The aim of this study was to propose and evaluate a very small wind turbine
(VSWT) that competes with commercial grid-connected VSWTs in terms of simplicity,
robustness and price. Its main components are a squirrel-cage induction generator (SCIG)
driven by a frequency converter. The system has a direct-drive shaft, and may be
constructed with commercial equipment. Simulation of the wind turbine effect is done with
a motor. A control program regulates the variable-speed of rotation through three
operational modes: (i) to drive the turbine to its optimum operation point; (ii) to limit its
maximum rotational speed; and (iii) to limit the maximum power it generates. Two tests
were performed, in order to evaluate the dynamic response of this system under variable
wind speeds. The tests demonstrate that the system operates at the optimum operational
point of the turbine, and within the set limits of maximum rotational speed and maximum
generated power. The drop in performance in relation to its nominal value is about 75%,
when operating at 50% of the nominal power. In summary, this VSWT with its proposed
control program is feasible and reliable for operating direct-shaft grid-connected VSWTs.
