自20世(shi)(shi)紀(ji)20年代(dai)(dai)(dai)起,高壓直流(liu)輸電(dian)(dian)技(ji)術(shu)經歷了三次技(ji)術(shu)革(ge)新,其(qi)主(zhu)要(yao)推(tui)動(dong)力來自換流(liu)器(qi)基本元件的(de)重大(da)變化。第(di)一代(dai)(dai)(dai)直流(liu)輸電(dian)(dian)技(ji)術(shu)采(cai)用的(de)換流(liu)元件是(shi)汞弧閥,其(qi)換流(liu)器(qi)拓撲是(shi)6脈動(dong)Graetz橋,主(zhu)要(yao)應用于20世(shi)(shi)紀(ji)70年代(dai)(dai)(dai)以前。第(di)二代(dai)(dai)(dai)直流(liu)輸電(dian)(dian)技(ji)術(shu)采(cai)用的(de)換流(liu)元件是(shi)晶(jing)閘管,其(qi)換流(liu)器(qi)拓撲與第(di)一代(dai)(dai)(dai)直流(liu)輸電(dian)(dian)技(ji)術(shu)相同,主(zhu)要(yao)在20世(shi)(shi)紀(ji)70年代(dai)(dai)(dai)初至20世(shi)(shi)紀(ji)90年代(dai)(dai)(dai)得以應用。
基(ji)于可控關(guan)斷(duan)器(qi)件的第三代直(zhi)(zhi)流(liu)(liu)(liu)輸(shu)電技(ji)術誕生于20世紀90年代初(chu),被國際(ji)權威(wei)學術組織命名為(wei)“電壓源(yuan)換流(liu)(liu)(liu)器(qi)型直(zhi)(zhi)流(liu)(liu)(liu)輸(shu)電”(VSC-HVDC),又稱為(wei)“輕型直(zhi)(zhi)流(liu)(liu)(liu)輸(shu)電”(HVDC Light)、“新型直(zhi)(zhi)流(liu)(liu)(liu)輸(shu)電”(HVDC Plus)。我國將此技(ji)術命名為(wei)“柔性直(zhi)(zhi)流(liu)(liu)(liu)輸(shu)電”。
柔性(xing)直流輸電(dian)(dian)技(ji)術(shu)是當今電(dian)(dian)網科(ke)技(ji)領域(yu)具革命性(xing)和(he)挑戰性(xing)的一項嶄新技(ji)術(shu),其可控性(xing)好、適應性(xing)強、運(yun)行方式靈活(huo)、適用(yong)場合多,在(zai)新能(neng)源(yuan)消納和(he)智能(neng)電(dian)(dian)網建設中具有廣闊(kuo)的應用(yong)前景。
有何技術特點——有效控制系統中的電流,快速切除和隔離故障,更加靈活地響應電網需求
柔性直(zhi)流(liu)(liu)輸電(dian)(dian)是(shi)采用可(ke)自關斷的全控型電(dian)(dian)力(li)電(dian)(dian)子器件(如IGBT等)的新(xin)一代(dai)直(zhi)流(liu)(liu)輸電(dian)(dian)技(ji)術。在電(dian)(dian)網中應用柔性直(zhi)流(liu)(liu)輸電(dian)(dian)技(ji)術,相(xiang)當于(yu)在電(dian)(dian)網中接入了(le)電(dian)(dian)源(yuan)和閥門,不僅能有效控制(zhi)系(xi)統中的電(dian)(dian)流(liu)(liu),快速(su)切除和隔(ge)離(li)故障,還可(ke)以更加靈活地響應電(dian)(dian)網需求。
與傳(chuan)統(tong)(tong)(tong)直(zhi)(zhi)流輸電(dian)(dian)技(ji)(ji)術(shu)(shu)(shu)相比,柔(rou)性直(zhi)(zhi)流輸電(dian)(dian)技(ji)(ji)術(shu)(shu)(shu)的“柔(rou)性特質”有(you)(you)哪些具體表現(xian)(xian)?一是(shi)具有(you)(you)動(dong)態(tai)無(wu)功支撐能力,可(ke)有(you)(you)效抑制電(dian)(dian)壓(ya)波(bo)動(dong);二(er)是(shi)不存在(zai)換相失敗(bai)問題(ti),可(ke)接入弱電(dian)(dian)網(wang)(wang),可(ke)為(wei)無(wu)源系統(tong)(tong)(tong)供電(dian)(dian),適(shi)用(yong)于(yu)孤(gu)島、海上新能源并網(wang)(wang);三是(shi)可(ke)實(shi)現(xian)(xian)有(you)(you)功功率(lv)和無(wu)功功率(lv)的獨(du)立控制,控制方(fang)式更加(jia)可(ke)靠靈活;四是(shi)潮流反(fan)轉迅速(su),易于(yu)構建多端直(zhi)(zhi)流系統(tong)(tong)(tong)或直(zhi)(zhi)流電(dian)(dian)網(wang)(wang);五是(shi)在(zai)同等電(dian)(dian)壓(ya)容量的條件下(xia)占(zhan)地(di)面(mian)積小(xiao),且(qie)規避了諧波(bo)大、交直(zhi)(zhi)流濾波(bo)器占(zhan)地(di)大等缺點。然而,由于(yu)元器件和調制技(ji)(ji)術(shu)(shu)(shu)的限制,柔(rou)性直(zhi)(zhi)流輸電(dian)(dian)技(ji)(ji)術(shu)(shu)(shu)也(ye)存在(zai)損(sun)耗較(jiao)(jiao)大、設備成本較(jiao)(jiao)高及容量相對較(jiao)(jiao)小(xiao)等不足。
綜(zong)合考慮上(shang)述技(ji)(ji)術特點,柔性直流(liu)輸電技(ji)(ji)術在提(ti)升(sheng)電力系統穩定性、提(ti)高配電網(wang)的(de)靈活性、增(zeng)強電網(wang)對(dui)清潔(jie)能源的(de)消納能力等方(fang)面有顯(xian)著優勢(shi),為解(jie)決多(duo)端直流(liu)聯網(wang)、緩解(jie)城市集(ji)群負荷(he)壓力等提(ti)供(gong)了(le)全新的(de)技(ji)(ji)術方(fang)案。這一技(ji)(ji)術是(shi)實現孤島供(gong)電、海(hai)上(shang)風電傳輸的(de)可(ke)靠和(he)有效(xiao)技(ji)(ji)術手段(duan),也是(shi)構建多(duo)種(zhong)形態能源互聯網(wang)與智能電網(wang)的(de)有力選擇。
我國應用實踐——在大電網互聯、海上風電輸送、大規模可再生能源并網等領域迅速發展
國家電網公司(si)于2006年提出柔(rou)性(xing)(xing)直(zhi)(zhi)流(liu)(liu)輸電技(ji)(ji)術(shu)總(zong)體規劃(hua),正式啟動(dong)柔(rou)性(xing)(xing)直(zhi)(zhi)流(liu)(liu)輸電重大科技(ji)(ji)專(zhuan)項。在這一(yi)規劃(hua)的指導下,國網經(jing)濟技(ji)(ji)術(shu)研究院迅速響應(ying)并組建了(le)柔(rou)性(xing)(xing)直(zhi)(zhi)流(liu)(liu)技(ji)(ji)術(shu)攻關團隊,針對柔(rou)性(xing)(xing)直(zhi)(zhi)流(liu)(liu)輸電成套技(ji)(ji)術(shu)開展系統化研究。歷經(jing)十余年科研攻關與(yu)創(chuang)新實(shi)(shi)踐(jian),我國已完全掌握了(le)柔(rou)性(xing)(xing)直(zhi)(zhi)流(liu)(liu)成套技(ji)(ji)術(shu),并不(bu)斷在實(shi)(shi)際工程中應(ying)用實(shi)(shi)踐(jian),取(qu)得多個“世界首創(chuang)”,有力推(tui)動(dong)了(le)柔(rou)性(xing)(xing)直(zhi)(zhi)流(liu)(liu)裝備國產化及相關產業鏈(lian)的全面進步。
2014年(nian)(nian),±200千伏舟山多端柔(rou)性直流(liu)(liu)(liu)輸電(dian)(dian)(dian)(dian)科技(ji)(ji)示范(fan)工(gong)程(cheng)即世(shi)界首個五端柔(rou)性直流(liu)(liu)(liu)輸電(dian)(dian)(dian)(dian)工(gong)程(cheng)成功投運(yun),舟山群島實現電(dian)(dian)(dian)(dian)網(wang)互聯和可靠供電(dian)(dian)(dian)(dian)。這是(shi)柔(rou)性直流(liu)(liu)(liu)成套技(ji)(ji)術自主化(hua)的首次應用(yong),標(biao)志著(zhu)我國在柔(rou)性直流(liu)(liu)(liu)輸電(dian)(dian)(dian)(dian)技(ji)(ji)術領域(yu)取得(de)重大突(tu)破。2015年(nian)(nian)年(nian)(nian)底,廈門±320千伏柔(rou)性直流(liu)(liu)(liu)輸電(dian)(dian)(dian)(dian)科技(ji)(ji)示范(fan)工(gong)程(cheng)正式投入運(yun)行。這是(shi)世(shi)界第一個采(cai)用(yong)對稱雙極(ji)接(jie)線方案的柔(rou)性直流(liu)(liu)(liu)輸電(dian)(dian)(dian)(dian)工(gong)程(cheng),攻克了高壓大容量柔(rou)性直流(liu)(liu)(liu)輸電(dian)(dian)(dian)(dian)多項關鍵技(ji)(ji)術難關。
與(yu)此同時,我國(guo)柔(rou)性(xing)直(zhi)流(liu)(liu)(liu)(liu)輸(shu)電(dian)(dian)(dian)技(ji)術(shu)(shu)在(zai)大電(dian)(dian)(dian)網(wang)(wang)互(hu)聯、海(hai)上(shang)(shang)(shang)風(feng)電(dian)(dian)(dian)輸(shu)送、大規(gui)模可再(zai)生(sheng)能(neng)源(yuan)(yuan)并網(wang)(wang)等領域迅速(su)發(fa)展。2018年(nian)(nian),渝(yu)鄂背(bei)(bei)靠背(bei)(bei)柔(rou)性(xing)直(zhi)流(liu)(liu)(liu)(liu)聯網(wang)(wang)工(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)投運,在(zai)世界(jie)上(shang)(shang)(shang)首(shou)次將柔(rou)性(xing)直(zhi)流(liu)(liu)(liu)(liu)輸(shu)電(dian)(dian)(dian)電(dian)(dian)(dian)壓提升至±420千(qian)伏。該(gai)工(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)輸(shu)送容量達到500萬(wan)千(qian)瓦,有(you)效提高了川渝(yu)電(dian)(dian)(dian)網(wang)(wang)與(yu)華中(zhong)電(dian)(dian)(dian)網(wang)(wang)間的(de)(de)互(hu)濟能(neng)力,促進了西南水電(dian)(dian)(dian)的(de)(de)開發(fa)和(he)大規(gui)模外送。2019年(nian)(nian),江蘇如東(dong)和(he)射陽(yang)海(hai)上(shang)(shang)(shang)風(feng)電(dian)(dian)(dian)柔(rou)性(xing)直(zhi)流(liu)(liu)(liu)(liu)工(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)啟(qi)動,這(zhe)兩項工(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)是(shi)我國(guo)首(shou)批(pi)海(hai)上(shang)(shang)(shang)風(feng)電(dian)(dian)(dian)經柔(rou)性(xing)直(zhi)流(liu)(liu)(liu)(liu)送出項目(mu)。2019年(nian)(nian)12月24日(ri),世界(jie)首(shou)個柔(rou)性(xing)直(zhi)流(liu)(liu)(liu)(liu)電(dian)(dian)(dian)網(wang)(wang)——張北柔(rou)性(xing)直(zhi)流(liu)(liu)(liu)(liu)電(dian)(dian)(dian)網(wang)(wang)試驗示范(fan)工(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)完(wan)成工(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)建設(she)、全線(xian)架通,計劃在(zai)2020年(nian)(nian)投入運行。該(gai)工(gong)(gong)(gong)(gong)程(cheng)(cheng)(cheng)以柔(rou)性(xing)直(zhi)流(liu)(liu)(liu)(liu)輸(shu)電(dian)(dian)(dian)為核心(xin)技(ji)術(shu)(shu),實現了大規(gui)模可再(zai)生(sheng)能(neng)源(yuan)(yuan)匯集(ji)與(yu)接入、多(duo)種形態能(neng)源(yuan)(yuan)互(hu)補與(yu)消納(na)、交直(zhi)流(liu)(liu)(liu)(liu)電(dian)(dian)(dian)網(wang)(wang)構建等諸多(duo)新技(ji)術(shu)(shu)融合,是(shi)柔(rou)性(xing)直(zhi)流(liu)(liu)(liu)(liu)輸(shu)電(dian)(dian)(dian)技(ji)術(shu)(shu)發(fa)展史上(shang)(shang)(shang)的(de)(de)里程(cheng)(cheng)(cheng)碑。
未來發展之路——應用場景和范圍廣闊,為傳統輸電方式轉換和大電網發展帶來全新變革
從(cong)世界范圍來看,能源(yuan)形勢正(zheng)在發生深刻變革(ge),全(quan)(quan)球電(dian)網(wang)將朝(chao)著智(zhi)能控制、多能互補、環(huan)保高(gao)效的方向發展。柔性直流(liu)輸電(dian)技(ji)術作(zuo)為當今世界前(qian)沿的電(dian)網(wang)技(ji)術,在新(xin)一代能源(yuan)革(ge)命及全(quan)(quan)球電(dian)網(wang)建設中扮演著愈發重要的角(jiao)色。
目前,世界各國(guo)(guo)已(yi)認識到柔性直流輸電技術的獨特優(you)勢及巨大的市(shi)(shi)場價值(zhi)。柔性直流輸電工程在歐美快速發展,美國(guo)(guo)、英國(guo)(guo)、德國(guo)(guo)等國(guo)(guo)在未來幾年(nian)內規劃了(le)多達50項柔性直流工程,柔性直流輸電工程的市(shi)(shi)場規模逐(zhu)漸擴大。
伴隨(sui)著新型換流(liu)(liu)閥的(de)應用、控(kong)制(zhi)技術的(de)發(fa)展(zhan)、換流(liu)(liu)器拓撲結構(gou)的(de)升(sheng)級(ji)和(he)直流(liu)(liu)保護手段(duan)的(de)突(tu)破,柔(rou)性(xing)直流(liu)(liu)輸電工程(cheng)的(de)電壓(ya)等級(ji)和(he)輸送容(rong)量將會不斷提升(sheng),而工程(cheng)造(zao)價有望顯著下降(jiang),柔(rou)性(xing)直流(liu)(liu)輸電技術的(de)應用場(chang)景和(he)范(fan)圍(wei)將更(geng)(geng)加(jia)廣(guang)闊(kuo)。此外,隨(sui)著新能源、柔(rou)性(xing)直流(liu)(liu)和(he)交流(liu)(liu)系統(tong)交互影(ying)響(xiang)機理研究的(de)日(ri)益(yi)深入,柔(rou)性(xing)直流(liu)(liu)輸電技術將在“源-網-荷-儲”一體(ti)化模(mo)式中發(fa)揮更(geng)(geng)加(jia)重要的(de)協調(diao)作用,為傳(chuan)統(tong)輸電方式的(de)轉換和(he)大(da)電網發(fa)展(zhan)帶來(lai)全新變革(ge)。
我國(guo)始終堅持自(zi)主(zhu)創新(xin)道路(lu),已(yi)全(quan)面完成了柔(rou)性直(zhi)流輸(shu)電(dian)技(ji)(ji)術從追(zhui)趕到(dao)引領的(de)跨越(yue)式發展,并向(xiang)高電(dian)壓、大功(gong)率、多(duo)(duo)端、雙極、背(bei)靠(kao)背(bei)、混合直(zhi)流輸(shu)電(dian)、新(xin)能源并網、孤島接入、海上風(feng)電(dian)外送等多(duo)(duo)個(ge)方向(xiang)開展探索與實(shi)踐。我國(guo)自(zi)主(zhu)研(yan)發的(de)柔(rou)性直(zhi)流技(ji)(ji)術及工程應用成果得(de)到(dao)了國(guo)際社會的(de)廣(guang)泛關注。隨(sui)著“一(yi)帶一(yi)路(lu)”建設的(de)深入推進,我國(guo)將越(yue)來(lai)越(yue)多(duo)(duo)地參與到(dao)全(quan)球電(dian)網建設中,柔(rou)性直(zhi)流輸(shu)電(dian)技(ji)(ji)術也會成為我國(guo)電(dian)力技(ji)(ji)術“走出去”的(de)閃亮名片。