JP2003324848A - Method and system for maintaining parallel operation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and economically realize stable parallel operation with a parallel operation inverter without the use of a storage battery, in a parallel operation system of a wind generator and a power transmission line. <P>SOLUTION: A parallel operation maintaining system 16 is connected parallel to a parallel operation inverter 14. The parallel operation maintaining system 16 converts an AC power of a power transmission line 15 into a DC power by an AC-DC conversion means, comprising a rectification/smoothing circuit of the parallel operation maintaining system 16 and an insulation type DC/DC convertor, and supplies it to the parallel operation inverter 14 for maintaining parallel operation. The parallel operation maintaining system 16 starts operation of the insulating type DC/DC convertor, if the wind speed of a wind meter 17 is higher than a prescribed value, while stops operation if lower than it. A brake circuit release circuit 13 shuts the output of a rectifier 12, while the insulating type DC/DC convertor is stopped. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system linkage maintenance device and a system linkage maintenance method in a system linkage system of a wind power generator and a transmission line.

[0002]

2. Description of the Related Art Conventionally small wind power generators (for example, several tens of k)
(W or less) when supplying the generated power to the power transmission line of the power company, in order to prevent the power transmission of the power company from being hindered by fluctuations in the power generation voltage of the wind power generator, etc. Connecting an inverter to connect the wind power generator and the power transmission line.

FIG. 3 is a block diagram of a conventional system for linking a wind power generator and a power transmission line. Since the wind power generator 1 normally uses a three-phase AC generator, the AC power generated by the wind power generator 1 is converted into DC power by the rectifier 2 and supplied to the grid interconnection inverter 3. System linkage inverter 3
Converts DC power into AC power, adjusts it so as not to hinder power transmission by the power company, and supplies the power to the power transmission line 4.

The grid-connected inverter 3 is generally replaced by one for solar power generation. However, the generated voltage of the solar power generator fluctuates little, whereas the generated voltage of the wind power generator fluctuates significantly, so the grid-connected inverter for solar power generation is not sufficient as a grid-connected inverter for wind power generators. Met. For example, the grid-coupling inverter 3 allows the grid-coupling for about 5 minutes in anticipation of safety even when the generated voltage of the wind power generator 1 reaches a predetermined value (for example, the output voltage of the rectifier 2 is 130V DC) at the start of the grid-cooperation. Designed not to start. Further, during the grid connection, the wind power disappears and the power generation voltage of the wind power generator 1 becomes equal to or lower than a predetermined value. Once the power grid connection is stopped, even if the wind is generated and the power generation voltage becomes equal to or higher than the predetermined value again, the grid connection is stopped. It takes time to decide whether or not to start, and the grid connection is not restarted immediately.

Since the wind power generator 1 is in a no-load state for the 5 minutes and during the judgment as to whether or not to restart the grid connection, the rotation speed rapidly increases and the power generation voltage becomes high. There is a risk that the diode, capacitor, or the diode, capacitor, etc. of the grid-connected inverter will be damaged.

As a method of eliminating this inconvenience, the system linkage system of FIG. 4 can be considered. In the system linkage system of FIG. 4, the storage battery 5 is connected to the output of the rectifier 2 via the diode D and the charging / discharging control circuit 6, and the storage battery 5 is once charged with the power of the rectifier 2 so that the charging voltage becomes a predetermined value or more. Then, the charging / discharging control circuit 6 closes the switch S to discharge the system-linked inverter 3 at once. As described above, the system linkage system of FIG. 4 temporarily stores the power of the wind power generator 1 in the storage battery 5, and the power of the storage battery 5 causes the system linkage inverter 3 to operate.
Maintain the system linkage of.

The system linkage system of FIG. 4 can eliminate the disadvantage of FIG. 3, but the storage battery 5 has a short life because it is repeatedly charged and discharged, and needs to be replaced in a short period of time. For example, the generated power of the wind power generator 1 is 2 kW, the output voltage of the rectifier 2 is 200 V
When the storage capacity of the storage battery 5 is 40 Ah (15 storage batteries of 12 V each are connected in series) and the charging current is 10 A, when the wind power generator 1 is fully operated, the charging time of the storage battery 5 is about 4 hours and the discharging time is about 4 hours. Will be about 2 hours. Since the life of the storage battery 5 is about 300 discharges, in the case of this example,
The storage battery 5 needs to be replaced in about one year. Therefore, in the case of FIG. 4, the cost of the storage battery is high, the burden of maintenance work and expenses of the storage battery and the like is large, and the construction cost of the storage battery and the like is also high.

[0008]

In view of the problems of FIGS. 3 and 4 described above, the present invention makes it possible to maintain stable system linkage of the system linkage inverter without using a storage battery and to perform maintenance. It is an object of the present invention to provide a system interconnection maintenance device and a system interconnection maintenance method that are low in construction cost and easy in maintenance.

[0009]

A system linkage maintenance device of the present invention is a system linkage maintenance device for a system linkage system of a wind power generator and a transmission line, in which AC power of the transmission line is converted to DC power by AC / DC conversion means. It is characterized in that the DC power is converted into power and the DC power is fed to the grid-connected inverter. The system linkage maintaining apparatus of the present invention is the above system linkage maintaining apparatus, wherein the AC / DC converting means is a rectifying / smoothing circuit and an insulation type D.
It is characterized by comprising a C / DC converter. The system linkage maintaining device of the present invention is the second system linkage maintaining device, wherein the insulation type DC / DC converter starts power supply to the system linkage inverter when the wind speed of the anemometer exceeds a predetermined value, and the anemometer. The power supply to the grid-connected inverter is stopped when the wind speed becomes lower than a predetermined value.

A grid connection maintaining method of the present invention is a grid link maintaining method for a grid linking system of a wind power generator and a transmission line, wherein AC power of a transmission line is converted into DC power by an AC / DC converting means, and the DC It is characterized in that power is supplied to the grid-connected inverter. The system linkage maintaining method of the present invention is characterized in that, in the system linkage maintaining method, the AC / DC converting means includes a rectifying / smoothing circuit and an insulation type DC / DC converter. The system linkage maintaining method of the present invention is the second system linkage maintaining method, wherein the insulation type DC / DC converter starts feeding power to the system linkage inverter when the wind speed of the anemometer exceeds a predetermined value.
When the wind speed of the anemometer becomes smaller than a predetermined value, the power supply to the system linkage inverter is stopped.

[0011]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described with reference to FIGS. The same reference numerals are used for the common parts in each drawing.

FIG. 1 is a schematic diagram of a system linkage system of a wind power generator and a transmission line using a system linkage maintenance device according to an embodiment of the present invention. In FIG. 1, 11 is a three-phase AC wind power generator, 12 is a rectifier, 13 is a brake circuit / disconnecting circuit, 14 is a grid connection inverter, 15 is a power company transmission line, 16 is a grid connection maintenance device, and 17 is an anemometer. Is.

The output of the wind power generator 11 is converted into DC power by the rectifier 12, and the system linkage inverter 14 is provided via the brake circuit / disconnection circuit 13 and the diode D1.
Supply to. The grid interconnection inverter 14 converts DC power into AC power and supplies the AC power to the power transmission line 15.

On the other hand, the system interconnection maintenance device 16 is connected in parallel to the system interconnection inverter 14 and converts the AC power of the transmission line 15 into DC by AC / DC converting means consisting of a rectifying / smoothing circuit and an insulation type DC / DC converter which will be described later. It is converted into electric power and supplied to the grid interconnection inverter 14. Since the system linkage inverter 14 maintains the system linkage with the DC power supplied from the system linkage maintenance device 16, it is not necessary to provide a storage battery for maintaining the system linkage as in the conventional case. The AC / DC converting means may be composed of only a rectifier, but it is desirable to use an insulating DC / DC converter in order to prevent electric power from flowing into the system linkage maintaining device 16.

The system linkage maintenance device 16 is used for the wind power generator 11
The wind speed is measured by the anemometer 17 attached to the. When the wind speed becomes higher than a predetermined value, the operation of the DC / DC converter is started, and when it becomes lower than the predetermined value, the operation of the DC / DC converter is stopped. That is, when the wind speed becomes lower than the predetermined value and the wind power generator 11 is stopped, the system linkage maintaining device 16 stops the operation of the DC / DC converter and stops the system linkage of the system linkage inverter 14.

While the wind power generator 11 is stopped,
The DC / DC converter can be operated to maintain the system linkage of the system linkage inverter 14, but since the power of the transmission line 15 is consumed during that period, the DC / DC is maintained while the wind power generator 11 is stopped. It is more economical to shut down the converter. However, in this case, most of the DC power for grid interconnection obtained from the power transmission line 15 is returned to the power transmission line 15 again via the grid interconnection inverter 14, so that all of the DC power is a DC / DC converter or a grid interconnection inverter. Not consumed by 14. Therefore, while the wind power generator 11 is stopped, whether to stop the operation of the DC / DC converter or to continuously operate the DC / DC converter depends on the environment in which the wind power generator 11 is installed. It may be decided in consideration of the frequency of occurrence of pods.

The system linkage maintaining device 16 is used for the wind power generator 11
Of the brake circuit / disconnection circuit 1 when the generated voltage of the DC / DC converter becomes much higher than the output voltage of the DC / DC converter, or while the DC / DC converter stops operating.
3 is controlled to cut off the output of the rectifier 12. For example,
The switch S1 of the brake circuit / separation circuit 13 is closed, and the switches S2 and S3 are opened. Wind generator 11
Can also be stopped by a mechanical brake, in which case a brake circuit can be provided to drive the mechanical brake. The diode D1 is a diode for preventing backflow, and the output power of the system linkage maintaining device 16 is the rectifier 12.
Prevents backflow to the side.

FIG. 2 is a configuration diagram of the system linkage maintaining device 16 according to the embodiment of the present invention. In FIG. 2, 21
Is a power generation voltage detection circuit that detects the power generation voltage of the wind power generator 11, 22 is a current detection circuit that detects the output current of the DC / DC converter 24, and 23 is a voltage that detects the output voltage of the DC / DC converter 24 The detection circuit 24 is an isolated DC that converts a DC input voltage into a predetermined DC output voltage.
/ DC converter, 25 is a rectifying / smoothing circuit for converting AC power of the transmission line 15 into DC power, and 26 is an anemometer 1
7, A / D converter that converts the analog signals of the generated voltage detection circuit 21, the current detection circuit 22 and the voltage detection circuit 23 into digital signals, 27 compares the signal of the A / D converter 26 with the set value of the setting circuit 29 An operation control circuit for generating a control signal, 28 is a PWM generation circuit for generating a PWM signal having a pulse width corresponding to the control signal of the operation control circuit 27, 29 is a power supply voltage of the DC / DC converter 24,
It is a setting circuit for setting a power supply current, a power supply start wind speed, a power supply duration time, and the like.

Rectifying / smoothing circuit 24 and insulation type DC / D
The C converter 25 constitutes an AC / DC converting means of the system linkage maintaining device 16. In addition, the A / D converter 26,
The arithmetic control circuit 27, the PWM generation circuit 28 and the like may be configured integrally with the CPU and configured to input a set value from the outside.

The rectifying / smoothing circuit 28 converts the AC voltage (100 V or 200 V) of the power transmission line 15 into a DC voltage and converts it into DC /
Supply to the DC converter 24. The DC / DC converter 24 converts the DC voltage supplied from the rectifying / smoothing circuit 25 into a DC voltage having a predetermined value, and supplies the DC voltage to the system linkage inverter 14.

The DC / DC converter 24 is controlled by the PWM signal of the PWM generating circuit 28, and has a function of starting power supply to the grid-linkage inverter 14, stopping power supply, or generating a power supply voltage or power supply current of a predetermined value.

Then, the start / stop of power supply of the DC / DC converter 24, the generation of power supply voltage and power supply current, etc. will be described. The A / D converter 26 includes an anemometer 17, a generated voltage detection circuit 21, a current detection circuit 22, and a voltage detection circuit 2.
When receiving the outputs of No. 3, the outputs are converted into digital signals and sent to the arithmetic control circuit 27. The arithmetic control circuit 27 compares the digital signal with the power supply start wind speed, the power supply voltage, the power supply current, etc. set in the setting circuit 29 to generate a control signal and sends it to the PWM generation circuit 28. The PWM generation circuit 28 has a pulse width PW corresponding to the control signal.
The M signal is generated and sent to the DC / DC converter 24. When the DC / DC converter 24 is in the stopped state, it starts the operation when it receives the PWM signal, and stops the operation when the PWM signal stops.

Next, the anemometer 17 will be described. The arithmetic control circuit 27 compares the wind speed of the anemometer 17 with the power feeding start wind speed set in the setting circuit 29, and the wind speed of the anemometer 17 is
When it is higher than the set power supply start wind speed (for example, 2.5 m / s), the power supply start signal is sent to the PWM generation circuit 28. When the wind speed of the anemometer 17 becomes lower than the set power supply start wind speed, the arithmetic control circuit 27 sends a power supply stop signal to the PWM generation circuit 28. Upon receiving the power supply stop signal, the PWM generation circuit 28 stops sending the PWM signal. When the PWM signal stops, DC / D
The C converter 24 stops power supply. When the DC / DC converter 24 stops the power supply, the arithmetic control circuit 27
After the power supply continuation time set by the setting circuit 29 has elapsed,
For example, after 10 minutes, the power supply stop signal is sent to the PWM generation circuit 28. When the wind speed of the anemometer 17 becomes higher than the set value during the 10 minutes, the DC / DC converter 24 continues without stopping the power supply.

The power supply start signal of the arithmetic control circuit 27 is also sent to the brake circuit / separation circuit 13, the switch S1 of the brake circuit / separation circuit 13 is opened, and the switch S
2, S3 is closed, and the rectifier 12 is connected to the grid-connected inverter 1
Connect to 4. Further, the power supply stop signal of the arithmetic control circuit 27 is also sent to the brake circuit / disconnection circuit 13 to close the switch S1 and open the switches S2 and S3 to cut off the output of the rectifier 12.

The DC / DC converter 24 starts power supply in response to the power supply start signal from the arithmetic control circuit 27, and starts power supply to the system linkage inverter 14. With the start of this power feeding, the system linkage inverter 14 starts system linkage.
Since the grid-coupling inverter 14 has the characteristic that, when the grid-coupling is started, the grid-coupling inverter 14 shifts to the grid-coupling state more quickly as the power generation amount of the wind power generator 11 is larger.
Has a large output (eg DC200
V, DC5A), and after the grid connection is started, the minimum output required for maintaining the grid connection (for example, DC150V,
Switch to DC 0.5A).

The switching control is performed by the arithmetic control circuit 27.
Do. The arithmetic control circuit 27 compares the detection values of the current detection circuit 22 and the voltage detection circuit 23 with the power supply voltage and the power supply current set in the setting circuit 29, and confirms that the system-linked inverter 14 has transitioned to the system-linked state. Then do.

Next, the generated voltage detecting circuit 21 will be described. The calculation control circuit 27 determines that the power generation voltage of the wind power generator 11 detected by the power generation voltage detection circuit 21 is DC / DC.
If the power supply voltage becomes much higher than the power supply voltage of the converter 24 (for example, 350 V), the brake circuit
A control signal is sent to the disconnecting circuit 13. The brake circuit / disconnection circuit 13 closes the switch S1 and opens the switches S2 and S3 to cut off the output of the rectifier 12.

In the diode D2, the power generation voltage of the wind power generator 11 becomes high and the output of the wind power generator 11 becomes DC / DC.
It is prevented from flowing into the converter 24 side. Further, when the DC / DC converter 24 starts to operate when the grid-linked inverter 14 is stopped and the DC / DC converter 24 starts to operate, the capacitor C1 waits until the grid-linked inverter 14 starts to operate (for example, several seconds). ~ Tens of seconds), wind power generator 1
The electric power generated by No. 1 is stored, and the wind power generator 11 is prevented from being in a no-load state and the generated voltage suddenly rising. The electric power stored in the capacitor C1 is supplied to the grid-connected inverter 1
When No. 4 starts operating, it is supplied to the grid interconnection inverter 14.

[0029]

According to the present invention, the electric power necessary for maintaining the system cooperation of the system cooperation inverter is generated from the power of the transmission line by the AC / DC converting means, and thus the conventional expensive storage battery is not required. Further, according to the present invention, since the storage battery is not used, the life of the system linkage maintenance device is long, the configuration is simple, the installation space is small, and the maintenance work load is small. Further, according to the present invention, since the storage battery is not used, maintenance and construction costs of the system linkage maintaining device are reduced.

According to the present invention, since the insulation type DC / DC converter is used as the AC / DC converting means of the system linkage maintaining device, it is possible to prevent electric power from flowing from the system linkage inverter side to the system linkage maintaining device side. According to the present invention, when the wind power generator is stopped, the power supply to the DC / DC converter 24 is stopped to stop the grid connection, so that the grid link power can be saved.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a system linkage system of a wind power generator and a transmission line, which uses a system linkage maintenance device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a system linkage maintenance device according to an embodiment of the present invention.

FIG. 3 is a block diagram of a conventional wind power generator-power transmission line system linkage system.

FIG. 4 is a block diagram of a conventional system for linking a wind power generator and a transmission line.

[Explanation of symbols]

11 wind power generator 12 Rectifier 13 Brake circuit / separation circuit 14 grid-connected inverter 15 power lines 16 system linkage maintenance device 17 Anemometer 21 Generation voltage detection circuit 22 Current detection circuit 23 Voltage detection circuit 24 Isolated DC / DC converter 25 Rectification / Smoothing circuit 26 A / D converter 27 Arithmetic control circuit 28 PWM generation circuit 29 Setting circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H02P 9/00 H02P 9/00 F (72) Inventor Yuki Iwata Togane-shi, Chiba 696-3 F term ( Reference) 3H078 AA26 CC22 CC52 CC72 5G066 HA30 HB02 HB05 5H590 AA08 CA14 CD01 CD03 CD10 CE01 FA08 FB01 GA02 GA04 HA02 HA04 HA11 JA02 JB04 5H730 AA13 AS00 AS01 BB21 CC01 EE02 EE07 FD01 FD21 FD31 FD05 FD61 FD61FD05FD61

Claims (6)

[Claims] 1. A system interconnection maintenance device for a system interconnection system of a wind power generator and a transmission line, wherein AC power of a transmission line is converted into DC power by AC / DC converting means, and the DC power is supplied to a system interconnection inverter. A system linkage maintenance device characterized by: 2. The system linkage maintaining device according to claim 1, wherein the AC / DC converting means includes a rectifying / smoothing circuit and an insulating DC / DC converter. 3. The system linkage maintaining device according to claim 2, wherein the insulation type DC / DC converter starts supplying power to the system linkage inverter when the wind speed of the anemometer exceeds a predetermined value, and the wind speed of the anemometer is measured. Is less than a predetermined value, power supply to the grid connection inverter is stopped. 4. A method for maintaining system linkage of a system for linking a wind power generator and a power transmission line, wherein AC power of a power transmission line is converted to DC power by AC / DC converting means, and the DC power is supplied to a system linkage inverter. A method for maintaining system interconnection characterized by: 5. The system linkage maintaining method according to claim 4, wherein the AC / DC converting means comprises a rectifying / smoothing circuit and an insulating DC / DC converter. 6. The system linkage maintenance device according to claim 5, wherein the insulated DC / DC converter starts power supply to the system linkage inverter when the wind speed of the anemometer exceeds a predetermined value, and the wind speed of the anemometer is measured. Is less than a predetermined value, the system linkage maintaining method is characterized in that power supply to the system linkage inverter is stopped.