Stability and dynamic characteristics analysis of improved Spar-type wind power floating foundations

The stability and dynamic characteristics of the modified Spar-type offshore wind power floating foundation under the action of wind and wave coupling, based on the establishment of the dynamics model and the non-linear Mathieu equation, the boundary equations of the stable and unstable domains are solved based on Floquet theory, the Mathieu stability map is obtained, and the numerical simulation verifies the displacement between the stable and unstable domains with time. The results show that: in the same sea state background, When the ratio of heave motion frequency to pitch motion natural frequency is close to 2:1, even if the excitation amplitude is small, it will cause the pitch parameter excitation motion, increasing the system damping can reduce the unstable area, so as to effectively suppress that pitch parametrically-excited vibration of the float foundation. Under level 6 sea conditions, the maximum heave displacement of the floating foundation reaches 2.007 m and the maximum pitch angular displacement reaches 3.9534°, but it is still within the permissible range.