Particle Swarm Optimization Optimizing Sliding Mode Control For STATCOM Reactive Power Compensation

STATCOM, an important one of FACTS devices, with its fast response speed, continuous adjustment of reactive power and the advantages of maintaining voltage stability in reactive power compensation of grid, has been further research by electric power research institutes at home and abroad. In this paper, the control system of STATCOM is studied, and the controller is designed based on Particle swarm optimization optimizing sliding mode control. Also, the simulation verify the effectiveness of the controller.Firstly, the paper analyzes the working principle of STATCOM, and establishes the Switching function mathematical model of STATCOM based on the method of KVL. Second, STATCOM model in three-phase static coordinate system is transformed into two-phase synchronous rotating coordinate system by park matrix, and verify the correctness of the model. Then analyzes the main circuit structure characteristic of static synchronous compensator, analysis the main control strategy about STATCOM, namely the control strategy of Current inner ring and voltage outer ring, as well as the control strategy about the dc voltage. Analyzes Current direct control and PWM pulse generating circuit, with triangle wave comparison method to achieved the PWM pulse, On the whole this paper adopts PI control for voltage outer ring and SMC control for Current inner ring.STATCOM is a strong coupling nonlinear system. Its controller designed by sliding mode variable structure control, can significantly improve the dynamic response characteristics and robustness of the control system. This paper expounds a design method of control system by sliding mode variable structure control, in which two-power exponential reaching law is used for weakening the high frequency chattering. Due to the setting of parameters in exponential reaching law is lack of strict theoretical support, thus lead to the reaching law parameters selection has certain blindness. So, Particle swarm optimization is applied to the exponential reaching law parameters adjustment.Simulation results show that the sliding mode controller of two-power exponential reaching law optimized by particle swarm optimization Which designed for STATCOM, the PSO optimization method can solve the problem about sliding mode reaching law parameters setting, also further weaken the chattering of sliding mode.Compared with the conventional sliding mode control, the controller makes the static synchronous compensator in maintaining the grid voltage stability, suppress the current mutation and reactive power compensation, power grid has better control effect.