Modeling of Rail Transit Earth Current Distribution at Neutral Point of AC Grounding Transformer

The intrusion of earth current into the neutral point of grounding transformers can pose threats to grid system. This issue is particularly prevalent in urban rail transit systems. A major challenge in modeling earth current distribution stems from the complex coupling of traction power supply system from the urban rail transit system and ac transmission systems, further complicated by varying leakage currents from diverse tracks. This paper introduces a lumped parameter model designed to address these challenges. The model transforms the coupling between the traction power supply system and the ac system into a point coupling, aiding the creation of a earth current distribution calculation model. Both mathematical and simulation models are provided. This model is anticipated to serve as a practical foundation for the effective mitigation and management of earth current concerns in ac power system.