SYSTEM AND METHODS FOR CONTROLLING WIND TURBINE
BACKGROUND OF THE INVENTION
[0001] The embodiments described herein relate generally to wind
turbines and, more particularly to a system and method for controlling a wind turbine.
[0002] At least some known wind turbines include a nacelle fixed on
a tower. The nacelle includes a rotor assembly coupled to a generator through a shaft.
In known rotor assemblies, a plurality of rotor blades extend from a rotor. The rotor
blades are oriented such that wind passing over the rotor blades turns the rotor and
rotates the shaft, thereby driving the generator to generate electricity.
[0003] During operation of known wind turbines, power output
generally increases with wind speed until a rated power output is reached. At least
some known wind turbines adjust a pitch of the rotor blades in response to an increase
in wind speed to maintain a constant power output. At least some known wind
turbines includes a feedback control system to monitor the wind turbine power output
and to change a pitch of a rotor blade pitch to adjust the power output to a predefined
power output level.
[0004] In case of sudden turbulent gusts, wind speed, wind
turbulence, and wind shear may change drastically in a relatively small interval of
time and may cause rotor imbalance. At least some known wind turbines have a time
lag between the occurrence of a turbulent gust and the pitching of the rotor blades
based on the operation of the feedback control system. As a result, load imbalances
and generator speed may increase significantly during such turbulent gusts, and may
exceed the maximum predefined power output level that cause the generator to trip
and the wind turbine to shut down. In addition, the rotor blades may be subjected to
stresses that cause fatigue cracking and/or failure, which may eventually cause
suboptimal performance of the wind turbine.
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CONFIRMAHON COPY
BRIEF DESCRIPTION OF THE INVENTION
[0005] In one aspect, a method of operating a wind turbine is
provided. The wind turbine includes a rotor that is rotatably coupled to a generator
that is positioned within a nacelle. The rotor includes one or more rotor blades that
are coupled to a hub. The method includes transmitting, from a first sensor to a
control system, at least a first monitoring signal indicative of a first wind condition at
a first distance from the wind turbine. A second sensor transmits at least a second
monitoring signal that is indicative of a second wind condition at a second distance
from the wind turbine that is longer than the first distance to the control system. The
control system calculates a wind turbine operating command based at least in part on
the first monitoring signal and the second monitoring signal. One or more wind
turbine components are operated based on the calculated wind turbine operating
command.
[0006] In another aspect, a wind turbine control system for use with a
wind turbine is provided. The wind turbine includes a rotor that is rotatably coupled
to a generator that is positioned within a nacelle. The rotor includes one or more rotor
blades that are coupled to a hub. The wind turbine control system includes a first
sensor that is configured to sense a first wind condition at a first distance from the
wind turbine. A second sensor is configured to sense a second wind condition at a
second distance from the wind turbine that is longer than the first distance. A
controller is coupled to the first sensor and the second sensor. The controller is
configured to calculate a wind turbine operating command based at least in part on the
sensed first wind condition and the sensed second wind condition.
[0007] In yet another aspect, a wind turbine is provided. The wind
turbine includes a tower, a nacelle that is coupled to the tower, a generator that is
positioned within the nacelle, a rotor that is coupled to the generator with a rotor shaft,
at least one rotor blade that is coupled to the rotor, and a wind turbine control system.
The wind turbine control system includes a first sensor that is configured to sense a
first wind condition at a first distance from the wind turbine. A second sensor is
configured to sense a second wind condition at a second distance from the wind
turbine that is longer than the first distance. A controller is coupled to the first sensor
and to the second sensor. The controller is configured to calculate a wind turbine
operating command based at least in part on the sensed first wind condition and the
sensed second wind condition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of an exemplary wind turbine.
[0009] FIG. 2 is a schematic view of the wind turbine shown in FIG.
1 including an exemplary wind turbine control system.
[0010] FIG. 3 is another perspective view of the wind turbine shown
in FIG. 1.
[001 1] FIG. 4 is a schematic view of an exemplary load adjustment
system that may be used with the wind turbine control system shown in FIG. 2.
[0012] FIG. 5 is a flow chart illustrating an exemplary method that
may be used for operating the wind turbine shown in FIG. .
DETAILED DESCRIPTION OF THE INVENTION
[0013] The exemplary methods and systems described herein
overcome disadvantages of known wind turbines by providing a control system that
operates the wind turbine based on a sensed wind condition upwind of the wind
turbine. Moreover, the wind turbine includes a LIDAR sensor for sensing a wind
condition at two locations upwind of the wind turbine. By determining the wind
condition upwind of the wind turbine, the control system facilitates preventing
overspeed of the wind turbine caused by sudden gusts of wind that may cause damage
to wind turbine components. By preventing an overspeed of the wind turbine, the cost
of operating the wind turbine system is facilitated to be reduced. As used herein, the
term "overspeed" refers to a rotational speed of a rotor shaft at which potential
damage to the rotor shaft including damage to the turbine may occur.
[0014] FIG. 1 is a perspective view of an exemplary wind turbine 10.
In the exemplary embodiment, wind turbine 10 is a horizontal-axis wind turbine.
Alternatively, wind turbine 10 may be a vertical-axis wind turbine. In the exemplary
embodiment, wind turbine 10 includes a tower 12 that extends from a support surface
14, a nacelle 16 that is mounted on tower 12, a generator 18 that is positioned within
nacelle 16, a gearbox 20 that is coupled to generator 18, and a rotor 22 that is
rotatably coupled to gearbox 20 with a rotor shaft 24. Rotor 22 includes a rotatable
hub 26 and at least one rotor blade 28 that is coupled to and extends outwardly from
hub 26. Alternatively, wind turbine 10 does not include gearbox 20, such that rotor
22 is coupled to generator 18 via rotor shaft 24.
[0015] In the exemplary embodiment, rotor 22 includes three rotor
blades 28. In an alternative embodiment, rotor 22 includes more or less than three
rotor blades 28. Rotor blades 28 are spaced about hub 26 to facilitate rotating rotor 22
to enable kinetic energy to be transferred from the wind into usable mechanical
energy, and subsequently, electrical energy. Rotor blades 28 are mated to hub 26 by
coupling a blade root portion 30 to hub 26 at a plurality of load transfer regions 32.
Loads induced to rotor blades 28 are transferred to hub 26 via load transfer regions 32.
In the exemplary embodiment, each rotor blade 28 has a length ranging from about 0
meters (m) (99 feet (ft)) to about 120 m (394 ft). Alternatively, rotor blades 28 may
have any suitable length that enables wind turbine 10 to function as described herein.
For example, other non-limiting examples of rotor blade lengths include 10 m or less,
20 m, 37 m, or a length that is greater than 120 m. As wind strikes rotor blades 28
from a direction 34, rotor 22 is rotated about an axis of rotation 36. As rotor blades
28 are rotated and subjected to centrifugal forces, rotor blades 28 are also subjected to
various forces and moments. As such, rotor blades 28 may oscillate, deflect and/or
rotate from a neutral position, i.e. a non-deflected position to a deflected position. A
pitch adjustment system 38 is coupled to one or more rotor blades 28 for adjusting a
pitch angle or blade pitch of each rotor blade 28, i.e., an angle that determines a
perspective of rotor blade 28 with respect to direction 34 of the wind. Pitch
adjustment system 38 is configured to adjust a pitch of rotor blade 28 to control the
oscillation, load, and/or power generated by wind turbine 10.
[0016] In the exemplary embodiment, wind turbine 10 includes a
control system 40. Control system 40 includes a controller 42 that is coupled in
communication with one or more wind condition sensors 44. Each wind condition
sensor 44 is configured to sense one or more wind conditions at a location upwind of
wind turbine 10, and to transmit a signal indicative of the sensed wind condition to
controller 42. As used herein, the term "upwind" refers to a distance from wind
turbine 10 oriented in direction 34 of the wind. Wind condition sensors 44 are
configured to sense wind conditions such as, for example a wind speed, a wind
direction, a wind turbulence intensity, and/or a storm wind gust. In the exemplary
embodiment, control system 40 is coupled in operative communication to pitch
adjustment system 38 to control a pitch of rotor blades 28. Control system 40 is
configured to adjust a pitch of rotor blades 28 based, at least in part, on the sensed
wind condition upwind of wind turbine 10. In the exemplary embodiment, control
system 40 is positioned within nacelle 16. Alternatively, control system 40 may be a
distributed system throughout wind turbine 10, on support surface 14, within a wind
farm, and/or at a remote control center.
[0017] FIG. 2 is a schematic view of wind turbine 10. Identical
components shown in FIG. 2 are labeled with the same reference numbers used in
FIG. 1. In the exemplary embodiment, nacelle 16 includes rotor shaft 24, gearbox 20,
generator 18, and a yaw drive mechanism 46. Yaw drive mechanism 46 facilitates
rotating nacelle 16 and hub 26 on yaw axis 48 (shown in FIG. 1) to control the
perspective of rotor blade 28 with respect to direction 34 of the wind. Rotor shaft 24
extends between rotor 22 and gearbox 20. Hub 26 is coupled to rotor shaft 24 such
that a rotation of hub 26 about axis 36 facilitates rotating rotor shaft 24 about axis 36.
A high speed shaft 50 is coupled between gearbox 20 and generator 18 such that a
rotation of rotor shaft 24 rotatably drives gearbox 20 that subsequently drives high
speed shaft 50. High speed shaft 50 rotatably drives generator 18 to facilitate
production of electrical power by generator 18.
[0018] In the exemplary embodiment, control system 40 includes a
plurality of sensors 52 for detecting various conditions of wind turbine 10. Sensors
52 may include, but are not limited to only including, vibration sensors, acceleration
sensors, rotational speed sensors, displacement sensors, power output sensors, torque
sensors, position sensors, and/or any other sensors that sense various parameters
relative to the operation of wind turbine 10. As used herein, the term "parameters"
refers to physical properties whose values can be used to define the operating
conditions of wind turbine 10, such as a temperature, a generator torque, a power
output, a component load, a shaft rotational speed, and/or a component vibration at
defined locations. In the exemplary embodiment, at least one acceleration sensor 54
is coupled to rotor shaft 24 for sensing a rotational speed of rotor shaft 24 and
transmitting a signal indicative of the sensed rotational speed to controller 42. At
least one vibration sensor 56 is coupled to one or more wind turbine components such
as, for example, rotor blade 28, hub 26, rotor shaft 24, gearbox 20, and/or generator
18 for sensing a structural loading imparted to the wind turbine components during
operation of wind turbine 10 and transmitting a signal indicative of the sensed loading
to controller 42.
[0019] Generator 18 may be any suitable type of electrical generator,
such as, but not limited to, a wound rotor induction generator, a double-fed induction
generator (DFIG, also known as dual-fed asynchronous generators), a permanent
magnet (PM) synchronous generator, an electrically-excited synchronous generator,
and a switched reluctance generator. At least one power sensor 58 is coupled to
generator 18 for sensing a power output of generator 18 and transmitting a signal
indicative of the sensed power output to controller 42.
[0020] In the exemplary embodiment, generator 18 includes a stator
60 and a generator rotor 62 positioned adjacent stator 60 to define an air gap
therebetween. Generator rotor 62 includes a generator shaft 64 that is coupled to high
speed shaft 0 such that rotation of rotor shaft 24 drives rotation of generator rotor 62.
A torque of rotor shaft 24, represented by arrow 66, drives generator rotor 62 to
facilitate generating variable frequency AC electrical power from a rotation of rotor
shaft 24. Generator 18 imparts an air gap torque between generator rotor 62 and
stator 60 that opposes torque 66 of rotor shaft 24. At least one torque sensor 68 is
coupled to generator 18 for sensing an air gap torque between generator rotor 62 and
stator 60 and transmitting a signal indicative of the sensed air gap torque to controller
42. A power converter assembly 70 is coupled to generator 18 for converting the
variable frequency AC to a fixed frequency AC for delivery to an electrical load 72,
such as, for example a power grid that is coupled to generator 18. Power converter
assembly 70 is configured to adjust the air gap torque between generator rotor 62 and
stator 60 by adjusting a power current and/or power frequency distributed to stator 60
and generator rotor 62. Power converter assembly 70 may include a single frequency
converter or a plurality of frequency converters that are configured to convert
electricity generated by generator 18 to electricity suitable for delivery over the power
grid.
[0021] In the exemplary embodiment, control system 40 is coupled
to power converter assembly 70 to adjust an air gap torque between generator rotor 62
and stator 60. By adjusting the air gap torque, control system 40 adjusts a rotational
speed of rotor shaft 24 and adjusts a magnitude of loads imparted to various
components of wind turbine 10, such as, for example rotor shaft 24, rotor blade 28,
gearbox 20, and/or hub 26. In the exemplary embodiment, control system 40
transmits one or more torque commands and/or one or more power commands to
power converter assembly 70. Power converter assembly 70 generates a rotor current
based on the torque commands and/or the power commands received from control
system 40.
[0022] In the exemplary embodiment, controller 42 is a real-time
controller that includes any suitable processor-based or microprocessor-based system,
such as a computer system, that includes microcontrollers, reduced instruction set
circuits (RISC), application-specific integrated circuits (ASICs), logic circuits, and/or
any other circuit or processor that is capable of executing the functions described
herein. In one embodiment, controller 42 may be a microprocessor that includes read¬
only memory (ROM) and/or random access memory (RAM), such as, for example, a
32 bit microcomputer with 2 Mbit ROM and 64 Kbit RAM. Alternatively, controller
42 may be a connected network of micro-computer processing units (micro-CPU's)
over a distributed network. As used herein, the term "real-time" refers to outcomes
occurring at a substantially short period of time after a change in the inputs affect the
outcome, with the time period being a design parameter that may be selected based on
the importance of the outcome and/or the capability of the system processing the
inputs to generate the outcome.
[0023] In the exemplary embodiment, controller 42 includes a
memory area 74 that is configured to store executable instructions and/or one or more
operating parameters representing and/or indicating an operating condition of wind
turbine 10. Operating parameters may represent and/or indicate, without limitation, a
wind speed, a wind temperature, a torque loading, a power output, and/or a wind
direction. Controller 42 also includes a processor 76 that is coupled to memory area
74 and is programmed to determine an operation of one or more wind turbine control
devices 78, for example, pitch adjustment system 38 and power converter assembly
70, based, at least in part, on one or more operating parameters. In one embodiment,
processor 76 may include a processing unit, such as, without limitation, an integrated
circuit (IC), an application specific integrated circuit (ASIC), a microcomputer, a
programmable logic controller (PLC), and/or any other programmable circuit.
Alternatively, processor 76 may include multiple processing units (e.g., in a multicore
configuration).
[0024] In the exemplary embodiment, controller 42 includes a sensor
interface 80 that is coupled in signal communication with at least one sensor 52 such
as, for example, wind condition sensor 44, acceleration sensor 54, vibration sensor 56,
power sensor 58, and torque sensor 68. Each sensor 52 generates and transmits a
signal corresponding to an operating parameter of wind turbine 10. Moreover, each
sensor 52 may transmit a signal continuously, periodically, or only once, for example,
though other signal timings are also contemplated. Furthermore, each sensor may
transmit a signal either in an analog form or in a digital form. Controller 42 processes
the signal(s) by processor 76 to create one or more operating parameters. In some
embodiments, processor 76 is programmed (e.g., with executable instructions in
memory area 74) to sample a signal produced by sensor 52. For example, processor
76 may receive a continuous signal from sensor 52 and, in response, calculate an
operating parameter of wind turbine 0 based on the continuous signal periodically
(e.g., once every five seconds). In some embodiments, processor 76 normalizes a
signal received from sensor 52. For example, sensor 52 may produce an analog signal
with a parameter (e.g., voltage) that is directly proportional to an operating parameter
value. Processor 76 may be programmed to convert the analog signal to the operating
parameter. In one embodiment, sensor interface 80 includes an analog-to-digital
converter that converts an analog voltage signal generated by sensor 52 to a multi-bit
digital signal usable by controller 42.
[0025] Controller 42 also includes a control interface 82 that is
configured to control an operation of control device 78. In some embodiments,
control interface 82 is operatively coupled to one or more wind turbine control
devices 78, such as, for example pitch adjustment system 38 and power converter
assembly 70.
[0026] Various connections are available between control interface
82 and control device 78 and between sensor interface 80 and sensor 52. Such
connections may include, without limitation, an electrical conductor, a low-level
serial data connection, such as Recommended Standard (RS) 232 or RS-485, a highlevel
serial data connection, such as Universal Serial Bus (USB) or Institute of
Electrical and Electronics Engineers (IEEE) 1394 (a/k/a FIREWIRE), a parallel data
connection, such as IEEE 1284 or IEEE 488, a short-range wireless communication
channel such as BLUETOOTH, and/or a private (e.g., inaccessible outside wind
turbine 10) network connection, whether wired or wireless.
[0027] FIG. 3 is another perspective view of wind turbine 10.
Identical components shown in FIG. 3 are labeled with the same reference numbers
used in FIG. 2. In the exemplary embodiment, each wind condition sensor 44
includes a light detection and ranging device, also referred to as LIDAR. LIDAR is a
laser-based measurement device that is configured to scan an annular region around
wind turbine 10 to measure wind conditions based upon a reflection and/or a
scattering of light transmitted by the LIDAR from aerosol. Wind conditions are
measured within a cone angle (Q) and a range (R) that are selected based at least in
part on a predefined level of accuracy of measurement as well as measurement
sensitivity. In the exemplary embodiment, a LIDAR sensor 84 is mounted within hub
26 and/or an outer surface of hub 26, and is configured to measure wind conditions
within a predefined portion 86 of a planar field of measurement 88 that is defined by
cone angle (Q) and range (R) upwind of wind turbine 10. Alternatively, LIDAR
sensor 84 may be mounted within nacelle 16, and/or to an outer surface of nacelle 16.
In the exemplary embodiment, cone angle (Q) is measured from a centerline axis 90
defined by wind condition sensor 44. Range (R) is measured between wind condition
sensor 44 and planar field of measurement 88. Portion 86 of measurement field 88
may be oriented with respect to predefined sections of rotor blade 28 such as, for
example, sections near a tip end of each rotor blade 28 that contribute to an
aerodynamic torque of rotor blade 28. Alternatively, wind condition sensor 44 may
include a radio detection and ranging (RADAR) measuring device, a Doppler
RADAR, a sonic detection and ranging (SODAR) measuring device, or any suitable
measuring device that enables wind turbine 10 to function as described herein.
[0028] In the exemplary embodiment, control system 40 includes a
first LIDAR sensor 92 and a second LIDAR sensor 94. First LIDAR sensor 92 and
second LIDAR sensor 94 are each coupled to hub 26 and are configured to sense a
wind condition such as, for example wind speed, a wind direction, a wind turbulence
intensity, and/or a storm wind gust at a location upwind of wind turbine 10. In the
exemplary embodiment, first LIDAR sensor 92 is configured to sense a wind
condition at a first distance, i.e. a first range (Ri) and to transmit a signal indicative of
the sensed wind condition at first range \) to controller 42. Second LIDAR sensor
94 is configured to sense a wind condition at a second distance, i.e. a second range
(R2) that is greater than first range (Ri), and to transmit a signal indicative of the
sensed wind condition at second range (R2) to controller 42. Moreover, first LIDAR
sensor 92 senses a wind condition that is closer to wind turbine 10 than the sensed
wind condition from second LIDAR sensor 94 such that the sensed wind condition
from first LIDAR sensor 92 more accurately reflects a wind condition at wind turbine
10. In addition, a planar field of measurement 88 of first LIDAR sensor 92 is closer
to wind turbine 10 than a planar field of measurement 88 of second LIDAR sensor 94
such that first LIDAR sensor 92 includes an accuracy of measurement that is greater
than an accuracy of measurement from second LIDAR sensor 94.
[0029] During operation of wind turbine 10, first LIDAR sensor 92
transmits a signal indicative of a wind condition in a first field 96 defined at first
range ( . Controller 42 calculates a first wind turbine operating command based, at
least in part, on the sensed wind condition within first field 96 to facilitate increasing
a power output of wind turbine 10. In one embodiment, controller 42 calculates first
wind turbine operating command to facilitate reducing a loading imparted to wind
turbine components from wind forces. In the exemplary embodiment, second LIDAR
sensor 94 transmits a signal indicative of a wind condition in a second field 98
defined at second range (R2) that is farther upwind than first field 96. Controller 42
calculates a second wind turbine operating command based, at least in part, on the
sensed wind condition within second field 98 to facilitate preventing an overspeed of
wind turbine 10. In the exemplary embodiment, controller 42 calculates a collective
wind turbine operating command based, at least in part, on the first wind turbine
command and the second wind turbine command.
[0030] During low wind velocities, an increase in speed of the wind
may cause an increase in the rotational speed of rotor 22 and rotor shaft 24, which in
turn increases an electrical power output of generator 18. In some embodiments, the
electrical power output of generator 18 is allowed to increase with the increased wind
speed until a rated power output level is reached. As wind speed increases, controller
42 adjusts a pitch of rotor blade 28 such that a rotational speed of rotor shaft 24 and
the electrical power output of generator 18 are maintained substantially constant at
rated power output levels. In the exemplary embodiment, control system 40 is
configured to maintain and/or increase a power output of generator 18 based on
signals received from first LIDAR sensor 92. More specifically, controller 42
calculates the first wind turbine operating command based, at least in part, on the
sensed wind condition from first LIDAR sensor 92 to adjust a power output of
generator 18 to facilitate increasing a performance of wind turbine 10.
[0031] During a sudden gust of wind, wind speed may dramatically
increase within a relatively small interval of time. During such sudden gusts,
controller 42 adjusts a pitch of rotor blade 28 such that a rotational speed of rotor
shaft 24 is reduced to facilitate preventing an overspeed of rotor shaft 24 which may
increase loading on wind turbine 10 and cause damage to wind turbine components.
In the exemplary embodiment, control system 40 is configured to protect wind turbine
10 based on signals received from second LIDAR sensor 94. More specifically,
controller 42 calculates the second wind turbine operating command based, at least in
part, on the sensed wind condition from second LIDAR sensor 94 to reduce a
rotational speed of rotor shaft 24 to facilitate preventing an overspeed of wind turbine
10.
[0032] FIG. 4 is a schematic view of an exemplary load adjustment
system 100 that may be used with control system 40 to operate wind turbine 10. In
the exemplary embodiment, load adjustment system 100 includes a performance
module 102 and a protection module 104. Performance module 102 is configured to
increase a performance of wind turbine 0 by operating wind turbine 10 to increase a
power output of generator 18 and/or reduce a loading of wind turbine components.
Protection module 104 is configured to operate wind turbine 10 to reduce a rotational
speed of rotor shaft 24 to facilitate preventing an overspeed of wind turbine 10.
[0033] Performance module 102 is configured to utilize a sensed
wind condition within first field 96 from first LIDAR sensor 92 to generate a wind
turbine operating command that is configured to increase a power output of generator
18 and/or reduce a loading to wind turbine components. In the exemplary
embodiment, performance module 102 receives signals from acceleration sensor 54,
vibration sensor 56, power sensor 58, and/or torque sensor 68, and calculates a
generator speed based, at least in part, on the received signals. In addition,
performance module 102 receives signals indicative of an operating pitch command
(po) from pitch adjustment system 38, and receives a signal indicative of an operating
generator torque command (to) from power converter assembly 70. Performance
module 102 also receives a signal indicative of a wind condition at first range (Ri)
upwind of wind turbine 10 from first LIDAR sensor 92, and calculates a generator
speed based, at least in part, on the sensed wind condition.
[0034] In the exemplary embodiment, performance module 102
determines a generator speed error (eg) between a predefined generator speed and the
calculated generator speed, and calculates a generator adjustment (gi) to generate a
wind turbine operating command indicative of a required change in blade pitch angle
and/or air gap torque to reduce the error (e ) between the predefined generator speed
and the calculated generator speed. Alternatively, performance module 102 calculates
a component loading based on the sensed wind condition and determines a loading
error (CL) between a predefined component loading and the calculated component
loading. Performance module 102 calculates a loading adjustment (g2) to generate a
wind turbine operating command indicative of a required change in blade pitch angle
and/or air gap torque to reduce error (e
[0035] In the exemplary embodiment, a first pitch command
generator 106 calculates a first pitch command p ) based on the calculated generator
adjustment (gi), and transmits a signal indicative of the first pitch command (p to a
pitch command module 108. Similarly, a first generator torque command generator
110 generates a first torque command (ti) based on the calculated generator
adjustment (gi), and transmits a signal indicative of the first generator torque
command (ti) to a generator torque command module 112.
[0036] In the exemplary embodiment, protection module 104 is
configured to utilize a sensed wind condition within second field 98 from second
LIDAR sensor 94 to generate a wind turbine operating command that is configured to
reduce a rotational speed of rotor shaft 24 and/or generator 18 to facilitate preventing
an overspeed of wind turbine 10. Protection module 104 receives a signal indicative
of a wind condition at second range (R2) upwind of wind turbine 10 from second
LIDAR sensor 94, and calculates a rotor shaft speed and/or a generator speed based,
at least in part, on the sensed wind condition. Protection module 104 calculates a
protection adjustment (gp) to generate a wind turbine operating command indicative
of a required change in blade pitch angle and/or air gap torque to reduce a rotational
speed of rotor shaft 24 and/or reduce a rotational speed of generator 18 in advance of
a sudden change in wind speed. A second pitch command generator 14 calculates a
second pitch command (p2) based on the calculated protection adjustment (gp), and
transmits a signal indicative of the second pitch command (p2) to pitch command
module 108. A second generator torque command generator 1 6 generates a second
torque command (t2) based on the calculated protection adjustment (gp), and transmits
a signal indicative of the second generator torque command (t2) to generator torque
command module 112.
[0037] In the exemplary embodiment, first pitch command (p and
second pitch command (p2) are summed at pitch command module 108 to generate a
collective pitch command (pc). Pitch command module 108 transmits collective pitch
command (pc) to pitch adjustment system 38 to adjust a pitch of rotor blade 28 based
on collective pitch command (pc). In one embodiment, pitch command module 108
applies one or more weighting factors (a, b, and n-factor) to each first pitch command
(pi) and second pitch command (p2) to generate collective pitch command (pc).
Generator torque command module 112 calculates a collective generator torque
command (tc) based on a sum of first torque command (t\) and second torque
command (t2), and transmits collective generator torque command (tc) to power
converter assembly 70 to adjust an air gap torque of generator 18 based on collective
generator torque command (tc). In one embodiment, generator torque command
module 112 applies one or more weighting factors (a, b, and n-factor) to first torque
command (ti) and to second torque command (t ) to generate collective generator
torque command (tc).
[0038] During operation of wind turbine 10, controller 42 receives
from first LIDAR sensor 92 signals that are indicative of a first wind condition at first
range (Ri) and receives from second LIDAR sensor 94 signals that are indicative of a
second wind condition at second range (R2) that is farther from wind turbine 10 than
first range (R]). Controller 42 is configured to calculate a wind turbine operating
command based at least in part on the sensed first wind condition and the sensed
second wind condition. Controller 42 is also configured to calculate a blade pitch
command based, at least in part, on the sensed first wind condition and the sensed
second wind condition, and to operate pitch adjustment system 38 to adjust the pitch
of rotor blade 28 based on the calculated blade pitch command.
[0039] In one embodiment, controller 42 is configured to calculate a
first blade pitch command signal based, at least in part, on the sensed first wind
condition to facilitate increasing a performance of wind turbine 10. Controller 42 is
also configured to calculate a second blade pitch command signal based, at least in
part, on the sensed second wind condition to facilitate preventing an overspeed of
wind turbine 10. In this embodiment, controller 42 is configured to calculate a
collective blade pitch command based, at least in part, on the calculated first blade
pitch command and the calculated second blade pitch command, and to operate pitch
adjustment system 38 to adjust the pitch of rotor blade 28 based on the calculated
collective blade pitch command. In an alternative embodiment, controller 42
calculates the second blade wind turbine operating command signal when the sensed
second wind condition is different than a predetermined wind condition.
[0040] In the exemplary embodiment controller 42 is configured to
generate a pitch command signal for each rotor blade 28. In one embodiment,
controller 42 is configured to generate the same pitch command signal for each rotor
blade 28. Alternatively, controller 42 is configured to generate a different pitch
command signal for each rotor blade 28. In the exemplary embodiment, control
system 40 is configured to adjust a pitch of each rotor blade 28 at the same time
period and to adjust a pitch of each rotor blade 28 at a different time period.
[0041] In the exemplary embodiment, controller 42 is configured to
calculate a generator torque command based at least in part on the sensed first wind
condition and the sensed second wind condition. Controller 42 is also configured to
operate generator 18 to adjust an air-gap toque of generator 18 based on the calculated
generator torque command. In one embodiment, controller 42 is configured to
calculate a first generator torque command signal based at least in part on the sensed
first wind condition, and to calculate a second generator torque command signal based
at least in part on the sensed second wind condition. In this embodiment, controller
42 is also configured to calculate a collective generator torque command based at
least in part on the calculated first blade pitch command and the calculated second
blade pitch command, and to operate generator 18 to adjust an air-gap toque of
generator 18 based on the calculated collective generator torque command.
[0042] FIG. 5 is a flow chart illustrating an exemplary method 200 of
operating wind turbine 10. In the exemplary embodiment, method 200 includes
transmitting 202, from first LIDAR sensor 92 to controller 42, at least a first
monitoring signal indicative of a first wind condition at first range i upwind from
wind turbine 10. At least a second monitoring signal indicative of a second wind
condition at second range (R2) is transmitted 204, by second LIDAR sensor to
controller 42. Controller 42 operates 206 one or more wind turbine components based
on the first monitoring signal and the second monitoring signal. In one embodiment,
controller 42 calculates 208 a first wind turbine operating command based, at least in
part, on the first monitoring signal to facilitate increasing a performance of the wind
turbine 10, and calculates 210 a second wind turbine operating command based, at
least in part, on the second monitoring signal to facilitate preventing an overspeed of
wind turbine 10. Controller 42 also calculates 212 a collective operating command
based, at least in part, on the calculated first wind turbine operating command and the
calculated second wind turbine operating command. Controller 42 also operates 214
one or more wind turbine components based on the calculated collective wind turbine
operating command.
[0043] In an alternative embodiment, controller 42 calculates a first
blade pitch command signal based, at least in part, on the sensed first wind condition,
and calculates a second blade pitch command signal based, at least in part, on the
sensed second wind condition. Controller 42 calculates a collective blade pitch
command based, at least in part, on the calculated first blade pitch command and the
calculated second blade pitch command, and operates pitch adjustment system 38 to
adjust a pitch of rotor blade 28 based on the calculated collective blade pitch
command.
[0044] In another alternative embodiment, controller 42 calculates a
first generator torque command signal based on the sensed first wind condition, and
calculates a second generator torque command signal based on the sensed second
wind condition. Controller 42 also calculates a collective generator torque command
based on the calculated first generator torque command and the calculated second
generator torque command, and operates generator 18 to adjust an air gap torque
based on the calculated collective generator torque command.
[0045] An exemplary technical effect of the method, system, and
apparatus described herein includes at least one of: (a) transmitting, from a first sensor
to a control system, at least a first monitoring signal indicative of a first wind
condition at a first distance from the wind turbine in the direction of the wind; (b)
transmitting, from a second sensor to the control system, at least a second monitoring
signal indicative of a second wind condition at a second distance from the wind
turbine in the direction of the wind that is larger than the first distance; (c) calculating,
by the control system, a wind turbine operating command based at least in part on the
first monitoring signal and the second monitoring signal; and (d) operating one or
more wind turbine components based on the calculated wind turbine operating
command.
[0046] The above-described method, system, and apparatus facilitate
adjusting a pitch of a rotor blade based on a sensed wind condition upwind of the
wind turbine. Moreover, the embodiments described herein facilitate calculating a
pitch adjustment based, at least in part, on a sensed wind condition at two locations
upwind of the wind turbine to prevent an overspeed of the wind turbine. By
calculating the pitch angle based on the sensed wind condition upwind of the wind
turbine, the above-described method, system, and apparatus overcome the problem of
known wind turbines that rely on wind speed that are adversely affected by the
rotation of the rotor. As such, the embodiments described herein facilitate improving
the operation of the wind turbine to increase the annual energy production of the wind
turbine.
[0047] Exemplary embodiments of a method, system, and apparatus
for controlling a wind turbine are described above in detail. The systems and methods
are not limited to the specific embodiments described herein, but rather, components
of the system and/or steps of the methods may be utilized independently and
separately from other components and/or steps described herein. For example, the
methods may also be used in combination with other rotating systems, and are not
limited to practice with only the wind turbine system as described herein. Rather, the
exemplary embodiment can be implemented and utilized in connection with many
other rotating system applications.
[0048] Although specific features of various embodiments of the
invention may be shown in some drawings and not in others, this is for convenience
only. In accordance with the principles of the invention, any feature of a drawing
may be referenced and/or claimed in combination with any feature of any other
drawing.
[0049] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person skilled in the art to
practice the invention, including making and using any devices or systems and
performing any incorporated methods. The patentable scope of the invention is
defined by the claims, and may include other examples that occur to those skilled in
the art. Such other examples are intended to be within the scope of the claims if they
have structural elements that do not differ from the literal language of the claims, or if
they include equivalent structural elements with insubstantial differences from the
literal language of the claims.

WHAT S CLAIMED IS:
1. A method of operating a wind turbine, the wind turbine
including a rotor rotatably coupled to a generator positioned within a nacelle, the rotor
including one or more rotor blades coupled to a hub, said method comprising:
transmitting, from a first sensor to a control system, at least a first
monitoring signal indicative of a first wind condition at a first distance from the wind
turbine;
transmitting, from a second sensor to the control system, at least a
second monitoring signal indicative of a second wind condition at a second distance
from the wind turbine that is longer than the first distance;
calculating, by the control system, a wind turbine operating command
based at least in part on the first monitoring signal and the second monitoring signal;
and,
operating one or more wind turbine components based on the
calculated wind turbine operating command.
2. A method in accordance with claim 1, further comprising:
calculating a first wind turbine operating command based at least in
part on the first monitoring signal to facilitate increasing a performance of the wind
turbine;
calculating a second wind turbine operating command based at least in
part on the second monitoring signal to facilitate reducing an overspeed of the wind
turbine; and,
calculating a collective operating command based at least in part on the
calculated first wind turbine operating command and the calculated second wind
turbine operating command.
3. A method in accordance with claim 2, further comprising
calculating the second wind turbine operating command signal when the second wind
condition is different than a predefined wind condition.
4. A method in accordance with claim 1, further comprising
sensing a first wind condition and a second wind condition with one or more light
detection and ranging (LIDAR) devices.
5. A method in accordance with claim 1, wherein the wind
condition includes one of a wind speed, a wind direction, a wind turbulence intensity,
and a wind gust.
6 . A method in accordance with claim , wherein the wind turbine
includes a pitch control system coupled to at least one rotor blade, said method further
comprises:
calculating a first blade pitch command based at least in part on the
first monitoring signal;
calculating a second blade pitch command based at least in part on the
second monitoring signal;
calculating a collective blade pitch command based at least in part on
the calculated first blade pitch command and the calculated second blade pitch
command; and,
operating the pitch control system to adjust the pitch of the rotor blade
based on the calculated collective blade pitch command.
7. A method in accordance with claim 1, further comprising:
calculating a first generator torque command based at least in part on
the first monitoring signal;
calculating a second generator torque command based at least in part
on the second monitoring signal;
calculating a collective generator torque command based at least in
part on the calculated first generator torque command and the calculated second
generator torque command; and,
operating the generator to adjust an air-gap torque of the generator
based on the calculated collective generator torque command.
8. A wind turbine control system for use with a wind turbine, the
wind turbine including a rotor rotatably coupled to a generator positioned within a
nacelle, the rotor including one or more rotor blades coupled to a hub, said wind
turbine control system comprising:
a first sensor configured to sense a first wind condition at a first
distance from the wind turbine;
a second sensor configured to sense a second wind condition at a
second distance from the wind turbine that is longer than the first distance; and,
a controller coupled to said first sensor and said second sensor, said
controller configured to calculate a wind turbine operating command based at least in
part on the sensed first wind condition and the sensed second wind condition.
9 . A wind turbine control system in accordance with claim 8,
wherein said wind turbine includes a pitch control system coupled to at least one rotor
blade, said controller coupled to said pitch control system and configured to:
calculate a blade pitch command based at least in part on the sensed
first wind condition and the sensed second wind condition; and,
adjust the pitch of the rotor blade based on the calculated blade pitch
command.
10. A wind turbine control system in accordance with claim 9,
wherein said controller is further configured to:
calculate a first blade pitch command based at least in part on the
sensed first wind condition;
calculate a second blade pitch command based at least in part on the
sensed second wind condition; and,
calculate a collective blade pitch command based at least in part on the
calculated first blade pitch command and the calculated second blade pitch command.
11. A wind turbine control system in accordance with claim 8,
wherein said controller is coupled to the generator and is configured to:
calculate a generator torque command based at least in part on the
sensed first wind condition and the sensed second wind condition; and,
adjust an air-gap torque of the generator based on the calculated
generator torque command.
12. A wind turbine control system in accordance with claim 11,
wherein said controller is further configured to:
calculate a first generator torque command based at least in part on the
sensed first wind condition;
calculate a second generator torque command based at least in part on
the sensed second wind condition; and,
calculate a collective generator torque command based at least in part
on the calculated first blade pitch command and the calculated second blade pitch
command.
13. A wind turbine control system in accordance with claim 8,
wherein each of said first sensor and said second sensor comprises at least one of light
detection and ranging (LIDAR) device, a radio detention and ranging (RADAR)
device, and a sonic detection and ranging (SODAR) device.
14. A wind turbine control system in accordance with claim 8,
wherein the wind condition includes at least one of a wind speed, a wind direction, a
wind turbulence intensity, and a wind gust.
15. A wind turbine system, comprising:
a tower;
a nacelle coupled to said tower;
a generator positioned within said nacelle;
a rotor coupled to said generator with a rotor shaft;
at least one rotor blade coupled to said rotor; and,
a wind turbine control system comprising:
a first sensor configured to sense a first wind condition at a first
distance from the wind turbine;
a second sensor configured to sense a second wind condition at
a second distance from the wind turbine that is longer than the first distance; and,
a controller coupled to said first sensor and said second sensor,
said controller configured to calculate a wind turbine operating command based at
least in part on the sensed first wind condition and the sensed second wind condition.
16. A wind turbine system in accordance with claim 15, wherein
each of said first sensor and said second sensor comprises at least one of a LIDAR
device, a RADAR device, and a SODAR device.
17. A wind turbine system in accordance with claim 15, further
comprising a pitch control system coupled to said at least one rotor blade, said
controller coupled to said pitch control system and configured to:
calculate a blade pitch command based at least in part on the sensed
first wind condition and the sensed second wind condition; and,
adjust the pitch of the rotor blade based on the calculated blade pitch
command.
18. A wind turbine system in accordance with claim 17, wherein
said controller is further configured to:
calculate a first blade pitch command based at least in part on the
sensed first wind condition;
calculate a second blade pitch command based at least in part on the
sensed second wind condition; and,
calculate a collective blade pitch command based at least in part on the
calculated first blade pitch command and the calculated second blade pitch command.
19. A wind turbine system in accordance with claim 15, wherein
said controller is coupled to said generator and is configured to:
calculate a generator torque command based at least in part on the
sensed first wind condition and the sensed second wind condition; and,
adjust an air-gap torque of the generator based on the calculated
generator torque command.
20. A wind turbine system in accordance with claim 19, wherein
said controller is further configured to:
calculate a first generator torque command based at least in part on the
sensed first wind condition;
calculate a second generator torque command based at least in part on
the sensed second wind condition; and,
calculate a collective generator torque command based at least in part
on the calculated first blade pitch command and the calculated second blade pitch
command.