THU TTUMTUNTUK

US009879649B2(12) United States Patent( 10) Patent No.: US 9,879,649 B2(45) Date of Patent:
Jan . 30 , 2018

Inoue(54) FLOATING OFFSHORE WIND TURBINE( 75 ) Inventor: Shunji Inoue, Tokyo (JP )(73 ) Assignee: NATIONAL INSTITUTE OF(56 )References Cited
U .S . PATENT DOCUMENTS
7,296 ,971 B2 * 11/2007 Borgen ................... FO3D 11/04

416 /85

MARITIME, PORT AND AVIATION( * ) Notice:( 21) Appl. No .:13/883 ,560

(22) PCT Filed:

Nov . 4 , 2011

FOREIGN PATENT DOCUMENTS
EP

1617076 AL

2080899 AL

1 /2006

7 /2009(Continued )OTHER PUBLICATIONSInternational Search Report for PCT/JP2011/006177 , dated Feb . 7 ,2012.
(Continued )Primary Examiner — Justin Seabe

Prior Publication Data
US 2013/0272846 A1 Oct. 17 , 2013( 30 )

290 / 42(Continued )EP(86 ) PCT No.:
PCT/ JP2011 /006177$ 371 (c )( 1),( 2 ), ( 4 ) Date : Jun . 30 , 2013(87 ) PCT Pub . No .: WO2012 /060108
PCT Pub. Date :May 10 , 2012
(65 )7,612,462 B2 * 11/2009 Viterna ............. ..... B63B 21/50

TECHNOLOGY, Tokyo ( JP )Subject to any disclaimer, the term of thispatent is extended or adjusted under 35
U .S .C . 154 (b ) by 618 days .

Foreign Application Priority Data

Nov. 5 , 2010 (JP ) .......... ................. 2010 -248511(51) Int. CI.
F03B 17 /06( 2006 .01)
FO3D 13 / 25
( 2016 .01)
(Continued )(52 ) U .S . CI.

CPC .... . .... FO3B 17 / 06 ( 2013 .01) ; B63B 1/048( 2013 .01 ); B63B 21 /50 ( 2013 .01); B63B 39/ 00(2013 .01);(Continued )(58 ) Field of Classification Search
CPC ...... B63B 2035 /4433; B63B 2035/ 446 ; B63B
21/ 50 ; B63B 21/ 502 ; B63B 2021/504;

ABSTRACT(57 )The present invention provides a floating offshore windturbine capable of suppressing yawing of a nacelle caused
by a gyro effect which is a cause of adverse influence ofpower generating efficiency of a wind turbine and enduranceof devices thereof. The floating offshore wind turbine
includes a rotor which is rotated by wind, a nacelle in which

a rotation shaft of the rotor is accommodated , and a towerincluding a turning seated bearing which supports thenacelle such that the nacelle can turn with respect to a sea
surface to exert a weathercock effect. The tower is provided
with yawing suppressing means which suppresses yawing of
the nacelle . According to this , it is possible to suppress theyawing of the nacelle generated by a gyro effect caused byyawing generated in the floating body by waves of the sea
surface .

5 Claims, 18 Drawing Sheets(Continued )

$

12

13

--

-- 1414
15

ap
L64

-

H
8

33

32

33

US 9,879,649 B2
Page 2
8 ,641, 369 B2 * 2 /2014 Rodriguez(51) Int. Ci.

B63B 21/50( 2006 .01)
(2006 .01)

B63B 39 /00( 2006 .01)

B63B 1/04

B63B 35/44(2006 .01)

B63B 39 / 06

( 2006 .01)

Tsouroukdissian ....... FO3D 7 /02
415 / 119
2004/ 0253093 Al 12/ 2004 Shibata et al.
2008/ 0084068 A14 / 2008 Shibata et al.
2009 / 0092449 AL

415 / 2 . 1(52 ) U .S . CI.
CPC ........ F030 13 /25 (2016 . 05 ) ; B633 2035 /442

FOREIGN PATENT DOCUMENTS(2013 .01 ); B63B 2035 /446 (2013 .01 ); B63B

2039 / 067 ( 2013.01) ; F05B 2240/ 2213

(2013 . 01 ); F05B 2240 /917 ( 2013 .01); F05B

2240 / 93 ( 2013 .01) ; F05B 2240 / 95 ( 2013 .01) ;e
se

F05B 2260 / 964 (2013 .01 ) ; YO2E 10 /28(2013 .01 ); YO2E 10 /721 ( 2013 .01); YO2E

10 / 725 ( 2013.01 ); YO2E 10 / 727 ( 2013.01) ;YO2E 10 /728 (2013 .01)

(58 ) Field of Classification Search
CPC ... FO3D 13 /25; YO2E 10 /727 ; F05B 2240 / 95 ;F05B 2240 / 917 ; F05B 2240/ 93 ; F05B
2260/ 96

See application file for complete search history .
(56 )References Cited

U .S . PATENT DOCUMENTS

7,686,543 B2 * 3/2010 They ..

4 /2009 Sveen

2009 /0142178 A1 * 6 /2009 Nieuwenhuizen .... E04H 12 /085

B63B 21 / 50

114 / 264

8, 192, 160 B2 * 6 /2012 Garcia Lopez ......... FO3D 11/04
416 / 1

8 ,471,396 B2 * 6 / 2013 Roddier .............. B63B 35 / 44
290 / 44

JP

WO

Wo

WO

WO
WO
WO

2002 -517660 A
2003 - 176774 A
2005 -526213 A1
2007 - 146858 A

6 /2002
6 /20039 / 2005
6 / 20072007 - 198167 A

8 /20072008 - 540902 A
2008 -546948 A

11/2008
12 /2008

2009 -248792 A

10 / 20092010 -014105 A

1 / 2010

2010 -216273 A

9 /20101999 /63219 AL

12 / 1999

2003 /098038 AL
2006 / 121337 AL

11/2003
11/2006

2007/ 119953 A1

10 /2007

WO 2009131826 A2 * 10 / 2009

. . .. . .

WO 2010048560 A2 * 4 /2010.....

B63B 35 / 44

B63B 35 / 44

OTHER PUBLICATIONSThe Extended European Search Report for EP Application No.
11837762. 1, dated Dec . 2 , 2014 .
11837762.1 , dated Aug. 8 , 2016 .
* cited by examiner

European Patent Office , Office Action for EP Patent Application No .

U .S . Patent

Jan . 30 , 2018

US 9 ,879,649 B2

Sheet 1 of 18

FIG . 1

20131
what

#
*
*
*
*

*
*

14

Food

Le

????

Q --

w

w

wwwwwwww

33

30
32

33

U . S . Patent

Jan . 30, 2018

US 9 ,879,649 B2

Sheet 2 of 18

FIG . 2
.MNJADI

.
www

*

*

*

sew w
*
*

intima** * ***???
???????????
:

13

w

P
*

.

*

*
*

.Wiegen

1

WAK.TUOHESSHSuCRnOLA

*

*

*

*

*

*

*

*

*

*

*

W
.

*

*

ARHTM

*
RARE

*

*

*

*

Tani

w
ww

.

namanyaU . S . Patent

Jan . 30, 2018

US 9 ,879,649 B2

Sheet 3 of 18

FIG . 3

Wind
d(
™
)
irection* WANAWAKOMATSUMOASAKAAMUK

KWA

SANA

KAV

** * ** * * * * SEMAKOMOSOM*emrin

o mesmo tempo em ministrului roman to urinary insula

comoeariciado??????-????????????????r????????????- ????????????? ??????? , MANGA??????
13

.
2

##

RA
Time (time
)
*

A

@
*

thw
S

t.

X

X

X

Brancacekonse

TT * XXXWA * * *Elenistosowa**** * **

MAMA MWAX

WANAW

moksloir

sharma
n
t
r
a
s
i
e
s
ebuy
)
.
(

rsavilmiste

.

e

MU

estilostrihen MARK psoratnioeait SXSWAT mintnimgautringdon*loscnaelsmkoenciseacnos
aklos
de
* **

*

* ** *

pada aopin e*XC92Akishte???????????????????e u8ue >oro?????ro?????

c

bina
wake

**

**

Time (second )finevmeintionrenidernier

WANV** * * * * *

**

** *

U . S . PatentJan. 30, 2018

FIG . 4A
160 0
As

0

Sheet 4 of 18

US 9 ,879 , 649 B2

--- --- --U . S . Patent

Jan . 30, 2018

Sheet 5 of 18

US 9 ,879,649 B2

FIG . 4BURSA

WRX AWT

wzeciw???

12XAT A KIT* *- - *Art 0 - - - - 0 - -----X

wa

F

PART

2

ERE

I was

Rp
can

& XV W X2* 7WANU . S . PatentJan. 30 , 2018

US 9 ,879 , 649 B2

Sheet 6 of 18

FIG . 4c.
-

160 ---------- - 02.

heet

103 -

Kore
+++--

LINED

164

LAArt weremeth

4AAAAAAA- itarFairst re

-----

to

CN - -,4---9,8,6++,.

U . S . Patent

Jan . 30 , 2018

US 9 ,879 ,649 B2

Sheet 7 of 18

FIG . 5A

165
167

of the

166

168

169

U . S . Patent

Jan . 30, 2018

US 9 ,879,649 B2

Sheet 8 of 18

FIG . 5B

165

167
#

Www

166
www

h

tt

F

168

169

pe worethan

MA

*
*

R

*

*

*

*

*AERBTSAR

*

it

*

*

*

*

*

ww

w

*
*

w

tym
i

th

MATHRIMAA

U . S . Patent

Jan . 30, 2018

Sheet 9 of 18

FIG . 6A

KOX hotely
4

US 9 ,879,649 B2

U . S . Patent

Jan . 30 , 2018

US 9 ,879 ,649 B2

Sheet 10 of 18

FIG . 6B

Voorwaar

YA-A9240

nou

Kamwona 20
erown 3132

U . S . Patent

Jan . 30 , 2018

US 9,879 ,649 B2

Sheet 11 of 18

FIG . 7

$w
e

wat
**44

oor
**
*
*
*

*
*

WHATSAvetene to*have theopen
are notthe

0 3232
phones***1

L2

U . S . Patent

Jan . 30 , 2018

Sheet 12 of 18

FIG . 8A
PRIOR ART

3132
33
FIG . 8B
PRIOR ART

nn

.
.

33

US 9 ,879,649 B2

U . S . Patent

Jan . 30, 2018

US 9,879 ,649 B2

Sheet 13 of 18

FIG . 9
em

L
-

ww y

w

ni
w

w

of
ter
s
w

samosama

w

w

w

2

www
w

.

W

www
ww

tre

s

ARR

* * *
*

*

* * **ww w

ht wwwnet
* 19

.

XX

SAretage

w

wwww

-

-

N

ikit
*
*

*
*

tehnic***,montArems niru ient

18
18A

11
*

U . S . Patent

Jan . 30, 2018

US 9,879 ,649 B2

Sheet 14 of 18

FIG . 10A
12 13
*
*
**
*
*
W

-

> --15wwwwwwwww

sammenm** *...--H(S)WW

WW

U . S . Patent

Jan . 30, 2018

US 9,879 ,649 B2

Sheet 15 of 18

FIG . 10B
*

12 13

yos
O

Art * *
ander

YWCA
15

K

WALA
*
WX

VW
-

+
-

U . S . Patent

Jan . 30 , 2018

Sheet 16 of 18

US 9 ,879,649 B2

FIG . 11

13

44

Loremen 44" 42

MAKRNWUU . S . Patent

Jan . 30 , 2018

US 9 ,879,649 B2

Sheet 17 of 18

FIG . 12

w

*

54 43

54

43

* ***

U .S . Patent

Jan . 30 , 2018

US 9 ,879,649 B2

Sheet 18 of 18

FIG . 13

2

&

3 11

Ý

---

15

64

F

-

33

32

33

US 9 ,879,649 B2
FLOATING OFFSHORE WIND TURBINE

patent document 1 describes a configuration that a vibration
suppressing apparatus is provided .

TECHNICAL FIELD

In a wind turbine , to attenuate vibration action in an edge

direction of blades of a rotor, patent document 2 describes a
The present invention relates to a floating offshore wind 5 configuration that oscillation action attenuating means isturbine capable of efficiently suppressing yawing (turning disposed in a nacelle .
oscillating motion ) of a nacelle in which a rotation shaft of
In a wind turbine device, to prevent vibration from being
a rotor is accommodated and yawing of a floating body .
transmitted to a nacelle frame through a speed increasinggear box and to prevent vibration from being transmitted
BACKGROUND TECHNIQUE
from the nacelle frame to the speed increasing gear box,
In conventional wind turbines , to change an orientation ofpatent document 3 describes a configuration that a vibration
isolation damper is provided between the speed increasing

a wind turbine in accordance with change in a wind direc - gear box and the nacelle frame.
tion , an active control apparatus which is combined with a ,PRIOR ART DOCUMENT
wind direction sensor is used . For example, there isemployed a configuration that a wind turbine is turned by a
Patent Document
power apparatus in accordance with a result ofmeasurementof the wind direction sensor, and the wind turbine is held at [Patent Document 1 ] Japanese Patent Publication No. 2003
a position suitable for the wind direction . To simplify a 20774

system of the entire wind turbine, the active control appa
ratus is omitted in some cases. When the active control[Patent Document 2 Japanese translation of PCT Interna

apparatus is to be omitted, a rotation shaft of a rotor of the[Patent Document 3 ]Japanese translation of PCT Interna
tional Application, Publication No. 2008 -546948

wind turbine is supported on a horizontal plane such that therotation shaft can freely turn , and the orientation of the wind 25

turbine is changed by a weathercock effect to follow thetional Application , Publication No. 2002-517660
SUMMARY OF THE INVENTION

change in the wind direction .
In the wind turbine, the rotor receives wind and rotates ,Problem to be Solved by the Invention
thereby generating electric power. If moment in a verticaldirection is applied to a rotation axis of rotation of the rotor, 30 Such a conventional wind turbine has a problem ofgyro moment is generated in a direction cross at right angles
vibration generated by rotation itself of the rotor and theto both the direction of the moment and the rotation axis of

the rotor by a so -called gyro effect. For example , in alike , but there are no conventional wind turbines which

focus attention on oscillation of a nacelle generated by gyro

floating offshore wind turbine provided on a floating body moment caused by the gyro effect. Hence, the vibration
which is floating in water,moment in the vertical direction 35 motion suppressing means used in the wind turbine appa
is generated due to influence of waves . Hence , gyro moment ratuses described in these patent documents can not prevent
is generated in a horizontal direction cross at right angles to yawing of the nacelle and the floating body generated by
the rotation axis of rotation of the rotor by the gyro effect. gyro moment caused by the gyro effect when the floating
In a floating offshore wind turbine including the active offshore wind turbine receives influence of waves.
control apparatus, a nacelle is held by a floating body at a 40 Hence , it is an object of the present invention to provide
position matching with a wind direction . Therefore, rotationa floating offshore wind turbine capable of preventing yaw

motion of the floating body rotating around a central axis of

ing of the nacelle and the floating body generated by gyro

moves repetitively (yawing ) together with the nacelle .

Means for Solving the Problem

the floating body is generated by gyro moment caused by the moment caused by the gyro effect, and capable of suppress
gyro effect generated in the nacelle in which the rotation
ing adverse influence on power generating efficiency of the
shaft of the rotor of the wind turbine is accommodated .Here , 45 wind turbine and endurance of devices thereof .
since motion of waves is repetitive motion , the floating body

In a floating offshore wind turbine in which the active

control apparatus is omitted , a rotation shaft of a rotor of a
A first aspect of the invention provides a floating offshore
wind turbine is supported such that the rotation shaft can 50 wind turbine which generates electricity using a floating
freely turn with respect to a floating body.Hence , yawing of body as a portion of a structure body on ocean comprisinga nacelle is generated by gyro moment caused by a gyro
effect generated in the nacelle .
The present inventor found that moment caused by thisa rotor which is rotated by wind, a nacelle in which at least
body including turning means which supports the nacellea rotation shaft of the rotor is accommodated , the structure

gyro effect was a cause of an adverse influence exerted on 55 such that the nacelle can turn with respect to a water surface ,power generating efficiency of the floating offshore windturbine and endurance of devices thereof.

To prevent vibration generated in a wind turbine appara -and yawing suppressing means which suppresses yawing of
the nacelle with respect to the water surface and using ahydrodynamic damper which suppresses yawing by mutual

tus, it is proposed to employ various configurations (patent interference between a shape or a structure of the structure
60 body and peripheral fluid as the yawing suppressing means.
documents 1 to 3 ).
Patent document 1 describes a wind turbine apparatus. According to this aspect, the yawing suppressingmeans can

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 andsuppress the yawing of the nacelle caused by a gyro effect.
Also , the yawing suppressing means can suppress yawing of
the nacelle which is induced by the gyro effect caused by

fixing means in a whirling direction . In this wind turbine 65 pitching of the floating body on the ocean . According to thestructure using this hydrodynamic damper , resistance tolike by resonance of a blades and resonance wind speed , yawing is varied by resistance to water of the underwater

apparatus, to suppress vibration generated in the tower or theUS 9,879 ,649 B2hydrodynamic damper in accordance with a turning speed of
the nacelle or the floating body, and it is possible to suppress
the yawing.
According to a second aspect of the invention , in thewith the rotor or a coning angle is given to the rotor, thenacelle can be turned by a so -called weathercock effect, theIf the nacelle is provided on a windward side as compared

respect to a water surface by a so -called weathercock effect,
and an orientation of the rotation shaft can be made tois possible to suppress yawing and to reduce a load of therotation shaft can be made to conform to a wind direction

floating offshore wind turbine of the first aspect, the nacelle 5 and the front face of the rotor can be in contradiction to theis provided on a windward side as compared with the rotor. wind direction . Therefore , it is possible to enhance theAccording to this aspect, the nacelle can be turned with power generating efficiency of the wind turbine. Further, itconform to a wind direction .

10
10

yawing suppressing means.

If the hydraulic damper or the friction damper is used as
According to a third aspect of the invention , in the floating the oscillating control means, resistance of the oscillating
offshore wind turbine of the second aspect, a coning angle
control means can be varied in accordance with a turning
is given to the rotor. According to this aspect, it is possible speedof the nacelle. Therefore, it is possible to suppress fast
to further enhance the so - called weathercock effect .
15
yawingAccording to a fourth aspect of the invention , in the 15 yan of the nacelle caused by a gyro effect without
floating offshore wind turbine of the first aspect, a hydraulic suppressing slow yawing of the nacelle caused by a weath
effect.
damper is further provided as the yawing suppressing eercock
If the hydrodynamic damper which suppresses yawing bymeans .
According to a fifth aspect of the invention , in the floating interference with surrounding fluid is used, resistance can beoffshore wind turbine of the first aspect, a friction damper is 20 varied in accordance with a turning speed of the nacelle , thefurther provided as the yawing suppressing means . If theyawing generated in the nacelle or the floating body due tohydraulic damper or the friction damper is used as theyawing suppressing means, resistance for suppressing thethe gyro effect can be suppressed , pitching of the floating
body can be suppressed , and power generating efficiency

yawing of the nacelle can be varied in accordance with aand endurance of devices can be enhanced
turning speed of the nacelle .
25 The floating offshore wind turbine of the invention
According to an eighth aspect of the invention , in the

includes the yawing suppressing apparatus . Therefore, it isfloating offshore wind turbine of the first aspect , the floating

possible to enhance the power generating efficiency andbody is moored by mooring lines.

According to a ninth aspect of the invention , in theendurance of the devices by suppressing the yawing of thenacelle caused by the gyro effect. It is also possible tofloating offshore wind turbine of the eighth aspect, the 30 suppress pitching of the floating body by reaction of the gyro
floating body is formed into a substantially cylindricaleffect.
shape , a pair of mooring lines composed of two mooring
If the floating body is moored by amooring method whichlines whose one ends are connected to two points on a
suppresses rotation motion of the floating body around its
circumference of a circle of the substantially cylindrical center axis , it is possible to effectively suppress yawing ofshape when the floating body is projected onto a horizontal 35 the nacelle and pitching of the floating body caused by aplane is used as the mooring method , and the two mooringlines are formed into substantially tangent lines of the circle
and extend on the same side. According to these aspects, itgyro effect, and it is possible to enhance power generating
efficiency and endurance of the devices .

If a predetermined angle is provided between a horizontal

is possible to suppress rotation around a cylindrical center plane and the rotation shaft of the rotor in a state where the
40 rotor does not receive wind , a side view direction of theaxis of the floating body .
According to a tenth aspect of the invention , in therotation shaft of the rotor and a side view direction of wind

floating offshore wind turbine of the first aspect, the nacellecan be substantially parallel to each other and can be madeis supported by the structure body such that a predetermined

to substantially conform to each other when electricity isangle is formed between a horizontal plane and the rotation

generated . Therefore , a rotation plane of the rotor can be

shaft of the rotor in a state where wind is not received so that 45 made perpendicular to a wind direction substantially at rightthe rotation shaft of the rotor in a state where wind isangles , and it is possible to enhance power generatingreceived becomes parallel to a wind direction . According toefficiency .
this aspect, the predetermined angle can be set while taking ,BRIEF DESCRIPTION OF THE DRAWINGS
into account, a fact that the wind turbine inclines when therotor receives wind . Therefore , when electricity is gener - 50
ated , the rotation shaft of the rotor can be made parallel to
FIG . 1 is a schematic perspective view showing a con
a wind direction . Here , " a state where the rotor receives
figuration of a floating offshore wind turbine according to awind and the wind turbine inclines ” means a state where the first embodiment of the present invention ;wind turbine is inclined by receiving wind of a typical wind
FIG . 2 is a side view of essential portions showing a
speed which is assumed at a place where the wind turbine is 55 structure of a yawing suppressing apparatus of a wind
installed . Examples of the typical wind speed are an average turbine according to the first embodiment of the invention ;annual wind speed and a wind speed at which power
FIG . 3 shows a relation between change in a wind

generating efficiency becomes maximum .
Effect of the Invention

According to the floating offshore wind turbine of thepresent invention , since the yawing suppressing means can
suppress yawing caused by a gyro effect, it is possible todirection on the ocean and a deflection angle of a floating

body on water caused by influence of waves, wherein (a ) is
60 a graph showing change in a wind direction and (b ) is agraph showing change in a deflection angle ;FIG . 4A is a schematic perspective view showing a
configuration of a hydraulic damper;
FIG . 4B is a schematic front view showing a configuration

suppress adverse influence by the yawing on the power 65 of the hydraulic damper ;generating efficiency of the wind turbine caused and endur ance of devices thereof .

FIG . 4C is a sectional view taken along a line A - A in FIG .

4B ;US 9 ,879,649 B2
FIG . 5A is a schematic perspective view showing a

FIG . 1 is a schematic perspective view showing a con

mooring apparatus of the floating body according to the first

body 31 is moored to anchors 33 provided on a sea bottom
B through mooring lines 32 . A line coming out from a lower

figuration of the floating offshore wind turbine 10 according
to the first embodiment. As shown in FIG . 1 , the floating
offshore wind turbine 10 includes a floating body 31 proof the friction damper ;FIG . 6A is a plan view showing a configuration of a 5 vided with a yawing suppressing apparatus 20 . The floating

configuration of a friction damper ;FIG . 5B is a schematic front view showing a configuration

embodiment of the invention ;FIG . 6B is a side view showing a configuration of the

portion of the floating body 31 is an electric feeder line 34 .

mooring apparatus of the floating body according to the first A structure of the yawing suppressing apparatus 20 pos
10 sessed by the floating offshore wind turbine 10 of theembodiment of the invention ;FIG . 7 is a diagram showing a configuration of a pair of embodiment will be described with reference to FIG . 2 .
FIG . 2 is a side view of essential portions showing amooring lines in the first embodiment of the invention ;FIG . 8A is a plan view showing a configuration of a structure of the yawing suppressing apparatus 20 of the windturbine 10 according to the first embodiment. As shown inconventional tension mooring method ;FIG . 8B is a side view showing a configuration of the 15 FIG . 2 , the yawing suppressing apparatus 20 is composed ofa rotor 11 which is rotated by wind , a nacelle 13 in which a
conventional tension mooring method ;FIG . 9 is a side view of essential portions showing a rotation shaft 12 of the rotor 11 is accommodated , a tower
structure of a yawing suppressing apparatus of a wind
( structure body) 15 having a turning seated bearing (turning
turbine according to a second embodiment of the invention; means ) 14 which supports the nacelle 13 such that the
FIG . 10A is a schematic side view showing a configura - 20 nacelle 13 can turn with respect to a water surface or ation in a state where the yawing suppressing apparatus

possessed by a floating offshore wind turbine according to

the second embodiment of the invention receives wind ;FIG . 10B is a schematic side view showing a configura

ground surface , and a yawing suppressing means 16 which

suppress yawing of the nacelle 13 with respect to the water
surface .

The rotor 11 includes a hub 17 which is radially provided

tion in a state where the yawing suppressing apparatus 25 with a plurality of blades 18 , and the rotation shaft 12
possessed by the floating offshore wind turbine according toconnected to the hub 17 . The rotation shaft 12 is rotatably

the second embodiment of the invention does not receive
FIG . 11 is a schematic perspective view showing a

supported in the nacelle 13 . If the rotor 11 receives wind, theFIG . 12 is a schematic perspective view showing aprovided on a leeward side as compared with the nacelle 13 .

rotation shaft 12 rotates and a generator (not shown ) pro
vided in the nacelle 13 generates electricity. A hollow arrowconfiguration of a floating offshore wind turbine according 30 w in FIG . 2 shows a wind direction . In the yawing suppressing apparatus 20 of the embodiment, the rotor 11 is
to a third embodiment of the invention ;wind ;

configuration of the floating offshore wind turbine according According to this configuration , it is possible to effectively
generate a so -called weathercock effect in which a side viewto the third embodiment of the invention ; andFIG . 13 is a schematic perspective view showing a 35 direction of the rotation shaft 12 conforms to a windconfiguration of a floating offshore wind turbine according direction by yawing of the nacelle 13 provided on theturning seated bearing 14 .
to a fourth embodiment of the invention .
The rotation shaft 12 rotates upon receiving wind W , andthe rotation shaft 12 is accommodated in the nacelle 13 . The
EXPLANATION OF SYMBOLS
40 nacelle 13 also includes electricity generating means (notshown ) , such as a gear box (not shown ) which increases a
10 , 40 , 50 , 60 floating offshore wind turbine
rotation speed of the rotation shaft 12 and transmits the
11 rotor
rotation to the generator, possessed by a wind turbine device .
12 rotation shaft
The nacelle 13 is supported by the turning seated bearing 14
13 nacelle
45 provided on the tower 15 such that the nacelle 13 can turn
14 turning seated bearing ( turning means)in a direction parallel to a sea surface P . According to this
15 tower (structure body )configuration, a direction of the rotation shaft 12 can be
16 yawing suppressing means
160 hydraulic damper
varied by yawing of the nacelle 13 in accordance withchange in a wind direction W , and a rotation plane of the
165 friction damper
50 blades 18 of the rotor 11 can be in contradiction to wind .
20 , 30 yawing suppressing apparatus

31 floating body
32 mooring line
41 structure body
42 turning means
44, 64 hydrodynamic damper
51A structure body upper portion
51B structure body lower portiona coning angle
ß predetermined angle

MODE FOR CARRYING OUT THE INVENTION

When a force in the vertical direction is applied by waves

while the rotor 11 is rotating, the yawing suppressing means
16 suppresses yawing of the nacelle 13 generated by a 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

60 thereof . Although the tower 15 is provided with the yawing

suppressing means 16 in this embodiment, instead thereof,
the nacelle 13 may be provided with the yawing suppressing( First Embodiment )means 16 .

embodiment, a case where the invention is carried out as afloating offshore wind turbine will be described .

turning seated bearing 14 such that it can turn with respect

A first embodiment of the present invention will be
When the yawing suppressing apparatus 20 is provided on
described below with reference to FIGS . 1 to 8 . In this 65 a wind turbine apparatus on land instead of the floating
offshore wind turbine 10, the nacelle 13 is supported by theUS 9 ,879,649 B2
to a ground surface . If moment in the vertical direction isIf the yawing suppressing apparatus 20 including theapplied for any reason , the yawing suppressing means 16

yawing suppressing means 16 is used , it is possible tocan suppress yawing of the nacelle 13 . The above -described

restrain yawing from generating in the nacelle 13 by a gyro

weathercock effect is also of assistance in reducing a load of effect caused by pitching of the floating body 31 caused by
5 waves. Further, by suppressing the yawing of the nacelle 13 ,the yawing suppressing means 16 .
Next, a mechanism for generating vawing in the nacelle it is also possible to suppress pitching of the floating body
13 of the floating offshore wind turbine 10 by the gyro effect 31 caused by reaction of the gyro effect .
FIGS. 4A to 4C schematically show a configuration of aon the ocean will be described with reference to FIGS. 1 and hydraulic, wherein FIG . 4A is a perspective view ,3 . If a rotating object ( substance ) rotates in a direction cross 10 FIG . 4B is damper
a
front
view
and FIG . 4C is a sectional view taken
at right angles to a rotation axis, moment acts in directions along an arrow A -Ain FIG
4B . As shown in these drawings,
intersecting with each other at right angles. This moment is the hydraulic damper 160 .includes
body 163 andcalled gyro moment. An effect for generating the gyro oil 164 in its interior surrounded bya arotationbody case 161 and a
moment is called a gyro effect.
2xL = T

12 : angular velocity of pitching motion
L : angular momentum of rotating object
T : gyro momentcap 162. The hydraulic damper 160 utilizes a braking force

15 generated by viscosity resistance of the oil 164 . By adjustinga gap between the body case 161 and the rotation body 163,a contact area of the oil 164 and viscosity of the oil 164 , itis possible to vary a braking torque ( resistance ) with respect

When the rotor 11 is rotating motion L , if motion gener
to rotation of the rotation body 163. There is such a relation
ating a restoring force via yawing of the floating body 31 by 20 between a rotation speed and a braking torque of the rotation
waves of a sea surface P is generated , whereby a pitching 2 body 163 that if the rotation speed is increased , the braking
is generated , the rotor 11 yaws in the vertical direction crossat right angles to the rotation axis S . According to this , gyro

torque is increased , and if the rotation speed is reduced , thebraking torque is also reduced .

moment acts in the horizontal direction cross at right angles
If the hydraulic damper 160 is used , since it utilizes theto both the rotation axis S of the rotor 11 and the vertical 25 viscosity resistance of oil 164 , there is a merit that change
direction . In the floating offshore wind turbine 10 , since thewith time of characteristics such as wearing is small. It isnacelle 13 can turn by the turning seated bearing 14 , yawing

possible to reduce influence of change in viscosity caused byof the nacelle 13 is generated in a direction shown by T ina temperature by selecting a kind of oil 164, but it is possible

direction on the ocean and a deflection angle of the floating

constitution of cooling oil 164 by wind as an example .

of FIG . 3 are compared with each other, it can be found thatrotation shaft-connecting material 168 which surrounds thetime, and change in a deflection angle caused by influence

the rotation shaft- connecting material 168 in a predeter

that when wind is strong , heat of oil 164 is lost, its viscosity
FIG . 1 by this gyro moment.
FIG . 3 shows a relation between change in a wind 30 is increased and the braking torque is increased by taking abody on water caused by influence of waves , wherein (a ) is
FIGS. 5A and 5B schematically show a configuration ofa graph showing change in a wind direction and (b ) is aa friction damper, wherein FIG . 5A is a perspective view andgraph showing change in a deflection angle . Portions sur
FIG . 5B is a front view . As shown in these drawings, therounded by broken lines in the graph ( a ) as well as the graph 35 friction damper 165 includes a friction material 167 which(b ) show change during one hour. If the graphs (a ) and (b ) is in contact with an outer surface of a rotation shaft 166 , achange in a wind direction is generated while taking a long

friction material 167 , and an elastic body 169 which pushesof waves is generated in a short time. That is , a turning speed 40 mined direction . The friction damper 165 utilizes a brakingof the nacelle 13 caused by change in a wind direction isforce generated by friction resistance between the rotation

slow , and a speed of yawing of the nacelle 13 caused by agyro effect caused due to influence of waves and so on is

fast.

shaft 166 and the friction material 167 . By adjusting friction
and the friction material 167, it is possible to vary a braking

resistance and contact areas between the rotation shaft 166

Since the deflection angle caused by the influence of 45 torque (resistance ). There is such a relation between awaves is varied with the short period , yawing of the nacellerotation speed and a braking torque of the rotation shaft 166

13 is induced by the gyro effect . The yawing of the nacellethat if the rotation speed is increased , the braking torque is

13 adversely affects the power generating efficiency of thewind turbine and endurance of the devices .

torque is also reduced .

increased , and if the rotation speed is reduced , the braking

To selectively suppress yawing of the nacelle 13 caused 50 When the friction damper 165 is used , there are merits
that a sealing portion is unnecessary and thus the configu
wind direction is varied , it is preferable that means whose ration can be simplified , and in an environment that anby the gyro effect while allowing the nacelle 13 to turn as a

resistance is varied in accordance with a turning speed of theambient temperature is largely varied , characteristics cannacelle 13 is used as the yawing suppressing means 16 . relatively stably be maintained . Even if a size of the friction
According to this , a so - called weathercock effect can be 55 material 167 is varied due to wearing, a braking force canexerted without generating an attenuation effect for slow

constantly be maintained correspondingly by means of ayawing of the nacelle 13 supported by the turning seatedbiasing force of the elastic body 169 . That is, even if the size

bearing 14 caused by change in a wind direction which isof the friction material 167 is varied due to friction , thevaried while taking a relatively long time. It is possible toelastic body 169 biases the friction material 167 and friction
allow an attenuation effect to exert for yawing of the nacelle 60 resistance between the rotation shaft 166 and the friction

13 which is caused by waves with a short period , and thus,

it is also possible to selectively inhibit yawing of the nacelle
13 .
Since the floating offshore wind turbine 10 of the embodi

material 167 can constantly be maintained .

The floating body 31 is moored to the anchors 33 provided
on the sea bottom B by means of the mooring lines 32 inwater by a mooring method of restraining the floating bodyment can suppress the yawing of the nacelle 13 by the 65 31 from rotating around the center axis . Hence , rotation of
yawing suppressing means 16 , it becomes possible to sup - the floating body 31 in water is suppressed . This mooringpress the adverse influence.
method will be described later.

US 9 ,879,649 B2
10
In this case , if a spring rate of the mooring line 32 isdefined as k , a tensile force T of the floating body 31 in atangential direction is obtained by the following equation ( 2 )by Hooke's law :There is a floating offshore wind turbine including anapparatus which actively controls rotation of the nacelle toconform to a wind direction . In this facility , a wind turbine
is temporalily fixed to the floating body and held at a
position conforming to the wind direction , i.e., a position 5
T = k :AL . . .
(2)where a rotation plane is in contradiction to wind. Hence , theAtorqueNgeneratedby
thisextensionisobtainedbythefloating body tries to rotate around a vertical rotation axis by following equation (3 ):gyro moment caused by a gyro effect of the rotor of the windturbine . Therefore , a mooring method which suppreses
N = Tr . . .
rotation motion of the floating body around its center axis
If
configurations
the two mooring lines 32 are as shown
suppresses this yawing . According to this, it is possible to in FIG . 7 , a torqueofwhichrebels against rotation can besuppress the adverse influence on the power generating generated irrespective of a rotation
direction . Hence , rota
efficiency of the floating offshore wind turbine and endur
tion of the floating body 31 is suppressed .
ance of the devices thereof.
15 In FIGS. 6A and 6B , the mooring lines 32 are formed into

However, there is another floating offshore wind turbine the tangent lines L1 and L2 in FIG . 7. However, it isof a method in which the apparatus which actively controls apparent that even if the mooring lines 32 are formed into L3
rotation of the nacelle is omitted and a nacelle is made to and L4 (broken lines) in FIG . 7 , the same effect can beconform to a wind direction by a weathercock effect . In such exerted .
a facility , a rotation shaft of a rotor of a wind turbine is 20 FIGS. 8A and 8B show a configuration of a conventional
supported such that the rotation shaft can freely turn with simple tension mooring method . It is apparent that motion

respect to a floating body . Hence , even if yawing of thefloating body is suppressed , yawing caused by a gyro effectgenerated in the nacelle can not be suppressed . Therefore , in(floating motion ) of the floating body 31 in the horizontal

direction is suppressed by mooring lines 32 which radiallyextend in three directions shown in FIG . 8 . However, in thethe floating offshore wind turbine 10 of this embodiment, the 25 plan view (FIG . SA ), since an angle formed between ayawing suppressing means 16 is provided , thereby suppress -rotation direction (circumferential direction ) of the floating

ing the yawing generated in the nacelle 13 by the gyro effect. body 31 and the mooring line 32 is substantially 90° , it is
The mooring method of restraining the floating body 31
difficult to suppress the rotation . Hence , themooring methodfrom rotating around its rotation axis will be described withshown in FIGS. 8A and 8B does not suppress rotation of the
30 floating body 31 around its center axis .
reference to FIGS. 6A , 6B and 7 .
FIGS. 6A and 6B show a configuration of a mooring(Second Embodiment)

apparatus of the floating body according to the first embodi-

A second embodiment of the invention will be described

ment, wherein FIG . 6A is a plan view and FIG . 6B is a side

below with reference to FIG . 9 . A yawing suppressing

view . Here , in FIG . 6A , the mooring apparatus of the floating

apparatus of a wind turbine of the second embodiment isplurality of mooring lines 32 are connected to the floating

embodiment in a configuration where a coning angle isbody is projected onto a horizontal plane. One ends of the 35 different from the yawing suppressing apparatus of the first
body 31. The other ends of the mooring lines 32 areconnected to the anchors 33 provided in water .

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.

floating body 31 is projected onto the horizontal plane . The

the embodiment, a nacelle 13 is provided on a windward

lines of the circle , and the mooring lines 32 extend on theto the rotor 11 . Here, the coning angle a is an angle between

The floating body 31 is formed into a substantially
cylindrical shape . A pair of mooring lines composed of the 40 FIG . 9 is a side view of essential portions showing a
two mooring lines 32 is used . One ends of the two mooring
structure of the yawing suppressing apparatus 30 of the windlines 32 are connected to two points on a circumference of turbine according to the second embodiment. As shown ina circle of the substantially cylindrical shape when the FIG . 9 , according to the yawing suppressing apparatus 30 of

two mooring lines 32 are formed into substantially tangent 45 side as compared with a rotor 11 . A coning angle a is given

same side . According to this, it is possible to avoid a case a straight line which connects a connected portion 18A of awhere when the yawing suppressing means 16 suppresses blade 18 with respect to a hub 17 and a tip end 18B andyawing , a force is applied to the floating body 31 and yawing which is shown by an alternate long and short dash line andis generated in the floating body 31 .
50 a vertical line V shown by an alternate long and short dash
FIG . 7 shows a relation between the floating body 31 andline in the drawing .

the two mooring lines 32 connected to lower right anchors
33 in the plan view (projection view on horizontal plane ) of

According to this configuration , the nacelle 13 supported
by a turning seated bearing 14 is automatically turned in

FIG . 6A . One ends of the two mooring lines 32 are conaccordance with change of a wind direction W in a statenected to points A and B on the circumference of the floating 55 where the nacelle 13 can freely turn in the horizontal

body 31 . The mooring lines 32 are formed into tangent lines
L1 and L2 in the points A and B .

direction , and a weathercock effect for conforming a rotation

the floating body 31 is generated in the floating body 31 , one

direction conform to each other, a rotation plane of the rotor

In this configuration, when rotation around a center C ofshaft 12 of a rotor 11 to the wind direction can be enhanced .

When an axial direction of the rotation shaft 12 and a windof the two mooring lines 32 extends and a tensile force acts . 60 11 , i.e ., a plane formed by a locus of the tip end 18B of the

When a radius of the floating body 31 is defined as r and arotation angle of the floating body 31 is defined as A0 , anextension amount AL of the mooring line 32 on the exten -blade 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 .

sion side in this plan view is obtained by the following
When the present invention is carried out as the floating
equation ( 1 ):65 offshore wind turbine ( see FIG . 1 ) including the yawing
AL = rx10 . . .

(1)suppressing apparatus 30 , it is preferable to employ such aconfiguration that the rotation shaft 12 of the rotor 11 in anUS 9 ,879,649 B2
11electricity generating state where the rotation shaft 12

body 41 with the hydrodynamic dampers 44 in this manner,receives wind and inclines is located on a horizontal plane

it is possible to suppress yawing of the structure body 41

H . This configuration will be described with reference tocaused by a gyro effect. To suppress yawing of the structure
body 41, the structure body 41 may be provided with the
FIGS. 10A and 10B schematically show a configuration 5 hydraulic damper 160 (see FIGS. 4A to 4C ) or the frictionof the yawing suppressing apparatus 30 provided in thedamper 165 (see FIGS. 5A and 5B ). It is also possible tofloating offshore wind turbine of the embodiment, wherein moor the structure body 41 also using another mooring
FIGS. 10A and 10B .

FIG . 10A is a side view in a state where wind is received andmethod which does not suppress rotation of the structure

FIG . 10B is a side view in a state where wind is not received .

body 41 around its center axis by means of mooring lines .

As shown in FIG . 10A , according to the yawing suppressing 10 Although the hydrodynamic dampers 44 are applied to theapparatus 30 of the embodiment , the rotation shaft 12
floating offshore wind turbine in the third embodiment, it is( straight line in the axial direction is shown by S ) of the rotor

also possible to apply the hydrodynamic dampers 44 to a

11 in the electricity generating state where the rotation shaft wind turbine installed on the ground for example. In this12 receives wind and inclines is located on the horizontal
case , turning means is supported in a state where theplane H . According to this, a direction of the rotation axis of 15 structure body floats in water in a pool such that the structure
the rotation shaft 12 can conform to the wind direction W
body can turn with respect to a ground surface , and the water(both of them can be parallel to each other ). Hence , in the in the pool provided in a periphery and the hydrodynamic
state where wind is not received as shown in FIG . 10B , the dampers 44 are made to mutually interfere . According to

nacelle 13 is supported by a tower 15 such that the rotation
this , the hydrodynamic dampers 44 can exert function as
shaft 12 (straight line S ) of the rotor 11 forms a predeter - 20 yawing suppressing means also in the wind turbine installed

mined angle ß with respect to the horizontal plane H .

The predetermined angle ß may be set based on the moston the ground .

FIG . 12 is a schematic perspective view showing ageneral wind speed so that power generating efficiency of configuration of a floating offshore wind turbine 50 having
the floating offshore wind turbine becomes excellent. Fur a configuration different from that of the floating offshore
ther, control means of the predetermined angle B which 25 wind turbine 40 according to the third embodiment. As
varies the predetermined angle ß such that the predetershown in FIG . 12 , in the floating offshore wind turbine 50 ,in the first embodiment.
( Third Embodiment)

A third embodiment of the invention will be described

is fixed to the anchors 43 on the sea bottom B through aplurality ofmooring lines 54 .
According to this configuration , since the structure body

floating offshore wind turbine will be described . The same

exert a weathercock effect. The yawing suppressing means

mined angle ß becomes the optimal angle in accordance withan upper portion 51A of a structure body 51 and the nacellea wind speed may be provided .
13 are integrally formed together, and the turning means 42
The configuration described with reference to FIGS. 10A
is provided between the structure body upper portion 51A
and 10B can also be used in the floating offshore wind 30 and a structure body lower portion 51B . The structure bodyturbine using the yawing suppressing apparatus 20 described lower portion 51B located lower than the turning means 42
below with reference to FIGS. 11 and 12 . In the third 35 upper portion 51A can turn in accordance with change of theembodiment, a case where the invention is carried out as awind direction W by the turning means 42, it is possible tonumbers are allocated to the members described in the firstor second embodiment, and explanation thereof will beomitted in the third embodiment.

FIG . 11 is a schematic perspective view showing a

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
40 structure body upper portion 51A also using another moor

ing method which does not suppress rotation around a center

configuration of a floating offshore wind turbine 40 accord -axis by means ofmooring lines.

ing to the third embodiment. As shown in FIG . 11 , the(Fourth Embodiment)

floating offshore wind turbine 40 is configured such that a

A fourth embodiment of the invention will be described

nacelle 13 and a structure body 41 are integrally formed 45 below with reference to FIG . 13. In the fourth embodiment,

together so that the nacelle 13 does not turn with respect toa configuration in which a floating offshore wind turbine is

the structure body 41 . The structure body 41 floats on water,
the nacelle 13 is fixed to an upper end of the structure body41, and a lower end of the structure body 41 is connected tomoored by a mooring method that does not suppress rotationof a floating body around its center axis will be described .
The same numbers are allocated to the members describedanchors 43 provided on a sea bottom B through turning 50 in the first to third embodiments , and explanation thereofmeans 42. The turning means 42 is for connecting thestructure body 41 to the anchors 43 such that the structure

will be omitted in the fourth embodiment.
FIG . 13 is a schematic perspective view showing abody 41 can turn in accordance with change in the windconfiguration of a floating offshore wind turbine according

direction W , and the turning means 42 makes the structure

to the fourth embodiment. As shown in FIG . 13 , a floating
body 41 exert a weathercock effect.
55 body 31 of a floating offshore wind turbine 60 of the fourth
Hydrodynamic dampers 44 are provided on an outer side
embodiment is moored to a sea bottom B by mooring linesof the structure body 41. The structure body 41 is moored by 32 by means of a so -called catenary method . Therefore , thea mooring method which does not suppress rotation of thestructure body 41 around its center axis . By locating thefloating body 31 can yawing around its center axis to someextent. That is , the floating body 31 is moored by a mooringhydrodynamic dampers 44 in water , a function as yawing 60 method not suppressing rotation around its center axis .

suppressing means can be exerted . That is, resistance of eachof the hydrodynamic dampers 44 having a blade shape

Hence , even if the yawing suppressing means 16 constrains
yawing of a nacelle 13 with respect to the floating body 31

against water becomes smaller with respect to slow yawing

generated by a gyro effect, the floating body 31 can yawingof the structure body 41 and becomes greater with respect toaround its center axis to some extent. As a result, thefast yawing. Hence , it is possible to selectively attenuate and 65 mooring lines 32 can not suppress the yawing of the nacellesuppress the yawing of the structure body 41 caused by a
13 . However , the floating body 31 of the floating offshore
gyro effect which is fast yawing. By providing the structure wind turbine 60 is provided with a plurality of blade-shaped

US 9 ,879,649 B2
13
can restrain the floating body 31 from generating the yaw

14
endurance of devices thereof. Especially , the invention isuseful for enhancing power generating efficiency of a float
ing offshore wind turbine and endurance of devices thereof.

floating body around its center axis , if the yawing suppress

The invention claimed is :1 . A floating offshore wind turbine which generates elec
tricity using a floating body as a portion of a structure bodyhydrodynamic dampers 64 . The hydrodynamic dampers 64
ing.
When the floating offshore wind turbine is moored by themooring method which does not suppress rotation of the 5

ing means 16 which is for suppressing yawing of the nacelle
13 in the turning seated bearing 14 and the hydrodynamic
on ocean , comprising:dampers 64 which are for suppressing yawing of the floating
a rotor which is rotated by wind ,body 31 are combined with each
each other, it is effective for 10 a nacelle in which at least a rotation shaft of the rotor issuppressing yawing of the nacelle 13 and the floating bodyaccommodated ,31 caused by a gyro effect.
wherein the structure body is in shape of a tower, includes

In the floating offshore wind turbine 60 of the fourtha turning seated bearing which

embodiment, the two hydrodynamic dampers 64 are dis
posed such that they are opposed to each other through thesupports the nacelle such that the nacelle can turn withfloating body 31 . That is, a line connecting mounted portions 15

respect to a water surface ,a hydrodynamic damper, which is provided on the strucpasses a substantially center of a cross section which isparallel to a horizontal plane of the floating body 31 . This is

ture body and suppresses yawing of the nacelle withrespect to the water surface by mutual interference
between a blade- shaped structure provided directly in alower part of the structure body and peripheral fluid ,a hydraulic damper or friction damper, which is provided
between the nacelle and the structure body where thehydrodynamic damper is provided and suppresses theyawing of the nacelle , andof the two hydrodynamic dampers 64 to the floating body 31

because that the hydrodynamic dampers 64 are provided not

for suppressing pitching of the floating body 31 but for 20

suppressing yawing of the floating body 31. That is, thehydrodynamic dampers 64 of the floating offshore windturbine 60 are provided so that the hydrodynamic dampers
64 interfere with outside water and become resistance of 25 a plurality ofmooring lines with which the structure bodyyawing of the floating body 31 . Therefore , it is unnecessary 25
is moored to anchors on a bottom of water.
to provide three or more hydrodynamic dampers 64 unlike
2.
The floating offshore wind turbine according to claim
a case where the hydrodynamic dampers 64 are provided for1
whereinthe nacelle is provided on a windward side as
suppressing the pitching . Hence, even if the number of compared withrotor.
hydrodynamic dampers 64 is one, the same function is 0 3 . The floatingtheoffshore
turbine according to claim
exerted . However, since the same function is exerted eve if 30 2 , wherein a coning angle windisgiven
to the rotor.
the number of the hydrodynamic dampers 64 is three or
4.
The
floating
offshorewindturbineaccording to claim
more , the number of the hydrodynamic dampers 64 may be 1 , wherein the floating body is formed into
a substantiallythree or more .
In the fourth embodiment, even if an apparatus which

cylindrical shape , the plurality of mooring lines are comof the yawing suppressing means 16 , it is possible to restrain
the floating body 31 from generating yawing by the hydrosubstantially cylindrical shape and the pairs ofmooring lines

posed of pairs of mooring lines whose one ends are con
actively controls rotation of the nacelle is provided instead 3535 nected
to two points on a circumference of a circle of theformed into substantially tangent lines of the circle anddynamic dampers 64 . The hydrodynamic dampers 64 gen areextendon the same side when the floating body is projected
erate a hydrodynamic effect by interference with surround 40 onto a horizontal
plane.
ing fluid and exert a function as yawing suppressing means. 40 5 . The floating offshore
wind turbine according to claim
Hence , a shape of a cross section of the structure body itself
1 , wherein the nacelle is supported by the structure bodymay be an angular shape or a shape having many concavo suchthat a predetermined angle is formed between a hori

convex portions.

INDUSTRIAL APPLICABILITY
The present invention can be utilized as an apparatus forenhancing power generating efficiency of a wind turbine andzontal plane and the rotation shaft of the rotor in a state
45 where wind is not received so that the rotation shaft of therotor in a state where wind is received becomes parallel toa wind direction .
*

*

*

*

*