Study on large power shunt active power filters with high compensation precision

Shunt Active Power Filters (APFs) are suitable to compensate current-type harmonics generated by nonlinear load, but large power and high compensation precision is difficult to be obtained due to low switching frequency of high power switch devices e.g. IGBTs and phase lag of digital control loop. In this paper, a high equivalent switching frequency is obtained in spite of low real switching frequency by using Carrier Phase Shifted SPWM (CPS-SPWM) technique. In addition, repetitive control algorithm with differential compensator is adopted to eliminate steady-state error of control loop. Based on these two approaches, very large power and high compensation precision can be obtained. Simulation results validate the feasibility of the schemes proposed by this paper.