Note: Descriptions are shown in the official language in which they were submitted.
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
WIND TURBINE WITH FRICTION DRIVE POWER TAKE OFF ON OUTER RIM
BACKGROUND OF THE INVENTION
FIELD OF INVENTION
This invention relates to a wind turbine and method of operation thereof
for producing energy and, more particularly, to a wind turbine having mufti-
blades
(for example eight to twenty), and a ring around the circumference thereof,
the
ring driving energy producing equipment. The blades are shaped with airfoils
to
produce maximum power coefficient.
DESCRIPTION OF THE PRIOR ART
Wind turbines, including windmills, are lcrlown and are used to power
energy production equipment including generators, compressors or pumps, as
well
as other devices. It is known to have the wind turbine connected to a shaft
and the
rotational energy in the shaft is then used to drive the energy producing
equipment. Windmills or wind turbines have gearboxes to transfer the energy
from the blades through the shaft t0 energy pTOdl1C111g equipment. Some wind
turbine manufactures are using a large diameter direct drive generator
connected
directly to the shaft and running at low rotational speed. Wind turbines with
large
rated electrical output require (<3 MW) large gearboxes and generators. This
can
result in heavy and costly power transmission and energy production equipment.
It
is lcrlown to use wind turbines to produce electrical energy. Fixed and
variable
speed wind turbines are used to produce electricity with the same frequency as
the
grid. Fixed and variable speed wind turbines have certain advantages and
disadvantages. Variable speed wind turbines have advantages of reducing the
dynamic loads on the power transmission systems and have higher power
coefficients than fixed speed wind turbines. Variable speed wind turbine use
several methods and systems to obtain the same frequency as the grid system of
an
electrical utility. These systems are more costly than those used in fixed
speed
wind turbines. Variable speed operation will allow the wind turbine to start
producing electricity at lower wind speeds and hence collect more energy. With
variable speed wind turbines, there is a difficulty of producing electricity
with the
same frequency as the grid because the wind velocity constantly changes and
therefore the speed of rotation of the blades of the wind turbine varies. With
-1-
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
constant speed wind turbines, the frequency of the electricity produced can
match
the frequency of the grid, but difficulty arises in maintaining a constant
speed with
variable wind conditions. Further, electrical energy cannot be produced by any
wind turbine during periods when the wind is not blowing or is not blowing at
a
sufficient velocity to rotate the rotor of the wind turbine.
Wind power is renewable and is a green energy.source that is highly
desirable as it does not pollute.
SUMfMARY OF THE INVENTION
It is an object of the present invention to provide a wind turbine that can be
controlled to operate energy producing equipment at variable speed rate of
speed.
It is further object of the present invention to provide a wind turbine
without using
a step up gearbox.
A wind turbine for producing energy has a rotor on a shaft. The rotor
supports a plurality of blades and is rotatably moLmted on the shaft. The
blades
each have a tip, there being a plurality or tips on the turbine. The tips are
connected to support a ring that extends around a circumference formed by the
tips. The ring rotates with the blades, the ring having a front and rear
surface with
rotators mounted to removably contact the ring on the front and rear surfaces.
Each of the rotators is connected to energy producing equipment. The rotators
rotate with the ring when the ring rotates, thereby driving the energy
producing
equipment. The turbine is controlled by a controller.
A wind turbine for producing energy has a rotor on a stationary shaft. The
rotor supports a plurality of blades shaped with airfoil sections and is
rotatably
mounted on the stationary shaft via a hub and a bearing. The blades each have
an
outer tip, there being a plurality of outer tips on the wind turbine. The tips
are
connected to a ring that extends around a circumference formed by the tips.
The
ring has front and rear surface and rotators are mounted to removably contact
the
ring on the front and rear surfaces. Each of the rotators is connected to
energy
producing equipment. When the ring rotates and the rotators are in contact
with .
the ring, the rotators also rotate, thereby driving the energy producing
equipment.
Preferably, the energy producing equipment is selected from the group of a
generator, a compressor and a pump.
-2-
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
Still more preferably, the rotators are momited on a cart with rails having
its
center of rotation at the center of the tower base circle. The cart being
rotatable to
move with the wind turbine either toward or away from the wind.
A method of operating a wind turbine for producing energy, said turbine
having a rotor on a shaft, said rotor supporting a plurality of blades and
being
rotatably mounted on said shaft, said blades each having a tip, there being a
plurality of tips on said turbine, said tips being connected to support a ring
that
extends around said tips, said ring rotating with said blades, said ring
having a
front and rear surface with rotators mounted to removably contact said ring on
said front and rear surfaces, each of said rotators being connected to energy
producing equipment, said rotators rotating with said ring when said ring
rotates,
said turbine being controlled by a controller, said method comprising
operating
said turbine by continuously monitoring wind conditions, adjusting yaw, blade
orientation and pressure and number of rotators against said ring or removal
of
rotators from said ring to produce power output whenever said wind conditions
are sufficient.
BRIEF I~E~CRIPTI~N ~F THE I~I~WI~TCi~
Figure 1 is a partial sectional side view of a wind turbine;
Figure 2 is a front view of a wind turbine;
Figure 3 is an enlarged view of a nacelle and bed plate;
Figure 4~A is a side view of a stationary cone;
Figure 4B is an enlarged partial perspective view of a spring loaded gate;
Figure SA is blade connection to a hub;
Figure SB is a partial schematic sectional view of a glade;
Figure 6 is a perspective view of a hub-blade connection;
Figure 7 is partial perspective view of spokes and said hub-blade
connection;
Figure 8A is a partial perspective view of side view of the hub;
Figure 8B is a partial perspective view along with lines A-A of Figure 8A;
Figure 8C is a partial perspective view along the lines B-B of Figure 8A;
Figure 9 is a partial perspective view of a blade-ring connection;
Figure 10 is a perspective view of a ring section;
Figure 11 is a top view of the ring section and part of a ring;
-3-
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
Figure 12 is a side view of the ring section;
Figure 13 is a perspective view of a tire connected to a shaft of a
generator; .
Figure 14 is a perspective view of two opposing tires and generator;
Figure 15 is a partial perspective view of a power production equipment
cart;
Figure 16 is a side view of a first section of a tower;
Figure 17 is a side view of a second section of the tower;
Figure 18 is a side view of a third section of the tower;
Figure 19 is a partial perspective view of the third section of the tower on a
foundation;
Figure 20 is a top view of the tower and foundation shown in Figure 19;
Figure 21 is a partial sectional side view of the tower and foundation
Figure 22 is a partial perspective view of a ring section with a bralce
system mounted thereon;
Figure 23 is an enlarged partial perspective view a rail cover layout ; and
Figure 24 is a graph of the operation of the yaw system.
I~E~~IZIPTI~~T ~F ~ PIZEFEI~I~ EI~I~~I~II~IVT'
In Figures 1 and 2, a turbine 2 has a rotor with a hub 6 and a plurality of
blades 10 extending outward from a root 3 to a tip 12. Preferably, the wind
turbine has eight to twenty blades. Connected to and supported by each of the
tips
12 is a ring with a front surface 14 and a baclc sluface 62. Rotators 18 are
located
and mounted to be removably placed into contact with the front surface 14 and
back surface 62 as the ring 1 rotates. The rotators each have a shaft 19 which
is
connected to energy producing equipment 20. The rotators are preferably tires
mounted on a rim 34. The tires are preferably made of rubber. Steel or metal
wheels can also be used as rotators. The energy producing equipment includes
generators, compressors, pumps and the lilce. When the energy producing
equipment is a generator, the rotation of the wind turbine 2 will cause the
front
surface 14 and back surface 62 of the ring to rotate. The tires will also
rotate when
they are in contact with the ring l, thereby driving the generators.
Preferably, each
tire is connected to a separate generator. Also preferably, every rotator,
shaft and
generator on the front surface 14 of the ring 1 has a corresponding rotator,
shaft
-4-
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
and generator on the back surface 62. The corresponding rotator is preferably
mounted and controlled to removably contact the back surface simultaneously
with the front surface rotator so that when a rotator is in contact with the
ring on
the baclc surface, the corresponding rotator on the front surface will also be
in
contact with the ring. Similarly, when a rotator on the front surface is moved
out
of contact with the ring, the corresponding rotator on the baclc surface will
also be
moved out of contact with the ring. The corresponding rotator is always
located
directly behind the rotator on the front surface. In this way, the pressure on
the
ring from front and baclc is equalized at all times so that the ring is not
unbalanced
by force exerted by the rotators 18. The rotator 18, shaft 19 and energy
producing
equipment 20 of each mechanism are mounted on a moving base 21. All the
mechanisms are mounted on a cart 22 having steel wheels 24 allowing the cart
22
to travel on a rail 26 when required to turn the turbine 2 toward or from a
direction
of the wind. A hydraulic supply 33 will provide the necessary hydraulic
pressure
to move the mechanisms. The electrical current produced by the turbine is
transmitted by the generator cables 23 to the transformer 29 via a slip ring
25 and
a main electrical cable 28.
In Figures l and 2, it can be seen that the blades 10 are connected to the hub
6 and the hub 6 is mounted on a stationary shaft 8 via a beaxing 5. A
stationary
cone 4 is mounted on a front side of the stationary shaft 8. The stationary
cone 4 is
fixed to the stationary shaft 8 by spolces 15 and a hollow shaft 16. The cone
is
equipped with spring loaded gates 31, which start allowing air to pass through
the
cone 4 at high wind speeds.
The stationary shaft 8 is fixed on a bedplate 13 by a front mounting 9 and a
rear mounting 11. The bedplate 13 is moLmted on a tower 17, which is fixed to
a
foundation 27. The foundation 27 is constructed into the ground 30.
In Figure 3, an electrical motor 35 will be used to power a yaw mechanism.
The motor 35 will drive a gear reducer 36 with a shaft 39, two locating
bearings
37, 38 and a pinion 40. The pinion 40 will drive a slew bearing 41 mounted to
the
bedplate 13 by bolts 42 and to a tower flange 43 by bolts 44. The tower flange
43
is welded to the tower 17.
Figure 4A shows an enlarged side view of the cone 4. A hollow shaft 16 is
fixed to the stationary shaft 8 and provides the necessary support for the
radial
-5-
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
spokes 15 and outer spokes 45. A spring loaded gate 31 (as shown in detail in
Figure 4B) has a spring 46 and a hinge 48 keeping the gate closed at low wind
speeds. The gate will start to open under high wind speed allowing air to pass
through the cone. The spring 46 is mounted on a base 47 supported by the
radial
spokes 15 of the cone.
Figure SA is a perspective view showing the blade to hub connection 3.
The blade 10 has a supporting shaft 49 which extends from the root of the
blade to
the tip (not shown in Figure SA). The blade root flange 50 is welded to the
support shaft 49 having bolt holes 51. This design is for a stall regulated
operation, which does not require a pitch mechanism. The blades 10 can be
mounted on a slew bearing and have an electrical motor and a gear reducer
(similar to the mechanism shown in Figure 3 for the yaw drive) to provide a
pitching mechanism for the blades 10.
In Figure SB, there is shown a schematic sectional view of the blade 10. It
can be seen that the blade 10 has an air foil shape with an outer wall 110,
ribs 112
and a blade shaft 114. The blade 10 has a D-shaped spar section 116 and a
trailing
edge section 118.
Figure 6 is a perspective view showing the hub blade connection 54~. The
blade root flange 50 from Figure SA (not shown in Figure 6) is mounted on a
hub
blade mounting flange 52. The hub blade molmting flange 52 (shown in Figure
SA, but not shown in Figure 6) has bolt holes 53 facing the blade root flange
bolt
holes 51.
Figures 7, 8A, 8B and 8C show the hub blade connection 54 connected to
hub rings 56 via mounting bolts 55. The hub rings 56 are connected to a center
of
the hub 6 by spokes 57.
Figures 8B and 8C show a partial perspective view of a side wall 120 of
the hub 6 and a cross member 122.
Figure 9 shows a blade to ring correction 12. The blade 10 has a
supporting shaft 49 which extends from the root of the blade to the tip (not
shown
in Figure 9). The blade tip flange 58 is welded to the blade support shaft 49
having bolt holes 59. Figure 9 shows an opposite end of the blade 10 from the
end
shown in Figure SA.
-6-
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
Figures 10, 11 and 12 show the front face of the ring section 14 and back
face of the ring section 62, the ring section has a blade mounting flange 60
with
bolt holes 59 facing the bolt holes of the blade tip flange 59. Each ring
section is
connected to the adjacent ring section by a mounting 32. Ring sections have
holes
61 to reduce the weight. Each ring section 14 has a curvature (Figure 12) so
that
the ring sections can form a circle (see Figure 2). The portions of the ring
sections
that the tires contact are flat.
Figure 13 shows a.perspective view of a front tire-generator mechanism 79
consisting of a rotator 18 (preferably a tire) mounted on a rim 34 which is
connected to a shaft 19 that drives the power generation equipment 20, which
in
this Figure is an electrical generator. A brake disc 67 is mounted on the
shaft 19
by a flange 66. Brake calipers 68 are located around the brake disc 67 (first
brake
option). A power generating equipment mounting 73 is fitted with rolling
elements 75, which are fixed to a motmting base 21. A spring 69 is mounted
around a hydraulic cylinder 70, which is connected to the shaft 19 and momted
on
support structure 64. Another spring 71 is mounted around a hydraulic cylinder
72, which is connected to the power generation equipment mount 73 and mounted
on the support structure 64. The springs 69, 71 will provide the required
pressure
to connect the rotator 18 to the front face ring 14 to transmit the required
power.
The hydraulic cylinders 70, 72 provide the required force to disconnect the
rotator
18 from the front face ring 14. A lock 74 locks the power generating equipment
mounting 73 into place when the rotator 18 is fully disconnected from the
front
face ring 14, relieving the two hydraulic cylinders 70, 72. A small hydraulic
cylinder 76 actuates the lock 74. The hydraulic cylinder 76 is mounted on a
support structure 77. The two hydraulic cylinders 70, 72 are supplied by
hydraulic
pressure by hydraulic lines 78 connected to the hydraulic supply 33. The
hydraulic
cylinders 70, 72 are mounted on a support structure 64, which is supported by
an
angled structural member 65, to provide the required stiffness. An electrical
cable
23 is used to connect the power generation equipment 20 (generator in this
case)
to the slip ring 25. The whole mechanism is mounted on the cart 22.
Figures 14 and 15 show the front tire-generator mechanism 79 and a back
tire-generator mechanism 80, which are mounted on the cart 22. The mechanisms
79, 80 are identical to one another and are mirror images of one another. An
_7_
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
electrical cable 23 connects the power generation equipment 20 (generator in
this
case) to the slip ring 25, which is coiniected to the transformer 29 by an
electrical
cable 28. The cart 22 has a cover 82 protecting the equipment from the
environment and a brush 81 scraping the front face ring 14 (not shown in
Figures
14 and 15) and the baclc face ring 62. The cart 22 is mounted on a steel
wheels 24,
the wheels being connected to a shaft 84 having a bearing 83. Inner steel
retention
wheels 85 are used to prevent the cart 22 from tipping to the sides. The steel
wheels 24 are rotate on the rail 26.
Figure 16 shows a first tower section 86 having a top first section tower
flange 43 that is fitted with bolts holes 44. Several service station supports
87 axe
located on the inside of the first tower section 86. The first tower section
87 is
constructed from hollow steel and is fitted at the bottom with a flange 89
having
bolt holes 88 to connect it to the next tower section.
Figure 17 shows a second tower section 90. A top flange 89 is fitted with
bolts holes 88 to connect the section to the first tower section 86 (not shown
in
Figure 17). Several service station supports 87 are located on the inside of
the
second tower section 90. The second tower section is constructed from hollow
steel and is fitted at the bottom with a flange 92 having bolts holes 91 to
connect it
to the next tower section.
Figure 18 shows the third tower section 93. A top flange 92 is fitted with
bolts holes 91. Several service station sttppouts 87 are located on the inside
of the
third tower section 93. The third tower section 93 is constructed of hollow
steel
and is fitted with a flange 95 having bolts holes 94 to connect it to the
foundation
flange 98 (see Figure 19).
Figures 19, 20, and 21 show the third tower section 93 connected to the
foundation flange 98 having steel support triangles 96 to prevent bending of
the
third tower section 93. The foundation steel flange 98 is connected to a steel
shaft
100 and steel rings 99 embedded into the reinforced concrete foundation 27.
Figure 22 is shows the second option for the brake system by fitting calipers
104 actuated by a hydraulic cylinder 101 having a hinged mechanism 102 at the
front ring side 14 and the baclc ring side 62 (not shown) to provide the
required
braking power to stop the wind turbine 2 from rotating. Hydraulic cylinders
101
_g_
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
are supplied with hydraulic fluid through hydraulic supply lines 103; which
are
connected to the hydraulic supply 33.
Figure 23 shows a rail cover 106 mounted on small wheels 107. The small
wheels 107 move on the rail 26 with the cart 22 to lceep the rail 26 protected
from
the outside environment. A steel wheel cover 105 protects the steel cart
wheels 24
from the outside environment. The steel wheel cover 105 can move up and down
to allow access to service the cart steel wheels 24. The same reference
numerals
are used in Figure 23 as those used in Figure 15 to refer to those components
that
are identical.
to OPERATION AND CONTROLS
The wind turbine of the present invention has the capacity to collect and
transmit power in the range of 50 kilowatts to 7.5 megawatts and has a low
capital
cost when compared to conventional power wind turbines rated in the same
range.
The wind turbine will rotate with relatively low rpm when compared to
conventional wind turbines (rpm will depend on the number of blades, when
using
blades the rotational speed is between 1 and 5 rpm). This low rotational speed
will provide long service time for the rotating parts requiring less
maintenance,
produce less noise than conventional wind turbines, and the turbine has better
control characteristics than conventional designs. The wind turbine of the
present
20 invention can be designed to compress air and to store that compressed air
for use
during peals hours for the electrical system. The number of compressors used
depends on the power delivered by the wind turbine and the capacity of each
compressor. Compressed air can be stored in underground storage pipes, tanks,
caverns or in the body of the wind turbine tower. Heat exchangers can be used
to
extract the heat from the compressed air storage and re-provide the same heat
for
the compressed air later for the regeneration process.
The wind turbine of the present invention can be used to drive an air-water
engine consisting of several cylinders. Air-water systems have been previously
described. A Pelton wheel is preferably used with the air-water system to
produce
electricity as described in US Patent No's. 6,672,054 and 6,718,761.
A single rotator can be designed to drive different types of energy production
equipment. For example, a rotator could be alternatively connected to a pump,
compressor and generator with a controller to control which type of energy
-9-
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
producing equipment is being driven at any particular time. The wind turbine
can
be constructed to be strong enough to have the rotators contact one surface of
the
ring only. Also, the ring can be designed with proj ection and indentations
thereon
corresponding to projections and indentations on the rotators. The ring could
also
be designed in separate parts with the front surface located on a separate
component from the back surface.
A control system for the wind turbine is as follows:
~ Operational sequence system.
The system will receive external signals according to the operating
conditions, above all the wind conditions and operator's intentions, which
will determine the set values for the control system.
Objectives of the operational sequence system are as follows:
1- Ensure fully automatic.operation.
2- Recognize hazards and activate the corresponding safety systems.
3- 1~/Ieet special requirements of the operator.
o supervisory systems controls.
The system will take into consideration the following:
1- Yaw motion.
2- Speed and power output.
3- l~Iode of operation.
The control system will talce into consideration the following:
1- Wind Measurement S stem:
Operational sequence and yawing requires measuring the wind speed and
direction.
Electrical motor-driven yawing system is proposed for the mufti blade wind
turbine, which requires information about wind direction.
Operational sequence requires the wind speed information in order to switch
between different modes of operation.
-10-
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
Measuring of the wind speed could be preformed indirectly by means of the
electrical output. The rotor itself is the only representative wind measuring
instrument of a turbine.
2- Yaw Control:
The wind measuring system provides a mean value of the wind direction over
a period of ten seconds. This value is compared with the instantaneous
azimuth position of the nacelle every two seconds. If the deviation remains
below 3 degrees, the yaw system will not be activated. If the determined yaw
angle is above this value, the time for correction is determined by a pre-
programmed function. An operating diagram for the yaw is shown in Figure
24.
If the yaw angle is small (0 to 20 degrees), yawing is carried out within 60
seconds.
If the yaw angle is 20 to 50 degrees, yawing is carried out within 20 seconds.
If the yaw angle is large (exceeds 50 degrees), yawing is caxried out
immediately.
The rotor. yaw speed is low and to be determined after taking into
consideration the gyroscopic moments. Since the yaw speed is the same for
small and large yaw movements of the turbine, large movements will take
much longer to complete than small movements. For small movements, the
commencement of yawing is delayed as the wind may change direction within
the delay period. For large movements (exceeding 50 degrees), the yaw
movement commences immediately.
3- Power and Speed Control by Rotor Blade Pitching when using a Blade
Pitching Mechanism:
The objective is to obtain a stable operating point by the following means:
a- Controlling the blade pitch, which will control the rotor's primary
energy.
b- Control of the generator voltage and reactive power.
c- Loading and unloading of the generators.
-11-
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
Extremely brief fluctuations of less than few seconds are reduced by the
rotor blades, friction ring, and actuating elements mass inertia. Combined
speed
and power control system is proposed for the control of the Multi Blade wind
turbine.
4- Mechanical Drive Train:
The inertia of the rotating masses including:
a- The Rotor.
b- The Friction ring.
c- The Rotator and shaft
d- The Generator Rotor.
The stiffnesses, the damping behavior, and vibration behavior are
different than those of a conventional wind turbine as the power transmission
system is unconventional using a friction drive and multi-generator system.
5- Full and Partial Load ~peration:
In full load operation the pitch control is active (when using a pitch
mechanism), so that rotational speed and power can be adjusted to the nominal
values. The speed controller can be provided with a degree of insensitivity to
reduce the number of pitching processes.
V'Jhen not using a pitch mechanism, the blades will be stall regulated.
Hence, the angle of the blades will be high enough at high wind speeds to
ensure stall to reduce the loads on the blades.
At partial load, control of the power output and rotor speed is carried out by
variation of the generator torque and loading and unloading of the Tire-
Generator mechanisms (if the mechanisms is not in contact with the friction
ring all the time).
Using the MPPT (Maximum Point Power Traclcing) process approach to
control the rotor speed achieving the optimal rotor power coefficient. This is
achieved by determining the set point for the power maximum by incremental
speed variation, in the form of a scanning process.
-12-
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
Control System Actions:
1- Acquisition of the input data necessary for operational sequence as wind
speed and wind direction.
2- Automatic operational sequence, with manual operation for special cases.
3- Activation of the safety and emergency systems taking into consideration
shutdown of the rotor even with out electric control system.
4- Adaptation to operation on the grid.
Operational Cycle:
Operational cycle includes the following:
~ System check at stand still: checking of the operational status of the most
important systems. The rotor is arrested by the parking brake and pitch
angle (when pitch mechanism is used). If no faults are indicated in the
system check, the turbine is ready for further progress in the operational
cycle.
~ Yawing: if the system check is positive, the yaw system is activated, the
rotor still being parked. The turbine is yawed to the wind direction (turbine
yawing includes moving the Rotor head and the Tire-Generator
Mechanism Cart at the same time) and it is checlced whether the wind
speed is within the operating range of 4 to 25 m/sec.
Start up: pitching of the rotor blades into the starting position (when using
a pitching mechanism), subsequently the mechanical rotor brake is
released. The rotor stars to turn and accelerates up to the synchronization
speed of the generator, corresponding to 90% of the nominal speed. Start
loading of the Tire-Generator Mechanism (Tire-Generator mechanisms
may be in contact with the friction ring all the time or may be loaded as the
wind speed increase). The blade pitch angle is controlled according to a
preset speed increase (when using a pitch mechanism).
~ Normal operation: if the generator's connection to the grid has been
established the power output into the grid begins (cut-in wind speed). The
-13-
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
turbine operates at partial load if the wind is below rated value. Under
these conditions the pitch angle is set to a predetermined value (when
using a pitch mechanism), which is the angle of the best compromise close
to the optimum in the rotor power characteristics (variable blade pitch
operation under partial load may be required). When operating at full load,
the blade pitch is then controlled 5tlch that the rated power is not exceeded.
When using a stall regulation as the state of pitch mechanism, the blades
will stall to avoid overrating the wind turbine and this will ensure that the
rated power is not exceeded.
~ Shut-down: if the wind speed drops below the cut-out wind speed or if
loaded operation is to be interrupted, the rotor will be brought to the
standstill. During the shutdown process the rotor blades are pitched in
order to achieve a defined speed decrease (when using a pitch mechanism).
The generators are talcen off the grid, within the range of 92% to 90% of
the rated speed. Rotor standstill is achieved by setting the speed set-point
value to zero. The rotor blades pitch to an angle of approximately ~0
degrees (when using a pitch mechanism). This brakes the rotor
aerodynamically to a low idling speed. Complete standstill is achieved by
applying the mechanical bralce. When using stall to regulate the blades, the
turbine is yawed out of the wind direction. This will reduce the rotor speed
to idling speed. ~'omplete standstill is achieved by applying the
mechanical brake.
The method of operating the wind turbine to produce energy can vary.
The turbine is preferably operated as a variable speed turbine and the
controller is used to control the operation of the turbine in light of the
wind
conditions. The controller preferably continually monitors the wind
conditions and when the conditions are sufficient to generate energy from
the wind turbine, the controller automatically adjusts the yaw, orients the
blades and when the blades are rotating at sufficient rpm, places the
appropriate number of rotators with the appropriate pressure against the
ring. In stronger wind conditions, the controller will place more rotators
against the ring and in weaker wind conditions, the controller will remove
some or all of the rotators from the ring. When wind conditions are not
-14-
CA 02522280 2005-10-14
WO 2004/092580 PCT/CA2004/000589
sufficient to generate energy, the controller will shut the turbine down by
applying a mechanical brake to the turbine to stop the blades from rotating
and also orienting the blades and adjusting the yaw of the turbine to reduce
the effect of the wind. As the wind conditions improve, the controller will
again release the brake, adjust tile yaw and orient the blades to cause the
blades to rotate at sufficient speed to generate energy. The controller will
then place the rotators in varying nLUnbers against the ring and remove
rotators as required as the wind conditions continue to vary. The process
will be repeated as the turbine continues to operate.
Numerous variations can be made to the invention within the scope of
the attached claims. For example, the front and rear surfaces of the ring
can have a plurality or alternating ridges and indentations thereon
corresponding to alternating indentations and ridges on said rotators. The
wind turbine has a controller that automatically controls the operation of
the turbine.
-15-
