U.S. patent application number 10/470754 was filed with the patent office on 2004-04-29 for wind energy plant.
Invention is credited to Wobben, Aloys.
Application Number | 20040081551 10/470754 |
Document ID | / |
Family ID | 7673596 |
Filed Date | 2004-04-29 |
United States Patent
Application |
20040081551 |
Kind Code |
A1 |
Wobben, Aloys |
April 29, 2004 |
Wind energy plant
Abstract
The present invention concerns a wind power installation
comprising a pylon and a rotor arranged on the pylon and having at
least one individually adjustable rotor blade, comprising a device
for detecting the wind direction and a device for detecting the
azimuthal position. The object of the present invention is to
develop a wind power installation of the kind set forth in the
opening part of this specification in such a way that the service
life of the azimuthal drives is prolonged and/or it is possible to
use smaller azimuthal drives which can thus be better handled. A
wind power installation comprising a pylon and a rotor arranged on
the pylon and having at least one individually adjustable rotor
blade, comprising a device for detecting the wind direction and a
device for detecting the azimuthal position. characterised by a
control of rotor blade adjustment in dependence on a deviation
between the ascertained wind direction and the detected azimuthal
position.
Inventors: |
Wobben, Aloys; (Aurich,
DE) |
Correspondence
Address: |
Neil Steinberg
Steinberg & Whitt
Suite 1150
2665 Marine Way
Mountain View
CA
94043
US
|
Family ID: |
7673596 |
Appl. No.: |
10/470754 |
Filed: |
November 12, 2003 |
PCT Filed: |
January 25, 2002 |
PCT NO: |
PCT/EP02/00898 |
Current U.S.
Class: |
415/4.1 |
Current CPC
Class: |
F05B 2270/321 20130101;
F03D 7/0224 20130101; F03D 7/0204 20130101; F05B 2240/93 20130101;
Y02E 10/72 20130101; F05B 2270/20 20130101; F05B 2270/326 20130101;
F03D 13/25 20160501; Y02E 10/727 20130101 |
Class at
Publication: |
415/004.1 |
International
Class: |
F03D 007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 10, 2001 |
DE |
101 06 208.7 |
Claims
1. A wind power installation comprising a pylon and a rotor
arranged on the pylon and having at least one individually
adjustable rotor blade, comprising a device for detecting the wind
direction and a device for detecting the azimuthal position.
characterised by a control of rotor blade adjustment in dependence
on a deviation between the ascertained wind direction and the
detected azimuthal position.
2. A wind power installation according to claim 1 characterised by
a platform (30) which floats on or in the water as a carrier for
the wind power installation (8, 10, 12).
3. A wind power installation according to claim 2 characterised by
a device for detecting the deflection of the platform (30) out of
the horizontal.
4. A wind power installation according to claim 2 or claim 3
characterised by a device for detecting the deflection of the pylon
(8) of the wind power installation (8, 10, 12) out of the
vertical.
5. A wind power installation according to one of the preceding
claims characterised by an azimuthal bearing in the form of a plain
bearing.
6. A wind power installation according to one of the preceding
claims characterised by a braking device for braking the azimuthal
rotary movement.
7. A wind power installation according to one of the preceding
claims characterised in that there is provided an azimuthal drive
for adjustment of the azimuthal position of the wind power
installation and comprising at least two and preferably four
asynchronous motors which during the azimuthal adjustment by
control of the rotor blade adjustment are acted upon with no direct
current or possibly a very low direct current or which are acted
upon with a three-phase current to assist with the azimuthal
adjusting movement.
8. A method of controlling the angle of incidence of a rotor blade
of a wind power installation according to one of the preceding
claims characterised in that a change in wind direction is
ascertained from a difference between the wind direction and the
azimuthal position and/or a deflection of the platform (30) out of
the horizontal and/or a deflection of the pylon (8) out of the
vertical and that the magnitude of the change in wind direction and
the duration thereof are compared to predeterminable threshold
values.
9. A method according to claim 8 characterised in that when a first
threshold value in respect of the magnitude of the change in wind
direction and a predetermined duration are exceeded at least one
rotor blade in a predeterminable region of the rotor blade circle
is adjusted.
10. A method according to claim 8 characterised in that when a
second threshold value in respect of the magnitude of the change in
wind direction is exceeded at least one rotor blade in a
predeterminable region of the rotor blade circle is adjusted and
the azimuthal drive is switched on.
11. A method according to claim 8 characterised in that when a
third threshold value in respect of the magnitude of the change in
wind direction is exceeded tracking adjustment is effected only
with the azimuthal drive.
12. A method according to one of the preceding claims characterised
in that to assist with the azimuthal adjustment by means of rotor
blade adjustment the azimuthal drives are supplied with a
corresponding current so that the azimuthal adjustment can be
effected more quickly.
13. A method according to one of the preceding claims characterised
in that the motor azimuthal drive is operated during azimuthal
adjustment by means of rotor blade adjustment in a braking mode,
for example by virtue of the fact that the azimuthal drive is in
the form of an asynchronous motor and during azimuthal adjustment
by means of rotor blade adjustment is supplied with a direct
current, for example a direct current of less than 10% of the
nominal current.
Description
[0001] The present invention concerns a wind power installation
comprising a pylon and a rotor arranged on the pylon and having at
least one individually adjustable rotor blade, comprising a device
for detecting the wind direction and a device for detecting the
azimuthal position.
[0002] Such wind power installations generally have an active drive
for tracking the wind direction. The drive rotates the machine
housing of the wind power installation in such a way that the rotor
blades of the rotor are oriented in the direction of the wind if
the installation is in the form of a windward-type rotor member.
That drive which is required for wind direction tracking is usually
an azimuthal drive which is usually disposed with the associated
azimuthal bearings between the top of the pylon and the machine
housing.
[0003] In the procedure involving the machine housing tracking the
wind direction, an operational wind measuring system supplies a
mean value in respect of the wind direction over a certain period
of time, for example ten seconds. That mean value is always
compared to the instantaneous azimuthal position of the machine
housing. As soon as a deviation exceeds a given value, the machine
housing is correspondingly adjusted to track the change in wind
direction so that the deviation of the rotor in respect of the wind
direction, being the yaw angle, is as slight as possible in order
to avoid power losses.
[0004] The way in which a wind direction tracking procedure is
implemented in known wind power installations is described in
`Winkraftanlagen`, Erich Hau, 2nd edition, 1996, pages 268 ff and
316 ff respectively.
[0005] In addition such a wind direction tracking procedure is
known from laid-open application DE 199 20 504.
[0006] A disadvantage with those known arrangements however is that
the azimuthal drives which are frequently in the form of electric
motors have to be actuated for each wind direction tracking
operation. Frequent actuation results in a high loading and
correspondingly relatively rapid ageing and a high level of wear in
such drives.
[0007] Furthermore a disadvantage with known structures of that
kind is that increasing sizes of installation logically require
more or larger drives in order to be able to implement the required
adjusting movement. However, particularly in the case of a fault or
if replacement is necessary, those larger drives require a
considerably higher level of expenditure as they can only be moved
out of or into the machine housing by means of a crane. If a hub
height of 130 m and more is further factored into the
considerations, installations which are set up on land already
involve a considerable level of expenditure; however that rises far
beyond all acceptable limits if the installation is an offshore
installation. It will be appreciated that the amount of space
required for such drives also increases.
[0008] Therefore the object of the present invention is to develop
a wind power installation of the kind set forth in the opening part
of this specification in such a way that the service life of the
azimuthal drives is prolonged and/or it is possible to use smaller
azimuthal drives which can thus be better handled.
[0009] In accordance with the invention, in a wind power
installation of the kind set forth in the opening part of this
specification, that object is attained by a control of rotor blade
adjustment in dependence on a deviation between wind direction and
azimuthal position. That control according to the invention means
that a considerable proportion of the wind direction tracking
operation can be effected without switching on an azimuthal drive
as the forces required for the wind direction tracking procedure
can be produced by suitable adjustment of the angle of incidence of
the rotor blades.
[0010] The invention affords the possibility, besides the hitherto
usual azimuth adjustment by means of a motor drive, together with
the motor drive or as an alternative thereto, to implement
azimuthal positioning by control of the rotor blade adjustment in
dependence on a deviation between the wind direction and the
azimuthal position. Under some circumstances that is particularly
advantageous when only slight azimuthal changes have to be
effected. That means that the motor azimuthal drive generally is
conserved.
[0011] If for example the motor azimuthal drive comprises two or
more asynchronous motors, those motors, for azimuthal adjustment,
can be supplied with corresponding three-phase current, but
retardation of the machine housing is effected by means of a direct
current supply to the asynchronous motors and the asynchronous
motors are also supplied with direct current during the stoppage
condition so that a mechanical brake is not absolutely necessary.
If now displacement of the machine housing, that is to say
azimuthal adjustment, is to be effected by means of the control of
the rotor blade adjustment, motor braking must be terminated, which
is preferably effected by the direct current being extremely low or
zero.
[0012] In a preferred embodiment of the invention, when the carrier
of a wind power installation according to the invention is a
platform on a floating platform or a platform floating in the
water, the deviation between wind direction and azimuthal position
is ascertained from detection of the deflection of the platform out
of the horizontal or deflection of the pylon of the wind power
installation out of the vertical. In that fashion it is easily
possible to detect an inclination which necessarily arises out of a
difference between wind direction and azimuthal position.
[0013] In a particularly preferred embodiment of the invention the
wind power installation according to the invention has an azimuthal
bearing in the form of a plain bearing which, by virtue of
predetermined sliding properties, on the one hand prevents knocking
or flapping of the pylon head in the event of rapid changes in wind
direction but on the other hand, with sufficiently high forces,
permits wind direction tracking without a motor drive.
[0014] Furthermore the invention provides a method of controlling
the angle of incidence of a rotor blade of a wind power
installation. That method ascertains a change in wind direction
from
[0015] a difference between wind direction and azimuthal position
and/or
[0016] a deflection of the platform out of the horizontal
and/or
[0017] a deflection of the pylon out of the vertical
[0018] and the magnitude of the change in wind direction and the
duration thereof are compared to predeterminable threshold values.
It is possible in that way to recognise whether there is a need for
wind direction tracking to be implemented.
[0019] Further advantageous embodiments are set forth in the
appendant claims.
[0020] An embodiment of the present invention is described in
greater detail hereinafter with reference to the Figures in
which:
[0021] FIG. 1 is a plan view of a machine housing of a wind power
installation,
[0022] FIG. 2 shows a wind power installation on a platform
floating in water,
[0023] FIG. 3 shows a simplified view of a control according to the
invention,
[0024] FIG. 4 shows a view on to an azimuthal bearing with four
drives, and
[0025] FIG. 5 shows a circuit diagram for an azimuthal motor.
[0026] FIG. 1 is a plan view on to a wind power installation with
the machine housing 10 and rotor blades 11, 12. The centre of
rotation of the machine housing 10 is marked by a point 20 while
the main axis of the horizontal-axis rotor is indicated by a
central line 14.
[0027] Now, as soon as there is a deviation between the main axis
14 of the rotor and the wind direction which is indicated in this
Figure by inclinedly extending arrows, a check is made to ascertain
whether a predeterminable threshold value in respect of the
magnitude of the change in wind direction and the duration thereof
is reached or exceeded. If that is the case, the angle of incidence
of the rotor blade 11 shown at the left in the Figure is altered in
such a way that the air resistance is reduced. That results in an
imbalance of forces between the two rotor blades 11, 12 and the air
resistance, which is now higher, at the right rotor blade 12, gives
rise to a force F which acts on the machine housing 10 with a
torque in the direction of the arrow illustrated above the centre
of rotation 20. In that way the rotor is adjusted to track to the
wind without the azimuthal drive having to be switched on.
[0028] If the difference between the main axis 14 of the rotor and
the wind direction exceeds a predeterminable threshold value, an
existing azimuthal drive can be switched on to assist with the
rotary movement and to reduce the asymmetric loading. That
azimuthal drive is also required if the wind has completely died
away and, after a period when there is no wind, blows from a
different direction which excludes tracking adjustment of the rotor
by the adjustment of the angle of incidence in the above-described
manner.
[0029] It will be appreciated that, in an alternative embodiment of
the invention, it is possible, in the situation shown in FIG. 1, to
increase the air resistance of the right rotor blade 12, instead of
reducing the air resistance of the left rotor blade 11. It will be
noted that this increase in the air resistance of the right rotor
blade 12 would result in a higher level of loading on that rotor
blade 12 and would thus detrimentally affect the service life
thereof. For that reason a reduction in the air resistance of the
left rotor blade 11 and therewith a reduction in the loading on
that rotor blade 11 is to be preferred.
[0030] FIG. 2 shows a wind power installation on a platform 30
which is floating in the water and which is held in its
predetermined position for example by at least two anchor chains
32.
[0031] In this case the platform 30 is below the surface 2 of the
water while the pylon 8 of the wind power installation sticks up
out of the water and carries the machine housing 10 with the rotor
blades 12.
[0032] As long as the wind is impinging on the wind power
installation in precisely frontal relationship, a nodding moment
will occur which deflects the wind power installation rearwardly in
the perspective shown in FIG. 2. It will be noted that as soon as
the wind direction is inclined, a lateral component is also added
to the frontal component. That lateral component will cause a
laterally directed deflection, in addition to the rearwardly
directed deflection. That is manifested on the one hand in an
inclination of the surface of the platform 30 out of the horizontal
or by an inclination of the pylon 8 of the wind power installation
out of the vertical by a predetermined amount which is indicated in
the Figure by the angle .alpha. on the one hand at the pylon 8 of
the wind power installation and on the other hand at the surface of
the platform 30.
[0033] While the deflection at the surface of the platform is still
relatively slight, the deflection out of the perpendicular at the
top of the pylon 8 can already be of a clearly detectable magnitude
so that detection at the top of the pylon 8 can provide for the
embodiment of a very sensitive device for detecting a change in
wind direction and a deflection arising therefrom.
[0034] It will be appreciated that, in terms of detecting the
deflection, it is to be noted that only a deflection due to the
lateral wind component is relevant for the control action according
to the invention.
[0035] FIG. 3 shows an embodiment for the control of the wind power
installation in accordance with the invention. A device 40
ascertains the wind direction. That device 40 can be for example a
simple weather vane, for example with an incremental sender, as is
provided in any case on any wind power installation. A further
device 42 ascertains the azimuthal position. Those two devices 40,
42 communicate their measurement results or data to a control 44
which in turn evaluates the two values from the wind direction
detection device 40 and the azimuthal position detection device 42
and compares them and if necessary, on the basis of predeterminable
characteristic values, implements suitable adaptation of the angle
of incidence of the rotor blades, by way of an adjusting device
46.
[0036] In this respect it is possible to predetermine for example
three threshold values for the magnitude of the difference between
the wind direction and the azimuthal position. If the deviation
between the two values reaches the first of those threshold values
for a given period of time, the angle of incidence of a rotor blade
12 is adjusted by an adjusting device 46 by way of a control line
48, for example to a pitch motor (not shown), in a given segment of
the circle of the rotor, in such a way that the air resistance
thereof is reduced so that the machine housing 10 with the rotor is
adjusted in tracking relationship with the wind until the wind
direction and the azimuthal position are again coincident within
also predeterminable tolerance limits. The control 44 then again
provides for the setting of the rotor blades 11, 12, which is
appropriate for optimum energy output.
[0037] If in evaluation of the data the second threshold value in
respect of the deviation between azimuthal position and wind
direction occurs, the control 44 can switch on the azimuthal drive
22 for example by way of a separate control line 49 and thus
support the wind direction tracking effect. The third threshold
value can be so determined that then a wind direction tracking
action is no longer possible by virtue of the change in the angle
of incidence of a rotor blade so that here the azimuthal drive 22
is definitely required.
[0038] FIG. 4 shows an active wind direction tracking device by
means of a motor azimuthal drive. That motor drive rotates the
machine head of the wind power installation in such a way that the
rotor of the wind power installation is optimally aligned in the
direction of the wind. Such an active drive for the wind direction
tracking action can be an azimuthal drive 51 with an associated
azimuthal bearing 52. That azimuthal bearing is disposed between
the pylon head and the machine housing. One azimuthal drive is
sufficient in small wind power installations, larger wind power
installations are generally equipped with a plurality of azimuthal
drives, for example four azimuthal drives, as shown in FIG. 4. The
four drives 51 are distributed uniformly around the periphery of
the pylon head (a non-uniform distribution is also possible).
[0039] The illustrated azimuthal drives are three-phase current
asynchronous motors which are used as asynchronous drive machines.
For adjustment purposes, for active azimuthal adjustment, those
three-phase current asynchronous motors are supplied with
corresponding three-phase current, in which case they produce a
corresponding torque. After the machine housing adjustment
procedure (after it has assumed the desired azimuthal position) the
four three-phase current asynchronous motors (ASM) are switched off
and thus no longer produce any torque. In order to uniformly retard
the motors and also thereafter still to produce a braking torque,
the motors are supplied with a direct current immediately after
separation from the three-phase current network, as far as possible
immediately thereafter. That direct current produces a stationary
magnetic field in the motors which are immediately braked
therewith. The direct current supply continues as far as possible
throughout the entire stoppage time and can be regulated in respect
of amplitude.
[0040] After the adjusting operation the ASM-drives are supplied
with a regulated direct current by means of a regulating device
(see FIG. 5). Slow rotary movements of the pylon head which are
caused by asymmetrical gusts of wind are only damped by a low
direct current (about 10% of the minimum current), but are
admitted. Faster rotary movements are avoided by an adapted higher
direct current and thus a higher braking torque. In the case of
very fast rotary movements the direct current is raised to the
nominal current of the motor.
[0041] The asynchronous motor does not produce any torque with the
direct current magnetisation in the stopped condition. However with
a rising rotary speed--up to about 6% of the nominal rotary
speed--the torque produced rises linearly, symmetrically in both
directions of rotation.
[0042] It is also appropriate for the individual motors of the
azimuthal drives to be coupled by means of a current transformer.
Simple counter-coupling of the asynchronous motors stabilises the
individual drives in that respect.
[0043] If therefore--as described--azimuthal adjustment is not to
be effected by means of active supply of three-phase current to the
asynchronous motors, the direct current of the asynchronous
azimuthal drives is set to zero or is made so low that controlled
adjustment of the azimuth can still be effected by means of rotor
blade angle adjustment. In order for example to maintain a low
braking counter-moment, it may also be advantageous to limit the
direct current of the asynchronous motors to a value of between 1%
and 10% of the nominal current so that a motor braking moment is
also afforded, over and above the braking action of the plain
bearings, and that braking moment makes it possible for the
azimuthal change to be effected in the desired manner and without
excessive swing deflection.
* * * * *