Work on China Southern Power Grid's 24.25 billion yuan ($3.59 billion) Wudongde DC (direct current) Project, the world's first multi-end flexible ultrahigh voltage direct current power transmission (UHVDC) project, is progressing steadily and expected to start operations by 2020, a company official said.

The project spans 16 cities in South China, three power converter stations in Kunming, Yunnan province, Liuzhou in the Guangxi Zhuang autonomous region, and Huizhou in Guangdong province and power transmission lines traversing 1,452 kilometers.

When completed, the project is expected to bolster the clean energy requirements of the Guangdong-Hong Kong-Macao Greater Bay Area. In addition, it will transmit another 20 billion kWh of clean power every year from Yunnan province and Guangxi to the Greater Bay Area. This will cut coal usage in the Greater Bay Area by about 6.31 million metric tons.

"Compared with the more frequently used 500kV high voltage direct current power transmission (HVDC), the company decided on 800kV UHVDC for higher power capacity and more stable transmission to meet the growing power demands of the Greater Bay Area," said Zhang Yan, deputy general manager for the Kunming's operations of the Wudongde DC Project.

Power consumption in the Greater Bay Area stood at 520 billion kWh last year.

Zhang Yong, director of the power dispatch section of China Southern Power Grid Dispatching and Control Center, said currently 90 percent of the power used in Macao is transmitted through the company's power grid. It also carries about 25 percent of the power used in Hong Kong, and 30 percent of that in Guangdong.

"It is a win-win situation for Yunnan province and the Guangxi Zhuang autonomous region to tie up with the Greater Bay Area. As both Yunnan and Guangxi have abundant water and wind resources to generate clean energy, and the Greater Bay Area has higher requirements for clean power projects, the projects will help foster economic growth in Guangxi and Yunnan," Zhang Yong said.

Earlier in March, the company said it will invest over 170 billion yuan to support grid construction in the Pearl River Delta, China's major economic hub covering Guangdong's capital city Guangzhou, Shenzhen and many other cities in South China.

Zhang Yan said one of the reasons why the company opted for multi-end UHVDC is to make power transmission more flexible.

"Usually power is transmitted in the region through the existing power transmission lines from Yunnan to Guangdong. But we designed another end in Guangxi, so that on days when there is lesser demand from the Greater Bay Area, the power can be transmitted to Guangxi, where there is huge demand," said Zhang Yan.

"Such measures help us to make full use of the capacity available for power transmission, as power cannot be stored or transmitted back," said Zhang Yan.