Study On The Arc Model Of Contact-loss In Subway Pantograph-OCS System

The Subway vehicle get energy used to carry through running equipment in the vehicle and vehicle operating by the sliding electrical contact between skate which is fixed on the phenomenon and the line of contact when subway vehicle running. The stability of current collection between the pantograph and catenary has an important effect to vehicle’s normal operation, it decides if the vehicle can running safe and stable.During subway vehicle running, pantograph will be divorced from contact line for such reason as hitting hard point, passing neutral section, height changing of contact line. If voltage breakdown the gap caused by the separation of pantograph and contact line, the arc will appear. The arc caused by contact- loss of pantograph would reduce the quality of current collection of subway vehicle and also produce the harmonic. The high order harmonic caused by arc would generate a phenomenon what is called overvoltage. The overvoltage phenomenon will do damage to the whole tractive power supply system. And the macro-energy and high temperature heat quantity released by the arc would do damage to the vehicle and the skate which is fixed on the phenomenon and the line of contact, these will reduce the life length of equipment. Nowadays, the research about contact- loss arc is always focusing on developing the contact-loss checking technology and the overvoltage or electromagnetic interference. The research about contact-loss arc itself is very seldom.First research the arc theory, analyzing the characteristic and the structure of arc, studying on the theory of AC arc extinguishing and near cathode effect. Then research the damage to contact terminals caused by arc, the moving characteristics of arc, energy balance in the poles of arc by analysis the theory of arc and electric contact. Analyze the actual process of subway vehicle running to research the produce mechanism and the characteristic of contact- loss arc. Analyses existing arc model and the energy changing of contact- loss arc, then establish the contact-loss arc model based on the theory of conservation of energy. Because it is hard to collect real- time data on the subway vehicle during the vehicle running, use the entity graph of the pantograph comprehensive testing-bed integral construction to simulate the running of subway vehicle, and analyze the data and the phenomenon observed and collected during the experiment. The analysis says that contact- loss will create arc, the faster the vehicle running the more contact- loss will occur. Finally, build the simulation on the MATLAB. Establish a simplified circuit of arc model in phenomenon and catenary system based on the test bench and proving the correctness of the arc model acquired.