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. Starti ng 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 turbin e's 5 m diameter blades produce 5 kW at a wind speed of 10 m/s. At this pit ch, 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 accelerat ion. The aerodynamic torque was obtained from a quasi-steady blade element analysis and the resistive torque of the drive train and generator was subt racted to determine the net torque accelerating the blades. The agreement b etween predicted and measured angular velocity was generally good and impro ved as the pitch angle increased. (C) 2000 Elsevier Science Ltd. All rights reserved.