| The power distance of the supply arm can be extended furthest by the long distance power supply technical scheme for the electrified railway,which the number of the neutral section at the section post can be reduced,and the potential security risks caused by the neutral section can be avoided.At the same time,the number of the external power supply interfaces can be also reduced,which the higher external power investment costs can be saved.As a result,it does better to promote the development of high speed and heavy load of electrified railway in China,and it is particularly important for the development of the electrified railway in the weak grid areas of the western region and the plateau and the development of municipal railways.Therefore,it is of great significance to carry out a detailed theoretical study on the long distance power supply technology,which can provide some useful theoretical support for the application and popularization of the project.First of all,the technical scheme of long distance power supply technology is introduced.According to the perspective of lumped parameter analyses,the mathematical expression of the traction current distribution,equivalent impedance of traction network,voltage drop and loss for the cable+AT power supply mode is emphatically analyzed,and the equivalent circuit of the cable+AT power supply mode is derived,which the AT leakage reactance is consided.In this paper,considering the distribution capacitance of the cable core,a method to calculate the voltage drop,the voltage loss and short circuit current is proposed,and a certain theoretical study is also studied for the single-core cable+direct supply.As a result,the mathematical model of traction network for long distance power supply technology is establishedSecondly,according to the theoretical analysis,the corresponding simulation is built by the means of Simulink.And the theoretical calculation and simulation analysis of voltage drop and current distribution are carried out,which the correctness and effectiveness of the theoretical analysis results is proved.Then,the cable capacitance effect,the shunt coefficient of traction cable,the equivalent impedance of traction network,the voltage drop and the voltage loss and so on of the electrical characteristics for the long distance power supply technology of the electric railway are studied in detail,and the electrical chracteristics of several kinds of methods are also compared,and the calculation graphic method and analytic method is given to get the longest distance power supply.The results shows the superiority of the long power distance.Finally,the design of the traction power supply system is briefly summarized,and the different application schemes for the long distance power supply technology are given,based on the existing line and the new line.With the parameters of Beijing-Shanghai line,the different optimization programs of the cable+AT mode is given from the perspective of existing programs and new programs.Under the condition of the maximum load,the different schemes are compared and analyzed,which the results show show the superiority of the prospect of long distance power supply technology and the wide application. |
