Over-Voltage Protection Research of Latent Circuit in SCOTT plus AT Traction Power Supply System

The mechanism causing the roof protection gap discharge and traction substation trip is researched for over-voltage produced in anchor section of articulated phase insulator in high-speed railway,with SCOTT + AT traction power supply system as the object of study. According to the transient modeling of the catenary parameters of electrified railway, articulated phase insulator and latent over-voltage circuit of the articulated phase insulator transition timing process for electric locomotive,taking electric locomotive passing the seven-span electrical section at a speed of 200km /h as example, PSCAD is used to simulate and the results show that: the maximum over-voltage of "Locomotive pantograph-electric phase" transition process is largely influenced by the voltage phase difference between pantograph and catenary, and the maximum over-voltage can reach 105kV. Through the method of saturated reactance and heat resistance cascaded in the secondary side of locomotive HV instrument transformer, the impact of maximum over-voltage on locomotive insulation is effectively curbed.