Grid-Forming Nature Retaining Fault Ride-Through Control

A ride-through controller is proposed to enable inverter based resources (IBRs) to retain grid-forming (GFM) nature under current-constrained operation, such as faults or overload conditions. In this context, GFM nature for IBR is denoted by a voltage source behind reactance that preserves synchronism with the grid leveraging power-synchronization. A comparative analysis of existing GFM controllers is presented to demonstrate that the current state-of-the-art, either fails to preserve the GFM nature under fault, or offers only sub-optimal ride-through performance with regard to converter capacity uti-lization and transient stability. The proposed solution maximizes capacity utilization while retaining GFM nature under fault as well as enhances transient stability. Furthermore, detection of fault occurrence and/or clearance is not required and the identical control structure is preserved regardless of normal or fault/overload operation. Hence, the proposed controller avoids recurring fault-mode operation observed for existing GFM controllers at fault clearance especially under weak grid conditions. Experimental results are presented to validate the proposed solution.