塔(ta)式太(tai)陽能熱(re)發(fa)電(dian)站的輸(shu)出與(yu)儲熱(re)調峰特性研究(jiu)
周慧(hui),張開宇,胡錦華*,劉(liu)盛豪,王玄驊,王巍
(浙江(jiang)可勝技術股份有限公司,杭(hang)州(zhou)310053)
摘要:隨著電(dian)(dian)(dian)(dian)(dian)網峰(feng)谷差的(de)增大(da),其對調峰(feng)電(dian)(dian)(dian)(dian)(dian)源的(de)需求(qiu)也隨之增加,塔(ta)式(shi)太(tai)陽能(neng)熱發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)站(zhan)具有良(liang)(liang)好的(de)可調度性(xing),是優質的(de)綠色(se)調峰(feng)電(dian)(dian)(dian)(dian)(dian)源。以(yi)青(qing)海省(sheng)某商業化運行的(de)50MW塔(ta)式(shi)太(tai)陽能(neng)熱發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)站(zhan)為研(yan)究對象,對其組成部分、運行模(mo)式(shi)、輸(shu)(shu)出特性(xing)及儲(chu)熱調峰(feng)能(neng)力進行了分析(xi)。分析(xi)結果顯示:(1)該太(tai)陽能(neng)熱發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)站(zhan)可克服光(guang)伏(fu)(fu)發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)、風(feng)電(dian)(dian)(dian)(dian)(dian)的(de)隨機性(xing)、波動性(xing)缺(que)點,在多云天氣下也能(neng)維持穩定(ding)高(gao)(gao)功率(lv)(lv)(lv)輸(shu)(shu)出,同時還能(neng)根據(ju)用電(dian)(dian)(dian)(dian)(dian)需求(qiu)維持低(di)功率(lv)(lv)(lv)持續(xu)運行,表現出良(liang)(liang)好能(neng)量調節能(neng)力。(2)該太(tai)陽能(neng)熱發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)站(zhan)可以(yi)在光(guang)伏(fu)(fu)發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)、風(feng)力發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)高(gao)(gao)峰(feng)期(qi)時,快速(su)降功率(lv)(lv)(lv)運行;而在光(guang)伏(fu)(fu)發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)、風(feng)力發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)處于谷值時,快速(su)升功率(lv)(lv)(lv)運行,使(shi)電(dian)(dian)(dian)(dian)(dian)網最(zui)大(da)限度地消納光(guang)伏(fu)(fu)發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)和(he)風(feng)電(dian)(dian)(dian)(dian)(dian)。
關鍵詞:塔式太陽能熱(re)發電(dian)站;儲熱(re)調峰;輸出(chu)特性;調峰電(dian)源(yuan)
DOI:10.19911/j.1003-0417.tyn20241211.01
文章編號:1003-0417(2025)06-38-07
可再生(sheng)能(neng)源(yuan)存(cun)在間歇性和波動性,其(qi)大規(gui)模(mo)并網增(zeng)大了(le)電(dian)(dian)網等效負荷的(de)(de)峰谷差(cha),進(jin)而對電(dian)(dian)網的(de)(de)安全運行(xing)造成了(le)威脅[1-4]。為使電(dian)(dian)網有效消納(na)可再生(sheng)能(neng)源(yuan),使用(yong)高穩定(ding)性的(de)(de)電(dian)(dian)源(yuan)進(jin)行(xing)靈(ling)活調峰成為一種有效方(fang)法[5-6],其(qi)中,采用(yong)熔鹽(yan)儲(chu)能(neng)技(ji)術(shu)的(de)(de)塔式太(tai)陽能(neng)熱發電(dian)(dian)站(zhan),可通過(guo)儲(chu)換熱系(xi)統實現能(neng)量的(de)(de)快速(su)釋放與(yu)轉換,具有天(tian)然的(de)(de)調峰優(you)勢[7-12]。
國內外學者已做了(le)(le)大(da)量(liang)有(you)關太陽(yang)(yang)能(neng)(neng)熱(re)(re)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)儲熱(re)(re)調(diao)峰(feng)(feng)特性的(de)(de)(de)(de)研究。比如(ru):Boukelia等[13]對(dui)有(you)無儲熱(re)(re)和(he)燃料(liao)備用系統的(de)(de)(de)(de)槽(cao)式太陽(yang)(yang)能(neng)(neng)熱(re)(re)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)站(zhan)的(de)(de)(de)(de)輸出功(gong)率進(jin)(jin)行(xing)(xing)了(le)(le)研究。崔楊等[14]研究發(fa)現:火(huo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)組的(de)(de)(de)(de)調(diao)峰(feng)(feng)成本受并網太陽(yang)(yang)能(neng)(neng)熱(re)(re)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)站(zhan)儲熱(re)(re)容量(liang)的(de)(de)(de)(de)影響(xiang),通(tong)過(guo)合理配(pei)置儲熱(re)(re)容量(liang)能(neng)(neng)有(you)效降低(di)火(huo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)組的(de)(de)(de)(de)調(diao)峰(feng)(feng)成本。張堯翔等[15]對(dui)太陽(yang)(yang)能(neng)(neng)熱(re)(re)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)可(ke)調(diao)節特性及太陽(yang)(yang)能(neng)(neng)熱(re)(re)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)-火(huo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)聯(lian)合調(diao)峰(feng)(feng)控制的(de)(de)(de)(de)可(ke)行(xing)(xing)性進(jin)(jin)行(xing)(xing)了(le)(le)分析,并通(tong)過(guo)算例驗證了(le)(le)其有(you)效性。贠(yuan)韞韻等[16]基于(yu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)網經濟性調(diao)度(du)問題建(jian)立(li)了(le)(le)太陽(yang)(yang)能(neng)(neng)熱(re)(re)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)站(zhan)需求響(xiang)應模(mo)型,得出火(huo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)組和(he)太陽(yang)(yang)能(neng)(neng)熱(re)(re)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)站(zhan)配(pei)合可(ke)以提高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)網對(dui)可(ke)再生能(neng)(neng)源(yuan)的(de)(de)(de)(de)消(xiao)(xiao)納深度(du)。董海鷹等[17]對(dui)熱(re)(re)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)聯(lian)產運行(xing)(xing)模(mo)式下的(de)(de)(de)(de)太陽(yang)(yang)能(neng)(neng)熱(re)(re)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)儲熱(re)(re)調(diao)峰(feng)(feng)策略進(jin)(jin)行(xing)(xing)了(le)(le)研究,研究結果表明:熱(re)(re)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)聯(lian)產運行(xing)(xing)模(mo)式下,通(tong)過(guo)太陽(yang)(yang)能(neng)(neng)熱(re)(re)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)站(zhan)的(de)(de)(de)(de)輔助供熱(re)(re),可(ke)顯著提高電(dian)(dian)(dian)(dian)(dian)(dian)(dian)網的(de)(de)(de)(de)風電(dian)(dian)(dian)(dian)(dian)(dian)(dian)消(xiao)(xiao)納水平。
雖然已有研究對(dui)太(tai)陽(yang)能(neng)(neng)(neng)熱(re)(re)發電(dian)站的(de)(de)儲(chu)熱(re)(re)調峰(feng)特(te)性進(jin)行了(le)研究,但基于太(tai)陽(yang)能(neng)(neng)(neng)熱(re)(re)發電(dian)站實際運行數據的(de)(de)儲(chu)熱(re)(re)調峰(feng)特(te)性的(de)(de)研究仍較為(wei)欠(qian)缺(que)。因此,本(ben)(ben)文以青海省某商業(ye)化(hua)運行的(de)(de)50MW塔式太(tai)陽(yang)能(neng)(neng)(neng)熱(re)(re)發電(dian)站(下文簡稱為(wei)“本(ben)(ben)太(tai)陽(yang)能(neng)(neng)(neng)熱(re)(re)發電(dian)站”)為(wei)研究對(dui)象,對(dui)其組成(cheng)部(bu)分、運行模式、輸出特(te)性及(ji)儲(chu)熱(re)(re)調峰(feng)能(neng)(neng)(neng)力進(jin)行分析(xi),旨(zhi)在為(wei)大(da)規模商業(ye)化(hua)塔式太(tai)陽(yang)能(neng)(neng)(neng)熱(re)(re)發電(dian)站的(de)(de)設計和運行提供理論支持。
1
本太陽能熱發電站概括
1.1組成部分介紹
本太陽(yang)能熱(re)(re)發(fa)電站由聚光集(ji)熱(re)(re)系(xi)統(tong)、儲換(huan)熱(re)(re)系(xi)統(tong)(包括(kuo)儲熱(re)(re)系(xi)統(tong)和換(huan)熱(re)(re)系(xi)統(tong))、汽輪(lun)機發(fa)電系(xi)統(tong)3部(bu)分組成,其運行原理圖如圖1所示。圖中:高(gao)加(jia)和低加(jia)分別為高(gao)壓加(jia)熱(re)(re)器和低壓加(jia)熱(re)(re)器的簡(jian)稱。
本太陽能(neng)熱(re)(re)(re)(re)發(fa)電(dian)站通過定日鏡陣列(鏡場)將(jiang)太陽輻射(she)反(fan)射(she)到吸(xi)熱(re)(re)(re)(re)塔(ta)(ta)塔(ta)(ta)頂(ding)的(de)(de)吸(xi)熱(re)(re)(re)(re)器上,吸(xi)熱(re)(re)(re)(re)器將(jiang)表面聚集(ji)的(de)(de)太陽輻射(she)能(neng)轉化(hua)為(wei)吸(xi)熱(re)(re)(re)(re)器內部(bu)傳熱(re)(re)(re)(re)工質(zhi)(采用熔鹽(yan),由60%的(de)(de)NaNO3和(he)40%的(de)(de)KNO3組(zu)成)的(de)(de)熱(re)(re)(re)(re)能(neng);隨后,通過管道(dao)將(jiang)由吸(xi)熱(re)(re)(re)(re)器加(jia)熱(re)(re)(re)(re)至565℃的(de)(de)熔鹽(yan)輸送到儲熱(re)(re)(re)(re)系統(tong)的(de)(de)熱(re)(re)(re)(re)鹽(yan)罐中儲存(cun),發(fa)電(dian)時熱(re)(re)(re)(re)鹽(yan)罐內的(de)(de)高溫熔鹽(yan)由熱(re)(re)(re)(re)鹽(yan)泵輸送至換(huan)(huan)熱(re)(re)(re)(re)系統(tong),在換(huan)(huan)熱(re)(re)(re)(re)系統(tong)中高溫熔鹽(yan)與給水換(huan)(huan)熱(re)(re)(re)(re),產生高品(pin)質(zhi)過熱(re)(re)(re)(re)蒸汽,進而(er)推(tui)動汽輪發(fa)電(dian)機(ji)組(zu)發(fa)電(dian)。
本太(tai)陽能熱發電站(zhan)(zhan)配置了(le)儲熱時長為7h的(de)儲熱系統,采用具有超高(gao)(gao)壓(ya)、高(gao)(gao)溫(wen)、中間一次(ci)再熱特性的(de)凝(ning)氣式(shi)汽輪發電機組,支持(chi)頻繁啟停。本太(tai)陽能熱發電站(zhan)(zhan)的(de)主(zhu)要技(ji)術參數如表(biao)1所示。
1.2本太陽能熱發電站的運行模式分析
由于太陽輻照具有周期性和波動性的特點,通過配備儲熱系統,本太陽能熱發電站可實現聚光集熱系統和汽輪機發電系統的解耦運行。根據運行特點,本太陽能熱發電站可分為4種運行模式,分別為:
1)儲(chu)熱模式。法向直接輻照(zhao)度(DNI)達到聚光集(ji)熱系(xi)統運行條件(jian)時,聚光集(ji)熱系(xi)統運行,儲(chu)熱系(xi)統儲(chu)熱,但(dan)此(ci)時儲(chu)熱量達不到汽輪發電機組啟動條件(jian)。
2)儲(chu)熱(re)(re)(re)且發(fa)(fa)(fa)電(dian)(dian)模式。當儲(chu)熱(re)(re)(re)系(xi)統儲(chu)熱(re)(re)(re)量滿足(zu)汽輪(lun)(lun)發(fa)(fa)(fa)電(dian)(dian)機組(zu)啟(qi)動(dong)條件時(shi)(shi),汽輪(lun)(lun)發(fa)(fa)(fa)電(dian)(dian)機組(zu)啟(qi)動(dong),汽輪(lun)(lun)機發(fa)(fa)(fa)電(dian)(dian)系(xi)統運(yun)行;此(ci)時(shi)(shi),本太陽能(neng)熱(re)(re)(re)發(fa)(fa)(fa)電(dian)(dian)站儲(chu)熱(re)(re)(re)與發(fa)(fa)(fa)電(dian)(dian)同時(shi)(shi)進行。
3)發電(dian)模式。當(dang)DNI不滿(man)足聚光(guang)集熱(re)系(xi)統(tong)運行條件時,聚光(guang)集熱(re)系(xi)統(tong)停運,但此時儲熱(re)系(xi)統(tong)儲存(cun)的熱(re)量能(neng)滿(man)足汽(qi)輪(lun)機發電(dian)機組(zu)運行,汽(qi)輪(lun)發電(dian)機組(zu)可根(gen)據電(dian)網(wang)調(diao)度需求進行負荷調(diao)節。
4)停(ting)機模式(shi)。在DNI為(wei)零或處于低值的情況(kuang)下,聚(ju)光集熱系(xi)統(tong)(tong)不(bu)運行(xing)且儲熱系(xi)統(tong)(tong)熱量不(bu)足時,汽(qi)輪機發電系(xi)統(tong)(tong)停(ting)運。
1.3本太陽能熱發電站典型日的運行模式分析
選取2019年12月21日(晴天)作(zuo)為典(dian)型日,對本太陽能熱(re)發(fa)電站在4種運(yun)行(xing)模式(shi)(shi)下的運(yun)行(xing)情(qing)況進行(xing)分析,分析結(jie)果如圖(tu)2所(suo)示。圖(tu)中:①為停機模式(shi)(shi);②為儲熱(re)模式(shi)(shi);③為儲熱(re)且(qie)發(fa)電模式(shi)(shi);④為發(fa)電模式(shi)(shi)。
由圖(tu)2可(ke)知:00:00~08:50時(shi)段,本太(tai)陽能熱(re)(re)發(fa)(fa)電(dian)(dian)站處(chu)于(yu)停(ting)機(ji)模(mo)(mo)式(shi),主要是因為(wei)此時(shi)DNI為(wei)零且儲(chu)(chu)熱(re)(re)系統(tong)的(de)儲(chu)(chu)熱(re)(re)量(liang)不足導致的(de)。08:50~11:45時(shi)段,本太(tai)陽能熱(re)(re)發(fa)(fa)電(dian)(dian)站處(chu)于(yu)儲(chu)(chu)熱(re)(re)模(mo)(mo)式(shi),隨著(zhu)DNI逐漸(jian)升高,聚光集熱(re)(re)系統(tong)開始工作,儲(chu)(chu)熱(re)(re)系統(tong)中的(de)熱(re)(re)熔鹽液位不斷(duan)(duan)升高,但汽輪發(fa)(fa)電(dian)(dian)機(ji)組尚(shang)未啟動(dong),因此本太(tai)陽能熱(re)(re)發(fa)(fa)電(dian)(dian)站處(chu)于(yu)儲(chu)(chu)熱(re)(re)模(mo)(mo)式(shi)。11:45~17:40時(shi)段,本太(tai)陽能熱(re)(re)發(fa)(fa)電(dian)(dian)站處(chu)于(yu)儲(chu)(chu)熱(re)(re)且發(fa)(fa)電(dian)(dian)模(mo)(mo)式(shi),隨著(zhu)熱(re)(re)鹽罐(guan)液位不斷(duan)(duan)上升,儲(chu)(chu)熱(re)(re)系統(tong)熱(re)(re)量(liang)達到汽輪發(fa)(fa)電(dian)(dian)機(ji)組啟動(dong)條件(jian),其開始運行(xing)并(bing)發(fa)(fa)電(dian)(dian)。17:40~24:00時(shi)段,本太(tai)陽能熱(re)(re)發(fa)(fa)電(dian)(dian)站處(chu)于(yu)發(fa)(fa)電(dian)(dian)模(mo)(mo)式(shi),隨著(zhu)DNI下降,聚光集熱(re)(re)系統(tong)停(ting)止(zhi)運行(xing),此時(shi)汽輪發(fa)(fa)電(dian)(dian)機(ji)組使用儲(chu)(chu)熱(re)(re)系統(tong)儲(chu)(chu)存的(de)熱(re)(re)量(liang)發(fa)(fa)電(dian)(dian)。
2
本太陽能熱發電站的輸出特性及儲熱調峰能力分析
2.1高輸出功率分析
從電網(wang)角度來看,為有(you)效消(xiao)納大(da)幅增加的(de)風電、光伏發(fa)(fa)電等隨(sui)機性大(da)的(de)可再生能源,其需要配置大(da)量調峰電源。本塔式(shi)太陽能熱(re)發(fa)(fa)電站配備了(le)儲熱(re)系統,能實現(xian)聚光集熱(re)系統和汽(qi)輪(lun)機發(fa)(fa)電系統解耦運(yun)行(xing),使(shi)汽(qi)輪(lun)發(fa)(fa)電機組的(de)輸(shu)出功(gong)率不再受DNI的(de)限制,在各種(zhong)天氣(qi)下(xia)均(jun)可實現(xian)高負荷下(xia)的(de)高功(gong)率輸(shu)出,可作為極好的(de)調峰電源。
為驗(yan)證本太(tai)(tai)陽能熱發電站(zhan)在不同天(tian)氣條件下的輸出特性,選(xuan)取2019年8月8—10日,對(dui)應的天(tian)氣狀態分別為多云(yun)(yun)(厚(hou)云(yun)(yun))、少云(yun)(yun)和(he)晴天(tian),對(dui)本太(tai)(tai)陽能熱發電站(zhan)在這72h內的輸出功率進(jin)行(xing)分析,分析結果如圖(tu)3所(suo)示。
由(you)圖3可知:在(zai)0~24h期(qi)間(jian)(jian),當DNI發(fa)生劇烈變化時,聚光(guang)集熱(re)系統(tong)從(cong)(cong)第13h開始逐漸降(jiang)(jiang)低負荷(he)運行直(zhi)至停機(ji);而在(zai)10~19h期(qi)間(jian)(jian),汽(qi)輪(lun)(lun)發(fa)電(dian)機(ji)組利用熱(re)鹽(yan)罐中的熱(re)量產生蒸(zheng)汽(qi),使自身維持在(zai)高輸(shu)(shu)出(chu)功(gong)(gong)(gong)率(lv)(lv)狀(zhuang)態(平均輸(shu)(shu)出(chu)功(gong)(gong)(gong)率(lv)(lv)大于45MW);然后(hou)隨(sui)(sui)著熱(re)熔(rong)鹽(yan)被消(xiao)耗(hao)至低位值,汽(qi)輪(lun)(lun)發(fa)電(dian)機(ji)組停止運行,本(ben)太陽能熱(re)發(fa)電(dian)站進入停機(ji)模式。在(zai)24~72h期(qi)間(jian)(jian),汽(qi)輪(lun)(lun)發(fa)電(dian)機(ji)組輸(shu)(shu)出(chu)功(gong)(gong)(gong)率(lv)(lv)從(cong)(cong)第32h開始提高,并以(yi)高輸(shu)(shu)出(chu)功(gong)(gong)(gong)率(lv)(lv)狀(zhuang)態維持至第44h時,隨(sui)(sui)著用電(dian)負荷(he)的下降(jiang)(jiang),汽(qi)輪(lun)(lun)發(fa)電(dian)機(ji)組的輸(shu)(shu)出(chu)功(gong)(gong)(gong)率(lv)(lv)維持在(zai)20MW左右。
綜(zong)上(shang)可知,在(zai)本太(tai)陽(yang)能熱(re)(re)發電站連續運行的72h中(zhong),聚光(guang)(guang)集熱(re)(re)系統可與汽(qi)輪機發電系統解耦運行,汽(qi)輪機發電系統不受DNI限制,即使在(zai)多云(yun)天(tian)氣DNI劇烈(lie)變化、早晚光(guang)(guang)照資源(yuan)不理(li)想時,只(zhi)要(yao)熱(re)(re)鹽(yan)罐液位高,本太(tai)陽(yang)能熱(re)(re)發電站仍可實現高負荷穩(wen)定輸(shu)出(chu)。說明(ming)本太(tai)陽(yang)能熱(re)(re)發電站在(zai)太(tai)陽(yang)輻照資源(yuan)波動時,仍具有高輸(shu)出(chu)功(gong)率穩(wen)定輸(shu)出(chu)的能力。
2.2低輸出功率的連續輸出特性
由(you)于本太陽能熱發電站(zhan)的(de)(de)儲熱時長只有7h,無(wu)法滿(man)足汽(qi)輪(lun)(lun)發電機組24h滿(man)負荷運(yun)行的(de)(de)需求,但汽(qi)輪(lun)(lun)發電機組頻繁啟停又會影響其使(shi)(shi)用壽命。因此,本太陽能熱發電站(zhan)采取白天滿(man)功率(lv)發電、夜間降功率(lv)保證汽(qi)輪(lun)(lun)發電機組連續運(yun)行的(de)(de)優(you)化策(ce)略,以(yi)減少(shao)汽(qi)輪(lun)(lun)發電機組的(de)(de)啟停次(ci)數,降低設備頻繁啟停過程產生的(de)(de)熱沖擊,提高汽(qi)輪(lun)(lun)發電機組的(de)(de)使(shi)(shi)用壽命。
為驗證該(gai)策略(lve)有效性,對(dui)本太陽(yang)能熱發電(dian)站(zhan)在2020年2月1—13日(ri)期間連(lian)續(xu)運(yun)行(xing)13天的情況進行(xing)統計,得到該(gai)期間的輸出(chu)功率、熱鹽罐(guan)液位及DNI數(shu)據,如圖4所示。
由圖4可知:連續13天運行(xing)(xing)(xing)期(qi)間(jian),在白(bai)天,本(ben)太陽能熱(re)(re)發電站以儲熱(re)(re)且發電模式(shi)運行(xing)(xing)(xing),當聚光集熱(re)(re)系統停止運行(xing)(xing)(xing)時(shi),汽輪發電機組則(ze)維持在低輸出功率工況運行(xing)(xing)(xing)。
在(zai)運行(xing)的(de)13天中,汽(qi)輪發電(dian)機(ji)組連(lian)續運行(xing)了292.8h,不(bu)間斷(duan)發電(dian)量達(da)(da)8.39GWh,不(bu)間斷(duan)發電(dian)量達(da)(da)成率為105.2%。這(zhe)表明(ming),汽(qi)輪發電(dian)機(ji)組的(de)低輸出功率運行(xing)能力不(bu)僅為本(ben)太陽能熱發電(dian)站(zhan)的(de)發電(dian)量提供了保障(zhang),也為其響應(ying)電(dian)網調度(du)帶來更多(duo)的(de)操作(zuo)空間。
2.3快速變負荷儲熱調峰能力
隨(sui)著可再(zai)生能(neng)(neng)源發電(dian)裝機(ji)容量的(de)增加(jia),電(dian)網(wang)峰(feng)谷差進一(yi)步加(jia)大(da),可再(zai)生能(neng)(neng)源電(dian)力(li)消納(na)能(neng)(neng)力(li)面臨挑戰(zhan),致使出現大(da)量棄(qi)風、棄(qi)光(guang)現象。雖(sui)然火(huo)(huo)電(dian)是重要的(de)調峰(feng)電(dian)源,但火(huo)(huo)電(dian)機(ji)組的(de)調峰(feng)能(neng)(neng)力(li)受鍋(guo)爐燃燒穩定性、水(shui)動力(li)安(an)全性和(he)環保裝置在低負荷運行(xing)下適應性的(de)限制。在傳統(tong)火(huo)(huo)力(li)發電(dian)系(xi)統(tong)中,由(you)于(yu)汽包(bao)的(de)筒體壁(bi)較厚(hou),機(ji)組快速(su)變負荷運行(xing)時,汽包(bao)筒體會產生由(you)內外壁(bi)溫差引(yin)起(qi)的(de)徑向熱應力(li)和(he)外壁(bi)上下溫差引(yin)起(qi)的(de)周向熱應力(li),從(cong)而降低其使用壽(shou)命(ming)。自(zi)然循環形式下,鍋(guo)爐的(de)變負荷速(su)率主要受汽包(bao)壽(shou)命(ming)的(de)限制[18-20]。對于(yu)未進行(xing)靈活(huo)性改造(zao)的(de)火(huo)(huo)電(dian)機(ji)組,其負荷可調范圍(wei)通常為50%~100%,負荷調節率為1%~3%Pe/min[21-22]。
本(ben)太陽能(neng)熱發電(dian)站在(zai)設(she)計(ji)上考慮了汽(qi)(qi)輪(lun)發電(dian)機組的(de)頻(pin)繁啟停和(he)寬負荷(he)調節能(neng)力(li)(li),運行(xing)中可精準控制(zhi)汽(qi)(qi)輪(lun)機發電(dian)系統(tong)的(de)熔鹽流(liu)量和(he)溫(wen)度(du)(du)。該設(she)計(ji)可實現汽(qi)(qi)輪(lun)發電(dian)機組蒸(zheng)汽(qi)(qi)參數(shu)數(shu)值(zhi)的(de)精細化(hua)控制(zhi)和(he)平穩(wen)過渡,降低(di)快(kuai)速(su)變(bian)負荷(he)時溫(wen)度(du)(du)變(bian)化(hua)對(dui)汽(qi)(qi)輪(lun)發電(dian)機組主要設(she)備(bei)的(de)熱沖擊(ji),延長設(she)備(bei)使用(yong)壽命。利用(yong)文獻(xian)[23]中的(de)公式,對(dui)本(ben)太陽能(neng)熱發電(dian)站變(bian)負荷(he)運行(xing)下汽(qi)(qi)包(bao)的(de)循環應力(li)(li)幅值(zhi)進行(xing)計(ji)算。汽(qi)(qi)包(bao)內徑為(wei)1500mm,壁厚為(wei)65mm,材料(liao)為(wei)低(di)合金高強度(du)(du)的(de)13MnNiMoR鋼,計(ji)算結果如表2所示(shi)。
由(you)(you)表2可知:升負(fu)(fu)荷(he)時(shi)汽(qi)包(bao)(bao)的最大循環(huan)(huan)應力幅(fu)值為60.97MPa,降(jiang)負(fu)(fu)荷(he)時(shi)汽(qi)包(bao)(bao)的最大循環(huan)(huan)應力幅(fu)值為83.96MPa。根據文(wen)獻(xian)[24]的研究結(jie)果,汽(qi)包(bao)(bao)壁上的循環(huan)(huan)應力幅(fu)值低于150MPa時(shi),對(dui)其(qi)壽命損(sun)耗很小。由(you)(you)此可得,本太陽(yang)能熱發電站變負(fu)(fu)荷(he)運行時(shi)對(dui)汽(qi)包(bao)(bao)造成的影響較小。
由于本太陽(yang)能熱(re)發電站變(bian)負(fu)荷(he)運行時冷(leng)/熱(re)鹽罐內的(de)冷(leng)/熱(re)鹽溫(wen)度基本不(bu)(bu)變(bian),因此(ci)變(bian)負(fu)荷(he)運行對(dui)儲罐產生(sheng)的(de)熱(re)應力可忽略不(bu)(bu)計(ji)。文獻[24]的(de)研究結果表(biao)明,當主蒸汽溫(wen)度波動不(bu)(bu)超過±25℃時,轉子和氣缸上(shang)不(bu)(bu)會(hui)產生(sheng)有害(hai)熱(re)應力。
根(gen)據本太(tai)陽能熱發電站2019年11月9日的(de)數據,其(qi)變負(fu)荷時主(zhu)蒸(zheng)汽最大溫度波動為-3.720℃(升負(fu)荷)/4.152℃(降負(fu)荷),均小(xiao)于±25℃,因此,可(ke)以(yi)認為在變負(fu)荷運行過(guo)程中汽輪發電機組側產(chan)生的(de)熱應力(li)對其(qi)自身壽命(ming)的(de)影響很(hen)小(xiao)。
根據(ju)文獻(xian)[25],塔式太陽能熱發(fa)電站的負荷(he)(he)調(diao)節范(fan)圍可(ke)(ke)達20%~100%,負荷(he)(he)調(diao)節率(lv)可(ke)(ke)達3%~6%Pe/min。將傳統火電廠(chang)與塔式太陽能熱發(fa)電電站的變負荷(he)(he)能力(li)進行對比(bi),如表3所示。
由表3可(ke)知:變負(fu)荷運行時,塔(ta)式太陽(yang)能(neng)熱(re)發電(dian)站(zhan)在安全性(xing)、環保性(xing)、負(fu)荷調(diao)節范圍和負(fu)荷調(diao)節速率等方面(mian)均(jun)優于(yu)傳(chuan)統火電(dian)廠。
選(xuan)取2019年11月9—10日期間本太陽能熱(re)發電站(zhan)儲(chu)熱(re)調峰時的運行曲線,如(ru)圖5所示。
由圖(tu)5可(ke)知:在夜間時段,本(ben)太陽能(neng)熱發電站維(wei)持在低(di)負荷運行(xing)狀(zhuang)態(tai),但在31h用電高峰(feng)期時卻能(neng)快速升至(zhi)滿功率(lv)運行(xing)狀(zhuang)態(tai)。
2019年11月(yue)9日本太陽能熱發電站儲熱調峰時的(de)升、降(jiang)負荷變化率如圖6所(suo)示。
結(jie)合圖5、圖6可知:在10:44~11:07時(shi)段(duan)(duan)(duan)內,本太(tai)陽(yang)能(neng)(neng)熱發電站的(de)輸出功(gong)率(lv)從(cong)48.82MW降至20.89MW,平(ping)(ping)均(jun)降負(fu)(fu)荷(he)變化(hua)率(lv)為(wei)(wei)(wei)2.32%Pe/min,最大(da)降負(fu)(fu)荷(he)變化(hua)率(lv)為(wei)(wei)(wei)4.72%Pe/min,隨后(hou)維持約20.77MW的(de)低(di)輸出功(gong)率(lv)運(yun)行3.7h。限(xian)功(gong)率(lv)時(shi)段(duan)(duan)(duan)(10:30~15:00)結(jie)束后(hou),本太(tai)陽(yang)能(neng)(neng)熱發電站重新開始升功(gong)率(lv),在14:58~15:17時(shi)段(duan)(duan)(duan)內從(cong)20.77MW升至50.13MW,平(ping)(ping)均(jun)升負(fu)(fu)荷(he)變化(hua)率(lv)為(wei)(wei)(wei)2.94%Pe/min,最大(da)升負(fu)(fu)荷(he)變化(hua)率(lv)為(wei)(wei)(wei)5.02%Pe/min。
根據本太陽能熱(re)發電(dian)站在不同時期的運行結果可以發現,其通過儲熱(re)調峰能夠靈活配(pei)合(he)電(dian)網(wang)調度時的快(kuai)速變負荷需求。
結合(he)光伏(fu)發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)、風(feng)電(dian)(dian)(dian)(dian)(dian)及太陽(yang)(yang)能熱發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)的(de)輸出(chu)特性可(ke)知(zhi),本太陽(yang)(yang)能熱發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)站(zhan)可(ke)以(yi)在光伏(fu)發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)、風(feng)力(li)發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)高峰期時,快速(su)降功率(lv)運(yun)行(xing);而在光伏(fu)發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)、風(feng)力(li)發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)處(chu)于谷值(zhi)時,快速(su)升(sheng)功率(lv)運(yun)行(xing),使電(dian)(dian)(dian)(dian)(dian)網(wang)最大(da)限度地消納光伏(fu)發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)和風(feng)電(dian)(dian)(dian)(dian)(dian),成為(wei)穩定的(de)儲熱調(diao)峰電(dian)(dian)(dian)(dian)(dian)源(yuan),承(cheng)擔調(diao)峰電(dian)(dian)(dian)(dian)(dian)源(yuan)削(xue)峰填谷的(de)作用,與(yu)光伏(fu)發(fa)(fa)(fa)(fa)電(dian)(dian)(dian)(dian)(dian)和風(feng)電(dian)(dian)(dian)(dian)(dian)等(deng)可(ke)再生能源(yuan)電(dian)(dian)(dian)(dian)(dian)力(li)實(shi)現良(liang)好的(de)互補。
3
結論
塔式太陽能熱發電站具有零碳排放、調峰靈活、相對調峰幅度大等優點,可以較好地滿足電網對調峰電源的要求。本文以青海省某商業化運行的50MW塔式太陽能熱發電站為研究對象,對其組成部分、運行模式、輸出特性及儲熱調峰能力進行了分析。得到以下結論:
1)該太(tai)陽能熱發電(dian)(dian)站可克服光伏(fu)發電(dian)(dian)、風(feng)電(dian)(dian)的隨機(ji)性(xing)、波動性(xing)缺點(dian),在多云天氣下(xia)仍能維持穩定高功(gong)率(lv)(lv)輸(shu)出,同(tong)時其還能根據用電(dian)(dian)需求靈活、快速(su)調整輸(shu)出功(gong)率(lv)(lv),并維持低功(gong)率(lv)(lv)持續運行,表現出良好(hao)能量調節能力。
2)該太陽能熱(re)發(fa)(fa)電(dian)(dian)(dian)站(zhan)可以在光伏發(fa)(fa)電(dian)(dian)(dian)、風力(li)發(fa)(fa)電(dian)(dian)(dian)高峰(feng)期(qi)時,快(kuai)(kuai)速降功(gong)率運行(xing);而在光伏發(fa)(fa)電(dian)(dian)(dian)、風力(li)發(fa)(fa)電(dian)(dian)(dian)處于谷值(zhi)時,快(kuai)(kuai)速升(sheng)功(gong)率運行(xing),使電(dian)(dian)(dian)網(wang)最大限度地消納光伏發(fa)(fa)電(dian)(dian)(dian)和(he)風電(dian)(dian)(dian)。
研(yan)究結果可(ke)為參與電(dian)網調(diao)峰的(de)大規模(mo)商業(ye)化塔式太陽能熱發(fa)電(dian)站的(de)設計和運行提(ti)供理論支撐。
參考文獻
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