Research On The Inhibition Of DC Component Of PV Inverter

In recent years, photovoltaic generation has a rapid development. As main equipment in photovoltaic system, photovoltaic grid-connected inverter should be given great attention. Due to various reasons, the AC output of inverter contains a DC component, which will not only harm equipments, but also threaten power quality of the power system. So it’s important to restrain and compensation this problem.This article first compare and analysis several kinds of photovoltaic inverter topology which are widely used in photovoltaic generation system. The AC output of isolation photovoltaic grid-connected inverter contains almost no DC component. But the non-isolation type inverter will transfer DC component to the power grid as the absence of isolation transformer.Secondly, the article also summarizes the DC output technical requirements of photovoltaic grid-connected inverter in domestic and foreign, analysis the DC output mechanism and harm of non-isolation photovoltaic grid-connected inverter. Restrain methods have also been discussed from software and hardware.Thirdly, the existent restrain methods are analyses, mainly from inverter topology structure improvement, capacitive DC blocking method, and DC component detection circuit improvement, etc.Finally, a comprehensive DC component control method is proposed based on the existing DC component restrain methods, in which virtual capacitance method and average current method are adopted, two levels of feedback are used in the control loop. Finally, a simulation example validates the feasibility of these control algorithms.