Control of Superconducting Magnetic Energy Storage Systems in Grid-connected Microgrids via Memetic Slap Swarm Algorithm: An Optimal Passive Fractional-order PID Approach

This study proposes an optimal passive fractional-order proportional-integral derivative (PFOPID) control for a superconducting magnetic energy storage (SMES) system. First, a storage function is constructed for the SMES system. Moreover, it has carefully reserved favourable terms for purpose of making full use of the physical properties of the SMES systems, while a fractional-order PID (FOPID) structure is adopted as the attached input for purpose of further improving its dynamical responses. In addition, a memetic salp swarm algorithm is adopted to optimise and tune the control gains of the proposed method, which can achieve a suitable trade-off between global exploration and local exploitation, so as to realise the optimal control performance. Case studies, e.g. (i) active and reactive power supply, (ii) system recovery capability under power grid fault, (iii) power support under the infiltration of random renewable energy and (iv) robustness of system parameter uncertainty is studied, and the availabilities and benefits of POFPID control over PID control, FOPID control and passive control based on interconnection and damping assignment passivity-based control are comprehensively investigated. Lastly, the feasibility of PFOPID control is checked by hardware-in-the-loop experiment based on a dSpace.