China’s State Grid Corporation (SGCC) is planning to significantly extend the capacity of the high-voltage lines linking coal-fired and hydropower plants with urban areas. At 750 kV and 1000 kV, the new high-voltage links are to include unprecedented levels of voltage. The 1000 kV link is to be the first in the world operated commercially at this voltage level. KEMA will assess the design, manufacture and end-product of the switchgear and compensating coils for these links.

China’s coal mines are concentrated in the northern part of the country, whereas the hydropower plants are in the south. The urban and industrial areas are located mainly along the east coast. The capacity of the current 330 kV and 500 kV high-voltage links is inadequate to meet the skyrocketing demand for electric power. SGCC decided to install new power lines of 750 kV and 1000 kV, the maximum voltage levels attainable today. In addition to installing hundreds of kilometers of high-voltage lines and towers, SGCC must build a series of substations, with switchgear, transformers and coils. China wants all the project components to be manufactured domestically.

Switchgear quality assurance  
With its long-standing experience and expertise in China and elsewhere, KEMA was commissioned to monitor the switchgear quality of the two scheduled lines. Switchgear ranks among the most complex and critical components in an electric power grid. 
The 750 kV project includes the construction of a 750 kV AC link spanning a distance of 300 km between China's northwest and west regions. This line will have four substations, built entirely by domestic companies. In this project KEMA is responsible for quality assurance of two gas-insulated switching (GIS) units and two coils. Since the link is to be put into operation before the end of the year, KEMA will complete its work on the 750 kV project in late October.

Pilot 1000 kV
The 1000 kV project involves a pilot for a 1000 kV AC link over a distance of 650 km between China’s northern and central regions. This link is scheduled to be operational by the end of 2008. The three substations related to this project will contain first-of-their-kind GIS units, also to be manufactured by Chinese companies. KEMA will assess whether the design meets the specified requirements. Moreover, KEMA will supervise the manufacturing process and acceptance tests. This project will continue until mid-2008.