Comb filters for harmonics control in grid connected power electronic converters applications

Abstract

This paper presents the method of current higher harmonics control for grid connected power electronic converter by means of a digital comb filter application. The proposed method provides multiple harmonics compensation and simple implementation. The Proportional-Resonant (PR) control was complemented with appropriately tuned comb filter which resulted in reduced mitigation of output current harmonics and reduced THD. Two types of comb filters have been verified as a harmonic compensator namely feedback and feedforward structures. The compensator based on the feedback comb filter included additional casual FIR low-pass filter for increased robustness. Proposed FIR filter is casual therefore its implementation on the digital microprocessors is greatly facilitated. The experimental results have demonstrated the effectiveness of proposed solution for grid connected converter operating in a network with distorted supply voltage.