JP2008187783A - Method of connecting system-interconnected inverter to wind power generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of a conventional generator such as that though a long fixed time for confirming the normal state of a generator safely is required, after the capacitor voltage of the system-interconnected inverter goes higher, so as to switch on the system-interconnected switch of the system-interconnected inverter, if wind velocity goes up suddenly since it does not get in a system-interconnected state meanwhile, the capacitor voltage goes up suddenly by the charge from the generator and the system-interconnected inverter breaks. <P>SOLUTION: This connection method to a wind power generator is as follows. In the system-interconnected inverter which is to be connected to the wind power generator that rectifies and outputs a current, a first switch is connected in parallel with the AC output of the system-interconnected inverter, and a second switch, a first insulating transformer, and a first rectifier are connected in series to the first switch, and the second insulating transformer, in parallel with the first switch, and the second rectifier, in series, are connected, and then the output of the first and second rectifiers is made the DC input of the system-interconnected inverter. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a connection method between a grid-connected inverter linked to a grid and a wind power generation apparatus that outputs a rectified output, and in particular, can be easily grid-connected to a fluctuating wind speed without using a battery. The present invention relates to a method for connecting wind power generators of a grid-connected inverter.

  Since the grid interconnection inverter needs to have a grid protection function and an independent operation confirmation function, the grid output was started after the grid switch was turned on after the normal state of the grid was completely confirmed.

FIG. 3 is a diagram for explaining a conventional method for connecting wind power generators of a grid-connected inverter.
In FIG. 3, 11 is a windmill, 12 is a wind power generator, 13 is a permanent magnet generator, 14 is a generator rectifier, 15 is a windmill brake, 1 is a grid-connected inverter, 2 is a capacitor, 3 is a grid switch, 4 is a system.
The wind power generator 12 includes a permanent magnet generator 13, a power generator rectifier 14, and a windmill brake 15.
The grid interconnection inverter 1 includes a capacitor 2 and a linkage switch 3.
The permanent magnet generator 13 is driven by the windmill 11, the AC output is converted into the DC output, and the capacitor 2 is charged. When the voltage of the capacitor 2 rises and the grid connection inverter 1 can be output to the grid 4, after confirming the normal state of the grid completely, the grid switch 3 is turned on and output to the grid 4.
System configuration diagram of Nikko Corporation's Environmental Energy Connection Department (383, Kashiwamachi, Hakusan City, Ishikawa Prefecture, TEL 076-274-6868) catalog "Nikko Wind Power Generation System NWG-4K"

In the wind power generation apparatus connecting method of the grid-connected inverter configured as described above, in order to turn on the grid switch 3, in order to completely check the normal state of the grid after the voltage of the capacitor 2 rises. A certain amount of time was required.
This fixed time is usually as long as 60 seconds or more. Therefore, if the output is not completely connected to the grid during this fixed time, the voltage of the capacitor 2 rapidly increases due to the charging from the wind power generator when the wind speed rapidly increases, and the grid-connected inverter 1 There was a problem of destruction.
Further, if a storage battery is used instead of the capacitor 2, a rapid increase in voltage can be suppressed, but there is a problem that it is expensive and requires maintenance and replacement.

  Therefore, in order to solve the above-described problem, in the wind power generation apparatus connecting method of the grid interconnection inverter of the present invention, after starting the wind turbine system, first, the DC input of the grid interconnection inverter 1 is charged using an insulating transformer. The wind turbine brake 15 is turned off after the grid switch 3 is forced to turn on by circulating the system energy.

In the method for connecting a wind turbine generator for a grid-connected inverter according to the present invention, after the wind turbine system is activated, the wind speed rapidly increases after the wind turbine brake 15 is turned off in order to forcibly turn on the interconnection switch 3 in advance. Thus, even if the power generation of the wind power generator suddenly increases, the voltage of the capacitor 2 does not increase rapidly. Therefore, the grid interconnection inverter 1 is not destroyed.
This wind power generation apparatus connecting method for grid-connected inverters can be configured by combining transformers and switches with small capacities and grid-connected inverters, and is thus extremely useful in practice.

  In the grid-connected inverter wind power generator connecting method of the present invention, in the grid-connected inverter connected to the wind power generator for rectifying output, the first switch is connected in parallel to the AC output of the grid-connected inverter, A second switch connected in series to the first switch, a first isolation transformer connected in series to the second switch, a first rectifier connected in series to the first isolation transformer; A second insulating transformer is connected in parallel to the first switch, a second rectifier is connected in series to the second insulating transformer, and the outputs of the first rectifier and the second rectifier are connected to the system. It is characterized by using a DC input of the interconnection inverter.

FIG. 1 shows an embodiment of the present invention, in which a switch, a transformer, and a rectifier are added to the grid interconnection inverter 1 shown in FIG.
In the figure, 5 is a first switch, 6 is a second switch, 10 is a first isolation transformer, 8 is a first rectifier, 9 is a second isolation transformer, and 7 is a second rectifier.

FIG. 2 is a diagram for explaining a sequence of the grid interconnection inverter and the wind turbine generator connection method.
Hereinafter, FIG. 1 will be described with reference to FIG.

The first switch 5 is connected in parallel to the AC output of the grid interconnection inverter 1. A second switch 6 is connected in series to the first switch 5, and a first rectifier 8 is connected via a first insulating transformer 10 connected in series. A second insulation transformer 9 is connected in parallel to the second switch 6, and a second rectifier 7 is connected in series.
The direct current sides of the first rectifier 8 and the second rectifier 7 are each connected to the direct current input of the grid interconnection inverter 1.

The first switch 5 is turned ON / OFF in synchronization with the start signal of the wind turbine system. The second switch 6 is turned on in synchronization with the first switch 5, passes through the second switch 6, the first insulation transformer 10, and the first rectifier 8, and then enters the capacitor 2 of the grid interconnection inverter 1. Charge.
Since the turn ratio of each insulation transformer is designed so that the non-system side voltage of the first insulation transformer 10 is higher than the anti-system side voltage of the second insulation transformer 9, the second switch 6 is turned on. During this period, no charging current flows through the second insulating transformer 9 and the second rectifier 7.

When the voltage of the capacitor 2 of the grid connection inverter 1 is charged and becomes a DC voltage that can be output to the grid 4, the grid connection inverter 1 completes the normal state of the system over the above-mentioned fixed time over 60 seconds. After confirming the above, the interconnection switch 3 is turned on at time T2 in FIG.
At this time, the power output from the grid interconnection inverter 1 to the grid 4 is the power circulating through the first insulating transformer 10.

When the interconnection switch 3 is turned on at time T2 in FIG. 2 and the output to the system 4 is confirmed, the second switch 6 is turned off at time T3 in FIG. When the second switch 6 is turned off, a charging circuit for the capacitor 2 of the grid-connected inverter 1 is formed through the second insulating transformer 9 and the second rectifier 7.
The time between the time T2 and the time T3 in FIG. 2 may be a time during which the grid-connected inverter 1 can surely confirm the output to the system 4, and does not need to be longer than necessary.
The anti-system side voltage of the second isolation transformer 9 is not a voltage that the grid interconnection inverter 1 can output to the grid 4, but the grid switch 3 of the grid interconnection inverter 1 is set to a voltage that can be turned on. .

At the same time as the second switch 6 is turned off, the windmill brake 15 is also turned off as shown at time T3 in FIG. 2 to accelerate the windmill 11 and output the wind power generation output to the grid 4.
Even if the windmill brake 15 is turned off and the windmill 11 starts to rotate, if there is not enough wind speed to be output to the system 4, the second insulating transformer 9 supplies a minute electric power that can keep the interconnection switch 3 ON. .
When the start signal of the windmill system is turned off, the first switch 5 is turned off and the windmill brake 15 is turned on as shown at time T4 in FIG.

As described above, in the embodiment of the present invention, after the wind turbine system is started, the interconnection switch 3 is forcibly turned on in advance. Therefore, even if the wind speed suddenly rises after the wind turbine brake 15 is turned off, the voltage of the capacitor 2 is maintained. It wo n’t soar. Therefore, the grid interconnection inverter 1 is not destroyed.
This wind power generation apparatus connecting method for grid-connected inverters is very useful in practice because it can be configured by combining transformers and switches with small capacity and grid-connected inverters without using a battery that requires maintenance and replacement.

It is a figure for demonstrating the wind power generator connection method of the grid connection inverter of this invention. It is a figure for demonstrating the sequence operation | movement of the wind power generator connection method of a grid connection inverter of this invention. It is a figure for demonstrating the wind power generator connecting method of the conventional grid connection inverter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 System connection inverter 2 Capacitor 3 Connection switch 4 System 5 1st switch 6 2nd switch 7 2nd rectifier 8 1st rectifier 9 2nd insulation transformer 10 1st insulation transformer 11 Windmill 12 Wind power generation Device 13 Permanent magnet generator 14 Power generator rectifier 15 Windmill brake

Claims (2)

In the grid-connected inverter connected to the wind power generator for rectified output, a first switch is connected in parallel to the AC output of the grid-connected inverter, and a second switch is connected in series to the first switch. The first isolation transformer is connected in series to the second switch, the first rectifier is connected in series to the first isolation transformer, and the second isolation transformer is connected in parallel to the first switch And a second rectifier connected in series to the second isolation transformer, and the outputs of the first rectifier and the second rectifier are used as DC inputs of the grid interconnection inverter. To connect a wind turbine generator of a power system inverter. The wind power generation apparatus connecting method for a grid-connected inverter, wherein the anti-system side voltage of the first insulating transformer according to claim 1 is set higher than the anti-system side voltage of the second insulating transformer.

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