Implementation and performance evaluation of controller signal embedded sensorless speed estimation for windturbine doubly fed induction generators

This paper reports a novel sensorless speed estimation method for wind turbine doubly fed induction generators that is highly non-invasive and utilises the readily available generator drive controller signals. A generalised analytic analysis is first presented that allows the assessment, identification and study of the controller signal spectral content needed to allow the establishment of real time speed estimation. An overlapping window parabolic interpolation algorithm is then proposed for tracking the controller signal speed dependent spectral content, with a view to provision of an increased real-time estimation rate. The reported method is implemented on a vector controlled doubly fed induction generator laboratory system and tested in transient operating regimes representative of wind generator application. The test results show that high accuracy high estimation rate is achievable in field application characteristic transient dynamics.