The Relay Protection Research Of Multi-car's DC Traction Supply System

Railway traffic is the key developmental direction of the city traffic system in the future. The security is the most important thing of the whole public traffic system. Hence, the relay protection study of multi-car's DC traction supply system is significant.Firstly, the development of the city railway traffic and the composing of the underground DC traction supply system were introduced briefly, respectively. The DC protection problems of the underground traction supply system were discussed and the solution was presented. The principle of the relay protection of multi-car's DC traction supply system and the several DC feeder protection methods were presented.Secondly, the short circuit fault of the multi-car's traction supply system was simulated and analyzed. The multi-car's DC feeder protection (tripping protection of the big electric current, protection of di/dt+ΔI) were collected by analyzing the voltaic changing characteristic at the situation of the engine start and the line went wrong. The setting principle was gained. The correctness and the rationality of the setting value were validated.Thirdly, the lack of the traditional protective method on special condition was analyzed. The railway DC self- adaption electrical current protection based on the electrical current integral and average value or changing characteristic was developed. The protection operant was tested for the first method. The validity was proved by the simulation result.At last, the examining electric circuit and the control software of the multi-cars traction supply system were designed, respectively.