基于暂态电流故障分量的直流配电网单极故障选线方法

The medium voltage flexible DC distribution network based on two-level converter (VSC) is suitable for the access of distributed energy such as wind energy and solar energy. However, when the unipolar grounding fault occurs, the fault current will rise rapidly, and the protection device must quickly identify the fault line. To solve this problem, this paper analyzes the transient characteristics of single-pole grounding fault in VSC terminal, and theoretically analyzes and calculates the variation characteristics of transient fault current. The fault line selection is carried out according to the difference of transient fault current information of each line. The proposed method can quickly and reliably identify the fault within 3 ms. Finally, the model of radial medium voltage flexible DC distribution network is built in PSCAD/EMTDC, and the protection line selection algorithm is verified by Matlab. The simulation results show that the proposed line selection method can accurately identify the single-pole grounding fault line of flexible DC distribution network.