Abstract

An instantaneous zero sequence voltage injection method is presented in this paper. The key novelty of this method lies in the ability to provide instantaneous zero sequence voltage references using stationary abc-framework variables with no numerical iterations and no phase-locked loops. This paper discusses its applicability, especially in the field of large-scale photovoltaic power plants integration, where the efforts are made to achieve grid energy balancing. As an application example, the proposed method is used to find suitable zero sequence voltage references to extract unbalanced power from each phase in star-connected cascaded H-bridge multilevel converters. Under same conditions, the proposed method allows reactive power control, in contrast to traditional approaches that only consider unity power factor operation. Experimental results are provided to verify the effectiveness of the proposed zero sequence voltage injection method.