JP3721731B2 - Solar power system - Google Patents

Description

[0001]
BACKGROUND 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 and a grid interconnection operation is performed so as to supply power to a common load.
[0002]
[Prior 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 power obtained from the solar cell is converted into electric power to perform grid-connected operation with a commercial power source. Is considered. That is, the DC power output from the solar cell is converted into AC power using an inverter circuit, and the grid connection is performed by connecting the power transmission system to the commercial power source. For such grid-connected operation between private power generation and commercial power, technical guidelines are provided in the distributed power grid interconnection technical guidelines (hereinafter abbreviated as guidelines) published by the Japan Electric Association. Has been. This guideline is shown to ensure the quality, security, reliability, and protection coordination of the power supplied by the commercial power source and to perform smooth grid-connected operation.
[0003]
By the way, as shown in FIG. 8, the photovoltaic power generation system is connected from a single-phase three-wire commercial power supply AC via a current limiter (hereinafter referred to as a limiter) 11 and a main circuit breaker 12 including an earth leakage breaker. There is one in which a power converter 23 that converts the output of the solar cell 20 to power is connected to the main line Lm via the interconnection breaker 21 and disconnection switches 22a and 22b. The limiter 11 is a breaker provided to limit the load current of the customer to a contract value or less with the electric power company. The power converter 23 uses an inverter circuit as described above, and has a function of converting a 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 the branch breakers 13, respectively. Limiter 11, main breaker 12, branch breaker 13, interconnection breaker 21, disconnect switch 22 a, 22 b are housed in distribution board 1, solar cell 20 is installed on the roof of a house, etc., and power converter 23 is solar In order to make the wiring between the battery 20 as short as possible, it is arranged outside the house. The reason why the wiring between the solar cell 20 and the power converter 23 is shortened and disposed outdoors is that a direct current flows between the solar cell 20 and the power converter 23 so that loss is not increased. This is because the maximum output voltage of 20 is about 300 V, so that the possibility of high-voltage wiring touching people is reduced and safety is increased.
[0004]
The disconnect switches 22a and 22b are provided for disconnecting the commercial power source AC and the power converter 23 in the event of an abnormality or a power failure of the commercial power source AC. That is, system interconnection is performed when the disconnection switches 22a and 22b are on, and system separation is performed when the disconnection switches 22a and 22b are off (that is, the disconnected state). According to the guideline, it is desirable that the disconnecting switches 22a and 22b have two contacts inserted between the two systems that perform grid connection.
[0005]
By the way, the disconnection switches 22a and 22b are disconnected when an abnormality or a power failure of the commercial power source AC is detected by the grid connection protection device 25. The grid connection protection device 25 is connected to the grid breaker 21. Abnormalities and power outages are detected based on the output of the sensor 27 inserted between the disconnect switches 22a and 22b. That is, when the sensor 27 detects the current flowing through the trunk line Lm and the voltage between the lines and passes it to the grid interconnection protection device 25, 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 if power is generated by the solar cell 20 in the event of an abnormality or a power failure. Can not do. Therefore, it has been proposed to connect a shared branch circuit Lc between the power converter 23 and the disconnection breakers 22a and 22b via the shared branch breaker 24. Providing such a shared branch circuit Lc makes it possible to supply power to the shared branch circuit Lc regardless of whether the system is interconnected or separated. That is, even if an abnormality or a power failure occurs, power can be supplied to the shared branch circuit Lc as long as an output is normally obtained from the power converter 23. As a result, there is a high possibility that power can be supplied to a load that needs to be supplied with priority, such as a communication device such as a telephone.
[0006]
[Problems to be solved by the invention]
By the way, in the above-mentioned photovoltaic power generation system, when performing maintenance of the power converter 23, it is necessary to turn off the interconnection breaker 21 and to disconnect the solar cell 20 and the power converter 23 from each other. A breaker (not shown) is provided between the solar cell 20 and the power converter 23, and the solar cell 20 and the power converter 23 are disconnected by operating this breaker. Such an operation enables maintenance of the power converter 23. At this time, however, no power is supplied to the shared branch circuit Lc from either the commercial power supply AC or the power converter 23, and the shared branch circuit Lc is not supplied with power. The connected load will stop. In other words, even if the shared branch circuit Lc is connected to a load that originally needs to supply power preferentially, power cannot be supplied to the load that should be operated preferentially during maintenance of the power converter 23. Problems arise.
[0007]
This invention is made | formed in view of the said reason, The objective is to provide the solar power generation system which enabled it to supply electric power to a shared branch circuit also at the time of the maintenance of a power converter. .
[0008]
[Means for Solving the Problems]
  The invention of claim 1 is inserted between a solar cell, a power converter that converts direct current output from the solar cell into alternating current, and a main line connected to a commercial power source and the power converter.Disconnection switch and interconnection breaker,System interconnection protection device that drives the disconnect switch to isolate the system when an abnormality or commercial power failure is detectedAnd load from the electric circuit between the main line and the interconnection breaker at least during grid connectionShared branch circuit that supplies power toAnd a switching switch provided between the power converter and the shared branch circuit, and the power converter is configured to lower the output voltage from the grid connection when the system is separated. A first contact for connecting the first output line of the power converter to the shared branch circuit at the time of system separation, and a second of the power converter for dividing and outputting the output voltage of the first output line of the power converter There are provided a second contact for connecting the output line to the shared branch circuit at the time of grid connection, and an interlock means for interlocking so as to prevent the first contact and the second contact from being simultaneously turned on. Has beenThingsThe
ThisAccording to the configuration, when performing maintenance of the power converter, the power breaker is turned off and the power converter is disconnected from the main line.At least during grid connectionSince the shared branch circuit is connected to the circuit on the commercial power supply side for the interconnection breaker,If grid connectionTurn off the interconnect breakerEven sharedIt is possible to supply power to the branch circuit. In other words, it is possible to supply power to the load connected to the shared branch circuit even during the maintenance period of the solar cell and the power converter.Moreover, since the first contact and the second contact inserted between the power converter and the shared branch circuit are prohibited from being simultaneously turned on, the interlock means is provided. It is possible to reliably prevent 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.
[0009]
  Invention of Claim 2Then, in the invention of claim 1, the interconnection breaker is inserted in the electric circuit between the power converter and the disconnection switch, and the shared branch circuit is connected to the electric circuit between the interconnection breaker and the disconnection switch. Supply power to the load.
  According to this configurationEven if the interconnection breaker is turned off, it is possible to supply power to the shared branch circuit unless system separation is performed by the disconnection switch.
[0010]
  Invention of Claim 3Then, in the invention of claim 1, the switching switch selects a state where the shared branch circuit is connected to the main line and a state where it is connected to the power converter.
  According to this configuration,Since the shared branch circuit is selectively connected to one of the main line and the power converter, if the shared branch circuit is connected to the main line with a switching switch during maintenance of the power converter or solar cell, commercial power Can supply power to the shared branch circuit.
[0011]
The invention according to claim 4 is the invention according to claim 3, wherein the disconnecting switch and the switching switch are combined with relays each having two normally open contacts. According to this configuration, since the disconnection switch and the switching switch are configured only by relays each having two normally open contacts, the disconnection switch and the switching switch are configured only by relatively inexpensive relays. In addition, the number of parts can be reduced, and as a result, the overall cost can be reduced.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
The basic configuration of this embodiment is the same as the conventional configuration shown in FIG. 8, but the position of the interconnection breaker 21 is different as shown in FIG.
That is, disconnection switches 22a and 22b are connected to the trunk line Lm connected to the commercial power supply AC via the limiter 11 and the main breaker 12, and the interconnection breaker is connected between the disconnection switch 22b and the power converter 23. 21 is inserted. The shared branch circuit Lc is connected to the electric circuit between the disconnecting switch 22b and the interconnection breaker 21 via the shared branch breaker 24. The power converter 23 converts the direct current output of the solar battery 20 into alternating current similar to the commercial power supply AC, and has an inverter circuit as a main configuration. A plurality of branch circuits Lb are connected to the trunk line Lm between the main breaker 12 and the interconnection breaker 21 via the branch breakers 13, respectively. Furthermore, the power converter 23 is disposed 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.
[0014]
The grid interconnection protection device 25 detects an abnormality or a power failure based on the output of the sensor 27 inserted between the grid breaker 21 and the disconnect switches 22a and 22b. The sensor 27 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 current and voltage to the grid interconnection protection device 25, the system 27 The interconnection protection device 25 detects voltage fluctuations and frequency fluctuations, and disconnects the disconnect switches 22a and 22b if they are abnormal. Further, it is possible to detect a power failure of the commercial power supply AC based on changes in voltage and current.
[0015]
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 grid connection and to output an alternating current of 100 V at the time of system separation. Whether the system interconnection state or the system separation state is instructed by a notification signal from the system interconnection protection device 25. Further, the power converter 23 divides the output equally and connects the divided midpoint to the neutral line of the trunk line Lm at the time of grid connection. The reason why the output voltage of the power converter 23 is switched between system interconnection and system separation is to secure current capacity by lowering the output voltage because only the solar battery 20 is a power source during system separation. Thus, since the output voltage of the power converter 23 changes between the grid connection and the grid separation, in order not to change the line voltage of the shared branch circuit Lc between the grid connection and the grid separation, Means for switching the connection relationship between the power converter 23 and the shared branch circuit Lc is necessary. Therefore, three-pole contact r₁₁~ R₁₃Switching switch 29a and a two-pole contact r_{twenty one}, R_{twenty two}Is provided between the power converter 23 and the shared branch breaker 24. Here, the disconnection switches 22a and 22b and the switching switches 29a and 29b are configured by electromagnetic relays.
[0016]
Contact r of switching switch 29a₁₁~ R₁₃And contact r of the switching switch 29b_{twenty one}, R_{twenty two}Are controlled by a switching signal from the power converter 23 so that they are not turned on at the same time. The switching switch 29a has a contact r between the three wires from the power converter 23 and the three wires from the disconnect switch 22b.₁₁~ R₁₃All contact points r₁₁~ R₁₃Is inserted in the same circuit. Here, in FIG. 1, output lines from the power converter 23 are referred to as a line, b line, and c line from the top. One contact r of the switching switch 29b_{twenty two}Is the contact r of the switching switch 29a.₁₁~ R₁₃Of the contacts r inserted into the c-line₁₃Connected in parallel. Further, the other contact r of the switching switch 29b._{twenty one}Is the contact r of the switching switch 29a.₁₁~ R₁₃Of the contact r inserted in the a line₁₁One end is connected between the power converter 23 and the power converter 23, and the contact r inserted in the b line₁₂And the other end of the common branch breaker 24 are connected.
[0017]
In short, the shared branch breaker 24 is connected to one power line and the neutral line of the trunk line Lm at the time of grid connection, and the line voltage between the a line and the c line becomes 100V at the time of system separation. The switching switch 29b has a contact r between the a line and the c line and the common branch breaker 24._{twenty one}, R_{twenty two}When the system is connected, the line voltage between the a line and the c line becomes 200 V. Therefore, the switching switch 29a has a contact r between the b line and the c line and the shared branch breaker 24.₁₂, R₁₃Is inserted. In other words, the shared branch breaker 24 is connected to the b line and the c line at the time of system interconnection, and is connected to the a line and the c line at the time of system separation, and one end of the shared branch breaker 24 is connected to the grid connection. When the system is separated, it must be selectively connected to one of the a line and the b line. That is, the contact r of the switching switch 29a.₁₂And contact r of the switching switch 29b_{twenty one}It must be prohibited to turn on at the same time. Suppose both contacts r₁₂, R_{twenty one}If both are turned on at the same time, a problem arises that the a-line and the b-line are short-circuited.
[0018]
Both switching switches 29a and 29b have contact r₁₁~ R₁₃, R_{twenty one}, R_{twenty two}Are all a contacts (normally open contacts) and are turned off if there is no switching signal from the power converter 23. Contact r₁₂And contact r_{twenty one}Are not simultaneously turned on, the contact r of the switching switch 29a is connected at the time of grid connection.₁₁~ 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. In addition, when the system is separated, the contact r₁₁~ R₁₃Turns off and contact r_{twenty one}, R_{twenty two}Is turned on. That is, the b line and the c line of the power converter 23 are connected to the shared branch circuit Lc at the time of system interconnection, and the a line and the c line of the power converter 23 are connected to the shared branch circuit Lc at the time of system separation. At the time of grid connection, the voltage between the a line and the c line is 200V, and the voltage divided by two is the voltage between the b line and the c line, so that a voltage of 100V is applied to the shared branch circuit Lc. When the system is separated, the voltage between the a line and the c line is 100 V, and this is applied to the shared branch circuit Lc. In this way, 100 V can be applied to the shared branch circuit Lc regardless of whether the system is connected or disconnected, and the current capacity is reduced by reducing the output voltage of the power converter 23 during system isolation. It can be secured.
[0019]
As described above, the disconnection switches 22a and 22b are shut off at the time of an abnormality or a power failure, and the supply of power from the commercial power supply AC to the shared branch circuit Lc is stopped, but the power converter 23 supplies the shared branch circuit Lc. Electric power can be supplied. On the other hand, when no abnormality or power failure is detected in the grid interconnection protection device 25 that monitors the output of the sensor 27, 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 failure. give. At the same time, the disconnection switches 22a and 22b are instructed to connect to the grid to turn on the contacts. When the power converter 23 receives a notification signal for notifying abnormality or cancellation of the power failure, 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}Turn off. This switching operation is performed automatically.
[0020]
In the above configuration, in order to perform maintenance of the power converter 23 and the solar cell 20, the interconnection breaker 21 is turned off and the power converter 23 is disconnected from the commercial power source AC. At this time, a breaker (not shown) provided between the power converter 23 and the solar cell 20 is also turned off. In the conventional configuration, when the interconnection breaker 21 is turned off, power cannot be supplied to the shared branch circuit Lc. However, in this embodiment, the disconnect switches 22a and 22b are turned on if there is no abnormality or power failure. Since electric power from the commercial power supply AC is supplied to the shared branch circuit Lc, it is possible to supply electric power to the shared branch circuit Lc even during maintenance of the power converter 23 and the solar battery 20.
[0021]
By the way, in order to reliably prevent the contacts of both switching switches 29a and 29b from being turned on simultaneously, it is desirable to interlock the contacts of both switching switches 29a and 29b. As the interlock, an electrical interlock based on a circuit configuration and a mechanical interlock based on a contact configuration are considered.
In order to perform the electrical interlock, for example, a configuration as shown in FIG. In this configuration, an electromagnetic relay having two a contacts (normally open contacts) is used as the switching switch 29b, system separation is performed by the disconnecting switches 22a and 22b, and the contact of the switching switch 29a. r₁₁~ R₁₃When is turned off, the drive coil Cb of the switching switch 29b is energized. That is, the auxiliary contact r which is the b contact (normally closed contact) on each of the disconnection switches 22a and 22b and the switching switch 29a.₃₁~ R₃₃These auxiliary contacts r₃₁~ R₃₃And a switching signal to the series circuit of the switching coil 29b and the drive coil Cb of the switching switch 29b,_{twenty one}, R_{twenty two}It opens and closes. The disconnect switches 22a and 22b and the switching switch 29a are auxiliary contacts r.₃₁~ R₃₃Except for, all the contacts are a-contacts.
[0022]
The disconnecting switches 22a and 22b are connected to the auxiliary contact r when the system is separated.₃₁, R₃₂At this time, a notification signal is given to the power converter 23 and the output voltage of the power converter 23 is switched to 100V. Further, when the switching switch 29a receives a notification signal from the grid connection protection device 25, the contact r of the switching switch 29a.₁₁~ R₁₃As a result, the auxiliary contact r₃₃Is turned on. That is, three auxiliary contacts r connected in series to the drive coil Cb₃₁~ R₃₃Are all turned on. Therefore, a switching signal is given to the coil Cb of the switching switch 29b, and the auxiliary contact r.₃₁~ R₃₃Is applied to the drive coil Cb through the contact r_{twenty one}, R_{twenty two}Is turned on. In the configuration of FIG. 2, the contact r of the switching switch 29a.₁₁~ R₁₃If is not off, auxiliary contact r₃₃Does not turn on, the contact r of the switching switch 29a₁₁~ R₁₃And contact r of the switching switch 29b_{twenty one}, R_{twenty two}Can be prevented from being turned on at the same time, and a short circuit between the a line and the b line can be prevented. Here, since the a-line and b-line must be prevented from being short-circuited at the time of grid connection, the auxiliary contact r of the disconnecting switches 22a, 22b.₃₁, R₃₃Is also connected in series to the drive coil Cb. That is, the contact point r inserted between the a line and the b line unless system separation is performed by the disconnecting switches 22a and 22b._{twenty one}As a result, the short circuit between the a line and the b line is surely prevented.
[0023]
On the other hand, in order to perform mechanical interlock, the configuration as shown in FIG. 3 may be employed. This is because the two a contacts r instead of the switching switches 29a and 29b.₄₁, R₄₂And one b contact r₄₃The switching switch 29 provided with is provided. Here, as is apparent from the operation of the circuit configuration shown in FIG. 1, the contact point r of both switching switches 29a and 29b.₁₃, R_{twenty two}Are not turned on at the same time, but there is no change in the electrical connection relationship regardless of which is turned on. Therefore, in the configuration shown in FIG.₁₃, R_{twenty two}The contact corresponding to is omitted. Further, the contact r of the switching switch 29a₁₁Is turned on when the grid is connected and turned off when the grid is separated.₄₁In addition, contact r₁₂And contact r_{twenty one}Contact r as a contact corresponding to₄₂, R₄₃Is provided. That is, both contact points r₄₂, R₄₃Is connected at one end to one end of the common branch breaker 24 and contact r₄₂Is connected to the b line of the output line of the power converter 23, and the contact r₄₃Is connected to the a line of the output lines of the power converter 23. Where contact r₁₂And contact r_{twenty one}Since it is prohibited to turn on at the same time, contact r₄₂A contact, contact r₄₃Interlocking is performed by using the b contact.
[0024]
(Embodiment 2)
In the first embodiment, the disconnection switches 22a and 22b and the switching switch 29a having three a contacts are used. However, in the present embodiment, the disconnection switches 22a and 22b are used as shown in FIG. And the switching switches 29a and 29b are configured only by electromagnetic relays having two a contacts. In the configuration of the first embodiment shown in FIG. 1, electromagnetic relays each having three a contacts are used as the disconnecting switches 22a and 22b, whereas in the present embodiment, two a contacts are provided. The electromagnetic relay is used, and according to the guidelines, two contacts are provided between the two systems that perform system interconnection. Therefore, the two lines connected to the shared branch circuit Lc of the trunk line Lm are connected to the two lines. By inserting two contact points of each of the column switches 22a and 22b, the guideline can be satisfied for two of the three wires.
[0025]
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 an attempt is made to configure this with an electromagnetic relay having two a contacts, two sets of electromagnetic contacts A relay is required. Therefore, two switching switches 29a that are simultaneously turned on / off₁29a₂Of the output line of the power converter 23, two switching switches 29a₁29a₂Contact point r₁₁₁, R₁₁₂Are inserted in series, and each switch 29a₁29a₂Remaining contact point r₁₂₁, R₁₂₂Are inserted into b-line and c-line, respectively. With this configuration, the switching switch 29a is also provided for one line in which the contacts of the disconnect switches 22a and 22b are not inserted.₁29a₂2 contacts r₁₁₁, R₁₁₂Will be inserted and the guideline will be satisfied.
[0026]
By adopting the contact configuration as described above, only the electromagnetic relay having two a contacts can be satisfied while satisfying the guideline that two contacts are inserted into the electric circuit connecting the two systems for grid connection. Compared with the case of using a special electromagnetic relay having three a contacts, the cost can be reduced. Also, two disconnection switches 22a and 22b and two switching switches 29a₁29a₂Are simultaneously turned on and off, the contact point control is the same as in the first embodiment shown in FIG.
[0027]
  If only the guideline is satisfied, as shown in FIG. 5, with respect to the configuration of the first embodiment shown in FIG. 1, only one disconnecting switch 22a is an electromagnetic having two a contacts. You may comprise by a relay. Other configurations and operations are the same as those of the first embodiment.
  (Reference example)
  In the first embodiment, the output voltage of the power converter 23 is changed between system interconnection and system separation.This exampleIs the one that does not change the output voltage of the power converter 23 between system interconnection and system separation. Such a configuration can be adopted when the generated power in the solar cell 20 has a sufficient margin for the power consumption of the load connected to the shared branch circuit Lc, and the a line of the power converter 23 is used. The shared branch circuits Lca and Lcb are connected between the line b and the line b and the line b and the line c via the shared branch breakers 24a and 24b, respectively. As shown in FIG.This exampleSince the switching switches 29a and 29b are not required in this configuration, the configuration of the contacts is simplified. Since there are two shared branch circuits Lca and Lcb, each shared branch circuit is used to suppress fluctuations in the output voltage of the power converter 23 due to a load connected to both the shared branch circuits Lca and Lcb. Voltage control is individually performed for each output line connected to Lca and Lcb. Other configurations and operations are the same as those of the first embodiment.
[0028]
  (Embodiment 3)
  In this embodiment, as shown in FIG. 7, a disconnecting switch 22 is inserted between the interconnection breaker 21 and the power converter 23 as in the conventional configuration. Here, since only one disconnection switch 22 is provided, two contacts are inserted in series between the main line Lm and the power converter 23 by the contact of the switching switch 29c in order to satisfy the guideline. It is. In the present embodiment, a configuration is adopted in which the shared branch circuit Lc is selectively connected to the trunk line Lm and the output line of the power converter 23 via the switching switch 29d. Further, a branch switch 14 having a b contact is connected between the switching switch 29d and the main line Lm. The switching switch 29d and the branch switch 14 are electromagnetic relays, and the output voltage of the power converter 23 is applied to the drive coils Cd and Ce through the switching switch 29c.
[0029]
The switching switch 29c realizes the functions of the two switching switches 29a and 29b in the first embodiment by one electromagnetic relay. The switching switch 29c includes two c contacts and one a contact. Each of the c contacts selects whether the a line and the c line among the output lines of the power converter 23 are connected to the disconnecting switch 22 or the switching switch 29d. Further, the a contact provided in the switching switch 29c selects whether or not the b line of the output lines of the power converter 23 is connected to the disconnect switch 22. That is, the interlock is performed by using such a switching switch 29c. In the switching switch 29c, the normally open side of the contact c is connected to the disconnection switch 22, and if there is no abnormality or power failure, the output line of the power converter 23 is connected to the trunk line via the disconnection switch 22 and the interconnection breaker 21. Connected to Lm. At this time, since the voltage from the power converter 23 is not applied to the drive coils Cd and Ce, the contact of the switching switch 29d is connected to the normally closed side, and since the branch switch 14 is also the b contact, the shared branch circuit Lc Is connected to the trunk line Lc.
[0030]
On the other hand, when the grid connection protection device 25 detects an abnormality or a power failure and the system disconnection by the disconnection switch 22 is performed, the power converter 23 receives the notification signal from the grid connection protection device 25 to switch the switch 29c. Invert the contact state. That is, the power converter 23 is connected to the switching switch 29d. At this time, the output voltage of the power converter 23 (voltage between the a line and the c line) is applied to the drive coils Cd and Ce, and the shared branch circuit Lc is connected to the power converter via the on / off switches 29c and 29d. 23. At this time, the trunk line Lm and the switching switch 29d are disconnected by the branch switch 14.
[0031]
As is clear from the above description, even in the configuration of this embodiment, when the maintenance of the power converter 23 and the solar battery 20 is performed, the interconnection breaker 21 may be turned off. At this time, the shared branch circuit Lc has a branch switch. 14 and the switching switch 29d, the power is supplied from the trunk line Lm, so that the power converter 23 and the solar cell 24 can be easily maintained. Other configurations and operations are the same as those of the first embodiment. In this embodiment, in addition to the limiter 11, the main breaker 12, the branch breaker 13, and the interconnection breaker 21, the branch switch 14, the switching switch 29d, and the common branch breaker 24 are also housed in the distribution board 1.
[0032]
【The invention's effect】
  The invention of claim 1 is inserted between a solar cell, a power converter that converts direct current output from the solar cell into alternating current, and a main line connected to a commercial power source and the power converter.Disconnection switch and interconnection breaker,System interconnection protection device that drives the disconnect switch to isolate the system when an abnormality or commercial power failure is detectedAnd load from the electric circuit between the main line and the interconnection breaker at least during grid connectionShared branch circuit that supplies power toAnd a switching switch provided between the power converter and the shared branch circuit, and the power converter is configured to lower the output voltage from the grid connection when the system is separated. A first contact for connecting the first output line of the power converter to the shared branch circuit at the time of system separation, and a second of the power converter for dividing and outputting the output voltage of the first output line of the power converter There are provided a second contact for connecting the output line to the shared branch circuit at the time of grid connection, and an interlock means for interlocking so as to prevent the first contact and the second contact from being simultaneously turned on. Has beenHowever, when performing maintenance of the power converter, the power breaker is turned off and the power converter is disconnected from the main line.At least during grid connectionSince the shared branch circuit is connected to the circuit on the commercial power supply side for the interconnection breaker,If grid connectionTurn off the interconnect breakerEven sharedThere is an advantage that power can be supplied to the branch circuit, and power can be supplied to the load connected to the shared branch circuit even during the maintenance of the solar cell and the power converter.Moreover, since the first contact and the second contact inserted between the power converter and the shared branch circuit are prohibited from being simultaneously turned on, the interlock means is provided. There is an advantage that the second contact can be surely prevented from being turned on at the same time, and a short circuit between the two output lines of the power converter can be prevented.
[0033]
  Invention of Claim 2As shown in Fig. 2, the connection breaker is inserted into the electric circuit between the power converter and the disconnection switch, and the shared branch circuit supplies power to the load from the electric circuit between the connection breaker and the disconnection switch. Then, even if the interconnection breaker is turned off, there is an advantage that it is possible to supply power to the shared branch circuit unless system separation by the disconnection switch is performed.
[0034]
  Invention of Claim 3As in the case where the switching switch selects the state where the shared branch circuit is connected to the main line and the state where it is connected to the power converter, the common branch circuit is selectively connected to one of the main line and the power converter. Therefore, there is an advantage that power can be supplied from a commercial power source to the shared branch circuit if the shared branch circuit is connected to the main line by a switching switch during maintenance of the power converter and the solar cell.
[0035]
As in the invention of claim 4, in the case where the disconnection switch and the switching switch are configured by combining the relays each having two normally open contacts, only the relay having two normally open contacts is used. Since the disconnecting switch and the switching switch are configured, it is possible to configure the disconnecting switch and the switching switch only with a relatively inexpensive relay, and it is possible to reduce the number of parts, resulting in the overall There is an advantage that the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a circuit diagram illustrating a first embodiment.
FIG. 2 is a main part circuit diagram showing a modification of the above.
FIG. 3 is a main part circuit diagram showing another modification of the above.
FIG. 4 is a circuit diagram showing a second embodiment.
[Figure 5]Another configuration as aboveFIG.
[Fig. 6]Reference exampleFIG.
[Fig. 7]Embodiment 3FIG.
FIG. 8 is a circuit diagram showing a conventional example.
[Explanation of symbols]
  14 Branch switch
  20 Solar cell
  22a, 22b Disconnect switch
  23 Power converter
  25 System interconnection protection device
  29a-29d switching switch
  AC commercial power
  Lm main line
  Lc shared branch circuit

Claims (4)

A solar cell, a power converter that converts direct current output from the solar cell into alternating current, a disconnect switch and a connection breaker inserted between the main line connected to the commercial power source and the power converter , an abnormality And a grid connection protection device that separates the system by detecting the disconnection switch when a power failure is detected in the commercial power supply, and at least a power supply to the load from the power line between the main line and the circuit breaker at the time of system connection A branch circuit and a switching switch provided between the power converter and the shared branch circuit are configured so that when the system is separated, the power converter lowers the output voltage than when the system is connected. Is a first contact for connecting the first output line of the power converter to the shared branch circuit at the time of system separation, and the first of the power converter for dividing and outputting the output voltage of the first output line of the power converter. Connect the 2 output lines to the shared branch circuit during grid connection Photovoltaic systems, wherein the second contact, that the first contact and the second contact is interlocked with means for interlocking is provided so as to prevent the turn on at the same time. The interconnection breaker is inserted into the electric circuit between the power converter and the disconnection switch, and the shared branch circuit supplies power to the load from the electric circuit between the interconnection breaker and the disconnection switch. The solar power generation system according to claim 1. 2. The photovoltaic power generation system according to claim 1, wherein the switching switch selects a state in which the shared branch circuit is connected to the main line and a state in which the common branch circuit is connected to the power converter . Solar power system according to claim 1, characterized in that the disconnecting switch and the diverter switch is constructed by combining a relay with a normally open contact of two each.

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