Research on parallel operation of active power filters

To cope with increasing nonlinear loads in power system, this paper proposes an active power filter(APF) suitable for parallel operation. This APF solves the problems of capacity enlargement. This APF operates independently and has the capacity limitation function of compensating load harmonics. Furthermore, an optimal approach under capacity-limitation is provided for calculating the compensating command current. The output current of each APF is optimized to make the APF has high efficiency and the total harmonic distortion of the source current smaller. The system is fault tolerant and has expansion flexibility. In addition to describe the theoretic bases of the proposed APF, this paper also researches the control algorithm of the APF. Some simulated results are provided for demonstrating the effectiveness of the proposed approach.