Unified Control for a Wind Turbine-Superconducting Magnetic Energy Storage Hybrid System Based on Current Source Converters

This paper proposes the unified control for a novel wind turbine-superconducting magnetic energy storage (SMES) hybrid system, where the SMES coil is integrated with the DC link of the current source converter (CSC) fed wind energy conversion system. The unified power and current control schemes are proposed for general grid conditions by designing the proper active damping, the closed-loop grid current regulation, and the decoupled double synchronous frame phase locked loop (DDSRF-PLL). Furthermore, the system operation schemes are proposed and designed for both the normal SMES current condition and the low SMES current condition. The performance of the proposed control schemes are verified by computer simulation.