The UHV DC converter valve is the core equipment of UHV DC transmission engineering and is the core functional unit for AC/DC conversion. As the DC power transmission is growing rapidly, the overload capability of converters is required as they might take the load of other malfunction units for a short time. During overload operation, the surface temperature of the thyristor in a converter rises significantly, which causes serious problems such as aging, malfunction.

A water-based phase change dispersion (PCD) that acts as a coolant enhancing the thermal shock resistance is developed in this project. By providing a better apparent specific heat capacity and other thermophysical properties, the coolant improves the cooling capacity, uniformity of temperature distribution of the thyristor, thereby reducing the surface temperature of the thyristor and improving the reliability, stability and life of the system.

The PCD has been mass produced and tested. It is proven that the PCD has low electric conductivity and can replace deionized water in the existing cooling system. Without increasing the scale of the existing cooling system and related costs, the cooling capacity of the system is increased by 10%, and the temperature of the thyristor is reduced by 5 °C. Therefore, the transmission power of the converter valve is increased by 8%, the overload capacity is increased by 15%.

Partners:

State Grid Tianjin Electric Power Company

Lucerne University of Applied Sciences and Arts

Duration: 7/2017 to 12/2019