影响距离保护正确动作的因素分析

 2023-01-20 09:01

论文总字数:30182字

摘 要

距离保护在电力系统的运行中大覆盖,尤其是在高压线路中,由于电压等级过高及其容易发生故障所以必须保证运行的稳定性,但实际运行中却存在许多得悉影响因素,如:出现系统发生振荡、过渡电阻的存在、互感器的二次回路是否断线、保护安装处与故障点间存在分支、电流和电压互感器。

通过对上述各影响的探究,采取行之有效的办法。全文将根据保护制约因素的分析确定方案,解决对影响保护正确动作的原因,保护易发生拒动或是误动的问题,有时还伴有灵敏度降低的情况。目前,针对已有的方案,有多种解决办法,其中包括基于全周傅氏算法处理测量是出现的误差,用四边形特性的距离继电器处理区外故障时过渡阻抗的超越问题,以及用电抗继电器、多相补偿继电器来提升过渡电阻的灵敏度。因为电力系统的复杂程度,许多方案仍然处于无法运行到实际的系统中来,本文讲述了过渡电阻在单侧电源线路和双侧电源线路中发生短路故障时将会出现的问题。实验结果表明,阻抗角的选择精确度越高,拟和的四边形特性的阻抗继电器的理想图形越近似,边界倾角偏差越小,极大的提高了系统运行稳定性。最后利用MATLAB中的M语言编程对110KV的单测电源供电网络对距离保护进行模拟与仿真。

关键词 电力系统,距离保护,电力系统振荡,MATLAB

Abstract

Distance protection with traditional current-voltage protection compared with the relatively high stability, usually make of different voltage level transports line distance to protect.However, now have lots of factors, such as: the useful resistance of the short circuit spot, the power system oscillation voltage transformer secondary circuit is disconnected, error protection installed at the point of failure between the branch current and voltage transformers, transmission lines, series and also capacitor, changes frequency in grid and load impedance. Thanks to the resistance to have exit , maybe it will occur the right of distance operation, resulting in protection, rejection or sensitivity reduction. At present, many solutions have been put forward to eliminate the influence of transition resistance, including processing the measurement impedance error, using quadrilateral distance relay to deal with the problem of transition impedance exceeding when out-of-zone faults occur, and using reactance relay and multiphase compensation relay to enhance the sensitivity of transition resistance. Lots of schemes are in the tastes positions. This paper describes the problems that will occur when the transition resistance is short-circuit fault in the single-side power supply line and the double-side power supply line. Taking quadrilateral characteristic impedance relay as an example, the working principle of different characteristic impedance relays under the influence of transition impedance is analyzed. The different results show that the more difficult the accuracy of impedance select, the more similar the ideal figure of the quadrilateral impedance relay with quadrangular characteristics, and the smaller the deviation of boundary dip angle, which improves the stability of the power system. Analysis and Research of the above constraints will propose appropriate solutions. Finally use the MATLAB language programming on a single measurement 110KV power supply network distance protection for modeling and simulation.

Keywords power systems,distance protection,power system oscillations, MATLAB

目录

摘要 ........................................................................... I

Abstract .......................................................................III

第一章 绪论 ....................................................................5

第二章 距离保护工作分析

2.1 距离保护的基本原理 .........................................................6

2.2 距离保护的动作原理 .........................................................7

2.3 距离保护的时限特性 .........................................................8

第三章 影响距离保护正确动作的主要因素及对策分析

3.1 影响距离保护正确动作的因素分析 .............................................9

3.2 电力系统振荡的具体影响及对策 ...............................................10

3.3 短路点的过渡电阻影响及解决办法 .............................................18

3.4 分支电流对距离保护的影响 ...................................................32

3.5 负荷阻抗的影响及对策 .......................................................33

3.6 影响距离保护的其他因素 .....................................................36

第四章 仿真模型实例

4.1 仿真网络与模型分析...........................................................38

4.2 传统的距离保护与新型微机保护算法.............................................38

4.3 仿真电力系统模型.............................................................39

4.4 数据采样计算 ................................................................40

4.5 MATLAB语言编程..............................................................40

第五章 结束语...................................................................42

致谢 ...........................................................................43

参考文献........................................................................44

第一章 绪论

电力系统越来越发展,电压等级越来越高,网络结构也日趋复杂化,系统的运行方式变化较大,使得线路中的保护也受到较大的影响。传统的保护算法已经不能完全适应电网的发展,寻求更可靠的解决办法首先必须要搞清楚影响线路保护正确动作的因素有哪些。高压输电线路在电网中使用较为广泛,主要是由于它能保证高压输电线路在运行过程中的稳定性,所以如何保证稳定性就成为当前电网亟待解决的问题,所以在电网运行的复杂情况下,引入了距离保护。长距离输电线路的过电流保护保护定值较大,其末端短路电流较小,所以通常满足不了灵敏性的要求,且由于过流保护的时限太长、速断的保护范围无法精确的确定等问题,从而缩小了保护的范围,无法实现保护要求的速动性和选择性,所以采用距离保护,用来保证电力系统的速动性和选择性[1]

距离保护与传统的电流电压保护相比具有比较高的稳定性,常被用于高的电压等级的输电线路中。但是,距离保护仍存在一定的弊端,如在线路中出现,所测量到的阻抗值与整定阻抗值出入大,将会使电压突然变为零,从而出现保护误动的情况。因此,为了保证距离保护在高压输电线路中的可靠性,要采取相应的防范措施。相比较电压保护和零序电流保护,极易受系统运行方式影响,而距离保护能够具有不受运行方式影响,且具有灵敏度较高,通过动作阻抗和时间来确定故障的特性。所以距离保护的运用越来越广泛。

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