| Existing single-phase industrial frequency AC traction power supply system causes load imbalance, reactive power and harmonic current pollution in three-phase power system. In addition, electric phase breaks of traction network restrict the development of high-speed railways and heavy-haul railways. Although some measures have been taken, the effect is limited. With the rapid development of power electronics technology and widespread application of the new power electronic devices, as a key equipment of co-phase traction power supply system, balance-converting device come into being, and problems caused by the existing railway power supply system can be solved.For the widely-adopted of YN, dll transformer in China electrified railway traction substation, the co-phase traction power supply system based on YN,d11wiring transformer is designed in this paper. Due to the development of high-speed railways and heavy-haul railways, co-phase traction power supply system requires large capacity balance-converting device.The paper comparing several high-voltage power circuit implementations,based on two-level four-multiple voltage source converter and three-level voltage source converter, main circuits of balance-converting device are designed. Comparative analysis of the two comprehensive compensation current generative methods, control strategies are studied. Propose control strategy to control DC capacitor midpoint voltage.According to measured data of a traction substation as electrical parameters MATLAB/Simulink is used to build two compensation scheme models and make simulation. The simulation results show the advantages of multiple structure and multi-level structure. The simulation results shows that the co-phase power supply structure, the detecting method of comprehensive compensating current and the controlling ploy of large capacity balance-converting device given in this paper can be realized. |
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