Design of Current Reference Controller for Inverter-Based Resources to Emulate Short-Circuit Behavior of a Synchronous Generator

Abstract

Renewable resources are mostly interfaced to the grid through inverter systems with dictated behavior during short-circuit faults depending on the manufacturer design and specifications. The unconventional short-circuit behavior of inverter-based resources (IBR) challenges the conventional protective functions, causing spurious tripping for some external fault conditions and no tripping for some internal faults. An approach to alleviate the IBR protection issues is to develop new protective functions compatible with the fault response of IBRs. However, in a transmission system with high penetration of IBRs, many protective relays throughout the grid could be affected so that replacement of a large number of conventional relays is not practically feasible. Rather, it is economically beneficial to design the control system of IBRs so as to mimic the fault behavior of a conventional synchronous machine. This paper presents a current reference controller for the full-converter IBRs to utilize the maximum current capability of the inverter power-electronic switches while emulating the incremental sequence current magnitudes of a conventional synchronous generator. Conducting simulation studies in the PSCAD/EMTDC program, it is shown than the proposed method is well capable of achieving the mentioned goal for all fault types.