DE4428731A1 - Variable length rotor blade for wind power systems - Google Patents

Abstract

The blade is intended esp. for use on systems at inland locations, and has a longitudinal supporting element with a profile which tapers towards the blade tip, and onto which ribs and leading and trailing edge coverings are fixed. In at least part of its extent, the hollow supporting profile (5) has a fixed component (20), and a telescoping component (21) which can move in a guideway. The telescoping region may start at the blade root (2) and extend up to 5 m, and the hollow profile may be of circular cross-section within this region. The region may also occur at between 50 and 80 percent of the blade length from the root.

Description

The invention relates to a variable-length rotor blade for wind turbines, especially for wind turbines at inland locations, which from one load-bearing hollow profile, frames and cladding panels attached to it Wing nose and wing tail exist as it is for the rational use of the regenerative energy source wind power is needed.

State-of-the-art wind turbines are characterized by rotors, the available wind at the respective location using high-performance Extract mechanical energy from the rotor blades and apply them to the rotor hub Main shaft or transmitted directly to a generator.

In the 50 to 1,000 kW power class, rotor blade designs dominate today, their characteristics

• - high-quality composite materials for the load-bearing components,
• - The use of organic matrix materials for securing the Corrosion resistance, small dimensions and high surface quality and
• - the shifting of the load-bearing cross-sections into the outer contour of the Rotor blade profiles are.

While previous main areas of application for the use of Wind turbines in windy coastal regions with predominantly If there were more uniform climatic conditions, they are now also gaining Inland locations of wind power plants in importance.

Common reasons for this development are:

• - the growing environmental awareness of energy system operators and Energy consumers;
• - the growing costs of energy supply based on fossil fuels Energy source;
• - the proximity of consumers to wind turbines at inland locations, associated with lower energy transmission losses;  
• - the generally cheaper energetic and traffic engineering Degrees of development of inland locations;
• - The largely unproblematic subsoil conditions on orographically advantageous locations inland and
• - the increasingly improved price-performance ratio of modern Plant designs.

Inland locations for wind turbines are often demanding connected, which is not satisfactory with previously available designs are fulfilled.

Such requirements are known to exist in particular in

• - strongly changing climatic conditions at an inland location, from low temperatures around -30 ° C to temperatures that favor roughness between -5 ° C and -1 ° C up to 50 ° C high ambient temperatures;
• - recognized higher risk of lightning strikes;
• - greater frequency of gusts and gusts;
• - frequent changes of wind direction;
• - possible proximity to areas at risk of noise pollution.

Wind turbines that are particularly suitable for inland locations are therefore designed so

• - That they in the so-called low wind range between 2m / s to 8 m / s with variable rotor speeds and work with optimal performance can;
• - that the weather-related plant shutdowns to values of less than 15% the calendar time can be reduced;
• - That the mechanical equipment if necessary with energy-consuming heating and / or cooling systems are equipped;
• - That measures to reduce the outgoing from the rotor blades Noise emissions, for example by limiting the rotor speed to values as small as possible, by ensuring the highest possible quality of the Wind breaking edges on the rotor blades and by ensuring required minimum clearances between the rotor blade and the mast will.

Starting at low wind speeds of less than 3 m / s Compared to the so-called strong wind wind turbines, such as rotors are usually used in windy coastal locations comparable nominal power of the installed machine sets via rotors with have a larger diameter.  

However, oversizing the rotor dimensions has the disadvantage connected, after reaching the nominal output with increasing Wind speeds do not have the required security Overloading of the machine set or the regular ones To be able to avoid braking.

Is this deficiency with stall-regulated rotor blades changed? Angle of attack of the rotor blade when attaching the rotor blades to the If the rotor hub is encountered, this has to do with the starting behavior of the Rotors are bought.

There has therefore been no lack of attempts to find more suitable rotor blades for To develop wind turbines that meet the above requirements better should correspond.

So far, the solution to the problem is primarily in the so-called Pitch control based on the performance of the rotor Machine set matched rotor blades seen.

Introduced technical solutions exist in the form of synchronous Rotation of the rotor blades on the connecting flange to the rotor hub using hydraulically moved linkage or via electric motor driven Ball slewing rings.

In these known solutions, the effective rotor circle area remains for the Energy transfer to the rotor shaft unchanged.

With the help of the twisting of the wing profile transversely to the rotor circle plane at strong winds achieve the aerodynamic braking of the rotor, as well when the system is at a standstill in the same position of the sash profile Rotor start is effected.

Nevertheless, it can be seen that wind turbines with pitch-controlled Rotor blades due to the lack of an oversized rotor circular area only start up at wind speeds of significantly more than 3.5 m / s and thus at typical inland locations over relatively large parts of the Calendar time are unable to supply energy.

A technical solution to the problem mentioned is not yet available.  

The object of the invention is therefore to eliminate the above Deficiencies in the prior art and in creating a solution for one variable-length rotor blade that can be produced with little technical effort, if necessary for painting a temporarily enlarged rotor circle area is suitable and safe in its performance with permissible strong winds is limited.

The object is achieved by the features of main claim 1 and solved their advantageous embodiments.

The proposed variable-length rotor blade, which is particularly advantageous for Wind turbines at inland locations should be suitable consists of one extending over the entire length of the rotor blade and towards the blade tip tapered load-bearing hollow profile, which is at least in a partial area Telescope with a rigid telescopic part and a movable telescopic part is executed.

The movable telescopic part is arranged in guideways. The twisting of the movable telescopic part when moving effecting guideways are either with the rigid or with the movable telescopic part firmly connected.

In individual sections, the guideways are designed so that they different degrees of twisting of the movable part of the rotor blade effect.

The use of a rotor for wind turbines with the invention variable-length rotor blades, provided that they are synchronized, now enables start-up behavior and energy generation to improve low wind speeds significantly, because for this case with With the help of the longer rotor blades, if necessary, not only a considerably larger one Rotor circle area is usable, but because the pitch-controlled moving parts the rotor blade in this case represent an unmistakably stronger starting aid. After starting the rotor by overcoming the inertia of the complete machine set including the rotor is moved of the movable part of the rotor blade that of the resulting Optimal rotor position corresponding to the wind speed on the rotor blade selected and, if necessary, used a somewhat smaller rotor circle area. At higher wind speeds than that for the generation of the nominal power are required by further reducing the area of the rotor circle necessary adjustments between the range of services of the rotor and with it coupled machine set made. This may allow because of the initially non-existent risk of overloading, also significantly stronger To be able to use the winch as usual to generate energy.  

Finally, a system overload with reduced requirements the stability of the mast construction with the invention Rotor blades equipped wind turbine prevented by the shortest Position of the variable-length rotor blade also the aerodynamic Braking position by aligning the profile of the rotor blade across Rotor circle level reached.

Another advantageous embodiment of the invention is that the as Telescopic section of the load-bearing hollow profile of the variable length Rotor blade starting at the blade root over a length of up to 5 m is arranged, the hollow profile advantageously in this area circular tube cross section.

In this case, the length of the rotor blade is changed, for example by extending the load-bearing hollow profile between the leaf root on Hub connection and the profiled part of the rotor blade.

For example, if you start from a rotor blade that has a shortest length of The area has 18 m and between the hub and the beginning of the rotor blade profile of the telescope is provided with a length of 5 m, then the rotor in in this case with a hub diameter of 2 m one from the rotor blade profile covered circular area of initially about 1,020 m².

Now the intended extension of the load-bearing hollow profile between Hub connection and beginning of the rotor blade profile made of about 4 m, see above the circular area covered by the rotor blade profile increases to approximately 1,350 m², thus temporarily increasing the range of services offered by the rotor from over 30% can be expected.

A further advantageous embodiment of the solution according to the invention is shown in FIG Arrangement of the telescopic part of the supporting hollow profile in about Range between 50 and 80% of the rotor blade length, from the blade root calculated before.

In this embodiment of the variable-length rotor blade according to the invention there is a temporary interruption of the closed over the length of the rotor blade Rotor blade profile accepted because the extended condition of the Rotor blade only as a starting aid or for the extreme Low wind operation is used. On the other hand, the structural engineering is reduced Requirements for this variant of the equipment of the length variable Noticeable rotor blade.

An advantageous embodiment of the variable-length rotor blade provides the moving part of the telescope in the contact area with the rigid part of the To equip telescopes with at least three guideways.  

In this case, the rigid part of the telescope is included in the guideways engaging sliding and / or rolling elements equipped.

In special cases, it may prove useful to use a larger number than to install three guideways and thus the guidance of the movable Part of the telescope in the rigid telescopic part and at the same time the required Rotation of the movable telescopic part in relation to the rigid telescopic part ensure safely.

In a further embodiment variant, it is also possible for the rigid part of the Telescopes in the contact area with the movable telescopic part with at least to equip three guideways, in which case the Sliding and / or rolling elements engaging guideways on the movable part of the telescope.

The displacement of the movable telescopic part compared to the rigid Telescopic part is carried out using technical means known per se, such as hydraulic ones Working cylinders, spindle drives, rack drives and / or Cable mechanisms, which are expediently arranged in the load-bearing hollow profile are.

In addition, between the movable telescopic part and the rigid Telescopic part sealing elements arranged, with the help of the penetration of Dirt and weather moisture in the interior of the hollow profile or between movable telescopic part and rigid telescopic part is prevented.

An advantageous embodiment of the invention is that the entire with Change in length of the rotor blade which can be effected with the aid of the telescope, referred to as the length A, is divided into several sections.

A distinction is made in length B as the resulting area between the inner end position and the inner working position of the length variable Rotor blade. The inner positions result for the extreme positions of the rotor blade when the telescope is merged.

A further distinction is made in length C, which is the area between the inner working position and the outer working position of the rotor blade results. This area is preferred during normal operation of the wind power plant, whereby the adjustments of the range of services of the rotor to the possible Power consumption of the machine set primarily by varying the Position of the rotor blade in this area results.  

Finally, there is also a length D as the area between the outer Working position and the outer end position defined.

These positions result from the extreme position of the rotor blade in the Connection with the telescopic extension of the rotor blade.

The individual length ranges are advantageously in the following proportions intended:

0.05 A <B <0.15 A,
0.05 A <D <0.15 A,
0.70 A <C <0.90 A.

In the different areas, the guideways are arranged so that characteristic twists of the movable telescopic part when surrender.

They are advantageously in the length range C between the inner and the outer working position between 0.6 and 1.0 degrees per meter Displacement, this twisting with the twisting of the Rotor blade profile is the same.

This ensures that the changes in the position of the rotor blade in normal working area of the wind turbine with the retention of each optimal position of the rotor blade profile to the one attacking the rotor blade Wind vector goes hand in hand.

In the length range B between the inner working position and the inner one The end position is advantageously between 65 and 80 Degree against the direction of the rotor blade twist, so that after reaching the inner end position also extensive alignment of the rotor blade profile across the rotor circle level and thus the aerodynamic braking position smallest possible target for the then for the energy conversion strong wind is reached.

In the length range D between the outer working position and the outer one End position is between 10 and 30 degrees against the Rotor blade twisting, so that after reaching the outer end position favorable position of the rotor blade profile can be recorded as a starting aid.

The advantages of the invention consist in particular in the now available technical solution, an additional pitch-controlled rotor in a special way the different wind conditions with the Aim to maximize energy yields at a specific location to be able to adapt.  

The invention will be explained in more detail below using an exemplary embodiment will.

Show in the attached drawing

Figure 1 is a schematic view of a variable-length rotor blade according to the invention with arrangement of the telescopic area on the blade root.

Fig. 2 is a schematic view of a wavelength-variable rotor blade assembly of the invention with the telescoping portion in the outer half of the rotor blade;

Fig. 3 is the schematic cross section of a telescopic connection with which is arranged on the rigid telescopic part arranged guide tracks and on the movable telescopic part slide members;

Fig. 4 is the schematic cross section of a telescopic connection with which is arranged at the movable telescopic part arranged guide tracks and the rigid telescopic part rolling elements;

Fig. 5 shows the schematic representation of the rotor blade end profile when reaching the individual length range limits when moving the movable telescopic part relative to the rigid telescopic part.

The rotor of a wind turbine with a nominal output of 500 kW has a diameter of 42 m. The hub of the rotor is equipped with three variable-length rotor blades 1 .

The variable-length rotor blade 1 with a total length of 20 m consists of a load-bearing hollow profile 5 , which is initially designed as a cylindrical tube from the blade root 2 to the attachment of the rotor blade profile and then tapers continuously until the end of the rotor blade 1 opposite the hub. The cladding of the load-bearing hollow profile 5 begins at a distance of 5,000 mm from the leaf root 2 . In this cladding-free section of the variable-length rotor blade 1 , the supporting hollow profile 5 has a circular profile with an outer diameter of 800 mm. In the area of the blade root, this profile is connected to an annular flange for the hub connection 16 .

The load-bearing hollow profile 5 is designed as a rigid telescopic part 20 in the area from the blade root 2 to the attachment of the rotor blade profile over a length of 5,000 mm.

Within this rigid telescopic part 20 four guideways 7 are evenly attached to the tube wall. The movable telescopic part 21 is non-positively connected to a displacement point in the plane of the leaf root 2 by means of a hydraulic working cylinder 10 .

If required, the hydraulic working cylinder can easily be replaced by a spindle drive 11 , a rack and pinion drive 12 or by a cable pull mechanism 13 .

With the help of the selected drive component, the movable part of the telescope 21 can be pushed out about 4,000 mm from the rigid part of the telescope 20 .

The movable telescopic part 21 receives lateral guidance through sliding elements 8 which are laterally fastened in recesses and which engage in the guide tracks 7 in a form-fitting manner. By means of the sliding elements 8 , the longitudinal guidance of the movable telescopic part 21 and, at the same time, the defined rotation of the movable telescopic part 21 relative to the rigid telescopic part 20 are carried out .

The sliding elements 8 are fastened in the region on the movable telescopic part 21 which remains in the rigid telescopic part 20 even when the outer telescopic part has reached its outer end position.

The guideways 7 are designed so that in the inner end position, the position of the wing tip 16 is characterized by an axial position of the wing tip, which forms an angle of 75 degrees with the rotor circle plane.

After a longitudinal displacement of 400 mm, the movable telescopic part 21 reaches the inner working position. In this position the wing tip has a layer 17 which is characterized by an axial position of the wing tip which forms an angle of approximately 3 degrees with the plane of the rotor circle. The rotation of the movable telescopic part 21 is therefore 72 degrees on this section. The movable telescopic part 21 can be moved by 3,400 mm between the inner and the outer working position. In this case, the movable telescopic part 21 is continuously rotated by approximately 3 degrees by means of the guide tracks 7 . After reaching the outer working position 18, the position of the wing tip is characterized by an axial position of the wing tip, which is aligned parallel to the rotor circle plane.

Between the outer working position and the outer end position movable telescopic part only moved by 200 mm.

The movable telescopic part 21 is rotated by 25 degrees, so that the position of the wing tip is characterized in that it again forms an angle of 25 degrees with the plane of the rotor circle.

The latter position is held by the management system of Wind turbine only for the purpose of starting the rotor rotation approached if, due to insufficient wind speed, the Rotor is at a standstill.

After the rotor has been put into operation, the outer one immediately Working position taken.  

Depending on the actual wind speeds and the range of services provided by the rotor, the working range of the telescope between the outer and inner working positions is used for the purpose of adaptation. If the wind speed rises to higher values and powers are already recorded above the rated power of the wind turbine, the operational management system controls a position of the movable telescopic part 21 between the inner working position and the inner end position.

With this measure, despite higher wind speeds Overloading of the mechanical engineering system avoided because it is already noteworthy performance shares by means of the aerodynamic Braking effects are compensated.

If it is necessary to shut down, the inner end position of the movable telescopic part.

The movable telescopic part 21 sensors 19 are arranged for registering the position reached in each case of the movable telescopic part 21st

As a result of the equipment according to the invention, the executed rotor blade 1 has an advantageous starting behavior, an easily controllable wing position for the purpose of optimized use of wind energy and for the purpose of preventing impermissible rotor speeds at higher wind speeds. The rotor with three variable-length rotor blades according to the invention starts up at wind speeds of less than 2 m / s and delivers the nominal power of 500 kW at less than 12 m / s.

Claims (11)

1. Variable-length rotor blade for wind turbines, especially for wind turbines at inland locations, consisting of a longitudinal support element as a tapering towards the end of the rotor blade hollow profile with attached frames, wing nose and wing tail panels, characterized in that the supporting hollow profile ( 5 ) at least in one Partial area is designed as a telescope with a rigid telescopic part ( 20 ) and a telescopic part ( 21 ) movable in guideways ( 7 ), the rigid part of the telescope ( 20 ) having the twisting of the movable telescopic part ( 21 ) causing guideways ( 7 ) during telescoping and if necessary, the guideways ( 7 ) are formed in individual sections with different twists. 2. Variable-length rotor blade according to claim 1, characterized in that the portion formed as a telescope of the supporting hollow profile ( 5 ) is arranged approximately at the blade root ( 2 ) starting over a length of up to 5 m and the hollow profile ( 5 ) in this Area has a circular tube cross section. 3. Variable-length rotor blade according to claim 1, characterized in that the supporting hollow profile ( 5 ) in the length range between 50 and 80% of the rotor blade length, calculated from the blade root ( 2 ), is equipped with a movable telescopic part ( 21 ). 4. Variable-length rotor blade according to claim 1 to 3, characterized in that the movable part of the telescope ( 21 ) in the contact area with the rigid part of the telescope ( 20 ) with at least three guideways ( 7 ) and the rigid part of the telescope ( 20 ) are equipped with sliding and / or rolling elements ( 8 , 9 ) engaging in the guideways ( 7 ). 5. Variable-length rotor blade according to claims 1 to 3, characterized in that the rigid part of the telescope ( 20 ) in the contact area with the movable part of the telescope ( 21 ) with at least three guideways ( 7 ) and the movable part of the telescope ( 21 ) are equipped with sliding and / or rolling elements ( 8 , 9 ) engaging in the guideways ( 7 ). 6. Variable-length rotor blade according to claims 1 to 5, characterized in that the supporting hollow profile ( 5 ) in the region designed as a telescope causes the displacement of the movable telescopic part ( 21 ) mechanisms such as hydraulic working cylinder ( 10 ), spindle drive ( 11 ), Rack and pinion drive ( 12 ) and / or cable mechanism ( 13 ). 7. Variable-length rotor blade according to claims 1 to 6, characterized in that sealing elements ( 14 ) preventing the penetration of dirt and weather moisture are arranged between the movable and rigid part of the telescope ( 20 , 21 ). 8. Variable-length rotor blade according to claims 1 to 7, characterized in that the entire length change A of the rotor blade ( 1 ) which can be effected with the aid of the telescope is divided into an area B between the inner end position and the inner working position, an area C between the inner Working position and the outer working position and a region D between the outer working position and the outer end position and that the length dimensions of these areas approximately
0.05 A <B <0.15 A,
0.05 A <D <0.15 A,
0.70 A <C <0.90 A
be. 9. Variable-length rotor blade according to claims 1 to 8, characterized in that the guideways ( 7 ) between the inner and the outer working position with a the rotor blade ( 1 ) by 0.6 to 1.0 degrees around the longitudinal axis of the rotor causing rotation Meters of displacement are arranged and that this rotation is the same as the rotor blade twist. 10. Variable-length rotor blade according to claims 1 to 9, characterized in that the guideways ( 7 ) are arranged between the inner working position and the inner end position with a rotation of the rotor blade ( 1 ) by 65 to 80 degrees around the longitudinal axis of the rotor and that this rotation of the rotor blade twist is in opposite directions. 11. Variable-length rotor blade according to claims 1 to 10, characterized in that the guide tracks ( 7 ) are arranged between the outer working position and the outer end position with a rotation of the rotor blade ( 1 ) by 10 to 30 degrees about the longitudinal axis of the rotor and that these Rotation of the rotor blade twist is in opposite directions.