Analysis Of Traction Network Fault Location Of All Parallel Auto-transformer Feeding Operation Mode

The traction power supply system is one of the major parts of China’s high-speed rail,it is all auto-transformer feeding system at present.The system structure is complicated,and it has various operation mode and fault types.The traction electric network which is long line equipment in the open air is one of the major parts of the traction power supply system,it is easily disturbed by external factors and then goes wrong.So the fault location of auto-transformer feeding system is very important,it’s accuracy directly concerns the efficiency of the fault diagnosis and handling.There are many fault location methods been applied to auto-transformer feeding system,and they are suitable for different operation mode.The fault location methods include the cross-line current ratio,the current ratio of up/down line,suck current ratio and so on,all of them are effective in application at present.The fault location methods also include the feed-absorption current ratio,the transfer impedance method,the traveling wave ranging method and so on,there are many relative theory researches about them.Comparing and analyzing these fault location methods in this paper.At first,in this paper,it introduces the structure of the current mainstream application auto-transformer feeding system in China.On this basis,it introduces the operation mode,the fault types and features,and the difference about the choice of electrical equipment and electrical wiring in high speed railways of different speed classes in China.It also introduces how to draw a current network diagram of auto-transformer feeding system when it goes wrong,and how to make the balance of the current in this fault system.Secondly,it analyses the theory and derives formulas based on the symmetrical components about the fault location methods which include the cross-line current ratio,the current ratio of up/down line and suck current ratio,under the traction substation with inductance coil and without,when the system goes T-R or T-F fault.Thirdly,on the basis of these formulas,it introduces calculation process of the fault location detailedly,and validates accuracy of these formulas by fault location calculation by some short-circuit test data of a traction substation of the Chengdu-Chongqing high-speed rail.It finally proves the necessity that the fault location calculation formula introduce the variable of the inductance coil in the system with inductance coil.At last,it discusses the possibility of application of the current ratio of up/down line in the asymmetric auto-transformer feeding system,whose length of uplink is not equal to its downlink.Finally,it can prove the applicability of the current ratio of up/down line in this asymmetric system through simulation model,and show us that the current ratio of up/down line has a high degree of flexibility and adaptability.