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1、专业好文档基于双端不同步数据的故障定位算法张华中, 王维庆，朱玲玲，崔冉（新疆大学 电气工程学院 ,新疆 乌鲁木齐830000）摘要：本文基于故障时沿线电压的分布规律提出了两种实用性较强的故障测距算法，利用线路两侧的电压和电流正弦相量计算故障距离，不要求双端数据的同步，能消除过渡电阻的影响，具有较高的工程实用价值。本文着重对输电线路故障测距方法进行可行性验证，采用ATP仿真获得故障线路的电气量值，并用Matlab计算故障点位置，仿真结果表明本文所提出的方法有较高的精度，能满足现场实际要求。关键词：输电线路；故障定位；双端不同步；ATP0 引言收稿日期：xxxx-xx-xx. 基金项目：自治区高
2、校高技术研究重点项目 编号：XJEDU2004I04自治区高技术研究发展计划项目 编号：200614118根据测距原理的不同，高压输电线路故障测距算法从数据来源上可分单端测距和双端测距1-8，由于已知信息的局限性，单端测距从原理上无法消除过渡电阻和对端系统阻抗变化带来的影响，在实际应用中难以满足要求，双端测距利用线路两侧的信息量理论上可以克服单端测距的缺点。通信技术的发展使得两端数据能很方便地取得，为此人们提出了许多双端测距的办法9-15。双端故障测距算法可分为两种：一种基于两端同步数据的算法，它需要两端的同步采样，但由于采样偏差及电流互感器和电容式电压互感器的移相等因素的影响，输电线路两端的
3、数据很难达到同步，并且需要GPS同步装置，在失步的情况下无法准确计算出故障距离；另一种是基于两端非同步数据的算法，它不要求两端的同步采样，但一般算法复杂，计算量大。本文在此基础上介绍了两种双端不同步数据的测距方法，一种适用于短线路，另一种适应于长线路，克服了不同步算法复杂的问题，不需要GPS同步装置，可以用在耗资少和不同步的电力系统进行故障测距。1 不同步测距算法原理图1 双端电源单相系统故障等效网络Fig.1 Single-phase grounded fault in double sources system图中：Z为线路单位长度阻抗；ZMS、ZNS分别为M侧、N侧系统阻抗；L为输电线路
4、长度；x为故障点离M侧保护安装处的距离；M、N分别为流过线路M、N侧故障相电流；M、N分别为线路M、N侧故障相电压；Rg为过渡电阻；g为故障支路电流。输电线路上发生故障时，如图1所示，线路无论采用集中参数模型或是分布参数模型，利用输电线路两侧监测到的电压、电流正弦相量计算出的故障点的电压幅值，理论上应该是相等的，与两端电源的相角差无关，所以不要求输电线路两侧同步。图2 故障后沿线电压示意图Fig.2 Diagram of voltage magnitude along the line after fault 图2出示了电压等级为500kV长度为200km的输电线路在40km处发生短路接地故障
5、时线路中各点电压变化趋势，由两侧测到的电压电流相量可以求得输电线全程各点电压的幅值，从而可以看出始、末两端感受到的沿线各点电压的分布情况，如图2所示，它们是单调的，交点（故障点）只有1个。图中虚线的点是始、末端感受到的过了故障点后那段距离的电压幅值。它们并非线路上的真值，由于发生了短路，使得沿线电压不再按原趋势分布，但是始、末端感受到的这段距离的电压幅值却按原趋势变化，从图中可看出，交点就是故障点，测距的关键是找出该点。A 短距离输电线路测距算法对于短线路，电压不高时，可用简单的RL等值模型作为输电线路的等效电路，图1给出了系统单相故障等效图，设线路全长为L，假定距离M端为x 的F处发生故障,
6、则M和F之间的任一点可以用M端的电压和电流表示，同理N和F之间的任一点也可以用N端的电压和电流表示，所以故障处的电压可以用两端的电气量表示M侧测出的故障点电压 （1）N侧测出的故障点电压（2）式中 Z1为线路单位长度的正序阻抗由式(1)、(2)可得 (3)其中 (4) (5)整理式(3)可得如下二次方程 (6)其中 式中M、N、P、Q分别为相量UM、UN、P、Q的相位角。根据双端系统提供的数据以及系统的参数可以求出方程中的系数a、b、c，即可求出方程中未知数, 也就得出了线路的故障距离。B 长距离输电线路测距算法对于一条高压长距离输电线路，应考虑线路的分布参数特性。假定线路单位长度阻抗为RjL
7、，单位长度导纳为GjC，则线路的波阻抗为，传播常数。若以线路M（N）端的电压、电流作为边界条件，可以推出线路上任一点的电压方程 (7) (8)式（7）、（8）可整理为 (9) (10)其中 （11） （12）建立目标函数 (13) 由于线路的参数均为已知量，对端的电气量也可以得到，因此，可以求出使目标函数F(x)有最小值时的X值；也可以建立迭代方程，求出满足式时的X值，因此由式(13)可得到故障点的位置。 2 ATP仿真验证2.1 仿真模型介绍为验证本算法的有效性，采用图3所示的500kV，200km两机模型和ATP、Matlab软件，对各种故障进行仿真。原始数据采样率为每周期96点，采用前置
8、低通滤波环节。为验证算法是否能普遍应用于录波装置和继电保护装置，在利用快速傅立叶算法前将采样率降为每周期24点。低通滤波器输出后经快速傅立叶算法形成各个相量，用于测距算法。考虑到故障发生后，保护装置动作，自启动第二周期以后的电气量可能不存在，故仿真时均采用故障后第二周期数据进行基波提取。通过改变两侧电源相位差、故障类型、故障点位置、过渡电阻的大小等多个影响因素，充分对比分析了两种算法的效果，测距误差采用下式计算：r=(D-x)/L100%，式中 r为相对误差；D为实际故障距离；x为测量距离;L为线路的全长。图3 仿真系统模型Fig.3 Simulation system model 系统等效参
9、数为：M端电源等值阻抗：Zms1=1.05+j43.18 Zms0= j29.09 N端电源等值阻抗：Zns1=1.06+j44.92 Zns0= j37.47线路参数：r1=0.0208/km, l1=0.8984mH/km, c1=0.0129Fr0=0.1148/km, l0=0.2886mH/km, c0=0.0052F2.2 仿真结果分析为了检验两端数据不同步对测距结果的影响，人为设置了两端不同步角度，故障点距M端50km，过渡电阻为50欧， 结果如表1所示，可以看出在双端数据同步和不同步条件下该方法的计算结果差别不大。从而，在两端数据不同的情况下，测距仍能达到较满意的精度。第一种方
10、法由于忽略了分布电容的影响，可以看出测距精度没有第二种方法精度高。表1 50 km 处不同步角度下的测距结果Table 1 The fault locating results using unsynchronized data at 50 km表2 A相接地短路（Rg50）Table.2 Phase A grounded fault（Rg50）鉴于输电线路单相接地故障的多发性及精确测距的困难度，本文以此类故障给出了详细的测试结果如表2所示 ，输电线路两端相位差20。针对非A相单相故障，相间故障、相间短路接地故障和三相故障，给出了详细的仿真结果如表3所示，故障距离M端100km。表 3 100
11、 km 处不同故障类型短路仿真结果（Rg50）Table 3 Fault location results at 100 km under different types of faults（Rg50）表4给出了过渡电阻较高（300）的情况下A相接地短路进行仿真分析的测距结果。表4 A 相经300 接地短路Table 4 Phase A grounded fault via 300 fault resistance 3 算法精度分析1).滤波的效果。本文中的两种算法的判据都是电压幅值相等的原理，但它只适应于正弦模型，故障后的电压、电流含有大量的非周期分量和高次谐波，若不能很好的滤出，将会影响测
12、距的精度。当不同步角度是负值时，两端的采样的时刻不一样， 若不能很好的滤波影响会更大。2).本文中的短线路算法的输电线路模型是建立集中参数模型的基础上，输电线路的故障发生在靠近电源两端时，对侧的电源提供的电流受分布电容的影响较大，供给短路点的电流和它提供的电流相量有一定的误差，测距精度有所下绛。3).算法1中利用电压幅值相等建立了二次方程，解方程可以得到了两个根，从仿真结果可看出，另一个根或者为负值，或者超出了线路的长度，真伪性容易判断；算法2理论上不存在判别根的真伪问题。4 结论本文基于不同的输电线路模型提出了两种故障测距的方法，都是根据故障点处电压幅值相等的原理来确定故障点的位置，原理简单
13、，两端电气量的采集数据不要求同步，传输的数据少，测得的故障距离是真实的，也不需要判别故障类型，算法易于实现，理论及仿真结果表明：此双端测距算法具有很大的优越性和较大的工程使用价值。参考文献1 贺家李，葛耀中超高压输电线故障分析与继电保护M北京：科学出版社，1987He Jiali, ， Ge YaozhongFault analysis and relay protection of EHV transmission linesMBeijing：Science Press，19872 王梅义电网继电保护应用M北京：中国电力出版社，1997Wang MeiyiApplication of rel
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23、easurementsJIEEE Trans on Power Delivery，2004， 19(4)： 1619-162215 李斌，贺家李，杨洪平等特高压长线路距离保护算法改进J电力系统自动化，2007，31(1)：43-46Li Bing，He Jiali，Yang Hongping，et alImprovement of distance protection algorithm of UHV long transmission line JAutomation of Electrical Power Systems，2007，31(1)：43-46张华中（1979），男，硕士，研究
24、方向为电力系统继电保护。E-mail:王维庆 （1959），男，教授，博士生导师，研究方向为电力系统继电保护及洁净能源技术。E-mail: 朱玲玲（1980），女，硕士，研究方向为电力系统故障诊断。E-mail:Fault Location Algorithms Based on Unsynchronized Data of Two-terminal ZHANG Huazhong，WANG Weiqing，ZHU Lingling，Cui Ran(School of Electrical Engineering, Xinjiang University,Urumqi830000 China)A
25、bstract: Two practical algorithms are presented based on the distributed regularity of voltage along the transmission line when fault occurs in the paper. Fault location is calculated using current and voltage sinusoidal phasors at both ends without necessity of data synchronization, and the influen
26、ce of fault resistance can be eliminated. So they have more practical values. The verification of their feasibility is emphasized in the paper. The electric parameters are acquired by ATP simulation and the fault location is calculated with Matlab programming. Lots of simulation results show these m
27、ethods presented in the paper can precisely locate the fault site and completely satisfy the practical need in the field. Key words: transmission line；fault location；unsynchronized data of two-terminal；ATPEditors note: Judson Jones is a meteorologist, journalist and photographer. He has freelanced w
28、ith CNN for four years, covering severe weather from tornadoes to typhoons. Follow him on Twitter: jnjonesjr (CNN) - I will always wonder what it was like to huddle around a shortwave radio and through the crackling static from space hear the faint beeps of the worlds first satellite - Sputnik. I al
29、so missed watching Neil Armstrong step foot on the moon and the first space shuttle take off for the stars. Those events were way before my time.As a kid, I was fascinated with what goes on in the sky, and when NASA pulled the plug on the shuttle program I was heartbroken. Yet the privatized space r
30、ace has renewed my childhood dreams to reach for the stars.As a meteorologist, Ive still seen many important weather and space events, but right now, if you were sitting next to me, youd hear my foot tapping rapidly under my desk. Im anxious for the next one: a space capsule hanging from a crane in
31、the New Mexico desert.Its like the set for a George Lucas movie floating to the edge of space.You and I will have the chance to watch a man take a leap into an unimaginable free fall from the edge of space - live.The (lack of) air up there Watch man jump from 96,000 feet Tuesday, I sat at work glued
32、 to the live stream of the Red Bull Stratos Mission. I watched the balloons positioned at different altitudes in the sky to test the winds, knowing that if they would just line up in a vertical straight line we would be go for launch.I feel this mission was created for me because I am also a journal
33、ist and a photographer, but above all I live for taking a leap of faith - the feeling of pushing the envelope into uncharted territory.The guy who is going to do this, Felix Baumgartner, must have that same feeling, at a level I will never reach. However, it did not stop me from feeling his pain whe
34、n a gust of swirling wind kicked up and twisted the partially filled balloon that would take him to the upper end of our atmosphere. As soon as the 40-acre balloon, with skin no thicker than a dry cleaning bag, scraped the ground I knew it was over.How claustrophobia almost grounded supersonic skydi
35、verWith each twist, you could see the wrinkles of disappointment on the face of the current record holder and capcom (capsule communications), Col. Joe Kittinger. He hung his head low in mission control as he told Baumgartner the disappointing news: Mission aborted.The supersonic descent could happe
36、n as early as Sunday.The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmospher
37、e (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 kilometers) and into the stratosphere. As he crosses the boundary layer (cal
38、led the tropopause), he can expect a lot of turbulence.The balloon will slowly drift to the edge of space at 120,000 feet (22.7 miles/36.53 kilometers). Here, Fearless Felix will unclip. He will roll back the door.Then, I would assume, he will slowly step out onto something resembling an Olympic div
39、ing platform.Below, the Earth becomes the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, hell be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end.Skydiver preps fo
40、r the big jumpWhen he jumps, he is expected to reach the speed of sound - 690 mph (1,110 kph) - in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him completely.If he goes too fas
41、t or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes its not needed. Instead, he plans to deploy his 270-square-foot (25-square-meter) main chute at an altitude of around 5,000 feet (1,524 meters).In order to deploy this chute successfully
42、, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds.Even if everything goes as planned, it wont. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is gu
43、aranteed to work higher than 25,000 feet (7,620 meters).It might not be the moon, but Kittinger free fell from 102,800 feet in 1960 - at the dawn of an infamous space race that captured the hearts of many. Baumgartner will attempt to break that record, a feat that boggles the mind. This is one of those monumental moments I will always remember, because there is no way Id miss this.