Approaches to Shunt Active Power Filter for Application with Capacitive Nonlinear Load

This paper analyzes the harmonic characteristics of diode rectifier with a large smoothing dc capacitor, interprets why Shunt Active Power Filter (SAPF) is not suitable for compensation voltage-type harmonic, and reveals the reason why the load peak current is enlarged at the same condition by using the subsection resonance mechanism. Furthermore, two-type methods are proposed to deal with the problems by this paper, i.e. to modify the topology/parameters so as to change the resonant frequency of the system; while the other is to improve and change SAPF's compensation bandwidth to be a selective or limited one. Both of them can suppress the harmonic current effectively and guarantee the load-side current without significant enlargement. Simulation results validate the feasibility of the schemes proposed by this paper.