DE102018127417A1 - Modeling and forecasting wind flow using fiber optic sensors in wind turbines - Google Patents

Abstract

A measuring device and a method for measuring wind flows on one or more rotor blades of a wind power plant are disclosed. At least two pressure sensors are included, which are designed to measure a fluid pressure, preferably an air pressure, at points on a rotor blade surface, the sensors being attached along a rotor blade axis. In addition, an evaluation device is included to evaluate the signals of the at least two pressure sensors.

Description

TECHNICAL AREA

The registration is in the field of wind turbine technology. In particular, the present application discloses systems and methods for improved prediction and evaluation of wind flows with regard to wind energy generation systems.

TECHNICAL BACKGROUND

There are particular challenges in the design, operation, and maintenance of wind turbines

Depending on the changing wind conditions during operation, wind turbines are exposed to large loads that can lead to material fatigue. The estimated life of a wind turbine is based on its resistance to such harsh conditions.

A better description of loads that lead to material fatigue could therefore lead to improved use of the wind turbine. An estimate of the loads that cause fatigue can be based on successive wind conditions in different areas along a blade axis of the rotor.

However, wind measurements are normal. Estimates (via meteorological (met) masts or nacelle-based facilities). However, the large areas covered by the rotor blades also mean that there are different conditions along the blade axis.

In other words, the wind conditions can no longer be homogeneous within this large range. This area is too large for this, if you assume, for example, a rotor diameter of more than 130 m. The area, which is already covered by a rotor with a diameter of 100 m, for example, is approximately 7,800 m ² . It can thus be seen that within such an area there may be different wind conditions or wind flow conditions at different locations on the area.

Time and space dependencies as well as statistical models can be used to estimate the change in wind flow conditions along the rotor blade axes, also known as "turbulent wind models". As modern wind turbines reach heights at which atmospheric influences can influence these models, the long-term description can be influenced by daily and regional differences.

In addition to the loads that can lead to material fatigue and failure of the system, predictions about an expected return on wind energy are of interest.

A yield of an expected wind energy production is given with probabilities of P50, P75 and P90. This means that probability values for an expected yield from wind power can be predicted with probabilities of 50, 75 or 90%.

Better estimates therefore reduce risk and improve financial conditions.

Mostly, cost-intensive measurements of at least one year in length are carried out using metal masts including several anemometers to describe wind flow fields (mathematically a vector field) during the location selection, as well as to carry out wind energy estimates and layout optimization.

Because local, i.e. To date, depending on the wind turbine-specific conditions depending on the geographic conditions around each of the turbines, a generic, representative wind field estimate has been carried out first with measurements of the meteorological masts of the wind turbines, in order to then extrapolate them for each turbine position. Limitations of the methods and their informative value or relevance of measurements are included in the probability estimates.

Both the minimum value for an expected wind energy production and the maximum fatigue load that are tolerated belong to the parameters in the design of a wind turbine.

Wind flow conditions are suggestions of a mechanical system whose system response is simulated using physical models. Therefore, the approaches proposed in the industry focus on a direct measurement of the system response i.e. on the generation of energy, mechanical loads or structural deformation of system components in a particular wind flow (excitation).

Estimating wind conditions is therefore the by-product of reverse modeling, in which the system response is used to infer or estimate an expected deflection.

Newer approaches in the industry are aimed at a better description of wind conditions in front of the rotor, such as with LiDAR technology (acronym for Light Detection And Ranging), anemometers that are mounted in the rotor hub and cameras in the rotor blades that make their deformations visible. However, each of these approaches has advantages and disadvantages:

However, LiDARs are dependent on atmospheric conditions and are more suitable for wind energy prediction than for load estimation because they scan an area in front of the turbine rather than a point; on the other hand, anemometers on the rotor hub do the opposite and provide better estimates than current Nacellen-based measurements. The US7281891B2 (2003-02-28), for example, discloses a wind turbine control with a LiDAR wind speed measuring device.

Cameras installed in the blades are a further improvement because they are arranged in the area of the wind for blade interaction. However, their line of sight is limited against the tip of the leaf when the leaves bend out of their field of vision. DE102011011392A1 (2011-02-17), for example, discloses an optical measuring device for measuring the deformation of a rotor blade of a wind turbine.

The US6909198B2 (2000-07-07) discloses a method and a device for processing and predicting the flow parameters of turbulent media.

A simpler and improved method and a device for predicting wind flow conditions on a rotor is therefore desirable.

SUMMARY

In a first aspect, therefore, a device for measuring wind flows on one or more rotor blades of a wind power plant is disclosed. The device can have at least two sensors, which can be designed to measure a fluid pressure at points on a rotor blade surface. This fluid pressure can be a wind-generated pressure and can be output as an electronically processable signal.

Furthermore, the device can contain an evaluation unit, which can be designed to evaluate signals from the at least two sensors and to supply the evaluation data resulting therefrom to a subsequent control unit.

In a further aspect, a method for determining wind parameters on a rotor blade surface is disclosed. The method may include: determining air pressure readings at at least two points on a rotor blade surface; Transfer of the air pressure measured values into an electronic evaluation unit; Evaluating the air pressure measured values and subsequently; Determine one or more parameters from the group: wind speed vector, turbulence intensity or wind shear.

According to a further aspect, a rotor blade is disclosed with a measuring device according to one or more aspects of the present disclosure.

In a further aspect, a wind turbine is disclosed with a measuring device according to one or more aspects of the present disclosure.

Figure list

• 1a, 1b, und 1c ein Rotorblatt gemäß Ausführungsformen der vorliegenden Anmeldung;
• 2 einen Rotor einer Windkraftanlage in Frontansicht;
• 3 eine Windkraftanlage im Windstrom in Seitenansicht; und
• 4 ein Ablaufdiagramm für ein Verfahren gemäß Ausführungsformen der Erfindung.

Exemplary embodiments are shown in the drawings and explained in more detail in the description below. The drawings show:

• 1a , 1b , and 1c a rotor blade according to embodiments of the present application;
• 2nd a rotor of a wind turbine in front view;
• 3rd a wind turbine in wind power in side view; and
• 4th a flowchart for a method according to embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to a preferred embodiment, therefore, a measuring device for measuring wind flows on one or more rotor blades 110 a wind turbine disclosed. The measuring device can have at least two sensors 130 contain. These sensors can be designed to measure a fluid pressure at points on a rotor blade surface and to output this as an electronically processable signal. The measuring device can also contain an evaluation device which is designed to evaluate signals from the at least two sensors and to supply these as evaluation data to a subsequent control unit. The sensors can preferably be along a rotor blade axis 120 of the rotor blade 110 be arranged as in 1a and in 1c (Side view) shown.

The control unit and the evaluation device can be arranged in a rotor blade be or at another location of the wind turbine evaluation device 150 , 210 and control unit 220 can also be arranged at different positions of the wind power plant, for example the external device can be arranged in a rotor blade and the control unit in the tower of the wind power plant or a machine housing, that is to say the part of a wind power plant in which the generator, transmission, etc. are accommodated.

Advantageously, several or all of the rotor blades 110 of a rotor 200 along their rotor blade axis 120 be equipped with sensors. It is particularly advantageous if at least two sensors are arranged along the rotor blade axis of each rotor blade. The higher the number of sensors used, the more precisely the following parameters can be determined. 2nd shows a rotor 200 with three rotor blades 110 . The arrangement of pressure sensors is schematic on one of the sheets 130 along the axis 120 of the rotor blade shown.

According to the embodiments described here, which refer to pressure sensors along the axis of a rotor blade, the pressure sensors can be arranged parallel to the axis of the rotor blade. Furthermore, the axis of the rotor blade according to the embodiments described here is considered the neutral fiber of the rotor blade or the line on the surface of the rotor blade with the greatest wind-blade interaction. This axis or line can be a straight or a curved line starting from the leaf root to the leaf tip. The definition of the rotor blade axis, or the line with the greatest wind-blade interaction, is carried out uniformly starting from the blade root to the blade tip within the scope of the embodiments described here.

According to a further advantageous aspect, the sensors of the measuring device can be fiber-optic sensors according to one or more of the preceding aspects. Fiber-optic sensors are very weather-resistant, robust and insensitive to, for example, electrical influences such as lightning strikes, as can occur on wind power towers or rotor blades.

Fiber optic sensors, in particular fiber optic pressure sensors, are known as such and are described, for example, in US Pat DE 10 2014 210 949 A1 disclosed.

In a further embodiment, a measuring device according to one or more of the preceding aspects is disclosed, wherein the evaluation device contained in the measuring device can be adapted to determine one or more parameters from the group of wind speed vector, turbulence intensity or wind shear from the evaluation data. The evaluation device can also be adapted to determine a prediction of the wind yield probability from the evaluation data. A wind report can be created from this to predict the energy yields that the wind turbine can deliver.

Due to the fact that the wind conditions can be measured locally on the blades or on the rotor blade surface by means of the fiber optic pressure sensors, more precise statements can be made about a wind energy yield to be achieved or the wind conditions to be expected in the short term. This can enable a much more precise control of the system, since there is real-time behavior of the wind conditions on the rotor blades.

An optimized wind turbine control is therefore not implemented via their system response, but can advantageously be implemented directly via the deflection of the fiber-optic sensors attached to the rotor blades in order to control the system.

3rd shows the conditions of one of wind 310 flowed rotor with rotor blades 110 on which there are pressure sensors 130 are located.

In a further advantageous embodiment, a measuring device according to one or more of the preceding aspects is disclosed, wherein the evaluation device can be further adapted to determine a load prediction of one or more mechanical components of the wind power plant from the evaluation data. The mechanical components can be, for example, the tower of the wind power plant, the rotor blades of the wind power plant or the gear of the wind power plant. All of these components are exposed to the stresses of changing wind conditions, such as when looking at the 3rd becomes clear.

The determination of the wind conditions with very short system response times, which is possible according to the invention, makes it possible to react more quickly to loads and thus to reduce excessive wear on the system. With a longer service life of the system, better economy can be achieved.

According to a further advantageous embodiment of the present application, a method 400 disclosed for determining wind parameters on a rotor blade surface. The process may include, among others:

Determine 410 of fluid pressure measured values, in particular of air pressure measured values at least two points on a rotor blade surface. Take over 420 the air pressure measured values in an electronic evaluation unit as well as evaluation 430 the air pressure readings and then determining 440 one or more parameters from the group: wind speed vector, turbulence intensity or wind shear.

According to a further preferred embodiment, a method for determining wind parameters according to the preceding aspects is disclosed. Here, the determination of the air pressure measured values can be done by means of fiber optic sensors which are arranged along a rotor blade axis.

According to a further advantageous embodiment, a rotor blade 110 disclosed with a measuring device according to one or more of the preceding aspects.

According to a further advantageous embodiment, a wind turbine with one or more rotor blades 110 disclosed with a measuring device according to one or more aspects of the present application.

The following features are particularly advantageous for embodiments of the present invention.

Fiber optic sensors are advantageously attached along the rotor blade axis. Measurements are thus carried out at the optimal position along the rotor blade axis, i.e. exactly where a wind-blade interaction takes place.

This localization overcomes the limitations of previous approaches because it measures the wind conditions along the entire area described by the rotor and does so at a higher sampling rate.

Measuring a deflection is the focus and not a system response. Advantage through time-to-response. It is not the system response that is of interest, but the measurement of a deflection as a direct reaction of a force caused by the oncoming wind.

The entire sheet length and not just point estimates is used to describe the wind flow. Measurements are carried out with fiber optic sensors that can measure a local pressure. The sensors are thus arranged so that the measured values can map all points at least along the rotor blade axis.

The measuring device according to the present disclosure and corresponding methods thus overcome problems and limitations of alternative procedures:

Wind speed vector, turbulence intensity and wind shear can be measured as areas with high sampling rates.

Turbulent wind field models can be better validated and further improved. Wind energy probability estimates can be improved in their accuracy and precision.

The methods and facilities presented enable new applications. For example, very short-term wind energy forecasts (less than 10 minutes goal time) are possible. In contrast to previous procedural measures, this enables very effective and fast control of the wind power plant and can thus contribute to optimized wind energy generation. The load values from the wind flow measured directly on the blades of the plant can be used advantageously for the operation and also in the design of wind power plants.

The influence of the wind speed on the rotor can be determined directly at the measuring location (pitch angle and sheet torsion calibration)

A wind / load dependency can be measured in real time (hybrid model correction for aero-elastic models) and can contribute to an improved design in wind turbine development.

Optimized turbine control is not implemented via its system response, as was previously the case, but directly via its deflection, in order to control the wind turbine.

Although the present invention has been described above on the basis of typical exemplary embodiments, it is not restricted to these but can be modified in a variety of ways. The invention is also not limited to the application possibilities mentioned.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for better information for 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.

Patent literature cited

• US 7281891 B2 [0017]
• DE 102011011392 A1 [0018]
• US 6909198 B2 [0019]
• DE 102014210949 A1 [0032]

Claims (12)

Measuring device for measuring wind flows on one or more rotor blades of a wind turbine, with at least two pressure sensors which are designed to measure a fluid pressure at points on a rotor blade surface, the at least two pressure sensors being arranged on one or more rotor blades, an evaluation device which is designed to evaluate signals of the at least two pressure sensors. Measuring device after Claim 1 , wherein the at least two pressure sensors are arranged along the rotor blade axis of one or more rotor blades. Measuring device according to one of the preceding claims, wherein the pressure sensors are fiber optic sensors. Measuring device according to one of the preceding claims, wherein the evaluation device is adapted to determine one or more parameters from the group wind speed vector, turbulence intensity or wind shear from the evaluation data. Measuring device according to one of the preceding claims, wherein the evaluation device is further adapted to determine a prediction of the wind yield probability from the evaluation data. Measuring device according to one of the preceding claims, wherein the evaluation device is further adapted to determine a load prediction of one or more mechanical components of the wind power plant from the evaluation data. Measuring device according to one of the preceding claims, wherein the mechanical components include one or more from the group tower of the wind turbine, rotor blades of the wind turbine, gearbox of the wind turbine. A method for determining wind parameters on a rotor blade surface, comprising: Determining air pressure measurements at at least two points on a rotor blade surface; Transfer of the air pressure measured values into an electronic evaluation unit; Evaluating the air pressure measured values and subsequently; Determine one or more parameters from the group: wind speed vector, turbulence intensity or wind shear. Method for determining wind parameters according to Claim 8 , wherein the determination of the air pressure measured values takes place by means of fiber optic sensors which are arranged on one or more Roror sheets. Method for determining wind parameters according to Claim 9 , wherein the pressure sensors are arranged along a rotor blade axis. Rotor blade with a measuring device according to one of the preceding claims. Wind power plant with one or more rotor blades with a measuring device according to one of the preceding claims.

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