A Distance Protection Method for Phase-to-Phase Short Circuit Faults in Inverter-Based Power Supply Outgoing Lines

This paper proposes a novel approach to address the challenges of distance protection in transmission lines connected to inverter-based resources. To tackle the issue of system frequency offset, an algorithm based on instantaneous values for solving differential equations is introduced, resolving the inaccuracies in phasor extraction inherent in conventional methods. Additionally, a new control strategy for inverters during fault conditions is presented. For Zone I distance protection, this strategy enhances the fault output current of inverters, thereby improving the precision of the differential equation algorithm. For Zones II and III, the strategy clarifies the current relationship of inverter-based power outputs and introduces a fault distance calculation method that accounts for boosting branches. Furthermore, for outlet faults, the strategy increases the reactive current output of inverter-based supplies, leading to the development of a fault direction discrimination method based on reactive current direction. Simulation results demonstrate that the proposed method effectively reduces protection operation time and enhances sensitivity for various inter-phase faults, ensuring reliable fault clearance.