Voltage-Based Segmented Control of Superconducting Magnetic Energy Storage for Transient Power Fluctuation Suppression in Island DC Microgrid

Voltage stability is one of the critical factors for the stable operation of DC microgrids (MG). For the communication free DC MG, the DC voltage is more vulnerable due to the DC voltage deviation caused by the droop characteristics. When facing the transient power fluctuation caused by multiple electric vehicles (EVs) connected to the grid, PV shedding, etc., the DC bus will have a large voltage sag. The voltage quality degradation will bring adverse effects to the DC MG. However, most energy storage systems like battery energy storage systems (BESS) are not suitable for suppressing transient large power fluctuation. In this paper, the SMES is introduced to a DC MG to form a power regulation system. A voltage-based segmented (VBS) control is designed for the SMES-based power regulation system to suppress transient large power fluctuation in the DC MG. The voltage deviation caused by power distribution can be tolerant by VBS controlled SMES. Meanwhile, the dynamic recovery capability of the DC voltage is improved. The control method of SMES is independent of other devices in DC MGs, hence it is not dependent on communication. The control strategy of the SMES is further verified by simulation results.