Study of the simulation of DC traction power supply system based on AC/DC unified Newton-Raphson method

The modern urban railway traction power supply system is a hybrid AC/DC system. The equivalent 24-pulse rectification is obtained by parallel connection of two 12-pulse uncontrolled rectifiers with 15deg phase shifted. Take 12-pulse uncontrolled rectifier as investigated subject, the operation modes as load current increasing is analyzed in this paper. Rectifier is depicted as a nonlinear electrical element in power flow. A improved unified Newton-Raphson method of urban railway AC/DC system based on rectifier models is proposed to speed up the urban rail traction power flow. The dynamic power and voltage variation of both AC/DC sides along with train running can be achieved. An example problem is provided for comparison. This method is successfully applied in the simulation of practical DC traction power supply system.