High-reliability and harmonic-sharing dual parallel topology for active power filter

This paper chooses the proportional resonant controller for the controlling of Active Power Filter, and proposed a new control topology for dual parallel APF application. The APF_I near the load side employs the proportional resonant controller to compensate the 5^th, 11^th, 17^th and 23^rd harmonics; The APF_II near the system side also employs the proportional resonant controller to compensate the 7^th, 13^th, 19^th and 25^th harmonics. Both APF_I and APF_II choose the system side harmonic current for feedback control, and also have fast dynamic response due to the proportional resonant controllers. Compared with traditional dual parallel APF, this topology let two parallel APFs have different compensation characteristic, which could compensate selected harmonics and realize harmonic sharing. When one of them is out of working, the other APF could still compensate almost half of all harmonics. Proposed parallel system has advantage for system expansion, cost saving and power-rate improving. The circuit currents for different harmonics are also discussed. This paper analysis the system characteristic and design the system configuration and control parameters. The simulation on MATLAB/simulink also demonstrates the validity and superiority of proposed system configuration and control strategy.