The starting behaviour of a small horizontal-axis wind turbine

This paper presents selected results taken from an extensive investigation of the starting performance of a small horizontal-axis wind turbine. Starting was observed for blade pitch angles varying between 0 and 35 degrees in 5 degrees increments. At 0 degrees, the angle for maximum power, the turbine's 5 m diameter blades produce 5 kW at a wind speed of 10 m/s. At this pitch, starting is characterised by a long "idling period" in which the blade's angular velocity increased only slowly because of the very high angles of attack. As the pitch angle increased, the idling period decreased. At all pitch angles, the measurements of angular velocity are compared with those obtained from a numerical integration of the equation for angular acceleration. The aerodynamic torque was obtained from a quasi-steady blade element analysis and the resistive torque of the drive train and generator was subtracted to determine the net torque accelerating the blades. The agreement between predicted and measured angular velocity was generally good and improved as the pitch angle increased. (C) 2000 Elsevier Science Ltd. All rights reserved.