Simulation Study On Static Var Compensator In Damping Power System Low Frequency Oscillation

With the expansion of power system and the improvement of degree of interconnection,power oscillation brings new problems to the power system stability analysis.Static Var Compensator(SVC) has made significant effects in the system reactive power compensation and improving system voltage stability of engineering application. At the same time, there is an extremely extensive application prospect in the inhibition of the system power oscillation.This paper is committed to the research and design of the wide-area additional damping controller of SVC,which considering the delay of the influence of the WAMS feedback signal in the event of power system low frequency oscillation situation. In this paper, the particle swarm optimiazation(PSO) is used in the parameters design of SVC controller to solve the system nonlinear problem.Also,the simulation is done on IEEE 4-machine-2area system.Firstly,the basic structure and control principle and control strategy of SVC is introduced.The control system and the working principle of SVC is simulated on the equivalent single machine infinite bus system in MATLAB.In addition, the classical second order model of single machine infinite bus system and the practical application generator Phillips-Heffron model are used to discussing the principle of the SVC to damping the low frequency oscillation of power system in this paper.Both models can proved that SVC has increased the system damping coefficient, and restrain the low frequency oscillation of the power system.Then,the basic algorithm principle and flowchart is introduced.Also, the optimize results of some improved PSO algorithms are compared to establishes the Ellipse weight strategy for the SVC damping controller parameters optimization strategy.The simulation experiment in a 2-machine test system shows that when the system suffers from faults and interference,the proposed controller is better than the conventional PI controller to damping the active trend oscillation.Finally,Considering the transmission delay of the wide-area measurement system(WAMS) feedback signal, a PSO optimization strategy of the wide-area SVC additional damping controller parameters based on Prony identification is proposed.In order to chose the suitable wide-area feedback signal,the one which has the largest geometric considerable degree corresponding with the interval oscillation mode is selected as a feedback signal wide-area SVC additional damping controller input signal. Prony identification is introduced to determine the dominant mode damping ratio as the optimization target of the PSO optimization algorithm for the nonlinear model parameters optimization design.This model of IEEE 4-machine-2area system with SVC is build in MATLAB.Compared with EWPSO parameter design,SVC controller designed by PPSO optimization algorithm can suppress the low frequency oscillation more effectively.