Real-Coded Genetic Algorithm for Robust Design of UPFC Supplementary Damping Controller S. C. Swain, S. Mohapatra, S. Panda & S. R. Nayak Abstract - In this paper is used in Designing UPFC based supplementary damping controllers for damping low frequency oscillations in a single machine infinite bus power system. The detail investigations have been carried out considering the four alternatives UPFC based damping controller namely modulating index of series inverter (MB),modulating index of shunt inverter (ME),phase angle of series inverter ( B) & phase angle of shunt inverter ( E). is employed to optimize damping controller parameters. Simulation results are presented & compared with a conventional method of tuning the damping controller parameters to show effective of the proposed design approach. Keywords - Power system oscillation, UPFC damping controller, Flexible AC transmission systems (FACTS),. I. INTRODUCTION With the application of FACTS technology, power flow along transmission lines can be more flexible controlled. UPFC can provide simultaneous & independent control of important power system parameters: line active power flow, line reactive power flow, impedance and voltage. is more efficient in terms of CPU time & offers higher precision with more consistent results. II. MODELING THE POWER SYSTEM WITH UPFC DAMPING CONTROLLER. This arrangement, comprising two parallel transmission lines, permits the control of real & reactive power flow through line. III. OBJECTIVE FUNCTION UPFC based controllers are designed to minimize the power system oscillation after a disturbance so as to improve the stability. IV. REAL-CODED GENETIC ALGORITHM Chromosome representation : Each individual or Chromosome is made up of a sequence of Genes. Various types of representations of an individual or chromosome are: binary digits, floating point numbers, integers, real values, matrices, etc. Selection function : The selection function determines which of the individuals will survive & move on to the next generation. Genetic operators: The basic search mechanism of GA is provided by the genetic operators. There two basic types of operators: crossover & mutation. These operators are used to produce new solutions based on existing solutions in the population. crossover takes two individuals to be parents & produces two new individuals while mutation alters one individual to produce a single new solution. Initialization, termination & evaluation function: An initial population is needed to start the genetic algorithm procedure. The initial population can be randomly generated. Special Issue of International Journal of Power System Operation and Energy Management, ISSN (PRINT): 7, Volume -, Issue 5
GA moves from generation to generation until a stopping criterion is met. Evaluation functions of many forms can be used in a GA so that the function can map the population into partially ordered set...5..5. V. SIMULATIONRESULTS Case : β-based UPFC damping controller x delb based UPFC damping controller.5 -.5 Fig. 5 : Electrical power deviation response for 5% Case : E based UPFC damping controller - x based UPFC damping controller - Fig. : 5% increase in mechanical power input - - x Fig. : 5% increase in mechanical power input - - x (pu) - Fig. : Speed deviation response for 5% step increase in Pm -..5 Fig. 7 : Speed deviation response for 5% step...5.5...5.5..5 -.5 Fig. : Electrical power deviation response for 5% -.5 Fig. : Electrical power deviation response for 5% Special Issue of International Journal of Power System Operation and Energy Management, ISSN (PRINT): 7, Volume -, Issue 5
..5 x based UPFC damping controller data..5. -.5 - -.5 Fig. 9: Electrical power deviation response for 5% Case : based UPFC damping controller. Fig. : 5% increase in mechanical power input x x based UPFC damping controller data - - - - Fig. : Speed deviation response for 5% step Fig. : 5% increase in mechanical power input Case : based UPFC damping controller x - - Fig. : Speed deviation response for 5% step x - - Fig. : Speed deviation response for 5% step increase inpm. Special Issue of International Journal of Power System Operation and Energy Management, ISSN (PRINT): 7, Volume -, Issue 55
x performance of - based UPFC damping controller is slightly better among four alternatives. Case : Comparison four alternative UPFC damping controllers for step change in reference voltage x - - (pu) Fig.5 : Speed deviation response for 5% step increase in Pm. Case 5: Comparison four alternative UPFC based damping controllers. - Fig. : Speed deviation response for 5% step increase in V ref x x (pu) - - Fig. : Speed deviation response for 5% step Fig.9 Speed deviation response for 5% step increase in V ref x 5.. Variation in Machine Inertia Case 7: Effect of parameter variation on the performance of UPFC damping controllers. (pu).5 x.5 - Fig. 7 : Speed deviation response for 5% step increase in Pm. 5.. Disturbance in reference voltage setting. The reference voltage is increased by 5%,5% at t=. & system dynamic response with all four alternative damping controllers is shown in fig. The (pu).5 -.5 Fig. : Speed deviation response for 5% step increase in Pm with 5% decrease in M Special Issue of International Journal of Power System Operation and Energy Management, ISSN (PRINT): 7, Volume -, Issue 5
Fig. : Speed deviation response for 5% step increase in Pm with 5% decrease in M. 5.. Variation in Direct Axis Transient Time Constant (pu) Fig. : Speed deviation response for 5% step increase in Pm with % decrease in T do (pu).5 x.5.5 -.5 x Fig. : Speed deviation response for 5% step increase in Pm with % decrease in T do VI. CONCLUSION: The design problem is transferred into an optimization problem & is employed to search for the UPFC based controller parameters. Simulations are presented & compared with a conventional phase compensation technique for tuning the damping controller parameters to superiority of the proposed design approach. - x - In this paper we have successfully studied the out of system at different parameter variation. We have studied at output at variation mechanical power disturbance in reference voltage setting & variation in system parameters like machine inertia, variation I circuit direct axis transient time constant. We have concluded that the oscillation in power system is minimized by use of optimization. APPENDIX A DATA OF SINGLE MACHINE INFINITE BUS POWER SYSTEM WITH UPFC System data: All data are in pu unless specified otherwise. Generator: M=.s, D=, X d =., X q =., X d =., T do =5., Pe=., V t =V b =. Excitor: K A =, T A =.s Transformer: X te =., X E =X B =. Transmission line: X BV =., X e =.5 UPFC parameters: m E =., m B =.79, E = -5.7, B = -7.7,V dc =., C dc =. REFERENCES [] L. Gyugyi et. al., The Unified Power Flow Controller: A New Approach to Powe Transmission Control, IEEE Trans. Power Delv.Vol., No., pp. 5-9, 995. [] Sidhartha Panda, S.C. Swain, P.K. Rautray, R. Mallik, G. Panda, Design and analysis of SSSCbased supplementary dampingcontroller, Simulation Modelling Practice and Theory, doi:./j.simpat...7 [] Sidhartha Panda, Multi-Objective Evolutionary Algorithm for SSSCBased Controller Design, Electric Power System Research, Vol. 79,Issue, pp. 97-9, 9. [] Sidhartha Panda, Differential Evolutionary Algorithm for TCSC-Based Controller Design, Simulation Modelling Practice and Theory, Vol. 7,pp. -, 9. [5] M.nambu & y.ohsawa, Development of an advanced power system stabilizer using a strict linearization approach, IEEE transations on power systems, vol. pp--,99. [] M.E.About-Ela, A.A.sallam,j.D.McCally & A.A. fouad, Damping controller design for power system oscillations using global signals, IEEE Special Issue of International Journal of Power System Operation and Energy Management, ISSN (PRINT): 7, Volume -, Issue 57
Transactions on power system, vol.ii,pp 77-77,99. [7] Sidhartha panda, A.K. baliarsingh, R.K.sahu, Multi-objective optimization Technique for TCSC Based supplementary damping controller design proceedings world congress on Nature & Biologically inspired computing (NaBIC 9), st st Dec.,9 bhubaneswar, india,pp.5-7,9. [] N.Tambey, M.L.kothari, UPFC Based damping controllers for damping low frequence oscillations in a power system,ie(i) journal EL,vol.,pp55,. Special Issue of International Journal of Power System Operation and Energy Management, ISSN (PRINT): 7, Volume -, Issue 5