Sensorless Strategy of a Two-Level MPPT for Permanent Magnet Wind Generation System Using SRF-PLL

Abstract

This paper presents the optimization of the wind power in a variable speed Wind Energy Conversion System (WECS) using a sensorless Maximum Power Point Tracking (MPPT) strategy that avoids mechanical measurement of the wind speed. The proposed system consists of a turbine, a direct-drive Permanent Magnet Synchronous Generator (PMSG) controlled by a Field Oriented Control (FOC) through a three phase controlled rectifier connected to a DC load. The choice of the FOC is justified by a power maximization analysis. The generator rotor speed and position required by the FOC and the sensorless MPPT are estimated using a Synchronous Reference Frame Phase Locked Loop (SRF-PLL). The proposed technique is validated using both simulation in Matlab-Simulink and experimental work based on step changes in wind speed. Results are presented at the end of the paper showing that the estimated angle and speed by the SRF-PLL are approximatively the same as the real ones, also figure of the output power shows that it is maximized confirming the effectiveness of the adopted approach.