Determination of Relay Protection Settings for DC Traction Networks Under Non-Standard Section Power Supply

The current paper presents a study on the determination of relay protection settings for the DC traction power supply network under real operational conditions. The focus of the study is on sections of the trolleybus contact network powered by the Traction Power Substation Yunak of “Sofia Public Electrical Transport Company” JSC. The research explores specific requirements and challenges associated with non-standard power supply scenarios for the DC traction contact network, analyzing the effectiveness of different relay protection strategies and proposing a comprehensive methodology for setting up protection units. Detailed case studies, including simulations and field tests, demonstrate the effectiveness of the proposed settings in improving the selectivity of relay protection operations and accurately identifying fault conditions in the network. The findings provide practical insights for enhancing the reliability and efficiency of relay protection systems in urban electric transport networks.