諧振原(yuan)因 隨著(zhu)工業的(de)飛(fei)速(su)發展，非線性(xing)電(dian)力負荷大量(liang)增加，某些負荷不(bu)僅產生諧波，還引起(qi)供(gong)電(dian)電(dian)壓(ya)波動與閃變，甚至引起(qi)三相電(dian)壓(ya)不(bu)平衡(heng)。引起三(san)相(xiang)電壓不平衡的原因有(you)(you)多種，如：單相(xiang)接地(di)、斷線諧振等(deng)，運(yun)行管理(li)(li)人員只(zhi)有(you)(you)將其正確區分開來(lai)，才能(neng)快速處理(li)(li)。

一、 斷線(xian)(xian)故(gu)障 如果一相(xiang)(xiang)斷線(xian)(xian)但(dan)未接(jie)地，或斷路器、隔離開關一相(xiang)(xiang)未接(jie)通(tong)，電(dian)(dian)壓(ya)(ya)(ya)互感器保險絲熔斷均(jun)造成三相(xiang)(xiang)參數不對(dui)稱(cheng)。上一電(dian)(dian)壓(ya)(ya)(ya)等(deng)級(ji)線(xian)(xian)路一相(xiang)(xiang)斷線(xian)(xian)時，下一電(dian)(dian)壓(ya)(ya)(ya)等(deng)級(ji)的電(dian)(dian)壓(ya)(ya)(ya)表現為(wei)三個相(xiang)(xiang)電(dian)(dian)壓(ya)(ya)(ya)都降低(di)，其中一相(xiang)(xiang)較低(di)，另兩(liang)相(xiang)(xiang)較高但(dan)二(er)者電(dian)(dian)壓(ya)(ya)(ya)值接(jie)近。本級(ji)線(xian)(xian)路斷線(xian)(xian)時，斷線(xian)(xian)相(xiang)(xiang)電(dian)(dian)壓(ya)(ya)(ya)為(wei)零，未斷線(xian)(xian)相(xiang)(xiang)電(dian)(dian)壓(ya)(ya)(ya)仍(reng)為(wei)相(xiang)(xiang)電(dian)(dian)壓(ya)(ya)(ya)。

二、接(jie)(jie)地(di)故(gu)障(zhang) 當線路一相(xiang)斷線并(bing)單相(xiang)接(jie)(jie)地(di)時，雖(sui)引起三(san)相(xiang)電(dian)(dian)壓(ya)(ya)不平衡，但接(jie)(jie)地(di)后電(dian)(dian)壓(ya)(ya)值(zhi)不改變(bian)。單相(xiang)接(jie)(jie)地(di)分為(wei)金(jin)(jin)屬性(xing)接(jie)(jie)地(di)和非金(jin)(jin)屬性(xing)接(jie)(jie)地(di)兩種。金(jin)(jin)屬性(xing)接(jie)(jie)地(di)，故(gu)障(zhang)相(xiang)電(dian)(dian)壓(ya)(ya)為(wei)零(ling)或接(jie)(jie)近零(ling)，非故(gu)障(zhang)相(xiang)電(dian)(dian)壓(ya)(ya)升高1.732倍(bei)，且(qie)持久(jiu)不變(bian)；非金(jin)(jin)屬性(xing)接(jie)(jie)地(di)，接(jie)(jie)地(di)相(xiang)電(dian)(dian)壓(ya)(ya)不為(wei)零(ling)而是降低為(wei)某一數(shu)值(zhi)，其他兩相(xiang)升高不到1.732倍(bei)。

諧振引起三相電(dian)壓(ya)不平衡有兩種(zhong)

一種(zhong)是基頻諧(xie)振，特征類似(si)于單相(xiang)接地，即(ji)一相(xiang)電壓降低，另兩(liang)相(xiang)電壓升高，查(cha)找故障(zhang)原因時不易找到故障(zhang)點，此時可檢查(cha)特殊(shu)用(yong)戶，若不是接地原因，可能就(jiu)是諧(xie)振引起(qi)的。

另一種是(shi)分頻諧振或(huo)高(gao)(gao)頻諧振，特(te)征是(shi)三相電壓同時升(sheng)高(gao)(gao)。

另外，還要注意，空(kong)投(tou)母線(xian)切除(chu)部分(fen)線(xian)路或單相(xiang)接地故(gu)障消失時，如出現接地信號，且一相(xiang)、兩(liang)相(xiang)或三(san)相(xiang)電(dian)壓(ya)超過(guo)線(xian)電(dian)壓(ya)，電(dian)壓(ya)表(biao)指(zhi)針(zhen)打到(dao)頭，并同(tong)時緩慢(man)移動，或三(san)相(xiang)電(dian)壓(ya)輪流升高超過(guo)線(xian)電(dian)壓(ya)，遇到(dao)這種情(qing)況，一般均(jun)屬(shu)諧(xie)振引起。

三相(xiang)不平(ping)衡的危(wei)害(hai)和影響(xiang)

對變(bian)(bian)壓(ya)(ya)器(qi)的(de)危害。在生(sheng)產、生(sheng)活(huo)用電中(zhong)，三(san)相負(fu)載不(bu)平(ping)衡(heng)(heng)時，使變(bian)(bian)壓(ya)(ya)器(qi)處(chu)于(yu)不(bu)對稱運行(xing)狀態。造成(cheng)(cheng)變(bian)(bian)壓(ya)(ya)器(qi)的(de)損(sun)耗(hao)增大(da)(包括(kuo)空載損(sun)耗(hao)和負(fu)載損(sun)耗(hao))。根據變(bian)(bian)壓(ya)(ya)器(qi)運行(xing)規程規定，在運行(xing)中(zhong)的(de)變(bian)(bian)壓(ya)(ya)器(qi)中(zhong)性線電流不(bu)得超過(guo)變(bian)(bian)壓(ya)(ya)器(qi)低壓(ya)(ya)側額定電流的(de)25%。此外，三(san)相負(fu)載不(bu)平(ping)衡(heng)(heng)運行(xing)會(hui)(hui)造成(cheng)(cheng)變(bian)(bian)壓(ya)(ya)器(qi)零(ling)序電流過(guo)大(da)，局部(bu)金屬件升溫(wen)增高，甚至(zhi)會(hui)(hui)導致(zhi)變(bian)(bian)壓(ya)(ya)器(qi)燒毀。

對用電(dian)設(she)備的(de)(de)影(ying)響(xiang)。三相電(dian)壓不(bu)(bu)平(ping)(ping)衡(heng)(heng)的(de)(de)發生將導(dao)(dao)致(zhi)達(da)到數(shu)倍電(dian)流(liu)(liu)不(bu)(bu)平(ping)(ping)衡(heng)(heng)的(de)(de)發生。誘導(dao)(dao)電(dian)動機(ji)中逆扭矩增(zeng)(zeng)加，從而使電(dian)動機(ji)的(de)(de)溫度上(shang)升，效率下降，能(neng)耗增(zeng)(zeng)加，發生震動，輸出(chu)虧耗等影(ying)響(xiang)。各相之間的(de)(de)不(bu)(bu)平(ping)(ping)衡(heng)(heng)會導(dao)(dao)致(zhi)用電(dian)設(she)備使用壽命(ming)縮短，加速設(she)備部件更換頻率，增(zeng)(zeng)加設(she)備維護(hu)的(de)(de)成本。斷路器(qi)允許電(dian)流(liu)(liu)的(de)(de)余量減(jian)少，當負載(zai)變(bian)更或交替時容(rong)易發生超載(zai)、短路現(xian)象。中性(xing)線中流(liu)(liu)入過大的(de)(de)不(bu)(bu)平(ping)(ping)衡(heng)(heng)電(dian)流(liu)(liu)，導(dao)(dao)致(zhi)中性(xing)線增(zeng)(zeng)粗。

對線(xian)(xian)損(sun)的(de)(de)影響。三(san)相四線(xian)(xian)制結(jie)線(xian)(xian)方式，當三(san)相負(fu)荷(he)平(ping)衡(heng)時(shi)線(xian)(xian)損(sun)最(zui)小；當一相負(fu)荷(he)重(zhong)，兩(liang)相負(fu)荷(he)輕(qing)的(de)(de)情(qing)況(kuang)(kuang)下線(xian)(xian)損(sun)增(zeng)量較小；當一相負(fu)荷(he)重(zhong)，一相負(fu)荷(he)輕(qing)，而第三(san)相的(de)(de)負(fu)荷(he)為(wei)平(ping)均負(fu)荷(he)的(de)(de)情(qing)況(kuang)(kuang)下線(xian)(xian)損(sun)增(zeng)量較大(da)(da)；當一相負(fu)荷(he)輕(qing)，兩(liang)相負(fu)荷(he)重(zhong)的(de)(de)情(qing)況(kuang)(kuang)下線(xian)(xian)損(sun)增(zeng)量最(zui)大(da)(da)。當三(san)相負(fu)荷(he)不(bu)平(ping)衡(heng)時(shi)，無(wu)論何種負(fu)荷(he)分配情(qing)況(kuang)(kuang)，電流不(bu)平(ping)衡(heng)度越(yue)大(da)(da)，線(xian)(xian)損(sun)增(zeng)量也(ye)越(yue)大(da)(da)。

三相不平衡的危(wei)害及解決(jue)辦法

一(yi)、三相電壓(ya)或電流不平衡等因素產生的主要危害：

1、旋轉(zhuan)電(dian)機(ji)在不對(dui)稱狀(zhuang)態下運行，會(hui)(hui)(hui)使(shi)轉(zhuan)子產生(sheng)附(fu)加損耗及(ji)發(fa)熱，從而引起(qi)電(dian)機(ji)整(zheng)體(ti)或局部升溫，此(ci)外反向磁(ci)場(chang)產生(sheng)附(fu)加力矩(ju)會(hui)(hui)(hui)使(shi)電(dian)機(ji)出現(xian)振(zhen)動。對(dui)發(fa)電(dian)機(ji)而言，在定(ding)子中還(huan)會(hui)(hui)(hui)形成一(yi)系列高次諧(xie)波。

2、引起以負序(xu)分量(liang)為啟動元件的多種(zhong)保(bao)護(hu)發生誤動作，直接威脅電網運行。

3、不(bu)平衡電壓使硅整流設(she)備出(chu)現非特(te)征性(xing)諧(xie)波(bo)。

4、對發電機(ji)、變(bian)壓器而言，當三相(xiang)負荷(he)不(bu)平衡時，如(ru)控制最大相(xiang)電流為(wei)額定值，則其余兩相(xiang)就不(bu)能滿(man)載，因而設備利用率下降，反之如(ru)要維持額定容(rong)量，將會(hui)造成負荷(he)較大的一相(xiang)過(guo)負荷(he)，而且(qie)還(huan)會(hui)出現(xian)磁路不(bu)平衡致使(shi)波形畸變(bian)，設備附加損耗增加等。

二、由不對稱負荷引起的電網(wang)三(san)相電壓不平衡可以采取的解決辦法：

1、將不(bu)對稱(cheng)負荷(he)分散接在不(bu)同的供電點，以減(jian)少集中連接造(zao)成不(bu)平衡度嚴重超(chao)標的問題(ti)。

2、使(shi)用(yong)交叉換相等辦(ban)法使(shi)不對(dui)稱負荷合理分配到各相，盡量使(shi)其平衡化(hua)。

3、加大負荷接入點的短路容量，如改變(bian)網絡或提(ti)高(gao)供電電壓級別(bie)提(ti)高(gao)系統承受(shou)不(bu)平(ping)衡負荷的能力。

解決三相負荷不平衡的幾點措施(shi)

一、重(zhong)視低壓(ya)配電網的(de)(de)規(gui)劃(hua)工(gong)作，加強與地方(fang)政府規(gui)劃(hua)等部門的(de)(de)工(gong)作溝通，避(bi)免(mian)配電網建(jian)設(she)(she)無序(xu)，尤其(qi)避(bi)免(mian)在低壓(ya)配電網中出現頭痛(tong)醫(yi)頭，腳(jiao)痛(tong)醫(yi)腳(jiao)的(de)(de)局(ju)面，在配電網建(jian)設(she)(she)和改造當(dang)中對低壓(ya)臺區進行合理的(de)(de)分(fen)區分(fen)片供電，配變(bian)布點盡量(liang)接近負荷中心，避(bi)免(mian)扇(shan)型供電和迂回(hui)供電，配電網絡的(de)(de)建(jian)設(she)(she)要(yao)遵循“小容量(liang)、多(duo)布點、短(duan)半徑”的(de)(de)配變(bian)選址原則。

二、在對采(cai)用低壓(ya)三相(xiang)(xiang)(xiang)四線(xian)(xian)制供電的地區，要積極爭取對有條件的配電臺(tai)區采(cai)用3芯或者(zhe)4芯電纜或者(zhe)用低壓(ya)集束導線(xian)(xian)供電至(zhi)用戶(hu)端，這樣可以在低壓(ya)線(xian)(xian)路(lu)(lu)施工(gong)中最大程度的避(bi)免(mian)三相(xiang)(xiang)(xiang)負荷(he)出(chu)現偏相(xiang)(xiang)(xiang)的出(chu)現，同時要做好(hao)低壓(ya)裝表(biao)工(gong)作(zuo)，單相(xiang)(xiang)(xiang)電表(biao)在A、B、C三相(xiang)(xiang)(xiang)的分(fen)布盡(jin)量均勻，避(bi)免(mian)出(chu)現單相(xiang)(xiang)(xiang)電只(zhi)掛(gua)接在一相(xiang)(xiang)(xiang)或者(zhe)兩相(xiang)(xiang)(xiang)上，在線(xian)(xian)路(lu)(lu)末端造成(cheng)負荷(he)偏相(xiang)(xiang)(xiang)。

三(san)、在(zai)(zai)低壓(ya)(ya)配(pei)電(dian)(dian)(dian)(dian)網(wang)零線(xian)(xian)(xian)(xian)采用(yong)多點接(jie)地，降(jiang)低零線(xian)(xian)(xian)(xian)電(dian)(dian)(dian)(dian)能(neng)(neng)損(sun)耗。目前由(you)于三(san)相(xiang)負荷的(de)分布不平衡，導致了零線(xian)(xian)(xian)(xian)出(chu)現電(dian)(dian)(dian)(dian)流，按照規程要(yao)求零線(xian)(xian)(xian)(xian)電(dian)(dian)(dian)(dian)流不得超(chao)過(guo)相(xiang)線(xian)(xian)(xian)(xian)電(dian)(dian)(dian)(dian)流的(de)25%，在(zai)(zai)實際(ji)運行(xing)當(dang)中，由(you)于零線(xian)(xian)(xian)(xian)導線(xian)(xian)(xian)(xian)截面較細，電(dian)(dian)(dian)(dian)阻值較相(xiang)同長度的(de)相(xiang)線(xian)(xian)(xian)(xian)大(da)(da)，零線(xian)(xian)(xian)(xian)電(dian)(dian)(dian)(dian)流過(guo)大(da)(da)在(zai)(zai)導線(xian)(xian)(xian)(xian)上也會(hui)造(zao)成(cheng)一(yi)定比例的(de)電(dian)(dian)(dian)(dian)能(neng)(neng)損(sun)耗，所以建議在(zai)(zai)低壓(ya)(ya)配(pei)電(dian)(dian)(dian)(dian)網(wang)公(gong)用(yong)主零線(xian)(xian)(xian)(xian)采用(yong)多點接(jie)地，降(jiang)低零線(xian)(xian)(xian)(xian)電(dian)(dian)(dian)(dian)能(neng)(neng)損(sun)耗，避免(mian)因為(wei)負荷不平衡出(chu)現的(de)零線(xian)(xian)(xian)(xian)電(dian)(dian)(dian)(dian)流產生的(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)嚴重(zhong)危及人身安(an)全，而且(qie)通過(guo)多點接(jie)地，減低了因為(wei)發熱等(deng)原因造(zao)成(cheng)的(de)零線(xian)(xian)(xian)(xian)斷(duan)股斷(duan)線(xian)(xian)(xian)(xian)，使(shi)得用(yong)戶使(shi)用(yong)的(de)相(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)升(sheng)高(gao)，損(sun)壞家用(yong)電(dian)(dian)(dian)(dian)器(qi)。此(ci)外對于零線(xian)(xian)(xian)(xian)損(sun)耗問題，在(zai)(zai)目前一(yi)般低壓(ya)(ya)電(dian)(dian)(dian)(dian)纜中，零線(xian)(xian)(xian)(xian)的(de)截面為(wei)相(xiang)線(xian)(xian)(xian)(xian)的(de)1/2，電(dian)(dian)(dian)(dian)阻值大(da)(da)造(zao)成(cheng)了在(zai)(zai)三(san)相(xiang)負荷不平衡時，零線(xian)(xian)(xian)(xian)損(sun)耗加(jia)大(da)(da)，為(wei)此(ci)可以考慮到(dao)適當(dang)增大(da)(da)零線(xian)(xian)(xian)(xian)的(de)導線(xian)(xian)(xian)(xian)截面，例如采用(yong)五芯電(dian)(dian)(dian)(dian)纜，每(mei)相(xiang)用(yong)一(yi)個(ge)芯線(xian)(xian)(xian)(xian)而零線(xian)(xian)(xian)(xian)則用(yong)兩(liang)個(ge)芯線(xian)(xian)(xian)(xian)。

四、對單相(xiang)(xiang)(xiang)(xiang)負(fu)(fu)荷(he)占較大(da)比(bi)重的(de)(de)(de)(de)供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)地區(qu)積極推廣(guang)(guang)單相(xiang)(xiang)(xiang)(xiang)變(bian)供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)。目(mu)前在(zai)城市居民小區(qu)內大(da)部分的(de)(de)(de)(de)負(fu)(fu)載電(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)是(shi)采用(yong)單相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)，由于線路負(fu)(fu)荷(he)大(da)多為動(dong)力(li)、照(zhao)明混載，而電(dian)(dian)(dian)(dian)(dian)(dian)氣設(she)備(bei)使用(yong)的(de)(de)(de)(de)同(tong)(tong)時(shi)率較低(di)，這(zhe)樣使得低(di)壓(ya)(ya)三相(xiang)(xiang)(xiang)(xiang)負(fu)(fu)荷(he)在(zai)實際運(yun)行中的(de)(de)(de)(de)不平衡的(de)(de)(de)(de)幅度(du)更大(da)。另(ling)外從目(mu)前農村(cun)的(de)(de)(de)(de)生(sheng)活用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)情況看，在(zai)很多欠(qian)發(fa)(fa)達和(he)不發(fa)(fa)達地區(qu)的(de)(de)(de)(de)農村(cun)存在(zai)著人均用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)量小，居住(zhu)分散(san)，供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)線路長(chang)等問題，對這(zhe)些(xie)地區(qu)可以(yi)考慮到對于用(yong)戶較分散(san)、用(yong)電(dian)(dian)(dian)(dian)(dian)(dian)負(fu)(fu)荷(he)主要(yao)以(yi)照(zhao)明為主、負(fu)(fu)荷(he)不大(da)的(de)(de)(de)(de)情況，采用(yong)采用(yong)單相(xiang)(xiang)(xiang)(xiang)變(bian)壓(ya)(ya)器(qi)(qi)供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)方式，以(yi)達減(jian)少損耗和(he)建設(she)資金的(de)(de)(de)(de)目(mu)的(de)(de)(de)(de)。目(mu)前單相(xiang)(xiang)(xiang)(xiang)變(bian)壓(ya)(ya)器(qi)(qi)損耗比(bi)同(tong)(tong)容量三相(xiang)(xiang)(xiang)(xiang)變(bian)壓(ya)(ya)器(qi)(qi)減(jian)少15％～20％，有的(de)(de)(de)(de)廠家生(sheng)產的(de)(de)(de)(de)單相(xiang)(xiang)(xiang)(xiang)變(bian)在(zai)低(di)壓(ya)(ya)側可以(yi)引出380V和(he)220V兩種電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)等級(ji)，同(tong)(tong)時(shi)在(zai)一些(xie)地區(qu)也已開展利用(yong)多臺單相(xiang)(xiang)(xiang)(xiang)變(bian)向三相(xiang)(xiang)(xiang)(xiang)負(fu)(fu)荷(he)供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)試(shi)點，為使用(yong)單相(xiang)(xiang)(xiang)(xiang)變(bian)供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)提供(gong)了更加廣(guang)(guang)闊(kuo)的(de)(de)(de)(de)空(kong)間(jian)。

五、積極開展(zhan)(zhan)變(bian)(bian)壓(ya)器負(fu)荷(he)實際測(ce)(ce)(ce)(ce)量(liang)和(he)(he)調整(zheng)工(gong)作(zuo)(zuo)(zuo)。配(pei)(pei)變(bian)(bian)的(de)(de)(de)負(fu)荷(he)實測(ce)(ce)(ce)(ce)工(gong)作(zuo)(zuo)(zuo)看似簡(jian)單，但是(shi)在實際工(gong)作(zuo)(zuo)(zuo)中有幾點(dian)需要(yao)(yao)(yao)(yao)注意，一(yi)是(shi)實測(ce)(ce)(ce)(ce)工(gong)作(zuo)(zuo)(zuo)不(bu)能(neng)簡(jian)單地(di)測(ce)(ce)(ce)(ce)量(liang)配(pei)(pei)變(bian)(bian)低壓(ya)側Ａ、B、C三(san)相(xiang)引出(chu)線的(de)(de)(de)相(xiang)電流(liu)，而且要(yao)(yao)(yao)(yao)測(ce)(ce)(ce)(ce)量(liang)零(ling)線上的(de)(de)(de)電流(liu)，或(huo)者是(shi)測(ce)(ce)(ce)(ce)量(liang)零(ling)線（排）對(dui)地(di)電壓(ya)，從(cong)而可以(yi)(yi)更好(hao)地(di)比較出(chu)三(san)相(xiang)負(fu)荷(he)的(de)(de)(de)不(bu)平衡情況，二是(shi)實測(ce)(ce)(ce)(ce)工(gong)作(zuo)(zuo)(zuo)要(yao)(yao)(yao)(yao)向低壓(ya)配(pei)(pei)電線路(lu)的(de)(de)(de)末(mo)端(duan)(duan)和(he)(he)分(fen)支端(duan)(duan)延伸，這樣可以(yi)(yi)進一(yi)步發現不(bu)平衡負(fu)荷(he)的(de)(de)(de)出(chu)現地(di)點(dian)，確定調荷(he)點(dian)，三(san)是(shi)負(fu)荷(he)實測(ce)(ce)(ce)(ce)工(gong)作(zuo)(zuo)(zuo)既要(yao)(yao)(yao)(yao)定期開展(zhan)(zhan)也要(yao)(yao)(yao)(yao)不(bu)定期開展(zhan)(zhan)，尤其是(shi)在大的(de)(de)(de)用戶負(fu)荷(he)投(tou)運和(he)(he)在高峰負(fu)荷(he)期間，要(yao)(yao)(yao)(yao)增(zeng)加實測(ce)(ce)(ce)(ce)的(de)(de)(de)次數，通過及時的(de)(de)(de)測(ce)(ce)(ce)(ce)量(liang)配(pei)(pei)變(bian)(bian)低壓(ya)出(chu)線和(he)(he)接近用戶端(duan)(duan)的(de)(de)(de)低壓(ya)線路(lu)電流(liu)，便于準確地(di)了解設(she)備的(de)(de)(de)運行情況，做好(hao)負(fu)荷(he)的(de)(de)(de)均衡合理分(fen)配(pei)(pei)。

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