A New Coordinated Control Strategy of Flywheel Energy Storage System Participating in Primary Frequency Regulation of Power Grid

This paper proposes a new coordinated control strategy for conventional thermal generators with the application of flywheel energy storage system (FESS) to participate in power grid primary frequency regulation (PFR). Through probability density analysis of power grid frequency distribution characteristics, this paper finds that small frequency fluctuation data accounts for more than 80% of total frequency data and proposes that frequency regulation assignments under small disturbances should be undertaken by FESS alone which can significantly reduce generator governor operation times. Comprehensively analyzing power grid frequency regulation requirement and FESS state of charge (SOC) recovery requirement, this paper designs the control rules of FESS output power and then proposes the detailed control strategies in four different working modes. As for frequency regulation indexes, the number of governor operations representing generator wear and tear is included as a new index to help evaluate the effectiveness of the proposed strategy. Finally, Matlab/Simulink is used to simulate a typical PFR system with FESS and the simulation results show that the proposed control strategy can effectively improve the frequency quality, maintain a good SOC level, reduce the number of governor operations thereby has good regulation effects.