直流牵引供电系统短路计算模型分析

分析了现阶段地铁直流系统短路计算存在的问题，对地铁直流供电系统短路计算模型进行了分析与改进，建立了一套符合保护整定和校验要求的故障计算模型。分析了地铁直流系统稳态短路计算误差产生的原因，从机组等效和拐点电流两方面给出了减小误差的方法，并给出了优化后的程序计算流程。介绍了直流侧出口和远端短路暂态电流的计算模型，在此基础上提出了一种通过超调量来区分出口、近端、远端短路故障的方法，以及近端短路暂态电流的计算方法。仿真验证表明，上述计算模型和方法在计算误差和完整性方面满足保护整定与校验要求。

Analysis of short-circuit model for DC traction supply system

This paper analyzes the problems in short-circuit calculation model of DC traction system, and presents a set of fault calculation process meeting the requirements of protection setting and validation by analyzing different fault calculation models. The reasons for producing calculation errors are analyzed. The method of reducing the calculation error in steady-state short-circuit calculation is presented from two aspects of rectifier unit equivalent and knee current. The optimized calculation process is given. Based on the calculation model of transient current of DC-side output short-circuit and remote short-circuit, the overshoot theory is applied to come up with a new method to identify the output short-circuit, close-up short-circuit, and far end short-circuit, and method of calculating the transient current of close-up short-circuit is proposed. Simulation examples confirm the feasibility and accuracy of the proposed models and methods in meeting the requirements of protection setting and validation.