Parallel converter scheme for large power high compensation Precision Shunt Active Power Filters

Shunt Active Power Filter (APF) is a good solution to eliminate current-type harmonics generated by nonlinear load. Challenges exist in realization of large power and high compensation precision simultaneously due to the limited capacity of semiconductor devices, thermal management, high slew rate of compensation current, low switching frequency and phase lag of digital control loop etc. This paper introduces the issue of developing a practical 527 kVA APF prototype by using dual converters paralleling approach. The circulation current between the two converters was effective suppressed depending on the consistency of the main circuit and drive circuit. With a superior and reliable digital control method and an additional high-pass filter branch, large power and high compensation precision are both achieved. Full power prototype tests validate the feasibility and stability of the proposed scheme.