Systems used to extract renewable energy often are subject to suboptimal working conditions due to the intermittent nature of most renewable energy sources. The flywheel energy storage system suggested in this paper utilises an electronic clutch that engages and disengages the generator from the flywheel of the renewable energy system in an attempt to prevent the generator rotor from coming to a rest and encounter undesirable startup torque. Simulation results demonstrate the effectiveness of the threshold controls – average power output by the system can be seen to increase by 5% for a system with a small generator and by over 7,300% for a system with a very large generator, when compared to results for when no threshold controls are applied. The increased effectiveness for the larger generators confirms that the proposed threshold control scheme improves power output by decreasing the effect of counter-torques on the operation of the system.
Keywords: flywheel energy storage, FES, intermittent energy, load control, velocity threshold, renewable energy