Improved Methodology for Testing the Compliance of Residual Current Detection of Non-Isolated Grid-Connected Photovoltaic Inverters

Abstract

Ensuring user safety in transformerless photovoltaic (PV) inverters is crucial due to the high leakage current caused mainly by the PV modules’ capacitance. Compliance with safety standards IEC 62109-2:2011 and IEC 63112:2021 demands leakage current tests utilizing a variable resistive-capacitive (RC) load. However, limited research has been conducted to assess the impact of test parameters on result conclusiveness. To address this gap, this paper investigates the influence of AC mains voltage phase angle on trip time results in the continuous leakage current test as per these standards. Our experiments, performed with five commercial transformerless PV inverters, reveal significant sensitivity of the results to this specific parameter. Supported by RMANOVA analysis, our findings substantiate this observation. Subsequently, we discuss potential strategies to enhance the accuracy of test outcomes and propose a well-defined methodology to ensure repeatability and reliability of results.