A novel ZCZ-filtered single-phase half-bridge distributed static compensator with DC-link filter capacitors and reduced passive component parameters

Distributed Static Compensators (DSTATCOM), composed of power converters and passive filters, have been extensively utilized in the distribution system to improve its power quality (PQ). For selection of passive filters, the LCL filters are increasingly employed to replace the conventional L filters. However, the LCL filters are normally designed for the application of grid-connected inverters (GCI), and therefore the filter components can be further optimized when applied to the DSTATCOM, where the grid-injected current is mainly capacitive. In this paper, a novel LCL-filtered half-bridge DSTATCOM topology is proposed, where the conventional filter capacitor is replaced by the DC-link capacitors with relatively large capacitances. As a consequence, the grid-side filter inductance can be dramatically reduced from the order of millihenry to several microhenry. Furthermore, the current stresses of semiconductor switches can be decreased, resulting in lower power losses and higher system efficiency. Moreover, a constant DC-link voltage can be maintained and the voltage across each capacitor can be well regulated with properly designed filters and controllers. Experiments were carried out on a down-scaled laboratory prototype, and simulation and experimental results are presented to verify the effectiveness of the proposed DSTATCOM topology.