直流輸電_-6uhvdc第六章特高壓

1、高壓直流輸電第六章 特高壓直流輸電毛承雄2010年10月22Ultra High Voltage 800kV DC The first 800kV HVDC (Yunnan-Guangdong) in the world successfully operated with monopole in Dec. 28, 2009. The transmission line is 1425km long, and operated with bipolar of capacity of 5000MW in June 2010.33800kV UHVDC from Xiangjiaba to Sha

2、nghai put into service in July 2010.44800 kV DC converter transformers800 kV DC transmission Line800 kV DC transmission Line800 kV DC converter station55Power Resources and Load Center80% hydropower2/3 Coal ResourcesLoad CenterTwo-thirds of the coal reserves are located in the North and 80% of the h

3、ydropower reserves are located in the West. These energy sources are far removed from the energy demands located in the eastern areas 800 km to 3000 km away.6UHVAC： 定位于更高一級電壓等級的網(wǎng)架建設(shè)和跨大區(qū)聯(lián)網(wǎng)送電UHVDC： 定位于我國西部大水電基地和大煤電基地的超遠距離超大容量的電力外送UHVAC： 1200km UHVDC優(yōu)于UHVAC 1400km UHVDC優(yōu)勢更明顯7Increase transmission capac

4、ity One 1000-kV circuit transmits about 5 GW, approximately 5 times that of a 500kV transmission line. An 800kV dc transmission line has the capacity of 6.4 GW, which is 2.1 times that of a 500kV dc power line.Extend transmission distance A 1000kV ac line can economically transmit power distances of

5、 1000 km to 2000km. An 800kV dc power line can economically transmit power over distances of 2000 km to 3000 km.Reduce transmission losses If the conductor cross-sectional area and transmission power are held constant, the resistance losses of a 1000kV ac power line is 25% that of the 500kV ac power

6、 line. The resistance loss of 800kV dc transmission line is about 39% that of a comparable 500kV dc line.Reduce costs The cost per unit of transmission capacity of 1000kV ac and 800kV dc transmission scheme are 73% and 72% that of 500kV ac and 500kV dc schemes, respectively.Reduce land requirements

7、A 1000-kV ac line power line saves 50% to 66% of the corridor area that a 500kV ac line would require. An 800kV dc line would save 23% of the corridor area required by a 500kV dc line.UHV Strategy8UHVDC運行方式500kV雙極直流輸電系統(tǒng)9已設(shè)計出：49種運行方式（功率正送和功率反送）完整雙極運行方式雙極運行方式 某一極的12個換流器故障退出雙極運行 每極1對換流器投入，400kV雙極運行完整單極

8、運行方式 正極金屬回線，負極金屬回線，正極大地回線，負極大地回線單極運行 只有一個極一個換流器運行，400kV單極運行OLT（Open Line Test）試驗方式 8種雙極運行21種完整雙極 1；雙極 4； 雙極 16種單極運行20種完整單極 4； 單極 16種OLT試驗 8種特高壓極線充電試驗10串聯(lián)換流器投切時序 UHVDC每個極有兩個換流器串聯(lián)，如何控制各個換流器的投切是UHVDC的一個難點。1112脈動換流器正常投入初始狀態(tài)：12脈動換流器處于閉鎖狀態(tài)，無電流流過，旁路斷路器閉合閉合兩臂隔離開關(guān)和換流器變壓器斷路器，打開隔離旁路開關(guān)，使電流流過直流斷路器解鎖換流器，使之運行處于輕微逆變狀態(tài)，電流同時流過環(huán)流變壓器斷路器和隔離開關(guān)設(shè)置電流指令為實際直流電流，逐步減小至90o，維持換流器；兩端電壓為0，斷開旁路斷路器，改變觸發(fā)角度使12脈動換流器兩端電壓達到正常運行工況，12脈動換流器正常投入1212脈動換流器正常切除閉合旁路開關(guān)，斷開換流器變壓器斷路器，打開換流器兩臂隔離旁路開關(guān)， 12脈動換流器退出運行設(shè)置換流器的電流指令為0，不投旁通對閉鎖換流器逐步降低/增加換流器觸發(fā)角至90o，使12脈動換流器兩端電壓維持為0，閉合旁路斷路器，電流同時流過環(huán)流變壓器斷路器和隔離開關(guān)13故障情況下12脈動換流器切