Abstract

This paper presents the development and implementation of a novel fifth-order extended Kalman filter (EKF) observer for estimating the rotor angle and rotor speed during the sensorless grid synchronisation stage required to connect the stator of a doubly fed induction generator (DFIG) to the grid. The effectiveness of the proposed EKF is validated through simulations in MATLAB/Simulink and PLECS, using a 9 HP DFIG under a flux vector control-based synchronisation strategy implemented in the virtual grid-side reference frame under ideal grid conditions. The fifth-order EKF observer exhibits a fast transient response and low ripple currents in steady state, regardless of the rotor speed throughout the operating region. The proposed synchronisation approach can be seamlessly integrated with the conventional EKF model after synchronisation, making it a promising solution for sensorless DFIG startup in wind energy applications. © 2025 IEEE.