iMOV — An Active, Controllable Overvoltage Protection Device for Multi-Inverter Microgrids with High IBR Penetration

This paper presents a low-cost, intelligent Metal-Oxide Varistor (iMOV) concept that provides active and controllable overvoltage protection for inverter-based-resource (IBR) dominated systems. The iMOV can sensitively clamp any high energy, overvoltage transient within a tight margin of the system’s nominal voltage to effectively protect semiconductor devices in power converters from voltage-induced breakdown failure. In detail, the iMOV uses two series-connected MOVs with a power electronic switch to provide active overvoltage clamping within 20% of the system's nominal voltage. Furthermore, the iMOV is also integrated with microprocessors and sensors to facilitate a self-triggering mechanism based on local voltage measurements, enabling a decentralized architecture. In this paper, the operation principles of the iMOV are articulated and preliminary feasibility is shown through simulation results. Lastly, an experimental setup is developed to validate the iMOV and highlight the voltage-sharing challenge of two series connected MOVs in a realistic hardware-based scenario.