind speed increases from 69ms to88ms Figure 15

Simultaneously as seen in Figure 16 renewable fractionrises sharply from 0 to 16 (when wind speed increases from69 to 7ms) and then steadily increases to 24 at a slowerrate In addition as shown in Figures 17 and 18 the mainemissions of carbon dioxide sulfur dioxide and nitrogenoxide persistently decrease 22

6 Problems Encountered in DecentralizedSystems [37]

The major difficulty associated with decentralized energysources is that they generally do not participate in ancillaryservices (voltage control frequency ability to operate instandalone mode etc) This is especially true for renewableenergy sources whose power flow is unpredictable and veryvolatile The integration of decentralized energy generationinto power networks raises the following problems

(i) random and unpredictable energy production (windsolar)

(ii) lack of power-frequency control(iii) no voltage adjustment performed(iv) sensitivity to voltage dips(v) significant sensitivity to changes in primary source

(wind solar) energy levels

The failure to take part in system services makes thistype of sources behave as passive generators from theelectrical energy generation point of view The penetrationof distributed energy generation must be limited from 20 to30 of the consumed power in order to guarantee acceptablesystem stability [19]

7 Conclusion

This study is related to the technical economic and envi-ronmental impact of grid-connected decentralized systems towhich an appropriatemanagement of energy is applied andbymeans of which are developed models of the different partsThe solar and wind energy resource data are collected fromthe weather station of Adrar which is a typical arid regionThe most significant results are as follows

The power that any subsystem can deliver depends on theweather conditions of the considered site

The PV based system only covers 1 of the total loadconsumption On the other hand the wind generator con-tribution amounts to about 21 of the energy productionwhile the remaining 78 are supplied by the conventionalelectricity grid

From an economic point of view it is found that for theAdrar site which is characterized by a high wind potentialthe hybrid system is competitive compared with the conven-tional system with a cost of the energy COE produced by thenetwork equal to $04kWh since the estimated COE relatedto the hybrid system is equal to $0399kWh based on anaverage wind speed greater than or equal to 6ms

From an environmental standpoint the rates of green-house gases (CO

2 SO2 andNOx) emissions are reduced from

20 to 22 in the case of a hybrid system compared with theconventional system

The sensitivity analysis indicates that PV-wind hybridsystem is feasible under the meteorological conditions inAdrar region With the increasing wind speed the NPCCOE and emissions of the hybrid renewable energy systemreduce and renewable fraction grows up

Conflict of Interests

None of the authors of this paper has a financial or personalrelationship with other people or organisations that couldinappropriately influence or bias the content of the paper

References

[1] J Koo K Park D Shin and E S Yoon ldquoEconomic evaluationof renewable energy systems under varying scenarios and itsimplications to Korearsquos renewable energy planrdquo Applied Energyvol 88 no 6 pp 2254ndash2260 2011

[2] World Energy Outlook IEA Paris France 2008[3] KHofman andX Li ldquoCanadarsquos energy perspectives andpolicies

for sustainable developmentrdquo Applied Energy vol 86 no 4 pp407ndash415 2009

[4] H Weigt ldquoGermanyrsquos wind energy the potential for fossilcapacity replacement and cost savingrdquo Applied Energy vol 86no 10 pp 1857ndash1863 2009

[5] S A Khan R Rashmi M Z Hussain S Prasad and U CBanerjee ldquoProspects of biodiesel production from microalgaein Indiardquo Renewable and Sustainable Energy Reviews vol 13 no9 pp 2361ndash2372 2009

[6] E S Yoon ldquoA review on sustainable energy recent devel-opments and future prospects of dimethyl ether (DME)rdquo inProceedings of the 10th International Symposium on ProcessSystems Engineering (PSE rsquo09) Bahia Brazil 2009

[7] ldquoAdrar lancement des travaux du projet de la ferme eoliennerdquo2011 httpwwwalgerie360comalgerieadrar-lancement-des-travaux-du-projet-de-la-ferme-eolienne

[8] A Ducluzaux ldquoLrsquoenergie electrique drsquoorigine eoliennerdquo in Con-ference sur lrsquoEnergie Grenoble France 2004

[9] S Nguefeu M Arab X Waymel and F Costa ldquoPWM invertersin decentralized generation systems characterization of thedynamic behavior under utility fault conditionsrdquo InternationalJournal of Distributed Energy Resources vol 2 no 2 pp 101ndash1142006

[10] G Panayiotou S Kalogirou and S Tassou ldquoDesign andsimulation of a PV and a PV-Wind standalone energy systemto power a household applicationrdquo Renewable Energy vol 37no 1 pp 355ndash363 2012

[11] S M Shaahid ldquoReview of research on autonomous wind farmsand solar parks and their feasibility for commercial loads in hotregionsrdquo Renewable and Sustainable Energy Reviews vol 15 no8 pp 3877ndash3887 2011

[12] M A Elhadidy and S M Shaahid ldquoParametric study of hybrid(wind + solar + diesel) power generating systemsrdquo RenewableEnergy vol 21 no 2 pp 129ndash139 2000

12 The Scientific World Journal

[13] S M Shaahid and M A Elhadidy ldquoTechnical and economicassessment of grid-independent hybrid photovoltaic-diesel-battery power systems for commercial loads in desert environ-mentsrdquo Renewable and Sustainable Energy Reviews vol 11 no8 pp 1794ndash1810 2007

[14] D Saheb-Koussa M Haddadi and M Belhamel ldquoEconomicand technical study of a hybrid system (wind-photovoltaic-diesel) for rural electrification in Algeriardquo Applied Energy vol86 no 7-8 pp 1024ndash1030 2009

[15] G J Dalton D A Lockington and T E Baldock ldquoFeasibilityanalysis of stand-alone renewable energy supply options for alarge hotelrdquo Renewable Energy vol 33 no 7 pp 1475ndash14902008

[16] ANCelik ldquoPresent status of photovoltaic energy inTurkey andlife cycle techno-economic analysis of a grid-connected pho-tovoltaic-houserdquo Renewable and Sustainable Energy Reviewsvol 10 no 4 pp 370ndash387 2006

[17] M A H Mondal and M Denich ldquoAssessment of renew-able energy resources potential for electricity generation inBangladeshrdquoRenewable and Sustainable Energy Reviews vol 14no 7 pp 2401ndash2413 2010

[18] D Saheb-Koussa M Haddadi M Belhamel S Hadji and SNouredine ldquoModeling and simulation of the fixed-speedWECS(wind energy conversion system) application to the AlgerianSahara areardquo Energy vol 35 no 10 pp 4116ndash4125 2010

[19] S Rehman I M El-Amin F Ahmad et al ldquoFeasibility studyof hybrid retrofits to an isolated off-grid diesel power plantrdquoRenewable and Sustainable Energy Reviews vol 11 no 4 pp635ndash653 2007

[20] S Singer B Rozenshtein and S Surazi ldquoCharacterization of PVarray output using a small number of measured parametersrdquoSolar Energy vol 32 no 5 pp 603ndash607 1984

[21] D Saheb-Koussa ldquoContribution a lrsquoetude theorique du com-portement drsquoun systeme hybride (eolien- photovoltaıque-diesel) de production drsquoelectricite sans interruptionrdquo Memoirede magister Blida Septembre 2005

[22] G Tsengenes and G Adamidis ldquoInvestigation of the behaviorof a three phase grid-connected photovoltaic system to controlactive and reactive powerrdquo Electric Power Systems Research vol81 no 1 pp 177ndash184 2011

[23] S-K Chung ldquoA phase tracking system for three phase utilityinterface invertersrdquo IEEE Transactions on Power Electronics vol15 no 3 pp 431ndash438 2000

[24] R Dufo-Lopez J L Bernal-Agustın and F Mendoza ldquoDesignand economical analysis of hybrid PV-wind systems connectedto the grid for the intermittent production of hydrogenrdquo EnergyPolicy vol 37 no 8 pp 3082ndash3095 2009

[25] T Burton D Sharpe N Jenkins and E BossanyiWind EnergyHandbook John Wiley amp Sons West Sussex UK 2001

[26] Union for Coordination of Transmission of Electricity ldquoWindPower in the UCTE interconnected Systemrdquo November2004 httpswwwentsoeeufileadminuser upload librarypublicationsceotherreportsWind Power 20041125pdf

[27] E Spooner and A C Williamson ldquoDirect coupled permanentmagnet generators for wind turbine applicationsrdquo IEE Proceed-ings Electric Power Applications vol 143 no 1 pp 1ndash8 1996

[28] N Laverdure S Bacha D Roye B Raison and F DumasldquoElements of modelling of wind power systems with energymanagement two structures in comparisonrdquo in Proceedings ofthe 28th IEEE Annual Conference of the Industrial ElectronicsSociety vol 2 pp 1083ndash1088 November 2002

[29] L Krichen B Francois and A Ouali ldquoA fuzzy logic supervisorfor active and reactive power control of a fixed speed windenergy conversion systemrdquo Electric Power Systems Research vol78 no 3 pp 418ndash424 2008

[30] The Cres Wind Farm ldquo301 MW Demonstration wind farmin Greece Various wind energy technologies in complex Ter-rain topographyrdquo httpwwwcreswindfarmgrsite1ArticlesV47 USpdf

[31] T AckermannWind Power in Power Systems Royal Institute ofTechnology John Wiley amp Sons Stockholm Sweden 2005

[32] F Poitiers Asynchronous generator study and control for thewind energy use [PhD thesis] University of Nantes NantesFrance 2003

[33] M Kacira M Simsek Y Babur and S Demirkol ldquoDeterminingoptimum tilt angles and orientations of photovoltaic panels inSanliurfa Turkeyrdquo Renewable Energy vol 29 no 8 pp 1265ndash1275 2004

[34] D Saheb-Koussa M Belhamel and K Benferhat ldquoContribu-tion a lrsquoetude theorique du comportement drsquoun systeme hybride(eolien- photovoltaıque- diesel) de production drsquoelectricite sansinterruptionrdquo Afrique Science vol 5 no 1 2009

[35] HOMERmdashGetting Started Guide for HOMER Version 21National Renewable Energy Laboratory US Department ofEnergyOffice of EnergyEfficiency andRenewable Energy 2005

[36] C D Barley C B Winn L Flowers and H J Green ldquoOptimalcontrol of remote hybrid power systemsmdashpart I simplifiedmodelrdquo in Proceedings of National Avian-Wind Power PlanningMeeting Washington DC USA 1995

[37] D Saheb-Koussa ldquoEtude technique economique et environ-nementale des systemes decentralises connectes au reseauelectriquerdquo Bulletin des Energies Renouvelables vol 23 pp 15ndash17 2012

[38] V Courtecuisse Supervision drsquoune centrale multi sources a basedrsquoeoliennes et de stockage drsquoenergie connectee au reseau electrique[These de doctorat] Ecole Nationale des Arts et Metiers 2008

TribologyAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Industrial EngineeringJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Renewable Energy

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StructuresJournal of

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear InstallationsScience and Technology of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Solar EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Wind EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear EnergyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

The Scientific World Journal 9

0 1000 2000 3000 4000 5000 6000 7000 8000 90000

500

1000

1500

2000

2500

3000

Time (h)

Pow

er (k

W)

Injected power into the gridPMAX-GRID

Figure 10 Power injected into the grid

1365 MWhyr

7225 MWhyr21

27225 MWhyr78

Photovoltaic systemWind systemGrid

Figure 11 Structure of the production system (PV-wind-grid)

26

48

26

Photovoltaic systemWind systemConverter

Figure 12 Distribution of operation hours of each of the renewableenergy equipment of the hybrid PV-wind-Grid system

05 1 15 2 25 3 35 4 450

20406080

100120140

Photovoltaic systemWind system

GridConverter

106$

Figure 13 Net present cost

05 1 15 2 25 3 35 4 4502468

1012

Photovoltaic systemWind system

GridConverter

106$yr

Figure 14 Annual net cost

Table 1 Cost comparison between a standard system (grid) and ahybrid system (PV-wind-grid)

Cost Conventional systemgrid

Hybrid systemPV-wind-grid

NPC ($yr) 177714200 177090600COE ($kWh) 04 0399

Table 2 Emissions comparison between a standard system (grid)and a hybrid system (PV-wind-grid)

Pollutant Kgyr Conventional systemgrid

Hybrid systemPV-wind-grid

CO2 21965160 17199524SO2 95229 74568NO119909

46572 36467

if the price per produced kWh of the latter is set to $04kWhHowever the net present cost is calculated for a projectlifetime period of 25 years and on the basis of an interest rateof 6 Figures 13 and 14 show the details of the correspondingcosts to each of the systems and the related annual costs [37]

57 Environmental Aspects The results regarding the effectsof each system configuration that is the conventional gridand the hybrid system (PV-wind-grid) on the environmentobtained by again using HOMER software in the caseof the Adrar site are shown in Table 2 [37] In this tablethe quantities of the main gases that are harmful to theenvironment including CO

2 SO2 and NOx are presented

10 The Scientific World Journal

160

165

170

175

180

72 76 80 84 88036

037

038

039

040

041

Leve

lized

cost

of en

ergy

($k

Wh)

Levelized cost of energy versus wind speed

Wind speed (ms)

Tota

l net

pre

sent

cost

($)

Levelized cost of energyTotal net present cost

Fixed

times106

Global solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 15 The relationship between cost and wind speed

72 76 80 84 88000

005

010

015

020

025

Rene

wab

le fr

actio

n

Renewable fraction versus wind speed

Wind speed (ms)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 16 The relationship between RF and wind speed

From these results it is found that the PV-wind-grid hybridsystem produces a reduction in the carbon dioxide gassulfur dioxide and nitrogen oxide rates by respectively 2022 and 22 as compared to the quantities produced by theconventional system [37]

58 Sensitivity Results In this study sensitivity analysis wasdone to study the effects of variation in the solar irradiationand wind speed The simulation software simulates thelong-term implementation of the hybrid system based ontheir respective search size for the predefined sensitivityvalues of the componentsThe emissions renewable fractionNPC and COE are simulated based on the three sensitivityvariables wind speed (ms) solar irradiation (kWm2day)and grid electricity price ($kWh) A long-term simulationfor every possible system combination and configurationwas done for a one year period (from January 1st 2005 toDecember 31st 2005) In the present case solar irradiationis set as sensitivity variables 119866 = 35 45 5 55 572 788 kWm2day while wind speed are V = 69 7 75 78 888msMoreover the grid electricity price is also defined as asensitivity variable (119901 = 01 02 03 04 $kWh) A total of 192

72 76 80 84 8816171819202122

Wind speed (ms)

times106

CO2

emiss

ions

(kg

yr)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

CO2 emissions versus wind speed

Figure 17The relationship betweenCO2emissions andwind speed

72 76 80 84 8830405060708090

100

Wind speed (ms)SO

2em

issio

ns (k

gyr

) SO2 emissions versus wind speed

SO2 emissionsNOx emissions

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 18 The relationship between sulfur dioxide and nitrogenoxide emissions and wind speed

sensitivity cases were tried for each system configurationThesimulation timewas 23minutes and 46 seconds on a personalcomputer with Intel CORE Intel Core Duo Processor of253GHz and a RAM of 2GBThe sensitivity results in termsof solar irradiation wind speed and grid electricity priceanalyze the feasibility of each system Here the feasibilityof hybrid renewable energy system is analyzed based onemission reduction and cost saving This type of sensitivityanalysis of the systems provides information that a particularsystem would be optimal at certain sensitivity variables [19]The PV-wind system is feasible when the grid electricityprice is more than $04 kWh Under this condition the RFcan be between 021 and 022 A PV-wind system is feasiblewhen global solar irradiation is more than 572 kWhm2 perday and the grid electricity price is more expensive than$04 kWh Based on the optimization results wind energyproduction shows a bigger proportion of energy generationthan solar While the solar power occupies less than 1 of thetotal energy generation wind power occupies approximatelya quarter

Therefore the wind energy resource has more impact onthe implementation Figures 15ndash18 reflect the cost renewablefraction and emission variation dependent on the sensitivityvariable wind speed The NPC and COE of the hybrid power

The Scientific World Journal 11

system reduce when the wind speed increases from 69ms to88ms Figure 15

Simultaneously as seen in Figure 16 renewable fractionrises sharply from 0 to 16 (when wind speed increases from69 to 7ms) and then steadily increases to 24 at a slowerrate In addition as shown in Figures 17 and 18 the mainemissions of carbon dioxide sulfur dioxide and nitrogenoxide persistently decrease 22

6 Problems Encountered in DecentralizedSystems [37]

The major difficulty associated with decentralized energysources is that they generally do not participate in ancillaryservices (voltage control frequency ability to operate instandalone mode etc) This is especially true for renewableenergy sources whose power flow is unpredictable and veryvolatile The integration of decentralized energy generationinto power networks raises the following problems

(i) random and unpredictable energy production (windsolar)

(ii) lack of power-frequency control(iii) no voltage adjustment performed(iv) sensitivity to voltage dips(v) significant sensitivity to changes in primary source

(wind solar) energy levels

The failure to take part in system services makes thistype of sources behave as passive generators from theelectrical energy generation point of view The penetrationof distributed energy generation must be limited from 20 to30 of the consumed power in order to guarantee acceptablesystem stability [19]

7 Conclusion

This study is related to the technical economic and envi-ronmental impact of grid-connected decentralized systems towhich an appropriatemanagement of energy is applied andbymeans of which are developed models of the different partsThe solar and wind energy resource data are collected fromthe weather station of Adrar which is a typical arid regionThe most significant results are as follows

The power that any subsystem can deliver depends on theweather conditions of the considered site

The PV based system only covers 1 of the total loadconsumption On the other hand the wind generator con-tribution amounts to about 21 of the energy productionwhile the remaining 78 are supplied by the conventionalelectricity grid

From an economic point of view it is found that for theAdrar site which is characterized by a high wind potentialthe hybrid system is competitive compared with the conven-tional system with a cost of the energy COE produced by thenetwork equal to $04kWh since the estimated COE relatedto the hybrid system is equal to $0399kWh based on anaverage wind speed greater than or equal to 6ms

From an environmental standpoint the rates of green-house gases (CO

2 SO2 andNOx) emissions are reduced from

20 to 22 in the case of a hybrid system compared with theconventional system

The sensitivity analysis indicates that PV-wind hybridsystem is feasible under the meteorological conditions inAdrar region With the increasing wind speed the NPCCOE and emissions of the hybrid renewable energy systemreduce and renewable fraction grows up

Conflict of Interests

None of the authors of this paper has a financial or personalrelationship with other people or organisations that couldinappropriately influence or bias the content of the paper

References

[1] J Koo K Park D Shin and E S Yoon ldquoEconomic evaluationof renewable energy systems under varying scenarios and itsimplications to Korearsquos renewable energy planrdquo Applied Energyvol 88 no 6 pp 2254ndash2260 2011

[2] World Energy Outlook IEA Paris France 2008[3] KHofman andX Li ldquoCanadarsquos energy perspectives andpolicies

for sustainable developmentrdquo Applied Energy vol 86 no 4 pp407ndash415 2009

[4] H Weigt ldquoGermanyrsquos wind energy the potential for fossilcapacity replacement and cost savingrdquo Applied Energy vol 86no 10 pp 1857ndash1863 2009

[5] S A Khan R Rashmi M Z Hussain S Prasad and U CBanerjee ldquoProspects of biodiesel production from microalgaein Indiardquo Renewable and Sustainable Energy Reviews vol 13 no9 pp 2361ndash2372 2009

[6] E S Yoon ldquoA review on sustainable energy recent devel-opments and future prospects of dimethyl ether (DME)rdquo inProceedings of the 10th International Symposium on ProcessSystems Engineering (PSE rsquo09) Bahia Brazil 2009

[7] ldquoAdrar lancement des travaux du projet de la ferme eoliennerdquo2011 httpwwwalgerie360comalgerieadrar-lancement-des-travaux-du-projet-de-la-ferme-eolienne

[8] A Ducluzaux ldquoLrsquoenergie electrique drsquoorigine eoliennerdquo in Con-ference sur lrsquoEnergie Grenoble France 2004

[9] S Nguefeu M Arab X Waymel and F Costa ldquoPWM invertersin decentralized generation systems characterization of thedynamic behavior under utility fault conditionsrdquo InternationalJournal of Distributed Energy Resources vol 2 no 2 pp 101ndash1142006

[10] G Panayiotou S Kalogirou and S Tassou ldquoDesign andsimulation of a PV and a PV-Wind standalone energy systemto power a household applicationrdquo Renewable Energy vol 37no 1 pp 355ndash363 2012

[11] S M Shaahid ldquoReview of research on autonomous wind farmsand solar parks and their feasibility for commercial loads in hotregionsrdquo Renewable and Sustainable Energy Reviews vol 15 no8 pp 3877ndash3887 2011

[12] M A Elhadidy and S M Shaahid ldquoParametric study of hybrid(wind + solar + diesel) power generating systemsrdquo RenewableEnergy vol 21 no 2 pp 129ndash139 2000

12 The Scientific World Journal

[13] S M Shaahid and M A Elhadidy ldquoTechnical and economicassessment of grid-independent hybrid photovoltaic-diesel-battery power systems for commercial loads in desert environ-mentsrdquo Renewable and Sustainable Energy Reviews vol 11 no8 pp 1794ndash1810 2007

[14] D Saheb-Koussa M Haddadi and M Belhamel ldquoEconomicand technical study of a hybrid system (wind-photovoltaic-diesel) for rural electrification in Algeriardquo Applied Energy vol86 no 7-8 pp 1024ndash1030 2009

[15] G J Dalton D A Lockington and T E Baldock ldquoFeasibilityanalysis of stand-alone renewable energy supply options for alarge hotelrdquo Renewable Energy vol 33 no 7 pp 1475ndash14902008

[16] ANCelik ldquoPresent status of photovoltaic energy inTurkey andlife cycle techno-economic analysis of a grid-connected pho-tovoltaic-houserdquo Renewable and Sustainable Energy Reviewsvol 10 no 4 pp 370ndash387 2006

[17] M A H Mondal and M Denich ldquoAssessment of renew-able energy resources potential for electricity generation inBangladeshrdquoRenewable and Sustainable Energy Reviews vol 14no 7 pp 2401ndash2413 2010

[18] D Saheb-Koussa M Haddadi M Belhamel S Hadji and SNouredine ldquoModeling and simulation of the fixed-speedWECS(wind energy conversion system) application to the AlgerianSahara areardquo Energy vol 35 no 10 pp 4116ndash4125 2010

[19] S Rehman I M El-Amin F Ahmad et al ldquoFeasibility studyof hybrid retrofits to an isolated off-grid diesel power plantrdquoRenewable and Sustainable Energy Reviews vol 11 no 4 pp635ndash653 2007

[20] S Singer B Rozenshtein and S Surazi ldquoCharacterization of PVarray output using a small number of measured parametersrdquoSolar Energy vol 32 no 5 pp 603ndash607 1984

[21] D Saheb-Koussa ldquoContribution a lrsquoetude theorique du com-portement drsquoun systeme hybride (eolien- photovoltaıque-diesel) de production drsquoelectricite sans interruptionrdquo Memoirede magister Blida Septembre 2005

[22] G Tsengenes and G Adamidis ldquoInvestigation of the behaviorof a three phase grid-connected photovoltaic system to controlactive and reactive powerrdquo Electric Power Systems Research vol81 no 1 pp 177ndash184 2011

[23] S-K Chung ldquoA phase tracking system for three phase utilityinterface invertersrdquo IEEE Transactions on Power Electronics vol15 no 3 pp 431ndash438 2000

[24] R Dufo-Lopez J L Bernal-Agustın and F Mendoza ldquoDesignand economical analysis of hybrid PV-wind systems connectedto the grid for the intermittent production of hydrogenrdquo EnergyPolicy vol 37 no 8 pp 3082ndash3095 2009

[25] T Burton D Sharpe N Jenkins and E BossanyiWind EnergyHandbook John Wiley amp Sons West Sussex UK 2001

[26] Union for Coordination of Transmission of Electricity ldquoWindPower in the UCTE interconnected Systemrdquo November2004 httpswwwentsoeeufileadminuser upload librarypublicationsceotherreportsWind Power 20041125pdf

[27] E Spooner and A C Williamson ldquoDirect coupled permanentmagnet generators for wind turbine applicationsrdquo IEE Proceed-ings Electric Power Applications vol 143 no 1 pp 1ndash8 1996

[28] N Laverdure S Bacha D Roye B Raison and F DumasldquoElements of modelling of wind power systems with energymanagement two structures in comparisonrdquo in Proceedings ofthe 28th IEEE Annual Conference of the Industrial ElectronicsSociety vol 2 pp 1083ndash1088 November 2002

[29] L Krichen B Francois and A Ouali ldquoA fuzzy logic supervisorfor active and reactive power control of a fixed speed windenergy conversion systemrdquo Electric Power Systems Research vol78 no 3 pp 418ndash424 2008

[30] The Cres Wind Farm ldquo301 MW Demonstration wind farmin Greece Various wind energy technologies in complex Ter-rain topographyrdquo httpwwwcreswindfarmgrsite1ArticlesV47 USpdf

[31] T AckermannWind Power in Power Systems Royal Institute ofTechnology John Wiley amp Sons Stockholm Sweden 2005

[32] F Poitiers Asynchronous generator study and control for thewind energy use [PhD thesis] University of Nantes NantesFrance 2003

[33] M Kacira M Simsek Y Babur and S Demirkol ldquoDeterminingoptimum tilt angles and orientations of photovoltaic panels inSanliurfa Turkeyrdquo Renewable Energy vol 29 no 8 pp 1265ndash1275 2004

[34] D Saheb-Koussa M Belhamel and K Benferhat ldquoContribu-tion a lrsquoetude theorique du comportement drsquoun systeme hybride(eolien- photovoltaıque- diesel) de production drsquoelectricite sansinterruptionrdquo Afrique Science vol 5 no 1 2009

[35] HOMERmdashGetting Started Guide for HOMER Version 21National Renewable Energy Laboratory US Department ofEnergyOffice of EnergyEfficiency andRenewable Energy 2005

[36] C D Barley C B Winn L Flowers and H J Green ldquoOptimalcontrol of remote hybrid power systemsmdashpart I simplifiedmodelrdquo in Proceedings of National Avian-Wind Power PlanningMeeting Washington DC USA 1995

[37] D Saheb-Koussa ldquoEtude technique economique et environ-nementale des systemes decentralises connectes au reseauelectriquerdquo Bulletin des Energies Renouvelables vol 23 pp 15ndash17 2012

[38] V Courtecuisse Supervision drsquoune centrale multi sources a basedrsquoeoliennes et de stockage drsquoenergie connectee au reseau electrique[These de doctorat] Ecole Nationale des Arts et Metiers 2008

TribologyAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Industrial EngineeringJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Renewable Energy

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StructuresJournal of

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear InstallationsScience and Technology of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Solar EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Wind EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear EnergyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

10 The Scientific World Journal

160

165

170

175

180

72 76 80 84 88036

037

038

039

040

041

Leve

lized

cost

of en

ergy

($k

Wh)

Levelized cost of energy versus wind speed

Wind speed (ms)

Tota

l net

pre

sent

cost

($)

Levelized cost of energyTotal net present cost

Fixed

times106

Global solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 15 The relationship between cost and wind speed

72 76 80 84 88000

005

010

015

020

025

Rene

wab

le fr

actio

n

Renewable fraction versus wind speed

Wind speed (ms)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 16 The relationship between RF and wind speed

From these results it is found that the PV-wind-grid hybridsystem produces a reduction in the carbon dioxide gassulfur dioxide and nitrogen oxide rates by respectively 2022 and 22 as compared to the quantities produced by theconventional system [37]

58 Sensitivity Results In this study sensitivity analysis wasdone to study the effects of variation in the solar irradiationand wind speed The simulation software simulates thelong-term implementation of the hybrid system based ontheir respective search size for the predefined sensitivityvalues of the componentsThe emissions renewable fractionNPC and COE are simulated based on the three sensitivityvariables wind speed (ms) solar irradiation (kWm2day)and grid electricity price ($kWh) A long-term simulationfor every possible system combination and configurationwas done for a one year period (from January 1st 2005 toDecember 31st 2005) In the present case solar irradiationis set as sensitivity variables 119866 = 35 45 5 55 572 788 kWm2day while wind speed are V = 69 7 75 78 888msMoreover the grid electricity price is also defined as asensitivity variable (119901 = 01 02 03 04 $kWh) A total of 192

72 76 80 84 8816171819202122

Wind speed (ms)

times106

CO2

emiss

ions

(kg

yr)

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

CO2 emissions versus wind speed

Figure 17The relationship betweenCO2emissions andwind speed

72 76 80 84 8830405060708090

100

Wind speed (ms)SO

2em

issio

ns (k

gyr

) SO2 emissions versus wind speed

SO2 emissionsNOx emissions

FixedGlobal solar = 572 kWhm2dRate 1 power price = $04kWh

Figure 18 The relationship between sulfur dioxide and nitrogenoxide emissions and wind speed

sensitivity cases were tried for each system configurationThesimulation timewas 23minutes and 46 seconds on a personalcomputer with Intel CORE Intel Core Duo Processor of253GHz and a RAM of 2GBThe sensitivity results in termsof solar irradiation wind speed and grid electricity priceanalyze the feasibility of each system Here the feasibilityof hybrid renewable energy system is analyzed based onemission reduction and cost saving This type of sensitivityanalysis of the systems provides information that a particularsystem would be optimal at certain sensitivity variables [19]The PV-wind system is feasible when the grid electricityprice is more than $04 kWh Under this condition the RFcan be between 021 and 022 A PV-wind system is feasiblewhen global solar irradiation is more than 572 kWhm2 perday and the grid electricity price is more expensive than$04 kWh Based on the optimization results wind energyproduction shows a bigger proportion of energy generationthan solar While the solar power occupies less than 1 of thetotal energy generation wind power occupies approximatelya quarter

Therefore the wind energy resource has more impact onthe implementation Figures 15ndash18 reflect the cost renewablefraction and emission variation dependent on the sensitivityvariable wind speed The NPC and COE of the hybrid power

The Scientific World Journal 11

system reduce when the wind speed increases from 69ms to88ms Figure 15

Simultaneously as seen in Figure 16 renewable fractionrises sharply from 0 to 16 (when wind speed increases from69 to 7ms) and then steadily increases to 24 at a slowerrate In addition as shown in Figures 17 and 18 the mainemissions of carbon dioxide sulfur dioxide and nitrogenoxide persistently decrease 22

6 Problems Encountered in DecentralizedSystems [37]

The major difficulty associated with decentralized energysources is that they generally do not participate in ancillaryservices (voltage control frequency ability to operate instandalone mode etc) This is especially true for renewableenergy sources whose power flow is unpredictable and veryvolatile The integration of decentralized energy generationinto power networks raises the following problems

(i) random and unpredictable energy production (windsolar)

(ii) lack of power-frequency control(iii) no voltage adjustment performed(iv) sensitivity to voltage dips(v) significant sensitivity to changes in primary source

(wind solar) energy levels

The failure to take part in system services makes thistype of sources behave as passive generators from theelectrical energy generation point of view The penetrationof distributed energy generation must be limited from 20 to30 of the consumed power in order to guarantee acceptablesystem stability [19]

7 Conclusion

This study is related to the technical economic and envi-ronmental impact of grid-connected decentralized systems towhich an appropriatemanagement of energy is applied andbymeans of which are developed models of the different partsThe solar and wind energy resource data are collected fromthe weather station of Adrar which is a typical arid regionThe most significant results are as follows

The power that any subsystem can deliver depends on theweather conditions of the considered site

The PV based system only covers 1 of the total loadconsumption On the other hand the wind generator con-tribution amounts to about 21 of the energy productionwhile the remaining 78 are supplied by the conventionalelectricity grid

From an economic point of view it is found that for theAdrar site which is characterized by a high wind potentialthe hybrid system is competitive compared with the conven-tional system with a cost of the energy COE produced by thenetwork equal to $04kWh since the estimated COE relatedto the hybrid system is equal to $0399kWh based on anaverage wind speed greater than or equal to 6ms

From an environmental standpoint the rates of green-house gases (CO

2 SO2 andNOx) emissions are reduced from

20 to 22 in the case of a hybrid system compared with theconventional system

The sensitivity analysis indicates that PV-wind hybridsystem is feasible under the meteorological conditions inAdrar region With the increasing wind speed the NPCCOE and emissions of the hybrid renewable energy systemreduce and renewable fraction grows up

Conflict of Interests

None of the authors of this paper has a financial or personalrelationship with other people or organisations that couldinappropriately influence or bias the content of the paper

References

[1] J Koo K Park D Shin and E S Yoon ldquoEconomic evaluationof renewable energy systems under varying scenarios and itsimplications to Korearsquos renewable energy planrdquo Applied Energyvol 88 no 6 pp 2254ndash2260 2011

[2] World Energy Outlook IEA Paris France 2008[3] KHofman andX Li ldquoCanadarsquos energy perspectives andpolicies

for sustainable developmentrdquo Applied Energy vol 86 no 4 pp407ndash415 2009

[4] H Weigt ldquoGermanyrsquos wind energy the potential for fossilcapacity replacement and cost savingrdquo Applied Energy vol 86no 10 pp 1857ndash1863 2009

[5] S A Khan R Rashmi M Z Hussain S Prasad and U CBanerjee ldquoProspects of biodiesel production from microalgaein Indiardquo Renewable and Sustainable Energy Reviews vol 13 no9 pp 2361ndash2372 2009

[6] E S Yoon ldquoA review on sustainable energy recent devel-opments and future prospects of dimethyl ether (DME)rdquo inProceedings of the 10th International Symposium on ProcessSystems Engineering (PSE rsquo09) Bahia Brazil 2009

[7] ldquoAdrar lancement des travaux du projet de la ferme eoliennerdquo2011 httpwwwalgerie360comalgerieadrar-lancement-des-travaux-du-projet-de-la-ferme-eolienne

[8] A Ducluzaux ldquoLrsquoenergie electrique drsquoorigine eoliennerdquo in Con-ference sur lrsquoEnergie Grenoble France 2004

[9] S Nguefeu M Arab X Waymel and F Costa ldquoPWM invertersin decentralized generation systems characterization of thedynamic behavior under utility fault conditionsrdquo InternationalJournal of Distributed Energy Resources vol 2 no 2 pp 101ndash1142006

[10] G Panayiotou S Kalogirou and S Tassou ldquoDesign andsimulation of a PV and a PV-Wind standalone energy systemto power a household applicationrdquo Renewable Energy vol 37no 1 pp 355ndash363 2012

[11] S M Shaahid ldquoReview of research on autonomous wind farmsand solar parks and their feasibility for commercial loads in hotregionsrdquo Renewable and Sustainable Energy Reviews vol 15 no8 pp 3877ndash3887 2011

[12] M A Elhadidy and S M Shaahid ldquoParametric study of hybrid(wind + solar + diesel) power generating systemsrdquo RenewableEnergy vol 21 no 2 pp 129ndash139 2000

12 The Scientific World Journal

[13] S M Shaahid and M A Elhadidy ldquoTechnical and economicassessment of grid-independent hybrid photovoltaic-diesel-battery power systems for commercial loads in desert environ-mentsrdquo Renewable and Sustainable Energy Reviews vol 11 no8 pp 1794ndash1810 2007

[14] D Saheb-Koussa M Haddadi and M Belhamel ldquoEconomicand technical study of a hybrid system (wind-photovoltaic-diesel) for rural electrification in Algeriardquo Applied Energy vol86 no 7-8 pp 1024ndash1030 2009

[15] G J Dalton D A Lockington and T E Baldock ldquoFeasibilityanalysis of stand-alone renewable energy supply options for alarge hotelrdquo Renewable Energy vol 33 no 7 pp 1475ndash14902008

[16] ANCelik ldquoPresent status of photovoltaic energy inTurkey andlife cycle techno-economic analysis of a grid-connected pho-tovoltaic-houserdquo Renewable and Sustainable Energy Reviewsvol 10 no 4 pp 370ndash387 2006

[17] M A H Mondal and M Denich ldquoAssessment of renew-able energy resources potential for electricity generation inBangladeshrdquoRenewable and Sustainable Energy Reviews vol 14no 7 pp 2401ndash2413 2010

[18] D Saheb-Koussa M Haddadi M Belhamel S Hadji and SNouredine ldquoModeling and simulation of the fixed-speedWECS(wind energy conversion system) application to the AlgerianSahara areardquo Energy vol 35 no 10 pp 4116ndash4125 2010

[19] S Rehman I M El-Amin F Ahmad et al ldquoFeasibility studyof hybrid retrofits to an isolated off-grid diesel power plantrdquoRenewable and Sustainable Energy Reviews vol 11 no 4 pp635ndash653 2007

[20] S Singer B Rozenshtein and S Surazi ldquoCharacterization of PVarray output using a small number of measured parametersrdquoSolar Energy vol 32 no 5 pp 603ndash607 1984

[21] D Saheb-Koussa ldquoContribution a lrsquoetude theorique du com-portement drsquoun systeme hybride (eolien- photovoltaıque-diesel) de production drsquoelectricite sans interruptionrdquo Memoirede magister Blida Septembre 2005

[22] G Tsengenes and G Adamidis ldquoInvestigation of the behaviorof a three phase grid-connected photovoltaic system to controlactive and reactive powerrdquo Electric Power Systems Research vol81 no 1 pp 177ndash184 2011

[23] S-K Chung ldquoA phase tracking system for three phase utilityinterface invertersrdquo IEEE Transactions on Power Electronics vol15 no 3 pp 431ndash438 2000

[24] R Dufo-Lopez J L Bernal-Agustın and F Mendoza ldquoDesignand economical analysis of hybrid PV-wind systems connectedto the grid for the intermittent production of hydrogenrdquo EnergyPolicy vol 37 no 8 pp 3082ndash3095 2009

[25] T Burton D Sharpe N Jenkins and E BossanyiWind EnergyHandbook John Wiley amp Sons West Sussex UK 2001

[26] Union for Coordination of Transmission of Electricity ldquoWindPower in the UCTE interconnected Systemrdquo November2004 httpswwwentsoeeufileadminuser upload librarypublicationsceotherreportsWind Power 20041125pdf

[27] E Spooner and A C Williamson ldquoDirect coupled permanentmagnet generators for wind turbine applicationsrdquo IEE Proceed-ings Electric Power Applications vol 143 no 1 pp 1ndash8 1996

[28] N Laverdure S Bacha D Roye B Raison and F DumasldquoElements of modelling of wind power systems with energymanagement two structures in comparisonrdquo in Proceedings ofthe 28th IEEE Annual Conference of the Industrial ElectronicsSociety vol 2 pp 1083ndash1088 November 2002

[29] L Krichen B Francois and A Ouali ldquoA fuzzy logic supervisorfor active and reactive power control of a fixed speed windenergy conversion systemrdquo Electric Power Systems Research vol78 no 3 pp 418ndash424 2008

[30] The Cres Wind Farm ldquo301 MW Demonstration wind farmin Greece Various wind energy technologies in complex Ter-rain topographyrdquo httpwwwcreswindfarmgrsite1ArticlesV47 USpdf

[31] T AckermannWind Power in Power Systems Royal Institute ofTechnology John Wiley amp Sons Stockholm Sweden 2005

[32] F Poitiers Asynchronous generator study and control for thewind energy use [PhD thesis] University of Nantes NantesFrance 2003

[33] M Kacira M Simsek Y Babur and S Demirkol ldquoDeterminingoptimum tilt angles and orientations of photovoltaic panels inSanliurfa Turkeyrdquo Renewable Energy vol 29 no 8 pp 1265ndash1275 2004

[34] D Saheb-Koussa M Belhamel and K Benferhat ldquoContribu-tion a lrsquoetude theorique du comportement drsquoun systeme hybride(eolien- photovoltaıque- diesel) de production drsquoelectricite sansinterruptionrdquo Afrique Science vol 5 no 1 2009

[35] HOMERmdashGetting Started Guide for HOMER Version 21National Renewable Energy Laboratory US Department ofEnergyOffice of EnergyEfficiency andRenewable Energy 2005

[36] C D Barley C B Winn L Flowers and H J Green ldquoOptimalcontrol of remote hybrid power systemsmdashpart I simplifiedmodelrdquo in Proceedings of National Avian-Wind Power PlanningMeeting Washington DC USA 1995

[37] D Saheb-Koussa ldquoEtude technique economique et environ-nementale des systemes decentralises connectes au reseauelectriquerdquo Bulletin des Energies Renouvelables vol 23 pp 15ndash17 2012

[38] V Courtecuisse Supervision drsquoune centrale multi sources a basedrsquoeoliennes et de stockage drsquoenergie connectee au reseau electrique[These de doctorat] Ecole Nationale des Arts et Metiers 2008

TribologyAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Industrial EngineeringJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Renewable Energy

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StructuresJournal of

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear InstallationsScience and Technology of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Solar EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Wind EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear EnergyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

The Scientific World Journal 11

system reduce when the wind speed increases from 69ms to88ms Figure 15

Simultaneously as seen in Figure 16 renewable fractionrises sharply from 0 to 16 (when wind speed increases from69 to 7ms) and then steadily increases to 24 at a slowerrate In addition as shown in Figures 17 and 18 the mainemissions of carbon dioxide sulfur dioxide and nitrogenoxide persistently decrease 22

6 Problems Encountered in DecentralizedSystems [37]

The major difficulty associated with decentralized energysources is that they generally do not participate in ancillaryservices (voltage control frequency ability to operate instandalone mode etc) This is especially true for renewableenergy sources whose power flow is unpredictable and veryvolatile The integration of decentralized energy generationinto power networks raises the following problems

(i) random and unpredictable energy production (windsolar)

(ii) lack of power-frequency control(iii) no voltage adjustment performed(iv) sensitivity to voltage dips(v) significant sensitivity to changes in primary source

(wind solar) energy levels

The failure to take part in system services makes thistype of sources behave as passive generators from theelectrical energy generation point of view The penetrationof distributed energy generation must be limited from 20 to30 of the consumed power in order to guarantee acceptablesystem stability [19]

7 Conclusion

This study is related to the technical economic and envi-ronmental impact of grid-connected decentralized systems towhich an appropriatemanagement of energy is applied andbymeans of which are developed models of the different partsThe solar and wind energy resource data are collected fromthe weather station of Adrar which is a typical arid regionThe most significant results are as follows

The power that any subsystem can deliver depends on theweather conditions of the considered site

The PV based system only covers 1 of the total loadconsumption On the other hand the wind generator con-tribution amounts to about 21 of the energy productionwhile the remaining 78 are supplied by the conventionalelectricity grid

From an economic point of view it is found that for theAdrar site which is characterized by a high wind potentialthe hybrid system is competitive compared with the conven-tional system with a cost of the energy COE produced by thenetwork equal to $04kWh since the estimated COE relatedto the hybrid system is equal to $0399kWh based on anaverage wind speed greater than or equal to 6ms

From an environmental standpoint the rates of green-house gases (CO

2 SO2 andNOx) emissions are reduced from

20 to 22 in the case of a hybrid system compared with theconventional system

The sensitivity analysis indicates that PV-wind hybridsystem is feasible under the meteorological conditions inAdrar region With the increasing wind speed the NPCCOE and emissions of the hybrid renewable energy systemreduce and renewable fraction grows up

Conflict of Interests

None of the authors of this paper has a financial or personalrelationship with other people or organisations that couldinappropriately influence or bias the content of the paper

References

[1] J Koo K Park D Shin and E S Yoon ldquoEconomic evaluationof renewable energy systems under varying scenarios and itsimplications to Korearsquos renewable energy planrdquo Applied Energyvol 88 no 6 pp 2254ndash2260 2011

[2] World Energy Outlook IEA Paris France 2008[3] KHofman andX Li ldquoCanadarsquos energy perspectives andpolicies

for sustainable developmentrdquo Applied Energy vol 86 no 4 pp407ndash415 2009

[4] H Weigt ldquoGermanyrsquos wind energy the potential for fossilcapacity replacement and cost savingrdquo Applied Energy vol 86no 10 pp 1857ndash1863 2009

[5] S A Khan R Rashmi M Z Hussain S Prasad and U CBanerjee ldquoProspects of biodiesel production from microalgaein Indiardquo Renewable and Sustainable Energy Reviews vol 13 no9 pp 2361ndash2372 2009

[6] E S Yoon ldquoA review on sustainable energy recent devel-opments and future prospects of dimethyl ether (DME)rdquo inProceedings of the 10th International Symposium on ProcessSystems Engineering (PSE rsquo09) Bahia Brazil 2009

[7] ldquoAdrar lancement des travaux du projet de la ferme eoliennerdquo2011 httpwwwalgerie360comalgerieadrar-lancement-des-travaux-du-projet-de-la-ferme-eolienne

[8] A Ducluzaux ldquoLrsquoenergie electrique drsquoorigine eoliennerdquo in Con-ference sur lrsquoEnergie Grenoble France 2004

[9] S Nguefeu M Arab X Waymel and F Costa ldquoPWM invertersin decentralized generation systems characterization of thedynamic behavior under utility fault conditionsrdquo InternationalJournal of Distributed Energy Resources vol 2 no 2 pp 101ndash1142006

[10] G Panayiotou S Kalogirou and S Tassou ldquoDesign andsimulation of a PV and a PV-Wind standalone energy systemto power a household applicationrdquo Renewable Energy vol 37no 1 pp 355ndash363 2012

[11] S M Shaahid ldquoReview of research on autonomous wind farmsand solar parks and their feasibility for commercial loads in hotregionsrdquo Renewable and Sustainable Energy Reviews vol 15 no8 pp 3877ndash3887 2011

[12] M A Elhadidy and S M Shaahid ldquoParametric study of hybrid(wind + solar + diesel) power generating systemsrdquo RenewableEnergy vol 21 no 2 pp 129ndash139 2000

12 The Scientific World Journal

[13] S M Shaahid and M A Elhadidy ldquoTechnical and economicassessment of grid-independent hybrid photovoltaic-diesel-battery power systems for commercial loads in desert environ-mentsrdquo Renewable and Sustainable Energy Reviews vol 11 no8 pp 1794ndash1810 2007

[14] D Saheb-Koussa M Haddadi and M Belhamel ldquoEconomicand technical study of a hybrid system (wind-photovoltaic-diesel) for rural electrification in Algeriardquo Applied Energy vol86 no 7-8 pp 1024ndash1030 2009

[15] G J Dalton D A Lockington and T E Baldock ldquoFeasibilityanalysis of stand-alone renewable energy supply options for alarge hotelrdquo Renewable Energy vol 33 no 7 pp 1475ndash14902008

[16] ANCelik ldquoPresent status of photovoltaic energy inTurkey andlife cycle techno-economic analysis of a grid-connected pho-tovoltaic-houserdquo Renewable and Sustainable Energy Reviewsvol 10 no 4 pp 370ndash387 2006

[17] M A H Mondal and M Denich ldquoAssessment of renew-able energy resources potential for electricity generation inBangladeshrdquoRenewable and Sustainable Energy Reviews vol 14no 7 pp 2401ndash2413 2010

[18] D Saheb-Koussa M Haddadi M Belhamel S Hadji and SNouredine ldquoModeling and simulation of the fixed-speedWECS(wind energy conversion system) application to the AlgerianSahara areardquo Energy vol 35 no 10 pp 4116ndash4125 2010

[19] S Rehman I M El-Amin F Ahmad et al ldquoFeasibility studyof hybrid retrofits to an isolated off-grid diesel power plantrdquoRenewable and Sustainable Energy Reviews vol 11 no 4 pp635ndash653 2007

[20] S Singer B Rozenshtein and S Surazi ldquoCharacterization of PVarray output using a small number of measured parametersrdquoSolar Energy vol 32 no 5 pp 603ndash607 1984

[21] D Saheb-Koussa ldquoContribution a lrsquoetude theorique du com-portement drsquoun systeme hybride (eolien- photovoltaıque-diesel) de production drsquoelectricite sans interruptionrdquo Memoirede magister Blida Septembre 2005

[22] G Tsengenes and G Adamidis ldquoInvestigation of the behaviorof a three phase grid-connected photovoltaic system to controlactive and reactive powerrdquo Electric Power Systems Research vol81 no 1 pp 177ndash184 2011

[23] S-K Chung ldquoA phase tracking system for three phase utilityinterface invertersrdquo IEEE Transactions on Power Electronics vol15 no 3 pp 431ndash438 2000

[24] R Dufo-Lopez J L Bernal-Agustın and F Mendoza ldquoDesignand economical analysis of hybrid PV-wind systems connectedto the grid for the intermittent production of hydrogenrdquo EnergyPolicy vol 37 no 8 pp 3082ndash3095 2009

[25] T Burton D Sharpe N Jenkins and E BossanyiWind EnergyHandbook John Wiley amp Sons West Sussex UK 2001

[26] Union for Coordination of Transmission of Electricity ldquoWindPower in the UCTE interconnected Systemrdquo November2004 httpswwwentsoeeufileadminuser upload librarypublicationsceotherreportsWind Power 20041125pdf

[27] E Spooner and A C Williamson ldquoDirect coupled permanentmagnet generators for wind turbine applicationsrdquo IEE Proceed-ings Electric Power Applications vol 143 no 1 pp 1ndash8 1996

[28] N Laverdure S Bacha D Roye B Raison and F DumasldquoElements of modelling of wind power systems with energymanagement two structures in comparisonrdquo in Proceedings ofthe 28th IEEE Annual Conference of the Industrial ElectronicsSociety vol 2 pp 1083ndash1088 November 2002

[29] L Krichen B Francois and A Ouali ldquoA fuzzy logic supervisorfor active and reactive power control of a fixed speed windenergy conversion systemrdquo Electric Power Systems Research vol78 no 3 pp 418ndash424 2008

[30] The Cres Wind Farm ldquo301 MW Demonstration wind farmin Greece Various wind energy technologies in complex Ter-rain topographyrdquo httpwwwcreswindfarmgrsite1ArticlesV47 USpdf

[31] T AckermannWind Power in Power Systems Royal Institute ofTechnology John Wiley amp Sons Stockholm Sweden 2005

[32] F Poitiers Asynchronous generator study and control for thewind energy use [PhD thesis] University of Nantes NantesFrance 2003

[33] M Kacira M Simsek Y Babur and S Demirkol ldquoDeterminingoptimum tilt angles and orientations of photovoltaic panels inSanliurfa Turkeyrdquo Renewable Energy vol 29 no 8 pp 1265ndash1275 2004

[34] D Saheb-Koussa M Belhamel and K Benferhat ldquoContribu-tion a lrsquoetude theorique du comportement drsquoun systeme hybride(eolien- photovoltaıque- diesel) de production drsquoelectricite sansinterruptionrdquo Afrique Science vol 5 no 1 2009

[35] HOMERmdashGetting Started Guide for HOMER Version 21National Renewable Energy Laboratory US Department ofEnergyOffice of EnergyEfficiency andRenewable Energy 2005

[36] C D Barley C B Winn L Flowers and H J Green ldquoOptimalcontrol of remote hybrid power systemsmdashpart I simplifiedmodelrdquo in Proceedings of National Avian-Wind Power PlanningMeeting Washington DC USA 1995

[37] D Saheb-Koussa ldquoEtude technique economique et environ-nementale des systemes decentralises connectes au reseauelectriquerdquo Bulletin des Energies Renouvelables vol 23 pp 15ndash17 2012

[38] V Courtecuisse Supervision drsquoune centrale multi sources a basedrsquoeoliennes et de stockage drsquoenergie connectee au reseau electrique[These de doctorat] Ecole Nationale des Arts et Metiers 2008

TribologyAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Industrial EngineeringJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Renewable Energy

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StructuresJournal of

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear InstallationsScience and Technology of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Solar EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Wind EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear EnergyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

12 The Scientific World Journal

[13] S M Shaahid and M A Elhadidy ldquoTechnical and economicassessment of grid-independent hybrid photovoltaic-diesel-battery power systems for commercial loads in desert environ-mentsrdquo Renewable and Sustainable Energy Reviews vol 11 no8 pp 1794ndash1810 2007

[14] D Saheb-Koussa M Haddadi and M Belhamel ldquoEconomicand technical study of a hybrid system (wind-photovoltaic-diesel) for rural electrification in Algeriardquo Applied Energy vol86 no 7-8 pp 1024ndash1030 2009

[15] G J Dalton D A Lockington and T E Baldock ldquoFeasibilityanalysis of stand-alone renewable energy supply options for alarge hotelrdquo Renewable Energy vol 33 no 7 pp 1475ndash14902008

[16] ANCelik ldquoPresent status of photovoltaic energy inTurkey andlife cycle techno-economic analysis of a grid-connected pho-tovoltaic-houserdquo Renewable and Sustainable Energy Reviewsvol 10 no 4 pp 370ndash387 2006

[17] M A H Mondal and M Denich ldquoAssessment of renew-able energy resources potential for electricity generation inBangladeshrdquoRenewable and Sustainable Energy Reviews vol 14no 7 pp 2401ndash2413 2010

[18] D Saheb-Koussa M Haddadi M Belhamel S Hadji and SNouredine ldquoModeling and simulation of the fixed-speedWECS(wind energy conversion system) application to the AlgerianSahara areardquo Energy vol 35 no 10 pp 4116ndash4125 2010

[19] S Rehman I M El-Amin F Ahmad et al ldquoFeasibility studyof hybrid retrofits to an isolated off-grid diesel power plantrdquoRenewable and Sustainable Energy Reviews vol 11 no 4 pp635ndash653 2007

[20] S Singer B Rozenshtein and S Surazi ldquoCharacterization of PVarray output using a small number of measured parametersrdquoSolar Energy vol 32 no 5 pp 603ndash607 1984

[21] D Saheb-Koussa ldquoContribution a lrsquoetude theorique du com-portement drsquoun systeme hybride (eolien- photovoltaıque-diesel) de production drsquoelectricite sans interruptionrdquo Memoirede magister Blida Septembre 2005

[22] G Tsengenes and G Adamidis ldquoInvestigation of the behaviorof a three phase grid-connected photovoltaic system to controlactive and reactive powerrdquo Electric Power Systems Research vol81 no 1 pp 177ndash184 2011

[23] S-K Chung ldquoA phase tracking system for three phase utilityinterface invertersrdquo IEEE Transactions on Power Electronics vol15 no 3 pp 431ndash438 2000

[24] R Dufo-Lopez J L Bernal-Agustın and F Mendoza ldquoDesignand economical analysis of hybrid PV-wind systems connectedto the grid for the intermittent production of hydrogenrdquo EnergyPolicy vol 37 no 8 pp 3082ndash3095 2009

[25] T Burton D Sharpe N Jenkins and E BossanyiWind EnergyHandbook John Wiley amp Sons West Sussex UK 2001

[26] Union for Coordination of Transmission of Electricity ldquoWindPower in the UCTE interconnected Systemrdquo November2004 httpswwwentsoeeufileadminuser upload librarypublicationsceotherreportsWind Power 20041125pdf

[27] E Spooner and A C Williamson ldquoDirect coupled permanentmagnet generators for wind turbine applicationsrdquo IEE Proceed-ings Electric Power Applications vol 143 no 1 pp 1ndash8 1996

[28] N Laverdure S Bacha D Roye B Raison and F DumasldquoElements of modelling of wind power systems with energymanagement two structures in comparisonrdquo in Proceedings ofthe 28th IEEE Annual Conference of the Industrial ElectronicsSociety vol 2 pp 1083ndash1088 November 2002

[29] L Krichen B Francois and A Ouali ldquoA fuzzy logic supervisorfor active and reactive power control of a fixed speed windenergy conversion systemrdquo Electric Power Systems Research vol78 no 3 pp 418ndash424 2008

[30] The Cres Wind Farm ldquo301 MW Demonstration wind farmin Greece Various wind energy technologies in complex Ter-rain topographyrdquo httpwwwcreswindfarmgrsite1ArticlesV47 USpdf

[31] T AckermannWind Power in Power Systems Royal Institute ofTechnology John Wiley amp Sons Stockholm Sweden 2005

[32] F Poitiers Asynchronous generator study and control for thewind energy use [PhD thesis] University of Nantes NantesFrance 2003

[33] M Kacira M Simsek Y Babur and S Demirkol ldquoDeterminingoptimum tilt angles and orientations of photovoltaic panels inSanliurfa Turkeyrdquo Renewable Energy vol 29 no 8 pp 1265ndash1275 2004

[34] D Saheb-Koussa M Belhamel and K Benferhat ldquoContribu-tion a lrsquoetude theorique du comportement drsquoun systeme hybride(eolien- photovoltaıque- diesel) de production drsquoelectricite sansinterruptionrdquo Afrique Science vol 5 no 1 2009

[35] HOMERmdashGetting Started Guide for HOMER Version 21National Renewable Energy Laboratory US Department ofEnergyOffice of EnergyEfficiency andRenewable Energy 2005

[36] C D Barley C B Winn L Flowers and H J Green ldquoOptimalcontrol of remote hybrid power systemsmdashpart I simplifiedmodelrdquo in Proceedings of National Avian-Wind Power PlanningMeeting Washington DC USA 1995

[37] D Saheb-Koussa ldquoEtude technique economique et environ-nementale des systemes decentralises connectes au reseauelectriquerdquo Bulletin des Energies Renouvelables vol 23 pp 15ndash17 2012

[38] V Courtecuisse Supervision drsquoune centrale multi sources a basedrsquoeoliennes et de stockage drsquoenergie connectee au reseau electrique[These de doctorat] Ecole Nationale des Arts et Metiers 2008

TribologyAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Industrial EngineeringJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Renewable Energy

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StructuresJournal of

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear InstallationsScience and Technology of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Solar EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Wind EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear EnergyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

TribologyAdvances in

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

FuelsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal ofPetroleum Engineering

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Industrial EngineeringJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Power ElectronicsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

CombustionJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Renewable Energy

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

StructuresJournal of

International Journal of

RotatingMachinery

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear InstallationsScience and Technology of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Solar EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Wind EnergyJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Nuclear EnergyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

High Energy PhysicsAdvances in

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014