Workers set up wires for the transmission line in Kunshan city, east China's Jiangsu province. (PHOTO: VCG)

By ZHONG Jianli

As an important part of China's west-to-east power transmission program, the Baihetan-Jiangsu ±800kV ultra-high-voltage (UHV) direct current (DC) power transmission line was put into operation in early July, with the ability to deliver more than 30 billion kWh clean electricity annually.

Stretching from Baihetan in southwest China's Sichuan province to east China's Jiangsu province, the project has a rated transmission capacity of eight million kilowatts and a line length of 2,088 kilometers.

For the first time, it applied hybrid cascading technology in the world's DC transmission field, that is, conventional DC converters connected in series with flexible DC converters.

This technology combines the advantages of conventional DC and flexible DC, which can effectively improve the safety, stability and flexibility of the power grid.

New equipment has been developed for the project, including the controllable self-recovery energy dissipation devices and amplitude-phase correctors. With these new devices, the power receiving capacity of the grid has been greatly improved.

By transmitting clean hydro electricity, the project will reduce coal usage by 14 million tons, and cut emissions by 25 million tons of carbon dioxide, 250,000 tons of sulfur dioxide, and 220,000 tons of nitrogen oxides each year. It helps further optimize the energy supply structure, and ease the pressure on the prevention and control of air pollution.

As the UHV power grid has large investment and high industrial added value, the Baihetan-Jiangsu project effectively drives the development of upstream and downstream industries, including power supply, electrical equipment, energy equipment, and raw materials, and promotes transformation and upgrading of related industries.

With a total investment of more than 30 billion RMB, the project has increased the output value of the power transmission & transformation equipment manufacturing industry by about 18 billion RMB, led to the investment of about 100 billion RMB in other related industries, and created more than 20,000 jobs.