planning studies for connection of 500 mw photovoltaic

Helwan University

From the SelectedWorks of Omar H. Abdalla

November 11, 2018

Planning Studies for Connection of 500 MWPhotovoltaic Power Plant to Oman Grid at IbriHisham A. Al-RiyamiAdil Al-BusaidiAhmed Al-NadabiMusabah N. Al-SayabiOmar H. Abdalla

Available at: https://works.bepress.com/omar/53/

http://www.helwan.edu.eg

https://works.bepress.com/omar/

https://works.bepress.com/omar/53/

Planning Studies for Connection of 500 MW Photovoltaic Power

Plant to Oman Grid at Ibri

H. A. Al Riyami1, A. G. Al Busaidi

1, A. A. Al Nadabi

1, M. N. Al Sayabi

1, A. S. Al Omairi

1, & O. H. Abdalla

2

1Oman Electricity Transmission Company (Sultanate of Oman)

2Helwan University (Egypt)

Summary:

The paper presents techno-economic studies

for connecting a 500MW Photovoltaic (PV) power

plant to the Main Interconnected Transmission

System (MITS) at Ibri. The objective is to justify

the required capital expenditure on the basis of the

submission of a full, complete and robust study

report insuring the transmission system in Oman

is planned, developed and operated in an efficient

manner. Three connection options are proposed

and compared considering cost, compliance with

the Security Standard, technical performance,

deliverability, environmental conditions, flood risk

assessment and safety.

The MITS models of 2020 and 2021 have been

updated to include the simulation of the alternative

connections of the 500MW PV power plant. The

DIgSILENT PowerFactory professional software is

used to perform system analyses for different

cases. The solar PV technology and components

are discussed. The MITS description and is

presented. Steady-state analyses; including power

flow, 3-phase short-circuit, 1-phase short-circuit

and contingency are presented. Transient analyses;

including system responses to line fault and

generator outage are presented.

Keywords: Ibri Solar Power Plant, MITS,

Photovoltaic.

1. INTRODUCTION

There has been a considerable interest in

renewable energies over the world in recent decades.

Oman Electricity Transmission Company (OETC) has

received a connection application from Oman Power

and Water Procurement Company (OPWP) [1] for

connection of a 500 MW Photovoltaic (PV) power

plant to the Main Interconnected Transmission

System (MITS) at Ibri. The target date of the PV

power plant connection is 1st of December 2020 and

the scheduled commercial operation date is June

2021. In order to meet the Transmission Licence

Conditions 8, 23 and 26 [2] and mitigate any risk

associated with non-compliance of these obligations,

OETC has to prepare a Pre-Investment Appraisal

Document (PIAD) including technical and economic

studies to assess a number of available connection

options and recommend the most financially and

technically suitable solution [3, 4].

The following three proposed options have been

assessed and compared:

Option 1: 132 kV connection by LILO of Ibri-

Dank Line.

Option 2: 220 kV direct connection to Ibri IPP grid station.

Option 3: 400 kV direct connection to Ibri IPP grid station.

The preferred option providing a technically

viable, deliverable and financially preferable solution

is Option 2: the construction of a 220 kV double

circuit connection from Ibri Solar Power Plant to Ibri

Independent Power Plant (Ibri IPP). This solution

allows new generation at Ibri Solar Power Plant to

supply local loads in the Ibri area with a parallel

connection into the wider 400 kV network to New

Izki. Furthermore, the selected option aligns with the

OETC master plan (2014-2030) [5]. The preferred

option presented a lower lifetime cost (on an NPV

basis), lower losses, higher technical performance and

a more deliverable solution.

Figure 1: The MITS of Oman in 2018.

The paper is organized as follows: Section 2 describes the existing transmission system in Oman. Section 3 provides a brief description of the PV Power Plant concept. Section 4 presents Ibri generation site and surrounding transmission assets. Section 5 presents the technical and economic studies of connecting Ibri IPP to the MITS and provides a comparison of the options. Section 6 presents full technical and economic studies of the preferred connection option. Section 7 summarises the main conclusions of the paper.

2. SYSTEM DESCRIPTION

The existing transmission system in northern

Oman has three HV operating voltages, i.e. 400 kV,

220 kV and 132 kV while in Dhofar 132 kV is

employed. The transmission system extends across the

whole of northern Oman and interconnects bulk

consumers and generators of electricity located in the

Governorates of Muscat, Batinah South, Batinah

North, Dhahirah, Buraimi, Dakhliyah, Sharquiya

South and Sharqiya North as shown in Figure 1.

The present OETC transmission system of the

MITS consists of [6]:

1214.5 circuit-km of 400 kV overhead

transmission lines


transmission lines


transmission lines

75.1 circuit-km of 220 kV underground cables

158.52 circuit-km of 132 kV underground cables

9750 MVA of 400/220 kV transformer capacity





Three 400/220/132/33 kV grid stations

Two 400/220 kV interconnection grid stations

Three 220 kV interconnection grid stations

Six 220/132/33 kV grid stations

Two 220/132 kV grid stations

Two 220/33 kV grid stations

Fifty Three 132/33 kV grid stations

One 132/11 kV grid station

In addition, the present OETC transmission

system at Dhofar consists of [6]:


transmission lines

33.64 circuit-km of 132 kV cables


Eight 132/33 kV grid stations

3. PHOTOVOLTAGE POWER PLANT

A photovoltaic system is a green power source, which converts sunlight directly to electricity. The main advantages of the PV system are that it requires

no fuel, produces no emissions, and involves no moving parts. Figure 2 shows the main components of a PV power plant. It consists of a large number of solar arrays, DC/DC converters, DC/AC inverters, filters, and step up transformers.

Figure 2: Main components of a PV power plant.

A solar PV module, which consists of a number of solar cells, produces only a small amount of current and voltage. In order to produce a large amount of electric power, the solar cell modules are connected into arrays. The output voltage from a PV array changes with solar radiation and ambient temperature. In order to connect the PV system to the transmission grid, the output DC voltage from PV system should be first regulated by a DC/DC converter and then converted to AC voltage source by a DC/AC inverter. A filter is used to eliminate harmonics. The power electronic components (DC/DC converter, DC/AC inverter, and filter) have the tasks to guarantee safe and efficient operation, to track the maximum power point tracking of the PV system, and to maintain power quality of the PV system output.

4. IBRI IPP GENERATION SITE AND

SURROUNDING MITS ASSETS

The Ibri Solar IPP site is proposed to be located approximately midway between the towns of Ibri and Dank (see Figure 3). Nearby there exists a 220 kV double-circuit OHTL which terminates at Ibri from Mahadha in the north (~150 km total length). In parallel to this, a 132 kV network extends from Ibri to Mahadha via Dank and Wadi Sa’a (see Figure 1). These 132 kV circuits also continue from Ibri to the east towards Izki. Also, there is 400 kV double-circuit line connected between Ibri IPP grid station and New Izki grid station (~264 km total length). There is a designed 400 kV overhead line but currently operated at 220 kV; it is under construction between Sohar-3 IPP via SFZ and Mahadh and is expected to be completed by end of July 2018. Mahadh is connected to the UAE grid and Ibri IPP via a double-circuit 220 kV overhead line. Therefore, the evacuation corridors of the generated power at Ibri area will be via the 400 kV system towards Izki and Misfah and via 220 kV system towards Mahadh and consumed locally at Ibri through the 220 kV and 132 kV systems in Ibri, Dreez, Dank and Heyal grid stations.

Figure 3: Ibri generation site

With reference to the Annual Five Year Capability Statement 2018 [6], it is expected that new 400 kV double circuit lines from Ibri to New Izki (under construction – June 2018 expected completion date), and 400/220 kV with 3x500 MVA transformers (already Energized). Additionally, the ongoing project of construction 400 kV double circuit lines from New Izki to Misfah is expected to be completed by the end of March 2019. New 400 kV lines to SFZ and Mahadh grid stations are construction.

Figure ‎4 shows the forecasted peak demand

growth against the net maximum generation export in

the area (substations along the corridor from Mahadha

in the north to Nizwa in the south).

5. TECHNICAL AND ECONOMIC

EVALUATION OF OPTIONS

Three options have been considered to mitigate the risks associated with non-compliance of License Conditions 8, 23 and 26 [2]. These options are summarised as follows:

Option 1: 132 kV connection by LILO of Ibri-

Dank Line.

Option 2: 220 kV direct connection to Ibri IPP

grid station.

Option 3: 400 kV direct connection to Ibri IPP

grid station.

Each of these options is assessed on the basis of the following performance considerations:

i. Deliverability

All the associated circumstances on every option have been assessed on term of circuit routes, grid station location …etc.

DC/AC Inverter

DC/DC Convert

er

Grid

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400

2018

2019

2020

2021

2022

762.8

819.5

832.7

881.4

934

1261

1803

1802

1801

2299

MW

Ye

ar

Peak Demand VS Net Generation

Net Generation

Peak Demand

Figure 4: Peak demand and net generation forecast in study area.

ii. TSS Compliance The Transmission Security Standard has been

prepared in accordance with Condition 26 of OETC's Transmission and Dispatch Licence [2]. OETC implements the TSS for the planning and operation of its licensed transmission system.

iii. Capital cost Cost of every asset and civil works cost on every options have been be calculated thoroughly.

iv. Net Present Value (NPV) The net present value is calculated for every option for 40 years.

v. Environmental considerations As OETC is an ISO 14001 (EMS) “Environmental Management System” certified company, it is committed toward environment so all the environmental impacts of every project are considered.

vi. Flood risk assessment OETC maintains a check list that considers the location of all assets associated to every option to the nearest flood or valleys.

vii. Safety As OETC is an ISO 18001 (OHSAS) “Occupational Health and Safety Assessment Series” certified company, it is committed toward safety so all the safety impacts of every project are considered.

viii. Comparison of options Table I provides a comparative summary of the

options based on the key aspects assessed including financial, technical performance, deliverability, environmental considerations including Flood Risk

Assessment (FRA) and safety aspects. Colour coding is provided for visual reference such that green indicates no issues, yellow indicates feasibility but with some additional considerations, red indicates a non-feasible aspect which prevents the option from being considered further and black notes items in non-feasible options that have not been fully assessed due to a prior limitation.

As summarised in Table I, Option 1 is deemed not feasible as a result of significant overloads seen under (N-1) assessments across a range of outage conditions and therefore non-compliant with the OETC TSS and subsequent Licence Condition 26. This option is therefore not considered further, leaving Option 2 and Option 3 as the remaining feasible options. While both options 2 and 3 are having almost similar technical performance, then the main factor for comparison is the capital cost for the present and future solar expansion. A summary of Option 2 and Option 3 and the relative merits of each are subsequently provided below:

Option 2

This option presents the least cost lifetime cost solution with regard to capital cost by minimising any new 400 kV infrastructure and utilising the 220 kV voltage level. It is proposed that the 220 kV overhead lines be constructed for a length of 3 km. It also complies with the TSS requirements. In addition, option 2 has lower power losses in comparison with option 3. Furthermore, option 2 incurs lower capital cost by about two million for the present connection of Ibri Solar-PV power plant and also lower capital cost by about one million for future solar expansion if required.

Table I: Comparison of options

Option 1

Option 2

Option 3

Capital Cost

[R.O.] 8,284,726.23 10,197,550.61

NPV -29,463,075 -33,448,649

Future Solar Expansion

Cost 1,354,497 2,202,375

Tech

nic

al

Perfo

rm

an

ce

Intact TSS Violation (Loading Issue) No issues No issues

N-1 TSS Violation (Loading&

Supply lost Issues) No issues No issues

N-M-1

No issues No issues

Short Circuit

No issues No issues

Losses (2022 Peak) High losses (51MW) Lower losses (32.13MW) Medium losses (33.03MW)

Deliverability

LILO of the 132kV OHL will

required long Shutdown and

proper coordination to secure

power supply to Dank and

Yanqul areas

- Crossing rail way

route

- Securing new OHL

route

- Crossing rail way route

- Securing new OHL

route

Environmental No issues No issues No issues

FRA Low risk Low risk Low risk

Safety Has medium risk dealing with

existing OHL diversion

Has medium risk by working in

live system at Ibri IPP GS

Has medium risk by working in

live system at Ibri IPP GS

Option 3

This option results in a greater capital cost due to

the establishment of a 400 kV substation at Ibri Solar-

PV PS with associated 400 kV OHL and additional

two 400 kV bays at Ibri IPP substation. Moreover, the

future solar expansion will entails higher capital cost

compared to option 2. Furthermore, it has higher loss

compared to be option 2.

Based on the comparison of the options presented

above, it is clear that option 2 represents the

technically preferred long term solution whilst

providing the lowest lifetime cost with minimised

deliverability risks. Subsequently, option 2 is

recommended for the connection of the proposed Ibri

Solar-PV IPP generator.

ix. Dynamic studies

Subsequently, dynamic studies of the preferred option (option 2) relating to a close and remote three phased fault of one of the 220 kV lines from Ibri Solar-PV PS to Ibri IPP have been conducted. Also, a Solar-PV PS trip at Ibri have been conducted and the results are presented. The studies have been completed for peak and off peak demand conditions. It is concluded that there are no issues to report with regard to the dynamic assessment with all generators in MITS remaining stable under the conditions assessed.

6. PREFERRED CONNECTION OPTION

A. Configuration Figure 5 shows the location of Ibri Solar power

plant with option 2 connection. Figure 6 shows a

simplified connection of Option 2. This preferred

option mitigates the licence condition risks whilst

providing a technically viable, deliverable and

financially preferable solution through the

construction of a 220 kV double circuit connection for

a length of 3 km from Ibri Solar-PV IPP to Ibri IPP

station. The solution allows new generation at Ibri

Solar-PV power plant to supply local loads in the

Ibri/Nizwa area with a parallel connection into the

wider 400 kV network to Misfah, Izki and Mudharib.

Figure 5: Location of Ibri 500 MW power plant

Figure 6: Simplified configuration of Option 2.

B. Works and Equipment

The outline specification of the works associated

with the preferred option is as follows:

Establish 220 kV switchgear (GIS) in Ibri Solar-PV

PS Substation

2 x 220 kV GIS: unit incomers

4 x 220 kV GIS: two bus section and two bus

coupler

2 x 220 kV GIS: outgaining feeders

Associated civil, auxiliary and infrastructure

works to support the above equipment

2 x 220 kV GIS as feeder incomers at Ibri IPP

substation with associated protection and civil

modification.

3 km 220 kV twin Araucaria overhead line double

circuit from Ibri Solar-PV IPP to Ibri IPP grid

station.

500 m, 220 kV, 2500 mm2 XLPE cable

between the gantries to the 220 kV GIS at Ibri

IPP station.

This option 2 is capable to cater for the future

solar expansion in Ibri area with additional investment

but with lower cost in comparison with option 3. It is

recommended that the works are carried out in time

for meeting the proposed schedule commercial

operation date of June 2021 to ensure compliance

with OETC licence conditions. Maximum export of

500 MW for the Ibri Solar-PV IPP generator is

expected in June 2021.

C. Cost

The chosen option aligns well with the OETC

principles of developing the Oman electricity

transmission system in a cost effective manner whilst

providing a secure and reliable service to customers in

compliance with statutory requirements (i.e. the Oman

Grid Code, Transmission Licence, etc.). The preferred

option provides lower lifetime cost (on NPV basis),

lower losses, higher technical performance and a more

deliverable solution. The estimated capital cost for

connection of the Ibri IPP to the MITS is R.O.

8,284,726.23. The requested funding will be

distributed over five years as follows:

2018 – R.O. 1,656,945.25

2019 – R.O. 2,899,654.18

2020 – R.O. 2,899,654.18

2021 – R.O. 828,472.62

D. Deliverability

This option would require the delivery of a new

220 kV specification double circuit line for a length of

approximately 3 km. Initial site surveys have been

conducted and indicated that there is scope to acquire

a suitable right of way to allow this development.

Also, the rail route is passing in between the Ibri

Solar-PV and Ibri IPP sites which shall be considered

during the OHTL design. However, at this time the

survey has indicated that the use of overhead line

throughout the route length should be feasible.

E. Technical Performance

A digital model of the MITS has been developed

[9] using the DIgSILENT professional software [10].

The model has been updated to accommodate new

assets to be added in studied years (2021). The

following simulation studies have been performed to

assess the technical performance of the MITS with

Option 2 of Ibri Solar IPP connection.

Intact Conditions

Tables II show power flow results at peak

demand condition after adding the Ibri IPP in 2021.

Although Ibri IPP and Ibri Solar-PV IPP physically

are in one site and Ibri Solar is connected through 3

km of 2 x 220 kV OHTL to Ibri IPP 220 kV BB, but

electrically they have a common connection point.

Therefore, it looks like one generation site with

approximately 2039 MW (500 MW Solar plus 1539

MW Ibri IPP). Since the connection of the Solar-PV

IPP under this option is via the 220 kV, the flow from

400 kV Ibri IPP GS to Ibri load group decreases and

the majority of the Ibri IPP power is now exported by

the 400 kV lines in the direction of New Izki and

Misfah areas around 1072 MW compared to 654.7

MW prior the connection of the Solar-PV IPP. Thus,

there is no concern for the out of frim loading of the

3x500 MVA, 400/220 kV transformers at Ibri IPP.

However, the risk of the out of firm loading is

cascaded to the 220/132 kV, 2x500 MVA

transformers at Ibir grid station where the loading

reached 56.18%. However, it should be highlighted

that the loading of these transformers is not mainly

driven by the connection of Ibri Solar-PV IPP rather

than the load growth in Ibri area where their loading

before the connection of the Solar-PV IPP was

47.91%. However, tripping any of these transformer

has not resulted in overloading of the second

transformer and therefore comply with TSS

requirement.

The other lines and transformers at Ibri network

are well within the standard limits. The loading of the

2 x 220 kV line between Ibri IPP to Ibri grid stations

is 41.74% which is very well within the firm capacity.

With respect to the voltage profile for Ibri network

area at different voltage levels 400 kV, 220 kV and

132 kV, it shows acceptable voltage profile and no

voltage violation has been detected for the system

peak condition.

(N-1) Contingency Conditions

A loss of one of the 400 kV lines to New Izki

results in small impact on the remaining network with

flows seen to be in line with intact conditions (with

exception to the second 400 kV line which is now

loaded to 41.62%). Similarly, a loss of one of the 220

kV lines to Mahadha also results in small impact on

the remaining network.

Subsequently, a loss of one of the 220 kV circuits

from the Ibri IPP substation to the Ibri 220/132 kV

substation results in other circuit loading to 77.48%.

Furthermore a loss of one of the 220/132 kV

transformers results in loading of the remaining

transformer to 96.66% which complies with TSS

criteria. Therefore, a third transformer may be will

required in the future considering the load growth of

the area which is subject to another assessment.

Moreover, losing one of the 3 x 400/220 kV

transformers at Ibri IPP station has no major impact as

the Solar-PV IPP connection is at 220kV system and

no violation has been observed. Additionally, a loss of

any of the 132 kV circuits in the Ibri to Jebreen

corridor results in loading of the remaining circuit (up

to 46.67%).

Finally, from voltage profile perspective, the

most credible scenario that has the highest voltage

changes is the loss of one of the 220/132 kV

transformers at Ibri grid station. However, the drop of

voltages were within the acceptable limits, where the

lowest voltages were (0.96-0.97 pu) noted at Dreez,

Hayel and Jebreen stations of as shown in Table II.

From the above assessment it is clear that Option

2, with connection arrangement does meet OETC TSS

requirements under (N-1) condition. This option is

therefore deemed feasible on the grounds of OETC

TSS compliance.

(N-M-1) Contingency Conditions

(N-M-1) conditions relate to a forced outage

occurring during the periods of low demand, when

another asset is already out for maintenance. The

network configuration for the (N-M-1) study reflects

the maintenance period (usually in winter) when the

OETC TSS requirements such that all 33 kV (and

below) connected loads are reduced to 67% of peak

demand unless realistic data is available, whilst direct

connected customers to transmission customers

remain at peak demand values. As the assessment

focus of this PIAD is the connection of Ibri Solar-PV

PS, it assumed to operate at its maximum output 500

MW to reflect the most challenging operation case.

Therefore, the connection arrangement that being

assessed must be capable to cater for full power

evacuation under the (N-M-1) condition whilst Ibri

IPP is dispatched in practical manner similarly to

other generation in the transmission network.

Therefore, the total generation at Ibri in this case is

892 MW (500 MW Solar plus 392 MW Ibri IPP).

The above arrangement provides a suitable

network configuration to allow the (N-M-1) studies to

be conducted, representing a reduced load scenario in

line with OETC TSS requirements (and practical

network loadings in the maintenance period) in

addition to a practical generation dispatch whilst

maintaining a maximum output of Ibri Solar-PV IPP.

Sur gas turbines, as the reference (swing bus)

machines, are seen to be at 54% output under this

arrangement, indicating a practical balance of

generation and demand. Further (N-M-1) contingency

analysis indicated no voltage constraints based on this

connection arrangement as the load during the

maintenance period is low.

Short Circuit Levels

Three-phase and single-phase to ground intact

system short circuit system levels (all generators on to

provide worst case assessment) have been calculated

(according to the IEC 60909) and are measured

against equipment ratings for relevant substation

locations in the vicinity of the new Ibri Solar IPP.

Table II: Branch power flow and voltage profile (2021)

Peak System Case Loading %

Condition N

Condition

N-1

Conditions

Lines / Scenarios Intact

System

220 kV OHL

Ibri Solar-

Ibri IPP

400 kV OHL

Ibri IPP-

New Izki

220 kV

OHL Ibri

IPP-Ibri GS

220 kV OHL

Ibri IPP-

Mahadha

132 kV

OHL Ibri

GS-Jebren

2x500 MVA

(220/132kV)

Tx @ Ibri GS

220kV OHL Ibri

Solar-Ibri IPP 35.99 71.19 36.3 35.64 35.74 35.52 35.63

400kV OHL Ibri

IPP-New Izki 29.07 29.07 47.94 29.69 30.99 29.86 30.29

220kV OHL Ibri

IPP-Ibri GS 41.74 41.74 47.65 77.48 44.24 38.48 35.91

220kV OHL Ibri

IPP-Mahadha 24.14 24.14 34.84 25.71 33.84 24.91 27.2

132kV OHL Ibri

GS-Jebren 32.7 32.68 41.47 28.95 34.13 46.67 25.62

3x500MVA

(400/220kV) Tx

Ibri IPP

28.55 28.62 42.35 27.43 25.39 26.4 26.09

2x500MVA

(220/132kV) Tx @

Ibri GS

56.18 56.18 64.13 52.14 59.54 51.79 96.66

Peak System Case Voltage Profile (pu)

220kV Ibri Solar

BB 1.04 1.04 1.02 1.04 1.04 1.05 1.04

400kV Ibri IPP BB 1.04 1.04 1.03 1.04 1.04 1.04 1.04

400kV New Izki

BB 1.02 1.02 1.0 1.02 1.01 1.01 1.01

220kV Ibri IPP BB 1.04 1.04 1.02 1.04 1.04 1.05 1.04

220kV Ibri GS BB 1.02 1.02 1.0 1.0 1.01 1.02 1.02

220kV Mahadha

GS BB 1.04 1.04 1.02 1.03 1.03 1.04 1.03

132kV Ibri GS BB 1.01 1.01 1.0 1.0 1.01 1.02 0.98

132kV Jebreen GS

BB 0.98 0.98 0.96 0.97 0.97 0.97 0.96

132kV Al Hayl GS

BB 1.0 1.0 0.97 0.98 1.0 1.0 0.97

132kV Dreez GS

BB 1.0 1.0 0.98 0.98 1.0 1.01 0.97

Table III shows a sample of the calculated short

circuit currents of 2022 system condition. These and

fault currents at other busbars are within the

corresponding thermal busbar fault levels.

Table III: Short circuit levels

Bus Bars Rating

(kA)

Short Circuit

3-Ph

(kA)

1-Ph

(kA)

400kV Ibri IPP BB 63 18.1 20.88

220kV Ibri IPP BB 50 19.4 20.43

220kV Ibri GS BB 50 13.12 13.04

132kV Ibri GS BB 31.5 15.84 18.87

Losses

Real power losses at 2019 peak demand have been

calculated for this option to be included in the lifetime

cost assessment and as a comparison to other feasible

options. The real power losses have been calculated

for the network in the vicinity of the Ibri IPP which is

directly impacted by the additional generation.

Broadly this relates to the 400 kV network from Ibri

to Izki, the 220 kV network to Mahadha from Ibri, the

132 kV network from Ibri to Al-Hayl and Nizwa in

addition to relevant transformers at these locations.

After the connection of the Solar-PV power plant,

the transmission losses have increased from 14.36

MW to 32.13 MW. The major losses increase is

observed in the 400 kV line, the 220 kV line to

Mahadha and 132 kV to Jebreen. This is because, the

majority of generated power (around 1072 MW) of

Ibri IPP is transmitted to Izki and Misfah areas via the

400 kV and 338 MW flow to the direction of

Mahadha GS via the 220 kV line. In addition, the

power flow towards Jebreen and Nizwa GSs has

increased causing more power losses in the long 132

kV lines. The losses are dominated by the 220 km 400

kV overhead line from Ibri IPP to Izki grid station

with losses of 18.8 MW.

F. Financial Assessment

The capital cost assessment of this option in full,

including five year spend phasing, and can be

summarised as a total cost of R.O. 8,284,726.23. The

NPV assessment of the option which accounts for

lifetime costs associated with losses and estimated

operations and maintenance costs over a 40 year

period. The resulting NPV is R.O. -29,463,075.

G. Environmental Considerations Initial site surveys have been conducted which

suggest there is scope to obtain a suitable corridor for

the new circuit. Furthermore, it is assumed at this

time that overhead line can be utilised for the entire

route length. Therefore, there are limited unknown

environmental concerns at this time.

H. Flood Risk Assessment

A flood risk assessment for the Ibri Solar IPP

power station has been conducted with full details.

The assessment has illustrated that there is no

significant flood risk associated with this

development.

I. Safety

There is no significant safety considerations

associated with Option 2. The new line will be

constructed in a new line corridor, offline and away

from other live infrastructure.

J. Dynamic Studies

The compliance with TSS requirements has been

assessed by steady state and dynamic studies for both

peak and off peak demand with full evacuation of Ibri

Solar IPP. The dynamic studies cover the rotor angle

stability, voltage response and frequency response at

both peak and off peak demands. Samples of the

dynamic studies are presented here. Figure 7 shows

the frequency response to a three phase short-circuit

cleared in 120 ms (at the 220 kV line between Ibri

Solar-PV and Ibir IPP GS), at peak demand. Figure 8

shows the frequency response to tripping the 500MW

Solar PV power plant.

7. CONCLUSION

This paper describes the assessment for each

option from different aspects, technically, financially

and risk of deliverability of the Ibri Solar IPP

connection project. The assessment of each option has

been carried out on the basis of the following

performance considerations: deliverability,

Transmission Security Standard (TSS) compliance

technical performance, capital cost, net present value,

environmental considerations, safety and flood risk

assessment. Power losses have also been considered

in the NPV calculation. In addition, the paper

describes the optimal generation connection design

that is respected the TSS criteria. The compliance

with TSS requirements has been proved by steady

state and dynamic studies for both peak and off peak

demand with full evacuation of Ibri Solar IPP power

plant.

The preferred Option 2 has shown to mitigate the

licence condition risks whilst providing a technically

viable, deliverable and financially preferable solution.

It consists of construction of a 220 kV double circuit

10.008.006.004.002.000.00 [s]

50.0004

50.0003

50.0002

50.0001

50.0000

49.9999

[Hz]

132kV Al Kamil BB: Electrical Frequency

132kV Manah BB: Electrical Frequency

220kV Airport Height BB: Electrical Frequency

220kV Barka PS BB: Electrical Frequency

220kV Barka-3 PS BB: Electrical Frequency

220kV Ibri IPP BB: Electrical Frequency

220kV Sohar-1 PS BB: Electrical Frequency



400kV Misfah BB: Electrical Frequency

400kV New Izki BB: Electrical Frequency

400kV Sohar-3 IPP BB: Electrical Frequency

400kV Sur PS BB: Electrical Frequency

132kV Rusail Industrial BB: Electrical Frequency

connection from Ibri Solar IPP to Ibri IPP grid

stations. The NPV assessment of this option which

accounts for lifetime costs associated with losses and

estimated operations and maintenance costs over a 40

year period. The resulting NPV of this option has

been calculated to be R.O. -29,463,075.

8. REFERENCES

[1] OPWP: “Seven Year Statement (2016-2022)”,

www.omanpwp.com

[2] OETC: “Transmission and Dispatch Licence”,

2016, www.omangrid.com

[3] OETC: “PIAD for Connection of Ibri IPP

Generator Project”, Ref: 51/2018, 2012.

[4] OETC-AMP-P-SOP-M-007 Preparing PIADs,

2017.

[5] H. Al-Riyami, O. H. Abdalla, A. Al-Busaidi, A.

Al-Nadabi, M. Al-Siyabi, M. Al-Abri, Z. Al-

Rawahi, J. Dubois, V. Lambillon, Sh. Mirza, and

A. Bastens: “Development of Transmission

System Master Plan of Oman (2014-2030)”,

Paper No. A036, GCC Cigre 2014, Al-

Manamah, Bahrain, November 2014.

[6] OETC: “Five Year Annual Transmission

Capability Statement (2017-2021),

www.omangrid.com

[7] OETC: “The Grid Code”, Version 2, April 2010,

www.omangrid.com.

[8] OETC: Transmission Security Standard, July

2016, www.omangrid.com

[9] O. H. Abdalla, H. Al-Hadi, and H. Al-Riyami:

“Development of a Digital Model for Oman

Electrical Transmission Main Grid”, Proc. of the

2009 International Conference on Advanced

Computations and Tools in Engineering

Applications, pp. 451-456, Notre Dame

University, Lebanon, 15-18 July, 2009,

www.ieeexplore.ieee.org

[10] DIgSILENT 2016 Technical Reference.

Figure 7: Frequency response, at peak demand, to a three phase short of 120 ms, at .

http://www.omanpwp.com/

http://www.omangrid.com/




http://www.ieeexplore.ieee.org/

10.008.006.004.002.000.00 [s]

50.01

49.97

49.93

49.89

49.85

49.81

[Hz]

132kV Al Kamil BB: Electrical Frequency

132kV Manah BB: Electrical Frequency

220kV Airport Height BB: Electrical Frequency

220kV Barka PS BB: Electrical Frequency

220kV Barka-3 PS BB: Electrical Frequency





400kV Misfah BB: Electrical Frequency

400kV New Izki BB: Electrical Frequency

400kV Sohar-3 IPP BB: Electrical Frequency

400kV Sur PS BB: Electrical Frequency

132kV Rusail Industrial BB: Electrical Frequency

Figure 8: Frequency response, at peak demand, to tripping the 500 MW Solar-PV power plant.

planning studies for connection of 500 mw photovoltaic

Documents