Power Flow Calculation and Analysis for High-Speed Railway Traction Network under Regenerative Braking

Based on the structure of high-speed railway traction power supply system,which used substation,auto-transformer,switching station,section post and locomotive location as the section of all-parallel AT traction network,the model of traction power supply system was established.Taking the EMU(electric multiple unit)for induction motor and static load in parallel,the power flow calculation method of traction network based on "locomotive-traction network"(locomotive-network in short)coupling was studied.Analysis results of cases under different working conditions show that the proposed method has the advantages of fast convergence and high precision,which can be used to analyze the power supply capacity and power quality at different locations of traction network and different working conditions of EMU.When EMU operated under regenerative braking state,the voltage of the contact wire rises at EMU position,while the voltage of the positive feeder is little affected.The voltage of rail is proportional to the grounding resistance of AT center tap and the operating power of EMU.When the states of traction and regenerative braking are concurrent,the energy generated by regenerative braking supports the EMU under traction state at the same power supply arm preferentially,and the surplus energy returns to public grid or is stored in traction substation.