A Novel Adaptive Phase-Comparison Distance Protection Scheme for Power Electronics-Dominated Power Systems

Conventional distance protection faces challenges in systems dominated by power-electronics-interfaced resources like direct-drive PMSG wind farms, experiencing Zone 1 under-reach for close-in faults at sending ends and undesired tripping for reverse faults at receiving ends during phase-to-phase faults. This paper proposes a novel Apparent Source Model, an equivalent source whose parameters depend on the external network, establishing a defined power angle to enable traditional analysis methods. Leveraging this model, an Enhanced Phase-Comparison Distance Protection Criterion is developed. The criterion utilizes the difference in the apparent source angle between prefault and fault states and the difference between the apparent source magnitude and the positive-sequence voltage at the relay. By evaluating these quantities, the scheme reliably distinguishes forward internal faults requiring tripping from reverse/external conditions requiring blocking, effectively resolving the identified misoperation issues. Simulation results confirm the scheme's improved reliability and security.