Dynamic loading on an upwind HAWT in yawed flow conditions: stochastic loads and resonant behaviour

摘要

As part of an investigative programme into the behaviour in yawed flow of horizontal-axis wind turbines of various sizes, measurements of dynamic loads have been obtained from a 15 kW upwind-rotor machine. Bending moments about 2 axes were recorded for all three blades at intervals of 10" rotor azimuth. Yaw torque was calculated by synthesising contributions from the blade flap moments, and compared with readings from a tower-mounted torsion sensor. Records of tower bending moment were made at the same time intervals as those used for the blades, enabling an investigation of resonant behaviour. Deterministic responses have been described in an earlier paper; here, discussion is con-fined to stochastic loads and resonant effects. It was found that good control of rotor yaw error offers no protection against the occurrence of extreme yaw loads. The magnitudes of these loads were as expected for a machine of this size. In the tower, significant bending and tor-sional resonances were observed, which complicated responses and were in some cases large enough to give cause for concern.