A Robust Vector Current Controller with Negative-Sequence Current Capability for Grid-Connected Inverters

This paper presents a vector current controller (in the synchronous reference, or dq, frame) with negative-sequence injection capability for three-phase grid-connected converters. is desired operation of converter during unbalanced conditions and also certain type islanding detection. The proposed first determines double-frequency references then uses sixth-order two-input two-output proportional-integral-resonance (PIR) structure, which optimally designed. Compared existing similar approaches, has simpler structure more robust performance, e.g., against system parameter uncertainties weak grid conditions. developed converters both L-type LCL-type filters. For converter, suboptimal partial state feedback control to achieve stability active damping resonance poles without requiring additional sensors. Detailed experimental results are presented illustrate properties performances controller.