Study On The Evolvement Of Pantograph-Catenary Arcing In High-speed Railway And Its Numerical Modeling

With the development of economy and technology of our nation, it gives more and more requirements to the safety and reliability and stability to the high-speed railway. With the train's running faster and faster, the relationship between catenary wire and pantograph strip becomes one of the three important relationships of high-speed railway, and it becomes the most serious problem of its development. During the running of train, the off-line phenomena of pantograph-catenary system happen more and more frequently due to three reasons. One is the vibration of pantograph, and the other one is the not smooth situation of catenary wire and rail. After all, the electrical characteristic of catenary wire cannot match the pantograph strip very well. During the off-line phenomena, arc occurs more and more frequently. One one hand, the arc is very important to keep the current continuity of train.One the other hand, the over-voltage due to arc damages the traction power system and the electrical equipment inside the train. Meanwhile, the arc will ablate the contact material of pantograph-catenary system, reduce the running performance of pantograph-catenary system,and lead to many accidents finally. So, it is very important to study the arcing characteristics.The previous researches are mainly about studying the electrical parameters of arc. The researches about arc's physical properties and the electrical wear mechanism of pantograph-catenary system are seldom.In this thesis, a novel model of pantograph-catenary arcing in air dielectric concerned with multiple physical fields in high speed train is established. The key impact factors of arc are studied. The changing characteristics of pantograph-catenary arc with time are simulated out.The mainly work of this thesis is as follows:(1) Based on the interaction mechanism between all physical fields during the arcing process, the physical fields are figured out. And then, a novel model of pantograph-catenary arc is established. By using a calculation software Fluent, a simplify geometry model of pantograph catenary system is built. The Navier-Stokes equations of arc plasma are made out.The software is second developed by using C program. The program is setting the physical parameters and source item of equations. The proper boundary conditions are set. After all,the arcing characteristics could be calculated out.(2) By adjusting the arc current value which input to the model and the gap distance between catenary wire and pantograph strip and the catenary wire radius, the temperature distributions of arc plasma and the pantograph strip and catenary wire are calculated out. The electrical ablation of pantograph-catenary system is figured out. And the way to reduce the electrical ablation of catenary wire is studied. Based on the pantograph-catenary testing platform, the arcing images are recorded by a high-speed camera. By dealing with the images during the arc evolvement period, the arcing situation is studied. And then, the pantograph-catenary arc model is validated.(3) By setting the arc current of model to be a sinusoidal current, the evolvement characteristics of pantograph-catenary arc with time and the dynamic evolvement process during the pantograph lowering process are studied. By adjusting the velocity of inlet boundary,the temperature distributions of arc plasma with different train speed are calculated out. It is found that with the train speed becoming faster and faster, the displacement of arc root becomes lager. And the arc radius reduing gradually, which make the arc to be extinguished easily.