采用特征频率电流相位相似度的配电网 接地故障选线方法

In response to the challenges of -weak characteristics and the influence of grounding transition resistance on line selection for single-phase grounding faults in low-current grounding systems, a line selection method for grounding faults in distribution net-works based on the phase similarity of characteristic frequency current is proposed. Firstly, using signal injection method, the distribution of zero-sequence current and characteristic current signal distribution after a single-phase grounding fault occurs in a low-current grounding system is analyzed to obtain the fault characteristic current distribution pattern. Secondly, the impact of different characteristic frequencies, line lengths, and line topologies on the propagation characteristics of the injected current signals is analyzed, with 220 Hz selected as the characteristic frequency for the injected current. Using the PSCAD/EMTDC platform, a distribution network simulation model is built. After a fault occurs, characteristic frequency current is injected, and the amplitude and phase characteristics of the characteristic frequency signals for each line are analyzed. By utilizing the phase of the characteristic frequency current, a line selection method based on the phase similarity of characteristic frequency currents is proposed, and criteria for single-phase grounding fault line selection are established. Simulation examples are conducted for different grounding transition resistance conditions of single-phase grounding faults, and line selection is performed using the proposed method. Results show that under high-resistance grounding conditions, the proposed method can accurately identify the faulty line with high sensitivity and accuracy. Compared to traditional line selection methods, the proposed method has lower complexity and can handle grounding transition resistance up to 10 kil. This method provides a new perspective for the theoretical research on line selection for single-phase grounding faults in low-current grounding systems.