China Southern Power Grid is a leader in the nation's push for infrastructure co-operation in neighboring countries, report Du Juan in Beijing, Guo Anfei in Laos and Hu Yongqi in Kunming

As China's GDP growth is slowing, the expansion of economies in Southeast Asia is accelerating - creating demand for more electricity.

That disparity has opened opportunities for China's electricity sector, which is investing in generation and grid operations in those faster-growing markets, even as it continues to sell them power produced within China.

A recent development on this front comes from China Southern Power Grid Co Ltd, one of the nation's two major operators of electricity transmission and distribution systems.

On Oct 13, CSPG was awarded the contract for a coal-fired power plant in Yongxing, Vietnam, valued at $1.76 billion. It's the largest such deal in Vietnam for a Chinese company.

As China and Vietnam seek closer economic and trading bonds, the two countries will start key infrastructure projects soon that will support bilateral investment and trading, Premier Li Keqiang said during a visit to Vietnam in October.

The coal-fired power plant that CSPG will build is part of Vietnam's seventh power industry development plan. It's also a key infrastructure project.

Work is expected to start next year and be completed in 48 months.

The plant has an estimated operating life of 25 years, according to the company.

Deng Xiaowen, director of the international department of CSPG, said the company has been expanding overseas through two main methods.

One is direct investment, such as building power plants locally. The second involves transmitting electricity to foreign users, which is considered a form of exports.

"In the next 10 years, CSPG's overseas expansion will continue to focus on the Greater Mekong Subregion," said Deng.

"Building up a unified power market in the Mekong, as well as Macao and Hong Kong, will help these regions utilize resources better to boost their economies."