牵引供电系统建模与短路电流的仿真

Modeling of Traction Power Supply System and Simulation of Short-circuit Current

由于牵引供电系统中感性和容性元件的存在,在发生瞬间、永久短路故障以及机车充电过程中,都会有不对称暂态电流冲击,这对基于电流变化量原理的保护判据将产生很大的影响,甚至导致保护的误动作。笔者基于EMTP对供电系统进行建模,分析了变压器对短路电流中暂态电流冲击的影响,考虑到实际电压器短路瞬间漏抗增大,对EMTP中的实际变压器做了一定的改进,最后得到的仿真波形与实际短路电流波形十分吻合。分析结果表明该模型具有很好的灵活性和较高的精确性,对基于电流变化量原理的保护以及误动作的排除等相关问题的研究具有十分重要的意义。

Because of the existence of capacitive and inductive components in traction power supply system, there will be dissymmetrical transient current impulsion in the system current when instantaneous fault, permanent fault or engine electrification happens. Under the influence of the current impulsion, protection instrument may make a wrong response according to the theory of current difference. A model of power supply system based on EMTP was built in this paper and the relationship between the transient current impulsion and the transformer was analyzed. According to the momentary augmentation of the losing impedance during the short period of the real transformer, the model of real transformer existed in EMTP has been improved, and the result of simulation which is basically the same with the shape of dissymmetry current impulsion shape of real short proves that the model has great flexibility and accuracy and it has great significance in the aspects of protection research based on the theory of current difference, the elimination of wrong protective action and other relative problems.