Dispatchable Virtual Oscillator Inverter: Fault Mitigation in Weak Grids

This work proposes a fault mitigation strategy for Dispatchable Virtual Oscilator (dVOC) grid-forming (GFM) controlled inverters operating in ultra-weak grid scenarios, i.e., with Short Circuit Ratio (SCR) close to 1. The proposed strategy enables the operation of the dVOC-based GFM inverter with SCR <1 and with power angle δ in four-quadrant range during high impedance faults. This is achieved by operating the inverter with constant amplitude voltage and regulating δ using only local measurements. The proposed strategy is validated by Controller-Hardware-in-Loop results using industry-grade hardware.