Variable Step HCS Based Sensorless Control of Wind Driven DFIG for Autonomous Operation

This paper presents a sensorless scheme of a wind turbine driven doubly fed induction generator (DFIG) in standalone mode. The sensorless scheme is based on modified hill climb search (HCS) method and the system is immune to mechanical and electrical problems of anemometer. The scheme uses variable frequency sampling time for error free generation of speed set point for the wind turbine generator. The scheme is suitable for both standalone and grid connected modes of operation. The modeling and simulation of sensorless wind energy system, are carried out in MATLAB/Simulink environment using SimPowerSystems tool box for different scenarios like variable wind speeds, change in load and nonlinear unbalanced load connected at point of common coupling (PCC). The DFIG stator voltages and currents are found sinusoidal and balanced and, follow the IEEE 519 standard. A comparison of proposed maximum power point tracking scheme with tip speed ratio method incorporating wind speed measurement, is also presented. Finally, the presented scheme is tested on a developed prototype in the laboratory to validate its performance both in steady state and dynamic conditions.