3-Phase Current-Source SMES-UPS Based on TFSC and its Control Strategies

3-phase current-source SMES-UPS based on toroidal field superconducting coils (TFSC) is introduced in this paper, which serves for the exciting power supply (EPS) for TFSC when the power grid is in order, as well as for uninterrupted power supply (UPS) for the cryogenic and vacuum system once the deep voltage sag or other grid faults are detected. In the case of former, by controlling active and reactive current of AC side of converter, not only the DC current in TFSC slopes up to a steady value according to the referenced rate, but also the AC side of converter can achieves unit power factor and low harmonic distortion; in the case of latter, by controlling the AC current of converter with the feedback of protected loads voltage, not only the amplitude and frequency of protected loads voltage is steady, but also its phase is invariable. A 1.0 kVA prototype has been established and the experiment when it serves for EPS for TFSC, as well as UPS for protected loads are carried out, the results show that the proposed control strategies may fulfil the goals of SMES-UPS based on TFPS perfectly on either of above condition