GRENZE International Journal of Engineering & Technology

GIJET

Grenze ID: 01.GIJET.1.1.F1 © Grenze Scientific Society, 2015

GRENZE International Journal of Engineering & Technology

GIJET

Volume 1 No 1 January 2015

Grenze ID: 01.GIJET.1.1.F2 © Grenze Scientific Society, 2015 http://gijet.thegrenze.com/

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Editor-in-Chief: Dr. Janahanlal Stephen (Matha College of Technology, India) Category: Journal Publisher: GRENZE Scientific Society Frequency: Twice Yearly Research Group: GRENZE Engineering Group Subject: Engineering and Technology

Grenze ID: 01.GIJET.1.1.F4 © Grenze Scientific Society, 2015

Table of Contents Long Paper 1. Simulation of Shunt Active Power Filter for Compensating Current 1-7 Harmonics for Single Phase System Srinivas K, Srinivas G and Narasihma Rao K 2. Mechanism and PLC Design of Twin Spindle Drilling Machine – 8-14 A Innovative Approach Pravin R Patil and Tayade R M Full Paper 3. Need for Professionalism in Projects 15-20 Parin Gosar, Gayatri S and Narkhede B E 4. A Critical Review on the Shear Lag Effect of Steel Channel Sections Subject 21-29 to Tensile Loading Rishi D S, Surendran M, Marimuthu V, Saravanan M, Palani G S and Prabha P 5. Distributed Generation: Benefits, Issues and Challenges 30-36 Prasanna Kumar Biswal, Deepak Kumar Lal and Bidyadhar Rout Regular Paper 6. Experimental Analysis of Harmonics Reduction in Single Phase Battery 37-43 Charger Narendra Kumar M, Kuldip Singh and Anjaneyulu K S R 7. Discharge Estimation by Rational Method using Global Mapper GIS for 44-52 Sustainable Stormwater Management: A Case Study from Pune City Nivedita G Gogate and Pratap M Rawal 8. A Novel and Efficient Method for Denoising and Compression of MR Images 53-58 for Telemedicine Applications Ananda Resmi S and Ajith A 9. Voltage Improvement in Wind Farm using STATCOM with NSVFF Control 59-66 Rijo Rajan and Reji P 10. Survey on Hadoop MapReduce Scheduling Algorithms 67-71 Pranoti K Bone and Wade A M 11. SET for Cluster-based Cloud Computing: A Survey 72-74 Neelambike S and Mallikarjunaswamy B P Grenze ID: 01.GIJET.1.1.F5 © Grenze Scientific Society, 2015

Simulation of Shunt Active Power Filter for

Compensating Current Harmonics for Single Phase System

K.Srinivas1, G.Srinivas2 and K.Narasihma Rao3

1 Gayatri vidya Parishad College of engineering, Dept. of EEE, Visakhapatnam, India Email: k.srinivas215@gmail.com

2 Gayatri vidya parishad College of engineering, Dept. of EEE, Visakhapatnam, India Email: srinivas.g@gvpce.ac.in

3 Gayatri vidya Parishad College of engineering, Dept. of EEE, Visakhapatnam, India

Email: hodeee@gvpce.ac.in

Abstract— Among the various power quality problem, current harmonics are most commonly seen on the power system. This is mainly due to increased application of non-linear loads by the end users. In this paper, an analysis and simulation of a PV interactive shunt power active filter (SPAF) is done for single phase system. The shunt active power filter is used to eliminate harmonics generated by the nonlinear load. During the day-time with intensive sunlight, the PV interactive Shunt Active Filter system brings all its functions into operation. At night and during no sunlight periods, the power required by the loads is received from the distribution system while the inverter system only provides reactive power and filter harmonic currents. For the Shunt Active Filter reference current computation, the instantaneous real and reactive current (Ip-Iq) method is used. For gating signal generation we apply the hysteresis current control technique. The Simulation results (using MATLAB/SIMULINK) are presented and discussed. The proposed solution has achieved a low THD (Total Harmonic Distortion), demonstrating the effectiveness of the presented method. Index Terms— Shunt active power filter, pv cell, current harmonics, non linear load.

I. INTRODUCTION

Harmonic currents are present in modern electrical distribution system caused from non-linear loads such as adjustable speed drives, electronic blast lightning, power supply of computer, fax machine and more of telecom equipment used in modern offices. The wide spread and growing demand of these loads greatly increased and the flow of harmonic currents on facilitated distribution system and has created a number of problems. These problems included over heated transformers, motors, conductors and neutral wire; nuisance breaker trips; voltage distortion, which can causes sensitive electronic equipment to malfunction or fail. The need to generate pollution-free energy has starts considerable effort toward renewable energy (RE) system.RE sources such as wind, sunlight, and biomass offer the promise of clean and abundant energy. Among the RE sources, solar energy, is an attractive one. This useful energy is supplied in the form of DC power from photovoltaic (PV) arrays bathed in sunlight and converted into more convenient AC power Grenze ID: 01.GIJET.1.1.521 © Grenze Scientific Society, 2015

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through an inverter system. The photovoltaic arrays interactive shunt active power filter system can supply real power from the photovoltaic arrays to loads, and support reactive and harmonic power simultaneously to use its almost installation capacity. This paper presents an analysis and simulation of a PV interactive Shunt Active Power Filter topology that achieves simultaneously harmonic current damping and reactive power compensation [2]. Also, the inverter is always used to act as an active power filter to compensate the nonlinear load harmonics and reactive power[4]. In the day-time with intensive sunlight, the PV interactive shunt active power filter system brings all its functions into operation. At night and during no sunlight periods, the power required by the load is received from the distribution system while the inverter system only provides reactive power compensation and filter harmonic currents. The shunt active power filter (SAPF) is a device that is connected in parallel to the power system. The performance of a shunt active power filter depends on many factors. .Block Diagram of PV Interactive shunt active filter shown in Figure 1.Among them, the reference generation is the most important.

Figure 1. Block Diagram of PV Interactive shunt active filter

The method to generate the reference template is responsible for the reference of currents that must be followed by an inverter current to produce the desired compensation currents that will mitigate harmonic currents generated by non-linear loads[4]. Harmonic detection method will calculate the reference compensating currents. In this paper the instantaneous real and reactive current method (Ip-Iq) algorithm is used to generated the reference compensating current[3].From this reference compensating current the actual compensating current are generated with the help of hysteresis current controlled voltage source inverter.Hysteresis current controlled inverter will inject the compensating current into the power system. These compensating currents, will cancel the harmonics generated by nonlinear load.

II. PV MODEL

A solar cell is basically a p-n junction fabricated in a thin wafer of semiconductor. The electromagnetic radiation of solar energy can be directly converted to electricity through photovoltaic effect. Being exposed to the sunlight, photons with energy greater than the band-gap energy of the semiconductor creates some electron-hole pairs proportional to the incident irradiation. To find the model of the photovoltaic generator, we must start by identifying the electrical equivalent circuit to that source. Many mathematical models have been developed to represent their highly nonlinear characteristics resulting from that of semiconductor junctions that are the major constituents of PV modules. There are several models of photovoltaic generators which have a certain number of parameters involved in the calculation of voltage and current output. In this study, we will present the model of single diodes (Figure 2) taking into account the internal shunt and series resistances of the PV cell

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Figure 2. Model of a photovoltaic cell

The current source Iph represents the cell photocurrent. Rsh and Rs are the intrinsic shunt and series resistances of the cell, respectively. Usually the value of Rsh is very large and that of Rs is very small, hence they may be neglected to simplify the analysis. PV cells are grouped in larger units called PV modules which are further interconnected in a parallel-series configuration to form PV arrays. The photovoltaic panel can be modeled mathematically as given in equations (1) - (4) Module photo-current :

Iph = [ ISCr+Ki(T-298)]*

Module reverse saturation current :

Irs= ISCr / [exp(QvOC/ NSkAT) – 1] (2)

The module saturation current I0 varies with the cell temperature, which is given by

IO = Irs [푇/푇r]3 exp [ ∗ − ] (3)

The current output of PV module is

IPV= NP*IPh-NP*I0 [exp ∗( )

− 1](4)

Where Vpv and Ipv represent the output voltage and current of the PV, Iph is the photocurrent; IO are diode saturation current; q is coulomb constant (1.602 e-19C); Tr is the reference temperature is 298 K;K is Boltzman’s constant (1.381e-23 J/K); T is cell temperature (K); NS are P-N junction ideality factor; Rsh and Rs are the intrinsic shunt and series resistance of the cell respectively; Ns is the number of cells connected in series is 36 ;Np is the number of cells connected in parallel is 1.

III. DETECTION METHOD BASED ON INSTANTANEOUS REACTIVE POWER THEORY

The instantaneous reactive power theory is used to detect the harmonics here. The source voltage V(t)=Vsinωt, where V is the peak value of voltage[1]. The load distortion current consisting by fundamental and harmonic components is expressed by Fourier series as

)5()sin(1

nn

ns tnIii

The distortion current is delayed by π/2 to get the other current component iβ.

)6(])2/(sin[1

nn

n tnIi

iα and iβ are divided into three components, viz.,active, reactive and harmonic current as follows: = iαp(t)+iαq(t)+iαh(t) (7)

)sin(sincossincos2

1111 nn

n tnItItIi

4

= iβp(t)+iβq(t)+iβh(t) (8) Where the fundamental active and reactive current is ip(t)=Ip sin t, iq(t)=Iqcos t Where IP and Iq are their peak values Ip=I1cosω1, Iq=I1sinω1 According to instantaneous reactive power theory we can make the following calculations The harmonics are filtered by low pass filter (LPF) The fundamental component is subtracted from actual current to get harmonic current. The result of the original distortion current is(t) subtracting the fundamental current if(t) is the sum of harmonics ih(t). The calculation process shown in Figure 3.

ih(t) = is(t)-if(t) (10)

Figure 3. Calculation process the harmonic component

III. HYSTERESIS CURRENT CONTROLLER

Hysteresis current control method of generating the switching signal for the inverter switches in order to control the inverter output current [5]. It is adopted in shunt active filter due to best among other current control methods, easy implementation and quick current controllability [4]. It is basically a fed back current control method, where the actual current continuously tracks the reference current in the hysteresis band(Figure 4).The actual current within this hysteresis band. The reference and actual current is compared with respect to hysteresis band which decides switching pulse of voltage source inverter.

)(sincos

)(cossin

harmonicsItitii

sharmonicItitii

qq

pp

))2

(sin(sin)2

cos()2

sin(cos2

1111 nn

n tnItItIi

q

p

ii

tttt

ii

sincoscossin

)9(sincossincos 1111 tItIii f

5

Figure 4. Hysteresis Current Controllers

As the current crosses a set hysteresis band, the upper switch in the half-bridge is turned off and the lower switch is turned on. As the current exceeds the lower band limit, the upper switch is turned on and the lower switch is turned off(Figure 5). The switching frequency depends on how fast the current changes from upper limit to lower limit and vie versa. This, in turn depends on voltage vd and load inductance.

Figure 5.Hysteresis Band and Generation of Pulses

IV. SIMULATION RESULTS

The proposed model for a PV interactive shunt active power filter using harmonic detection method with hysteresis current controller has been successfully modelled and tested using MATLAB/SIMULINK toolbox it is shown in Figure 6.

Figure 6.MATLAB/SIMULINK model of PV interactive SAPF

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Figure7. Distorted current at source without compensation

Figure7 shows the distorted load currents of nonlinear load.

Figure 8. FFT analysis

Figure 8 shows FFT analysis for figure 7wave from. Harmonic currents are injected into power system by nonlinear load. Because of harmonics source current will be distorted. For distorted current THD is 33%.

Figure 9.Compensating currents injected by the active power filter

Figure 9 shows the compensating currents injected by the active power filter at the point of common coupling. Figure 10 shows the supply or source currents after compensation by active power filter. Figure 11 shows FFT analysis for figure 10 wave from. Compensating currents are injected into power system by SAPF. AS a result THD is reduced 33% to 2.4%.reactive power will decreased and power factor will improve .

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Figure 10.Current at source after compensation

Figure11.FFT analyses for above distorted current

V. CONCLUSION

In this paper, a PV interactive shunt active power filter is used for harmonic injection into the power supply. The harmonics generated due to nonlinear load are compensated by injected harmonics. A current control strategy is presented for SAPF in single phase circuit. The proposed method is capable of reducing the harmonics in the limits of IEEE 519-1992. After compensation of current harmonics, the source current is sinusoidal waveform, having THD 2.4%. The above system can be applied for single phase systems where there is a severity of current harmonics due to non-linear load.

REFERENCES

[1] Lei Xiao, GuoChunlin, XuYongha “Study on Harmonic and Reactive Current Detection in Single-Phase Circuit” IEEE International Conference on Measuring Technology and Mechatronics Automation 2009

[2] Jin weiHe,Yun Wei Li and Frede Blaabjerg “Active Harmonic Filtering Using Current-Controlled, Grid-Connected Dg Units With Closed-Loop Power Control” IEEE Transactions On Power Electronics, Vol. 29, No. 2, February 2014.

[3] Hirofumi akagi, yoshihirakanazawa, and akiraNabae“Instantaneous Reactive Power Compensators Comprising Switching Devices Without Energy Storage Components”, IEEE transactions on industry applications,vol.Ia-20,no.3, may/june 1984.

[4] Vasundhara Mahajan, Pramod Agarwal, Hari Om Gupta, Simulation of Shunt Active Power Filter using Instantaneous Power Theory, IEEE Fifth Power India Conference on Dec.2012

[5] Ned Mohan ,Undeland and Riobbins, “Power Electronics: Converters, Application and Design”, Wiley India edition, 3rd Edition,September 2002.

Mechanism and PLC Design of Twin Spindle Drilling

Machine - A Innovative Approach

Pravin R Patil 1 and R.M.Tayade 2

1Research Scholar (M.Tech), Veermata Jijabai Technological Institute, Mumbai, India prpatil@somaiya.edu

2Associate Professor Mech Engg Dept., Veermata Jijabai Technological Institute, Mumbai, India rmtayade@vjti.org

Abstract— The author of this paper has taken an initiative with keen interest to design an entire newly Twin Spindle Head Drill Machine currently not available in commercial market, to be exclusively used for Flange manufacturing along with other supplementary manufacturing options. The author in this paper had explained the conceptual Design of the machine and its mechanism, electrical system, PLC, interlocking and safety system. Index Terms— Clutch, Feed screw, Indexing, PLC, Spindle, Twin head.

I. INTRODUCTION

Kinematic system in any machine tool is comprised of chain(s) of several mechanisms to enable transform and transmit motion(s) from the power source(s) to the cutting tool and the work-piece for the desired machining action .The kinematic structure varies from machine tool to machine tool requiring different type and number of tool-work motions. The present commercially viable drilling machines has limitations with respect to number drill heads and precision problems in drilling holes at the given Pitch Circle Diameter with the low cost machines. A single head has also low Production volumes and automation problems for the conventional machines. A number of sincere attempts have been made by various Machine Tool Designers for designing low cost machine with simple automation without CNC system for high precision and mass production especially in Drilling machines but results were not too futile. A simple single head drilling utility machine has been designed by HMT Bangalore accompanied with various features, but the price of machine doesn’t make it affordable for the Vendors, who serve as feeding unit to large ventures. The author of this paper has taken an initiative to Design the affordable, precision, and mass production Drilling machine on simple PLC and basic design concepts which will be viable especially to small and medium workshops, which are specially engaged in Flange manufacturing. The author through this paper has put forwarded a unique concept of Twin Spindle Drill Head machine, to which feed is given through a single motor and drill is rotated by separate motors. The entire feeding Design, work holding system, Gear Box system is unique one. The paper will immensely benefit the designer and Machine Tool Manufacturer as such Practical and simple Design is not being currently available. Grenze ID: 01.GIJET.1.1.525 © Grenze Scientific Society, 2015

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II. LITERATURE SURVEY

“ Ref. [1]” Parallel Machine Tool is a new type of machine tool which was firstly shown at the 1994 International Manufacturing Technology Show in Chicago by two American machine tool companies, Giddings & Lewis and Ingersoll. These machine tools, named Hexpod, were based on the paradigm of the spatial six degrees of freedom (DOF) parallel manipulator. The parallel machine tool technology promises to offer manufacturers a number of advantages relative to conventional machine tools, such as a higher stiffness-to-mass ratio, higher speeds, higher accuracy, reduced installation requirements, mechanical simplicity, and high flexibility. “ Ref. [2]” The 6-DOFs Stewart platform is one PMT configuration that has been used in a number of new Machine Tool designs at the beginning of the birth of PMT. For machining applications, disadvantages of the Stewart platform include a complex workspace, limited orientation range of motion and a requirement of six actuators for a 5-DOFs task (milling, drilling and similar operations). Moreover, there are some disadvantages for the parallel kinematics itself, such as the forward kinematics cannot be described in closed-form, and the dimensional design is difficult, and so on. For these reasons, many researchers begin to pay their attention to less than 6 DOFs PMTs especially hybrid PMTs “Ref. [3]” The required path accuracy of machine tools designed for micromachining is sufficiently provided by state-of-the-art machine tools, but they typically have limited feed drive dynamics. Various micro machining processes, e.g. micro-drilling, demand high jerk movements of the feed axes. The justification of additional expenses for direct drives is beyond question when high gains of the position control loops (K factors) as well as high jerk values are needed and at the same time additional masses and process forces are low. Hence, direct drives are predestined for highly dynamical micro drilling machines. “Ref. [4]” When attaching direct drives, the mechanical components of the drive system are not limiting the position controller’s bandwidth, as in the case of using electro-mechanical drives . Here, the machine tool frame limits the practicable controller bandwidth and the maximum jerk value. “Ref. [5]” The present design concept for machine tool structures aims at maximum stiffness and high eigen frequencies. This leads not only to huge and heavy frames with adverse weight/workspace ratio but the frequency content of the excitation has high energy even at the high eigen frequencies.

III. MOTIVATION

The drilling machine commercially available in the market has a limitations of drilling hole in pitch circle diameter. The costly jigs and fixtures are to be used and as the PCD changes new fixtures are required, moreover the production time is too high. The CNC commercial machine can overcome this problem but is not affordable for small and medium scale industry. In keeping the following limitations point a motivational challenge was to design a Twin Head Pitch Circle Drilling Machine, which is capable of doing same effective operation as CNC machine but with lest cost, ease in operations and low maintenance.

IV. PROBLEM DOMAIN

The design of the machine involves number of complexity in Mechanical design, Electrical wiring, PLC, Tooling design etc. The mechanical design of the machine should be a compact one with standard selection of materials and should be very safe, maintenance free. . The machine cycle is to be automatically controlled through various PLC commands and the system is to be designed by means of various proximity switches and relay control for turning ON and OFF the various drive motor and clutches as per the requirement and has to operate in synchronizing cycle.

V. PROBLEM DEFINITION

The task is to design a machine with twin spindle head which can operate simultaneously for drilling holes at a variable Pitch circle diameter with a high accuracy and precision. The machine is to operate at higher speed and feed in auto-cycle mode so that entire cycle operates in automatic mode. The machine is to be designed in absence of costly controller and drive card and only on basis of simple sensors like proximity switches and relay with high cost affordability.

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VI. STATEMENT

The task is to Design a machine capable of drilling two holes simultaneously in a flange at 180 degree apart at variable Pitch Circle diameter distance and the entire drilling cycle has to operate in automatic mode.

VII. INNOVATIVE CONTENT

Design Principle: Pitch Circle Drilling Machine (PCDM) is a Special Purpose Machine (SPM) designed for drilling two holes simultaneously in a circular component at high speed. The two holes are drilled simultaneously by means of two separate Spindle head (Twin Head) which hold the drill tool and are feed against the work piece at an angle of 180 degree. An outline schematic diagram Fig 1 simply demonstrates the arrangement of various machine elements of Pitch Circle Drilling Machine. The machine has two independent spindles which enclose in a sub-assembly units mounted in a cast Iron bracket and are placed on two separate slides viz. Slide left and Slide right. These two slides can move horizontally on Slide main, the distance between the slides can be adjusted through Ball nut and Ball screw assembly and is equal to the Pitch circle Diameter of the job. The Main slide unit holding the both slide is mounted on the column of the machine by means conventional Wedge and Dowell pin arrangement. The main slide unit can be independently moves in a vertical direction through Ball screw and Ball nut assembly acting as a feed screw. The rotary drive to the spindle to perform the drilling operations is provided by means of separate electric motors to each spindle which can be operated individually through electric panel. The main slide is controlled through separate clutch mounted between the Gear box and Main slide. The work holding arrangement is versatile in nature and can be held in number of ways. A rotary Indexing Table is provided which can be indexed according to the numbers of hole required to be drilled in the component and through clamping pin arrangement the table can be locked at the during the operations, the locking mechanism is a through Gear and pin arrangement. The job can be hold in a chuck, which will be mounted directly on the rotary table.

Fig 1: Layout of Machine in 3D view

IX. PROBLEM FORMULATION OR REPRESENTATION OR DESIGN

Working cycle : The machine is designed on automation cycle controlled by PLC unit where only input required for operation such as job thickness, pitch circle diameter, speed, feed are to be provided and machine will automatic perform all the operations in a sequential manner without any manual interference. The system to be affordable is controlled through logical gates only without any costly computerized drive control units. Fig 2 shows a schematic arrangement of the machine.The distance between the left and Right slide is adjusted to the diameter of Pitch circle diameter. The accurate setting of the distance is done by means graduation disc provided at the front face of the spindle. The main feed slide is driven by means of geared

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motor which rotates in the clockwise direction and through gearing and clutch arrangement is provided to the feed screw. The feed screw rotates in anticlockwise direction which in turns drives the main slide in vertical downward direction. The slide holding the spindle drill is provided the rotary motion through separate motor. The drilling operation is started as soon as it touches the work piece and is continued till the preset depth of drilling has been reached. As the final depth is achieved the sensor through logical unit turns on the reverse clutch and the slide moves in upward direction. As soon as the initial set point is achieved the forward clutch turns on and the slide moves again in downward direction. As soon as slide moves in upward direction the rotary table will be indexed at required degree, so that new position can be worked out. The chips are flushed out with coolant and are collected in separate tray provided at the bottom. The rotary table basically indexed through motor and the locking of table during operation is done through locking pin which is of same shape as gear shape and locks in the tooth width. The unlocking, rotation and locking of the rotary table is through PLC unit.

Fig 2 Working Cycle Diagram

X. SOLUTION METHODOLOGIES OR PROBLEM SOLVING

Specifications of Machine: Hole Diameter : 14 to 30mm Hole Depth : 60mm Max. P.C.D : 150mm Min. (Work Dia.200mm) 450mm Max. (Work Dia.500mm) No. of Holes : 1 to 24 Drill : Sandvik Coro drill with replaceable inserts Spindle RPM : 400 to 1600 Spindle Power : 4kW x 2 Spindles Cutting Speed : 40-70 m/min. Cutting Feed : 0.08-0.12 mm/rev.

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Feed Power : 1.8kW Spindle Motor : Model No. BN112M4 (4-Pole), 4kW. Feed Motor : Geared Motor 1.8kW, Output RPM-58 Coolant Motor : 0.37kW Control : Programmable Logic Controller Rotary table : 24 positions Electro-Pneumatic Controlled Accuracy : +/- 0.05mm

Fig 3: Elevation and Plan of Twin Spindle Machine

XI. ELECTRICAL AND PLC UNIT DESIGN

The electrical diagram illustrates the simplified design of the electrical drives. The machines cycle works on basic PLC unit instead of complicated control system due to limitations of operations. The electrical wiring diagram as shown in the fig-4 shows the different motors and their connections. The machine cycle is automatically controlled through various PLC commands and the system is designed by means of various proximity switches and relay control for turning ON and OFF the various drive motor and clutches as per the requirement. The Table 1 indicates the basic Input and Output PLC commands used for the working cycle of CNC machine.

XII. CONCLUSIONS

The research paper provides a new and novel concepts for the new product development as currently the idea is out of public domain and will serve the need of Machine Tool Industry. The machine being very simple and compact one and due to availability of twin head the production output will be high as well as the cost involved will also be less. The machine tooling is very simplified and works on standard Delta drills with replaceable inserts and job setting is also simple in nature. The PLC and electrical design being very simple and no complicated programming is required as in CNC system and cycle time is at par with CNC and can be operated by semi-skilled labour. The mechanical and electrical system are well user friendly and can be easily maintained.

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TABLE I. PLC INPUT AND OUTPUT DETAILS

PLC INPUT DETAILS PLC OUTPUT DETAILS 1000 Emergency 2000 Emergency Stop 1001 Manual cycle 2001 Manual cycle Lamp 1002 Auto cycle 2002 Auto cycle Lamp 1003 Auto start 2003 Spindle-I ON 1004 Auto stop 2004 Spindle-I OFF 1005 Coolant start 2005 Spindle-II ON 1006 Coolant stop 2006 Spindle-II OFF 1007 Machine lock key 2007 Home Position Lamp 1008 Spindle-I ON 2008 Feed motor ON 1009 Spindle-I OFF 2009 Feed motor OFF 1010 Spindle-II ON 2010 Feed clutch ON 1011 Spindle-II OFF 2011 Feed clutch OFF 1012 Feed motor ON 2012 Unlock solenoid 1013 Feed motor OFF 2013 Clamp-I solenoid 1014 Geared motor ON 2014 Clamp-II solenoid 1015 Geared motor OFF 2015 Clamp-III solenoid 1100 Index ON 2100 Clamp-IV solenoid 1101 Index position proxy 2101 Geared motor ON 1102 Unlock cylinder Reed switch 2102 Geared motor OFF 1103 Unlock cylinder - I Reed switch 2103 Coolant motor ON 1104 Unlock cylinder - II Reed switch 2104 Coolant motor OFF 1105 Unlock cylinder - III Reed switch 2105 Tower lamp green 1106 Unlock cylinder - IV Reed switch 2106 Tower lamp orange 1107 Feed in mm 2107 Tower lamp red 1108 Feed direction upwards 2108 Low air pressure lamp 1109 Feed direction downwards 2109 Limit position-I 1110 Feed clutch ON 2110 Limit position-II 1111 Feed clutch OFF 2111 Limit position-III 1112 Feed counter pulse 2112 Limit position-IV 1113 Pressure Switch 2113 Drill feed 1114 Limit Switch Position -I 2114 Rapid feed 1115 Limit Switch Position -II 1200 Limit Switch Position -III 1201 Limit Switch Position -IV 1202 Unlock Cylinder reverse selector switch 1203 Clamp cylinder –I reverse selector switch 1204 Clamp cylinder –II reverse sel. switch 1205 Clamp cylinder –III reverse sel. switch 1206 Clamp cylinder –IV reverse sel. switch 1207 Index counter pulse 1208 Cycle count 1209 Cycle count Reset 1210 Drill feed sel. switch 1211 Rapid feed sel. switch

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Fig 4: Wiring diagram of different drives used in machines

The paper will immensely benefit the small and medium scale industry as it will increase the productivity. The idea presented in this research paper can be further utilized for further development of this Twin spindle Drilling machine into Twin Head Milling machine.

REFERENCES

[1] Jinsong Wang, Xiaoqiang Tang, “Analysis and dimensional design of a novel hybrid machine tool”, International Journal of Machine Tools and Manufacture 43 (2003) pp. 647–655.

[2] Wei-Tai Lei, Wen-Chung Wang , Tien-Ching Fang, “ Ballbar dynamic tests for rotary axes of five-axis CNC machine Tools”, International Journal of Machine Tools & Manufacture 82-83 (2014) pp. 29–41.

[3] Linxia Liao, Jay Lee,Expert, “ Systems with Applications”, Expert Systems with Applications 37 (2010) pp 240–252.

[4] E.L.J. Bohez, “Five-axis milling machine tool kinematic chain design and analysis”, International Journal of Machine Tools and Manufacture 42 (2002) pp. 505–520.

[5] Bin Li, Hui Cai, Xinyong Mao, Junbin Huang , Bo Luo, “ Estimation of CNC machine–tool dynamic parameters based on random cutting excitation through operational modal analysis”, International Journal of Machine Tools and Manufacture 71 (2013) pp. 26-40

Need for Professionalism in Projects

Parin Gosar1, Gayatri S2 and Dr. B. E. Narkhede3

1 Pursuing M.Tech in Project Management, VJTI, Mumbai, India Email: parin_gosar@yahoo.com

2 Pursuing M.Tech in Project Management, VJTI, Mumbai, India Email: gayatri1989@gmail.com

3 Head of Project Management, VJTI, Mumbai, India Email: benarkhede@vjti.org.in

Abstract— Any human endeavor; be it setting up an industry, doing research, establishing any trade or business or going for entrepreneurship of any nature faces challenges as well as offers opportunities for growth. Success of that endeavor lies in effective management of challenges and utilization of opportunities. Project management focuses on these aspects. This paper emphasizes the challenges faced, in general, by any project, need of project management and project management professionals along with the implicit and explicit opportunities that are available in knowing project management and owning professionals for handling projects. Index Terms— ROI, project charter, critical path, float, scope creep and schedule slippage

I. INTRODUCTION

Management is the key to succeed in any field. Management ranges from dealing with people to crisis handling to correct decision making. A good management is always rewarding and leads to the positive growth of the community involved directly or indirectly. One way to define management is to utilize resources efficiently and get the work done by the people to achieve the goals of an organisation keeping in mind the success of the organisation. When it comes to the success of an organisation, the administrative abilities play a bigger role as compared to the technical knowledge. Management consists of the bigwigs of a company. Management is the base to start a business and continue its growth in terms of name, fame and wealth and maintain the position after achieving greater heights. Management plays an important role to maintain the positive growth graph of an organisation. Any set of interlinked activities which are unique and temporary is considered to be a project. Managing the resources and carrying out these temporary activities effectively and efficiently and delivering the deliverables on time are called Project Management. Project Management includes the management of cost, scope, time, quality, human resources, risk, stakeholders and safety. The following literature survey briefs about the lapses in projects that lead to project delay or failure.

II. LITERATURE SURVEY

Reference [1] Projects fail or get delayed mainly when the uncertainties involved with the parameters of the project are ignored or misunderstood. While working on any project, faulty initial deadlines along with Grenze ID: 01.GIJET.1.1.14 © Grenze Scientific Society, 2015

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inconsistency or irregularities may lead to schedule slippage. This is mainly because of improper determination of the deadlines tied to higher level objectives which has critical links into schedules of other projects in the organization’s portfolio. Reference [2 & 3] To start and execute the project effectively, its need, requirements, benefits and progress are to be communicated with the stakeholders. Meeting and considering the demand of all the stakeholders is not possible. Hence, it becomes difficult to execute the project effectively. The oral communication in projects is not effective every time as it may not stand as a testimony. Also, the role played by the media has high impact on projects. Miscommunication through media comes into picture when the facts are not conversed to stakeholders. Reference [4] When the need and requirements of a project become uncertain, the setting of project goal gets disturbed and thus leading to blurred vision of the said project. This gives rise to scope creep followed by increase in cost, resources and schedule slippage. Since, there is no anti-scope-creep spray in project utility belts, the project delays or fails. Reference [5] Projects usually compete for resources (people, money, time) against other projects. This leads to a tough competition among all the projects. This mainly occurs due to the absence of the upper management in resource allocation. Reference [6] The risk or reliability in a project is generally determined by trusting someone else’s assessment. This may lead to risks never thought of. Unwanted uncertainties rising during the project phase are the risks. To manage risk is a difficult task as all possible risks can’t be predicted. Thus, the solution for this is to analyse the factors which may lead or act as a risk in the project and accordingly the plans should be made. Reference [7] Project requires skilled people to carry out the project activities. To find and keep such skilled people tied to the project is another challenge. This makes developing countries dependent on others and thus contributing to price rise of the project and also elongates the chain of stakeholders. Reference [8] Various factors were identified which affect the Web-Based construction project management systems. Many probationers still don’t know or are uncertain about the measures that should be used to evaluate system performance. Reference [9 &10] In any large scale project, when there is a need for decision making, there always occurs difference of opinion between two individuals or an individual and organization or the project team and its stakeholders. Due to such non-cohesiveness the projects are affected economically. Reference [11] The focus on procuring process needs more attention as construction projects consume non-renewable sources of energy. The traditional construction procurement system is not capable of dealing with sustainability parameters. Most of the projects’ characteristics are not identified which affects the use of construction procurement system. Reference [12] The projects under World Bank fail to manage their entire life cycle. The projects funded by World Bank have lack of ownership of the local stakeholders and in identifying institutional capacity of the borrower to implement and then operate the project are hurdles in managing the life cycle of a project. Reference [13] The problems associated with simultaneous multiple project handling are capacity, complexity, conflict, commitment and context. These factors vary according to size, urgency and skills required for a project. Many problems can be alleviated by identifying the common elements like resources, accounting and reporting systems to reduce the degree of complexity. Reference [14] Projects should have hybrid model i.e. a combination of orthodox and political models. It helps in an acknowledgement of political nature of the public decision making and can use the tools of orthodox model in shaping eventual decisions. Also the projects are to be planned with alternative approaches to avoid last minute delay. Reference [15 & 16] Understanding the need of the project is most important. The selection of a project must be done after detailed analysis of the opportunities and hurdles associated with it. The planning must be done considering the future aspects of it. Reference [17] The change in scope affects the schedule of a project. Most of the time it becomes difficult to include such changes and manage the project under predefined parameters. The aim behind writing this paper is to study the causes of recurring issues in projects and finding the way out to achieve success in any project so as to induce positive impact on society, technology and economy.

III. PROBLEM IDENTIFICATION

Above mentioned reasons of the project delay are mainly due to lack of synergy of technical and managerial aspects with the project constraints like cost, time and scope. These constraints affect the social, economic and technological factors associated with the projects. The projects suffer due to lack of experience in maintaining cost, scope and time and in following the set methodologies. The project professionals are either from technical or management background. Thus, they may lack in the knowledge areas defined by the Project Management Book of Knowledge (PMBOK).

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IV. METHODOLOGY

In order to understand the requirements of the people involved in a project, it is first essential to know the qualities needed while being in a project. These are

Planning - To determine the goal and the way to achieve it. Organising- It’s all about deciding where and when decisions will be made and who will do what for

whom. Leading – It is about involving the people for discussion and motivating and guiding them to

achieve the goals. Commanding- It follows unity of command. The process of assigning, monitoring and convincing

people falls under commanding. Precise commanding leads to the accurate management of the team to achieve the set goals.

Controlling- It is necessary to monitor the project at every stage. Minute carelessness in project may place the project on the path of failure. Thus, we can say that the progress of the project should be on the fingertips of the project manager so that he/she can take corrective actions if and when required to keep the project on the track and to achieve the set goals.

These qualities are to be comprehended in the best possible way in order to run the project successfully and the following study on Navi Mumbai metro project stands as a testimony to the statement. During the study, the communication flow in multiple-project environment was learnt which is diagrammatically represented in figure1.

Figure 1. Communication flow between the stakeholders of the project

It is clear from the fig. 1 that the inability to execute project makes its owner dependent on General Consultant (GC). Thus, the GC has to manage the project entirely. Major approvals and the requirements are to be obtained from the project owner and government organisations. If the project is funded by some institutions under loan basis then the amounts are released on the basis of progress made. In order to have continuous flow of money the project is to be kept on track. In multiple-project handling, the degree of complexity increases and the role becomes more vital. GC is the body responsible for the planning, designing, execution, controlling, closing and commissioning of the project. Thus, it becomes necessary for GC to have technical knowledge and managerial qualities. The role and responsibilities of the stakeholders are described in the table below:

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TABLE I. ROLE AND RESPONSIBILITIES OF STAKEHOLDERS

Sr. No. Stakeholders Role and responsibilities

1 Project owner Arranging funds

Specifying requirements Setting clear goals

2 Financial institutions Providing and releasing funds 3 Advisors Making project efficient through experience

4 Contractors and subcontractor Executing project as per plans Selecting proficient vendors

5 Vendors Providing continuous flow of materials

6 Operational team Accepting handover

Generation of revenue Repair and maintenance

7 General Consultant

Disseminating Planning

Designing Obtaining clearances

Monitoring critical path Performing quality checks

Mitigating risks Resource allocation

Executing tendering and bidding process Assisting operational team Multiple project handling

Based on the table-1, it was understood that the general consultant has to possess right chiaroscuro of both the technical and the management skills along with the intricate knowledge of the project parameters. This is because the general consultant has to fulfil the requirements of project owner while managing different stakeholders and at the same time ensuring methods to overcome uncertainties in the project. He has to get timely approvals and clearances, so that the project can be kept on right track, avoiding time and cost over-run. Since, he assists the operational team, it becomes obligatory for him to hold the operational knowledge. As the flow of information takes place via general consultant, his role becomes all the more vital. Any communication gap can incur huge loss in the project, thus making it necessary for the general consultant to own good communication skills and high persuasive talent. Due to execution of multiple projects at a time he should have resource allocation skills and must be in a position to identify the common resources so that the allocation can be made more efficient. He should be well-versed not only with financial knowledge but also negotiation skills in order to carry out tendering and bidding processes. It is clear that the role of GC is like a project manager who is responsible and answerable for anything related to the project. By applying the defined methodologies of project management, such multiple-project environment can be handled more efficiently. The benefits of having professionals in project are listed below.

Projects are selected on Return on Investment (ROI) basis, so that the invested amount can be recovered and actual revenue can be generated as fast as possible. To achieve this, project management helps in planning the resources to ensure that time and budget performances are maintained.

People working on a project may drift off the topic easily and spend too much time on unnecessary tasks. The project management tools help in solving the above said problem by focusing on the project charter, barriers resolver and prioritising the activities, so that the project team is always on the required ground.

In any project, the requirements collection is the initial phase as it strengthens and justifies the goals to be achieved. It also helps to communicate the benefits of projects to the stakeholders. Efficient project management helps in analysing the project and deciding the optimum requirements needed for its successful completion.

A project is a set of activities interconnected with each other. These interconnected activities form a path. The path with maximum duration and zero total float is the critical path. Any disturbance in the critical path may lead to an unsuccessful project. Executing the critical activity and completing it

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on time can be done by monitoring and controlling the resources for which softwares and tools are available. This can be effectively done by knowing the intricacies of project management.

In the new era of technology, softwares are pumping station for almost all activities. The project management softwares are used to calculate required resources, time for completion of the activities and the cost involved for carrying out the activities. For utilizing these softwares up to its maximum capacity, the people are to be trained so that they can work in actual fact. Apart from the training in using the software, minutiae of project management can help the project team to manage the vendors with their effective communication so that the required materials are delivered at the right place and on time. This avoids delay in project due to scarcity or non-availability of resources.

For projects, effective verbal as well as written communication is essential. Project benefits are to be explained to the stakeholders to get the idea about their expectancy. During the execution phase of the project, its progress must be informed consisting outcomes, changes and hurdles to the superiors and stakeholders. Thus, clear and defined communication plan is required. Post project too, communication plays an important role. The handover of project to the client means to give details of the project which will be required during the operational period. Thus, communication is necessary from start till the project enters operational phase. Clear idea of project management will result in effectual communication.

The scope of the project depends on the state of mind of stakeholders. The change in the scope, delays the project completion. The scope change may be because of the change in demand, requirements, cash inflow, union matters, government issues, etc. The project team, with experience and thorough knowledge of project management, gets well trained to face such situations and becomes superior decision makers.

Project closure is the last phase of the project. Before closing, all the legal documents are cross checked and verified. Some of these documents will be required for future purpose like government issues, renewal of licenses, loan applications and maintenance purpose. Handover is done after achieving the goals and complete quality check. This quality check is performed in the best possible manner using project management tools and techniques. Project management techniques also help in keeping the service receiver and service provider in loop even after the handover of the project.

V. RESULT

From the above content, it is derived that having project professionals help in delivering the project on time and in budget, keeping it on right track by efficient monitoring and coherent communication, understanding the project requirements along with appropriate resource estimation and being capable of handling unexpected issues. All these will help in potent handover and effective closure with post-project or operational assistance.

VI. CONCLUSION

Projects must be strategically aligned to support the organization’s corporate strategy if they are to survive the ever-changing priorities of the organization. Solid project planning reduces the risks associated with any project. Need for professional project management techniques emerged with growing scope and complexity of projects, with tightening restrictions and requirements for use of material, financial and labour resources and for quality of work and performance. Today every organisation involved in projects want people specialised in all fields for carrying out the project activities smoothly. The introduction of project professionals to handle the project intricately will prove to be a positive solution for increasing the success rate of projects. The professionals should be aware of optimum usage of tools and techniques available to complete a project. These professionals do not just learn through experience or nearly being in a project environment but capture the essence of managing projects through hands on training on simulated projects which make them understand the optimal synergism of knowledge area, thus making them diligent project handlers. Because of these, the presence of professionals in handling projects will reduce the chance of project failure as they can mitigate the chances of cost overrun or overtime they can also handle multiple projects without resource conflict and with effective communication. Their ability to handle and use technology to its fullest will also save many projects. There proficiency in understanding the resources of a project and acquiring only the needed resources will avoid wastes and thus,

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this increases profit. Having professionals will make R & D arena richer, thus contributing to the increase in gross domestic product and helping in the development of a country.

VII. FUTURE SCOPE

Reference [18] After identifying the importance of project professionals, the creation of them is the next step. This can be done by formally educating the people on project management. But, the available infrastructures are not capable of fulfilling the demand of ever growing project professionals. Thus, the needed support is to be made available so that the demand of erudite project professional can be met. Industrial involvement will help in gaining hands-on experience and help the professionals grow more organization-friendly.

REFERENCES

[1] S Meeampol and S. O. Ogunlana, “Factors affecting cost and time performance on highway construction projects: evidence from Thailand,” Journal of Financial Management of Property and Construction, vol. 11, issue 1, pp. 3–20, 2006.

[2] Bon-Gang Hwang, Xianbo Zhao and Si Yi Ng, “Identifying the critical factors affecting schedule performance of public housing project,” Habitat International, vol. 38, pp. 214–221, 2013.

[3] Adnan Enshassi, Sherif Mohamed and Saleh Abushaban, “Factors affecting the performance of construction projects in the Gaza strip,” Journal of Civil Engineering and Management, vol. 15, issue 3, pp. 269-280, 2009.

[4] S. O. Ogunalana, Promkuntong K., and Jearkjirm V., “Construction delays in a fast-growing economy: comparing Thailand with other economies,” International Journal of Project Management, vol. 14, issue 1, pp. 37–45, 1996.

[5] Enshassi, A., Al-Najjar, J. and Kumaraswamy M. M., “Delays and cost overruns in the construction projects in the Gaza Strip,” Journal of financial management of property and construction, vol. 14, issue 2, pp. 126–151, 2009.

[6] Hemanta Doloi, Anil Sawhney and K. C. Iyer, “Structural equation model for investigating factors affecting delay in Indian construction projects,” Construction Management and Economics, vol. 30, pp. 869–884, 2013

[7] Philip Bromiley and John M. Bryson, “Critical factors affecting the planning and implementation of major projects,” Strategic Management Journal, vol. 14, pp. 319–317, 1993.

[8] Pollaphat Nitithamyong and Mirosław J. Skibniewski, “Success or failure factors and performance measures of web-based construction project management systems: professionals viewpoint,” Journal of Construction Engineering and Management, vol. 132, issue 1, pp. 80–87, 2006.

[9] Doloi Hemanta, “Cost overruns and failure in project management: Understanding the roles of key stakeholders in construction projects,” Journal of Construction Engineering and Management, pp. 267–297, 2013.

[10] Loosemore Martin, “Managing public perceptions of risk on construction and engineering projects: how to involve stakeholders in business decisions,” International Journal of Construction Management, pp. 65–74, 2009.

[11] P. D. Rwelamila, A. A. Talukhaba and A. B. Ngowi, “Project procurement system in the attainment of sustainable construction,” Sustainable Development, vol. 8, pp. 39–50, 2000.

[12] Robert Youker, “Managing the project cycle for time, cost and quality: lessons from World Bank experience,” International Journal of Project Management, vol. 7, issue 1 pp. 52–57, 1989.

[13] John H Payne, “Management of multiple simultaneous projects: a state-of-the-art review,” International Journal of Project Management, vol. 13, issue 3, pp. 163–168, 1995.

[14] David Hulme, “Projects, politics and professionals: Alternative approaches for project identification and project planning,” Agricultural systems, vol. 47, issue 2, pp. 211–233, 1995.

[15] Haim Katz and Mordechai I. Henig, “R&D Project Selection: A decision process approach,” Journal of Multi-Criteria Decision and Analysis, vol. 5, pp. 169–177, 1996.

[16] Nicholas S. Vonortas and Henry R. Hertzfeld, “Research and development project selection in the public sector,” Journal of Policy Analysis and Management, vol. 17, issue 4, pp. 639–657, 1998.

[17] Muzaffar A.Shaikh, “Project schedule re-computation after risk inclusion,” Systems Engineering, vol. 3, pp. 242–249, 1998.

[18] Udechukwu Ojiako, Melanie Ashleigh, Max Chipulu and Stuart Maguire, “Learning and teaching challenges in project management,” International Journal of Project Management, vol. 29, pp. 268–278, 2011.

A Critical Review on the Shear Lag Effect of Steel

Channel Sections Subject to Tensile Loading

D. S. Rishi1, M. Surendran2, V. Marimuthu3, M. Saravanan4, G. S. Palani5 and P. Prabha6 1 M Tech, Indian institute of technology, Guwahati, India

Email: sririshid000@gmail.com 2 Scientist, CSIR-Structural Engineering Research Centre, Chennai, India

Email: { surendran, marivel, saravanan, pal, prabha }@serc.rec.in

Abstract— The net section capacity of channel sections under tension are affected by shear lag effect. In India the strength of channel sections are evaluated by using the equations available for angle sections. Hence, an attempt has been made to check the validity of these equations for channel sections. For this purpose, guidelines available in various codes of practices and literature are revisited. This paper examines the factors affecting the net section capacity of tension members and the various empirical equations from the literature. Different codal equations related to the net section capacity of channel sections are studied and compared with the corresponding experimental results reported in literature. Effect of the gauge, length of connection and the number of row of bolts are studied. Index Terms— Tension capacity, Shear lag effect, Channel sections, Angle sections.

I. INTRODUCTION

The net section failure capacities of channel sections under tension are influenced by shear lag effect, which arises due to uneven stress distribution due to the presence of bolt holes and eccentricity of the loading. This creates a lag in stress transfer across the cross-section, which leads to reduction in the cross section strength. The consequence of this shear lag can be observed when the member fails through net tensile area at a load lesser than the tensile capacity of the member. For plates under tension having bolts, the tensile stress is usually not uniformly distributed, having stress concentration adjacent to the hole and decreases in transverse direction. Due to this only the portion around the hole reaches ultimate and the stress in the other regions are less. The criterion for the design of angles and channel tension members is governed by eccentricity unlike plate sections which is loaded axially and the reduction in the effective area is due to stress concentration around the bolt hole. Whereas in angle and channel sections, shear lag effect is more pronounced than plate elements due to various factors like eccentricity, ratio of unconnected leg to that of connected leg length, length of the connection, thickness of the section etc. Stress distribution on angle section under tension is shown in Fig.1. It shows the stress lag in the unconnected leg. Similarly, the stress distribution of channel sections is also affected by shear lag. However, there are no design guidelines for channel tension members. This paper presents the critical review of literature of channel sections under tension and compares the strength predicated by the codal provisions. Grenze ID: 01.GIJET.1.1.18 © Grenze Scientific Society, 2015

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II. REVIEW OF EMPIRICAL EQUATIONS

A. McKibben et al. (1906) [15] tested 18 specimens for tensile tests and studied the net section efficiencies of each member and on the bases of the findings and results, the following equation was formulated.

Fig.1 Stress Distribution in unconnected leg due to Shear Lag

Capacity = 푓 × 퐴 ×푈 (1)

U = 1.0− 0.18 (2)

where, LC = width of the connected leg, L0 = width of the unconnected leg, An is the net cross sectional area, fu is the ultimate tensile strength of steel.

B. Nelson et al. (1953) [17] observed that the capacity is a function of no of bolt hole per line and the ratio of outstanding leg area to that of connected leg area. It was observed that there was no change in the capacity of the connection on increasing the connection length or by changing the connection type. Based on the results obtained from 18 single angles connected at their ends, the following equation was proposed

Capacity = 푓 × 퐴 × 푈 (3)

푈 = (4)

where, n is the number of bolts per line and 푟 = , where Ao is the gross cross sectional area of outstanding leg and Acn is the net cross sectional area of connected leg.

C. Munse et al. (1963) [16] proposed an empirical equation based on tests of 218 tension specimens out of which 56 are single angles and 33 are double angles. The empirical equation includes a factor for the ductility of the material, the effect of punching the holes, the effect of holes spacing on the connection and a factor to take account for both eccentricity in the connected parts and the connection length.

capacity=푓 × 퐴 (5)

퐴 = 퐾 × 퐾 ×퐾 × 퐾 × 퐴 (6)

where, K1 is the ductility factor given by (0.82+0.0032Q), Q is the percentage reduction in the area of a standard tensile coupon test.

K2 is the fabrication factor = 0.85 for punching effect

= 1.0 for drilling effect

K3 = 1.6 − 0.7( )

K4 is the shear lag factor given by 1.0 – (X/L)

where X refers to the distance from face of the plate to the center of gravity of the member. L is the length of the connection (distance between the first and the last bolt).

D. Marsh et al. (1969) [14] conducted a series of tests on single angle members in tension and compression to study the effects of plastic behavior during ultimate loading of the sections. Marsh stated that as the extreme fibers of the section yield, the line of action of the load would move, as well as the eccentricity. Based on these observations, it was proposed that the net effective area (Ane) could be calculated as follows

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퐴 = ..

(7)

where Lc = width of the connected leg, L0 = width of the unconnected leg, t = thickness of the section, L' = distance from the point of loading to the innermost bolt and d = diameter of the bolt hole.

E. Gaylord (1992) [8] gave an equation for the net section capacity accounting for the shear lag effects. He assumed it depends on four factors: steel ductility, fabrication methods, connection efficiency, and shear lag effects. They gave an expression as follows Aeff = K1.K2.K3.K4.An where, K1 = ductility factor = 0.82 + 0.0032 R ≤ 1.0 K2 = fabrication factor = 0.85 for punching effects

= 1.0 for drilling effects. K3 = efficiency coefficient K4 = shear lag factor. R = percent reduction in the cross sectional area of a tensile coupon at failure.

F. Kulak et al. (1993) [10] conducted experiments on single and double angle tension members. Based on test results the following equation was proposed

푃 = 0.85휑 퐹 .퐴 + 훽.퐴 .퐹 (8)

Pp is the factored resistance of the member

휑 = 0.90

Fu = ultimate tensile strength of the material, Fy = yield strength of the material

AC = net area of the connected leg, Au = gross area of the connected leg

훽 = 1 .0 for members with four or more transverse lines of fasteners

= 0.5 for members with fewer than four transverse lines of fasteners

G. Usha et al. (2003) [18] developed a finite element model considering both material and geometrical non-linearity. Various parameters were studied and then compared with the respective experimental results. It was observed that the net section efficiency depends on connection length (b/L), the slenderness of outstanding leg (w/t), ratio of material yield strength to ultimate strength (fy/fu) and hence the following equation was proposed

푃 = 푓 × 퐴 + × 푓 × 퐴 (9)

= 1.38− 0.076 × × (10)

where Acn = net area of connected leg, Ao = area of the outstanding leg

H. Lip Teh et al. (2013) [12] studied net tension of cold reduced steel channel brace and proposed an equation for net section strength. It was observed to be influenced by stress concentration around the bolt hole, which is referred as in-plane shear lag, the out-of-plane shear lag, and the bending moment arising from the connection eccentricity with respect to the neutral axis. Based on the results presented in the paper of Pan (2004) and the results from Lip Teh et al. (2012)[13], a net section capacity for channel braces in tension is developed as given below

푃 = 퐴 .퐹 ..

(11)

where, 푤 = flange width,푤 = web depth,푥 = connection eccentricity, and푙 = length of connection.

From the review, it is found that the empirical equations reported in the literature are for angle sections only. All the equations addressed the shear lag effect of unconnected leg adequately f or angle sections. Its

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adequacy for channel sections will be discussed in the later sections. Further, the review of design guidelines reported in the codes has been conducted.

III. REVIEW OF INTERNATIONAL CODAL PROVISIONS

A. IS 800:2007 [9]

Indian standard considers three modes of failure for the design of tension members namely gross yielding, net section rupture, block shear and the least among these is considered as design strength. In angle and channel sections, for the design of net section rupture additional reduction factor beta (훽) is incorporated, which varies with connection length, slenderness of outstanding leg, and ratio of yield strength to ultimate strength and hence strength varies accordingly. Net section rupture is given by

푃 = 푓 × 퐴 + × 푓 × 퐴 (12)

= 1.38− 0.076 × × (13)

where, Acn = net area of the connected leg, Ao= gross area of outstanding leg

B. AISC 360: 2010 [1]

American standard considers the limit states of tensile yielding in the gross section and tensile rupture in the net section as the governing factors for the design of tension members. For tensile rupture in the net section, the equation is given by

푃 퐴 = 퐹 .퐴 .∅ (14) where, Ae = effective net area, Ag = gross area of the member, Fy = yield stress, Fu = ultimate stress, ∅ = 0.75.

C. Euro Code – 1993 [7]

Euro code takes into account the effect of spacing and edge distances of the bolts, number of bolts and pitch for the design of net section strength. Based on these parameters, euro code gives net section strength.

퐹표푟1퐵표푙푡푁 , = ( . ) (15)

퐹표푟2푏표푙푡푠푁 , =. . (16)

퐹표푟3표푟푚표푟푒푏표푙푡푠푁 , =. . (17)

β2 and β3 are the reduction factors dependent on pitch p1 as given in Table I. For intermediate values of p1, the intermediate values of β may be determined by linear interpolation. Anet is the net area of the section.

TABLE I. REDUCTION FACTORS BASED ON VARIATION OF PITCH

Pitch p1 ≤ 2.5d0 ≥ 5.0 d0 2 Bolts β2 0.4 0.7 3 Bolts β3 0.5 0.7

D. British Standard – 5950 [4]

British code states that for angles, channels, T-sections with eccentric end connection can be treated as axially loaded section with reduced net section area and hence reduced strength. The equation for net section tension capacity is given as

푃 = 푃 (퐴 − 0.5푎 ) (18)

Where Py is the ultimate tensile strength, a2 = Ag – a1, Ag = gross sectional area of the section, a1 = gross area of the connected element, Ae = sum of effective net areas given as, Ae = Ke an but ae < ag

Ke depends on grade of steel, where S 275 represents the specified minimum yield strength of the material (which is 275) and the yield strength of the material increases with increase in thickness of the member.

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For grade

S 275, Ke = 1.2 S460, Ke = 1.0 S 355, Ke = 1.1 For other steel grades Ke = (us/1.2)/py

E. Australian- 4100 [2]

Australian code provides two criteria for tension member design which are yield and ultimate strength. The yield criterion is given by (Ag .fy) and the ultimate strength through the net section is given by

푁 = 0.85퐾 퐴 푓 (19)

Kt is the correction factor for the distribution of forces determined in accordance with clause 7.3 of AS 4100 given as below

Kt = 0.75 for unequal angles connected by short leg, 0.85 otherwise Kt = 0.85 for channels sections Kt = 0.90 for T section

For sections on both sides of gusset plate, Kt = 1.

From the review of codal provisions, it is found that most of the codes suggest the adoption of the provisions given for angle sections to channel sections also. However, Australian-code adopts the shear lag of channel section through empirical factor. Hence, in order to check the validity of design guidelines given for angle sections, the experimental results available in the literature are collected and used for comparative study

IV. DETAILS OF EXPERIMENTAL WORK FROM LITERATURE

Udagawa et al. (2004) [11] conducted experiments on 42 channel sections in order to investigate the effect of bolt hole arrangements and edge distances of bolted joints on the ultimate tensile strength and failure modes. The setup is kept such that two channels are placed opposite to each other and a gusset plate is placed in between them and tension load is applied.

A. Specimen details Fig. 2 shows the specimen details of Udagawa et al. (2004) [11]. Channels of three different dimensions were considered which are (75x40x5x7), (100x50x5x7.5), (125x65x6x8). The arrangements of bolts were made in single rows and two rows and in each case the number of bolts are varied from 2 bolts to 5 bolts. The bolt arrangements of one line and high strength bolts of M16 or M20 of channel (75x40x5x7) are referred to as A series. A two line bolt hole arrangements and high strength bolts of M16 of channel (100x50x5x7.5) were referred to as B series. A two line bolt hole arrangements of high strength bolts of M16 or M20 were used for channels of (125x65x6x8) are referred to as C series. The pitch of different specimens were varied as 2.5d or 3.0d respectively, where d represents bolt diameters as 16mm or 20mm.

Fig.2: Test specimen (Kuniaki Udagawa et al)

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The different channel specimens were represented as xyz*, where x refers the number of bolt lines, y refers the number of bolts per row and z refers the variation of the configuration of bolts such as pitch and the end distance, * refers for 20 mm bolt diameter. Table II presents the specimen details

TABLE II. DETAILS ABOUT THE EXPERIMENTAL SECTIONS

Specimen Section fy (N/mm2) fu (N/mm2) g1/d e1/d

A122 75 x 40 x 5x7 304.11 459.108 2.36 4.5

A132 75 x 40 x 5x7 304.11 459.108 2.36 4.5

A142 75 x 40 x 5x7 304.11 459.108 2.36 4.5

A143* 75 x 40 x 5x7 308.034 464.994 1.87 2.51

A151 75 x 40 x 5x7 317.844 482.652 2.35 2.51

A152 75 x 40 x 5x7 304.11 459.108 2.36 4.5

A153* 75 x 40 x 5x7 308.034 464.994 1.88 2.5

B222 100 X 50 X 5 X 7.5 300.186 455.184 1.97 4.5

B232 100 X 50 X 5 X 7.5 300.186 455.184 1.97 4.5

B242 100 X 50 X 5 X 7.5 300.186 455.184 1.97 4.5

B251 100 X 50 X 5 X 7.5 300.186 455.184 1.97 4.5

C224 125 X 65 X 6 X8 300.186 464.013 1.99 4.5

C225 125 X 65 X 6 X8 299.205 456.165 2.33 4.5

C234 125 X 65 X 6 X8 300.186 464.013 1.99 4.5

C235 125 X 65 X 6 X8 299.205 456.165 2.33 4.5

C237* 125 X 65 X 6 X8 300.186 442.431 2.03 4.49

C244 125 X 65 X 6 X8 300.186 464.013 1.99 4.5

C245 125 X 65 X 6 X8 299.205 456.165 2.33 4.5

C247* 125 X 65 X 6 X8 300.186 442.431 2.03 4.49

C251 125 X 65 X 6 X8 299.205 456.165 2.33 4.5

C252* 125 X 65 X 6 X8 309.996 457.146 2.03 4.5

V. COMPARISION OF DIFFERENT EQUATIONS

With the results of Udagawa et al.(2004)[11],a comparative study has been conducted by using different code equations and empirical equations reported in the literature .The above empirical equations and different codal equations are studied and their failure capacities for the different experimental specimens are evaluated and compared with corresponding experimental value and their error is given in Table III and Table IV.

VI. RESULTS AND DISCUSSIONS

For BS code if only two number of bolts are used in single row, the error in prediction is high. But on increasing the number of bolts it predicts with reasonable accuracy. This concludes that as we increase the length of connection, the shear lag effect reduces, hence the prediction value is closer to actual value.

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TABLE III. PERCENTAGE ERROR IN PREDICTION OF STRENGTH AS PER DIFFERENT INTERNATIONAL CODES

For two numbers of bolts, error in prediction by using Euro Code equations is high. Error as high as about 58% is observed. Hence these equations are too economical to be considered for designs.

All the predictions with respect to AISC and IS CODE are with an accuracy of about 90%. Also AISC has better prediction than all the codes, because it considers the effect of eccentricity of the connection to account for the effect of shear lag.

It can be observed that on specimens (C224, C225), (C234, C235) and (C244, C245) only parameter that change is the gauge and their experimental strength changes significantly, whereas the codal predictions do not show a significant change. This is because gauge distance is not considered in any of the equations. It has to be considered as a parameter.

Specimen

Experimental Udagawa et al. (2004) IS Code AISC AUS Euro code Canadian BS Code

(KN) (%) (%) (%) (%) (%) (%)

A122 212.58 -18.85 -19.21 -56.95 29.70 -6.70 -74.39

A132 296.90 2.45 -2.54 -12.38 50.47 13.41 -24.87

A142 331.92 9.01 3.12 -0.52 55.70 22.55 -11.69

A143* 337.51 11.51 5.59 -0.12 47.99 24.85 -6.84

A151 344.38 7.32 0.75 -1.85 45.69 21.52 -13.17

A152 335.75 8.20 1.67 0.62 56.20 23.43 -10.42

A153* 337.37 9.71 3.15 -0.17 47.97 24.82 -6.89

B222 265.56 -10.63 -0.78 -44.97 57.43 35.39 -2.32

B232 340.65 -4.06 -5.65 -13.01 57.43 26.77 -2.32

B242 385.93 2.91 -1.29 0.25 57.43 26.77 -2.32

B251 401.18 4.08 -1.35 4.04 57.43 26.77 -2.32

C224 435.51 12.78 1.50 -33.85 56.27 33.62 -6.92

C225 380.92 5.78 -10.71 -50.45 56.27 33.62 -6.92

C234 526.50 5.06 -5.77 -10.72 56.27 24.77 -6.92

C235 472.84 -2.99 -15.78 -21.20 56.27 24.77 -6.92

C237* 473.33 -1.73 -8.54 -13.61 57.69 27.22 -1.51

C244 599.29 9.92 -0.09 2.73 56.27 24.77 -6.92

C245 559.42 1.50 -5.42 -2.44 56.27 24.77 -6.92

C247* 539.35 3.94 -2.60 0.29 57.69 35.78 -1.51

C251 602.82 8.59 -1.37 4.93 56.27 24.77 -6.92

C252* 566.87 2.26 -4.52 1.98 57.69 27.22 -1.51

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TABLE IV. PREDICTED STRENGTH FOR DIFFERENT EMPIRICAL EQUATIONS

Specimen

Experimental Udagawa et al. (2004) Nelson et al. (1953) Teh et al. (2013) Pan (2004) Munse and Chesson (1963)

(kN) (kN) (kN) (kN) (kN)

75 x 40 x 5x7 212.58 191.48 238.50 295.65 208.27

75 x 40 x 5x7 296.90 230.90 287.33 390.06 290.05

75 x 40 x 5x7 331.92 257.40 287.90 390.97 290.84

75 x 40 x 5x7 337.51 253.12 291.59 395.99 294.57

75 x 40 x 5x7 344.38 290.61 302.96 411.50 306.17

75 x 40 x 5x7 335.75 276.43 288.18 391.43 291.24

75 x 40 x 5x7 337.37 272.96 291.88 396.45 294.97

100 X 50 X 5 X7.5 265.56 200.31 267.63 324.11 246.14

100 X 50 X 5 X7.5 340.65 246.05 297.74 390.78 310.18

100 X 50 X 5 X7.5 385.93 277.77 309.34 413.00 331.53

100 X 50 X 5 X7.5 401.18 301.05 315.49 424.11 342.21

125 X 65 X 6 X8 435.51 339.41 411.10 504.03 382.17

125 X 65 X 6 X8 380.92 333.67 404.15 495.50 375.71

125 X 65 X 6 X8 526.50 408.13 453.71 596.43 469.37

125 X 65 X 6 X8 472.84 401.22 446.03 586.34 461.43

125 X 65 X 6 X8 473.33 360.51 427.42 567.27 458.09

125 X 65 X 6 X8 599.29 454.09 469.94 627.23 498.43

125 X 65 X 6 X8 559.42 446.41 470.41 631.76 504.29

125 X 65 X 6 X8 539.35 403.95 439.83 590.00 479.97

125 X 65 X 6 X8 602.82 478.77 470.41 631.76 504.29

125 X 65 X 6 X8 566.87 449.92 461.15 621.36 507.24

VII. SUMMARY AND CONCLUSIONS

An attempt has been made to check the validity of these equations for channel sections. For this purpose, guidelines available in various codes of practices and literature are revisited. Several International Codal provisions and equation available in literature, on shear lag effect have been reviewed. The capacity predicted by these equations are compared with the experimental results available in literature. Gauge distance is found to influence the net-section capacity significantly and has been not considered adequately. Hence it should be considered.

ACKNOWLEDGEMENTS

This paper is being published with the kind permission of Director, CSIR-SERC.

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REFERENCES

[1] AISC-LRFD (1999), “Load and Resistance Factor Design Specification for Structural Steel Buildings’. American Institute of Steel Construction, Chicago, III.

[2] AS4100 (1998), “Australian Standards- Steel Structures”, Standards Association of Australia, The Crescent, Homebush, NSW 2140.

[3] ASCE Manual No.52 (1988), “Guide for Design of Steel Transmission Towers” American Society of Civil Engineers.

[4] BS-5950 – Part 1(1990), “Code of Practice for Design in Simple and Continuous Construction: Hot rolled sections” British Standards Institute, London.

[5] CAN/CSA-S16.1-M94 (1994), “Limit States Design of Steel Structures”, Canadian Standards Assoc., Rexdale (Toronto), Ontario, Canada, M9W 1R3.

[6] Chi-Ling Pan (2004). “Prediction of the strength of bolted cold-formed channel section in tension.” Thin-Walled Struct., 42(8), 1177–1198.

[7] Eurocode 3 (1992), “Design of Steel Structures”, General Rules and Rules for Buildings. [8] Gaylord E.H and Stallmeyar J.E. (1992), ‘Design ofsteel structures’, McGraw Hill Book Company, New York. [9] IS: 800 (1984), “Code of Practice for General Construction in Steel” Bureau of Indian Standards, New Delhi. [10] Kulak and Wu (1997), “Shear Lag in Bolted Angle Tension Members”, ASCE, Journal of Structural Engineering,

vol 123, n.9, pp. 1144-1152. [11] Kuniaki Udagawa and Takao Yamada (2004), “Ultimate strength and failure modes of tension channels jointed with

high-strength bolts” 13th World Conference on Earthquake Engineering Vancouver, B.C., Canada August 1-6, 2004 Paper No.3288.

[12] Lip H. Teh, A.M.ASCE; and Benoit P. Gilbert (2013), “Net Section Tension Capacity of Cold-Reduced Sheet Steel Channel Braces Bolted at the Web” journal of structural engineering, may 2013

[13] Lip H. Teh, and Gilbert, B. P. (2012). “Net section tension capacity of bolted connections in cold-reduced steel sheets.” J. Struct. Eng, 138(3), 337–344.

[14] Marsh, C. (1969), “Single Angles in Tension and Compression,” ASCE J. Struct. Div. Tech. Note, Vol. 95, No. ST5, pp. 1043–1049.

[15] McKibben, F.P., (1906), “Tension tests of steel angles”, Proc. of ASTM, vol 6, pp.267-274. [16] Munse and Chesson (1963), “Riveted and Bolted Joints: Net section Design”, ASCE, [17] Nelson, H.M., (1953), “Angles in tension” Publication No.7, British Constructional Steelwork Assoc., UK, pp.8-18 [18] Usha (2003), “Analytical study on Non-linear behavior of steel angle tension members”, M. S Thesis, Department of

Civil Engineering, IIT Madras, India.

Distributed Generation: Benefits, Issues and

Challenges

1Prasanna Kumar Biswal, 2Deepak Kumar Lal and 3Bidyadhar Rout 1-3Department of Electrical Engineering, Veer Surendra Sai University of Technology, Odisha, India

1prasannabiswal7@gmail.com 2laldeepak.sng@gmail.com 3bdr23@rediffmail.com

Abstract— Integrating of Distributed generation (DG) into power system is one of the emerging technological innovations in power sector that brings several benefits besides supporting power supply to the feeder. DG operates in parallel with distribution network meets base load, provides peak load, power quality improvement and generation backup stand-by supply. However, the connection of DG with the complexity of power system raises various issues. The inclusion of DG in distribution system changes the operating characteristics such as power losses, voltage profile, stability and reliability of distribution system. Moreover, the impact of DG in power system depends on various technical features, such as technology, size of the units, operation and control strategies and location in the power network. This paper listed few challenges related to integration of DG in distribution system. Index Terms— Distributed generation, Distributed generation benefits, Power quality, Reliability, Regulations.

I. INTRODUCTION

Distributed generation (DG) is an emerging approach in electric power sector. It is seen that there is no consensus on a precise definition of DG due to its varying technology and wide applications. The best definition of DG is an electric power generation source within the distribution networks or on the customer side of the network [1-3]. These are also called dispersed generations, embedded generations and decentralized generations depending on purpose, location, power delivery, technology, ownership and penetration of distributed generation in the world [1]. DG includes both conventional and renewable energy resources. The renewable energy sources are environmentally friendly, that includes photo-voltaic system, wind turbines, small/micro hydro plants, fuel cells, micro-turbines, reciprocating engines etc. and storage technologies such as batteries, flywheels, ultra capacitors and superconducting magnetic energy storage. Being increasing interest on DG worldwide, it is expected to play a major role in power system in near future. Integration of DG in distribution system has several benefits to utilities and customers [2-8]. A general approach has been proposed to assess the technical benefits of DG in a quantitative manner [5]. DG has the benefit to be used as a backup source and improve power system reliability [8, 9]. Nevertheless, the reliability of the power system reduces if DG is not properly coordinated, located and designed to work with existing network components [10, 11]. The impacts of DG on reliability indices and power quality are presented in [12]. The impact on power systems including intentional islanding on reliability are discussed [13]. The impact of DG on dynamics of power system and stability is investigated in [14-16]. Distributed Grenze ID: 01.GIJET.1.1.20 © Grenze Scientific Society, 2015

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resources impact on system voltage, capacitor operation, voltage regulator or load tap changing (LTC) transformer is presented in [17] in different operation mode of distribution system. Integration of DG in power system may impact positively or negatively depending on various technical features. Therefore, connection and increasing penetration of DG should be carefully evaluated and planned. Distribution system planning frameworks with DG in deregulated electricity market are proposed in [18, 19]. This paper presents a general discussion on integrating DG benefits, issues and challenges in sections II, III and IV respectively. Finally conclusion is given in section V.

II. DG BENEFITS

Placement of DG in suitable location in distribution system has several benefits. The benefits are categorized into three groups:

A. Technical benefits 1. Reduced line losses and voltage profile improvement The power flow in the traditional distribution line is from the generating station to distribution systems. But placement of DG changes this scenario. Presence of DG converts the passive distribution network to active network and provides power locally to the loads which results in reduction of current flow in some part of the network. Consequently, there happens the reduction of line losses which are very much dependent on line currents. Similarly location and size of DG affects the voltage drop in the lines due to change scenario of flow of line current. DGs with power electronic converters are capable to deliver certain amount of reactive power, when it is necessary for the line. Hence DG integration impact positively on voltage profile and also minimizes line losses through avoiding the flow of reactive power over larger distances. 2. Increased overall energy efficiency Reducing line losses, improving voltage profile and power factor correction increase overall energy efficiency. 3. Enhanced system reliability and security Proper coordination between DG units and rest of the network results improvement of distribution system reliability. DG units can be used as a generation backup during interruption of main supply. For sensitive and critical loads, DG provides a standby power supply where the grid is not very reliable. A DG can be modelled as constant active and reactive power injections independent of the system voltage at the unit terminal bus. Also it can be modelled as controlled voltage sources in which the terminal voltage is maintained at a constant value by reactive power injection. In both the cases the reliability of the system improves. 4. Improve power quality Many distribution systems are operated radially and the distance customers experience low voltage at their terminals due to voltage drop in the lines. The locations of DG near the load, counter the poor voltage regulation. DG can also help to mitigate voltage sags during a fault. Thus DG improves power quality of both DG owners as well as nearby loads.

Fig. 1 A radial distribution system with DG

5. Relieved transmission and distribution (T&D) congestion DG provides power locally to the load as shown in fig.1 and reduces power flow in some of the transmission network. It reliefs the transmission capacity and manages congestion in power system.

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B. Economical benefits 1. Deferred investments for upgrades of facilities DG provides power locally to the load. So these can reduce or avoid the need for building new T&D lines, upgrade the existing power systems and reduce T&D networks capacity during planning phase [20, 21]. 2. Enhanced productivity Increased energy efficiency and improved power quality enhance productivity. T&D lines capacity release increases the system equipment and transformers lifetime. 3. Reduced health care costs due to improved environment Since most of the DG includes renewable energy sources, it has very little impact on environment. Thus it reduces health care costs. 4. Reduced fuel costs due to increased overall efficiency Increased energy efficiency, improved power quality and increased productivity ultimately reduce fuel requirements and its associated costs. 5. Reduced reserve requirements and the associated costs DG can be used as a generation backup during interruption from main supply and also cost effective source of peak power demand. So it ultimately reduces reserved requirements and the associated costs. 6. Lower operating costs due to peak shaving DG is a cost effective source of peak power demand, or economic savings in energy consumed from utility and electricity demand charges [4].

C. Environmental benefits Local atmospheric pollution, regional (acid rain) and global (greenhouse gases) environmental problems, mainly from the use of fossil fuels, are well established. Moreover, the still unsolved problem is of disposing of nuclear waste. Renewable energy sources provide a promising alternative and their deployment is thought of as an important energy policy priority for many countries. It is well known that renewable energy is environmentally friendlier than conventional fuels, it is indigenous, promoting national energy independence, and could actively contribute to local job creation. Renewable DG has several environmental benefits and could provide a promising alternative to conventional power generation if some economic, institutional, social and technical barriers could be overcome, and the appropriate planning instruments for their deployment be developed.

III. DG Integration Issues

There are various issues confronting the user of DG when integrating with distribution system and utility grid.

A. Voltage level A rise in the voltage level above permissible limit in radial distribution systems is a key factor that limits the additional DG capacity. Drop of voltage may also occur due to improper location and coordination of DG with capacitor operation, voltage regulator or LTC transformer [13, 17]. So voltage control is an issue when DG is connected to the distribution grid as mention by IEA (2002) [22].

B. Reactive power Most of the DG technologies use asynchronous generators. These machines derive excitation from the network and behave as reactive loads even if they generate active power. Hence voltage control is very difficult with these machines. Low power factor in induction machines draws more reactive power and low power factor results large fault current. DGs with power electronic converters are capable to deliver certain amount of reactive power, when it is necessary for the line.

C. Reverse power flow The power flow in the traditional distribution line is unidirectional from the generating station to distribution systems. But integration of DG in distribution system changes this scenario. An increased size of DG units may cause power flows from the low voltage distribution grid to the medium or high voltage grid. Thus, the system requires new protection schemes for this type of application.

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D. System frequency Imbalances between demand and supply of electricity cause the system frequency to deviate from the rated value. Increasing in the capacity of DG units affect the system frequency and have the potential to become free riders on the efforts of the transmission grid operator and the regulatory body and increases the complexity of control.

E. Protection scheme The issues related to protection scheme are shown in fig. 2 to 4. As shown in fig.2, if any fault occurs at A, the fault current will flow from the grid and DG. The fault current increases depending on distributed generators types and characteristics. Relay located between bus 2 and bus 3 will only measure the current flowing from the grid. Means, the relay detects only a part of the real fault current and may therefore not trigger properly. With a fault at bus 2 as shown in fig. 3, fault current from DG passes the relay in reverse direction, which can cause problems if directional relays are used. Thus location of DG changes the magnitude, duration and direction of the fault current in a line. The solution of the above problem is to use directional over current relays. But fault current contribution from relatively large DG may cause a nuisance trip of breaker A as the case shown in fig. 4 [12].

Fig. 2 A radial distribution system having DG and a fault at point A

Fig. 3 A radial distribution system having DG and a fault in a line between buses 2 and 3

Fig. 4 A radial distribution system having DG and a fault near to bus 5

IF

DG

Grid Bus 1 Relay A

Relay B

Bus 2

Bus 3

Bus 4

Bus 5 Load 1

Load 2

34

F. Islanding protection Islanding is a condition which a portion of the utility system that contains distributed resources/group of distributed resources and some loads remains energized while isolating from main utility system. A DG may energize a certain segment of the network, which may cause risk to repairing personnel come into contact. Hence protective equipment must be placed to avoid such situation. In most cases it is not desirable for a DG to island with any part of the utility system because this can lead to safety and power quality problems that will affect the utility system and loads [13]. Also reliability will reduce due to time elapsed for re-synchronizing with the main utility.

G. Power quality and reliability Both electric utilities and end users are becoming increasingly concerned about the quality of electric power due to various reasons. Any power problem manifested in voltage, current or frequency deviations that result in failure or misoperation of customer equipment is called power quality problem. The benefit of DG to improve power quality of the DG owner and nearby loads is discussed in previous section. But connection of DG may also causes system frequency deviation due to demand supply mismatch, injection of harmonics by DG having power electronic converters and rise of voltage due to non-optimal placement and sizing of generation units etc. The introduction of DG in radial distribution system may cause reverse power flow. This reduces line voltage drops and it may increase the service voltage at customers end. If a voltage regulator or LTC transformer is present at substation for line drop compensation, then unsuitable location and coordination of DG causes interference of LTC transformer operation [12, 16] and results poor voltage regulation. Investigation shows that DG may cause voltage flicker and introduce harmonics [12]. If DG starts or its output fluctuates frequently enough, flicker may be noticeable to customers lighting loads, and this is a well known phenomena of intermittent renewable DG sources. Some DG such as PV, fuel cells etc produce direct current. Hence, these are connected with the grid via DC-AC power electronics converter, which may contribute harmonics in power system. Also asynchronous DG sources which use power electronics converter for interconnection injects harmonics into the system. The harmonics type and severity will depend on the power converter technology and interconnection configuration. DG can be used as a generation backup during outages of main supply [9]. If the DG is sized to support the critical load having very less starting time, then reliability for customer load improves considerably. But the improvement of reliability of system having number of customers by integration of DG cannot be realized.

IV. CHALLENGES TO INTEGRATE DG

Challenges to integrate DG into distribution network are listed below.

A. Power quality The aspects of integration of DG such as benefits and problem in view of power quality are presented in previous sections. DG may support the system or deteriorate power quality. So connecting DG is a challenging task and every possible ways need to be developed to counter power quality problems.

B. Protection scheme An issue on failure of protection schemes due to introduction of DG in traditional distribution systems is discussed. Therefore, for each connection of DG in distribution system, the protection selectivity must be re-evaluated. Also research need are for finding the solution of nuisance tripping of breaker and issues related to fuse saving.

C. Stability When the DG size is small, the impact on power system dynamic performance is negligible. Investigation shows that the effects of DG on the dynamics of a power system and stability strongly depend on the technology of the distributed generators [15, 16]. Large penetration of DG may lead to instability of the voltage profile due to the bidirectional power flows and complicated reactive power equilibrium arising when insufficient control is introduced. The voltage throughout the grid may fluctuate. The situation deteriorates if DG includes variable renewable energy resources. Therefore maintaining stability of power system is a challenging task after integration of DG and in increased penetration.

35

D. Regulatory Most of the DGs are owned by customer. Some form of incentive schemes are in existence in many countries in the world for renewable DGs [6]. But surveys indicate that at present situation majority of the countries do not have well defined regulation and security standards [4, 6]. Many countries have no common guidelines for the connection of DG units to the utilities in their region. The rules for connection of DG are defined individually by the local utilities.

V. CONCLUSIONS

This paper has surveyed and presented DG benefits, key issues and challenges for DG integration to distribution networks. DG has the potential to improve distribution system performance. Also DG increases the complexities of controlling, protecting and maintaining the distribution systems. Therefore, DG connections are of most interest to power system planners, policy makers and regulators, DG owners and customers.

REFERENCES

[1] Ackermann, Thomas, Göran Andersson, and Lennart Söder, "Distributed generation: a definition", Electric power systems research 57, no. 3 (2001): 195-204.

[2] Pepermans, Guido, Johan Driesen, Dries Haeseldonckx, Ronnie Belmans, and William D’haeseleer, "Distributed generation: definition, benefits and issues", Energy policy 33, no. 6 (2005): 787-798.

[3] El-Khattam, Walid, and M. M. A. Salama, "Distributed generation technologies, definitions and benefits", Electric Power Systems Research 71, no. 2 (2004): 119-128.

[4] Dondi, Peter, Deia Bayoumi, Christoph Haederli, Danny Julian, and Marco Suter, "Network integration of distributed power generation", Journal of Power Sources 106, no. 1 (2002): 1-9.

[5] Chiradeja, Pathomthat, and R. Ramakumar, "An approach to quantify the technical benefits of distributed generation", IEEE Transactions on Energy Conversion, 19, no. 4 (2004): 764-773.

[6] J.A.Pecas Lopes, N. Hatziargyriou, J. Mutale, P. Djapic, N. Jenkins, “Integrating distributed generation into electric power systems: A review of drivers, challenges and opportunities”, Electric power systems research 77, (2007): 1189-1203.

[7] Greatbanks J. A., Popovic D.H., Begovic M., Pregelj A., Green T.C., "On optimization for security and reliability of power systems with distributed generation", Power Tech Conference Proceedings, 2003 IEEE Bologna , vol.1, no., pp.8 pp. Vol.1, 23-26 June 2003.

[8] Waseem I., Pipattanasomporn M., Rahman S., "Reliability benefits of distributed generation as a backup source", IEEE Power & Energy Society General Meeting, 2009. PES '09, pp.1-8, 26-30 July 2009.

[9] Borges, Carmen LT, and Djalma M. Falcao, "Optimal distributed generation allocation for reliability, losses, and voltage improvement", International Journal of Electrical Power & Energy Systems 28, no. 6 (2006): 413-420.

[10] Chowdhury, A. A., Sudhir Kumar Agarwal, and Don O. Koval, "Reliability modeling of distributed generation in conventional distribution systems planning and analysis", IEEE Transactions on Industry Applications 39, no. 5 (2003): 1493-1498.

[11] Senjyu, Tomonobu, Yoshitaka Miyazato, Atsushi Yona, Naomitsu Urasaki, and Toshihisa Funabashi, "Optimal distribution voltage control and coordination with distributed generation", IEEE Transactions on Power Delivery 23, no. 2 (2008): 1236-1242.

[12] McDermott, Thomas E., and Roger C. Dugan, "Distributed generation impact on reliability and power quality indices", In Rural Electric Power Conference, 2002 IEEE, pp. D3-D3_7, IEEE, 2002.

[13] Barker, Philip P., and Robert W. De Mello, "Determining the impact of distributed generation on power systems. I. Radial distribution systems", In IEEE Power Engineering Society Summer Meeting, 2000, vol. 3, pp. 1645-1656. IEEE, 2000.

[14] Hadjsaid, Nouredine, J-F. Canard, and Frederic Dumas, "Dispersed generation impact on distribution networks", Computer Applications in Power, IEEE 12, no. 2 (1999): 22-28.

[15] Slootweg J.G., Kling W.L., "Impacts of distributed generation on power system transient stability", IEEE Power Engineering Society Summer Meeting, 2002, vol. no. 2, pp. 862-867, 25-25 July 2002.

[16] Azmy A.M., Erlich I., "Impact of distributed generation on the stability of electrical power system", IEEE Power Engineering Society General Meeting, 2005, pp. 1056-1063 Vol. 2, 12-16 June 2005.

[17] Walling, R. A., Robert Saint, Roger C. Dugan, Jim Burke, and Ljubomir A. Kojovic. "Summary of distributed resources impact on power delivery systems", IEEE Transactions on Power Delivery 23, no. 3 (2008): 1636-1644.

[18] El-Khattam, Walid, Kankar Bhattacharya, Yasser Hegazy, and M. M. A. Salama, "Optimal investment planning for distributed generation in a competitive electricity market", IEEE Transactions on Power Systems 19, no. 3 (2004): 1674-1684.

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[19] Porkar, S., P. Poure, A. Abbaspour-Tehrani-fard, and S. Saadate, "A novel optimal distribution system planning framework implementing distributed generation in a deregulated electricity market", Electric Power Systems Research 80, no. 7 (2010): 828-837.

[20] Brown, R.E., Jiuping Pan, Xiaoming Feng, Koutlev, K., "Siting of distributed generation to defer T&D expansion," Transmission and Distribution Conference and Exposition, 2001 IEEE/PES, vol. no. 2, pp.622-627 vol.2, 2001.

[21] Gil, Hugo A., Geza Joos, "On the quantification of the network capacity deferral value of distributed generation", IEEE Transactions on Power Systems 21, no. 4 (2006): 1592-1599.

[22] IEA, Distributed Generation in Liberalized Electricity Markets, Paris, 128 pages, 2002.

Experimental Analysis of Harmonics Reduction in

Single Phase Battery Charger

1Dr. M.Narendra Kumar, 2Mr. Kuldip Singh and 3Dr.K.S.R. Anjaneyulu 1,2GNIT, Hyderabad,3 JNTU Anatapur,

Email: vp.gnit@gniindia.org, Phone: +91-8096609840

Abstract— The harmonic distortion is one of the most important problem associated with power quality and creates several disturbances in the power system. This paper includes the harmonic reduction technique to improve the power quality and includes the simulation for the same. Mobile/Laptops battery chargers are non-linear devices that inject harmonic currents and pollute network voltage [1]. Distorted current or voltage waveforms from its ideal form will be treated as harmonic distortion. Harmonics are generated due to non-linear load. In this paper we simulated the battery charging process, the methods to reduce the harmonic effects and analyze the impact of harmonics. Index Terms— Battery charger, Harmonics, Filters, Power quality.

I. INTRODUCTION

The growing presence of non-linear loads in commercial, industrial and residential installations has lead to a rise in harmonic levels in power distribution system [1]. The mobile phone/Laptops battery are charged by single phase supply. Due to this charging process the harmonic current are injected and create the power quality problem. The harmonic distortion is a form of electrical pollution that can cause problems if the sum of the harmonic currents increases above certain limits. A harmonic current is one with multiples of fundamental frequency, for instance a 250 Hz current on a 50 Hz network is the 5th harmonic. The 250 Hz current represents energy that cannot be used by devices on the network. It will be converting in to heat. According to the International Electro technical Commission (IEC), the level of harmonics is described by the total harmonic distortion (THD). THD is expressed as a percentage of the total voltage or current. In the standard IEEE 519 it is referred to as total demand distortion (TDD)[2]. The harmonics may cause cables to overheat and damage their insulation. Capacitors overheat with-in, is the most severe case and the risk of explosion due to the dielectric breaks-down. Electronic displays and lighting may flicker, circuit breakers can trip, and computers fail and meters give false readings. Harmonic currents and voltages are created by non-linear loads connected on the phone chargers/ Laptops. All power electronic components used in different types of electronic systems can increase harmonic disturbances by injecting harmonic currents directly into the supply network. The Different level of Harmonics are shown in Fig.1. This paper analyzes the use of capacitors and inductances to reduce the harmonic emission of single phase mobile phone/Laptop battery chargers. The study is supported by experimental measurements in actual installations.

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Fig. 1 Different level of harmonics. Fig:2 Block diagram of a single phase chargers

II. SINGLE PHASE BATTERY CHARGERS

The single phase phone/laptop charger is used for cell phone/Laptops battery charging. The Fig.2 is shown the block diagram of single phase charger. It consists of single phase transformer which step down the 230V to 12V AC .The single phase diode bridge is used as a rectification from 12V AC to 12V DC and LC components are used as a smoothing circuit for remove the ripple and by using regulation circuit the 12DC is regulated to 5V DC. The supply voltage V and the battery voltage E are also plotted as reference is shown in Fig 3 This circuit operates in discontinuous conduction mode where two different states can be distinguished: -The diodes are off and the current” i” is zero. -The current “i” flow through the rectifier diodes and charge the battery.

Fig. 3 Voltage and current waveform

The commutation angles ߠଵ andߠଶ which define the charges AC current considering half-wave symmetry conditions. To obtain the instantaneous wave shape of the current, these angles must be determined by analyzing the circuit states corresponding to the current segment I and II. The E is the voltage in battery. [1]

Where ଵܸis the rms value of the fundamental supply voltage v. The circuit diagram for single phase cell phone charger is show in Fig-4 and the input voltage waveform with harmonics feedback to network is shown in Fig-5.

III. FILTER DESIGN CONSTRAINTS

There are various issues in the design of a passive filter for its proper functioning in harmonic reduction. The key issues are mentioned here: Minimizing harmonic source current. The prime objective of the filter design is to minimize the harmonic current in ac mains. This is ensured by minimizing the filter impedance at the harmonic frequencies so that the harmonic filter acts as a sink for the harmonic currents. Minimizing fundamental current in passive filter To ensure that the installation of passive filter does not cause the system loading, the

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Fig-4 Circuit diagram for Cell phone chargers Fig: 5 voltage with Harmonics feeding back to network

fundamental current in the passive filter is minimized by the maximizing the passive filter impedance at the fundamental frequency. Environment and ageing effect The capacitors with metalized film construction lose capacitance as they age. Similarly the manufacturer tolerance of the harmonic filter reactor may result in tuned frequency higher than the nominal. IEEE Standard recommends that the passive filters are tuned at 6% below the rated frequency so that it will exhibit acceptable tuning at the end of its 20 year life. The resonant frequency for the nth harmonic is given as:

F=1/2.π.n.C.R (3) The values of filter components can be calculated from above equations Quality factor can be defined as

Q=L/(CR)2 (4) The values of filter components can be calculated from above equations.

IV. MITIGATION OF SINGLE PHASE CHARGER HARMONICS BY LINE INDUCTANCE AND CAPACITANCE

The mitigation method is based on the increase in AC side inductance L Henery. This leads to a growth in current pulse width and thus to a decrease in the harmonics contents of the current wave [1]. From eq. 1 & 2 , we can derive that the commutation angles approximately depends on the ration E/V only. In the boundary

between the commutation angles coincide and the boundary conditions are obtained from equ. 1 & 2 [2].

For commutation angle ߠଵsmaller than ߠ, the current extinguishes when the emf E is greater than the instantaneous supply voltage and the current through the diodes stop at this point . on the other hand, for commutation angle ߠଵgreater than ߠ, the emf E is always smaller than the supply voltage and current continues flowing through the diodes all the time.[1]

V. SIMULATION ANALYSIS

In experimental analysis we have simulated the battery charger with different filters for single phase charging. The results are analyzed based on the impact of filter on input side and output voltage side. We used different filters to know the voltage level. Simulation is done with the help of circuit shown in Fig 6. a.) Capacitor filter C connected both Input Side and Output side of transformer: As shown below in Fig. 7

we have shown the impact of C filter on the output voltage. This contains the harmonics.

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Fig 6. Simulink circuit for simulation

Fig: 7 Output Voltage with C-Filter

Fig: 8 Output voltage with LC filter

b.) Output Side LC filter and input of transformer is with Inductance L. we have shown the impact of inductance L on the output voltage and impact of LC filter on DC voltage side in Fig. 8

Fig. 9 DC voltage with LC

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Fig:10 Output voltage with LC filter

c.) Output side Capacitance C and input side LC filter: As given below Fig 9 & Fig-10 the impact of inductance LC on the Reverse voltage.

The THD is defined as the root mean square (RMS) value of the total harmonics of the signal, divided by the RMS value of its fundamental signal. For example, for currents, the THD is defined as

Total harmonic distortion (THD) = IH/IF, (5)

Where

and In = RMS value of the harmonic n IF = RMS value of the fundamental current.

Fig. 11 FFT analysis of C-L filters

Fig. 12 FFT analysis of LC-C filters

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Fig. 13 FFT analysis of C-LC filters

The THD has a null value for a pure sinusoidal voltage or current.

TABLE I. WITH DIFFERENT FILTER THD VALUES

S.NO Filter Type THD (DC)

THD (AC)

1 C-L 0.603 9.71%

3 LC-C 11 30.45%

4 C-LC 0.523 7.45%

As per experimental analysis of single phase battery charger with different filters to reduce the harmonic effects on DC and AC voltage, we find out the different values of THD by simulation as shown in Table.1. When the tupe of filter is changing the harmonic values also changing in AC and DC voltage. From simulation results we found that the Capacitance (C) filter is more efficient to remove the harmonics in DC voltage and LC filter is more efficient to remove harmonics in reverse AC voltage. By using these filters the power quality in single phase battery charger in improving. From above experimental analysis we have seen the impact of LC filter on output voltage and impact of Capacitance filter on DC voltage.

VI. CONCLUSION

This paper studies the use of inductance (L) and Capacitance (C) to reduce the harmonics emission of single phase mobile/laptop charger. The modified circuit is simulated and thus obtained results are without harmonics in AC and DC .In this paper we simulated the single phase Battery charging process and analyzed the impact of harmonics and the methods to reduce the harmonic effects. The C-LC filter is more effective filter to reduce the Harmonics from reverse AC and DC voltage.

REFERENCES [1] L.Sainz and J Balcells, “ Experimental measurements about harmonics current of electric vehicle battery chargers”.

Department of Electronics Engineering, E.T.S.E.I.B. (UPC) 1997. [2] J. G. Mayordomo, A. Hernández, R. Asensi, L. F. Beites and M. Izzeddine, “A unified theory of uncontrolled

rectifiers, discharge lamps and arc furnaces. PART I: An analytical approach for normalised harmonic emission calculations”, in Proc. 8th IEEE ICHQP 1998, pp. 740-748.

[3] B. Singh, and K. Al-Haddad, “A review of active filters for power quality improvement,”IEEE Transactions on Industrial Electronics, vol. 46, no. 5, pp. 960-971, Oct. 1999.

[4] M. Singh, and V. Tiwari, “Modeling analysis and solution of power quality problems,”National Level Conference Problem Practices and Prospects in Power Distribution System Operation and Control, pp.121-132,2012.

[5] L. Chen, and A. V. Jouanne, “A comparison and assessment of hybrid filter topologiesand control algorithms,” IEEE/PESC Ann. Meeting Conf, vol. 2, pp. 565-570,2012.

[6] Kannan Karthik, and J.E.Quaicoe, “Voltage compensation and harmonic suppressionusing series active and shunt passive filters,” Electrical and Computer Engineering, Canadian Conference, vol. 1, 2000, p. 582-586.

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[7] J. A. Orr, A. E. Emanuel and K. W. Oberg, “Current harmonics generated by a cluster of electric vehicle chargers”, IEEE Trans. on Power Apparatus and Systems, Vol. PAS-101, No. 3, March 1982, pp. 691-700.

[8] J. A. Orr, A. E. Emanuel and D. J. Pileggi, “Current harmonics, voltage distortion, and powers associated withbattery chargers. Part I: Comparisons among different types of chargers”, IEEE Trans. on Power Apparatus and Systems, Vol. PAS-101, No. 8, August 1982, pp. 2703- 2710.

Discharge Estimation by Rational Method using Global Mapper GIS for Sustainable Stormwater

Management: A Case Study from Pune City

Nivedita G Gogate1 and Dr Pratap M Rawal2

1Assistant Professor, Department of Civil Engineering, MIT, Pune, Maharashtra, India 2Professor, Department of Civil Engineering, COEP, Maharashtra, India

Abstract— The sharp rise in urban development has led to an increase in impervious areas and a decrease in vegetated surfaces. The thrust toward this development has caused drought and overflow problems to occur. In the 1960s, management of stormwater quantity for flood prevention was the only imperative in the developed countries, but in subsequent decades, objectives for stormwater management have diversified to include quality, ecosystem health, reuse, integration with urban design etc along with quantity and has inspired the development of novel stormwater management approaches designed to minimize impervious cover and maximize infiltration of rainfall known as Low Impact Development (LID) in USA and Water Sensitive Urban Design (WSUD) in Australia. The massive urbanization in India has resulted in generation of huge quantities of stormwater which are unutilized and polluted. Managing urban stormwater in India poses huge challenges and the consequences of its neglect are severe. India too needs to adopt sustainable practices in overall water management. Stormwater is being managed in a traditional way in most of the urbanized cities of India. At many places, natural drains simply carry the runoff and engineered infrastructure is absent. This has led to the problem of localized flooding and consequent deterioration of roads. In order to study the present stormwater situation, a case study of Pune city in Maharashtra state is selected. In this work, an attempt is made to determine the stormwater quantity in a sub basin of Pune city by rational method using Global Mapper GIS software. It also presents the analysis of stormwater quality in the same sub basin. The constraints in adopting sustainable techniques are discussed with respect to the case study. This data will be further used to identify suitable sites for stormwater recharge subsequently. Index Terms— Stormwater Management, Low Impact development, Water Sensitive Urban Design, Rational Method, Global Mapper GIS Software.

I. INTRODUCTION

The sharp rise in urban development has led to an increase in impervious areas and a decrease in vegetated surfaces. Traditionally, surface runoff was considered as an undesired water in developed areas which needed to be diverted as complete and as fast as possible from urban areas. In contrary to earlier concepts which considered surface runoff as clean water, the rainwater from impervious areas may be polluted. According to the report by USEPA, 2000 [1], the conventional stormwater management system decreases Grenze ID: 01.GIJET.1.1.12 © Grenze Scientific Society, 2015

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groundwater recharge, increases runoff volume and changes the timing, frequency and rate of discharge. These changes can cause flooding, water quality degradation, stream erosion and the need to construct end of pipe BMPs. In the 1960s, management of stormwater quantity for flood prevention was the only imperative in the developed countries, but in subsequent decades objectives for stormwater management have diversified to include quality, ecosystem health, reuse, integration with urban design etc along with quantity (Refer Fig 1) and has inspired the development of novel stormwater management approaches designed to minimize impervious cover and maximize infiltration of rainfall known as Low Impact Development (LID) in USA and Water Sensitive Urban Design (WSUD) in Australia. These techniques, if implemented at a watershed scale may offer a more sustainable solution to stormwater management.

Fig. 1: Diversification of the Objectives for Stormwater Management [2]

LID is a comprehensive technology-based approach to managing urban stormwater. The LID approach combines a hydrologically functional site design with pollution prevention measures to compensate for land development impacts on hydrology and water quality. Use of these techniques helps to reduce off-site runoff and ensure adequate groundwater recharge [1].

A. Stormwater Management in Indian Context Managing urban stormwater in developing countries poses huge challenges and the consequences of its neglect are severe. Inadequate drainage causes needless death, disease and loss of homes, property and livelihoods. Poor stormwater management also pollutes the environment and squanders limited freshwater resources. India is currently in the early stages of a profound demographic, social and economic transition. The proportion of the population which is urban has doubled over the last thirty years and is now about 30% (India Year Book, 2006). According to Ref. [3], the runoff increases with increase in percentage of impervious surfaces which result due to urbanization. Also, this high runoff volume has a high erosive capacity. This report [3] also points out that sediment yields in areas undergoing suburban development can be as much as 5 to 500 times greater than in rural areas. Reference [4] states that the impervious surface area within a watershed is a very important parameter which decides as to how much will be the quantum of change in runoff. When there are no detention basins to arrest this additional flow and the downpour is excessive the flooding and inundation of low lying urban areas can be catastrophic. Urban areas are characterized by extensive impervious surfaces, damaged soils, and little room for green space or for stormwater management facilities. Urbanization disrupts natural soil profiles, increases impervious surfaces and decreases vegetative cover. These changes increase stormwater runoff at the expense of groundwater recharge, degrading water quality and impairing aquatic habitats. Developing countries suffer due to the growth of the so-called irregular city. The lack of the basic infrastructure necessary to accomplish urban growth in these cities is generally critical. One of the major concerns for these regions is the problem

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of urban floods. Traditional engineering solutions alone cannot solve this problem and channel enlargement measures tend to transfer the problem to downstream reaches. High population densities in urbanized Indian cities are responsible for the water crisis being faced by these cities today. The haphazard and unplanned growth in such cities has led to a critical situation for water. The massive urbanization in India has resulted in generation of huge quantities of stormwater which are unutilized and polluted. Although in the past urban runoff was largely viewed as a nuisance, wi thin the new paradigm of sustainabi lity, t his water is recognized as a potential resource that should be managed accordingly. In India, management of stormwater is either neglected or done using conventional method of providing an engineered drainage system. Stormwater management is not receiving enough attention since India has seasonal monsoon and stormwater becomes important only after a significant failure has taken place. Thus, decision making to determine the preferred ways of sustainable stormwater management in Indian context is becoming more complex. The objective of present work is to study the quantity and quality aspects of stormwater in urbanized cities of India using case study of Pune city. An attempt is made to determine the stormwater quantity in a sub basin of Pune city by rational method using Global Mapper GIS software. It also presents the analysis of stormwater quality in the same sub basin. This data will be subsequently used to identify sustainable practices for management of stormwater in urban centers of India.

B. Pune City: A Case Study Pune city has been selected as a case study for this work. The city has grown tremendously in the last few decades. The current population of the city is 3.6 million and is projected to be 7.7 million in year 2041. As urban centers grow, natural land formations are altered for building and transportation. This results in a multifold increase in 'Paved' area giving rise to up to 3 times increased flow causing nearly 95% runoff [5]. There has been a two fold increase in built up area in less than a decade since 1999 (Refer Table I) [6].

TABLE I: CHANGES IN LAND USE PATTERN IN PUNE [6]

S N

Year Barren Land

Built-up

Fallow Land

Vegetation

Water bodies

Total

1 1999 34.8 23.8 8.33 32.2 0.83 100

2 2008 5.73 49.1 20.82 23.5 0.78 100

If coupled with blocked natural drainage, this increased flow causes flooding. The rainfall pattern in the city has changed over the last few years (higher intensity, lower duration) [5]. The city has been facing the problem of flooding for the last few years. Pune’s groundwater is disappearing fast due to increased use through wells and bore wells. The Environment Status Report (ESR) has warned that such excessive use may severely affect the availability of groundwater and its quality. The report has called for increased water conservation measures to augment the city’s needs. Increased urbanization in the city has resulted in a rising demand for water in the city. The fluctuating amount of rainfall in the past two years in Pune has put additional pressure on the water supply system [5]. Excess built up area has left no open areas for natural percolation, leading to floods each week during monsoon, causing traffic jam & reduced work hours, besides air pollution.

II. MATERIALS & METHODS

A. Stormwater Quality in Kothrud Basin According to Ref. [7], streams are the highest polluted surface water sources as they receive raw sewage. The trends presented in the report indicate that the surface water quality is deteriorating in Pune city. As quality of stormwater is one of the major issues with respect to sustainable stormwater management systems, the water quality in the streams flowing through pune city is required to be analysed. For this, the drainage basin map of pune city (fig. II) was studied. According to this map, the city is divided into 23

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drainage basins from ‘A’ to ‘W’. Out of these 23 basins, the basin ‘B’ (kothrud) was selected for water quality analysis. Figure III shows the drainage map of kothrud basin.

Fig 2: Drainage Basin Map of Pune City [8]

Fig 3: Drainage Map of Kothrud (B) Basin [8]

As can be seen from figure 3, there are 3 major streams flowing through this basin (BN1, BN3 and BN7). Three sampling points were selected at the beginning of each of these streams. Two sampling points were selected on downstream side of stream BN1 and at the confluence of streams BN3 and BN7 near Alankar Police Station. One sampling point was selected near Mhatre bridge where all these streams come together and discharge into the Mutha river. Grab samples were collected at all these 6 sampling locations and were immediately analyzed for Biochemical Oxygen Demand BOD5 (20oC), Chemical Oxygen Demand (COD), Total Solids (TS) and Total Suspended Solids (TSS). The results of analysis are presented in Table II below.

TABLE II: STORMWATER QUALITY IN KOTHRUD BASIN [9]

Sampling Location No. COD (mg/l) BOD5

(mg/l) Total Solids (mg/l) Total Suspended Solids (mg/l)

1 321 122 540 247

2 293 94 490 345

3 196 87 477 269

4 242 109 504 208

5 365 89 594 280

6 263 113 540 239

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It can be concluded from the table above that water quality in all the streams in the kothrud basin is very poor and is comparable to that of dilute to medium strength sewage. Hence, it is extremely essential to take appropriate steps to reduce the pollution level.

B. Determination of Stormwater Quantity in Kothrud Basin In order to determine the suitable LID technique, it is required to determine the quantity of stormwater in kothrud basin. The stormwater quantity was calculated using Rational method. In this method, the runoff is calculated by using the following equation. Q = 10 C i A, where Q is stormwater runoff in m3/hr, C is coefficient of runoff, i is intensity of rainfall in mm/hr and A is the area of drainage district in hectares. The frequency of storm for which the stormwater systems are to be designed depends on the importance of the area to be drained. The suggested frequency of flooding in the different areas is as follows [10]: a) Residential areas

i) Peripheral areas: twice a year ii) Central and comparatively high priced areas: once a year

b) Commercial and high priced areas: once in 2 years. From the Intensity-Duration-Frequency (IDF) relationship for pune, the design intensity of rainfall is 74mm/hr [5]. Table III shows the runoff coefficient C for different types of areas.

TABLE III: RUNOFF COEFFICIENT [10]

Description Runoff Coefficient C

Roads & Pathways 1.0 Residential / Industrial / Commercial, fully paved, high density

0.95

Residential / Industrial / Commercial, largely paved, medium density

0.85

Residential / Industrial / Commercial, moderately paved, low density

0.75

Open ground with bushes, steep slopes 0.5 Open ground / gardens / lawns, low to moderate slopes

0.3

For drainage area determination, Global Mapper GIS software was used. The sub-watershed area was calculated using the following steps.

1) Georeferencing of the map: The kothrud basin map was first georeferenced using the toposheet of Pune area obtained from Survey of India.

2) Digitization of contours: The contours were then digitized on the georeferenced kothrud basin map at 5m contour interval. Refer fig. 4. The contours at 1m interval were then generated using the software.

3) Triangulated Elevation Grid: The triangulated elevation grid was then generated using the elevation data for delineating the watersheds. (fig. 5).

4) Digital Elevation Model (DEM): From the triangulated elevation grid, DEM was generated using the software. Refer fig. 6.

5) Watershed Delineation: The watershed delineation was carried out by the software using the DEM as base data. (fig. 7).

6) These watersheds were generated based on the elevation data. But, while determining runoff by rational formula, the drainage areas have been modified based on elevation data as well as nature of landuse (i.e. percent imperviousness). Hence the sub-watersheds were revised considering the landuse pattern in each. Refer fig. 8.

7) Determination of flowrate: The runoff at various points was then determined using the Rational formula.

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Fig. 4: Contour Digitization

Fig. 5: Triangulated Elevation Grid

Fig. 6: Digital Elevation Model (DEM)

Fig. 7: Watershed Delineation

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Fig. 8: Revised watersheds

For each sub-watershed, area was determined using the software and imperviousness coefficient was determined from the landuse map. Using the rational formula, the discharge at various locations was estimated. From this data, the discharge at sampling locations was determined (Refer Table IV).

TABLE IV: DISCHARGE AT SAMPLING LOCATIONS

Sampling Location No Stream Q in cu.m/sec

1 BN3 8.01

2 BN1 0.7

3 BN7 10.1

4 BN7 89.3

5 BN1 92.4

6 BN1 199.5

The quality and quantity data thus obtained will be helpful to select the appropriate option for sustainable stormwater management.

III. DISCUSSION

A. LID techniques LID techniques have been successfully used in many developed countries, though most of the developing countries including India are still much behind. The primary goal of Low Impact Development methods is to mimic the predevelopment site hydrology by using site design techniques that store, infiltrate, evaporate, and detain runoff. Use of these techniques helps to reduce off-site runoff and ensure adequate groundwater recharge. Major LID techniques which have been tried as demonstration projects, lab models or have been implemented for study purpose, particularly in America and Australia are Bioretention, Permeable Pavements, Swales, Green Roofs / Vegetated Roof tops, etc [11, 12, 13, 14, 15].

B. Constraints in adopting sustainable stormwater management techniques in India The massive urbanization in India has given rise to lot of changes in urban areas. The drivers of change can be: A. Direct (visible physical stresses): land use changes, overuse and pollution. B. Indirect (underlying societal causes): Political (law- policy), Economic, Social, and Technological. The major direct driver is Land use Change. Farmlands, public (government owned) wastelands, hills, riverbanks, ponds etc. in and around cities have been converted into habitation or infrastructure (roads,

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bridges, office premises etc.). This has led to reduced open spaces and interrupted air circulation causing 2-3°C higher temperature than outside the city. Weekly floods during the monsoon, traffic jam, reduced work hours have become a common feature leading to economic loss from 15% to 25%. The main cause is reduced soil surface due to higher built up areas affecting water soaking ability of the city. This enormous increase in impervious area has resulted in generation of huge quantities of stormwater which are unutilized and polluted. Although engineered infrastructure is a necessary component for drainage of urban runoff, nonstructural approaches are important complementary measures, focusing on actions to prevent and mitigate problems related to flooding, as well as those related to pollution and deterioration in environmental health conditions. It is now well established that the traditional practice of urban stormwater management contributes to the degradation of receiving waterways, and it’s value as an alternative water source is being recently recognized. Consequently, this traditional practice is increasingly considered out of touch with the environmental values of society and impedes the broader pursuit of advancing more sustainable urban environments [16, 17, 18]. Selection of an appropriate technique for sustainable stormwater management depends on factors like existing landuse, percent imperviousness, availability of stormwater runoff, slopes, hydrogeology of the area. In Pune, stormwater is being managed in the traditional way by providing stormwater drains. There are 362 km length natural streams in the city which drain the runoff in Mutha river. Out of the 362km length, 51 km of stream lengths are partially obstructed and 15 km fully blocked [5]. It was observed that the existing capacity of these drains is inadequate at many places to accommodate the increasing volume of stormwater. Many roads have no road side drains and during rains, the water overflows on the roads and affects the traffic. In fact, the roads act as free passages for the flow of runoff. This results into localized flooding causing traffic jams and resulting in deterioration of the roads. For adoption of most of the sustainable stormwater techniques, open or pervious area is required. Low availability of open area is a major constraint in adoption of sustainable techniques like retention or detention of runoff. Apart from limited availability of space, the maintenance of these may create further problems in Indian conditions. Thus, detention or retention techniques have a limited scope, particularly in highly urbanized cities. The most suitable option to manage stormwater in such condition is stormwater recharge. Hence, it is proposed to analyze Kothrud drainage basin to determine suitable recharge locations using landuse / land cover, slope, hydrogeological, pre and post-monsoon well water level data and runoff quantity data. Based on potential recharge sites, appropriate LID measures will be suggested taking into account available space, economy and other site specific constraints.

IV. CONCLUSION

It can be observed that GIS technique can be effectively used to determine the runoff from the selected catchment. In this work, Global Mapper GIS was used to delineate the sub-watersheds in the selected catchment, to determine the slope and other characteristics of the selected catchment and to determine the area of the sub-watersheds. Further, Rational method was used to calculate the runoff quantity at various points and then finally at the sampling locations. Thus, use of GIS software has reduced the time and effort required for runoff determination. This runoff quantity data will be subsequently used in identifying suitable sustainable techniques for managing stormwater in Indian conditions. Also, from the stormwater quality analysis, it can be concluded that the stormwater is highly polluted. Hence, the stormwater needs to be managed in a sustainable way. As is evident from the literature, LID and/or WSUD techniques have been successfully used for sustainable stormwater management in developed countries. In developing countries like India, stormwater is being managed in the traditional way by providing stormwater drains. Managing the stormwater sustainably is an effective way of maintaining the health of water resources and aquatic ecosystems as well as meeting the human needs of water by minimizing the impacts of urban development. Thus, there is a need to consider sustainable options for managing the stormwater in India. Limited availability of open space and the inherent maintenance problems inhibit the adoption of retention or detention techniques in India. Such problems in the adoption of sustainable stormwater systems in developing countries can be alleviated to some extent by providing techniques promoting artificial recharge of groundwater. It is proposed to identify suitable sites for stormwater recharge in the selected basin.

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REFERENCES

[1] USEPA (2000), “Low Impact Development (LID) A Literature Review.” [2] Roy, A. H., Wenger, S. J., Fletcher, T. D., Walsh, C. J., Ladson, A. R., Shuster, W. D., Thurston, H. W., Brown, R.

R. (2008), “Impediments and Solutions to Sustainable, Watershed-Scale Urban Stormwater Management: Lessons from Australia and the United States.” Environmental Management, 42, 344–359.

[3] National Institute of Hydrology (2001). “Urban Hydrology A State of The Art Report.” [4] Fact finding committee Report (2006), “Final Report on Mumbai Floods.” Govt. of Maharashtra. [5] Oak Ajit (2010), “Drainage Plan for Pune City.” Primove Consultants Pvt. Ltd. Pune. [6] Desai C.G., Patil M.B., Mahale V.D. and Umrikar B. (2009), “Application of remote sensing and geographic

information system to study land use / land cover changes: a case study of Pune Metropolis.” Advances in Computational Research, vol. 1(2), 10-13.

[7] PMC (2010), “Environment Status Report.” Pune Municipal Corporation. [8] Pune Municipal Corporation Official Website (2012). http://www.punecorporation.org/pmcwebn/ Storm_

Water.aspx Accessed July, 2012. [9] Gogate, N G. Rawal P M. (2012), ‘Sustainable Stormwater Management in Developing and Developed Countries: A

Review’. Proc. of Int. Conf. on Advances in Design and Construction of Structures 2012. [10] Central Public Health and Environmental Engineering Organization (2012), ‘Manual On Sewerage And Sewage

Treatment’. [11] Davis, Allen P. and Minami, Christie. 1999. Evaluation of Pollution Removal Characteristics at Bioretention

Facilities At Peppercorn Place. Project No. 01-4- 33173. University of Maryland, College Park, Department of Civil Engineering.

[12] Booth, Derek B., Leavitt, Jennifer and Peterson, Kim. 1996. The University of Washington Permeable Pavement Demonstration Project, Background and First Year Field Results. Center for Urban Water Resources Management, Department of Civil Engineering.

[13] Kuo, Jan-Tai, Yu, Shaw L., Fassman, Elizabeth and Pan, Henry. 1999. Field Test of Grassed Swale Performance in Removing Runoff Pollution. Paper Presented at the 19999 26th Annual Water Resources Planning and Management Conference (ASCE), Published in Conference Proceedings.

[14] Miller, Charlie. (1998). Vegetated Roof Covers, A New Method for Controlling runoff in Urbanized areas. Proceedings from the 1998 Pennsylvania Stormwater Management Symposium, Villanova University.

[15] Alfredo, K. Montalto, F. Goldstein, A. 2010. Observed and Modeled Performances of Prototype Green Roof Test Plots Subjected to Simulated Low- and High-Intensity Precipitations in a Laboratory Experiment. Journal of Hydrologic Engineering, Vol. 15, No. 6, pp 444-457.

[16] Thomas, J. F., Gomboso, J., Oliver, J. E., Ritchie, V. A. (1997). Wastewater re-use, stormwater management and the national water reform agenda. (In Report to the Sustainable Land and Water Resources Management Committee and to the Council of Australian Governments National Water Reform Task Force: Background positions paper 1, CSIRO, Land and Water, Canberra.)

[17] Newman, P., Kenworthy, J. (1999). Sustainability and cities: Overcoming automobile dependence. Island Press, Washington, D.C.

[18] Wong, T. H. F., Eadie, M. L. (2000). Water sensitive urban design—A paradigm shift in urban design. (Paper in CD ROM presented at The International Water Resources Association for the Xth World Water Congress, Melbourne.

A Novel and Efficient Method for Denoising and

Compression of MR Images for Telemedicine Applications

Ananda Resmi S1, Ajith A2

1Deparment of Electronics and Communication Engineering, College of Engineering Pathanapuram, Kollam, Kerala, India, email: anandaresmi@gmail.com

2Deparment of Electronics and Communication Engineering, College of Engineering Perumon, Kollam, Kerala, India, email: aloysius.ajith@gmail.com

Abstract— The presence of Rician noise is the major drawback of MR images for data storage, transmission and analysis for medical applications especially for diagnostic applications at remote locations. This work demonstrates an efficient method for removing the Rician noise and compression of MR image for data storage and transmission applications by preserving useful details. The method demonstrates a fast algorithm based on non local means and DCT based compression scheme for effective storage and transmission applications. This method was tested for 20 sets of MRI data for different noise level and its Peak signal to noise ratio (PSNR) value found acceptable for further applications. This algorithm was effectively degraded the presence of Rician noise which reduced the number of computations and thus by minimising the computational complexity and time of the system. The performance of the method is evaluated and compared by means of mean square error and Peak Signal to Noise Ratio of existing algorithm and it is observed that these parameters were outperformed with respect to existing algorithm which is acceptable for further analysis of MRI Image. Index Terms— Rician Noise, Image denoising, Image compression, Fast Non local means, DCT, Magnetic resonance image.

I. INTRODUCTION

The main purpose of telemedicine technology is to enhance health care delivery to a wider population, which provides transfer of pathological and imaging reports of patients across the telemedicine networks, so as to provide consultation by expert from distant locations. This application is very efficient since patient records, stored electronically, can be made available through the internet for consultation, diagnosis, treatment, education, training, monitoring etc resulting in the elimination of the need for physical storage and transfer of records [1]. The medical images which are transmitting across telemedicine network to remote medical centres for multipurpose application have to be pre-processed for eliminating noise present in the images and effective loss-less compression algorithms are necessary for saving storage space and better utilization of bandwidth to increase speed of data transmission[2,3]. Hence the existing image compression algorithms and noise cancellation methods have to be analyzed over several parameters and its constraints. Magnetic resonance imaging (MRI) is a very effective medical imaging technique for examination of the soft Grenze ID: 01.GIJET.1.1.13 © Grenze Scientific Society, 2015

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tissues in the body (such as brain). In this imaging technique, magnetic field in-homogeneities cause distortions in images that are reconstructed by conventional fast Fourier transform (FFT) methods. Since the FFT is a unitary transform, the white Gaussian noise on the measured quadrature signals is converted into white Gaussian noise on the two orthogonal R-space signals. The magnitude of this complex signal corrupted by Gaussian noise then exhibits Rician distributed noise [3]. There exist some techniques that are adapted to eliminate Rician noise. It has been shown that Rician noise is approximated very well by Gaussian noise in the case of high SNR (bright regions) [4]. Several non-iterative image reconstruction methods are used currently to compensate for field in-homogeneities, but these methods assume that the field map that characterizes the off-resonance frequencies is spatially smooth [5]. Particularly, in medical imaging, denoising is challenging because quality of image should be increased, that is measured in terms of signal to noise ratio (SNR) must be high. As an image pre processing procedure, noise removal has been extensively studied and many denoising schemes have been proposed, from the earlier smoothing filters and frequency domain denoising methods to the lately developed wavelet using correlation [6,7], curvelet, and ridgelet based methods, shape adaptive transform [8], bilateral filtering, Non local means (NLM) based methods, Linear minimum mean square error (LMMSE) estimator [9] and more recently proposed nonlinear variational methods like the total variation minimization [10] Medical image data which is to be used for diagnostic applications should have high SNR so the compression mechanism involved should not be lossy [11]. This is partially due to legal reasons (depending on the corresponding country’s laws) and partially due to the fear of misdiagnosis because of lost data in the compression procedure [1]. A possible solution to this problem is to use selective compression where parts of the image that contain crucial information (e.g. micro calcifications in mammograms) are compressed in a lossless way whereas regions containing unimportant information are compressed in a lossy manner [12]. In any case, we will restrict the discussion to lossless data formats [2]. A number of methods are available in literature. Transform coding is a widely used method of compressing medical images. 2-D images from the spatial domain are mapped to the frequency domain and concentrates vital information into few transform coefficients. Examples of such a transform operation are cosine transform [13] and wavelet transform [13, 14]. The existing medical image compression techniques discussed so far have not presenting any techniques for effectively removing the noise present in the image without affecting quality of the image. This work gives a novel method for Rician noise elimination and compression technique using modified non local means algorithm and discrete cosine transform (DCT). This paper is organized as follows. The Method and material used for this work is discussed is discussed in section II, Section III details the results obtained in this work and a discussion of results followed by conclusion of the work.

II. METHODS AND MATERIALS

The basic block diagram of entire procedure is shown in fig.1. The method consists of two phases. The first phase is acquisition of MR image data and denoising of this image data. Second phase is compression of denoised MRI data which is in the DICOM format using DCT compression. The performance of the method is evaluated by means of computing SNR on decompressed images for different noise levels of the input image.

A. Image Acquisition and Denoising

MRI images were collected from the Department of Radiology, Sree Chitra Institute of Medical Sciences and Technology (SCIMST) and Regional Cancer Centre, Thiruvananthapuram, Kerala, India. The images were gray scale images. Axial slices of T1 weighted post contrast brain MRI data were considered in this work. Image denoising and compression was done on 20 data sets with each set contains 20 slices. The images acquired contain Rician noise which has to be removed by retaining content of the image. Pre processing steps involved before compression are not sufficient for removing the noise. The method used here is modified method of non local means algorithm. Non Local (NL) means algorithm is based on the natural redundancy of information in images to remove noise. At the pixel i, the non local means denoised pixel,푣(횤) is the simply the weighted average of all of the pixels within the noisy image as per eqn. (1).

55

푣(횤) = ∑ 푤(푖, 푗)푣(푗)(1)

where the weights w(i, j) depend upon the similarity between the pixels i and j and must satisfy the conditions 0≤w(i, j)≤1 and ∑ 푤(푖, 푗) = 1. Note that each pixel i of the image has its own independent weights of the other j pixels within the image. To quantify the similarity between the pixels i and j, a neighbourhood or window, Ni, around the pixel of interest is defined to allow information about local structures and textures to be incorporated. The similarity between the pixels i and j is then computed using a Gaussian weighted Euclidean distance, D(i, j), between the neighbourhood around the pixel i, v(Ni), and the neighbourhood around the pixel j, v(Nj),in eqn. (2).

퐷 (푖, 푗) = 푣(푁 ) −푣(푁 ),

= ∑ [퐺 (푙)(푣 푁 (푙) − (푣(푁 (푙)))] (2)

Here the operator ‖. ‖ , denotes the squared Gaussian weighted Euclidean distance D2 (i, j), Ga represents the Gaussian kernel with standard deviation a, and l represents one of the total nl elements within a neighbourhood. For a two dimensional image, the Gaussian kernel, Ga, can be defined by eqn. (2),

퐺 (푥, 푦) = exp −(푥 − 푥 ) + (푦 − 푦 )

2푎 (3)

where xo and yo denote the center of the Gaussian kernel with x and y corresponding to the coordinates of the element l in eqn (2).Given the Gaussian weighted Euclidean distance, D(i, j), between the pixels i and j, the weights w(i,j) are computed according to eqn.(4)

푤(푖, 푗) =1푍(푖)

exp−퐷 (푖, 푗)

ℎ(4)

where Z(i) is the normalizing factor defined by eqn. (5) to ensure∑ 푤(푖, 푗) = 1.

푍(푖) = exp(−퐷 (푖, 푗)

ℎ )(5)

The parameter h is a constant which controls the decay of the exponential function as a function of the euclidean distance [14]

Fig.1 Block diagram of the method

Rician noise added MR image

Denoising using Fast Non Local Means

Compression based on DCT

Image storage and Transmission

Image Restoration

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The main disadvantage of the NL-means algorithm is the computational complexity and its increased computation time. In this work, a modified method of NL algorithm is used to reduce computation time and improve the performance of the method. Weight evaluation using an exponential function is still a time consuming task. To reduce the amount of these evaluations a lookup table can be used for the weight calculations in eqn (4). Since the bandwidth parameter h is constant, the weights can be calculated in advance [15]. An improvement of image quality towards the original algorithm is to ignore the contributions from dissimilar windows. Using a pre-classification technique, only weights for the most meaningful pixels are computed. This pre-classification technique is based on the similarity of the mean and the gradient, similar neighbourhoods tend to have close means and close gradients [15, 16]. This technique is a fast way to exclude dissimilar windows, which eventually results in a smaller computation time and even in a better overall denoising quality. The gradient is sensitive to noise level, so the standard deviation is preferable in case of high level of noise. In this way, the local means and local standard deviations are pre-computed in order to avoid repetitive calculations of moments for one same neighbourhood [16].

B. Compression of denoised DICOM Image The denoised MR image data in DICOM format is compressed using DCT based compression standard. In JPEG compression, subdivide the image into sub-blocks of size 8x8. It is then processed from left to right and top to bottom and 2D- DCT is computed for this block [17, 18]. The resulting coefficients are then quantized in accordance with the transform normalization array. After each block’s DCT coefficients are quantized, the elements of the resulting array are recorded in accordance with the zigzag pattern and entropy coding (EC) is performed using Huffman coding [17]. Compressed image could be retrieved using reverse process of compression.

C. Performance Evaluation There are some quality measures which allow comparing compression algorithm performances. Two error metrics are generally used. Compressed image could be retrieved using reverse process of compression. In medical domain, details loss may cause a loss of useful clinical information leading in some cases to a possible erroneous diagnosis. According to American College of Radiology [12], clinically significant diagnostic information must not be lost during compression process. Thus, finding an acceptable distortion level is a great challenge which is according to [9] dependant on the kind of medical imaging modality used, coding algorithm, image acquisition protocol, explored organ, and pathology. The performance of the denoised and compressed image is measured in terms of mean square error (MSE), Peak signal to noise ratio (PSNR) and its compression ratio. Mean Square Error (MSE):The MSE is the cumulative squared error between the compressed and the original image [3]. This parameter essentially captures the error that has occurred as a result of compressing an image in a lossy manner. Where I(x, y) is the original image , Ĭ(x, y) is the decompressed image.

푀푆퐸 =1푀푁 퐼(푥, 푦)− 퐼(푥,푦) (6)

Peak Signal to Noise Ratio: PSNR is a measure of the peak error [18]. PSNR measure the compression efficiency because it is proportional to the quality. PSNR is expressed in decibels. It relates to the mathematical similarity of two images.

푃푆푁푅 = 20푙표푔255푀푆퐸

(7)

III. RESULTS AND DISCUSSIONS

The method was implemented on 20 sets of T1 weighted MRI data. Fig. 2 shows example of a denoised MR image using fast non local means algorithm. The usefulness of the algorithm was tested by adding different levels of Rician noise on same image and repeated for every slice in each dataset.

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(a) (b) (c)

Figure.2 shows example for denoising of rician noise added image using fast non local means algorithm for a noise level of 20 db (a) Original image (b) Rician noise added image (c) Denoised image

Performance of the method was also compared with respect to non local means algorithm. It was observed that, time required Fast NLM is very low compared to existing methods such as Non-Local means. Time required fast non local means is around 8.418seconds and for NLM is 978.04 Seconds. Denoised MR images were compressed for storage and transmission applications. DCT based compression standard is used here which can eliminate high frequency noise that is channel noise. Using this, a compression ratio of 16 is obtained. Fig. 3 shows the example for compressing a denoised image. Computation time required for NL method and FNLM method, computation time required for compression without denoising and compression after denoising using FNL method are included in table I.

(a) (b) (c)

Figure.3 shows different levels of compression (a) denoised image for compression (b) compressed and encoded image ( c) decompressed image

TABLE I. SHOWS COMPARATIVE STUDY ON COMPUTATION TIME FOR EACH METHOD

METHOD Time Required (Seconds) Non Local Means 978.042559

Fast Non Local Means 8.418

DCT Compression 2.0419

Denoising (FNLM) and Compression 11.0203

In order to check the robustness of the algorithm, rician noise levels added in the image were varied from 5db to 35db and the corresponding PSNR is measured. Fig.4 shows the graphical plot for Noise level Vs. PSNR. From this graph it can be well observed that this method is very useful for storage and telemedicine applications because PSNR varies from 73 dB to 45dB, medical images having these PSNR values can be used for medical applications.

IV. CONCLUSION

A novel and robust method for denoising and compression of Rician noise added MR image was developed by combining fast Non local means algorithm and DCT based compression technique. The computation time of this method was compared with respect to existing fast non local means algorithm. The novelty of this method is that it is very faster than the existing methods. Using this algorithm, a compression ratio of 16 and a maximum PSNR of 80 db is obtained. The robustness of the method was also tested by varying the noise levels added in the image and proved that this method very effective for storage and telemedicine applications.

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Figure.4 shows the graphical plot of level of rician noise added and PSNR of decompressed image

REFERENCES

[1] Janet, Divya Mohandass and S.Meenalosini,. (2011).’ Lossless Compression Techniques for Medical Images in Telemedicine’, Advances in Telemedicine: Technologies, Enabling Factors and Scenarios, Prof. Georgi Graschew (Ed.), InTech, publications 2011,

[2] Norcen, R. Podesser, M. Pommera, A. Schmidt, H. P. Uhl, A., ‘Confidential storage and transmission of medical image data’, Computers in Biology and Medicine , 2003, 33, pp. 277–292

[3] Saleha, M. Sharif, M. Yasmin, M. Raza, M.and Sajjad, M. ‘Brain Image Compression: A Brief Survey’, ‘Research Journal of Applied Sciences, Engineering and Technology’, 2013 5(1):pp 49-59.

[4] Bradley, P. S , Douglas, C. N. Jeffrey, A. F. Fast, Iterative Image Reconstruction for MRI in the Presence of Field In homogeneities, IEEE Transactions on Medical Imaging, 2003, 22(2),pp.195-213

[5] Erdogmus, D. Erik, G. L, Rui, Y. Jose, C. P., Fitzsimmons, J. R. ‘ Measuring the signal-to-noise ratio in magnetic resonance imaging: a caveat’ , ‘Signal Processing’ 2004, 84 pp.1035 – 1040

[6] Aelterman, J. Goossens, B. Pizurica, A. and Philips, W. ‘Removal of Correlated Rician Noise in Magnetic Resonance Imaging’, 16th European Signal Processing Conference (EUSIPCO 2008), Lausanne, Switzerland, August 25-29, 2008

[7] Lu, K. He, N. and Li, L.’ Non local Means-Based Denoising for Medical Images’, ‘Computational and Mathematical Methods in Medicine, Volume, 2012, 7 pp.

[8] Santiago, A.F. Carlos A.L., and Carl, F. W. ‘Noise and Signal Estimation in Magnitude MRI and Rician Distributed Images: A LMMSE Approach’, ‘IEEE Transactions on Image Processing’, 2008, 17(8), pp.1383-1398

[9] Nowak, R. D. ‘Wavelet based Rician noise removal for Magnetic Resonance Imaging’, IEEE Transactions on Image Processing, 1998,

[10] Raghuvanshi, D. Jain, D.Pankaj J., ‘Performance Analysis of Non Local Means Algorithm for Denoising of Digital Images’, ‘International Journal of Advanced Research in Computer Science and Software Engineering’, 2013, 3(1),

[11] Anuja, P. P. Manisha, G. ‘DCT and DWT in Medical image Compression’, ‘International Journal on Advanced Computer Theory and Engineering (IJACTE)’, 2013, 2(3), pp.2319 – 2526 .

[12] Monika S., Sonika A., Mangal S.,’Image Compression Using Wavelet Family on Biomedical Application (ultra sound)’, International Journal of Advanced Research in Computer Science and Software Engineering, 2013, 3( 8), pp.946-950

[13] Zukoski, M. J. Terrance, B. Tunç I.’ A novel approach to medical image compression’, Int.J.Bioinformatics Research and Applications, 2006, 2(1), pp 89-103

[14] David, B., Sacchi, M. Non-Local Means Denoising of Seismic Data, Geo Convention: Vision2012 [15] Dauwe, A. Goossens, B. Luong, H.Q. and Philips, W. ‘A Fast Non-Local Image Denoising Algorithm’, ‘Proc. of

SPIE-IS&T Electronic Imaging’, SPIE Vol. 6812, 2008 [16] Pierrick,C.,Pierre,Y. Christian B. Fast Non Local Means Denoising for 3D MR Images: Lecture Notes in Computer

Science, volume 4191, 2006,pp.36-40. [17] NageswaraRao,T., Srinivasa, K. Devi, R., Image Compression using Discrete Cosine Transform: Georgian

Electronic Scientific Journal: Computer Science and Telecommunications, No.3(17), 2008 [18] AnandaResm,i S.,TessammaT. Automatic Segmentation of Brain MRIs using morphological methods; Department

of Electronics, Cochin University of Science and Technology.Proceedings of International Conference on Modelling and Simulation (MS09) India 1-3 Dec 2009

5 10 15 20 25 30 35 40 45 500

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20

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40

50

60

70

80

90

100

Noise level in dBP

SN

R in

dB

Voltage Improvement in Wind Farm using

STATCOM with NSVFF Control

Rijo Rajan1, Reji P2 1 Govt. Engineering College/Electrical, Thrissur, India

Email: rijoelectrical@gmail.com 2 Govt. Engineering College/Electrical, Thrissur, India

Email: rejip@gmail.com

Abstract— Power generation from renewable energy source, the wind has grown tremendously and its growth potential is still significant. Unlike conventional sources, due to the unpredictable nature of wind and due to various aerodynamic aspects, the active power generated by wind turbines fluctuates. The power variation causes stability issues because of the fluctuation of the voltage at the point of connection of wind farm. Therefore, power quality issues especially; voltage sag is the major limiting factors for connecting wind farm into power grid, mainly the wind farm with fixed-speed induction generators. This paper investigates the use of a static synchronous compensator (STATCOM) to mitigate the sustained voltage sag of wind farm with fixed speed induction generators. A control strategy which combines negative-sequence voltage feed-forward (NSVFF) control is used to mitigate voltage fluctuation of wind farm. The simulation results show that the STATCOM significantly improves the power quality of wind farm integrated to grid.

Index Terms— Power quality, STATCOM, wind farm, Induction Generator

I. INTRODUCTION

The main problem regarding wind power systems is the major discrepancy between the irregular character of the primary source (wind speed is a random, strongly non-stationary process, with turbulence and extreme variations). The active power generated by wind turbines fluctuates due to the aerodynamic aspects. The power variation can cause fluctuation of the voltage at point of connection of wind farm. Therefore, power quality issues (sustained voltage sag) are the major limiting factors for connecting wind farm into power grid, especially the wind farm with fixed-speed induction generators. Voltage collapse is associated with the reactive power demands of loads not being met because of limitations on the production and transmission of reactive power. Limitations on the production of reactive power usually include generator and FACTS devices reactive power limits and the reduced reactive power produced by capacitors at low voltage levels, etc. This paper prescribes a new power injection model of STATCOM for voltage stability.

II. POWER EXTRACTED FROM WIND

The horizontal axis approach currently dominates wind turbine applications. A horizontal axis wind turbine consists of a tower and a nacelle that is mounted on the top of the tower. The nacelle contains the generator, Grenze ID: 01.GIJET.1.1.19 © Grenze Scientific Society, 2015

Grenze Int. J. of Engineering and Technology, Vol. 1, No. 1, January 2015

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gearbox and the rotor. Different mechanisms exist to point the nacelle towards the wind direction or to move the nacelle out of the wind in the case of high wind speeds. On small turbines, the rotor and the nacelle are oriented into the wind with a tail vane. On large turbines, the nacelle with the rotor is electrically yawed into or out of the wind, in response to a signal from a wind vane. Horizontal axis wind turbines typically use a different number of blades, depending on the purpose of the wind turbine. Two-bladed or three-bladed turbines are usually used for electricity power generation. Turbines with 20 or more blades are used for mechanical water pumping. The number of rotor blades is indirectly linked to the tip speed ratio, 휆, which is the ratio of the blade tip speed and the wind speed:

R

(1)

Where 휔 is the frequency of rotation, R is the radius of the aerodynamic rotor and υ is the wind speed [1]. Currently, three-bladed wind turbines dominate the market for grid-connected, horizontal axis wind turbines. Three-bladed wind turbines have the advantage that the rotor moment of inertia is easier to understand and therefore often better to handle than the rotor moment of inertia of a two-bladed turbine. Furthermore, three-bladed wind turbines are often attributed ‘better’ visual aesthetics and a lower noise level than two-bladed wind turbines. The power of an air mass that flows at speed υ through an area A can be calculated as follows: Power in wind.

31

2wP A (2)

Where A is intercepting area in m2, 휌 is air density in kg/m3 and υ is wind speed in m/s. The power in the wind is converted into the mechanical–rotational energy of the wind turbine rotor, which results in a reduced speed in the air mass. The power in the wind cannot be extracted completely by a wind turbine, as the air mass would be stopped completely in the intercepting rotor area. This would cause a ‘congestion’ of the cross-sectional area for the following air masses. The theoretical optimum for utilizing the power in the wind by reducing its velocity was first discovered by Betz. According to Betz, the theoretical maximum power that can be extracted from the wind is

312w P B e t zP A C 31 0 . 5 9 (3 )

2A

III. VOLTAGE STABILITY ISSUES OF WIND FARM

The influence of connecting a wind farm on the gird voltage is directly related to the short circuit power level. The short circuit power level in a given point in the electrical network represents the system strength. If the voltage at a remote point can be taken as constant, VS and the short circuit power level SSC in MVA is defined as 푉 /푍 where ZK is the equivalent impedance between the points concerned.

Fig.1 simple systems with an equivalent wind power generator connected to a network.

Fig.1 Illustrates an equivalent wind power generation unit, connected to a network with equivalent short circuit impedance ZK. The network voltage at the assumed infinite bus bar and the voltage at the Point of Common Coupling (PCC) are Vg and VS, respectively [2]. The output power and reactive power of the generation unit are Pg and Qg, which corresponds to a current Ig.

*g

gg

SI

V

(4)

61

g gg

g

P j QI

V

(5)

k g k g k g k g

g g

R P X Q X P R QV j

V V

(6)

The voltage difference ΔV, between the system and the connection point is given in eqn. 6.

p qV V j V (7)

The voltage difference ΔV is related to the short circuit impedance, the real and reactive power output of the wind power generation unit. It is clear that the variations of the generated power will result in the variations of the voltage at PCC. If the impedance ZK is small then the voltage variations will be small (the grid is strong). On the other hand, if ZK is large, then the voltage variations will be large (the grid is weak). However, strong or weak are relative concepts. For a given wind power capacity P the ratio RSC = SSC / P is a measure of the strength. The voltage at PCC should be maintained within utility regulatory limits. Operation of wind turbines may affect the voltage in the connected network. If necessary, the appropriate methods should be taken to ensure that the wind turbine installation does not bring the magnitude of the voltage outside the required limits.

IV. VOLTAGE FLUCTUATION MITIGATION

For the power system in Fig.2, the voltage at the sending end of the power line Vs, can be approximately calculated as:

1 12

2s

PR QXV V

V

(8)

Where P and Q are the active and reactive power flow on the line, respectively; V2 is the voltage at the receiving end of the power line. Since the voltage V2 is constant but the generated active power by the wind farm is varying due to the variation of the wind speed, the voltage Vs fluctuates when the reactive power is relatively constant. However, by quickly varying the reactive power Q using fast and smooth dynamic reactive compensation from the STATCOM, the fluctuation of the voltage Vs can be mitigated [3] [4].

Fig.2 Single line diagram of wind farm with STATCOM

V. STATCOM

The objective of the STATCOM is to provide fast and smooth voltage regulation at the point of common coupling (PCC). The STATCOM is made up of a shunt transformer, a VSC, a dc capacitor, a magnetic circuit, and a controller. If there is no energy storage device coupled to the dc link and the losses are neglected, neither shunt converter is capable of absorbing or generating real power so that only operating in the reactive domain is possible. The reactive power exchange of STATCOM with the ac system is controlled by regulating the output voltage amplitude of VSC. If the amplitude is increased above that of the ac system,

62

the current flows through the shunt transformer from the STATCOM to the ac system, and the device generates reactive power (capacitive) [5]. If the amplitude is decreased to a level below that of the ac system, then the current flows from the ac system to STATCOM. The capacitor is used to maintain dc voltage to the VSC, which itself keeps the capacitor charged to the required levels. Thus, by controlling the VSC output voltage lead or lag with respect to the ac system voltage, the capacitor dc voltage can be decreased or increased, respectively, to control the reactive power output of the device [6]. When the VSC voltage leads the bus voltage, the capacitor supplies active power to the system, reducing its voltage; on the other hand, when the VSC voltage lags the bus voltage, the capacitor is charged by consuming active power from the system [7] [8] [9].

VI. CONTROL STRATEGY FOR STATCOM

Negative-sequence voltage feed-forward control is formulated with DSRF PLL to detect the PCC voltage unbalance components. PCC voltage can be used to determine positive-sequence and negative-sequence components. DSRF is composed of two rotating reference axes; one is rotating in anti-clock wise direction and other in clock wise direction. Reference axis rotating in anti-clock wise direction is dq+1 frame and its angular position is 휃′and axis rotating in clock wise is dq-1 frame and its angular position is -휃′. Using Parks transformation the PCC voltage is transformed from abc reference frame to anti-clock wise and clock wise rotating reference frame. The matrix expression given in Eqn.9 and 10 is obtained when 휃 ≈ 휔푡 + ∅ .

1

1

' '1 1 1 1

1 ' '

1 cos(2 ) s (2 )cos sin 2

sin(2 ) cos(2 )sd P N N

S S Ssq

V inV V VV t

(9)

1

1

' '

' '

cos(2 ) cos(2 )sin(2 ) sin(2 )

sd P NS S

sq

VV VV

(10)

Positive-sequence and negative-sequence voltage amplitude are V and V respectively. The initial phase angle of positive-sequence and negative-sequence voltage are ∅ and ∅ respectively. Since both axes are rotating in opposite direction, the oscillating frequency 2ω corresponding to the coupling between axes. A decoupling calculation is described in Eqn.11 and 12 to cancel the oscillations.

111 1

11

* ' '

* ' '

cos(2 ) sin(2 )sin(2 ) cos(2 )

sdsdsd sq

sqsq

VVV VVV

(11)

111

11

* '

* '

cos(2 )sin(2 )

sdsdsd

sqsq

VVVVV

(12)

The structure model of the DSRF PLL can formulated form Eqn.11 and 12 and the structure is shown in Fig.3. Decoupling computation is used to ascertain the positive and negative sequence components of the unbalanced PCC voltage. Positive and negative fundamental component of the PCC voltage can be detected using The Doubly Synchronous Revolving reference Frame (DSRF) PLL method [10]. The complete control strategy consists of PWM control and the Negative Sequence Voltage Feed-Forward control. The structure of NSVFF control is shown in Fig.4.

Fig.3 Structure model of the DSRF PLL

63

Fig.4 Block diagram of the NSVFF control scheme

VII. PERFORMANCE ANALYSIS OF WIND FARM UNDER UNSYMMETRICAL FAULT

To investigate the effect of the STATCOM with NSVFF control on power quality issues of the WTGs, an unsymmetrical fault is applied at the 575V bus and the fault is cleared after 0.5s. Fig.5 shows the response of the PCC voltage without STATCOM. Without any reactive power support the system voltage drops to 0.65pu even after clearing the fault. Fig.6 shows voltage and current response of wind farm at PCC with STATCOM using NSVFF control. The PCC voltage is stabilized at 0.99pu when wind farm is supported by STATCOM using Negative Sequence Voltage Feed Forward Control (NSVFF). Voltage instability of wind farm is caused by fatal over speeding of the WTGs during fault. As a result, the wind farm has to be disconnected from the power grid. However, when using the dynamic reactive compensation device STATCOM, the voltage instability is prevented and the WTGs successfully ride through the grid fault and remain in service. Fig.7 shows the reactive power demand of wind farm during fault. During unsymmetrical fault the reactive power demand is increased to 17MVAr. Due to the heavy reactive power demand the voltage at PCC decreases. Since wind farm is supported by STATCOM the reactive power demand is reduced to 2.2MVAr. Therefore, the STATCOM mitigated the power quality issue of wind farm at PCC by injecting reactive power. Fig.8 shows reactive power generated by the STATCOM with NSVFF control.

Fig.5 Variation of voltage at PCC without STATCOM

Fig.6 Variation of voltage at PCC with STATCOM

Fig.7 Variation of reactive power demand of wind farm at

PCC

Fig.8 Variation of reactive power generated by STATCOM

VIII. PERFORMANCE ANALYSIS OF WIND FARM UNDER SYMMETRICAL FAULT

The effect of STATCOM with NSVFF control on wind farm during symmetrical fault is analysed on the simultion model. A symmetrical fault is considered to occur in the 575V bus at 1.0 sec and the fault is cleared after 0.5 sec. Fig.9 shows the response of the wind farm at PCC under symmetrical fault without STATCOM. Wind farm voltage level is reduced to 0.4pu during the fault and the voltage at the bus after clearing the fault is 0.64pu. Since the reactive power demand of the wind farm is increased the system could not back to stable voltage limit even after clearing the symmetrical fault. Fig.10 shows voltage response of the wind farm at PCC with STATCOM using NSVFF control. The PCC voltage is stabilized at 0.98pu, this is due to reactive power support from STATCOM. Fig. 11 shows the reactive power demand of wind farm at PCC, during fault state the demand incereased to 14.6MVar and the demand sustaine in that magnitude if wind farm is not supported with STATCOM. Wind farm with out STATCOM, voltage at PCC even after clearing the fault is 0.64pu. As wind farm is supported by STATCOM, the Voltage at PCC back to prefault limit of 1pu after clearing the fault. Fig.12 shows variation of reactive power injected by STATCOM at PCC. The reactive power injected by STATCOM is 2.6MVar during symmetrical fault. During the fault, the wind generator accelerates, since it is no longer able to generate enough electromagnetic torque to balance the torque coming from wind turbine. When the fault is cleared, Without STATCOM, the generator is not able to produce enough braking torque to bring the speed and the PCC voltage back to their pre-fault values. As a result, the wind farm has to be disconnected from the power grid. However, when using STATCOM for reactive compensation, the PCC voltages and the SCIG rotor speed recover to their pre-fault nominal values, and the wind farm remains connected to the grid. Therefore, STATCOM enhances transient stability of wind energy sytem when it experience symmetrical fault and the low voltage ride-through capability of wind farm.

Fig.9 Variation of voltage at PCC without STATCOM

Fig.10 Variation of voltage at PCC without STATCOM

64

Fig.11 Reactive power demand of wind farm at PCC

Fig.12 Reactive power generated by STATCOM

Table I shows PCC voltage in pu of wind farm without STATCOM and with STATCOM using NSVFF control. Power quality like sustained voltage sag is a main issue related with wind farm during symmetrical and unsymmetrical faults. Results show that STATCOM with NSVFF control improves voltage stability of wind farm at PCC.

TABLE I PCC VOLTAGE IN PU DURING FAULT CONDITIONS

Fault Condition

without

STATCOM

With STATCOM (NSVFF control)

Unsymmetrical fault 0.65 0.99

Symmetrical fault 0.64 0.98

IX. CONCLUSION

The voltage instability of wind farm at PCC during unsymmetrical fault and symmetrical fault are the major concern for ensuring the system stability. The effect of the faults remains even after clearing the abnormality issues and this voltage instability issues limits the wind farm integrating with the grid. This paper examines the use of STATCOM to mitigate the voltage fluctuations of wind farm at PCC during unsymmetrical and symmetrical fault conditions and improve the voltage stability at the PCC. STATCOM with negative sequence voltage feed forward scheme and PWM control is employed to stabilize the voltage of wind farm at PCC during unsymmetrical and symmetrical conditions. Doubly synchronous revolving frame theory is used to obtain the positive-sequence and negative-sequence components of the voltages at PCC during abnormal conditions. MATLAB/SIMULINK environment is used to model the simulation which contains wind farm with fixed-speed wind turbines, STATCOM and power grid. The simulation results shows that sustained voltage sag of grid integrated wind farm at PCC during symmetrical and unsymmetrical fault conditions is subdued and there by improved the PCC voltage stability.

REFERENCES

[1] Larsson, Ake (2002) "Flicker emission of wind turbines during continuous operation."IEEE transactions on Energy Conversion Vol.17 No.1, March 2002, pp. 114-118.

[2] Gaztanaga, Haizea, Ion Etxeberria, Dan Ocnasu, and Seddik Bacha (2007) "Real-time analysis of the transient response improvement of fixed-speed wind farms by using a reduced-scale STATCOM prototype." Power Systems, IEEE Transactions on Vol.22 No.2, May 2007, pp. 658-666.

[3] Qiao, Wei, and Ronals G. Harley. "Power quality and dynamic performance improvement of wind farms using a STATCOM." Power Electronics Specialists Conference, 2007. PESC 2007. IEEE. IEEE, 2007.

[4] Jazayeri, M., and M. Fendereski (2007). "Stabilization of gird connected wind generator during power network disturbances by STATCOM." Universities Power Engineering Conference, 2007. UPEC 2007. 42nd International. IEEE, 2007.

[5] Fadaeinedjad, Roohollah, Gerry Moschopoulos, and Mehrdad Moallem (2008). "Using STATCOM to mitigate voltage fluctuations due to aerodynamic aspects of wind turbines." Power Electronics Specialists Conference, 2008. PESC 2008. IEEE. IEEE, 2008.

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[6] Qi, L., J. Langston, and M. Steurer (2008). "Applying a STATCOM for stability improvement to an existing wind farm with fixed-speed induction generators."Power and Energy Society General Meeting-Conversion and Delivery of Electrical Energy in the 21st Century, 2008 IEEE. IEEE, 2008.

[7] Chen, Ning Minhui Qian, Lingzhi Zhu, Liangzhong Yao, Fubao Wu,Mei Chen and Ningbo Wang (2012). "A coordinated reactive power and voltage control system for wind farm grid integration." Power System Technology (POWERCON), 2012 IEEE International Conference on. IEEE, 2012.

[8] Naimi, Djemai, Tarek Bouktir, and Ahmed Salhi (2013). "Improvement of transient stability of Algerian power system network with wind farm." Renewable and Sustainable Energy Conference (IRSEC), 2013 International. IEEE, 2013.

[9] Muyeen, S. M and M. Fendereski (2007). "Stabilization of wind farms connected with multi machine power system by using STATCOM." Power Tech, 2007 IEEE Lausanne. IEEE, 2007.pp. 1182-1186

[10] Rodriguez, Pedro, Josep Pou, Joan Bergas, J. Ignacio Candela, Rolando P. Burgos, Dushan Boroyevich (2007) "Decoupled double synchronous reference frame PLL for power converters control." Power Electronics, IEEE Transactions on Vol.22 No.2, March 2007: 584-592.

Survey on Hadoop MapReduce Scheduling

Algorithms

1Pranoti K. Bone and 2A.M.Wade 1PG Student and 2Asst. Professor

1-2Computer Engineering Depatment, Smt. Kashibai Navale College of Engineering, Vadgaon(Bk), Pune, India. pranotibone7@gmail.com adi.wade@gmail.com

Abstract— Mapreduce in hadoop is parallel processing. In modern world data centres operate various MapReduce function in parallel, hence it is essential to furnish an effective scheduling algorithm in order to optimize completion time required for these jobs. Hadoop adapted FIFO scheduling as default scheduling algorithm but maybe this scheduling is not powerful to fulfil the requirements of all jobs. So in this situation one should use alternate scheduling algorithms. This study will incite other experience clients and designers to conceive the details of certain scheduling, enable them to make the best decisions for their certain research interests. Index Terms— Hadoop, MapReduce, scheduling algorithm.

I. INTRODUCTION

Many big firms like Amazon, Facebook and Yahoo use Hadoop. Hiding the details of parallel processing, including data distribution to processing nodes is possible just because of Hadoop [1]. There are the two main component of Hadoop - 1.Hadoop Distributed file system (HDFS) 2.Hadoop MapReduce [2]. HDFS is called as block oriented file system shown in figure 1 [3]. Here every individual file is divided into a block of 64MB. Further these blocks are stored within machines having cluster along with data storage capacity. Every individual machine in the cluster is denoted as ‘DataNode’. Every file constitutes several blocks which are not stored on the same machine .On block by block basis these target machines holding each block are selected randomly. Hence in order to access certain file the co-operation of multiple machine is required. Because of failure of any node in cluster problem of unavailability arises. HDFS cures this problem by making copies of each block over number of machines, generally it is taken as 3. NameNode is a single node in HDFS cluster. It not only manages file system namespace but also regulates user access to files. DataNode helps to store data in block format within files. There are two functions are performed by NameNode - 1. To map data block to DataNode 2. To manage file system. Operations like opening, closing, renaming files and directories. In case of failure of NameNode machines, NameNode data must be preserved. Numbers of copies of NameNode information are maintained on different machines. Hence, in the event of crash it can be accessed by other nodes in cluster. These other nodes can be denoted as secondary NameNode. MapReduce was primarily suggested by Google in order to manage large scale web search applications. MapReduce is signified as an effective programming approach because of advancement of machine learning, data mining and search application in data centres. It includes following two data processing functions - 1) Grenze ID: 01.GIJET.1.1.24 © Grenze Scientific Society, 2015

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Map 2) Reduce. Parallel Map functions are carried on input data which is divided into predetermined sized blocks and generate intermediate output as a cluster of <key, value>pairs. These pairs are intermixed along with various reduce tasks based on <key, value>pairs. Hadoop MapReduce has a master – workers like architecture means it consists of one JobTracker i.e. master and various TaskTracker i.e. workers. The duty of separation from input data and determination of TaskTracker depending on their network space to data source is entrusted upon JobTracker .On the other hand TaskTracker have to submit periodic status report to their master i.e. JobTracker through heartbeat message.

Fig.1. HDFS Architecture

TABLE I. MAPREDUCE I/O

Mapreduce I/O

Functions Input Output Directions

Map (K1,V1)

(K2,V2) The input keys (K1,V1) is mapped to keys k of an intermediate format (K2,V2) collection.

Reduce (K2,V2) (K2,V2) Reduce a group of middle set values associated with K2 to smaller set of values.

In the event of task or worker failures, functions are relaunched on other nodes. The records of heartbeat messages coming from TaskTracker are maintained by JobTracker in order to use them in task assignment. In modern world data centres operate various MapReduce function in parallel, hence it is essential to furnish a effective scheduling algorithm in order to optimize completion time required for these jobs. Nowadays scheduler gives more attention to optimized, little theoretical understanding of scheduling problem subsists in relation to MapReduce. Here we have scrutinized the scheduling algorithm for MapReduce and also compared distinct scheduling algorithm [4][5][6] for MapReduce framework for Hadoop.

II. SCHEDULING IN HADOOP

A. Issues Of Schedulinng In Mapreduce Locality - Locality is the major issue of map-reduce scheduling. The distance between the

input data node and task-assigned node is termed as Locality. Lesser distance leads to lesser data transfer cost. As compared to other scheduling constraints locality is considered as basic approach. Because of limited bisection bandwidth of network locality is considered as very critical issue affecting performance in shared cluster environment. Throughput of task increases due to high locality. Node locality is defined as the processing of a task on a node

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holding the data. In case of impossibility of achieving node locality, job is executed on the same track called as rack locality. In case of nonfulfillment of locality Data transferring I/O cost can greatly affect the execution because of shared bandwidth of network. In order to save cost of network, jobs pursue the policy of assigning task to the nearer location.

Synchronisation - The process of transmitting the intermediate output of the map function to the reduce operation as input is also taken into account as a component which affect performance is termed as synchronisation. Before initiating the sending of intermediate output mappers have to wait for the completion of all the map processes. As map and reduce phases are interdependent, a single node slows down the whole procedure by making other nodes wait till completion. There are many components which degrades the synchronisation process. For e.g. node failures miss-configuration, heterogeneity of cluster and serious overhead of I/O cost.

Fairness - In many big enterprises like Yahoo, Facebook, Google several map-reduce jobs are executed in the shared data warehouse of respective firm. As map-reduce function possess heavy workload , it may rule the utilization of shared clusters, hence some short computation tasks may not have.

B. Related Work Hadoop uses various scheduling algorithms for task assignment. Many researchers are focusing on this issue. Various scheduling algorithm are listed in table I.

TABLE II. VARIOUS SCHEDULING ALGORITHMS

Scheduling Algorithm Description Advantages Disadvantages

FIFO Scheduling First in first out – Oldest job selected first by job tracker.

The HOD virtual cluster can be utilised in a comparatively self-directing way.

It is also adjustable in that it can dwindle when the workload varies.

When it has no running function, it automatically de allocates node from virtual cluster.

It supplies greater safety, with less sharing of nodes.

Because of lack of dissension within the nodes for multiple clients’ job it enhance the performance.

Poor Locality Poor utility

Size of the job or priority are not given any importance

As the resources are used by large jobs, small jobs are ignored.

Fair Scheduling A Process of allocating resources to jobs in such a way that every job will get almost same proportions of resources. When there is any slot vacant the scheduler will assign this slot to the job having huge job deficit.

Less complex Works well when both

small and large clusters Furnish fast response

time for small tasks mixed with large tasks.

It sets the bounds to the number of associate jobs in every job pull.

Job size is completely ignored.

Does not examine availability of resources on fine-grained basis.

Capacity Scheduling

[8]

The capacity scheduler grants sharing huge cluster by devoting each firm capacity guarantee. In case of vacant slots in certain JobTracker, the scheduler will select a queue, then select a job and at last allocate this slot to a job.

Ensure guaranteed access with the potential to reuse unused capacity and prioritize jobs within queues over large cluster.

The most complex among three schedulers.

Does not consider resource availability on a fine-grained basis.

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Delay scheduling [9][10]

Queue based scheduling relaxing fairness for locality enhancement. Although the first slot we consider giving to a job is unlikely to have data for it, tasks finish so quickly that some slot with data for it will free up in the next few seconds

Simplicity of

scheduling

No particular

Dynamic priority

scheduling [11]

In order to balance current workload it allows users to enhance or diminish their queue priorities. Supports the capacity distribution dynamically among concurrent users based on priorities of the users. As per priorities of the users. It helps the capacity distribution.

Configured easily. In the event of crash of system all incomplete low priority processes gets lost.

Deadline constraint scheduling [12]

It concentrates on the deadline constraint of task which denotes the problem of deadline but mainly helps in enhancing system utilization.

Supports optimization of hadoop implementation.

Cost incurred for each node should be uniform.

Longest Approximate Time to End Scheduling [13]

LATE scheduler always speculatively executes the task. If any task works slowly so it is very uncommon to continue with the task processing. Task is progress is very slow due to some reasons like high CPU load on the node, slow background processes etc. All tasks should be finished for completion of the entire job. The scheduler detects a slow running task to launch another equivalent task as a backup which is termed as execution relies implicitly on certain assumptions: a) Uniform Task progress on nodes b) Uniform computation at all nodes.

Robust to node heterogeneity.

Considers node heterogeneity while determining where to run speculative jobs.

Rather than executing task having slow response time it speculatively executes only the jobs which will enhance job response time

It does not divide map slow nodes and decrease slow nodes.

The static manner of computing the growth of job results in poor

Self-Adaptive MapReduce Scheduling [14]

The process of SAMR algorithm includes reading the historical information and tuning parameters, finding the slow tasks, finding the slow TaskTracker, launching backup tasks, collecting results and updating the historical information.

Uses historical information to tune weights of map and reduce stages.

It does not consider that the dataset sizes and the job types can also affect the stage weights of map and reduce tasks.

Enhanced Self-Adaptive MapReduce Scheduling [15]

ESAMR scheduling algorithm also considers the fact that slow tasks extends the execution time of the whole job and due to hardware heterogeneity different amounts of time are needed to complete the same task on different nodes. ESAMR records historical information for each node as in case of SAMR and it adopts a k-means clustering algorithm to dynamically tune stage weight parameters and to find slow tasks accurately. ESAMR significantly improves the performance of MapReduce scheduling in terms of estimating task execution time and launching backup tasks

Can identify slow tasks more accurately.

Improves the performance in terms of estimating task execution time and launching backup tasks.

Little overhead due to K-means algorithm.

Allows only one speculative copy of a task to run on a node at a time.

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III. CONCLUSION

Now a day, the demand of Hadoop is greatly enhancing. Industry possess a large amount of data in large number of data sets hadoop can be implemented. MapReduce is one of the most important parts of hadoop. Here in this paper we have discussed many scheduling algorithms. In the scheduling of hadoop there are several research channels. Future work includes development of scheduling algorithm for load balancing strategy.

ACKNOWLEDGMENT

I would like to thank my respected Guide Prof. A. M. Wade for encouragement and support. I gratefully acknowledge him for inculcating valuable basic knowledge of Big Data Hadoop, MapReduce in me. We are also thankful to the department of Computer Engineering, Smt. Kashibai Navale College of Engineering, Pune for providing us infrastructure facilities necessary for this work and moral support.

REFERENCES

[1] Apache Hadoop. http://hadoop.apache.org. [2] J. Dean and S. Ghemawat. Mapreduce: Simplified data processing on large clusters. OSDI ’04, pages 137–150,

2004. [3] Hadoop Distributed File System, http://hadoop.apache.org/hdfs. [4] V. Krishna Reddy, B. Thirumala Rao, LSS Reddy, “Research issues in Cloud Computing”, Global Journal

Computer Science & Technology Vol. 11, no. 11, June 2011,pp.70-76. [5] Yang XIA†, Lei WANG1, Qiang ZHAO1, Gongxuan ZHANG2, “Research on Job Scheduling Algorithm in

Hadoop”, 2011. [6] Stonebraker, M., “MapReduce and parallel DBMS: friends or foes?”, ACM, 2010. [7] B. Thirumala Rao, N. V. Sridevi, V. Krishna Reddy, LSS.Reddy, “Performance Issues of Heterogeneous Hadoop

Clusters in Cloud Computing”, Global Journal Computer Science & Technology Vol. 11, no. 8, May 2011,pp.81-87. [8] Hadoop’s Capacity Scheduler :http://hadoop.apache.org/core/docs/current/capacityscheduler. [9] Matei Zaharia, Dhruba Borthakur, Joydeep Sen Sarma, Khaled Elmeleegy, Scott Shenker, and Ion Stoica. “Delay

scheduling: a simple technique for achieving locality and fairness in cluster scheduling in EuroSys10”, Proceedings of the 5th European conference on Computer systems, pages 265–278, New York, NY, USA, 2010. ACM.

[10] Matei Zaharia, Dhruba Borthakur, Joydeep Sen Sarma,Khaled Elmeleegy, Scott Shenker, Ion Stoica, “Job Scheduling for Multi-User MapReduce Clusters”, Electrical Engineering and Computer Sciences, University of California at Berkeley, April 2009.

[11] Thomas Sandholm and Kevin Lai. “Dynamic proportional share scheduling in Hadoop in JSSPP”, 15th Workshop on Job Scheduling Strategies for Parallel Processing, April, 2010.

[12] K. Kc and K. Anyanwu, "Scheduling Hadoop Jobs to Meet Deadlines", in Proc. CloudCom, 2010, pp.388- 392. [13] M.Zaharia, A.Konwinski, A.Joseph, Y.zatz, and I.Stoica. Improving mapreduce performance in heterogeneous

environments. In OSDI’08: 8th USENIX Symposium on Operating Systems Design and Implementation, October 2008

[14] Quan Chen; Daqiang Zhang; Minyi Guo; Qianni Deng; Song Guo; , "SAMR: A Self-adaptive MapReduce Scheduling Algorithm in Heterogeneous Environment,"(2010) Computer and Information Technology (CIT), 2010 IEEE 10th International Conference on , vol., no., pp.2736-2743.

[15] Xiaoyu Sun, Chen He and Ying Lu “ESAMR: An Enhanced Self-Adaptive MapReduce Scheduling Algorithm”(2012) IEEE 18th International Conference on Parallel and Distributed Systems.

SET for Cluster-based Cloud Computing: A Survey

Neelambike S1 and Dr. B P Mallikarjunaswamy2

1 Assistant professor, GM Institute of Technology,Davangere Email: neelais@gmail.com

2 Professor, Sri Siddhartha Institute of Technology, Tumkur Email: drbpmswamy@rediffmail.com

Abstract— secure data transmission is a critical issue for Cloud computing networks. Clustering is an effective and practical way to enhance the system performance of cloud. Paper provides study about a secure data transmission for cluster-based cloud (CCNs), where the clusters are formed dynamically and periodically. The paper proposes two Secure and Efficient data Transmission (SET) protocols for CCNs, called SET-IBS and SET-IBOOS, by using the Identity-Based digital Signature (IBS) scheme and the Identity-Based Online/Offline digital Signature (IBOOS) scheme, respectively. In SET-IBS, security relies on the hardness of the Diffie-Hellman problem in the pairing domain. SET-IBOOS further reduces the computational overhead for protocol security, which is crucial for Cloud, while its security relies on the hardness of the discrete logarithm problem. The paper shows the feasibility of the SET-IBS and SET-IBOOS protocols with respect to the security requirements and security analysis against various attacks. The calculations and simulations are provided to illustrate the efficiency of the proposed protocols. The expected results of using the proposed protocols is the increase in performance of the existing secure protocols for CCNs, in terms of security overhead and energy consumption. Index Terms— SET;SET-IBS;SET-Iboos;Cloud;CCN.

I. INTRODUCTION

In existing System of Cloud computing networks, Secured socket layer (SSL) is being used to provide the security for efficient data transmission. A disadvantage of SSL Just because a site uses SSL to secure personal data does not mean it is completely safe. As research conducted by ethical hackers show, as many as 30 percent of SSL sites are unsafe [1]. In the Proposed System, Secure and efficient data transmission is thus especially necessary and is demanded in many such practical CCNs. So this paper proposes two Secure and Efficient data Transmission (SET) protocols for CCNs, called SET-IBS and SET-IBOOS, by using the Identity-Based digital Signature (IBS) scheme and the Identity-Based Online/Offline digital Signature (IBOOS) scheme, respectively. Advantages of proposed system This paper has been proposed in order to reduce the computation and storage costs of encrypting data, by applying digital signatures to message packets, which are efficient in communication and also applying the key management for security. So, the transactions are secured by using the digital signatures.

II. LITERATURE REVIEW In Secure and Efficient Data Transmission for Cluster-based Wireless Sensor Networks [2] paper the results Grenze ID: 01.GIJET.1.1.509 © Grenze Scientific Society, 2015

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show that SET-IBS and SET-IBOOS protocols provides better performance for efficient data transmission in Cluster based wireless sensor networks. For achieving the efficient data transmission in cloud network introduces the same two protocols [SET-IBS and SET-IBOOS]. Cluster-based data transmission in WSNs has been investigated by researchers in order to achieve the network scalability and management, which maximizes node lifetime and reduce Bandwidth consumption by using local collaboration among sensor nodes [3]. Using the clustering algorithms easily identified which cloud is free then allocates the task to that particular cloud to achieve the specific task. Adding security to LEACH-like protocols is challenging, because they dynamically, randomly and periodically rearrange the network’s clusters and data links [4]. These same concepts are used in proposed system for making the dynamic clusters for achieving the fast and efficient result. The symmetric key management for security, which suffers from a so-called orphan node problem [5]. This problem occurs in CWSNs when a node does not share a pairwise key with others in its preloaded key ring. In order to mitigate the storage cost of symmetric keys, the key ring in a node is not sufficient for it to share pairwise symmetric keys with all of the nodes in a network. In proposed work uses the symmetric key management for achieving the key exchange. The feasibility of the asymmetric key management has been shown in WSNs recently, which compensates the shortage from applying the symmetric key management for security [6]. Digital signature is one of the most critical security services offered by cryptography in asymmetric key management systems, where the binding between the public key and the identification of the signer is obtained via a digital certificate [7]. The Identity-Based digital Signature (IBS) scheme [8], based on the difficulty of factoring integers from Identity-Based Cryptography (IBC), is to derive an entity’s public key from its identity information, e.g., from its name or ID number. Recently, the concept of IBS has been developed as a key management in WSNs for security. Carman [9] first combined the benefits of IBS and key pre-distribution set into WSNs, and some papers appeared in recent years [10–11]. The IBOOS scheme has been proposed in order to reduce the computation and storage costs of signature processing. A general method for constructing online/offline signature schemes was introduced by Even et al. [12]. The IBOOS scheme could be effective for the key management in WSNs. Specifically; the offline phase can be executed on a sensor node or at the BS prior to communication, while the online phase is to be executed during communication. Some IBOOS schemes are designed for WSNs afterwards, such as [13] and [14]. The offline signature in these schemes, however, is precompiled by a third party and lacks reusability, thus they are not suitable for CWSNs. Proposes two Secure and Efficient data Transmission (SET) protocols for CCNs, called SET-IBS and SET-IBOOS, by using the IBS scheme and the IBOOS scheme, respectively. The key idea of both SET-IBS and SET-IBOOS is to authenticate the encrypted data, by applying digital signatures to message, which are efficient in communication and applying the key management for security. In the proposed protocols, secret keys and pairing parameters are distributed and preloaded in all cloud, which overcomes the key escrow problem described in ID-based crypto-systems [15]. Our objective is to build a fully secured data transmission for cluster-based cloud (CCNs), where the clusters are formed dynamically and periodically. The paper proposes two Secure and Efficient data Transmission (SET) protocols for CCNs, called SET-IBS[16] and SET-IBOOS, by using the Identity-Based digital Signature (IBS) scheme and the Identity-Based Online/Offline digital Signature (IBOOS) scheme, respectively[16,17]. SET Protocol: In this module, Secure and Efficient data Transmission (SET) protocol for CCNs. The SET-IBOOS protocol is designed with the same purpose and scenarios for CCNs with higher efficiency. The proposed SET-IBOOS operates similarly to the previous SETIBS, which has a protocol initialization prior to the network deployment and operates in rounds during communication. First introduce the protocol initialization, and then describe the key management of the protocol by using the IBOOS scheme, and the protocol operations afterwards. Key management for security: In this module, security is based on the each services request from the client. The corresponding private pairing parameters are preloaded in the cloud during the protocol initialization. The IBOOS scheme in the proposed SET-IBOOS consists of following four operations, extraction, offline signing, online signing and verifications. Key management: In this Module, the key cryptographies used in the protocol to achieve secure data transmission, which consist of symmetric and asymmetric key based security. Storage cost: In this module, represents the requirement of the security keys stored in each service provider. Network scalability: In this module, indicates whether a security protocol is able to scale without compromising the security requirements. Here, “comparative low” means that, compared with SET-IBS and

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SET-IBOOS, in the secure data transmission with a symmetric key management, the larger network scale increases. Communication overhead: In this module, the security overhead in the data packets during communication. Computational overhead: In this module, the energy cost and computation efficiency on the generation and verifications of the certificates or signatures for security. Attack resilience: In this module, the types of attacks that security protocol can protect against.

III. CONCLUSIONS

In this paper, first reviews the data transmission issues and the security issues in CCNs. The deficiency of the symmetric key management for secure data transmission has been discussed. We then presented two secure and efficient data transmission protocols respectively for CCNs, SET-IBS and SET-IBOOS. In the evaluation section, we provided feasibility of the proposed SET-IBS and SET-IBOOS with respect to the security requirements and analysis against routing attacks. SET-IBS and SET-IBOOS are efficient in communication and applying the ID-based crypto-system, which achieves security requirements in CCNs, as well as solved the orphan node problem in the secure transmission protocols with the symmetric key management.

ACKNOWLEDGMENT

The authors wish to thank My Guide Dr. B.P. Mallikarjunaswmay for his valuable support and suggestion for preparing papers, my grateful thanks to my brother and mother and sisters for their valuable supports.

REFERENCES

[1] David Wagner and Bruce Schneier, “Analysis of the SSL 3.0 protocol” in Revised April 15, 1997. [2] Huang Lu, Student Member, IEEE, Jie Li, Senior Member, IEEE, Mohsen Guizani, Fellow, IEEE, “Secure and

Efficient Data Transmission for Cluster-based Wireless Sensor Networks” IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEM YEAR 2013.

[3] A. A. Abbasi and M. Younis, “A survey on clustering algorithms for wireless sensor networks,” Comput. Commun., vol. 30, no. 14-15, pp.2007.

[4] 2826–2841, 2007. L. B. Oliveira, A. Ferreira, M. A. Vilac¸a et al., “SecLEACH-On the security of clustered sensor networks,” Signal Process., vol. 87, pp. 2882–2895, 2007.

[5] L. B. Oliveira, A. Ferreira, M. A. Vilac¸a et al., “SecLEACH-On the security of clustered sensor networks,” Signal Process., vol. 87, pp. 2882–2895, 2007.

[6] S. Sharma and S. K. Jena, “A Survey on Secure Hierarchical Routing Protocols in Wireless Sensor Networks,” in Proc. ICCCS, 2011, pp.146–151.

[7] G. Gaubatz, J. P. Kaps, E. Ozturk et al., “State of the Art in Ultra-Low Power Public Key Cryptography for Wireless Sensor Networks,” in Proc. IEEE PerCom Workshops, 2005, pp. 146–150.

[8] W. Diffie and M. Hellman, “New Directions in Cryptography,” IEEE Trans. Inf. Theory, vol. 22, no. 6, pp. 644–654, 1976.

[9] A Shamir, “Identity-Based Cryptosystems and Signature Schemes,” in Lect. Notes. Comput. Sc. - CRYPTO, 1985, vol. 196, pp. 47–53.

[10] D. W. Carman, “New Directions in Sensor Network Key Management,” Int. J. Distrib. Sens. Netw., vol. 1, pp. 3–15, 2005.

[11] R. Yasmin, E. Ritter, and G. Wang, “An Authentication Framework for Wireless Sensor Networks using Identity-Based Signatures,” in Proc. IEEE CIT, 2010, pp. 882–889.

[12] H. Lu, J. Li, and H. Kameda, “A Secure Routing Protocol for Cluster-Based Wireless Sensor Networks Using ID-Based Digital Signature,” in Proc. IEEE GLOBECOM, 2010, pp. 1–5.

[13] J. Sun, C. Zhang, Y. Zhang et al., “An Identity-Based Security System for User Privacy in Vehicular Ad Hoc Networks,” IEEE Trans. Parallel Distrib. Syst., vol. 21, no. 9, pp. 1227–1239, 2010.

[14] S. Even, O. Goldreich, and S. Micali, “On-Line/Off-Line Digital Signatures,” in Lect. Notes. Comput. Sc. - CRYPTO, 1990, vol. 435, pp. 263–275.

[15] S. Xu, Y. Mu, and W. Susilo, “Online/Offline Signatures and Multisignatures for AODV and DSR Routing Security,” in Lect. Notes. Comput. Sc. - Inf. Secur. Privacy, 2006, vol. 4058, pp. 99–110.

[16] J. Liu, J. Baek, J. Zhou et al., “Efficient online/offline identity-based signature for wireless sensor network,” Int. J. Inf. Secur., vol. 9, no. 4, pp. 287–296, 2010.

[17] Y. Jararweh, Z. Alshara, M. Jarrah, M. Kharbutli, M. Alsaleh, “Teachcloud: a cloud computing educational toolkit”, Proceedings of the 1st International IBM Cloud Academy Conference (ICA CON 2012), IBM, Research Triangle Park, NC, USA, 2012.

Author Index

A Ajith A 53 Ananda Resmi S 53 Anjaneyulu K S R 37 B Bidyadhar Rout 30 D Deepak Kumar Lal 30 G Gayatri S 15 K Kuldip Singh 37 M Mallikarjunaswamy B P 72 Marimuthu V 21 N Narasihma Rao K 1 Narendra Kumar M 37 Narkhede B E 15 Neelambike S 72 Nivedita G Gogate 44

P Palani G S 21 Parin Gosar 15 Prabha P 21 Pranoti K Bone 67 Prasanna Kumar Biswal 30 Pratap M Rawal 44 Pravin R Patil 8 R Reji P 59 Rijo Rajan 59 Rishi D S 21 S Saravanan M 21 Srinivas G 1 Srinivas K 1 Surendran M 21 T Tayade R M 8 W Wade A M 67

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