Comparison of Results from Dynamic-Response Field Tests

The dynamic response of Howden's 3 30-kW horizontal axis wind turbine (HAWT) and the Northern Power Systems 100-kW 'North Wind 100' HAWT has been measured. The Howden machine incorporates a 26-m-diameter, upwind, three-bladed, wood/epoxy rotor that operates at 42 rpm and is a rigid-hub design. The North Wind 100 rotor has a diameter of 17.8 m, is upwind, two-bladed, and constructed of fiberglass,and has a teetered hub. The Northern Power turbine's blades are fully pitchable, while the Howden machine uses pitchable blade tips. This paper will present the results from each of these test programs in an effort to compare the dynamic response of each turbine. The analysis will focus on rotor bending loads in terms of both time domain and frequency response. The FLAP code will be used toexplore sensitivity to teeter stiffness and natural frequency placement to provide a better understanding of the differences in behavior caused by configuration alone. The results are presented in the form of normalized azimuth-averaged plots of the deterministic loads, and spectral density plots of the stochastic responses. This presentation of the results will contrast major responsedifferences due to design configurations.