Remote cryogenic helium gas circulating cooling system for a 10-Mvar class HTS dynamic synchronous condenser

This paper focuses on the remote cryogenic helium circulating system for cooling the 10-Mvar class HTS DSC. The cryogenic system is an upgraded version to provide a cooling power about 200 W@20 K. Six cryogenic cryocoolers are employed as the cold source. Two cryogenic helium blowers are used to overcome the pressure drop. Circulating loop is divided into two branches, of each three coolers are installed in parallel and then as a whole connected to a helium blower in series. The detailed design, structure parameters, and optimization of the cooling system were described as well. In the experimental tests coupled with the rotor section of 10-Mvar HTS DSC, the magnet was firstly pre-cooled to about 110 K with liquid nitrogen, and then further cooled to around 34.5 K by the circulating helium gas. In the near future, the 10-Mvar class HTS DSC will be installed, tested and integrated into the power grid for practical application.