電(dian)(dian)(dian)力變壓(ya)器(qi)是傳輸、分配電(dian)(dian)(dian)能的(de)(de)樞紐，是電(dian)(dian)(dian)力網(wang)的(de)(de)核心元(yuan)件(jian)，其可靠運行(xing)(xing)不僅(jin)(jin)關系到廣大用戶的(de)(de)電(dian)(dian)(dian)能質量，也關系到整個系統的(de)(de)安全程(cheng)度(du)。電(dian)(dian)(dian)力變壓(ya)器(qi)的(de)(de)可靠性由(you)其健康狀況決(jue)定，不僅(jin)(jin)取決(jue)于設計(ji)制造(zao)、結構材料，也與檢修(xiu)維護密切相關。就電(dian)(dian)(dian)力系統中變壓(ya)器(qi)抗(kang)短(duan)路能力的(de)(de)提(ti)高的(de)(de)問題進行(xing)(xing)探討。
一、電力變壓器概述
電(dian)(dian)(dian)(dian)子電(dian)(dian)(dian)(dian)力變(bian)(bian)壓器(qi)主要是采(cai)用(yong)電(dian)(dian)(dian)(dian)力電(dian)(dian)(dian)(dian)子技(ji)術實現(xian)的(de)，其基本原(yuan)(yuan)理(li)為(wei)在(zai)原(yuan)(yuan)方(fang)將工(gong)(gong)(gong)頻信(xin)號通過電(dian)(dian)(dian)(dian)力電(dian)(dian)(dian)(dian)子電(dian)(dian)(dian)(dian)路轉化(hua)為(wei)高頻信(xin)號，即升(sheng)頻，然后通過中間(jian)(jian)高頻隔(ge)(ge)離變(bian)(bian)壓器(qi)耦合到副方(fang)，再還原(yuan)(yuan)成(cheng)工(gong)(gong)(gong)頻信(xin)號，即降頻。通過采(cai)用(yong)適(shi)當的(de)控(kong)制方(fang)案來(lai)控(kong)制電(dian)(dian)(dian)(dian)力電(dian)(dian)(dian)(dian)子裝置的(de)工(gong)(gong)(gong)作(zuo)，從而將一(yi)種頻率(lv)、電(dian)(dian)(dian)(dian)壓、波(bo)形的(de)電(dian)(dian)(dian)(dian)能變(bian)(bian)換為(wei)另(ling)一(yi)種頻率(lv)、電(dian)(dian)(dian)(dian)壓、波(bo)形的(de)電(dian)(dian)(dian)(dian)能。由于(yu)中間(jian)(jian)隔(ge)(ge)離變(bian)(bian)壓器(qi)的(de)體積(ji)取決于(yu)鐵芯材(cai)質的(de)飽和磁通密度以及鐵芯和繞組的(de)允許溫升(sheng)，而飽和磁通密度與(yu)工(gong)(gong)(gong)作(zuo)頻率(lv)成(cheng)反(fan)比，這(zhe)樣提(ti)(ti)高其工(gong)(gong)(gong)作(zuo)頻率(lv)就(jiu)可(ke)提(ti)(ti)高鐵芯的(de)利用(yong)率(lv)，從而減小變(bian)(bian)壓器(qi)的(de)體積(ji)并(bing)提(ti)(ti)高其整體效率(lv)。
二、提高電力變壓器抗短路能力的措施
變(bian)壓器(qi)的(de)(de)(de)安全、經濟(ji)、可靠(kao)運(yun)行(xing)與出(chu)力，取決于本(ben)身的(de)(de)(de)制造質量和運(yun)行(xing)環境以及檢修質量。本(ben)章(zhang)試圖回答(da)在變(bian)壓器(qi)運(yun)行(xing)維護(hu)過(guo)程(cheng)中，有效預防變(bian)壓器(qi)突發性故障的(de)(de)(de)措施。
電(dian)網經(jing)常(chang)由(you)于雷擊(ji)、繼電(dian)保(bao)護(hu)誤(wu)動或拒動等造(zao)成短路(lu)，短路(lu)電(dian)流的(de)(de)(de)(de)強大沖(chong)擊(ji)可(ke)能使變(bian)壓(ya)器(qi)(qi)受(shou)(shou)(shou)損，所(suo)(suo)以(yi)應從(cong)各方(fang)面(mian)努力提高變(bian)壓(ya)器(qi)(qi)的(de)(de)(de)(de)耐(nai)受(shou)(shou)(shou)短路(lu)能力。變(bian)壓(ya)器(qi)(qi)短路(lu)沖(chong)擊(ji)事故的(de)(de)(de)(de)統計結果表明(ming)，制造(zao)原因引(yin)起(qi)的(de)(de)(de)(de)占80%左右(you)，而運(yun)行(xing)、維護(hu)原因引(yin)起(qi)的(de)(de)(de)(de)僅(jin)占10%左右(you)。有關設計、制造(zao)方(fang)面(mian)的(de)(de)(de)(de)措施在第二章(zhang)已有論(lun)述，本章(zhang)著(zhu)重就運(yun)行(xing)維護(hu)過(guo)程中(zhong)(zhong)應采取的(de)(de)(de)(de)措施加(jia)以(yi)說明(ming)。運(yun)行(xing)維護(hu)過(guo)程中(zhong)(zhong)，一(yi)方(fang)面(mian)應盡量減少短路(lu)故障，從(cong)而減少變(bian)壓(ya)器(qi)(qi)所(suo)(suo)受(shou)(shou)(shou)沖(chong)擊(ji)的(de)(de)(de)(de)次數;另一(yi)方(fang)面(mian)應及時測試變(bian)壓(ya)器(qi)(qi)繞(rao)組的(de)(de)(de)(de)形變(bian)，防患于未然。
(一)規(gui)范設計(ji)(ji)，重視(shi)線(xian)(xian)圈(quan)(quan)(quan)制造(zao)的(de)(de)(de)(de)軸向壓(ya)(ya)(ya)緊工(gong)藝(yi)(yi)。制造(zao)廠(chang)家在(zai)(zai)設計(ji)(ji)時，除要(yao)(yao)考慮變壓(ya)(ya)(ya)器(qi)降低損耗，提高(gao)(gao)絕緣(yuan)水平(ping)外(wai)，還要(yao)(yao)考慮到(dao)提高(gao)(gao)變壓(ya)(ya)(ya)器(qi)的(de)(de)(de)(de)機械強度(du)和(he)抗短路故障能力。在(zai)(zai)制造(zao)工(gong)藝(yi)(yi)方面，由于很多變壓(ya)(ya)(ya)器(qi)都采(cai)用(yong)了絕緣(yuan)壓(ya)(ya)(ya)板，且高(gao)(gao)低壓(ya)(ya)(ya)線(xian)(xian)圈(quan)(quan)(quan)共用(yong)一個(ge)壓(ya)(ya)(ya)板，這種結構(gou)要(yao)(yao)求要(yao)(yao)有很高(gao)(gao)的(de)(de)(de)(de)制造(zao)工(gong)藝(yi)(yi)水平(ping)，應(ying)對墊(dian)塊進行密化(hua)處(chu)理，在(zai)(zai)線(xian)(xian)圈(quan)(quan)(quan)加工(gong)好后(hou)還要(yao)(yao)對單個(ge)線(xian)(xian)圈(quan)(quan)(quan)進行恒壓(ya)(ya)(ya)干燥,并測量出線(xian)(xian)圈(quan)(quan)(quan)壓(ya)(ya)(ya)縮后(hou)的(de)(de)(de)(de)高(gao)(gao)度(du);同一壓(ya)(ya)(ya)板的(de)(de)(de)(de)各個(ge)線(xian)(xian)圈(quan)(quan)(quan)經過上述工(gong)藝(yi)(yi)處(chu)理后(hou)，再調(diao)整到(dao)同一高(gao)(gao)度(du)，并在(zai)(zai)總裝(zhuang)時用(yong)油壓(ya)(ya)(ya)裝(zhuang)置對線(xian)(xian)圈(quan)(quan)(quan)施(shi)加規(gui)定(ding)的(de)(de)(de)(de)壓(ya)(ya)(ya)力，達到(dao)設計(ji)(ji)和(he)工(gong)藝(yi)(yi)要(yao)(yao)求的(de)(de)(de)(de)高(gao)(gao)度(du)。在(zai)(zai)總裝(zhuang)配中(zhong)，除了要(yao)(yao)注(zhu)意(yi)高(gao)(gao)壓(ya)(ya)(ya)線(xian)(xian)圈(quan)(quan)(quan)的(de)(de)(de)(de)壓(ya)(ya)(ya)緊情況外(wai)，還要(yao)(yao)特(te)別注(zhu)意(yi)低壓(ya)(ya)(ya)線(xian)(xian)圈(quan)(quan)(quan)壓(ya)(ya)(ya)緊情況的(de)(de)(de)(de)控制。
(二)對(dui)變壓(ya)器進行(xing)(xing)短路(lu)(lu)試(shi)驗，以防患于未(wei)然(ran)。大(da)型變壓(ya)器的(de)(de)運行(xing)(xing)可(ke)靠性，取決于其(qi)(qi)結構和制造工藝水平，其(qi)(qi)次是在運行(xing)(xing)過程(cheng)中(zhong)對(dui)設備進行(xing)(xing)各種(zhong)試(shi)驗，及時掌握設備的(de)(de)工況。要了解變壓(ya)器的(de)(de)機(ji)械穩定性，可(ke)通過承(cheng)受短路(lu)(lu)試(shi)驗，針對(dui)其(qi)(qi)薄弱(ruo)環節加以改進，以確(que)保對(dui)變壓(ya)器結構強度設計時做到心中(zhong)有數。
