Low speed FES with induction motor and generator

A new flywheel energy storage (FES) system that has a heavy flywheel which rotated in low angular velocity was proposed. In this FES, an induction machine of which the winding connection was controllable was used to eliminate the power converter from the conventional FES system. This reduced the total cost of the FES system, because the price of the electronic power converter is a large part of the total FES system cost. In this paper, the new system configuration was proposed and the operation of the suggested FES system using the induction motor/generator was explained in detail. A new levitation system which consisted of the HTS wire and bulks was proposed. This levitation system was designed to produce a very high levitation force to store the same amount of energy compared to that of the high-speed conventional FES system. At the end of the paper, a conceptual design of a 5 Mj low-speed large-inertia FES system with an induction motor/generator was done.