U.S. patent application number 13/581990 was filed with the patent office on 2013-08-01 for device and method for reducing loads.
This patent application is currently assigned to Robert Bosch GmbH. The applicant listed for this patent is Guenter Berger, Joachim Breidert, Boris Buchtala, Volker Knoblauch, Sebastian Schmidt, Bernd Schnurr, Stefan Zimmermann. Invention is credited to Guenter Berger, Joachim Breidert, Boris Buchtala, Volker Knoblauch, Sebastian Schmidt, Bernd Schnurr, Stefan Zimmermann.
Application Number | 20130195654 13/581990 |
Document ID | / |
Family ID | 44502786 |
Filed Date | 2013-08-01 |
United States Patent
Application |
20130195654 |
Kind Code |
A1 |
Berger; Guenter ; et
al. |
August 1, 2013 |
Device and Method for Reducing Loads
Abstract
A device for reducing loads in a drive train of a wind turbine
includes a machine support. The wind turbine includes a sensor
means, a controllable damper means, an actuating means. The sensor
means is configured to detect at least one variable characterizing
vibrations and/or misalignments in the drive train. The
controllable damper means is configured to produce at least one
adjusting torque which compensates at least one torque associated
with the load in the drive train. The actuating means is configured
to actuate the damping means based on the at least one variable
detected by the sensor means.
Inventors: |
Berger; Guenter;
(Castrop-Reuxel, DE) ; Zimmermann; Stefan;
(Stuttgart, DE) ; Breidert; Joachim;
(Schwieberdingen, DE) ; Buchtala; Boris;
(Muehlacker, DE) ; Schnurr; Bernd;
(Lohr-Sendelbach, DE) ; Schmidt; Sebastian;
(Wuerzburg, DE) ; Knoblauch; Volker;
(Bobenheim-Roxheim, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Berger; Guenter
Zimmermann; Stefan
Breidert; Joachim
Buchtala; Boris
Schnurr; Bernd
Schmidt; Sebastian
Knoblauch; Volker |
Castrop-Reuxel
Stuttgart
Schwieberdingen
Muehlacker
Lohr-Sendelbach
Wuerzburg
Bobenheim-Roxheim |
|
DE
DE
DE
DE
DE
DE
DE |
|
|
Assignee: |
Robert Bosch GmbH
Stuttgart
DE
|
Family ID: |
44502786 |
Appl. No.: |
13/581990 |
Filed: |
February 9, 2011 |
PCT Filed: |
February 9, 2011 |
PCT NO: |
PCT/EP2011/000606 |
371 Date: |
November 12, 2012 |
Current U.S.
Class: |
416/1 ;
416/43 |
Current CPC
Class: |
F03D 7/02 20130101; F01D
7/00 20130101; F16F 15/022 20130101; F05B 2270/334 20130101; F03D
80/00 20160501; F05B 2270/1095 20130101; Y02E 10/72 20130101 |
Class at
Publication: |
416/1 ;
416/43 |
International
Class: |
F01D 7/00 20060101
F01D007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 2, 2010 |
DE |
10 2010 009 863.9 |
Claims
1. A device for reducing loads in the drivetrain of a wind turbine
generator system with a machine carrier, comprising: a sensor means
configured to detect at least one variable characterizing
vibrations and/or misalignments in the drivetrain; an activatable
damping means configured to generate at least one adjusting torque,
which compensates for at least one torque associated with the load
in the drivetrain; and an activating means configured activate the
damping means on the basis of the at least one variable detected by
the sensor means.
2. The device as claimed in claim 1, wherein the damping means
includes an actuator means, by which an activatable movement of at
least one element of the drivetrain in relation to the machine
carrier can be brought about.
3. The device as claimed in claim 1, wherein the damping means
includes a braking means, by which an activatable braking of a
movement of at least one element of the drivetrain in relation to
the machine carrier can be brought about.
4. The device as claimed in claim 2, wherein the movement is a
rotation of the at least one element about an axis of rotation of
the drivetrain.
5. The device as claimed in claim 2, wherein the movement is a
raising or lowering of at least one element in relation to the
machine carrier.
6. The device as claimed in claim 1, wherein the sensor means
includes speed, acceleration, force, rotational speed, rotational
angle, position and/or torque sensors.
7. The device as claimed in claim 1, wherein the sensor means is
configured to detect vibrations and loads with respect to the
machine carrier and/or with respect to a surface of the Earth.
8. The device as claimed in claim 1, wherein the damping means
and/or the sensor means is/are provided on torque supports of the
drivetrain.
9. The device as claimed in claim 1, wherein: the device further
includes a model and/or an observer means, and the actuating means
is configured for a path adaptation.
10. A method for reducing loads in the drivetrain of a wind turbine
generator system, comprising: detecting at least one variable
characterizing a vibration and/or a misalignment in the drivetrain;
determining at least one torque associated with the load in the
drivetrain on the basis of the at least one variable detected;
determining at least one adjusting torque; compensating the at
least one torque, for reducing the loads; and subjecting at least
one element of the drivetrain to the at least one actuating torque
determined.
11. The method as claimed in claim 10, wherein a changing of the
torsional and/or flexural torque in the drivetrain is determined on
the basis of the variable detected.
12. The method as claimed in claim 10, wherein the at least one
element is rotated and/or raised or lowered in relation to a
machine carrier of the wind turbine generator system in an
activatable manner and/or the rotational movement of the at least
one element is retarded in an activatable manner for subjecting the
at least one element of the drivetrain to the at least one
actuating torque determined.
Description
[0001] The present invention relates to a device and a method for
reducing loads, in particular torsional vibrations as well as
static and dynamic flexural torques, in the drivetrain of a wind
turbine generator system.
[0002] 1. Prior Art
[0003] Drivetrains, comprising components such as for example gear
units, clutches and connecting elements (shafts), are important
constituent parts of various electrical power generating systems,
such as for example wind turbine generator systems, hydroelectric
installations, etc.
[0004] The drivetrain performs the task of establishing a
mechanical connection between a drive unit (for example a rotor of
a wind turbine generator system) and a driven unit (for example a
corresponding generator), via which power is transmitted through a
rotational movement. Drivetrain components such as gear units serve
the purpose of transforming the rotational speed and the torque at
the drive unit to values that correspond to the operating range of
the generator. Clutches are used as and when required for a
disconnection between the drive unit and the driven unit and shafts
establish the mechanical connection between the components
involved. Further components, such as mechanical brakes or the
like, may also be integrated in the drivetrain.
[0005] Since the components involved cannot be produced with any
rigidity that may be desired, but have a finite rigidity, they may
be induced to undergo natural vibrations. This may be caused, for
example, by an non-constant input power (in the case of wind
turbine generator systems for example due to wind surges or wind
turbulences) or by outside disturbances. Vibrations of other origin
may also increase the loads in the drivetrain, in the case of a
wind turbine generator system for example tower vibrations or
vibrations caused by the meshing engagements of a gear unit.
[0006] Further dynamic loads occur when the rotor blades pass the
tower during their rotation. Depending on the number of blades, the
reduction in wind speed immediately in front of the tower (in the
case of upwind turbines) or in the wake of the tower (in the case
of downwind turbines) results in periodic flexural torque loads in
the drivetrain of the wind turbine generator system. Furthermore,
static loads occur in the drivetrain if a misalignment between the
components involved has occurred during the assembly of the shafts.
This misalignment may also occur over time due to system components
moving by themselves (e.g. creep in the case of elastomer mountings
or settling in the case of screw connections) and consequently
results in additional flexural torque loads and forces.
[0007] Vibrations and other additional loads have disadvantageous
effects on the lifetime of the components involved, in particular
of the gear unit. Constant pulsating loads and static additional
loads increase the wear of the components concerned and lead to
shorter replacement intervals, which represents a financial and
technical burden on the operator of the system and the network and
reduces the income from the system. In particular from the
viewpoint of the presumably increasing proliferation of wind
turbine generator systems in the offshore area in the foreseeable
future, this aspect will play an ever-increasing role, since the
replacement of damaged components of such systems is made even more
difficult. There is therefore the aim of reducing these loads in
order to increase the lifetime of the components.
[0008] DE 1 993 07 51 A1 discloses a method for reducing vibrations
of components in a wind turbine generator system in which bearings
of an elastomeric material that has a damping angle of at least
12.degree. and a spring stiffness chosen such that the natural
frequency of the vibrating components is less than 50 Hz are used
in the system. A disadvantage of this is that respectively
pre-known elastomeric materials must be used for the damping of
specific vibrations and that adaptation to variable vibrations, for
example to fluctuating vibrational amplitudes, is not possible.
[0009] Against this background, there is the need for improved
solutions for reducing loads in the drivetrain of wind turbine
generator systems, in particular torsional vibrations, as well as
dynamic additional loads, that can be flexibly adapted to these
loads that occur and ensure a better reduction. Static additional
loads caused by misalignments are to be avoided, in order to
provide further relief for the drivetrain as a whole.
[0010] 2. Disclosure of the Invention
[0011] The present invention provides a device and a method for
reducing loads, in particular torsional vibrations as well as
static and dynamic additional loads, in the drivetrain of a wind
turbine generator system, with the features of the independent
patent claims. Advantageous refinements are the subject of the
subclaims and of the description which follows.
[0012] 3. Advantages of the Invention
[0013] The proposed measures allow a significant reduction of
torque vibrations or torsional vibrations and loads in the
drivetrain, in particular the gear unit, of wind turbine generator
systems to be brought about. In particular in such wind turbine
generator systems with a gear unit, a reduction of vibrations and
loads is particularly advantageous on account of the exposed
arrangement, the possible occurrence of wind surges, the
periodically fluctuating loading of the rotor (reduction in wind
speed immediately in front of the tower/in the wake of the tower
when the tower is passed by rotor blade) as well as possible loads
due to misalignment of one or more components.
[0014] The proposed measures make active damping of a mechanical
vibration or loading possible in a drivetrain by activatable
damping means. A torque or a force for vibration damping or load
reduction is generated by the activatable damping means. The use of
a suitable sensor system, in particular using acceleration sensors
based on the Ferraris principle, but also for example force,
rotational speed, rotational angle, position and/or torque sensors
and a closed-loop and/or open-loop control technique made to match,
allows particularly rapid, adaptive vibration damping and load
reduction to be brought about. A suitable actuator system or
adjustable, variable damping, as known per se, may be used for
example here.
[0015] In order to damp torsional vibrations, the actuators
advantageously bring about a rotation of the drivetrain or of the
corresponding gear unit and/or lead to a prescribed damping
sequence of a rotational movement. In this connection, even a
slight rotational movement by a few degrees about the axis of
rotation, in particular in conjunction with suitable
speed-transforming transmissions, can bring about significant
damping of torsional vibrations.
[0016] In addition, raising or lowering of the gear unit may be
brought about by the actuator system. The moving or adjusting of at
least one actuator or a combination of a number of actuators
advantageously leads here to an equalizing of loads. The latter may
be compensated both by periodic moving (in order for example to
equalize loads from the reduction in wind speed immediately in
front of the tower) and by the permanent adjustment (loads due to
misalignment of system components). Also in the case of this
approach to a solution, significant damping of additional loads can
be brought about even by very small adjusting movements.
[0017] An activated active and/or retarded rotational movement of a
drivetrain and/or of a gear unit housing integrated in a drivetrain
is brought about by the present invention. In other words, damping
of a rotational movement or of other loads is brought about by
damping means, that is to say for example by corresponding
actuators or springs, an adjusting torque resulting from a load
torque or corresponding thereto being generated. The corresponding
adjusting torque may be generated by controlled moving or adjusting
of at least one damper or by a combination of the damping means
described here. The damping movements can be set by suitable
open-loop or closed-loop control means.
[0018] By choosing suitable closed-loop and/or open-loop control
strategies, allowance can be made particularly advantageously for
the particular requirements of wind turbine generator systems. For
example, particularly advantageous damping can be brought about by
correcting the effects of wake.
[0019] The damping devices proposed according to the invention with
the associated closed-loop and/or open-loop control technique may
be advantageously integrated in torque supports of the drivetrain,
that is to say supports or fastenings for diverting a torque,
preferably on a gear unit housing.
[0020] Therefore, a reduction of vibrations and loads in the
drivetrain can be brought about by the measures according to the
invention. This particularly allows a reduction of the loads in
components of the drivetrain, in particular the gear unit, to be
achieved. As a result, the mechanical loading of wind turbine
generator systems is reduced, whereby the longevity of such systems
is improved significantly. Furthermore, a reduction of vibrations
also has the effect in particular of improving the output power of
a generator of the wind turbine generator system, since otherwise
variances in speed would have to be corrected in the generator.
[0021] As mentioned, the vibrations may be detected here by way of
measuring acceleration on the drivetrain, preferably at different
positions of the drivetrain, and/or by speed sensors. In the case
of speed sensors, it may be advisable to derive the speed for
determining the acceleration. The misalignment can likewise be
detected at the points concerned by corresponding position sensors.
Parallel models (as disclosed for example in EP 0 473 914 B1)
and/or control engineering observers (with variables that occur, in
particular torque, being calculated from the sensor variables with
the aid of models) may be used with particular advantage. A path
adaptation, which takes particularities and deviations from the
theoretical model into consideration, may also be advantageously
provided as part of the closed-loop control. Digital and/or analog
transmission of an output sensor signal may be used for the
closed-loop control, visualization, open-loop control and/or
switching.
[0022] Significant drivetrain vibrations are induced in particular
during emergency shutdowns (disconnection from the network or load
shedding) due to the suddenly absent generator torque in wind
turbine generator systems. Therefore, the device according to the
invention can be used with particular advantage as part of an
emergency shutdown procedure, in order thereby to significantly
reduce vibrations that occur.
[0023] A closed-loop and/or open-loop control device may also
include wind field sensors for pre-activating the damping system,
which may for example bring about a deflection from the neutral
position in the damping system, in order thereby to increase a
damping path. Such wind field sensors are advantageously arranged
on the upwind side.
[0024] It is taken as understood that such a pre-activation of the
damping system may also be performed using a multiplicity of
sensors, for example acceleration, force, rotational speed,
rotational angle, position and/or torque sensors, either on their
own or in combination.
[0025] A multiplicity of actuators may be used with particular
advantage within the scope of the present invention. Suitable
actuators comprise electrodynamic, piezoelectric, hydraulic
(cylinder, membrane) and pneumatic actuators, which may for example
also be realized using electroactive polymers, shape-memory
actuators or electro- or magneto-rheological fluids.
[0026] For example, devices that can be used as adjustable spring
elements include those that are disclosed in EP 1 566 543 A1.
Hydraulically pretensioned elastomer spring elements for supporting
a gear unit on its torque supports are provided here. These
elastomer spring elements are connected via hydraulic lines. For
damping a torque of a gear unit, a throttling of the fluid exchange
of the elastomer spring elements may be performed. In a
corresponding way, spring elements such as those known from EP 2
003 362 A2 may be used.
[0027] As already explained above, such actuators may be provided
at bearing points of torque supports, it being possible for example
to use a controlled oil and/or air bubble in the rubber. Apart from
single actuators, a number of actuators may be used, in particular
connected in series or in parallel, for different frequency ranges,
optionally also using different types of these actuators.
[0028] In particular for controlling the output power, but also for
damping, it may be advantageous for energy to be stored in an
accumulator, such as for instance a hydraulic accumulator, a
storage battery, a double-layer capacitor, in the form of
superconducting coils, flywheels and/or other inertial mass
systems. With regard to improved energy efficiency, it is
particularly advantageous to use the energy from an actuator for
feeding the network, so that an intercepted vibration can also be
used for power generation.
[0029] Further advantages and refinements of the invention emerge
from the description and the appended drawing.
[0030] It goes without saying that the features mentioned above and
still to be explained below can be used not only in the
respectively specified combination but also in other combinations
or on their own without departing from the scope of the present
invention.
[0031] The invention is schematically represented in the drawing on
the basis of an exemplary embodiment and is described in detail
below with reference to the drawing.
DESCRIPTION OF THE FIGURES
[0032] FIG. 1 shows a schematic cross-sectional view of a
drivetrain of a wind turbine generator system with a device
according to a particularly preferred embodiment of the
invention.
[0033] FIG. 2 shows a schematic longitudinal sectional view of a
drivetrain of a wind turbine generator system with a device
according to a particularly preferred embodiment of the
invention.
[0034] FIG. 3 shows a graph illustrating a reduction of vibrations
according to a particularly preferred embodiment of the
invention.
[0035] A transverse sectional view and a longitudinal sectional
view of a drivetrain of a wind turbine generator system with a
device for reducing loads according to a preferred embodiment of
the invention are respectively represented in FIGS. 1 and 2. FIGS.
1 and 2 are explained together, the cross-sectional view being
denoted overall by 100 and the longitudinal sectional view being
denoted overall by 200.
[0036] The drivetrain shown in FIGS. 1 and 2 is substantially made
up of a main shaft 10, a gear unit 20 and a generator shaft 30. The
gear unit 20 may be, for example, a three-stage gear unit that is
conventionally used in wind turbine generator systems. The main
shaft 10 is frictionally connected to a rotor, for example a vane
rotor R. The gear unit 20 is enclosed by a gear unit housing 21.
The generator shaft 30 is connected to a generator 40 via a clutch
31. FIG. 2 additionally shows a main bearing 90, in which the main
shaft 10 is mounted.
[0037] Torque supports 22 are provided for fixing or supporting the
gear unit housing 21. The drivetrain 10 to 30 is mounted as a whole
on a machine carrier 60. The mounting itself may be configured for
example as elastomer mounting 24, with two bearing bushes 24a and
24b respectively for each torque support 22. Damping systems
denoted overall by 25 are respectively provided between the machine
carrier 60 and the torque supports 22. As explained, the damping
systems 25 may have a series of different damping devices, one
actuator respectively for each bearing bush 25a and 25b being
represented by way of example within FIG. 2. The damping devices 25
are adjustable dampers. The control of such dampers is performed on
the basis of a control device that is not represented in detail but
is schematically indicated in FIGS. 1 and 2 by 70. The control is
performed with allowance for a measured-value output of one or more
sensors 80 and 82.
[0038] The sensors 80 detect a torque fluctuation, for example due
to a change in acceleration, in the drivetrain 10 to 30. By means
of the sensors 82, an angular offset or a deviation from the ideal
alignment of the shafts, is detected, for example laser-optically.
The control device 70 controls at least one of the provided damping
systems 25 in such a way that an adjusting torque is generated and
a torque fluctuation, or torsional flexural torque, is thereby
minimized. In a preferred refinement, the adjusting torque is
brought about by a rotation or by the raising or lowering of the
gear unit 20 or gear unit housing 21.
[0039] In order to reduce torsional vibrations, the left-hand
torque support 22 is moved upward, for example, by the damping
system 25 on the left in FIG. 1 and the right-hand torque support
22 is similarly moved downward by the damping system 25 on the
right in FIG. 1. The machine carrier 60 forms the common reference
point both for the detection of the torque and for the generation
of the adjusting torque, i.e. a variation on the rotational speed
in relation to the machine carrier is detected and an active
counter-rotation of the gear unit 20 in relation to the machine
carrier is brought about. Alternatively, damping may be performed
by the damping properties of the damping systems 25 being
prescribed variably over time in such a way that a rotation of the
gear unit 20 induced by a torque fluctuation is optimally
damped.
[0040] Dynamic loads that occur when the rotor blades pass the
tower during their rotation can be reduced for example by the
parallel moving of the damping systems 24a and/or 24b shown in FIG.
2. The exact periodic damping sequence, and consequently the moving
cycle of the damping means, depends on the number of rotor blades
and their rotational speed, and is consequently dependent on the
wind turbine generator system that is respectively under
consideration.
[0041] If it is intended to compensate for flexural torques and
forces resulting from a misalignment (a or .beta.), the damping
system 25b on the right in FIG. 2 may, for example, be moved
downward or the damping system 25a on the left in FIG. 2 may be
moved upward. The respective opposite damping systems, which in
FIG. 2 are concealed, are thereby likewise moved in a corresponding
way. Altogether, the compensation for possible alignment errors
between the gear unit and the main shaft and/or between the gear
unit and the clutch is produced by the raising or lowering of one
side or of the complete gear unit 20.
[0042] In FIG. 3, a torsional torque 310 without damping and a
torsional torque 320 after damping according to a particularly
preferred embodiment are represented in the form of a diagram 300,
in the form of a torque M on the y axis 302 against a time t of 5 s
on the x axis 301. As can be seen, a torsional torque vibration is
significantly reduced by the damping behavior according to the
preferred embodiment as compared with the undamped state.
* * * * *