两相短路故障的计算

编号0714141

课程设计

系（部）院：机电工程系

专业：电气工程及其自动化

作者姓名：

学号:

指导教师：职称：讲师

完成日期：年月日

二○一○年十二月

目录

目录 0

摘要 (2)

ABSTRACT (3)

1 引言 (4)

1.1短路故障的原因 (4)

1.2短路故障发生的原因 (4)

1.3短路类型 (4)

1.4短路的危害 (4)

2 电力系统自动化的一般概念 (5)

3 本课程设计的主要任务 (6)

4 课程设计的目的 (6)

5 课程设计任务书 (6)

6课程设计内容及过程 (8)

6.1数学模型 (8)

6.1.1架空输电线的等值电路和参数 (8)

6.1.2变压器等值电路和参数 (9)

6.2对称分量法 (11)

6.2.1不对称三相量的分解 (11)

6.2.2变压器的各零序等值电路 (12)

6.3两相短路接地的分析 (13)

6.4算例 (16)

课程设计总结 (19)

参考文献 (20)

摘要

电力系统自动化(automation of power systems)对电能生产、传输和管理实现自动控制、自动调度和自动化管理。电力系统是一个地域分布辽阔，由发电厂、变电站、输配电网络和用户组成的统一调度和运行的复杂大系统。在电力系统的设计和运行中，必须考虑到可能发生的故障和不正常的运行情况，防止其破坏对用户的供电和电气设备的正常工作。从电力系统的实际运行情况看，这些故障多数是由短路引起的，例如短路时电路的电压骤降,严重影响电气设备的正常运行，短路时保护装置动作,如熔断器的保险丝熔断,将短路电路切除,这会造成停电，而且短路点越靠近电源,停电范围越大,造成生活的不便和经济上的损失，严重的短路会影响电力系统运行的稳定性,可使并列运行的发电机组失去同步,造成系统解列，不对称短路,像单相短路和两相短路。因此除了对电力系统的短路故障有一较深刻的认识外，还必须熟练掌握电力系统的短路计算。这里着重介绍简单不对称故障两相短路接地的常用计算方法。对称分量法是分析不对称故障常用方法，根据对称分量法，一组不对称的三相量可以分解为正序、负序和零序三相对称的三相量。在应用对称分量法分析计算不对称故障时必须首先作出电力系统的各序网络，通过网络化简求出各序网络对短路点的输入电抗以及正序网络的等值电势，再根据不对称短路的不同类型，列出边界方程，以求得短路点电压和电流的各序分量。

关键词：两相短路故障;短路计算;两相短路接地;对称分量法.

Abstract

automation of power systems is to the electric power production, transmission and management achieve automatic control, automatic scheduling and automation management. Power system is a vast, regional distribution by generator, transformer substation, power transmission and distribution network composed of users and the unified dispatching and operation of large complicated system. In power system design and operation, we must consider the possibility of failure and normal operation, prevent power supply of damage to users and electrical equipment to work properly. From the actual operation of power syst em, these problems are mostly caused by a short circuit, E.g. short circuit of voltage sag, when serious influence electric equipment of normal operation, short circuit protection device, such as when 13a fuse fuse, will short-circuit circuit excision, this could cause short-circuit point power, but the closer power supply, power range, the greater the cause of life inconvenience and economically loss, serious short-circuited will influence the stability of power system operation, can make the paratactic operation generator sets lost synchronization, cause system solution columns, asymmetric short-circuit, like ngle-phase short circuit and two-phase short-circuit. so in addition to power system short circuit fault has a more profound understanding, but also must be familiar with power system short-circuit calculations. Here focuses on a simple asymmetric two-phase short-circuit ground fault calculation methods. Symmetry is a common method of asymmetric fault, according to asymmetric method, a set of asymmetri cal three-phase quantity can be decomposed into positive sequence, negative sequence and zero sequence symmetrical three-phase three-phase volume. In the application of symmetry analysis and calculation must be made asymmetric failure of the order power system network, simplifying the network obtained the sequence network short-circuit point on the input reactance and equivalent positive sequence network potential, and then under asymmetric short-circuit the different types of boundary equations are listed, in order to achieve short-circuit voltage and current of each point sequence component.

Keyword: Two-phase short circuit fault; Short-circuit calculation; Two-phase ground short circuit;Symmetry.