Research On Rail Potential And Stray Current Comprehensive Suppression For Urban Rail Transit

At present, with the rapid development of urban construction and the rapid growth of urban population, the pressure of traffic in the city is increasing. The urban rail transit system, with its comfortable, fast and large passenger capacity, becomes one of the best means to resolve the contradiction between supply and demand in the city passenger. With the increase of urban rail transit coverage, stray current and rail potential problems caused by its traction power supply system cannot be ignored.In this paper, the continuous and discrete models of return system are deduced based on urban rail transit traction return system. Field test data is used to establish the simulation system. The distribution and influence factors of stray current and rail potential are simulated and analyzed. In the operations of urban rail transit line, stray current is collected by drainage device, and rail potential is controlled by rail potential limiting device, however, the control of two devices is not associated with each other. In the simulation results, stray current increases while rail potential is reduced by rail potential limiting device, and rail potential increases while stray current is collected by drainage device, sometimes, it even causes the closing of rail potential limiting device. So, three methods are proposed in order to limit rail potential and stray current integrated in this paper:(1) Optimal control measure of rail potential limiting device: the rail potential limiting device whose rail potential is maximum acts, to reduce the probability of multiple rail potential limiting devices acting at the same time;(2) Optimal control measure of drain cabinet: drainage cabinets are turned off transitorily, when rail potential limiting device acts, to prevent them shorting by the earth;(3) Hierarchical rail potential limiting device: some small resistances are used to reduce rail potential, while limiting leakage of stray current. The simulation results show that the previous two optimization measures exist some drawbacks, and hierarchical rail potential limiting device can effectively achieve the goal of rail potential and stray current comprehensive suppression.