New control strategy for variable speed wind turbine with DC-DC converters

The paper studies the performance of variable speed wind turbine (VSWT) configuration with non-inverting buck-boost converter. The wind turbine systems consist of permanent magnet synchronous generator (PMSG) connected to diode rectifier, DC chopper and load. New control strategy, based on the maximum power point tracking (MPPT) and limited power point tracking (LPPT) algorithms is used to improve the system operation. When necessary to limit the power injected to the grid, due to system operator demands, a control unit is implementing to switch between two regimes of wind turbine operation: at maximum power and at limited power. The MPP tracker is simple perturb and observation (P&O) controller in combination with two optimum wind turbines power/torque versus speed characteristics. Two control loops: inner feed forward current control loop and outer voltage control closed loop are applied for the non-inverting buck-boost converter. The performance of the dynamic models and the control loops is tested under various wind conditions. The simulation results are shown. The results prove the strategy and models reliability.