JP2003116224A - Photovoltaic generation system, power converter thereof, and control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an output voltage to a load from being affected by the voltage of a system power source. SOLUTION: This power converter 30 has different connection paths between the three of a solar battery array 1, a system power source 4 and the load 6. The power converter 30 is operated to convert DC power outputted by the solar battery array 1 into AC power, outputs it to the load 6, and links extra AC power to the system power source 4 in a manner of a tidal reverse current when the power consumption of the load 6 is lower than power supplied from the solar battery array 1, and converts the DC power outputted by the solar battery array 1 into AC voltage, output it to the load compensating for the insufficient AC power with the system power source 4 when the power consumption of the load 6 exceeds the power supplied from the solar battery array 1. The connection path 32 to the load 6 and the connection path 33 to the system power source 4 in the power converter 30 are not electrically connected directly to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photovoltaic power generation system, a power conversion device therefor, and a control method for the system, and more particularly to a photovoltaic power generation system in which an output voltage to a load is not affected by a voltage of a system power supply. The present invention relates to a system, a power converter thereof, and a control method of the system.

[0002]

2. Description of the Related Art In recent years, problems such as global warming due to the emission of carbon dioxide accompanying the use of fossil fuels, accidents at nuclear power plants and radioactive contamination due to radioactive waste have become serious.
There is growing interest in the global environment and energy. Under such circumstances, photovoltaic power generation that uses sunlight, geothermal power generation that uses geothermal power, wind power generation that uses wind power, etc. have been put into practical use as inexhaustible and clean energy sources.

Among these, there are various forms of solar power generation using a solar cell depending on the output scale from several W to several thousand kW. As a typical system using a solar cell, there is a solar power generation system in which DC power generated by the solar cell is converted into AC power (orthogonal conversion) by an inverter or the like and supplied to a commercial power system.

Further, using a direct current power source such as a solar cell,
An uninterruptible power supply system that supplies power to a necessary load even when power supply from a system power supply is stopped has been put into practical use in various forms.

Some conventional solar power generation systems and uninterruptible power supply systems will be described below with reference to the drawings.

[Conventional Example 1] FIG. 2 is a block diagram showing a general configuration of a conventional photovoltaic power generation system capable of supplying electric power to a system power supply. In the figure, 1 is a solar cell array, 2 is a solar cell array junction box, 3 is a grid-connected reverse flow power converter, 4 is a grid power supply, 5 is a switchboard for connecting to a load, and 6 is a load. .

For the purpose of improving efficiency during power transmission and the like, the solar cell array 1 is configured such that a plurality of solar cell modules are connected in series to generate high-voltage DC power and a plurality of solar cell modules are connected in parallel. It has a unique structure.

When there are a plurality of solar cell arrays 1, the junction box 2 is integrated and connected to the grid interconnection reverse flow power converter 3.

The grid-connected reverse flow power converter 3 converts the DC power obtained from the solar cell array 1 into AC power, and outputs the AC power to a power line to which the grid power supply 4 is connected.

The system power supply 4 is supplied from the power company 1
00V (101 ± 6V) or 200V (202 ± 2)
It is a commercial AC power supply of 0V. The switchboard 5 is a box for branching into a building or the like for power distribution. The load 6 is a terminal device used in a building or the like.

The solar cell array 1 outputs electric power when it receives the solar radiation of the sun, and is supplied from the system power supply 4. When the solar cell array 1 outputs, the system interconnection reverse power flow converter. 3 is operated and the output of the solar cell array 1 is used. Then, when the output of the solar cell array 1 exceeds the total amount of electric power of the load 6, electric power is sent back to the system power supply 4 (reverse flow).

[Prior art example 2] FIG.
An example of an uninterruptible power supply system described in Japanese Patent No. 448, etc. that supplies power to a necessary load even when power supply from a grid power supply is stopped using a solar cell is shown in the same manner as FIG. It is a block diagram.

In the figure, 1 is a solar cell array, 2 is a solar cell array junction box, 3 is a grid-connected reverse flow power converter, 4 is a grid power supply, 5 is a switchboard for connecting to a load, and 6 is a Load, 7 uninterruptible power supply, 7a storage battery for uninterruptible power supply, 7b power converter for uninterruptible power supply, 8 emergency generator, 9 emergency load, 20 emergency system separation switch, Reference numeral 21 is an emergency connection switch.

For the purpose of improving efficiency during power transmission, the solar cell array 1 is configured so that a plurality of solar cell modules are connected in series to generate high-voltage DC power and a plurality of solar cell modules are connected in parallel. It has a unique structure.

When there are a plurality of solar cell arrays 1, the junction box 2 is integrated and connected to the grid interconnection reverse flow power converter 3.

The grid-connected reverse flow power converter 3 converts the DC power obtained from the solar cell array 1 into AC power, and outputs the AC power to a power line to which the grid power supply 4 is connected.

The system power supply 4 is supplied from the power company 1
It is a commercial AC power supply of 00V or 200V. The switchboard 5 is a box for branching into a building or the like for power distribution. The load 6 is a terminal device used in a building or the like.

In the uninterruptible power supply 7, in a normal state in which power is being supplied from the grid power 4, the emergency connection switch 21 is opened and disconnected from the output of the solar cell array 1, and the emergency grid separation switch 20 is connected. The storage battery 7a is charged by being connected to the system power supply 4 via the power supply. At this time, the power converter 7b may be operated as necessary to drive the emergency load 9.

Further, in the uninterruptible power supply device 7, the emergency system separation switch 20 is opened and the emergency connection switch 20 is opened at the time of so-called power failure when the power is not supplied from the system power 4.
Is closed, the storage battery 7a is charged by the electric power output from the solar cell array 1, or the power converter 7b is operated to drive the emergency load 9. The emergency power generator 8 backs up the uninterruptible power supply 7 as needed to improve the reliability of the power supply. Emergency load 9
Is a terminal load that the device user preferentially uses when the power supply from the system power supply 4 is stopped.

The emergency system separation switch 20 connects the uninterruptible power supply 7 or the emergency generator 8 depending on the situation,
It is a switch for disconnecting. Emergency connection switch 2
1 is a switch that closes to supply the output of the solar cell array 1 to the uninterruptible power supply 7 when the power supply from the system power supply 4 is stopped and to charge the storage battery 7a or back up the operation of the power conversion device 7b. is there.

The solar cell array 1 outputs electric power when it receives sunlight from the sun, and is supplied with electric power from the system power supply 4. When the solar cell array 1 outputs the electric power, the grid-connected reverse flow power conversion is performed. The device 3 is operated and the solar cell array 1 is operated.
The output of is used. Then, when the output of the solar cell array 1 exceeds the total amount of electric power of the load 6, electric power is sent back to the system power supply 4 (reverse flow).

Here, when the power supply from the system power supply 4 is stopped for some reason, the emergency system separation switch 20 is opened to disconnect the electrical connection between the system power supply 4 and the uninterruptible power supply 7. The uninterruptible power supply 7 starts the self-sustained operation by the electric power supplied from the storage battery 7a or the electric power supplied from the emergency generator 8, and supplies the power to the emergency load 9.

[Prior art example 3] FIG. 4 shows a patent No. 029473.
An example of the uninterruptible power supply system described in Japanese Patent Laid-Open No. 72, which supplies power to a required load even when power supply from a system power supply is stopped by using a DC power supply, is shown in the same manner as in FIG. It is a figure.

In the figure, 3a is a system interconnection power converter having a storage battery charging function, 4 is a system power supply, 5 is a switchboard for connecting to a load, 6 is a load, 10a and 10b are transformers, 11 is an important load. , 12 is an emergency load, 22 is a storage battery as a DC power source, 23 is an emergency load connection switch, and 24 is an AC switch that functions as a system disconnection switch.

The grid-connected power conversion device 3a having a storage battery charging function converts the DC power obtained from the storage battery 22 as a DC power supply from DC to AC and connects it to the electric path to which the grid power supply 4 is connected. In addition to outputting, when the charge capacity of the storage battery 22 decreases or the power consumption of the load decreases, the storage battery 22 is charged with the system power.

The system power source 4 is supplied from the power company 1
It is a commercial AC power supply of 00V or 200V. The switchboard 5 is a box for branching into a building or the like for power distribution. The load 6 is a terminal device used in a building or the like.

The transformers 10a, 10b act as active filters when the grid interconnection power converter 3a having a storage battery charging function receives power from the grid power supply 4, and controls reactive power.

The important load 11 is a terminal device or the like that must be backed up in a building or the like. Emergency load 1
2 is a minimum load that needs to be used when the power supply from the system power supply 4 is stopped for some reason.

The grid-connected power conversion device 3a having a storage battery charging function is usually a transformer arranged on each line when the power supplied from the grid power supply 4 is sufficient compared to the power consumption of the load 6. A harmonic current is detected by a current transformer (not shown) to remove the harmonic component of the current supplied from the system power source 4, and the power factor is brought close to 1 to charge the storage battery 22 at the same time.

On the contrary, when the power consumption of the load 6 increases and the power supplied from the system power source 4 exceeds a predetermined value, the system interconnection power conversion device 3a having the storage battery charging function supplies the direct current from the storage battery 22. Receives power and performs reverse conversion operation,
It is connected to the system power supply 4 to supply power to the load 6.

When the power supply from the system power supply 4 is stopped for some reason, the AC switch 24 is immediately opened and the power of the storage battery 22 operates the system interconnection power converter 3a, which is important. It supplies power to the load 11 or the emergency load 12 and operates as an uninterruptible power supply.

[Prior art example 4] FIG.
No. 93, No. 5-328611, No. 5
Another example of a solar power generation system that performs bidirectional power conversion with a system power source, as described in Japanese Patent No. 328748-
It is the block diagram shown similarly to FIG.

In the figure, 1 is a solar cell array, 2 is a solar cell array connection box, 4 is a system power supply, 5 is a switchboard for connecting to a load, 6 is a load, and 13 is electric power that works as a DC / DC converter. A conversion circuit, 13a is a DC / AC conversion circuit which is a DC input portion of the power conversion circuit 13, and 13b.
Is an AC / DC conversion circuit of the power converter 13, and 14 is a DC-
A bidirectional power conversion circuit between alternating currents, a power conversion circuit 15 for converting direct current to alternating current, a motor load 16 and a smoothing capacitor 17.

For the purpose of improving efficiency during power transmission, the solar cell array 1 is configured so that a plurality of solar cell modules are connected in series to generate high-voltage DC power and a plurality of solar cell modules are connected in parallel. It has a unique structure.

The connection box 2 is integrated and connected to the power conversion circuit 13 when the solar cell array 1 is plural.

The system power source 4 is supplied from the power company 1
It is a commercial AC power supply of 00V or 200V. The switchboard 5 is a box for branching into a building or the like for power distribution. The load 6 is a terminal device used in a building or the like.

The power conversion circuit 13 stores a DC power obtained from the solar cell array 1 in a smoothing capacitor at an input stage and a DC / AC conversion circuit 13a for converting DC power to AC power by a switching element, and a transformer. The AC / DC converter circuit 13b receives AC power that has been transformed into a predetermined AC voltage and converts it to DC power by a rectifying element, and functions as a so-called DC / DC converter as a whole.

DC-AC bidirectional power conversion circuit 14
Is a bidirectional power conversion circuit capable of converting AC power from the system power supply 4 into DC power and outputting DC power from the power conversion circuit 13 as AC power to the system power supply 4.

The power conversion circuit 15 is a power conversion circuit that outputs AC power from DC power to drive an AC load. The motor load 16 is a load such as an AC motor of an inverter air conditioner. The smoothing capacitor 17 smoothes the DC line.

The solar cell array 1 outputs electric power when it receives the solar radiation of the sun, and DC electric power is output by the electric power converting circuit 13 composed of the DC / AC converting circuit 13a and the AC / DC converting circuit 13b. When the electric power load 16 consumes electric power and the resulting inflow power to the power conversion circuit 15 exceeds the output of the power conversion circuit 13, the bidirectional power conversion circuit 14 converts the AC power from the grid power supply 4 into DC power. Then, the shortage of the power supplied to the power conversion circuit 15 is compensated.

On the contrary, when the electric power consumption of the motor load 16 is zero or small and the electric power flowing into the electric power conversion circuit 15 due to the electric power consumption is less than the output of the electric power conversion circuit 13,
The bidirectional power conversion circuit 14 converts the DC power from the power conversion circuit 13 into AC power, and is connected to the system power supply 4 to reversely flow the excess power to the power conversion circuit 15 to the system power supply 4.

[0042]

Prior art example 1 shown in FIG.
In the solar power generation system capable of supplying power to the grid power source, the AC output of the grid-connected reverse power flow device 3, that is, the potential at the AC connection point to the grid power 4 is
If the loss due to the wiring resistance is ignored, the potential is almost the same as that of the load 6. Therefore, the AC interconnection voltage output from the grid interconnection reverse flow device 3 or the terminal voltage of the load 6 is determined depending on the voltage supplied from the grid power supply 4.

Here, the AC voltage of the system power supply 4 is, for example, a general 100V with respect to the electric power supplier supplying the electric power.
Since a standard with a value having a width of 101 ± 6V for a system and a range of 202 ± 20V for a 200V system with a doubled voltage is defined, 107V, 200V for a 100V system.
The system may receive an AC voltage with a maximum voltage of 222V.

The situation where the AC voltage of the system power source 4 is close to such a maximum voltage occurs when the voltage on the sending side is increased in consideration of the loss of the transmission line, and it occurs in a power plant or substation of a power company. It is likely to occur in an area near the sending out, and more likely to occur when the load power is large in an area where the load power varies greatly depending on the day of the week or time. By receiving power at such a maximum voltage, the following three problems occur.

The first problem is that, when the AC voltage of the grid power supply 4 is high, the greater the DC power input from the solar cell array when the grid connection reverse power flow device 3 performs the grid connection operation, the greater the DC power input. The AC voltage output from the system power supply 4 also rises. At this time, if the AC voltage of the system power supply 4 is a value close to the maximum voltage, the output voltage from the system interconnection reverse flow device 3 will reach the above-mentioned maximum voltage in a state where the interconnection operation is not performed.

However, in all general grid-connected reverse power flow converters, it is customary to control the output voltage so as not to exceed the maximum voltage, and as a result, reverse power flow, that is, power sale is possible. Even if a large amount of electric power is obtained from the solar cell array, the reverse power flow will be reduced or stopped.

As a second problem, when the AC voltage of the system power source 4 rises as described above, the terminal voltage of the load 6 also rises. Therefore, for example, if a resistive load is connected, The power consumption will increase automatically.

In the case of a resistive load such as a heating wire, the amount of heat generated increases with an increase in power consumption, and it is expected that the function will be improved. Particularly, if the load is a resistive load such as a lighting device, The brightness is slightly increased, the power consumption is increased rather than the function is improved, and when the maximum voltage is reached, about 10% of the power is wasted with respect to the standard value. Moreover, use in such situations generally shortens the life of the product.

The problem of voltage fluctuation of the system power supply has not been a problem so far, but in recent years,
It is increasing with the spread of power generation facilities such as solar power generation and wind power generation other than electric power companies and home solar power generation systems.

Further, as a third problem, in a general system interconnection reverse power flow device, since the interconnection points of the system power supply and the load are the same and the potentials are substantially the same, for example, If the AC power supply from the grid power supply stops for some reason, it is usually detected that the AC power supply has stopped, and the emergency load terminal provided on a different route in the grid-connected reverse power flow device is provided. Except for the output, it is necessary to stop the operation of the grid-connected reverse power flow device. For this reason, although the electric power can be obtained from the power generation source such as the solar power generation, the normally used load cannot be used at all.

For example, also in the conventional example 2 shown in FIG. 3, when the power supply from the system power supply 4 is stopped, the emergency load 9 can be used, but to the load 6 to which power is supplied only from the system power supply 4. Is not supplied.

Also in the conventional example 3 shown in FIG. 4, the loads backed up by the uninterruptible power supply are the important load 11 and the emergency load 12, and the important load 11 can always supply power. When the power supply from the system power supply 4 is stopped, similarly to the conventional example 2 shown in FIG. 3, the power is not supplied to the load 6 to which the power is supplied only from the system power supply.

In Conventional Example 4 shown in FIG. 5, when the power generated by the solar cell is obtained, the power is supplied to the motor load 16 or is linked to the system power supply 4 and flows backward.
However, the point where the normal load 6 is connected as shown in FIG. 5 is on the side of the system power supply 4 of the bidirectional power conversion circuit 14, so when the power supply from the system power supply 4 is stopped, the motor load 16 However, the normal load 6 cannot be supplied with electric power.

Further, in any of the conventional examples 2 to 4,
The load 6 is substantially directly connected to the system power supply 4, and the load 6
The terminal voltage of is almost equal to the voltage of the system power supply 4. Therefore, the above-mentioned first and second problems also occur.

The present invention has been made in view of the above situation, and a photovoltaic power generation system and its power converter, and an output power converter for the system, in which the output voltage to the load is not affected by the voltage of the system power supply. The purpose is to provide a control method.

[0056]

In order to achieve the above object, a solar power generation system of the present invention comprises a solar cell array,
When the system power supply, the load, and the solar cell array, the system power supply, and the load are connected by different connection paths, and the power consumption of the load is less than the power supplied from the solar cell array. In addition, while converting the DC power output from the solar cell array to AC power and outputting the AC power to the load, the surplus AC power is connected to the grid power source for reverse flow, and the power consumption of the load is When the power supplied from the solar cell array is exceeded,
The DC power output from the solar cell array is converted to AC power and output to the load, and a power converter configured to supplement the insufficient AC power from the system power supply, The connection path to the load in the power conversion device is not electrically directly connected to the connection path to the system power supply.

The above object can also be achieved by the power conversion device of the solar power generation system and the control method of the solar power generation system according to the present invention.

That is, according to the present invention, in a solar power generation system including a solar cell array, a system power supply, a load, and a power conversion device, the power conversion device includes a solar cell array, a system power supply, and a load. A different connection path is provided between each of them, and the power converter is used to convert the DC power output from the solar cell array into AC power when the power consumption of the load is less than the power supplied from the solar cell array. And output to the load, and the surplus AC power is connected to the system power supply for reverse flow, and when the power consumption of the load exceeds the power supplied from the PV array, the DC output from the PV array is output. The power is converted to AC power and output to the load, and at the same time, the system operates so as to supplement the lacking AC power from the system power supply, and the connection path to the load and the system power Electrically so as not to directly connect the connection route to.

By doing so, it is possible to output an arbitrary AC voltage to the load regardless of the AC voltage of the system power supply, and even if the AC voltage of the system power supply rises,
It is possible to prevent the AC voltage output to the load from increasing when reverse power flow is performed, and prevent the life of the device used as the load from decreasing.

In addition, the islanding prevention function, which is required when performing reverse power flow in a general system interconnection and which stops the operation of the power conversion device when the power supply from the system power supply is stopped, is not necessary, and is positive. Independent operation becomes possible.

[0061]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[Embodiment 1] FIG. 1 is a block diagram showing a configuration of a photovoltaic power generation system as a first embodiment of the present invention. In the figure, 1 is a solar cell array, 2 is a solar cell array junction box, 30 is a power converter, 4 is a system power supply, 5 is a switchboard for connecting to a load, and 6 is a load.

For the purpose of improving efficiency during power transmission and the like, the solar cell array 1 is configured such that a plurality of solar cell modules are connected in series to generate high-voltage DC power and a plurality of solar cell modules are connected in parallel. It has a unique structure.

The connection box 2 is integrated and connected to the power conversion device 30 when the solar cell array 1 is plural.

The power converter 30 converts the DC power obtained from the solar cell array 1 into AC power and supplies the AC power to the load 6 via the switchboard 5. In addition, when the output of the solar cell array 1 exceeds the total amount of electric power of the load 6, electric power is sent back to the system power supply 4 (reverse flow).

The system power supply 4 is supplied from the power company 1
00V (101 ± 6V) or 200V (202 ± 2)
It is a commercial AC power supply of 0V. The switchboard 5 is a box for branching into a building or the like for power distribution. The load 6 is a terminal device used in a building or the like.

The power conversion device 30 is a characteristic part of this embodiment, and its configuration will be described below.

As shown in the figure, the power conversion device 30 of this embodiment has a first connection path 31 and a second connection path 31 as connection paths.
Has a connection path 32 and a third connection path 33.

The first connection path 31 includes a solar cell, usually a solar cell array 1 in which solar cell panels are connected in series, or a solar cell arranged between a solar cell and a power conversion device as shown in the figure. This is a path for connecting the power converter 30 with the connection box 2 or the switch means in which the terminals are collected, and the DC power output from the solar cell array 1 is input to the power converter 30 via the connection path 31. It

The second connection path 32 connects the normal load 6 or the power distribution device 30 and the switchboard 5 or switch means arranged between the load 6 and the power conversion device 30 as shown in the figure. The AC power output from the power conversion device 30 is a path through which the load 6 is connected through the connection path 32.
Is supplied to.

The third connection path 33 is a bidirectional path that connects the power conversion device 30 to the system power supply 4, or switch means or the like located between the system power supply 4 and the power conversion device 30. The connection path 32 and the connection path 33 are not electrically directly connected.

The operation of this embodiment will be described. In the state where power is being supplied from the system power supply 4, when there is solar radiation from the sun, the DC power generated by the solar cell array 1 is connected to the power conversion device through the connection path 31. It is input to 30. When the power consumption of the load 6 exceeds the power generated by the solar cell array 1, in addition to the AC power converted from the DC power generated by the solar cell array 1 by the power conversion device 30, the power supply from the system power supply 4 via the connection path 33. The AC power supplied by way of the connection path 32 is supplied to the load 6 as AC power. On the other hand, when the power generated by the solar cell array 1 exceeds the power consumption of the load 6, the internal surplus power of the DC power generated by the solar cell array 1 is converted into AC power by the power conversion device 30 and is connected by the connection path 33. It is connected to the system power supply 4 and flows backward as AC power. When the power consumption of the load 6 and the output power of the solar cell array 1 are equal,
Neither power supply from the system power source 4 nor reverse power flow is performed.

Here, in the present embodiment, since the connection path 32 and the connection path 33 are not electrically connected directly, the terminal voltage in the connection path 32 is not influenced by the terminal voltage in the connection path 33. On the contrary, the terminal voltage on the connection path 33 is not affected by the terminal voltage on the connection path 32.

Therefore, for example, in the case of a 100V system, even if the AC voltage of the system power supply 4 is 105V, the AC voltage in the connection path 32 of the power supplied to the load 6 is 100V.
It is possible to output at a value lower than V, for example, 95 V, which is the minimum voltage of the standard of a 100 V commercial power source, and further,
If there is no problem in the operation of the load 6, the system power supply 4
It is also possible to set the voltage to be lower than the minimum voltage of 95 V of the standard.

Similarly, for a 200 V system, the system power source 4
200 such as 182V which is the minimum voltage of the AC voltage standard
Output at a value lower than V is also possible, and if there is no hindrance in the operation of the load 6, it is possible to set an AC voltage below the standard minimum voltage 182V, for example 180V.

Further, when the power supply from the system power supply 4 is stopped for some reason, when there is solar radiation from the solar cell array 1 and power is being output from the solar cell array 1, the system power supply 4
DC power generated from the solar cell array 1 is input to the power conversion device 30 via the connection path 31 and AC power is output via the connection path 32, as in the case where power is being supplied from the solar cell array 1. Is also possible. Of course, at this time, the value of the AC voltage in the connection path 32 is arbitrary.

Here, the operation of the power conversion device 30 in this embodiment will be described with reference to the flowchart of FIG.

First, it is determined whether or not power is being supplied from the system power supply 4 (step S101). If power is being supplied, it is determined whether or not the solar cell array is operating due to the output power from the solar cell array 1. Is determined (step S1
02). If the solar cell array 1 is not in operation, the power supplied from the system power supply 4 via the connection path 33 is output to the load 6 via the connection path 32 (step S10).
4).

When it is determined in step S102 that the solar cell array 1 is operating, it is determined whether the output power of the solar cell array 1 is less than the power consumption of the load 6 (step S104). If the output power of the solar cell array 1 is less than the power consumption of the load 6, in addition to the AC power converted from the output power of the solar cell array 1 input via the connection path 31, the system power supply via the connection path 33. The electric power supplied from 4 is output to the load 6 via the connection path 32 (step S105).

If it is determined in step 104 that the output power of the solar cell array 1 is equal to or more than the power consumption of the load 6,
The output of the solar cell array 1 input through the connection path 31 is converted into AC power and the load 6 is output through the connection path 32.
(Step S106), and it is determined whether or not the output power of the solar cell array 1 still has surplus power (step S107). If there is surplus power, solar array 1
The surplus power of the DC power generated by is converted into AC power, is connected to the system power supply 4 through the connection path 33, and flows backward as AC power (step S108).

On the other hand, if it is determined in step S101 that power is not being supplied from the system power supply 4, it is determined whether the solar cell array 1 is in operation (step S
109), if it is operating, the output power from the solar cell array 1 input via the connection path 31 is converted into AC power and output to the load 6 via the connection path 32 (step S110).

As described above, according to the present embodiment, in the solar power generation system, the connection point to the system power source and the connection point to the load, which are conventionally electrically connected directly, are connected to each other by the power conversion device. The output voltage to the load can be set arbitrarily because it is not electrically connected directly by interposing it, and the power consumption of the load can be adjusted while the power is being supplied from the system power supply. Therefore, it becomes possible to drive the load even when power is not supplied from the system power supply.

Further, since the relation between the voltage supplied to the load and the system voltage is cut off, it is possible to detect and prevent the islanding operation which is indispensable in the conventional photovoltaic power generation system in which the reverse power flow is performed in cooperation with the system power supply. Since it is no longer necessary and active self-sustaining operation is possible, it is easy to use the load for emergencies and the like when the power supply from the grid power is stopped due to a disaster or the like.

[Second Embodiment] The second embodiment according to the present invention will be described below. FIG. 6 is a block diagram showing the configuration of a photovoltaic power generation system according to the second embodiment of the present invention.

In the figure, 1 is a solar cell array, and 30
Is a grid-connected reverse flow power converter, 4 is a power supply, 6 is a load, and 13 is a DC / DC that works as a DC / DC converter.
A conversion circuit, 14 is a bidirectional power conversion circuit for converting between DC and AC, 15 is a DC / AC conversion circuit for converting DC power into AC power, 17 is a smoothing capacitor, 31 is the solar cell array 1 and DC. A first connection path connecting the DC / AC conversion circuit 13 and 32, the DC / AC conversion circuit 15 and the load 6
And 33 is a third connection path connecting the bidirectional power conversion circuit 14 and the system power supply 4.

The solar cell array 1 is constructed such that a plurality of solar cell modules are connected in series to generate high-voltage DC power and a plurality of solar cell modules are connected in parallel for the purpose of improving efficiency during power transmission. It is a simplified notation of what is shown, and the junction box is also omitted.

The grid-connected reverse flow power converter 30 converts the DC power obtained from the solar cell array 1 from DC to AC and converts the DC power into an electric path to which the grid power supply 4 is connected via the third connection path 33. While connecting and outputting as AC power,
AC power is supplied to the load 6 connected via the second connection path 32.

The system power supply 4 is supplied from the power company 1
00V (101 ± 6V) or 200V (202 ± 2)
It is a commercial AC power supply of 0V. The load 6 is a terminal device used in a building or the like, and the switchboard is omitted here for simplification.

The DC / DC conversion circuit 13 inputs the DC power supplied from the solar cell array 1 to operate the solar cell array 1 at an optimum operating point voltage, for example, and the grid-connected reverse power flow converter 30. Converts to DC power with the required intermediate voltage inside.

The bidirectional power conversion circuit 14 is connected to the system power supply 4 when the power output from the solar cell array 1 is larger than the power consumption of the load 6 while the power is supplied from the system power supply 4. In order to output AC power connected to the system power supply 4 via the connection path 33 of No. 3, power conversion from DC power to AC power is performed, and power is supplied from the system power supply 4 and consumption of the load 6 is performed. When the electric power output from the solar cell array 1 is smaller than the electric power, the load 6
In order to output AC power via the second connection path 32, power conversion from AC power to DC power is performed. When the power supply from the grid power supply 4 is stopped for some reason, the power conversion operation described above is stopped, and the third connection path 33, which is a connection path with the grid power supply 4, is connected.
Is disconnected from the electrical connection with the load 6, the solar cell array 1 and other power input / output terminals of the grid-connected reverse power flow converter 30.

The DC / AC conversion circuit 15 converts all the power consumed by the load 6 into the system power supply 4 or the solar cell array 1.
Alternatively, both are received and output via the second connection path 32. At this time, the DC / AC conversion circuit 15 outputs an arbitrary AC voltage that is optimum for the load 6 to be connected without being affected by the AC voltage of the system power supply 4.

When the power supply from the grid power supply 4 is stopped, the third connection path 33 of the grid power supply 4 is connected to the solar cell array 1 and the load 6 is connected to the second connection path 33. When the electric power output from the solar cell array 1 is obtained by disconnecting the electrical connection with the path 32, the electric power converted by the DC / AC conversion circuit 15 is continued to the load 6 via the connection path 32. It can also be supplied.

The smoothing capacitor 17 is a circuit for generating an intermediate DC power required inside the system interconnection reverse flow power converter 30, and is a capacitor normally used for stabilizing the voltage.

The present embodiment has the configuration described above, and is characterized in that the grid-connected reverse power flow converter 30 has a DC / DC converter.
The third connection path 33, which is a connection path with the system power supply 4, is composed of the DC conversion circuit 13, the bidirectional power conversion circuit 14, the DC / AC conversion circuit 15, and the smoothing capacitor 17.
However, since the bidirectional power conversion circuit 14 and the DC / AC conversion circuit 15 are arranged between the second connection path 32 which is a connection path with the load 6 and the connection path 32 with the load 6, That is, they are not directly connected electrically.

In such a configuration, when DC power is output from the solar cell array 1 while power is being supplied from the system power supply 4 and the DC power exceeds the power consumption of the load 6, both The direct-current power conversion circuit 14 performs reverse power flow conversion from direct-current power connected to the system power supply 4 to alternating-current power, and direct-current power is output from the solar cell array 1 while power is supplied from the system power supply 4. When the direct current power is lower than the power consumption of the load 6, the bidirectional power conversion circuit 14 obtains insufficient power from the direct current power from the solar cell array 1 from the system power source 4 to convert the alternating current power to the direct current power. Convert.

At this time, the DC / AC conversion circuit 15 converts the DC power obtained from the DC / DC conversion circuit 13 or the bidirectional power conversion circuit 14 into AC power in order to supply AC power to the load 6. However, the AC voltage output to the second connection path 32 to the load 6 does not depend on the AC voltage of the system power supply 4. For example, if the system power supply 4 is a 100V system, 101 ± 6V may be output, and if it is a 200V system, a value according to the standard such as 202 ± 10V may be output, and the AC voltage of the load 6 may be output to the AC voltage of the system power supply 4. Since it does not affect the above, the value may exceed the standard range.

When power supply from the system power supply 4 is stopped, the bidirectional power conversion circuit 14 causes the third connection path 33 to the system power supply 4 and the first connection path 31 to the solar cell array 1. By disconnecting the connection to the second connection path 32 to the load 6 and the load 6, when the DC power is output from the solar cell array 1, the AC power converted by the DC / AC conversion circuit 15 is passed through the connection path 32. It is also possible to continuously supply electric power to the load 6.

[Third Embodiment] The third embodiment of the present invention will be described below.

In the second embodiment described above, when the power supply from the system power supply 4 is stopped, the power supplied to the load 6 is only the power supplied from the solar cell array 1. . Therefore, in the configuration of the second embodiment, the load 6 is required unless the capacity of the solar cell array 1 is sufficiently large and the solar radiation from the sun is sufficiently obtained.
It may be difficult to reliably back up the power supply to the.

In this embodiment, in order to supply sufficient electric power to the load even in such a case, in addition to the solar cell array 1, a fourth battery for connecting a DC battery or the like for supplying DC power is connected. A connection path is provided.

FIG. 7 is a block diagram showing the configuration of the solar power generation system according to this embodiment. In the figure, 1 is a solar cell array, 30 is a grid-connected reverse flow power converter,
Reference numeral 4 is a system power supply, 6 is a load, 13 is a DC / DC conversion circuit that functions as a DC / DC converter, 14 is a bidirectional power conversion circuit that performs conversion between DC and AC, and 15 is DC / AC that performs DC / AC conversion. Conversion circuit, 17 is a smoothing capacitor, 3
1 is a first connection path connecting the solar cell array 1 and the DC / DC conversion circuit 13, 32 is a DC / AC conversion circuit 15
Is a second connection path connecting the load 6 and the load 6, and 33 is a third connection path connecting the bidirectional power conversion circuit 14 and the system power supply 4.

The configuration described above is the same as that of the second embodiment, and in addition to this, the present embodiment further includes a charge / discharge control circuit 18 and a storage battery 22 as a DC power supply, a charge / discharge control circuit 18 and a storage battery. A fourth connection path 34a for connecting to 22
And have.

Since the basic operation of this embodiment is the same as that of the second embodiment, the added portion will be mainly described.

The charge / discharge control circuit 18 forms a part of the grid-connected reverse flow power converter 30, and the DC / DC converter 1
3, the bidirectional power conversion circuit 14, and the DC / AC conversion circuit 15 are connected to a common connection point, and charge / discharge of the storage battery 22 is controlled.

The storage battery 22 is a direct current power source for storing and discharging electric power by the charge / discharge control circuit 18, and is composed of lead and NiC.
d, NiMH, Li ion, Li metal, etc.
It may be a fuel cell that receives refueling and accumulates electric power.

In the second embodiment, the power supply from the system power supply 4 is stopped and the DC / DC conversion circuit 1
When the output from 3 is less than the power consumption of the load 6, it is impossible to back up the load 6 by the grid-connected reverse power flow converter 30, that is, the DC / DC conversion circuit 13, but in the present embodiment, When backup by the DC / DC conversion circuit 13 becomes impossible, the fourth
The storage battery 22 connected to the connection path 34a operates the charge / discharge control circuit 18 to make up for the power shortage in the DC / DC conversion circuit 13 alone, and operates to back up the load 6.

Therefore, the function of the load 6 is not impaired even when the power supply from the system power supply 4 is stopped, and the capacity of the solar cell array 1 can be reduced.

Of course, when electric power is supplied from the system power supply 4, the charge / discharge control circuit 18 is operated to operate the storage battery 2
If 2 is charged, it is not necessary to separately charge the storage battery 22.

[Fourth Embodiment] The fourth embodiment of the present invention will be described below.

The third embodiment has a configuration in which the charge / discharge control circuit 18 and the storage battery 22 are added as a backup to the second embodiment, but this embodiment uses an AC power supply different from the system power supply 4. A fourth connection path for connection is provided.

FIG. 8 is a block diagram showing the configuration of a solar power generation system according to the fourth embodiment of the present invention. In the figure, 1 is a solar cell array, 30 is a system interconnection reverse flow power converter, 4 is a system power supply, 6 is a load, and 13 is DC / D.
DC / DC conversion circuit acting as C converter, 14 bidirectional power conversion circuit for converting DC / AC, 15 DC / AC conversion circuit for DC / AC conversion, 17 smoothing capacitor, 31 solar cell array 1 is a first connection path connecting the DC / DC conversion circuit 13 and 32 is a second connection path connecting the DC / AC conversion circuit 15 and the load 6.
Reference numeral 3 is a third connection path that connects the bidirectional power conversion circuit 14 and the system power supply 4.

The configuration described above is the same as that of the second embodiment, and in addition to this, the present embodiment has a power conversion circuit for 19 AC generators, 25 AC generators, and 34b power conversion circuits. It has a connection path between 19 and the AC generator 25.

Since the basic operation of this embodiment is the same as that of the second embodiment, the added portion will be mainly described.

The power converter circuit 19 for the AC generator constitutes a part of the grid-connected reverse flow power converter 30 and is a DC / DC converter.
The conversion circuit 13, the bidirectional power conversion circuit 14, and the DC / AC conversion circuit 15 are connected to a common connection point, and the AC generator 2 is connected.
The AC power output from 5 is converted into DC power and output.

The AC generator 25 is an AC generator that emits electric power through the power conversion circuit 19, and includes wind power, hydraulic power, and
Any power source may be used, such as thermal power and a micro gas turbine, as long as it is a power source that generates AC power.

In the second embodiment, the power supply from the system power supply 4 is stopped and the DC / DC conversion circuit 1
When the output of 3 is less than the power consumption of the load 6, backup of the load 6 by the grid-connected reverse flow power converter 30, that is, the DC / DC conversion circuit 13 is not possible. When the backup by the DC / DC conversion circuit 13 becomes impossible, the electric power output from the AC generator 25 via the fourth connection point path is converted by the power conversion circuit 19, and the DC / DC conversion circuit 1
It is configured such that the load 6 is backed up by supplementing the shortage of electric power with only the load 3.

Therefore, the function of the load 6 is not impaired even when the power supply from the system power supply 4 is stopped, and the capacity of the solar cell array 1 can be reduced.

[Fifth Embodiment] The fifth embodiment of the present invention will be described below.

The second embodiment has a structure in which the AC voltage for driving the load 6 does not depend on the AC voltage from the grid power supply 4, but when the power supply from the grid power supply 4 is stopped. In addition, all the loads 6 are connected to the solar array
Since it is configured to back up only by itself, reliable backup may not be possible unless the capacity of the solar cell array 1 is sufficiently large and solar radiation from the sun is sufficiently obtained. It has been described in the third embodiment.

In this embodiment, the emergency load is preferentially driven when the power supply from the system power supply 4 is stopped.

FIG. 9 is a block diagram showing the configuration of the solar power generation system according to the fifth embodiment of the present invention. In the figure, 1 is a solar cell array, 30 is a system interconnection reverse flow power converter, 4 is a system power supply, 6 is a load, and 13 is DC / D.
DC / DC conversion circuit acting as C converter, 14 bidirectional power conversion circuit for converting DC / AC, 15 DC / AC conversion circuit for DC / AC conversion, 17 smoothing capacitor, 31 solar cell array 1 is a first connection path connecting the DC / DC conversion circuit 13 and 32 is a second connection path connecting the DC / AC conversion circuit 15 and the load 6.
Reference numeral 3 is a third connection path that connects the bidirectional power conversion circuit 14 and the system power supply 4.

The configuration described above is the same as that of the second embodiment. In addition to this, the present embodiment has a second DC / AC conversion circuit for performing an emergency load of 9 and a DC / AC conversion of 15a. , 34c of the emergency load 9 and a fourth DC / AC conversion circuit path 15a.

Since the basic operation of this embodiment is the same as that of the second embodiment, the added portion will be mainly described.

The emergency load 9 is an AC load which is backed up separately from the load 6 in an emergency or the like by the AC power supplied from the second DC / AC conversion circuit 15a,
It is an important load having a higher priority than the load 6 or a load required only in an emergency.

The second DC / AC conversion circuit 15a constitutes a part of the grid-connected reverse power flow converter 30 and is a DC / DC converter.
The emergency load 9 is connected to a common connection point with the conversion circuit 13, the bidirectional power conversion circuit 14, and the DC / AC conversion circuit 15.
The AC power converted from the DC power is output to.

In the second embodiment, the power supply from the system power supply 4 is stopped and the DC / DC conversion circuit 1 is
When the output of 3 is less than the power consumption of the load 6, backup of the load 6 by the grid-connected reverse flow power converter 30, that is, the DC / DC conversion circuit 13 is not possible. When the backup by the DC / DC conversion circuit 13 becomes impossible, the system-connected reverse power flow converter 30 is provided separately from the DC / AC conversion circuit 15.
The second DC / AC conversion circuit 15a provided in the
The electric power is preferentially supplied to the emergency load 9 connected to the connection path 34c. In this case, it is conceivable to stop the operation of the DC / AC conversion circuit 15 and to operate only the second DC / AC conversion circuit 15a when the power supply from the system power supply 4 is stopped.

Of course, at this time, the AC voltage output from the second DC / AC conversion circuit 15a may be any value suitable for the emergency load.

[Sixth Embodiment] The sixth embodiment of the present invention will be described below.

In the fifth embodiment, the fourth DC / AC converting circuit 15 is provided separately from the DC / AC converting circuit 15, and the second DC / AC converting circuit 15a is provided in the grid-connecting reverse flow power converter 30. AC power is output via the emergency load 9
Is driven by alternating current, but some users have a demand to drive a direct current load in an emergency.

The present embodiment meets such a requirement, and in addition to the load 6, a DC emergency load is provided.

FIG. 10 is a block diagram showing the configuration of a solar power generation system according to the sixth embodiment of the present invention. In the figure, 1 is a solar cell array, 30 is a system interconnection reverse flow power converter, 4 is a system power supply, 6 is a load, and 13 is DC /
A DC / DC conversion circuit that functions as a DC converter, 14 a bidirectional power conversion circuit that converts between DC and AC, 15 a DC / AC conversion circuit that performs DC / AC conversion, 17 a smoothing capacitor, 31 a solar cell array 1 is a first connection path connecting the DC / DC conversion circuit 13 and 32 is a second connection path connecting the DC / AC conversion circuit 15 and the load 6;
Reference numeral 33 is a third connection path that connects the bidirectional power conversion circuit 14 and the system power supply 4.

The above-mentioned structure is the same as that of the second embodiment. In addition to this, the present embodiment has the second DC which acts as an emergency load 9a and a DC / DC converter 26.
/ DC conversion circuit, emergency load 9a of 34d and second DC
And a fourth connection path for connecting to the / DC conversion circuit 26.

Since the basic operation of this embodiment is the same as that of the second embodiment, the added portion will be mainly described.

The emergency load 9a is a DC load that is backed up separately from the load 6 in an emergency or the like by the AC power supplied from the second DC / DC conversion circuit 26,
It is an important load having a higher priority than the load 6 or a load required only in an emergency.

The second DC / DC conversion circuit 26 forms a part of the grid-connected reverse power flow converter 30, and includes the DC / DC converter 13, the bidirectional power converter 14, and the DC / AC converter 15. It is connected to a common connection point with and converts DC power into DC power to be output to the emergency load 9a and outputs the DC power.

In the second embodiment, when the power supply from the grid power supply 4 is stopped and the output of the DC / DC converter circuit 13 is below the power consumption of the load 6, the grid-connected reverse power flow converter is shown. 30, that is, the backup of the load 6 by the DC / DC conversion circuit 13 becomes impossible, but in the present embodiment, when the backup by the DC / DC conversion circuit 13 becomes impossible, the load 6 is replaced by the DC / AC conversion circuit 15. Separately, by the second DC / DC conversion circuit 26 provided in the system interconnection reverse flow power converter 30, the fourth connection path 34d
The power is preferentially supplied to the emergency load 9a connected to. In this case, it is conceivable to stop the operation of the DC / AC conversion circuit 15 and to operate only the second DC / DC conversion circuit 26 when the power supply from the system power supply 4 is stopped.

Of course, at this time, similarly to the fifth embodiment, the voltage supplied to the second DC / DC converting circuit 26 may be any value suitable for the emergency load.

[Seventh Embodiment] A seventh embodiment of the present invention will be described below.

The first to sixth embodiments described above are
It corresponds to the basic configuration example to the application example of the solar power generation system according to the present invention. This embodiment is a combination of these embodiments.

FIG. 11 is a block diagram showing the configuration of the solar power generation system according to the seventh embodiment of the present invention. In the figure, 1 is a solar cell array, 30 is a system interconnection reverse flow power converter, 4 is a system power supply, 6 is a load, and 13 is DC /
DC / DC conversion circuit acting as a DC converter, 14 bidirectional power conversion circuit between DC and AC, 15 DC / AC conversion circuit for DC / AC conversion, 17 smoothing capacitor, 31 solar cell array 1 and DC / DC conversion circuit 13
, A second connection path connecting the DC / AC conversion circuit 15 and the load 6, and a third connection path connecting the bidirectional power conversion circuit 14 and the system power supply 4. It is a connection route.

The configuration described above is the same as that of the second embodiment. In addition to this, the present embodiment has an emergency load 9a, a charge / discharge control circuit 18 and a storage battery 22 as a DC power source, and 26a. Second DC / DC conversion circuit that functions as a DC / DC converter of the third battery, a fourth connection path connecting the storage battery 22 of 34a and the charge / discharge circuit 18, and an emergency load 9 of 35
a for connecting a and the second DC / DC conversion circuit 26a
And a connection path of.

Since the basic operation of this embodiment is the same as that of the second embodiment, the added portion will be mainly described.

The emergency load 9a is the DC / AC conversion circuit 1
Second DC / DC conversion circuit 26a provided separately from
It is an important load which is driven by the electric power output from the device and has a higher priority than the load 6 which is backed up separately from the load 6 in an emergency or a DC load required only in an emergency.

The second DC / DC converting circuit 26a forms a part of the grid-connected reverse power flow converting device 30, is commonly connected to the connection point of the charge / discharge control circuit 18 and the storage battery 22, and is used for emergency use. DC power converted from DC power is output to the load 9a.

That is, the present embodiment has a structure in which the third embodiment and the sixth embodiment are combined.

In the second embodiment, when the power supply from the grid power supply 4 is stopped and the output of the DC / DC conversion circuit 13 is below the power consumption of the load 6, the grid-connected reverse power flow converter is shown. 30, that is, the backup of the load 6 by the DC / DC conversion circuit 13 becomes impossible, but in the present embodiment, the DC / AC conversion circuit 15 is provided at the time when the backup by the DC / DC conversion circuit 13 becomes impossible. Separately from the grid-connected reverse flow power converter 30, the second DC / DC converter 26a is provided to preferentially supply power to the emergency load 9a via the fifth connection path 35. Be seen. In this case, it may be possible to stop the operation of the DC / AC conversion circuit 15 and to operate the second DC / DC conversion circuit 26a at the time when the power supply from the system power supply 4 is stopped.

Of course, at this time, as in the sixth embodiment, the DC voltage supplied from the second DC / DC converting circuit 26a may be any value suitable for the emergency load 9a.

In this embodiment, the second DC
The input to the / DC conversion circuit 26a is the fourth connection path 34
The second DC / DC conversion circuit 26, which is connected to a
The input to a is DC / DC as in the sixth embodiment.
It may be commonly connected to a connection point between the conversion circuit 13 and the charge / discharge control circuit 18, and the emergency load 9a and the storage battery 22 may be connected.
The form may be such that the and are directly connected.

[Other Embodiments] The configurations of the above-described embodiments are shown for the sake of concrete explanation of the present invention, and do not limit the scope of the present invention.

That is, according to the present invention, in a solar power generation system having at least a solar cell array, a system power supply, and a load, when the power consumption of the load is lower than the DC power supplied from the solar cell array, the surplus power is consumed. Is connected to the system power supply to perform reverse power flow conversion, and when the power consumption of the load exceeds the DC power supplied from the solar cell array, a power converter configured to supplement the insufficient power from the system power supply. Is provided, and the voltage of the connection path to the load of the power conversion device is not affected by the AC voltage of the connection path connected to the system power supply.

In this case, it is preferable to operate in a state where the AC voltage of the connection path to the load is lower than the AC voltage of the system power supply.

In a preferred embodiment of the invention,
As another power source of the solar cell, a storage battery capable of storing electric power and a circuit for charging and discharging the storage battery, an AC generator and a power conversion circuit of the AC generator may be provided. Alternatively, an AC or DC emergency load may be provided, or they may be combined.

Another object of the present invention is to supply a storage medium having a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to supply the computer (or CPU) of the system or apparatus.
It is needless to say that it can be achieved by reading and executing the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

A storage medium for supplying the program code is, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD.
-R, magnetic tape, non-volatile memory card, ROM, etc. can be used.

Further, not only the functions of the above-described embodiments are realized by executing the program code read by the computer, but also the OS (operating system) running on the computer based on the instructions of the program code. It is needless to say that this also includes a case where the above) performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written in the memory provided in the function expansion board inserted in the computer or the function expansion unit connected to the computer, based on the instruction of the program code, It goes without saying that a case where the CPU or the like included in the function expansion board or the function expansion unit performs some or all of the actual processing and the processing realizes the functions of the above-described embodiments is also included.

When the present invention is applied to the above storage medium, the storage medium stores the program code corresponding to the above-described flowchart (shown in FIG. 12).

[0159]

As described above, according to the present invention, it becomes possible to output an arbitrary AC voltage to the load regardless of the AC voltage of the system power supply, and the AC voltage of the system power supply rises. Also in this case, it is possible to prevent the AC voltage output to the load from increasing when reverse power flow is performed, and prevent the life of the device used as the load from decreasing.

In addition, the islanding prevention function, which is required when performing reverse power flow in a general system interconnection and which stops the operation of the power conversion device when the power supply from the system power supply is stopped, is not necessary. Independent operation becomes possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a photovoltaic power generation system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an overall configuration of a photovoltaic power generation system of Conventional Example 1.

FIG. 3 is a block diagram showing an overall configuration of a photovoltaic power generation system of Conventional Example 2.

FIG. 4 is a block diagram showing an overall configuration of a photovoltaic power generation system of Conventional Example 3.

FIG. 5 is a block diagram showing an overall configuration of a photovoltaic power generation system of Conventional Example 4.

FIG. 6 is a block diagram showing an overall configuration of a photovoltaic power generation system according to a second embodiment of the present invention.

FIG. 7 is a block diagram showing an overall configuration of a photovoltaic power generation system according to a third embodiment of the present invention.

FIG. 8 is a block diagram showing an overall configuration of a photovoltaic power generation system according to a fourth embodiment of the present invention.

FIG. 9 is a block diagram showing an overall configuration of a photovoltaic power generation system according to a fifth embodiment of the present invention.

FIG. 10 is a block diagram showing an overall configuration of a photovoltaic power generation system according to a sixth embodiment of the present invention.

FIG. 11 is a block diagram showing an overall configuration of a photovoltaic power generation system according to a seventh embodiment of the present invention.

FIG. 12 is a flowchart illustrating an operation of the power conversion device according to the first embodiment of the present invention.

[Explanation of symbols]

1 Solar cell array 2 connection boxes 3, 3a, 30 Power converter 4 power supply 5 switchboard 6 load 7 Uninterruptible power supply 7a, 22 storage battery 7b Power converter 8 emergency generator 9, 9a, 12 Emergency load 10a, 10b transformer 11 Important load 13 DC / DC conversion circuit 14 Bidirectional power conversion circuit 15 DC / AC conversion circuit 19 Power conversion circuit 16 Motor load 17 Capacitor 18 Charge / discharge control circuit 25 AC generator 31-35 Connection route

Claims (8)

[Claims] 1. A solar cell array, a system power supply, a load, and a connection path that is different from the solar cell array, the system power supply, and the load, and the power consumption of the load is the solar cell. When the power is less than the power supplied from the array, the DC power output from the solar cell array is converted to AC power and output to the load, and the surplus AC power is connected to the grid power supply to reverse the power. When the power consumption of the load exceeds the power supplied from the solar cell array, the direct current power output from the solar cell array is converted into alternating current power and output to the load, and the insufficient alternating current And a power conversion device configured to supplement electric power from the system power supply, wherein a connection path to the load in the power conversion device is connected to the system power supply. Photovoltaic system characterized in that it is not connected connection path electrically directly. 2. The solar power generation system according to claim 1, wherein the power conversion device outputs AC power to the load at a voltage lower than the voltage of the grid power supply. 3. A power supply is further provided, and the power conversion device includes a detection means for detecting the presence or absence of power supply from the system power supply, and when it is detected that there is no power supply from the system power supply, The solar power generation system according to claim 1 or 2, wherein electric power output from the solar cell array and electric power supplied from the power source are output to the load. 4. A power supply and an emergency load are further provided, and the power conversion device includes a detection means for detecting the presence or absence of power supply from the system power supply, and there is no power supply from the system power supply. The solar power according to claim 1 or 2, wherein, when detected, the power output from the solar cell array and the power supplied from the power source are output to the load and the emergency load. Power generation system. 5. A power supply and an emergency load are further provided, and the power conversion device includes a detection means for detecting the presence or absence of power supply from the system power supply, and there is no power supply from the system power supply. The photovoltaic power generation according to claim 1 or 2, wherein when detected, the power output from the solar cell array and the power supplied from the power source are preferentially output to the emergency load. system. 6. The power source is one of a storage battery, a generator, and a fuel cell, and the power source is any one of claims 3 to 5.
The solar power generation system according to any one of 1. 7. A power conversion device for a photovoltaic power generation system including a solar cell array, a system power supply, and a load, wherein the solar cell array, the system power supply, and the load are connected by different connection paths. When the power consumption of the load is less than the power supplied from the solar cell array, the DC power output from the solar cell array is converted to AC power and output to the load, and When the power consumption of the load exceeds the power supplied from the solar cell array, the direct current power output from the solar cell array is converted into AC power. It is configured to convert and output to the load, and to supplement the lacking AC power from the system power supply, connection to the load in the power conversion device. Road is, the power conversion device of the photovoltaic power generation system characterized by not connected connection path electrically directly to the system power supply. 8. A method for controlling a photovoltaic power generation system including a solar cell array, a system power supply, a load, and a power conversion device, wherein the power conversion device includes the solar cell array, the system power supply, and Providing different connection paths between the load and each of the loads, the power conversion device is output from the solar cell array when the power consumption of the load is less than the power supplied from the solar cell array. While converting the direct current power to the alternating current power and outputting it to the load, the surplus alternating current power is connected to the system power supply to reverse flow, and the power consumption of the load is the power supplied from the solar cell array. When it exceeds, while converting the direct current power output from the solar cell array to alternating current power and outputting to the load, operating to supplement the lacking alternating current power from the system power supply, A method for controlling a photovoltaic power generation system, wherein a connection path to the load in the power conversion device is not electrically directly connected to a connection path to the system power supply.