A pilot protection method for the transmission line of wind farm-flexible DC system based on high-frequency inductance difference coefficients

Conventional protection schemes for wind farm-flexible flexible direct current (DC) system transmission lines are susceptible to malfunctions in external fault scenarios and exhibit limited immunity to fault resistance in internal fault scenarios. In the pursuit of enhancing pilot protection performance, a novel protection method based on high-frequency inductance difference coefficients is proposed. Firstly, the fault transient characteristics of both the wind farm and the flexible DC converter are analyzed, deriving their respective transient models. Subsequently, a high-frequency fault component network comprising inductive impedances is constructed. Then, a protection criterion based on high-frequency inductance difference coefficients is formulated. Finally, the proposed method is subjected to simulation tests on the RT-LAB platform. The results validate its capability to accurately identify the locations of internal and external faults, demonstrating robust immunity to fault resistance. Because it operates independently of synchronous information interaction, it functions rapidly.