小电流接地系统单相接地选线装置的设计.rar

小电流接地系统单相接地选线装置的设计
摘要

在配电网中，单相接地故障率最高，但由于故障后接地电流小，故障特征不明显，因此小电流接地系统单相接地故障选线问题虽已经研究多年却一直未能很好解决。
本文针对小电流接地系统发生单相接地时，系统的故障特征进行了分析。针对小电流接地故障时的特点，结合目前用的较多群体比幅比相原理，提出了一种新的选线原理即过半选线原理，来实现小电流接地系统选线保护。在此原理基础上设计了以AT89C51单片机为核心的小电流接地系统单相接地故障选线装置，详细论述了该装置的实现原理、系统结构及其软件与硬件实现方法。
该装置灵敏性和可靠性高、运行稳定、抗干扰能力强，系统能够正确区分母线和线路故障，准确地选出故障线路，具有一定理论意义和实际应用价值。
关键词：小电流；单相接地；过半选线；单片机；硬件

Abstract

In the distribution network, the single-phase earth failure rate is highest, because breakdown, the earth current is small, the breakdown characteristic is not obvious, although the undercurrent earth system single-phase earth fault route selection question already studied many years actually not to be able very good to solve.
This article has the single-phase earth in view of the undercurrent earth system, system's breakdown characteristic has carried on the analysis. In view of the undercurrent earth fault's time characteristic, many communities which the union uses at present compared to compared to the principle, proposed one kind of new route selection principle namely more than half route selection principle, realizes the undercurrent earth system route selection protection. Has designed in this principle foundation take AT89C51 monolithic integrated circuit as the core undercurrent earth system single-phase earth fault route selection installment, elaborated this equipment to realize the principle, the system structure and the software and the hardware in detail realizes the method.
The fault line selection installment movement correct, the sensitivity and the reliability high, the movement are stable, antijamming ability, the system can differentiate the bus bar and the line fault correctly, selects the faulty line accurately, has certain theory significance and the practical application value.
Key word：Undercurrent；Single-phase earth；More than half route selection；Monolithic integrated circuit；Hardware

目录

0前言 ……………………………………………………………………………1
1小电流接地系统单相接地故障分析……………………………………………2
1.1中性点不接地电网发生单相接地故障的特点………………………………2
1.2中性点经消弧线圈接地当网单相接地故障的特点…………………………5
2 小电流接地选线的算法………………………………………………………8
2.1 现有选线算法综述 …………………………………………………………8
2.1.1零序电流比幅算法…………………………………………………………8
2.1.2群体比幅比相法……………………………………………………………8
2.1.3无功功率算法………………………………………………………………9
2.1.4五次谐波分量算法…………………………………………………………9
2.1.5有功分量法…………………………………………………………………9
2.1.6小波算法……………………………………………………………………10
2.1.7注入信号法…………………………………………………………………10
2.1.8首半波法……………………………………………………………………10
2.2 选线影响因素分析 …………………………………………………………11
2.3 过半选线原理的提出 ………………………………………………………12
2.3.1故障信息分析………………………………………………………………12
2.3.2过半选线原理………………………………………………………………12
3硬件电路设计 …………………………………………………………………14
3.1 总体思路 ……………………………………………………………………14
3.2  CPU处理模块………………………………………………………………15
3.2.1 AT89C51的结构与性能特点………………………………………………15
3.2.2 AT89C51的引脚使用分配…………………………………………………17
3.3 数据采集模块 ………………………………………………………………19
3.3.1传感器的选取………………………………………………………………19
3.3.2采样信号的调理……………………………………………………………20
3.3.3滤波电路……………………………………………………………………21
3.3.4多路转换器…………………………………………………………………21
3.4 锁相功能模块 ………………………………………………………………22
3.5 A/D转换模块…………………………………………………………………23
3.5.1 AD1674内部结构及其功能………………………………………………23
3.5.2 AD1674引脚及其功能……………………………………………………25
3.5.3 A/D转换与单片机接口电路………………………………………………26
3.6 复位电路……………………………………………………………………27
3.7 存储空间扩展………………………………………………………………28
3.7.1程序存储器扩展……………………………………………………………29
3.7.2数据存储器扩展……………………………………………………………30
3.7.3外部存储器与单片机接线…………………………………………………31
3.8通信系统……………………………………………………………………32
3.9人机对话模块………………………………………………………………35
3.9.1键盘部分……………………………………………………………………35
3.9.2液晶显示部分………………………………………………………………35
3.10 装置硬件设计的抗干扰措施………………………………………………38
4系统软件流程图设计 …………………………………………………………39
4.1软件总体框架…………………………………………………………………39
4.2软件流程图…………………………………………………………………40
4.2.1主程序流程…………………………………………………………………40
4.2.2采样子程序…………………………………………………………………41
4.2.3故障检测流程……………………………………………………………42
4.2.4选线流程设计……………………………………………………………42
4.2.5单片机通信程序……………………………………………………………44
4.3软件抗干扰措施……………………………………………………………45
5技术经济分析…………………………………………………………………46
6结论……………………………………………………………………………47
致谢……………………………………………………………………………48
参考文献…………………………………………………………………………49
附录A 译文………………………………………………………………………50
附录B 外文文献…………………………………………………………………61