UNIFIED P O W E R FLOW C O N T R O L L E R AS P O W E R SYSTEM STABILIZER A dissertation submitted to the Department of Electrical Engineering, University of Moratuwa in partial fulfilment of the requirements for the degree of Master of Science by WARUSAPPERUMA KANKANAMALAGE MAHESH PRASANNA WARUSAPPERUMA Supervised by: Prof. J.R.Lucas Dr. P.S.N. De Silva LIEHAH" <3 X \ • 3 ^ ° C 1 t JTWTYBFMBnATWA.'-'WlAMKA MORATUWA Department of Electrical Engineering TH University of Moratuwa, Sri Lanka University of Moratuwa 92969 9 X 9 6 9 January 2009 i DECLARATION The work submitted in this dissertation is the result of my own investigation, except where otherwise stated. It has not already been accepted for any degree, and is also not being concurrently submitted for any other degree. Date: 30th January 2009 We/I endorse the declaration by the candidate. Prof. J.R.Lucas Dr. P.S.N. De Silva Li Table of Contents ACKNOWLEDGEMENT VI LIST OF FIGURES VII LIST OF TABLES VIII CHAPTER 1 1 INTRODUCTION 1 1.0 SCOPE OF THE PROJECT 1 1. L INTRODUCTION TO STABILITY 2 1.11 ROTOR ANGLE STABILITY 2 L .2 INTRODUCTION TO FLEXIBLE A C TRANSMISSION SYSTEMS 6 CHAPTER 2 12 THEORETICAL VERIFICATION 12 2 . 0 U P F C AS A POWER SYSTEM STABILIZER 12 2 .1 U P F C MODEL IN MATLAB/SIMULINK SIMULATOR 16 CHAPTER 3 21 CASE STUDY 21 3 . 0 INTRODUCTION 21 3 .1 KUKULE GANGA HYDRO POWER PLANT MODELLING 2 2 3 . 2 HORANA GENERATORS MODELLING 2 5 3 .3 TRANSMISSION LINE MODELLING 2 8 3 .4 TRANSMISSION LINE DATA 2 8 3 .5 MODELLING OF PANNIPITIYA BUS 2 9 3 . 6 MODELLING OF PANADURA LOAD CENTER 2 9 iii 3 . 7 U P F C MODELLING 3 0 CHAPTER 4 32 SIMULATION RESULTS AND ANALYSIS 32 4 . 0 INTRODUCTION 3 2 4 .1 ANALYSIS OF FAULTS 3 2 4 . 2 EFFECT OF INCREASE IN DAMPING COEFFICIENT OF THE U P F C 3 8 4 . 3 EFFECT OF INCREASE IN SHUNT CONVERTER POWER RATING 4 5 CHAPTER 5 47 CONCLUSION 47 5 .0 CONCLUSION AND RESULTS 4 7 5.1 RECOMMENDATIONS FOR FUTURE RESEARCH 4 9 REFERENCES 51 APPENDIX - A: UNIFIED POWER FLOW CONTROLLER (PHASOR TYPE) 53 APPENDIX - B: POWER GRID DATA 55 iv Abstract The FACTS device - Unified Power Flow Controller (UPFC) and its performance is studied under transient condition in the usage as a power system stabilizer. This device creates an impact on power system stability with its unique capability to control real and reactive power flows simultaneously on a transmission line and regulate voltage at the bus connected. These features become significant as the UPFC can allow loading of the transmission lines up to their thermal limits by regulating the power flow through desired paths. This gives the power system operators the desired flexibility in satisfying the deregulated power system imposed requirements. The new technology associated with the UPFC and its structure is studied. The theoretical analysis is done in verifying its capability for stability enhancement. A practical system is modelled to verify the theoretical analysis in MATLAB/SIMULINK platform. Theoretical and practical verification reveals the function of UPFC in power system stabilisation. The parameters associated with the UPFC are studied for optimum stability criterion. Acknowledgement Thanks are due first to my supervisors, Professor J.R.Lucas and Dr. P.S.N.De Silva for their great insights, perspectives, guidance and sense of humour. My sincere thanks go to the officers in Post Graduate Office, faculty of Engineering, University of Moratuwa, Sri Lanka for helping in numerous ways to clarify the things related to my academic works in time with excellent cooperation and guidance. Sincere gratitude is also extended to the people who serve in the office of Department of Electrical Engineering. I would also like to extend my sincere gratitude to M/s Maga Engineering (Pte) Ltd. for sponsoring me for the first year work of my MSc course and providing required duty leave. Lastly, I should thank my parents, many individuals, friends and colleagues who have not been mentioned here personally in making this educational process a success. May be I could not have made it without your support. vi List of Figures Figure Page FIGURE 1.0: POWER - DELTA CURVE FOR SYNCHRONOUS MACHINE 3 FIGURE 1.1: PHASE-ANGLE COMPENSATION 8 FIGURE 1.2: COMPARISON OF FACTS DEVICES 9 FIGURE 1.3: UPFC BLOCK DIAGRAM 10 FIGURE 1.4: VSC SIMPLIFIED DIAGRAM 11 FIGURE: 2.0 (B): UPFC SIMPLIFIED MODEL 12 FIGURE 2.1: PHASOR DIAGRAM 13 FIGURE 2.2: PROPOSED CONTROL LOOP FOR UPFC 15 FIGURE 2.3: UPFC BLOCK IN SIMULINK 17 FIGURE 2.4: CONTROLLER - SERIES COMPENSATOR 17 FIGURE 2.5 TRANSMISSION LINE WITH VOLTAGE SOURCES 18 FIGURE 2.6 : PHASOR DIAGRAM ILLUSTRATING P AND Q PROPOSTIONALITIES 19 FIGURE 2.7:CONTROLLER - SHUNT COMPENSATOR 20 FIGURE 3.0 : SUB NETWORK SELECTED FOR CASE STUDY 21 FIGURE 3.1: KUKULE GANGA HYDRA POWER PLANT 22 FIGURE 3.2 MODEL OF KUKULE GANGA POWER STATION IN SIMULINK 25 FIGURE 3.3 HORANA DIESEL POWER GENERATORS 27 FIGURE 3.4 MAIN SYSTEM CONSISTING MATUGAMA, HORANA, PANNIPITIYA & PANADURA BUS 29 FIGURE 3.8: MATUGAMA SUB SYSTEM WITH UPFC 30 FIGURE 4.0: ROTOR ANGLE RESPONSE TO FAULT ON HORANA BUS 33 FIGURE 4.1: ROTOR ANGLE RESPONSE TO FAULT ON PANNIPITIYA BUS F 34 FIGURE 4.2: ROTOR ANGLE RESPONSE TO FAULT ON PANADURA BUS 35 FIGURE 4.2: ROTOR ANGLE RESPONSE TO FAULT ON PANADURA BUS 36 FIGURE 4.3: ROTOR ANGLE RESPONSE TO FAULT ON MATUGAMA BUS 37 FIGURE 4.4: POWER VS. LOAD ANGLE CURE FOR A SYNCHRONOUS GENERATOR 38 FIGURE 4.5: SIMULATION RESULTS WITH K = 1 40 FIGURE 4.6: SIMULATION RESULTS WITH K = 10 42 FIGURE 4.7: SIMULATION RESULTS WITH K = 30 44 FIGURE 4.8: SIMULATION RESULTS DIFFERENT SHUNT CONVERTER RATINGS 46 vii List of Tables Table Page TABLE 3.0: KUKULE - GENERATOR PARAMETERS 23 TABLE 3.1: KUKULE - HYDRAULIC TURBINE PARAMETERS 23 TABLE 3.2: KUKULE - EXCITATION SYSTEM PARAMETERS 24 TABLE 3.3: KUKULE - UNIT TRANSFORMER PARAMETERS 24 TABLE 3.4: HORANA GENERATOR PARAMETERS 26 TABLE 3.5: HORANA GOVERNOR AND DIESEL ENGINE PARAMETERS 26 TABLE 3.6: HORANA EXCITATION SYSTEM PARAMETERS 27 TABLE 3.7: HORANA - UNIT TRANSFORMER PARAMETERS 27 TABLE 3.8: HORANA - UNIT TRANSFORMER PARAMETERS 28 TABLE 5.0: UPFC PARAMETERS 47 TABLE 5.1: PERFORMANCE RESULTS AFTER ADDING UPFC TO THE SYSTEM 48 TABLE 5.2: EFFECT OF INCREASE OF K VALUES 49 viii Chapter 1 Introduction 1.0 Scope of the Project Today, in the world, reliability of Electrical Power systems is one of the important aspects and numerous researches have been conducting towards this. As far as reliability and stability are concerned, new emerging technology plays vital roles towards achieving these targets. Flexible AC transmission devices are used to control power flow in power systems. But systems like Unified Power Flow Controllers (UPFC) are very new concepts of flexible AC transmission. It can work in any compensation mode and is the most advanced controller in FACTS devices. And also UPFCs have never been used in Sri Lankan power system as this concept itself is a new system to the world. Study of FACTS devices like UPFC is an objective of this project. And its performance under transient conditions to improve the stability of a power system has been discussed in this thesis. Stability analysis is done with respect to rotor angle stability criterion under transient conditions. And then, Unified Power Flow Controller's capability of standing as a power system stabilizer has been studied. That is, UPFC's capability and how it could introduce dampness to a system is studied theoretically as well as practically for stability enhancement. A practical power system portion from the Sri Lankan power system is selected for verification of the theoretical development. System selected to carry out the study is Matugama, Kukule, and Horana Pseudo Island of the National Power System. Configuration and the parameters of the Unified Power Flow Controller (UPFC) to be implemented at Matugama, Kukule, and Horana Pseudo Island of the National Power System are studied. Above systems are modelled in the MATLAB/SIMULINK software environment to achieve these results. 1 1.1 Introduction to stability Power system stability is analysed when it is subjected to transient disturbance. When subjected to a disturbance, power system parameters would vary depending upon the type of disturbance, for example, Voltage, Frequency, Power flow, etc. This variation could be oscillatory or non - oscillatory depending upon disturbance/ system parameters. In practical power systems, it can be observed that there are mainly two types of disturbances. Severe or large disturbances like Loss of major generating plant, loss of main transmission line, 3 phase - ground fault in a transmission line or faulted circuit breaker, loss of major load etc. Small disturbances are always there in a power system such as small load changes, small load loss, fault through a high impendence, small embedded generator tripping etc. There are various definitions for stability given in various literatures. But all agree that the stability is in general a state of [1] equilibrium between two opposing forces. Electrical Power System's generation side has been made out mainly from synchronous generators. Therefore, it is a very clear fact that they should remain in synchronism in all of above disturbances. And also there is another instance where instability can be observed without loss of synchronism. In this instant, the system is unable to keep the voltage levels of their buses within acceptable levels but all generators remain intact. Primitive definition for Stability has been given in the literature [11] as follows: • If the oscillatory response of a power system during the transient period following a disturbance is damped and the system settles in a finite time to a new steady operating condition, we say the system is stable. If the system is not stable, it is considered unstable. Stability problem could be identified in two different ways, as describec • Voltage Stability 1.11 Rotor Angle Stability If we consider a synchronous machine, and from basics of synchronous machines, it's stator electrical quantities are synchronised with the rotor mechanical speed. And also, the machine load is reflected by its rotor load angle (that is the position of the rotor Rotor Angle Stability .A 2 relative to the rotating magnetic field of the synchronous generator). Therefore, when power system oscillates as a result of a disturbance, the rotor also oscillates with its stator electrical quantities. Therefore, through rotor angle stability analysis, we analyse the behaviour of the rotor angle of the synchronous machines in a power system. Therefore, Rotor angle stability can be identified as [1] the ability of interconnected synchronous machines of a power system to remain in synchronism. Torque balance of the system is very important for them to remain in synchronism. For this to happen it is necessary that the synchronous generators have to operate in a stable portion of the Power delta curve within which 5 varies from 0 to id2 as illustrated in the figure 1.0 below. Power (pu) Figure 1.0: P o w e r - d e l t a curve for synchronous machine Electrical torque variation after a perturbation can be resolved into two components as per the [1], • Change in Electrical Torque = Synchronising Torque + Damping Torque 3 In a synchronous machine, electrical torque component is created by interaction between three windings, namely; Stator winding, Field winding and damping winding. And from the above resolved two components, synchronising torque is the most important one. This is the one which continues throughout from steady state to transient condition. The second component is created when the machine is subjected to a transient disturbance. And this damping torque can be resolved further into three different components [11] namely; Positive sequence damping (this is proportional to slip frequency and is beneficial to damp out oscillations), Negative sequence damping (slip frequency in this case is 2-S, therefore, this is retarding the rotor), DC braking (creates during faults, retard rotor movements). Depending on the size of the disturbance, Rotor angle stability can be classified into two categories as follows, • Small signal stability - When a system is subjected to small disturbances, system's ability to remain in synchronism is analysed. When subjected to small disturbances, following types of oscillations can be observed in a practical power system[l], such as Local mode oscillations (Oscillation of one single machine with respect to the rest of the system), Inter-area mode oscillations ( Oscillation of many machines in one part of the power system with respect to other parts), Control mode oscillations (this is associated with generator units and other controls), Torsional mode oscillations ( this is associated with turbine shaft rotational components). Automatic Voltage Regulators play a vital role when this type of disturbance occurs. There are AVR based power system stabilizers which provide dampness to active power variation through voltage control. • Transient Stability: When a system is subjected to a large disturbance and system's ability to maintain its synchronism is analysed. This depends upon the initial operating state, location and severity of the disturbance. Thus transient stability of a system has to be defined with these conditions. In this paper, a case study is carried out with the transient faults on transmission lines. And rotor angle stability enhancement is analysed after adding UPFC to the system. 4 There can be three possible cases when a system is subjected to a transient disturbance and it is cleared after some time. Those are namely; • Rotor angle oscillates and stabilises after some time due to system dampness. And this is a stable case. • Rotor angle increases until synchronism is lost and this is known as first swing instability. This is mainly due to lack of synchronising torque of the system. • Rotor angle oscillates and grows until synchronism is lost. This is mainly due to lack of damping torque of the system. 1.12 Voltage Stability Power system might lose its stability without loss of synchronism. That is the case where the voltage instable. This can be happen due to increase demand in inductive loads (such as induction motors etc.) in a system. System falls into a situation where, increase in reactive power reduces bus voltage. Therefore, system is instable. In normal circumstances, when we increase the reactive power injection to a bus, the bus voltage increases. This type of instability is out of the scope of my project. Therefore, no detail discussion is carried out. 5 1.2 Introduction to Flexible AC Transmission Systems Proper utilization of existing AC transmission systems nowadays is very vital as the power industry is becoming increasingly de-regularised. Transmission system's power transfer capabilities have been restricted by network characteristics such as; • Stability limits • Thermal Limits • Voltage Limits • Loop Flows Without adding new generators or transmission lines into the system, its capabilities can be improved by inserting Flexible AC Transmission Systems (FACTS) devices into the system. This is an emerging technology and proved to be very effective systems as well. Role of FACTS devices is to enhance the controllability of AC power transmission and as well as to improve the Power Transfer Capabilities. FACTS devices use power electronic devices/semiconductors, such as Thyristers, Gate Turn Offs (GTO), Insulated Gate Bipolar Transistors (IGBTs). Since they use these electronic components, they can be controlled very fast as well as with different control algorithms adapted to various situations. There are many different kinds of FACTS devices available, namely; • Shunt Compensators • Series Compensators - Series impedance, Phase angle Compensation type • Shunt - Series Compensators • 1.2.1 Shunt Compensation Shunt compensator is capable of injecting current into a system where it is connected. It should be capable of injecting reactive power into the transmission system in order to increase the transmittable power. Active power transfer capability of a shunt compensator connected to the middle of a transmission line (impedance = X) connected with two voltage sources with equal voltage magnitude (V) and 8 phase 2V2 § difference can be proved to be equal to P = —— sin — value and reactive power X 2 6 4V2 f 8\ Q = 1 — cos— as per the literature [12]. Therefore, it is clear that active power X V 2 J transfer can be improved with an additional injection of reactive power to the system. There are shunt-compensators available in the world such as: • TCR - Thyristor - Controlled Reactor • TSC - Thyristor - Switched Capacitors • SVC - Static Var Compensators • STATCOM 1.2.2 Series Compensation Series compensators are mainly, variable capacitors connected in series with the transmission line. Therefore, they have to be capable of handling the line current. By changing the line impedance variably, power flow through a transmission line can be varied. Detailed analysis can be found on the literature [12]. Active, reactive power flowing through a series compensated transmission line can be proved to be as follows: p 2 V • S P = sin — (1 -r)X 2 2V2 r 0 = x —(1-cos S) X (1 - r f X Where, r = l""'p is called the degree of compensation. Xeq=(X-Xcomp) = X(\-r) Following are the typical series compensators available, • TSSC - Thyrister Switched Series Capacitor • TCSC - Thyrister Controlled Series Capacitor • FCSC - Force Commutation Controlled Series Capacitor • SSTATCOM - Series Static Var Compensator 7 1.2.3 Series compensation - Phase Angle Compensation Phase angle compensation is a special case of series compensation where it is required to engage a series voltage source connected in series with the line and with the capability of handling active power as well as reactive power. This enables it to vary its series injected voltage with any phase angle with respect to the line current so that the active power flow can be controlled. All pervious compensation modes deal with reactive power sources unlike this one. As this is required to handle active power it has to be installed closer to a voltage source. Transmittable active power can be controlled in the following manner, V2 P = — s i n ( ^ - o - ) X Where a is the phase angle of the injected series voltage. Figure 1.1: Phase-angle compensation By observing above equation and figure 1.1, we can see that, the power transfer curve can be shifted parallel to the delta axis. Hence, although it doesn't increase the maximum power transfer, maximum power can be obtained with lower delta value by shifting the curve. Practically, Phase shifter is used as phase angle compensator. It is a shunt connected excitation transformer with secondary connected through thyristors with series transformer. This is worked as a thyristor controlled tap changer which will control the secondary injection voltage to line. 8 1.2.4 Comparison of FACTS devices With 50% of Series Capacitive Compensation <- With shunt Compensation With phase - shifter Compensation Without Compensation 7T +a 5(rad) O 7T /2 71 Figure 1.2: Comparison of FACTS devices Above chart illustrates Active power variation with respect to delta angle for different types of compensation provided by FACTS devices. Shunt controller injects voltage to a point, and it is very effective in controlling bus voltage, therefore it can damp reactive power oscillation (voltage oscillation). And it has increased the stability margin largely, compared to other controllers. Series controller directly injects line current in series, therefore, it affects power flow directly. Therefore, it is the best option to control and increase power transfer capability. Phase shifter would be connected in the instance where uncontrollable phase differences exist. 1.2.5 Unified Power Flow Controller Unified Power Flow Controller (UPFC) is the complete compensator with all of above features. Therefore, it can be treated as complete compensator. Block diagram of the UPFC is given in the Figure 1.3 below. It has two Voltage Source Converters 9 connected to series as well as shunt transformers. These two converters are coupled with a common DC link capacitor. Vi<0, Bus i Shunt Transfo Series transformer P,Q I Vm x VjOj V i , Converter Vn Converter Figure 1.3: UPFC block diagram Principle of operation Converter 2 performs the main function of the UPFC by injecting, via a series transformer, an AC voltage with controllable magnitude and phase angle in series with the transmission line. The basic function of converterl is to supply or absorb the real power demanded by the converter 2 at the common DC link. It can also generate or absorb controllable reactive power and provide independent shunt reactive compensation for the line. Converter 2 supplies or absorbs the required reactive power locally and exchanges the active power as a result of the series injection of voltage. 10 Voltage Source Converter There are two voltage source converters available in the UPFC. Therefore, its operation is discussed here briefly. Following diagram shows basic configuration of Voltage Source Converter. +V D c -VDC Figure 1.4: VSC simplified diagram Voltage source converter is made out of 6nos of IGBTs with reverse diode connected each. DC side of the converter is connected to a capacitor. Four quadrant operations are possible for this kind of a converter [14]. Real power exchange between converter DC side and AC side can be performed by controlling output voltage angle [13]. When AC output voltage of the converter leads that of system voltage, then the real power flow from DC side to AC side will happen and vice versa. To exchange reactive power from converter to system, converter voltage magnitude has to be increased, and if the voltage magnitude is decreased with respect to the system voltage then reactive power will be absorbed. 11 Chapter 2 Theoretical Verification 2.0 UPFC as a Power System Stabilizer The way the UPFC can be used to damp power swing can be explained using the simple generator-infinite bus-bar system [10] shown in the figure below. The system equivalent reactance has been neglected in order to simplify the equation describing the equivalent circuit. AV Infinity Bus ( a ) : UPFC with, infinity bus system AV K Figure: 2.0 (b): UPFC simplified model 12 Figure 2.1 : Phasor diagram The booster voltage AV has an in-phase component AVQ and quadrature component AVp. Both components are proportional to the voltage at the point where the UPFC is installed and can be written as, AVq = VJ(t), = Vj{t), (eq2.0) where (3(t) and y(t) are the control variables. From figure 2.1 gives, sin© = —— = — y, V V cos© = Vs +AV0 V , s V v (eq2.1) Neglecting the network losses, the electrical power can be expressed as, t E V , v P\S J=—^-s in (£ - © ) = —!V-(sin£ c o s 0 - c o s S sin©) E..V (eq2.2) Where Xd is the equivalent transient reactance which also includes the reactance of the transformer and the transmission line. Substituting for sin© and cos© expressions obtained from equation above gives, P(S')'= ^ [(sin S')(l + fi)- (cos S)y\ (eq2.3) P(S') = bsin 8' - (bcos S')y(t) + (bsin8)Pit) 13 E V / Where b = 8 y • is the amplitude of the power angle characteristic with / xd zero booster voltage. The equation (eq2.3) shows that the control of the in-phase booster voltage (via the control variable (3(t)) increases the amplitude of the power - angle characteristic while control of the quadrature booster voltage (via the control variable y(t)) shifts the characteristic horizontally. From the generator swing equation, ..d2S dS from that we can derive, d8 Aco dt dAo) . d5 _ («12-4) ~dT= m ~ ~ ~dT~ UPFC Where,PUPFC = -(bcosS )y(t) + (b sin S )/3(t) is the additional power component enforced by the controller. This component introduces additional damping to the system if it is made positive and proportional to the speed deviation Aco. This can be achieved through the following control strategy: y(t) = -K{cos S') Aco (eq2.5) p{t) = K(smS')Aco (ecl2-6) Substituting equations (eq2.5) and (eq2.6) into the expression for P U P F C = Kb(ATO) = D 1 J P F C (AO)) (eq2 .7) where DUPFC = KB is the damping coefficient due to the controller. This coefficient is constant for the control strategy defined in equations (eq2.5) and (eq2.6) and does not depend on 5'. 14 Therefore from equation (eq2.4), M — = Pm -(bsmS')-D—-Kb(Aco) dt dt . . dS dS' M = Pm - (b sin 8 ) - D Kb -dt "' dt dt M ^ = Pm -(bsm8)-(D + Kb) (eq2.8) dt m dt Hence from the equation (eq2.7) it is clear that the damping coefficient has increased due to the addition of the UPFC by 'Kb' amount. This definitely supports the improvement of stability of the system. Higher damping level would be added by the UPFC to fadeout the oscillations in the system very quickly. In the literature [3], it has been explained the way external control may be comprised of different control loops depending on the control objectives. Typically, the principal steady state function of a UPFC is power flow control to a specified set point. Additional functions for stability improvement, such as damping controls, may be included in the external control. External control Figure 2.2: Proposed control loop for UPFC 15 If power flow control loop is "slow", as is typically the case for a PI controller with a large time constant or for manual control, Xss is assumed here to be constant during large disturbance transient periods. In the particular case of a PI power flow control, a protection logic scheme may be implemented to avoid contradictory control signals that could degrade the overall performance. When the system is subjected to a severe disturbance, the stability control loop must provide maximum compensation level during the immediate post-fault period, so that synchronizing torque is increased to improve the first - swing stability response of the system, as well as provide proper modulation to damp the subsequent power oscillations. Two fundamental elements in this controller design process, i:e. input signal and parameter tuning, are discussed below. The effect of set point value on controller performance, and particularly its effect on interactions between the stability control loop (dynamic control) and the power flow control loop (steady state control), is also discussed. Parameter tuning: a number of alternative methods may be used for selection of control parameters for UPFC. The most popular ones, which are based on linear systems theory, are phase and gain margin techniques, pole placement through root locus analysis, Eigen value placement based on residues, and optimal selection of control parameters based on Eigen value sensitivities. However due to high nonlinearity of UPFC behaviour and major concern is the controller's performance under severe disturbances, which typically trigger large excursions of generator angles, power flows, bus voltage and other system variables due to non linear characteristics of the power system, parameters were adjusted using full time domain simulation (trial and error method). 2.1 UPFC model in Matlab/Simulink Simulator UPFC model given in MATLAB/SIMULINK software is used for simulation purposes. Therefore, detail understanding of the model is necessary. Matlab version used for this simulation is R2008a. Following figure shows the basic block given in the simulator. This phasor type block models an IGBT - based UPFC. 16 Trip m Bypass A2 A1 UPFC B2 B1 C2 C1 Figure 2.3: UPFC block in Simulink Parameters can be defined for the UPFC after double clicking it. Detailed analysis of series and shunt controller are given below as per the literature [7], 2.1.1 Series Converter Control system of series converter is meant to control active power and reactive power. Therefore, it has two degrees of freedom. Simplified block diagram of the UPFC can be drawn as follows, Figure 2.4: Controller - Series compensator 17 As can be seen from above figure, series converter can be operated on two modes, namely; • Voltage injection mode • Auto mode 2.1.2 Voltage Injection Mode Injected voltage (AV) can be resolved into two components as given in the figure 2.1 above. Those are namely; AVp and AVq. These two components can be directly injected to the UPFC model given in the Simulink software. Therefore, by comparing those two systems we can write; The in-phase component with Vs is responsible for reactive power transfer, and the in- phase quadrature component with Vs is responsible for active power transfer. This can be further proved as follows using simple transmission line, AVp = Vqref AVq = Vdref Eq - 2.9 A A / V ^ Es<8 jX Vs<0 Figure 2.5 Transmission line with voltage sources From the above figure, we can write KVL as Eg<8' - Vs < 0 = jlX Eg < 8' = < 0 + jlX •a E q - 2 . 1 0 18 But we know that, V* xl = P-jQ 1 = P-jQ v s LiBHMH 1SITY OF MOIKTtm ^ tAhK* MOWATUWA E q - 2 . 1 1 Form eq-2.10 & eq 2.11 Eg<8' = Vs<0+jx{^-) En < 8' = K < 0 + — + — Eq - 2.12 From eq - 2.12 we can draw the phasor diagram as follows, (XP)/V s (XQ)/V s Figure 2.6 : Phasor diagram illustrating P and Q propostionalities Therefore, from Eq - 2.0, Eq - 2.9, Eq - 2.5 and 2.6 we can derive the following relationship, AVp = Vqref= - Vs K (cos8') Aw Eq- 2.13 AVq = Vdref = Vs K (sin8') Aw These inputs can be given into the UPFC model in the Simulink to work it as a Power System Stabilizer. In manual injection mode, inbuilt regulators are bypassed and converter voltage is derived from reference values. In Automatic mode, power flow control can be done. This is done using sensed voltage and current in the system as illustrated in the block diagram. In this case voltage regulators are used with defined Pref and Qref. As in this thesis we only do the manual external voltage injection, other parameters associated with the Power flow control (automatic) mode is not discussed in detail. 19 c 9 r ; Q O L. V. From the equation 2.7, it is clear that, damping constant of the UPFC can be varied by changing the value of K (since b is a constant). 2.1.3 Shunt Converter Shunt converter also can be operated on two modes. They are, Voltage Control Mode and Var control Mode. Its block diagram can be drawn as given in the literature [7] as shown below, Figure 2.7:Controller - Shunt compensator The shunt controller can be operated in two different modes: • Voltage regulation mode: As long as the reactive current stays within the minimum and maximum current values (-Imax, Imax) imposed by the converter rating, the voltage is regulated at the reference voltage Vref. • Var control mode (reactive power output is kept constant) In this project the shunt controller is kept in the Voltage control mode. 20 Chapter 3 Case Study 3.0 Introduction Performance of the UPFC was monitored with real practical system in Sri Lankan power system. Area selected was Matugama, Kukule, Horana Pseudo Island of the National Power System. System was modelled in the Simulink software, which is a common engineering tool nowadays used by engineers around the world. Following figure 3.0 illustrates the simplified selected network portion from the Sri Lankan Power system to analyse the theoretical development in the previous chapter. The actual network diagram is given in the Appendix B. T 1 Panadura 14.1km Zebra Horana Generator Bus 31.6MVA 12.3km Pannipitiya Goat 4 .7km-Lynx Bus n Panadura Load Bus 15km Zebra 4.7km - Lynx 12.3km Goat Matugama Bus " 29.1 km Goat Kukule Generator Bus 75MW T 2 Panadura 27km - Lynx Figure 3.0 : Sub network selected for Case study 21 All power system components illustrated in the above figure 3.0 are modelled in the Simulink software environment. Detail discussion is given below for each components modelling below. 3.1 Kukule Ganga Hydro Power plant modelling There are two hydro generators each 37.5MW installed in the Kukule Ganga Power plant, and connected to the 132kV bus through two 46MVA transformers. 2 x 37.5MW Salient pole 2x46MV| gen tf 132kV Kukule Bus To Matugama 132kV double Figure 3.1: Kukule Ganga Hydra Power Plant Synchronous machine model given in the Simulink is used for modelling of generators. Using this model salient pole 3 phase generator can be modelled. Hydraulic Turbine Governor Model is used to model water turbines of the system. Excitation System Model is used to model excitation system of the generator and to control terminal voltage. The parameters related to those systems are used and combination of above three systems, a complete hydro generator is modelled. There is a 3phase transformer model given in the Simulink. Simulink implement this using three single-phase transformers. Generator and Transformer parameters are given below, 22 3.1.1 Generator Parameters Parameter Value Nominal Power 37.5MW Line to Line Voltage 13.8kV Frequency 50Hz Y V ' V " V V " Ad, Ad ,Ad ,Aq,Aq 1.305, 0.296, 0.252, 0.474, 0.243, 0.18 (pu) rp , m || m || i d , id , 1 qo 1.01,0.053,0.1 (s) Stator Resistance 0.0028544 (pu) Inertia Constant - H 3.2 (s) Pole pairs 32Nos Table 3.0: Kukule - Generator Parameters 3.1.2 Hydraulic Turbine Parameters Parameter Value Servo motor Ka,Ta(s) 10/3 ,0.07 s The speed deviation damping coefficient ft 0 Water starting time Tw (s) 2.67s PID regulator, Kp,Ki,Kd, 1.163,0.105,0 Permanent droop Rp 0.05 Td (s) 0.01s Table 3.1: Kukule - Hydraulic Turbine Parameters 23 3.1.3 Excitation System Parameters Parameter Value Low Pass Filter Time Constant Tr(s) 0.02 Regulator Gain Ka, Time constant Ta(s) 300, 0.001 Damping Filter Gain and Time constant KfQ, Tf(s) 0.001,0.1 Table 3.2: Kukule - Excitation System Parameters 3.1.4 Unit Transformer Parameters Parameter Value Nominal Power and frequency 46MVA, 50Hz Primary winding Voltage, R(pu),L(pu] 13.8kV,0.0027pu, 0.08pu Secondary winding Voltage, R(pu),L(pu) 132kV,0.0027pu, 0.08pu Magnetization Resistance pu 500 Magnetization Reactance pu 500 Vector Group YNd5 Table 3.3: Kukule - Unit Transformer Parameters In the next page modelled system is shown in figure 3.2, 24 Figure 3.2 Model of Kukule ganga power station in Simulink 3.2 Horana Generators Modelling Horana power station is a diesel power plant with capacity of 31.6MW. This power plant consists of 4 generators connected parallel with each capacity of 7.9MW. This has been modelled as a single equivalent diesel generator for simplicity. This is also connected through a unit transformer to the 132kV grid at Horana bus. Equivalent Generator Parameters are given below in the table 3.4, 25 3.2.1 Equivalent Generator Parameters Parameter Value Nominal Power 31.6MW Line to Line Voltage l lkV Frequency 50Hz V V ' V " V V " Ad, Ad ,Ad ,Aq,Aq 1.56, 0.296, 0.177, 1.06, 0.177, 0.052 (pu) rp 1 rp II rp II I d , id , 1 qo 3.7, 0.05,0.05 (s) Stator Resistance 0.0036 (pu) Inertia Constant - H 1.7 (s) Pole pairs 2Nos Table 3.4: Horana Generator Parameters 3.2.2 Equivalent Governor and Diesel Engine Parameters Parameter Value Regulator Gain 40 Regulator Time constants Ti, T2, T3 • 0.01,0.02, 0.2(S) Actuator Time constants T4, Ts, T6 0.25, 0.009, 0.0384(S) Torque Limits Oto 1.1 (pu) Engine Time Delay 0.024(S) Table 3.5: Horana Governor and Diesel Engine Parameters 26 3.2.3 Excitation system Parameters Parameter Value Low Pass Filter Time Constant Tr[s) 0.02 Regulator Gain Ka, Time constant Ta(s) 200, 0.02 Damping Filter Gain and Time constant KfQ, Tf(s) 0.001,0.1 Table 3.6: Horana Excitation System Parameters 3.2.4 Unit Transformer Parameters Parameter Value Nominal Power and frequency 40MVA, 50Hz Primary winding Voltage, R(pu),L(pu) 1 lkV,0.0027pu, 0.08pu Secondary winding Voltage, R(pu),L(pu) 132kV,0.0027pu, 0.08pu Magnetization Resistance pu 500 Magnetization Reactance pu 500 Vector Group YNd5 Table 3.7: Horana - Unit Transformer Parameters Modelled system is given below, uuref (pu) 1.0 1 Vtref (pu) uiref Pm Vf Uref Vt m w Diesel Engine Speed & Vol tage Control C 1 Yg C r» Conn l - < Z > Conn2 Three-phase Transformer 40 MVA 11 kV / 1 3 2 kV Conn3 Figure 3.3 Horana diesel power generators 27 3.3 Transmission Line Modelling Distributed parameter transmission line model given in the Simulink Library is used for the transmission line modelling of the selected system. As per the literature [7], the Distributed Parameter Line block implements an N-phase distributed parameter line model with lumped losses. The model is based on the Bergeron's travelling wave method used by the Electromagnetic Transient Program (EMTP). In this model, the lossless distributed LC line is characterized by two values (for a single-phase line): the surge impedance and the phase velocity. There are three main types of 132kV transmission lines in the selected system. Those are Lynx, Zebra and Goat. Those parameters were obtained from the transmission design division of Ceylon Electricity Board. These details are attached in Appendix B. Transmission line parameters of the selected system can be tabulated as follows, 3.4 Transmission Line Data Line Section Volt ( kV) Ccts. Conductor Length (Km) R/cct InPU X/cct InPU Y/cct InPU Kukule - Mathugama 132 2 Lynx 27.0 0.02758 0.06214 0.01315 Single in and out connection from Horana GS to Panadura T - Mathugama 132 2 Zebra 20.0 0.00872 0.04442 0.01040 Pannipitiya - Panadura (T) 132 2 Goat 12.3 0.00629 0.02734 0.00631 Panadura(T) - Mathugama 132 2 Goat 29.1 0.01488 0.06467 0.01493 Pandura(T) - Panadura Sub Station 132 2 Lynx 4.7 0.00480 0.01082 0.00229 Note : the line parameters are given in pu values wrt Zbase = V/Jase / MVA /„ (.MVAbase=100, Vhase in kV) Table 3.8: Horana - Unit Transformer Parameters 28 3.5 Modelling of Pannipitiya Bus Pannipitiya bus has the highest fault level among the buses in the system. Therefore, it is considered the one closer to infinity bus. It is therefore, modelled as three phase voltage source with impedance in series, which is calculated using fault level of the bus. 3.6 Modelling of Panadura Load Center Panadura bus is a load bus. It has a load curve with high night peak. For the analysis purpose, highest peak load is used. The block used to simulate this is RLC parallel load block. As per literature [7], The Three-Phase Parallel RLC Load block implements a three-phase balanced load as a parallel combination of RLC elements. At the specified frequency, the load exhibits constant impedance. Active power consumption is around 50MW, and reactive power consumption is around 4MVar. The modelled main system in Simulink is given in the figure 3.4 below, powergui KukuleMatugama CQWli: = n - \ aduraT Pannipit iya Lii e I-— » - - Three-Phase Breaker3 Matugama PanaduraT Line w I I 3 PanaduraT Panadura Linel fa'jlt Rreaksr2 \ Panadura Load LLL P a n d a d u r a T I C c A a Horana C c Three-Phase Bn m Three-Phase Breaker4 f r ^ i < i" u \ PanaduraT Panadura Line2 P a n d a d u r a T 2 DG Three-Phase Source PanaduraT Pannipitiya Line2 Horana Panadu raT Line Figure 3.4 Main system consisting Matugama, Horana, pannipitiya & Panadura bus 29 UPFC model is inserted near Kukule Generator bus end of the above system. Inputs to the UPFC are given as proved in the Chapter 2. Pha$«A PhaseB PhaseC Power P lan t # 1 P n o m = 7 5 MW , J m Trip M Vliiref UPFC A! B2 B1 C2 • — H C o n n 2 !-«CE> Conn3 Figure 3.8: Matugama sub system with UPFC 3.7 UPFC modelling In modelling the UPFC, it is required to identify the capacities and parameters of it. As discussed previously, there are two converters coupled through a common DC link capacitor. Therefore, converter ratings and parameters, capacitor ratings, controller parameters are necessary for modelling purposes. 3.7.1 Series converter of the UPFC This needs to handle line current as well as its injected voltage to the line in series. Normally, maximum injected voltage is around 0.1 pu. Current handling capability of the series transformer should be same as the line current in steady state. Therefore, series converter rating is taken as O.lxLine rating, it is around 10MVA. Resistance and Inductance of the series converter is taken as 0.00533pu, 0.16pu respectively. 30 3.7.2 Shunt Converter of the UPFC As per the literature[15], if we assume the active power to be released by the DC link capacitor at transient state, then the shunt devices rating should at least be equal to the steady state power flow through the series device (i:e about 100MVA). If shunt device is expected to transmit all the transient state power, then, it should be equal to transient state power flow though the series converter. This will be further explained in the simulation by selecting two power values to the shunt converter and how that could affect the transient behaviour. Therefore, for the moment 100MVA value is selected as the shunt converter rating. Shunt converter impedances are taken as typical values, like for resistance 0.00733pu and Inductance 0.22pu. 3.7.3 DC link Capacitor Details of design aspects of DC link capacitor are given in the literature [15]. According to that, in transient state energy stored in the DC link capacitor is transmitted and stored in the series line inductor as a magnetic energy. This type of situation only happens in the transient state, but not in the steady state. But when DC link capacitor supplies its energy in this transient state, fluctuation of its voltage can be observed. Whereas, if the shunt converter can supply this energy through DC link capacitor, a constant DC link capacitor voltage can be maintained. Value of the DC link capacitor can be obtained from following equation according to [15], Crlr — 3L(/x 2 - /0 2) 'dc IfV2 Where, Cdc = DC link capacitor capacitance in F. L = Line inductance . I1 - value of the current after transient. /0 = value of the current at the start of the transient. Vdc0= DC link capacitor voltage - steady state. = 40000V _ 3x0.16(720 -200 ) _ , „ _ „ Cdr = — = 717.6uF ~ 750 uF a c 2x0.1x400002 r r 31 Chapter 4 Simulation Results and Analysis 4.0 Introduction In this chapter, the modelled system is analysed with simulation results obtained from the MATLAB/Simulink. Basically, the system is analysed before adding the UPFC to the system and then, the improvement towards the system stability is to be identified after adding the UPFC to the system at Kukule Ganga Generator bus. The modelled system is simulated before adding the UPFC to the system with various faults created. The aim of this creation of fault is to obtain a situation where system cannot hold its stability. Therefore, three phase line to ground faults have to be created to simulate this situation. Then the critical clearing time was observed to be increasing with the UPFC introduced in the system. Input K value is changed, in order to observe the effect of the damping coefficient imposed by the UPFC to the system. Results are analysed for various K valued Then effective damping coefficient and damping ratio to the system is fcalculdt^fi using simulation results. Then UPFC performance is studied by changing parameters of shunt converter, as explained in the previous chapter to find out most suitable parameters for shunt converter for optimum operation. This type of optimisation is normally combined with cost benefit analysis as well. 4.1 Analysis of Faults 4.1.1 Fault created on Horana Bus: A three phase to ground fault is created on Matugama - Horana transmission line towards the Horana end with fault impedance of 0.001Q. The time duration of the fault is from 20.0s to 20.5s, so that giving sufficient time to make the system to become unstable. It is observed that with this type of fault in the line, the system is marginally unstable and unable to come back to a stable point after clearing the fault after 500 32 milliseconds, as system itself does not provide sufficient damping to this type of transient behaviour. Kukule Ganga generator rotor angle variation were observed and results are shown in figures below, Rotoi Angle(Deg| Vs. Time(S) H lllll — Ill ill 111 (a) Without UPFC in Operation •m (b) With UPFC in Operation (c) With UPFC in Operation - Zoomed view of (b) Figure 4.0: Rotor Angle Response to Fault on Horana Bus These types of large transient oscillations have been damped by the UPFC as can be seen from the above Figure 4.0. When UPFC is not in operation, huge oscillatory response is observed as shown by Figure 4.0(a). Rotor angle maximum overshoot has been limited to just above 90degrees, when UPFC in operation. Thereafter, oscillation is damped out to zero at around 30s. First swing of rotor angle is a very high value, 33 when UPFC is not inserted, it goes to above 150 degrees. That behaviour is damped out by DC link capacitor either by absorbing that energy temporary or releasing its stored energy to the series inductor. 4.1.2 Fault created near Pannipitiya Bus: A three phase to ground fault is created on Pannipitiya Bus with fault impedance of 0.001Q. The critical clearing time of this case before adding the UPFC is 600 milliseconds. Therefore, the time duration of the fault is taken from 20.0s to 20.7s, so that giving sufficient time to make the system to unstable. Fault time duration for this case is 700 milliseconds, as system itself does not provide sufficient damping to this type of transient behaviour. (a) Without UPFC in Operation (b) With UPFC in Operation • (c) With UPFC in Operation - Zoomed view of (b) Figure 4.1: Rotor Angle Response to Fault on Pannipitiya Bus 34 As can be seen from above figure 4.1, rotor angle maximum overshoot has been limited to just below 50degrees, when UPFC in operation. This is because the fault is far away from the Kukule generators and somewhat closer to the infinite bus. Therefore, fault current is largely fed by infinite bus. Thereafter, oscillation is damped out to zero at around 26s. 4.1.3 Fault created near Panadura Load Bus: A three phase to ground fault is created on Panadura bus with fault impedance of 0.00 ID. The time duration of the fault is from 20.0s to 20.6s, because critical clearing time for this kind of fault is observed to be 500milliseconds. 500 milliseconds fault time is in between the values of previous two cases, where in this case fault lied between those two cases. Therefore, the model validity to some extent also confirmed by this behaviour. Kukule Ganga generator rotor angle variation is observed and results are shown in figures below, (a) Without UPFC in Operation (b) With UPFC in Operation Figure 4.2: Rotor Angle Response to Fault on Panadura Bus 35 (C) With UPFC in Operation - Zoomed view of (b) Figure 4.2: Rotor Angle Response to Fault on Panadura Bus This type of large transient behaviour has been damped out by the UPFC as can be seen from the above Figure 4.2. When UPFC is not in operation huge oscillatory response is observed as shown by Figure 4.2(a). Rotor angle maximum overshoot has been limited to just below 70degrees, when UPFC in operation. Thereafter, oscillation is damped out to zero at around 29s. The maximum overshoot value also lies in between the values of previous two simulations. 4.1.4 Fault created near Matugama Bus: A three phase to ground fault is created closer to Kukule generators. That is on Matugama bus with fault impedance of 0.001 Q. The time duration of the fault is from 20.0s to 20.3 Is, so that giving sufficient time to make the system to become unstable. Critical clearing time for this case is 300 milliseconds, as fault is very closer to the Kukule generators. The fault is allowed to persist 1 Omillisecond more to create an unstable situation. Kukule Ganga generator rotor angle variation were observed and results are shown in figures below, 36 (a) Without UPFC in Operation (b) With UPFC in Operation (c) Without UPFC in Operation - Zoomed (a) (d) With UPFC in Operation - Zoomed (b) Figure 4.3: Rotor Angle Response to Fault on Matugama Bus As can be seen from the above Figure 4.3, UPFC was only able to damp out the oscillation when fault existed lOmilliseconds more unlike in previous cases. When UPFC is not in operation huge oscillatory response is observed as expected, as shown by Figure 4.3(a). Rotor angle maximum overshoot has been limited to just below 90degrees, when UPFC is in operation. Thereafter, oscillation is damped out to zero at 37 around 32s. An initial high overshoot of above 150degrees was also observed in this case. And that is due to the closeness of the fault to Kukule bus. 4.2 Effect of increase in damping Coefficient of the UPFC Let us examine the effect of increase in damping coefficient, as a result of insertion of UPFC to the system practically with the simulation. Kb is the additional damping coefficient provided by the UPFC (according to the equation 2.7). We can increase the value of Kb in the model in order to obtain better results. As b is a constant value, we can increase the value of K. Advantages of by having a larger damping constant to the system can be theoretically explained as follows. Then the system is simulated with different K values and results are shown in Figure 4.5 and Figure 4.6. Theoretical examination can be shown as follows, From the generator swing equation, d2S „,dS at at For small 5, let it is equal to A8, then ./fd1AS M — + Kd Ke AS = pm dt2 dt As Pe linear for small 8, as shown in the Figure 4.4 below, Figure 4.4: Power Vs. Load angle cure for a Synchronous Generator 38 Taking Laplace Transformation of the above equation, (S2 +^-S + ^ )AS = Pm M M Therefore, M 2 M From above equation, to have real roots, When this equation has real roots, that means Eigen values of the system has real negative numbers. When Eigen values are real negative the system damp out without oscillations. To obtain the point where these two transitions are taking place, the following equality can be written, From the above equation, it can be seen that when Ke has higher values that means when generator is in low load condition, for disturbances in the system creates generator to oscillate more. But, when generator is in higher load condition then generator output oscillations would damp out quickly without much oscillations. But problem with the higher load condition of the generator is that, the chances of getting back to the stability reduce as it operates very closer to the critical clearing angle point. In other words inertia constant can be increased either by reducing Ke, or by increasing Kd. Therefore, by adding UPFC (which will increase the M), we can operate the machine in low load condition so that no oscillations would result due to disturbances in the same time providing enough gap to the critical clearing angle. This will enable the enhancement of stability of a system. K value (in page 19, Eq - 2.13) of the UPFC input can be increased in this model in order to increase the overall damping coefficient. It is simulated with different K values, and effective increase of dampness is obtained. This simulation is carried out with fault in the Matugama - Horana transmission line towards Horana end. = 2 VM 39 (b) Simulation Result when K = 1 behaviour of peak values, after adding exponential trend line Figure 4.5: Simulation results with K = 1 40 Stability of a system is determined by is Eigen values. Real Eigen values correspond to non-oscillatory mode, complex Eigen values correspond to oscillatory mode response. These complex Eigen values always occur in conjugate pairs. Typical type of it as follows, A = a ± jo) QU _ g(cr±jo))t = eatcos(i)t ± jeatsincot If a is negative, oscillations decay to zero, otherwise it increases, eo is the Angular Velocity of oscillation. Therefore, from the above simulation and from the graph in (b) Average time between two peaks = 0.6667 s Damped Frequency of Oscillation = 1.5Hz Therefore, co = 2 n f = 9.4248 rad/s From the above graph, a = -0.45 Lets, find the damping ratio which determines the rate of decay of the amplitude of the oscillations. -a Therefore, damping ratio is ~Vg2+o>2 = 0.0477 Time constant of amplitude decay isl/| K U R U N E G A L A 2xZrt>ra, 70.5km Zefari , 1 9 3 km 20, Ivar K'RIBAT 50.Mv«r Zebr«^ ,2 km Z e b n , 4 . 6 k m 2x250 MVA B A R G E DG 4x9MW Zebra , 3.6 km M V A B I Y A G A M A I 2x60 MVA 33kV KELAN1YA 4x1.5 MVA 32kV 4 i 9 M W 76 MVA MVA 132kV 1x31.5 MVA 132kV 2x36 MVA 132kV 220kV O R U W A L A (Steel Corp.) - J ^ H'mvt 33kV 8x6.375 ^ M W K H D D C LAKDANAV1 i 109MW+ 54 M W ^ 161 MVA + , j S I M V A 1 104MW+I 61 M W (GS) S A P U G A S K A N D A (PS) 2x31.5 > MVA 3 n A T H U R U G I R I Y A Lynx, 36.0km 2xGoat, 12.5km 147 MVA H 83 M V A 220kV 2x40 MVA 2x150 MVA KELANITISSA Lynx.31.9 km 1 3 2 k V 132kV K O L O N N A W A 1x28.7 MVA 149 MVA SRI J 'PURA 132kV 132kV 5x31.5 MVA 2i3r! MVA 15kV 132kV" 33 kV 220kV 33kV S 2x60 R M V A 100 i l l ( f M v t r ' n VJ< 3x27+ 2x28.7 MVA l l k V - 2x31.5 MVA 33kV 2x250 MVA K O S G A M A S l f H A W PANN1PITIYA 132kV 3x31.5 MVA 132kV D E H I W A L A 33kV 3x31.5 R A T M A L A N A MVA 132kV M A R A D A N A 2x31.5 £ MVA rf l l k V I Zebra.20.0 km 132kV 132kV 2x31.51 MVA I !32kV TJTCT 2x31.5 MVA I32kV 132kV 3x30 MVA 3x30 MVA 132kV 33 kV P A N A D U R A 33kV I M » c y 15.08 M W R A T N A P U R A l l k V — I - 2x35 f S M W v y K U K U L E H O R A N A H A V E L O C K T O W N KOLLUPITIYA 132kV F O R T DEN1YAYA 3x31.5 MVA 33kV M A T U G A M A L y . i H . 4 k m — k e H Lyax, 54.7kl 33kV LINE 2x31.5 MVA 33kV l t k V LINE TRANSFORMER Lynx, 99.7km 3 WINDING AUTO TRANSFORMER I32kV 132kV 2x31.5 MVA 33kV HYDRO POWER STATION MH Mini-Hydro 132kV 2x10 MVA 33kV 1 0 2x30/ MVA >NEW SSSL JURADHAPURA THERMAL POWER STATION DG Dies*! Generator CC Combined Cycle ST Steam Turbine GT G«i Turbine CABLE LLNE HABARANA 1 0 M V , R VALACHCHENA 132kV BREAKER SWITCH CAPACITOR UKUWELA 1x50 MVA 132kV |3x31.5 MVA Y 12.5kV A 1x40 ^ M W BOWATENNA Static v i r compensator 4L65 MW 11BATHKUMBURA THULHIRIYA 220kV 220kV 220kV RANTAMBE 3x96 MVA 3X90 MVA 13.8kV 3x67 MW 2x81 MVA 2x61 MW 220kV 3x31.5 MVA l i l 0 5 MVA KOTMALE •IANDENIGALA 132kV VICTORIA 2x34.5 M V A / 2x32.1 MVA 1S+JI.5 MVA Lynx, 28.0km Lynx, 8 Jkm 132kV WIMALASURENDRA Oriole, 79.9km 132kV POLPITIYA 2x5 MVA 12.5kV 2x37.5 M W BADULLA 2x31.5 MVA 132kV 132kV 2x31.5 MVA 2x15 MVA 33kV Lyni^8.8kni INGINTYAGALA • H A W A K A AMPARA 132kV LAXAPANA CANYON 132kV 132kV 2x31.5 MVA 132kV i.9 kV 2x2.4+2x3.1 MW NEW LAXAPANA 2x72 MVA 2x16+ 2x12.5+ 3x13-33 S 1 8 - 3 3 MVA M W Lvpx, 38.0km NUWARA ELIYA Zebra, 35 km 132kV 132kV 2X16 MVA 2x31.5 MVA 2x71 MVA 10.5kV 2x31 j MVA 132kV M I l ( V ) ' 27.5 M W BALANGODA EMBtLIPITIYA SAMANALAWEWA HAMBANTOTA Ly»I, 103 J km 132 kV TRINCOMALEE legend 220kV LINE I32kV LINE Table 4.11. Maximum three phase fault levels (Continued...) Grid Substation / Power Station Voltage (kV) Existing Switchgear Capacity (kA) Maximum Three Phase Short Circuit Current (kA) 2006 2011 2015 41 K o s g a m a 132 25 7 .6 8 . 0 8 .2 4 2 K o l m a l e P/S 2 2 0 4 0 12 4 14 .2 17.4 132 31 .5 8.7 9 . 9 10.3 4 3 K o t u g o d a 2 2 0 1 0 8 2 0 . 0 24 .9 132 3 1 . 5 / 4 0 14.7 2 7 . 3 23 .8 3 3 25 9 .4 14.2 15.7 4 4 K o t u g o d a N e w 3 3 10 .0 9 .9 45 K u k u l e P /S 132 4 . 8 6.1 8 .0 4 6 Kurunega la 132 25 4.1 5 . 0 5.1 4 7 Laxapana P/S 132 31 .5 17.2 19.7 20 .3 4 8 M e d a g a m a 132 4 . 0 4 . 2 4 9 M a d a m p e 132 4 . 2 11 .3 12 5 0 M a h i y a n g a n a 132 7 . 3 8.1 51 M a h o 1 3 2 25 4 . 3 4 . 0 5 2 Matara 132 31 .5 3 .5 6 . 8 7 .8 5 3 Mathuga ina 2 2 0 16.8 132 4 0 6 .3 9 . 5 17.4 5 4 N e w C h i l a w 2 2 0 13 .7 16.8 1 3 2 14.4 15.5 55 N a u l a 1 3 2 4 .7 8.7 5 6 N e w Anuradhapura 2 2 0 3.1 9 . 3 13.0 132 5 .4 10.7 12.8 3 3 3 .4 4 . 4 4 . 9 5 7 N e w Laxapana 132 3 1 . 5 / 4 0 17 .2 19.7 2 0 . 4 5 8 N u w a r a Hliya 132 31 .5 7 . 9 8 . 9 9 . 2 5 9 O r u w a l a 132 12.4 14.1 14.6 3 3 1.1 1.1 1.1 6 0 Padirippu 132 5 .7 6 . 2 61 P a l l e k e l e 1 3 2 5 .5 6 . 0 6 2 Panadura 132 25 10.9 13 .2 17.9 6 3 Pannala 132 8 .5 10.4 64 Pannip i l iya 2 2 0 50 11.6 15 .9 2 0 . 2 132 3 1 . 5 / 4 0 19.2 2 4 . 9 2 7 . 3 Terl iary W i n d i n g 3 3 14.1 14 7 14.9 65 P o l o n n a r u w a 132 3 . 9 4 .8 6 6 Po lp i t iya P/S 132 17.5 1 7 . 4 19 .9 20 .5 6 7 Put ta lam PS 2 2 0 13.5 17.7 68 Put ta lam G S 132 25 5 . 1 8 .2 7.1 6 9 R a n d c n i g a l a 2 2 0 31.5 8 . 5 10.4 11.1 7 0 R a n t e m b e PS 2 2 0 25 8 . 1 9 . 9 10.6 132 6 . 7 10 2 11.8 3 3 9 . 7 9 .7 9 .9 71 Ra imalana 132 31.5 14 .0 16.8 17.9 5 . 6 7 2 Ratnapura 132 4 . 6 5 .4 7 3 S a m a n a l a w c w a PS 132 31.5 8.5 10.4 11.7 Verm Transr \i,m l)t ; incnl I'lan ' 6-201 I'age 4 :il Table 4.11. Maximum three phase fault levels Grid Substation / Voltage (kV) Existing Switchgear Maximum Three Phase Short Circuit Current (kA) Capacity (kA) 2006 2011 2015 i A m b a l a n g o d a 132 8.1 10.8 2 Ampara 132 31 .5 1.3 5 .4 5 .8 3 A n i y a k a n d a 132 15.1 15 .0 4 Anuradhapura 132 1 5 / 1 1 / 2 0 / 3 1 . 5 5 .4 10.7 12.8 5 Arangala 2 2 0 22 6 Athurugir iya 132 14.1 16.3 17.0 7 Badul la 132 2 5 / 3 1 . 5 6 .5 8 .0 8.5 8 B a l a n g o d a 132 31 .5 8.8 11.4 12.4 9 B a r g e 2 2 0 13.0 18.0 10 Bel ia t ta 132 4 .9 5 .6 1! B i y a g a m a 2 2 0 4 0 14.0 21 .7 27 .4 . 132 31 .5 18.0 26.1 2 9 . 6 3 3 25 10.9 16.0 2 0 . 8 12 B o l a w a t t a 132 2 5 / 1 7 . 5 / 8 . 8 / 1 3 . 1 6 .5 14.0 14.4 13 B o w a t e n n a P / S 132 12.5 3.6 3 .9 4.1 14 C a n y o n P/S 132 2 5 / 4 0 9.5 1 0 2 10.3 15 C h u n n a k u m 132 2 .2 2 .3 16 C o l o m b o _ A 132 16.8 20 .8 2 2 . 3 17 C o l o m b o _ B 132 10.7 18 C o l o m b o _ C 132 2 6 . 2 2 8 . 4 19 C o l o m b o _ E 132 25 19.1 26 .2 28 .4 2 0 C o l o m b o _ F (Fort ) 132 25 18.5 2 5 . 9 28 .1 21 C o ! o m b o _ I 132 18.9 24.1 2 6 . 0 2 2 D e h i w a l a 132 16.6 20 .5 2 2 . 0 2 3 D e n i y a y a 132 4 . 0 5 .9 6 . 2 2 4 E m b i l i p i t i y a 132 31 .5 6.1 8.1 - 11.1 2 5 G a l l e 132 1 0 . 9 / 1 1 / 4 0 2 .3 8 .9 10.4 2 6 Habarana 2 2 0 ' j 19.2 132 2 0 / 2 5 / 3 1 . 5 4.1 7 .7 18.7 2 7 H a m b a n t o i a G S 2 2 0 15.6 132 3 1 . 5 4 .1 4 .1 12.8 2 8 Horana 132 7.5 8 ? Ing in iyaga la ] i :> 12 5 i i 18.4 23 .4 25 .3 31 K e l a n i y a 132 4 0 2 0 . 3 2 8 . 9 31 .7 3 2 Katana 132 r u 16.9 3 3 K e g a l l e 132 5.1 34 Ke lan i t i s sa P/S 2 2 0 5 0 13.5 19.0 22 .2 132 2 5 / 3 1 . 5 2 1 . 0 27 .7 30 .2 3 3 - T 3 3 7 . 0 7.1 7.1 3 3 - A ( load b u s ) 3 3 2 5 / 2 6 . 2 11.2 6 .6 6.6 3 3 - B ( load b u s ) 33 2 5 / 2 6 . 2 9 .8 6 . 6 6 .6 35 K e r a w a l a p i t i y a P /S 2 2 0 17.0 1 9 6 36 K H D P/S 132 3 1 . 5 17.3 2 3 J 2.1 24.8 37 K i l i n o c h c h i 132 2.1 38 Kir ibathkumbura 132 25 6 .9 8 .3 8 .9 39 K i r i m l i w e l a 2 2 0 26.5 4 0 K o l o n n a w a 132 4 0 22.1 29 .4 32.2 Table 3.2 Transmission lines/UG cables proposed for the period 2004-2013 Line Section Volt. / (kV) Ccts. Proposed year Conductor Length / (km) R /cct in p.u. X/cct in p.u. Y7CCT~ in p.u. 132 kV UG cables Pannipitiya - Dehiwala* 132 1 2006 XLPE, 1000 9.0 0.00139 0.00816 0.10346 Colombo I - Kolonnawa* 132 1 2006 XLPE, 1000 4.6 0.00071 0.00417 0.05288 Dehiwala - Havelock Town* 132 1 2006 XLPE, 800 8.5 0.00151 0.00805 0.09073 Colombo A - Colombo I* 132 1 2006 XLPE. 800 6.3 0.00112 0.00597 0.06725 Kelanitissa-Colombo C* 132 1 2008 XLPE, 500 1.6 0.00044 0.00167 0.01401 Colombo C- Kolonnawa* 132 1 2008 XLPE, 500 6.2 0.00171 0.00648 0.05430 Colombo C-Colombo B 132 1 2012 XLPE, 500 2.0 0.00055 0.00209 0.01752 Colombo B-Kolonnawa 132 1 2012 XLPE, 500 4.2 0.00116 0.00439 0.03678 Kolonnawa-Colombo K 132 1 2013 XLPE, 500 5.0 0.00138 0.00522 0.04379 Colombo K-J'Pura 132 1 2013 XLPE, 500 5.0 0.00138 0.00522 0.04379 132kV Overhead lines New Galle-Matara 132 1 2007 Zebra 34.0 0.01487 0.07574 0.017733 Ambalangoda-New Galle 132 1 2007 Zebra 36.0 0.01570 0.07996 0.018720 Habarana-Valachchena 132 1 2007 Zebra 99.7 0.04349 0.22144 0.051850 Kelaniya - KHD*- 132 4 2005 Zebra 3.6 0.00157 0.00800 0.00187 Sapugaskanda GS 132 2 2005 Zebra 1.0 0.00044 0.00222 0.00052 Single in out to Horana from PanaduraT-Mathuaama* 132 2 2005 Zebra 20.0 0.00872 0.04442 0.01040 Mathugama-Ambalangoda* 132 2 2007 Zebra 28.0 0.01221 0.06219 0.01456 Aniyakanda single in out* 132 2 2007 Zebra 5.0 0.00218 0.01111 0.00260 Madampe T- Pannala* 132 2 2007 ' Zebra 15.0 0.00654 0.03332 0.00780 Ukuwela-Pallekele 132 2 2008 Zebra 18.0 0.00785 0.03998 0.009360 Puttalam-Maho lcct stringing/double cct 132 2 2007 2012 Zebra 42 0.01832 0.09329 0.02184 Kothmale-Kiribathkumbura 132 2 2007 Zebra 22.5 0.00981 0.04997 0.01170 Rantembe-Ampara 132 2 2007 Zebra 130 0.05670 0.28874 0.0760 Vavuniya-KiLinochchi 132 2 2007 Lynx 74.1 0.07570 0.17054 0.03610 Kilinochchi -Chunnakam 132 2 2007 Zebra 67.2 0.02931 0.14926 0.03495 Ampara-Padirippu 132 2 2009 Zebra 35 0.01527 0.07774 0.018201 Kolonnawa-Pannipitiya 132 2 2009 Zebra 12.9 0.00563 0.02865 0.00671 Kegaile-Thulhiriya 132 2 2010 Zebra 18.7 0.00816 0.04153 0.00972 Note : T h e line pa r ame te r s are g i v e n in p.u. va lues w.r . t . Zb a u . = V ^ " / M V A b a s e (MVAb a S ( .= 100, Vb a 5 Cin kV). * -committed or under construction l^ii'K Term Transmission Deirlo/jment Studifs 2004' 201J l-age VI [fable 3.1 Existing transmission lines/UG cables cont. r Line Section Volt. / (kV) Ccts. Max. Oper. temp °C Conductor Length / (km) R /cct in p.u. X/cct in p.u. Y / c c t in p.u. Double Circuit cont.. 132 ^apugaskanda GS - Biyagama 2 75 Zebra 4.2 0.00183 0.00933 0.00218 vKolonnawa - Kelaniya 132 2 75 Zebra 6.6 0.00288 0.01466 0.00343 vKelaniya - Kotugoda 132 2 75 Zebra 19.3 0.00842 0.04287 0.01004 yKukule-Mathugama 132 2 75 Lynx 27.0 0.02758 0.06214 0.01315 Total 132kV 2 cct route length 1336.3 Total 132kV 2cct circuit length 2672.6 220 kV transmission lines Single Circuit yVictoria-Randenigala 220 1 75 2xZebra 16.4 0.00129 0.01037 0.03202 /Randenigala-Rantembe 220 1 75 2xZebra 3.1 0.00024 0.00196 0.00605 vfcotmale-New Anuradhapura 220 1 75 lxZebra 163 0.02560 0.13033 0.23545 Total 220 kV 1 cct route length 182.5 Total 220 kV lcct circuit length 182.5 Double Circuit / B iyagama-Kelanitissa 220 2 75 2xGoat 12.5 0.00134 0.00764 0.02361 <-B iyagama-Kotugoda 220 2 75 Zebra 19.6 0.00308 0.01567 0.02831 "Biyagama-Kotmale 220 2 75 2xZebra 70.5 0.00554 0.04457 0.13764 /Kotmale-Victoria 220 2 75 2xZebra 30.1 0.00236 0.01903 0.05877 Pannipitiya-B iyagama 220 2 15 Zebra 15.5 0.00243 0.01239 0.02239 Total 220 kV 2 cct route length 148.2 Total 220 kV 2cct circuit length 296.4 851 Note : The line parameters are given in p.u. values w.r.t. ZbaS£ = V ^ 2 / MVAbaS(: (MVAbase=100, Vbase in kV). * under construction 195 M u t u a l ^ '. Im p e d a n c e y l n /k m 0 .2 0 5 3 5+ j 0 .8 3 6 9 4 0 . 1 6 8 4 6 + j 0 .6 4 7 5 1 0 .2 5 1 5 0 + j 0 .7 K 7 57 0 .1 9 4 6 1 + j 0 .6 1 8 5 6 P o s i t i v e I m p e d a n c e n/ km C O N D U C I O H Z e r o I n p e d a n c e n / k n 0 .3 G 2 7 8 + j 1 . 3G O 89 0 .3 2 5 9 8 + j 1 . 1 7 1 4 0 0 .1 7 8 0 + j 0 .4 0 1 0 0 .1 7 8 0 + j 0 .4 0 1 0 0 .3 9 7 3 5 + j 1 .3 1 1 4 9 0 .1 7 8 0 + j 0 .4 0 1 0 0 .3 5 2 3 0 + j 1 .1 4 2 4 2 0 .1 7 8 0 + j 0 .4 0 1 0 L Y N X 1> :3 / 1 ;:n 0. 66 77 0. 30 19 6+ j 1. 07 74 4 0 .0 3 8 0 + j 0 .3 0 6 0 0 .7 0 3 0 5 + j 0 .5 1 )2 1 ! 0 .2 6 5 7 5 + j 0 . 66 7 7 S 0 .7 0 3 0 5 1 j 0 .5 1 1 2 1 [ 0 .2 6 5 7 7 + i 0 .6 6 7 6 9 0 .2 3 9 1 8 + j 0 .9 2 1 0 4 0 .0 3 8 0 + j 0 .3 0 G 0 7. r; FI R A 2 >: 4< im in 0 . 3 1 2 6 6 + j l .0 7 9 7 4 0 .2 9 6 0 G O A T 2> :1 0 >n m 0 .2 4 9 8 8 + j 0 .9 2 3 3 4 0 .3 3 G 0 1 + j 1 .1 8 8 5 7 0 .0 5 2 0 + j 0 .2 9 G O G O A T 2 x 1 0 in n 0 .0 7 6 0 + j 0 .3 8 7 0 Z E B R A l x l :> r. n 0 .2 7 3 2 3 + j 1 .0 3 2 1 7 0 .0 7 6 0 + j 0 .3 8 7 0 0 3 0 6 + j 0 .5 1 1 1 7 Z K hR A 1 0 .4 7 0 5 4 + j 1 .3 2 5 6 7 0 .2 4 7 0 + C O Y O T K l x l '. in n 0 .2 4 7 0 • C O Y O IF . lx l 1 . 3 2 2 0 0 0 .4 7 2 2 0 + 0 . 2 5 1 5 0 1 0 .4 1 5 4 0 + j 1 .1 5 2 9 8 0 .2 4 7 0 + j 0 .4 1 5 0 0 . 1 9 4 6 1 + j 0 .G 1 8 5 6 T IG L R lx l 0 .4 3 6 0 0 .4 2 1 4 4 + 1 . 3 1 3 8 3 0 .1 9 1 0 + 0. 25 15 01 O R I D L L lx l' M '.n 0 .1 9 1 0 + j 0 .4 3 6 0 0 .3 G 4 6 4 + 1 . 1 4 4 7 0 . 1 9 4 6 1 + j 0 .6 1 8 5 6 0 .0 4 0 0 + j 0 .1 5 1 0 C A U I. L J' -O C u 0 .1 9 1 0 + j 0 .4 3 G 0 C A H L ! 0 .0 8 9 7 + j 0 .3 7 9 4 0 . 2 7 0 3 C +