[DESCRIPTION]
[Title of Invention]
POWER OUTPUT LEVELING METHOD AND APPARATUS FOR WIND TURBINE
GENERATING FACILITY
5
[Technical Field]
[0001]
The present invention relates to a power output leveling method and a power
output leveling apparatus for a wind turbine generator facility.
10
[Background Art]
[0002]
There are a variety of methods for leveling the power output of the wind
turbine generator facility, which fluctuates depending on a wind speed. For instance,
15 Patent Literature 1 discloses a method for controlling the fluctuation in power output
in a wind turbine generator facility when the power output of the wind turbine
generator facility increases. The method of Patent Literature 1. includes the steps of
increasing rotation speed of a rotor, storing surplus power output as rotation energy
and performing pitch control such as not to exceed a prescribed rotation speed.
20
[Citation List]
[Patent Literature]
[0003]
[PTL 1]
25 JP 11-082282A
[Summary of Invention]
[Technical Problem]
[0004]
30 In the wind turbine generator facility of Patent Literature 1, the pitch control
is performed to feather the blade so as to reduce the rotation speed. As a result, the
wind energy that is available to be converted into electric power is partially lost and
thus, it may be difficult to achieve a desired power output.
An electric power supplier supplies electric power produced in the wind turbine
35 generator facility to consumers. The electric power supplier sets a target output in a
set period of time. The profit of the electric power supplier depends on whether or
1-
not the target output is achieved. Therefore, a method of leveling power output as
well as increasing power production, is desired.
[0005]
It is an object of the present invention is provide power output leveling method
5 and apparatus for a wind turbine generator, which can level the power output and
increase power production as well.
[Solution to Problem]
[0006]
To solve the problems above, an aspect of the present invention is a power
10 output leveling method for adjusting an output of a wind turbine generator facility in
which a wind turbine generator is combined with a secondary battery to a target
output. The power output leveling method includes the steps of: measuring an
output of the wind turbine generator; calculating a target-output achievement rate
that is a rate of an integrated value of the measured outputs of the wind turbine
15 generator from a starting point of a set period of time to a prescribed point within the
set period of time with respect to a target output in the set period of time; and
selecting an operation mode of the wind power facility. In the step of selecting the
operation mode, when the target-output achievement rate is below a first threshold, a
pitch-control invalid operation mode may be selected. In the pitch-control invalid
20 operation mode a pitch control for leveling the output to reduce surplus output of the
wind turbine generator with respect to the target output is invalid and at least one of
charging in the secondary battery and storing rotation energy of the wind turbine
generator is performed.
The target output in the set period of time is, for instance, annual power
25 production of an electric power supplier, which is produced by the wind turbine
generator facility and supplied to consumers.
The prescribed point within the set period of time may be a mid-point or the
end of the set period of time. For instance, monthly target outputs are set, "set
period of time" being one month, "prescribed point within the set period of time" being
30 a point which is one month past the starting point, and a monthly target-output
achievement rate may be monitored repeatedly. Alternatively, annual target outputs
are set, "set period of time" being one year, "prescribed point within the set period of
time" being a point which is n month past the starting point (n is a natural number),
and the target-output achievement rate may be monitored repeatedly every n month.
35 [0007]
In this manner, the target-output achievement rate is calculated based on the
2
measured output of the wind turbine generator. When the target-output
achievement rate is below the first threshold, the pitch control for leveling the output
to reduce surplus output of the wind turbine generator with respect to the target
output is invalid and at least one of charging in the secondary battery and storing
5 rotation energy of the wind turbine generator is performed. Thus, the pitch control
to feather the blades is performed less often. As a result, the amount of wind energy
lost without being converted into electric energy is reduced, thereby generating more
electrical energy.
The pitch angle herein refers to an angle formed between a blade chord and a
10 rotor plane for rotation. When the blade angle is large, the wind passes through and
the energy that the rotor extracts from the wind decreases. Thus, the pitch control
to reduce surplus output of the wind turbine generator with respect to the target
output refers to a pitch control to reduce the output of the wind turbine generator by
increasing the pitch angle of the blade.
15 [0008]
In the step of selecting the operation mode, when the target-output
achievement rate is not less than the first threshold, a pitch-control permitted
operation mode may be selected. In the pitch-control permitted operation mode, the
pitch control is performed to reduce the surplus output of the wind turbine generator
20 with respect to the target output.
In this manner, in the pitch-control permitted operation mode, the pitch
control is permitted to reduce the surplus output of the wind turbine generator.
Thus, depending on the state of the secondary battery, charging of the surplus output
of the wind turbine generator into the secondary battery may be avoided and instead
25 the pitch control may be performed to reduce the number of times of charging into the
secondary battery, thereby extending the life of the secondary battery. Further, it is
possible to reduce load on the secondary battery for leveling the power output and
thus, inexpensive secondary battery with small capacity may be used.
[0009]
30 When pitch-control permitted operation mode is selected in the operation mode
selecting step, a step of calculating a loss rate is also provided. The loss rate is a
rate of an amount of power loss due to the pitch control to an ideal output that is
obtained based on a wind speed according to a performance curve of the wind turbine
generator representing a relationship between the wind speed and the ideal output of
35 the wind turbine generator. When the calculated loss rate is not less than a second
threshold, the operation mode may be switched from the pitch-control permitted
operation mode to the pitch-control invalid operation mode.
Even if the target-output achievement rate at a point is not less than the first
threshold and there is comparatively sufficient power production, the wind speed and
the wind direction changes and thus, it does not assure the power production can be
5 kept positively after achieving the threshold once in order to achieve the target
output. Therefore, when the loss rate is not less than the second threshold, even if
the target-output achievement rate is not less than the first threshold and the pitchcontrol
permitted operation mode is selected, the operation mode is switched to the
pitch-control invalid mode, thereby performing the pitch control for reducing the
10 surplus output of the wind turbine generator less frequently. Thus, it is easy to
achieve the target output in the set period of time.
The power curve of the wind turbine generator is a performance curve of the
wind turbine generator representing a relationship between the wind speed and the
ideal output of the wind turbine generator and is used to calculate the ideal output at
15 the measured wind speed by applying the measured wind speed to the curve.
[0010]
The power output leveling method further includes the step of obtaining a
deterioration level of the secondary battery. When the obtained deterioration level of
the secondary battery exceeds a third threshold, charging and discharging of the
20 rotation energy of the wind turbine generator may be performed with higher priority
than charging and discharging of the secondary battery, so as to reduce the surplus
output or supply insufficient output with respect to the target output.
In this manner, the deterioration level of the secondary battery is obtained and
the obtained deterioration level is compared with the third threshold that is set in
25 advance. When the deterioration level exceeds the third threshold, storing or
discharging of the rotation energy of the wind turbine generator is performed with
higher priority than charging or discharging of the secondary battery so as to reduce
the number of times that the secondary battery is charged. In this manner, it is
possible to prevent the life of the secondary battery from decreasing. Further, it is
30 possible to reduce load on the secondary battery for leveling the power output and
thus, inexpensive secondary battery with small capacity may be used.
[0011]
The deterioration level of the secondary battery may be at least one of the
number of charge-discharge cycles, the number of total charge-discharge cycles and
35 the number of charge-discharge rates.
[0012]
4
The power output leveling method may also include a step of obtaining a
remaining capacity of the secondary battery. When the obtained remaining capacity
of the secondary battery is not in a set range, charging and discharging of the
secondary battery may be performed with higher priority than charging and
5 discharging of the rotation energy of the wind turbine generator, so as to reduce the
surplus output or supply insufficient output with respect to the target output.
In this manner, the remaining capacity of the secondary battery is obtained
and when the remaining capacity is not in the set range, charging and discharging of
the secondary battery is performed with higher priority than charging and
10 discharging of the rotation energy of the wind turbine generator so as to keep the
remaining capacity in an adequate range. This prevents the life of the secondary
battery from decreasing. Further, it is possible to maintain the remaining capacity
within the prescribed range and thus, inexpensive secondary battery with small
capacity can be used.
15 [00131
The power output leveling method also include a first target output modifying
step of modifying the target output temporarily so as to reduce a difference between
the output of the wind turbine generator and the target output, when the obtained
deterioration level of the secondary battery exceeds the third threshold.
20 In this manner, when the obtained deterioration level of the secondary battery
exceeds the third threshold, the target output is modified temporarily so as to reduce
the difference between the output of the wind turbine generator and the target output.
Thus, it is possible to sufficiently perform leveling of the power output more often by
a method other than charging and discharging of the secondary batter (mainly by
25 storing and discharging of the rotation energy of the wind turbine generator). As a
result, it is possible to reduce the number of times that the secondary battery is
charged or discharged, thereby extending the life of the secondary battery. Further,
it is possible to reduce load on the secondary battery for leveling the power output
and thus, inexpensive secondary battery with small capacity may be used.
30 [0014]
The power output leveling method may also in clued a second target output
modifying step of increasing the target output when the target-output achievement
rate is less than the first threshold.
In this manner, the target output is increased so as to reduce the amount of
35 wind energy lost without being converted into electric energy.
[0015]
The power output leveling method may further include a step of obtaining a
frequency of a grid to which the wind turbine generator and the secondary battery are
connected, and a third target output modifying step of reducing the target output
when the obtained frequency exceeds a set upper limit whereas increasing the target
5 output when the obtained frequency becomes less than a set lower limit.
In this manner, when the obtained frequency exceeds the set upper limit, the
target output is reduced, thereby preventing the frequency of the grid from increasing.
When the obtained frequency becomes lower than the lower limit of the set range, the
target output is increased, thereby preventing the frequency of the grid from
10 decreasing. Therefore, it is possible to control the frequency of the grid within the
set range.
[0016]
Another aspect of the present invention is a power output leveling apparatus of
adjusting an output of a wind turbine generator facility in which a secondary battery
15 is combined with a wind turbine generator to a target output. The power output
leveling apparatus includes: an output measuring unit which measures an output of
the wind turbine generator; a calculation unit which calculates a target-output
achievement rate that is a rate of an integrated value of the measured outputs of the
wind turbine generator from a starting point of a set period of time to a prescribed
20 point within the set period of time with respect to a target output in the set period of
time; and an operation mode selection unit which selects a pitch-control invalid
operation mode when the target-output achievement rate is below a first threshold.
In the pitch-control invalid operation mode, a pitch control for leveling the output to
reduce surplus output of the wind turbine generator with respect to the target output
25 is invalid and at least one of charging into the secondary battery and storing rotation
energy of the wind turbine generator is performed.
According to the above power output leveling apparatus, the target-output
achievement rate is calculated from the measured output of the wind turbine
generator, and when the calculated target-output achievement rate is below the first
30 threshold, the pitch control for leveling the output to reduce surplus output of the
wind turbine generator with respect to the target output is invalid and at least one of
charging into the secondary battery and storing rotation energy of the wind turbine
generator is performed. Thus, the pitch control to feather the blades is performed
less often. As a result, the amount of wind energy lost without being converted into
35 electric energy is reduced, thereby generating more electrical energy.
[0017]
Another aspect of the present invention is a power output leveling method for
adjusting an output of a wind turbine generator facility in which a secondary battery
is combined with a wind turbine generator to a target output. The power output
leveling method includes the steps of measuring an output of the wind turbine
5 generator; calculating a loss rate that is a rate of an amount of power loss due to the
pitch control to an ideal output that is obtained based on a wind speed according to a
performance curve of the wind turbine generator representing a relationship between
the wind speed and the ideal output of the wind turbine generator; and selecting an
operation mode of the wind power facility. In the step of selecting the operation
1.0 mode, when the loss rate is below a second threshold, a pitch-control invalid operation
mode is selected. In the pitch-control invalid operation, a pitch control for leveling
the output to reduce surplus output of the wind turbine generator with respect to the
target output is invalid and at least one of charging into the secondary battery and
storing rotation energy of the wind turbine generator is performed.
15 [0018]
According to the above power output leveling method, the loss rate is
calculated from the measured output of the wind turbine generator and when the
calculated loss rate is below the second threshold that is set in advance, the pitch
control for leveling the output to reduce surplus output of the wind turbine generator
20 with respect to the target output is invalid and at least one of charging into the
secondary battery and storing rotation energy of the wind turbine generator is
performed. Thus, the pitch control to feather the blades is performed less often. As
a result, the amount of wind energy lost without being converted into electric energy
is reduced, thereby generating more electrical energy.
25 [Advantageous Effects of Invention]
[0019]
According to the present invention, in order to reduce surplus output of the wind
turbine generator with respect to the target output, when the target-output
achievement rate is below the first threshold, the pitch-control invalid operation mode
30 is selected based on the target-output achievement rate or the loss rate. In the
pitch-control invalid operation mode, a pitch control for leveling the output to reduce
surplus output of the wind turbine generator with respect to the target output is
invalid and at least one of charging in the secondary battery and storing rotation
energy of the wind turbine generator is performed. Thus, the pitch control to feather
35 the blades is performed less often. As a result, the amount of wind energy lost
without being converted into electric energy is reduced, thereby generating more
7
electrical energy.
[Brief Description of Drawings]
[0020]
5 [FIG.1]
FIG.1 illustrates an overall structure of a power output leveling apparatus for
a wind turbine generator facility in relation to a first preferred embodiment of the
present invention.
[FIG.2]
10 FIG.2 is a control block diagram for reducing surplus output of the wind
turbine generator when a pitch - control invalid operation mode is selected.
[FIG.3]
FIG.3 is a control block diagram for supplying insufficient output of the wind
turbine generator when the pitch-control invalid operation mode or a pitch-control
15 permitted operation mode is selected.
[FIG.4l
FIG.4 is a control block diagram for reducing surplus output of the wind
turbine generator when the pitch-control permitted operation mode is selected.
[FIGS]
20 FIG.5 shows embodiments in which control is performed by an overall control
unit of a master controller.
[FIG.6]
FIG.6 is a control flow diagram showing a control flow of selecting the pitchcontrol
invalid operation mode and the pitch-control permitted operation mode.
25 [FIG.7]
FIG.7 is a control flow diagram showing a control by the overall control unit
when the pitch-control invalid operation mode is selected.
[FIG.8l
FIG.8 is a control flow diagram showing a control by the overall control unit
30 when the pitch-control permitted operation mode is selected.
[Description of Embodiments]
[0021]
A preferred embodiment of the present invention will now be described in
35 detail with reference to the accompanying drawings. It is intended, however, that
unless particularly specified, dimensions, materials, shape, its relative positions and
the like shall be interpreted as illustrative only and not limitative of the scope of the
present invention.
FIG.1 illustrates an overall structure of a power output leveling apparatus for
5 a wind turbine generator facility in relation to a first preferred embodiment of the
present invention.
FIG.1 shows the wind turbine generator facility 1 having a wind turbine
generator 2, an electrical storage device 3 and a power output leveling apparatus 4.
The wind turbine generator facility 1 is connected to a grid 6 via a grid
10 interconnection part 5. The wind turbine generator 2 and the secondary battery are
connected in parallel to the grid interconnection part 5.
[0022]
The wind turbine generator 2 is a wind turbine system equipped with a socalled
super- synchronous scherbius induction generator which is configured such that
15 electric power produced by a generator 9 is available to be outputted to the grid 6 via
an electric transformer 8 and a grid interconnection part 5 from both of a stator coil
SC and a rotor coil RC. Specifically, the stator coil SC of the generator 9 is directly
connected to the grid 6 and the rotor coil RC is connected to the grid 6 via an inverter
unit 14. Although simplified in FIG.1, an electric wire from the stator coil SC to the
20 grid 6 and an electric wire from the rotor coil RC through the inverter unit 14 to the
grid 6 are practically three-phase three-wire system.
A rotor 52 having blades 52B installed to a hub 52A is coupled to the generator
9 via a gearbox (not shown). The rotation of the rotor 52 produced by wind power is
inputted to the generator 9.
25 [0023]
The inverter unit 14 includes a generator-side inverter 18A, a DC bus 18B and
a grid-side inverter 18C. The inverter unit 14 converts AC power from the rotor coil
RC into AC power compatible with a frequency of the grid 6. The generator-side
inverter 18A converts the DC power generated in the rotor coil RC into DC power so
30 as to output the AC power to the DC bus 18B. The grid-side inverter 18C controls
voltage of the DC bus 18B to perform supply and demand with the grid side. That is,
the grid-side inverter 18C converts the DC power from the DC bus 18B into the AC
power of the same frequency as the grid 6, and outputs the AC power to the grid 6.
The generator-side inverter 18A controls electric power outputted to the grid 6 from
35 the generator 9.
FIG.I illustrates an exemplary case where the wind turbine generator 2 is a
wind power turbine system equipped with the super-synchronous scherbius induction
generator. However, this is not limitative and the wind turbine generator may be
configured such that the generator is a heteropolar synchronous generator and the
stator coil is connected to the grid via an inverter unit formed by an inverter and a
5 converter.
[0024]
The output of the wind turbine generator 2 can be adjusted by controlling a
power transistor of the generator-side inverter 18A based on a control signal from a
rotation energy control unit 25 of a wind turbine controller 20. The wind turbine
10 controller 20 is described in details later.
For instance, in order to reduce the output of the wind turbine generator 2, the
generator-side inverter 18A of the inverter unit 14 is controlled by the rotation energy
control unit 25 to reduce one of torque and output of the generator, and the wind
power acting on the blades 52B is converted into rotation energy of the wind turbine
15 generator 2 and stored, thereby adjusting the output.
On the other, in order to increase the output of the wind turbine generator 2,
the generator-side inverter 18A of the inverter unit 14 is controlled by the rotation
energy control unit 25 to increase one of torque and output of the generator, and the
rotation energy of the wind turbine generator 2 is converted into electric energy and
20 recovered.
[0025]
The electrical storage device 3 of the wind turbine generator facility 1 includes
a secondary battery 10, a DC-AC converter 11, a transformer 12 and a battery
condition detection unit 31.
25 The electrical storage device 3 converts AC power produced in the wind turbine
generator 2 into DC power by the DC-AC converter 11 to store the DC power, converts
discharged DC power into AC power by the DC-AC converter 11, and after the
transformer 23 transforms the AC power to a prescribed voltage, the AC power is
supplied to the grid 6 via the grid interconnection part 5.
30 [0026]
The grid interconnection part 5 is provided to connect the wind turbine
generator facility 1 to the grid 6. Based on conditions of grid, interconnection
between the grid interconnection part 5 and the grid 6, a variety of adjustment of
supply power is performed. For instance, the grid interconnection conditions include
35 a condition to set the voltage and fluctuation at an interconnection point within a
permissible range. Further, the grid interconnection part 5 may include a
-10-
transformer 13.
The grid 6 herein refers to a group of devices for supplying the power output
produced in the power generating facility to consumers via an electric power cable
and an electric power substation. In this embodiment, the grid 6 refers to a
5 commercial power grid from which general consumers receive electric power.
[0027]
The power output leveling apparatus 4 includes a wind turbine controller 20
which controls output of the wind turbine generator 2, a battery controller 30 which
controls the electrical storage device 3, and a master controller 40 which gives
10 commands to the wind turbine controller 20 and the battery controller 30 respectively.
In the power output leveling apparatus 4, the output of the wind turbine generator 2
is leveled and adjusted to the target output. Each component of the power output
leveling apparatus 4 is described in details below.
[0028]
15 The master controller 40 includes an achievement rate calculation unit 45, an
achievement rate monitoring unit 41, an operation mode selection unit 42, a loss rate
calculation unit 43, a loss rate monitoring unit 44, a grid monitoring unit 46 and an
overall control unit 48.
[0029]
20 The achievement rate calculation unit 45 calculates an integrated value of
measured outputs of the wind turbine generator 2 from a starting point of a set period
of time to a prescribed point within the set period of time. The integrated value is
divided by a target output in the set period of time to calculate a target-output
achievement rate.
25 The achievement rate monitoring unit 41 monitors constantly or periodically
whether or not the target-output achievement rate calculated by the achievement rate
calculation unit 45 is not less than a first threshold that is set in advance and the
results is outputted to the operation mode selection unit 42.
The operation mode selection unit 42 selects one of a pitch-control invalid
30 operation mode and a pitch-control permitted operation mode based on a signal from
the achievement rate monitoring unit 41. Specifically, when the target-output
achievement rate is below the first threshold, the pitch-control invalid. operation mode
is selected. In the pitch-control invalid operation mode, a pitch control for leveling
the output to reduce surplus output of the wind turbine generator 2 with respect to
35 the target output is invalid and at least one of charging of the secondary battery 10
and storing of rotation energy of the wind turbine generator 2 is performed. When
-11-
the target-output achievement rate is not less than the first threshold, the pitchcontrol
permitted operation mode is selected. In the pitch-control permitted
operation mode, the pitch control is performed to reduce the surplus output of the
wind turbine generator 2 with respect to the target output.
5 [0030]
The loss rate calculation unit 43 calculates a loss rate by dividing an amount of
power loss due to the pitch control by an ideal output obtained based on a wind speed
according to a power curve of the wind turbine generator 2, and the calculation result
is outputted to the loss rate monitoring unit 44. The amount of power loss due to the
10 pitch control can be obtained as a difference between an actual output obtained from
the measured output of the wind turbine generator 2 measured by an output
measuring unit 15 and the ideal output. The amount of power loss is the amount of
wind energy that was available for power generation but lost due to the pitch control.
[0031]
15 The loss rate monitoring unit 44 constantly or periodically monitors whether or
not the loss rate calculated by the loss rate calculation unit 43 is not less than a
second threshold that is set in advance and the monitoring result is outputted to the
operation mode selection unit 42. Based on the signal outputted from the loss rate
monitoring unit 44, the operation mode selection unit 42 switches the operation mode
20 from the pitch-control permitted mode to the pitch-control invalid mode. Specifically,
when the calculated loss rate is not less than the second threshold, the operation
mode is switched from the pitch-control permitted operation mode to the pitch-control
invalid operation mode even during the operation in the pitch-control permitted
operation mode so as to reduce the surplus output of the wind turbine generator 2
25 with respect to the target output by a method other than the pitch control.
[0032]
The overall control unit 48 sends a control signal to a pitch control unit 26 of the
wind turbine controller 20 and to a battery control unit 33 of a battery controller 30 in
accordance with the selected operation mode selected by the operation mode selection
30 unit 42.
The grid monitoring unit 46 receives a grid frequency of the grid 6 measured by a
sensor 17, monitors a state of the grid 6 and outputs the monitoring result t the
overall control unit 48. The overall control unit 48 reduces the target output
temporarily when the grid frequency of the grid 6 exceeds an upper limit of the
35 prescribed range, whereas temporarily increases the target output of the wind turbine
generator facility 1 when the grid frequency of the grid 6 becomes below a lower limit
-12-
of the prescribed range. In this manner, the frequency of the grid 6 is kept with the
prescribed range.
[0033]
The wind turbine controller 20 includes a difference calculation unit 22, a
5 rotation energy monitoring unit 24, a rotation energy control unit 25 and a pitch
control unit 26.
The difference calculation unit 22 calculates a difference between the
measured output of the wind turbine generator 2 measured by the output measuring
unit 15 and the target output set in advance, and outputs the calculation result to the
10 overall control unit 48 of the master controller 40.
The rotation energy monitoring unit 24 monitors constantly or periodically an
amount of rotation energy (inertial energy) stored when the rotation speed of the
rotor 52 increases.
The rotation energy control unit 25 changes torque of the generator by
15 controlling the generator-side inverter 18A based on the control signal from the
overall control unit 48 of the master controller 40, thereby performing control for
converting the surplus output of the wind turbine generator 2 to rotation energy or
recovering the rotation energy as electrical energy of the wind turbine generator 2.
The pitch control unit 26 adjusts pitch angle of the blades 52B based on the
20 control signal from the overall control unit 48 of the master controller 40 to reduce
the difference between the output of the wind turbine generator 2 and the target
output to perform the pitch control.
[0034]
The battery controller 30 includes the battery state monitoring unit 32 and the
25 battery control unit 33.
The battery state monitoring unit 32 receives detection result on a
deterioration level of the secondary batter 10 from the battery state detection unit 31
connected to the secondary battery 10 and monitors the state of the secondary batter
10. The monitoring result of the state of the secondary battery 10 from the battery
30 state monitoring unit 32 is sent to the overall control unit 48 of the master controller
40. Based on the monitoring result, it is determined whether or not charging and
discharging of the secondary battery 10 is performed with higher priority to reduce
the difference between the output of the wind turbine generator and the target output.
As an indicator of the deterioration level, at least one of the number of charge-
35 discharge cycles, the number of total charge-discharge cycles and the number of
charge- discharge rates is used.
-13-
In the preferred embodiment, the number of charge-discharge cycles refers to
the number of charge-discharge cycles in a set period of time that is set in advance.
Each cycle is from charging to discharging of the secondary battery 10. The number
of total charge-discharge cycles is the total number of charge-discharge cycles from a
5 starting point of using the secondary battery 10 to a prescribed point. The number of
charge-discharge rates is the number of times an amount of charge-discharge exceeds
a prescribed threshold in unit time.
[0035]
FIG.2 to FIG.4 are used to explain signals transmitted between each
10 component when the power output leveling apparatus 4 performs such control to level
the output. FIG.2 is a control block diagram for reducing surplus output of the wind
turbine generator 2 when the pitch-control invalid operation mode is selected. FIG.3
is a control block diagram for supplying insufficient output of the wind turbine
generator 2 when one of the pitch-control invalid operation mode and a pitch-control
15 permitted operation mode is selected. FIG.4 is a control block diagram for reducing
surplus output of the wind turbine generator 2 when the pitch-control permitted
operation mode is selected.
[0036]
(To reduce surplus output of the wind turbine generator when the pitch-control
20 invalid operation mode is selected)
As shown in FIG.2, the difference calculation unit 22 of the wind turbine
controller 20 calculates a difference A P ( > 0 ) between the output of the wind
turbine generator 2 and the target output. The difference A P is sent to a first
switch 34 which is a part of the overall control unit 48 of the master controller 40.
25 The battery state monitoring unit 32 monitors constantly or periodically whether or
not the deterioration level of the secondary battery detected by the battery state
detection unit 31 is below a third threshold, and sends the monitoring result to the
first switch 34. Based on the signal from the battery state monitoring unit 32, the
first switch 34 selects which one of charging into the secondary battery 10 and storing
30 the rotation energy of the wind turbine generator 2 is performed with higher priority
in order to reduce the surplus output A P of the wind turbine generator 2.
Specifically, when the deterioration level is below the third threshold, in order
to reduce the surplus output of the wind turbine generator 2 with respect to the
target output, the first switch 34 is connected to a lower connection terminal on a
35 lower side of FIG.2 (secondary battery side) to perform charging of the secondary
battery with higher priority than storing the rotation energy. When the
-14-
deterioration level is not less than the third threshold, in order to reduce the surplus
output of the wind turbine generator 2 with respect to the target output, the first
switch 34 is connected to an upper connection terminal on an upper side of FIG.2
(rotation energy side) to perform storing of the rotation energy with higher priority
5 than charging of the secondary battery.
[0037]
When the first switch 34 is connected to the lower connection terminal, the
difference A P outputted from the difference calculation unit 22 of the wind turbine
controller 20, is inputted to a battery priority area of the battery control unit 33 via
10 the first switch 34.
In contrast, when the first switch 34 is connected to the upper connection
terminal of FIG.2, the difference A P is outputted to a comparison unit 38 and a
subtractor 39 via the first switch 34.
[00381
15 The rotation energy monitoring unit 24 calculates a surplus amount of stored
rotation energy A E which is a difference between a maximum amount of rotation
energy that can be stored in the wind turbine generator 2 and a current amount of
rotation energy E that is currently saved in the wind turbine generator 2, and outputs
the surplus amount of stored rotation energy A E to an comparison unit 38.
20 [0039]
The comparison unit 38 calculates an amount of command rotation energy A P
m of the wind turbine generator 2 based on comparison result of comparing the
difference A P and the surplus amount A E of stored rotation energy. Specifically,
the comparison unit 38 calculates A Po) as A Pm = A E when A P > A E, and A Pm
25 = A P when A P < A E. The amount of command rotation energy, A Pm from the
comparison unit 38 is then outputted to the rotation energy control unit 25 and the
subtractor 39.
[0040]
In the rotation energy control unit 25, the generator-side inverter ISA (see
30 FIG.1) is controlled based on the amount of command rotation energy, A Pm to reduce
the torque and the output of the generator, and wind power acting on the blades 52B
is converted into rotation energy of the wind turbine generator 2 to store surplus
output, thereby leveling the output.
[0041]
35 The subtractor 39 subtracts the amount of command rotation energy A Pm
outputted from the comparison unit 38 from the difference A P outputted from the
-15-
difference calculation unit 22 via the first switch 34. When A P - A Pw (amount of
convertible command rotation energy) is positive, i.e. A P > A Pw , a charge command
amount A Pb (=A P - A Pw ) is outputted to the battery priority area of the battery
control unit 33. In contrast, when A P - A Pw is negative, i.e. A P < A Pw , it is
5 deemed that the surplus output is solved by storing the rotation energy and thus, the
charge command amount A Pb (=A P - A Pw ) outputted to the battery priority area
of the battery control unit 33 is zero.
[00421
(To supply insufficient output of the wind turbine generator 2 when one of the pitch-
10 control invalid operation mode and the pitch-permitted operation mode is selected)
As shown in FIG.3, first, the difference calculation unit 22 of the wind turbine
controller 20 calculates the difference -A P (< 0) between the output of the wind
turbine generator 2 and the target output. The difference -A P is sent to a second
switch 35 which is a part of the overall control unit 48 of the master controller 40.
15 Further, the battery state monitoring unit 32 monitors constantly or periodically
whether or not the deterioration level of the secondary battery 10 detected by the
battery state detection unit 31 is below the third threshold, and sends the monitoring
result to the second switches 35 and 36. Based on the signal from the battery state
monitoring unit 32, the second switches 35 and 36 select which one of discharging
20 from the secondary battery 10 and discharging the rotation energy of the wind
turbine generator 2 is performed with higher priority in order to supply the
insufficient amount -A P of the wind turbine generator 2.
Specifically, when the deterioration level is below the third threshold, in order
to supply the insufficient output of the wind turbine generator 2 with respect to the
25 target output, the second switches 35 and 36 are connected to a lower connection
terminal on a lower side of FIG.3 (secondary battery side) to perform discharging of
the secondary battery 10 with higher priority than recovering the rotation energy. In
contrast, when the deterioration level is not less than the third threshold, in order to
supply the insufficient output of the wind turbine generator 2 with respect to the
30 target output, the second switches 35 and 36 are connected to a upper connection
terminal on an upper side of FIG.3 (rotation energy side) to perform recovering the
rotation energy with higher priority than discharging of the secondary battery.
[00431
When the second switch 35 is connected to the lower connection terminal
35 (secondary battery side), the difference -A P that is outputted from the difference
calculation unit 22 of the wind turbine controller 20, is inputted to the battery
-16-
priority area of the battery control unit 33. When the second switch 36 is connected
to the lower connection terminal, an energy discharge command of discharging
rotation energy is not outputted to the rotation energy control unit 25. Therefore,
the amount of the insufficient output -A P of the wind turbine generator 2 is
5 discharged from the secondary battery 10.
In contrast, when the second switch 35 is connected to the upper connection
terminal (rotation energy side), the difference -A P is outputted to an adder 51. The
rotation energy monitoring unit 24 obtains a current amount of stored rotation energy,
A Pm of the wind turbine generator 2. The current amount of stored rotation energy,
10 A Pm of the wind turbine generator 2 is also inputted to the adder 51. Then, the
adder 51 obtains -A P b from the sum of the difference -A P and the current amount of
stored rotation energy A Pm . The sum -A P b is inputted to the rotation energy
priority area of the battery control unit 33 as a battery discharge command amount.
On the other hand, when the second switch 36 is connected to the upper connection
15 terminal (rotation energy side), the amount of stored rotation energy A Pm is sent
from the rotation energy monitoring unit 24 via the second switch 36 to the rotation
energy control unit 25. In such process, the amount of stored rotation energy A Pm
is multiplied by -1 to change plus to change plus and minus sign, and the amount of
stored rotation energy A Pm becomes an energy discharge command amount -A Pm of
20 discharging the rotation energy and is inputted to the rotation energy control unit 25.
[0044]
In the rotation energy control unit 25, the generator-side inverter 18A (see
FIG.1) is controlled based on the energy discharge command amount -A Po to
increase torque or output of the generator, and the rotation energy stored in the rotor
25 52 is recovered to convert into electric energy, thereby solving insufficient output and
also leveling output.
[0045]
When the sum obtained in the adder 51 is positive, i.e. A Pm > A P, it is
deemed that the insufficient output is supplied by recovering the rotation energy.
30 Therefore, the battery discharge command amount -A Pb outputted to a rotation
energy priority area of the battery control unit 33 is zero.
[0046]
(To reduce surplus output of the wind turbine generator when the pitch-control
permitted operation mode is selected)
35 As shown in FIG.4, first, the difference calculation unit 22 of the wind turbine
controller 20 calculates the difference A P ( > 0) between the output of the wind
turbine generator 2 and the target output. The difference A P is sent to a third
switch 36 which is a part of the overall control unit 48 of the master controller 40.
Further, the battery state monitoring unit 32 monitors constantly or periodically
whether or not the deterioration level of the secondary battery 10 detected by the
5 battery state detection unit 31 is below the third threshold, and sends the monitoring
result to the third switch 37. Based on the signal from the battery state monitoring
unit 32, the third switch 37 selects which one of charging of the secondary battery 10
and storing the rotation energy of the wind turbine generator 2 together with pitch
control is performed with higher priority in order to reduce the surplus output A P of
10 the wind turbine generator 2.
Specifically, when the deterioration level is below the third threshold, in order
to reduce the surplus output A P with respect to the target output, the third switch
37 is connected to a lower connection terminal on a lower side of FIG.4 (secondary
battery side) to perform charging of the secondary battery 10 with higher priority. In
15 contrast, when the deterioration level is not less than the third threshold, in order to
reduce the surplus output A P with respect to the target output, the third switch 37
is connected to an upper connection terminal on an upper side of FIG.4 (rotation
energy side) to perform at least one of storing of the rotation energy and the pitch
control. In such case, from the perspective of improving power output of the wind
20 turbine generator facility 1, the rotation energy is stored with higher priority than
the pitch control. However, if there is still surplus output after storing the rotation
energy, the pitch control may be performed for the remaining amount of the surplus
output of the wind turbine generator 2 to reduce the surplus output.
[0047]
25 When the third switch 37 is connected to the lower connection terminal of
FIG.4, the difference A P outputted from the difference calculation unit 22 of the
wind- turbine controller 20 is outputted to the battery control unit 33 as the charge
command amount.
In contrast, when the third switch 37 is connected to the upper connection
30 terminal of FIG.4, the difference A P is outputted to the wind turbine controller 20.
[0048]
FIG.5 shows embodiments in which control is performed by the overall control
unit 48 of the master controller 40 described above.
As shown in FIGS, the integrated value of measured outputs of the wind
35 turbine generator 2 from a starting point of a set period of time to a prescribed point
of within the set period of time is calculated and then, the integrated value is divided
-18-
by a target output in the set period of time to calculate a target-output achievement
rate Ta.
[0049]
(CASE 1)
5 When the target-output achievement rate Ta is not less than the first
threshold TT of the target-output achievement rate that is set in advance (YES in a
section of the target-output achievement rate Ta), and both of a deterioration level Ba
(in accordance with the number of charge-discharge cycles as an indicator) and a
deterioration level Bb (in accordance with the number of charge-discharge rates as an
10 indicator) are below third thresholds BT and Bs respectively that are set beforehand
(YES in a section of the battery deterioration level Ba, Bb), the secondary battery 10
is discharge or charged.
Specifically, when the output Wa of the wind turbine generator 2 exceeds the
target output WT, the third switch 37 is connected to the lower connection terminal
15 (secondary battery side) of FIG.4 to input the difference A P from the difference
calculation unit 22 to the battery priority area of the battery control unit 33 via the
third switch 37. When the output Wa of the wind turbine generator 2 is not greater
than the target output WT, the second switch 35 is connected to the lower connection
terminal (secondary battery side) of FIG.3 to input the difference -A P from the
20 difference calculation unit 22 to the battery priority area of the battery control unit
33 via the second switch 35.
[0050]
(CASE 2)
When the target-output achievement rate Ta is not less than the first
25 threshold Tr (YES in the section of the target-output achievement rate Ta), and at
least one of the deterioration level Ba and the deterioration level Bb is not less than
the third thresholds BT and Bs respectively (NO in the section of the battery
deterioration level Ba, Bb), the rotation energy is stored and recovered first. Further,
in the case where the output Wa of the wind turbine generator 2 exceeds the target
30 output WT, if there is still surplus output after storing the rotation energy, the pitch
control is performed, whereas in the case where the output Wa of the wind turbine
generator 2 is not greater than the target output WT, if there is still insufficient
output after recovering the rotation energy, the secondary battery 10 is discharged.
Specifically, when the output Wa of the wind turbine generator 2 exceeds the
35 target output WT, the third switch 37 is connected to the upper connection terminal
(rotation energy side) of FIG.4 to input the difference A P from the difference
-19-
calculation unit 22 to the wind turbine controller 20 via the third switch 37. When
the output Wa of the wind turbine generator 2 is not greater than the target output
WT, the second switch 35, 36 is connected to the upper connection terminal (rotation
energy side) of FIG.3 to input the energy discharge command amount -A Pc to the
5 rotation energy control unit 21 and also input the battery discharge command amount
-A P to the rotation energy priority area of the battery control unit 33.
[0051]
(CASE 3)
When the target-output achievement rate Ta is below the first threshold TT
10 (NO in the section of the target-output achievement rate Ta), and both of the
deterioration level Ba and the deterioration level Bb are below the third thresholds BT
and Bs (YES in the section of the battery deterioration level Ba, Bb), the secondary
battery 10 is charged or discharged.
Specifically, when the output Wa of the wind turbine generator 2 exceeds the
15 target output WT, the first switch 34 is connected to the lower connection terminal
(secondary battery side) of FIG.2 to input the difference A P from the difference
calculation unit 22 to the battery priority area of the battery control unit 33 via the
first switch 34. When the output Wa of the wind turbine generator 2 is not greater
than the target output WT, the second switch 35 is connected to the lower connection
20 terminal (secondary batter side) of FIG.3 to input the difference -A P outputted from
the difference calculation unit 22 to the battery priority area of the battery control
unit 33.
[0052]
(CASE 4)
25 When the target-output achievement rate Ta is below the first threshold TT
(NO in the section of the target-output achievement rate Ta), and at least one of the
deterioration level Ba and the deterioration level Bb is not less than the third
thresholds BT and Bs respectively (NO in the section of the battery deterioration level
Ba, Bb), the rotation energy is stored and recovered with higher priority. Then, in
30 the case where the output Wa of the wind turbine generator 2 exceeds the target
output WT, if there is still surplus output after storing the rotation energy, the
secondary battery is charged, whereas in the case where the output Wa of the wind
turbine generator 2 is not greater than the target output WT, if there is still
insufficient output after recovering the rotation energy, the secondary battery 10 is
35 discharged.
Specifically, when the output Wa of the wind turbine generator 2 exceeds the
-20-
target output WT, the first switch 34 is connected to the upper connection terminal
(rotation energy side) of FIG.2 to input the store command amount A Pm to the
rotation energy control unit 25 and also input the charge command amount A Pb to
the rotation energy priority area of the battery control unit 33. In contrast, when
5 the output Wa of the wind turbine generator 2 is not greater than the target output
WT, the second switch 35, 36 is connected to the upper connection terminal (rotation
energy side) of FIG.3 to input the energy discharge command amount -A Pm to the
rotation energy control unit 25 and also input the battery discharge command amount
-A P b to the rotation energy priority area of the battery control unit 33
10 [0053]
Next, control flows performed in the power output leveling apparatus 4 are
explained in reference to the flow charts.
[0054]
FIG.6 is a control flow diagram showing a control flow of selecting the pitch-
15 control invalid operation mode and the pitch-control permitted operation mode.
As shown in FIG.6, the output measuring unit, 15 measures a current output
Wa of the wind turbine generator 2 (Step S10).
[0055]
Based on the measured output Wa, an integrated value of the measured otputs
20 of the wind turbine generator 2 from a starting point of a set period of time to a
prescribed point within the set period of time and divide the integrated value is
divided by a target output in the set period of time by the achievement rate
calculation unit 45 to calculate the target-output achievement rate Ta (Step S12).
[0056]
25 Next, the calculated target-output achievement rate Ta is compared with the
first threshold TT in the achievement rate monitoring unit 41 and the comparison
result is sent to the operation mode selection unit 42 (Step S14).
When the calculated target-output achievement rate Ta is below the first
threshold TT (YES in S14), the operation mode selection unit 42 selects the pitch-
30 control invalid operation mode which invalidates the pitch control (Step S16).
Subsequently, the overall control unit 48 controls the rotation energy control unit 25
and the battery control unit 33 so as to operate in the pitch-control invalid operation
mode.
On the other, when the calculated target-output achievement rate Ta is not
35 less than the first threshold TT (NO in S14), the loss rate calculation unit 43
calculates a loss rate La (an amount of power production lost due to the pitch control)
-21-
which is a rate of the actual production amount obtained from the measured output
Wa measured by the output measuring unit 15 to an ideal output (Step S17). Then,
the calculated loss rate La is compared with a second threshold LT of a loss rate that
is set in advance and the comparison result is sent to the operation mode selection
5 unit 42. When the loss rate La is not less than the second threshold LT (YES in S18),
the process advances to the step S16 so that the operation-mode selection unit 42
selects the pitch-control invalid operation mode.
When the loss rate La is below the second threshold LT (NO in S18), the process
advances to a step S19 so that the operation-mode selection unit 42 selects the pitch-
10 control permitted operation mode to allow the pitch control (Step S19). Subsequently,
the overall control unit 48 controls the rotation energy control unit 25, the pitch
control unit 26 and the battery control unit 33 so as to operate in the pitch-control
permitted operation mode.
[0057]
15 Now, control flows performed by the overall control unit 48 after the operation
mode selection unit 42 selects the pitch-control invalid operation mode are explained
below.
[0058]
FIG.7 is a control flow diagram showing a control by the overall control unit 48
20 when the pitch-control invalid operation mode is selected.
As shown in FIG.7, when the pitch-control invalid operation mode is selected
(Step S16), the battery state detection unit 31 obtains the deterioration level of the
secondary battery 10, e.g. the number of charge-discharge cycles, Ba and the number
of charge- discharge rates, Bb (Step S20) and outputs the obtained result to the
25 battery state monitoring unit 32.
Further, in the pitch-control invalid operation mode only invalidates the pitch
control for leveling the power output and does not invalidate a pitch control itself.
[0059]
The difference calculation unit 22 determines whether or not the output Wa of
30 the wind turbine generator 2 measured by the output measuring unit 15 exceeds the
target output WT (Step S22).
[0060]
Then, the battery state monitoring unit 32 determines whether or not both of
the deterioration levels Ba and Bb inputted from the battery state detection unit 31
35 are below the third thresholds BT and Bs (Step S24 and Step S26).
[0061]
-22-
When it is determined in the step S22 that the output Wa of the wind turbine
generator 2 exceeds the target output WT and it is determined in the step S24 that
both of the deterioration levels Ba and Bb inputted from the battery state detection
unit 31 are below the third thresholds BT and Bs, the process advances to a step S28
5 to charge the secondary battery 10 under the control by the overall control unit 48.
Such control corresponds to Wa > WT of Case 3 in FIG.5 that is described above.
[0062]
When it is determined in the step S22 that the output Wa of the wind turbine
generator 2 exceeds the target output WT and it is determined in the step S24 that at
10 least one of the deterioration levels Ba and Bb inputted from the battery state
detection unit 31 is not less than the third thresholds BT and Bs, the process advances
to a step S30 to store the rotation energy with higher priority under the control by the
overall control unit 48. If there is still surplus output after storing the rotation
energy, charging of the secondary battery 10 is performed. Such control corresponds
15 to Wa > WT of Case 4 in FIG.5 that is described above.
[0063]
When it is determined in the step S22 that the output Wa of the wind turbine
generator 2 is not greater than the target output WT and it is determined in the step
S26 that both of the deterioration levels Ba and Bb are below the third thresholds BT
20 and Bs, the process advances to a step S32 to discharge from the secondary battery 10
under the control by the overall control unit 48. Such control corresponds to Wa
WT of Case 3 in FIG.5 that is described above.
[0064]
When it is determined in the step S22 that the output Wa of the wind turbine
25 generator 2 is not greater than the target output WT and it is determined in the step
S26 that at least one of the deterioration levels Ba and Bb is not less that the third
thresholds BT and Bs, the process advances to a step S34 to perform recovering of the
rotation energy with higher priority under the control by the overall control unit 48.
Such control corresponds to Wa < WT of Case 4 in FIG.5 that is described above.
30 [0065]
FIG.8 is a control flow diagram showing a control by the overall control unit 48
when the pitch-control permitted operation mode is selected.
As shown in FIG.8, when the pitch-control permitted operation mode is
selected (Step S19), the battery state detection unit 31 obtains the deterioration levels
35 Ba and Bb of the secondary battery 10; e.g. Bathe number of charge-discharge cycles
and Bb:the number of charge- discharge rates (Step S40) and outputs the obtained
-23-
result to the battery state monitoring unit 32.
[0066]
The difference calculation unit 22 determines whether or not the output Wa of
the wind turbine generator 2 measured by the output measuring unit 15 exceeds the
5 target output Wr (Step S42).
[0067]
Then, the battery state monitoring unit 32 determines whether or not both of
the deterioration levels Ba and Bb inputted from the battery state detection unit 31
are below the third thresholds BT and Bs (Step S44 and Step S46).
10 [0068]
When it is determined in the step S42 that the output Wa of the wind turbine
generator 2 exceeds the target output Wr and it is determined in the step S44 that
both of the deterioration levels Ba and Bb inputted from the battery state detection
unit 31 are below the third thresholds BT and Bs, the process advances to a step S48
15 to charge the secondary battery 10 under the control by the overall control unit 48.
Such control corresponds to Wa > WT of Case 1 in FIGS that is described above.
[0069]
When it is determined in the step S42 that the output Wa of the wind turbine
generator 2 exceeds the target output WT and it is determined in the step S44 that at
20 least one of the deterioration levels Ba and Bb inputted from the battery state
detection unit 31 is not less than the third thresholds BT and Bs, the process advances
to a step S50 to store the rotation energy with higher priority under the control by the
overall control unit 48. Only when there is still surplus output after storing the
rotation energy, the pitch control is performed. Such control corresponds to Wa > WT
25 of Case 2 in FIG.5 that is described above.
[0070]
When it is determined in the step S42 that the output Wa of the wind turbine
generator 2 is not greater than the target output WT and it is determined in the step
S46 that both of the deterioration levels Ba and Bb are below the third thresholds BT
30 and Bs, the process advances to a step S52 to discharge from the secondary battery 10
under the control by the overall control unit 48. Such control corresponds to Wa
WT of Case 1 in FIG.5 that is described above.
[0071]
When it is determined in the step S42 that the output Wa of the wind turbine
35 generator 2 is not greater than the target output WT and it is determined in the step
S46 that at least one of the deterioration levels Ba and Bb is not less that the third
-24-
thresholds BT and Bs, the process advances to a step S54 to perform recovering of the
rotation energy with higher priority under the control by the overall control unit 48-
Such control corresponds to Wa < WT of Case 2 in FIG.5 that is described above.
[0072]
5 Further, after the steps of the battery-priority operation mode, S28, S32, S48
and S52 and after the steps of the rotation-energy-priority mode, S30, S34, S50 and
S54, it is possible to provide a step of obtaining a frequency of the grid to which the
wind turbine generator 2 and the secondary battery 10 are connected by a frequency
sensor 17 and a step of modifying the target output so as to reduce the target output
10 WT when the frequency exceeds an upper limit of a prescribed range set beforehand or
to increase the target output WT when the frequency becomes lower than the lower
limit of the prescribed range. In this manner, it is possible to keep the frequency of
the grid 6 within the prescribed range.
[0073]
15 According to the preferred embodiment, the achievement rate calculation unit
45 calculates the target-output achievement rate Ta from the measured output Wa of
the wind turbine generator 2 measured by the output measuring unit 15, and the
operation mode selection unit 42 selects the pitch-control invalid operation mode
when the achievement rate is below the first threshold set beforehand. In such case,
20 in order to reduce the surplus output t P of the wind turbine generator with respect
to the target output, a pitch control is invalid and at least one of charging in the
secondary battery 10 and storing rotation energy of the wind turbine generator 2 is
performed, thereby performing the pitch control to feather the blades less often. As
a result, the amount of wind energy lost without being converted into electric energy
25 is reduced, thereby generating more electrical energy.
[0074]
In the pitch-control permitted operation mode, the pitch control is permitted to
reduce the surplus output of the wind turbine generator 2. Thus, depending on the
state of the secondary battery 10, charging of the surplus output of the wind turbine
30 generator 2 into the secondary battery may be avoided and instead the pitch control
may be performed to reduce the number of times of charging into the secondary
battery 10, thereby extending the life of the secondary battery 10.
[0075]
Even if the target-output achievement rate Ta at a point exceeds the first
35 threshold TT and there is comparatively sufficient power production, the wind speed
and the wind direction changes and thus, it does not assure the power production can
-25-
be kept positively after achieving the threshold once in order to achieve the target
output. Therefore, when the loss rate La calculated by the loss rate calculation unit
43 is not less than the second threshold LT, even if the production target achievement
rate Ta is not less than the first threshold TT and the pitch-control permitted
5 operation mode is selected, the operation mode is switched to the pitch-control invalid
mode by the operation mode selection unit 42, thereby performing the pitch control
for reducing the surplus output of the wind turbine generator 2 less frequently. Thus,
it is easy to achieve the target output in the set period of time.
[0076]
10 The battery state detection unit 31 obtains the deterioration levels Ba and. Bb
of the secondary battery 10. The obtained deterioration levels Ba and Bb are
compared with the third thresholds BT and Bs that are set in advance. When at least
one of the deterioration levels Ba and Bb is not less than the third thresholds BT and
Bs, storing or discharging of the rotation energy of the wind turbine generator 2 is
15 performed with higher priority than charging or discharging of the secondary battery
10 so as to reduce the number of times that the secondary battery 10 is charged. In
this manner, it is possible to prevent the life of the secondary battery 10 from
decreasing.
[0077]
20 While the present invention has been described with reference to exemplary
embodiments, it is obvious to those skilled in the art that various changes may be
made without departing from the scope of the invention.
[00781
For instance, in the above preferred embodiment, the target output WT of the
25 wind turbine generator facility 1 is temporarily increased or decreased based on the
frequency of the grid 7 obtained by the sensor 17. However, this is not limitative and
the target output WT of wind turbine generator facility 1 may be modified temporarily
based on the deterioration levels Ba and Bb of the secondary battery 10. Specifically,
when at least one of the deterioration levels Ba and Bb detected by the battery state
30 detection unit 31 is not less than the third thresholds BT and Bs, the target output WT
may be temporarily modified to reduce the difference between the output of the wind
turbine generator 2 and the target output. In this manner, it is possible to
sufficiently perform leveling of the power output more often by a method other than
charging and discharging of the secondary batter (mainly by storing and discharging
35 of the rotation energy of the wind turbine generator 2). As a result, it is possible to
reduce the number of times that the secondary battery 10 is charged or discharged,
-26-
thereby extending the life of the secondary battery 10.
[0079]
In the above preferred embodiment, which one of storing/discharging of
rotation energy of the wind turbine generator 2 and charging/discharging of the
5 secondary battery 10 is performed with higher priority, is switched based on the
result of comparing the deterioration levels Ba and Bb and the third thresholds BT
and Bs. However, this is not limitative and which one of storing/discharging of
rotation energy of the wind turbine generator 2 and charging/discharging of the
secondary battery 10 is performed with higher priority, may be switched based on a
10 remaining capacity of the secondary battery 10 (SOC) in replacement of or in addition
to the deterioration levels Ba and Bb. For instance, battery state detection unit 31
detects the remaining capacity of the secondary battery 10 in addition to the
deterioration levels Ba and Bb and the battery state monitoring unit 32 determines
whether or not the remaining capacity is within a prescribed range. When the
15 remaining capacity of the secondary battery 10 is not in the prescribed range,
charging and discharging of the secondary battery is performed with higher priority
by the overall control unit 48 to level the power output, thereby keeping the
remaining capacity within the prescribed range.
Specifically, in the above preferred embodiment, in CASE 2 of FIG.5 where Wa
20 WT and in Case 4 of FIG.5 where Wa > WT and Wa < WT, in order to level the
power output of the wind turbine generator facility 1, the rotation energy is stored or
recovered and then, if there is still difference between the output Wa of the wind
turbine generator 2 and the target output WT, the secondary battery is charged or
discharged. However, this is not limitative and it is also possible to charge or
25 discharge the secondary battery 10 with higher priority when the remaining capacity
of the secondary battery 10 is not within the prescribed range, so as to keep the
remaining capacity within the prescribed range. In this manner, it is possible to
extend the life of the secondary battery 10.
[0080]
30 In the above preferred embodiment, the target-output achievement rate Ta
obtained by the achievement rate calculation unit 45 is used when the operation mode
selection unit 42 selects an operation mode. However, this is not limitative and the
loss rate La obtained by the loss rate calculation unit 43 may be used to select an
operation mode. Specifically, the steps S12 and S14 of FIG.6 are replaced by the
35 steps S17 and S18 of FIG.6. First, the loss rate La is compared with the second
threshold LT. When La ? LT, the pitch-control invalid operation mode is selected
-27-
(S16). On the other hand, when La < LT, the target-output achievement rate Ta is
compared with the first threshold TT. When Ta < TT, the pitch-control invalid
operation mode is selected (S16), whereas, when Ta ? TT, the pitch-control
permitted operation mode is selected (S19).
5 [0081]
In the above preferred embodiment, the wind turbine generator facility 1
includes one wind turbine generator 2. However, the number of wind turbine
generators 2 should not be limited and the wind turbine generator facility 1 may
include more than one wind turbine generator 2.
10
[Reference Signs list]
[0082]
1 Wind turbine generator facility
2 Wind turbine generator
15 3 Electrical power storage device
4 Power output leveling apparatus
5 Grid interconnecting part
6 Grid
8 Transformer
20 9 Generator
10 Secondary battery
11 DC-AC converter
12 Transformer
13 Transformer
25 14 Inverter unit
15 Output measuring unit
17 -- Sensor
18A Generator-side inverter
18B DC bus
30 20 Wind turbine controller
22 Difference calculation unit
24 Rotation energy monitoring unit
25 Rotation energy control unit
26 Pitch controller
35 30 Battery controller
31 Battery state detection unit
32 Battery state monitoring unit
33 Battery control unit
34 First switch
5 35, 36 Second switch
37 Third switch
38 Comparison unit
39 Subtractor
40 Master controller
10 41 Achievement rate monitoring unit
42 Operation mode selection unit
43 Loss rate calculation unit
44 Loss rate monitoring unit
45 Achievement rate calculation unit
15 46 Grid monitoring unit
48 Overall control unit
51 Adder
52 Rotor
52A Hub
20 52B Blade
SC Stator winding
RC Rotor winding

[CLAIMS]
[Claim 1]
A power output leveling method for adjusting an output of a wind turbine generator
facility in which a wind turbine generator is combined with a secondary battery
5 to a target output, the method comprising the steps of:
measuring an output of the wind turbine generator;
calculating a target-output achievement rate that is a rate of an integrated value of
the measured outputs of the wind turbine generator from a starting point of a set
period of time to a prescribed point within the set period of time with respect to a
10 target output in the set period of time; and
selecting an operation mode of the wind power facility,
wherein, in the step of selecting the operation mode, when the target-output
achievement rate is below a first threshold, a pitch-control invalid operation
mode is selected, in said pitch-control invalid operation mode a pitch control for
15 leveling the output to reduce surplus output of the wind turbine generator with
respect to the target output being invalid and at least one of charging in the
secondary battery and storing rotation energy of the wind turbine generator
being performed.
20 [Claim 21
The power output leveling method for the wind turbine generator facility according to
claim 1,
wherein, in the step of selecting the operation mode, when the target-output
achievement rate is not less than the first threshold, a pitch-control permitted
25 operation mode is selected, in said pitch-control permitted operation mode the
pitch control being performed to reduce the surplus output of the wind turbine
generator with respect to the target output.
[Claim 3]
30 The power output leveling method for the wind turbine generator facility according to
claim 2, further comprising the step of:
when the pitch-control permitted operation mode is selected in the operation mode
selecting step, calculating a loss rate that is a rate of an amount of power loss due
to the pitch control to an ideal output that is obtained based on a wind speed
35 according to a performance curve of the wind turbine generator representing a
relationship between the wind speed and the ideal output of the wind turbine
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generator,
wherein, when the calculated loss rate is not less than a second threshold, the
operation mode is switched from the pitch-control permitted operation mode to
the pitch-control invalid operation mode.
5
[Claim 4]
The power output leveling method for the wind turbine generator facility according to
claim 1, further comprising the step of:
obtaining a deterioration level of the secondary battery,
10 wherein, when the obtained deterioration level of the secondary battery exceeds a
third threshold, charging and discharging of the rotation energy of the wind
turbine generator is performed with higher priority than charging and
discharging of the secondary battery, so as to reduce the surplus output or supply
insufficient output with respect to the target output.
15
[Claim 5]
The power output leveling method for the wind turbine generator facility according to
claim 4,
wherein the deterioration level of the secondary battery is at least one of the number
20 of charge-discharge cycles, the number of total charge-discharge cycles and the
number of charge-discharge rates.
[Claim 6]
The power output leveling method for the wind turbine generator facility according to
25 claim 1, further comprising the step of:
obtaining a remaining capacity of the secondary battery,
wherein, when the obtained remaining capacity of the secondary battery is not in a
set range, charging and discharging of the secondary battery is performed with
higher priority than charging and discharging of the rotation energy of the wind
30 turbine generator, so as to reduce the surplus output or supply insufficient output
with respect to the target output.
[Claim 7]
The power output leveling method for the wind turbine generator facility according to
35 claim 4, further comprising:
a first target output modifying step of modifying the target output temporarily so as
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to reduce a difference between the output of the wind turbine generator and the
target output, when the obtained deterioration level of the secondary battery
exceeds the third threshold.
5 [Claim 3]
The power output leveling method for the wind turbine generator facility according to
claim 1, further comprising:
a second target output modifying step of increasing the target output when the targetoutput
achievement rate is less than the first threshold.
10
[Claim 9]
The power output leveling method for the wind turbine generator facility according to
claim 1, further comprising:
a step of obtaining a frequency of a grid to which the wind turbine generator and the
15 secondary battery are connected; and
a third target output modifying step of reducing the target output when the obtained
frequency exceeds a set upper limit whereas increasing the target output when
the obtained frequency becomes less than a set lower limit.
20 [Claim 10]
A power output leveling apparatus of adjusting an output of a wind turbine generator
facility in which a secondary battery is combined with a wind turbine generator
to a target output, the apparatus comprising:
an output measuring unit which measures an output of the wind turbine generator;
25 a calculation unit which calculates a target-output achievement rate that is a rate of
an integrated value of the measured outputs of the wind turbine generator from a
starting point of a set period of time to a prescribed point within the set period of
time with respect to a target output in the set period of time; and
an operation mode selection unit which selects a pitch-control invalid operation mode
30 when the target-output achievement rate is below a first threshold, in said pitchcontrol
invalid operation mode a pitch control for leveling the output to reduce
surplus output of the wind turbine generator with respect to the target output
being invalid and at least one of charging into the secondary battery and storing
rotation energy of the wind turbine generator being performed.
35
[Claim 11]
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A power output leveling method for adjusting an output of a wind turbine generator
facility in which a secondary battery is combined with a wind turbine generator
to a target output, the method comprising the steps of:
measuring an output of the wind turbine generator;
5 calculating a loss rate that is a rate of an amount of power loss due to the pitch
control to an ideal output that is obtained based on a wind speed according to a
performance curve of the wind turbine generator representing a relationship
between the wind speed and the ideal output of the wind turbine generator; and
selecting an operation mode of the wind power facility,
10 wherein, in the step of selecting the operation mode, when the loss rate is below a
second threshold, a pitch-control invalid operation mode is selected, in said pitchcontrol
invalid operation a pitch control for leveling the output to reduce surplus
output of the wind, turbine generator with respect to the target output being
invalid and at least one of charging into the secondary battery and storing
15' rotation energy of the wind turbine generator being performed.