變電站干式變壓器缺陷及故障

2013年11月30日, 110 kV某變電(dian)站10 kV1號站用變例行試(shi)驗時發現絕緣電(dian)阻明顯降低, 直流電(dian)阻高壓(ya)(ya)側偏(pian)差達22.353%, 低壓(ya)(ya)側偏(pian)差達3.078%。試(shi)驗不合格。

2014年3月1日, 110 kV某變(bian)電(dian)站10 kV1號(hao)站用變(bian)運行過程中站用變(bian)高壓A相頂部出現匝(za)間(jian)短路, 造成1號(hao)站用變(bian)燒損。

2014 年(nian)3 月21 日, 110 kV某變(bian)電站(zhan)(zhan)(zhan)10 kV1 號站(zhan)(zhan)(zhan)用變(bian)運行過(guo)程中高壓A相頂部(bu)出現匝(za)間短路, 引(yin)起1號站(zhan)(zhan)(zhan)用變(bian)燒損。

燒(shao)損站(zhan)用變均為(wei)(wei)同(tong)一(yi)廠(chang)家(jia)2010 年3 月出廠(chang)的產(chan)品, 各項參數均一(yi)致, 型(xing)號(hao)為(wei)(wei)SC11-80/10.5, 額定(ding)容量80 kVA, 額定(ding)電壓10.5/0.4 kV, 聯結組別為(wei)(wei)Dyn11。

現場處理情況

站用變燒損情況

根據(ju)現場(chang)檢(jian)查, 故(gu)障均在本(ben)體范圍內, 對二(er)次接(jie)線及高低壓(ya)電纜均無影(ying)響。現場(chang)更換站用變(bian)后送電正常(chang)。

站用變解體

對(dui)(dui)燒(shao)損的兩(liang)臺站用變(bian)分別進行了解體(ti)分析, 主要(yao)對(dui)(dui)外觀進行了檢查并對(dui)(dui)線(xian)圈故障部分進行解體(ti)。

外觀檢查

變壓器C相高壓繞組及低壓繞組環氧樹脂絕(jue)緣燒(shao)毀, 主(zhu)要在上端部, 與燒(shao)毀部位對應的B相高壓繞組絕(jue)緣也被(bei)燒(shao)傷, A相繞組無(wu)燒(shao)傷跡象,。

解體檢查情況

對(dui)變壓(ya)器燒毀(hui)部位進(jin)行(xing)解體檢查, 發(fa)現C相高(gao)壓(ya)繞組(zu)燒損處漆包銅線燒黑(hei), 匝間有短路燒損痕(hen)跡。低壓(ya)線圈絕緣(yuan)碳化(hua)。

變電站干式變壓器故障原因分析

1) 站用變產品(pin)質量不良。

兩(liang)臺站用變C相高(gao)壓繞(rao)組及低(di)壓繞(rao)組環氧樹脂絕(jue)緣燒毀, 高(gao)壓繞(rao)組燒損處漆包銅線燒黑, 匝間短路, 低(di)壓線圈絕(jue)緣碳化。廠(chang)家(jia)未(wei)能提供該容量的型(xing)式試驗(yan)報告。

2) 站用變沒(mei)有配置溫(wen)控。

站用變沒有配置溫度控制系統-干式變壓器溫控器 。干(gan)(gan)式(shi)電力變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)的(de)(de)安(an)全運行和(he)使用壽命, 很大程度(du)上取決(jue)于變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)繞組的(de)(de)安(an)全可(ke)靠, 而(er)繞組的(de)(de)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)超(chao)過絕(jue)緣(yuan)(yuan)耐熱溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)致使絕(jue)緣(yuan)(yuan)破壞, 導致變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)不能(neng)正(zheng)常(chang)(chang)工作(zuo), 進而(er)引(yin)發(fa)事(shi)故(gu), 而(er)干(gan)(gan)式(shi)變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)的(de)(de)溫(wen)(wen)(wen)(wen)(wen)(wen)控(kong)是維護干(gan)(gan)式(shi)變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)運行的(de)(de)重要部件, 能(neng)有效防止變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)過高引(yin)發(fa)事(shi)故(gu)。當(dang)變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)達到(dao)100°時(shi)(shi), 溫(wen)(wen)(wen)(wen)(wen)(wen)控(kong)能(neng)自動啟(qi)動風機, 有效降低變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du), 從而(er)保證干(gan)(gan)式(shi)變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)在正(zheng)常(chang)(chang)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)下安(an)全工作(zuo), 當(dang)變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)為(wei)130°時(shi)(shi), 溫(wen)(wen)(wen)(wen)(wen)(wen)控(kong)器(qi)(qi)會發(fa)出蜂鳴報(bao)警, 面板(ban)上“超(chao)溫(wen)(wen)(wen)(wen)(wen)(wen)”燈亮, 并(bing)通過后(hou)板(ban)“報(bao)警”輸(shu)出端(duan)輸(shu)出開關信號給超(chao)溫(wen)(wen)(wen)(wen)(wen)(wen)報(bao)警器(qi)(qi).當(dang)變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)達到(dao)150°時(shi)(shi), 溫(wen)(wen)(wen)(wen)(wen)(wen)控(kong)后(hou)板(ban)“跳(tiao)閘”輸(shu)出端(duan)輸(shu)出開關信號給跳(tiao)閘控(kong)制器(qi)(qi), 以(yi)(yi)切斷電源, 保護干(gan)(gan)式(shi)變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)。根據“GB1094.11-2007電力變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)第(di)11部分(fen)干(gan)(gan)式(shi)變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)”正(zheng)常(chang)(chang)溫(wen)(wen)(wen)(wen)(wen)(wen)升限制表2中規定:干(gan)(gan)式(shi)變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)絕(jue)緣(yuan)(yuan)系(xi)統溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)為(wei)155°, 從上面的(de)(de)分(fen)析可(ke)以(yi)(yi)看到(dao)溫(wen)(wen)(wen)(wen)(wen)(wen)控(kong)可(ke)以(yi)(yi)有效防止變(bian)(bian)(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)過高引(yin)發(fa)事(shi)故(gu)。

3) 站用變沒有配置(zhi)風機。

站用(yong)變(bian)(bian)(bian)沒有(you)配置風機(ji)(ji)。用(yong)干(gan)式(shi)變(bian)(bian)(bian)壓(ya)(ya)器(qi)風機(ji)(ji)強(qiang)迫風冷(leng)是降低干(gan)式(shi)變(bian)(bian)(bian)壓(ya)(ya)器(qi)溫度的(de)(de)有(you)效(xiao)方(fang)(fang)法。干(gan)式(shi)變(bian)(bian)(bian)壓(ya)(ya)器(qi)橫流風機(ji)(ji)安裝于(yu)變(bian)(bian)(bian)壓(ya)(ya)器(qi)的(de)(de)器(qi)身下兩(liang)(liang)側, 置于(yu)干(gan)式(shi)變(bian)(bian)(bian)壓(ya)(ya)器(qi)線(xian)圈的(de)(de)兩(liang)(liang)側, 風機(ji)(ji)出(chu)風口對準干(gan)式(shi)變(bian)(bian)(bian)壓(ya)(ya)器(qi)線(xian)圈方(fang)(fang)向, 冷(leng)卻(que)風直(zhi)接吹(chui)進干(gan)式(shi)變(bian)(bian)(bian)壓(ya)(ya)器(qi)高(gao)、低壓(ya)(ya)冷(leng)卻(que)氣道(dao), 散熱(re)效(xiao)果就好, 這(zhe)樣(yang)才(cai)能確保變(bian)(bian)(bian)壓(ya)(ya)器(qi)的(de)(de)正常安全運(yun)行。

4) 站用變散熱環境(jing)惡劣。

站用(yong)變(bian)(bian)安裝在(zai)密(mi)封的開(kai)關柜(ju)內, 散(san)(san)熱(re)環(huan)境惡劣。由于(yu)站用(yong)變(bian)(bian)長期在(zai)無通風情況下運行(xing), 熱(re)風無法散(san)(san)出, 而站用(yong)變(bian)(bian)又沒有設置溫控進行(xing)保護, 導致熱(re)效應累積, 致使絕緣提前老化(hua), 造(zao)成事(shi)故。

5) 站(zhan)用變(bian)和站(zhan)用變(bian)柜在裝備后未(wei)進行(xing)型式(shi)試驗。

站用變和站用變柜廠家僅對(dui)自生產設備進行型式試驗, 而未對(dui)裝配后整體進行型式試驗, 未對(dui)其溫升及散(san)熱性能(neng)進行考核。

綜上所述:站(zhan)用變(bian)質量不良(liang)是導(dao)致(zhi)站(zhan)用變(bian)正常運行三(san)年后出現損(sun)壞(huai)的主要原因, 加之(zhi)站(zhan)用變(bian)沒有配置溫(wen)控及(ji)風機, 散熱環境惡劣致(zhi)使(shi)熱效應累(lei)積, 造成絕(jue)緣提前劣化, 導(dao)致(zhi)站(zhan)用變(bian)拉弧放電, 致(zhi)使(shi)變(bian)壓器高壓C相繞(rao)組匝(za)間(jian)短路, 短路環流(liu)使(shi)繞(rao)組內(nei)部溫(wen)度升高, 進而燒毀(hui)。

4預防措施

1) 全面梳(shu)理電網在運站(zhan)(zhan)用變情(qing)況(kuang), 梳(shu)理出位于開關(guan)柜(ju)內(nei)的(de)站(zhan)(zhan)用變, 重點對KYN柜(ju)型的(de)柜(ju)內(nei)站(zhan)(zhan)用變柜(ju)進行核查(cha)。

2) 排(pai)查治(zhi)理開(kai)(kai)關柜(ju)(ju)(ju)內(nei)運行環(huan)(huan)境(jing);結合停電對柜(ju)(ju)(ju)內(nei)設備進行全面維護性(xing)檢修及(ji)清掃。重(zhong)點考核(he)試(shi)驗前后站(zhan)用變溫度及(ji)絕緣變化(hua)情(qing)況。控制高壓室及(ji)柜(ju)(ju)(ju)內(nei)的溫濕(shi)度, 及(ji)時開(kai)(kai)啟驅潮裝置(zhi)及(ji)空調(diao)設備, 確(que)保開(kai)(kai)關柜(ju)(ju)(ju)運行環(huan)(huan)境(jing)良好。

3) 開(kai)(kai)展開(kai)(kai)關(guan)柜帶(dai)電測(ce)試工(gong)作。主要開(kai)(kai)展開(kai)(kai)關(guan)柜局(ju)放測(ce)試, 重點關(guan)注站用變柜內局(ju)放情(qing)況。

4) 納入大(da)修技改項目(mu)逐步將開關柜(ju)內站用(yong)變移除(chu), 采(cai)用(yong)戶(hu)外站用(yong)變的形式。

5) 加快(kuai)外(wai)接380 V電源接入(ru)站用電系(xi)統(tong), 確(que)保母線全停時站用電系(xi)統(tong)正常可靠運行。

干式(shi)站(zhan)(zhan)用變(bian)(bian)故障(zhang)頻發(fa)給變(bian)(bian)電站(zhan)(zhan)的(de)安(an)全穩定運行(xing)(xing)(xing)帶來了很大的(de)隱患, 其本體內部絕(jue)緣(yuan)往往由于(yu)質量(liang)問題(ti)及(ji)運行(xing)(xing)(xing)環境不良等因(yin)素提前老(lao)化, 使得變(bian)(bian)壓器繞(rao)組(zu)因(yin)絕(jue)緣(yuan)破(po)壞(huai)而(er)發(fa)生短路故障(zhang), 溫升過高而(er)燒毀。針對(dui)故障(zhang)現(xian)狀, 積極開(kai)展變(bian)(bian)電站(zhan)(zhan)開(kai)關柜運行(xing)(xing)(xing)環境排查(cha)治(zhi)理, 加強站(zhan)(zhan)用變(bian)(bian)運行(xing)(xing)(xing)維(wei)護技(ji)術監測, 大力改(gai)善工作環境, 及(ji)時(shi)發(fa)現(xian)并消除設備缺(que)陷隱患, 是保(bao)證站(zhan)(zhan)用變(bian)(bian)安(an)全運行(xing)(xing)(xing)水平的(de)強有力措施。