Application of superconductors to improve the performance of DFIG-based WECS

This paper presents a new cost-effective technique to improve the performance of doubly fed induction generator (DFIG)-based wind energy conversion systems (WECS) during wind gust and fault events through the integration of high temperature superconductor (SC) within the DC link of the rotor side and grid side converters that interface the DFIG rotor with the grid. Fractional order proportional integral (FOPI) controller is employed to control the energy exchange between the SC and the system through controlling the duty cycle of the DC chopper interfacing the SC with the DC link. Rating of the SC and parameters of the proposed FOPI controller are precisely calculated using harmony search optimization technique in order to regulate the DFIG generated power and improve its fault ride through capability during disturbance events. To validate the superiority of the proposed FOPI controller, the performance of the studied system is also investigated when a conventional PI controller is employed. Results reveal the ability of the proposed topology and controller to improve the performance of the DFIG-based WECS during wind gust and short circuit faults at the DFIG terminals.