DE29913625U1 - Wind turbine - Google Patents

Description

05.08.1999 02110-99 LafiVbs

Dr. Richard Metzler D-82343 Pocking

Wind turbine

The present invention relates to wind turbines with a buoyancy body, a cable for anchoring the buoyancy body to the earth's surface, a rotor arrangement and a generator coupled thereto, which are attached to the buoyancy body by means of a suspension and can be pivoted relative to it.

Wind turbines for environmentally friendly electricity generation have established themselves as a technically serious option for generating electricity. Although the number of turbines has increased significantly, their share of the total electricity supply is still negligible.

A major reason is that in many places the wind energy is not sufficient for the economic operation of a plant. It must be taken into account that the wind speed is slowed down to zero immediately on the ground. The further away from the ground the wind speed increases, as the influence of ground or surface friction and the resulting turbulence of the wind becomes smaller and smaller.

Measurements carried out in Germany have shown that in areas with little wind, wind speeds of 7 m/sec can be reached at an altitude of 100 metres and in areas with strong winds, they can reach around 8 m/sec. In particular, the gustiness of the wind decreases considerably above an altitude of 100 metres above the ground.

In the well-known wind power plants, the rotor, the generator and the corresponding gear are mounted on a tower. Due to technical and economic limitations, the height of the towers is limited. As a rule, hub heights of up to around 65 meters are built. One exception was the large wind turbine "Growian", which had a hub height of 130 meters. However, this was a one-off project, as the technical problems and costs were far from being economically viable.

However, if the economically viable, low construction heights are implemented, only a few areas have sufficiently consistently high wind speeds. The coasts are particularly suitable for wind turbines. Another problem with conventional wind turbines is that the towers with their mounted rotors are perceived as disruptive to the landscape. For this reason, plans are already being made to install large wind turbines offshore, i.e. far from the coast on the open sea.

In order to counteract the problems mentioned above and to make wind turbines usable in areas where the wind speed is relatively low and fluctuates greatly in regions close to the ground, it has already been proposed to position the rotor and the generator above at least one buoyancy body, such as a gas balloon, which is anchored to the ground by means of ropes. The rotor and, if necessary, the gearbox and the generator are therefore mounted below a floating buoyancy body instead of at the top of a tower. This makes it possible to increase the hub height of the rotor arrangement to several hundred meters. Accordingly, the wind turbine can be used almost anywhere, regardless of the ground conditions at a specific location. Due to the high altitudes

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The prevailing high wind speeds guarantee a high energy yield.

Even if a system of this type has not yet been built, the principle described has been known since the 1920s (see AT-PS 10 55 36). Publications have already documented a wide variety of design proposals for this basic principle (DE 25 24 360 A1, DE 31 00 085 A1, DE 41 17 952 A1, DE 195 26 129 A1), and in some cases, options for transmitting power from several rotors suspended from a buoyancy body to a central generator have also been proposed (see AT-PS 372 764, US 44 50 364, DE 37 29 087 A1).

In order to achieve an effective conversion of wind energy into electrical energy, different rotor designs have already been considered, and the question of the optimal positioning of the rotor arrangement in relation to the wind direction has also been taken into account. For example, DE 25 24 360 shows a wind turbine of the type mentioned above, in which the rotor arrangement is pivotally mounted relative to the lifting body and is connected to a tail unit in the manner of a wind vane, which is intended to ensure a favorable positioning of the rotor arrangement in relation to the wind direction.

In addition to the fact that considerations of electricity generation from renewable sources have only become more important in recent years, it has also not been possible to implement the existing concepts for wind turbines for economic and technical reasons.

Firstly, there are problems due to the strongly fluctuating wind energy. While in most areas the winds are relatively light, on some days of the year heavy storms can be expected. The necessary strength for this requires a relatively high weight for the rotors used to date, so that large buoyancy bodies are necessary. The design of the buoyancy bodies is also difficult. Since round balloons can only float up to

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While streamlined balloons without an internal structure are storm-proof up to wind speeds of around 15-17 m/sec, the designs proposed so far would require a stable internal framework structure similar to a real zeppelin, which would, however, multiply the cost of the buoyancy body. Even this zeppelin is not suitable for withstanding a heavy storm with speeds of over 40 m/sec.

Another problem is the durability of the balloon envelopes. According to the current state of technology, this is limited to 5-7 years. The reason for this is the decomposition of the polymers that form the envelope of the gas balloon due to the strong UV radiation. This lifespan is not a problem for sports balloons and the like, but for a wind turbine, the relatively frequent replacement of one of the most expensive components would lead to an unacceptably high cost burden.

The present invention is therefore based on the object of creating an improved wind turbine of the type mentioned at the beginning, which avoids the disadvantages of known systems from the prior art. In particular, a technically safe and economical implementation of this system concept is to be created.

According to the invention, this object is achieved in a wind turbine of the type mentioned at the outset in that a swivel drive with which the rotor arrangement can be swiveled from its working position out of the wind into a storm-proof position, a wind detection device for detecting the wind strength and a swivel control device for controlling the swivel drive depending on the detected wind strength are provided.

A storm protection is therefore provided to prevent damage or even destruction of the system due to excessive wind speeds. If a predetermined wind speed is exceeded, the rotor is automatically swung out of the wind and brought into a safety position in which the attack

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surface of the rotor arrangement is reduced and rotation of the rotor arrangement is largely prevented. The provision of a separate swivel drive and the automatic control system makes it possible to react immediately to excessive wind speeds without a time delay and to quickly secure the wind turbine.

In a further development of the invention, a tail unit, which serves in the manner of a wind vane to adjust the rotor arrangement and is connected to it via a boom extending downstream of the rotor arrangement, is designed to be tiltable relative to the rotor arrangement by means of a tilting mechanism. Preferably, the tail unit can be pivoted away together with the boom supporting it by approximately a right angle. In the working position, the tail unit is rigidly connected to the rotor arrangement and, together with it, is pivotably mounted relative to the buoyancy body so that the rotor arrangement can align itself with the wind. If a predetermined wind speed is exceeded, the tail unit is then pivoted away into a safety position. Preferably, the tilting mechanism has an electric servomotor for this purpose, which is controlled by the pivot control device depending on the wind strength.

According to a further preferred embodiment of the invention, the rotor arrangement, the generator and the tail unit form a single assembly which can be pivoted as a whole relative to the suspension. The rotor arrangement and the generator can be permanently installed on a nacelle to which the tail unit is pivotably attached, the nacelle in turn being pivotably mounted relative to the buoyancy body. The pivot axis of the nacelle and the pivot axis of the tail unit relative to the nacelle are preferably arranged parallel to one another, in particular horizontally. In order to be able to quickly pivot the rotor arrangement relative to the buoyancy body, a servomotor, in particular an electric one, can be provided which is connected between the rotor arrangement and its suspension. In particular, the servomotor can be provided for pivoting the nacelle.

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According to a further preferred embodiment of the invention, the length of the cable and thus the height of the system is automatically adjusted by cable winches. Several wind sensors attached at different heights on the balloon, the gondola and the cable measure the wind strength in this area and transmit the data to a computer on the ground. This calculates the optimal operating height and controls the cable winches. If the wind changes, the altitude control device registers the change and uses the available values to determine the new optimal rotor height. It triggers a corresponding signal to the cable winches of the altitude adjustment device, which gives or pulls cable until the new target position is found.

In order to secure the wind turbine during storms, the height control device is designed in a further development of the invention in such a way that the buoyancy body with the rotor arrangement attached to it is pulled to the earth's surface when a predetermined wind speed is reached. The height control is therefore designed as a storm protection device. Together with the swivel control for the rotor arrangement described above, the height control device designed in this way can provide effective protection against damage or destruction of the rotor arrangement by storms.

In order to protect the sensitive buoyancy body from storms, a depression can be provided in the area where the rope is anchored to the earth's surface to accommodate the buoyancy body. The depression is preferably designed as a funnel-shaped hole in the ground with a smooth surface. Appropriate fixing means, in particular a net of strong ropes, can be provided to fix the buoyancy body in the depression. In addition, a ring-shaped wall can be built using the excavated earth. In this way, even strong storms can hardly damage the buoyancy body.

In the stationary wind turbines used to date, the massive rotor blades, mostly made of glass fibre reinforced plastic, are a major component

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sten factor. If these are used together with a balloon, they require large buoyancy bodies due to their weight, which in turn are more sensitive to storms and significantly more expensive. In a further development of the invention, therefore, no solid rotor blades are used, but rotors with rotor blades in a lightweight construction. This not only makes the rotor cheaper, but above all reduces its weight. This reduces the forces that can endanger the stability of the system, and the use of a rotor in a lightweight construction enables the wind turbine to be lighter, so that relatively smaller and therefore less expensive buoyancy bodies can be used.

The lightweight construction of the rotor blades can be designed in various ways. In particular, the rotor blades can be designed as a hollow construction. In a further development of the invention, the rotor blades consist of an internal frame and a covering applied to it. The covering can actually be made of a cloth or film, in particular a synthetic fiber fabric. In order to achieve greater strength of the covering, the frame can be covered with thin metal sheets or plastic plates. The frame structure itself, which forms a load-bearing core, is made of a sufficiently strong material, in particular metal, wood or plastic. Such a construction of the rotor blades results in a minimal dead weight with sufficient strength and also in relatively easy repair if some struts break or the surface is damaged.

According to another advantageous embodiment of the invention, the rotor blades each consist of a metal or plastic rod and a sail stretched across it. The rod, which acts like the mast of a sailing ship, is fitted with a sailcloth. This allows a particularly simple and lightweight design of the rotor blades to be achieved.

In order to enable the best possible use of the respective wind speeds, a rotor arrangement with variable rotor blade area is provided in a further development of the invention. The rotor area can preferably be automatically adapted to the prevailing wind strength. For this purpose, appropriate means are provided which are controlled by a rotor area control device depending on the detected wind strength. The measurement signals from the wind sensors already mentioned can be used for this.

The variability of the rotor surface can be achieved in different ways. In the sail design of the rotor blades mentioned above, a reefing device can be provided for reducing and increasing the sail surface with a drive that can be controlled automatically by the control system. An electric motor and a cable pull coupled to it are preferably provided as the drive. For example, the corresponding sails can be wound onto parts of the rods or pulled into the interior of corresponding rod parts.

According to a further embodiment of the invention, the rotor arrangement can have a rotor whose rotor blades can be assembled in a modular manner from various rotor blade pieces, so that a change in surface area can be achieved by inserting additional rotor blade pieces or differently sized rotor blade pieces. The rotor blades are variable in length, the rotor diameter is adjustable. By changing the rotor blade surface, the wind turbine is given a sort of "gear shift" through which a more uniform performance profile can be achieved. The performance of the wind turbine is stabilized.

In order to increase the stability of the rotor blades in a lightweight construction, a guying system for the rotor blades can advantageously be provided. In particular, a central holding mandrel extending along the axis of rotation of the corresponding rotor is provided, to which guy ropes for the rotor blades are attached. The guying system can be designed on one side, in particular arranged on the inflow side of the rotor blades, in order to prevent excessive stress on the rotor blades.

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blades caused by strong gusts. If necessary, the guying can also be carried out on both sides.

In order to meet the requirements for balloon envelopes, high-quality synthetic fiber materials are preferably used as balloon materials. These have the required gas-tightness, tear resistance and at the same time the necessary corrosion resistance in relation to temperature fluctuations, UV radiation and moisture. However, UV radiation decomposes the polymers of the envelope over time, so that the gas-tightness is no longer guaranteed.

To extend the life of the balloon envelope, it is suggested to cover it with a protective cover made of a simple, cheaper material that is optimized exclusively for UV resistance. In particular, the protective cover can have a reflective outer side and a black absorbent inner side. This protective cover prevents the actual envelope from being directly exposed to UV radiation. When the protective cover is worn out, it is replaced without the need for a new, expensive balloon envelope. In this way, the life of the balloon envelope can be significantly extended with limited investment.

The balloon can be designed as a multi-chamber or single-chamber version. The buoyancy body receives the necessary buoyancy force from a filling consisting of a gas that is lighter than air, preferably hydrogen and/or helium. The balloon can preferably be spherical or "zeppelin-shaped", i.e. oval with tail fins.

These and other features emerge not only from the claims but also from the following description and the associated drawings, which explain a preferred embodiment in more detail. In the drawings:

Fig. 1 a schematic representation of the wind turbine at a glance

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Fig. 2 is a schematic representation of the wind turbine similar to Fig. 1, showing in detail the lifting body, the rotor, the generator and the tail unit as well as the associated suspension on the lifting body.

Fig. 3 is a schematic partial view of the rotor arrangement and its suspension in its working position,

Fig. 4 is a schematic partial view of the rotor arrangement and its suspension in a securing position,

Fig. 5 is a schematic representation of the wind turbine (a) in its working position before the turbine is brought to the ground before a storm and (b) in its safety position after it has been brought to the ground during a storm, and

Fig. 6 is a partial view of a rotor whose rotor blades can be assembled in a modular manner from several rotor blade pieces.

The wind turbine shown in Fig. 2 has a rotor arrangement 1 with a single rotor 2, which in the embodiment shown there consists of a three-bladed horizontally running propeller. The rotor 2 is coupled via a shaft to a generator 3, which is arranged in a nacelle 4. If necessary, a reduction gear can be connected in front of the generator 3, which can also be arranged in the nacelle. On the downstream side of the nacelle 4, a tail unit 5 with vertical and lateral control surfaces is provided, which is attached to the nacelle 4 via a boom 6 in the manner of a wind vane.

The nacelle 4 forms a single assembly with the components accommodated in it or attached to it, i.e. the rotor 2, the generator 3 and the tail unit 5. The nacelle 4 is attached to a suspension 7 designed as a framework.

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, as will be explained later, which in turn is attached to the buoyancy body 8, which in the illustrated embodiment is designed as a balloon. This can be designed as a multi-chamber helium balloon and carries the components suspended from it.

As shown in Fig. 1, the suspension 7 is anchored to the ground via three holding cables 18. The holding cables are in turn wound up by cable winches (not shown here) that are arranged on the ground. The length of the holding cables can be specifically changed via the cable winches, which are motor-driven.

A power line leads from the generator 3 to a transformer station that is located on the ground. The power line can be led along the holding cable to the ground. In a further development of the invention, the holding cable can also simultaneously form the power cable.

As shown in Fig. 2, a guying system 9 is provided for the rotor blades of the rotor 2. This comprises several guying cables 10, each of which is attached at one end to a central holding mandrel 11, which extends coaxially to the axis of rotation of the rotor 2 towards the front, i.e. towards the inflow side of the rotor 2. The other end of the guying cables 10 is attached to one of the rotor blades of the rotor 2.

The gas balloon intended as a buoyancy body 8 is designed free of internal framework structures. It has a gas-tight shell 12 which consists of a gas-tight coated fabric, in particular a suitable synthetic fiber fabric. A UV radiation-repellent protective cover 13 is pulled over the gas-tight shell 12, which protects the gas-tight shell 12 underneath from premature aging and destruction.

The suspension of the rotor assembly and the generator is explained in more detail below.

The nacelle 4 with the components arranged therein or attached thereto is mounted on the suspension 7 so as to be pivotable about a horizontal nacelle axis 14 (see Fig. 3, 4). The nacelle axis 14 is approximately perpendicular to the axis of rotation of the rotor 2. A nacelle rotation mechanism 15 is assigned to the nacelle axis 14, which has an electric servomotor (not shown in detail) as a pivot drive, with the aid of which the nacelle 4 can be tilted or rotated about the nacelle axis 14.

The tail unit 5 is pivotably mounted relative to the nacelle 4. The boom 6 supporting the tail unit 5 is attached to the downstream side of the nacelle 4 with a tilting joint 16. The tail unit pivot axis 17 defined by this extends parallel to the nacelle axis 14 and, like it, horizontally.

To compensate for any oblique position of the holding cable 18, the gondola 4 and thus the rotor arrangement 1 can first be brought into a favorable alignment with the oncoming wind direction around the gondola axis 14. This can be done by the rotating mechanism 15. If necessary, the rotating mechanism 15 can be switched off and the alignment of the rotor arrangement around the gondola axis 14 can be brought about by the tail unit 5. In the working position shown in Fig. 3, the tail unit 5 is folded out, i.e. its boom 6 extends essentially coaxially with the axis of rotation of the rotor 2. In order to move the rotor arrangement 1 out of the wind into a securing position, the tail unit 5 is first folded away by an approximately right angle. To do this, the boom 6 with the tail unit 5 attached to it is pivoted about the tilting joint 16. The tilting mechanism provided for this purpose preferably has an electric actuator (not shown in detail) which is controlled by the control device (also not shown) arranged on the ground depending on the wind strength.

Furthermore, the nacelle rotation mechanism 15 is activated for storm protection, which can take place simultaneously with or after the pivoting of the tail unit 5. The nacelle rotation mechanism 15 pivots the nacelle 4 into the position shown in Fig. 4.

showed an approximately vertical position in which the rotor blades of the rotor 2 lie approximately in a horizontal plane. The nacelle rotation mechanism 15 is also controlled by the control device (not shown). This evaluates the wind strengths detected by means of wind sensors (also not shown) and sends the corresponding control signals to the corresponding servomotors.

In order to completely protect the wind turbine from a storm, the buoyancy body 8 with the attached rotor assembly 1, the generator 3 and the tail assembly 5 is pulled to the ground by means of the cable winches 19 onto which the holding cable 18 is wound. The cable winches 19 are controlled by the control device, which evaluates the wind strengths recorded at different heights. In addition to storm protection, the height control device can be used to position the rotor assembly at the optimal height. To do this, the control device evaluates the measurement signals from the wind sensors positioned at different heights.

Fig. 6 shows the detailed design of the rotor 2 and its rotor blades. The rotor blade shown there consists of several rotor blade pieces that can be plugged together in a modular manner, so that the length of the rotor blades can be changed by exchanging or adding to the rotor blade pieces 22. A suitable connection, in particular a plug connection 23, is provided between the rotor blade pieces 22, which can absorb the loads that occur. As Fig. 6 shows, additional guy ropes 10 are expediently provided when the rotor blades are extended, so that each rotor blade is guyed at several points relative to the central holding mandrel 11. The rotor blade pieces shown have the lightweight construction described at the beginning in order to achieve a low weight of the rotor 2.

The wind turbine described above is characterized by the fact that it can be manufactured at a reasonable cost. In addition, the most important restrictions for the further expansion of wind energy are eliminated.

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The wind turbine described can basically be set up anywhere. Due to the working height of the rotor arrangement of up to 300 meters, no special wind priority areas are required for economical operation.

Thanks to the height regulation and the variable rotors, a significant amount of electricity can be produced even in times of light wind. This means that energy production is more stable - apart from on stormy days. This means that a larger proportion of electricity production can be based on wind power.

The ecological arguments against wind turbines, such as the disruption of the landscape, noise emissions, vibrations or the so-called disco light effects, are largely eliminated.

Particularly in areas that do not yet have a comprehensive power grid, the possibility of installing wind turbines in almost any decentralized manner means that the traditional power distribution via overhead power lines can be partially dispensed with. This would enable the necessary further increase in energy production from renewable sources to be achieved at economic cost.

Claims (15)

1. Wind power plant with a buoyancy body ( 8 ), a cable ( 18 ) for anchoring the buoyancy body to the earth's surface, a rotor arrangement ( 1 ) and a generator ( 3 ) coupled thereto, which are fastened to the buoyancy body by means of a suspension ( 7 ) and can be pivoted relative to the latter, characterized by a pivot drive ( 15 , 17 ) with which the rotor arrangement ( 1 ) can be pivoted from a working position out of the wind into a storm-safe position, a wind detection device for detecting the wind strength, and a pivot control device for controlling the pivot drive depending on the detected wind strength. 2. Wind power plant according to the preceding claim, wherein a tail unit ( 5 ) in the manner of a wind vane is provided for adjusting the rotor arrangement ( 1 ) and can be tilted away relative to the rotor arrangement ( 1 ) by means of a tilting mechanism ( 17 ), wherein the tilting mechanism has a servomotor which can be controlled by the swivel control device depending on the wind strength. 3. Wind turbine according to one of the preceding claims, wherein the pivot drive ( 15 ) has a servo motor which is connected between the rotor arrangement ( 1 ) and its suspension ( 7 ) and is provided for pivoting the rotor arrangement relative to the suspension about a particularly horizontal axis ( 14 ). 4. Wind turbine according to one of the preceding claims, wherein the rotor arrangement ( 1 ), the generator ( 3 ) and the tail unit ( 5 ) form a unitary assembly which as a whole is pivotable relative to the suspension ( 7 ). 5. Wind turbine according to one of the preceding claims, wherein cable winches ( 19 ) are provided for individually adjusting the length of the cables of the cabling ( 18 ), by means of which the wind turbine can be positioned exactly at one point and variably adjusted in height. 6. Wind turbine according to one of the preceding claims, wherein the height adjustment is carried out automatically by a computer calculating the ideal operating height on the basis of data supplied by wind sensors installed at different heights and giving a corresponding control impulse to the cable winches. 7. Wind power plant according to the preceding claim, wherein the height control device is designed such that the buoyancy body ( 8 ) with the rotor arrangement ( 1 ) attached thereto is pulled to the earth's surface when a predetermined wind speed is exceeded. 8. Wind power plant according to one of the preceding claims, wherein a depression ( 20 ), in particular surrounded by an earth wall ( 21 ), for receiving the buoyancy body ( 8 ) is provided at the anchoring of the stranding ( 18 ) in the earth's surface. 9. Wind turbine according to one of the preceding claims, wherein the rotor arrangement ( 1 ) has a rotor ( 2 ) whose rotor blades have an internal frame and a covering resting thereon. 10. Wind power plant according to one of the preceding claims, wherein the rotor arrangement ( 1 ) has a rotor whose rotor blades have a rod system and a sail stretched by the rod system, wherein preferably a reefing device is provided for reducing and enlarging the sail area, in particular with a drive that can be controlled automatically by a controller. 11. Wind turbine according to one of the preceding claims, wherein the rotor arrangement ( 1 ) has a guy ( 9 ) for the rotor blades, in particular a central holding mandrel ( 11 ) extending along the axis of rotation and guy cables ( 10 ) for the rotor blades attached thereto. 12. Wind turbine according to one of the preceding claims, wherein the rotor arrangement ( 1 ) has a rotor with a variable rotor blade area, in particular with variable-length rotor blades. 13. Wind turbine according to one of the preceding claims, wherein the rotor arrangement ( 1 ) has a rotor ( 2 ) whose rotor blades can be assembled in a modular manner from various rotor blade pieces ( 22 ). 14. Wind turbine according to one of the preceding claims, wherein the buoyancy body ( 8 ) has a gas-tight casing ( 12 ) and a UV protective casing ( 13 ) located over the latter. 15. Wind turbine according to one of the preceding claims, wherein one of the holding cables ( 18 ) is simultaneously designed as a current-carrying cable.