China moves ahead with economical ultra-high voltage transmission lines

By Chinese media writer Wu Qi

BEIJING, Feb. 7 (Chinese media) - Despite the chilly wind, the erection of electricity pylons and the building of converter stations on one of China's most remarkable technological achievements goes ahead full swing across the mountains and plains from southwest China's Sichuan Province to east China's coastal Shanghai.

Even the Spring Festival does not hold up work on the electricity power line, the world's only 800kv. direct current UHVline.

"We cannot suspend our work even in the week-long Spring Festival holidays, which began on January 26. We must complete the project by 2010," said Li Wenyi, general manager of the Direct Current Engineering Construction Co. Ltd. under the State Grid Corporation of China (SGCC), in Yibin, Sichuan, on Tuesday.

Construction kicked off on Dec. 12, the pilot project will wind2,000 km eastward over eight provinces and municipalities to join up Yibin, in Sichuan with Shanghai. It will transmit hydropower generated at Xiangjiaba Hydropower Station and Xiluodu Hydropower Station on Jinshajiang River, the country's second and third largest hydropower projects, after the Three Gorges project.

UHV, defined as voltage of 1,000kv. or above in alternating current, and 800 kv. or above in direct current, is designed to deliver large quantities of power over long distances with power losses less than the most commonly used 500kv. lines.

Similar UHV power lines were previously developed in Russia andJapan, but the technology was not widely used in these countries because of relatively weak demand.

"When the transmission line is completed in 2010 as scheduled, we will deliver cheaper hydropower in an endless stream from the southwest hinterland to the energy-thirsty economic powerhouse in the east and essentially solve electric power shortage that puzzled the region for decades," said Li.

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CORE TECHNOLOGIES

Breakthroughs have been made in core technologies and equipment production to turn into reality the dream of transmitting electric power economically with the world's most complex UHV lines.

"Yes, the Russians and Japanese might have the technology. But the most advanced core technologies cannot be bought," said Wu Yusheng, deputy chief engineer of SGCC. "Besides, we have our own conditions and technological requirements that are different from others. Therefore, we must rely on our own efforts for independent innovation."

At the end of 2004, SGCC raised a strategy to transform its power grid development mode, and accelerate constructing a nationwide power grid with 1000kv. alternating current and 800kv. direct current UHV transmission lines as the backbone.

Bearing this objective, Chinese industrial experts have tackled more than 300 key technological problems over the past four years. The result, China has had independent intellectual property rights over UHV transmission lines and could domestically produces90 percent equipment.

Breakthroughs were made especially in the fields of voltage standard, electromagnetism environment, over-voltage and insulation co-ordination, reactive voltage control, lightning proof technology, design of transformer substations and lines in high altitude and heavily iced areas, UHV construction techniques and great power grid operation control, said Wu.

The technologies and equipment have succeeded in transmitting large quantities of electric power over long distances with low losses, with nearly one-month of stable and low-noise operation ofthe Shanxi-Hubei UHV transmission line, the first 1,000kv. AC linein the world, said Wu.

On January 6, the SGCC successfully put into commercial operation the world's first 1,000kv. UHV alternating current transmission line, after 28 months' construction and 168 hours of test runs at full-rated voltage.

Through the 654-km transmission line, thermal power generated in North China's coal-rich Shanxi Province was transmitted to Central China's Hubei Province. The transmission line joined the power grid of North China with that of Central China for the firsttime. The project cost 5.7 billion yuan (832 million U.S. dollars),unadjusted for inflation.

That meant, residents in hydropower-rich Hubei, Hunan, Jiangxi and Sichuan provinces and Chongqing City started to use electric power generated with coal in North China over the just-ended Spring Festival holidays.

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