DE102013223294A1 - Method for detecting a change in mass or rigidity of a component of a wind energy plant - Google Patents

Abstract

The invention relates to a method for detecting a change in mass or rigidity of a component of a wind energy plant, which has a drive train (15) and at least one component (10) which is mechanically connected to a rotatable element (20) of the drive train, wherein a Mass or stiffness change of the at least one component (10) by a change of a vibration (100; 101; 102) of the at least one component (10) in at least one direction on a time-varying size of the drive train (15), wherein the wind turbine detection means (50) for detecting the time variable variable, whereby the time variable variable is detected in time, wherein a signal of the time variable variable with respect to a deviation, which is caused by the mass or stiffness change of the at least one component (10) over a Reference value is examined.

Description

The present invention relates to a method for detecting a change in mass or rigidity of a component, in particular of a rotor blade, of a wind energy plant.

State of the art

Wind turbines are also installed at icing-prone locations. In the USA, for example, about 65% of the wind turbines are located in locations where icing is possible. Through various meteorological phenomena, ice can start on the rotor blades of wind turbines. This partly causes a mass increase of up to several hundred kilograms.

Such a high mass increase on the rotor blades can lead to heavy loads up to the destruction of wind turbines. In addition, so-called ice shedding may occur, i. Ice is thrown away from the rotor blades. The consequence can be damage to property, animals and persons.

One option for detecting ice on wind turbines is partly required by law or used for plant protection. After detection of ice, appropriate countermeasures can be taken, such as defrosting or stopping the system.

From the DE 100 65 314 B4 For example, a method is known with which changes in state of a rotor blade, for example. Eisansatz, a wind turbine can be detected. For this purpose, a special sensor is necessary, which is mounted on the rotor blade and connected to an evaluation unit. Such a method is costly and expensive to install due to the sensor or multiple sensors on multiple rotor blades.

It is therefore desirable to provide a way to detect mass or stiffness changes of rotor blades or other components of wind turbines cost and without or at least with little installation effort.

Disclosure of the invention

According to the invention, a method with the features of claim 1 is proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

Advantages of the invention

In a method for monitoring a wind turbine, which is a drive train and at least one component, in particular a rotor blade, which is mechanically connected to a rotatable element of the drive train, in particular a rotor, wherein a mass or stiffness change of the component on vibration changes of this component affects the drive train, is particularly suitable for detecting ice accumulation or lightning strike on the component of the wind turbine. It is particularly advantageous if in any case existing detection means, in particular a sensor, are used to detect changes in a signal detected by the detection means size. An additional, complex attachment of, for example, one or more sensors to one or more rotor blades is thus no longer necessary.

Advantageously, a speed, a rotation rate, an acceleration and / or a torque is used for the variable, wherein one or more of these variables are detected on a rotor shaft, on a transmission, in a transmission and / or on a further shaft in the drive train. In particular, they are not recorded on the component itself. Such variables are usually detected in wind turbines anyway and are suitable for analysis with regard to corresponding deviations.

Advantageously, the quantity is detected over time to generate the signal. The signal is accordingly a time sequence of values of magnitude. The signal may advantageously be analyzed temporally and / or spectrally, i. in the time domain or in the frequency domain.

A spectral analysis comprises in particular an evaluation of the occurring frequencies. The signal is subjected in particular to a Fourier transformation. Preferably, the signal is examined with regard to changes in certain frequencies, since vibrations of components take place in specific natural frequencies, which shift to lower frequencies in the case of, for example, mass increase and stiffness decrease.

A temporal analysis includes in particular an evaluation of vibration durations, phase angles and phase shifts and attenuations. In particular, the signal is subjected to no Fourier transformation, but rather time-based evaluation methods, such as stochastic subspace identification, system identification with autoregressive models, stability plot, Kalman filtering, auto and cross-correlation analysis in the time domain and linear and / or nonlinear principal component analysis.

It is also advantageous if a sensor is used for the inventive method, which is not located on a rotating component. This may be, for example, a speed sensor, which is mounted next to a shaft. This simplifies the mounting of the sensor and the associated cable routing. Also, such an attached sensor is less prone to failure.

An arithmetic unit according to the invention, e.g. a controller in a wind turbine, is, in particular programmatically, configured to perform a method according to the invention.

Also, the implementation of the invention in the form of software is advantageous because this allows very low cost, especially if an executing processing unit is still used for other tasks and therefore already exists. Suitable data carriers for providing the computer program are, in particular, floppy disks, hard disks, flash memories, EEPROMs, CD-ROMs, DVDs and the like. It is also possible to download a program via computer networks (Internet, intranet, etc.).

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

The invention is illustrated schematically with reference to an embodiment in the drawing and will be described in detail below with reference to the drawing.

figure description

1 schematically shows a drive train of a wind turbine and three rotor blades connected thereto via a rotor.

Detailed description of the drawing

In 1 is a powertrain 15 a wind turbine in a preferred embodiment shown. By way of example, there is the drive train 15 from one as a rotor 20 formed rotatable element, a rotor shaft 25 , a gearbox 30 , another wave 35 and a generator 40 ,

To the rotor 20 mechanically connected are three rotor blades 10 , Schematically there are three vibrations 100 . 101 . 102 a rotor blade 10 located. Here is the direction of the vibration 100 the direction of a rotation about a longitudinal axis 200 a rotor blade 10 ,

The direction of the vibration 101 is along a rotation axis 210 of the powertrain 15 , The direction of the vibration 102 is along the direction of rotation of the rotor 20 ie tangential to the axis of rotation 210 of the powertrain 15 , Usually, the rotor blade 10 excited to vibrate. A natural frequency of a vibratory system is a frequency with which the system can oscillate as a natural mode after a single excitation.

Furthermore, as a sensor 50 formed detection means for detecting a variable in time. In a preferred embodiment, the sensor detects 50 For example, a speed of the other shaft 35 , The sensor 50 is to a computing unit 60 connected, in which a signal of the detected speed, for example, is evaluated.

The sensor 50 In this case, preference is given to a sensor which is in any case connected to or in the drive train 15 the wind turbine is present, by which the corresponding size is detected in the wind turbine anyway.

The vibration 102 For example, has a certain frequency, which essentially depends on the mass and rigidity of the rotor blade 10 depends. The vibration 102 transmits through the mechanical connection of the rotor blade 10 on the drive train 15 , The frequency of the oscillation 102 is thus in a signal of the time-varying size of the drive train 15 visible, noticeable. For this purpose, depending on the nature of the time-variable variable and / or the signal, a corresponding transformation and / or adaptation of the signal must be made, for example a Fourier transformation. There, then the natural frequency, taking into account any scaling due to, for example, gear ratios, visible.

In order to obtain a reference value for the natural frequency, the natural frequency is determined in a properly functioning wind turbine. There may also be reference values over a range of different wind speeds and / or rotational speeds of the rotor 20 be determined.

During the operation of the wind turbine, the variable that is variable in time is, for example, continuously detected and processed accordingly, so that the natural frequency of the oscillation 102 can be found in it.

For mass or stiffness changes of the rotor blade 10 , For example, by ice accumulation or damage, eg. By lightning strike, the natural frequency of the oscillation changes 102 , This change also causes a change in the through the sensor 50 recorded variable in the driveline, ie it is the changed natural frequency found in it.

Such a deviation in the detected time-variable variable thus means a change of state of the rotor blade 10 , Corresponding (counter) measures can be initiated. By example. More accurate analysis of the natural frequency or its possible changes is also a more accurate interpretation possible, such as. An increased mass by ice accumulation, the amount of mass increase or a mechanical change of the rotor blade by, for example, lightning.

The example of the vibration 102 explained monitoring can also be for one of the vibrations 100 . 101 and / or combinations thereof.

In addition to the natural frequencies of the rotor blades, other vibrations, such as e.g. Coupling frequencies between the rotor and the drive train, to be evaluated in terms of mass change.

Such monitoring can not only with rotating rotor 20 take place, but also with the rotor stationary, if, for example, the wind speed is not sufficient to enable the rotor in rotation, but to vibrations of the rotor blades 10 to stimulate.

As an alternative or in addition to an evaluation in the frequency domain, an evaluation in the time domain is to evaluate period durations, amplitudes, phase angles and / or attenuations. From this, too, a mass or stiffness change can be determined in a simple manner, for example by comparing a period duration or frequency value and / or amplitude value and / or phase value of a reference state (ice-free and undamaged) with the current value.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10065314 B4 [0005]

Claims (12)

Method for detecting a change in mass or rigidity of a component of a wind energy plant which has a drive train ( 15 ) and at least one component ( 10 ) with a rotatable element ( 20 ) of the drive train is mechanically connected, wherein a mass or stiffness change of the at least one component ( 10 ) by a change of a vibration ( 100 ; 101 ; 102 ) of the at least one component ( 10 ) in at least one direction to a variable in size of the drive train ( 15 ); wherein the wind turbine detecting means ( 50 ) for detecting the time-variable variable, whereby the time-variable variable is detected in time; wherein a signal of time-variable magnitude with respect to a deviation caused by the mass or stiffness change of the at least one component ( 10 ) is examined against a reference value. The method of claim 1, wherein the time-varying variable is a rotational speed, a rotation rate, an acceleration and / or a torque. Method according to claim 1 or 2, wherein the time-variable variable on a rotor shaft ( 25 ), on a transmission ( 30 ), in a transmission ( 30 ) and / or on another wave ( 35 ) in the drive train ( 15 ) is detected. Method according to one of the preceding claims, wherein the signal is examined with respect to a deviation of a frequency from a reference value of the frequency. Method according to one of the preceding claims, wherein the signal is examined with regard to a deviation of a period duration and / or amplitude and / or phase position and / or attenuation from a reference value. Method according to one of the preceding claims, wherein at least part of the detection means ( 50 ) is located on a non-rotating component for detecting the time size. Method according to one of the preceding claims, wherein the detection means ( 50 ) comprise at least one sensor for detecting the time-variable variable. Method according to one of the preceding claims, which is carried out while the drive train ( 15 ) turns or does not turn. Method according to one of the preceding claims, wherein the at least one component ( 10 ) is a rotor blade. Arithmetic unit ( 60 ), which is adapted to perform a method according to any one of the preceding claims. Computer program that causes a computer unit to perform a method according to one of claims 1 to 9, when it is executed on the computing unit, in particular according to claim 10. Machine-readable storage medium with a computer program stored thereon according to claim 11.

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