Improved Control Strategy of DS-PMSG Based Standalone Tidal Turbine System Using Sensorless Field Oriented Control

Abstract

This paper presents a standalone tidal stream system with a focus on the reduction of the number of sensors needed by the control scheme. The electromechanical converter is a dual star permanent magnet synchronous generator (DS-PMSG) driven by a horizontal axis marine current turbine (MCT). The generator is controlled via a field oriented control (FOC) strategy and feeds a two three phase two level SVPWM converters, the speed and the position of the shaft are estimated using an extended Kalman filter (EKF), and the speed is regulated using a fuzzy logic controller. The system is simulated using Matlab/Simulink environment, the simulation results show the efficacy of the proposed control scheme, fuzzy speed regulator and the EKF estimator, however, the high number of pole pairs of the generator amplifies the position estimation error even if it was negligible, causing tracking errors of the electromagnetic torque and undesirable high d axis current, but the stability of the system is not affected.