A Robust Sensorless Speed Estimation Method for SCIG based WECS with Reduced Current Sensors

Owing to the increasing demand for electric power there exist an increased penetration of renewable energy sources with the grid. However, this is now the major reason for grid instability. Thus, for precise power control and grid integration of Wind Energy Conversion Systems (WECS), accurate angular grid frequency and speed signal is necessary. In this regard, a sensorless speed estimation method is proposed for wind driven SCIGs with reduced number of current sensors. Unlike the other methods reported so far, this method brings forth a sensorless method which is capable of computing all the variations in speed signal either under dynamic speed variations or ripples in speed in case of distorted grid conditions. Here, the rotor speed signal is derived from the measured stator voltages and a single stator current signal, thus facilitating high reliability and robustness in speed computation. The efficacy of the proposed scheme is shown using simulation results on a 2.2 kW SCIG in MATLAB Simulink.