Abstract
In order to obtain high efficiency of energy conversion in a wind turbine generator system, it is desirable that the magnitude of the turbine torque driving the generator is set to be proportional to the square of the rotor shaft speed. In a WTG system with constant magnetic field generator, this can be achieved by making the generator's output current be proportional to the square of the shaft speed. However, detailed characteristics of the wind turbine are requied in advance to determine the value of the proportionality coefficient.
This paper proposes the method which controls the proportionality coefficient and makes it match to the specific wind turbine under operation in natural wind field, without the preliminary knowledge of the turbine characteristics. The method can be applied to the systems with a propeller type wind turbine and a constant magnetic field DC generator.
