你知道電容器回路串聯電抗器的意義在哪嗎？

       電容器在感性負載處并聯連接也就是所謂的串聯電抗器。這是(shi)電(dian)(dian)(dian)(dian)(dian)網(wang)中最(zui)常用的(de)無功補(bu)償方法。它也是(shi)提(ti)高功率(lv)因數，改善電(dian)(dian)(dian)(dian)(dian)壓(ya)質(zhi)量和(he)能量損失的(de)有效措施。為了滿足電(dian)(dian)(dian)(dian)(dian)網(wang)和(he)電(dian)(dian)(dian)(dian)(dian)氣設(she)備(bei)的(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)質(zhi)量要求(qiu)，根(gen)據電(dian)(dian)(dian)(dian)(dian)抗(kang)負載的(de)變化切換適量的(de)電(dian)(dian)(dian)(dian)(dian)容。但是(shi)，當國(guo)有企業投入運營時，它們將產(chan)生(sheng)大規模，高頻率(lv)的(de)收(shou)盤(pan)激增。如果電(dian)(dian)(dian)(dian)(dian)容器(qi)連接到電(dian)(dian)(dian)(dian)(dian)網(wang)以存(cun)儲諧波污染，由于電(dian)(dian)(dian)(dian)(dian)容器(qi)的(de)電(dian)(dian)(dian)(dian)(dian)容阻抗(kang)特性，諧波電(dian)(dian)(dian)(dian)(dian)流將被放大。危(wei)險(xian)的(de)過電(dian)(dian)(dian)(dian)(dian)流會對(dui)電(dian)(dian)(dian)(dian)(dian)氣設(she)備(bei)產(chan)生(sheng)不利影(ying)響(xiang)，嚴重時會對(dui)設(she)備(bei)造(zao)成損壞。

為了避免諧波對補償裝置的影響，電容器回路采用串聯電抗器，既不影響電容器的(de)無功(gong)補(bu)償(chang)，又能抑制(zhi)高次諧(xie)波(bo)。因此，補(bu)償(chang)電容電路中的(de)串聯(lian)電抗器具有抑制(zhi)高次諧(xie)波(bo)和限制(zhi)合閘涌流的(de)作(zuo)用。

然而，操作實踐表明(ming)，在電(dian)(dian)容(rong)器(qi)(qi)(qi)(qi)回路的串聯電(dian)(dian)抗器(qi)(qi)(qi)(qi)之后，當無功功率補償裝置投(tou)入運行時(shi)可能會發(fa)生過(guo)電(dian)(dian)壓，并且可以(yi)減小(xiao)電(dian)(dian)容(rong)器(qi)(qi)(qi)(qi)的端子電(dian)(dian)壓和(he)使用壽命。分析(xi)了串聯電(dian)(dian)抗器(qi)(qi)(qi)(qi)在電(dian)(dian)容(rong)器(qi)(qi)(qi)(qi)回路中的優缺(que)點。

1電(dian)容器(qi)環路串聯電(dian)抗器(qi)的優點(dian)

（1）限制合閘涌流

無功補(bu)償電(dian)(dian)(dian)容器(qi)投切時，往往會(hui)發生(sheng)沖(chong)擊合閘涌流(liu)。這(zhe)是(shi)因為(wei)電(dian)(dian)(dian)容器(qi)第一次不充電(dian)(dian)(dian)，流(liu)入電(dian)(dian)(dian)容器(qi)的(de)(de)電(dian)(dian)(dian)流(liu)僅(jin)受電(dian)(dian)(dian)路(lu)阻(zu)抗的(de)(de)限制。由(you)于電(dian)(dian)(dian)路(lu)接近(jin)短路(lu)狀態，電(dian)(dian)(dian)路(lu)阻(zu)抗很小，會(hui)產生(sheng)很大的(de)(de)浪涌電(dian)(dian)(dian)流(liu)。

隨著總線短路(lu)容(rong)器(qi)的(de)增加或電抗(kang)器(qi)電感(gan)對電容(rong)電容(rong)電抗(kang)的(de)百分(fen)比(bi)的(de)增加，K值(zhi)大(da)大(da)降低(di)，串(chuan)聯電抗(kang)器(qi)可限制串(chuan)聯電抗(kang)器(qi)后(hou)的(de)合閘(zha)涌流(liu)。

（2）抑制高次諧波

當補償(chang)電(dian)(dian)(dian)(dian)容(rong)(rong)接入點處的電(dian)(dian)(dian)(dian)網中存在諧(xie)波(bo)(bo)(bo)時(shi)(shi)，電(dian)(dian)(dian)(dian)容(rong)(rong)器對n次諧(xie)波(bo)(bo)(bo)的容(rong)(rong)抗(kang)降低到(dao)(dao)Xc / n，并且系統電(dian)(dian)(dian)(dian)感對n次諧(xie)波(bo)(bo)(bo)的電(dian)(dian)(dian)(dian)感升(sheng)高到(dao)(dao)nXs。當網格中存在n個諧(xie)波(bo)(bo)(bo)電(dian)(dian)(dian)(dian)流(liu)時(shi)(shi)，如果nXs = Xc / n，則發生(sheng)n次諧(xie)波(bo)(bo)(bo)共振現象(xiang)。在疊加n次諧(xie)波(bo)(bo)(bo)電(dian)(dian)(dian)(dian)流(liu)和基(ji)波(bo)(bo)(bo)電(dian)(dian)(dian)(dian)流(liu)之后，流(liu)過(guo)電(dian)(dian)(dian)(dian)容(rong)(rong)器的電(dian)(dian)(dian)(dian)流(liu)突然增加，其過(guo)電(dian)(dian)(dian)(dian)流(liu)將(jiang)危及(ji)電(dian)(dian)(dian)(dian)容(rong)(rong)器的安全性。此時(shi)(shi)，由系統阻(zu)抗(kang)上的諧(xie)波(bo)(bo)(bo)電(dian)(dian)(dian)(dian)流(liu)產生(sheng)的諧(xie)波(bo)(bo)(bo)電(dian)(dian)(dian)(dian)壓(ya)與原始電(dian)(dian)(dian)(dian)壓(ya)疊加，產生(sheng)過(guo)電(dian)(dian)(dian)(dian)壓(ya)，這(zhe)將(jiang)影(ying)響電(dian)(dian)(dian)(dian)容(rong)(rong)器的壽命。

對電(dian)容(rong)器回路(lu)中的串(chuan)聯電(dian)抗器進行(xing)補償后(hou)，可以有效地避免(mian)諧振區，抑(yi)制高次諧波。

當電網存(cun)在高次(ci)諧(xie)波時，當n>n0時，阻抗(kang)是感性的，對(dui)等(deng)效網絡具(ju)有明顯的諧(xie)波抑制作用(yong)。

操作實踐(jian)表明，如果串(chuan)聯電(dian)(dian)抗器的(de)(de)主要(yao)目的(de)(de)是限制浪涌電(dian)(dian)流，應選擇(ze)(ze)電(dian)(dian)容(rong)為0.2-2％的(de)(de)電(dian)(dian)抗器;如果要(yao)抑(yi)制高次諧波，應選擇(ze)(ze)電(dian)(dian)容(rong)為6％的(de)(de)電(dian)(dian)抗器。電(dian)(dian)抗器應串(chuan)聯在電(dian)(dian)容(rong)器組的(de)(de)電(dian)(dian)源側，這樣可以(yi)更好地(di)抑(yi)制諧波效應。

2系列反應器的缺點

（1）電(dian)容器接(jie)通和斷(duan)開(kai)時發生過電(dian)壓。

在(zai)(zai)并聯電(dian)(dian)(dian)(dian)(dian)容器(qi)(qi)組的電(dian)(dian)(dian)(dian)(dian)路中串聯連接(jie)的電(dian)(dian)(dian)(dian)(dian)抗器(qi)(qi)，尤其(qi)是線(xian)性電(dian)(dian)(dian)(dian)(dian)抗器(qi)(qi)或高(gao)質量電(dian)(dian)(dian)(dian)(dian)抗器(qi)(qi)，在(zai)(zai)斷(duan)路器(qi)(qi)切(qie)換(huan)電(dian)(dian)(dian)(dian)(dian)容器(qi)(qi)時(shi)產生過電(dian)(dian)(dian)(dian)(dian)壓(ya)，因(yin)為斷(duan)路器(qi)(qi)在(zai)(zai)閉(bi)合時(shi)反彈(dan)并分開。在(zai)(zai)門處重(zhong)新點(dian)火將增加過電(dian)(dian)(dian)(dian)(dian)壓(ya)的概率(lv)和倍(bei)數。因(yin)此，切(qie)斷(duan)電(dian)(dian)(dian)(dian)(dian)容器(qi)(qi)的斷(duan)路器(qi)(qi)應(ying)選擇(ze)性能高(gao)，無浪涌電(dian)(dian)(dian)(dian)(dian)流且(qie)無需(xu)重(zhong)新點(dian)火的開關，以(yi)避免在(zai)(zai)運行過程中產生過電(dian)(dian)(dian)(dian)(dian)壓(ya)。

（2）電容器端電壓升高

電(dian)(dian)容(rong)(rong)器串聯電(dian)(dian)抗器運(yun)行(xing)后，電(dian)(dian)容(rong)(rong)器端(duan)電(dian)(dian)壓(ya)高于母線電(dian)(dian)壓(ya)，電(dian)(dian)容(rong)(rong)器端(duan)電(dian)(dian)壓(ya)由(you)下列公(gong)式確定(ding)。

Uc=Ue＆middot;Xc/（Xc-XL）

其中Ue是(shi)電容器(qi)總線的額(e)定電壓。

當(dang)(dang)反應器(qi)XL大于(yu)電(dian)(dian)容(rong)(rong)器(qi)XC時，電(dian)(dian)容(rong)(rong)器(qi)端(duan)電(dian)(dian)壓升高。如果XL大于(yu)電(dian)(dian)容(rong)(rong)器(qi)XC，則電(dian)(dian)容(rong)(rong)器(qi)的端(duan)電(dian)(dian)壓升高更多。例如，當(dang)(dang)xl=6%xc時，電(dian)(dian)容(rong)(rong)器(qi)端(duan)電(dian)(dian)壓降(jiang)增加(jia)(jia)6.4%，當(dang)(dang)xl=13%xc時，電(dian)(dian)容(rong)(rong)器(qi)端(duan)電(dian)(dian)壓降(jiang)增加(jia)(jia)11.5%。

另外，對于具有非接地中性點的電容器組，由于三相的實際電容不能完全平衡，使得某些電容器端面的電壓明顯增加。串聯電抗器后(hou)三相電(dian)容的不平(ping)衡(heng)現象(xiang)更(geng)加(jia)嚴(yan)重.結果表明，電(dian)容端電(dian)壓(ya)的增加(jia)值大于三相電(dian)容平(ping)衡(heng)值。

增加電(dian)(dian)(dian)(dian)容器端子的(de)(de)電(dian)(dian)(dian)(dian)壓將(jiang)危(wei)及(ji)安全(quan)操(cao)作，影響(xiang)使用(yong)壽命，甚至引起鼓脹和爆炸(zha)等(deng)事故。為此，電(dian)(dian)(dian)(dian)容器電(dian)(dian)(dian)(dian)路(lu)中的(de)(de)串聯電(dian)(dian)(dian)(dian)抗器還應考慮三(san)相電(dian)(dian)(dian)(dian)容器的(de)(de)平衡，以避免(mian)較(jiao)大(da)的(de)(de)端電(dian)(dian)(dian)(dian)壓上升。