A commitment to safety and stability of electric power grids


In December 2018, the National Intellectual Property Administration announced winners of the 20th China Patent Awards, the highest honor in China's science and technology communities, with research projects of SCUT receiving two Silver Awards and five Merit Awards.

Among these seven scientific inventions was a Silver Award winner, “Dynamic reactive power compensation device and its control method for centralized multi-infeed DC systems”, a technology co-developed by SCUT and the China Southern Power Grid.

The study was completed by a team led by Wang Juanjuan, a professor at the School of Electric Power of SCUT. Her team has long been engaged in the research of dynamic reactive power compensation and centralized multi-infeed DC systems in electric power grids.

In China, over 80 percent of energy sources are concentrated in the northwest, while the center and the east are using up more than 70 percent electric power consumed by the whole country. For this reason, over the decades, China has been giving every effort to construct a massive transmission project to bring electric power from the west to the east.

In such a cross-regional grid, high voltage direct current (HVDC) transmission, by showing unique advantages in lower cost and enhanced stability and flexibility, is a prior choice for large-capacity and long-distance electricity transmission. China has built and is building more than 50 power lines of HVDC transmission, which, along with alternating-current (AC) transmission, make up one of the largest AC-DC hybrid power grid in the world.

However, the connection between AC and DC systems is a sophisticated project. Among various means of connection, centralized infeed from multiple DC power lines into the AC system is the most intricate one, in particular when dealing with operational risks caused by complication of stability and insufficient supply of voltage.

To solve these issues, Professor Wang Juanjuan and her team created an innovative type of dynamic reactive power compensation device, a key tool to stabilize the power system and to improve the efficiency.

With fast response and precision control, this device is suitable for being used in centralized multi-infeed DC systems. It is designed to improve the operation reliability and reduce the workload of operating maintenance in power grids, while it does not need to adopt water-cooled equipment, and remarkably lower the construction cost for dynamic reactive power compensation.

The technology has been delivered to use in power grids built by the China Southern Power Grid as a key measure to ensure the country's “West to East” Electricity Transmission Project. Up to the end of 2017, it had created additional sales of more than 500 million yuan for enterprise users, and greatly enhanced safety and operational stability of AC-DC hybrid power grids in China.

Source from the School of Electric Power
Translated by Xu Peimu
Cover image designed by Mo Zhihao
Edited by Xu Peimu and Yang Manxi