Direct power control of SRG-based WECSs using optimised fractional-order PI controller

This study introduces two fractional-order proportional-integral (FOPI) controllers optimised by harmony search (HS) optimisation algorithm, for direct power control of switched reluctance generator (SRG) through regulating the off-delay angle of the generator. These two proposed FOPI controllers aim at improving the integration of SRG into the wind energy conversion system (WECS) through two control modes. The two control modes are maximum power point tracking during healthy operation with wind speed variation and fault ride-through capability during faulty conditions. On the basis of the voltage magnitude at the point of common coupling between the SRG and grid, each mode, and consequently, the corresponding FOPI controller is activated. Comparison between FOPI controllers and classical PI controllers optimised by HS is introduced. Simulation results show the capability of the two modes of control proposed for improving the SRG-WECS performance in both healthy and faulty operating conditions with the superiority of FOPI controller over conventional PI controllers. An experimental platform is built to show the adequacy of the proposed FOPI controller of SRG.