Transmission line single-phase grounding fault calculation model and empirical research based on actual cases

Abstract

With the expansion of power systems and the integration of renewable energy sources, the probability of single-phase grounding faults in 220 kV high-voltage transmission lines has significantly increased. Accurately calculating fault currents is crucial for relay protection setting, circuit breaker selection, and the safe and stable operation of power grids. This paper establishes a single-phase grounding fault current calculation model based on the symmetrical component method, tailored to the actual operation of the 220 kV power grid in the DD region. First, it analyzes the characteristics of zero-sequence currents generated by single-phase grounding faults under the directly grounded neutral point mode in 220 kV systems. Second, it constructs a composite sequence network diagram incorporating power source voltage, system equivalent reactance, and fault point impedance, calculating theoretical data. By comparing actual recorded data with theoretical calculations, the results show that the theoretical calculation error is controlled within 3%, verifying the model’s effectiveness.