Modeling and Simulation for Traction Power Supply System of High-Speed Railway

Han Zhengqing, Zhang Yuge, Liu Shuping, Gao Shibin School of Electrical Engineering, Southwest Jiaotong University

Chengdu, Sichuan, 610031, China hanzhengqing@swjtu.cn

Abstract—Traction power supply system is an electrical power network used to receive power from three phase power transmission system and supply power for the train driving on the single-phase AC power system electric railway, mainly composed of the traction substation, traction network, partition substation, switch substation and other components. Based on analysis of the compositions of high-speed railway traction power supply system and the autotransformer power supply mode in parallel entirely, this paper establish a simulation model of traction power supply system in the MATLAB / Simulink environment, and a variety of fault conditions in the traction power supply system are simulated, therefore, provided a reference for research on the protection scheme and fault impedance location scheme.

Keywords-high-speed railway, traction power supply system, autotransformer feeding, simulation model

I. INTRODUCTION In recent years, rapid development of high-speed railway

has achieved, and a number of high-speed railway lines have been put into operation. In China's high-speed railway traction power supply system, most of them use autotransformer feeding mode, which has a priority of high voltage, long distance, large power supply capacity and small catenary resistance, is conducive to the operation of electric locomotive at high-speed, heavy duty, high-power operation. Also, the mode has better protective effect to nearby communication lines; it is conducive to the location of substations as large traction substation spacing. According to domestic and international experience, Autotransformer feeding mode is very suitable for large volume and high-speed railway line. Electrical model and simulation modeling of the traction power supply system can improve the level of the design of high-speed railway, and provides a theoretical basis for the protection scheme and fault location of high-speed railway traction power supply system, also of great significance for ensuring the safety of high-speed railway traction power supply, reliable, high quality and economic performance.

II. TRACTION POWER SUPPLY SYSTEM OF HIGH-SPEED RAILWAY

Traction power supply system can apply several feeding modes: track return feeding, boosting transformer feeding, Auto-Transformer (AT) feeding and so on. AT feeding is not

only suitable for high-speed, heavy load operation, but also has good anti-jamming effect. Compared to other feeding systems, AT feeding system provides with higher voltage, lower traction units impedance, lower voltage loss, larger power capacity, smaller power loss and longer feeding section, also reduces the number of substations to reduce the number of split-phase power at the same distance, is benefit to the high-speed operation of locomotive, etc, has obvious technical and economic benefits. Based on the double-track power supply system, Cross-paralleling AT feeding system puts the Traction catenary line (T), Rail (R) and negative Feeder (F) of the up and down the line traction in parallel at the substation and the outlet of the Zoning Department and the AT Department, the traction unit length resistance and voltage loss are reduced, and the supply capacity is further enhanced. Cross-paralleling AT feeding mode is elected in Beijing-Tianjin inter-city in China, Wuhan-Guangzhou line, Zhengzhou-Xi’an line, Beijing-Shanghai line, the scheme is shown in Figure 1.

Figure 1. Schematic diagram of high-speed railway traction power supply

system

Traction power supply system consists of traction substation, autotransformer substation, section post and traction electric network. The main function of traction substation is converting and controlling the electrical energy, completing the convergence between single-phase traction net and three-phase power system and transforming voltage. Traction electric network is responsible for the supply of electricity to the electric locomotive .

A. Traction substation Traction station is very important part of electrified

railway, and the function is turning the 110kV or 220kV power frequency AC high voltage into 27.5kV single-phase power frequency AC which is suitable for electric locomotive

Supported by China National Natural Science Fund (50907055) and Fundamental Research Funds for the Central Universities

978-1-4244-6255-1/11/$26.00 ©2011 IEEE

though traction transformer with certain connection form, and then sending these electricity to the corresponding direction of electrified railway though various feeders to meet the power needs which are come from several directions of electric locomotive. Traction station has two incoming lines and two groups or sets transformers generally. The transformer is using single-phase connection or Vv connection, as shown in Figure 2 and3.

AU

BU

CU

AI BI

Iα Iβ

Uα

Figure 2. Equivalent circuit of single-phase connection transformer

AU

BU

CUAI BI

Iα IβUα

CI

Uβ

Figure 3. Equivalent circuit of Vv connection transformer

B. Autotransformer station When high-speed railway in China is using AT feeding

system, and setting one autotransformer per 10~15 km along the railway. Just the same distance as the railway section, set the autotransformer in each field station along the railway as possible. At the same time, separate from section post and switching post for better operating management.

C. Section post The section post makes up and down feeders of electrified

railway in parallel to increase the voltage level of feeding sections which is at the end of the feeders and balance the current of up and down feeding sections and reduce the loss of electricity energy. Effect is more obvious in the direction of the heavier car and the situation when the road has a large ramp; Adjacent traction substation can supply electricity through section post with the fault of traction substation.

III. THE MODELING OF TRACTION POWER SUPPLY SYSTEM Traction power supply system includes external power

supply, traction transformers, autotransformer transformers, catenary system and so on. This simulation system is a typical simulation of the Chinese high-speed railway traction power supply system, and the conditions are as follows: the power is introduced from the 220kV power system overhead, the main transformer in the traction substation is Vv traction transformer whose design capacity is 20MVA, and along the way there is an Autotransformer Station (ATS), 1 Section Post (SP) each of which has 2 sets of autotransformer. Catenary uses up and down inphase single-side cross-paralleling power supply system , and there is a section post (SP) at the feeding

section end to make sure the up and down catenarys work in parallel to supply power under normal circumstances and use over-zone feeding in case of accident. The figure 4 shows the simulation model of the high-speed railway traction power supply system .

Figure 4. Simulation model of the high-speed railway traction power supply system

Chinese high-speed railway traction substations mainly use the Vv traction transformer. The model is shown in Figure 5.

Figure 5. Simulation model of the main transformer in the traction

substation

From the needs of the simulation, the section post can be seen as constituted by two autotransformer substation. The simulation model is shown in Figure 6.

Figure 6. Simulation model of autotransformer and section post

Traction model needs to simulate the catenary, the negative feeder, the impedance of the rail itself and the mutual impedance. The model is shown in Figure 7.

Figure 7. Line package model

IV. SIMULATION OF TRACTION POWER SUPPLY SYSTEM The simulation of traction power supply system can be

used for fault analysis and fault location analysis, the design mainly concerns on the short-circuit fault simulation of different positions of the traction network (in this paper it occurs at 0.04s, and lasts to 0.2s), and obtains the fault voltage and current waveform of catenary at traction substation.

A. The voltage and current waveforms in normal operation

Figure 8. Normal operation

B. Short-circuit fault

1) In the first feeding section (0.2km to the traction substation)

a) The voltage and current waveforms in catenary-rail short-circuit fault

Figure 9. Catenary-rail short-circuit fault in 1st feeding section

b) The voltage and current waveforms in negative feeder-rail short-circuit fault

Figure 10. Negative feeder-rail short-circuit fault in 1st feeding section

c) The voltage and current waveforms in catenary-negative feeder short-circuit fault

Figure 11. Catenary-negative feeder short-circuit fault in 1st feeding section

2） In the second feeding section (4.91km to ATS) a) The voltage and current waveforms in catenary-rail

short-circuit fault

Figure 12. Catenary-rail short-circuit fault in 2nd feeding section

b) The voltage and current waveforms in negative feeder-rail short-circuit fault

Figure 13. Negative feeder-rail short-circuit fault in 2nd feeding section

c) The voltage and current waveforms in catenary-negative feeder short-circuit fault

Figure 14. Catenary-negative feeder short-circuit fault in 2nd feeding section

According to the simulation results, the fault in down line is similar to up line. Therefore, only the fault simulation results in one direction line are given in this article.

3） Line broken fault a) The voltage and current waveforms in catenary line

broken fault

Figure 15. Catenary broken fault

b) The voltage and current waveforms in negative feeder broken fault

Figure 16. Negative feeder broken fault

We can see from the simulated waveforms above, when short-circuit fault occurs, the voltage on catenary becomes lower, but current becomes higher. When it occurs in the first feeding section, the voltage drops more and the current increases more; It is opposite to the second feeding section. As the first feeding section is close to the traction substation, so short-circuit fault has greater impact on the voltage and current of feeding system. However, when line broken fault occurs, the voltage value by the side of traction becomes higher, but current value becomes lower. Meanwhile, it makes little effect on the voltage between catenary and rail, also on the current of catenary.

V. CONCLUSION Traction power supply system has great significance to the

safe and reliable operation of High-speed railway. The paper analyzes the composition of China's high-speed railway traction power supply system and introduces a simulation model of traction power supply system built in MATLAB2008. Meanwhile, the simulation results in normal operation, various kinds of short-circuit fault and line broken fault are given in this paper. The model described in this paper can be used to analyze and validate protection schemes and fault location algorithm for the traction power supply system of China high-speed railway.

ACKNOWLEDGMENT

The authors express sincere gratitude to the support of China National Natural Science Fund (50907055) and Fundamental Research Funds for the Central Universities.

REFERENCES [1]. Qunzhan Li, Jianmin. “Analysis of traction power supply system”.

Southwest Jiaotong University press, 2007 [2]. Jinhao Wang, Lei Xue, Mengzan Li, Shuzhong Wang. “Traction

transformer connection of different application methods”. the first phase of Modern Power-February , 2009

[3]. Ziliang Li, Wei Chen, Ping Dang. “The principle analysis of electrified railway power supply autotransformer”. electrified railway, 1998, (03): 12-18

[4]. Wang Jing, Guoqing Weng, Youbing Zhang. “The simulition and application of power system using MATLAB/SIMULINK”. School of Electronic Science and Technology of Xi'an University press, 2008