圖1

利用wangs定(ding)理(li)的(de)基本(ben)概念，在(zai)(zai)A相(xiang)(xiang)(xiang)與(yu)C相(xiang)(xiang)(xiang)之間接入一(yi)個適(shi)當的(de)電(dian)(dian)(dian)感(gan)L將(jiang)A相(xiang)(xiang)(xiang)有(you)功(gong)電(dian)(dian)(dian)流(liu)的(de)1/3轉(zhuan)(zhuan)移到(dao)(dao)C相(xiang)(xiang)(xiang)，這時電(dian)(dian)(dian)感(gan)L在(zai)(zai)A相(xiang)(xiang)(xiang)產(chan)(chan)生(sheng)(sheng)(sheng)的(de)感(gan)性(xing)無(wu)(wu)功(gong)電(dian)(dian)(dian)流(liu)恰(qia)好將(jiang)電(dian)(dian)(dian)阻(zu)在(zai)(zai)A相(xiang)(xiang)(xiang)產(chan)(chan)生(sheng)(sheng)(sheng)的(de)容(rong)性(xing)無(wu)(wu)功(gong)電(dian)(dian)(dian)流(liu)抵消(xiao)掉(diao)。在(zai)(zai)B相(xiang)(xiang)(xiang)與(yu)C相(xiang)(xiang)(xiang)之間接入一(yi)個適(shi)當的(de)電(dian)(dian)(dian)容(rong)C將(jiang)B相(xiang)(xiang)(xiang)有(you)功(gong)電(dian)(dian)(dian)流(liu)的(de)1/3轉(zhuan)(zhuan)移到(dao)(dao)C相(xiang)(xiang)(xiang)，這時電(dian)(dian)(dian)容(rong)C在(zai)(zai)B相(xiang)(xiang)(xiang)產(chan)(chan)生(sheng)(sheng)(sheng)的(de)容(rong)性(xing)無(wu)(wu)功(gong)電(dian)(dian)(dian)流(liu)恰(qia)好將(jiang)電(dian)(dian)(dian)阻(zu)在(zai)(zai)B相(xiang)(xiang)(xiang)產(chan)(chan)生(sheng)(sheng)(sheng)的(de)感(gan)性(xing)無(wu)(wu)功(gong)電(dian)(dian)(dian)流(liu)抵消(xiao)掉(diao)。電(dian)(dian)(dian)感(gan)L在(zai)(zai)C相(xiang)(xiang)(xiang)產(chan)(chan)生(sheng)(sheng)(sheng)的(de)感(gan)性(xing)無(wu)(wu)功(gong)電(dian)(dian)(dian)流(liu)恰(qia)好將(jiang)電(dian)(dian)(dian)容(rong)C在(zai)(zai)C相(xiang)(xiang)(xiang)產(chan)(chan)生(sheng)(sheng)(sheng)的(de)容(rong)性(xing)無(wu)(wu)功(gong)電(dian)(dian)(dian)流(liu)抵消(xiao)掉(diao)。這樣三相(xiang)(xiang)(xiang)電(dian)(dian)(dian)流(liu)完(wan)全平衡，并且三相(xiang)(xiang)(xiang)的(de)功(gong)率因(yin)數全等于1。

設有(you)一個電(dian)阻(zu)連接在(zai)A相(xiang)與零(ling)線之間，這是另一個典型(xing)的不平衡(heng)負荷，調(diao)整不平衡(heng)電(dian)流(liu)(liu)的目(mu)標(biao)就(jiu)是將(jiang)這個電(dian)阻(zu)的電(dian)流(liu)(liu)平均分配到(dao)三相(xiang)當中去(qu)，具體(ti)的方法如圖2所示：

圖2

在(zai)(zai)(zai)A相(xiang)(xiang)(xiang)與C相(xiang)(xiang)(xiang)之(zhi)(zhi)間接(jie)入一(yi)個適(shi)當的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)感(gan)(gan)L1將(jiang)(jiang)A相(xiang)(xiang)(xiang)有(you)功(gong)電(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)1/3轉移到C相(xiang)(xiang)(xiang)，在(zai)(zai)(zai)A相(xiang)(xiang)(xiang)與B相(xiang)(xiang)(xiang)之(zhi)(zhi)間接(jie)入一(yi)個適(shi)當的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)容C1將(jiang)(jiang)A相(xiang)(xiang)(xiang)有(you)功(gong)電(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)1/3轉移到B相(xiang)(xiang)(xiang)，這時電(dian)(dian)(dian)(dian)(dian)感(gan)(gan)L1在(zai)(zai)(zai)A相(xiang)(xiang)(xiang)產(chan)生(sheng)的(de)(de)(de)感(gan)(gan)性無(wu)功(gong)電(dian)(dian)(dian)(dian)(dian)流(liu)恰好將(jiang)(jiang)電(dian)(dian)(dian)(dian)(dian)容C1在(zai)(zai)(zai)A相(xiang)(xiang)(xiang)產(chan)生(sheng)的(de)(de)(de)容性無(wu)功(gong)電(dian)(dian)(dian)(dian)(dian)流(liu)抵消掉。在(zai)(zai)(zai)B相(xiang)(xiang)(xiang)與零線(xian)之(zhi)(zhi)間接(jie)入一(yi)個電(dian)(dian)(dian)(dian)(dian)感(gan)(gan)L2將(jiang)(jiang)電(dian)(dian)(dian)(dian)(dian)容C1在(zai)(zai)(zai)B相(xiang)(xiang)(xiang)產(chan)生(sheng)的(de)(de)(de)容性無(wu)功(gong)電(dian)(dian)(dian)(dian)(dian)流(liu)抵消掉。在(zai)(zai)(zai)C相(xiang)(xiang)(xiang)與零線(xian)之(zhi)(zhi)間接(jie)入一(yi)個電(dian)(dian)(dian)(dian)(dian)容C2將(jiang)(jiang)電(dian)(dian)(dian)(dian)(dian)感(gan)(gan)L1在(zai)(zai)(zai)C相(xiang)(xiang)(xiang)產(chan)生(sheng)的(de)(de)(de)感(gan)(gan)性無(wu)功(gong)電(dian)(dian)(dian)(dian)(dian)流(liu)抵消掉。于是三相(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)流(liu)完全平衡(heng)，并且三相(xiang)(xiang)(xiang)的(de)(de)(de)功(gong)率因數全等(deng)于1。

一(yi)個實際的(de)(de)(de)有功負荷(he)系統相當于在(zai)各(ge)相與(yu)(yu)相之(zhi)(zhi)間(jian)以及各(ge)相與(yu)(yu)零(ling)線(xian)之(zhi)(zhi)間(jian)分別接有不同的(de)(de)(de)電(dian)(dian)阻，在(zai)計算的(de)(de)(de)時(shi)候將各(ge)電(dian)(dian)阻分別單獨計算，然后(hou)按(an)疊(die)加(jia)原(yuan)理加(jia)在(zai)一(yi)起就可以確定各(ge)相與(yu)(yu)相之(zhi)(zhi)間(jian)以及各(ge)相與(yu)(yu)零(ling)線(xian)之(zhi)(zhi)間(jian)需要接入(ru)的(de)(de)(de)電(dian)(dian)感和電(dian)(dian)容(rong)數量。在(zai)疊(die)加(jia)的(de)(de)(de)過(guo)程中，如(ru)果某一(yi)路既有電(dian)(dian)感又有電(dian)(dian)容(rong)，則(ze)進(jin)行抵消處(chu)理，例如(ru)：計算得出A相與(yu)(yu)B相之(zhi)(zhi)間(jian)應(ying)接入(ru)15Kvar的(de)(de)(de)電(dian)(dian)感和7Kvar的(de)(de)(de)電(dian)(dian)容(rong)，則(ze)抵消處(chu)理之(zhi)(zhi)后(hou)僅剩(sheng)8Kvar的(de)(de)(de)電(dian)(dian)。

以(yi)(yi)上介紹的(de)(de)(de)方法需要使用電(dian)(dian)(dian)感(gan)(gan)，在(zai)實際(ji)的(de)(de)(de)無(wu)功(gong)補償(chang)裝置中使用電(dian)(dian)(dian)感(gan)(gan)是不(bu)適合的(de)(de)(de)，因為(wei)電(dian)(dian)(dian)感(gan)(gan)的(de)(de)(de)價格高、損耗大(da)、重量大(da)。所(suo)幸的(de)(de)(de)是，實際(ji)的(de)(de)(de)電(dian)(dian)(dian)力系(xi)統(tong)負荷(he)(he)總(zong)是存在(zai)電(dian)(dian)(dian)感(gan)(gan)的(de)(de)(de)，正(zheng)因為(wei)負荷(he)(he)存在(zai)電(dian)(dian)(dian)感(gan)(gan)，才(cai)需要進行(xing)無(wu)功(gong)補償(chang)，于是我(wo)們就可以(yi)(yi)利(li)用負荷(he)(he)的(de)(de)(de)電(dian)(dian)(dian)感(gan)(gan)來(lai)調整不(bu)平衡有功(gong)電(dian)(dian)(dian)流。理論計算與實踐經驗均表明：只要在(zai)各(ge)相與相之間(jian)以(yi)(yi)及各(ge)相與零線之間(jian)恰(qia)當的(de)(de)(de)接入不(bu)同數量的(de)(de)(de)電(dian)(dian)(dian)容(rong)器(qi)，就可以(yi)(yi)在(zai)無(wu)功(gong)補償(chang)的(de)(de)(de)同時調整不(bu)平衡有功(gong)電(dian)(dian)(dian)流。并且接入的(de)(de)(de)電(dian)(dian)(dian)容(rong)器(qi)總(zong)Kvar數與分相補償(chang)裝置將各(ge)相功(gong)率因數補償(chang)至1所(suo)需要的(de)(de)(de)總(zong)Kvar數相同。

由(you)于調整(zheng)(zheng)不(bu)平(ping)衡有(you)功(gong)(gong)電(dian)流(liu)(liu)(liu)(liu)需要利(li)用(yong)負(fu)荷(he)(he)的(de)(de)(de)電(dian)感，因(yin)此負(fu)荷(he)(he)的(de)(de)(de)功(gong)(gong)率(lv)因(yin)數越(yue)低意味著可(ke)以(yi)利(li)用(yong)的(de)(de)(de)電(dian)感越(yue)多，則調整(zheng)(zheng)不(bu)平(ping)衡有(you)功(gong)(gong)電(dian)流(liu)(liu)(liu)(liu)的(de)(de)(de)能(neng)力就越(yue)強。計算表明：如果負(fu)荷(he)(he)的(de)(de)(de)功(gong)(gong)率(lv)因(yin)數為(wei)0.7，那么最(zui)(zui)大相(xiang)(xiang)電(dian)流(liu)(liu)(liu)(liu)是(shi)(shi)最(zui)(zui)小(xiao)(xiao)相(xiang)(xiang)電(dian)流(liu)(liu)(liu)(liu)2倍的(de)(de)(de)情況可(ke)以(yi)調整(zheng)(zheng)到平(ping)衡。如果負(fu)荷(he)(he)的(de)(de)(de)功(gong)(gong)率(lv)因(yin)數為(wei)0.85，那么最(zui)(zui)大相(xiang)(xiang)電(dian)流(liu)(liu)(liu)(liu)是(shi)(shi)最(zui)(zui)小(xiao)(xiao)相(xiang)(xiang)電(dian)流(liu)(liu)(liu)(liu)1.5倍的(de)(de)(de)情況可(ke)以(yi)調整(zheng)(zheng)平(ping)衡。如果負(fu)荷(he)(he)的(de)(de)(de)功(gong)(gong)率(lv)因(yin)數為(wei)1，那么意味著沒有(you)可(ke)以(yi)利(li)用(yong)的(de)(de)(de)電(dian)感，因(yin)此無法進行(xing)不(bu)平(ping)衡調整(zheng)(zheng)。

下面舉(ju)一例說明如何連接電容器來達到即補償功率因(yin)數又調整不平衡電流的目的。

設有(you)一用電系統如圖3所示(shi)：

圖3

這(zhe)(zhe)是一個功(gong)率因(yin)(yin)數(shu)很低(di)且三(san)相(xiang)(xiang)嚴重不平衡(heng)(heng)的例子(zi)，三(san)相(xiang)(xiang)的功(gong)率因(yin)(yin)數(shu)均為0.707。C相(xiang)(xiang)電流(liu)比A相(xiang)(xiang)電流(liu)大(da)一倍。在這(zhe)(zhe)個例子(zi)里，由(you)于負荷含有足夠多的電感(gan)，因(yin)(yin)此只(zhi)要(yao)恰(qia)當地投入電容(rong)器，就可以使三(san)相(xiang)(xiang)的功(gong)率因(yin)(yin)數(shu)均為1，并且三(san)相(xiang)(xiang)電流(liu)平衡(heng)(heng)。電容(rong)器的接法(fa)如圖4所示：

圖4

圖5

圖6

圖7

圖8