单片机实现的电力系统零序电流保护_毕业设计 精品

安徽工业大学 毕业设计（论文）说明书

单片机实现的电力系统零序电流保护

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安徽工业大学 毕业设计（论文）说明书

摘 要

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电力系统继电保护是保证电力系统安全稳定运行、限制电力系统大面积停电事故最基本和最有效的技术手段。根据接地短路时零序电流大小变化作为故障特征量，变压器接地方式、非全相运行、单相自动重合闸等因素对零序电流保护的运行产生重要的影响，必要时需要采取相应闭锁装置。

零序电流保护属于小接地电流系统的保护方式，它利用系统发生故障时零序电流比正常运行时大的特点，来实现有选择性地发出信号或瞬时切断主回路电源, 避免事故的发生。零序电流可以通过对称分量法求得，实际应用时可用电流互感器测得所需分量。

本文结合零序电流和单片机的各自优点，阐述和论证电力系统零序电流保护原理以及基于单片机的实现。

关键词：继电保护；零序电流；单片机；对称分量法

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安徽工业大学 毕业设计（论文）说明书

Abstract

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Power system relay protection is to guarantee the safe and stable operation of power system and it is also the most basic and the most effective technological way to restrictions on a large scale power blackouts．According to ground short circuit，Transformer grounding method the size changed of the zero sequence current as fault characteristics, transformer grounding method. The open-phase operation and single-phase automatic reclosing such as zero-sequence current protection of the operation have a major impact. When it's necessary, we need to adopt corresponding locking device.

Zero-sequence current protection is the protection of the small ground current system. It uses the characteristic of zero sequence current of the failure system bigger than normal operation. To achieve selective transient signal or cut off the main circuit power supply, in order to avoid accidents. Zero sequence current can be obtained by symmetrical component method，it can be measured by the current transformer in practical applications.

In this paper, combined with the advantages of the zero-sequence current and microcontroller ,this design focuses on explain and demonstrate the power system zero-sequence current protection principles and single chip microcomputer-based realization method.

Keywords：Relay protection, zero-sequence current, single-chip microcomputer,

Symmetrical components method.

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安徽工业大学 毕业设计（论文）说明书

目 录

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第1章 绪论......................................................... 1

1.1引言 ........................................................ 1 1.2 课题的研究背景和意义........................................ 1 第2章.电力系统继电保护............................................. 3

2.1电力系统 .................................................... 3

2.1.1 电力系统简介.......................................... 3 2.1.2 电力系统的组成........................................ 4 2.2 继电保护.................................................... 5

2.2.1 电力系统发展简史...................................... 5 2.2.2 研究现状.............................................. 6 2.2.3 继电保护的基本原理.................................... 6 2.2.4 继电保护的组成........................................ 7 2.2.5 对电力系统继电保护的基本要求.......................... 8 2.2.6 发展趋势.............................................. 9

第3章 电力系统零序电流保护........................................ 11

3.1 电力系统零序电流........................................... 11

3.1.1 零序电流简介......................................... 11 3.1.2 零序电流产生原因..................................... 11 3.1.3 电力系统的正序、负序和零序........................... 12 3.2 对称分量法................................................. 12

3.2.1 电力系统的对称分量方法介绍........................... 12 3.2.2 对称分量法原理....................................... 13 3.3电力系统零序电流保护 ....................................... 15

3.3.1 零序电流保护的原则................................... 15 3.3.2 零序电流保护原理..................................... 16 3.3.3 零序电流保护的特点................................... 17

第4章.单片机的A/D扩展............................................ 19

4.1 STC89C52单片机 ............................................ 19

4.1.1 STC89C52RC单片机介绍 ................................ 19 4.1.2 STC89C52RC单片机的工作模式 .......................... 20 4.1.3 STC89C52RC引脚功能说明 .............................. 20 4.2 A/D转换接口 .............................................. 21

4.2.1 A/D转换器概述 ....................................... 21 4.2.2 ADC0809.............................................. 23 4.2.3 ADC0809工作过程 ..................................... 25 4.2.4 A/D转换器与单片机接口要考虑的问题 ................... 26 4.2.5 ADC0809与STC89C52单片机的接口 ...................... 26 4.3 单片机的时间中断........................................... 30

4.3.1 时间中断的工作模式................................... 30 4.3.2 中断服务试验程序..................................... 31

第5章 零序电流保护................................................ 33

5.1 零序电流保护的硬件组成..................................... 33

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