Advanced Superconducting Power Conditioning System for Effective Use of Renewable Energy

Abstract

In order to use effectively renewable energy sources, we propose a new system, called Advanced Superconducting Power Conditioning System (ASPCS) that is composed of Superconducting Magnetic Energy Storage (SMES), Fuel Cell-Electrolyzer (FC-EL), hydrogen storage and dc/dc and dc/ac converters in connection with a liquid hydrogen station for fuel cell vehicles. The ASPCS compensates the fluctuating electric power of renewable energy sources such as wind and photovoltaic power generations by means of the SMES having characteristics of quick response and large I/O power, and hydrogen energy with FC-EL having characteristics of moderate response and large storage capacity. The moderate fluctuated power generations of the renewable energy are compensated by a trend prediction with the Kalman filtering algorithm. In case of excess of the power generation by the renewable energy to demand it is converted to hydrogen with EL. On the contrary, in case of shortage the electric power is made up with FC. The faster fluctuation that cannot be compensated by the prediction method is effectively compensated by SMES. In the ASPCS, the SMES coil with an MgB2 conductor is operated at 20 K by using liquid hydrogen supplied from a liquid hydrogen tank of the fuel cell vehicle station. The necessary storage capacity of SMES is estimated as 50 MJ to 100 MJ depending on the prediction time for compensating fluctuation of the rated wind power generation of 5 MW. As a safety, a thermo-siphon cooling system is used to cool indirectly the MgB2 SMES coil by thermal conduction. The concept of the ASPCS and the design study of the SMES are reported.