毕业论文《电力系统的漏电保护综合设计》

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电力系统的漏电保护综合设计 2015 年 3 月 16 日

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摘 要

随着我国经济建设规模的不断扩大。用电量迅速增长，安全用电这一问题显得尤为重要。低压电网的漏电保护已经引起我国各用电部门及劳动保护部门的高度重视，建立科学的完善的漏电保护体系已迫在眉睫。漏电保护器主要用来防止漏电造成的经济损失及人生触电造成的伤亡，对解决漏电问题有重要意义。

本课题在分析低压电网漏电保护系统的基础上，提出了以单片机为核心，基于零序电流法和最低幅值选相法的漏电保护方案。以单片机为核心进行软硬件设计，实现漏电的检测、快速处理和显示，设计出了可靠价廉的漏电保护器。该装置完善了传统的漏电保护器，能快速判断出电网是否发生漏电及具体是哪一相漏电，并发出用于切除故障的信号。

关键词：漏电保护器，单片机，零序电流

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ABSTRACT

Accompany with the economy’s increase, the use of electricity is growing quickly, and the safety is becoming more and more important. The residual current protect of the low-pressure electricity net has been highly regarded by the electric department, a scientific and full-classed residual protect system is highly recommended. The use of residual current operated protective device can avoid the economy loss of the fire and people’s death due to the electric shock, so it is extensive used.

Based on the actual leakage-protection system for underground low voltage distribution

networks, this paper advance a new scheme which based zero-sequence current and the theory of lowest amplitude, and the single-chip microcontroller MCS-51 is the core. The design of software and hardware, real-time discharging and displaying by applying single-chip microcontroller technology. And in final, intelligent residual current operated device with high reliabiliby is completed. This device bring the traditional residual current operated protective device to

completion ，it could judge whether the electric network leakage of electricity cropped up and which the phase cropped up quickly , and send the relay signals to cut off fault.

KEY WORDS: residual current operated protective device, single-chip microcontroller,

zero-sequence current

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目录

第一章 绪论 ............................................................................................................... 1

1.1 引言 ............................................................................................................ 1

1.2 漏电保护的发展及现状 ............................................................................ 2

1.2.1 国外研究状况 ................................................................................. 2

1.2.2 国内研究状况 ................................................................................. 3

1.3 本文所做工作 ............................................................................................ 4

第二章 漏电原理及分析 ........................................................................................... 5

2.1漏电故障的基本概念 ................................................................................... 5

2.1.1 漏电的定义 ....................................................................................... 5

2.1.2 漏电的种类 ....................................................................................... 6

2.2 漏电保护器的分类 ...................................................................................... 7

2.3 漏电分析 ...................................................................................................... 8

2.3.1 利用节点电压法分析单相漏电 ....................................................... 9

2.3.2 利用节点电压法分析两相漏电 ..................................................... 13

2.3.3 比较两种漏电故障 ........................................................................ 14

2.4 单相漏电各故障参数的变化 .................................................................... 14

2.4.1单相漏电时零序电压的变化规律 .................................................. 15

2.4.2各相对地电压 .................................................................................. 18

2.4.3零序电流 .......................................................................................... 18

2.4.4漏电电流 .......................................................................................... 20

2.5 漏电保护装置的主要参数 ........................................................................ 20

第三章 漏电保护装置的结构及原理 ................................................................... 23

3.1 漏电保护装置的结构 ................................................................................ 23

3.2 漏电判断原理 ............................................................................................ 24

3.2.1漏电判断原理 .................................................................................. 24

3.2.2 漏电相选择原理 ............................................................................. 26

3.3单片机的选用 ............................................................................................. 27

3.3.1 MCS—51单片机系列单片机简介 ................................................ 28

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3.3.2 单片机外部引脚说明 ..................................................................... 31

结束语 ....................................................................................................................... 35

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