课程设计35KV电网继电保护设计——距离保护

1、车辆与动力工程学院课程设计说明书35kv电网继电保护课程设计摘 要本次课程设计的题目是35kv电网继电保护设计距离保护。主要任务是为保证电网的安全运行,需要对电网配置完善的继电保护装置.根据该电网的结构、电压等级、线路长度、运行方式以及负荷性质的要求，给35kv的输电线路设计合适的继电保护。根据给定的相关数据，首先设计了输电线路图，然后进行整定计算。根据对距离保护i，ii， iii段保护的整定计算，熟悉距离保护的基本原理。根据这次设计总结距离保护的优缺点。并对这次设计进行总结。关键词：35kv继电保护、整定计算、故障分析、短路电流计算第一章 概论21.1继电保护的基本概念2第二章 距离保护的要

2、求32.1 电力系统距离保护32.1.1距离保护概念及适用范围32.1.2距离保护的时限特性32.2 阻抗继电器4第三章 距离保护的计算53.1 系统电路图53.2 短路电流计算53.3 距离保护的整定83.4本设计的具体计算133.4.1距离保护i段的整定计算133.4.2距离保护ii段的整定计算和校验133.4.3距离保护iii段的整定计算和校验14第四章 距离保护的评价154.1距离保护的优缺点和应用范围15第五章 设计心得16参考文献17第一章 概论1.1继电保护的基本概念 在电力系统运行中，外界因素（如雷击、鸟害等）、内部因素（绝缘老化，损坏等）及操作等，都可能引起各种故障及不正常运

3、行的状态出现，常见的故障有：单相接地；三相接地；两相接地；相间短路；短路等。 电力系统非正常运行状态有：过负荷，过电压，非全相运行，振荡，次同步谐振，同步发电机短时失磁异步运行等。 电力系统继电保护和安全自动装置是在电力系统发生故障和不正常运行情况时，用于快速切除故障，消除不正常状况的重要自动化技术和设备。电力系统发生故障或危及其安全运行的事件时，他们能及时发出告警信号，或直接发出跳闸命令以终止事件。 继电保护的基本任务： （1）自动迅速，有选择的跳开特定的断路器（2）反映电气元件的不正常运行状态 电力系统对继电保护的基本要求 ：速动性，选择性，灵敏性,可靠性。第二章 距离保护的要求2.1 电

4、力系统距离保护2.1.1距离保护概念及适用范围距离保护是反应故障点至保护安装地点之间的距离（或阻抗）。并根据距离的远近而确定动作时间的一种保护装置。该装置的主要元件为距离（阻抗）继电器，它可根据其端子上所加的电压和电流测知保护安装处至短路点间的阻抗值，此阻抗称为继电器的测量阻抗。当短路点距保护安装处近时，其测量阻抗小，动作时间短；当短路点距保护安装处远时，其测量阻抗增大，动作时间增长，这样就保证了保护有选择性地切除故障线路。 用电压与电流的比值(即阻抗)构成的继电保护，又称阻抗保护，阻抗元件的阻抗值是接入该元件的电压与 电流的比值：u/i=z，也就是短路点至保护安装处的阻抗值。因线路的阻抗值与

5、距离成正比，所以叫距离保护或阻抗保护。距离保护分为接地距离保护和相间距离保护等。 距离保护分的动作行为反映保护安装处到短路点距离的远近。与电流保护和电压保护相比，距离保护的性能受系统运行方式的影响较小。距离保护分为接地距离保护和相间距离保护等。距离保护适用于35kv及以上的电压等级电路。2.1.2距离保护的时限特性距离保护一般都作成三段式，第1段的保护范围一般为被保护线路全长的8085，动作时间为保护装置的固有动作时间。第段的保护范围需与下一线路的保护定值相配合，一般为被保护线路的全长及下一线路全长的3040，其动作时限要与下一线路距离保护第1段的动作时限相配合，一般为05s左右。第段为后备保

6、护，其保护范围较长，包括本线路和下一线路的全长乃至更远，其动作时限按阶梯原则整定。2.2 阻抗继电器阻抗继电器针对的是线路的阻抗而言，故而分析线路阻抗是非常必要的。通常起动元件采用过电流继电器或阻抗继电器。为了提高元件的灵敏度,也可采用反应负序电流或零序电流分量的复合滤过器来作为起动元件。第三章 距离保护的计算3.1 系统电路图图3-13.2 短路电流计算当k2点发生短路时，短路电流的计算如下：最大运行方式下，k2点短路的等值电路图 图3-2-1 等值简化电路图图3-2-2最大运行方式下k2短路时，a电站、c电站到短路点的转移电抗分别为：xak=5.333/2+0.75=3.417xck=0.

7、292+0.876+0.75+4/2=3.918a电站、c电站到短路点的计算电抗为：xjsa=3.417(23/0.8)/100=0.256 xjsc=3.918(24/0.8)/100=0.391查运算曲线图，得a、c短路电流标幺值为：ia0.2*=3.175 ic0.2*=2.412 有名值为：iak0.2=3.17515/(37)=0.74ka ick0.2=2.41210/(37）=0.38ka最小运行方式下，k2点短路的等值电路图图3-2-3等值简化电路图：图3-2-4最小运行方式下k2短路时，a电站、c电站到短路点的转移电抗分别为xak=0.75+5.333=6.083xck=0.

8、292+0.876+0.75+4=5.917计算电抗为xjsa=6.0833.75/100=0.228 xjsc=5.9175/100=0.30查运算曲线图，得a、c短路电流标幺值为ib0.2*=3.433 ic0.2*=2.950 有名值为iak0.2=3.4333.75/(37）=0.201ka ick0.2=2.9505/(37）=0.23ka按照上述方法，可求得k3、k4、k5、k6、k7、k8点短路时相应的短路电流。3.3 距离保护的整定 （1）距离i段的整定距离保护段无延时的速动段它应该只反映本线路的故障，下级出口处发生短路故障时应可靠不动作，所以测量元件的阻抗整定应该躲过本线路末

9、端短路时的测量阻抗来整定。即其中1.5, 满足要求。3.4.3距离保护iii段的整定计算和校验(1)动作阻抗：按躲开最小负荷阻抗整定；kzq=1,=1.15,=0.83， =1.5，i =1.75kazlmin=0.9ue/1.732ifmax=0.935/1.7321.75=10.39=（ zlmin）/ ( kzq)=(0.83*10,39) /(1.5*1.15)=5(2)动作时间：断路器1的动作时间为：= +t=1.5+0.5=2 s断路器2的动作时间为：t2= +t=2.0+0.5=2.5 s取其中较长者，于是,断路器1的动作时间为：t1= +t=2.0+0.5=2.5 s(3)灵敏

10、性校验： 本线路末端短路时的灵敏系数为： /z12=5/0=1.5 ，满足要求。第四章 距离保护的评价4.1距离保护的优缺点和应用范围主要优点：能满足多电源复杂电网对保护动作选择性的要求；阻抗继电器是同时反应电压的降低和电流的增大而动作的，因此距离保护较电流保护有较高的灵敏度。其中段距离保护基本不受运行方式的影响，而、段受系统运行变化的影响也较电流保护要小一些，保护区域比较稳定。主要缺点：不能实现全线瞬动。对双侧电源线路，将有全线的3040的第段时限跳闸，这对稳定有较高要求的超高压远距离输电系统来说是不能接受的。阻抗继电器本身较长复杂，还增设了振荡闭锁装置，电压断线闭锁装置，因此距离保护装置调

11、试比较麻烦，可靠性也相对低些。应用范围：对不要求全线速动的线路，可作为主保护，否则，可作为相间或接地故障的后备保护。第五章 设计心得本次设计是针对35kv输电线路在双回路情况下进行的分析计算和整定的。在进行设计时首先要设计线路图。然后根据设计要求进行距离保护的整定，并且对其进行灵敏度较验。我认为，在这次的课程设计中，在收获知识的同时，还收获了阅历，收获了成熟，在此过程中，我通过查找大量资料，与同学探讨，以及不懈的努力，不仅培养了独立思考、动手操作的能力，在各种其它能力上也都有了提高。更重要的是，通过本次课程设计，我学会了很多学习的方法。而这是日后最实用的，真的是受益匪浅。要面对社会的挑战，只有

12、不断的学习、实践，再学习、再实践。此次课程设计能顺利的完成与同学和老师的帮助是分不开的，在对某些知识模棱两可的情况下，多亏有同学的热心帮助才可以度过难关；更与老师的悉心教导分不开，在有解不开的难题时，多亏老师们的耐心指导才使设计能顺利进行。很感谢学校和老师给我们安排了这次课程设计，让我真正感受到的是合作的重要，许多时候都是组员的讨论，老师的指导中的一句半句启发了我，就出现的让人欣喜的结果；理论知识同样很重要，有些问题都是由于基础知识掌握不好才出现的。在此衷心再次感谢老师的悉心教导和各位同学的帮助！参考文献1 崔家佩.电力系统继电保护及安全自动整定计算.北京：中国电力出版社，20062 张保会，

13、尹项根.电力系统继电保护（第二版）. 北京：中国电力出版社,20093 许建安.继电保护整定计算. 北京：中国水利水电出版社，20034 李光琦.电力系统暂态分析（第三版）.北京：中国电力出版社，20075 贺家李. 电力系统继电保护原理（第四版）. 中国电力出版社.g an employment tribunal claimemployment tribunals sort out disagreements between employers and employees.you may need to make a claim to an employment tribunal if: y

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34、capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. it will climb higher than the tip of mount everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilomete

35、rs) and into the stratosphere. as he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.the supersonic descent could happen as early as sunda.the weathethe balloon will slowly drift to the edge of space at 120,000 feet ( then, i would assume, he will slowly step out onto something resembling an olympic diving platform.below, the earth becomes the concrete bottom of a swimming pool that he want