Research On Traction Power Supply Technology In Special Section

The average elevation in the west of China is higher,and a part of line sections are located in the harsh environment of the high cold and high altitude,for example,the Ganqing section line is located in the hinterland of the mountainous area,with the continuous long steep grade and dense tunnel groups,resulting in the different left and right power supply distance of traction substation and the uneven traction load of the power supply arm,which makes it difficult to design the traction power supply scheme;however,as the electrical weak link of traction power supply system,the over-voltage phenomenon occurs from time to time when the electric multiple units(EMU)passes through the electrical phase separation,due to the limitation of geographical location,the electrical phase separation in some mountainous areas cannot be set up in the tunnel,the over-voltage problem of electrical phase separation in the tunnels is seldom studied.In this paper,the method of the theoretical analysis and simulation is used to study the design of traction power supply scheme and the over-voltage of the electric multiple units(EMU)passing through the articulated electrical phase separation in the tunnel.Firstly,the current commonly used traction network power supply mode has been compared,and the advantages and disadvantages of each power supply mode have been compared based on the structure characteristics,power supply capacity and engineering cost;the four different traction transformer of the single-phase connection,Y/Δ wiring,Scott wiring and V/x wiring have been compared,by combining with the characteristics of each transformer,a new type of traction transformer is put forward,the AT power supply mode and TRNF power supply mode can be combined and used,and the transformer is analyzed from the steady state operating characteristics,capacity utilization,negative sequence features and power supply capacity,and by taking the Shuang Peng Xi traction substation as the research object,three kinds of power supply schemes have been put forward.Secondly,from a theoretical point of view,the process of the EMU passing through the articulated electrical phase separation is analyzed and calculated,the mathematical formula of the voltage to ground in the neutral line of electrical phase separation has been deduced,and the influencing factors of neutral line voltage have been analyzed;and then,the calculation methods for the electrical parameters of the traction wire outside the tunnel and inside the tunnel have been compared,the potential coefficient function of conductor in the tunnel has been derived,and the specific calculation formula of the neutral line distribution capacitance of electrical phase separation in the tunnel has been given.Then,the function and usage of electromagnetic transient simulation software PSCAD have been introduced simply,the simulation model of Shuang Peng Xi traction power supply system has been set up in PSCAD,the three kinds of power supply scheme is simulated and compared from the power supply capacity and negative sequence influence,the simulation results have shown that under the same simulation conditions,the power supply ability of new type traction transformer is stronger than that of Scott traction transformer,the negative sequence influence produced is basically the same as the negative sequence influence of V/x traction transformer.Finally,the over-voltage sizes generated when the EMU passes through the articulated electrical phase separation inside the tunnel and outside the tunnel have been compared,the maximum over-voltage amplitude value of the EMU passing through the electrical phase separation outside the tunnel is 86.88 kv,and the maximum over-voltage amplitude value of the electrical phase separation inside the tunnel is 115.53 kv,which is 32.98% higher than that outside the tunnel and 3.27 times the rated voltage amplitude value of traction network.With respect to the overvoltage problems of electrical phase separation in the tunnel,the restraining scheme for the replacement of electrical phase separation metal neutral line to the non-metallic line has been proposed,the simulation results have shown that the maximum overvoltage amplitude value of the non-metallic neutral line is 50.2 k V,which is reduced by about 56.55% than the metal line overvoltage,which is only the 1.42 times the rated voltage amplitude value of traction network,the operating overvoltage caused by the EMU passing through the phase separation can be effectively reduced.