Output Power Smoothing of Grid-Tied PMSG-Based Variable Speed Wind Turbine Using Optimal Controlled SMES

Due to the stochastic nature of wind speed, energy storage systems are used to reduce the fluctuations of the output power of wind farms. In this paper, the superconducting magnetic energy storage (SMES) is used to smoothen the output power of a permanent magnet synchronous generator (PMSG) driven by a variable speed wind turbine. The PMSG is connected to the grid through a back-to-back converter. The SMES is connected to the DC link of the back-to-back converter through an asymmetrical converter. The Grey Wolf Optimizer ( GWO) is used to find the optimal parameters of a proportional-integral (PI) controller used to regulate the charge and discharge operation of the SMES unit. The grid-tied PMSG wind turbine system is modelled and simulated using PSCAD/EMTDC software. Wind speed data measured at Zaafarana wind farm, Egypt is used in evaluating the system's performance. Simulation results revealed that the optimal controlled SMES has smoothened the output wind power and reduced the total harmonic distortion of it.