This invention relates to a buoyant wind power station. More particularly, it relates to a buoyant wind power station in which a wind turbine is placed on an installation.

By an installation is meant, in this connection, a floating vessel in any form, such as a buoy, a barge, a ship or a platform.

Floating installations are subjected to partly considerable environmental forces from winds, currents and waves. Accord- ing to the kind of installation, environmental forces may set up considerable movements in the six degrees of freedom. In windmill structures, which are relatively tall, movements from pitching and rolling may constitute structural restrictions in the construction of the wind power station.

Several measures to remedy such problems are known. According to WO 2005/068835 wind speeds and movement are measured, the windmill being stopped by means of a brake if predetermined limit values are exceeded.

According to US 2005/0206168, additional floats are placed around a main float. The additional floats are of such a design that they provide considerably increased buoyancy if they are moved down into the water.

WO 03/004869 discloses a buoyant wind power station in which the design of the float together with the moorings restricts the tilt of the windmill.

It has turned out in practice that the prior art, with the exception of devices in which the windmill is stopped, has to be constructed as relatively large, heavy and thereby expensive structures for the intended effect to be achieved.

The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art .

The object is achieved according to the invention through the features which are specified in the description below and in the claims that follow.

A buoyant wind power station in which a wind turbine is placed on an installation is provided and is characterized by the installation being provided with a stabilizing gyro.

Because of the way it works, a stabilizing gyro arranged in the wind power station will counteract angular deflections of the wind power station around angular axes in directions other than the stabilizing gyro's own rotational axis. If the gyro rotates around a vertical axis, angular deflections in the form of rolling and pitching due to at least winds, waves and currents will be counteracted.

The positioning of the stabilizing gyro in the installation depends on the design of the installation and must, on the basis of known principles, be adjusted with respect to whether the centre of gravity of the wind power station is above or below the centre of buoyancy, among other things.

The stabilizing gyro may be constituted by one or more masses that are arranged in suitable positions, for example as part of the wind turbine, the axle, gear or generator of the wind turbine .

For example, the stabilizing gyro may be constituted by a separate flywheel rotating at relatively great speed, or a relatively large mass rotating at considerably lower speed.

If the relatively large mass is positioned at a relatively low level in the installation, it may form part of the ballast of the installation.

The mass of a slow-rotating stabilizing gyro may constitute 10-80 % of the installation weight, for example. Calculations show that at speeds of between 5 and 20 revolutions per minute, a good effect is achieved when the mass constitutes 30- 60 % of the installation weight.

The stabilizing gyro may surround the drive shaft of the wind turbine. If the drive shaft is vertical, as, with advantage, it may be if a Gelhard or Darrieus turbine is used, or also with other turbines when the generator of the windmill power station is placed in the installation, the stabilizing gyro will function in accordance with the intention.

If constituted by a separate mass, the stabilizing gyro may be driven by the drive shaft via a gear, or directly by the drive shaft. Alternatively, the stabilizing gyro may be driven by, for example, an electromotor.

The installation may be provided with at least two stabilizing gyros, wherein two stabilizing gyros may be counter- rotating. The stabilizing gyros may have different axes of rotation.

Because of the stabilizing gyro's way of working, dampening a rotation in one plane will cause the occurrence of a rotation perpendicular to the rotation which is being dampened. This may be counteracted by the counter-rotation of two stabilizing gyros .

In a relatively simple and cost-effective way, a stabilizing gyro in accordance with the invention could stabilize pitch 5 and roll deflections to a substantial extent.

In what follows is described an example of a preferred embodiment which is visualized in the accompanying drawings, in which:

Figure 1 shows schematically a wind power station which iso provided with a stabilizing gyro according to the invention; and

Figure 2 shows schematically a wind power station in an alternative embodiment.

In the drawings, the reference numeral 1 indicates a buoyants wind power station including an installation 2 floating in the sea 4 and being moored by means of moorings 6. The installation 2 is provided with ballast 8.

A drive shaft 10 projects vertically up from an electric generator 12, arranged relatively low in the installation 2, and0 up to a wind turbine 14 which is at a level above the installation 2. The drive shaft 10 rotates around a centre axis 16 and is supported in the installation 2 by means of an upper bearing 18 and a lower bearing 20. Thus, in this preferred exemplary embodiment, the drive shaft 10 is arranged to fol-s low the pitch and roll movements of the installation 2.

A stabilizing gyro 22 in the form of a rotatable mass is supported around the drive shaft 10 by means of gyro bearings 24. The stabilizing gyro 22 is driven from the drive shaft 10 by way of a gear 26. When the wind turbine 14 is set into rotation, the torque is transmitted to the generator 12 via the drive shaft 10. Some of the torque is transmitted by way of the gear 26 to the stabilizing gyro 22 which is given a relatively high speed of rotation.

When a pitch or roll movement rotates the centre axis 16 out of its vertical position, the stabilizing gyro 22 will, because of a gyro's way of working, known per se, counteract this rotation.

In an alternative embodiment, see figure 2, the stabilizing gyro 22 is placed relatively low in the installation 2, has a considerable mass relative to the total mass of the installation 2, has a relatively large radius, rotates relatively slowly and contributes to lowering the centre of gravity to a lower level.

In this alternative embodiment, the stabilizing gyro 22 may be connected to the drive shaft 10, whereby the gyro bearings 24 and the gear 26 are redundant.