Design and Evaluation of Superconducting Magnetic Energy Storage in a Multi‐VSG System for Subsynchronous Oscillation Inhibition

ABSTRACT This paper presents the design and assessment of a superconducting magnetic energy storage (SMES) for a multi‐virtual synchronous generator (multi‐VSG) system, with a specific focus on subsynchronous oscillation (SSO) inhibition. To analyse the frequency response characteristics of a 100 kW × 3 multi‐VSG system and establish a linkage between SSO suppression and SMES design, this work first proposes a novel impedance reshaping‐driven co‐optimisation framework for SMES and multi‐VSG parameters. Within this framework, key VSG variables, including virtual inertia, damping and impedance reshaping time constants, are optimised using the improved whale migration algorithm to minimise the sum of phase differences between grid and VSG impedances at the crossover frequency. The minimum SMES capacity is quantified by integrating the transient power imbalance using the optimised VSG parameters. Based on a comprehensive strategy for mitigating SSO and maintaining routine power balancing, the 150 kJ SMES magnet is designed using Yttrium Barium Copper Oxide tapes, with its geometric and tape parameters further optimised. To evaluate the SMES performance in the system, simulations of diverse scenarios, incorporating power reference adjustment and grid fault, demonstrate that the SMES can effectively suppress the SSO, confirming that the proposed scheme meets the system's operational requirements.