JPH01107622A - System linkage power converter - Google Patents

Abstract

PURPOSE:To exactly judge the voltage variations by the opening of a power system and the instantaneous voltage variations such as thunder surge, etc., by providing a power conversion means to convert the power from a DC power source into AC power and supplies to the power system and a judgement means from the result in comparing the output current of this power conversion means with the current reference value. CONSTITUTION:In case a linkage breaker 14 is turned ON, the DC power of a DC power source 11 is supplied to a power conversion device 12, the output of which is supplied to a power system 15. The output current of the power conversion device 12 is detected by a current detector 16 and the current signal iS is given to a judgement section 131 of a control/protection circuit 13 where it is judged whether the current reference value i/the current signal iS=infinity . In case the power system 15 is sound, the judgement will be NO and the gate command for continuous operation is given to the power conversion device 12 from the control/protection circuit 13. If the power system is found abnormal, then the current signal iS from the current detector 16 becomes zero and when the judgement with the judgement section 131 becomes YES on whether the current reference value i/the current signal iS=infinity , the power conversion system 12 is stopped.

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) This invention provides a power conversion device for grid connection that converts DC power from a DC power supply into AC power and supplies the AC power to the power grid. Regarding.

(Prior Art) Conventionally, as this type of power converter for grid connection, there is one shown in FIG. 4. In the figure, 1 is a DC power supply, and the DC power of this DC power supply 1 is supplied to a power conversion device 2. This gravity conversion device 2 is composed of an inverter using Cyrisk, etc., and converts the DC power of the DC power source 1 into AC power in response to a gate command from the control/protection circuit 3.

The AC power of this power conversion device 2 is then supplied to the power grid 5 via the interconnection breaker 4 . Further, the output current of the power converter 2 is detected by a current detector 6 and given to the control/protection circuit 3 as a current signal is, and the output voltage of the power converter 2 is detected by a voltage detector 7, and the voltage signal is and is given to the control/protection circuit 3 as a signal. In this state, the control/protection circuit 3 compares the current signal is supplied by the current detector 6 with the current reference value i, gives a gate command to the power converter 2 to reduce the difference between them, and controls the power converter 2. The AC output of the converter 2 is made to follow the current reference value i11.

By the way, in this configuration, if the interconnection breaker 4 becomes open due to an accident in the power system 5, the output current of the power converter 2 becomes zero, and the current signal is also becomes zero. Therefore, the current reference value 1 in the control protection circuit 3
1 and the current signal is, and a signal is given as a gate command to increase the output current of the power converter 2. However, since the output side of the power converter 2 is open because the grid breaker 4 is in the cutoff state, no output current actually flows and the output voltage suddenly increases, which is extremely dangerous. This could lead to a dangerous situation.

Therefore, conventionally, as shown in FIG. 5, when the voltage signal VS of the voltage detector 7 increases due to the opening operation of the interconnection breaker 4 and exceeds a predetermined voltage regulation value vb, a system abnormality occurs. After determining this, a gate command to that effect is generated, and the operation of the power conversion device 2 is stopped.

However, with such a device, when an instantaneous fluctuation occurs in which the output side voltage of the power converter 2 suddenly increases as shown in FIG. 6 due to the influence of a lightning surge, for example, the fluctuating voltage at this time becomes When the regulation value vb is exceeded, it may be mistakenly determined that there is a system abnormality, and a gate command to that effect may be issued, causing the operation of the power converter 2 to stop unnecessarily.
The drawback was that the reliability of the device was significantly inferior.

(Problem to be solved by the invention) In this way, in the conventional power converter for grid connection, when the output side voltage of the power converter suddenly increases due to the influence of lightning surge, etc., the voltage at this time is There is a drawback that when the regulation value is exceeded, it is mistakenly judged as a system abnormality and the operation of the power converter is stopped. Therefore, the purpose of this invention is to prevent the power system from becoming open. It is an object of the present invention to provide a power converter for grid connection which can stop the operation of the device only when the system is in use, improves reliability, and has excellent safety.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a DC power supply, a power conversion means for converting the DC power of the DC power supply into AC power and supplying the same to an electric power system, and the power conversion means. and a control means for stopping the operation of the power conversion means based on the judgment result of the judgment means, The operation of the power conversion means is stopped only when the grid is open.

(Function) As a result, it is possible to accurately distinguish between voltage fluctuations due to an open power system and instantaneous voltage fluctuations due to lightning surges, etc., and it is possible to stop the operation of the device only when the power system becomes open. become able to.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the circuit configuration of the same embodiment. In the figure, 11 is a DC power supply, and the DC power of this DC power supply 11 is supplied to a power conversion device 12. This power conversion device 12 is composed of an inverter using Cyrisk, etc., and converts the DC power of the DC power source 11 into AC power in response to a gate command from the control/protection circuit 13. The AC power of this power conversion device 12 is then supplied to the power grid 15 via the interconnection breaker 14. In addition, the power converter 1
The output current of No. 2 is detected by the current detector 16 and is given to the control/protection circuit 13 as a current signal is.

Here, the control/protection circuit 13 includes a determination unit 131 that determines the relationship between the current signal is supplied by the current/current detector 6 and the current reference value III. This judge 131
As shown in FIG. 2, the current reference value 11' and the current signal is are given, and in this state, the current reference value ill/current signal 1S-oo (infinity) is determined. And, now that the power grid is healthy, the current detector 6
If the current signal Ls is being supplied, the determination is NO, and the control/protection circuit 13 allows a gate command that reduces the difference between the current signal Ls and the current reference value P for continuous operation, In addition, if the power system is in an open state and the current signal is from the current detector 6 becomes zero, YE
S is determined, and a gate block command to stop the operation of the power conversion device 12 by the control/protection circuit 13 is permitted.

Next, the operation of the embodiment configured as described above will be explained.

Now, if the power grid 15 is healthy and the interconnection breaker 14 is in the on state, when DC power from the DC power source 11 is supplied to the power converter 12, AC power is output from the power converter 12. and is supplied to the power grid 15 via the interconnection breaker 14. In this case, the output current of the power converter 12 is detected by the current detector 16, and the current signal is
is given to the determination unit 131 of the control/protection circuit 13.

Then, the determination unit 131 determines whether the relationship between the current reference value i11 and the current signal Ls is: current reference value ill/current signal i S w 00 (infinity). Here, the power system is healthy and the current signal is is being supplied, so - (infinity),
In other words, there is no divergent solution, and the answer is NO. As a result, the control/protection circuit 13 gives a gate command for continuous operation to the power converter 12, but in this case, the gate command from the control/protection circuit 13 is based on the current signal is and the current reference value i. The difference is made smaller, and the output power of the power conversion device 12 is operated to follow the current reference value l.

In this state, if an abnormality occurs in the power system and the interconnection breaker 14 is cut off, the output current of the power conversion device 12 will stop flowing, and the current signal is from the current detector 16 will become zero. Then, the determination unit 131 of the control/protection circuit 13
Then, since the current reference value i''/current signal i B m oo (infinity) is obtained as the judgment result, it is judged as YES.As a result, the control Φ protection circuit 13 sends the gate block command to the power conversion The power converter 12 is immediately stopped from operating.

In this case, the output voltage of the power converter 12 is changed as shown in FIG.
When it reaches zero, it tries to rise rapidly as shown in FIG. become.

Therefore, by focusing on the fact that the output current of the power conversion device becomes zero when the power system becomes open due to the disconnection operation of the interconnection breaker, the current reference value can be set using the output current of the power conversion device. Since the open state of the power system is determined when the result of division becomes infinity, that is, a divergent solution, the moment when the output side voltage of the power converter suddenly increases due to the effects of a lightning surge, for example, Even if fluctuations occur, they will not malfunction and will be able to respond accurately only to the open state of the power grid.
The reliability of the device can be significantly increased. Additionally, when it is determined that the power system is open, a gate block command is issued to the power converter to immediately stop the power converter's operation, thereby quickly suppressing the rise in the output voltage of the power converter. It also has excellent safety features, such as preventing danger to people due to high voltage generation.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be implemented with appropriate modifications without changing the gist.

For example, in the above embodiment, when the result of dividing the reference value i and the current signal Ls becomes infinite, the open state of the system is determined. , the open state of the grid may be determined when the predetermined set value is exceeded. In this way, the open state of the system can be quickly known, making high-speed protection possible. Further, reliability can be further improved by making the above-mentioned set value variable and by detecting a system open as an AND condition in combination with an instantaneous voltage rise.

[Effects of the Invention] According to the present invention, there is provided a DC power supply, a power conversion means for converting the DC power of the DC power supply into AC power and supplying it to the power system, and an output current and a current base value of the power conversion means. and a control means for stopping the operation of the power converting means based on the result of the determination by the determining means. The operation of the conversion means is stopped. This makes it possible to accurately distinguish between voltage fluctuations caused by an open power grid and instantaneous voltage fluctuations caused by lightning surges, etc., and allows the device to stop operating only when the power grid becomes open. It is possible to improve reliability and to obtain a product with excellent safety.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the circuit configuration of an embodiment of the present invention, Fig. 2 is a diagram for explaining the determination section of the control/protection circuit used in the embodiment, and Fig. 3 is the embodiment. FIG. 4 is a circuit configuration diagram showing an example of a conventional power converter for grid connection, and FIGS. 5 and 6 are diagrams for explaining the same device. 11... DC power supply, 12... Power converter, 13.
...Control/protection circuit, 131... Judgment section, 14...
Grid connection breaker, 15...Power system. Applicant's representative Patent attorney Takehiko Suzue Figure 1 (continued operation) (stopped) Figure 2 Interconnector disconnector Figure 3

Claims (3)

[Claims] (1) A DC power supply, a power conversion means that converts the DC power of this DC power supply into AC power and supplies it to the power system, and the result of comparing the output current of this power conversion means with the current reference value. A determination means for determining an open state;
A power conversion device for grid connection, comprising: a control device that stops the operation of the power conversion device based on the determination result of the determination device. (2) The determination means determines the open state of the power system when the result of dividing the current reference value by the output current of the power conversion means is a divergent solution. The power conversion device for grid connection described in Section 1. (3) The determination means determines the open state of the power system when the result of dividing the current reference value by the output current of the power conversion means exceeds a predetermined value. The power converter for grid connection according to item 1.