WO2013015097A1

WO2013015097A1 - Electricity storage system and system interconnection system using same

Info

Publication number: WO2013015097A1
Application number: PCT/JP2012/067344
Authority: WO
Inventors: 俊之平田; 紘一郎江阪; 大祐福田
Original assignee: 三洋電機株式会社
Priority date: 2011-07-22
Filing date: 2012-07-06
Publication date: 2013-01-31
Also published as: JPWO2013015097A1; JP6043967B2

Abstract

[Problem] To provide an electricity storage system in which an existing system interconnection device can be used to build a solar power generation system that uses a storage cell and a solar cell jointly. [Solution] An electricity storage system provided with a storage cell (30), for supplying the output of the storage cell (30) to a system interconnection device (2) for converting the output power of a solar cell (1) to alternating-current power and outputting to a commercial power system (5); the electricity storage system characterized in comprising: a charging circuit (31) for charging the storage cell (30); a line (7) for connecting the solar cell (1) and the system interconnection device (2); a discharging circuit (31) for discharging from the storage cell (30) to the system interconnection device (2), the discharging circuit being connected to the storage cell (30); and a power outage detection circuit (33) for detecting a power outage in the commercial power system (5); discharging from the storage cell (30) to the system interconnection device (2) being enabled when a power outage is detected by the power outage detection circuit (33).

Description

[Supplement based on Rule 26.07.2012] Power storage system and grid interconnection system using it

This invention relates to the electrical storage system connected to the line which connects a solar cell and a grid connection apparatus.

Recently, a solar power generation system having a solar cell and a grid interconnection device that converts DC power output from the solar cell into AC power and superimposes it on a commercial power system is provided. Such a grid-connected device of a photovoltaic power generation system can perform a self-sustained operation in which a solar cell is disconnected from a commercial power system and a power output from the solar cell is supplied to a load when a power failure occurs in the commercial power system. It has become.

The grid interconnection device cannot operate independently when a power failure occurs while the solar cell cannot output DC power (for example, at night). For this reason, a grid interconnection device is also proposed in which power from the storage battery can be input to the grid interconnection device, and in the event of a power failure, the power from the storage battery can be converted into AC power and supplied to the load. Yes. (Patent Document 1).
JP 2008-54473 A

In the grid interconnection device described in Patent Document 1, a storage battery is connected to a line connecting the solar battery and the inverter circuit, and a charge / discharge circuit for charging and discharging the storage battery is arranged between the storage battery and the line. ing. Thus, when the grid interconnection device detects that a power failure has occurred, the grid interconnection device gives a discharge command to the charge / discharge circuit, and supplies power from the storage battery to the inverter circuit. Thereby, even at night when the solar battery does not generate electricity, the storage battery becomes a power source, and the grid interconnection device can perform a self-sustained operation.

However, as described above, it is sufficient that the grid interconnection device has a function that can be used in combination with the solar battery and the storage battery, but many grid interconnection devices that do not have such a function are also provided. In addition, even if a power storage system having a storage battery and a charge / discharge circuit is attached to a grid interconnection device that does not have such a function, a circuit for notifying the power storage system of a power failure is separately required for the grid interconnection device, After all, there is a problem that a dedicated grid interconnection device is required.

The present invention has been made in view of such a point, and provides a power storage system that can assemble a solar power generation system that uses both a storage battery and a solar battery even when an existing grid interconnection device is used. .

In order to achieve the above object, the power storage system of the present invention comprises a storage battery, wherein the storage battery is connected to a grid interconnection device that converts the output power of the solar battery into alternating current power and outputs it to the commercial power system. A charging circuit for charging the storage battery, a line connecting the solar battery and the grid interconnection device, and a discharge circuit connected between the storage battery and discharging from the storage battery to the grid interconnection device A power failure detection circuit for detecting a power failure in the commercial power system, and having a configuration that enables discharge from the storage battery to the grid interconnection device when the power failure is detected by the power failure detection circuit. Features.

In this way, the power storage system supplies the DC power output from the storage battery to the grid interconnection device without receiving a power failure signal from the grid interconnection device in the event of a power failure. Then, the grid interconnection device receives this DC power, converts it to AC power, and can supply power to the load (becomes able to operate independently). In this manner, a solar power generation system that uses a storage battery and a solar battery in combination can be assembled even if an existing grid interconnection device is used.

In the above-described invention, the power failure detection circuit has an open / close circuit that opens a contact piece when power is supplied from a commercial power system, detects that the open / close circuit is closed, and detects the closed circuit from the storage battery. It discharges to a system apparatus, It is characterized by the above-mentioned.

In the above-described invention, the charging circuit and the discharging circuit are charging / discharging circuits that charge and discharge the storage battery via an insulating transformer.

In the above-mentioned invention, the charging circuit and the discharging circuit are configured by a charging / discharging circuit using a non-insulated bidirectional chopper circuit, and have a switch between the charging / discharging circuit and the line, When the power failure detection circuit detects feeding of the commercial power system, the switch is opened.

Further, in the above-described invention, when the grid interconnection device is operated independently, the terminal that outputs power, the commercial power system, and a load connected to the grid interconnection device or the output from the commercial power system A switching circuit that outputs any one of the electric power to the load is provided, and when a power failure is detected, output power of the grid interconnection device is output to the load.

Moreover, in the above-mentioned invention, when the power failure is detected by the power failure detection circuit and the output voltage of the solar battery is equal to or higher than a first predetermined value, the storage battery is charged by the charging circuit, and the power failure detection circuit causes the power failure to occur. And when the output voltage of the solar cell is less than a first predetermined value, the storage battery is discharged by the discharge circuit, the power failure detection circuit detects the feeding of the commercial power system, and the output of the solar cell When the voltage is equal to or higher than a second predetermined value, the charging circuit charges the storage battery, the power failure detection circuit detects the power supply of the commercial power system, and the output voltage of the solar battery is less than the second predetermined value. In some cases, the charging circuit and the discharging circuit are stopped.

In order to achieve the above object, the grid interconnection system of the present invention includes the grid interconnection device and the above-described power storage system.

According to the present invention, it is possible to provide a power storage system capable of assembling a solar power generation system that uses a storage battery and a solar battery in combination using an existing grid interconnection device.

It is a lineblock diagram showing photovoltaic power generation system 100 in a 1st embodiment. It is a lineblock diagram of system interconnection device 2 in a 1st embodiment. It is a block diagram of the electrical storage system 3 in 1st Embodiment. It is a perspective view of the electrical storage system 3 in 1st Embodiment. It is a block diagram which shows the solar energy power generation system 100 in 2nd Embodiment. It is a block diagram which shows the modification of the electrical storage system 3 in 2nd Embodiment. It is a perspective view of the electrical storage system 3 in 2nd Embodiment. It is a block diagram which shows the solar energy power generation system 100 in 3rd Embodiment. It is a figure which shows the operation | movement pattern of a gate block signal generation circuit.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram illustrating a photovoltaic power generation system 100 according to the first embodiment.

The solar power generation system 100 includes a solar cell 1, a grid interconnection device 2, and a power storage system 3.

The solar cell 1 changes its power generation amount according to the amount of solar radiation. The solar cell 1 includes a plurality of single cell solar cells, and is configured by connecting a plurality of single cell solar cells in series and / or in parallel. For example, the rated voltage is 250 V, 300 V, output 2.4 Kw, output 4.8 Kw, and the like.

The grid interconnection device 2 receives the DC power output from the solar cell 1, converts the input DC power into AC power, and outputs the AC power to the commercial power grid 5 via the grid interconnection relay 21 (linkage). System operation). Further, when the commercial power system 5 is out of power, the DC power output from the solar cell 1 and / or the power storage system 3 is input, the input DC power is converted into AC power, and this AC power is converted to a relay 22 for independent operation. Is supplied to the load 6 through (stand-alone operation). The grid interconnection device 2 has a function of automatically switching between grid operation and independent operation by detecting a power failure in the commercial power system 5. It should be noted that the switching between the grid operation and the independent operation may be performed manually after the grid interconnection device 2 detects a power failure and stops. The block diagram of the grid connection apparatus 2 in 1st Embodiment is shown in FIG.

The grid interconnection device 2 includes a booster circuit 23, an inverter circuit 24, a filter circuit 25, a grid interconnection control circuit 26, a grid interconnection relay 21, and a self-sustained operation relay 22.

As shown in FIG. 2, the booster circuit 23 is composed of a booster chopper circuit having a reactor, a switch element, and a diode. By controlling the duty ratio of the switch element, the DC power input to the grid interconnection device 2 is obtained. Boost to desired voltage.

The inverter circuit 24 is composed of a plurality of switch elements connected in a full bridge. By performing PWM control of this switch element, the DC power output from the booster circuit 23 is converted into AC power. The inverter circuit 24 outputs the converted AC power to the filter circuit 25.

The filter circuit 25 includes two reactors and a capacitor, and removes a high-frequency component of AC power output from the inverter circuit 24. The AC power from which the high frequency component has been removed is output to the commercial power system via the grid interconnection relay 21 or to the load 6 via the autonomous operation relay 22.

The grid interconnection control circuit 26 controls operations of the booster circuit 23, the inverter circuit 24, the grid interconnection relay 21, and the independent operation relay 22. The grid interconnection control circuit 26 determines whether or not the commercial power system 5 has a power failure at the time of startup. When the commercial power system 5 has a power failure, the grid interconnection control circuit 26 opens the grid interconnection relay 21 and closes the autonomous operation relay 22 to perform autonomous operation. In addition, when the commercial power system 5 is supplying power, the grid interconnection control circuit 26 closes the grid interconnection relay 21 and opens the independent operation relay 22 to perform interconnection operation.

The power storage system 3 supplies power to the grid interconnection device 2 when the commercial power system 5 is out of power, and uses the output power of the solar cell 1 when the commercial power system 5 supplies power. Charge. FIG. 3 shows a configuration diagram of the power storage system 3 in the first embodiment. The perspective view of the electrical storage system 3 in 1st Embodiment is shown in FIG.

The power storage system 3 includes a storage battery 30, a charge / discharge circuit 31, a power storage system control circuit 32, and a power failure detection circuit 33. The storage battery 30, the charging / discharging circuit 31, and the electrical storage system control circuit 32 are accommodated in the housing 35a. The power failure detection circuit 33 is housed in a housing 35b different from the housing 35a, and is connected to the power storage system control circuit 32 in the housing 35a by a signal line 36.

The storage battery 30 is configured by using, for example, a lead storage battery and connecting cells in series and / or in parallel so that the rated voltage is 12 [V] to 240 [V].

The charging / discharging circuit 31 is configured to charge or discharge the storage battery 30 via the insulating transformer 31c. Specifically, two bridge circuits 31a and 31b in which a plurality of (four) switch elements (for example, an element such as an IGBT) in which diodes are connected in antiparallel are connected in a full bridge are connected to an insulating transformer 31c. Connected through. In addition, since the charge / discharge circuit 31 can perform both charge and discharge, it can be called a charge circuit or a discharge circuit.

The AC side of the bridge circuit 31a is connected to the insulation transformer 31c, and the DC side is connected to the line 7 connecting the solar cell 1 and the grid interconnection device 2. The line 7 and the charge / discharge circuit 31 are connected by a connection line 38. The AC side of the bridge circuit 31 b is connected to the insulating transformer 31 c, and the DC side is connected to the storage battery 30. When charging the storage battery 30, the switch element of the bridge circuit 31a is PWM-driven, and the switch element of the bridge circuit 31b is stopped (shut off) to operate as a diode rectifier circuit. Thereby, the output voltage from the solar cell 1 is stepped down to a voltage slightly higher than the rated output of the storage battery 30, and the storage battery 30 can be charged. Charging is performed by constant current charging until the voltage of the storage battery 30 reaches a predetermined voltage value, and is charged by constant voltage when the voltage of the storage battery 30 is higher than the predetermined voltage value.

When discharging the storage battery 30, the switch element of the bridge circuit 31b is PWM-driven, and the switch element of the bridge circuit 31a is stopped (cut off) to operate as a diode rectifier circuit. Thereby, the output voltage from the storage battery 30 is boosted to about the operating voltage of the solar battery 1 and supplied to the grid interconnection device 2.

An electromagnetic relay is used for the power failure detection circuit 33. An AC relay that receives driving power from the commercial power system 5 is used as the electromagnetic relay. The AC relay is installed near the distribution board that distributes the power of the commercial power system 5 (the casing 35b is arranged near the distribution board). The AC relay is connected to the commercial power system 5 by wiring from the distribution board and supplied with AC power. The AC relay opens the contact piece when power is supplied from the commercial power system 5, and closes the contact piece when power is not supplied. The contact piece is connected to the power storage system control circuit 32 via the signal line 36, and the power storage system control circuit 32 detects a power failure by detecting a current flowing when the contact piece is closed. Conversely, the power storage system control circuit 32 detects that the commercial power system 5 supplies power when no current flows.

The power storage system control circuit 32 controls the operation of the charge / discharge circuit 31. The operation of the charging / discharging circuit 31 is as follows: (1) When the commercial power system is out of power and the solar cell is sufficiently generating power, (2) The commercial power system is out of power and the solar cell is sufficiently When power is not generated, (3) When the commercial power system is feeding and the solar cell is generating power, (4) When the commercial power system is feeding and the solar cell is not generating power Divided into four ways.

The case of (1) will be described. In the case of (1), the commercial power system 5 is in a state where the solar battery can sufficiently generate power, supply power to the load 6 for autonomous operation, and use the power for charging the storage battery during a power failure. is there. The power storage system control circuit 32 detects a power failure of the commercial power system 5 by the power failure detection circuit 33, and the voltage of the connection line 38 (output voltage of the solar cell) is equal to or higher than a first predetermined value (for example, the load 6 for autonomous operation). This value is determined when the value is sufficient to supply power. In this case, the power storage system control circuit 32 instructs the charge / discharge circuit 31 to charge the solar battery 1 to the storage battery 30.

The case of (2) will be described. In the case of (2), while the commercial power system 5 is out of power, the solar cell is generating power, but the power supply to the load 6 for independent operation is insufficient, and supply of load power using the discharge of the storage battery It is in a state to perform. The power storage system control circuit 32 detects the power failure of the commercial power system 5 by the power failure detection circuit 33, and the voltage of the connection line 38 (the output voltage of the solar cell) is less than a first predetermined value (for example, the load 6 for autonomous operation). This value is determined when the value is sufficient to supply power. In this case, the power storage system control circuit 32 monitors the current flowing between the storage battery 30 and the charge / discharge circuit, and performs discharge by current control so that the current becomes a predetermined current value.

The case of (3) will be described. In the case of (3), the commercial power system 5 is supplying power, and the solar battery 1 is in a state where the storage battery 30 can be charged. The power storage system control circuit 32 detects the power supply of the commercial power system 5 by the power failure detection circuit 33, and the voltage of the connection line 38 (the output voltage of the solar battery) is equal to or higher than a second predetermined value (for example, the rated voltage of the storage battery 30). In some cases, this state is determined. In this case, the power storage system control circuit 32 instructs the charge / discharge circuit 31 to charge the solar battery 1 to the storage battery 30.

The case of (4) will be described. In the case of (4), while the commercial power system 5 is supplying power, the solar battery 1 cannot charge the storage battery 30. The power storage system control circuit 32 detects the power supply of the commercial power system 5 by the power failure detection circuit 33 and the voltage of the connection line 38 (output voltage of the solar battery) is less than a second predetermined value (for example, the rated voltage of the storage battery 30). In some cases, this state is determined. In this case, the power storage system control circuit 32 shuts off all the switch elements constituting the bridge circuit of the charge / discharge circuit 31 and stops the charge / discharge circuit 31.

Also, the first predetermined value may be set higher than the second predetermined value. In this way, charging is performed when the threshold value is higher than that during power supply during a power failure, and therefore, power supply with priority to the load 6 can be performed during a power failure.

The power storage system control circuit 32 is configured to perform protection control such as overcharge protection and overdischarge protection in addition to the control performed in the cases (1) to (4).

According to the first embodiment described above, the power storage system 3 detects a power failure by the power failure detection circuit 33 connected to the commercial power system 5 and supplies DC power from the storage battery 30 to the grid interconnection device 2. become. By doing in this way, the electrical storage system 3 supplies the direct current power which the storage battery 30 outputs to the grid connection apparatus 2, without receiving the signal of a power failure from the grid connection apparatus 2 at the time of a power failure. And the grid connection apparatus 2 receives this direct current power, converts it into alternating current power, and can supply electric power to the load 6 (becomes able to carry out a self-supporting operation). In this manner, a solar power generation system that uses a storage battery and a solar battery in combination can be assembled even if an existing grid interconnection device is used.

Moreover, since the charging / discharging circuit 31 performs charging and discharging of the storage battery 30 via an insulating transformer, the switching element of the charging / discharging circuit 31 is shut off (stopped) so as to be connected to the solar battery 1. Since the line 7 connecting the system device 2 and the storage battery 30 are disconnected, the commercial power system 5 supplies power, and the solar battery 1 is not generating power, the discharge from the storage battery 30 to the grid interconnection device 2 Can be prevented.

In addition, the charge / discharge circuit 31 discharges the storage battery 30 only when the commercial power system 5 has a power failure. As a result, only charging is performed when the commercial power system 5 is feeding, so that the storage battery 30 can be used with a charging capacity of almost 100% when the commercial power system 5 fails.

Further, the power failure detection circuit 33 is accommodated in a housing 35b separate from the housing 35a, and the power storage system control circuit 32 and the power failure detection circuit in the housing 35a are connected by a signal line 36. Thereby, the power failure detection circuit 33 can be arrange | positioned near the distribution board which distributes the electric power of the commercial power system 5, and the line which connects the commercial power system 5 and the power failure detection circuit 33 can be shortened. By shortening this line, disconnection of this line can be prevented and malfunction of the storage battery 30 due to disconnection can be prevented.

Further, since the power failure is detected when the AC relay contact piece is closed, even if the signal line 36 is disconnected, it is not determined that the power failure occurs, and the storage battery 30 is not discharged. Thereby, the unexpected discharge (discharge when the commercial power system 5 is feeding) of the storage battery 30 can be prevented. *

(Second Embodiment)
In the first embodiment, the charging / discharging circuit 31 that charges and discharges the storage battery 30 via an insulating transformer is adopted. However, in the second embodiment, a non-insulating bidirectional chopper is used for the charging / discharging circuit. Is adopted. Moreover, in 2nd Embodiment, it connects with the relay 22 for independent operation of the grid connection apparatus 2, and the commercial power grid 5, and according to the power failure and electric power feeding of the commercial power grid 5, the grid connection apparatus 2 of the grid connection apparatus 2 is The power storage system 3 is provided with a switching circuit that outputs power from the commercial power grid 5 to the load 6 during power feeding. About another structure, since the structure similar to 1st Embodiment can be used, description is abbreviate | omitted.

FIG. 5 is a configuration diagram showing the solar power generation system 100 according to the second embodiment. FIG. 6 is a configuration diagram illustrating a modified example of the power storage system 3 in the second embodiment. FIG. 7 is a perspective view of the power storage system 3 in the second embodiment.

As shown in FIG. 6, the charge / discharge circuit 31 d includes a plurality (two) of

switch elements

131 and 132, a reactor 133, a switch 134, and a diode 135 in which diodes are connected in reverse parallel. By opening and closing the switch element 131 at a predetermined duty ratio, the output voltage from the solar cell 1 is stepped down to a voltage slightly higher than the rated output of the storage battery 30, and the storage battery 30 can be charged. As in the first embodiment, the charging is constant current charging until the voltage of the storage battery 30 reaches a predetermined voltage value, and constant voltage charging is performed when the voltage of the storage battery 30 is greater than the predetermined voltage value.

When discharging the storage battery 30, the switch element 132 is opened and closed with a predetermined duty ratio. Thereby, the output voltage of the storage battery 30 is boosted to about the operating voltage of the solar battery 1 and supplied to the grid interconnection device 2.

The switch 134 and the diode 135 are connected in parallel, and the diode 135 is connected to flow a current from the charge / discharge circuit 31 to the storage battery 30. A parallel circuit of the switch 134 and the diode 135 is provided between the charge / discharge circuit 31 and the storage battery 30 (or may be provided between the charge / discharge circuit 31 and the line 7). When a non-insulated bidirectional chopper is used, when the solar cell 1 is not generating power, even though the switch element of the charge / discharge circuit 31 is shut off, a diode connected in reverse parallel to the switch element 131 is used. The storage battery 30 is discharged to the grid interconnection device 2.

The parallel circuit of the switch 134 and the diode 135 is for preventing this, and the switch 134 is opened when the commercial power system 5 is supplying power, and the switch 134 is closed and used in the event of a power failure. . Thereby, when the commercial power system 5 is supplying power and the solar cell 1 is not generating power, the switch 134 is opened, and discharge from the storage battery 30 to the grid interconnection device 2 can be prevented. In the case of a power failure, the switch 134 is closed to supply power from the storage battery 30 to the grid interconnection device 2.

The power storage system 3 includes a switching circuit 34 as shown in FIGS. As the switching circuit 34, a switch circuit that switches between two contacts is used. The switching circuit 34 is housed in the housing 35b shown in FIG. 7 together with the power failure detection circuit 33. The switching circuit 34 is connected to the autonomous operation relay 22 of the grid interconnection device 2, the commercial power system 5, and the load 6. The connection of the autonomous operation relay 22 and the load 6, and the commercial power system 5 and the load 6 are connected. Switch between connections.

When the switching circuit 34 connects the autonomous operation relay 22 and the load 6, output power when the grid interconnection device 2 performs autonomous operation can be supplied to the load. Further, when the switching circuit 34 connects the commercial power system 5 and the load 6, the power of the commercial power system 5 can be supplied to the load.

A connection line 39 is used for connection between the autonomous operation relay 22 and the switching circuit 34. The commercial power system 5 and the switching circuit 34 are connected by wiring from the distribution board. The switching circuit 34 is connected to the load by using an outlet 37 provided in the housing 35b so that a household load can be easily connected.

The power storage system control circuit 32 switches the connection of the switching circuit 34 in addition to the control described in the first embodiment. When the power storage system control circuit 32 detects a power failure, the power storage system control circuit 32 connects the autonomous operation relay 22 and the load 6, and when the power failure is not detected (the commercial power system 5 is supplying power) The power system 5 and the load 6 are connected. Thereby, at the time of a power failure of the commercial power system 5, the power that the grid interconnection device operates independently is supplied to the load 6, and the power supplied from the commercial power system 5 is supplied to the load 6 when the commercial power system 5 is fed.

Further, when the power storage system 3 having such a switching circuit 34 is connected to a grid interconnection device capable of automatic switching between interconnection operation and independent operation, it is possible to continue supplying power to the load 6 even if a power failure occurs. (It can be used like a UPS).

(Third embodiment)
In the first embodiment and the second embodiment, the operation of discharging and charging the normal storage battery has been described. However, the power storage system 3 performs the protection operation of the power storage system or the storage battery in addition to the normal operation. Can do. In the present embodiment, the protection operation of the power storage system 3 will be described.

FIG. 8 is a configuration diagram showing the solar power generation system 100 according to the third embodiment. The charge / discharge circuit 31 has a solar cell side circuit 31a on the solar cell side of the insulating transformer 31c. And the solar cell side circuit 31a has the 1st switch element 41 which charges by repeating conduction | electrical_connection / interruption | blocking periodically (PWM drive). Moreover, the charging / discharging circuit 31 has the storage battery side circuit 31b in the storage battery side of a solar cell. And the storage battery side circuit 31b has the 2nd switch element 42 which discharges by repeating conduction | electrical_connection / interruption | blocking periodically (PWM drive).

The solar cell side circuit 31 a is connected so as to bypass the first switch element 41 (for example, in parallel with the first switch element 41), and a first diode 44 that flows a current in a direction opposite to that of the first switch element 41. have. Further, the storage battery side circuit 31b is connected so as to bypass the second switch element 42 (for example, in parallel with the second switch element 42), and includes a second diode 45 that flows a current in the direction opposite to that of the second switch element 42. Have.

The power storage system 3 further includes a parallel circuit 130 in which a switch 134 and a third diode 135 are connected in parallel between the charge / discharge circuit 31 and the storage battery 30. Thus, in the power storage system 3, the first switch element 41 is PWM-driven, whereby a current flows through the first switch element 41, the second diode 45, and the third diode 135, and the storage battery 30 is charged. Further, the storage system 3 opens the switch 134 and PWM-drives the second switch element 41, whereby a current flows through the switch 134, the second switch element 42, and the first diode 44, so that the storage battery 30 Discharge. That is, charging is performed by bypassing the switch during charging, and discharging is performed through the switch during discharging.

In addition, the power storage system 3 is provided with a manual switch 40 on a power line connecting the line 7 and the charge / discharge circuit 31, and when the power storage system 3 is used, the manual switch 40 is closed and used. The power storage system 3 includes ground fault detection sensors CT1 and CT4 such as ZCT for detecting a ground fault, current sensors CT2 and CT3, and voltage sensors VS1 and VS2. Ground fault detection sensor CT1 is arrange | positioned between the line 7 and the charging / discharging circuit 31, and detects the ground fault in the meantime. The current sensor CT2 is disposed on the cathode side (storage battery side) of the third diode 135, and detects the charging current to the storage battery. The current sensor CT3 is disposed on the storage battery side of the switch 134 and detects a discharge current from the storage battery. The ground fault detection sensor CT4 is disposed between the parallel circuit 130 and the storage battery 30, and detects a ground fault therebetween. The voltage sensor VS1 is disposed on the solar cell 1 side of the charge / discharge circuit 31 and detects the voltage of the solar cell 1. The voltage sensor VS <b> 2 is connected to the storage battery 30 side of the charge / discharge circuit 31 and detects the voltage of the storage battery 30.

The outputs of these sensors CT1 to CT4 and voltage sensors VS1 and VS2 are input to the power storage system control circuit 32 and used when the power storage system 3 performs a protection operation.

The power storage system control circuit 32 includes a charge drive circuit 61 for driving the first switch element 41, a discharge drive circuit 62 for driving the second switch element 42, and a switch drive circuit for driving the switch 134. Have.

The charge drive circuit 61 inputs a gate block signal GB1 and a charge control signal S1, which will be described later, and drives the first switch element 41. The charge control signal S1 is a signal for driving the first switch element 41 in order to charge the storage battery 30 in normal operation. When the storage battery 30 is subjected to constant current charging or constant voltage charging, the charging current or charging voltage is set. A PWM signal created by feedback is used. When “Hi” is input as the gate block signal GB1, the first switch element 41 is cut off (so-called gate block) regardless of what signal is input to the charge control signal S1. The switch element is prohibited from being turned on (maintained in a cut-off state).

The discharge drive circuit 62 receives the discharge control signal S2 and drives the second switch element 42. The discharge control signal S2 is a signal for driving the second switch element 42 to discharge the storage battery 30 in a normal operation, and is generated by feeding back a discharge current and a charge voltage when discharging the storage battery 30. Use signals. When “Hi” is input as the gate block signal GB2, the transmission of the discharge control signal S2 is cut off, the second switch element 42 is cut off (so-called gate block), and the first switch element is always turned off. To do.

The power storage system control circuit 32 includes a PV undervoltage detection unit 51, a PV overvoltage detection unit 52, and a solar cell ground fault detection unit 53. In addition, the power storage system control circuit 32 includes a discharge overcurrent detection unit 54 that detects charging / discharging abnormality of the power storage system 3. The power storage system control circuit 32 includes a storage battery overcharge detection unit 56 that detects an abnormality in the storage battery 30, a storage battery overdischarge detection unit 57, and a storage battery ground fault detection unit 58.

The PV undervoltage detection unit 51 detects the voltage of the solar cell 1 with the voltage sensor VS1, and outputs a PV undervoltage signal SA1 according to the detected voltage. Specifically, when the voltage of the solar cell 1 is lower than a predetermined voltage value, it is determined that the voltage of the solar cell 1 is low and the storage battery 30 cannot be charged (abnormal), and the PV undervoltage signal SA1 is “Hi”. Is output. Further, when the voltage of the solar cell 1 is higher than a predetermined voltage value, it is determined that the voltage of the solar cell 1 is high and the storage battery 30 can be charged (normal), and “Low” is output as the PV undervoltage signal SA1. . Here, the predetermined voltage value is set such that the charge / discharge circuit 31 can determine that the storage battery 30 cannot be charged.

The PV overvoltage detection unit 51 detects the voltage of the solar cell 1 with the voltage sensor VS1, and outputs a PV undervoltage signal SA1 according to the detected voltage. Specifically, when the voltage of the solar cell 1 is higher than a predetermined voltage value, an abnormality of the solar cell 1 is detected, and “Hi” is output as the PV overvoltage signal SA2. When the voltage of the solar cell 1 is lower than a predetermined voltage value, the solar cell 1 is determined to be normal, and “Low” is output as the PV undervoltage signal SA1. Here, as the predetermined voltage value, a voltage value higher than a voltage (for example, a rated voltage or a prescribed maximum voltage) at which the solar cell 1 performs a normal operation is set.

The solar cell ground fault detector 53 detects the current flowing to the solar cell 1 side of the charge / discharge circuit 31 by the ground fault detection sensor CT1, and outputs a solar cell ground fault signal SA3 according to the detected current. Specifically, when the current detected by the ground fault detection sensor CT1 is higher than a predetermined current value, a ground fault (abnormality) of the solar battery is detected, and “Hi” is output as the solar battery ground fault signal SA3. To do. Further, when the current detected by the ground fault detection sensor CT1 is lower than a predetermined current value, it is determined that the solar battery 1 has no ground fault (normal), and “Low” is output as the solar battery ground fault signal SA3. . Here, the predetermined current value is set to a current value that does not flow when charging / discharging is normally performed by the charging / discharging circuit 31.

The discharge overcurrent detection unit 54 detects a current discharged from the storage battery 30 by the current sensor CT3, and outputs a discharge overcurrent signal SA4 according to the detected current. Specifically, when the current detected by the current sensor CT3 is higher than a predetermined current value, it is detected that the battery 30 is overdischarged (abnormal), and “Hi” is output as the discharge overcurrent signal SA4. To do. When the current detected by the current sensor CT3 is lower than a predetermined current value, it is detected as normal and “Low” is output as the discharge overcurrent signal SA4. Here, the predetermined current value is set to a current value higher than a current (for example, a rated discharge current or a maximum discharge current) that flows during normal discharge by the charge / discharge circuit 31.

The charging overcurrent detection unit 55 detects the current charged in the storage battery 30 by the current sensor CT2, and outputs the charging overcurrent signal SA5 according to the detected current. Specifically, when the current detected by the current sensor CT2 is higher than a predetermined current value, it is detected that the storage battery 30 is overcharged (abnormal), and “Hi” is output as the charge overcurrent signal SA5. To do. When the current detected by the current sensor CT2 is lower than a predetermined current value, it is detected as normal and “Low” is output as the charge overcurrent signal SA5. Here, as the predetermined current value, a current value higher than a current (for example, a rated charge current or a maximum charge current) that flows when charging is normally performed by the charge / discharge circuit 31 is set.

The storage battery overcharge detection unit 56 detects the voltage of the storage battery 30 with the voltage sensor VS2, and outputs a storage battery overcharge signal SA6 according to the detected voltage. Specifically, when the voltage detected by voltage sensor VS2 is higher than a predetermined voltage value, it is detected that storage battery 30 is overcharged, and “Hi” is output as storage battery overcharge detection signal SA6. Further, when the voltage detected by the voltage sensor VS2 is lower than a predetermined voltage value, it is detected that the storage battery 30 is normal, and “Low” is output as the storage battery overcharge detection signal SA6. Here, the predetermined voltage value will be described. The voltage (open voltage) of the storage battery 30 is high if it is high, and low if it is low, depending on the charge capacity (for example, in proportion). By determining the charging capacity at which the storage battery 30 operates, the operating voltage of the storage battery is defined, and when this operating voltage is exceeded, it can be determined that the battery is overcharged. Therefore, the upper limit of the operating voltage is preferably set to the predetermined voltage value.

The storage battery overdischarge detection unit 57 detects the voltage of the storage battery 30 by the voltage sensor VS2, and outputs a storage battery overdischarge signal SA7 according to the detected voltage. Specifically, when the voltage detected by the voltage sensor VS2 is lower than a predetermined voltage value, it is detected that the storage battery 30 is overdischarged, and “Hi” is output as the storage battery overdischarge detection signal SA7. Further, when the voltage detected by the voltage sensor VS2 is higher than a predetermined voltage value, it is detected that the storage battery 30 is normal, and “Low” is output as the storage battery overdischarge detection signal SA7. Here, the predetermined voltage value may be set to the lower limit of the operating voltage of the storage battery 30.

The storage battery ground fault detection unit 58 detects a current flowing to the storage battery 30 side of the charge / discharge circuit 31 by the ground fault detection sensor CT4 and outputs a storage battery ground fault signal SA8. Specifically, when the current detected by the ground fault detection sensor CT4 is higher than a predetermined current value, the ground fault (abnormality) of the storage battery 30 is detected, and “Hi” is output as the storage battery ground fault signal SA8. . Further, when the current detected by the ground fault detection sensor CT4 is lower than a predetermined current value, it is determined that the storage battery 30 has no ground fault (normal), and “Low” is output as the storage battery ground fault signal SA8. Here, the predetermined current value is set to a current value that does not flow when charging / discharging is normally performed by the charging / discharging circuit 31.

The output signals SA1 to SA8 are input to the gate block signal generation circuit 64, and the gate block signals GB1 and GB2 are output to the charge drive circuit 61 and the discharge drive circuit 62, respectively, according to the input signals. FIG. 9 is a diagram illustrating an operation pattern of the gate block signal generation circuit 64.

As shown in FIG. 9, when any “Hi” signal of the signals SA1, SA2, SA3, SA5, SA6, and SA8 is input to the gate block signal generation circuit 64, the gate block signal generation circuit 64 The gate block signal GB1 is generated and output to the charge driving circuit 61. When any one of the signals SA2, SA3, SA4, SA7, and SA8 is input to the gate block signal generation circuit 64, the gate block signal generation circuit 64 receives the “Hi” gate block signal GB2. It is generated and output to the discharge drive circuit 62.

Thereby, the abnormality of the solar cell 1, the storage battery 30, and the charge / discharge circuit 31 is judged, and when the abnormality is detected, the first switch element 41 or the second switch element 42 is gate-blocked. Specifically, when the solar cell 1 is insufficient in voltage, when the solar cell 1 is overvoltage, when the solar cell 1 is grounded, when the current flowing during charging is overcurrent, or when the storage battery is overcharged When the storage battery is grounded, the first switch element 41 is gate-blocked. Further, when the solar cell 1 is overvoltage, when the solar cell 1 is grounded, when the current flowing during discharge is overcurrent, when the storage battery 30 is overdischarged, or when the storage battery 30 is grounded The gate block of the second switch element 42 is performed.

The power storage system 3 includes a power failure detection unit 59, a discharge operation unit 60, a logical product circuit AN1, and a negative circuit NO1.

The power failure detection unit 59 outputs a “Hi” signal when the power failure detection circuit 33 detects a power failure of the commercial power system 5, and a “Low” signal when the power failure detection circuit 33 detects power supply of the commercial power system 5. Output to AN1.

The discharge operation unit 60 accepts discharge from the user. For example, a button for accepting the discharge of the storage battery 30 may be prepared, and the user may accept the discharge when the button is pressed. If the discharge operation unit 60 accepts discharge, the discharge operation unit 60 outputs a “Hi” signal to the AND circuit AN1 if the discharge operation unit 60 does not accept discharge.

The AND circuit AN1 outputs a “Hi” signal when the “Hi” signal is input from the discharge operation unit 60 and the power failure detection unit 59, and “Low” if any one of the signals is “Low”. Output a signal. The signal output from the AND circuit AN1 is input to the switch drive circuit 63 and the negative circuit NO1.

The switch driving circuit 63 closes the switch 134 when the “Hi” signal is input, and opens the switch 134 when the “Low” signal is input.

In the negative circuit NO1, the input signal is inverted and the discharge inhibition signal SA9 is output to the gate block signal generation circuit 64. That is, when the “Hi” signal is input to the negative circuit NO1, the “Low” signal is output as the discharge inhibition signal, and when the “Low” signal is input, the “Hi” signal is output as the discharge inhibition signal.

When the “Hi” discharge inhibition signal is input, the gate block signal generation circuit 64 generates a “Hi” gate block signal GB 2 and outputs the gate block signal GB 2 to the discharge drive circuit 62.

As a result, when the discharge operation unit 60 does not accept discharge or when the power failure detection circuit 33 detects feeding of the commercial power system 5, the second switch element 42 is gate-blocked and the switch 134 is opened. Thus, the discharge by the charge / discharge circuit 31 is prohibited twice. On the contrary, when the discharge operation unit 60 accepts the discharge and the power failure detection circuit 33 detects the power failure of the commercial power system 5, the second switch element 42 is released from the gate block and the switch 134. Is closed and discharging by the charge / discharge circuit 31 becomes possible.

As described above, according to the third embodiment, when there is an abnormality in the solar cell 1, the storage battery 30, or the charge / discharge circuit 31, the first switch element or the second switch element is gate-blocked. The charging / discharging operation of the charging / discharging circuit 31 is prohibited depending on the state, and the storage system 3 or the storage battery 30 can be protected.

Moreover, since the discharge of the storage battery 30 is blocked from the soft and hard surfaces by the gate block of the charging / discharging circuit 31 and the switch 134, the discharge of the storage battery 30 is not accidentally discharged and the self-supporting operation of the storage battery 30 is performed. A sufficient charging capacity can be secured.

In addition, the battery is charged by bypassing the switch when charging, and discharged through the switch when discharging. For this reason, it is not necessary to operate the switch 134 about the charging operation performed even when the commercial power system 5 is out of power or during power feeding, and can be easily executed only by the operation by software.

In the third embodiment, the first switch element 41 and the second switch element 42 are kept in the cutoff state by the gate block. However, the output of the control signals S1 and S2 is reduced (for example, set to zero) so as to be in the cutoff state. It may be kept.

In the third embodiment, the charge / discharge circuit 31 is expressed as shown in FIG. 8 for simplicity. However, in the charge / discharge circuit 31 in the first embodiment, the first switch element 41 is a switch element of the bridge circuit 31a. Corresponds to the first switch element 41, the second switch element 42 corresponds to the switch element of the bridge circuit 31b, respectively, and the first diode corresponds to the switch element of the bridge circuit 31a. It can be said that it corresponds to a diode provided in parallel, and the second diode corresponds to a diode provided in anti-parallel to the switch element of the bridge circuit 31b.

In the third embodiment, the parallel circuit 130 is expressed as shown in FIG. 8 for the sake of simplicity, but can be connected as shown in FIG. 4, for example.

In the third embodiment, the charge / discharge circuit 31 using the insulation transformer 31c has been described. However, for example, a charge / discharge circuit 31d as shown in FIG. 4 that does not use the insulation transformer 31c can also be used. In the case of FIG. 4, the first switch element 41 corresponds to the switch element 131, the second switch element corresponds to the switch element 132, and the first diode 44 is a diode provided in antiparallel with the first switch element. The second diode 45 corresponds to a diode provided in antiparallel with the second switch element.

As mentioned above, although one embodiment of the present invention was described, the above explanation is for making an understanding of the present invention easy, and does not limit the present invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof.

For example, in this embodiment, an electromagnetic relay that opens a contact piece when power is supplied from the commercial power system 5 is used to determine whether the commercial power system 5 is a power failure or power supply. Various circuits can be used as long as the circuit opens and closes the contact piece. For example, a photocoupler or the like may be used.

In addition, for example, the power failure detection circuit 33 uses an electromagnetic relay to open and close the contact piece to detect a power failure. However, the contact piece is opened and closed by using an open / close circuit such as a photocoupler. You may detect whether the electric power grid | system 5 is supplying electric power.

For example, in the present embodiment, an example in which a lead storage battery is used as the storage battery 30 has been shown, but a lithium ion battery, a nickel hydrogen battery, or the like can also be used.

Further, for example, in this embodiment, the charge / discharge circuits (insulation type) 31a to 31c using the insulation transformer and the bidirectional chopper 31d are described as the charge / discharge circuit 31, but various configurations can be used. For example, a charging circuit and a discharging circuit may be arranged in parallel. Further, the charging circuit and the discharging circuit may be set to either an insulating type or a non-insulating type.

Further, for example, in this embodiment, charging is performed from the solar battery 1, but it is also possible to charge using the commercial power system 5. In this case, the charging circuit and the discharging circuit are separated, the discharging circuit is disposed between the line 7 and the storage battery 30, and the charging circuit is disposed between the commercial power system 5 and the storage battery 30. By doing in this way, the storage battery 30 can be charged, without using the bidirectional | two-way grid connection apparatus 2 (dedicated grid connection apparatus).

Further, for example, in the present embodiment, the outlet 37 is provided in the housing 35b, but the outlet 37 is attached to a wall of a building and used by wiring from the switching circuit to the outlet 37 (for example, wiring from the inside of the wall). You may do it.

DESCRIPTION OF SYMBOLS 1 Solar cell 2 Grid connection apparatus 3 Power storage system 5 Commercial power grid 6 Load 7 Line 8 Link breaker 21 Grid connection relay 22 Self-sustained operation relay 23 Grid connection control circuit 24 Inverter circuit 25 Filter circuit 26 Grid connection System control circuit 30 Storage battery 31 Charge / discharge circuit 32 Storage system control circuit 33 Power failure detection circuit 34 Switching circuit 35 Housing 36 Signal line 37 Outlet 38 Connection line 39 Connection line 40 Manual switch 41 First switch element (charge switch element)
42 Second switch element (discharge switch element)
44 First diode 45 Second diode 48 Breaker 130 Parallel circuit 134 Switch 135 Third diode CT1 to CT4 Current sensor VS1, VS2 Voltage sensor

Claims

In a power storage system that includes a storage battery and supplies the output of the storage battery to a grid interconnection device that converts the output power of the solar battery into alternating current power and outputs it to a commercial power system,
A charging circuit for charging the storage battery;
A discharge circuit connected between the storage battery and a line connecting the solar battery and the grid interconnection device, and discharging from the storage battery to the grid interconnection device;
A power failure detection circuit for detecting a power failure in the commercial power system,
A power storage system comprising a configuration that enables discharge from the storage battery to the grid interconnection device when a power failure is detected by the power failure detection circuit.
The power failure detection circuit has an open / close circuit that opens a contact when power is supplied from a commercial power system,
2. The power storage system according to claim 1, wherein discharging from the storage battery to the grid interconnection device is performed by detecting that the open / close circuit is closed.
The power storage system according to claim 1 or 2, wherein the charging circuit and the discharging circuit are charging / discharging circuits that charge and discharge the storage battery via an insulating transformer.
The charging circuit and the discharging circuit are constituted by a charging / discharging circuit by a non-insulated bidirectional chopper circuit,
Having a switch between the charge / discharge circuit and the line, or between the charge / discharge circuit and the storage battery,
3. The power storage system according to claim 1, wherein the switch is opened when the power failure detection circuit detects feeding of the commercial power system. 4.
The grid interconnection device is connected to a terminal that outputs power when the grid interconnection device operates independently, the commercial power system, and a load, and either the grid interconnection device or the output power from the commercial power system is connected to the load. A switching circuit that outputs to
The power storage system according to any one of claims 1 to 4, wherein when a power failure is detected, output power of the grid interconnection device is output to the load.
When the power failure detection circuit detects a power failure and the output voltage of the solar battery is equal to or higher than a first predetermined value, the charging circuit charges the storage battery.
When the power failure detection circuit detects a power failure and the output voltage of the solar battery is less than a first predetermined value, the discharge circuit discharges the storage battery,
When the power failure detection circuit detects feeding of the commercial power system, and the output voltage of the solar battery is equal to or higher than a second predetermined value, the charging circuit charges the storage battery,
The power failure detection circuit detects power supply of the commercial power system, and stops the charging circuit and the discharging circuit when the output voltage of the solar battery is less than a second predetermined value. .
The charging circuit includes a first switch element that performs the charging by periodically repeating conduction / cutoff,
The discharge circuit includes a second switch element that performs the discharge by periodically repeating conduction / cutoff,
A first diode connected so as to bypass the first switch element and flowing a current in a direction opposite to the first switch element;
A second diode connected so as to bypass the second switch element and flowing a current in a direction opposite to the second switch element;
A parallel circuit in which a switch and a third diode are connected in parallel between the discharge circuit and the storage battery;
When charging, the first switch element, the second diode, and the third diode are charged with current flowing, and when discharging, the switch, the second switch element, and the first diode are charged. The power storage system according to claim 1, wherein a current flows through the battery and discharges the battery.
A discharge operation unit for receiving the discharge;
When the discharge operation unit does not accept the discharge, or when the power failure detection circuit detects feeding of the commercial power system, the second switch element is gate-blocked and the switch is opened. The power storage system according to claim 7, which is characterized by:
Determining an abnormality of the solar cell, the storage battery, the discharge circuit, and the charging circuit;
The power storage system according to claim 7 or 8, wherein when the abnormality is detected, the first switch element or the second switch element is gate-blocked.
In the case where the voltage of the solar battery is insufficient, the solar battery is overvoltage, the solar battery is grounded, the current flowing during charging is an overcurrent, the storage battery is overcharged, the storage battery The power storage system according to claim 9, wherein a gate block of the first switch element is performed when a ground fault occurs.
When the solar cell is overvoltage, when the solar cell is grounded, when the current flowing during the discharge is overcurrent, when the storage battery is overdischarged, when the storage battery is grounded The power storage system according to claim 9 or 10, wherein the gate block of the second switch element is performed.
A grid interconnection system comprising the grid interconnection device and the power storage system according to any one of claims 1 to 11.