JP2022124714A - Device for calculating blade fatigue damage amount of wind power generator and wind power generation system - Google Patents

Abstract

To provide a device for calculating a blade fatigue damage amount of a wind power generator and a wind power generation system which are highly reliable and inexpensive.SOLUTION: A device for calculating a blade fatigue damage amount of a wind power generator comprises: a blade fatigue damage amount calculation section which calculates a blade fatigue damage amount of a wind power generator from an average wind speed and turbulent intensity which are wind conditions in a predetermined period; a distortion measurement section which measures distortion in an axial direction of a tower trunk section; a correction coefficient calculation section which calculates a correction coefficient for the blade fatigue damage amount in the predetermined period, using a measurement value of the distortion in the axial direction in the predetermined period measured in the distortion measurement section, a measurement value of a rotation speed of the generator in the predetermined period, and a measurement value of a wind speed in the predetermined period as input data; and a corrected blade fatigue damage amount calculation section which calculates a corrected blade fatigue damage amount by correcting the blade fatigue damage amount calculated by the blade fatigue damage amount calculation section with the correction coefficient calculated with the correction coefficient calculation section.SELECTED DRAWING: Figure 1

Description

An embodiment of the present invention relates to a wind power generator blade fatigue damage amount calculation device and a wind power generation system.

Damage control of parts is important for efficient operation of wind power generators. In particular, if the blades of the wind power generator are broken or broken during operation, the blades may scatter or collide with the tower, resulting in a serious accident. As for blade damage, there are some damages that cannot be predicted individually, such as lightning strikes and bird strikes, but there are also damages that can be predicted over time, such as fatigue damage due to operation.

The fatigue damage amount of the blades can be estimated not only from the wind conditions at the installation site at the time of construction, but also from the actual operating conditions and wind conditions, using the design information of the wind power generator and the blades. By repairing or replacing blades whose material strength has decreased based on the amount of damage over time due to fatigue, breakage of the blades during operation can be prevented. However, repairing or replacing blades is costly and takes a long time. Excessive repair/replacement hinders efficient operation of wind power generators.

As a means of determining appropriate blade repair/replacement timing, there is a method of monitoring fatigue/durability of members based on fluctuating load due to wind conditions and information on the actual usage environment.

Japanese Patent No. 4939508 Japanese Patent Application Laid-Open No. 2004-101417

In the wind turbine structure stress analysis device, stress analysis program, and wind power generation system of Patent Document 1, load time series data is created based on parameters related to the operating environment in order to prevent failures due to fatigue deterioration due to fluctuating loads. Then, the stress time series data of the target location is created.

The monitoring device of Patent Document 2 detects a predetermined factor that affects the service life of the device, and calculates the degree of wear of the device and the remaining period of the service life by reflecting the history.

In order to ensure high reliability in the method of monitoring the fatigue and durability of members based on these wind conditions and usage information, it is necessary to obtain sufficient input information, product structure, operation, material strength A computing device based on various databases such as is required, but it is not easy. Regarding the fatigue damage amount of the blade, it is possible to use the method based on the general design information as described above, but as mentioned above, in reality, it is estimated from the wind conditions at the time of construction. Taking this into consideration, the amount of fatigue damage can be calculated cumulatively based on actual wind condition information.

We installed a strain gauge on the blade and calculated the amount of fatigue damage from the measured blade strain. Then, a comparison was made with the amount of fatigue damage calculated based on actual wind condition information. As a result, compared to the amount of fatigue damage calculated based on wind condition information, the actual amount of fatigue damage may be larger. It was found that the blade strain cannot be sufficiently estimated only from the general design information.

Although it is possible to directly monitor the behavior of the blade and calculate the amount of fatigue damage by attaching a strain gauge to the blade, it is not a cheap method. In other words, with the current technology, the calculation accuracy of the fatigue damage amount of the blades is low, and it is necessary to allow a margin for the fatigue damage amount. The problem is that there is no means of calculation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a highly reliable and inexpensive wind power generator blade fatigue damage calculator and wind power generation system.

A wind power generator blade fatigue damage amount calculation device according to an embodiment includes a blade fatigue damage amount calculation unit that calculates a blade fatigue damage amount of a wind power generator from an average wind speed and turbulence intensity, which are wind conditions within a predetermined period; a strain measuring unit that measures the axial strain of the tower body, an axial strain measured value within the predetermined period measured by the strain measuring unit, and a measured value of the rotation speed of the generator within the predetermined period; A correction coefficient calculation unit that calculates a correction coefficient for the blade fatigue damage amount within the predetermined period using the wind speed measurement value within the predetermined period as input data, and the blade fatigue calculated by the blade fatigue damage amount calculation unit. a corrected blade fatigue damage amount calculation unit that calculates a corrected blade fatigue damage amount by correcting the damage amount with the correction coefficient calculated by the correction coefficient calculation unit.

The figure which shows the structure of the wind power generation system of embodiment. FIG. 4 is a flow chart showing processing of the wind power generator blade fatigue damage amount calculation device of the embodiment. 4 is a diagram for explaining a tower moment M; FIG. The figure for demonstrating the method of calculating|requiring the fatigue damage amount correction factor of a blade. The figure for demonstrating the method of calculating|requiring the fatigue damage amount correction factor of a blade. The figure for demonstrating the method of calculating|requiring the fatigue damage amount correction factor of a blade. FIG. 4 is a diagram for explaining the relationship between wind conditions and the amount of fatigue damage;

DESCRIPTION OF THE PREFERRED EMBODIMENTS A wind power generator blade fatigue damage amount calculator and a wind power generation system according to embodiments will be described below with reference to the drawings.

As shown in FIG. 1, a wind power generation system 10 according to the present embodiment includes a wind power generator 20 and a fatigue damage amount calculation device 30 for wind power generator blades. A wind power generator blade fatigue damage amount calculation device 30 includes a blade fatigue damage amount calculation unit 31, a correction coefficient calculation unit 32, a corrected blade fatigue damage amount calculation unit 33, and a fatigue damage amount integration unit 34. ing.

The wind power generator 20 includes a nacelle 15 as a housing, a tower 14 as a support supporting the nacelle 15 from below, a plurality of blades (windmill blades) 12, and a boss supporting the plurality of blades 12 via a hub. 19 and .

The nacelle 15 incorporates a rotating shaft 17, a speed change mechanism 16, and a generator 18. As shown in FIG. One end of the rotating shaft 17 is fixed to the boss 19 and the other end of the rotating shaft 17 is connected to the transmission mechanism 16 . The transmission mechanism 16 is connected to the generator 18 via an appropriate coupling mechanism or the like. For example, the three blades 12 are fixed at their base ends at 120-degree intervals around the axis of the boss 19 (rotating shaft 17).

Here, during operation (during power generation) of the wind power generator 20, the directions of the pressure surface (positive pressure surface) and the suction surface of each blade body are adjusted so that each blade 12 rotates by receiving the wind force. . The directions of the pressure surface and the suction surface of each blade body are adjusted so that, for example, each blade 12 does not rotate even when the wind power generator 20 is not operating (during non-power generation). A plurality of such blades 12 , bosses 19 and rotating shafts 17 are rotatably supported with respect to the nacelle 15 .

That is, during operation of the wind power generator 20, the plurality of blades 12 rotating together with the boss 19 and the rotating shaft 17 convert fluid energy obtained from wind power into rotational energy. Also, the rotational energy (driving force) of the rotating shaft 17 is decelerated or accelerated by the transmission mechanism 16 and transmitted to the generator 18 . The generator 18 uses this transmitted rotational energy to generate electricity.

On the other hand, the nacelle 15 is provided with a wind condition measuring instrument (wind condition sensor) 23 having functions such as an anemometer and an anemoscope. The wind condition measuring instrument 23 capable of measuring wind direction and wind speed measures wind condition information representing, for example, the average wind speed and changes in wind speed at the installation location where the wind power generator 20 is installed, and the measured wind condition information ( measurement results). Note that the wind condition measuring instrument 23 may simply measure wind speed and wind direction and output the measurement result together with the measured time information. The nacelle 15 is also provided with a device (not shown) for controlling and measuring operating conditions such as the number of revolutions of the generator 18, the output of the generator 18, the pitch of the blades 12, and the like. Further, the tower 14 is provided with strain gauges 21 and 22 for detecting the strain of the body of the tower 14 and an entrance 24 through which workers enter and exit.

In the wind power generator 20 configured as described above, a strain gauge was installed on the blades 12, and the amount of fatigue damage to the blades 12 for 10 minutes was calculated from the measured strain of the blades 12. At that time, a strain gauge was also installed on the trunk of the tower 14, and from the strain behavior of the tower 14, the load and moment received by the blade 12 for 10 minutes were monitored.

As a result of this monitoring, it was found that each blade 12 receives different loads and moments during rotation, and the resultant force acts as the load and moment on the tower 14 . Furthermore, as a result of analyzing the correlation between the amount of fatigue damage to the blade 12 and the load and moment received by the blade 12, the amount of fatigue damage to the blade 12 that occurs within a certain time varies depending on the wind conditions (average wind speed, turbulence intensity). , is also affected by variations in the moment acting on the blade 12 during that time.

In other words, by combining the fatigue damage amount of the blade 12 calculated from the general wind conditions so far and the fatigue damage amount of the blade 12 calculated from the fluctuation of the moment received by the blade 12, the fatigue damage amount of the blade 12 It is expected that the calculation accuracy will improve.

In addition, in order to obtain the moment that the blade 12 receives during rotation, as in this measurement, a strain gauge is attached to each blade 12 to monitor the strain of the blade 12, or the deformation of each blade 12 is measured in detail. It is necessary to measure and monitor. However, this does not constitute an inexpensive measuring means.

Therefore, the strain behavior of the tower 14 was measured from a strain gauge installed on the body of the tower 14 . What is calculated by this is the sum of the force and moment that each blade 12 receives, and since the moment fluctuation that each blade 12 receives cannot be obtained, there is another problem that the amount of fatigue damage cannot be calculated. rice field.

Therefore, as a result of further investigation, although the instantaneous moment and load of each blade 12 are different, there is periodicity in the force and moment applied to each blade 12 during constant speed operation. It is found that the amount of divergence of is correlated with the magnitude of the moment fluctuation. More specifically, the periodicity of the moment depends on the rotational speed of the generator 18, and the deviation amount of the moment can be calculated from the difference in the original moment calculated from the change in the wind speed. Using the rotational speed of , measurements of wind speed change, and measurements of strain in the body of tower 14, the amount of fatigue damage correction can be calculated.

That is, by combining a device for cumulatively calculating the fatigue damage amount of the blade 12 from the wind conditions with a device for calculating the fatigue damage amount of the blade from the measurement data of the strain gauge installed on the tower 14, a low-cost and highly accurate blade 12 fatigue damage amounts can be monitored. This low-cost blade 12 fatigue damage amount calculation means enables the power generator to determine appropriate inspection and repair timings, enabling efficient operation of the wind power generator.

The graph of FIG. 7 shows the relationship between the parameter indicating the wind conditions for 10 minutes and the fatigue damage amount of the blade 12 for 10 minutes obtained from the measurement value of the strain gauge provided on the blade 12 . The parameters are the average wind speed and turbulence intensity for 10 minutes obtained from an anemometer installed at the height of the nacelle (value obtained by dividing the standard deviation of changes in wind speed during a certain period (standard deviation of fluctuating wind speed) by the average wind speed. ). The fatigue damage amount of the blade 12 is calculated using strain amplitude data of the blade 12 measured by a strain gauge attached to the blade 12 . A generally linear correlation is observed between this parameter and the amount of fatigue damage to the blade 12 . That is, by using this correlation, the amount of fatigue damage to the blade 12 can be estimated from the parameters calculated using the average wind speed and turbulence intensity.

However, this correlation has rather broad bands. In FIG. 7, even if the parameter values are the same, the fatigue damage amount of the blade 12 is approximately doubled. Looking at the safe side, when evaluating the fatigue damage amount using the maximum side fatigue damage amount and the upper limit curve, there is a possibility that the life will be estimated in half. In order to accurately estimate the replacement and repair timing of the blade 12, a fatigue damage amount correction coefficient that indicates where the fatigue damage amount during operation for a certain period corresponds to in the band shown by the upper limit curve and the lower limit curve. Desired.

Next, the tower moment will be described with reference to FIGS. 1 and 3. FIG. Consider a force, F, acting perpendicularly to the tower 14 through the blade rotation axis, as shown in FIG. Further, the moment acting on the tower 14 at a certain height of this blade rotation axis is defined as tower moment, M. In order to measure the strain in the axial direction of the body of the tower 14, the strain gauges 21 and 22 are installed at two or more locations with different heights in the axial direction. As will be described later, in order to calculate the moment, it is necessary to install strain gauges at two or more locations with different heights.

FIG. 3 shows how the tower moment is calculated from the axial strain of the tower shell. From the measured value of the strain in the tower axial direction and the section modulus of the tower, the moment of the strain gauge attachment height can be found. Using the blade rotation axis height F and M defined above, the moment of strain gauge attachment height is F × moment arm + M (moment arm: difference between blade rotation axis height and strain gauge attachment height) . The graph in FIG. 3 plots the moments at four points on the 2nd, 3rd, 4th, and 6th platforms at a certain moment, but from the straight line connecting these, the moment of the blade rotation axis height at that moment, M, is It can be seen that the relation of F×moment arm+M is established.

Next, a method for obtaining the fatigue damage amount correction coefficient of the blade 12 from the tower moment will be described. Assume that three blades 12 are arranged at a pitch of 120 degrees as shown in FIG. The tower load F is the sum of FB1 to FB3, and the tower moment M is the sum of the moments generated from FB1, FB2, and FB3.

Assuming that the force applied to the blades 12 is greatly affected by the wind speed, if the wind speeds at the positions of the blades 12 are the same at three locations, FB1 to FB3 have the same magnitude. At this time, even if the blade 12 rotates, the tower moment M therebetween is uniform. The actual tower moment fluctuates over time. This can also be caused by changes in wind speed, but if the change in wind speed at each blade position is the same, the variation in tower moment must be correlated with change in wind speed. However, in reality, fluctuations in tower moment cannot be explained only by changes in wind speed.

Therefore, consider a model in which the force applied to the blade 12 differs depending on the position of each blade. Focusing on the change in blade height during blade rotation, we considered a model in which the wind speed distribution changes depending on the blade height. FIG. 5 schematically shows the change amount (ΔFB) of the load received by the blade 12 when the blade rotates 180 degrees from the 12 o'clock position to the 6 o'clock position. It can be seen that this amount of change varies depending on the form of distribution of the load due to height (second order and half order in the example shown in FIG. 5).

FIG. 6 shows calculation results of how the tower moment changes for various load distributions of 2nd order, 1st order, 0.5th order, and 1/3rd order. It can be seen that the change in moment during one-third revolution of the blade 12 is determined by the load distribution. In other words, using this relationship, it is possible to determine the change in the force that each blade 12 receives during rotation from the amount of divergence between the change in tower moment calculated from the strain of the tower and the tower moment calculated from the change in wind speed. This is because even if the wind condition, average wind speed, and turbulence intensity are the same, there is a difference in wind speed when focusing on the height, there is a difference in the fluctuating load actually applied to the blade 12, and there is a difference in the amount of fatigue damage. Become.

As a result of the analysis, there is a correlation between the difference in the amount of fatigue damage due to the difference in the fluctuating load actually received by the blade 12 and the difference in the amount of fatigue damage found from the wind conditions in FIG. A correction factor can be derived.

It should be noted that it is necessary to use periodicity in obtaining the change in the force that each blade 12 receives during rotation from the difference between the tower moment change calculated from the strain of the tower 14 and the tower moment calculated from the wind speed change. . Here, when the fatigue life consumption of the blades 12 is high, focusing on the fact that the wind turbine is operating at a substantially constant speed, the periodicity is analyzed using the measurement data of the generator rotation speed (rotation speed). is doing. The periodicity shown in FIG. 6 can be obtained by performing frequency analysis such as Fourier transform on the waveform actually measured by the strain gauge provided on the blade 12 .

As shown in the flow chart of FIG. 2, in the wind power generator blade fatigue damage amount calculation device 30 shown in FIG. and turbulence intensity), the fatigue damage amount of the blade within a predetermined period is calculated (step 101 in FIG. 2).

Further, in the wind power generator blade fatigue damage amount calculation device 30, the correction coefficient calculation unit 32 measures the strain measured within a predetermined period from the strain gauges 21 and 22 that detect the strain in the axial direction of the body of the tower 14, and , using the measured value of the rotation speed of the generator within a predetermined period and the wind speed measurement value within the predetermined period as input data, and using the periodicity obtained by utilizing the measured value data of the rotation speed of the generator as described above. Then, a correction factor for the fatigue damage amount of the blade within a predetermined period is calculated (step 102 in FIG. 2). In other words, the change in the tower moment within a predetermined period is calculated from the strain measurement value, and the amount of change in the force applied to the blade is calculated from the measured value of the rotation speed of the generator within the predetermined period and the wind speed measurement value within the predetermined period. , from these calculation results, a correction factor for the amount of blade fatigue damage within a predetermined period is calculated.

Then, in the corrected blade fatigue damage amount calculation unit 33, the blade fatigue damage amount calculated by the blade fatigue damage amount calculation unit 31 is corrected by the correction coefficient calculated by the correction coefficient calculation unit 32, and within a predetermined period The fatigue damage amount of the corrected blade is calculated (step 103 in FIG. 2), and the fatigue damage amount of the corrected blade within this predetermined period is accumulated in the fatigue damage amount accumulation unit 34 (step 104 in FIG. 2).

While the wind power generator blades are rotating and generating power, the above steps 101 to 104 are repeatedly executed, and these steps are terminated while the wind power generator blades are stopped.

As described above, according to the configuration of the present embodiment, the amount of fatigue damage to the blade is affected by the moment in the axial direction of the tower using the measurement data of the strain gauge installed on the tower, which is an inexpensive means. To provide a highly reliable and inexpensive wind power generator blade fatigue damage amount calculator and wind power generation system by calculating the actual blade load change and using the fatigue damage amount correction factor calculated therefrom. be able to.

In the above embodiment, the case where the axial moment of the tower is determined by the strain gauges provided on the body of the tower has been described. Acceleration measurements may be used to determine the axial moment of the tower. Furthermore, in the above embodiment, a model is used in which the wind speed distribution changes depending on the height. and the measured value of the number of rotations of the generator within a predetermined period as input data, the correction factor calculation unit may be configured to calculate a correction factor for the fatigue damage amount of the blade within a predetermined period.

Although several embodiments of the invention have been described above, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

10...wind power generation system, 12...blade, 14...tower, 15...nacelle, 16...transmission mechanism, 17...rotating shaft, 18...generator, 19...boss, 20...wind power generation Machine 21 Strain gauge 22 Strain gauge 30 Wind power generator blade fatigue damage amount calculator 31 Blade fatigue damage amount calculator 32 Correction coefficient calculator 33 Correction Finished blade fatigue damage amount calculation unit, 34 . . . fatigue damage amount integration unit.

Claims (5)

a blade fatigue damage amount calculation unit that calculates the blade fatigue damage amount of the wind power generator from the average wind speed and turbulence intensity, which are the wind conditions within a predetermined period;
a strain measuring unit that measures the axial strain of the tower body;
The axial strain measurement value within the predetermined period measured by the strain measurement unit, the rotation speed measurement value of the generator within the predetermined period, and the wind speed measurement value within the predetermined period are used as input data, a correction factor calculation unit that calculates a correction factor for the amount of blade fatigue damage within the predetermined period;
Corrected blade fatigue damage amount for calculating a corrected blade fatigue damage amount by correcting the blade fatigue damage amount calculated by the blade fatigue damage amount calculation unit with the correction coefficient calculated by the correction coefficient calculation unit a calculation unit;
A fatigue damage amount calculation device for a wind power generator blade, characterized by comprising:
In the wind power generator blade fatigue damage amount calculation device according to claim 1,
The fatigue damage amount calculation device for wind power generator blades, wherein the strain measuring unit measures the axial strain of the tower body at two or more height positions of the tower body.
In the wind power generator blade fatigue damage amount calculation device according to claim 2,
The correction coefficient calculation unit
calculating a change in tower moment within the predetermined period from the strain measurement value from the strain measuring unit;
calculating the amount of change in the force applied to the blade from the measured value of the rotation speed of the generator within the predetermined period and the wind speed measured value within the predetermined period;
A wind power generator blade fatigue damage amount calculation device, wherein a correction coefficient for the blade fatigue damage amount within the predetermined period is calculated from these calculation results.
a blade fatigue damage amount calculation unit that calculates the blade fatigue damage amount of the wind power generator from the average wind speed and turbulence intensity, which are the wind conditions within a predetermined period;
Using as input data the measured values of wind speed measured at different heights within the predetermined period and the measured values of the rotation speed of the generator within the predetermined period, a correction coefficient for the fatigue damage amount of the blade within the predetermined period is calculated. a correction coefficient calculation unit for calculation;
Corrected blade fatigue damage amount for calculating a corrected blade fatigue damage amount by correcting the blade fatigue damage amount calculated by the blade fatigue damage amount calculation unit with the correction coefficient calculated by the correction coefficient calculation unit a calculation unit;
A fatigue damage amount calculation device for a wind power generator blade, characterized by comprising:
a wind generator;
A wind power generator blade fatigue damage amount calculation device according to any one of claims 1 to 4;
A wind power generator system comprising:

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