A Control Strategy for Output Maximisation of a PMSG-Based Variable-Speed Wind Turbine

Abstract

This paper presents a control strategy for output maximisation of a direct drive permanent magnet synchronous generator (PMSG)-based small-scale variable-speed wind turbine. The control topology uses a single switch three-phase switch-mode rectifier and the generator torque, and power is controlled by controlling the switch duty cycle of the switch. To extract maximum power from the wind, the torque reference of the PMSG is calculated from generator speed and wind turbine characteristics. From this torque reference, a current reference is calculated using measured DC link voltage and generator speed. The current error is then used to control the duty cycle of the switch-mode rectifier and thereby torque of the generator is regulated through a proportionalintegral regulator. The operational characteristics of the generating system are investigated under varying wind speed through extensive simulations and the results confirm that the proposed control strategy can maximise the output power under fluctuating wind speeds.