Novel high-stability semi-submersible fan foundation and design method thereof

Abstract

The invention relates to a novel high-stability semi-submersible fan foundation. The novel high-stability semi-submersible fan foundation comprises a central pillar, side pillars, floating boxes and diagonal bracings; the central pillar is divided into two sections, wherein the diameter of the lower section is uniform, and the diameter of the upper section is decreased progressively from bottom totop; the side pillars comprise a plurality of sets of oblique side pillars and vertical side pillars which are distributed in the circumferential direction and connected with one another, the obliqueside pillars are oblique from bottom to top toward the outer side, and the upper ends of the vertical side pillars and oblique side pillars are connected; the floating boxes are fixedly connected with the bottom ends of the oblique side pillars and central pillar, and the floating boxes form a transverse divergent structure taking the bottom of the central pillar as the center; one ends of the diagonal bracings are connected with the central pillar, and the other ends of the diagonal bracings are connected with the vertical side pillars; a water plane is located at the lower section of the central pillar, under the diagonal bracings, and at the position where the vertical side pillars are located e; the distance between the lower ends of the vertical side pillars and the water plane is the wave amplitude height of a wave once a year under the sea state of a platform; the floating boxes, the central pillar and the side pillars are all of hollow structures, and provide buoyancy for thefan foundation.

Description

technical field [0001] The invention relates to an offshore wind turbine foundation, specifically, a novel semi-submersible wind turbine foundation with high stability. Background technique [0002] According to different water depth conditions, offshore wind farms can be divided into: intertidal zone wind farms, offshore wind farms and distant sea wind farms. Among them, offshore wind farms, that is, sea areas with a water depth of 50m below the theoretical lowest tide level, need to adopt floating foundations to reduce development costs. At present, floating foundations are divided into the following three categories: column foundations (Spar), semi-submersible foundations (Semi-submersible) and tension leg foundations (TLP). Among them, Spar has a lower center of gravity and a smaller draft area, and has better stability, but it is only suitable for deep-water sea areas and the assembly and installation of components are complicated; TLP has a small The motion response ...

AI Technical Summary

Problems solved by technology

This method will greatly lengthen the connecting structure between the columns, increasing the stress and structural fatigue of the supporting rods; ② increasing the cross-sectional area of ​​the columns

This will directly lead to an increase in the water surface area and drainage volume of the floating foundation, increase the construction cost, and reduce the installed power; at the same time, it also reduces the heave period. When the wave frequency excites energy close to the natural frequency of the heave When this happens, the platform will resonate, which will have a bad influence on the hydrodynamic performance, greatly intensify the movement of the semi-submersible fan foundation on the sea surface, and increase the potential safety hazard

[0005] 2) The semi-submersible wind turbine foundation has a higher center of gravity than the Spar type and TLP type, so that the stability margin of the platform is not large

To lower the center of gravity, the ballast needs to be adjusted downwards, but due to the relatively small draft of the platform, the space to adjust the ballast is extremely limited, resulting in serious limitations

[0006] 3) The existing semi-submersible foundation uses bar structures such as cross braces and diagonal braces to connect each column. However, due to many manufacturing difficulties and potential fatigue failure risks, this is not good for floating structures

In addition, the foundation of the fan produces six-degree-of-freedom movement under operating conditions, and the water entering and exiting the rod structure will cause the displacement and the area of ​​the water plane to change from time to time, making the platform's motion state unstable

[0007] 4) The existing floating fan foundations at home and abroad all use circular columns, and the processing of a single circular column is difficult and has high precision

Compared with the square column, the vortex-induced motion performance is poor, resulting in a large-scale lateral motion under the action of ocean currents, resulting in a decrease in the relative wind speed stability, thereby reducing the wind energy conversion efficiency of the wind turbine

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