Coordinated Control Strategies for SMES-Battery Hybrid Energy Storage Systems

Power swings may cause power system instability; therefore, hybrid energy storage systems (HESSs) are necessary to smooth the output of wind farms. Superconducting magnetic energy storage (SMES) systems have a high power density, whereas battery energy storage systems (BESSs) provide a high energy density. The significant contribution of this paper is the proposal of hierarchical control strategies for an HESS composed of an SMES system and a BESS. Mathematical models and port-controlled Hamiltonian (PCH) models of the HESS are established. At the device level, a novel HESS control strategy based on the PCH models is proposed to improve its output performance. At the system level, a multilevel power allocation method based on empirical mode decomposition, Fuzzy control and advanced control is proposed to achieve an efficient grid connection for a wind farm; the grid connection considers the real-time and future state of charge of the SMES system and BESS. The effectiveness of the proposed strategies are verified through simulation studies.