Ultra high voltage (UHV) refers to power transmission technology with alternating current (AC) voltage levels of 1000 kilovolts or more and direct current (DC) of ±800 kilovolts or more, a definition by China. Other countries may have different thresholds. China commissioned first such power transmission line in 2008. As of March 2025, 42 UHV power transmission lines were operating, half of which with AC and half with DC.

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Technology

Abbreviations

　　UHVDC --超高压直流输电(ultra-high-voltage direct current)

　　UHVAC-- 超高压交流输电( ultra-high-voltage alternating current)

　　HVDC--高压直流电(High-voltage direct current)

The advantages of UHV

large transmission capacity
long transmission distance
low line loss
space saving
Improved Efficiency: The application of ultra-high voltage technology allows an effective increase in transmission efficiency, reducing interference caused by external and internal factors. Besides, it does not require reactive compensation, unlike traditional power transmission models, which may be limited by thermal resistance problems in the high voltage cables, which affects the stability of the transmission.
Greater Reliability and Stability: Ultra high voltage transmission is more reliable and stable, Effectively avoiding wasting energy during transmission. Even in adverse conditions, it can meet high power transmission demands, something that traditional methods cannot match.
Costs reduction: The application of ultra-high voltage transmission technology allows a significant reduction in power transmission costs. According to data, The transmission capacity of ultra-high voltage lines is more than three times higher compared to conventional transmission lines. This means that under the same transmission conditions, ultra-high-voltage networks can reduce electricity grid costs by 90%.
Balance in Energy Distribution: Promotion of ultra-high voltage transmission technology can achieve a balance in electric power distribution, benefiting various regions and ensuring equitable distribution of energy.

The disadvantages of UHV

Impact on Human Health: There is a debate in the scientific community about the impact of ultra-high voltage on human health. A definitive conclusion has not yet been reached and a more complete data analysis is required.. Fortunately, Most ultra-high voltage transmission lines are located in areas far from inhabited areas., which limits direct contact with the population.
Need for Continuous Innovation: Despite significant advances in ultra-high voltage transmission technology and its promising future in the electrical sector, it is necessary to continue innovating based on the changing demands of energy transmission. The rapid evolution of electrical technologies implies the need to research and develop products such as lightning arresters and transformers in accordance with power transmission requirements.
Vulnerable for natural disasters and the terrorism attack, especially the DC transmission lines. ((need to add more from the debate))
Expensive on constructing such a line.

Background

Who invented UHV?

The former Soviet Union launched the first 907 kilometers long UHV transmission line, connecting the towns of Ekibastuz and Kokchetav in Kazakhstan in September 1985 with a voltage of 1150 kV. It was downgraded to a common 500 kV after the dismantlement of the Soviet Union in 1991.

Besides China, which countries have developed UHV transmission lines?

India
Japan.
Brazil
Italy
UK

When did China adopt the technology?

Since 2004, China began large scale experiment on UHV. In 2006, the first such line, Southeastern Shanxi - Nanyang - Jingmen UHV was permitted for construction and went operational in 2008.

UHV Transmission Line Network details

Four stages of UHV development in China

2008-2014 Mainly hydro and coal power transmission 以煤电传输开端，以水电传输为主.
2015-2019 In order to improve the air quality in major cities, UHV permitting and construction accelerated, aiming to replace coal use in the areas. 改善大气环境, 输电代替输煤.
2020-2024 Establish and strengthen UHV regional power grid 建立并加强特高压局域电网.
2023- Accelerate providing access to renewable energy 为可再生能源提供通道.

Table 1: UHV projects commissioned between 2008-2014.

UHV Power Tansmission Line	UHV Tansmission Line in Chinese	Other name	Status	Commissioned Year	Capacity 额定输送容量 (MW)	Technology	Transmission Distance（km）	circuit	Investment (Billion RMB）	Permitted Date	Ultimate Parent	Start Region	End Region
Anhui South- Zhejiang North- Shanghai	皖电东送淮南-浙北-上海特高压交流输电示范工程	皖电东送	operating	2013-08-01	10500	1000 kV Ultra-AC	648.7	2	18.5	2012-09	State Grid	Anhui	Shanghai
Southeastern Shanxi - Nanyang - Jingmen	晋东南--南阳--荆门1000千瓦特高压交流实验示范工程		operating	2008-01	5000	1000 kV Ultra-AC	645		5.887	2006-8	State Grid	Shanxi	Hubei
Xiangjiaba-Shanghai	向家坝-上海±800千伏特高压直流输电示范工程	复奉直流	operating	2010	6400	±800 kV Ultra-DC	1907		23.274	2007-04-26	State Grid	Sichuan	Shanghai
Jinping-Jiangsu South	锦屏-苏南 ±800千伏特高压直流输电工程	锦苏直流	operating	2012-12-21	7200	±800 kV Ultra-DC	2059		22	2008-11	State Grid	Sichuan	Jiangsu
Xiluodu-Zhejiang	溪洛渡-浙江±800千伏特高压直流输电工程	宾金直流, 溪浙工程	operating	2014-07	8000	±800 kV Ultra-DC	1680		23.855	2012-07	State Grid	Sichuan	Zhejiang
Hami South -- Zhengzhou	哈密南--郑州±800千伏特高压直流输电工程	天中直流，哈郑直流，疆电外送第三通道	operating	2014	8000	±800 kV Ultra-DC	2210		23.4	2012-5	State Grid	Xinjiang	Henan
Yunnan-Guangdong	云南楚雄-广东惠东（云广±800千伏特高压直流输电工程）	楚穗直流，云广直流	operating	2010	5000	±800 kV Ultra-DC	1373		13.2	2006	China Southern Power Grid	Yunnan	Guangdong
Nuozhadu-Guangdong	糯扎渡送电广东±800kV直流输电工程（云南普洱-广东江门）	普侨直流	operating	2013	5000	±800 kV Ultra-DC	1413		13.3	2011-10	China Southern Power Grid	Yunnan	Guangdong
Zhejiang North-Zhejiang Middle-Zhejiang South-Fuzhou	浙北-福州1000千伏特高压交流输变电工程	浙福特高压	operating	2014-12-26	6800	1000 kV Ultra-AC	603	2	18.87	2013-03	State Grid	Zhejiang	Fujian

Table 2: UHV projects commissioned 2015-2019.

UHV Power Tansmission Line	UHV Tansmission Line in Chinese	Other name	Status	Commissioned Year	Capacity 额定输送容量 (MW)	Technology	Transmission Distance（km）	circuit	Investment (Billion RMB）	Permitted Date	Ultimate Parent	Start Region	End Region
Anhui South- Nanjing- Shanghai	皖电东送淮南-南京-上海1000千伏特高压交流输变电项目	皖电东送	operating	2019-09-26	6000	1000 kV Ultra-AC	779.5	2	26.1	2014-4-21	State Grid	Anhui	Jiangsu
Jiuquan- Hunan	酒泉-- 湖南+-800千伏特高压直流输电工程 (陇电入湘)	祁韶直流，酒湖工程	operating	2017-6	8000	±800 kV Ultra-DC	2383		26.2	2015-5-18	State Grid	Gansu	Hunan
Xiong'an-Shijiazhuang	雄安-石家庄1000千伏特高压交流工程（北京西-石家庄交流特高压输变电工程）		operating	2019-06-04		1000 kV Ultra-AC	228	2	3.5	2017-07	State Grid	Hebei	Hebei
Xilingol-Shengli	锡盟-胜利特高压交流输电工程		operating	2017-7	3000	1000 kV Ultra-AC	240	2	4.956	2016-01	State Grid	Inner Mongolia	Inner Mongolia
Xilingol- Jiangsu	锡盟-泰州±800千伏特高压直流工程	锡泰直流	operating	2017－8	10000	±800 kV Ultra-DC	1619		26.4	2015-10-30	State Grid	Inner Mongolia	Jiangsu
Xilingol- Shandong	锡盟--山东1000千伏特高压交流输变电工程		operating	2016 - 8	9000	1000 kV Ultra-AC	730	2	17.8	2014-7-12	State Grid	Inner Mongolia	Shandong
Western Mongolia- Tianjin	蒙西-天津南1000千伏特高压交流输变电工程		operating	2019-01-11	6000	1000 kV Ultra-AC	608	2	17.5	2015-1	State Grid	Inner Mongolia	Tianjin
Shanghai Temple- Shandong	上海庙--山东临沂±800千伏特高压直流输电工程	昭沂直流	operating	2019	10000	±800 kV Ultra-DC	1238		22.1	2015-12	State Grid	Inner Mongolia	Shandong
Jarud- Shandong Qingzhou	扎鲁特--山东青州±800千伏特高压直流输电工程（鲁固直流项目）	鲁固直流	operating	2017-12-31	10000	±800 kV Ultra-DC	1234		22.1	2016-8	State Grid	Inner Mongolia	Shandong
Eastern Ningxia- Zhejiang	宁东-浙江±800千伏特高压直流输电工程 (灵州-绍兴±800千伏特高压直流输电工程)	灵绍直流	operating	2016-08-01	8000	±800 kV Ultra-DC	1720		23.7	2014-8-5	State Grid	Ningxia	Zhejiang
Yuheng- Weifang	榆横--潍坊1000千伏特高压交流输变电工程		operating	2017-08	6000	1000 kV Ultra-AC	1049	2	24.2	2015-5	State Grid	Shaanxi	Shandong
Northern Shanxi- Nanjing	晋北--江苏±800千伏特高压直流输电工程（雁门关-淮安特高压直流输电工程）	雁淮直流	operating	2017-07	8000	±800 kV Ultra-DC	1119		16.2	2015-6-10	State Grid	Shanxi	Jiangsu
Zhundong - Southern Anhui	准东--皖南+-1100千伏特高压直流输电工程	吉泉直流，疆电外送第四通道	operating	2019	12000	1100 kV Ultra-DC	3324		40.7	2015-12-28	State Grid	Xinjiang	Anhui
Yunnan Northwest-Guangdong	滇西北—广东±800千伏直流输电工程（丽江—深圳±800千伏特高压直流线路）	新东直流	operating	2018-05-18	5000	±800 kV Ultra-DC	1953		17	2015-12-28	China Southern Power Grid	Yunnan	Guangdong

Table 3: UHV projects commissioned 2020-2024.

UHV Power Tansmission Line	UHV Tansmission Line in Chinese	Other name	Status	Commissioned Year	Capacity 额定输送容量 (MW)	Technology	Transmission Distance（km）	circuit	Investment (Billion RMB）	Permitted Date	Ultimate Parent	Start Region	End Region
Fuzhou-Xiamen	福州-厦门1000千伏特高压交流输电工程		operating	2023-12-16		1000 kV Ultra-AC	234	2	7.1	2022-01	State Grid	Fujian	Fujian
Gansu East- Shandong	陇东-山东特高压直流工程（陇电入鲁）	陇电入鲁	operating	2024-12	8000	±800 kV Ultra-DC	926		20.2	2023-2	State Grid	Gansu	Shandong
Zhangbei-Shengli	张北-胜利1000千伏特高压输电交流项目		operating	2024-10-31		1000 kV Ultra-AC	366	2	6.786	2022-09-15	State Grid	Hebei	Inner Mongolia
Zhangbei-Xiong'an	张北-雄安1000千伏特高压交流输变电工程		operating	2020-08-29	6000	1000 kV Ultra-AC	319	2	5.98	2018-11	State Grid	Hebei	Hebei
Zhumadian-Nanyang	驻马店-南阳1000千伏特高压交流输电工程		operating	2020-06-06		1000 kV Ultra-AC	188.4	2	2.16	2018-12-10	State Grid	Henan	Henan
Zhumadian-Wuhan	驻马店-武汉1000千伏特高压交流输电工程		operating	2023-11-27		1000 kV Ultra-AC	287	2	3.8	2021-11-17	State Grid	Henan	Hubei
Nanyang-Jingmen-Changsha	南阳～荆门～长沙1000kV特高压交流输变电工程		operating	2022-10	6000	1000 kV Ultra-AC	625.8			2021-4-1	State Grid	Henan	Hunan
Jingmen-Wuhan	荆门—武汉1000千伏特高压交流输变电工程		operating	2022-12-28		1000 kV Ultra-AC	234		6.5	2020-12-23	State Grid	Hubei	Hubei
Wuhan-Nanchang	武汉至南昌1000千伏特高压交流线路工程		operating	2023-12-27		1000 kV Ultra-AC	462.9	2	9.082	2022-6-27	State Grid	Hubei	Jiangxi
Western Mongolia-Mid Shanxi	蒙西-晋中1000千伏特高压交流工程		operating	2020-09	8000	1000 kV Ultra-AC	313	2	5.4	2018-03	State Grid	Inner Mongolia	Shanxi
Nanchang-Changsha	南昌-长沙1000千伏特高压交流输电工程		operating	2021-12-26		1000 kV Ultra-AC	341	2	10.2	2020-12-22	State Grid	Jiangxi	Hunan
Qinghai-Henan	青海—河南±800千伏特高压直流输电工程（青豫直流）	青豫直流	operating	2020-12-30	8000	±800 kV Ultra-DC	1587		22.3	2018-10	State Grid	Qinghai	Henan
North of Shaanxi-Hubei Wuhan	陕北-湖北±800千伏特高压直流工程	陕武直流	operating	2021	8000	±800 kV Ultra-DC	1137		18.5	2019-01-01	State Grid	Shaanxi	Hubei
Weifang-Linyi-Zaozhuang-Heze-Shijiazhuang	潍坊-临沂-枣庄-菏泽-石家庄1000千伏特高压交流工程（山东-河北特高压交流环网）		operating	2020-01-04		1000 kV Ultra-AC	816	2	14	2017-10-31	State Grid	Shandong	Hebei
Yazhong-Jiangxi	雅中-江西±800千伏特高压直流输电工程	雅湖直流	operating	2021	8000	±800 kV Ultra-DC	1696		24.4	2019-08	State Grid	Sichuan	Jiangxi
Sichuan-Chongqing	川渝1000千伏特高压交流工程		operating	2024-12-27	4000	1000 kV Ultra-AC	658	2	28.6	2022-09	State Grid	Sichuan	Chongqing
Baihetan-Jiangsu	白鹤滩-江苏±800千伏特高压直流输电工程	建苏直流	operating	2022-07-01	8000	±800 kV Ultra-DC	2087		30.7	2020-11	State Grid	Sichuan	Jiangsu
Baihetan-Zhejiang	白鹤滩—浙江±800千伏特高压直流输电工程	金塘直流	operating	2022-12-30	8000	±800 kV Ultra-DC	2121		29.9	2021-07	State Grid	Sichuan	Zhejiang
Wudongde-Guangxi-Guangdong	乌东德电站送电广东广西特高压多端柔性直流示范工程（昆柳龙柔性直流工程）	昆柳龙直流	operating	2020-12	8000	±800 kV Ultra-DC	1452		24.3	2018-03	China Southern Power Grid	Yunnan	Guangdong

Table 4: UHV projects under construction and proposed.

UHV Power Tansmission Line	UHV Tansmission Line in Chinese	Other name	Status	Commissioned Year	Capacity 额定输送容量 (MW)	Technology	Transmission Distance（km）	circuit	Investment (Billion RMB）	Permitted Date	Ultimate Parent	Start Region	End Region
Gansu-Zhejiang	甘肃－浙江±800千伏特高压直流输电工程（陇电入浙）	陇电入浙	construction		8000	±800 kV Ultra-DC	2370		35.3	2024-7	State Grid Corperation of China	Gansu	Zhejiang
Badan Jilin-Sichuan (Gansu-Sichuan)	巴丹吉林-四川±800千伏特高压直流线路工程(陇电入川)	陇电入川	proposed		8000	±800 kV Ultra-DC					State Grid Corperation of China	Gansu	Sichuan
Western Mongolia-Beijing, Tianjin, Hebei	蒙西-京津冀（库布齐-雄安）±800kV特高压直流输电线路工程	（库布其北—沧州±800kV 特高压直流输电工程）	proposed		8000	±800 kV Ultra-DC	699.7				State Grid Corperation of China	Inner Mongolia	Hebei
Ningxia-Hunan	宁夏-湖南±800千伏直流特高压外送工程		construction		8000	±800 kV Ultra-DC	1634		28.1	2023-05-24	State Grid Corperation of China	Ningxia	Hunan
Shaanxi-Anhui	陕西-安徽±800千伏特高压直流输电工程		construction		8000	±800 kV Ultra-DC	1070		20.5	2024-02-22	State Grid Corperation of China	Shaanxi	Anhui
Datong-Huailai-Tianjin South	大同-怀来-天津南特高压交流工程		construction	2027		1000 kV Ultra-AC	771.9	2	22.5	2024-09	State Grid Corperation of China	Shanxi	Tianjin
Jinshang-Hubei	金上-湖北±800千伏特高压直流输电工程	金湖特高压	construction		8000	±800 kV Ultra-DC	1784		33.5	2022	State Grid Corperation of China	Sichuan	Hubei
Tibet Southeast-Guangdong, Hong Kong, Macao	藏东南-粤港澳大湾区±800千伏特高压直流输电工	藏玉直流	proposed			±800 kV Ultra-DC			54.9		China Southern Power Grid 51%, State Grid 49%	Tibet	Guangdong
Hami North-Chongqing	哈密—重庆±800千伏特高压直流输电工程	哈重特高压，“疆电外送”第三条直流通道	construction	2025	8000	±800 kV Ultra-DC	2290		28.1	2023-07	State Grid Corperation of China	Xinjiang	Chongqing

Ultra-High-Voltage (UHV) Power Transmission System in China

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