Optimization of PI Controller Gains in Nonlinear Controller of STATCOM Using PSO and GA

According to nonlinear operation of STATCOM, nonlinear controller has a better performance in comparison with linear controller. Regulating the DC capacitor voltage in STATCOM is a common task and can improve the system dynamic. The nonlinear control is based on exact linearization via feedback. A PI controller exists in this control system to regulate the capacitor voltage. In conventional scheme, the trial and error method has been used to determine PI controller coefficients. In this paper, the effect of PI gains on responses of Vdc, Id and Modulation Index (M) is presented. The exact calculation of optimized PI coefficients can be carried out to reduce disturbances and steady state error in DC link voltage. Therefore, in this paper, Particle Swarm Optimization (PSO) approach is used. It is shown that capacitor voltage tracks the reference value and vibrations are less than conventional status. Also, Genetic Algorithm (GA) has been used and compared with the results.