摘 要
电力系统与工业生产、人们的生活密切相关，如何保障电网的安全稳定运行就显得尤为重要。当电网发生短路、断线等故障时，就要采取相关措施，使系统以尽量小的代价恢复到稳定运行状态。作用于电力系统单个元件的继电保护装置就是这些措施中最为重要的一种。
当电网发生短路故障时，安装于系统各个元件上的有着相互配合关系的保护装置判别出发生故障的元件，并迅速将故障元件从系统中隔离出来，使得系统剩余部分能正常运行。要使得电网中的保护装置能够正确地动作，就必须使各个保护装置间在定值和动作时间上根据相关规则保持正确的配合关系，也就是要做好电网继电保护装置的整定计算工作。
早前的继电保护整定是通过人工手动计算，不仅费时，也容易出现计算失误。随着计算机技术的飞速发展高级程序语言的出现，基于计算机的继电保护计算软件得到了长足的发展。本文采用面向对象的C++语言，编制了针对配电网的电流三段式保护整定计算程序。实现了环网的解锁和查找，并具备手动和自动计算两种功能，并针对某一基于实际电网改造的系统进行了验证计算，程序计算结果表明了该继电保护程序的计算正确性。
关键词：继电保护，短路，整定计算，配电网,环网
ABSTRACT
Power system has a close relationship with industry and living of human been, so it’s very important to guarantee the steady running of power system. When power grid suffers faults such as short circuit or disconnect of line, the corresponding measures should be taken to get the grid back to steady state. Relay, which equipped in power grid, is one of the most important measures.
When the grid suffers a short circuit fault, the relays in the grid, which have cooperate relation, find the element that the fault locates in, and insulate this element from the grid rapidly. So the rest grid can steadily run. To guarantee the relays in the grid can work correctly, how to cooperate among these relays must accord with the correlative rule. So the relay setting should be computed correctly.
Relay setting is done by human before, which costs a lot of time and is easy to incur computing misplay. With the development of computer and its language, relay setting based on computer has a great progress. In this paper, a three-step current protection program, which is suit for distributing net, is written with C++. In this program, the ring-system of power grid can be found and unblocked, and both manual and automatic relay setting are available. To validate the correctness of the program, the relay setting of a power system adapted from a real distributing net is done, the result is satisfying.
KEY WORDS: relay，short circuit，relay setting，distributing net, ring-system
目 录
前 言 1
第1章 继电保护整定基本原理 3
1.1继电保护整定计算概述 3
1.1.1保护的整定方法 3
1.1.2 差动保护 3
1.1.3阶段式保护 3
1.2 配电网的特征和三段式电流保护的应用特点 4
1.2.1配电网的特征 4
1.2.2 三段式电流保护的应用特点 4
1.3 电流速断保护 4
1.3.1 电流速断保护的整定计算原则 5
1.3.2 电流速断保护整定计算公式 5
1.3.3 灵敏度校验（保护范围的校验） 6
1.3.4电流速断保护的主要优缺点 6
1.4 限时电流速断保护 6
1.4.1限时电流速断保护的整定计算原则 6
