Live-Grid Installation and Field Testing of the First Italian Superconducting Fault Current Limiter

Since 2009, Ricerca sul Sistema Energetico S.p.A. has been involved in the development of a resistive-type superconducting fault current limiter (SFCL) for MV applications to be installed in the A2A Reti Elettriche S.p.A. distribution grid in the Milan area. The project started with simulations, design, and testing activities for a single-phase device; this first step paved the way for developing, testing, and live-grid installation at the hosting utility site of the final three-phase SFCL prototype. The result of this research activity is a resistive-type 9 kV/3.4 MVA SFCL device, based on first-generation (1G) BSCCO tapes, nowadays permanently installed as a single-feeder fault protection. This device is the first SFCL successfully installed in Italy. In this paper, we report on installation of the three-phase device and field-testing activity. The next step of the R&D activity will consist in the design of a three-phase SFCL demonstrator 9 kV/15.6 MVA to be installed at the same substation in an incoming feeder to limit the contribution of this feeder to the total short-circuit current of the network. This application is very demanding in terms of SFCL reliability and availability, but also the most interesting one for the A2A hosting utility needs.