Development of MVA Class HTS SMES System for Bridging Instantaneous Voltage Dips

Abstract

A SMES system of MVA class for bridging instantaneous voltage dips has been developed using Bi-2212 wire. The Bi-2212 wire has high-performance conductive characteristics that do not deteriorate at a low temperature in high magnetic fields beyond 10 T. These characteristics enable a compact design of a SMES system of the Bi-2212 wire. In addition, coils of the Bi-2212 wire can be adequately insulated due to a high temperature margin. Therefore, the SMES system designed by using the coils has advantages to enhance dielectric strength and output power of the system. In our previous study, a SMES system consisting of 4 unit coils was constructed and the various properties were examined. Up to the present, the total 18 unit coils were stacked to make a coil system (outer diameter: 700 mm, height: 554 mm, stored energy: 984 kJ) and installed into a SMES system of 1 MVA for bridging instantaneous voltage dips. Also, the cooling system of the HTS SMES has been improved. The characteristics of the conduction cooled HTS coils of 1 MJ class were investigated in the operations of 1 MVA SMES system for bridging instantaneous voltage dips. Thermal reliability was verified during each operations of exciting, standby, bridging and current damping. Moreover, the repetitive bridging operations even worked out every 5 minutes. Advantages of the conduction cooled HTS coils for SMES were verified.