Position Sensorless Control of Grid-Connected Doubly Fed Induction Generators: A Comprehensive Review and Emerging Trends

With the rapid global expansion of wind energy and increasing deployment of large offshore turbines, achieving reliable sensorless control of wind energy conversion systems (WECSs) has become increasingly important. This paper presents a comprehensive review of modern sensorless control techniques for the doubly fed induction generator (DFIG), which is a dominant technology in variable-speed WECSs. This review focuses on control strategies and rotor speed and position estimation techniques, covering their theoretical foundations, operational characteristics, and emerging research trends. In addition, sensorless operations of the DFIG beyond power generation, including grid synchronisation and stand-alone operation, are presented, providing a foundation for future research in the field.