Reduction of common-mode current in parallel connected PV-inverters with negative grounding

Abstract

This paper is focused on the analysis and reduction of the common-mode current for parallel inverters with negative grounding in the photovoltaic (PV) generation system. Due to the existence of the solar parasitic capacitance to ground, transparent conductive oxide (TCO) corrosion occurs in some type of thin-film solar modules. The negative terminal of the thin-film array can be directly connected to the ground in a single PV-inverter to avoid TCO corrosion. However, a large common-mode current is injected when the negative terminals of parallel inverters connect to the ground directly. The performance of the proposed control strategy is verified by a PV system. The experimental results show that the performance of the proposed control strategy is as expected.