JP2013106437A - Wind power generation apparatus, method and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress active power dropping and reactive power consumption upon recovery of a power system after generation of a low voltage event of the power system.SOLUTION: A wind power generation apparatus 1, including: a windmill rotor hub 11 that is rotated by wind power; a fixed speed type induction generator 13 driven by the rotation of the windmill rotor hub 11; and a brake 20 that brakes the rotation of the windmill rotor hub 11 and that is interconnected with the power system 15, includes a control section 18 that determines that a low voltage event has occurred when a voltage of the power system 15 is smaller than a first threshold value and controls the brake 20 to obtain a rotational speed between a synchronous speed and a rotational speed of an induction generator 13 that obtains a rated output.

Description

  The present invention relates to a wind power generation apparatus and method, and a program.

  In recent years, guidelines for power grid interconnection requirements for wind power generation facilities have been established, and the installed wind power generation apparatus must be adapted to the interconnection requirements. In addition, in the event of a short-term power system low voltage event due to the occurrence of a power system accident, operation that minimizes the impact on the power system without disconnecting the wind power generator from the power system side That is, a function corresponding to LVRT (Low Voltage Ride Through) is required.

For example, when a low voltage event occurs in which the voltage of the power system decreases due to the occurrence of an accident on the power system side, the generator of the wind power generator increases in speed due to the absence of the load, but the speed exceeds a predetermined amount. As the wind power rises, the wind power generation device breaks down, and a technique for preventing the failure by controlling to a predetermined rotation speed is being studied.
In the following Patent Document 1, when a power system accident occurs, the wind turbine blade pitch angle is controlled to prevent over-rotation of the generator accompanying the accident, and the power system voltage value has returned to the state before the accident. In such a case, a technique has been proposed in which the pitch angle is controlled to control the rotation speed within the operable range, thereby shortening the time until the operation is resumed.

  In addition, for example, when recovering from a state where the voltage of the power system has dropped, a large current flows and a large torque is generated according to the slip at that time, and a large load is applied to the equipment, so the generator rotation speed is synchronized. A technology has been proposed that prevents the generation of large torque or anti-load torque that occurs when the control of the converter and the inverter is resumed by controlling the pitch angle of the wind turbine blades so that the rotational speed becomes higher or higher. (Patent Document 2 below).

JP 2010-35418 A International Publication No. 2010/095248

However, when the rotational speed control by the pitch angle control is performed as in the methods of Patent Document 1 and Patent Document 2, the windmill blade is moved to the feather side when the voltage value of the power system returns to the state before the accident. Since it is on the side where the wind escapes, there is a problem that the drop in the active power value occurs as shown by the solid line in FIG.
In addition, when the voltage value of the power system is restored, the reactive power consumed by the induction generator in the wind power generator in which the induction generator is mounted in a fixed speed method due to over-rotation is shown in FIG. As shown by the dotted line in FIG. In such a case, the voltage at the interconnection point between the wind turbine generator and the power system will eventually decrease as seen from the power system side, and as shown by the solid line in FIG. It does not rise to the voltage value of the system (dotted line in FIG. 7A). Conventionally, there is no method for suppressing such reactive power consumption, and there has been a problem in that reactive power consumption cannot be suppressed. Further, the control of the rotational speed by controlling the pitch angle of the windmill blade is not suitable for a low voltage event that occurs instantaneously such as LVRT because the response speed is slow.

  The present invention has been made in view of such circumstances, and it is possible to suppress a drop in active power and a reactive power consumption when a voltage value of the power system is restored after the occurrence of a low voltage event in the power system. An object of the present invention is to provide a power generation apparatus and method, and a program.

In order to solve the above problems, the present invention employs the following means.
The present invention includes a wind turbine generator that is linked to an electric power system, and includes a rotor that is rotated by wind power, a fixed-speed induction generator that is driven by the rotation of the rotor, and a brake that brakes the rotation of the rotor. And determining that a low voltage event has occurred when the voltage of the power system is lower than a first threshold, and determining the rotational speed of the induction generator to obtain a synchronous speed and a rated output. There is provided a wind turbine generator comprising control means for controlling the brake so as to have a rotational speed between the rotational speeds of the brakes.

According to such a configuration, the control means for controlling the brake that brakes the rotation of the rotor that is rotated by wind power determines that a low-voltage event has occurred when the voltage of the power system becomes lower than the first threshold value. The brake is controlled so that the rotational speed of the rotor becomes a rotational speed between the synchronous speed and the rotational speed of the induction generator capable of obtaining the rated output.
Thus, since the rotation speed of the induction generator is controlled using a brake that brakes the rotation of the rotor provided on the shaft of the wind turbine generator, the consumption of reactive power generated when the generator rotation speed increases is reduced. It can suppress, and it can contribute to the quick return of the voltage in the connection point of an electric power grid | system and a wind power generator. Also, when the rotational speed is controlled by the pitch angle of the windmill blade, the pitch angle is set to the feather side. However, since the rotational speed is not controlled by the pitch angle in the present invention, it is effective when the voltage of the power system is restored. Reduced power drop. Furthermore, compared with the case where the generator rotational speed is controlled by the pitch angle control of the windmill blade, when the power system is restored, the time required for voltage restoration at the interconnection point can be shortened. The generator rotation speed controlled by the control means is preferably substantially synchronous speed.

The said control means of the said wind power generator is good also as controlling the rotation speed of the said induction generator by carrying out on-off control of the said brake.
The generator speed can be easily controlled by on / off control.

The control means of the wind turbine generator is configured such that the rotational speed of the induction generator is set to a target rotational speed set in a rotational speed range between the synchronous speed and the rotational speed of the induction generator that provides a rated output. It is good also as performing feedback control so that it may correspond.
By controlling the generator speed so that it matches the target speed, the generator speed can be controlled with high accuracy, so it is more effective in reducing reactive power consumption and restoring active power than when on-off control is performed. Can be done.

  The wind power generator includes a power adjustment unit between the induction generator and the power system, and the power adjustment unit is configured to detect a voltage value of the power system after the low voltage event of the power system has occurred. May be determined to have returned to the grid when the value becomes larger than the second threshold, and the power adjustment may be performed so that the output power value of the wind turbine generator is the power value immediately before the occurrence of the low voltage event.

For example, even when a decrease in wind speed occurs after the system is restored, the power is adjusted so that the power value immediately before the low voltage event is obtained. Alternatively, after a low voltage event, when the voltage recovers and then the wind speed becomes weaker, the power supplied to the power system decreases and decreases and becomes unstable. By adjusting, a stable output is supplied to the power system side.
In order to accelerate the voltage recovery after the low voltage event, reactive power may be supplied by the power adjusting means.

The power adjustment means of the wind power generator may be a power storage device capable of storing electricity.
Power adjustment can be easily performed by the power storage device. The power storage device is a secondary battery such as a lithium ion battery, a lead storage battery, a sodium sulfur battery, or a redox flow battery.

The power storage device of the wind power generator may supply power to the control means.
The power stored in the power storage device can be used as a power source for the control means, and the power can be used effectively.

  The present invention includes a wind turbine generator that is linked to an electric power system, and includes a rotor that is rotated by wind power, a fixed-speed induction generator that is driven by the rotation of the rotor, and a brake that brakes the rotation of the rotor. And determining that a low-voltage event has occurred when the voltage of the power system is lower than a first threshold, and determining the rotation speed of the induction generator to obtain a synchronous speed and a rated output. Provided is a method for controlling a wind turbine generator that controls the brake so as to have a rotational speed between that of an induction generator.

  The present invention includes a wind turbine generator that is linked to an electric power system, and includes a rotor that is rotated by wind power, a fixed-speed induction generator that is driven by the rotation of the rotor, and a brake that brakes the rotation of the rotor. And determining that a low voltage event has occurred when the voltage of the power system is lower than a first threshold, and determining the rotation speed of the induction generator to obtain a synchronous speed and a rated output. There is provided a control program for a wind turbine generator for causing a computer to control the brake so as to have a rotational speed between the rotational speed of the induction generator.

  The present invention has an effect that, after the occurrence of a low voltage event in the power system, it is possible to suppress a drop in active power and a reactive power consumption when the voltage value of the power system is restored.

It is the figure which showed schematic structure of the wind power generator which concerns on the 1st Embodiment of this invention. (A) Trend of system voltage and interconnection point voltage when performing rotational speed control according to the first embodiment, (b) Trend of active power and reactive power supplied from the generator, (c) Generator rotation It is the figure which showed an example of the tendency of a number. It is an operation | movement flow of the control part which concerns on 1st Embodiment. It is the figure which showed schematic structure of the wind power generator which concerns on the 3rd Embodiment of this invention. It is the figure which showed an example of the tendency of the active electric power and reactive power which are supplied from a generator, when a wind speed falls after a voltage return. (A) Trend of system voltage and interconnection point voltage when performing rotational speed control according to the third embodiment of the present invention, (b) Trend of active power and reactive power supplied from the generator, (c) It is the figure which showed an example of the tendency of generator rotation speed. In the case of the conventional control, (a) the trend of system voltage and interconnection point voltage, (b) the trend of active power and reactive power supplied from the generator, (c) the graph showing the trend of generator rotation speed is there.

[First Embodiment]
Hereinafter, an embodiment of a wind turbine generator and method and a program according to the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a schematic configuration of a wind turbine generator 1 according to the present embodiment. As shown in FIG. 1, a wind turbine generator 1 according to this embodiment includes a wind turbine blade 10, a wind turbine rotor hub (rotor) 11, a gear 12, a generator (induction generator) 13, a solenoid valve 14, a hydraulic pump 19, A voltmeter 9, a control unit (control means) 18, and a brake 20 are provided, and are connected (connected) to the power system 15 at the connection point Y.
A plurality of windmill blades 10 are radially attached to the windmill rotor hub 11. A generator 13 is connected to the main shaft of the wind turbine rotor hub 11 via a gear 12 having a predetermined gear ratio, and is mechanically coupled to be rotatable integrally.

Therefore, the windmill blade 10 receives wind energy and rotates together with the windmill rotor hub 11 to drive the generator 13 to generate electric power, thereby converting the wind energy into electric energy. The generator 13 is a fixed-speed induction generator, for example, a squirrel-cage induction generator.
A voltmeter 9 is provided near the interconnection point Y between the wind power generator 1 and the power system 15. The voltmeter 9 measures the voltage at the interconnection point Y and outputs the measurement result to the control unit 18.

The hydraulic pump 19 is adapted to send a working fluid (for example, working oil) in a tank (not shown), and the sent working fluid is sent to the electromagnetic valve 14.
On / off of the electromagnetic valve 14 is controlled by the control unit 18. The electromagnetic valve 14 operates the brake 20 with the working fluid sent from the hydraulic pump 19 when in the on state, and releases the operation of the brake 20 when in the off state.

A brake 20 that brakes the rotation of the wind turbine rotor hub 11 is provided between the gear 12 and the generator 13. The brake 20 is connected to the hydraulic pump 19 via the electromagnetic valve 14.
The brake 20 includes a brake disc 16 and a brake caliper 17. The brake disc 16 is mechanically coupled so as to rotate integrally with the wind turbine rotor hub 11. The brake caliper 17 includes a brake pad (not shown) on the surface facing the brake disc 16, and the brake caliper 17 moves the brake disc 16 through the brake pad by the working fluid supplied when the electromagnetic valve 14 is turned on. Clamping and braking of the rotation of the brake disc 16 are performed. By braking the rotation of the brake disc 16 in this way, the rotation of the wind turbine rotor hub 11 is adjusted or the rotation is stopped.

The control unit 18 determines that a low-voltage event has occurred when the voltage of the power system 15 is lower than the first threshold, and determines the rotation speed of the generator 13 for the generator 13 that can obtain the synchronous speed and the rated output. The brake 20 is controlled so that the rotational speed is between the rotational speeds. Low voltage events include, for example, short duration voltage drop patterns required by LVRT. The generator rotational speed is preferably a substantially synchronous speed. Specifically, the control unit 18 determines whether or not the voltage measurement result acquired from the voltmeter 9 is smaller than the first threshold. If the voltage measurement result is smaller than the first threshold, it is determined that a low voltage event has occurred. To do.
The control unit 18 controls the number of revolutions of the generator 13 by controlling the brake 20 on and off. Specifically, the control unit 18 outputs an on / off control signal for the electromagnetic valve 14 to the electromagnetic valve 14, and controls the brake 20 on / off by switching the on / off state of the electromagnetic valve 14.

  The control unit 18 functions as, for example, an auxiliary storage device such as a CPU (Central Processing Unit) that executes various arithmetic processes, a ROM (Read Only Memory) that is a read-only memory that stores basic programs, and the like, and a work area for the CPU. A computer system having a main storage device such as a random access memory (RAM), which is a readable / writable memory, and a storage device for storing programs and various data. For example, a control program for the wind turbine generator is stored in the ROM of the controller 18. A series of processing steps for realizing various functions, which will be described later, is realized by the CPU reading the arithmetic program into a RAM or the like and executing information processing / arithmetic processing.

FIG. 2 is a diagram showing an example of trends in the voltage, power, and rotation speed of the generator when brake control is performed. FIG. 3 is an operation flow showing a process of brake control related to the rotational speed control of the wind turbine generator 1 according to the present embodiment. Below, the effect | action of the wind power generator 1 which concerns on this embodiment is demonstrated using FIG.2 and FIG.3. Here, the case where the synchronization speed of the generator 13 is 1500 [rpm] and the slip at which the rated output is obtained is 2% will be described as an example.
In the control device 18, the voltage value of the interconnection point Y between the wind power generator 1 and the power system 15 is acquired (step SA1). It is determined whether or not the voltage value of the interconnection point Y is smaller than a first threshold value (for example, 0.6 [pu]) (step SA2). If not smaller than the first threshold value, the process returns to step SA1 to perform the processing. repeat.

  When a low voltage event occurs on the power system 15 side at time 1 [second] in FIG. 2 and the voltage value at the interconnection point Y becomes smaller than the first threshold value, the rotational speed of the generator 13 is reduced. Information is acquired (step SA3), and it is determined whether or not the generator rotational speed is larger than a third threshold (for example, 1530 [rpm] (= 1500 [rpm] + 1500 × 2 [%])) (step SA6). ). If the generator speed is not greater than the third threshold value, the process returns to step SA1 and the process is repeated.

  When the generator rotational speed is larger than the third threshold (for example, around time 1.4 [second] in FIG. 2), the brake control is turned on, and the control device 18 controls the electromagnetic valve 14 to be turned on / off. A signal ON signal is output (step SA7), and the process returns to step SA1 to repeat the process. The electromagnetic valve 14 controls the valve opening degree to an on state based on the acquired on signal, and operates the brake 20 with the working fluid from the hydraulic pump 19. When the solenoid valve 14 is turned on and the brake 20 is driven, the brake caliper 17 sandwiches the brake disc 16 rotating together with the wind turbine rotor hub 11, and the frictional force between the brake caliper 17 and the brake disc 16 causes The rotation of the brake disc 16 is decelerated.

  Then, as shown in FIG. 2 (c), since the brake control is performed when the generator rotational speed increases to 1530 [rpm], the rotational speed decreases thereafter. Then, the process returns to step SA1 to repeat the process. In the present embodiment, as shown in FIG. 2 (c), the brake control is performed twice near time 1.4 [seconds] and 2.0 [seconds], and the generator rotational speed is substantially reduced. Since the control is performed so as to achieve the synchronous speed, the reactive power consumed by the generator 13 is reduced as compared with the reactive power consumption shown in FIG. 7B as shown by the dotted line in FIG. Yes.

Thereafter, when the voltage of the power system returns, as shown in FIG. 2A, the system voltage gradually rises and the interconnection point voltage also rises.
Further, the control unit 18 not only determines whether the voltage at the interconnection point Y is smaller than the first threshold value, but also determines whether the voltage is larger than a second threshold value (for example, 0.8 [pu]) larger than the first threshold value. It is determined whether or not (step SA4). If it is not larger than the second threshold value, the process returns to step SA1 to repeat this process. If the voltage value at the interconnection point Y is greater than the second threshold value, the brake control is turned off (step SA5), and this process ends.

  When the brake control is turned off, an off signal of an on / off control signal is output from the control unit 18 to the electromagnetic valve 14, and the valve opening degree of the electromagnetic valve 14 is turned off. As a result, the windmill blade 10 is operated without being brake-controlled, and since the pitch angle control for the rotational speed control is not performed when a low voltage event occurs, the solid line in FIG. As shown, the active power does not drop after voltage recovery.

Even if the voltage at the interconnection point Y is smaller than the first threshold value, if the generator speed is smaller than the fourth threshold value (step SA8), the brake control is turned off (step SA9). Return to step SA1.
Further, as shown in FIG. 2 (a), as in this embodiment, the generator rotation speed is controlled by brake control and the consumption of reactive power is suppressed, so that the voltage value of the interconnection point voltage is The voltage value of the voltage is accurately followed.

As described above, according to the wind turbine generator 1 and the method and program according to the present embodiment, the control unit 18 that controls the brake 20 that brakes the rotation of the windmill rotor hub 11 that is rotated by the wind power includes the power system 15. It is determined that a low-voltage event has occurred when the voltage of the current becomes lower than the first threshold, and the rotational speed of the rotor becomes the rotational speed between the synchronous speed and the rotational speed of the generator 13 that can obtain the rated output. The brake 20 is controlled as follows.
Thus, since the rotation speed of the generator 13 is controlled using the brake 20 that brakes the rotation of the wind turbine rotor hub 11 provided on the shaft of the wind turbine generator 1, the invalidity generated when the generator rotation speed increases. Power consumption can be suppressed, and the voltage at the interconnection point Y can be quickly restored. Further, when the rotational speed is controlled by the pitch angle of the windmill blade 10, the pitch angle is set to the feather side. However, in the present invention, the rotational speed is not controlled by the pitch angle. In addition, active power does not drop.

  Further, when the generator rotational speed is controlled by controlling the pitch angle of the windmill blade 10, the active power returns to the rated operation around time 5 [seconds] as shown by the solid line in FIG. However, in the present invention, as indicated by the solid line in FIG. 2 (b), the active power is the rated operation after about 0.5 [seconds] after the power system is restored around time 2.8 [seconds]. Has returned to. Thus, compared with the case where brake control is not performed, in the present invention, the time required for voltage recovery can be shortened (in the above example, about 2 [seconds]).

  Further, the present invention may be applied to a wind power generator having a stall control mechanism that does not have a pitch control mechanism.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment in that the control unit of the wind turbine generator according to the first embodiment performs feedback control of the brake instead of performing on / off control of the brake. About the wind power generator of this embodiment, description is abbreviate | omitted about the point which is common in 1st Embodiment, and a different point is mainly demonstrated.

The control unit performs feedback control (for example, PID) so that the rotational speed of the generator matches the target rotational speed set in the rotational speed range between the synchronous speed and the rotational speed of the generator at which the rated output is obtained. Control, PI control). For example, a servo valve is used instead of the electromagnetic valve 14 in FIG. In the case of PID control, the information on the generator rotational speed is fed back to the control unit, and proportional control (P control), integral control (I control) and differential control (differential control) for the servo valve are performed by a PID controller provided in the control unit. A control amount (servo valve opening command signal) based on (D control) is generated. The controller outputs the generated servo valve opening command signal to the servo valve, and adjusts the valve opening of the servo valve to adjust the flow rate of the working fluid circulated from the hydraulic pump side to the brake side in a stepwise manner. adjust.
In this way, since the generator speed can be controlled accurately by feedback control so that the generator speed matches the target speed, the control of reactive power consumption and the return of active power are controlled by on / off control. Compared with, it can be done effectively.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described. A schematic configuration of the wind turbine generator according to the third embodiment will be described with reference to FIGS. 4 to 6. In addition to the configuration of the wind turbine generator according to the first embodiment, the present embodiment includes a power adjustment unit (power adjustment means) 21 as shown in FIG. Different from the second embodiment. About the wind power generator 1 'of this embodiment, description is abbreviate | omitted about the point which is common in 1st Embodiment, 2nd Embodiment, and a different point is mainly demonstrated.

As shown in FIG. 4, the wind turbine generator 1 ′ includes a power adjustment unit 21 between the generator 13 and the power system 15.
The power adjustment unit 21 determines that the system has been restored when the voltage value of the power system 15 becomes larger than the second threshold after the occurrence of the low voltage event of the power system 15, and the output power value of the wind power generator 1 ' However, the power is adjusted so as to be the power value immediately before the occurrence of the low voltage event.

Specifically, the power adjustment unit 21 includes an AC / DC converter 212 and a power storage device 211 that stores electricity.
The AC / DC converter 212 is an AC / DC converter that converts AC and DC. For example, in order to supply the active power determined by the control unit 18 to the power system 15, the AC / DC converter 212 is stored in the power storage device 211. The converted DC power is converted into AC power, and the converted AC power is output to the power system 15.
The power storage device 211 is, for example, a secondary battery such as a lithium ion battery, a lead storage battery, a sodium sulfur battery, or a redox flow battery. The power storage device 21 is not limited to supplying power to the power system 15 side, and may be used as a power supply source that supplies power to the control unit 18.

After controlling the brake 20, the control unit 18 determines whether or not the active power value at the interconnection point Y is a value immediately before the occurrence of the low voltage event. For example, after system recovery, the output decreases due to an event such as a decrease in wind speed, and the active power value may become smaller than the power value immediately before the low voltage event occurs, as indicated by X in FIG. . In such a case, the control unit 18 supplies power from the power adjustment unit 21 to the power system 15 side, and raises the active power value to a value immediately before the occurrence of the low voltage event. As a result, as shown in FIG. 6B, a drop in the active power does not occur after the power return.
In this way, by supplementing the active power with the power stored in the power storage device 211, stable active power can be supplied to the power system 15 side even when an event such as a change in wind speed occurs.
In addition, reactive power can be supplied from the power storage device 211 to the power system 15 side in order to accelerate voltage recovery after a low voltage event. Thereby, a power system voltage can be stabilized more.

1, 1 'Wind power generator 13 Generator (induction generator)
15 Power system 16 Brake disc 17 Brake caliper 18 Control unit (control means)
20 Brake

Claims (8)

A wind power generator that includes a rotor that is rotated by wind power, a fixed-speed induction generator that is driven by the rotation of the rotor, and a brake that brakes the rotation of the rotor, and is linked to an electric power system,
It is determined that a low-voltage event has occurred when the voltage of the power system is lower than a first threshold, and the number of revolutions of the induction generator is determined from the number of revolutions of the induction generator capable of obtaining a synchronous speed and a rated output. A wind power generator comprising control means for controlling the brake so as to achieve a rotational speed between   The wind power generator according to claim 1, wherein the control means controls the number of revolutions of the induction generator by controlling the brake on and off.   The control means feeds back the rotation speed of the induction generator to a target rotation speed set in a range of rotation speeds between the synchronous speed and the rotation speed of the induction generator at which a rated output is obtained. The wind power generator according to claim 1 to be controlled. Comprising power adjusting means between the induction generator and the power system;
The power adjustment means determines that the system has been restored when the voltage value of the power system becomes greater than a second threshold after the occurrence of the low voltage event of the power system, and the output power value of the wind turbine generator The wind power generator according to any one of claims 1 to 3, wherein the power is adjusted so that the power value immediately before the occurrence of the low-voltage event becomes a power value.   The wind power generator according to claim 4, wherein the power adjustment unit is a power storage device capable of storing electricity.   The wind power generator according to claim 5, wherein the power storage device supplies power to the control unit. A control method for a wind power generator that is connected to an electric power system, comprising: a rotor that is rotated by wind power; a fixed-speed induction generator that is driven by rotation of the rotor; and a brake that brakes rotation of the rotor. There,
It is determined that a low-voltage event has occurred when the voltage of the power system is lower than a first threshold, and the number of revolutions of the induction generator is determined from the number of revolutions of the induction generator capable of obtaining a synchronous speed and a rated output. A method for controlling a wind turbine generator, wherein the brake is controlled to achieve a rotational speed between A control program for a wind turbine generator connected to an electric power system, comprising: a rotor that is rotated by wind power; a fixed-speed induction generator that is driven by the rotation of the rotor; and a brake that brakes the rotation of the rotor. There,
It is determined that a low-voltage event has occurred when the voltage of the power system is lower than a first threshold, and the number of revolutions of the induction generator is determined from the number of revolutions of the induction generator capable of obtaining a synchronous speed and a rated output. A control program for a wind turbine generator for causing a computer to control the brake so as to achieve a rotational speed of between.

Images