Study Of Scheme About New Damping Auto-Passing Neutral Section

Single-phase,50Hz AC power system is applied in Chinese electrified railway. Different phase in rotation is used to balance the three-phase load of power system. In order to prevent short circuit between diffrent phases and make sure the locomotive pass by smoothly, phase-separations are set every20to30kilometer. If we take manual mode of passing over of neutral section, the driver’s operation and the reliability of the road signal instructions determine whether the locomotive can pass the phase-separations or not. Once negligence, it will cause charged cross the phase-separation, and influence of the traction power supply system safety operation. So the auto-passing device is necessary in the electrified railway. The on-board neutral-section auto-passing device and the ground auto-passing device are widely used at present. In the actual application, there are some changes of the system paramater when the locomotive passes the phase insulator. It can cause over-voltage and flow, and it seriously affects the electric railway’s safe operation. So the study of scheme about auto-passing neutral device has the theoretical and actual value.The paper presents a new scheme about damping auto-passing neutral section, which adds a Y-type resistors bank on the phase-separations. It uses the damping effect of the Y-type resistors bank to reduce the transient over-voltage which appears when the locomotive passes the phase insulator. First, the paper introduces the work principle and the control strategy and the feature. Secondly, the steady state loss will decrease and the damping effect of the Y-type resistors bank will weak when the resistance of the Y-type resistors bank increase. For the purpose of reducing the steady state loss and ensuring the damping function, the paper analysis the way of how to choose the resistance of the Y-type resistors bank reasonably. Thirdly, the paper proves the scheme is effective in reducing the over-voltage and flow by electrical calculation about the process of locomotive passing the phase insulator. Finally, the Matlab/Simulink software is used to establish the locomotive model and the model of the locomotive passing the phase insulator. Then the models of the locomotive separating from the left feeding section, contacting to the right feeding section, and the whole process of the locomotive passing the phase insulator are simulinked. The simulation waveforms are analyzed and sumarized, which validate the effectiveness of the new scheme about damping auto-passing neutral section to reduce the over-voltage and flow. Based on the principle, which the resistors are used to reduce the over-voltage of the new scheme about damping auto-passing neutral section, the paper introduces another scheme to reduce the over-voltage. It adds a bank of resistors to ground on the neutral section of the on-board neutral-section auto-passing device. Simulations are taken to validate the effectiveness of over-voltage reducing.