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諧(xie)波(bo)電(dian)流對計量的影(ying)響(xiang)

發布時間:2017-09-28 瀏覽:1093

  近(jin)年來隨著國(guo)家(jia)產業政策(ce)的(de)(de)(de)(de)(de)(de)調(diao)整和節(jie)能(neng)環(huan)保工作的(de)(de)(de)(de)(de)(de)不斷推進,高(gao)耗能(neng)和對環(huan)境、電(dian)(dian)網污染較為(wei)嚴重(zhong)的(de)(de)(de)(de)(de)(de)企(qi)業,在沿海(hai)和中東部(bu)(bu)地(di)區已逐步關停或轉產,一些如30萬噸以下的(de)(de)(de)(de)(de)(de)小型煉鋼、鐵合金(jin)(jin)、大型起重(zhong)吊裝、牽引等設(she)備的(de)(de)(de)(de)(de)(de)電(dian)(dian)力電(dian)(dian)子(zi)裝置帶來的(de)(de)(de)(de)(de)(de)諧(xie)波問題,對電(dian)(dian)力系統安(an)全、穩定、經(jing)濟(ji)運行(xing)構成潛在威脅,給(gei)周圍電(dian)(dian)網運行(xing)帶來極大影響。按國(guo)家(jia)對諧(xie)波的(de)(de)(de)(de)(de)(de)管理(li)(li)要求,企(qi)業進行(xing)諧(xie)波治理(li)(li)需投(tou)入數(shu)十(shi)至數(shu)百萬的(de)(de)(de)(de)(de)(de)資金(jin)(jin),使(shi)得一些中小企(qi)業借(jie)西部(bu)(bu)大開發(fa)(fa)招商引資時機,紛紛遷(qian)往(wang)西部(bu)(bu)邊遠(yuan)經(jing)濟(ji)欠發(fa)(fa)達省區,利用西部(bu)(bu)能(neng)源的(de)(de)(de)(de)(de)(de)相對充裕和對諧(xie)波管理(li)(li)的(de)(de)(de)(de)(de)(de)滯后,而謀(mou)求“發(fa)(fa)展”,而使(shi)西部(bu)(bu)電(dian)(dian)網變的(de)(de)(de)(de)(de)(de)更加脆弱。諧(xie)波是電(dian)(dian)網的(de)(de)(de)(de)(de)(de)一大公害。

  電(dian)(dian)(dian)(dian)(dian)力系統中(zhong)的(de)(de)主(zhu)要諧(xie)波(bo)(bo)源(yuan)可(ke)分為(wei)兩類:一是含(han)半導體(ti)的(de)(de)非(fei)線性元件(jian),如各(ge)種整(zheng)流(liu)設(she)(she)備(bei)(bei)(bei)(bei)、變(bian)流(liu)器(qi)、交直流(liu)換流(liu)設(she)(she)備(bei)(bei)(bei)(bei)、變(bian)頻器(qi)等(deng)節(jie)能和(he)控制用的(de)(de)電(dian)(dian)(dian)(dian)(dian)力電(dian)(dian)(dian)(dian)(dian)子設(she)(she)備(bei)(bei)(bei)(bei);二是含(han)電(dian)(dian)(dian)(dian)(dian)弧和(he)鐵(tie)磁(ci)非(fei)線性設(she)(she)備(bei)(bei)(bei)(bei)的(de)(de)諧(xie)波(bo)(bo)源(yuan),如交流(liu)電(dian)(dian)(dian)(dian)(dian)弧爐及鐵(tie)磁(ci)諧(xie)振設(she)(she)備(bei)(bei)(bei)(bei)等(deng)。隨(sui)著硅整(zheng)流(liu)、電(dian)(dian)(dian)(dian)(dian)弧爐及可(ke)控硅換流(liu)設(she)(she)備(bei)(bei)(bei)(bei)的(de)(de)廣(guang)泛使(shi)用和(he)各(ge)種非(fei)線性負荷的(de)(de)增加,當正弦基(ji)波(bo)(bo)電(dian)(dian)(dian)(dian)(dian)壓(ya)施(shi)加于(yu)非(fei)線性設(she)(she)備(bei)(bei)(bei)(bei)時(shi),設(she)(she)備(bei)(bei)(bei)(bei)吸收的(de)(de)電(dian)(dian)(dian)(dian)(dian)流(liu)與施(shi)加的(de)(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)波(bo)(bo)形不同,電(dian)(dian)(dian)(dian)(dian)流(liu)因而發生了(le)畸變(bian),諧(xie)波(bo)(bo)電(dian)(dian)(dian)(dian)(dian)流(liu)注入到電(dian)(dian)(dian)(dian)(dian)網中(zhong),造成(cheng)電(dian)(dian)(dian)(dian)(dian)壓(ya)正弦波(bo)(bo)形畸變(bian),這些設(she)(she)備(bei)(bei)(bei)(bei)就成(cheng)了(le)電(dian)(dian)(dian)(dian)(dian)力系統的(de)(de)諧(xie)波(bo)(bo)源(yuan)。

  信(xin)息來源://tede.cn

  1 對諧波的(de)限值(zhi)和對計量的(de)要(yao)求

  GB/T 14549《電(dian)能質量(liang)公(gong)用(yong)電(dian)網諧(xie)波(bo)》中明確給出了公(gong)用(yong)電(dian)網諧(xie)波(bo)電(dian)壓的***值,見表1。諧(xie)波(bo)電(dian)壓的***值參見GB/T 14549。

  


  信(xin)息(xi)來自:www.tede.cn

  表1 公用電(dian)網諧波電(dian)壓(相電(dian)壓)

  


  信息請(qing)登陸:輸配電設備網

  表2 電(dian)能表確定基本誤差時(shi)的條件要求(qiu)

  工頻整數倍數的(de)諧波波形(xing),對電能計量(liang)裝置的(de)準確(que)計量(liang)產生(sheng)了較大的(de)影響(xiang)。

  DL/T 614-1997《多功能(neng)電(dian)能(neng)表》對諧波影響的(de)要求:分別將含有10%的(de)3次、5次諧波干(gan)擾(rao)源(yuan)施加在多功能(neng)電(dian)能(neng)表電(dian)壓(ya)線路,***大需量值誤差(cha)的(de)改變量應不超過0.2%,程序不應紊亂,內存數(shu)據不應丟失(shi)(測量單元為額定(ding)工(gong)作狀態)。

  2 計量電能表受(shou)諧波影(ying)響的誤差

  2.1 感應式(shi)電能表受諧波的影響

  感應(ying)式電(dian)(dian)能表是(shi)(shi)靠電(dian)(dian)磁(ci)感應(ying)來產生(sheng)轉動(dong)力矩(ju)的(de)(de)(de),電(dian)(dian)能表工(gong)作(zuo)(zuo)時,電(dian)(dian)壓線圈(quan)(quan)(quan)(quan)的(de)(de)(de)電(dian)(dian)流(liu)(liu)所(suo)產生(sheng)的(de)(de)(de)磁(ci)通(tong)分為兩部(bu)分,一(yi)部(bu)分是(shi)(shi)穿(chuan)過(guo)(guo)(guo)鋁(lv)盤(pan)(pan)并(bing)由(you)(you)(you)回(hui)(hui)磁(ci)板構(gou)成(cheng)回(hui)(hui)路(lu)的(de)(de)(de)工(gong)作(zuo)(zuo)磁(ci)通(tong),另一(yi)部(bu)分是(shi)(shi)不(bu)穿(chuan)過(guo)(guo)(guo)鋁(lv)盤(pan)(pan)而由(you)(you)(you)左右(you)鐵(tie)軛構(gou)成(cheng)回(hui)(hui)路(lu)的(de)(de)(de)非工(gong)作(zuo)(zuo)磁(ci)通(tong)。而電(dian)(dian)流(liu)(liu)線圈(quan)(quan)(quan)(quan)所(suo)產生(sheng)的(de)(de)(de)磁(ci)通(tong),兩次穿(chuan)過(guo)(guo)(guo)鋁(lv)盤(pan)(pan),并(bing)通(tong)過(guo)(guo)(guo)電(dian)(dian)流(liu)(liu)元件(jian)鐵(tie)芯構(gou)成(cheng)回(hui)(hui)路(lu)。由(you)(you)(you)于電(dian)(dian)壓線圈(quan)(quan)(quan)(quan)和電(dian)(dian)流(liu)(liu)線圈(quan)(quan)(quan)(quan)產生(sheng)的(de)(de)(de)交變磁(ci)通(tong),在不(bu)同位置(zhi)穿(chuan)過(guo)(guo)(guo)鋁(lv)盤(pan)(pan),并(bing)在鋁(lv)盤(pan)(pan)的(de)(de)(de)不(bu)同位置(zhi)感應(ying)出電(dian)(dian)流(liu)(liu)(渦流(liu)(liu)),此渦流(liu)(liu)與磁(ci)場相互作(zuo)(zuo)用便(bian)產生(sheng)推動(dong)鋁(lv)盤(pan)(pan)轉動(dong)的(de)(de)(de)力矩(ju),鋁(lv)盤(pan)(pan)轉動(dong)與負載有功功率(lv)成(cheng)正比。

  電能(neng)表產生(sheng)誤差(cha)的原因很(hen)多,與系統高次諧波相關的體現為兩(liang)個方(fang)面:

  ·電磁(ci)感應式電能表的設計只按基波考(kao)慮;

  信息來源://tede.cn

  ·由(you)諧波(bo)和基波(bo)疊(die)加而成的(de)電(dian)壓、電(dian)流波(bo)形發生畸變。

  2.2 電(dian)子(zi)式電(dian)能表(biao)受諧波的(de)影響

  電子式電能表的工作過程如圖(tu)1。

  

信息請登(deng)陸:輸配電設(she)備網


  圖1 電子式電能表的(de)工(gong)作原(yuan)理(li)

  全電(dian)子(zi)式電(dian)能表(biao)產(chan)生誤差(cha)的因素,完全消(xiao)除了感(gan)應(ying)式電(dian)能表(biao)的機械轉動、元件(jian)磨損、傾斜度等的影響,但(dan)對其運行環(huan)境、元器件(jian)質(zhi)量(liang)、電(dian)能質(zhi)量(liang)、諧波頻率的影響產(chan)生的誤差(cha)也是多方(fang)面的。

  3 諧波工況(kuang)下的電能計量(liang)

  3.1 諧(xie)波工況下的(de)準確計(ji)量要求

  隨著電力市場改革的推進,電能(neng)作(zuo)為一種商品已經全面走向市場化(hua),電能(neng)表能(neng)否在(zai)各種工業狀況下準確計量,逐漸受到了供(gong)用(yong)電雙方的重視(shi)。

  隨著大(da)功率非(fei)線性(xing)負荷的迅速(su)增加(jia),使(shi)得供電(dian)系(xi)統中電(dian)壓、電(dian)流波形發生畸(ji)變,對電(dian)網造成了嚴重(zhong)的影響,并使(shi)電(dian)能表計量的誤(wu)差(cha)急劇增大(da)。

  在諧波工況下(xia)是否依然(ran)能夠準確計(ji)量,成為對(dui)三相多(duo)功能電能表的必然(ran)要求。

  3.2 諧波工況(kuang)下的計量準確性

  在實際(ji)的計量(liang)中(zhong),電力用戶可(ke)以分為(wei)兩類(lei),即產生諧(xie)(xie)波的諧(xie)(xie)波源用戶和(he)不產生諧(xie)(xie)波的諧(xie)(xie)波受害(hai)者(zhe)用戶。

  作(zuo)為(wei)諧波(bo)源的(de)用戶(hu),一(yi)方面產生了(le)諧波(bo)功率,對(dui)電(dian)網(wang)造成了(le)污染(ran),另一(yi)方面,計(ji)費總電(dian)能(neng)(neng)為(wei)基(ji)波(bo)電(dian)能(neng)(neng)減去產生的(de)諧波(bo)電(dian)能(neng)(neng)。作(zuo)為(wei)正常使(shi)用的(de)諧波(bo)受害者用戶(hu),一(yi)方面設備(bei)深(shen)受諧波(bo)危害,另一(yi)方面,計(ji)費總電(dian)能(neng)(neng)為(wei)基(ji)波(bo)電(dian)能(neng)(neng)加上吸收的(de)諧波(bo)電(dian)能(neng)(neng)。 信息來自:輸配電(dian)設備(bei)網(wang)

  4 諧波測量功能(neng)的實現

  4.1 總電能脈沖輸出框圖

  總電(dian)能脈(mo)沖輸出框圖見(jian)圖2。

  


  信息來(lai)源://www.tede.cn

  圖2 總(zong)電能脈(mo)沖輸出(chu)框圖

  4.2 諧波電能脈沖輸(shu)出框圖

  諧波電能脈(mo)沖輸出(chu)框圖見圖3。

  圖3 諧波(bo)電能脈沖輸出框圖

  


  信息來源://www.tede.cn

  5 多功能電能表諧波計量

  全電(dian)子式(shi)電(dian)能(neng)表通(tong)過不斷演變,由原來的(de)(de)單(dan)片機(ji)技術發展到(dao)采用(yong)大(da)容量CPU、漢字點陣字庫,以及A/D+DSP+CPU形式(shi),不斷完善(shan)獨立、固化的(de)(de)計量專(zhuan)用(yong)芯片,并逐步(bu)拓展大(da)量程、寬量限電(dian)能(neng)表,滿足不同(tong)方式(shi)的(de)(de)計量需要;現以諧(xie)波(bo)(bo)多功(gong)能(neng)表為例,介紹(shao)諧(xie)波(bo)(bo)計量的(de)(de)特(te)點。

  5.1 諧波(bo)計量電能表的主要特點

  ·帶有諧波(bo)功(gong)率測量并能指示諧波(bo)潮流方向;

  ·具有測(ce)量(liang)與基(ji)波(bo)方向一致/相反的(de)諧波(bo)有功電能,基(ji)波(bo)有功電能、基(ji)波(bo)無功電能、實(shi)際消耗電能、總電能的(de)功能;

  ·時(shi)鐘自帶溫(wen)度(du)補償,在(zai)停電時(shi)同樣能進行(xing)溫(wen)度(du)補償,在(zai)-40~+70℃范圍內,時(shi)鐘精度(du)優(you)于0.5s/d;

  ·具(ju)有(you)備用(yong)時段功能(neng);

  ·RS485能實現波特率自(zi)適應功能;

  ·能實(shi)現(xian)自動校表(biao)。

  5.2 諧(xie)波計量測試情(qing)況

  電(dian)(dian)能(neng)(neng)表(biao)在諧波(bo)工況下(xia),當諧波(bo)電(dian)(dian)能(neng)(neng)方(fang)向與(yu)基(ji)波(bo)電(dian)(dian)能(neng)(neng)相反(fan)時,基(ji)波(bo)電(dian)(dian)能(neng)(neng)與(yu)諧波(bo)電(dian)(dian)能(neng)(neng)的代數和與(yu)標(biao)準表(biao)的總(zong)電(dian)(dian)能(neng)(neng)一致(zhi),而(er)消耗電(dian)(dian)能(neng)(neng)等于(yu)基(ji)波(bo)電(dian)(dian)能(neng)(neng)與(yu)諧波(bo)電(dian)(dian)能(neng)(neng)的絕對值之和。

  當(dang)諧(xie)波(bo)電能(neng)方向與基波(bo)電能(neng)相同(tong)時,消耗電能(neng)與標準表的總電能(neng)一(yi)致。

  信息來源(yuan)://tede.cn

  電(dian)能(neng)表(biao)在(zai)諧(xie)波(bo)(bo)工(gong)況下的電(dian)壓(ya)、電(dian)流有(you)效值(zhi),基波(bo)(bo)功率和(he)諧(xie)波(bo)(bo)功率與理論值(zhi)一致。

  電網的高次諧(xie)波(bo)對電能計量(liang)的準確性有影(ying)(ying)響,當(dang)諧(xie)波(bo)含量(liang)滿足國標規(gui)定時(shi),誤差影(ying)(ying)響微小,當(dang)諧(xie)波(bo)含量(liang)超過國標規(gui)定時(shi),無論是(shi)電磁感(gan)應(ying)式電能表(biao)還是(shi)全電子式電能表(biao),誤差影(ying)(ying)響均較大;即諧(xie)波(bo)含量(liang)愈(yu)高影(ying)(ying)響量(liang)越大,電能計量(liang)誤差也(ye)越大。

  為了合(he)理計量(liang)用(yong)戶(hu)(hu)消耗的(de)(de)有(you)功(gong)電(dian)能(neng),在選用(yong)電(dian)量(liang)平(ping)衡統(tong)計和(he)貿易結(jie)算電(dian)能(neng)表(biao)時,針對含高次諧波的(de)(de)線路和(he)用(yong)戶(hu)(hu),不僅(jin)要(yao)求(qiu)(qiu)用(yong)戶(hu)(hu)按國標的(de)(de)要(yao)求(qiu)(qiu)進(jin)行諧波治(zhi)理,還應(ying)選用(yong)具有(you)計量(liang)諧波分量(liang)電(dian)能(neng)的(de)(de)多(duo)功(gong)能(neng)電(dian)能(neng)表(biao)。

  對同(tong)一計量(liang)點,在(zai)諧(xie)波(bo)(bo)超過國(guo)標(biao)規定時,采用相同(tong)準確級別的全(quan)(quan)電(dian)子式(shi)電(dian)能(neng)表(biao)和電(dian)磁(ci)(ci)感應(ying)式(shi)電(dian)能(neng)表(biao),計量(liang)電(dian)能(neng)量(liang)是有較大差別的;對大功率變流設備、電(dian)弧爐等產生高(gao)次諧(xie)波(bo)(bo)的電(dian)力(li)負載(zai)用戶,為了只記錄負荷消(xiao)耗的基(ji)波(bo)(bo)有功電(dian)能(neng),用電(dian)磁(ci)(ci)感應(ying)式(shi)電(dian)能(neng)表(biao)比用同(tong)準確級別的全(quan)(quan)電(dian)子式(shi)電(dian)能(neng)表(biao)更合(he)理(li)。當諧(xie)波(bo)(bo)源來自電(dian)網時,前(qian)者(zhe)數(shu)值較大;當諧(xie)波(bo)(bo)源是用戶時,則(ze)情況相反。

  在電(dian)(dian)(dian)(dian)網(wang)(wang)中,無論諧波(bo)流(liu)向如(ru)何,當(dang)諧波(bo)從負(fu)載流(liu)向電(dian)(dian)(dian)(dian)網(wang)(wang)時,實際(ji)上是(shi)負(fu)載將(jiang)電(dian)(dian)(dian)(dian)網(wang)(wang)中的(de)基(ji)波(bo)經過濾波(bo)和整流(liu)后,形成的(de)諧波(bo)電(dian)(dian)(dian)(dian)流(liu)反(fan)送(song)回電(dian)(dian)(dian)(dian)網(wang)(wang),這是(shi)一(yi)種(zhong)電(dian)(dian)(dian)(dian)能(neng)(neng)污染(ran)。全電(dian)(dian)(dian)(dian)子式電(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)將(jiang)負(fu)載(諧波(bo)源)消耗的(de)基(ji)波(bo)有功(gong)(gong)電(dian)(dian)(dian)(dian)能(neng)(neng)和諧波(bo)源(負(fu)載)向電(dian)(dian)(dian)(dian)網(wang)(wang)返送(song)的(de)諧波(bo)有功(gong)(gong)電(dian)(dian)(dian)(dian)能(neng)(neng)(被污染(ran)的(de)電(dian)(dian)(dian)(dian)能(neng)(neng))進行(xing)了(le)代數相加(jia),使得記錄(lu)的(de)能(neng)(neng)量(liang)比負(fu)載消耗的(de)基(ji)波(bo)有功(gong)(gong)電(dian)(dian)(dian)(dian)能(neng)(neng)量(liang)還(huan)要(yao)小,這是(shi)全電(dian)(dian)(dian)(dian)子式電(dian)(dian)(dian)(dian)能(neng)(neng)表(biao)計(ji)量(liang)原(yuan)理上的(de)不足之(zhi)處


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