Coordinated optimization of over-voltage protection devices based on chain reaction mechanism in urban rail transit

• Mechanism of over-voltage protection device chain reaction is revealed. • Fast rail potential prediction method after device action is proposed. • Global coordinated control strategy is proposed to ensure metro electrical safety. • Method reduces protection actions by 52.78% and potential by 28.72%. • Coordinated strategy ensures real-time performance and high robustness. Excessive rail potential in urban rail traction power supply system poses severe safety risks to equipment and personnel. Currently, over-voltage protection devices are controlled independently based on local rail potential. In practice, this uncoordinated operation often triggers unnecessary device actions, leading to a cascading chain reaction that exacerbates stray current leakage and threatens system reliability. However, the theoretical mechanism driving this chain reaction remains unclear, and effective coordinated control strategies are lacking. To address this, this paper proposes a novel coordinated control strategy based on the chain reaction mechanism. First, a sensitivity matrix is analytically derived to explicitly quantify the precise impact of a single protection device’s action on the rail potential distribution across the entire line. This rigorous mathematical model elucidates the root cause of the protection device chain reaction phenomena. Subsequently, a fast rail potential prediction algorithm based on the sensitivity model is developed, which is then integrated into a global optimization algorithm designed to minimize unnecessary actions while maintaining safety. The model’s accuracy is validated using field measured data from an operating metro line. Simulation results demonstrate that the optimization method reduces protection device action counts by 52.78% and the average maximum rail potential by 28.72%. Furthermore, experimental statistics on an industrial controller confirm an average execution time of 0.374 ms, strictly satisfying real-time engineering requirements. This research provides both theoretical insights into the chain reaction mechanism and a practical, high-efficiency solution for enhancing the electrical safety of urban rail transit.