【作者】 李健；

【导师】 卢继平；

【作者基本信息】 重庆大学 ， 电气工程， 2007， 硕士

【摘要】 配电系统担负着直接为广大用户供电的责任。随着社会经济的发展,人们对电力的需求日益增长,同时也对供电质量提出了更高的要求。因此,当配电系统故障发生后,快速有效地检出故障线路,及时排除故障以恢复供电,对保障系统安全、稳定运行和供电可靠性具有深远的意义。配电系统中性点采用小电流接地方式在我国得到了广泛应用。配电系统发生单相永久接地故障后,短路电流只能通过对地电容或阻抗形成小电流回路,故障信号微弱导致选线困难。同时,由于配电系统结构复杂,故障定位也是一个公认的难题。本文首先在分析了配电系统单相接地故障特征的基础上,针对装设零序电流互感器的配电系统,提出了运用在时频空间皆具有良好聚焦特性的小波包变换,以适当频率带宽,对故障零序暂态电流信号进行处理。按照能量的观点,选择系统小波包变换能量最集中的频带来实现配电系统接地选线的新方法。接着针对只配置了A、C两相电流互感器配电系统,提出了基于A、C相电流小波变换能量的故障选线方法。最后,结合小波分析方法和神经网络理论,构建了小波神经网络模型,并且研究了将该模型引入到配电系统故障定位中的新方案。理论分析及大量仿真试验结果证明,本文提出的配电系统故障选线方法准确、可靠,具有较强的适应性。特别是基于A、C相电流分析的选线方法能有效地检测出在只配置A、C两相电流互感器配电系统中发生了B相单相接地的故障线路,克服了传统基于零序电气量的选线方法遇到这类故障失效的缺点。同样,大量仿真试验结果也证明了本文提出的基于小波神经网络模型的配电系统故障定位方案具有一定的可行性,并对未来的配电系统高精度故障定位研究有重要的推动作用。更多还原

【Abstract】 The large amounts of power distribution systems take on the basic task of mains power supply to the widespread consumers. Along with the development of society and economy, the demand for power supply and its quality has increased rapidly in recent years. Consequently, it is necessary to analyze the abnormal state and find out the insulation hidden trouble of distribution networks. Besides, faults should be detected rapidly and effectively in order to guarantee the operation of the distribution systems safely and reliably.The small current grounding power system is a popular neutral grounding mode around the world and is widely used in our country. However, the faulty line identification and fault location in such system are acknowledged two difficult problems, which have not solved successfully for many years.Firstly, a new method of faulty line selection in distribution system is proposed in this paper, in which the signal of zero-sequence transient current is dealt with the way of the wavelet package based on analyzing the characteristics of the single-phase earth fault in distribution system. The method just mentioned is validated by a great number of simulation experiments in Matlab accurately and reliably for various distribution systems with different neutral grounding modes. Then, a new way to identify the faulty line in the distribution systems, two current transformers only installed in phase A and C, has been presented. Finally, the fault location algorithm has been presented, combining the Wavelet Package Transform and the Neutral Network.Theoretical analysis and a variety of simulation results show that the proposed methods are accurate and reliable. They are suited for various small current grounding systems, furthermore, the robustness and feasibility of there schemes are also testified. And the method of fault location in distribution systems proposed in this paper has also been validated by many simulation results.更多还原