JP3363354B2 - Solar power system - Google Patents

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 in which a power supply device using a solar cell is electrically connected to a commercial power source to perform grid interconnection operation so as to supply power to a common load. It is a thing.

[0002]

2. Description of the Related Art In recent years, as one of the measures to prevent global warming due to carbon dioxide, a solar cell is installed in a house for private power generation, and the electric power obtained by the solar cell is converted into electric power to connect to a commercial power source. It is considered to perform system operation. That is, the DC power output from the solar cell is converted into AC power by using the inverter circuit, and the power transmission system is connected to the commercial power source for system interconnection. Regarding such grid interconnection operation between private power generation and commercial power source, technical guidelines are given in the distributed power grid interconnection technical guidelines (hereinafter abbreviated as guidelines) issued by the Japan Electric Association. Has been done. This guideline ensures the quality, safety, reliability, and protection coordination of power supplied by commercial power sources,
It is shown for smooth grid interconnection.

By the way, as a solar power generation system,
As shown in FIG. 7 , an interconnection breaker 21 and a main line Lm connected from a single-phase three-wire commercial power source AC via a current limiter (hereinafter referred to as a limiter) 11 and a main breaker 12 including an earth leakage breaker. Parallel switch 22a, 2
There is one in which a power converter 23 for converting the power of the output of the solar cell 20 is connected via 2b. The limiter 11 is a breaker provided to limit the load current of the customer to a value equal to or less than the contract value with the electric power company. The power converter 23 uses the inverter circuit as described above, and has a function of converting the DC voltage output from the solar cell 20 into an AC voltage. A plurality of branch circuits Lb are connected to the trunk line Lm between the main breaker 12 and the interconnection breaker 21 via branch breakers 13. Limiter 1
1, the main breaker 12, the branch breaker 13, the interconnection breaker 21, the disconnect switch 22a, 22b is housed in the distribution board 1, the solar cell 20 is installed on the roof of the house, the power converter 23 is a solar cell It is placed outside the house in order to keep the wiring to and from 20 as short as possible. The reason why the wiring between the solar cell 20 and the power converter 23 is shortened and arranged outdoors is that a direct current flows between the solar cell 20 and the power converter 23 so as not to increase the loss, and the solar cell This is because the maximum output voltage of 20 is about 300 V, so that the possibility that high-voltage wiring will come into contact with people is reduced and safety is improved.

The disconnect switches 22a and 22b are provided for disconnecting the commercial power source AC and the power converter 23 when an abnormality occurs or when the commercial power source AC fails. That is, the grid disconnection switches 22a and 22b are turned on to perform system interconnection, and system disconnection is performed when the breaker switches 22a and 22b are turned off (that is, in the disconnected state). According to the above guideline, it is desirable that the disconnecting switches 22a and 22b have two contacts inserted between the two systems for system interconnection.

By the way, the disconnection switches 22a and 22b are disconnected when an abnormality or a power failure of the commercial power supply AC is detected by the grid interconnection protection device 25, and the grid interconnection protection device 25 is interconnected. Breaker 21 and disconnect switch 22
An abnormality or a power failure is detected based on the output of the sensor 27 inserted between a and 22b. In other words, the sensor 27 detects the current flowing in the main line Lm and the voltage between the lines, and transfers it to the grid interconnection protection device 25, so that an abnormality or a power failure can be detected. Since the disconnection switches 22a and 22b are inserted between the power converter 23 and the branch breaker 13, power is supplied to the branch circuit Lb even when power is being generated by the solar cell 20 during an abnormality or a power failure. Can not do. Therefore, the power converter 23 and the disconnection switch 22
It has been proposed to connect a shared branch circuit Lc between a and 22b via a shared branch breaker 24. If such a shared branch circuit Lc is provided, it becomes possible to supply power to the shared branch circuit Lc regardless of whether the system is connected or separated. That is, even when an abnormality occurs or a power failure occurs, power can be supplied to the shared branch circuit Lc as long as the power converter 23 outputs normally. As a result, there is a high possibility that power can be supplied to a load such as a communication device such as a telephone that needs to be supplied with priority.

[0006]

By the way, in the above-described photovoltaic power generation system, since the grid interconnection protection device 25 only performs grid separation by the disconnecting switches 22a and 22b in the event of an abnormality or power failure, In the event of a power failure, the power converter 23 automatically supplies power to the shared branch circuit Lc.

However, when an abnormality or a power failure occurs due to a disaster, there is a possibility that a short circuit or disconnection of the wiring system may occur, and if power is supplied to the common branch circuit Lc without inspecting the wiring system after disconnection. It may not be possible to ensure sufficient safety. The present invention has been made in view of the above circumstances, and an object thereof is to provide a solar power generation system with improved safety by manually selecting whether or not to supply power to a shared branch circuit at the time of system separation. To provide.

[0008]

According to the invention of claim 1, a solar cell, a power converter for converting direct current output from the solar cell into an alternating current, a main line connected to a commercial power source, and a power converter are provided. A parallel disconnection switch inserted between them to switch between grid interconnection and grid separation, a common branch circuit that supplies power to the load from the electric line between the power converter and the parallel disconnection switch, and an abnormality or commercial power supply. When a power outage is detected, the decoupling switch is driven to separate the grid and the grid converter protects the power from the power converter to the shared branch circuit. The power converter is equipped with an operation switch that restarts the power supply to the branch circuit.
It is configured to lower the output voltage when disconnecting from the grid.
Between the power converter and the common branch circuit during grid interconnection.
Does not change the line voltage of the shared branch circuit when the system is separated
Switch the connection between the power converter and the common branch circuit
A switching switch is provided . According to this configuration, the power is disconnected by the disconnect switch when an abnormality occurs or the commercial power supply is interrupted, but it is possible to supply the power from the power converter to the shared branch circuit if power is generated by the solar cell. . However, power is not automatically supplied from the power converter to the shared branch circuit at the time of grid separation, but power is temporarily stopped from the power converter to the shared branch circuit at the time of grid separation, and the operation switch is When it is operated, the power supply from the power converter to the shared branch circuit is restarted, so when the system is separated due to an abnormality or power failure, by operating the operation switch after confirming safety The safety can be improved. Furthermore, the lineage
At the time of separation, only the solar cell will be the power source, so a power converter
The current capacity is secured by lowering the output voltage of
Therefore, power conversion is performed during grid interconnection and grid separation.
Since the output voltage of the converter changes, it is shared with the power converter.
By switching the connection relationship with the road with the switching switch
Common branch regardless of grid connection and grid separation
It is possible to prevent changes in the line voltage of the circuit.

[0009] invention of claim 2 is the invention of claim 1, wherein the diverter switch, a first contact connected to a shared branch circuit a first output line of the power converter during the system partition, power A second contact for connecting the second output line of the power converter, which divides the output voltage of the first output line of the converter and outputs the divided voltage, to the shared branch circuit during grid interconnection, the first contact, and the second contact. And an interlocking means for interlocking so as to prevent the contact of the switch from being turned on at the same time.
According to this configuration, the interlock means is provided to prevent the first contact and the second contact inserted between the power converter and the shared branch circuit from being turned on at the same time. It is possible to reliably prevent the first contact point and the second contact point from being turned on at the same time, and to prevent a short circuit between the two output lines of the power converter.

According to a third aspect of the present invention, in the first aspect of the invention, when the system interconnection protection device detects an abnormality or cancellation of a power failure, the system interconnection operation is automatically restored.
According to this configuration, the system is separated due to the abnormality or the power failure, but the system is automatically restored to the system interconnection operation when the abnormality or the power failure is restored, so that there is no trouble of performing the restoration operation.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the box including the disconnecting switch, the power converter, and the system interconnection protection device is provided, and the operation unit including the operation switch is different from the box. It is provided on the body. According to this configuration, the operation unit can be placed in a place different from the disconnecting switch and the power converter, so that the box is installed outdoors to shorten the electric path between the power converter and the solar cell, for example. Even if it is installed in the room, the operability can be improved by arranging the operation unit indoors.

According to a fifth aspect of the present invention, in the second aspect of the present invention, the disconnecting switch and the switching switch are each combined with a relay having two normally open contacts. According to this configuration, since the parallel switch and the switching switch are configured only by the relays each having two normally open contacts,
It is possible to configure the disconnecting switch and the switching switch only with relatively inexpensive relays, reduce the number of component types, and consequently reduce the overall cost.

[0013]

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) The basic construction of this embodiment is the same as the conventional construction shown in FIG. 7 , and as shown in FIG. The main difference is that the operation unit 22 is provided.

That is, as in the conventional configuration, the limiter 1
A power converter 23 is connected to a main line Lm connected to a commercial power supply AC via a main breaker 12 and a main breaker 12 via an interconnection breaker 21 and disconnection switches 22a and 22b. The power converter 23 converts the direct current output of the solar cell 20 into alternating current similar to the commercial power supply AC, and has an inverter circuit as a main component. A plurality of branch circuits Lb are connected to the trunk line Lm between the main breaker 12 and the interconnection breaker 21 via branch breakers 13.

By the way, the limiter 11 and the main breaker 1
2, the branch breaker 13, and the interconnection breaker 21 are housed in the distribution board 1 in the same manner as in the conventional configuration.
2b is a power converter 2 provided outside the distribution board 1 in this embodiment.
3 and the system interconnection protection device 25 are unitized and housed in the box 2. The box 2 is usually placed outdoors near the solar cell 20 so that the loss of DC power in the path from the solar cell 20 to the power converter 23 is reduced. Power converter 23 and disconnection switch 22a,
The common branch circuit Lc is connected to the circuit 22b via the common branch breaker 24.

The system interconnection protection device 25 is an interconnection breaker 21.
The abnormality and the power failure are detected based on the output of the sensor 27 inserted between the disconnection switch 22a and the disconnection switch 22b. Sensor 2
Reference numeral 7 includes a current sensor that detects a current flowing through the main line Lm and a voltage sensor that detects a voltage between the main lines Lm.
By passing the detected values of the current and the voltage to the grid interconnection protection device 25, the grid interconnection protection device 25 detects the voltage fluctuation and the frequency fluctuation, and if there is an abnormality in these, the disconnection switches 22a and 22b are turned on. Disengage. Further, it is possible to detect a power failure of the commercial power supply AC based on changes in voltage and current.

By the way, the power converter 23 is configured to output an alternating current of 200 V (when the commercial power source is 100 V) at the time of system interconnection, and output an alternating current of 100 V at the time of system isolation. The system interconnection protection state or the system isolation state is indicated by a notification signal from the system interconnection protection device 25. In addition, the power converter 23 divides the output into equal parts, and connects the divided midpoint to the neutral line of the main line Lm during grid interconnection. The output voltage of the power converter 23 is switched between the time of system interconnection and the time of system isolation in order to secure the current capacity by lowering the output voltage because only the solar cell 20 serves as a power source during system isolation. In this way, the output voltage of the power converter 23 changes between the system interconnection and the system separation, so that the line voltage of the shared branch circuit Lc is not changed between the system interconnection and the system separation. A means for switching the connection relationship between the power converter 23 and the shared branch circuit Lc is required. So 3
Is provided with a switching switch 29b comprises a diverter switch 29a and the contact r _21, r ₂₂ of the two-pole comprising a contact r ₁₁ ~r ₁₃ poles between the common branch breakers 24 and power converter 23. Here, the parallel switch 22a, 22b and the switching switch 2
9a and 29b are electromagnetic relays.

[0019] is controlled by the switching signal from the switching switch 29a of the contact r ₁₁ ~r ₁₃ and diverter switch 29b contacts r _21, the power so as not to turn on at the same time the r ₂₂ converter 23. Diverter switch 29a each contact r ₁₁ ~ between the 3 lines from 3 lines and disconnecting switch 22b from the power converter 23
r ₁₃ is inserted, and all the contacts r _{11 to} r ₁₃ are inserted in the same electric circuit. Here, in FIG. 1, the output lines from the power converter 23 are referred to as a line, b line, and c line from the top. One contact r ₂₂ of the change-over switch 29b is connected in parallel with the contact r ₁₃ inserted in the line c of the contact r ₁₁ ~r ₁₃ of the change-over switch 29a. The other contact r ₂₁ of the switching switch 29b is connected at one end between the power converter 23 and the contact r ₁₁ inserted into the line a among the contacts r _{11 to} r ₁₃ of the switching switch 29a. The other end is connected between the contact r ₁₂ inserted in the wire and the shared branch breaker 24.

In short, the shared branch breaker 24 is connected to one power line of the main line Lm and the neutral line when the system is connected, and the line voltage between the a line and the c line is 100 V when the system is separated. contact r _21, r ₂₂ is inserted from becomes between the diverter switch 29b is shared branch breakers 24 and a line and c-line, the line voltage between a line and c-line at the time of system interconnection is 200V Therefore, the switching switch 29a is connected to the line b and the line c.
Contact points r ₁₂ and r ₁₃ are inserted between the line and the common branch breaker 24. In other words, the common branch breaker 24 is connected to the b line and the c line at the time of system interconnection, and a at the time of system isolation.
Since it is connected to the line and the c line, one end of the shared branch breaker 24 must be selectively connected to one of the a line and the b line at the time of system interconnection and system isolation. That is,
The contact r ₁₂ of the switching switch 29a and the contact r ₂₁ of the switching switch 29b must be prohibited from turning on at the same time. If both contacts r ₁₂ and r ₂₁ are turned on at the same time, there will be a problem that the a line and the b line are short-circuited.

Both switching switches 29a and 29b have a contact point r.₁₁~
r₁₃, R_{twenty one}, R_{twenty two}Are all a contacts (normally open contacts),
If there is no switching signal from the power converter 23, it turns off.
Contact point r₁₂And contact point r_{twenty one}So that and do not turn on at the same time
Therefore, when the system is connected, the contact r of the switching switch 29a₁₁
~ R₁₃Is turned on, and the contact r of the switching switch 29b is turned on._{twenty one}, R _{twenty two}
A switching signal is provided to turn off the. Also, the system
Contact point r when separated₁₁~ R₁₃Turns off. Where the lineage
The power converter 2 is notified by the notification signal from the interconnection protection device 25.
At the stage when the switching signal is generated from 3, the contact r_{twenty one}, R_{twenty two}Is
It is kept off as in the grid connection, and the shared branch circuit
No power is supplied to Lc. Also, during this period
Since power is not supplied from the power converter 23, the power converter
It is desirable to stop the operation of DC-AC conversion by 23.
Good

In this embodiment, an operation switch SW for manual operation is provided, and when the operation restart is instructed by the operation of the operation switch SW, the contact r of the switch 29b is switched.
_A switching signal is given so that ₂₁ and r ₂₂ are turned on. Further, in the case of stopping the operation of the power converter 23, the operation is restarted by an operation restart instruction from the operation switch SW. In this way, the power supply to the common branch circuit Lc is stopped until an instruction is given from the operation switch SW, and when the system is separated due to a disaster or the like, the common branch circuit Lc is inspected and then checked. Since the power supply can be instructed, safety is enhanced.

As described above, after the power supply to the common branch circuit Lc is stopped at the time of an abnormality or a power failure, the power is supplied from the power converter 23 to the common branch circuit Lc by operating the operation switch SW. It will be possible. On the other hand, when the grid interconnection protection device 25 monitoring the output of the sensor 27 no longer detects an abnormality or a power failure, the grid interconnection protection device 25 sends a notification signal to the power converter 23 to notify the cancellation of the abnormality or the power outage. give. In addition, at the same time, the disconnect switches 22a, 22
Instructing b to connect the system to turn on the contact. The power converter 23 turns on the contact point r ₁₁ ~r ₁₃ of the receiving a notification signal for notifying the cancellation of abnormal or power failure diverter switch 29a, to turn off the contact point r _21, r ₂₂ of the change-over switch 29b.
This switching operation is automatically performed regardless of the operation switch SW.

By the way, the two switching switches 29a and 29b are
To ensure that the contacts do not turn on at the same time,
Interlocking the contacts of the exchange switches 29a and 29b
Is desirable. The interlock is based on the electrical
Interlock and mechanical interlock by contact structure
Is considered. For electrical interlock
Is configured as shown in FIG. 2, for example. In this configuration,
Equipped with two a contacts (normally open contacts) as the switch 29b
The electromagnetic relay is used, and the parallel switch 22a, 22b
System separation is performed and the switching switch 29a is connected.
Point r₁₁~ R₁₃Switch is turned off when the switch is turned off.
The driving coil Cb is energized. One
Mari, detraining switch 22a, 22b and switching switch 29
Auxiliary contact r which is ab contact (normally closed contact) for each a₃₁~
r ₃₃And these auxiliary contacts r₃₁~ R₃₃And switching switch
A switching signal is given to the series circuit with the driving coil Cb of 29b.
Contact of switch 29b_{twenty one}, R_{twenty two}Open and close
Is. Parallel switch 22a, 22b and switching switch 2
9a is an auxiliary contact r₃₁~ R₃₃All contacts are a contacts except
Composed of dots.

The disconnecting switches 22a, 22b turns on the auxiliary contact r _31, r ₃₂ and perform the system partition, the output voltage at this time by notification signal is applied to the power converter 23 the power converter 23 is 100V Can be switched. In addition, the switching switch 2
9a turns off the contact r ₁₁ ~r ₁₃ of receiving the diverter switch 29a the notice signal from the system interconnection protection device 25, as a result, auxiliary contacts r ₃₃ is turned on. That is, the drive coil C
All three auxiliary contacts r _{31 to} r ₃₃ connected in series with b are turned on. Here, if the operation switch SW is operated,
A switching signal is given to the coil Cb of the switching switch 29b,
The drive coil Cb is energized through the auxiliary contacts r _{31 to} r ₃₃ , and the contacts r ₂₁ and r ₂₂ are turned on. Since the contact r ₁₁ ~r ₁₃ of the change-over switch 29a in the configuration of FIG. 2 is an auxiliary contact r ₃₃ If off does not turn on, diverter switch 29
The contacts r _{11 to} r _{13 of a} and the contacts r ₂₁ and r of the switching switch 29b.
It is possible to prevent ₂₂ and ₂₂ from being turned on at the same time, and it is possible to prevent a short circuit between the a line and the b line. Here, since the short-circuit prevention between the a-line and the b-line must be performed even when the system is connected, the auxiliary contacts r ₃₁ , r _{33 of the} disconnecting switches 22a, 22b are also connected in series to the drive coil Cb. is there. That is, unless the system disconnection is performed by the disconnecting switches 22a and 22b, the contact r inserted between the line a and the line b.
_This will also turn on a because the ₂₁ never turns on.
A short circuit between the line and the b line is surely prevented.

On the other hand, to perform mechanical interlock,
The configuration as shown in FIG. 3 may be adopted. This is a switching open / close
Instead of providing the devices 29a and 29b, two a contacts r₄₁，
r₄₂And and one b contact r₄₃And a switching switch 29 equipped with
It is provided. Here, the operation of the circuit configuration shown in FIG.
As is clear from the work, both switching switches 29a and 29b
Contact point r₁₃, R_{twenty two}Do not turn on at the same time, which
Since the electrical connection does not change even when the power is on,
In the configuration shown in, both contacts r₁₃, R_{twenty two}Contacts corresponding to are omitted
I am doing it. Further, the contact point r of the switching switch 29a₁₁Is a grid
It is turned on at the time of system and turned off at the time of system separation,
Corresponding contact point r₄₁And the contact point r₁₂Contact with
Point r_{twenty one}Contact r as a contact equivalent to and₄₂, R₄₃Provide
is there. That is, both contact points r₄₂, R₄₃Is one end shared
Connected to one end of the marker 24, contact point r ₄₂The other end of the power converter
Connect to the b line of the 23 output lines, and contact r₄₃The other end of
It is connected to the a line of the output lines of the power converter 23.
Where contact point r₁₂And contact point r _{twenty one}And be turned on at the same time
Is prohibited, contact r₄₂Contact a, contact r₄₃B contact
The interlock is performed by setting the points.
It If this structure is adopted, both contacts r₄₂, R₄₃The same
Sometimes it cannot be turned off, so a grid protection device
DC-AC by the power converter 23 by the notification signal from 25
By stopping the conversion operation and operating the operation switch SW
The operation of the power converter 23 is restarted.

(Second Embodiment) In the first embodiment, the operation switch SW gives an instruction to the power converter 23, but in the present embodiment, as shown in FIG. 4, the operation unit 3 provided separately from the box 2 is provided. The operation switch SW is provided on the control unit 3 and the operation unit 3 is connected to the system interconnection protection device 25. The operation unit 3 includes an operation switch SW and a display device DP including a liquid crystal display device, and a display mode changeover switch S for switching the display content of the display device DP.
It has W ₁ . The display device DP can display the instantaneous power amount, the used power amount, the integrated power amount, and the like calculated based on the current and voltage detected by the sensor 27. In addition, in the present embodiment, an instruction to restart the operation is given to the power converter 23 through the grid interconnection protection device 25.
A switching instruction is given to 9a and 29b through the power converter 23. Other configurations and operations are similar to those of the first embodiment.

(Third Embodiment) In the first embodiment, as the decoupling switches 22a and 22b and the switching switch 29a, those having three a contacts are used. However, as shown in FIG. Then, the parallel switch 22a, 22b and the switching switch 29a, 29b are constituted by only an electromagnetic relay having two a contacts. In the configuration of the first embodiment shown in FIG. 1, the electromagnetic relays each having three a contacts are used as the disconnecting switches 22a and 22b.
In the present embodiment, an electromagnetic relay having two a-contacts is used, and according to the guideline, two contacts are provided between two systems for system interconnection. Therefore, the shared branch circuit of the trunk line Lm is used. By inserting two contacts of each of the disconnecting switches 22a and 22b into the two wires connected to Lc, it is possible to satisfy the guideline for two of the three wires.

On the other hand, in the configuration of the first embodiment shown in FIG. 1, since the switching switch 29a has three a contacts, if it is to be constructed by an electromagnetic relay having two a contacts, it will be 2 A set of electromagnetic relays is required. Therefore, two switching switches 29a ₁ and 29a that are simultaneously turned on and off
₂ is provided, and ₂ is provided for the a line of the output lines of the power converter 23.
Contacts r ₁₁₁ , r of the individual switching switches 29a ₁ , 29a _2
112 is inserted in series and each switching switch 29a ₁ , 29a ₂
The remaining contact points r ₁₂₁ and r ₁₂₂ are inserted into the b line and the c line, respectively. With this configuration, the disconnection switches 22a, 22
two contacts r _111, r _{11 2} of b of diverter switch 29a ₁ also 1 line contact is not inserted, 29a ₂ is to satisfy the guideline will be inserted.

By adopting the contact structure as described above, two a contacts are provided while satisfying the guideline of inserting two contacts each in the electric path connecting the two systems for system interconnection. It can be composed of only electromagnetic relays,
Compared with the case of using a special electromagnetic relay having three a-contacts, the cost can be reduced. Also,
Two disconnection switches 22a, 22b and two diverter switch 29a _1, from 29a ₂ are the respective is off simultaneously, with respect to control of the contact is the same as in the first embodiment shown in FIG.

If only the guidelines are satisfied, FIG.
As shown in FIG. 1, in addition to the configuration of the first embodiment shown in FIG. 1, only one of the disconnecting switches 22a may be configured by an electromagnetic relay having two a contacts. Other configurations and operations are Ru similar der first embodiment.

[0032]

According to the invention of claim 1, a solar cell, a power converter for converting direct current output from the solar cell into alternating current,
A disconnecting switch that is inserted between a main line connected to a commercial power source and a power converter to switch between grid interconnection and grid separation,
A shared branch circuit that supplies power to the load from the electric line between the power converter and the parallel disconnect switch, and the parallel disconnect circuit that drives the parallel disconnect switch when an abnormality or power failure of the commercial power source is detected, and also performs power separation. The power converter is equipped with a grid interconnection protection device that stops the power supply from the power supply to the shared branch circuit, and an operation switch that manually restarts the power supply from the power converter to the shared branch circuit when the grid is separated. Sometimes grid interconnection
The power converter is configured to lower the output voltage from time to time.
And the shared branch circuit between grid connection and grid separation.
Power conversion so that the line voltage of the shared branch circuit is not changed
Switch that switches the connection between the switch and the shared branch circuit
Is provided , the power is not automatically supplied from the power converter to the shared branch circuit at the time of grid separation, but the power is supplied from the power converter to the shared branch circuit at the time of grid separation. Once the power is turned off and the operation switch is operated, the power supply from the power converter to the shared branch circuit is restarted, so if the system is separated due to an abnormality or power failure, check the safety before operating. There is an advantage that the safety can be enhanced by operating the switch. Furthermore, when the system is separated, only the solar cells
Since it becomes a power source, it is necessary to reduce the output voltage of the power converter.
Therefore, the current capacity is secured, and this ensures that the
The output voltage of the power converter changes between and when the system is separated
Switch the connection between the power converter and the shared branch circuit
By switching the unit, it is possible to
Prevents changes in line voltage of shared branch circuit regardless of separation
It has the advantage that it can be stopped.

[0033] As the invention of claim 2, wherein the diverter switch, a first contact connecting the first output line of the power converter to the shared branch circuit at the time of the system partition, the first power converter The second contact that connects the second output line of the power converter that divides the output voltage of the output line of and outputs to the shared branch circuit at the time of system interconnection, the first contact and the second contact at the same time. In a device provided with an interlock means for interlocking so as to prevent it from being turned on, the first contact and the second contact inserted between the power converter and the shared branch circuit are simultaneously provided. Since the interlock means is provided to prohibit the turning on, the first contact and the second contact are surely prevented from turning on at the same time, and the two output lines of the power converter are prevented. There is an advantage that a short circuit can be prevented.

According to the third aspect of the present invention, when the system interconnection protection device detects the abnormality or the cancellation of the power failure, the system automatically returns to the system interconnection operation, but the system is separated due to the abnormality or the power failure. There is an advantage that there is no need to perform a recovery operation because the system automatically restarts when the system is recovered from an abnormality or power failure. According to a fourth aspect of the present invention, a box including a disconnect switch, a power converter, and a system interconnection protection device is provided, and an operation unit including an operation switch is provided separately from the box. Since the operation unit can be placed in a place different from the disconnect switch and the power converter, for example, the box is installed outdoors to shorten the electric path between the power converter and the solar cell. Even in such a case, there is an advantage that the operability is facilitated by disposing the operation unit indoors.

According to the fifth aspect of the present invention, in the combination of the parallel disconnecting switch and the switching switch each having two normally open contacts, two normally open contacts are provided. Since the disconnecting switch and the switching switch are composed of only the relay, the disconnecting switch and the switching switch can be composed of only the relatively inexpensive relay, and the number of parts can be reduced. There is an advantage that the overall cost can be reduced.

[0036]

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment.

FIG. 2 is a main part circuit diagram showing a modified example of the above.

FIG. 3 is a main part circuit diagram showing another modified example of the above.

FIG. 4 is a circuit diagram showing a second embodiment.

FIG. 5 is a main part circuit diagram showing a third embodiment.

FIG. 6 is a circuit diagram of a main part showing an application example.

FIG. 7 is a circuit diagram showing a conventional example.

[Explanation of symbols]

Two boxes 3 operation unit 20 solar cells 22a, 22b Disconnection switch 23 Power converter 25 grid protection device 29a, 29b Switching switch AC commercial power supply Lm main line Lc common branch circuit SW operation switch

Front page continuation (72) Inventor Hirotada Higashihama 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (72) Inventor Hiroaki Yuasa 1048, Kadoma, Kadoma City, Osaka Prefecture (72) Inventor Hiroyuki Ohno 1048 Kadoma, Kadoma City, Osaka Prefecture, Matsushita Electric Works, Ltd. (72) Inventor Eiji Iwami 1048 Kadoma, Kadoma City, Osaka Prefecture (72) Inventor, Hisashi Usui, 1048 Kadoma, Kadoma City, Osaka Prefecture Address: Matsushita Electric Works Co., Ltd. (72) Inventor: Shinichiro Okamoto 1048, Kadoma, Kadoma City, Osaka Prefecture Address: Matsushita Electric Works Co., Ltd. (56) Reference JP-A-9-46923 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) H02J 3/00-9/08

Claims (5)

(57) [Claims] 1. A solar cell, a power converter for converting direct current output from the solar cell into alternating current, and a grid interconnection and grid separation inserted between a main line connected to a commercial power source and a power converter. Switching circuit that switches the power supply, a shared branch circuit that supplies power to the load from the electric path between the power converter and the disconnection switch, and the disconnection switch that drives when an abnormality or commercial power failure is detected. System protection device that stops the power supply from the power converter to the shared branch circuit, and an operation switch that restarts the power supply from the power converter to the shared branch circuit manually when the system is disconnected. The power converter is configured to lower the output voltage when the system is disconnected than when the system is connected.The power converter and the shared branch circuit share a common branch when the system is connected and when the system is separated. Does not change the line voltage of the circuit Thus, the photovoltaic power generation system is provided with a switching switch for switching the connection relationship between the power converter and the shared branch circuit. 2. The switching switch includes a first power converter.
Of the first output line of the power converter and the second output line of the power converter that divides the output voltage of the first output line of the power converter and outputs the divided voltage. A second contact, which is sometimes connected to the shared branch circuit, and an interlock means for interlocking so as to prevent the first contact and the second contact from being turned on at the same time, are provided. The solar power generation system according to claim 1, which is characterized in that. 3. The photovoltaic power generation system according to claim 1, wherein when the grid interconnection protection device detects an abnormality or cancellation of a power failure, it automatically returns to grid interconnection operation. 4. A box comprising a disconnecting switch, a power converter and a system interconnection protection device, wherein an operation unit including an operation switch is provided separately from the box. Item 1. The solar power generation system according to item 1. 5. The disconnection switch and the switching switch are each provided in two pieces.
The photovoltaic power generation system according to claim 2, wherein the photovoltaic power generation system is configured by combining relays each having a normally open contact.
Mu.