Computer Simulation of Feeder Protection Systems in Overhead Contact Network for Urban Electric Transport

Purpose: To evaluate the efficiency of the available protection measures against overload currents and short circuits, and to identify the specific behaviour of these protections in various emergency situations, including energy recovery processes in urban electric transportation systems using the practices of «Gorelektrotrans» State Unitary Enterprise (SUE) in St. Petersburg. Methods: A theoretical analysis of regulatory documents and instructions has been undertaken, along with numerical experiments using MATLAB Simulink software. The aim of the experiments was to simulate typical failure cases and emergency states of the overhead contact network, such as different types of short-circuits and energy recovery during rolling stock movement. Results: The results provide quantitative estimates of the current and voltage values in the contact network under different failure scenarios. They reveal that the existing protective measures are insufficiently sensitive to low-power short- circuit events and reverse polarity current phenomena during energy recuperation. It has been established that traditional protective devices are ineffective in the event of small-scale fault currents and the unique features associated with energy transfer through low-resistance contacts. Practical significance: The practical significance of the research is to emphasise the need to reconsider the design and implementation of protective systems for contact networks. The aim is to enhance the sensitivity of these systems to critical failures, such as minor short- circuit currents, and to conditions arising from reversed energy flow (recuperation). A series of recommendations have been proposed to improve organisational and technical measures and to implement automated monitoring systems for the condition of the contact network and its associated equipment. These measures will minimise the risk of accidents and ensure the reliable operation of urban electric transport systems.