A feed-forward based harmonic compensation approach for low switching frequency grid interfacing VSI

摘要

Embedding voltage harmonic compensation function in Distributed Generation (DG) systems is a promising solution for the increasing concern about power quality in distribution grid. This paper focuses on adding harmonic compensation function to these low switching frequency DG systems and applies a current feed forward method to overcome the bandwidth limit in their feedback control loop. The complex feed forward gain is designed based on the virtual impedance theory. By applying discrete modeling method, the zero-order-hold characteristics of low switching frequency PWM are accurately modeled. The stability analysis in z domain is also given to verify its applicability and advantage in stability. Finally, the good compensation performance is validated by experiment results.