Fuzzy logic based indirect current control of the shunt active power filter

This paper presents a fuzzy logic based controller for indirect current control of shunt active power filter. Estimation of the fundamental component of the line current is based on its effect on the voltage of the inverter DC side capacitor. To improve the classic PI controller used in this scheme, a decaying factor is introduced to its integral part. Proportional and integral gains are constant, but the decaying factor varies according to the system condition. Since the appropriate performance of this controller is greatly dependent on the decaying factor, a fuzzy logic based system is used to determine the proper value of this parameter, in which the decision is made on the basis of the voltage error of the inverter DC side capacitor. Computer simulation of a typical power distribution system with a nonlinear load and shunt active power filter is carried out and the results are presented which imply a better dynamic performance of the proposed scheme compared to the conventional PI controller.