JP2001268800A - Solar light power generation control method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize solar light power generation of small loss irrespective of the amount of power generation. SOLUTION: Corresponding to the amount of power generation of solar batteries 10a to 10d, the solar battery having the large amount of power generation is connected with an inverter in a one-to-one manner and operated, and a plurality of solar batteries having the small amount of power generation are combined, connected in parallel with inverters the number of which is smaller than the solar batteries on the DC side and operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plurality of power generators each comprising a combination of a solar cell and an inverter for converting DC power output from the solar cell into AC power, connected in parallel, and linked to a power system. The present invention relates to a photovoltaic power generation control method and device for controlling a photovoltaic power generation device.

[0002]

2. Description of the Related Art In photovoltaic power generation, FIG. 1 (the relationship between the output voltage and the output current of a solar cell) is shown in units of a combination of a solar cell and an inverter for converting DC power output from the solar cell into AC power. ) And FIG. 2 (similarly, the relationship between the output voltage and the output power), that is, a so-called maximum power tracking control that operates at a maximum power point that changes according to the amount of solar radiation to the solar cell is performed.

When a large-capacity photovoltaic power generator is operated, as shown in FIG. 3, a plurality of solar cell panels 10a... 10d and a plurality of inverters (INV) 12a. There is a system (so-called orthogonal common system) for connecting a solar cell panel and an inverter in parallel. In this case, each of the inverters 12a.
d equally distributes the load, and performs the maximum power tracking control by regarding all the solar cells 10a to 10d as one solar cell.
Then, when the amount of solar radiation decreases and each inverter has a low output, the conversion efficiency decreases as shown in FIG.
As shown in Japanese Patent No. 2967667, Japanese Patent Publication No. 5-11428, Japanese Patent Application Laid-Open No. Hei 6-165513, Japanese Patent Application Laid-Open No. 8-33211, etc., output from the number-of-operated-operations control device 14 is made in accordance with the power information of the entire solar cell panel. It has been proposed that the number of inverters to be operated be reduced by an operation stop command to reduce the number of inverters to be operated so that the inverter to be operated is operated in a region with high conversion efficiency.

Separately, as shown in FIG. 5, each solar cell panel 10a... 10d and inverters 12a.
There is also a large capacity system (so-called DC separation system) in which d is connected one-to-one and each is operated independently. In this case, the maximum power tracking control is performed for each combination.

[0005]

However, in the former method of performing the maximum power tracking control by treating the entire solar cell as one cell, the state of shadows of surrounding buildings and the like and the state of dirt on the surface of the solar cell panel are considered. When the power generation state of each solar cell is different due to the difference in the amount of solar radiation depending on the installation location of the solar cell, etc., the power generation Is reduced.

On the other hand, the latter method of connecting each solar cell and the inverter in a one-to-one manner has the advantage that power can be individually generated at an optimum point in a situation where the amount of power generation is large. There is a problem in that the operation is performed in a state where the conversion efficiency is poor, resulting in loss.

[0007] The present invention has been made to solve the above-mentioned conventional problems, and has as its object to enable solar power generation with small loss regardless of the amount of power generation.

[0008]

The present invention comprises a solar cell,
In a photovoltaic power generation control method for controlling a photovoltaic power generation device that is connected in parallel with a plurality of power generation devices in combination with an inverter that exchanges DC power output from the solar cell into AC power and is linked to a power system. Depending on the amount of power generated by each solar cell, a solar cell with a large amount of power generation is connected to an inverter one-to-one and operated, and a plurality of solar cells with a small amount of power generation are combined into a smaller number of inverters than the number of solar cells. This problem has been solved by connecting and operating in parallel on the DC side.

In a similar photovoltaic power generation control device,
Connection means capable of changing the connection state between the solar cell and the inverter, and a solar cell having a large amount of power generation is connected one-to-one with the inverter according to the amount of power generation of each solar cell, and a solar cell having a small amount of power generation is This problem is also solved by providing a plurality of combinations and connection control means for connecting in parallel on the DC side to a smaller number of inverters than the solar cells.

The present invention is based on the fact that the solar cells and the inverters are operated in a one-to-one combination. When the power generation amount of each solar cell is large and each inverter can be operated in a state of high conversion efficiency, one pair is used. In one combination, optimal maximum power follow-up control is performed, respectively.On the other hand, when the power generation amount of each solar cell decreases and each inverter enters a state of low conversion efficiency, the solar power generation amount decreases. By integrating the batteries, increasing the total power, and connecting them in parallel on the DC side to a smaller number of inverters than solar cells, the inverters were operated at high conversion efficiency,
Power can be supplied with a small conversion loss.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In the first embodiment of the present invention, as shown in FIGS. 6 to 8, a plurality of (four in this case) power generating devices combining solar cell panels 10a... 10d and inverters 12a. In a photovoltaic power generation device linked to an electric power system, a connection (for example, a contactor) 20 that can change the connection state of the output side of the solar cell panels 10a to 10d and an input to each of the inverters 12a to 12d are cut off. According to a connector (for example, a contactor) 22 for separating and power information (power generation amount) input from each solar cell,
And a connection control device 30 for switching between the connectors 20 and 22.

First, when the power generation amount of each solar cell panel is large, as shown in FIG.
10d and inverters 12a... 12d are connected one-to-one to operate.

On the other hand, when the power generation amount is small and the total power generation amount of the four solar cells is less than one inverter, FIG.
As shown in FIG. 1, all the solar cell panels 10a... 10d are connected to one inverter (in this case, the top inverter 12a).
Are connected in parallel, and the input to other inverters (here, inverters 12b... 12d) is cut off.
The connection controllers 20 and 22 are switched by the connection control device 30. In this case, since there is no input except for the inverter 12a at the uppermost stage, the operation is automatically stopped.

If the amount of power generation is moderate, for example, if the total amount of power generation of three solar cell panels is less than that of two inverters, as shown in FIG. , 22 are switched and the solar cell panels (here, 10b, 10c, 10d) are connected in parallel to one inverter (here, 12b). Since there is no input except for the inverter, the operation is automatically stopped. In addition, one solar cell panel (here, 10a) and an inverter (here, 12a) are connected one-to-one.

In the first embodiment, the connector 22 is provided to disconnect the input of the inverter to be stopped. However, FIG. 9 (for a large amount of power generation) and FIG. 10 (for a small amount of power generation) ), Instead of providing the connector 22 as in the second embodiment shown in FIG. 11 (during power generation), externally inputting an operation stop command from the connection / operation control device 32 to each of the inverters 12a to 12d. Thus, the operation of the inverter can be stopped.

According to the second embodiment, the connector 22 for disconnecting the inverter input can be omitted.

In each of the above-described embodiments, for simplification of the drawings, the number of solar cell panels and the number of inverters are each set to four, and parallel solar cell panels can be connected only between adjacent solar cell panels. However, the number of solar cell panels and the configuration in which parallel connection is possible are not limited to this, and it is also possible to arrange connectors on a network so that arbitrary panels can be connected in parallel. Further, the type of the connector is not limited to the contactor, and a semiconductor element or the like may be used.

FIG. 12 shows an example of a control procedure for performing control according to the embodiment of the present invention.

First, in step 100, the amount of power generated by each inverter is calculated.

Next, at step 102, it is determined whether or not any of the inverters connected to the plurality of solar cells has a power generation of 100%. If the result of the determination is positive, the process proceeds to step 104, where the connection is switched to return the solar cell and the inverter to a one-to-one combination.

Next, at step 106, the power generation amount of the inverter is calculated again.

After completion of step 106, or when the result of the determination in step 102 is negative, step 108
To find a combination that does not exceed 100% with inverters of similar power generation. For example, if 40% have three units, a combination of two units and one unit is used. Or 30% is 3
In the case of a unit, three units are put together.

Then, the process proceeds to step 110, where step 1
The connection is switched so that the combination determined in step 08 is reached, and the inverter from which the solar cell is removed is stopped.

In this way, the power generation of each inverter is calculated, and the inverter is operated at a point where the power generation of each inverter is as large as possible and the conversion efficiency is good. Note that, in this example, even once
If the solar radiation conditions change and the power generation exceeds 100%, the solar energy cannot be used effectively. Therefore, when the power reaches 100%, the system is returned to an individual state once and the individual power generation is checked again. . Further, in this example, solar cells having the same power generation amount are combined.
This is to avoid a case where the output of the solar cell having a good power generation state is deteriorated by arranging the solar cells having different power generation states in parallel. In the case of using a solar cell free from such a fear, a combination that maximizes the power generation amount of each inverter may be simply made.

[0026]

FIG. 13 shows a solar cell panel 10a,
10b is mounted on a wall surface and generates 40% of electric power, the corresponding inverters 12a and 12b are operated at a 40% output operation efficiency of 85%, and the solar cell panels 10c and 1b are operated.
When 0d is mounted on the roof and the amount of power generation is 70%, and the corresponding inverters 12c and 12d have a 70% output operation efficiency of 90%, as shown in FIG. By integrating the outputs of the inverters 10b and 10b and stopping the operation of the inverter 12b, the inverter 12a was able to increase the output operation efficiency to 80% and 93%.

In this way, by integrating the solar cell panels 10a and 10b attached to the wall into one inverter 12a, the inverter can be operated at a high efficiency point.
The loss was reduced.

[0028]

According to the present invention, a photovoltaic power generation with a small loss can be realized regardless of the magnitude of the power generation amount.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a change in the relationship between an output voltage and an output current depending on the amount of solar radiation of a solar cell;

FIG. 2 is a diagram showing an example of a change in the relationship between output voltage and output power.

FIG. 3 is a block diagram showing a configuration example of a photovoltaic power generator of a conventional orthogonal common system in which all photovoltaic panels and inverters are connected in parallel.

FIG. 4 is a diagram showing an example of power generation efficiency of an inverter.

FIG. 5 is a block diagram showing a configuration example of a photovoltaic power generator of a conventional DC separation system in which each solar cell and an inverter are connected one-to-one.

FIG. 6 is a block diagram showing a connection state when the amount of power generation is large in the first embodiment of the present invention.

FIG. 7 is a block diagram showing a connection state when the amount of power generation is small.

FIG. 8 is a block diagram showing an example of a connection state when the power generation amount is medium.

FIG. 9 is a block diagram showing a connection state when the amount of power generation is large in the second embodiment of the present invention.

FIG. 10 is a block diagram showing a connection state when the amount of power generation is small.

FIG. 11 is a block diagram showing an example of a connection state when the power generation amount is medium.

FIG. 12 is a flowchart illustrating an example of a control procedure according to the embodiment of the present invention.

FIG. 13 is a block diagram illustrating an example of a power generation amount of a solar cell panel and an operation efficiency of an inverter in a one-to-one operation according to an embodiment of the present invention.

FIG. 14 is a block diagram showing an example of the operation efficiency of the inverter when the outputs of the photovoltaic panels mounted on the wall surface are put together.

[Explanation of symbols]

 10a, 10b, 10c, 10d: Solar panel 12a, 12b, 12c, 12d: Inverter 20, 22: Connector 30: Connection control device 32: Connection / operation control device

Claims (2)

[Claims] 1. A plurality of power generators each comprising a combination of a solar cell and an inverter for converting DC power output from the solar cell into AC power are connected in parallel to control a solar power generator linked to a power system. In the solar power generation control method, the solar cells having a large amount of power generation are operated in one-to-one connection with the inverter according to the amount of power generation of each solar cell, and the solar cells having a small amount of power generation are combined in plurality. And a solar power generation control method comprising: connecting the inverter to a smaller number of inverters than the solar cells on the DC side in parallel. 2. A plurality of power generators each comprising a combination of a solar cell and an inverter for converting DC power output from the solar cell into AC power are connected in parallel to control a solar power generator linked to a power system. A connection means capable of changing a connection state between the solar cell and the inverter; and a solar cell having a large amount of power generation connected to the inverter one-to-one according to the amount of power generation of each solar cell. And a connection control means for connecting a plurality of solar cells having a small amount of power generation in parallel on the DC side to a smaller number of inverters than the solar cells.