摘要
在我国,66KV及其以下电压等级的配电网络中,一般都采用中性点不接地方式或中性点经消弧线圈接地方式,通称为小电流接地方式。单相接地是小电流接地系统中出现最多的故障,如何迅速地确定接地点的位置是一直存在的技术难题。
本文根据小电流接地系统单相接地时零序电流行波的特点,分析了只应用同极性行波测距会由于折、反射波的合成效应造成故障测距误差过大的问题。在此基础上,提出了综合利用不同极性的正向行波和反向行波进行故障测距的新方法。
本文首先介绍了小电流接地系统故障定位的研究现状,简要分析了目前存在的各种定位方法;其次介绍了小波变换的基本理论及其在信号奇异性检测中的应用,为行波测距准备了先进的数学工具;然后阐述了行波测距的基本理论和主要方法,为本文的新测距方法提供了详实的理论基础;最后详细阐述了测距新方法的原理和具体步骤,给出了各种条件下的仿真结果,分析了各种参数对测距结果的影响,验证了该测距新方法的正确性。
该测距新方法抗干扰能力强,可靠性高,有很好的理论价值和应用价值。
In China, small current grounding style, including neutral insulated and neutral grounded with Petersen coil, is widely used in the distribution networks of 66KV or lower levels. Single-phase-grounding fault is the most common fault in the small current grounding system. How to locate the grounding point is a technical problem long existing.
According to the characteristic of the zero-sequence current traveling wave appearing when single phase grounding fault occurs in small current grounding system, the problem that the error is too great when only the traveling waves of the same polarity are used is analyzed in the paper. Based on the analysis, a new method for fault location in small current grounding system is proposed in this paper, in which both positive traveling wave and negative traveling waves are used.
Firstly, the author introduces the research background of fault location in small current grounding system in the paper, and analyzes all kinds of fault location methods existing nowadays. Secondly, the basic theory of wavelet transform and its application in the signal singularity identification are introduced, which supplies an advanced math tool for the traveling wave fault location method. Thirdly, the author explains the basic theory and main methods of traveling weave fault location, which provides a detailed theory basis for the new fault location method. Finally, the author demonstrates the principle and the detailed steps of the new method, shows the simulation results under all kinds of conditions, and analyzes the influences of all kinds of parameters. Based on the simulation, the correctness of the new method is proved.
The new method has a good ability of anti-disturbing. Its reliability is also very high. Therefore, it is valuable for both theory and application.
引文
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