Approach to low-cost prevention of DC injection in transformerless grid connected inverters

With the growing popularity of distributed generation, there are concerns over the effects that distributed generators may have on power quality. One highly important aspect often overlooked when considering power quality is DC current and the effects that it may have on distribution components. This study considers the problems associated with DC current injection into the electricity distribution network from transformerless grid connected inverters. A new method of preventing differential mode DC injection from transformerless inverters is proposed which eliminates the need for a bulky and costly isolation transformer. This technique is experimentally validated and its benefits regarding DC injection reduction are shown.