The Optimal Power Flow Of Combined Co-phase Traction Power Supply System

Reactive power,negative sequence and harmonics are three main problems in the traction power supply system of electrified railways of China.The development towards heavy carrying ability and fast speed is also limited by phase splitting problems in traditional different-phase power supply system.The application of co-phase power supply system can well solve the power quality problems,and can replace the existing substation electricity phase splitting.If the power transmission line is applied,the phase splitting of post station can also be canceled.On the basis of the existing co-phase power supply system,a combined co-phase power supply system is developed,which can achieve optimized economic output of the compensating device.Therefore the power flow optimization research of co-phase power supply system is of practical significance.Power flow optimization is practically described as the optimization of the control strategy of active converter equipment,which aims to achieve the optimized power flow of the system.In this paper,the optimal power flow calculation is applied to co-phase power supply system,and the equivalent flow calculation model is obtained.When the traction load is a constant value,the optimal output corresponds with the minimized system loss.Under a series of constraints,the optimized output of traction transformer and compensating devices based on minimized system loss is researched.Firstly,the feasibility of the simulation model is analyzed,and the constraints of power flow optimization are discussed.Then the optimization for a single combined co-phase substation is carried out.Each output of the traction transformer and the compensating device in a coordination is acquired,and the result of single-station co-phase power supply is compared with that of two-station.The power flow problems under the condition of regenerative brake are analyzed,and the results are compared with that under the traction condition.