含电力电子变压器的直流配电线路双端故障测距方法

Dual-terminal Fault Location Method for DC Distribution Lines with Power Electronic Transformer

含电力电子变压器的直流配电网是当前的研究热点,直流配电线路的故障测距技术是快速定位故障点,尽快恢复供电的重要技术支撑。提出一种基于故障极电流谐波量的直流配电线路双端故障测距方法。通过对测量得到的故障暂态电流波形进行差分滤波和全周傅氏分解,实现对衰减直流分量的消除与故障高频成分的提取。然后利用从两端换流器出口分别计算到故障点过渡电阻上电压相同的特点,推导出故障距离与系统参数及谐波电流间的函数关系,从而实现故障测距。仿真结果表明,所提方法在多种故障情形下均能较为精准地实现故障测距,在不对称的系统参数下仍具有较高的测距精度。

At present,the direct-current(DC)distribution network with power electronic transformers(PETs)deserves extensive research,and the fault location technology for DC distribution lines is an important technical support for quickly locating fault to restore power supply as soon as possible.In this paper,a dual-terminal fault location method for DC distribution lines is proposed based on the harmonic current at fault poles.By performing differential filtering and full-time Fourier decomposition on the measured fault transient current waveform,the decaying DC component is eliminated and the high-frequency fault components are extracted.Then,using the characteristics of equal voltage drop across the fault resistance calculated from the outlets of both terminals of the converter,the functional relation between the fault distance and the system parameters and harmonic current is deduced so as to achieve fault location.Simulation results show that the proposed method can accurately locate fault under various fault conditions,and it still has higher location accuracy even with asymmetric system parameters.