Study On Rail Potential And Reducing Measures Of AT-fed Traction Power System

For the load of high-speed and heavy-duty railway is larger, the rail potential will be much higher, person and equipments will be affected by rail voltage, measures must be taken to reduce it, AT-fed traction power system is suitable for high-speed and heavy-duty railway, study on rail potential and reducing measures of AT-fed traction power system is important.Because of the rail has self-impedance and rail-earth leakage conductance, so when the current flow the rail, the rail potential will be produced. In this paper, the rail voltage of AT-fed traction power system can be calculated by the principle of substitution and superposition are summarized first, calculation methods show that the traction current and rail potential calculation of AT-fed traction power system has the property of "decoupling". Integrated grounding as an important measure to reduce rail potential, in this paper, the necessity of integrated grounding has been discussed, the program of integrated grounding which include the basic components of integrated grounding, the scope and principle of integrated grounding, the schematic diagram of integrated grounding, the selection of material and cross-sectional area on integrated grounding wire have been researched.The technical measures to reduce rail potential such as the increasing of rail-earth leakage conductance, the reduction of AT leakage impedance, the addition of transversal connection between the rails, the addition of transversal connection between rail and protection wire, the addition of integrated grounding and so on, in this paper, the technical measures to reduce rail potential have been analysed in theory. The integrated grounding wire (GW) as the grounding body of integrated grounding, has the diversion effect to the rail, the grounding effect can be evaluated by the shunt coefficient, through the influences of radius on GW, interval of transversal connections, buried depth of GW and soil resistivity on shunt coefficient were analyzed, the research result shows that the effect of the radius on GW and the interval of transversal connections is obvious, the effect of the burial depth on GW and the soil resistivity is not obvious.The models of traction include the the chain network model based on multi-conductor transmission lines theory and the equivalent model have been introduced, based on the chain network model and the simplified equivalent model, the simulation models of AT-fed traction power system have been built by Matlab/Simulink in this paper at last, the effect of changing the related parameters to rail potential such as transversal connection, rail-earth leakage conductance, AT leakage reactance and electric conductivity of integrated grounding have been simulated, the sensitivity analysis of rail potential by the related parameters has been analysed, the results show that the effect of transversal connection to decrease rail potential is obvious, the effect of rail-earth leakage conductance, AT leakage impedance and electric conductivity of integrated grounding to decrease rail potential is not obvious.