摘要(yao)(yao):預防性試(shi)驗(yan)是保證電力變壓器(qi)(qi)安全運行的重要(yao)(yao)措(cuo)施,對變壓器(qi)(qi)故障診(zhen)斷具有確(que)定性影響,通過各種試(shi)驗(yan)項目(mu),獲取準確(que)可靠(kao)的試(shi)驗(yan)結(jie)果是正確(que)診(zhen)斷變壓器(qi)(qi)故障的基本(ben)前(qian)提。

前言：根(gen)據《電力設備(bei)交(jiao)接和(he)預防性試驗(yan)(yan)規程》規定的(de)試驗(yan)(yan)項目及試驗(yan)(yan)順序,主要(yao)包括油中(zhong)溶(rong)解氣體分析(xi)、繞組(zu)絕緣電阻(zu)的(de)測(ce)量(liang)(liang)、繞組(zu)直流(liu)(liu)電阻(zu)的(de)測(ce)量(liang)(liang)、介質(zhi)損耗因數(shu)tgD檢測(ce)、交(jiao)流(liu)(liu)耐壓試驗(yan)(yan)、線圈變(bian)形試驗(yan)(yan)、局部放(fang)電測(ce)量(liang)(liang)等。

1.油中溶解氣體(ti)分析

在(zai)(zai)(zai)變(bian)(bian)壓(ya)(ya)器(qi)(qi)診(zhen)斷(duan)中(zhong)(zhong),單靠電(dian)(dian)氣(qi)試驗(yan)方法(fa)往往很難(nan)發(fa)(fa)(fa)現某些局部(bu)(bu)故(gu)(gu)(gu)障(zhang)(zhang)和(he)(he)(he)發(fa)(fa)(fa)熱(re)(re)(re)(re)缺(que)陷,而(er)通過變(bian)(bian)壓(ya)(ya)器(qi)(qi)油(you)中(zhong)(zhong)氣(qi)體(ti)(ti)(ti)(ti)的(de)(de)(de)色譜分(fen)析這種(zhong)化(hua)(hua)學檢(jian)測的(de)(de)(de)方法(fa),對發(fa)(fa)(fa)現變(bian)(bian)壓(ya)(ya)器(qi)(qi)內(nei)部(bu)(bu)的(de)(de)(de)某些潛(qian)伏性(xing)(xing)(xing)故(gu)(gu)(gu)障(zhang)(zhang)及其(qi)(qi)發(fa)(fa)(fa)展程度(du)(du)的(de)(de)(de)早期診(zhen)斷(duan)非(fei)常靈敏而(er)有效,這已為(wei)大量(liang)故(gu)(gu)(gu)障(zhang)(zhang)診(zhen)斷(duan)的(de)(de)(de)實(shi)踐所證明(ming)。油(you)色譜分(fen)析的(de)(de)(de)原理是(shi)基于任何(he)一種(zhong)特定的(de)(de)(de)烴類氣(qi)體(ti)(ti)(ti)(ti)的(de)(de)(de)產生速率(lv)隨(sui)溫度(du)(du)而(er)變(bian)(bian)化(hua)(hua),在(zai)(zai)(zai)特定溫度(du)(du)下,往往有某一種(zhong)氣(qi)體(ti)(ti)(ti)(ti)的(de)(de)(de)產氣(qi)率(lv)會出現值(zhi);隨(sui)著溫度(du)(du)升(sheng)高(gao),產氣(qi)率(lv)的(de)(de)(de)氣(qi)體(ti)(ti)(ti)(ti)依(yi)此為(wei)CH4、C2H6、C2H4、C2H2。這也(ye)證明(ming)在(zai)(zai)(zai)故(gu)(gu)(gu)障(zhang)(zhang)溫度(du)(du)與溶解(jie)氣(qi)體(ti)(ti)(ti)(ti)含量(liang)之間存在(zai)(zai)(zai)著對應的(de)(de)(de)關(guan)系,而(er)局部(bu)(bu)過熱(re)(re)(re)(re)、電(dian)(dian)暈(yun)和(he)(he)(he)電(dian)(dian)弧是(shi)導致(zhi)油(you)浸紙絕(jue)緣(yuan)(yuan)(yuan)中(zhong)(zhong)產生故(gu)(gu)(gu)障(zhang)(zhang)特征氣(qi)體(ti)(ti)(ti)(ti)的(de)(de)(de)主(zhu)要(yao)(yao)原因。變(bian)(bian)壓(ya)(ya)器(qi)(qi)在(zai)(zai)(zai)正常運行(xing)狀態下,由(you)于油(you)和(he)(he)(he)固(gu)體(ti)(ti)(ti)(ti)絕(jue)緣(yuan)(yuan)(yuan)會逐漸老(lao)化(hua)(hua),變(bian)(bian)質,并(bing)分(fen)解(jie)出少量(liang)的(de)(de)(de)氣(qi)體(ti)(ti)(ti)(ti)(主(zhu)要(yao)(yao)包(bao)括(kuo)氫(qing)H2甲烷CH4乙(yi)烯C2H4乙(yi)炔C2H2一氧化(hua)(hua)碳CO二氧化(hua)(hua)碳CO2等(deng)多(duo)種(zhong)氣(qi)體(ti)(ti)(ti)(ti))。當變(bian)(bian)壓(ya)(ya)器(qi)(qi)內(nei)部(bu)(bu)發(fa)(fa)(fa)生過熱(re)(re)(re)(re)性(xing)(xing)(xing)故(gu)(gu)(gu)障(zhang)(zhang),放電(dian)(dian)性(xing)(xing)(xing)故(gu)(gu)(gu)障(zhang)(zhang)或(huo)內(nei)部(bu)(bu)絕(jue)緣(yuan)(yuan)(yuan)受潮(chao)時,這些氣(qi)體(ti)(ti)(ti)(ti)的(de)(de)(de)含量(liang)會迅(xun)速增加。這些氣(qi)體(ti)(ti)(ti)(ti)大部(bu)(bu)分(fen)溶解(jie)在(zai)(zai)(zai)絕(jue)緣(yuan)(yuan)(yuan)油(you)中(zhong)(zhong),少部(bu)(bu)分(fen)上升(sheng)至絕(jue)緣(yuan)(yuan)(yuan)油(you)的(de)(de)(de)表(biao)面,并(bing)進入氣(qi)體(ti)(ti)(ti)(ti)繼電(dian)(dian)器(qi)(qi)。電(dian)(dian)力(li)變(bian)(bian)壓(ya)(ya)器(qi)(qi)的(de)(de)(de)內(nei)部(bu)(bu)故(gu)(gu)(gu)障(zhang)(zhang)主(zhu)要(yao)(yao)有過熱(re)(re)(re)(re)性(xing)(xing)(xing)故(gu)(gu)(gu)障(zhang)(zhang)、放電(dian)(dian)性(xing)(xing)(xing)故(gu)(gu)(gu)障(zhang)(zhang)及絕(jue)緣(yuan)(yuan)(yuan)受潮(chao)等(deng)多(duo)種(zhong)類型(xing)。據有關(guan)資料介紹,在(zai)(zai)(zai)對故(gu)(gu)(gu)障(zhang)(zhang)變(bian)(bian)壓(ya)(ya)器(qi)(qi)的(de)(de)(de)統計表(biao)明(ming):過熱(re)(re)(re)(re)性(xing)(xing)(xing)故(gu)(gu)(gu)障(zhang)(zhang)占63%;高(gao)能量(liang)放電(dian)(dian)故(gu)(gu)(gu)障(zhang)(zhang)占18.1%;過熱(re)(re)(re)(re)兼高(gao)能量(liang)放電(dian)(dian)故(gu)(gu)(gu)障(zhang)(zhang)占10%;火花(hua)放電(dian)(dian)故(gu)(gu)(gu)障(zhang)(zhang)占7%;受潮(chao)或(huo)局部(bu)(bu)放電(dian)(dian)故(gu)(gu)(gu)障(zhang)(zhang)占1.9%。而(er)在(zai)(zai)(zai)過熱(re)(re)(re)(re)性(xing)(xing)(xing)故(gu)(gu)(gu)障(zhang)(zhang)中(zhong)(zhong),分(fen)接開(kai)關(guan)接觸不(bu)(bu)良占50%;鐵(tie)芯多(duo)點接地和(he)(he)(he)局部(bu)(bu)短路(lu)或(huo)漏(lou)磁環流(liu)約(yue)占33%;導線過熱(re)(re)(re)(re)和(he)(he)(he)接頭不(bu)(bu)良或(huo)緊固(gu)件松(song)動引起過熱(re)(re)(re)(re)約(yue)占14.4%;其(qi)(qi)余(yu)2.1%為(wei)其(qi)(qi)他故(gu)(gu)(gu)障(zhang)(zhang)。

對變壓(ya)器故障部位的準確判(pan)斷,有賴(lai)于對其(qi)內部結(jie)構(gou)和運行狀態的全面掌(zhang)握,并(bing)結(jie)合(he)歷年(nian)色(se)譜數據和其(qi)它預防(fang)性(xing)試驗(直阻、絕緣、變比、泄漏、空載(zai)等)進行比較。

2.繞組直(zhi)流電阻(zu)的測(ce)量

它(ta)(ta)是一(yi)項方便而有(you)效的考察繞(rao)組(zu)(zu)絕緣和電(dian)(dian)流(liu)回路連接(jie)(jie)(jie)狀(zhuang)況的試(shi)(shi)(shi)驗,能反(fan)應繞(rao)組(zu)(zu)焊接(jie)(jie)(jie)質量、繞(rao)組(zu)(zu)匝(za)間短(duan)路、繞(rao)組(zu)(zu)斷(duan)股或(huo)引(yin)出線(xian)折斷(duan)、分接(jie)(jie)(jie)開(kai)關及(ji)導線(xian)接(jie)(jie)(jie)觸不良等故(gu)(gu)障,實際(ji)上它(ta)(ta)也是判斷(duan)各(ge)相繞(rao)組(zu)(zu)直流(liu)電(dian)(dian)阻是否平衡(heng)、調(diao)壓開(kai)關檔是否正確的有(you)效手段。如在(zai)對(dui)某變壓器低壓側10KV線(xian)間直流(liu)電(dian)(dian)阻作試(shi)(shi)(shi)驗時,發現不平衡(heng)率為(wei)2.17%,超過部頒標準值1%的一(yi)倍還多(duo),色譜分析(xi)(xi)不存在(zai)過熱故(gu)(gu)障,且每(mei)年預試(shi)(shi)(shi)數(shu)(shu)據(ju)反(fan)映直流(liu)電(dian)(dian)阻不平衡(heng)系數(shu)(shu)超標外,其(qi)它(ta)(ta)項目均(jun)正常,經(jing)分析(xi)(xi)換算后(hou)確定C相電(dian)(dian)阻值較大(da),判斷(duan)C相繞(rao)組(zu)(zu)內有(you)斷(duan)股問題,經(jing)吊(diao)罩(zhao)檢查后(hou),驗證C相確實有(you)一(yi)股開(kai)斷(duan),避免了故(gu)(gu)障的進(jin)一(yi)步(bu)擴(kuo)大(da)。

3.繞組(zu)絕(jue)緣(yuan)電阻的(de)測(ce)量

繞(rao)組連同套管一(yi)起的(de)絕(jue)(jue)(jue)緣(yuan)(yuan)電阻(zu)和吸收比(bi)或化指數(shu),對(dui)變壓(ya)(ya)器整(zheng)體(ti)的(de)絕(jue)(jue)(jue)緣(yuan)(yuan)狀況具有(you)較高(gao)靈敏度,它(ta)能有(you)效檢查出變壓(ya)(ya)器絕(jue)(jue)(jue)緣(yuan)(yuan)整(zheng)體(ti)受潮、部(bu)件表面(mian)受潮或臟污以(yi)(yi)及貫(guan)穿性(xing)的(de)集中缺陷(xian),如各種貫(guan)穿性(xing)短路、瓷(ci)件破裂(lie)、引線(xian)接(jie)殼、器身(shen)內有(you)銅線(xian)搭橋(qiao)等現象(xiang)引起的(de)半(ban)貫(guan)通性(xing)或金(jin)屬性(xing)短路等。相對(dui)來講(jiang),單(dan)純依靠絕(jue)(jue)(jue)緣(yuan)(yuan)電阻(zu)值大小對(dui)繞(rao)組絕(jue)(jue)(jue)緣(yuan)(yuan)作判斷,其靈敏度、有(you)效性(xing)較低(di)。一(yi)方(fang)面(mian)是由于測(ce)量(liang)時試驗電壓(ya)(ya)太低(di),難以(yi)(yi)暴露缺陷(xian),另一(yi)方(fang)面(mian)也(ye)因為絕(jue)(jue)(jue)緣(yuan)(yuan)電阻(zu)與繞(rao)組絕(jue)(jue)(jue)緣(yuan)(yuan)結(jie)構尺寸、絕(jue)(jue)(jue)緣(yuan)(yuan)材料的(de)品種、繞(rao)組溫度有(you)關,但對(dui)于鐵(tie)芯夾件、穿心(xin)螺栓等部(bu)件,測(ce)量(liang)絕(jue)(jue)(jue)緣(yuan)(yuan)電阻(zu)往往能反(fan)映故障(zhang),這是因為這些部(bu)件絕(jue)(jue)(jue)緣(yuan)(yuan)結(jie)構較簡單(dan),絕(jue)(jue)(jue)緣(yuan)(yuan)介(jie)質單(dan)一(yi)。

4.測(ce)量(liang)介質損(sun)耗因(yin)數tgD

它主(zhu)要用來(lai)檢查變(bian)壓(ya)器(qi)整(zheng)體受潮油質劣化、繞組(zu)上附著油泥及嚴(yan)重的(de)(de)(de)局(ju)部(bu)缺(que)陷。介質測(ce)量(liang)(liang)常受表面(mian)泄露(lu)和(he)(he)(he)外(wai)界條件(如(ru)干擾電(dian)(dian)(dian)(dian)(dian)(dian)場(chang)和(he)(he)(he)大氣條件)的(de)(de)(de)影響(xiang),因(yin)而(er)要采取措施減少和(he)(he)(he)消除(chu)影響(xiang)。現(xian)場(chang)我們一般測(ce)量(liang)(liang)的(de)(de)(de)是(shi)連(lian)同套管(guan)一起的(de)(de)(de)tgD,但為了提(ti)高(gao)(gao)測(ce)量(liang)(liang)的(de)(de)(de)準確和(he)(he)(he)檢出(chu)缺(que)陷的(de)(de)(de)靈(ling)敏度(du),有(you)時(shi)也進行分解試驗(yan),以判斷(duan)缺(que)陷所在(zai)(zai)位置。測(ce)量(liang)(liang)泄漏電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)和(he)(he)(he)測(ce)量(liang)(liang)絕(jue)緣電(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)相(xiang)似,只是(shi)其(qi)靈(ling)敏度(du)較(jiao)(jiao)高(gao)(gao),能有(you)效(xiao)發現(xian)有(you)些(xie)其(qi)他(ta)試驗(yan)項目所不能發現(xian)的(de)(de)(de)變(bian)壓(ya)器(qi)局(ju)部(bu)缺(que)陷。泄漏電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)值與(yu)(yu)變(bian)壓(ya)器(qi)的(de)(de)(de)絕(jue)緣結構(gou)、溫度(du)等(deng)因(yin)素有(you)關,在(zai)(zai)《電(dian)(dian)(dian)(dian)(dian)(dian)力(li)設(she)備交(jiao)接和(he)(he)(he)預防性試驗(yan)規程(cheng)》中不作規定,只在(zai)(zai)判斷(duan)時(shi)強調比(bi)較(jiao)(jiao),與(yu)(yu)歷年數(shu)據相(xiang)比(bi),與(yu)(yu)同類型變(bian)壓(ya)器(qi)數(shu)據相(xiang)比(bi),與(yu)(yu)經驗(yan)數(shu)據相(xiang)比(bi)較(jiao)(jiao)等(deng)。介質損(sun)耗因(yin)數(shu)tgD和(he)(he)(he)泄漏電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)試驗(yan)的(de)(de)(de)有(you)效(xiao)性正隨著變(bian)壓(ya)器(qi)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)等(deng)級的(de)(de)(de)提(ti)高(gao)(gao)、容(rong)(rong)(rong)量(liang)(liang)和(he)(he)(he)體積的(de)(de)(de)增(zeng)大而(er)下降(jiang),因(yin)此單純(chun)靠tgD和(he)(he)(he)泄漏電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)來(lai)判斷(duan)繞組(zu)絕(jue)緣狀況的(de)(de)(de)可能性也比(bi)較(jiao)(jiao)小,這(zhe)主(zhu)要也是(shi)因(yin)為兩(liang)項試驗(yan)的(de)(de)(de)試驗(yan)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)太低,絕(jue)緣缺(que)陷難以充分暴(bao)露(lu)。對于電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)性設(she)備,實(shi)踐證明如(ru)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)型套管(guan)、電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)式電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)互感器(qi)、耦(ou)合電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)器(qi)等(deng),測(ce)量(liang)(liang)tgD和(he)(he)(he)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)(rong)量(liang)(liang)CX仍是(shi)故障診(zhen)斷(duan)的(de)(de)(de)有(you)效(xiao)手段(duan)。

5.交流耐壓試驗

它是鑒(jian)定(ding)絕緣強度等(deng)有效(xiao)的方法,特(te)別是對考(kao)核(he)主絕緣的局部缺(que)陷,如繞(rao)(rao)組(zu)主絕緣受(shou)潮、開(kai)裂或在運輸過程(cheng)中引(yin)起的繞(rao)(rao)組(zu)松動(dong)、引(yin)線距離不夠以及(ji)(ji)繞(rao)(rao)組(zu)絕緣上附著(zhu)污物(wu)等(deng)。交流耐(nai)壓(ya)(ya)試(shi)驗(yan)(yan)雖對發現絕緣缺(que)陷有效(xiao),但受(shou)試(shi)驗(yan)(yan)條件限制,要進行(xing)35KV及(ji)(ji)8000KVA以上變壓(ya)(ya)器(qi)耐(nai)壓(ya)(ya)試(shi)驗(yan)(yan),由于電(dian)(dian)(dian)容電(dian)(dian)(dian)流較大,要求高(gao)電(dian)(dian)(dian)壓(ya)(ya)試(shi)驗(yan)(yan)變壓(ya)(ya)器(qi)的額定(ding)電(dian)(dian)(dian)流在100mA以上,目(mu)前這樣(yang)的高(gao)電(dian)(dian)(dian)壓(ya)(ya)試(shi)驗(yan)(yan)變壓(ya)(ya)器(qi)及(ji)(ji)調壓(ya)(ya)器(qi)尚不夠普遍(bian),如果能(neng)對高(gao)電(dian)(dian)(dian)壓(ya)(ya)、大電(dian)(dian)(dian)流電(dian)(dian)(dian)力變壓(ya)(ya)器(qi)進行(xing)交流耐(nai)壓(ya)(ya)試(shi)驗(yan)(yan),對保證變壓(ya)(ya)器(qi)安全運行(xing)有很大意義(yi)。

6.線圈變形檢測

變(bian)壓(ya)器(qi)繞組(zu)(zu)(zu)變(bian)形(xing)是指在電動(dong)力和(he)機械力的(de)(de)作(zuo)用(yong)下,繞組(zu)(zu)(zu)的(de)(de)尺(chi)寸(cun)或(huo)形(xing)狀發生不(bu)可(ke)逆的(de)(de)變(bian)化(hua),包括軸(zhou)向和(he)徑向尺(chi)寸(cun)的(de)(de)變(bian)化(hua)、器(qi)身轉移、繞組(zu)(zu)(zu)扭曲、鼓包和(he)匝間短路等。繞組(zu)(zu)(zu)變(bian)形(xing)是電力系統安(an)全運行的(de)(de)一大(da)隱患,一旦繞組(zu)(zu)(zu)變(bian)形(xing)而未被診斷繼續投入運行則可(ke)能(neng)導(dao)致(zhi)事故,嚴(yan)重時(shi)燒毀線圈。造成變(bian)壓(ya)器(qi)繞組(zu)(zu)(zu)變(bian)形(xing)的(de)(de)主要原因有:

6.1短路故障(zhang)電(dian)(dian)(dian)流沖擊,電(dian)(dian)(dian)動(dong)力(li)使(shi)繞(rao)組容易破壞(huai)或變形。電(dian)(dian)(dian)動(dong)力(li)的(de)產(chan)生是(shi)繞(rao)組中(zhong)的(de)短路沖擊電(dian)(dian)(dian)流與漏磁(ci)相(xiang)互作用的(de)結果,在(zai)運行中(zhong),由于輻向和軸(zhou)向電(dian)(dian)(dian)動(dong)力(li)同時作用,可能使(shi)整(zheng)個繞(rao)組發生扭轉。

6.2在(zai)運輸(shu)或安裝中受到意外沖撞(zhuang)、顛(dian)簸和震動等(deng)。如(ru)某(mou)供(gong)電(dian)部(bu)門在(zai)對(dui)35KV、20000KVA主變(bian)(bian)壓器(qi)(qi)運輸(shu)途中,遭受強烈撞(zhuang)擊。事(shi)后在(zai)對(dui)該變(bian)(bian)壓器(qi)(qi)交接吊罩檢查時,發現油(you)箱下部(bu)固定器(qi)(qi)身(shen)的4個螺栓全部(bu)開焊裂(lie)斷(duan),上部(bu)對(dui)器(qi)(qi)身(shen)定位(wei)的4個定位(wei)釘(ding)全部(bu)松動,并(bing)在(zai)定位(wei)板(ban)上劃(hua)出(chu)小(xiao)槽(cao)。器(qi)(qi)身(shen)向油(you)枕方向縱向位(wei)移(yi)11mm,橫向位(wei)移(yi)23mm,繞組對(dui)端圈錯位(wei),達30mm,可看到器(qi)(qi)身(shen)已經(jing)*沒有(you)固定裝置而處于自(zi)由狀態(tai),并(bing)經(jing)過長途運輸(shu)及多次編組,器(qi)(qi)身(shen)在(zai)油(you)箱中搖晃,必(bi)然造成變(bian)(bian)壓器(qi)(qi)損壞(huai)。

6.3保(bao)護系統有死區,動作(zuo)失靈,導致變壓器承(cheng)受穩定短路電流作(zuo)用時間長,造成(cheng)繞組變形。

結(jie)(jie)語(yu)：在變壓器計劃檢修或故障診斷(duan)中,預(yu)防性試(shi)(shi)驗結(jie)(jie)果(guo)依(yi)舊是*的(de)診斷(duan)參量。每個(ge)(ge)預(yu)防性試(shi)(shi)驗項(xiang)目不能孤立的(de)去看(kan)待,應將(jiang)幾個(ge)(ge)項(xiang)目試(shi)(shi)驗結(jie)(jie)果(guo)有機結(jie)(jie)合起來(lai)綜合分析,這將(jiang)有效提高判定的(de)準確性。