Electric Power ›› 2024, Vol. 57 ›› Issue (4): 220-228.DOI: 10.11930/j.issn.1004-9649.202306046

• Power System • Previous Articles    

Refined Diagnosis Method for Disconnected High-Resistance Grounding Faults in Medium-Voltage Distribution Lines

Peng ZHENG1(), Pengcheng HAN2, Guodong WANG1, Ying LOU1   

  1. 1. School of Electrical Engineering & Automation, Luoyang Institute of Science and Technology, Luoyang 471023, China
    2. School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, China
  • Received:2023-06-13 Accepted:2023-09-11 Online:2024-04-23 Published:2024-04-28
  • Supported by:
    This work is supported by Key Research and Development and Promotion Special Project of Henan Province (Stable Operation Control and Reliability Improvement Strategy for Multi-terminal AC/DC Power Systems Based on Source-Network-Load-Storage, No.232102241041).

Abstract:

Multiple voltage drops or abnormal currents may occur in the power system, resulting in significant deformation and fluctuation of fault signal characteristics related to the medium voltage DC distribution network, exceeding the normal fluctuation range, leading to a decrease in the refinement of fault diagnosis. A refined diagnosis method for high resistance grounding faults in medium voltage distribution lines has been proposed. On the basis of constructing a high resistance grounding resistance model, the wavelet energy moment algorithm is used to obtain the characteristics of high resistance grounding faults in medium voltage distribution lines. The extracted fault features are input into the least squares multi-level support vector machine to achieve precise diagnosis of high resistance grounding faults in medium voltage distribution lines. The simulation results indicate that the difference in fault phase voltage waveform obtained by the proposed method is less than 2.3%; The similarity of fault phase current waveform is higher than 98%; The diagnosis time is relatively short, and the highest recognition rate during fault diagnosis can reach 98%, with an average recognition accuracy of 95%; The convergence value reaches 0.97. From this, it can be seen that the proposed method has strong anti-interference performance and can accurately identify high resistance grounding faults when photovoltaic energy is connected to medium voltage distribution lines, ensuring stable operation after photovoltaic energy is connected to medium voltage distribution lines.

Key words: medium voltage distribution line, high resistance ground fault, wavelet energy distance algorithm, feature extraction, least squares multi-level support vector machine