| CPC F03D 13/25 (2016.05) [B63B 21/502 (2013.01); B63B 35/44 (2013.01); E02D 27/425 (2013.01); E02D 27/525 (2013.01); B63B 2035/446 (2013.01)] | 7 Claims |
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1. A floating windmill, comprising a floating element and a wind turbine, the floating windmill comprising:
a tension leg in the form of one or more rigid structures, wires or combined rigid structure and wires, oriented vertical in a low-force operating condition;
an anchoring;
a buoyancy element fully submerged in an operating condition, providing tension in the tension leg as arranged between the anchoring and the buoyancy element, wherein the buoyancy element includes a buoyancy system that includes a pump, piping and valves, for adjusting a ballast water level in the buoyancy element;
a swivel, wherein the swivel is arranged in the buoyancy element;
a rigid cross bar fully submerged in the operating condition, connecting the buoyancy element and the floating element;
wherein the floating windmill in operation is configured with the wind turbine on an upper end of the floating element extending up above sea level, with a lower end or part of the floating element submerged in sea, with the rigid cross bar on one end connected to the lower end or part of the floating element and on an opposite end connected to the buoyancy element, with the rigid cross bar fully submerged, with the buoyancy element fully submerged, with the tension leg arranged between the buoyancy element and the anchoring on a seabed;
wherein the floating element with the wind turbine on the upper end can weathervane freely around the buoyancy element, wherein in a low force condition when the forces by ocean current, wind and waves are low, the floating element, the buoyancy element and the tension leg are oriented in a vertical direction within 5° from an equilibrium condition and the rigid cross bar is oriented in a horizontal direction within 5° from the equilibrium condition, wherein, in the equilibrium condition, the floating element, the buoyancy element and the tension leg are oriented in the vertical direction and the rigid cross bar is oriented in the horizontal direction; and
wherein in a high force condition when the forces by ocean current, wind and waves are high, a shape of the floating element, the rigid cross bar, the buoyancy element and the tension leg is stretched by the forces to provide a stretched shape, wherein the orientation of the vertical and horizontal elements is deviated from the equilibrium condition by more than 5°, which change in shape and dynamic behavior reduce extreme stress levels in the floating windmill.
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4. A method of at least one of installation and maintenance of a floating windmill, the floating windmill comprising:
a floating element and a wind turbine, the floating windmill comprising:
a tension leg in the form of one or more rigid structures, wires or combined rigid structure and wires, oriented vertical in a low-force operating condition;
an anchoring;
a buoyancy element fully submerged in an operating condition, providing tension in the tension leg as arranged between the anchoring and the buoyancy element;
a swivel, wherein the swivel is arranged in the buoyancy element;
a rigid cross bar fully submerged in the operating condition, connecting the buoyancy element and the floating element;
wherein the floating windmill in operation is configured with the wind turbine on an upper end of the floating element extending up above sea level, with a lower end or part of the floating element submerged in the sea, with the rigid cross bar on one end connected to the lower end or part of the floating element and on an opposite end connected to the buoyancy element, with the rigid cross bar fully submerged, with the buoyancy element fully submerged, with the tension leg arranged between the buoyancy element and the anchoring on a seabed;
wherein the floating element with the wind turbine on the upper end can weathervane freely around the buoyancy element, wherein in a low force condition when the forces by ocean current, wind and waves are low, the floating element, the buoyancy element and the tension leg are oriented in a vertical direction within 5° from an equilibrium condition and the rigid cross bar is oriented in a horizontal direction within 5° from the equilibrium condition, wherein, in the equilibrium condition, the floating element, the buoyancy element and the tension leg are oriented in the vertical direction and the rigid cross bar is oriented in the horizontal direction; and
wherein in a high force condition when the forces by ocean current, wind and waves are high, a shape of the floating element, the rigid cross bar, the buoyancy element and the tension leg is stretched by the forces to provide a stretched shape, wherein the orientation of the vertical and horizontal elements is deviated from the equilibrium condition by more than 5°, which change in shape and dynamic behavior reduce extreme stress levels in the floating windmill
the method comprising:
installing and maintaining the floating windmill in components;
wherein the installation takes place by transporting the floating element and the wind turbine to a windmill site, where the components are coupled to the buoyancy element that has been preinstalled with an anchor on the seabed; and
wherein the buoyancy element includes a buoyancy system or facilities for connecting to a buoyancy system on a vessel, comprising a pump and piping and valves, for adjusting a ballast water level, allowing to bring the buoyancy element up and down between a surface position and a submerged position, wherein a coupling of the buoyancy element to the rigid cross bar can take place near or at the surface position.
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