基于单片机的线路差动保护系统设计

摘要

随着我国微型电子技术和嵌入式系统的发展，目前行业内相对比较传统的线路差动保护系统无法满足客户的需求。为了改进传统线路差动保护系统在控制上得短板问题，在本次毕业设计中，将使用相对先进、快捷、智能的控制机制。该系统的控制大脑为核心控制器51系列嵌入式开发系统，主要采用数字控制技术。该线路差动保护系统设计具有智能控制、差动保护等功能，而且性价比高、度准确、能耗较低、制作简易、称重方便快捷等特点，给人民生活带来了很大的影响，在市场上很受欢迎。

电力作为一种高级、清洁、方便的能源利用形式，正越来越广泛地应用于经济社会的各个方面。电力系统运行的安全性是形成系统威胁的主要问题，然而电力系统中的故障却是不可避免的。为确保系统安全稳定运行，增强供电的可靠性和连续性,就需要一个优质的故障诊断分析系统。输电线路，它连接着电源和各种用电设备,实现电能的传输任务。当输电线路发生短路故障时,短路电流比正常工作电流大许多倍，产生巨大的热效应和力效应。这不仅危及线路的本身的运行，而且给整个电力系统的安全稳定运行带来了隐患。本设计对采用单片机构成结构简单，成本低，使用方便的三段式电流保护装置的硬件结构、软件设计进行了研究，本文采用STC89C52单片机以及单片机最小系统的输电线路差动保护装置。本论文重要包括二大部分的内容。第一部分介绍了微机保护的相关知识，第二部分为单片机实现线路过流保护的硬件电路设计，包括模拟电流输入、单片机系统、继电器动作、以及按键和显示电路，并介绍了了LM324、AD0809、LF398 等芯片。

关键词：差动保护；单片机；电流保护；输电线路；

Abstract

With the development of micro electronic technology and embedded system in China, the traditional line differential protection system can not meet the needs of customers. In order to improve the traditional line differential protection system in the control of the short board problem, in this graduation project, will use relatively advanced, fast, intelligent control mechanism. The control brain of the system is the core controller 51 series embedded development system, which mainly adopts digital control technology. The line differential protection system design has intelligent control, differential protection and other functions, and cost-effective, accurate, low energy consumption, simple production, convenient and fast weighing characteristics, has brought a great impact on people's lives, is very popular in the market.

Electric power, as an advanced, clean and convenient form of energy utilization, is more and more widely used in all aspects of economic society. The safety of power system operation is the main problem of system threat, but the failure of power system is inevitable. In order to ensure the safe and stable operation of the system and enhance the reliability and continuity of power supply, a high quality fault diagnosis and analysis system is needed. Transmission line, it is connected with the power supply and various electrical equipment, to achieve the task of electric energy transmission. When a short circuit fault occurs in a transmission line, the short circuit current is many times larger than the normal operating current, resulting in huge thermal effect and force effect. This not only endangers the operation of the line itself, but also brings hidden trouble to the safe and stable operation of the whole power system. In this design, the hardware structure and software design of the three-stage current protection device with simple structure, low cost and convenient use of single chip microcomputer are studied. In this paper, the transmission line differential protection device of STC89C52 single chip microcomputer and the minimum system of single chip microcomputer is adopted. This thesis mainly includes two parts. The first part introduces the relevant knowledge of microcomputer protection, the second part realizes the hardware circuit design of circuit overcurrent protection for single chip microcomputer, including analog current input, single chip microcomputer system, relay action, and key and display circuit, and introduces LM324, AD0809, LF398 and other chips.

Keywords: Differential protection; Single chip microcomputer; Current protection; Transmission lines;

摘要... 1

第一章 绪论... 5

1.1 研究课题背景... 5

1.2 国内外发展概况... 7

1.3 课题研究的目的及意义... 8

1.4 课题的研究内容及章节安排... 9

第二章 线路差动保护... 10

2.1 线路差动保护的基本原理... 10

2.2 线路差动保护的不平衡电流... 10

2.3 平行线路横联方向差动保护... 11

第三章 系统硬件总体设计... 13