A Novel b-shaped L-type Transformerless Hybrid Active Power Filter in Three-Phase Four-Wire Systems

This paper presents a novel b-shaped L-type transformerless hybrid active power filter (HAPF) for reactive power, current harmonics and neutral current compensation in three-phase four-wire distribution power system. The passive filter (PF) is tuned to compensate the dominant harmonic current and also reactive power of the load, while the active power filter (APF) compensates the remaining harmonic and reactive power values. With appropriate design of the system parameters, the novel HAPF topology can prevent most of the fundamental voltage and current across the APF. This results in a great reduction of the APFs VA rating, but without significantly deteriorates the system compensation capability. Moreover, transformerless HAPF benefits by eliminating the transformer phase shift, voltage drop, harmonics loss, bulky size and expensive cost. As a result, the proposed HAPF is characterized by small APF capacity, economical cost, well filtering effect and easy realization. And it is suitable to be implemented in high voltage and current conditions. A DC-link power flow controller is also employed to uniform its voltage level. Finally, simulation results are given to verify the viability and effectiveness of the novel HAPF.