Passive Pitch Control of Small Horizontal Axis Wind Turbines

Abstract

Abstract Small wind turbines utilize various mechanisms to regulate power. One concept is to pitch the blades to feather as wind speeds increase. This paper presents the development and application of an analysis tool to a conceptual passive pitch control of a 1 kW hori-zontal axis wind turbine that is based upon the rotor blades and generator characteristics of the Southwest Windpower’s Whisper H40 wind turbine. The current analysis and concept machine is constrained to only two-degrees of freedom (rotor spin about the main shaft and pitch-link motion about its pivot point) at 0 o yaw error with respect to the main wind direction. The current analysis tool is the starting point of a more complete methodology that will include addi-tional degrees of freedom. A simple strip theory model provides the aerodynamics as a function of the relative wind vector’s magnitude and local angle of attack. The second order dynamics equations of mo-tion for the two-degree of freedom system were solved using forth-order Runge-Kutta time integra-tion tools in MATLAB. Calculations for static and turbulent winds including IEC standard extreme wind conditions have been performed for the concept ma-chine. In summary, this paper presents the develop-ment and application of a new design/analysis tool specifically implemented for small wind turbines.