Analysis of sequence voltage for single-phase ungrounded broken-line faults in distribution network
CHEN Chenggong1, CHEN Yulong2, LI Can3, TANG Tao2, ZHAO Wei3
1. Zhuzhou Power Supply Company of State Grid Hunan Electric Power Company Limited, Zhuzhou, Hunan 412000; 2. School of Electrical & Information Engineering, Changsha University of Science & Technology, Changsha 410004; 3. Zhuzhou Electric Power Survey, Design and Research Co., Ltd, Zhuzhou, Hunan 412000
Abstract:The ungrounded broken-line fault of distribution network has the characteristics of high hazard degree and difficult identification, so it is necessary to study its fault voltage characteristics. Composite sequence network models are developed for ungrounded broken-line faults under three neutral configurations (low-resistance, ungrounded, and Petersen coil) based on boundary conditions and equivalent circuits. Analytical expressions for sequence voltages are derived at multiple measurement points: 10 kV busbars, fault line terminals, and 380 V post-fault sections. The research examines the correlation between busbar zero-sequence voltage and post-fault line capacitance, analyzes the relationship between negative-sequence voltage and system-to-load impedance ratio. Matlab simulation validates the theoretical analysis with excellent consistency. The findings provide crucial theoretical foundations for distribution network broken-line fault diagnosis.