點擊數：19752013-04-26 11:20:44 來源: 汕頭市鐘金達電氣設備有限公司-梅蘭日蘭、施耐德、常熟、指明集團專業供應商、汕頭成套設備廠
問：交流特高壓電網電氣設備的絕緣有(you)什(shen)么(me)特點，其影響(xiang)因(yin)素(su)是什(shen)么(me)?
答：現代電(dian)(dian)網(wang)應具(ju)有安全(quan)不間(jian)斷的(de)(de)基本功(gong)能。實踐表明，在全(quan)部停電(dian)(dian)事故中，輸電(dian)(dian)線路和變(bian)電(dian)(dian)站電(dian)(dian)氣設備的(de)(de)絕緣(yuan)閃絡或擊穿是最主要的(de)(de)原因。因此，為了保證電(dian)(dian)網(wang)具(ju)有一(yi)個可接受的(de)(de)可靠性(xing)指標，科學合(he)理(li)地選擇電(dian)(dian)氣裝置的(de)(de)絕緣(yuan)水平至(zhi)關(guan)重要。
電(dian)(dian)氣(qi)設(she)備的(de)絕緣在運(yun)行中會(hui)受到(dao)以下幾種電(dian)(dian)壓(ya)的(de)作(zuo)用：工作(zuo)電(dian)(dian)壓(ya)、暫時(shi)過電(dian)(dian)壓(ya)、操作(zuo)過電(dian)(dian)壓(ya)、雷(lei)電(dian)(dian)過電(dian)(dian)壓(ya)和陡波過電(dian)(dian)壓(ya)。電(dian)(dian)氣(qi)裝置的(de)絕緣強度一般以在上述(shu)各種電(dian)(dian)壓(ya)的(de)作(zuo)用下的(de)放電(dian)(dian)電(dian)(dian)壓(ya)來表征。
交流(liu)特(te)高(gao)(gao)(gao)壓(ya)(ya)設(she)備(bei)絕緣的(de)主要(yao)特(te)點(dian)：一是運行(xing)電壓(ya)(ya)高(gao)(gao)(gao)。為(wei)了降低設(she)備(bei)尺(chi)寸(cun)和(he)造價，通過(guo)采(cai)用(yong)大(da)容量高(gao)(gao)(gao)性(xing)能的(de)避雷器等(deng)(deng)措施，降低過(guo)電壓(ya)(ya)水(shui)平(ping)和(he)設(she)備(bei)試驗(yan)(yan)絕緣水(shui)平(ping)，運行(xing)電壓(ya)(ya)與試驗(yan)(yan)水(shui)平(ping)的(de)比(bi)值同超高(gao)(gao)(gao)壓(ya)(ya)相比(bi)有顯著增(zeng)加。二是設(she)備(bei)的(de)重要(yao)性(xing)提(ti)高(gao)(gao)(gao)。特(te)高(gao)(gao)(gao)壓(ya)(ya)線路輸送容量可(ke)達500千瓦，單(dan)組(zu)變壓(ya)(ya)器容量為(wei)300千瓦，要(yao)求(qiu)設(she)備(bei)具有更高(gao)(gao)(gao)的(de)可(ke)靠(kao)性(xing)。三是設(she)備(bei)尺(chi)寸(cun)比(bi)較(jiao)大(da)。由于設(she)備(bei)尺(chi)寸(cun)增(zeng)大(da)，雜散分布電容和(he)局部發(fa)熱(re)等(deng)(deng)因素對絕緣的(de)長期穩定運行(xing)形成威脅。
特(te)高(gao)壓(ya)輸電(dian)線(xian)路的(de)絕緣可以分為兩類：一類是導線(xian)與(yu)桿塔或(huo)大地(di)之間的(de)空氣間隙，另(ling)一類則是絕緣子。由于電(dian)壓(ya)等級(ji)的(de)提(ti)(ti)高(gao)，特(te)高(gao)壓(ya)輸電(dian)工(gong)程對絕緣子提(ti)(ti)出了(le)更(geng)高(gao)的(de)要(yao)求(qiu)，如高(gao)機械(xie)強度、防污閃、提(ti)(ti)高(gao)過電(dian)壓(ya)耐受能力和降低無線(xian)電(dian)干擾等。
問：什么是內部過電(dian)壓(ya)(ya)?交流特(te)高(gao)壓(ya)(ya)電(dian)網的(de)內部過電(dian)壓(ya)(ya)與(yu)超高(gao)壓(ya)(ya)電(dian)網相比，有哪(na)些相同(tong)點(dian)和不同(tong)點(dian)?
答(da)：內(nei)部(bu)過(guo)(guo)(guo)(guo)電(dian)(dian)壓(ya)(ya)(ya)是由(you)于(yu)電(dian)(dian)力系統故障，或開(kai)關操(cao)作(zuo)而引(yin)起的(de)(de)電(dian)(dian)網中能量(liang)的(de)(de)轉化，從而造成(cheng)(cheng)瞬時(shi)(shi)(shi)(shi)或持(chi)續高(gao)于(yu)電(dian)(dian)網額定允(yun)許(xu)電(dian)(dian)壓(ya)(ya)(ya)，并(bing)對電(dian)(dian)氣裝置可能造成(cheng)(cheng)威(wei)脅的(de)(de)電(dian)(dian)壓(ya)(ya)(ya)升高(gao)。內(nei)部(bu)過(guo)(guo)(guo)(guo)電(dian)(dian)壓(ya)(ya)(ya)分為(wei)操(cao)作(zuo)過(guo)(guo)(guo)(guo)電(dian)(dian)壓(ya)(ya)(ya)和暫時(shi)(shi)(shi)(shi)過(guo)(guo)(guo)(guo)電(dian)(dian)壓(ya)(ya)(ya)兩大類(lei)，其中在故障或操(cao)作(zuo)時(shi)(shi)(shi)(shi)瞬間發生的(de)(de)稱(cheng)為(wei)操(cao)作(zuo)過(guo)(guo)(guo)(guo)電(dian)(dian)壓(ya)(ya)(ya)，其持(chi)續時(shi)(shi)(shi)(shi)間一(yi)般(ban)在幾十毫(hao)秒(miao)之內(nei);在暫態(tai)過(guo)(guo)(guo)(guo)渡過(guo)(guo)(guo)(guo)程結束以后出現的(de)(de)，持(chi)續時(shi)(shi)(shi)(shi)間大于(yu)0.1秒(miao)甚至數小時(shi)(shi)(shi)(shi)的(de)(de)持(chi)續性過(guo)(guo)(guo)(guo)電(dian)(dian)壓(ya)(ya)(ya)稱(cheng)為(wei)暫時(shi)(shi)(shi)(shi)過(guo)(guo)(guo)(guo)電(dian)(dian)壓(ya)(ya)(ya)。暫時(shi)(shi)(shi)(shi)過(guo)(guo)(guo)(guo)電(dian)(dian)壓(ya)(ya)(ya)又可以分為(wei)工(gong)頻過(guo)(guo)(guo)(guo)電(dian)(dian)壓(ya)(ya)(ya)和諧振過(guo)(guo)(guo)(guo)電(dian)(dian)壓(ya)(ya)(ya)。
另(ling)外，在GIS變(bian)電站中，由于隔離刀閘(zha)操作，會(hui)產(chan)生波頭(tou)很陡、頻(pin)率(lv)很高(gao)(gao)的操作過(guo)電壓(ya)，其頻(pin)率(lv)達數(shu)百千周(zhou)至幾十兆(zhao)周(zhou)，稱之(zhi)為快速暫(zan)態(tai)過(guo)電壓(ya)(VFTO)。VFTO可(ke)能威脅(xie)到GIS及其相鄰設備的安全(quan)，特別(bie)是變(bian)壓(ya)器匝間絕緣(yuan)的安全(quan)，也可(ke)能引發(fa)變(bian)壓(ya)器內(nei)部的高(gao)(gao)頻(pin)振蕩。
特(te)高(gao)(gao)(gao)壓(ya)電(dian)(dian)網的過(guo)電(dian)(dian)壓(ya)問(wen)題與(yu)超高(gao)(gao)(gao)壓(ya)電(dian)(dian)網相比(bi)有(you)相似之處，但由(you)于特(te)高(gao)(gao)(gao)壓(ya)系(xi)統線路輸送(song)容量大(da)、距離(li)可能(neng)更長(chang)，而自身(shen)的無功(gong)(gong)功(gong)(gong)率很大(da)，每(mei)100公里的1000千伏線路無功(gong)(gong)功(gong)(gong)率可達530兆乏左右，使(shi)得在甩(shuai)負(fu)荷時(shi)可能(neng)導(dao)致嚴重的暫時(shi)過(guo)電(dian)(dian)壓(ya);在正常運行負(fu)荷變化時(shi)將給無功(gong)(gong)調(diao)節、電(dian)(dian)壓(ya)控制以及(ji)故(gu)障時(shi)單(dan)相重合閘(zha)潛供電(dian)(dian)流熄滅等造成一系(xi)列困難。同時(shi)高(gao)(gao)(gao)電(dian)(dian)壓(ya)長(chang)空氣絕緣的飽和、高(gao)(gao)(gao)海拔和電(dian)(dian)氣設(she)備制造等方面的因素(su)，給過(guo)電(dian)(dian)壓(ya)限制提出(chu)更高(gao)(gao)(gao)的要(yao)求(qiu)。
問(wen)：交流(liu)特(te)高壓電網(wang)的雷電過(guo)電壓有什(shen)么特(te)點?有什(shen)么保護(hu)措(cuo)施?
答：交(jiao)流特高壓(ya)電(dian)(dian)(dian)網(wang)的雷(lei)電(dian)(dian)(dian)過電(dian)(dian)(dian)壓(ya)及其防(fang)(fang)護可以(yi)分為線路和(he)變電(dian)(dian)(dian)站兩個方面(mian)。線路的雷(lei)電(dian)(dian)(dian)過電(dian)(dian)(dian)壓(ya)防(fang)(fang)護包括繞擊和(he)反擊防(fang)(fang)護，變電(dian)(dian)(dian)站的雷(lei)電(dian)(dian)(dian)過電(dian)(dian)(dian)壓(ya)防(fang)(fang)護包括直(zhi)擊雷(lei)和(he)侵入(ru)波的防(fang)(fang)護。
1. 特(te)高壓線(xian)路的雷電過電壓防護
由于特高(gao)(gao)壓輸電(dian)(dian)(dian)(dian)(dian)線(xian)路(lu)(lu)桿塔(ta)高(gao)(gao)度高(gao)(gao)，導(dao)(dao)(dao)線(xian)上(shang)工作電(dian)(dian)(dian)(dian)(dian)壓幅(fu)值很(hen)大(da)，比較容易從導(dao)(dao)(dao)線(xian)上(shang)產生向(xiang)上(shang)先導(dao)(dao)(dao)，相當于導(dao)(dao)(dao)線(xian)向(xiang)上(shang)伸出的導(dao)(dao)(dao)電(dian)(dian)(dian)(dian)(dian)棒，從而(er)引起避雷(lei)(lei)線(xian)屏蔽性能變差。這一點(dian)不但可從電(dian)(dian)(dian)(dian)(dian)氣(qi)幾何(he)理(li)論(lun)上(shang)得(de)到解釋，運(yun)行情(qing)況也提供了佐證。前(qian)蘇聯的特高(gao)(gao)壓架(jia)空輸電(dian)(dian)(dian)(dian)(dian)線(xian)路(lu)(lu)運(yun)行期間內曾多(duo)次發(fa)生雷(lei)(lei)擊(ji)跳閘，基本原因是在耐張轉角塔(ta)處雷(lei)(lei)電(dian)(dian)(dian)(dian)(dian)繞(rao)擊(ji)導(dao)(dao)(dao)線(xian)。日(ri)本特高(gao)(gao)壓架(jia)空輸電(dian)(dian)(dian)(dian)(dian)線(xian)路(lu)(lu)在降(jiang)壓運(yun)行期間雷(lei)(lei)擊(ji)跳閘率也很(hen)高(gao)(gao)，據(ju)分析是線(xian)路(lu)(lu)遭到側面雷(lei)(lei)擊(ji)引起了絕緣子閃絡。
理論分析和運(yun)行情況均表明，特高(gao)壓(ya)輸(shu)(shu)電(dian)線(xian)(xian)路雷(lei)擊(ji)跳閘的(de)(de)主要原因(yin)是避雷(lei)線(xian)(xian)屏(ping)(ping)蔽失效(xiao)，雷(lei)電(dian)繞擊(ji)導線(xian)(xian)造(zao)成的(de)(de)。因(yin)此采(cai)用良好的(de)(de)避雷(lei)線(xian)(xian)屏(ping)(ping)蔽設(she)計(ji)，是提高(gao)特高(gao)壓(ya)輸(shu)(shu)電(dian)線(xian)(xian)路耐(nai)雷(lei)性能的(de)(de)主要措施。同時還應(ying)該考慮到(dao)特高(gao)壓(ya)輸(shu)(shu)電(dian)線(xian)(xian)路導線(xian)(xian)上工作(zuo)電(dian)壓(ya)對避雷(lei)線(xian)(xian)屏(ping)(ping)蔽的(de)(de)影響。對于山區(qu)，因(yin)地形影響(山坡、峽谷)，避雷(lei)線(xian)(xian)的(de)(de)保護(hu)可能需要取(qu)負(fu)保護(hu)角。
2. 特高壓變(bian)電站的雷(lei)電過電壓保護
根(gen)據我國110～500千伏變(bian)(bian)電(dian)(dian)(dian)站多年(nian)來的運行經驗(yan)，如果特高壓變(bian)(bian)電(dian)(dian)(dian)站采用敝開(kai)式(shi)高壓配電(dian)(dian)(dian)裝置(zhi)，可直(zhi)(zhi)接在變(bian)(bian)電(dian)(dian)(dian)站構架(jia)上(shang)安裝避雷針(zhen)或避雷線作為直(zhi)(zhi)擊(ji)雷保護裝置(zhi);如果采用半封閉組合(he)電(dian)(dian)(dian)器(qi)(HGIS)或全封閉組合(he)電(dian)(dian)(dian)器(qi)(GIS)，進出線套管需設直(zhi)(zhi)擊(ji)雷保護裝置(zhi)，而(er)GIS本身僅(jin)將其(qi)外殼接至變(bian)(bian)電(dian)(dian)(dian)站接地網(wang)即可。
與超高壓變(bian)(bian)電(dian)(dian)(dian)站一樣，特高壓變(bian)(bian)電(dian)(dian)(dian)站電(dian)(dian)(dian)氣設(she)備也需(xu)考慮由架空(kong)輸電(dian)(dian)(dian)線(xian)(xian)路傳入(ru)(ru)的(de)雷電(dian)(dian)(dian)侵入(ru)(ru)波過電(dian)(dian)(dian)壓的(de)保護，其(qi)根本措施在于在變(bian)(bian)電(dian)(dian)(dian)站內適當(dang)的(de)位置(zhi)設(she)置(zhi)避(bi)雷器(qi)(qi)。由于限制(zhi)線(xian)(xian)路上操作過電(dian)(dian)(dian)壓的(de)要求，在變(bian)(bian)電(dian)(dian)(dian)站出線(xian)(xian)斷路器(qi)(qi)的(de)線(xian)(xian)路側和(he)變(bian)(bian)壓器(qi)(qi)回路均(jun)需(xu)要安(an)裝避(bi)雷器(qi)(qi)。至于變(bian)(bian)電(dian)(dian)(dian)站母線(xian)(xian)上是否要安(an)裝避(bi)雷器(qi)(qi)，以及各避(bi)雷器(qi)(qi)距(ju)被保護設(she)備的(de)距(ju)離(li)，則需(xu)通過數(shu)字仿真計算予以確定。
問：交流特高(gao)壓(ya)電網絕緣配(pei)合的特點是什么(me)?與超高(gao)壓(ya)電網有什么(me)區別?
答：絕緣(yuan)配合(he)技術是考慮運行環境(jing)和過(guo)電壓保護(hu)裝(zhuang)置(zhi)特性的(de)基礎上，科學合(he)理地選(xuan)擇電網中(zhong)電氣裝(zhuang)置(zhi)的(de)絕緣(yuan)水平。在此過(guo)程(cheng)中(zhong)，權衡設備造價、維修費(fei)用和故障損失，力求(qiu)用合(he)理的(de)成本(ben)獲得較好的(de)經濟利益。
交(jiao)流特(te)高(gao)壓(ya)(ya)電(dian)(dian)(dian)(dian)網(wang)(wang)中(zhong)，由于空(kong)氣間隙的放電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓(ya)(ya)在(zai)(zai)操(cao)作過電(dian)(dian)(dian)(dian)壓(ya)(ya)下(xia)呈現飽(bao)和特(te)性，從而(er)使得電(dian)(dian)(dian)(dian)網(wang)(wang)中(zhong)電(dian)(dian)(dian)(dian)氣設備的絕(jue)緣(yuan)(yuan)占據電(dian)(dian)(dian)(dian)網(wang)(wang)設備總投資的份額(e)愈來(lai)愈大(da);同時(shi)(shi)由于特(te)高(gao)壓(ya)(ya)電(dian)(dian)(dian)(dian)網(wang)(wang)輸送容量巨大(da)，絕(jue)緣(yuan)(yuan)故障的后果將非(fei)常嚴重，因此(ci)在(zai)(zai)特(te)高(gao)壓(ya)(ya)電(dian)(dian)(dian)(dian)網(wang)(wang)中(zhong)絕(jue)緣(yuan)(yuan)配合(he)問題更值得關注，在(zai)(zai)特(te)高(gao)壓(ya)(ya)的絕(jue)緣(yuan)(yuan)配合(he)研究中(zhong)需采(cai)用更精確的方法。例如對(dui)于操(cao)作過電(dian)(dian)(dian)(dian)壓(ya)(ya)作用下(xia)空(kong)氣間隙的選擇，宜采(cai)用長操(cao)作波頭(1000微秒(miao))的試驗情況替代(dai)以往超高(gao)壓(ya)(ya)電(dian)(dian)(dian)(dian)網(wang)(wang)線(xian)路絕(jue)緣(yuan)(yuan)配合(he)時(shi)(shi)采(cai)用標準操(cao)作波形(250微秒(miao))。
問：交流特高壓電(dian)網有哪(na)些限制內部過電(dian)壓的措施?
答：交流特高壓(ya)輸(shu)電系(xi)統(tong)限制內部過電壓(ya)的主要措(cuo)施如下：
1.輸電線路上裝(zhuang)設高壓并(bing)聯電抗器，其(qi)中性點通過(guo)小電抗接地(di);
2. 線路的(de)架空地線(避雷線)采用光纖電纜(OPGW)或良導(dao)體導(dao)線;
3. 變電站母線和輸電線路上裝設(she)吸收能量較大(da)的(de)避雷器;
4. 斷路器采用(yong)合分(fen)閘電阻;
5. 在GIS變(bian)電(dian)站中采用有電(dian)阻接入的隔離刀閘裝置。