WO2011048024A2

WO2011048024A2 - Method for controlling a wind energy system

Info

Publication number: WO2011048024A2
Application number: PCT/EP2010/065530
Authority: WO
Inventors: Christoph Lucks
Original assignee: Windcomp Gmbh
Priority date: 2009-10-21
Filing date: 2010-10-15
Publication date: 2011-04-28
Also published as: DE102009050235B3; WO2011048024A3

Abstract

According to the invention said aim is achieved by means of a method for controlling a wind energy system comprising a tower, a nacelle horizontally rotatably disposed on the tower, and a horizontal rotor rotatably disposed on the nacelle, wherein the distance to the rotor blades passing through is measured at at least two different measurement points by means of at least two non-contacting distance sensors disposed fixedly on the nacelle and symmetrically to the rotor axis, the measurement axes thereof running symmetrically to the rotor axis, and the measured distance signals or a difference between the signals is used as the guide parameter for the controlled or regulated adjustment of actuating parameters of the wind energy system.

Description

description

Method for controlling a wind turbine

Technical area

The invention relates to a method for controlling a wind turbine, a tower, a rotatably mounted on the tower horizontally arranged nacelle and a rotatable on the nacelle

arranged horizontal rotor.

State of the art

Wind turbines, especially those of modern design, are highly complex systems that need to be controlled by a variety of boundary conditions and parameters. Important guided variables, ie manipulated variables, are among others. the orientation of the machine house to the wind, so the setting of the azimuth angle of the machine house opposite the tower, as well as the so-called blade angle

pitch controlled equipment, i. the angular adjustment of the rotor blades about their longitudinal axis.

The correct and correct orientation of the machine house to the wind in a manner in which the flow of wind is carried out in an ideal manner exactly perpendicular to the rotor plane, is for the yield or efficiency of mechanical and thus ultimately electrical energy from the

Wind energy of high relevance. The setting of the blade angle is done especially at higher wind loads in the pitch angle controlled operation of the wind turbine on the one hand also to achieve the highest possible energy yield, on the other hand to protect the limited in their design parts and elements of the wind turbine from excessive loads and thus a calculated and economically required service life to grant the plant.

For the correct alignment of the machine house to the wind wind measuring systems are arranged on the wind turbines, usually arranged behind the rotor in lee anemometer. A known problem is that due to congestion on the tower and

Turbulence, caused by passing rotor blades, the wind direction can not be determined exactly with such anemometers can. Thus, the wind direction determined with such an anemometer fluctuates significantly in a time course, which is why always for controlling the orientation of the nacelle

Mean values must be taken as a basis. But even these mean values are clearly flawed, so that angle deviations of up to 10 °, sometimes even more, can be observed. Such large deviations in the angle between the rotor plane and the direction of inflow from the ideal size of 90 ° significantly reduce the effective surface area and thus noticeably minimize the energy yield.

To remedy this problem and to remedy this situation, various approaches have already been pursued. So it has been tried

Wind vane or the like Windrichtungsmesser in front of the rotor at the

Wind turbine to place here to more accurate and from

Wind shadow effects and turbulence less distorted

To obtain measurements. However, the deviations are also in the proposed measuring systems in this respect and

Impairment by the immediately before the rotor level

occurring back pressure significantly and lead to falsified

Results. Further proposals, which provide optical measurement systems which are effective at measuring sections clearly in front of the wind turbine, are still being tested. These systems are costly and could not prove a much higher accuracy to date.

In addition, there are currently efforts, especially with large

designed modern wind turbines to increase the energy yield by an individual pitch control of the rotor blades. Up to now, it has always been customary to set the pitch angle of all rotor blades to equalize the capacity of the wind turbine. This ignores the fact that the wind speed near the ground is lower due to the ground roughness compared to the wind speed at a greater distance to the ground. This means that a rotor blade passing over near the ground is exposed to a lower wind load than a rotor blade brushing in the upper region of the tower or even beyond it. This consideration further leads to the idea that the pitch angle Accordingly, the rotor blade is chosen flatter and thus a larger profile of the blade can be exposed to the wind when the rotor blade is moved close to the ground, as if this passes through the higher zones. Thus, the energy input on the rotor blade near the bottom can be increased again and thus the power output of the

Wind turbine to be optimized.

The theoretical considerations to that effect are now far

So far, however, no simple and reliable system has been specified, with which appropriate reference variables for the regulation of such an individual Pitchwinkelverstellung can be determined. While there are efforts in this regard, e.g. to absorb corresponding loads on the rotor blades by means of strain gauges and as characteristic or reference variables for the

Rotor blade adjustment to use, but the results to be achieved are not yet satisfactory.

Presentation of the invention

The invention is intended to a extent a method for controlling a

Wind turbine to be specified, which is particularly suitable for a more accurate alignment of the machine house to the wind, but is also suitable for the individual Pitchwinkelverstellung the rotor blades.

The inventor has come to the realization that a corresponding

Method can be easily designed if with at least two stationary to the nacelle and symmetrically to the rotor axis arranged non-contact distance sensors whose measuring paths are symmetrical to the rotor axis of rotation, the distances of the

Rotor blades determined along at least two different measuring points and the determined distance signals or their difference are used as a reference variable. The determination of the distance takes place with the aid of non-contact distance measurement, as can be done, for example, with optical sensors (in particular laser rangefinders), but also with ultrasound, radar or the like. The measuring points lie in a two-dimensionally reduced view approximated on an imaginary circle around the rotor axis are, if one the Wandering of the measuring points in the direction of the rotor axis of rotation due to the deflection ignores.

[001 1] By means of the determination of the spacing of the rotor blades in the manner indicated, different degrees of deflections of the rotor blades can be detected and determined. Depending on the selected measuring section and its position, the measured values can be selectively different information taken.

Thus, at two points lying on a horizontal line measuring points at different points of the idealized approximate circle as mentioned above about the rotor axis, a different deflection of

Rotor blades are determined, as is typical in a

Oblique flow due to a malposition of the machine house to the wind occurs. Thus, if the rotor blades on one side of the rotor with the distance sensor aiming at it are systematically measured to a closer distance than the rotor blades passing on the other side of the nacelle, then the nacelle is to be rotated in its azimuth angle in the direction of the rotor blades being measured closer. This rotor tracking is continued until the distances between the rotor blades on both sides, ie with both of the non-contact distance sensors, are the same within a tolerance. Particularly good results can be achieved if the horizontal line runs through the center of the rotor axis, or as close as possible to this. Moreover, the more accurate the measurements are the farther outward the distance sensors will be, that is, the greater the radius of the idealized circle as mentioned above. It is of course to ensure that none of the distance sensors aims to a point that lies beyond the blade tips of passing rotor blades. Typically, one will here choose the measurement point in a range which is about 70 to 90% of the rotor blade length to the blade tip.

If the method in the manner described for the alignment of the machine house to the wind, so applied to the adjustment or adjustment of the azimuth angle of the machine house, it is of particular advantage, when initially using the conventional means, such as an anemometer located in the lee of the rotor, the machine-housing alignment is roughly made and then a fine adjustment by means of the method according to the invention. The great advantage of this method lies in the described application in that a wind direction no longer needs to be measured, but the correct orientation in the wind is detected indirectly via a uniform load of the rotor blades in the rotor plane. This is independent of any congestion effects or turbulences in the rotor blades and can be detected very reliably and accurately, thus allowing a very angular alignment of the machine house in the wind and thus a good optimization of the power output.

Similarly, the method according to the invention can be used in an alternative or additional application to the

Angle of attack (also called pitch angle) to change or optimize at least one rotor blade. For this, e.g. along a in

Substantial vertical line to two different points of the above-mentioned, idealized and simplified assumed circle around the rotor axis aligned distance sensors are used, which then detect corresponding distances and thus deflections of the rotor blades. Especially with stronger winches, it will be noted for the same pitch angle setting for all rotor blades that the

Rotor blades have a greater distance to the respective sensor in the lower passage near the bottom than in their upper,

away from the ground passage. This can be used, in particular to flatten the blade angle in the region of the lower passage and thus in this area a higher energy yield and a better

To obtain a performance entry. It is particularly conceivable to specify a minimum operating distance, starting from a maximum load of the rotor blade, and to use this as a reference variable for adjusting the pitch angle, depending on the blade position. This individual adjustment of the pitch angle or

Anstellwinkels the rotor blade allows, especially near the ground Range a higher yield of naturally lower there

Flow velocity of the wind and thus a higher

Energy input to achieve and thus the overall performance of

Wind turbine to increase. Again, there is an optimal measurement result in two sensors, when the substantially vertical line passes through the center of the rotor axis or close to it.

For a refinement of the measurement, in particular in the application to the sheet-by-piece individual adjustment of the pitch angle can also be provided more than one distance sensor and evaluated according to a variety of measured distance data. It is also possible in principle to influence the two variables mentioned at the same time with a method according to the invention for the control of the wind energy plant, for example by pairing the distance sensors along a horizontal and further distance sensors along a vertical line at different points on the circle mentioned and simplifying assumed in pairs Measure distance. But it is equally possible to simplify distance sensors in different distribution at different angles along the

assumed circle around the rotor axis to make measurements, e.g. determine three such distance sensors and then computationally corresponding horizontal and vertical distance differences with known mathematical methods of trigonometry.

In order to eliminate possible Messausreißer or error due to gusty wind or the like., The distance signals can be measured over a predetermined period and like ittelt be and find only the average distance signals as a guide for the control of the wind turbine use.

Further, it is advantageous in the method according to the invention, when the distance signals are indexed rotor blade by way and processed. Thus, each individual rotor blades associated with appropriate distance signals and it can also be made individual evaluations for each of the rotor blades. This can also be abnormal Deflection of individual rotor blades are detected, which are due for example to a material fatigue. This is of particular advantage, since in this way appropriate material fatigue can be detected early and countermeasures can be taken (eg repair or replacement of the blade or stopping of the wind energy plant) in order to avoid fatal accidents such as a collision of the blade with the tower.

Brief description of the drawings

Further advantages and features of the invention will become apparent from the

following description of an embodiment with reference to the accompanying figures. Showing:

Fig. 1 in a schematic representation a plan view of a

Wind turbine whose rotor has been flowed obliquely to illustrate a possible use variant of the method according to the invention; and

Fig. 2 shows schematically a side view of a wind turbine and a wind speed profile over ground to illustrate a further variant of the method.

Way (s) for carrying out the invention

The process of the invention in two possible basic applications will be explained and described with reference to the highly schematic representations.

In Fig. 1, a wind turbine 1 is shown in a schematic plan view from above. On the tower, which can not be seen in this view, a machine house 2, also referred to as a nacelle, is placed opposite the latter in the azimuth angle, on which rotatable a rotor 3 is mounted. The rotor 3 is composed of a hub 4 and the rotor blades 5 arranged thereon.

On the machine house 2 here only schematically indicated two contactless distance sensors 6 are arranged, which make along the plane lying in the drawing plane and extending measuring sections 7 and 8 in the direction of the outer ends of the rotor blades distance measurements. The measuring sections 7, 8 are at an identical angle α to the longitudinal center axis of the machine house, which is equal to the rotor axis A, inclined. Accordingly, the distance sensors aim symmetrically at the roaming rotor blades. At the same

Deflection of the rotor blades result in the same extent

Distance values, at least within a predefined tolerance.

In Fig. 1 it is indicated that the wind W, the rotor 3 of the

Wind turbine 1 flows in a deviating from 90 ° to the rotor plane oblique direction. This oblique flow causes the rotor blade 5, shown on the right in the figure, to deflect more strongly than the rotor blade 5 shown on the left in the figure, so that a

Distance difference results. The distance along the measuring path 8 is shorter than the distance to the rotor blade 5 along the measuring path 7. This difference is evaluated by the method according to the invention in a controller and for tracking the azimuth angle of the

Used this machine house, which is rotated in the direction of the measuring section of the shorter distance and thus driven in the correct orientation to the wind.

In Fig. 2, a second application of the method according to the invention is shown and explained in a schematic side view of a wind turbine 1. The wind turbine 1 in turn consists of a tower 9, with a rotatably attached to the upper end of the machine house 2 and a rotatably mounted on the machine housing rotor 3, consisting of hub 4 and rotor blades 5. On the machine house 2 again non-contact distance sensors 6 are arranged this time track within a vertical plane measuring sections 10 and 1 1 track. The measuring sections 10 and 1 1 are again with the same

Angle to the rotor axis A arranged, here the angle ß.

It is also shown how schematically results in a wind speed profile WP, with lower in the vicinity of the bottom B.

Wind speeds (represented by shorter arrows) and at higher altitudes greater wind speeds (represented by longer arrows).

Due to this different distribution of wind speeds results that at the same pitch angle setting, ie at the same set angles of attack for all rotor blades 5, in the upper region of the wind energy installation 1, ie away from the ground, passing rotor blades 5 experience a higher deflection than ground-level rotor blades 5. These differences in the deflection can be detected by the method according to the invention and / or readjustment of the angle of attack of the upper and / or or lower rotor blades 5 are used. This is done, in particular, with the aim of achieving a higher energy or power yield by adjusting the rotor blades 5 passing through in the lower region of the wind turbine with a flatter angle of attack and thus a larger profile in cross section, so that they have a higher degree of wind energy record and to drive the

Generators can be transferred to the system.

From the foregoing description has become clear once again, with which comparatively simple means, the inventive method can be implemented to the power output of

Optimize wind turbines.

[0029] List of Reference Numerals

[0030] 1 wind energy plant

2 engine house

3 rotor

4 hub

5 rotor blade

6 distance sensor

7 measuring section

8 measuring section

9 tower

10 measuring section

[0040] 1 1 measuring section

A rotor axis of rotation

B floor

W wind

WP wind speed profile

Α angle [0046] β angle

Claims

claims

1. A method for controlling a wind turbine, which has a tower, a tower rotatably mounted on the tower engine house and rotatably mounted on the machine housing horizontal rotor, wherein by means of at least two stationary to the nacelle and symmetrical to the rotor axis arranged non-contact distance sensors whose measuring distances the rotor axis of rotation are symmetrical, measured at at least two different measuring points of the distance to the sweeping rotor blades and the measured distance signals or a difference of the signals are used as a reference variable for the controlled or controlled adjustment of manipulated variables of the wind turbine.

2. The method according to claim 1, characterized in that two measuring points lie on a horizontal line and that the measured distance values to the rotor blades or their difference as a reference variable for adjusting the azimuth angle of the machine house are used relative to the tower.

3. The method according to claim 2, characterized in that the

Machine housing is traced in the direction in which the shorter distance to the rotor blade is measured, until the measured distances at the two measuring points within a predetermined

Tolerance threshold are equal or the difference between the measured distances is below a predetermined tolerance threshold.

4. The method according to any one of the preceding claims, characterized

characterized in that two measuring points lie on a vertical line and that the measured distance values to the rotor blades or their

Difference can be used as a reference variable for adjusting the angle of attack of at least one rotor blade.

5. The method according to any one of the preceding claims 2 to 4, characterized

in that the horizontal and / or vertical line on which two measuring points lie intersects the axis of rotation of the rotor.

6. The method according to any one of the preceding claims, characterized

characterized in that the distance signals are measured over a predetermined period of time and liked ittelt and that the averaged distance signals as Reference variables are used.

7. The method according to any one of the preceding claims, characterized

in that the distance signals are indexed by rotor blades and thus processed.

8. The method according to any one of the preceding claims, characterized

characterized in that as non-contact distance sensors optical

Distance sensors, in particular laser distance sensors are used.