The world’s longest power transmission lines
High-voltage direct current (HVDC) has emerged as the preferred transmission technology for long-distance bulk power supply. Power-technology.com profiles the world’s five longest operational power transmission lines.
Rio Madeira transmission link, Brazil
The Rio Madeira transmission link in Brazil, with an overhead length of 2,385km, is the world's longest power transmission line. The 600kV high-voltage direct current (HVDC) bipolar line was brought into commercial operation in November 2013 and is capable of transmitting 7.1GW of power.
The Rio Madeira HVDC link exports electricity from the Santo Antônio and Jirau hydropower plants on the banks of the Madeira River in north-west Brazil to major load centres in south-eastern Brazil. It connects the Porto Velho Collector Substation in the state of Rondônia to the Araraquara-2 Substation in the state of São Paulo.
The HVDC transmission line was constructed in 24 months by Interligação Elétrica do Madeira (IE Madeira), a consortium comprised of three major Brazilian energy providers. ABB supplied power equipment for three HVDC stations. Alstom supplied two HVDC bi-pole converter stations and four HVDC converter transformers for the project.
Jinping-Sunan transmission line, China
China's 2,090km-long Jinping-Sunan transmission link, an 800kV ultra high-voltage direct current (UHVDC) transmission line, is the world's second longest power transmission line. The 7.2GW transmission link is owned by State Grid Corporation of China (SGCC) and was put into operation in December 2012.
The line passes through eight Chinese provinces to transmit power generated from Guandi, Jinping and Sichuan hydroelectric plants located in Yalong River in central-western Sichuan province to the industrialised coastal area of Jiangsu province in eastern China. The AC voltage at both ends of the line is 525kV.
The transmission project was approved by the government in November 2008 and involved an investment of approximately CNY22bn ($3.5bn). ABB designed and engineered the project in association with SGCC and local Chinese partners. ABB supplied the key components of the project, including the 800kV UHVDC transformers for both converter stations.
Xiangjiaba-Shanghai transmission line, China
The Xiangjiaba-Shanghai transmission line, with an overhead length of 1,980km, is the world's third longest transmission line. The 800kV, 7.2GW line, owned by SGCC, is the world's first ever UHVDC transmission line and started commercial operation in July 2010.
The Xiangjiaba-Shanghai link transmits power from the Xiangjiaba hydropower plant located in south-west China to the country's major industrial and commercial hub, Shanghai. The link comprises a single overhead line and 28 high / ultra-high-voltage converter transformers. The AC voltage at both ends of the line is 525kV.
The UHVDC transmission project was approved by the government in April 2007 and was completed in 30 months. ABB, under a turnkey contract, provided the overall system design, in addition to supplying the key components such as high- and ultra-high-voltage converter transformers, thyristor valves, DC and AC switchyard equipment, and the HVDC control system.
Inga-Kolwezi transmission line, Congo
Congo's 1,700km-long Inga-Kolwezi transmission line, formerly known as the Inga-Shaba link, is the world's fourth longest transmission line. The 500kV transmission line, with a rated capacity of 560MW, is owned and operated by Democratic Republic of Congo's (DRC) national electricity utility, Société Nationale d'Electricité (Snel).
The Inga-Kolwezi HVDC link carries power from the Inga Falls hydropower station on the Congo River to the copper mining district of Katanga in south-eastern Congo. The line was brought into service in 1982 and was the longest transmission line in the world at that time. The AC voltage at both ends of the line is 220kV.
The key components for the project, including the converter stations, were supplied by ABB. The company was awarded a contract to refurbish the line with new thyristor valves, new high-voltage apparatus and a new control and protection system to enhance the efficiency and reliability of the line in 2009.
Talcher-kolar transmission link, India
India's 1,450km-long Talcher-Kolar transmission link is the world's fifth longest transmission line. The 500kV HVDC transmission line, also known as the East-South transmission link, has a rated capacity of 2,500MW and is owned by Power Grid Corporation of India. It was the world's second longest transmission link at the time of commissioning in February 2003.
The Talcher-kolar HVDC transmission link transfers electricity from the Talcher power generation centre in the East Indian state of Orissa to Kolar near Bangalore in the South Indian state Karnataka. The bipolar transmission line had the capacity to transmit 2,000MW of power at the time of commissioning and was upgraded to 2,500MW in 2007. Siemens built the converter stations for the Talcher-kolar HVDC link.
Power Grid Corporation of India is also building India's first UHVDC transmission line, the 1,728km 800kV North-East Agra UHVDC link, capable of transmitting 8,000MW of power. The project is being delivered by ABB and is scheduled for commissioning in 2015. It will be the longest power transmission line in the country upon commissioning.