CN105443315A - Method of operating wind power plant and controller thereof - Google Patents

Abstract

The invention relates to a method (300) for operating a wind energy installation (100), wherein the method (300) has a determined step (302), wherein in the determined step (302) a rotor blade (112) is used ) rotational speed information ( 206 ) and optionally acceleration information and processing rules to determine a local bending angle of at least one rotor blade ( 112 ) of a rotor ( 108 ) of a wind energy installation ( 100 ). The rotational speed information ( 206 ) here represents the rotor blade ( 112 ) of the rotational speed (ω). The processing rules represent a rotor-specific model of the rotor blade (112).

Description

Method and controller for operating a wind energy plant

technical field

The invention relates to a method for operating a wind energy installation, a corresponding controller and a corresponding computer program.

Background technique

In wind energy installations, the wind causes aerodynamic deformations of the rotor blades. In order to be able to intervene in a regulatory manner, it is necessary to measure the load on the blade, for example to detect the deformation in the blade.

Contents of the invention

Against this background, the method presented here provides a method for operating a wind power plant according to the independent claims, as well as a controller using the method and finally a corresponding computer program. Advantageous refinements emerge from the subclaims and the following description.

To reduce the load, the angle of attack of the rotor blades of the rotor of the wind energy installation can be adjusted using at least one measured value detected on the rotor blades. In particular, rotational speed information can be used here, which is detected by a rotational speed sensor which is placed on the rotor blade at a distance from the rotational axis of the rotor. The current rotational speed of the rotor blade can be directly attributed to the current load on the rotor blade.

A method for operating a wind power plant is described, wherein the method has the following steps:

A local bending angle of at least one rotor blade of a rotor of a wind energy installation is determined using rotational speed information of the rotor blades and a processing rule, wherein the rotational speed information indicates the position at a distance from the rotor axis of rotation. The rotational speed of the rotor blade detected on the rotor blade, and the processing rules represent a rotor-specific model of the rotor blade.

"Wind energy installations" can be understood as wind power installations or wind turbines. In this case, the rotor of the wind energy installation is rotated by wind energy and an electric generator is driven by the rotor. The aerodynamic forces on the rotor bend the rotor blades in this case. Bending moments, blade root bending moments, thus arise at the interface between the hub of the rotor and the rotor blades. The rotational speed information can be used multidimensionally or multiaxially. Processing rules may describe mechanical relationships at the rotor blades. Optionally, accelerations measured in the rotor blade can additionally be used to determine the local bending angle.

The local bending angle can also be determined using information on the angle of attack of the rotor blade. The angle of attack information can indicate the angle of attack of the rotor blade adjusted by the adjusting device. The angle of attack information may be an actual value of the angle of attack of the rotor blade. The angle of attack of the rotor blade has a decisive influence on the aerodynamics at the rotor blade.

The local bending angle can also be determined using acceleration information. The acceleration information can represent an acceleration of the rotor blade detected on the rotor blade at a different distance from the axis of rotation. The local bending angle can be guaranteed by the acceleration. There is a geometric relationship between rotational speed and acceleration. Acceleration information can be used multi-dimensionally or multi-axis. A further distance between the acceleration receiver and the axis of rotation can be equal to the distance of the rotational speed sensor, for example when a common sensor housing is formed. Likewise, acceleration receivers and rotational speed sensors can be arranged at different distances from the axis of rotation.

In the determining step, the blade deflection and/or the blade root bending moment can be determined using local bending angles and processing rules.

The method can have the step of providing a reference variable for an adjustment device of the rotor blade using a local blade bending angle, blade offset or blade root bending moment. The reference variable may be a target value for the angle of attack of the rotor blade.

The detected rotational speed can be a vector. Accordingly, the detected acceleration may be a vector. Such vectors can each have three entries (Eintrag).

The methods presented here also provide a controller which is designed to carry out, control or carry out the steps of one of the variants of the methods presented here in a corresponding device. The object underlying the invention can also be solved quickly and effectively by means of this embodiment variant of the invention, which is embodied in the manner of a controller.

A “controller” in the context of the present invention is to be understood as an electrical device which processes sensor signals and emits control signals and/or data signals as a function of the sensor signals. The controller can have an interface, which can be embodied in hardware and/or software. In the case of a hardware configuration, the interface can be, for example, a so-called system ASIC, which contains various functional components of the controller. However, it is also possible for the interface to be a separate, integrated switching circuit or to consist at least partially of separate components. When configured as software, the interface can be a software module that is present, for example, on a microcontroller next to other software modules.

Also advantageous is a computer program product or computer program with a program code which can be stored on a machine-readable carrier or storage medium, such as a semiconductor memory, hard disk memory or optical memory, and in particular when the program product or program is implemented on a A computer or device is used to implement, execute and/or control the steps of the method according to one of the above-described embodiments.

Description of drawings

The invention is explained in more detail below by way of example with reference to the drawings. In the attached picture:

FIG. 1 shows a diagram of a wind power plant with a controller for operating a wind power plant according to an embodiment of the invention;

Figure 2 shows a block diagram of a controller for operating a wind energy plant according to an embodiment of the present invention;

FIG. 3 shows a flow chart of a method for operating a wind energy installation according to an embodiment of the invention;

Figure 4 shows an illustration of a deformation at a wind energy installation according to an embodiment of the invention; and

FIG. 5 shows a further illustration of deformations on a wind energy installation according to an exemplary embodiment of the invention.

In the following drawings, the same or similar elements may be provided with the same or similar reference numerals. Furthermore, the illustration of the figures, the description of the figures and the claims contain several features in combination. It is clear to a person skilled in the art that these features can also be considered individually or that the features can be combined in other combinations not explicitly described here.

detailed description

FIG. 1 shows a diagram of a wind energy installation 100 with a controller 102 for operating a wind energy installation 100 according to an exemplary embodiment of the invention. Wind energy installation 100 has a tower 104 . A nacelle 106 is arranged horizontally and rotatably on the tower 104 . The main shaft of wind energy installation 100 is rotatably mounted approximately horizontally in nacelle 106 . The main axis represents the axis of rotation of rotor 108 of wind energy installation 100 . The main shaft connects the rotor 108 of the wind energy installation with the generator in the nacelle 106 . A transmission mechanism may be located between the rotor 108 and the generator. The main shaft is designed to transmit the rotation of the rotor 108 to the rotor or transmission of the generator. The rotor 108 has a rotor hub 110 and three rotor blades 112 mounted axially rotatably in the hub 110 . The angle of attack of the rotor blades 112 is individually adjustable in the hub 110 .

A sensor device 116 is attached to each of the rotor blades 112 at a distance 114 from the hub 110 or from the axis of rotation. Sensor device 116 here includes at least one multi-axis rotational speed sensor. Sensor device 116 is connected to controller 102 so that controller 102 can read at least one current rotational speed information from sensor device 116 .

In one exemplary embodiment, controller 102 is designed to provide a reference variable for an angle adjustment of rotor blade 112 using rotational speed information.

FIG. 2 shows a block diagram of a controller 102 for operating a wind energy installation according to an exemplary embodiment of the invention. The controller 102 basically corresponds to the controller in FIG. 1 . Controller 102 has means 200 for determining. The determining device 200 is designed to determine a local bending angle or blade root bending moment 204 of at least one rotor blade of a rotor of a wind energy installation using rotational speed information 206 of the rotor blade and processing rules. Rotational speed information 206 , as in FIG. 1 , indicates the rotational speed of the rotor blade detected on the rotor blade at a distance from the rotor axis of rotation. The processing rules represent a rotor-specific model of the rotor blade.

In one embodiment, the controller 102 has means 202 for providing. Device 202 for providing is designed to provide reference variable 208 for an adjustment device of the rotor blade using local bending angle or blade root bending moment 204 .

The controller 102 has an interface 210 for reading in or outputting at least rotational speed information 206 and/or a reference variable 208 .

FIG. 3 shows a flow chart of a method 300 for operating a wind energy installation according to an exemplary embodiment of the invention. Method 300 has a determined step 302 . Method 300 can be executed on a controller as shown in FIGS. 1 and 2 . In a determination step 302 , a local bending angle or blade root bending moment of at least one rotor blade of a rotor of a wind energy installation is determined using rotational speed information of the rotor blade and processing rules. In this case, the rotational speed information represents the rotational speed of the rotor blade detected on the rotor blade at a distance from the axis of rotation of the rotor. The processing rules represent a rotor-specific model of the rotor blade.

In one embodiment, the method 300 has a step 304 provided. In a provided step 304 , a reference variable is provided for an adjustment device of the rotor blade using a local bending angle or blade root bending moment.

4 and 5 show illustrations of variants on a wind energy installation 100 according to an exemplary embodiment of the invention. Wind energy installation 100 basically corresponds to the wind energy installation in FIG. 1 . The coordinate system K _N , K _T , the rotational speed ω _T,y , ω _T,x and the angles β, α _C , α _T , _x , _y as well as the offset w and the rotation angle Ω _R of the rotor 108 . Here, the coordinate system K _N is the rotor coordinate system. The coordinate system K _T is the coordinate system of the nacelle 106 or the tower. Both coordinate systems are referenced to the system coordinate system 400 , which here has, shifts and/or rotates its coordinate origin at the base of the tower 104 . The coordinate origin of the coordinate system K _T is arranged at the center of rotation of the nacelle 106 . The coordinate origin of the coordinate system K _N is arranged at the rotation center of the hub 110 . The coordinate system K _N and the axis of rotation 402 of the rotor are inclined by an angle α _{T relative to the coordinate system K T .} The rotor blades 112 are adjusted by an angle α _C relative to the axis of rotation 402 perpendicular to the rotor plane 404 . Angle β is the angle of attack of rotor blade 112 in hub 110 .

When the rotor blade 112 is deformed during operation, the rotor blade rotates at an angle _y is bent from the rotor plane 404 and the rotor blades are offset w relative to the rotor plane 404 .

The tower 104 is bent backwards in the direction of the axis of rotation 402 at a rotational speed ω _T,y due to the resultant force on the nacelle 106 and the tower 104 . The tower 104 is also offset laterally transverse to the axis of rotation 402 by ω _T,x due to the torque of the rotor 108 .

In order to reduce the mechanical stress on wind energy installation 100 and increase the efficiency, individual adjustments of rotor blades 112 in wind are aimed at. Different sensors are often proposed in combination with model knowledge as input signals for regulation. Also suggested are strain gauges, accelerometers and LIDAR.

Inexpensive and reliable provision of signals which are suitable as input variables for the controller for the individual adjustment of the angle of attack β of the rotor blade 112 is achieved by the method presented here. In particular the blade root bending moment is recovered.

The bending moment is estimated by analyzing the inertial data in the hub 110 and in the rotor blade 112 combined with model knowledge through the dynamic hold of the rotor blade 112 . In this case, the rotational speed ω is evaluated in particular and can be guaranteed by the acceleration.

In other words, the application of the rotational speed ω or the rotational speed ω and the acceleration sensor is introduced.

Based on this evaluation, regulation can minimize the mechanical and aerodynamic unbalance of rotor 108 , reduce the asymmetric loading of rotor 108 and maximize the efficiency of wind energy installation 100 .

At a point x ₀ on the rotor blade 112 , which is r ₀ at a distance from the axis of rotation 402 , the rotational speed ω and, as an extension of the method presented here, also the acceleration a are measured by means of corresponding sensors while the rotor 108 is rotating. The measured rotational speed ω is the superposition of the rotational speed ω of the rotor 108 , the oscillating motion of the tower 104 , the oscillating motion of the rotor blades 112 , and the rotational speed ω of the rotor blades 112 produced by the pitch adjustment β. According to an embodiment, the rotational speed ω, the acceleration a are vectors with three terms.

In addition to purely considering the rotational speed signal ω, it is also possible to analyze the combination of the rotational speed signal ω in the point x ₀ and the acceleration a in the point x ₀ or in another point on the rotor blade. In addition to the sources already mentioned for the rotational speed, gravity, centrifugal acceleration and Coriolis acceleration can also be taken into consideration for the acceleration.

It is useful to define different coordinate systems K _N , K _T for different elements of wind energy installation 100 and to define transformations between these coordinate systems. In the embodiment described here, a coordinate system K _N of the tower 104 , a coordinate system K _T of the hub 110 , a coordinate system K _BR of the blade root and a coordinate system _KB of the blade element 112 are considered.

The transformation is:

K _T → KN: R _y (α _T ),

K _N → K _BR : R _Z (β) R _y (α _C ) R _x (Ω _R ) and

K _BR →K _B : R _x ( _x ) R _y ( _y ).

R _x (α), R _y (α), R _Z (α) denote matrices which rotate the corresponding coordinate system by a given angle α around the x-axis, y-axis or z-axis. The angle α _N indicates the inclination of the main axis 402 relative to the structure at the top of the tower. Angle α _C indicates the conical adjustment of blade 112 . The angle of rotation due to rotor rotation is denoted by Ω _R and the pitch angle of the rotor blades is denoted by β.

The rotational speed ω generated by the tower oscillation in the coordinate system K _T is ω _T =[ω _T,x , ω _T,y ,0] ^T . Regarding the rotational speed of the rotor in K _N is . The pitch of the rotor blades 112 is considered in K _BR by the rotational speed cause. The rotational speed ω generated by the swing of the blade element 112 passes through the _KB to give.

Therefore, the rotational speed ω detected by the sensor positioned in the blade element 112 as a whole is:

Can directly measure the rotational speed ω _T , and . The variable β is the regulating variable of the system and is therefore also known. Its time derivative can be calculated, for example, by numerical differentiation. The angles α _C and α _T are structural variables and are also known as such structural variables.

Bending corners in the method presented here _x , _y is determined by the measured value ω _T , and recover. angle _y indicates the rotation of the blade element 112 in the direction of impact, and the angle is directly related to the root bending moment in the direction of impact. angle _x indicates the rotation of the blade element 112 in the pivot direction, and the angle is directly related to the blade root bending moment in the pivot direction.

introduced by The relationship and all measured values of rotational speed ω or angular velocity ω can be calculated _y and as well as _x and estimated value. Measurement noise can be reduced by combining these values and filtering in time.

Using a system-specific model for dynamically maintaining the blade 112, instead of statically recovering the target variable by subsequent filtering can also be designed directly for _x and The observer for _y (Beobachter).

The non-linear relationship provides, for example, a non-linear Kalman filter, such as an extended Kalman filter, an unscented Kalman filter or a rolling temporal estimation.

To improve the bending angle of recovery _x and The quality of _y , in addition to the speed, can also analyze the information of the acceleration sensor. The corresponding relationship is similar to that described here for the rotational speed ω.

The gravity and acceleration at the top of the tower due to the deflection of the tower are in the coordinate system K _T as kick in. Different accelerations in the coordinate system K _N due to rotation, centrifugal acceleration , Coriolis acceleration and the acceleration due to the change in rotor speed . The oscillation of the blade 112 results in an acceleration , where w represents the vector deflection of the blade 112 at point x ₀ . This term is an integral part of the coordinate system _KB .

The resulting measured acceleration is thus:

.

In vector deflection w and bend angle _x with There is a linear relationship between _y . The constant of proportionality can be calculated from the relationship of the bend line and the slope of the bend line at the location of the sensor.

Thus, a given measurement equation for acceleration can be used in a non-linear observer in order to improve the quality of the recovered signal.

In the method presented here, inertial sensors are used in or on the rotor blade 112 of the wind energy installation 100 . An individual pitch adjustment of the blades 112 is particularly well possible by means of this sensor.

The exemplary embodiments shown are selected as examples only and can be combined with one another.

List of reference signs:

100 wind energy equipment

102 controller

104 Tower

106 cabin

108 rotor

110 hub

112 rotor blades

114 spacing

116 sensor device

200 for sure device

202 means for providing

204 Local blade bending angle or blade root bending moment

206 speed information

208 reference variable

210 interface

300 Method for operating a wind energy plant

302 OK Steps

304 provided steps

400 system coordinate system

402 rotation axis

404 rotor plane

w offset

500 devices for extraction

502 Devices for determination

504 means for determining

506 acceleration sensor

508 acceleration value

516 load value

Claims (8)

1. Method (300) for determining a load on a rotor of a wind energy installation (100), wherein said method (300) has the following steps: determining (302) a local bending angle of at least one rotor blade (112) of a rotor (108) of the wind energy installation (100) using rotational speed information (206) of the rotor blade (112) and a processing rule, wherein said rotational speed information (206) represents said rotor blade (112) detected on said rotor blade (112) at a distance (114) from said rotor (108) axis of rotation (402) The rotational speed (ω) of , and the processing rule represents a rotor-specific model of the rotor blade (112). 2. The method (300) according to claim 1, wherein in the step of determining (302) the local bending angle is also determined using angle of attack information of the rotor blade (112), wherein the The angle of attack information represents the angle of attack (β) of the rotor blade (112) adjusted by the adjusting device. 3. The method (300) according to any one of the preceding claims, wherein in the step of determining (302) the local bending angle is also determined using acceleration information (508), wherein the acceleration Information ( 508 ) indicates an acceleration of the rotor blade ( 112 ) detected on the rotor blade ( 112 ) at a further distance ( 114 ) from the axis of rotation ( 402 ). 4 . The method according to claim 1 , wherein in the determining step, the blade deflection and/or the blade root bending moment are determined using local bending angles and processing rules. 5. The method (300) according to any one of the preceding claims, having the step (304) of providing in which using a local blade bending angle, blade offset or blade root bending moment A reference variable is provided for the adjustment device of the rotor blade. 6. The method (300) according to any one of the preceding claims, wherein the detected rotational speed (ω) and/or the detected acceleration are vectors. 7. A controller (102) for operating a wind energy installation (100), which controller is designed to carry out all the steps of the method (300) according to any one of the preceding claims. 8. Computer program set up to carry out all the steps of the method (300) according to any one of the preceding claims.