Improved MRAS Rotor Position Observer Based on Control Winding Power Factor for Stand-Alone Brushless Doubly-Fed Induction Generators

The main contribution of this study is to propose a new rotor position observer with the approach of model reference adaptive system (MRAS) associated with the quantity of control winding (CW) power factor of the brushless doubly-fed induction generator (BDFIG) for sensorless voltage control target in stand-alone systems. The proposed observer relies on the field-orientation scheme of power winding (PW) side. The proposed sensorless methodology does not need any computation process with integration for obtaining the flux components. In addition, the new methodology can reduce the voltage sensors required for detecting the actual CW voltage quantities to be used in the calculations process of the proposed MRAS procedure by directly realizing the CW reference stationary voltages from the input path of SVPWM. This would ensure the simplicity of the suggested procedure for detecting the rotational position of the generator. The stability confirmation of the presented estimation method is analyzed and realized with the aid of technique of hyperstability concept and aided with the criteria of Popov's analysis. Moreover, the verification of robustness for the proposed observer is studied via uncertainty issues of machine parameters. Comprehensive simulation and experimental results are carried out on a test prototype of BDFIG to verify the control procedure.