Chinese electricity transmission reaches ultra-high levels

The SGCC (State Grid Corporation of China) has launched its first ultra-high voltage power grid – a 1 000 kV UHV AC (Ultra High Voltage Alternating Current) pilot project connecting Shanxi, Nanyang and Jingmen.

UHV (Ultra High Voltage), defined as voltage of 1 000 kV or more AC (alternating current) and 800 kV or more DC (direct current), is designed to deliver large quantities of power over long distances with little loss of same and reducing the number of transmission lines to a minimum.

The grid runs some 640 kilometres and consists of three substations and two sections of transmission lines. It starts at Jindongnan Substation in Changzhi, Shanxi province, where China has abundant coal resources, and ends at Jingmen Substation in Jingmen, Hubei province, across the Yellow and Hanjiang rivers.

Airscape view of Jingmen Substation

The SGCC put the grid into commercial operation on 6 January 2009 after 28 months of construction.

Electricity demand in China is steadily rising, but meeting that demand is difficult given the great distances that separate the country’s major manufacturing and population centres from the dams and coal deposits that constitute its primary sources of electricity. Large-scale, long-distance transmission networks are one answer.

The grid is the first stage in a series of developments that SGCC plans to build over coming years to promote the highly efficient development and utilization of China’s energy resources and facilitate the sustainable development of China’s energy industry.

The grid will save tremendous quantities of coal-powered energy – still by far the most common source of electricity in China – while occupying less land.

The project boasts a number of "firsts" in engineering and technological feats for UHV equipment, much of which was designed in China. It is the world's first UHV transmission line to enter production mode. It has the world's first 1 000 kV UHV single-phase transformer with 3 000 MVA, a 1 000 kV shunt reactor with the highest voltage level and the largest capacity of 960 MVar.

Jindongnan Substation – equipped with a 3 000 MVA transformer and a set of 3 x 320 Mvar shunt reactors, five circuits of 400 kV lines equipped with HGIS (Hybrid Gas Insulated Switch), two sets of 240 Mvar reactors and four sets of 210 Mvar capacitors – covers 7.8 hectares. The Nanyang switch station, which occupies 8.15 hectares in Zhaohe Town, Fangcheng County, Nanyang City, Henan Province, has double circuits of 1000 kV lines and two sets of 240 Mvar shunt reactors. Jingmen Substation has a single 3 000 MVA transformer, one set of 3 x 200 Mvar shunt reactors and four sets of 210 Mvar capacitors installed at the 110 kV-end of the transformer. It spreads over 11.5 hectares.

The transmission lines are split into two sections of 359 and 281 kilometres, supported by 1 284 towers of 70 different designs. The average height of the towers is 77.2 metres. Their average weight is 70.5 tons.

The highest rated operating voltage reaches 1100 kV and largest transmission capacity 2 800 MW. According to Yinbiao Shu, Executive Vice-President of SGCC and member of the IEC Market Strategy Board, the project will boost UHV grid development in China as the "first most state-of-the-art technology in UHV AC with the highest operation voltage, the largest transmission capability, longest transmission distance and least line loss".

Net electricity generation in non-OECD
Asia by fuel, 2005-2030, shows that coal
still accounts for the largest source of
electricity generation

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Credit: Energy Information Administration

The world’s electrical consumption is set to rise dramatically, according to the US Department of Energy. Its latest annual energy outlook report predicts that world net electricity generation nearly doubles in the IEO2008 (The International Energy Outlook 2008) reference case, from about 17.3 trillion kWh in 2005 to 24.4 trillion kWh in 2015 and 33.3 trillion kWh in 2030.

Non-OECD (Organisation for Economic Cooperation and Development) developing countries show the strongest growth in electricity demand as they expand their power grids to support sustained robust economic growth. Total electricity generation in the non-OECD countries increases by an average of 4.0 % per year from 2005 to 2030, as compared with a projected average increase of 1.3 % per year for OECD electricity generation. In 2030, generation in the non-OECD countries is projected to exceed generation in the OECD countries by 46 %.

Summarizing the Chinese UHV power transmission construction, Shu said that the project would provide large amounts of clean energy from mine-mouth power stations, hydropower, nuclear power and renewable power to the far-away load centres in the most efficient way.