IMPROVEMENT OF POWER SYSTEM OPERATION USING SIMULINK MODEL OF UPFC

Vinay Kakkar1, Narendra Kumar2 and Nirmal Kr. Agarwal3

1Asso. Prof. EE Dept. IPEC Ghaziabad E-mail: vkakkar123@gmail.com,2Prof EE Dept. DCE Delhi, E-mail: dnk_1963@yahoo.com,3Asst. Prof. EE Dept. JSSATE Noida E-mail: nirmalnitham@gmail.com

ABSTRACT

This paper deals in a systematic approach for designing Unified Power Flow Controller (UPFC) based dampingcontrollers for damping low frequency oscillations in a power system. Fuzzy logic is also incorporated to damp lowfrequency oscillation Detailed study have been done and their simulink models are generated considering fouralternative UPFC based damping controllers. The comparative study is also done with and with out damping controllerusing simulink model.

ISSN : 0973-7391

IJCSC Volume 4 • Number 1 • January-June 2013 pp. 37-42

1. INTRODUCTION

Power systems over the worldwide becoming complexday to day and continuous requirements are coming forstable, secured, controlled, economic and better qualitypower. These requirement become more essential whenderegulation environment becoming more vital andimportant. Power transfer capacity in transmissionsystem is limited due to various factor such as steadystate stability limit, thermal limit, transient stability limitand system damping or even negative damping. Thescenario of the magnitude of various limits are givenin Figure 1.

Figure 1: Various Limit of Transmission Line

The electrical damping of power system require tobe mitigate to stable oscillations free power transfer.Flexible AC Transmission System and Distributed

Flexible AC Transmission System provides feasible andcost-effective solution to these problems and so thesedevices are required to use worldwide for improvingperformance of power system

2. EXPERIMENT

(A) Basic Approach

The SMIB test system has been considered for evaluatingthe performance of developed controller. Firstly we willsimulate the Heffron- Phillips model for SMIB withoutany controller, and then UPFC will be installed in thatsystem to see the system behavior. Afterwards we willcarry out simulation study of the damping controller forUPFC for enhancing the transient stability of the SMIBsystem.

(B) Single Machine Infinite Bus (Smib) SystemWe analyze the SMIB with and without UPFC. Initialcondition and system data are given in Appendix A. Tosee the system performance, we have to build Heffron-Phillips model for SMIB. Using initial data condition andbasic equation given in Appendix B, we calculate theK-constants (K1, K2, K3, K4, K5 and K6) [6] for above testsystem. Using these different calculated K-constant, makeHeffron-Phillips simulation model using SIMULINK.

Figure 2: (a) Single Machine Infinite Bus (SMIB) System

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(C) Smib System Without UPFC

Using given data, with input of step load perturbationand calculated K constant value, we form a simulationmodel shown in Fig. 2(b)

Figure 2: (b) Simulation Model for SMIB System without UPFC

The output of this simulation model is taken as speeddeviation (�w) and angle deviation (��). So, the followingresponse is formed for speed deviation (�w) and angledeviation (��) against time from simulation model usingSMIB system. The simulation process is carried forduration of 10 second. The time division scale isconverted in to points i.e. 10s = 300 points.

Figure 3: Response of SMIB system Without UPFC

From viewing response of the system we have, thevariation in speed and angle is oscillatory in nature. Dueto formation of these oscillations the system is unstable.To improve the system performance and getting thestable position we have to eliminate these oscillations.To eliminate these oscillations and improving systemperformance we install UPFC with this SMIB system.

(D) SMIB System with UPFC

As primary function of UPFC is not only the power flowcontrol but also transient stability and damping theoscillation in power system. In this case UPFC is installedwith in line, to damp the oscillation occurred due to loadperturbation. The data for UPFC is also given inAppendix A. To see the performance of system installedwith UPFC, the procedure is same for this case asdescribed in case of without UPFC. We make a modifiedHeffron- Phillips model for SMIB system using UPFC.In this case we use the dynamics and linearized modelof UPFC. In this case we are not only calculating themodified K-constants for Heffron-Phillips model, butalso the constants for FACTS device which are installedin system i.e. Kp, Kq and Kv. These constants are requiredto see the effect of FACTS devices on power system.

As we know that, the significant control parametersof UPFC are mB, �B, mE and �E. By controlling mB, themagnitude of series injected voltage can be controlled,therefore controlling the reactive power compensation.By controlling �B of series converter results in real powerexchange.

By controlling mE the voltage at a bus where UPFCis installed is controlled through reactive powercompensation. By controlling �E, easier to regulates thedc voltage at dc link. Hence by taking considerationof individual control parameters of UPFC i.e. based onmB, �B, mE and �E, we will investigate the performance ofSMIB system.

Again, In this case also, we see the response ofsystem for speed deviation and angle deviation againsttime. The value of FACTS device constant (Kp, Kq andKv) is different for each control parameters of UPFC i.e.

Improvement of Power System Operation Using Simulink Model of UPFC 39

based on mB, �B, mE and �E. The simulation model of SMIBsystem with UPFC is shown in Fig. 4. The response ofsystem with individual control parameter of UPFC isshown in figures below.

Figure 4: Simulation Model for SMIB with UPFC

Figure 5: Response of System from mB Based UPFC

Figure 6: Response of System from B Based UPFC

Figure 7: Response of System from mE Based UPFC

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Figure 8: Response of System from E Based UPFC

(E) SMIB System with Damping Controller for UPFC

As we can see that using UPFC the oscillation of SMIB isreduced. But still the system is having oscillations whichshould be damped. So we install a damping controlleron UPFC. The procedure for designing the dampingcontroller is already given in Chapter 5. The controllerdesign is based on compensation technique. Thedamping controller having the input as speed deviationand controller output is input to the UPFC device. Thesimulation model is shown in Fig 9.

Figure 9: Simulation Model of SMIB using DampingController for UPFC

In this case also, the formation of damping controlleris based on control parameter of UPFC i.e. mB, �B, mE

and �E. The corresponding gain and phase compensationconstant is different for every control parameter basedUPFC. To see the performance of SMIB system, outputis taken as in terms of angle deviation i.e.. ��. Theresponse of system is formed by using mB baseddamping controller for UPFC is shown in Figure 10.

Figure 10: Response of System from mb Based UPFCwith Damping Controller

(F) SMIB System with Fuzzy Controller for UPFC

As the response of SMIB system with damping controlleris shown in Fig. 10. In this sub section we install a fuzzydamping controller for UPFC. The input given to fuzzydamping controller is .w and its integral. The outputformed from fuzzy logic controller is given as input toUPFC. Here also, the formation of fuzzy controllerdepends on mB, �B, mE and �E parameter based UPFC.The simulation model is shown in Figure 11. Fordesigning purpose of fuzzy damping controller, inpreprocessing state a gain and signal washout is usedwhose values can be tuned depending upon which typeof UPFC (based on control parameter) is used. In thissimulation model a MATLAB function code isintroduced which works as fuzzy logic controller. Thevalue of controller gain variable and constant used infuzzy logic controller are adjustable.

The following response of system is formed usingmB, �B, mE and �E based UPFC using fuzzy controller.

Improvement of Power System Operation Using Simulink Model of UPFC 41

Figure 11: Simulation Model for SMIB using FuzzyDamping Controller for UPFC

Figure 12: Comparison of Plot Based on Differentmb, b,me and e Fuzzy Damping Controller

3. CONCLUSION

The response of SMIB using UPFC with dampingcontroller and fuzzy controller are shown in Fig 10 andFig. 12 respectively. In comparison of both compensationtechnique and fuzzy technique based controller, theresponse of fuzzy based controller is better. Looking atFig. 10 and 12, it is evident that peak overshoot in angleof machine with fuzzy damping controller is negligiblewhere as it has a visible high value in range of 13-15%with compensation based damping controller. Thus itcan be concluded that system is stabilized quickly andefficiently with fuzzy damping controller.

APPENDIX A

The nominal parameters and the operating conditionsof the SMIB system are given below (all value in pu):

Generator:H = 4

M = 2H

D = 0.0

Tdo’ = 6.0 sXd = 1.0

Xq = 0.6

Xd’ = 0.3

Excitation System:Ta = 0.01s

Ka = 100

Transformer:

XtE = 0.1XE = 0.1

XB = 0.1

Transmission Line:

XBV = 0.3Operating Condition:

Vt = 1.0

Vb = 1

Pt = 0.2f = 50 Hz

UPFC Parameters:

mB = 0.0789

mE = 0.4013

�B = –78.2174°�E = –85.3478°

Parameters of DC link:

Vdc = 2

Cdc = 1

REFERENCES[1] Z. Hamid, I. Musirin, M.M. Othman, M.R. Khali

“Optimum Tuning of Unified Power Flow Controller viaAnt Colony Optimization Technique” The 4th

International Power Engineering and OptimizationConference (PEOCO2010), Shah Alam, Selangor,Malayasia 23-24 June 2010.

[2] A. Rajabi-Ghahnavieh,M. Fouthi Firuzabad, M.Shahidehpour, R. Feuillet, “UPFC for Enhancing PowerSystem Reliability” IEEE Transaction on Power Delivery,25 No. 4, October 2010.

[3] S. Jamali,A. Kazemi, H. Shateri “Distance Relay Over-Reaching Due to SSSC Presence on Second Circuit ofDouble Circuit Line” Industrial Electronics and Application,2008, 3rd IEEE Conference Issue , 3-5 June 2008 pp. 918- 923First Initial, Middle Initial, Last Name, “Book Title”.Publisher, Location, year.

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[4] G.I. Rashid,H.I Saheen, S J .Cheng “Nonlinear PI PredictiveControl Design for Thyristor Controlled Series Compensator”Transmission and Distribution Conference and Exposition,2008. T&D.IEEE/PES 21-24 April, 2008, pp. 1-7.

[5] M. Khederzadeh,A. Ghorbani,A. Salemnia “Impact ofSSSC on the Digital Distance Relaying” Power and EnergySocity General Meeting, 2009 IEEE , Issue, 26-30 July 2009pp. 1-8.

[6] K.R. Padiyar., “Power System Dynamics Stability andControl”, 2nd Edition, BS Publications, 2002.

[7] Mohammad Hasan Raouf, Ebrahim Rasooli Anarmarzi,Hamid Lesani, and Javad Olamaei “Power SystemDamping Using Hierarchical Fuzzy Multi- Input PowerSystem Stabilizer and Static VAR Compensator”International Journal of Electrical and ElectronicsEngineering 5:2 2011 pp. 117-123.