Predictive current control of grid-connected voltage source converters during network unbalance

Abstract

This study proposes an improved predictive current control (PCC) scheme for grid-connected voltage source converters (GC-VSCs) during network voltage unbalance. The control scheme is based on space vector modulation (SVM) and implemented in the positive synchronous reference frame without current-sequential decomposition. Because of the requirement of controlling the double-frequency negative sequence components, detailed compensation methods accounting for control delay and a finite sampling frequency are analysed and designed for the proposed PCC scheme to improve the control accuracy and increase the control bandwidth. Experimental results are compared with those of conventional vector control with single proportional integral (PI) and dual PI current control schemes, and demonstrate the effectiveness of the proposed control strategy during steady-state and transient conditions when the network voltage is unbalanced.