A Novel OPAL-RT Real-time Simulator-based Experimental Approach to Study Open-Switch Faults of Interfacing Inverters of Renewable Distributed Generation in Microgrids

With increasing penetration of renewable energy sources in electric distribution systems, the microgrid is a fundamental building block for grid modernization. Renewable distributed generation (DG) units are connected within a microgrid through interfacing inverters equipped with advanced control schemes, and these inverters play an essential role in microgrid operations. However, DG interfacing inverters may fail due to various faults. In this paper, an experimental investigation of open-switch faults using a 2 kW three-phase two-level conventional voltage source inverter (VSI) is conducted through the Opal-RT real-time simulator test bench in the lab, where three grid-forming inverter control schemes (droop control, virtual synchronous generator (VSG) control, and VSG with a Fuzzy secondary controller) are implemented under healthy and 21 single- and multi-open-switch fault conditions. Five inverter loadings (30%, 45%, 60%, 75% and 90%) are also implemented in the testing. Three phase voltage and current signals were recorded at the inverter output/load terminal during experiments, which provided unique and novel datasets for studying inverter open-switch fault diagnosis in microgrids.