一 种 适 用 于 混 合 三 端 直 流 系 统 的 纵 联 保 护 方 案

To improve the transmission reliability of multi-terminal systems，this paper proposes a hybrid three-terminal DC trans-mission line pilot protection method based on the Mann-Kendall test method. The method uses the T-connected bus three terminal current fault component to determine the fault area，then uses the Mann-Kendall test method to analyze the changing trend of the current at both ends of the line in the fault area，and realizes the fault type identification and the fault pole selection. Finally，the model is built in PSCAD/EMTDC and different fault conditions are simulated，and the proposed protection method is verified with MATLAB. Simulation results show that the proposed method can operate reliably within 2.5 ms under various fault conditions，with good quick-action，and has strong resistance to noise interference and transition resistance.