A Series Hybrid Active Power Filter with the function of Adjustable Fundamental Impedance

Abstract

This paper proposed a series hybrid active power filter (SHAPF) with the function of adjustable impedance. The principle of SHAPF based on magnetic flux compensation is addressed. A linear transformer with air gap and multiple secondary windings is chosen, which are injecting specific currents into multiple secondary windings respectively. The fundamental current of primary winding is detected and function as the initial reference signal. And the initial reference signal would be phase shifted to constitute the second type of current reference signals. The multiple secondary windings are also divided into two types, corresponding to be controlled by the two reference currents, so that the primary winding can almost present short circuit for harmonic currents and continuously variable impedance for fundamental current. Besides, the stability condition is derived and analyzed in detail. The simulation results have verified the effectiveness of the proposed SHAPF with adjustable fundamental impedance.