DYNAMIC MODELING AND STABILITY ANALYSIS OF A DUAL-ROTOR WIND TURBINE

Various modal analysis methods are available for single rotor wind turbines, but there is no report and guidance on the modal property analysis of multi-rotor wind turbines. This paper presents a dynamic modeling method for the modal response analysis of a wind turbine with two three-bladed isotropic rotors. The equations of motion are derived using Lagrange's equations and are further linearized at a steady-state equilibrium. To avoid using Floquet Theory to remove the periodic coefficients, multi-blade coordinates are utilized. Comparison between the numerical simulations and a high-fidelity model in HAWC2 shows agreements in terms of modal frequencies. The results shows that the whirling modes splits into symmetric and asymmetric rotor modes.