Performance Analysis of Pilot Zero Sequence Directional Protection for Double Circuit Transmission Lines under Complex Fault Condition

Double-circuit transmission lines are widely used in UHV transmission, which can improve the reliability of the lines. The pilot zero-sequence directional protection has a high sensitivity to asymmetric ground faults of the entire power grid. During the period when complex faults occur on one circuit of double-circuit transmission lines on the same tower, due to the existence of multiple fault sources, the pilot zero-sequence directional protection may refuse to operate. Based on the principle of pilot zero-sequence directional protection, taking the single-phase grounding-disconnection complex fault of typical double-circuit lines as the research object, this paper qualitatively puts forward the influencing factors on the misoperation of pilot zero-sequence directional protection. Finally, through RTDS modeling and simulation, the influence of sending & receiving power flow and transition resistance on pilot zero-sequence directional protection when complex faults occur at different fault points is verified.