Effect of Single-Point Ground Faults on Relays in Substation Secondary DC Systems

This paper addresses the existing research on single-point grounding faults in secondary DC systems, which used to predominantly focus on the steady-state analysis of direct grounding faults and typically considers only one type of grounding fault. Based on the wiring diagram of the secondary DC systems, we constructed the equivalence model of grounding of the secondary DC systems, which taked into account the insulation monitoring parameter. This study utilizes the principles of circuit superposition, Laplace transform theory, and simulation analysis to investigate the impact of relay interference in a secondary DC systems under two scenarios: direct grounding and high impedance grounding of the power supply's positive and negative poles. And this paper studied of the secondary DC systems in different grounding faults, the impact of each parameter of the circuit on the relay, and derive the main influencing factors of the voltage on both ends of the relay and its changing law, and put forward a targeted anti-interference model to prevent the interference. And targeted proposed anti-interference measures for the secondary DC systems grounding fault judgment and detection provided a new idea and method, the reliability of fault judgment and subsequent monitoring technology to enhance the useful exploration.