CONTROL BY VARIABLE ROTOR SPEED OF A FIXED-PITCH WIND TURBINE OPERATING IN A WIDE SPEED RANGE

Variable rotor speed control of a fixed-pitch wind turbine is investigated on a system consisting of a wind turbine which can operate in a wide speed range, from 0 to 38 Rpm. It produces any desired output from the rated (20 kW) to no-load, providing there is wind enough. A special technique is used to determine the operating point of the wind turbine by using the measured rotor speed and power. A difficult problem with this type of wind turbine control is to determine the upper speed limit reasonably high to capture as much energy as possible but still low enough to avoid power peaks.