An adaptive K-factor control scheme for inverter-based resources to enhance operation of distance protection

Traditional distance protection may misoperate in the presence of inverter-based resources (IBRs) due to their distinctive characteristics compared to synchronous generators. Various solutions have been presented in the literature to overcome this issue, including a new control scheme for IBRs. This paper proposes a K-factor-based control scheme to enhance the operation of distance relays during all types of faults. In this scheme, based on the fault type, the K-factor—and thus the IBR current references—is adjusted so that the apparent reactance measured by the distance relay’s corresponding element equals the actual line replica reactance. Unlike available methods, all fault ride-through requirements of IEEE Standard 2800–2022 and German grid code, such as those related to the positive- and negative-sequence reactive currents and the maximization of the inverter phase current, are completely fulfilled. The effectiveness and superiority of the proposed scheme over other methods, particularly the conventional fixed K-factor scheme, are validated through extensive simulations in the PSCAD software and testing of an industrial relay in a practical setup.