Dual Current Control of Inverter-Based Resources for Enhanced Resilience and Complying Grid Codes

Inverter-based resources (IBRs) are controlled during faults to inject currents that follow grid codes (GCs). However, these fault currents possess different characteristics compared with those injected by traditional sources. Thus, conventional relays are susceptible to failure when fault currents are emanated from IBRs. This paper proposes a dual current control (DCC) to allow correct operation for the conventional current-angle-based phase selection method (PSM) without violating reactive current requirements imposed by GCs. The proposed method is designed in four stages. First, the positive-sequence current reference is determined according to GCs. Then, an initial negative-sequence current angle reference is determined to impose the relative angle between the negative-and zero-sequence currents to equal the bisector of its correct PSM zone. Subsequently, the reference negative-and positive-sequence current angles are updated such that the relative angle between the negative-and positive-sequence currents and that between the negative-and zero-sequence currents are placed in their correct PSMs zones. Lastly, stationary frame reference currents are designed and controlled to force IBR's current to possess the designed sequence current angles without violating its current limits. Time-domain simulations are carried out for different fault types, locations, and resistances to verify the accuracy of the proposed method.