一、什么是光伏逆變器

逆變器又稱(cheng)電(dian)源調(diao)(diao)整(zheng)器(qi)(qi)，根(gen)據逆(ni)(ni)(ni)(ni)變(bian)(bian)器(qi)(qi)在光(guang)伏發電(dian)系(xi)(xi)統(tong)(tong)中的用途可分(fen)為獨立型電(dian)源用和(he)并(bing)網用二種。根(gen)據波(bo)(bo)形調(diao)(diao)制方(fang)式又可分(fen)為方(fang)波(bo)(bo)逆(ni)(ni)(ni)(ni)變(bian)(bian)器(qi)(qi)、階(jie)梯波(bo)(bo)逆(ni)(ni)(ni)(ni)變(bian)(bian)器(qi)(qi)、正弦波(bo)(bo)逆(ni)(ni)(ni)(ni)變(bian)(bian)器(qi)(qi)和(he)組合式三相逆(ni)(ni)(ni)(ni)變(bian)(bian)器(qi)(qi)。對于(yu)用于(yu)并(bing)網系(xi)(xi)統(tong)(tong)的逆(ni)(ni)(ni)(ni)變(bian)(bian)器(qi)(qi)，根(gen)據有無變(bian)(bian)壓(ya)器(qi)(qi)又可分(fen)為變(bian)(bian)壓(ya)器(qi)(qi)型逆(ni)(ni)(ni)(ni)變(bian)(bian)器(qi)(qi)和(he)無變(bian)(bian)變(bian)(bian)壓(ya)器(qi)(qi)型逆(ni)(ni)(ni)(ni)變(bian)(bian)器(qi)(qi)。

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二、結構原理

逆變器是一種由半導體器件組成的電力調整裝置，主要用于把直流電力轉(zhuan)換成(cheng)交流(liu)電(dian)(dian)(dian)力。一般由升壓(ya)回(hui)(hui)(hui)(hui)路和逆(ni)變(bian)橋式(shi)回(hui)(hui)(hui)(hui)路構成(cheng)。升壓(ya)回(hui)(hui)(hui)(hui)路把太陽(yang)電(dian)(dian)(dian)池(chi)的(de)(de)(de)(de)直(zhi)流(liu)電(dian)(dian)(dian)壓(ya)升壓(ya)到逆(ni)變(bian)器(qi)輸(shu)(shu)出控(kong)制(zhi)所需的(de)(de)(de)(de)直(zhi)流(liu)電(dian)(dian)(dian)壓(ya)；逆(ni)變(bian)橋式(shi)回(hui)(hui)(hui)(hui)路則(ze)(ze)把升壓(ya)后的(de)(de)(de)(de)直(zhi)流(liu)電(dian)(dian)(dian)壓(ya)等價地(di)(di)轉(zhuan)換成(cheng)常用頻(pin)率的(de)(de)(de)(de)交流(liu)電(dian)(dian)(dian)壓(ya)。逆(ni)變(bian)器(qi)主(zhu)要由晶體管等開關(guan)(guan)元(yuan)件(jian)構成(cheng)，通(tong)過有(you)規(gui)則(ze)(ze)地(di)(di)讓(rang)開關(guan)(guan)元(yuan)件(jian)重復開-關(guan)(guan)（ON-OFF），使直(zhi)流(liu)輸(shu)(shu)入變(bian)成(cheng)交流(liu)輸(shu)(shu)出。當然(ran)，這樣單純地(di)(di)由開和關(guan)(guan)回(hui)(hui)(hui)(hui)路產生的(de)(de)(de)(de)逆(ni)變(bian)器(qi)輸(shu)(shu)出波(bo)(bo)(bo)形(xing)(xing)并(bing)(bing)不(bu)實(shi)用。一般需要采用高(gao)頻(pin)脈寬(kuan)調制(zhi)（SPWM），使靠(kao)近正弦(xian)(xian)波(bo)(bo)(bo)兩端的(de)(de)(de)(de)電(dian)(dian)(dian)壓(ya)寬(kuan)度變(bian)狹(xia)，正弦(xian)(xian)波(bo)(bo)(bo)中央的(de)(de)(de)(de)電(dian)(dian)(dian)壓(ya)寬(kuan)度變(bian)寬(kuan)，并(bing)(bing)在(zai)半周期內(nei)始(shi)終讓(rang)開關(guan)(guan)元(yuan)件(jian)按一定頻(pin)率朝一方向動作(zuo)，這樣形(xing)(xing)成(cheng)一個脈沖(chong)波(bo)(bo)(bo)列(lie)（擬(ni)正弦(xian)(xian)波(bo)(bo)(bo)）。然(ran)后讓(rang)脈沖(chong)波(bo)(bo)(bo)通(tong)過簡單的(de)(de)(de)(de)濾(lv)波(bo)(bo)(bo)器(qi)形(xing)(xing)成(cheng)正弦(xian)(xian)波(bo)(bo)(bo)。

三、逆變器的元器件構成

1、電流傳感器

對于電(dian)流(liu)傳(chuan)(chuan)感器(qi)要求精度高、響(xiang)應(ying)時間快，而且耐低溫(wen)(wen)、高溫(wen)(wen)等(deng)環境要求，目(mu)前國內很多廠(chang)家都用開環電(dian)流(liu)傳(chuan)(chuan)感器(qi)來取代閉環電(dian)流(liu)傳(chuan)(chuan)感器(qi)，如：JCE1000-AXS、JCE1500-AXS、JCE2000-AXS等(deng)

2、電流互感器

一般采用(yong)BRS系列電流(liu)互感(gan)器，從幾(ji)百(bai)到幾(ji)千A不等，輸出信號一般采用(yong)0-5A為標準

3、電抗器

三、功能

1、自動運行和停機功能

早晨日出(chu)(chu)后，太(tai)陽輻射(she)強(qiang)度逐漸增強(qiang)，太(tai)陽電(dian)(dian)(dian)池(chi)的(de)(de)輸(shu)出(chu)(chu)也(ye)隨之增大，當(dang)達到逆(ni)(ni)變(bian)(bian)(bian)器(qi)(qi)工作(zuo)所需的(de)(de)輸(shu)出(chu)(chu)功(gong)率后，逆(ni)(ni)變(bian)(bian)(bian)器(qi)(qi)即自動(dong)開始運(yun)(yun)行(xing)(xing)。進入運(yun)(yun)行(xing)(xing)后，逆(ni)(ni)變(bian)(bian)(bian)器(qi)(qi)便時(shi)(shi)時(shi)(shi)刻刻監視太(tai)陽電(dian)(dian)(dian)池(chi)組件(jian)的(de)(de)輸(shu)出(chu)(chu)，只(zhi)要(yao)太(tai)陽電(dian)(dian)(dian)池(chi)組件(jian)的(de)(de)輸(shu)出(chu)(chu)功(gong)率大于逆(ni)(ni)變(bian)(bian)(bian)器(qi)(qi)工作(zuo)所需的(de)(de)輸(shu)出(chu)(chu)功(gong)率，逆(ni)(ni)變(bian)(bian)(bian)器(qi)(qi)就持續運(yun)(yun)行(xing)(xing)；直到日落停機(ji)，即使陰雨天逆(ni)(ni)變(bian)(bian)(bian)器(qi)(qi)也(ye)能(neng)運(yun)(yun)行(xing)(xing)。當(dang)太(tai)陽電(dian)(dian)(dian)池(chi)組件(jian)輸(shu)出(chu)(chu)變(bian)(bian)(bian)小(xiao)，逆(ni)(ni)變(bian)(bian)(bian)器(qi)(qi)輸(shu)出(chu)(chu)接近(jin)0時(shi)(shi)，逆(ni)(ni)變(bian)(bian)(bian)器(qi)(qi)便形成待機(ji)狀態(tai)。

2、最大功率跟蹤控制功能

太陽能電(dian)(dian)(dian)池(chi)組(zu)件的輸出(chu)是隨(sui)太(tai)(tai)(tai)陽(yang)輻(fu)射強度和太(tai)(tai)(tai)陽(yang)電(dian)(dian)(dian)池(chi)組(zu)件自(zi)身溫度（芯片溫度）而(er)變(bian)化(hua)的。另外由于(yu)太(tai)(tai)(tai)陽(yang)電(dian)(dian)(dian)池(chi)組(zu)件具有電(dian)(dian)(dian)壓隨(sui)電(dian)(dian)(dian)流增(zeng)大而(er)下降的特(te)性，因此存在(zai)能獲取最(zui)(zui)大功(gong)率的最(zui)(zui)佳工(gong)作點。太(tai)(tai)(tai)陽(yang)輻(fu)射強度是變(bian)化(hua)著的，顯然最(zui)(zui)佳工(gong)作點也是在(zai)變(bian)化(hua)的。相對(dui)于(yu)這(zhe)(zhe)些變(bian)化(hua)，始終讓(rang)太(tai)(tai)(tai)陽(yang)電(dian)(dian)(dian)池(chi)組(zu)件的工(gong)作點處于(yu)最(zui)(zui)大功(gong)率點，系(xi)統(tong)始終從太(tai)(tai)(tai)陽(yang)電(dian)(dian)(dian)池(chi)組(zu)件獲取最(zui)(zui)大功(gong)率輸出(chu)，這(zhe)(zhe)種控(kong)制(zhi)就是最(zui)(zui)大功(gong)率跟(gen)蹤控(kong)制(zhi)。太(tai)(tai)(tai)陽(yang)能發(fa)電(dian)(dian)(dian)系(xi)統(tong)用的逆變(bian)器的最(zui)(zui)大特(te)點就是包括(kuo)了最(zui)(zui)大功(gong)率點跟(gen)蹤（MPPT）這(zhe)(zhe)一功(gong)能。

四、選購步驟及方法

1、功率

一(yi)般根據系統(tong)的要求配置對應(ying)功(gong)率段的逆(ni)變(bian)(bian)器(qi)，選型(xing)的逆(ni)變(bian)(bian)器(qi)的功(gong)率應(ying)該與太陽能電池(chi)方陣的最(zui)大功(gong)率匹配，一(yi)般選取光伏逆(ni)變(bian)(bian)器(qi)的額定輸出功(gong)率與輸入總功(gong)率相(xiang)近左右，這樣可以節約成本。

2、關鍵技術指標

1）選擇合適的輸入輸出電(dian)壓范圍，確保產品(pin)的最優組(zu)合。

2）逆變器(qi)的(de)歐洲效(xiao)率：它(ta)的(de)高(gao)低將直接影響到光(guang)伏(fu)發電(dian)系統的(de)設計成(cheng)本與(yu)發電(dian)效(xiao)率。

3）太陽電池方陣最大功率(lv)跟蹤功能(neng)（MPPT）及其效率(lv)。

4）應注(zhu)意所選(xuan)用的(de)逆變器應有基(ji)本的(de)保(bao)(bao)(bao)護(hu)功(gong)能(neng)，如過(guo)流/短路保(bao)(bao)(bao)護(hu)、過(guo)功(gong)率保(bao)(bao)(bao)護(hu)，過(guo)溫保(bao)(bao)(bao)護(hu)，防(fang)雷保(bao)(bao)(bao)護(hu)、孤島保(bao)(bao)(bao)護(hu)等功(gong)能(neng)。

5）逆變(bian)(bian)器輸出電流波形(xing)畸變(bian)(bian)率（THD%）要低于(yu)4%。

3、認證標準

作為光伏(fu)電站的核心設備，為保證電站的穩定(ding)、可靠、持續運(yun)行，并(bing)網逆變器(qi)必須有很高的可靠性(xing)。它應具有銷售目的地的安(an)規認(ren)證，電磁(ci)兼容(rong)認(ren)證，及各國并(bing)網認(ren)證：（以歐(ou)洲為例）

安規(gui)：EN62109-1，EN62109-2

電磁兼容(rong):EN61000-6-1,EN61000-6-2,EN61000-6-3,EN61000-6-4

并網認證:VDE0126-1-1(德(de)國)

4、品牌與服務

建議購買目前市(shi)場上口碑不錯的品牌(pai)(pai)，因為一般品牌(pai)(pai)形(xing)象好的公司，通常(chang)會在技術，以及維修服務上有較大的投(tou)資，能滿(man)足對(dui)客(ke)戶的承(cheng)諾。