The Research Of DC Feeder Protection Of Subway

With the rapid development of subway,it is necessary to consummate the protection for DC traction power supply system. But it is very late to develop this kind of protection and there is no manufacturer which has the ability to make it in China,so developing the DC feeder protection of subway is needed. Fristly,according to the non-linear characteristics of twelve-phase rectifier,the thesis gives the calculation model for a short circuit in the subway traction power supply networks which provides the academic foundation for the design of the setting values and the simulation of protection.Secondly,the thesis designs the DC feeder protection and control of subway,and gives the principle of setting accordingly,after it analysizes the characteristics of electric current under tow load and short circuit and considers severel factors. To validate the rationality of the design,the thesis simulates the transient electric current under two work conditions (starting and passing the insulation )ahd short circuit . The results of simulation show that the design is rational.At last,the thesis designs the hardware and software of the protection. Because the feeder short circuit current of subway is very great,the plug-in boards of input and output are different from the AC feeder protection. After analyzing and comparing the two popular input components,the thesis choices the shunt. In addition,the thesis gives the original design of output plug-in board. In the part of software the thesis presents an algorithm to eliminate the influence of the exist of low harmonic wave to the rate-of-rise protection in the short circuit current. By simulation,it is proved that the algorithm can meet the demand and the error is quite small.