WO2013073559A1 - Wind power generation device and method, and program - Google Patents

Abstract

The purpose of the invention is to suppress active power drop and reactive power consumption when a power system returns to normal after the occurrence of a low voltage event of the power system. A wind power generation device (1) comprises: a wind turbine rotor hub (11) rotated by wind power; a fixed-speed induction generator (13) driven by the rotation of the wind turbine rotor hub (11); and a brake (20) for braking the rotation of the wind turbine rotor hub (11). The wind power generation device (1) is interconnected to a power system (15) and equipped with a control unit (18) for, when the voltage of the power system (15) becomes less than a first threshold value, determining that a low voltage event occurs and controlling the brake (20) so that the rotation speed of the induction generator (13) becomes a rotation speed between a synchronous speed and a rotation speed of the induction generator (13) capable of obtaining a rated output.

Description

Wind turbine generator and method and program

The present invention relates to a wind turbine generator, method and program.

In recent years, guidelines for power grid connection requirements for wind power generation facilities have been prepared, and it is necessary to adapt the installed wind power generation equipment to the grid connection requirements. In addition, operation that minimizes influence on the power system without disconnecting the wind turbine from the power system side when a low voltage event of the power system for a short time occurs due to the occurrence of a power system accident. 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 drops due to the occurrence of an accident on the power system side, the generator of the wind turbine generator has its speed increased by removing the load. As the wind turbine generator breaks down as the wind turbine rises, a technology to control the rotation speed to prevent a breakdown is considered.
According to Patent Document 1 below, when an accident occurs in the power system, the pitch angle of the wind turbine blade is controlled to prevent over-rotation of the generator accompanying the accident, and the voltage value of the power system is restored to the state before the accident. In such a case, a technology has been proposed in which the pitch angle is controlled to control the rotational speed within the operable region, and the time until resumption of operation is shortened.

Also, for example, when the voltage of the power system recovers from a drop, 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 device. A technology has been proposed that controls the pitch angle of the wind turbine blade so that it is equal to or higher than the rotational speed, and prevents large torque generation or anti-load torque generation that occurs when control of the converter and inverter is resumed. (Patent Document 2 below).

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

However, in the case of performing rotation speed control by pitch angle control as in the methods of Patent Document 1 and Patent Document 2 above, the wind turbine blade is on the feather side when the voltage value of the power system returns to the state before the accident. Since it is on the (wind escape side), there is a problem that a drop of the active power value occurs as shown by the solid line in FIG. 7 (b).
Further, at the time of restoration of the voltage value of the electric power system, in the wind power generator mounted with the induction generator in the fixed speed system due to over-rotation, reactive power consumed by the induction generator is as shown in FIG. As shown by the dotted line, it will be more. In such a case, the voltage at the connection point between the wind turbine and the power system will eventually decrease as seen from the power system side, as shown by the solid line in FIG. 7 (a). It does not rise up to the system voltage value (dotted line in FIG. 7 (a)). Conventionally, there is no method for suppressing such reactive power consumption, and there has been a problem that the consumption of reactive power can not be suppressed. Furthermore, the control of the number of revolutions by pitch angle control of the wind turbine blade is not suitable for instantaneous low voltage events 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 the fall of active power and the reactive power consumption at the time of restoration of the voltage value of the power system after the occurrence of a low voltage event of the power system. An object of the present invention is to provide a power generation device and method, and a program.

A first aspect of the present invention includes a rotor that is rotated by wind power, a fixed speed induction generator driven by rotation of the rotor, and a brake that brakes the rotation of the rotor, and is connected to an electric power system It is determined that the low voltage event has occurred when the voltage of the power system becomes smaller than a first threshold, and the synchronous speed and the rated output are obtained. The wind turbine according to claim 1, further comprising: control means for controlling the brake to a rotational speed between the rotational speed of the induction generator and the rotational speed of the induction generator.

According to such a configuration, the control means for controlling the brake for braking the rotation of the rotor rotated by the wind power determines that the low voltage event has occurred when the voltage of the electric power system becomes smaller than the first threshold value. The brake is controlled so that the number of rotations of the rotor is equal to the number of rotations of the synchronous generator and the number of rotations of the induction generator from which the rated output can be obtained.
As described above, 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, the consumption of reactive power generated by the increase of the generator rotation speed is reduced. It can be suppressed, and it can contribute to the quick return of the voltage at the connection point between the power system and the wind turbine. Moreover, although the pitch angle is on the feather side in the case of controlling the number of revolutions according to the pitch angle of the wind turbine blade, in the present invention, the number of revolutions is not controlled by the pitch angle. Power reduction can be reduced. Furthermore, compared with the case where generator rotation speed is controlled by pitch angle control of a windmill blade, when an electric power system resets, the time concerning voltage return in an interconnection point can be shortened. The generator rotational speed controlled by the control means is preferably approximately synchronous.

The control means of the wind power generator may control the number of rotations of the induction generator by performing on / off control of the brake.
The generator rotational speed can be easily controlled by the on-off control.

The control means of the wind turbine generator sets the rotational speed of the induction generator to a target rotational speed set in a range of rotational speeds between the synchronous speed and the rotational speed of the induction generator from which a rated output can be obtained. It is good also as feedback control so that it may correspond.
Since the generator rotational speed can be accurately controlled by performing feedback control so that the generator rotational speed matches the target rotational speed, it is effective to suppress reactive power consumption and restore active power as compared to the case of on / off control. Can be

The wind power generator comprises a power conditioning means between the induction generator and the power system, wherein the power conditioning means is adapted to provide a voltage value of the power system after the occurrence of the low voltage event of the power system. It is also possible to determine that the system has returned to a system when the value of becomes larger than the second threshold, and adjust the power so that the output power value of the wind power generator becomes the power value immediately before the low voltage event occurs.

For example, even if the decrease in wind speed occurs after the system restoration, the power is adjusted to the power value immediately before the low voltage event. Alternatively, if a voltage recovery occurs after a low voltage event and then the wind speed becomes weak, the power supplied to the power system will decrease, increase, decrease, and become unstable. By being adjusted, a stable output is supplied to the power system side.
In addition, reactive power may be supplied by the power adjustment means in order to accelerate voltage recovery after a low voltage event.

The power adjusting unit of the wind turbine generator may be a power storage device capable of storing electricity.
The power storage device can simplify the power adjustment. Further, the power storage device is, for example, a secondary battery such as a lithium ion battery, a lead storage battery, a sodium sulfur battery, a redox flow battery or the like.

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

A second aspect of the present invention comprises a rotor that is rotated by wind power, a fixed speed induction generator driven by the rotation of the rotor, and a brake that brakes the rotation of the rotor, It is determined that the low voltage event has occurred when the voltage of the power system becomes smaller than a first threshold, and the number of revolutions of the induction generator is set to the synchronous speed and the rated speed. It is the control method of the wind power generator which controls the above-mentioned brake to become the number of rotations between the number of rotations of the above-mentioned induction generator from which output is obtained.

A third aspect of the present invention comprises 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 the rotation of the rotor, Control program for a wind turbine generator, wherein it is determined that a low voltage event has occurred when the voltage of the power system becomes smaller than a first threshold, and the number of rotations of the induction It is a control program of a wind turbine for causing a computer to control the brake to have a rotational speed between the rotational speed of the induction generator from which an output can be obtained.

The present invention has an effect that it is possible to suppress the fall of active power and the reactive power consumption at the time of recovery of the voltage value of the power system after the occurrence of the low voltage event of the power system.

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

First Embodiment Hereinafter, an embodiment of a wind turbine generator, method, and 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 1 according to the present embodiment. As shown in FIG. 1, the wind turbine generator 10 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 a power system 15 at an interconnection point Y.
A plurality of wind turbine blades 10 are radially attached to the wind turbine 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 connected and integrally rotatable.

Therefore, the wind turbine blade 10 receives the wind energy, rotates with the wind turbine rotor hub 11, and drives the generator 13 to generate electric power, thereby converting the wind energy into electric energy. The generator 13 is a fixed speed type induction generator, and is, for example, a cage type induction generator.
A voltmeter 9 is provided in the vicinity of an interconnection point Y between the wind turbine 1 and the electric 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 deliver a working fluid (for example, a hydraulic fluid) in a tank (not shown), and the delivered working fluid is fed to the solenoid valve 14.
The solenoid valve 14 is controlled by the controller 18 to turn on and off. The solenoid valve 14 actuates the brake 20 by the working fluid fed from the hydraulic pump 19 when in the on state, and releases the actuation of the brake 20 when in the off state.

Between the gear 12 and the generator 13, a brake 20 for braking the rotation of the wind turbine rotor hub 11 is provided. The brake 20 is connected to the hydraulic pump 19 via a solenoid valve 14.
The brake 20 includes a brake disc 16 and a brake caliper 17. The brake disc 16 is mechanically connected to rotate integrally with the wind turbine rotor hub 11. The brake caliper 17 has a brake pad (not shown) on the surface facing the brake disc 16, and the working fluid supplied when the solenoid valve 14 is turned on causes the brake caliper 17 to transmit the brake disc 16 via the brake pad. It pinches and brakes the rotation of the brake disc 16. By braking the rotation of the brake disk 16 in this manner, the rotation of the wind turbine rotor hub 11 is adjusted or the rotation is stopped.

The control unit 18 determines that the low voltage event has occurred when the voltage of the electric power system 15 becomes smaller than the first threshold, and the rotation speed of the generator 13 can be obtained at the synchronous speed and the rated output. The brake 20 is controlled to have a rotational speed between the rotational speed and the rotational speed. Low voltage events include, for example, the short voltage drop patterns required by LVRT. The generator speed is preferably approximately synchronous. Specifically, the control unit 18 determines whether or not the voltage measurement result obtained from the voltmeter 9 is smaller than the first threshold, and if smaller than the first threshold, it is determined that the low voltage event has occurred. Do.
Further, the control unit 18 controls the number of rotations of the generator 13 by controlling the brake 20 on and off. Specifically, the control unit 18 outputs an on / off control signal of the solenoid valve 14 to the solenoid valve 14 and performs on / off control of the brake 20 by switching the on / off state of the solenoid valve 14.

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

FIG. 2 is a diagram showing an example of the tendency of the voltage, the electric power, and the rotational speed of the generator when the brake control is performed. FIG. 3 is an operation flow showing a process of brake control according to the rotational speed control of the wind turbine 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 synchronous speed of the generator 13 shall be 1500 rpm, and the case where the slip which can obtain a rated output is 2% is mentioned as an example, and is demonstrated.
In the control device 18, the voltage value of the connection point Y between the wind turbine 1 and the power system 15 is acquired (step SA1). It is determined whether or not the voltage value at the interconnection point Y is smaller than a first threshold (for example, 0.6 pu) (step SA2), and if it is not smaller than the first threshold, the process returns to step SA1 and repeats the process.

When a low voltage event occurs on the electric 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, information on the number of revolutions of the generator 13 is It 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 rpm × 2%)) (step SA6). If the generator rotational 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 becomes larger than the third threshold (e.g., around 1.4 seconds in FIG. 2), the brake control is turned on, and the controller 18 outputs an on-off control signal to the solenoid valve 14. An on signal is output (step SA7), and the process returns to step SA1 to repeat the process. The solenoid valve 14 controls the valve opening degree to the on state based on the acquired on signal, and operates the brake 20 by 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 holds the brake disc 16 rotating together with the wind turbine rotor hub 11, and the friction force between the brake caliper 17 and the brake disc 16 The rotation of the brake disc 16 is decelerated.

Then, as shown in FIG. 2C, 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. 2C, the brake control is performed twice at around 1.4 seconds and around 2.0 seconds, and the generator rotational speed becomes approximately the synchronous speed. Since control is performed as described above, 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. 2B.

Thereafter, when the voltage of the power system recovers, as shown in FIG. 2 (a), the system voltage gradually rises and the interconnection point voltage also rises.
The control unit 18 not only determines whether the voltage at the interconnection point Y is smaller than the first threshold, but also determines whether it is larger than the second threshold (e.g., 0.8 pu) larger than the first threshold. It is determined (step SA4). If it is not larger than the second threshold value, the process returns to step SA1 and the present process is repeated. If the voltage value at the connection point Y is larger than the second threshold value, the brake control is turned off (step SA5), and the process ends.

When the brake control is turned off, an off signal of the on / off control signal is output from the control unit 18 to the solenoid valve 14, and the valve opening degree of the solenoid valve 14 is turned off. As a result, the wind turbine blade 10 is operated without being brake-controlled, and since pitch angle control for rotational speed control is not performed when a low voltage event occurs, the solid line in FIG. 2 (b) As shown, the active power does not sink after voltage recovery.

Further, even if the voltage at the interconnection point Y is smaller than the first threshold, if the generator rotational speed is smaller than the fourth threshold (step SA8), the brake control is turned off (step SA9). It returns to step SA1.
Further, as shown in FIG. 2A, as in the present embodiment, by controlling the generator rotational speed by brake control and suppressing consumption of reactive power, the voltage value of the interconnection point voltage is Accurately follow the voltage value of voltage.

As described above, according to the wind turbine generator 1 and the method and program thereof of the present embodiment, the control unit 18 for controlling the brake 20 for braking the rotation of the wind turbine rotor hub 11 rotated by the wind power is the power system 15. It is determined that a low voltage event has occurred when the voltage of V becomes smaller than the first threshold, and the number of rotations of the rotor is the number of rotations between the synchronous speed and the number of rotations of the generator 13 at which rated output can be obtained Control the brake 20 in the same manner.
As described above, since the rotational 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 power generation device 1, invalidity occurs due to the generator rotational speed rising. Power consumption can be suppressed, which can contribute to quick recovery of voltage at interconnection point Y. Moreover, although the pitch angle is on the feather side in the case of controlling the number of revolutions according to the pitch angle of the wind turbine blade 10, in the present invention, the number of revolutions is not controlled by the pitch angle. There is no sinking of active power.

Furthermore, when the generator rotational speed is controlled by pitch angle control of the wind turbine blade 10, the active power returns to the rated operation around 5 seconds as shown by the solid line in FIG. In the present invention, as shown by the solid line in FIG. 2B, the active power returns to the rated operation about 0.5 seconds after the power system is restored near the time 2.8 seconds. As described above, according to the present invention, the time required for the voltage recovery can be shortened (about 2 seconds in the above example) as compared to the case where the brake control is not performed.

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

Second Embodiment The second embodiment of the present invention will be described below. The present embodiment differs 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 (e.g., PID control) so that the rotational speed of the generator matches the target rotational speed set in the range of the rotational speed between the synchronous speed and the rotational speed of the generator from which the rated output can be obtained. Control, PI control). For example, a servo valve is used instead of the solenoid valve 14 of FIG. 1 as a structure of a wind power generator. In the case of performing PID control, the generator rotational speed information is fed back to the control unit, and the PID controller provided in the control unit performs proportional control (P control), integral control (I control) and differential control (P control) on the servo valve. A control amount (servo valve opening command signal) based on D control) is generated. The control unit outputs the generated servo valve opening degree command signal to the servo valve, and adjusts the valve opening degree of the servo valve, thereby gradually stepping up the flow rate of the working fluid to be circulated from the hydraulic pump side to the brake side. adjust.
As described above, since the generator rotational speed can be accurately controlled by performing feedback control so that the generator rotational speed matches the target rotational speed, the case where reactive power consumption suppression and active power recovery are controlled by on / off control You can do it effectively compared to.

Third Embodiment The third embodiment of the present invention will be described below. The schematic configuration of the wind turbine generator according to the third embodiment will be described with reference to FIGS. 4 to 6. The present embodiment, in addition to the configuration of the wind turbine generator according to the first embodiment, includes a power adjustment unit (power adjustment unit) 21 as shown in FIG. It differs from the second embodiment. About wind power generation control device 1 'of this embodiment, explanation is omitted about a point which is common in a 1st embodiment and a 2nd embodiment, and a different point is mainly explained.

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 is 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 turbine 1 ' But adjust the power to a power value just before the low voltage event occurs.

Specifically, the power adjustment unit 21 includes an AC-DC converter 212 and a power storage device 211 that stores power.
The AC-DC converter 212 is an AC-DC converter that converts AC and DC, and for example, in order to supply the active power determined by the control unit 18 to the power system 15, it is stored in the power storage device 211 The direct current power is converted into alternating current power, and the converted alternating current 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. Further, 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 for supplying power to the control unit 18.

After controlling the brake 20, the control unit 18 determines whether the active power value at the connection point Y is a value immediately before the occurrence of the low voltage event. For example, after system restoration, the output may decrease due to an event such as a decrease in wind speed, and the active power value may be 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 causes the power adjustment unit 21 to supply power to the power system 15 side, and boosts the active power value to a value immediately before the occurrence of the low voltage event. As a result, as shown in FIG. 6B, the fall of the active power does not occur after the power recovery.
As described above, by compensating the active power with the power stored in the power storage device 211, stable active power can be supplied to the power grid 15 even if 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 in order to accelerate voltage recovery after a low voltage event. Thereby, the 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 brakes

Claims (8)

1. A wind turbine generator connected to an electric power system, comprising: a rotor that is rotated by wind power; a fixed speed induction generator driven by rotation of the rotor; and a brake that brakes the rotation of the rotor,
   It is determined that a low voltage event has occurred when the voltage of the power system becomes smaller than a first threshold, and the number of rotations of the induction generator is the number of rotations of the induction generator at which synchronous speed and rated output can be obtained. A wind power generator comprising control means for controlling the brake to achieve a rotational speed between.
2. The wind power generator according to claim 1, wherein the control means controls the number of rotations of the induction generator by controlling the brake on and off.
3. The control means performs feedback so that the number of revolutions of the induction generator matches a target number of revolutions set in the range of the number of revolutions between the synchronous speed and the number of revolutions of the induction generator from which a rated output can be obtained. The wind turbine generator according to claim 1, wherein the wind turbine generator is controlled.
4. Power regulation means between the induction generator and the power system,
   The power adjustment unit determines that the system has been restored when the voltage value of the power system becomes larger than a second threshold after the occurrence of the low voltage event of the power system, and the output power value of the wind power generator The wind turbine generator according to any one of claims 1 to 3, wherein the power adjustment is performed so that the power value immediately before the occurrence of the low voltage event occurs.
5. The wind power generator according to claim 4, wherein the power adjustment unit is a power storage device capable of storing electricity.
6. The wind power generator according to claim 5, wherein the power storage device supplies power to the control means.
7. A control method of a wind turbine generator connected to an electric power system, comprising: a rotor rotated by wind power, a fixed speed type induction generator driven by rotation of the rotor, and a brake braking the rotation of the rotor There,
   It is determined that a low voltage event has occurred when the voltage of the power system becomes smaller than a first threshold, and the number of rotations of the induction generator is the number of rotations of the induction generator at which synchronous speed and rated output can be obtained. The control method of the wind power generator which controls the said brake so that it may become the rotation speed in between.
8. A control program of a wind turbine generator connected to an electric power system, comprising: a rotor that is rotated by wind power; a fixed speed induction generator driven by 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 becomes smaller than a first threshold, and the number of rotations of the induction generator is the number of rotations of the induction generator at which synchronous speed and rated output can be obtained. A control program for a wind turbine generator for causing a computer to control the brake to achieve a rotational speed between

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