A 0.2 MJ cryogen free Nb₃Sn SMES in UPS application

The rising industrial demand for a high-quality power supply has resulted in a growing interest in superconducting magnetic energy storage (SMES). These devices have a storage capacity ranging from fractions of MWs up to about 1 MWh. The commercialized units are based on NbTi technology at liquid helium temperature. The development of mechanical cooling systems has been very active during the recent years. The cooling capacities of cryocoolers are well around 10 W at 10 K. Based on this fact, a conduction-cooled Nb₃Sn SMES concept has been built and tested (uninterrupted power supply) application. The cryogenic interface of the coil also provides the protection scheme of the magnet which helps speed up the current decay during normality and thus diminishes the hot spot temperature in the winding. The test results are presented and discussed together with problems related to the cryointegration of the magnet. The magnet system has been demonstrated to compensate a short term loss of power.