Research On Setting Calculation Of Feeder Protection Of Traction Power Supply System

In this thesis, the structure form and operation mode of railway traction network are diversed, and have their own particularity and complexity. Compared with power system, the operation mode and the specific structure of traction network should be considered when designing the feeder protection of railway traction power. In this thesis, the feeder protection of traction power supply system in direct power supply mode and AT power supply mode have been studied.Impedance protection, as the core of feeder protection, is mainly studied along with analyzing and deducing the measuring impedance of different structures with variety faults in different sections. By mainly using impedance-oriented protection and several design principles like backup protection, the thesis desperately focus on the direct power supply mode and the AT power supply mode then finishes the whole protection scheme as result. The new direct power supply protection scheme need not to switch the fixed value interval. Due to the maximum of unit measured impedance value is important to the protection, in this thesis, the equivalent circuit method was adopted to study the influence of self coupling transformer leakage, providing more precise setting basis for AT power supply mode.The conclusions above are realized by software programming, which can realized the automatic calculation of the short-circuit impedance, the automatic setting of the distance protection The direct and AT power supply mode simulation models were built in Simulink to verify the theoretical calculation of impedance measurement.It can be seen that the formula derivation and simulation results are basically the same, which verified the accuracy and theoretical reference value of the method of equivalent circuit. In addition, by compared with the leakage impedance of the auto transformer neglected, the calculated curve with the leakage impedance factor is much closer to the simulation results. Therefore, self-coupling transformer leakage impedance effect shall be taken into consideration the whole set calculation to make setting results more accurate and reliable, reducing the protection misoperation and refuse operation probability.Considering leakage reactance, the curve is more close to the simulation curve. Ignoring the leakage impedance will lead to the largest measurement impedance value is smaller than reality, which is detrimental to the reliability of relay protection design.Finally, the overall design of relay protection software for the device of traction power supply system has been carried out in this thesis. The device mathematical model has been established, and the feeder protection setting calculation and generation management and other integrated functions have been achieved initially, improving the efficiency and automation level of the traction power supply system.