三相电机智能保护器的设计

摘要

电动机作为动力设备，被广泛地应用于发电厂和工矿企业。随着我国经济的发展，电动机将会更加广泛的应用于石油、化工、冶金等部门，因此研究设计性能良好的电动机保护装置就更有现实意义。

本文首先介绍了电动机保护的意义、发展现状和存在的问题，描述了电动机运行中常见的故障现象，并针对各种故障特征建立了相应的判断流程图。

因为传统过流保护在电机发生不对称故障时不能够进行有效保护，本文引入了对称分量法作为电机保护的基本理论以检测电机运行中的不对称故障。本装置通过测量电机运行时的零序和负序分量，应用对称分量法，能够对电动机进行短路保护、断相保护、三相不平衡保护、接地保护、堵转保护、欠电压保护、过载保护、过电压保护。

系统采用模块化设计，主要包括：数据采集模块、单片机模块、显示通信模块、电源模块和控制模块。

由于电机保护器的重要性以及对保护功能的精确性、全面性要求，本系统还有进一步完善的必要和潜力。

关键词：电动机保护，89C51，对称分量法

Abstract

The electromotor as the power device is widely used in the power plants andindustrial enterprises. With the development of the economy in our country, theelectromotor will continue to be used in the field of oil, chemical industry andmetallurgy,etc. So, it is very important to produce electromotor protector with good characters.

The meaning of the electromotor protection , present development and the existing problems are introduced in this paper, the general faults of the electromotorrunning is described. According to the characters of the various fault , the mathemodel is established and the theory.

The traditional over-current protector Can not effectively protect motor when there is a imbalanced fault．In this paper,the Symmetrical components method is employed as basic theory of motor protection to fulfill the diagnosis of imbalanced fault．The intelligent protector Can deal with the following motor faults such as short—circuit，loss of phase，imbalance，locked rotor,overload，low—voltage，over-voltage by measuring negative sequence current，positive sequence current and zero sequence current and processing the current data with the Symmetrical components method．

System USES modular design, including: the data acquisition module and single-chip microcomputer module, communication module, that power supply module and control module.

The motor protector should be more accuracy and perfect，So the designed system need more betterments．

Key Words:Electromotor protection，89C51，Symmetrical components method

目录

摘要 .............................................................. I ABSTRACT ......................................................... II 第一章 绪论 ....................................................... 1 1.1 研究意义 .................................................... 1 1.2 电机保护器的历史及发展情况 .................................. 2 1.2.1 热继电器、熔断器和电磁式电流继电器 ...................... 2 1.2.2 模拟电子式电机保护器 .................................... 3 1.2.3 微机式电机保护器 ........................................ 4 第二章 电机保护器原理 ............................................. 6 2.1 电动机故障分析原因 .......................................... 6 2.2 三相电机保护器状态及诊断 .................................... 7 2.3 采用方法 .................................................... 7 2.4 保护器设计要求 ............................................. 13 2.4.1 两相不对称短路保护 ..................................... 13 2.4.2 断相保护 ............................................... 13 2.4.3 三相电压不平衡运行 ..................................... 13 2.4.4 欠压保护 ............................................... 13 2.4.5 过压保护 ............................................... 14 2.4.6 过载保护 ............................................... 14 2.4.7 单相接地故障保护与两相接地故障保护 ..................... 14 第三章 系统硬件总体设计 .......................................... 15 3.1 系统硬件总体设计框图 ....................................... 15 3.2 数据采集模块 ............................................... 16 3.2.1 三相电压采集单元 ....................................... 16 3.2.2 电流采集模块 ........................................... 21

3.2.3 模拟多路转换器 ......................................... 23 3.2.4 A/D转换电路 ............................................ 25 3.3 单片机控制电路设计 ......................................... 29 3.3.1 单片机的选择 ........................................... 29 3.3.2 晶振电路 ............................................... 31 3.3.3 复位电路 ............................................... 32 3.4监测模块 ................................................... 33 3.4.1 通信电路 ............................................... 33 3.4.2 LCD显示电路 ............................................ 34 3.5 电源电路 ................................................... 35 3.6 输入与输出电路 ............................................. 36 3.6.1 键盘电路 ............................................... 36 3.6.2 继电控制 ............................................... 37 第四章 系统软件设计 .............................................. 39 4.1总流程图 ................................................... 39 4.2 故障判断流程图 ............................................. 43 结论 ............................................................. 54 致谢 ............................................. 错误！未定义书签。 参考文献： ....................................................... 55