Novel Control of a UPFC Connecting the KSA and Kuwait in the GCC Interconnection

International Journal of Automation and Power Engineering (IJAPE) Volume 3 Issue 3 May 2014 www.ijape.org DOI: 10.14355/ijape.2014.0303.01

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Novel Control of a UPFC Connecting the KSA and Kuwait in the GCC Interconnection Tariq Masood*1, R.K. Aggarwal1, Nasser Alemadi4, Suhail A. Qureshi2 D.P. Kothari3

Qatar Petroleum, Doha Qatar; Electrical and Electronics Engineering Department University of Bath, Bath BA2 7AY United Kingdom; Electrical Engineering Department, Qatar University Doha Qatar; Electrical Engineering Department University of Engineering and Technology, Lahore Pakistan; MVSR Engineering College, Hyderabad [email protected];*1 [email protected];1 [email protected] [email protected];2 [email protected];3 Received 29 October 2013; Accepted 1 December 2013; Published 13 May 2014 © 2014 Science and Engineering Publishing Company Abstract

This paper presents a study performed to investigate the steady state and dynamic state performance of the UPFC device in between KSA and Kuwait. The main objective of this work was to identify and determine the UPFC impact on GCC power grid operations and control for different transmission contingencies. This study aims to develop a model and to simulate for different operating and control parameters with and without UPFC system, to evaluate the effectiveness of the UPFC device on the GCC power grid. The simulated results presented herein clearly demonstrate enhancement to power flow, power angle and stability margin in the GCC interconnection. This work also shows additional benefits principally, reduction of losses, increase of the load ability, and enhancement of the sustainability of the GCC interconnection.

Keywords

UPFC Controllability; Gain Control; Gain Measurement; PI Control Design; Control System Analysis; Controllability; Gain Measurement; Matlab

Introduction

Based on various statistics and surveys, the GCC (Gulf Cooperative Council) has been playing a crucial role globally. In particular, the GCC integrated power grid has developed a center of large numbers of industrial and domestic activities which are leading to massive economic growth and benefits for its inhabitants, more so, due to a population growth, induction of new oil and gas industries and other individual activities in the GCC countries. These are the main reasons as to why the electricity demand has increased dramatically. It has been determined and identified through various analyses that current demand for GCC power

consumption is about 60 GW. It is projected that the demand will reach 180 GW within the next 25 years. In order to maintain reliable, sustainable, and well controlled power transfer between the GCC countries, it has been decided to interconnect all the GCC countries [2]. The interconnection is divided into two basic segmental links, neighbour to neighbour and common-link topologies.

• In the 1st stage, United Arab Emirates (UAE) and Oman will be interconnected through “neighbor to neighbor” sophisticated control topology.

• In the 2nd stage, KSA, Bahrain, Qatar and Kuwait will be interconnected through “common-link” control topology and this is also called the Northern System.

• In the 3rd stage, “common-link” topology will demonstrate UAE national grid and Oman northern grid interconnection; this is called the southern system.

• In the 4th stage, the southern and the northern power systems will be interconnected through hybrid link sophisticated control topologies.

In order to enhance these interconnected topologies, numerous power system studies have been carried to evaluate the technicalities and economic importance of theses interconnection. Based on the findings, the areas that require additional FACTS devices at GCC power grid have been identified. The studies clearly demonstrate that the FACTS controllers are strong a candidate in the technology options. Essentially, these devices will deliver the following benefits to the GCC power grid:

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• Enhanced power transfer capability, reliability, controllability, angle and voltage stability

Fig.1 demonstrates the total power generation and distribution in between the GCC countries and Fig.2 shows the interconnections within the GCC power grid. Prime contributions of this research work are as listed below.

Al FadhliInterconnection

310 km

Bahrain 600 MW

UAE900 MW

Oman400 MW

GhunanInterconnection

113km

SalwaInterconnection

290 km

Al-sila & Al-FuhahInterconnection

150 km

Legends:400kV Lines220kV Lines

Qatar750 MW

SSSC

STATCOMUPFC

RTURemote

Telemetry Unit

Saudi Arabia1200 MW

HVDCBack-to-Back

Kuwait1200 MW

BLOCK.2Current Measured1.Al-Fuaha Subs2.Salwa Subs3.Al-Zour Subs4. Al-Fadhili Subs

BLOCK.4Reference Iq1.Al-Fuaha Substation2.Salwa Subs3.Al-Zour Subs4. Al-Fadhili

BLOCK.3Reference Voltage 1.Al-Fuaha 2.Salwa 3.Al-Zour 4. Al-Fadhili 1.0PU (400KV)

BLOCK.1Voltage Measured1.Al-Fuaha Subs 2.Salwa subs3.Al-Zour Subs4. Al-Fadhili 1.0PU (400KV)

BLOCK.5Sending EndVoltage DeviationCurrent DeviationReceiving EndCurrent DeviationVoltage Deviation

FIG.1 UPFC SCHEMATIC CONTROL TOPOLOGY AND POWER

SHARED

Al-Wasset substation

(Oman)

Al-Ouhah substation

(UAE)

Doha South substation

(Qatar)

Al-Ghunan substation (Bahrain)

Kuwait (2500 MW) LegendsOLTC TransformerShunt ReactorHVDC ConverterOverhead LinesUnderground CableSubmarine cable

Kuwait 275 kV 6 circuits network

KSA 220 kV

network380 kV network

380kV 60Hz2x125MVAR400kV 50Hz

2x125MVAR400kV

4x125MVAR400kV

4x125MVAR400kV

2x125MVAR3x300MVAR

1x125MVAR400kV

2 circuits 220kV

66kV network

4 circuits 220kV

132kV network

132 kV network

132kV network6 circuits 220kV

6 circuits 220kV

2x125MVAR4x300MVAR

400kV

125MVAR400kV

G1 G2 G3

2x125MVAR

Al-Jasra substation (Bahrain)

Al-Fadhili substation

(KSA)

UPFC DeviceLocation

Al-Zoursubstation

(KSA)

FIG.2 GCC POWER GRID SINGLE LINE DIAGRAM

• Investigation of the UPFC impact on GCC power grid with anew PI control technique

• Investigation of a comparison of GCC power grid operation with and without UPFC

The UPFC implementation will enhance power system network controllability and power flow, improved voltage profile, and enhance power system network stability margin. This paper is structured as follows: in sections I, II, III and IV, the research study introduction, power system background, UPFC controller selection process and UPFC reinforcement plan are described. In sections V, VI and VII, UPFC model operational strategy, model case study and UPFC operating performance outcomes are demonstrated. In sections VIII and IX, UPFC discussions & conclusion are presented.

GCC Power System Background Information

The GCC power network is classified and implemented into numerous strategic power system operational directions to meet reliable and sustainable industrial and domestic customers’ requirements on the GCC power grid. Fig.2 demonstrates the growing domestic and industrial power requirements and enhanced reliable and sustainable power system operation on the GCC power grid. In this figure:

• The 1st segment shows a double-circuit 400kV/50Hz line stretching from Kuwait to the KSA.

• The 2nd segment shows a back-to-back HVDC 380kV KSA link introduced at Fadhili substation (KSA) to convert 60Hz to 50 Hz frequency in order to synchronize to the GCC power systems network.

• The 3rd segment shows a double circuit 400kV/50Hz overhead line stretching (and partially connected with submarine link) from the KSA to the Bahrain

• The 4th segment shows, a double circuit 400kV/50Hz line stretching from the KSA to Salwa Substation

• The 5th segment shows a double circuit 400kV/50Hz line stretching from the KSA to the Qatar (Doha South substation)

• The 6th segment shows a double circuit 400kV/50 Hz line stretching from the KSA to the United Arab Emirates.

• The 7th segment shows a double and a single circuit 220kV/50Hz line stretching from the United Arab Emirates to Oman. (Al-Mohaisen, CIGREE], Al-Asaad, CIGREE]

UPFC Controllers Selection Process

Based on comprehensive feedback received from the

International Journal of Automation and Power Engineering (IJAPE) Volume 3 Issue 3 May 2014 www.ijape.org

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highly skilled personnel from industry and academia, a strong portal is developed. These inputs are integrated by using Wideband Delphi technique (wikipedia.org) in order to investigate generate and allocate near optimal values of significant and submission criteria(s) as established in Table I, II and III. Equation (1) represents the mathematical method to determine CRVZ value of each FACTS device derived from its significance and submission criteria(s). Equation (1) also indicates the functionality of the measurement model (Andrew Stellman, ISBN: 0-596-00948-8)

CRVZ =

� Xn100

12

𝑛𝑛=1xY � X1

100. Y1 + X2

100xY + X3

100. Y2 … . + X12

100. Y3� (1)

Where:

CRVZ (credible value)

z (subscript): SSSC, UPFC, IPFC, STATCOM etc

X1 to X12 (Table I indicates the significant values of the FACTS devices)

Y (Submission criteria of each segment of design significant as shown in Table II)

Tables IV and V show the calculated score CRVZ of each device based on the criteria as stated in Tables I & II, using equation (1). If the summation score in tables IV and V of any device is above 65, it means good submission and 80 is significant (strong candidate). The Wideband Delphi technique is thus very effective in providing a basis for near optimization of important supporting parameters in order to formulate selection process of FACTS devices more pragmatically. Based on the above mentioned calculation score, the UPFC device attained a 73.55 weighted score and was selected to be implemented in between the Kuwait and the KSA ( B. Nagaraj, IEEE), (Bin Zuo, IEEE).

TABLE I FACTS DEVICES SELECTION CERITERIA

Criteria B 1…12 Y 1…12 Equation (1) Weighted Score

Control Significance 10 80 (B1/100).Y1 8 Control Integration 11 80 (B2/100).Y2 8.8

Design Capacity 8 65 (B3/100).Y3 5.20 Reliability 12 80 (B4/100).Y4 10.40

Maintenance frequency 13 80 (B5/100).Y5 8.45 Availability for trial 11 80 (B6/100).Y6 8.8

Refuse disposal 7 65 (B7/100).Y7 4.55 Monitoring equipment 8 65 (B8/100).Y8 5.2

Simulation results 6 65 (B9/100).Y9 3.9 Capex 4 65 (B10/100).Y10 2.6 Opex 6 65 (B11/100).Y11 3.9

Post Installation Support 4 65 (B12/100).Y12 2.6 Total 100 825 - 73.55

TABLE II.FACTS DEVICES SELECTION CERITERIA SCOREBOARD

Criteria Description Submission Score No submission of any consequence 0

Some submission but unacceptably low 20 Satisfactory 50

Good submission 65 Significantly above the minimum acceptable.

Considered a strong candidate. 80

Exceptional submission 100

TABLE III.FACTS DEVICES ESTIMATED SCORE

Device Submission Score Device Submission Score TCVR 46.5 STATCOM 67

TCPAR 49.5 SVC 58 UPFC 73.55 GCSC 41.5 IPFC 59 TSSC 36 SSSC 68.8 TCSC 43

TABLE IV FACTS DEVICES CALCULATED SCORE

Static Shunt Compensator Static Series Compensator

STATCOM SVC GCSC TSSC SSSC

S.No Weighted

Score Weighted

Score Weighted

Score Weighted

Score Weighted

Score

1 6.7 5.8 4.2 3.6 6.7 2 7.4 6.4 4.6 4.0 7.4 3 5.4 4.6 3.3 2.9 5.4 4 8.0 7.0 5.0 4.3 8.0 5 8.7 7.5 5.4 4.7 8.7 6 7.4 6.4 4.6 4.0 7.4 7 4.7 4.1 2.9 2.5 4.7 8 5.4 4.6 3.3 2.9 5.4 9 4.0 3.5 2.5 2.2 4.0

10 2.7 2.3 1.7 1.4 2.7 11 4.0 3.5 2.5 2.2 4.0 12 2.7 2.3 1.7 1.4 2.7

Total 67.1 58.0 41.7 36.1 67.1

TABLE V. FACTS DEVICES CALCULATED SCORE

Static voltage and phase Angle control

Combined Compensator

Static Series Compensator

TCVR TCPAR UPFC IPFC TCSC

S.No Weighted Score

Weighted Score

Weighted Score

Weighted Score

Weighted Score

1 4.7 5.0 8 5.9 4.3 2 5.1 5.4 8.8 6.5 4.7 3 3.7 4.0 5.20 4.7 3.4 4 5.6 5.9 10.40 7.1 5.2 5 6.0 6.4 8.45 7.7 5.6 6 5.1 5.4 8.8 6.5 4.7 7 3.3 3.5 4.55 4.1 3.0 8 3.7 4.0 5.2 4.7 3.4 9 2.8 3.0 3.9 3.5 2.6

10 1.9 2.0 2.6 2.4 1.7 11 2.8 3.0 3.9 3.5 2.6 12 1.9 2.0 2.6 2.4 1.7

Total 46.6 49.6 73.55 59.0 42.9


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System Reinforcement Plan

In order to identify the reactive power compensation requirements between KSA and Kuwait, various thorough power system analyses and surveys were conducted successfully. In this study, recommend- tions were provided to resolve the system’s normal, single contingency and double contingency problems at Kuwait and KSA substations as well as the positive impact on power system stability at downstream Bahrain, Qatar, UAE and Oman power exchange inter-ties. Based on these analyses, the following reinforcement plans for the Kuwait and KSA are thus recommended:

• High capacity 1020MVA, 400kV line between Kuwait and KSA stations

• A +/-500 MVA UPFC at the Kuwait substation (Al-Zour) fully utilizing the high capacity of the 400kV line, which provides dynamic voltage support and control by replacing several mechanical switched capacitors in the area.

• Series reactors may cause to restrain loadings on existing thermal-limited at Kuwait and KSA facilities.

Operations Strategy

Voltage Control

During any system operations instability, mechanically switched shunt capacitors or reactor banks and their associated controls are usually slow to respond and the control offered is a vulnerable control. To resolve such a situation, the UPFC offers a predetermined reactive power margin to maximize the shunt converter’s dynamic reactive power reserve for system contingency conditions (Ch. Chengaiah, IEEE). Moreover, it ensures that the controllable reactive power range of the shunt converter (+/-500) i.e. a maximum control range of 500MVar, is available at all times to compensate for dynamic system disturbances in between KSA and Kuwait.

Power Flow Control

With system facilities at the Kuwait substation (Al-Zour), the 400kV line loading needs to be maintained at a level which would minimize the system losses. The study indicates that during peak or near peak load conditions, a 1200MW line loading will minimize the losses. The UPFC is thus necessary to reduce the line loading by injecting reactive power. Hence reactive power flow and directions are monitored to maintain the dynamic reactive power

margin of the shunt inverter. Series power flow control becomes more important during contingency conditions (Chiha, J. ISCCSP). Under severe contingency conditions, the UPFC will control KSA line which will be capable of transferring 4800MVA.

UPFC Model Case Study

Appendix 1 demonstrates the UPFC controller for the Kuwait substation which has been designed to meet the specified system requirements, to provide fast reactive shunt compensation with a total control range of +/-500MVAR and control the power flow in the 400kV high capacity transmission line, forcing the transmitted power under contingency conditions go up to 1500 MVA. In order to increase the system reliability and provide flexibility for future system changes, the UPFC controller has to be configured in such a way as to allow self-sufficient operations of the shunt converter as an independent STATCOM and series converter as an independent Static Synchronous Compensator (Jia-jun & Mei-juan, IEEE). These converters can be coupled to deliver either shunt only or series only compensation over a double control range. Fig.1. shows 1200 MW power exchange from Kuwait to KSA on the GCC Power grid. The actual control algorithms that govern the instantaneous operations of both converters are performed in the real-time control, employing multiple digital signal processors. The real time controller communicates the pole via the valve interface (Jose.P.Theratti, IEEE) . When both converters (SSSC+STATCOM) are operating in a UPFC mode, the shunt converter first operates and controls the bus Al-Zour (Kuwait) voltage by generating or absorbing reactive power. In fact it also allows transfer of active power through the DC bus. Hence the reactive power is increased or reduced by varying the DC bus voltage.) Secondly, operating in UPFC mode of operations, the series injected voltage is controlled by changing the Sigma conduction angle, which leads to generating higher harmonic content compared to the shunt converter.. The likely power flow through the AL-Fidhili bus KSA when there is zero voltage generated by the series converter is: P =900MW (7.5pu) and Q = -0.4pu. Here, P and Q magnitudes, phase angle and series injected can vary in UPFC mode of operations. To keep the ideal condition of UPFC operations, it is very important to keep the series injected voltage at maximum value (0.1pu) as well as to change the phase angle from zero to 360 degrees to meet operational requirement as demonstrated in Fig.6 (Tariq Masood, IEEE).


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UPFC Operating Performance Observations

UPFC Changing Real and Reactive Power

Fig.3 demonstrates the GCC power network operational trends in between Kuwait and the KSA without UPFC device operations. In Fig.4, the UPFC shows a zero (0) voltage and active power flow from KSA on the line near the N (natural) to the Kuwait. Equation (2) demonstrates the exchange of real and reactive and Equation (3) indicates the uncompensated network as indicates in Fig.3 proves the network operating trends without UPFC device. Equation (4) shows the compensated network and Fig.4 proves the network performance with UPFC device in between Kuwait and KSA.

00 , ,S RV V V V Vpq Vpqδ ρ= ∠ = ∠− = ∠− (2)

For the uncompensated system Vpq = 0 2 2

0 0sin , (cos 1)RV VP P Q QX X

δ δ= = = − = − (3)

For the compensated system

0

0

,

sin( )

cos( )

pqR

pq

pq

V V VP jQ V Hence

jXVV

P PX

VVQ Q

X

δ ρδ

δ ρ

δ ρ

− ∠− + ∠− − = ∠−

= − −

= − −

(4)

Following are operating performance observations of the UPFC.

• The first waveform of the UPFC shows measured power (yellow trace) against the reference power (magenta trace). Initially active power was 9pu from 0.1s to 0.25s and gradually ramped up to 12pu from 0.26 to 0.5s and stayed there rest of the operations.

• The second waveform of the UPFC shows the measure reactive power (yellow trace) against the reference reactive power (Magenta trace). Initially reactive power was zero from 0.1s to 0.5s against the reference value. It ramped up from 0 to 2pu from 0.5s to 0.65s against the reference value and it was stayed there rest of the operations.

• The third waveform indicates the L1, L2 and L3 real power variation; it was steady from 0.1 to 0.25s and ramped up from 0.27 to 0.5 from KSA to Kuwait.

• The fourth waveform indicates the L1, L2 and L3 reactive power variation it was steady from 0.1 to 0.55s and ramped up from 0.57 to 0.65 from KSA to Kuwait.

FIG.3 INDICATES THE NETWORK OPERATING TRENDS

WITHOUT UPFC DEVICE

FIG.4. INDICATES THE NETWORK CONTROL AND OPERATING

TRENDS WITH UPFC DEVICE

Shunt Part of the UPFC

Fig.5 shows the series part of the UPFC operations at Al Fadhili interconnection from the Kuwait. The following are operating performance observations of the shunt part of the UPFC. The shunt part of UPFC loop equation may be written in vector form as (Tariq Masood ICEE).

1 ( )sabc abc abc abc

s s

Rd i i E Vdt L L

= − + − (5)

RS and LS present the transformer losses Eabc AC side phase voltage and Vabc the STATCOM side phase voltage and iabc are three phases current.

The STATCOM output cos( )a dcE kV wt α= + (6)

• The first waveform primary voltage in magenta trace and current in yellow trace are both in phase. The second voltage shown in cyan trace, varies from 0.1s to 0.55 s randomly and then stabilizes from 0.6 to 0.8s.

• The second waveform shows the measured Vdc; initially it was zero and ramped up 33kV within


96

0.015s and then ramped down at 11kV. After a couple of oscillations, it stays at 20kV for the rest of the operations.

• The third waveform shows the measured reactive power (yellow trace) against the reference reactive power (magenta trace). The measured reactive power takes a couple of oscillations from 0 to 0.1s to ramp up to 0.55pu and stays there for 0.55s and then ramps down to zero and stays there for the rest of the operations. Initially, the Q reference was zero from 0.3s and ramped up to 1pu and dropped at zero after 0.5s.

• The fourth waveform shows the measured voltage (yellow trace) against the reference voltage (Magenta trace). Initially, the measured voltage oscillates for 0.15s and stays at 1.15pu for 0.55s and is then normalized at 0.65s.

FIG.5. INDICATES THE STATCOM CONTROL AND OPERATING

PARAMETERS

Series Part of the UPFC

Fig.6 shows the series part of the UPFC operations at Al Fadhili interconnection from the KSA. The following are the operating performance observations of the series part of the UPFC. 1 1V θ∠ and 2 2V θ∠ are midpoint voltages on Al-Fadhli interconnection of the SSSC, and the inj injV θ∠ represents the voltage injected in between KSA and Kuwait by the controller. This is similar to

shunt part of the UPFC (Tariq Masood, ICEE). Equation (7) demonstrates the capacitive and Equation (8) inductive mode of SSSC operations in between Kuwait and KSA.

( )90

Q S SV VV I e Ij X

δλλ

− ° ∠ −= ⇒ =

− (7)

( )90

Q S SV VV I e Ij X

δλλ

+ ° ∠ −= ⇒ =

+ (8)

FIG.6. INDICATES THE SSSC CONTROL AND OPERATING

PARAMETERS

• The first waveform shows the injected voltage in quadrature of the line current. Injection voltage was +/- 0.05pu for 0.33s and dropped from 0.05 to 0.021pu; it then stayed there from 0.33 to 0.58s and ramped up from 0.02pu to 0.025pu and stayed at that level for the rest of the operations.

• The second waveform shows the measured three phases of current; initially the magnitude was +/- 0.9pu form 0.38s and it ramped up from 9.0pu to 10pu and stayed at that level for the rest of the operations.

• The third waveform shows the measured injected voltage against the reference voltage. Initially, the measured voltage ramped up from 0 to 0.1pu from 0.0 to 0.18s and ramped down from 0.1 to -0.5pu, stayed there from 0.2 to 0.37s and again ramped up from negative to positive 0.03pu and stayed at that level for the rest of the operations.

• The fourth waveform shows the Vdc; initially the DC voltage ramped up from zero to 23kV and then ramped down to 17kV; it oscillated from 0 to 0.1s


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and then, after certain period it stayed at 2kV for the rest of the operations.

• The fifth waveform shows the 3phase real power randomly being transmitted from Kuwait to KSA.

• The sixth waveform shows the 3 phase reactive power randomly being transmitted from Kuwait to KSA (Tariq Masood, 7th IEEE GCC).

Novel Control Pattern of UPFC Device

Fig.1. indicates the control schematic of UPFC device. This schematic comprises of measured and reference values control blocks of the UPFC device operations. The first control block.1 will collect the measured voltage data from four substations as mentioned in the schematic. The second control block.2 will collect the measured current data from the same substations. The third (block.3) and fourth (block.4) will indicates the defined reference values of current and voltage of the four substations. These measured and reference values are plugged in control block.5 to determine the deviation(s) of each defined parameter. These deviations could be +/- (2, 4 &6)% and will be sent to control topology for final action based on the deviations, however the control loop will respond to inject or absorb reactive power to/from the GCC power grid as demonstrated below. These values are adjusted based on corresponding PI control values as demonstrated in Table X and Fig.7. Each control boundary tuned by introducing new PI control parameters in order to adjust minimum, medium and maximum reactive power compensation.

FIG.7. INDICATES THE PI CONTROL VALUES

Based on the research study, the concept is to develop and customize and optimize the UPFC controller operating and control system by incorporating new control compensation technique’s parameters. In this method, the control system has three operating and control boundaries in order to run the system successful. In the first operating scenarios the UPFC

controller can be adjusted +/- CL3 (inductive)/CC3 (capacitive) at minimum to eliminate+/- 2% power deviation by incorporating first set of P & I values(P=0.32; I= 0.6 and SP=400kV) as demonstrated in Fig.7 & 8.

• In the first waveform power_reference (magenta color) against the power_measured (yellow color) indicates the 2% deviation and after injection of reactive power it took 0.03s to eliminate the deviation and establish. The total power to be transmitted 1200MW (12pu) on the GCC power grid. By introducing 2% deviation the total power will be delivered 11.76pu at receiving end without injection of reactive power.

• The second waveform shows the Q_ reference (magenta color) and Q_ measured (yellow color). To eliminate 2% deviation 0.66pu reactive power to be injected in order to reduce the line impedance to deliver more power. The yellow trace indicates the 0.66pu reactive power was injected in the line within 0.11s, however the power deviation has been addressed by transferring (1200MW) 12pu to the receiving end [16],.

FIG.8. INDICATES THE MINIMUM COMPENSATION

In the second operating scenarios the UPFC controller can be adjusted +/- CL33 (inductive)/CC33 (capacitive) at medium to eliminate +/- 4% power deviation by incorporating second set of P & I values(P=0.36; I= 0.8 and SP=400kV) as demonstrated in Fig.7 & 9.

• In the first waveform power reference (magenta color) against the power measured (yellow color) indicates the 4% deviation and after injection of reactive power it took 0.055s to eliminate the deviation. The total power to be transmitted 1200MW (12pu) on the GCC power grid. By introducing 4% deviation the total power will be delivered 11.52pu at receiving end without injection of reactive power.

• The second waveform shows the Q_ reference (magenta color) and Q_ measured (yellow color). To eliminate 4% deviation 1.33pu reactive power to be

0

100

200

300

400

500

600

700

800

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49

CO

NTR

OLL

ER O

UTP

UT

CONTROLLER ITERATION

UPFC Control Configuration to Maintain line Voltage 400KV I=.6

I=.8

I=.9

I=1

I=1.1

2% power deviation introduced

To eliminate above deviation 0.66pu Q injected


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injected in order to reduce the line impedance to deliver more power. The yellow trace indicates the 1.33pu reactive power was injected in the line within 0.16s and the power deviation has been addressed by transferring (1200MW) 12pu to the receiving end.

FIG.9. INDICATES THE MEDIUM COMPENSATION

In the third operating scenarios the UPFC controller can be adjusted +/- CL333 (inductive)/CC333 (capacitive) at maximum to eliminate +/- 6% power deviation by incorporating second set of P & I values(P=0.38; I= 0.9 and SP=400kV) as demonstrated in Fig.7 & 10.

• In the first waveform power reference (magenta color) against the power measured (yellow color) indicates the 6% deviation and after injection of reactive power it took 0.078s to eliminate the deviation. The total power to be transmitted 1200MW (12pu) on the GCC power grid. By introducing 4% deviation the total power will be delivered 11.28pu at receiving end without injection of reactive power.

• The second waveform shows the Q_ reference (magenta color) and Q_ measured (yellow color). To eliminate 6% deviation 2.0pu reactive power to be injected in order to reduce the line impedance to deliver more power. The yellow trace indicates the 2.0pu reactive power was injected in the line within 0.18s and the power deviation has been addressed by transferring (1200MW) 12pu to the receiving end.

FIG.10. INDICATES THE MAXIMUM COMPENSATION

The controller will oscillate and inject or absorb controlled reactive power based on corresponding PI

control values of each operating boundary as demonstrated in Tables X.

Discussion

The UPFC model’s results demonstrate a viable positive impact on the GCC power grid operations and control in order to exchange 1200MW power within the GCC power grid to secure sustainable power system operations and control at different operating conditions. The UPFC model’s new operation and control system optimization technique shows the importance of FACTS devices at different locations on the GCC Power grid.

Selection Model

The UPFC control device was identified as the most suitable candidate based on the Wideband Delphi calculation values estimation technique. As demonstrated in section III, the wideband Delphi technique is ideally suited to evaluate the integrity of the various FACTS devices pragmatically. The integrity of each device setup based on expert staff members input. These staff members are high recognized inside the industry and academia. Based on calculations emanating from the aforementioned technique, the selection process values are described in Tables IV and V.

Controller Significance

Based on the research study, the concept is to develop and customize the UPFC controller operating and control system by incorporating new control compensation techniques parameters. In this method, the control system has three operating and control boundaries in order to run the system successful. The UPFC controller can be adjusted at minimum (+/- CL3/CC3), medium (+/- CL33/CC33), and maximum (+/- CL333/CC333) at both capacitive and inductive modes of compensation operations. This controller has a capacity and capability to control the oscillation up to +/- 6 % at the both sides (sending and receiving ends) of power system operations. Based on the voltage deviation the controller will inject or absorb the reactive power from the AC power system. This controller oscillates from +/-2% to +/-6% in order to maintain reactive power compensation on both sides of the transmission lines. These control boundaries will communicate and adjust the reactive power based on sending and receiving end voltage deviation. The controller will oscillate and inject or absorb controlled reactive power based on corresponding PI control values of each operating boundary as demonstrated in






99

Tables X. Each control boundary tuned by introducing new PI control values in order to adjust minimum, medium and maximum reactive power compensation.

Conclusions

The UPFC model developed herein demonstrates the characteristic and operating performance of the UPFC in between the Kuwait and the KSA. The results attained by the installation of this UPFC device on the GCC power grid gives very promising results after implementing novel control topology. It has the unique capability to provide independent and synchronized control for the real and reactive power flow, as well as regulating the bus voltage as defined. These results are obtained by implementing novel control and operating limits minimum, medium and maximum) compensation factor. It has the flexibility to run independently, STATCOM and SSSC compensation and enhanced control to regulate the bus voltage. The successful UPFC installation between Kuwait and KSA has also proven the concept of operating two or more voltage source converters from a common dc bus, enabling the converters to exchange real power amongst them. Importantly, it has the capability of providing two dimensional compensations by injecting real power as well as reactive power into the transmission line and this clearly justifies its practical implementations.

Appendix

The UPFC control schematic parameters in between KSA and Kuwait

ACKNOWLEDGMENT

I extend my special gratitude to the, Adjunct. Prof. Dr Abdel-ETY Edris and Executive Director Senior Advisor with Quanta Technology in Oakland for their unprecedented support and value added contribution to make this study a great success.

TABLE VI FACTS DEVICES FINAL LOCATION AND DEFINED POWER AND SYSTEM’S VOLTAGE

Country Id

Country Name

Power ID

Mw Voltage ID

Line Voltage kV

C1 Kuwait PC1 1200 V1 400 C2 Saudi Arabia PC2 1200 V2 400 C3 Bahrain PC3 600 V3 400 C4 Qatar PC4 750 V4 400 C5 Oman PC5 400 V5 220

C6 United Arab

Emirates PC6 900 V6 400

C6 United Arab

Emirates PC7 400 V7 220

UPFC Technical data

TABLE VII POWER, VOLTAGE AND FREQUENCE

Countries Power Exchange, Voltage & Frequency

Power exchanged from Kuwait to main transmission line 1200MW, 400kV, 50Hz

Power exchanged from Kingdom Saudi Arabia to main transmission line

1200MW, 400kV, 60Hz DC link to convert 60Hz to

50 Hz frequency

TABLE VIII EXISTING REACTIVE POWER AND DISTANCE

Existing Power System Reactive Power

Distance

Reactive Power Demand in the KSA (Al-Ghunan

substation) 500Mvar

KSA (Al Fadhili substation to Al-Ghunan Substation) within

KSA =114 kilometer Reactive Power Demand in the Bahrain (Al Jasra

substation) 850Mvar

KSA (Al-Ghunan Substation to Slawa substation) in the (Qatar) =

288 Kilometres Reactive Power demand

in the KSA (Al-Salwa Substation)

500Mvar Qatar (Slawa Substation to Doha South Substation) within Qatar =

97Kilometers Reactive Power demand

in the Qatar (Doha South Substation)

250Mvar

TABLE IX MULTIVARIABLE CONTROLLER’S CONFIGURATION:

UPFC LOCATION: IN Between KSA and

Kuwait

Iq regulator: Kp: 10 dB; Ki 34 dB

CC2 and LC = minimum compensation capacitive or

inductive +/-2%

Rated UPFC: +/- 500 MVAR

DC balance regulator ; Kp:

0.0017 dB; Ki:0.017 dB

Ref_V: 1.0 pu (400KV)

CC22 and LC22 = medium compensation capacitive or

inductive +/-4%.

P (proportional gain) = 0.55 and 1.32

I(integral time) = 0.65, 0.85, 0.95, 1.01, 1.15 D (derivative time)

None

Droop: 0.033 pu/100MVA; Kp: 15dB; Ki: 3400/3600 dB

CC222 and LC222 = full compensation capacitive or

inductive +/-6%.

Abbreviations and Acronyms

TERMS : FUNCTIONS KSA Kingdom Saudi Arabia CC3,

CC33,CC333 : UPFC 1st, 2nd and 3rd capacitive control pattern

CL3,CL33, CL333 : UPFC 1st, 2nd and 3rd inductive control pattern

PI : Proportional Integral control

GCC : Gulf cooperative Council (Qatar, Oman, Bahrain, Kuwait and Saudi Arabia)

V_ reference : Ref_voltage as defined in the control block Va : Primary voltage on the GCC power grid Ia : Primary current on the GCC power grid

Vdc : Dc voltage across the capacitor Vac : AC voltage on the GCC power grid

QMvar : Reactive power in MVAR Va : Secondary side of power system

Alpha : Firing angle of thyristor control CAPEX : Capital expenditure OPEX : Operating expenditure

Ki : Integral Gain to adjust UPFC controller Kp : Proportional gain to adjust UPFC controller


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APPENDIX NO.1

TABLE X FACTS DEVICES FINAL LOCATION AND DEFINED CAPACITIVE POWER EXCHANGE

DEVICE ID

DEVICE NAME

COUNTRYID STATIONID

CAPACTIVIE CONTROL ID

P (POR)

I (INT)

REFERENCE VOLTAGE(KV)

MEASURED VOLTAGE (KV)

ERROR IN %

UP UPFC S6/C6 CC3 0.32 0.6 400 392 -2% UP UPFC S6/C6 CC33 0.35 0.8 400 384 -4% UP UPFC S6/C6 CC333 0.40 0.9 400 376 -6% UP UPFC S6/C6 LC3 0.32 0.6 400 408 2% UP UPFC S6/C6 LC33 0.35 0.8 400 416 4% UP UPFC S6/C6 LC333 0.40 0.9 400 424 6%

275KV Kuwait Power

Distribution Network (6 Circuits)

Converter No.1

Total Power Generation 2500 MW

275KV, 50 HZ

SSSC Converter No.2 connection at Al-Zour

Substation

400KV 50HZ2 X 125MVAR

292KM

OLTCOnline tap changer

transformers



220KV Kingdom Saudi Arabia

Power Distribution Network

380KV Kingdom Saudi Arabia

Power Distribution Network

(7Circuits)

Iq reactive current will flow from SVS to AC

system if V2>V1Iq reactive current will flow from AC to SVS

system if V1>V2θ∠1V

φ∠2V

Proposed UPFC controller to be installed in between Kuwait and Kingdom Saudi Arabia

STATCOM Converter No.1 connection at Al-Fadhili

Substation

Back to Back Converters

To Bahrain, Qatar, UAE and Oman

Positive sequence

fundamental line voltage calculator

Slope settingK Slope

K1 -K2/S

Instantaneous reactive current

calculator

Error amplifier(PI Controller) Vref + iqRef +

+ φ

φ

α iq -V -

SSSC control system

Pole control

Pole control

Pole control

Pole control

Pole control

Pole control

Pole control

Pole control

Signal from CT

Signal from PTConverter No.2

STATCOM control system

Pole control

Pole control

Pole control

Pole control

Pole control

Pole control

Pole control

Pole control

Signal from CT

Signal from PT

Phase Lock loop

Voltage magnitudeCalculator

Polarity detector

Error amplifier(PI Controller) Vq Ref + +

α∆

V -

Phase shifter +/- 90 deg

Phase locked loop+

αθ ∆+

θConverter gate

pattern logic

Converter gate pattern logic

Al-Zour Substation

Al-Fadhili Substation

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1-10 http://en.wikipedia.org/wiki/Wideband_delphi

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Tariq Masood (SM’03) received the M.Eng. in electrical power system engineering from University of Bath, Bath, UK., in 2007 and Ph.D. in electrical engineering from the University of Bath, Bath, UK. He joined the Qatar Petroleum since 1997 where he is

currently Production Data analyst. He is/has been on several

production department technical and management committees’ member. He has published 15 technical papers in IEEE conferences. He is the Secretary/Treasurer of IEEE Qatar Section. He received several awards in recognition of his outstanding performance and dedication to improve Qatar Petroleum production Operations and control. He was the secretary for the GCC oil producing companies (QP-Qatar, PDO-Oman ARAMCO-Saudi Arabia, KOC-Kuwait, TATWEER-Bahrain, and ADNOC-United Arab Emirates) technical committee in 2008 and 2011.

Raj Aggarwal (SM’91) received the B.Eng. and Ph.D. degrees in electronics and electrical engineering from the University of Liverpool, Liverpool, U.K., in 1970 and 1973, respectively. He then joined the University of Bath, Bath, U.K,., where he is

currently Professor of Electrical Engineering and Head of the Electrical Power and Energy Systems Group, Department of Electronic and Electrical Engineering. Professor Aggarwal is/has been on several Institute of Engineering and Technology and CIGRÉ committees and has been a member of the EPSRC Scientific Advisory committee on energy. In 2005, he was awarded the D.Eng. degree from the University of Liverpool for his original and outstanding contribution to electrical power systems. He has published many technical papers and is the recipient of several Institute of Engineering and Technology premium awards for papers published.

Suhail Aftab Qureshi received the degree of Master’s and Ph.D. in Electrical Engineering from the University of Manchester, Institute of Science and Technology (UMIST), U.K, England, during the year 1989 to 1993. During this

time he also secured three times ORS (Overseas Research Student) Award from UK, England. In 2005 he was also awarded Best University Teacher Award from Higher Education Commission (HEC). He is currently working as Professor and Head of the Power Division in Electrical Engineering Department, UET Lahore. He has presented more than 100 research papers in different national/international conferences and journals. He also has completed more than 125 M.Sc. theses. He is also author of two books in “Power Distribution System” and “Power System Transients” in the years 2009 and 2011 respectively. He has been elected many times at different forums to serve the Engineering community. He was elected 9-times as president of Teaching Staff Association (TSA) in UET, Lahore. He was elected and served as member syndicate and senate of UET a number of times. He has also served for the cause of engineers in Pakistan Engineering Council (PEC) for 6-Years.

Nasser A. Al-Emadi received the B.S. and M.S. degrees, both in electrical engineering, from Western Michigan University, Kalamazoo, in 1989 and 1994 respectively, and the Ph.D. degree, from Michigan State University, East Lansing, in 1999. He is


102

currently an Assistant Professor at the department of Electrical Engineering in Qatar University. His research interests include operation, planning, and control of Power systems, as well as stability and control of AC machine.

D.P. Kothari, obtained his B.E [Electrical], M.E. [Power Systems] and Doctoral Degree in Electrical Engineering from the Birla Institute of Technology & Science, Pilani. His fields of specialization are Optimal Hydro-thermal Scheduling, Unit

Commitment, Maintenance Scheduling, Energy Conservation (loss minimization and voltage control), and Power Quality and Energy Systems Planning and Modeling. Prior to his assuming charge as Vice Chancellor of VIT University, he was

the Professor of Centre for Energy Studies, Indian Institute of Technology, New Delhi. He also served as Director i/c, IIT, Delhi [2005], Deputy Director [Administration], IIT, Delhi [2003-06], Principal, Visvesvaryaya Regional Engineering College, Nagpur [1997-98], Head, Centre for Energy Studies, IIT, Delhi [1995-97]. He was visiting professor at Royal Melbourne Institute of Technology, Melbourne, Australia in 1982-83 and 1989 for two years. He was NSF Fellow at Purdue University, USA in 1992. He has published 720 research papers in various national and international journals and conferences, guided 32 PhDs, authored 27 books in Power Systems and other allied areas. He is a Fellow of the Indian National Academy of Engineering [FNAE], Indian National Academy of Sciences [FNASc], Institution of Engineers [FIE] and Fellow IEEE.

Documents

Novel Control of a UPFC Connecting the KSA and Kuwait in the GCC Interconnection