JP2003259693A - Power converter for parallel wind power generation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of a power conversion circuit for parallel wind power generation being expensive, where the power conversion circuit outputs electric power to an AC power supply system by a plurality of synchronous generators connected to a plurality of windmills. <P>SOLUTION: The power converter comprises respective diode rectifying circuits that are connected to AC sides of a plurality of synchronous generators, respective DC capacitors that are connected to the diode rectifying circuits in parallel and at the same time connect the output side of one diode rectifying circuit to that of the other one in series so that a DC voltage is added, DC/DC converters that are connected to the serial DC capacitors connected in parallel, and a PWM conversion circuit that is connected to the DC/DC converters in parallel. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to parallel wind power generation in which a plurality of wind turbines to which synchronous generators are connected are arranged and which outputs electric power to an AC power supply system, and more particularly, to output of a plurality of synchronous generators. The present invention relates to a power converter for parallel wind power generation that collectively outputs to an AC power supply system.

[0002]

2. Description of the Related Art A power conversion circuit for converting alternating current to direct current from a synchronous generator connected to a wind turbine and further converting direct current to alternating current to take out electric power is known,
The explanation is omitted here. Furthermore, the same applies to a circuit in which a plurality of the power conversion circuits are connected in order to output power to the AC power supply system from a plurality of wind turbines having different rotation speeds. Hereinafter, a power conversion circuit that outputs electric power to the AC power supply system from the above-described conventional synchronous generator connected to a plurality of wind turbines will be described in detail. FIG. 3 is a main circuit connection diagram of a conventional power conversion circuit that outputs electric power to an AC power supply system from a synchronous generator connected to two wind turbines. In FIG. 3, 1 is a first wind turbine, 3 is a first synchronous generator, 5 is a first anemometer, 9 is a first DC capacitor,
14 is a first generator inverter, 16 is a first system inverter, 2 is a second wind turbine, 4 is a second synchronous generator, 6
Is the second anemometer, 10 is the second DC capacitor, 15
Is a second generator inverter, 17 is a second system inverter, and 13 is an AC system power supply.

Synchronous generator 3 driven by a first wind turbine
The AC side of is connected to the first generator inverter 14, and the DC side of the first generator inverter 14 is
First DC capacitor 9 and first system inverter 1
The DC side of 6 is connected in series, and the output of the first anemometer 5 is output to the first generator inverter 14. The AC power of the first synchronous generator 3 driven at a variable speed by the first windmill 1 is converted into the DC power of the variable frequency AC power by the first generator inverter 14, and the It is stored in the DC capacitor 9. The DC power stored in the first DC capacitor 9 is further converted into AC by the first system inverter 16 and output to the AC power supply system 13. This first system inverter 16
Therefore, in order to output the alternating-current power to the alternating-current power supply system 13, the direct-current voltage Vdc1 of the first direct-current capacitor 9 needs to be approximately √2 times the effective value of the alternating-current voltage of the alternating-current power supply system 13 or more. Yes, the DC voltage is controlled by the first generator inverter 14.

FIG. 2 is a diagram for explaining the outline of the wind turbine output with respect to the rotational angular velocity with the wind velocity as a parameter. In the wind turbine, when the shape of the wind turbine is determined, the wind turbine output with respect to the rotational angular velocity of the wind turbine is uniquely determined, and there is a peak in the wind turbine output. That is, in FIG. 2, when the wind speed is U1, the maximum output P1 of the wind turbine at the wind speed U1 is obtained at the rotational angular velocity ω1.
When the wind speed is U2, the wind speed U
The maximum output of the wind turbine at 2 is P2. Then, the wind speed, and the rotational angular velocity and the maximum output of the wind turbine that have the maximum output of the wind turbine have the following relationships. The rotational angular velocity ω1 at the wind speed U1 and the rotational angular velocity ω2 at the wind speed U2 have a relation proportional to the wind speed, and the maximum output P1 of the wind turbine at the wind speed U1.
And the maximum output P2 of the wind turbine at the wind speed U2 have a relation proportional to the cube of the wind speed. First generator inverter 14
Is detected by the first anemometer 5 using the above relationship, and is always controlled at the maximum output commensurate with the wind speed.

The AC side of the second synchronous generator 4 driven by the second wind turbine 2 is connected to the second generator inverter 15, and the DC side of the second generator inverter 15 is connected to the AC side. , The DC side of the second DC capacitor 10 and the second system inverter 17 are connected in series, and the output of the second anemometer 6 is output to the second generator inverter 15. The variable frequency AC power of the second synchronous generator 4 driven at a variable speed by the second wind turbine 2 is converted into DC power by the second generator inverter 15, and is converted into the second DC capacitor 10. It can be stored. The DC power stored in the second DC capacitor 10 is further converted into AC by the second system inverter 17 and output to the AC power system 13. The second generator inverter 15 detects the wind speed from the second anemometer 6 using the above relationship, and is always controlled at the maximum output commensurate with the wind speed.

[0006]

As described above, in the system for outputting electric power to the AC power supply system 13 by the plurality of synchronous generators connected to the plurality of wind turbines, the rotation speed of each synchronous generator is increased. However, there is a problem that it is necessary to connect a plurality of expensive generator inverters and a plurality of grid inverters. The present invention has been made in view of the above circumstances, and the main purpose thereof is to change to a generator inverter, use a diode rectifier and a DC / DC converter, and change to a plurality of system inverters. The purpose of the present invention is to provide an inexpensive power conversion circuit for parallel wind power generation using one PWM conversion circuit.

[0007]

According to the present invention, a plurality of synchronous generators connected to a plurality of wind turbines are used to convert AC power into DC power by a plurality of diode rectifier circuits, respectively. In the system that charges the DC capacitor of, and converts the DC power into AC power and outputs it to the AC power system from the DC power supply in which multiple capacitors are connected in series, the number of revolutions of the synchronous generator differs and Even if the voltage is different, the fact that the currents flowing through the multiple synchronous generators are the same because the multiple DC capacitors are connected in series is used. Furthermore, by controlling the power of the PWM conversion circuit that converts direct current to alternating current based on the wind speed, the maximum output that always matches the wind speed is taken out.

The present invention is based on the above-mentioned principle and solves the above-mentioned problems. Means for achieving the object are 1) and in claim 1, a plurality of wind turbines connected to a plurality of wind turbines. In a power converter that extracts electric power from a synchronous generator and outputs it to an AC power system, each diode rectifier circuit connected to the AC side of the plurality of synchronous generators, and connected in parallel with the diode rectifier circuit and DC output of the diode rectifier circuit and the other of the DC rectifier circuit connected in series with the output side of the other diode rectifier circuit so as to add the DC voltage, and DC / DC connected in parallel with the DC capacitor connected in series. A power converter for parallel wind power generation, comprising a converter and a PWM converter circuit connected in parallel with the DC / DC converter.

2) In claim 2, in the PWM conversion circuit, a plurality of anemometers are provided in the vicinity of the plurality of wind turbines, an average wind speed value is measured by the anemometer, and power control is performed based on the wind speed value. It is an electric power converter of parallel wind power generation of Claim 1 comprised so that it may perform. Less than,
An embodiment of the present invention will be described in detail with reference to the drawings.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a main circuit configuration diagram in which a power converter circuit for outputting power from an synchronous power generator connected to two wind turbines is connected to an AC power supply system of the present invention. Is. In the figure, 7 and 8 are first and second diode rectifier circuits, 11 is a DC / DC converter, and 12 is a PWM conversion circuit. The same numbers as in FIG. 3 represent the same components.
Hereinafter, FIG. 1 will be described. The AC power of the first synchronous generator 3 driven by the first windmill 1 is converted into DC power by the first diode rectifier circuit 7 and stored in the first DC capacitor 9. The AC power of the second synchronous generator 4 driven by the second wind turbine 2 is converted into DC power by the second diode rectifier circuit 8 and stored in the second DC capacitor 10.

The first DC capacitor 9 and the second DC capacitor 10 are connected in series, and the DC output is
DC / DC converter 11 consisting of one for two wind turbines
Is output to. In the DC / DC converter 11, a voltage obtained by adding the DC voltage Vdc1 of the first DC capacitor 9 and the DC voltage Vdc2 of the second DC capacitor 10 is applied, and the PWM
It is converted into a DC voltage required by the conversion circuit 12. Windmill
In the PWM conversion circuit 12 that is composed of one unit for two units, DC /
DC power is input from the DC converter 11, converted into AC power, and output to the AC system power supply 13.

In the parallel wind power generation having such series-connected DC capacitors, the first wind turbine 1 and
When the rotation speed of the second wind turbine 2 is different and the internal induced voltage of each synchronous generator is different, the first DC capacitor 9
The DC voltage Vdc1 and the DC voltage Vdc2 of the second DC capacitor 10 are values proportional to the internal induced voltage of each synchronous generator. However, since the direct currents flowing through the respective DC parts connected in series must be the same, the currents flowing through the respective synchronous generators are also the same currents. Therefore, it is possible to extract electric power proportional to the rotation speed of each wind turbine.

Further, the wind speeds of these wind turbines installed close to each other are the same, and the currents of the synchronous generators are also the same, so that the rotational speeds of the wind turbines may differ due to temporary turbulence of the wind. , Even if the DC voltage of the DC capacitor is unbalanced, the wind force acts so that the loads of these wind turbines are balanced and the rotation speeds are the same, and the DC voltage of the DC capacitor is gradually balanced.

The maximum output value, which is uniquely determined by the wind speed, as shown in FIG. 2, is input to the PWM conversion circuit 12 in advance in a memory or the like in the control circuit. Thereby, PWM
The conversion circuit 12 detects the wind speed from the first anemometer 5 and the second anemometer 6, and uses the average wind speed to output the maximum output that is uniquely determined by the wind speed to the AC system power supply 13. By this operation, the DC voltage values of the first and second DC capacitors 9 and 10 are small in the angular velocity of the maximum output when the wind speed is low, so that the DC voltage is proportional to the induced voltage of the synchronous generator. When the value is small and the wind speed is high, the DC voltage value is large because the rotational angular velocity that provides the maximum output is large. Here, the PWM converter circuit is controlled using the average wind speed, but when the wind turbines 1 and 2 are close to each other, even a wind speed value from one anemometer can sufficiently obtain a value close to the maximum output value.

The embodiment of the present invention has been described above in connection with the case where two wind turbines are connected in parallel, but one DC / DC
It goes without saying that a converter, one PWM converter circuit, and multiple diode rectifier circuits can be applied to three or more parallel wind power generators. Also, the DC voltage when connecting a DC capacitor in series is uncertain, so I explained using the DC / DC converter to adjust the DC voltage to be applied to the PWM power conversion circuit. For example, the DC / DC converter may be omitted because the DC voltage can be maintained sufficiently to be connected to the AC power supply system. Further, a permanent magnet type synchronous generator may be used as the synchronous generator.

[0016]

As described above, according to the present invention, a plurality of synchronous generators connected to a plurality of wind turbines are used to convert AC power into DC power by a plurality of diode rectifier circuits. DC from a DC power source that charges multiple DC capacitors and connects multiple DC capacitors in series.
The DC / DC converter converts the DC voltage required by the PWM converter, and the PWM converter that controls the power according to the wind speed value converts DC power to AC power and outputs it to the AC power system. It is a device. According to this means, even if the number of revolutions of the synchronous generator is different and the internal induced voltage is different, since the plurality of DC capacitors are connected in series, the current flowing through the plurality of synchronous generators is the same. Therefore, even if there is a difference in the rotational speed of the wind turbine due to temporary turbulence of the wind, it is possible to extract electric power proportional to the rotational speed of each wind turbine. Act to be the same.
In addition, the maximum output matching the wind speed can always be output to the AC power supply system. Moreover, instead of the conventional expensive multiple generator inverters and system inverters, multiple inexpensive diode rectifier circuits, one DC / DC converter, and 1
The power can be taken out by one PWM conversion circuit, so it is extremely useful in practice.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main circuit configuration diagram in which a power converter circuit for parallel wind power generation that outputs power to an AC power supply system from a synchronous generator connected to two wind turbines of the present invention is connected.

FIG. 2 is a diagram illustrating an outline of wind turbine output with respect to rotational angular velocity with wind velocity as a parameter.

FIG. 3 is a block diagram showing a conventional main circuit connection diagram in which a power converter circuit for parallel wind power generation that outputs electric power to an AC power supply system is connected from a conventional synchronous generator connected to two wind turbines.

[Explanation of symbols]

1st windmill 2 second windmill 3 first synchronous generator 4 Second synchronous generator 5 First anemometer 6 second anemometer 7 First diode rectifier circuit 8 Second diode rectifier circuit 9 First DC capacitor 10 Second DC capacitor 11 DC / DC converter 12 PWM conversion circuit 13 AC power supply system 14 1st generator inverter 15 Second generator inverter 16 First system inverter 17 Second system inverter

Claims (2)

[Claims] 1. A power converter for extracting electric power from a plurality of synchronous generators connected to a plurality of wind turbines and outputting the electric power to an AC power supply system, each of which is connected to the AC side of the plurality of synchronous generators. A DC rectifier circuit and DC capacitors connected in parallel with the diode rectifier circuit and connected in series so that the output side of the diode rectifier circuit on one side and the output side of the diode rectifier circuit on the other side are added so that a DC voltage is added. And a DC / DC converter connected in parallel with the DC capacitor connected in series, and a PWM conversion circuit connected in parallel with the DC / DC converter. 2. In the PWM conversion circuit, a plurality of anemometers are provided near the plurality of wind turbines, an average wind speed value is measured by the anemometer, and power control is performed based on the wind speed value. Item 1. A power converter for parallel wind power generation according to Item 1.