THATTOI TOITOITUNUTULMUQLARINIUS 20180149132A1( 19) United States( 12 ) Patent
Application Publication (10 ) Pub. No.: US 2018 /0149132 A1
INOUE(43) Pub. Date :May 31, 2018(52 ) CPC
U .S. CI.
............. FO3B 17 /06 ( 2013.01); YO2E 10 / 727(54 ) YAWING SUPPRESSING APPARATUS OF
WIND TURBINE AND FLOATINGOFFSHORE WIND TURBINE(2013 .01); B63B 21/ 50 ( 2013 .01); B63B 39 /00(2013 .01 ); F03D 13/ 25 ( 2016 .05 ); F05B

( 71 ) Applicant: National Institute of Maritime, Port

2260/ 964 (2013. 01 ); F05B 2240 /95 ( 2013 .01) ;and Aviation Technology , Tokyo (JP )F05B 2240 /93 (2013 .01) ; F05B 2240 / 917( 2013.01) ; F05B 2240 /2213 (2013 .01) ; B63B

(72) Inventor: Shunji INOUE, Tokyo (JP )(21) Appl. No.: 15/883,003(22) Filed : Jan. 29, 2018

2039/067 ( 2013 .01); B63B 2035 /446

(2013 .01); B63B 2035/442 ( 2013 .01); YO2E
10 /28 ( 2013.01); YO2E 10 / 721 (2013 . 01 );YO2E 10 /725 ( 2013 .01 ); YO2E 10 /728

( 2013 .01 ); B63B 1/048 (2013.01)

Related U .S . Application Data
(63 ) Continuation of application No. 13/ 883,560 , filed on
Jun . 30 , 2013 , now Pat. No. 9 ,879 ,649, filed as
application No. PCT/JP2011/006177 on Nov. 4 , 2011 .

(57)

(30 )

turbine capable of suppressing yawing of a nacelle caused
by a gyro effect which is a cause of adverse influence ofForeign Application Priority Data

Nov. 5, 2010 ( JP )......... .... 2010 - 248511

B63B 1 /04
B63B 21/50
B63B 39 /00
FO3D 13 / 25

B63B 39 / 06
B63B 35 /44

The present invention provides a floating offshore wind

power generating efficiency of a wind turbine and enduranceof devices thereof. The floating offshore wind turbine 10

includes a rotor 11 which is rotated by wind , a nacelle 13 in

Publication Classification(51) Int. Ci.
F03B 17/06

ABSTRACT

which a rotation shaft 12 of the rotor 11 is accommodated ,and a tower 15 including a turning seated bearing 14 which(2006 .01)

supports the nacelle 13 such that the nacelle 13 can turn withtower is provided with yawing suppressingmeans 16 which
suppresses yawing T of the nacelle 13 . According to this, it
is possible to suppress the yawing T of the nacelle 13
generated by a gyro effect caused by yawing 22 generated in
the floating body 31 by waves of the sea surface P .

respect to a sea surface P to exert a weathercock effect. The( 2006 .01)

(2006 .01)

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May 31, 2018

US 2018/0149132 A1YAWING SUPPRESSING APPARATUS OF

WIND TURBINE AND FLOATINGOFFSHORE WIND TURBINECROSS -REFERENCE TO RELATEDAPPLICATIONS[0001 ] This application is a continuation of patent appli
cation Ser. No. 13 /883 ,560 filed on Jun . 30 , 2013 , which is
National Stage Application of International Application No .
PCT/JP2011 /006177, filed on Nov . 4 , 2011, the disclosure ofwhich is incorporated herein by reference in its entirety . The
International Application No. PCT/ JP2011/ 006177 isentitled to and claims benefit of Japanese Patent Application

No. 2010 -248511 , filed on Nov. 5 , 2010 , the disclosures ofwhich are incorporated herein by reference in their entire
ties.
TECHNICAL FIELD[0002] The present invention relates to a yawing suppress
ing apparatus of a wind turbine capable of efficiently suppressing yawing ( turning/oscillating motion ) of a nacelle inwhich a rotation shaft of a rotor is accommodated andyawing of a floating body , and the invention also relates toa floating offshore wind turbine.

BACKGROUND TECHNIQUE
10003 ] In conventional wind turbines , to change an orien
tation of a wind turbine in accordance with change in a winddirection , an active control apparatus which is combinedwith a wind direction sensor is used . For example , there isemployed a configuration that a wind turbine is turned by apower apparatus in accordance with a result ofmeasurementof the wind direction sensor, and the wind turbine is held at
a position suitable for the wind direction . To simplify asystem of the entire wind turbine , the active control appa

[0006 ] In a floating offshore wind turbine in which theactive control apparatus is omitted , a rotation shaft of a rotorof a wind turbine is supported such that the rotation shaft canfreely turn with respect to a floating body . Hence , yawing ofa nacelle is generated by gyro moment caused by a gyro
effect generated in the nacelle .
10007 ]. The present inventor found that moment caused bythis gyro effect was a cause of an adverse influence exerted

on power generating efficiency of the floating offshore windturbine and endurance of devices thereof.

[0008 ] To prevent vibration generated in a wind turbine

apparatus , it is proposed to employ various configurations( patent documents 1 to 3 ) .

[0009] Patent document 1 describes a wind turbine appa
ratus. The wind turbine apparatus includes , as an active

control apparatus of a nacelle, a whirling driving source
which whirls a platform supported on an upper end of a

tower and fixing means in a whirling direction . In this windturbine apparatus, to suppress vibration generated in thetower or the like by resonance of a blades and resonancethat a vibration suppressing apparatus is provided .

wind speed , patent document 1 describes a configuration[0010 ] In a wind turbine, to attenuate vibration action in anedge direction of blades of a rotor, patent document 2
describes a configuration that oscillation action attenuatingmeans is disposed in a nacelle .
[0011 ] In a wind turbine device , to prevent vibration frombeing transmitted to a nacelle frame through a speed increas

ing gear box and to prevent vibration from being transmitted
from the nacelle frame to the speed increasing gear box ,patent document 3 describes a configuration that a vibration
isolation damper is provided between the speed increasinggear box and the nacelle frame.
PRIOR ART DOCUMENT

ratus is omitted in some cases. When the active control
apparatus is to be omitted , a rotation shaft of a rotor of thewind turbine is supported on a horizontal plane such that therotation shaft can freely turn , and the orientation of the windturbine is changed by a weathercock effect to follow the

Patent Documents[0012 ] [ Patent Document 1] Japanese Patent Publication

No .2003 - 176774

right angles to both the direction of the moment and the[0013 ] [Patent Document 2 ] Japanese translation of PCT
International Application , Publication No.2002 -517660[0014 ] [ Patent Document 3 ] Japanese translation of PCT
International Application , Publication No.2008 -546948
SUMMARY OF THE INVENTION

rotation axis of the rotor by a so - called gyro effect. For
example , in a floating offshore wind turbine provided on a[0015 ] Problem to be Solved by the Invention

change in the wind direction .

[0004 ] In the wind turbine, the rotor receives wind androtates , thereby generating electric power. If moment in a
vertical direction is applied to a rotation axis of rotation of
the rotor, gyro moment is generated in a direction cross at

floating body which is floating in water, moment in thevertical direction is generated due to influence of waves .

Hence , gyro moment is generated in a horizontal direction
cross at right angles to the rotation axis of rotation of therotor by the gyro effect.
[0005 ] In a floating offshore wind turbine including theactive control apparatus , a nacelle is held by a floating bodyat a position matching with a wind direction . Therefore ,[0016 ] Such a conventional wind turbine has a problem ofvibration generated by rotation itself of the rotor and thelike , but there are no conventional wind turbines which

focus attention on oscillation of a nacelle generated by gyro
motion suppressing means used in the wind turbine appa
moment caused by the gyro effect. Hence , the vibration

ratuses described in these patent documents can not prevent
yawing of the nacelle and the floating body generated byaxis of the floating body is generated by gyro moment

gyro moment caused by the gyro effect when the floating
offshore wind turbine receives influence of waves .

modated . Here , since motion of waves is repetitive motion ,provide a yawing suppressing apparatus of a wind turbine
and to provide a floating offshore wind turbine capable ofrotation motion of the floating body rotating around a central
caused by the gyro effect generated in the nacelle in which
the rotation shaft of the rotor of the wind turbine is accom -the floating body moves repetitively (yawing ) together with

the nacelle .

[0017 ] Hence , it is an object of the present invention topreventing yawing of the nacelle and the floating body
generated by gyro moment caused by the gyro effect, andMay 31, 2018

US 2018/0149132 A1
capable of suppressing adverse influence on power gener

ating efficiency of the wind turbine and endurance of devices
thereof.

Means for Solving the Problem[0018 ] A first aspect of the invention provides a yawing

rotor receives wind and the wind turbine inclines ” means astate where the wind turbine is inclined by receiving wind ofa typical wind speed which is assumed at a place where thewind turbine is installed . Examples of the typicalwind speed
are an average annual wind speed and a wind speed at whichpower generating efficiency becomes maximum .

suppressing apparatus of a wind turbine comprising a rotor
which is rotated by wind ; a nacelle in which at least arotation shaft of the rotor is accommodated ; a structure bodyin shape of a tower, which is moored by a mooring method
which does not suppress rotation and yawing around a center
axis with respect to a water surface ; yawing suppressingmeans which suppresses rotation and yawing of the nacelle

Effect of the Invention[0024 ] According to the yawing suppressing apparatus of
the wind turbine of the present invention , since the yawing

suppressing means can suppress yawing caused by a gyro

effect, it is possible to suppress adverse influence by the
yawing on the power generating efficiency of the windwith respect to the water surface wherein the yawing supturbine caused and endurance of devices thereof.

which suppresses yawing induced by a gyroscopic effect,

compared with the rotor or a coning angle is given to thepressing means is a hydrodynamic damper in a blade shape,

which is faster than a rotation speed of the nacelle by aweathercock effect, by mutual interference with peripheral
fluid , and the hydrodynamic damper and an attachment
portion thereof are directly provided on a lower portion of
the structure body , and position only in water According tothis aspect, the yawing suppressing means can suppress theyawing of the nacelle caused by a gyro effect.
[0019 ] According to a second aspect of the invention , inf0025 ]. If the nacelle is provided on a windward side as

rotor, the nacelle can be turned by a so - called weathercock
effect, the rotation shaft can be made to conform to a winddirection and the front face of the rotor can be in contra

diction to the wind direction . Therefore , it is possible toenhance the power generating efficiency of the wind turbine .

Further, it is possible to suppress yawing and to reduce aload of the yawing suppressing means.

the yawing suppressing apparatus of the wind turbine of thefirst aspect, the nacelle is provided on a windward side as100261. If the hydraulic damper or the friction damper isused as the oscillating control means , resistance of theoscillating control means can be varied in accordance withnacelle can be turned with respect to a water surface or a

suppress fast yawing of the nacelle caused by a gyro effectcompared with the rotor. According to this aspect, theground surface by a so -called weathercock effect, and an

orientation of the rotation shaft can be made to conform toa wind direction .

[ 0020 ] According to a third aspect of the invention , in theyawing suppressing apparatus of the wind turbine of thesecond aspect, a coning angle is given to the rotor. Accord
ing to this aspect, it is possible to further enhance theso - called weathercock effect .
[0021 ] According to a fourth aspect of the invention , in theyawing suppressing apparatus of the wind turbine of the first
aspect, a hydraulic damper, which suppresses the yawing
induced by the gyroscopic effect , which is faster than therotation speed of the nacelle by the weathercock effect, isused as the yawing suppressing means.
[0022] According to a fifth aspect of the invention , in theyawing suppressing apparatus of the wind turbine of the first
aspect, a friction damper, which suppresses the yawing
induced by the gyroscopic effect, which is faster than therotation speed of the nacelle by the weathercock effect, isused as the yawing suppressing means. If the hydraulicdamper or the friction damper is used as the yawing suppressing means, resistance for suppressing the yawing of thenacelle can be varied in accordance with a turning speed of
the nacelle.
[0023] According to a sixth aspect of the invention , in the
floating offshore wind turbine of the seventh aspect, thenacelle is supported by the structure body such that apredetermined angle is formed between a horizontal plane

and the rotation shaft of the rotor in a state where wind is notreceived so that the rotation shaft of the rotor in a state wherewind is received becomes parallel to a wind direction .

According to this aspect, the predetermined angle can be set

while taking, into account, a fact that the wind turbine
inclines when the rotor receives wind . Therefore , whenelectricity is generated , the rotation shaft of the rotor can bemade parallel to a wind direction . Here , " a state where thea turning speed of the nacelle . Therefore , it is possible towithout suppressing slow yawing of the nacelle caused by aweathercock effect.

[0027 ] If the hydrodynamic damper which suppresses

yawing by interference with surrounding fluid is used ,resistance can be varied in accordance with a turning speedof the nacelle , the yawing generated in the nacelle or thefloating body due to the gyro effect can be suppressed ,pitching of the floating body can be suppressed , and power
generating efficiency and endurance of devices can beenhanced .
[0028 ] The floating offshore wind turbine of the invention
includes the yawing suppressing apparatus of the windturbine of the invention . Therefore , it is possible to enhance
the power generating efficiency and endurance of thedevices by suppressing the yawing of the nacelle caused by
the gyro effect. It is also possible to suppress pitching of thefloating body by reaction of the gyro effect.
10029 ]. If a predetermined angle is provided between ahorizontal plane and the rotation shaft of the rotor in a state
where the rotor does not receive wind, a side view directionof the rotation shaft of the rotor and a side view direction ofwind can be substantially parallel to each other and can bemade to substantially conform to each other when electricity
is generated . Therefore, a rotation plane of the rotor can bemade perpendicular to a wind direction substantially at rightangles , and it is possible to enhance power generating

efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS[0030 ] FIG . 1 is a schematic perspective view showing a
configuration of a floating offshore wind turbine according
to a first embodiment of the present invention ;[0031 ] FIG . 2 is a side view of essential portions showing

a structure of a yawing suppressing apparatus of a windturbine according to the first embodiment of the invention ;May 31, 2018

US 2018/0149132 A1[0032 ] FIG . 3 shows a relation between change in a winddirection on the ocean and a deflection angle of a floating

body on water caused by influence of waves, wherein (a ) isa graph showing change in a wind direction and (b ) is agraph showing change in a deflection angle ;[0033] FIG . 4A is a schematic perspective view showing
a configuration of a hydraulic damper ;[ 0034 ] FIG . 4B is a schematic front view showing a
configuration of the hydraulic damper ;[ 0035 ] FIG . 4C is a sectional view taken along a line A - A

in FIG . 4B ;100361. FIG . 5A is a schematic perspective view showing
a configuration of a friction damper;[0037 ] FIG . 5B is a schematic front view showing a

configuration of the friction damper ;10038 ] FIG . 6A is a plan view showing a configuration ofa mooring apparatus of the floating body according to thefirst embodiment of the invention ;[0039 ] FIG . 6B is a side view showing a configuration of

the mooring apparatus of the floating body according to thefirst embodiment of the invention ;[0040 ] FIG . 7 is a diagram showing a configuration of apair of mooring wires in the first embodiment of the invention ;[0041] FIG . 8A is a plan view showing a configuration ofa conventional tension mooring method ;[0042] FIG . 8B is a side view showing a configuration of
the conventional tension mooring method ;[0043] FIG . 9 is a side view of essential portions showing

a structure of a yawing suppressing apparatus of a windturbine according to a second embodiment of the invention ;[0044 ] FIG . 10A is a schematic side view showing a

configuration in a state where the yawing suppressing appa
ratus possessed by a floating offshore wind turbine accord

ing to the second embodiment of the invention receives
wind ;[0045 ] FIG . 10B is a schematic side view showing a
configuration in a state where the yawing suppressing appa
ratus possessed by the floating offshore wind turbine accord

ing to the second embodiment of the invention does notreceive wind;[0061 ] 41 structure body[0062] 42 turning means[0063] 44 , 64 hydrodynamic damper[0064 ] 51A structure body upper portion[0065 ] 51B structure body lower portion[0066 ] aa coning angle
10067 ] Bpredetermined angle

MODE FOR CARRYING OUT THE INVENTIONFirst Embodiment[0068 ] A first embodiment of the present invention will be
described below with reference to FIGS . 1 to 8 . In thisembodiment, a case where the invention is carried out as afloating offshore wind turbine will be described .

[0069 ] FIG . 1 is a schematic perspective view showing a

configuration of the floating offshore wind turbine 10
according to the first embodiment. As shown in FIG . 1 , thefloating offshore wind turbine 10 includes a floating body 31

provided with a yawing suppressing apparatus 20 . The
floating body 31 is moored to anchors 33 provided on a sea

bottom B through mooring wires 32 . A line coming out froma lower portion of the floating body 31 is an electric feeder

line 34 . A structure of the yawing suppressing apparatus 20
possessed by the floating offshore wind turbine 10 of theembodiment will be described with reference to FIG . 2 .
[0070 ] FIG . 2 is a side view of essential portions showing
a structure of the yawing suppressing apparatus 20 of thewind turbine 10 according to the first embodiment. As
shown in FIG . 2 , the yawing suppressing apparatus 20 iscomposed of a rotor 11 which is rotated by wind, a nacelle
13 in which a rotation shaft 12 of the rotor 11 is accommo
dated , a tower ( structure body ) 15 having a turning seatedbearing ( turning means ) 14 which supports the nacelle 13

such that the nacelle 13 can turn with respect to a water

surface or a ground surface , and an yawing suppressingmeans 16 which suppress yawing of the nacelle 13 withrespect to the water surface .

[0071] The rotor 11 includes a hub 17 which is radially[0046 ] FIG . 11 is a schematic perspective view showing aprovided with a plurality of blades 18, and the rotation shaft
12 connected to the hub 17 . The rotation shaft 12 is rotatably

to a third embodiment of the invention ;[0047 ] FIG . 12 is a schematic perspective view showing a
configuration of the floating offshore wind turbine according
to the third embodiment of the invention ; andsupported in the nacelle 13 . If the rotor 11 receives wind , theconfiguration of a floating offshore wind turbine according[0048 ] FIG . 13 is a schematic perspective view showing a
configuration of a floating offshore wind turbine according

to a fourth embodiment of the invention .

EXPLANATION OF SYMBOLS[0049] 10, 40 , 50 , 60 floating offshore wind turbine[0050 ] 11 rotor[ 0051] 12 rotation shaft
10052] 13 nacelle[0053 ] 14 turning seated bearing ( turning means )rotation shaft 12 rotates and a generator (not shown ) pro
vided in the nacelle 13 generates electricity . A hollow arrow
w in FIG . 2 shows a wind direction . In the yawing suppressing apparatus 20 of the embodiment, the rotor 11 isprovided on a leeward side as compared with the nacelle 13 .
According to this configuration , it is possible to effectively
generate a so - called weathercock effect in which a side view
direction of the rotation shaft 12 conforms to a winddirection by yawing of the nacelle 13 provided on theturning seated bearing 14 .
10072 ]. The rotation shaft 12 rotates upon receiving wind
W , and the rotation shaft 12 is accommodated in the nacelle
13 . The nacelle 13 also includes electricity generating means(not shown ), such as a gear box (not shown ) which increases[ 0054 ] 15 tower (structure body )100551 16 yawing suppressing means[00561 160 hydraulic dampera rotation speed of the rotation shaft 12 and transmits therotation to the generator, possessed by a wind turbine device .

[0057] 165 friction damper

provided on the tower 15 such that the nacelle 13 can turn[0058 ] 20 , 30 yawing suppressing apparatus[0059 ] 31 floating body[0060 ] 32 mooring wire

The nacelle 13 is supported by the turning seated bearing 14

in a direction parallel to a sea surface P . According to thisconfiguration , a direction of the rotation shaft 12 can bevaried by yawing of the nacelle 13 in accordance with

May 31, 2018

US 2018/0149132 A1change in a wind direction W , and a rotation plane of theblades 18 of the rotor 11 can be in contradiction to wind .

[0073] When a force in the vertical direction is applied bywaves while the rotor 11 is rotating , the yawing suppressingmeans 16 suppresses yawing of the nacelle 13 generated bya gyro effect. Attention is paid to the yawing of the nacelle
13 caused by the gyro effect, the yawing suppressing means
16 is provided . Since the yawing suppressing means 16 cansuppress the yawing of the nacelle 13, it becomes possible
to enhance power generating efficiency of the floating off
shore wind turbine 10 and to enhance endurance of devices
thereof. Although the tower 15 is provided with the yawing

suppressing means 16 in this embodiment, instead thereof ,[0081 ] Since the deflection angle caused by the influenceof waves is varied with the short period , yawing of thenacelle 13 is induced by the gyro effect. The yawing of thenacelle 13 adversely affects the power generating efficiencyof the wind turbine and endurance of the devices.
10082] To selectively suppress yawing of the nacelle 13
caused by the gyro effect while allowing the nacelle 13 toturn as a wind direction is varied , it is preferable that means
whose resistance is varied in accordance with a turning

speed of the nacelle 13 is used as the yawing suppressingmeans 16 . According to this, a so - called weathercock effectcan be exerted without generating an attenuation effect forslow yawing of the nacelle 13 supported by the turning

seated bearing 14 caused by change in a wind direction

the nacelle 13 may be provided with the yawing suppressingmeans 16 .
[0074 ] When the yawing suppressing apparatus 20 iswhich is varied while taking a relatively long time. It is

floating offshore wind turbine 10 , the nacelle 13 is supported

and thus, it is also possible to selectively inhibit yawing ofprovided on a wind turbine apparatus on land instead of theby the turning seated bearing 14 such that it can turn withrespect to a ground surface . If moment in the verticaldirection is applied for any reason , the yawing suppressingmeans 16 can suppress yawing of the nacelle 13. The
above - described weathercock effect is also of assistance in

reducing a load of the yawing suppressing means 16 .
[0075 ] Next, a mechanism for generating yawing in thenacelle 13 of the floating offshore wind turbine 10 by the

gyro effect on the ocean will be described with reference to

FIGS. 1 and 3 . If a rotating object (substance ) rotates in a
direction cross at right angles to a rotation axis , moment acts
in directions intersecting with each other at right angles .

This moment is called gyro moment. An effect for generat
ing the gyro moment is called a gyro effect.
QxL = T

[0076 ] 2 : angular velocity of pitching motion[0077 ] L : angular momentum of rotating object[0078 ] T: gyro moment[ 0079 ] When the rotor 11 is rotating motion L , if motion
generating a restoring force via yawing of the floating body
31 by waves of a sea surface P is generated , whereby apitching 2 is generated , the rotor 11 yaws in the verticaldirection cross at right angles to the rotation axis S . Accord
ing to this, gyro moment acts in the horizontal direction
cross at right angles to both the rotation axis S of the rotor
11 and the vertical direction . In the floating offshore windturbine 10 , since the nacelle 13 can turn by the turning seatedbearing 14 , yawing of the nacelle 13 is generated in a

direction shown by T in FIG . 1 by this gyro moment.
[0080 ] FIG . 3 shows a relation between change in a winddirection on the ocean and a deflection angle of the floating
body on water caused by influence of waves , wherein ( a ) isa graph showing change in a wind direction and (b ) is apossible to allow an attenuation effect to exert for yawing of

the nacelle 13 which is caused by waves with a short period ,the nacelle 13 .

[0083 ] Since the floating offshore wind turbine 10 of theembodiment can suppress the yawing of the nacelle 13 by
the yawing suppressing means 16 , it becomes possible tosuppress the adverse influence.
[0084 ] If the yawing suppressing apparatus 20 including
the yawing suppressing means 16 is used , it is possible torestrain yawing from generating in the nacelle 13 by a gyro
effect caused by pitching of the floating body 31 caused bywaves . Further, by suppressing the yawing of the nacelle 13 ,it is also possible to suppress pitching of the floating body
31 caused by reaction of the gyro effect.
[0085] FIGS. 4A to 4C schematically show a configurationof a hydraulic damper, wherein FIG . 4A is a perspective
view , FIG . 4B is a front view and FIG . 4C is a sectional view
taken along an arrow A - A in FIG . 4B . As shown in thesedrawings, the hydraulic damper 160 includes a rotation body
163 and oil 164 in its interior surrounded by a body case 161

and a cap 162. The hydraulic damper 160 utilizes a braking

force generated by viscosity resistance of the oil 164. By
adjusting a gap between the body case 161 and the rotationbody 163 , a contact area of the oil 164 and viscosity of theoil 164, it is possible to vary a braking torque (resistance )with respect to rotation of the rotation body 163. There issuch a relation between a rotation speed and a braking torqueof the rotation body 163 that if the rotation speed isincreased , the braking torque is increased , and if the rotation
speed is reduced , the braking torque is also reduced .

[0086 ] If the hydraulic damper 160 is used , since it utilizes
the viscosity resistance of oil 164 , there is a merit thatchange with time of characteristics such as wearing is small .

It is possible to reduce influence of change in viscosity

caused by a temperature by selecting a kind of oil 164, but

it is possible that when wind is strong , heat of oil 164 is lost,its viscosity is increased and the braking torque is increased

graph showing change in a deflection angle . Portions sur

by taking a constitution of cooling oil 164 by wind as anof FIG . 3 are compared with each other, it can be found thatchange in a wind direction is generated while taking a longration of a friction damper, wherein FIG . 5A is a perspective

time, and change in a deflection angle caused by influencedrawings , the friction damper 165 includes a friction material 167 which is in contact with an outer surface of arotation shaft 166 , a rotation shaft - connecting material 168

gyro effect caused due to influence of waves and so on isfast .

body 169 which pushes the rotation shaft -connecting materounded by broken lines in the graph (a ) as well as the graph(b ) show change during one hour. If the graphs (a ) and (b )ofwaves is generated in a short time. That is, a turning speedof the nacelle 13 caused by change in a wind direction isslow , and a speed of yawing of the nacelle 13 caused by aexample.
[0087 ] FIGS. 5A and 5B schematically show a configu
view and FIG . 5B is a front view . As shown in thesewhich surrounds the friction material 167 , and an elastic
rial 168 in a predetermined direction . The friction damper

May 31, 2018

US 2018/0149132 A1
165 utilizes a braking force generated by friction resistance
between the rotation shaft 166 and the friction material 167 .

the floating body 31 . The other ends of the mooring wires 32

are connected to the anchors 33 provided in water.

By adjusting friction resistance and contact areas between
the rotation shaft 166 and the friction material 167, it is[0094 ] The floating body 31 is formed into a substantially
cylindrical shape . A pair of mooring wires composed of thea relation between a rotation speed and a braking torque ofwires 32 are connected to two points on a circumference ofpossible to vary a braking torque ( resistance ). There is suchthe rotation shaft 166 that if the rotation speed is increased ,two mooring wires 32 is used . One ends of the two mooring

the braking torque is increased , and if the rotation speed isa circle of the substantially cylindrical shape when the

reduced , the braking torque is also reduced .

two mooring wires 32 are formed into substantially tangent[0088 ] When the friction damper 165 is used , there are

merits that a sealing portion is unnecessary and thus theconfiguration can be simplified , and in an environment thatan ambient temperature is largely varied , characteristics canrelatively stably be maintained . Even if a size of the friction

floating body 31 is projected onto the horizontal plane. Thelines of the circle , and the mooring wires 32 extend on thesame side . According to this, it is possible to avoid a casewhere when the yawing suppressing means 16 suppresses
yawing, a force is applied to the floating body 31 and yawing

constantly be maintained correspondingly by means of ais generated in the floating body 31.
[0095 ] FIG . 7 shows a relation between the floating bodyof the friction material 167 is varied due to friction , theanchors 33 in the plan view (projection view on horizontal

material 167 is varied due to wearing, a braking force canbiasing force of the elastic body 169. That is, even if the size
elastic body 169 biases the friction material 167 and friction

resistance between the rotation shaft 166 and the friction
material 167 can constantly be maintained .
[0089] The floating body 31 is moored to the anchors 33

provided on the sea bottom B by means of the mooring wires

32 in water by a mooring method of restraining the floating
body 31 from rotating around the center axis . Hence , rotation of the floating body 31 in water is suppressed . Thismooring method will be described later.
[0090 ] There is a floating offshore wind turbine including
an apparatus which actively controls rotation of the nacelle

to conform to a wind direction . In this facility , a wind turbine
is temporarily fixed to the floating body and held at a

position conforming to the wind direction , i.e ., a position

where a rotation plane is in contradiction to wind .
Hence , the floating body tries to rotate around a verticalrotation axis by gyro moment caused by a gyro effect of therotor of the wind turbine . Therefore , a mooring method
which suppresses rotation motion of the floating bodyaround its center axis suppresses this yawing. According tothis , it is possible to suppress the adverse influence on the

power generating efficiency of the floating offshore wind

31 and the two mooring wires 32 connected to lower rightplane ) of FIG . 6A . One ends of the twomooring wires 32 areconnected to points A and B on the circumference of thefloating body 31. The mooring wires 32 are formed into

tangent lines L1 and L2 in the points A and B .
10096 ] In this configuration, when rotation around a center
C of the floating body 31 is generated in the floating body31, one of the two mooring wires 32 extends and a tensile
force acts . When a radius of the floating body 31 is definedas r and a rotation angle of the floating body 31 is defined
as 40 , an extension amount AL of the mooring wire 32 on
the extension side in this plan view is obtained by thefollowing equation ( 1 ):AL = rxA0[0097 ] In this case, if a spring rate of the mooring wire 32
is defined as k , a tensile force T of the floating body 31 ina tangential direction is obtained by the following equation( 2 ) by Hooke's law :T = k . AL
(2)[0098 ] A torque N generated by this extension is obtainedby the following equation (3 ):turbine and endurance of the devices thereof .

[0091] However, there is another floating offshore windturbine of a method in which the apparatus which actively

controls rotation of the nacelle is omitted and a nacelle ismade to conform to a wind direction by a weathercock
effect . In such a facility , a rotation shaft of a rotor of a windturbine is supported such that the rotation shaft can freely
turn with respect to a floating body. Hence, even if yawingof the floating body is suppressed , yawing caused by a gyro
effect generated in the nacelle can not be suppressed . There
fore , in the floating offshore wind turbine 10 of this embodi
ment, the yawing suppressing means 16 is provided , thereby

suppressing the yawing generated in the nacelle 13 by the
gyro effect.
[0092] The mooring method of restraining the floating

body 31 from rotating around its rotation axis will be

described with reference to FIGS. 6A , 6B and 7 .

[0093] FIGS.6A and 6B show a configuration of a moor

( 1)

N = Tir( 3)[0099 ] If configurations of the two mooring wires 32 areas
shown in FIG . 7 , a torque which rebels against rotation canbe generated irrespective of a rotation direction . Hence ,rotation of the floating body 31 is suppressed .
[0100 ] In FIGS. 6A and 6B , the mooring wires 32 areformed into the tangent lines L1 and L2 in FIG . 7 . However ,it is apparent that even if the mooring wires 32 are formed
into L3 and L4 ( broken lines ) in FIG . 7 , the same effect canbe exerted .

[0101] FIGS. 8A and 8B show a configuration of a con

ventional simple tension mooring method . It is apparent that
motion (floating motion ) of the floating body 31 in thehorizontal direction is suppressed by mooring wires 32

which radially extend in three directions shown in FIGS. 8 .

However, in the plan view (FIG . 8A ), since an angle formed
between a rotation direction (circumferential direction ) of
the floating body 31 and the mooring wire 32 is substantiallying apparatus of the floating body according to the first
embodiment, wherein FIG . 6A is a plan view and FIG . 6B
is a side view . Here , in FIG . 6A , the mooring apparatus ofmooring method shown in FIGS . 8A and 8B does notends of the plurality of mooring wires 32 are connected toaxis .

the floating body is projected onto a horizontal plane . One

90°, it is difficult to suppress the rotation . Hence , thesuppress rotation of the floating body 31 around its centerMay 31, 2018

US 2018/0149132 A1Second Embodiment[0102] A second embodiment of the invention will be

described below with reference to FIG . 9 . A yawing suppressing apparatus of a wind turbine of the second embodi

ment is different from the yawing suppressing apparatus of
the first embodiment in a configuration where a coning angle
is given to a rotor. The same numbers are allocated to themembers described in the first embodiment, and explanation

thereof will be omitted in the second embodiment.

[0103] FIG . 9 is a side view of essential portions showing
a structure of the yawing suppressing apparatus 30 of thewind turbine according to the second embodiment. As
shown in FIG . 9 , according to the yawing suppressing
apparatus 30 of the embodiment, a nacelle 13 is provided ona windward side as compared with a rotor 11 . A coning angle
a is given to the rotor 11. Here , the coning angle a is anangle between a straight line which connects a connected
portion 18A of a blade 18 with respect to a hub 17 and a tip
end 18B and which is shown by an alternate long and shortmined angle ß becomes the optimal angle in accordance witha wind speed may be provided .
[0108 ] The configuration described with reference to
FIGS. 10A and 10B can also be used in the floating offshore
wind turbine using the yawing suppressing apparatus 20
described in the first embodiment.

Third Embodiment[0109 ] A third embodiment of the invention will be

described below with reference to FIGS. 11 and 12 . In thethird embodiment, a case where the invention is carried out

as a floating offshore wind turbine will be described . The

same numbers are allocated to themembers described in thefirst or second embodiment, and explanation thereof will beomitted in the third embodiment.
[0110 ] FIG . 11 is a schematic perspective view showing a
configuration of a floating offshore wind turbine 40 accord
ing to the third embodiment. As shown in FIG . 11 , thefloating offshore wind turbine 40 is configured such that adash line and a vertical line V shown by an alternate long
[0104 ] According to this configuration , the nacelle 13

nacelle 13 and a structure body 41 are integrally formed
together so that the nacelle 13 does not turn with respect tothe structure body 41. The structure body 41 floats on water,a state where the nacelle 13 can freely turn in the horizontal

anchors 43 provided on a sea bottom B through turningand short dash line in the drawing .

supported by a turning seated bearing 14 is automaticallyturned in accordance with change of a wind direction W in

direction , and a weathercock effect for conforming a rotation
shaft 12 of a rotor 11 to the wind direction can be enhanced .
When an axial direction of the rotation shaft 12 and a winddirection conform to each other , a rotation plane of the rotor

11 , i.e., a plane formed by a locus of the tip end 18B of theblade 18 is perpendicular to the wind direction substantiallyat right angles . If the weathercock effect is enhanced , a loadof yawing suppressing means 16 is further reduced .

[ 0105 ] When the present invention is carried out as thefloating offshore wind turbine ( see FIG . 1 ) including theyawing suppressing apparatus 30 , it is preferable to employ
such a configuration that the rotation shaft 12 of the rotor 11

in an electricity generating state where the rotation shaft 12

receives wind and inclines is located on a horizontal plane

H . This configuration will be described with reference to[0106 ] FIGS. 10A and 10B schematically show a configu

FIGS. 10A and 10B .

ration of the yawing suppressing apparatus 30 provided in

the floating offshore wind turbine of the embodiment,

wherein FIG . 10A is a side view in a state where wind isreceived and FIG . 10B is a side view in a state where wind

is not received . As shown in FIG . 10A , according to theyawing suppressing apparatus 30 of the embodiment, theby S ) of the rotor 11 in the electricity generating state where
the rotation shaft 12 receives wind and inclines is located on
the horizontal plane H . According to this , a direction of therotation axis of the rotation shaft 12 can conform to the windrotation shaft 12 (straight line in the axial direction is shown

direction W (both of them can be parallel to each other ).
Hence , in the state where wind is not received as shown in
FIG . 10B , the nacelle 13 is supported by a tower 15 such thatthe rotation shaft 12 ( straight line S ) of the rotor 11 forms apredetermined angle ß with respect to the horizontal planeH.

[ 0107 ] The predetermined angle ß may be set based on themost general wind speed so that power generating efficiencyof the floating offshore wind turbine becomes excellent.
Further, controlmeans of the predetermined angle B which
varies the predetermined angle ß such that the predeter

the nacelle 13 is fixed to an upper end of the structure body

41 , and a lower end of the structure body 41 is connected tomeans 42 . The turning means 42 is for connecting thestructure body 41 to the anchors 43 such that the structure

body 41 can turn in accordance with change in the winddirection W , and the turning means 42 makes the structure
body 41 exert a weathercock effect.

[0111 ] Hydrodynamic dampers 44 are provided on anouter side of the structure body 41. The structure body 41 ismoored by a mooring method which does not suppress
rotation of the structure body 41 around its center axis. By

locating the hydrodynamic dampers 44 in water , a function
as yawing suppressing means can be exerted . That is ,resistance of each of the hydrodynamic dampers 44 having

a blade shape against water becomes smaller with respect towith respect to fast yawing . Hence, it is possible to selec

slow yawing of the structure body 41 and becomes greater

tively attenuate and suppress the yawing of the structure

body 41 caused by a gyro effect which is fast yawing. By

providing the structure body 41 with the hydrodynamicof the structure body 41 caused by a gyro effect . To suppress
dampers 44 in this manner, it is possible to suppress yawing
yawing of the structure body 41, the structure body 41 may

be provided with the hydraulic damper 160 ( see FIGS. 4A
to 4C ) or the friction damper 165 (see FIGS. 5A and 5B ). It
is also possible to moor the structure body 41 also using

another mooring method which does not suppress rotation of
the structure body 41 around its center axis by means ofmooring wires .
[0112 ] Although the hydrodynamic dampers 44 areapplied to the floating offshore wind turbine in the third
embodiment, it is also possible to apply the hydrodynamic
dampers 44 to a wind turbine installed on the ground forexample . In this case , turning means is supported in a state

where the structure body floats in water in a pool such thatthe structure body can turn with respect to a ground surface ,and the water in the pool provided in a periphery and thehydrodynamic dampers 44 are made to mutually interfere .
According to this, the hydrodynamic dampers 44 can exert
function as yawing suppressing means also in the windturbine installed on the ground .

May 31, 2018

US 2018/0149132 A1[0113 ] FIG . 12 is a schematic perspective view showing a

configuration of a floating offshore wind turbine 50 having

portions of the two hydrodynamic dampers 64 to the floating

body 31 passes a substantially center of a cross section

a configuration different from that of the floating offshore

which is parallel to a horizontal plane of the floating bodywind turbine 40 according to the third embodiment. As
shown in FIG . 12 , in the floating offshore wind turbine 50 ,an upper portion 51A of a structure body 51 and the nacelle
13 are integrally formed together, and the turning means 42

provided not for suppressing pitching of the floating body 31
but for suppressing yawing of the floating body 31. That is ,the hydrodynamic dampers 64 of the floating offshore windis provided between the structure body upper portion 51A
and a structure body lower portion 51B . The structure body

31. This is because that the hydrodynamic dampers 64 areturbine 60 are provided so that the hydrodynamic dampers

is fixed to the anchors 43 on the sea bottom B through a

64 interfere with outside water and become resistance ofyawing of the floating body 31 . Therefore , it is unnecessary
to provide three or more hydrodynamic dampers 64 unlike[0114 ] According to this configuration , since the structure

suppressing the pitching . Hence , even if the number oflower portion 51B located lower than the turning means 42
plurality of mooring wires 54 .

body upper portion 51A can turn in accordance with changeof the wind direction W by the turning means 42 , it ispossible to exert a weathercock effect. The yawing suppress

ingmeans 16 provided in the structure body 51 can suppress
yawing of the nacelle 13 by a gyro effect . It is also possible

to moor the structure body upper portion 51A also using
another mooring method which does not suppress rotation
around a center axis by means of mooring wires.

a case where the hydrodynamic dampers 64 are provided forhydrodynamic dampers 64 is one , the same function isexerted . However, since the same function is exerted eve if
the number of the hydrodynamic dampers 64 is three or

more, the number of the hydrodynamic dampers 64 may bethree or more .
[0119 ] In the fourth embodiment, even if an apparatus
which actively controls rotation of the nacelle is provided
instead of the yawing suppressing means 16 , it is possible torestrain the floating body 31 from generating yawing by the

Fourth Embodiment[0115] A fourth embodiment of the invention will behydrodynamic dampers 64 . The hydrodynamic dampers 64

embodiment, a configuration in which a floating offshoremeans. Hence, a shape of a cross section of the structure

described below with reference to FIG . 13 . In the fourthwind turbine is moored by a mooring method that does not

suppress rotation of a floating body around its center axis

generate a hydrodynamic effect by interference with surrounding fluid and exert a function as yawing suppressing
body itselfmay be an angular shape or a shape having many
concavo - convex portions.

will be described . The same numbers are allocated to theIndustrial Applicability

explanation thereof will be omitted in the fourth embodi
ment .

ratus for enhancing power generating efficiency of a windmembers described in the first to third embodiments, and[0120 ] The present invention can be utilized as an appa

to the fourth embodiment. As shown in FIG . 13 , a floating

turbine and endurance of devices thereof. Especially , theinvention is useful for enhancing power generating effi
ciency of a floating offshore wind turbine and endurance ofbody 31 of a floating offshore wind turbine 60 of the fourth

devices thereof.

embodiment is moored to a sea bottom B by mooring wires
32 by means of a so - called catenary method. Therefore , thefloating body 31 can yawing around its center axis to someextent. That is , the floating body 31 is moored by a mooring

comprising:a rotor which is rotated by wind ;[0116 ] FIG . 13 is a schematic perspective view showing a
configuration of a floating offshore wind turbine according

method not suppressing rotation around its center axis .
Hence, even if the yawing suppressing means 16 constrains

yawing of a nacelle 13 with respect to the floating body 31

generated by a gyro effect, the floating body 31 can yawing
around its center axis to some extent. As a result, themooring wires 32 can not suppress the yawing of the nacelle

13. However , the floating body 31 of the floating offshore

wind turbine 60 is provided with a plurality of blade -shapedhydrodynamic dampers 64. The hydrodynamic dampers 64

can restrain the floating body 31 from generating the yaw[0117 ] When the floating offshore wind turbine is mooreding .

by the mooring method which does not suppress rotation of
the floating body around its center axis , if the yawing
suppressing means 16 which is for suppressing yawing of
the nacelle 13 in the turning seated bearing 14 and thehydrodynamic dampers 64 which are for suppressing yaw

ing of the floating body 31 are combined with each other, it

is effective for suppressing yawing of the nacelle 13 and thefloating body 31 caused by a gyro effect.
[0118 ] In the floating offshore wind turbine 60 of the
fourth embodiment, the two hydrodynamic dampers 64 aredisposed such that they are opposed to each other throughthe floating body 31. That is, a line connecting mounted

1. A yawing suppressing apparatus of a wind turbine

a nacelle in which at least a rotation shaft of the rotor isaccommodated ;a structure body in shape of a tower, which is moored bya mooring method which does not suppress rotation andyawing around a center axis with respect to a water
surface ;yawing suppressingmeans which suppresses rotation andyawing of the nacelle with respect to the water surface
wherein the yawing suppressing means is a hydrodynamic
damper in a blade shape, which suppresses yawing
induced by a gyroscopic effect, which is faster than arotation speed of the nacelle by a weathercock effect,

by mutual interference with peripheral fluid , andthe hydrodynamic damper and an attachment portion
thereof are directly provided on a lower portion of thestructure body, and position only in water.
2 . The yawing suppressing apparatus of the wind turbine
according to claim 1 wherein the nacelle is provided on awindward side as compared with the rotor.
3 . The yawing suppressing apparatus of the wind turbine
according to claim 2 , wherein a coning angle is given to therotor.
4 . The yawing suppressing apparatus of the wind turbine

according to claim 1 , wherein a hydraulic damper, which
suppresses the yawing induced by the gyroscopic effect,

May 31, 2018

US 2018/0149132 A1
which is faster than the rotation speed of the nacelle by theweathercock effect, is used as the yawing suppressingmeans.
5. The yawing suppressing apparatus of the wind turbine
according to claim 1 , wherein a friction damper, which
suppresses the yawing induced by the gyroscopic effect,
which is faster than the rotation speed of the nacelle by theweathercock effect, is used as the yawing suppressingmeans.

6 . (canceled)
7 . (canceled )8 . (canceled )9 . (canceled )10 . The floating offshore wind turbine according to claim

1 , wherein the nacelle is supported by the structure bodysuch that a predetermined angle is formed between a horizontal plane and the rotation shaft of the rotor in a state
where wind is not received so that the rotation shaft of therotor in a state where wind is received becomes parallel toa wind direction .
****