Design and operation of double SMES coils for variable power system through VSC-HVDC connections

In this paper, a new topology incorporating double superconducting magnetic energy storage (SMES) coils is proposed, and control strategies for effectively delivering power to a grid via high-voltage direct current (HVDC) are developed. Power grids have become increasingly complex due to the use of renewable energy and dynamic loads. As such, it is important to design a power transmission system that satisfies power supply and demand requirements. HVDC is especially attractive for particular power transmission technologies, because the fast control characteristics of HVDC contribute to the stabilization of connected power grids. SMES has also received attention as a promising method to overcome the aforementioned issues. In the proposed scheme, one SMES coil in series with the dc line is specifically designed for use as a fault current limiter, while the other coil in parallel with the line is employed for energy storage. This study describes the effectiveness of combining these two schemes to mitigate the dynamic power fluctuation of generator and load, reinforcing controllability, and dependability of the power delivery. Case studies demonstrate the improved performance and robustness of voltage sourced converter-HVDC linked with double SMES coils for dc fault.