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 utilization 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.
