太陽(yang)照在地(di)面太陽(yang)能電池(chi)方陣上的(de)輻射光的(de)光譜、光強(qiang)受到大氣(qi)層(ceng)厚度(即(ji)大氣(qi)質量(liang)(liang))、地(di)理位置、所在地(di)的(de)氣(qi)候和氣(qi)象、地(di)形地(di)物等的(de)影響,其(qi)能量(liang)(liang)在一(yi)日(ri)、一(yi)月和一(yi)年(nian)內都有(you)很大的(de)變化,甚(shen)至各年(nian)之間(jian)的(de)每(mei)年(nian)總輻射量(liang)(liang)也有(you)較大的(de)差別。
太(tai)陽(yang)能電(dian)(dian)(dian)池(chi)方(fang)陣的光(guang)電(dian)(dian)(dian)轉換效率(lv)(lv),受到電(dian)(dian)(dian)池(chi)本身的溫度、太(tai)陽(yang)光(guang)強和蓄電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)壓浮(fu)動的影響,而(er)這三者在一天內都會發生變(bian)化,所(suo)以太(tai)陽(yang)能電(dian)(dian)(dian)池(chi)方(fang)陣的光(guang)電(dian)(dian)(dian)轉換效率(lv)(lv)也是變(bian)量。
蓄(xu)電(dian)池組也(ye)是工作在浮充電(dian)狀態下(xia)的,其電(dian)壓隨方陣(zhen)發電(dian)量(liang)和負載(zai)用電(dian)量(liang)的變化而變化。蓄(xu)電(dian)池提供的能(neng)量(liang)還受(shou)環境溫度的影響。
太(tai)陽能(neng)電(dian)(dian)池充放電(dian)(dian)控(kong)制器(qi)由電(dian)(dian)子元(yuan)器(qi)件(jian)制造而(er)成(cheng),它本身也需要耗能(neng),而(er)使用的元(yuan)器(qi)件(jian)的性(xing)能(neng)、質量等也關系到耗能(neng)的大小,從而(er)影響到充電(dian)(dian)的效率等。
負(fu)載(zai)的(de)(de)用(yong)(yong)電(dian)情況(kuang),也(ye)視用(yong)(yong)途(tu)而定,如通(tong)信(xin)中繼站、無人氣(qi)象站等,有固定的(de)(de)設(she)備(bei)耗電(dian)量。而有些(xie)設(she)備(bei)如燈塔、航標燈、民用(yong)(yong)照明及生(sheng)活(huo)用(yong)(yong)電(dian)等設(she)備(bei),用(yong)(yong)電(dian)量是(shi)經常有變化的(de)(de)。
因(yin)(yin)此,太(tai)陽(yang)能電源系統(tong)的設計,需要考(kao)慮的因(yin)(yin)素(su)多而(er)復雜。特點是:所用(yong)的數據(ju)大(da)多為以前統(tong)計的數據(ju),各統(tong)計數據(ju)的測量以及數據(ju)的選擇(ze)是重要的。
設(she)計(ji)者的任務是:在太陽(yang)(yang)能(neng)電(dian)池方陣(zhen)所處的環境條件下(即現場的地(di)理位置(zhi)、太陽(yang)(yang)輻射(she)能(neng)、氣候、氣象、地(di)形(xing)和地(di)物等(deng)),設(she)計(ji)的太陽(yang)(yang)能(neng)電(dian)池方陣(zhen)及蓄電(dian)池電(dian)源系統既要(yao)講究經濟效益,又要(yao)保證系統的高(gao)可靠性。
某特定地點的(de)太陽輻(fu)射能量數據(ju),以氣象(xiang)臺(tai)提供的(de)資料為依據(ju),供設計太陽能電池(chi)方陣用。這(zhe)些氣象(xiang)數據(ju)需取(qu)積累(lei)幾年甚(shen)至幾十年的(de)平均值。
地(di)(di)球上各地(di)(di)區受太陽(yang)(yang)光照射(she)(she)及輻(fu)射(she)(she)能(neng)變(bian)化的(de)(de)(de)(de)(de)(de)周期(qi)為(wei)一天(tian)24h。處(chu)在某一地(di)(di)區的(de)(de)(de)(de)(de)(de)太陽(yang)(yang)能(neng)電(dian)(dian)(dian)池(chi)方陣的(de)(de)(de)(de)(de)(de)發(fa)電(dian)(dian)(dian)量也有(you)24h的(de)(de)(de)(de)(de)(de)周期(qi)性的(de)(de)(de)(de)(de)(de)變(bian)化,其規律與太陽(yang)(yang)照在該(gai)地(di)(di)區輻(fu)射(she)(she)的(de)(de)(de)(de)(de)(de)變(bian)化規律相同(tong)。但是(shi)(shi)天(tian)氣(qi)的(de)(de)(de)(de)(de)(de)變(bian)化將(jiang)影響方陣的(de)(de)(de)(de)(de)(de)發(fa)電(dian)(dian)(dian)量。如果有(you)幾天(tian)連續(xu)陰雨(yu)天(tian),方陣就(jiu)幾乎(hu)不能(neng)發(fa)電(dian)(dian)(dian),只能(neng)靠蓄(xu)電(dian)(dian)(dian)池(chi)來供電(dian)(dian)(dian),而(er)蓄(xu)電(dian)(dian)(dian)池(chi)深度(du)放電(dian)(dian)(dian)后又需盡(jin)快地(di)(di)將(jiang)其補充好。設(she)計者多數(shu)以氣(qi)象(xiang)臺(tai)提供的(de)(de)(de)(de)(de)(de)太陽(yang)(yang)每天(tian)總(zong)(zong)的(de)(de)(de)(de)(de)(de)輻(fu)射(she)(she)能(neng)量或(huo)(huo)每年(nian)的(de)(de)(de)(de)(de)(de)日(ri)照時(shi)數(shu)的(de)(de)(de)(de)(de)(de)平(ping)均值作為(wei)設(she)計的(de)(de)(de)(de)(de)(de)主要數(shu)據(ju)。由于一個地(di)(di)區各年(nian)的(de)(de)(de)(de)(de)(de)數(shu)據(ju)不相同(tong),為(wei)可靠起見應(ying)取近十(shi)年(nian)內的(de)(de)(de)(de)(de)(de)最(zui)小(xiao)數(shu)據(ju)。根據(ju)負載的(de)(de)(de)(de)(de)(de)耗電(dian)(dian)(dian)情況,在日(ri)照和無(wu)日(ri)照時(shi),均需用蓄(xu)電(dian)(dian)(dian)池(chi)供電(dian)(dian)(dian)。氣(qi)象(xiang)臺(tai)提供的(de)(de)(de)(de)(de)(de)太陽(yang)(yang)能(neng)總(zong)(zong)輻(fu)射(she)(she)量或(huo)(huo)總(zong)(zong)日(ri)照時(shi)數(shu)對決定(ding)蓄(xu)電(dian)(dian)(dian)池(chi)的(de)(de)(de)(de)(de)(de)容量大小(xiao)是(shi)(shi)不可缺少的(de)(de)(de)(de)(de)(de)數(shu)據(ju)。
對太陽能電(dian)池(chi)方陣而言,負載應包括(kuo)系統中所有耗(hao)電(dian)裝置(除用電(dian)器(qi)外還有蓄電(dian)池(chi)及線(xian)路(lu)、控制器(qi)等)的(de)耗(hao)量。
方陣的(de)輸出功率與組件(jian)串并聯的(de)數(shu)量有(you)關,串聯是(shi)為了獲(huo)得所需(xu)要的(de)工作電壓,并聯是(shi)為了獲(huo)得所需(xu)要的(de)工作電流,適(shi)當數(shu)量的(de)組件(jian)經(jing)過串并聯即(ji)組成所需(xu)要的(de)太陽能電池方陣。
3蓄(xu)電池組容(rong)量設(she)計
太(tai)陽能電(dian)池(chi)(chi)電(dian)源系(xi)統(tong)的(de)(de)(de)儲能裝置(zhi)主(zhu)要是蓄電(dian)池(chi)(chi)。與太(tai)陽能電(dian)池(chi)(chi)方陣配套的(de)(de)(de)蓄電(dian)池(chi)(chi)通常工(gong)作在(zai)浮(fu)充狀態下,其(qi)電(dian)壓隨方陣發(fa)電(dian)量(liang)(liang)(liang)和(he)負載(zai)用電(dian)量(liang)(liang)(liang)的(de)(de)(de)變(bian)化而變(bian)化。它的(de)(de)(de)容量(liang)(liang)(liang)比負載(zai)所需的(de)(de)(de)電(dian)量(liang)(liang)(liang)大得多。蓄電(dian)池(chi)(chi)提供的(de)(de)(de)能量(liang)(liang)(liang)還受環境溫度的(de)(de)(de)影(ying)響(xiang)。為了(le)與太(tai)陽能電(dian)池(chi)(chi)匹配,要求蓄電(dian)池(chi)(chi)工(gong)作壽命長且維護簡單。
(1)蓄電(dian)池的選用(yong)
能夠和(he)太(tai)陽能電(dian)(dian)池(chi)(chi)配套使(shi)用(yong)的(de)蓄(xu)電(dian)(dian)池(chi)(chi)種類很多,目前廣(guang)泛采用(yong)的(de)有鉛酸(suan)免維(wei)(wei)護蓄(xu)電(dian)(dian)池(chi)(chi)、普(pu)通(tong)鉛酸(suan)蓄(xu)電(dian)(dian)池(chi)(chi)和(he)堿性(xing)(xing)鎳鎘(ge)蓄(xu)電(dian)(dian)池(chi)(chi)三種。國內目前主要(yao)(yao)使(shi)用(yong)鉛酸(suan)免維(wei)(wei)護蓄(xu)電(dian)(dian)池(chi)(chi),因為(wei)其固有的(de)“免”維(wei)(wei)護特(te)性(xing)(xing)及對環(huan)境(jing)較(jiao)(jiao)少污染(ran)的(de)特(te)點,很適(shi)合用(yong)于性(xing)(xing)能可靠的(de)太(tai)陽能電(dian)(dian)源系統,特(te)別是無人值守的(de)工(gong)作(zuo)站。普(pu)通(tong)鉛酸(suan)蓄(xu)電(dian)(dian)池(chi)(chi)由(you)于需要(yao)(yao)經常維(wei)(wei)護及其環(huan)境(jing)污染(ran)較(jiao)(jiao)大,所(suo)以主要(yao)(yao)適(shi)于有維(wei)(wei)護能力或(huo)低檔場(chang)(chang)合使(shi)用(yong)。堿性(xing)(xing)鎳鎘(ge)蓄(xu)電(dian)(dian)池(chi)(chi)雖然有較(jiao)(jiao)好的(de)低溫(wen)、過充、過放性(xing)(xing)能,但(dan)由(you)于其價格較(jiao)(jiao)高(gao),僅適(shi)用(yong)于較(jiao)(jiao)為(wei)特(te)殊的(de)場(chang)(chang)合。
(2)蓄電池組容(rong)量的計算
蓄(xu)電(dian)(dian)池(chi)的(de)(de)(de)容(rong)(rong)量對保(bao)證連續(xu)供電(dian)(dian)是(shi)很(hen)重要(yao)(yao)的(de)(de)(de)。在(zai)一年內,方陣(zhen)發電(dian)(dian)量各(ge)月(yue)份有很(hen)大差別。方陣(zhen)的(de)(de)(de)發電(dian)(dian)量在(zai)不(bu)能滿足(zu)(zu)用電(dian)(dian)需(xu)要(yao)(yao)的(de)(de)(de)月(yue)份,要(yao)(yao)靠蓄(xu)電(dian)(dian)池(chi)的(de)(de)(de)電(dian)(dian)能給(gei)以(yi)補(bu)足(zu)(zu);在(zai)超過(guo)用電(dian)(dian)需(xu)要(yao)(yao)的(de)(de)(de)月(yue)份,是(shi)靠蓄(xu)電(dian)(dian)池(chi)將多余(yu)的(de)(de)(de)電(dian)(dian)能儲存起來。所以(yi)方陣(zhen)發電(dian)(dian)量的(de)(de)(de)不(bu)足(zu)(zu)和過(guo)剩(sheng)值(zhi),是(shi)確(que)定(ding)蓄(xu)電(dian)(dian)池(chi)容(rong)(rong)量的(de)(de)(de)依(yi)據之(zhi)一。同樣,連續(xu)陰雨天期間(jian)的(de)(de)(de)負(fu)載用電(dian)(dian)也必須(xu)從蓄(xu)電(dian)(dian)池(chi)取得。所以(yi),這期間(jian)的(de)(de)(de)耗電(dian)(dian)量也是(shi)確(que)定(ding)蓄(xu)電(dian)(dian)池(chi)容(rong)(rong)量的(de)(de)(de)因素之(zhi)一。
因此,蓄電池的容(rong)量(liang)BC計算公式為:
BC=A×QL×NL×TO/CCAh(1)
式中:A為安全系數,取1.1~1.4之間;
QL為負載日(ri)平(ping)均耗電量,為工作(zuo)電流(liu)乘以日(ri)工作(zuo)小(xiao)時數;
NL為(wei)最長連續陰(yin)雨(yu)天數(shu);
TO為(wei)溫(wen)度修正系數,一般在0℃以(yi)(yi)上取(qu)1,-10℃以(yi)(yi)上取(qu)1.1,-10℃以(yi)(yi)下取(qu)1.2;
CC為蓄電池放電深度,一(yi)般鉛(qian)酸(suan)蓄電池取0.75,堿性鎳鎘蓄電池取0.85。
4太陽能電池方陣設計
(1)太陽能(neng)電池組件(jian)串聯數Ns
將太(tai)陽(yang)能(neng)電(dian)(dian)池(chi)組(zu)件按一(yi)定(ding)數目串(chuan)聯(lian)(lian)(lian)起來,就可獲得所需(xu)要的(de)工作電(dian)(dian)壓(ya),但(dan)是,太(tai)陽(yang)能(neng)電(dian)(dian)池(chi)組(zu)件的(de)串(chuan)聯(lian)(lian)(lian)數必須適當。串(chuan)聯(lian)(lian)(lian)數太(tai)少,串(chuan)聯(lian)(lian)(lian)電(dian)(dian)壓(ya)低于(yu)蓄電(dian)(dian)池(chi)浮充(chong)(chong)電(dian)(dian)壓(ya),方陣就不能(neng)對蓄電(dian)(dian)池(chi)充(chong)(chong)電(dian)(dian)。如果串(chuan)聯(lian)(lian)(lian)數太(tai)多使(shi)輸出電(dian)(dian)壓(ya)遠高于(yu)浮充(chong)(chong)電(dian)(dian)壓(ya)時,充(chong)(chong)電(dian)(dian)電(dian)(dian)流(liu)也(ye)不會有(you)明顯的(de)增加。因此,只有(you)當太(tai)陽(yang)能(neng)電(dian)(dian)池(chi)組(zu)件的(de)串(chuan)聯(lian)(lian)(lian)電(dian)(dian)壓(ya)等于(yu)合適的(de)浮充(chong)(chong)電(dian)(dian)壓(ya)時,才能(neng)達到最(zui)佳的(de)充(chong)(chong)電(dian)(dian)狀(zhuang)態。
計算方法如下:
Ns=UR/Uoc=(Uf+UD+Uc)/Uoc(2)
式中(zhong):UR為太陽能電池(chi)方陣(zhen)輸出最小電壓;
Uoc為太(tai)陽(yang)能(neng)電(dian)池組件(jian)的(de)最佳工作電(dian)壓;
Uf為蓄電池浮充電壓;
UD為二極管壓(ya)降(jiang),一般取0.7V;
UC為其(qi)它(ta)因數引起的(de)壓降。
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