Study On The Modeling Of DC Traction Substation In AC-DC Power Flow Calculation

With the increasing of urban traffic congestion and environmental pollution, urban rail transit become the inevitable trend of development of urban transport because of its large volume, high speed, zero pollution, etc. Study on modeling of urban rail transit power supply system can not only provide theoretical support for choosing equipment capacity, inspecting substation location, but also offer simulation for line operation, expansion simulation.Based on the in-depth analysis of working principle of diode rectifier traction substation, this thesis establishes6-pulse,12-pulse,24-pulse diode rectifier traction substation mode respectively. On this base, the operational principles of traction substation with ground resistor braking device, traction substation with super capacitor energy storage devices, and PWM rectifier feedback traction substation are analyzed. Those types of DC traction substation model are built in different working conditions. Substation models laid the theoretical foundation for AC-DC power flow calculation of urban transit power supply system.For power supply system of urban rail transit, first, external power grid model, main substation model and medium voltage network cable model in AC power supply system are established. Next, traction network model and metro vehicle model in DC power supply system are set up. Making use of AC-DC power supply system mode, the application method of various types of traction substation in AC-DC power flow calculation is analyzed. Then a living example is given to illustrate iteration AC-DC power flow calculation step. Finally, according to the field test data in Shanghai metro viaduct line3, underground railway line4, the correctness of the24-pulse diode rectifier traction substation model is verified.Based on AC-DC power flow calculation method, using C#language, software of urban rail transit power supply system is founded. Using field test data in Pudong Avenue and Linping road traction substation of Shanghai metro line4, the availability of the DC traction substation model in AC-DC power flow calculation is verified.