The first 750-kilovolt-electricity transmission project in China has been in safety and stable operation since going into smooth operation on September 26 and the line voltage is within an eligible range, according to the State Grid Corp of China (SGCC) recently, reports People's Daily on October 24.

It costs nearly two years to complete the 750-kilovolt project, including a 141-kilometer transmission line linking Guanting of Qinghai Province with Lanzhou of Gansu Province in the western region and two 750-kilovolt transformer substations. First of its kind in the country, the project has been designed, manufactured and put into operation by China independently with advanced levels in the world. And it is also one of the world's top transmission projects with the highest voltage.

Located in northwestern China with average altitude of 2,000 meters above sea level, the project was built in a varied geological area with broad frozen earth. The air break joint and insulation levels are close to or equivalent to a million-volt level and the project is the first to be built in such an environment in the world. The construction work shows that China's grid technology has entered into the advanced ranks of the world. It also marks that China has accumulated precious experiences in the development of building extra high-volt grid.

Before this, the grid voltage was 330-kilovolt in the vast areas of the western part in the nation, which was difficult to cope with the demand for development. If continuing to transmit electricity with the voltage, there will occur problems, including the density of lines and the drop of the electricity-transmitting efficiency, causing the waste of resources. The capacity of the 750-kilovolt line will be four times that of the past 330-kilovolt line, obviously reducing line losses resulted from power transmission. At the same time, the line will take less land areas than the 330-kilovolt line does.

It is reported that the SGCC plans to extend the grid trunk network in northwest China by 2010 to better serve the West Development Strategy and to transmit electricity from China's west to the east. By then, an electricity-network will be formed by connecting the Laxiwa Hydropower Station in northwest China's Qinghai Province, Qianxian County in Shaanxi Province and the terminal in the east part of Yinchuan in the Ningxi Hui Autonomous Region. And the 750-kilovolt lines will be extended to 4,730 kilometers in the west with a transformation capacity of 13.2 million kilovolt amperes by 2010.

By People's Daily Online