【作者】 石吉银；

【导师】 李欣然；

【作者基本信息】 湖南大学 ， 电力系统及其自动化， 2007， 硕士

【摘要】 我国中低压配电网广泛采用中性点不接地系统或是经消弧线圈接地系统,即小电流接地系统。小电流接地系统单相接地故障率较高,但其故障选线和测距至今未能很好地解决。究其原因,主要体现为故障电流太小,特征不明显。随着配电网自动化水平的提高,小电流接地系统单相接地故障选线和测距问题需要迫切解决。本文在总结了现有的选线和测距方法的基础上,提出了用获得线路阶跃响应来实现故障选线和测距的方法。经分析表明,故障线路和非故障线路阶跃响应频谱特性表现出较大的差异:故障线路幅频特性比非故障线路大,且幅频特性反相。本文用所得出的结论进行故障选线仿真分析,结果准确。本文还分析了故障线路阶跃响应幅频特性峰值及其所对应的频率与故障距离之间的关系,并以此作为测距特征量;通过ATP仿真获得样本数据,训练了BP神经网络,实现了测距特征量到故障距离的映射。仿真结果表明,此方法可以实现准确测距。本文设计了小电流接地系统单相接地故障的选线和测距装置的硬件及软件方案。利用模块化设计的思想,本文提出了硬件系统的设计方案,给出了器件选择的原则、系统设计的思路以及实现的方法;分析了用DSP和CPLD组建数据采集系统的合理性,成功设计了基于二者的控制系统。本文利用软件工程的思想给出了软件设计方案,详细对各功能模块进行了分析,并给出了设计方法;分析了软件抗干扰的重要性,给出了提高软件可靠性的方法;搭建了软件调试平台,完成了软件模块的编写。仿真结果表明,本文提出的基于线路阶跃响应实现故障选线和测距的方法可行,有一定的实用价值;设计的硬软件系统,具有较高的工程意义。更多还原

【Abstract】 Non-Grounded or Petersen-Grounded systems are called neutral un-effectual grounded systems (NUGS), which are widely used in the middle and low voltage distribution networks in China. The fault rate of single-phase-to-ground of NUGS is high, but its fault line selection and location have not been well solved yet. It mostly because the fault current is small and the fault trait is not obvious. With the improvement of the distribution network automation, the fault line selection and location need to be solved urgently.Based on the summary of the line selection and location methods existed, this paper presents a new method of line selection and location by obtaining the step response of the lines. The analysis indicates that the spectrum characters are greatly different between the fault and the normal lines: the frequency-amplitude characteristic of the fault line is bigger than the normal, and the magnitude-frequency characteristic of the fault line is reverse to the normal. By the analysis of fault line selection simulation, this result presented can select the true line. This paper also analyzs the relation between the peak point of frequency-amplitude characteristic and its corresponding frequency and the fault distance, and takes this two as the locating diagnostic values. By ATP simulation, the sampling data can be got and a BP neural net is trained for establishing the relation between the locating diagnostic values and the fault distance. The simulation result indicates that this method can measure the fault distance accurately.This paper designed the scheme of the hardware and software of the line selection and location device for NUGS. This paper presented the hardware scheme based on modularized designing; and offered the principle for IC device selection, the plan for the system designing and its realization; analyzed the rationality of constructing the data-sampling system with DSP and CPLD and successfully designed a control system based on them. This article presented the scheme of the software designing with the software engineering method, analyzed the each function module and presented their designing method; analyzed the importance of the software anti-jamming and produced the methods for enhancing the software reliability; established the software debugging platform and finished the module software writing.The simulation result indicates that the line step response method presented in this paper for fault line selection and location is feasible, and has certain practical value; the hardware and software system designed have higher project significance.更多还原