A Grey Wolf Optimizer for Optimum Parameters of Multiple PI Controllers of a Grid-Connected PMSG Driven by Variable Speed Wind Turbine

This paper presents a novel application of a grey wolf optimizer (GWO) to improve the low voltage ride through (LVRT) capability and the maximum power point tracking (MPPT) of a grid-connected permanent-magnet synchronous generator driven directly by a variable-speed wind turbine (DD-PMSG-VSWT). The LVRT capability and MPPT enhancements are achieved by the optimal tuning of eight proportional-integral (PI) controllers in the cascaded control of the machine-side converter and the grid-side inverter, simultaneously. An online optimization is used and achieved by minimizing the integral-squared error of the error inputs of the PI controllers that are controlling dc link voltage, generated real power, and terminal voltages of the PMSG and the grid. The symmetrical and asymmetrical faults for testing the optimum gain parameters are simulated and examined using PSCAD/EMTDC. The obtained results of the optimum values of the GWO algorithm are compared with those attained using the optimum values of the genetic algorithm and the simplex method.