An Overview of DC Component Generation, Detection and Suppression for Grid-Connected Converter Systems

Transformerless grid-connected distributed photovoltaic (PV) systems (TGCDPVs) has the merits of high efficiency, small size, and low cost, draws great interest in recent years. However, Direct Current (DC) injection is a serious issue in TGCDPVS, which degrade its power quality. Some publications have discussed DC component generation and suppression methods; however, there are very few systematic reviews on the generation, detection, and suppression of DC component in TGCDPVS. For young researchers and designers working in photovoltaic power generation systems, the DC injection suppression is of great importance. This paper first reviews a number of issues related with dc component in TGCDPVs, the DC current generation and its detriments to the grid are reviewed at first, then, a comprehensive review on the latest DC detection method are performed, finally, various DC suppression solutions are given. Comparisons between various DC component detection and suppression methods are discussed. In the end, some future suggestions are given. This review shall provide a useful guideline and a clearer vision for researchers to determine the best solution for DC suppression in their PV product.