Since the extracted power from a wind turbine is always fluctuating, due to the continuous variations of the wind speed. A new technique for controlled frequency supply generated from a stand alone wind turbine is designed and implemented in laboratory environment.
This technique is based on a controller by which the output power of the wind turbine is divided into two parts, the first part is considered to be constant power which is kept at a constant frequency, the second part has the remaining output power. Two induction generators connected to the same shaft driven by the wind turbine simultaneously generate these two parts.
The first induction generator generates the constant output power, which feeds a critical load, while the second induction generator, which generates the remaining output power, is connected to a non-critical load through a three-phase bridge converter.
The non-critical load extracts any fluctuation of the output power of the wind turbine to keep constant shaft speed. The paper includes the design of the bridge converter and the associated firing circuit, PID controller and the principle of the controlled system.