JP6168854B2 - Grid interconnection device - Google Patents

Description

  The present invention relates to a grid interconnection device, and more particularly to an improvement of a grid interconnection device that supplies power to a load from a grid power source, a storage battery, and a power generation device.

  2. Description of the Related Art Conventionally, a grid interconnection device that can supply power to a load not only from a grid power supply but also from a storage battery and a solar battery is known. A solar cell that outputs DC power is connected to a system power supply and a load via an inverter device called a PV (Photo Voltaic) power conditioner. The storage battery is connected in parallel to the solar battery with respect to the DC input terminal of the PV power conditioner, is charged by the generated power of the solar battery, and backs up the power supply to the load at the time of power failure or instantaneous voltage drop.

  In such a grid interconnection device, since the solar cell and the storage battery are connected on the DC line, the output voltage of the solar cell is dominated by the voltage of the storage battery, and the solar cell cannot be generated with maximum efficiency. (For example, Patent Document 1).

  In the grid interconnection device, since the solar battery and the storage battery are both connected to the DC input terminal of the PV power conditioner, the output power of the storage battery and the generated power of the solar battery are separated on the AC line. In other words, it is impossible to measure only the power generated from the solar cell as AC power, and the power generated by the solar cell cannot be sold.

  Generally, an electric power company prohibits selling the output power of a storage battery to an electric power company in order to prevent the electric power of the storage battery charged using low-cost night electric power from being sold in the daytime. For this reason, in order to sell the power generated by the solar cell to an electric power company, it is necessary to measure only the output of the solar cell, distinct from the output of the storage battery. In addition, since the power measurement must be performed on the AC line, the grid interconnection device has a problem that the generated power of the solar cell cannot be sold.

  Furthermore, the conventional grid interconnection device is configured to stop the operation of the inverter device at the time of power failure of the system power supply and restart the operation at the time of power recovery (for example, Patent Document 2). Since power supply to the system side during a power failure of the system power supply is prohibited, it is necessary to stop the inverter device during the power failure. For this reason, although the storage battery can be charged using the output of the power generator, there is a problem that the output of the power generator cannot be supplied to the load.

  Note that a general uninterruptible power supply can supply the output of a storage battery to a load at the time of a power failure of the system power supply, but this type of power supply does not include a power generator such as a solar battery, The power can be supplied only to a short time immediately after the occurrence of a power failure.

JP 2000-132251 A JP 2013-5630 A

  The present invention has been made in view of the above circumstances. In the non-power failure state, the grid power supply and the power generation apparatus perform a grid-connected operation for supplying power to the load, while in the power failure state, the reverse power flow to the system power source is performed. It aims at providing the grid connection apparatus which can perform the self-sustained operation which supplies electric power to a load from a storage battery and an electric power generator, preventing.

  Another object of the present invention is to provide a grid interconnection device capable of charging a storage battery and selling the generated power of the power generation device during grid operation for supplying power from the system power supply and the power generation device to the load. And

  Moreover, it aims at providing the grid connection apparatus which can supply electric power from a power generator to a load in the power failure state from a power failure to a power recovery using the power generator which stops an output autonomously at the time of a power failure. To do.

  In particular, an object of the present invention is to provide a grid interconnection device in which the power generation device is a solar cell.

  It is another object of the present invention to provide a grid interconnection device capable of charging a storage battery and generating a solar cell with high efficiency during grid operation for supplying power from a grid power source and a solar battery to a load. And

  The grid interconnection apparatus according to the first aspect of the present invention has a DC terminal to which a storage battery is connected and an AC terminal to which a grid power supply is connected, and performs bidirectional power conversion between the DC terminal and the AC terminal. An inverter circuit, a load and a power generation device connected in parallel with the system power supply to a common line including the AC terminal, system voltage measuring means for measuring the voltage of the system power supply, the AC terminal and the system power supply A system switch that connects the AC terminal, the load, and the power generation device, and a self-standing switch that connects the AC terminal, the load, and the power generation device. Based on the measurement result of the grid voltage switch and the grid voltage measuring means that is selectively connected to either of the power supply side, a power failure and power recovery of the grid power supply are detected, and the grid switch is The self-standing switch to be non-conductive, the interconnection switch is connected to the system power supply side, and the bidirectional inverter circuit and the generator are driven. The system operation state, and the system switch is made non-conductive to make the self-supporting switch conductive, and the interconnection switch is connected to the AC terminal side, and the bidirectional inverter circuit and It is comprised with the connection control means which switches the self-sustaining operation state which driven the said electric power generating apparatus.

  By adopting such a configuration, the grid power supply, the load, the power generation device, and the storage battery can be connected to each other on the common line by connecting the grid switch, the self-supporting switch, and the grid switching switch to the grid connection in the grid operation state. Connected. On the other hand, in the self-sustained operation state, the load, the power generation device, and the storage battery are connected to each other on the common line while being disconnected from the system power supply by making each switch stand-alone.

  Switching of the operation state is performed by detecting a power failure and power recovery of the system power supply, and supplying power from the system power supply and the power generation device to the load while charging the storage battery before the power failure before or after the power failure. be able to. Moreover, at the time of the independent operation from a power failure to a power recovery, it is possible to supply power from the power generation device and the storage battery to the load while preventing the power of the power generation device and the storage battery from flowing backward to the system power supply. Moreover, a storage battery can be charged using the electric power of a power generator.

  Further, by connecting the storage battery and the power generation device on a common line via a bidirectional inverter circuit, only the output of the power generation device can be measured as AC power, distinct from the output of the storage battery. For this reason, it becomes possible to sell the electric power generated by the power generator to an electric power company.

  In the grid interconnection device according to the second aspect of the present invention, in addition to the above configuration, the grid control means sets the grid switch and the self-supporting switch in a non-conductive state, and sets the grid switching switch to the grid power supply side. The power generator is connected to the connected power generator and is switched to the power generator linked operation state in which the power generator is driven.

  According to such a configuration, the storage battery can be disconnected from the system power supply while the load and the power generation apparatus are connected to the system power supply in the power generation apparatus interconnection operation state. Therefore, it is possible to sell the electric power generated by the power generator to an electric power company by switching the operation state to the power generator linked operation state.

  In addition to the above configuration, the grid interconnection device according to the third aspect of the present invention is provided when the interconnection control means switches the operation state among the interconnection operation state, the independent operation state, and the power generator interconnection operation state. The self-sustained stop state in which the bidirectional inverter circuit and the power generator are stopped is provided during switching of the operation state.

  According to such a configuration, the bidirectional inverter circuit and the power generation device can be temporarily stopped when the operation state is switched among the interconnection operation state, the independent operation state, and the power generation device interconnection operation state. That is, when the operating state is switched at the time of a power failure, power recovery, or the like, it is possible to satisfy the demand of the electric power company that the device connected to the common line with the system power supply must be stopped.

  In addition to the above configuration, the grid interconnection device according to the fourth aspect of the present invention determines whether the power generation device has a power failure and power recovery based on the voltage supplied to the common line, and stops output after the determination of the power failure. After the power recovery is judged, the output is restarted, and after the above-mentioned grid control means detects a power failure and shifts from the grid operation state to the self-sustained stop state, the self-support switch The power supply from the storage battery to the common line is started, and the power generator determines that power is restored. Configured to resume output.

  According to such a configuration, the voltage level of the common line rises due to the power supply from the storage battery to the common line at the time of transition from the self-sustaining stop state to the self-sustaining operation state. Resume output. In other words, when a power failure is detected and a transition is made from a connected operation state to a self-sustained operation state, the output of the power generation device is temporarily stopped and then the power generation device autonomously restarts the output to cause the power generation device to transition to the self-sustained operation state. be able to.

  In addition to the above-described configuration, the grid interconnection device according to the fifth aspect of the present invention, after the interconnection control means detects power recovery and shifts from the self-sustained operation state to the self-sustained stop state, At the time of transition, the power supply to the common line is resumed by setting the system switch to the conductive state and controlling the connection switch to be connected to the system power supply side, and the power generator is restored. It is configured to restart the output after determining that the power is present.

  According to such a configuration, the voltage level of the common line rises due to the power supply to the common line at the time of transition from the self-sustained stop state to the interconnected operation state. To resume. In other words, when the power recovery is detected and the transition from the self-sustained operation state to the connected operation state is made, after the output of the power generation device is temporarily stopped, the power generation device autonomously resumes the output to enter the connected operation state. Can be migrated.

  In the grid interconnection device according to the sixth aspect of the present invention, in addition to the above-described configuration, the interconnection control means detects a power failure and stops the bidirectional inverter circuit and the power generation device to change from the interconnection operation state to the self-sustaining stop state. After the transition, the system switch, the self-sustained switch and the interconnection changeover switch are set to the self-sustained connection, and the bidirectional inverter circuit is activated to perform the control to be switched to the self-sustained operation state. After the bidirectional inverter circuit and the power generation device are stopped to shift from the self-sustained operation state to the self-sustained stop state, the system switch, the self-supporting switch, and the system connection switching switch are connected to the system connection and the bidirectional inverter It is configured to perform control to activate the circuit and switch to the connected operation state.

  According to such a configuration, the operation state can be switched by controlling the bidirectional inverter circuit, the power generator, and each switch.

  In addition to the above configuration, the grid interconnection apparatus according to the seventh aspect of the present invention is a solar cell in which the power generation device generates DC power using the photovoltaic effect, and converts the DC power of the solar cell into AC power. And a power conditioner for controlling the power generation efficiency of the solar cell. According to such a configuration, since the solar cell and the storage battery are connected on the common line via the bidirectional inverter circuit, it is possible to suppress the output voltage of the solar cell from being influenced by the voltage of the storage battery. Can be generated with high efficiency.

  In addition to the above configuration, the grid interconnection apparatus according to the eighth aspect of the present invention is configured such that the storage battery is charged and discharged by the bidirectional inverter circuit. According to such a configuration, the storage battery can be charged using the power supplied from the system power supply or the power generation device, while the discharge power of the storage battery can be supplied to the load.

  According to the present invention, in the non-power failure state, the grid operation for supplying power from the system power source and the power generation device to the load is performed, while in the power failure state, the reverse power flow to the system power source is prevented while the storage battery and the power generation device It is possible to provide a grid interconnection apparatus that performs a self-sustaining operation for supplying power to a load.

  In addition, it is possible to provide a grid interconnection device that can charge the storage battery and sell the generated power of the power generation device during the grid operation for supplying power from the grid power source and the power generation device to the load.

  Moreover, the grid connection apparatus which supplies electric power from a power generator to a load can be provided in the power failure state from a power failure to a power recovery using the power generator which stops an output autonomously at the time of a power failure.

  In particular, it is possible to provide a grid interconnection device in which the power generation device is a solar cell.

  In addition, it is possible to provide a grid interconnection device that can charge a storage battery and generate power with high efficiency in a grid operation in which power is supplied from a grid power source and a solar battery to a load.

1 is a system diagram showing a configuration example of a grid interconnection device 1 according to an embodiment of the present invention. It is the figure which showed an example of operation | movement of the grid connection apparatus 1 of FIG. It is the block diagram which showed the structural example of the interconnection control part 15 of FIG. It is the timing chart which showed an example of operation | movement of the system power supply 2, the bidirectional | two-way inverter circuit 11, SW21-23, and the PV power conditioner 4 of FIG. It is the flowchart which showed an example of the operation | movement at the time of the grid operation in the grid connection apparatus 1 of FIG. It is the flowchart which showed an example of the operation | movement at the time of the independent operation in the grid connection apparatus 1 of FIG.

  FIG. 1 is a system diagram showing a configuration example of a grid interconnection device 1 according to an embodiment of the present invention. The grid interconnection device 1 is connected to the grid power supply 2 and can supply power from the grid power supply 2 to the load 3. Further, the storage battery 10, the PV power conditioner 4, and the solar battery 5 are incorporated, and the outputs of the solar battery 5 and the storage battery 10 can be supplied to the load 3. Furthermore, the storage battery 10 can be charged with the electric power of the system power supply 2 and the solar battery 5, and the output of the solar battery 5 can be caused to flow backward to the system power supply 2. That is, in the grid interconnection device 1, power can be supplied from each of these power supplies to the load 3 by linking the grid power supply 2, the solar battery 5 and the storage battery 10 as distributed power supplies.

  The grid interconnection device 1 includes a load 3, a PV power conditioner 4, a solar battery 5, a storage battery 10, a bidirectional inverter circuit 11, a voltmeter 14, a grid connection control unit 15, a grid terminal 16, and a grid SW (switch) 21. The self-supporting SW 22 and the interconnection switching SW 23 are configured.

<System terminal 16>
The system terminal 16 is an external terminal to which the system power supply 2 is connected, and predetermined AC power is supplied to the system terminal 16 via an electric power company power network (commercial system). The system terminal 16 is connected to a commercial system via, for example, a distribution board or a service line.

  The load 3 is a device that operates by being supplied with AC power. For example, an electric device such as a television receiver or a refrigerator arranged in a house, a wiring device such as an outlet or a wall switch, an air conditioner, or a lighting facility. And other equipment.

  The solar cell 5 is a power generation device that generates direct-current power using the photovoltaic effect, and can convert sunlight energy into electric power. For example, it consists of a photovoltaic module in which a plurality of cells are connected in series or in parallel.

  The load 3 and the PV power conditioner 4 are respectively connected in parallel with the system power supply 2 to the common line 6 including the AC terminal 13 of the bidirectional inverter circuit 11.

<PV power conditioner 4>
The PV power conditioner 4 has an input terminal (not shown) connected to the solar cell 5, an output terminal (not shown) connected to the common line 6, and DC power input from the solar cell 5 is converted to AC power. It is an inverter device that converts and outputs to the common line 6, and performs system interconnection control that synchronizes the output with the waveform of the system power supply 2. Moreover, the system power supply control 2 which judges the power failure and power recovery of the system power supply 2, and stops or restarts the output is performed.

  The PV power conditioner 4 determines whether or not a power failure and power recovery occur according to whether or not a predetermined voltage is generated on the common line 6. When a predetermined voltage is detected, the PV power conditioner 4 determines that the power failure is in a non-power failure state. Operate. Further, if the voltage on the common line 6 drops below a predetermined level and a certain time or more elapses, it is determined that a power failure has occurred, and the PV power conditioner 4 is stopped. Further, the operating point of the solar cell 5 is controlled by controlling the operating point of the solar cell 5 to maximize the output power.

  In the present embodiment, for easy explanation, the actual power failure state and the non-power failure state are detected by the interconnection control unit 15 described later, and the PV power conditioner 4 is stopped by the interconnection control unit 15. The subsequent restart of the operation of the PV power conditioner 4 is described as being performed based on the judgment of the PV power conditioner 4, but the PV power conditioner 4 may be controlled by the interconnection control unit 15.

  For example, the PV power conditioner 4 includes a chopper circuit, an inverter circuit, and a control circuit (all not shown), and the voltage at the input terminal to which the solar cell 5 is connected is boosted to a DC intermediate voltage by the chopper circuit. The inverter circuit converts the intermediate voltage into an AC voltage and outputs it from the output terminal to the common line 6. The control circuit controls these circuits based on the voltage at the input terminal and the output terminal.

  The operating point control of the solar cell 5 is performed by controlling the switching operation of the inverter circuit and the chopper circuit. The output characteristics (VI characteristics) of the solar cell 5 change depending on the amount of solar radiation and temperature. For this reason, the output power can be maximized by controlling the output voltage of the solar cell 5 by the well-known MPPT (Maximum Power Point Tracking) and optimizing the operating point on the output characteristics. .

  System protection control determines power outage and power recovery. When power outage is determined, the output of PV power conditioner 4 is stopped. The AC power is prevented from being output from the PV power conditioner 4. The determination of power failure and power recovery is made based on the voltage supplied to the common line 6, and the output is stopped by stopping the switching operation of the chopper circuit and the inverter circuit. That is, the PV power conditioner 4 can autonomously perform system protection control.

<Storage battery 10>
The storage battery 10 is a secondary battery that is charged and discharged by inputting and outputting DC power, and for example, a lithium ion battery can be used. The electric power stored in the storage battery 10 is supplied to the DC terminal 12 of the bidirectional inverter circuit 11. In addition, the storage battery 10 is not limited to what is built in the grid connection apparatus 1, It may be connected externally.

<Bidirectional inverter circuit 11>
The bidirectional inverter circuit 11 has a DC terminal 12 to which the storage battery 10 is connected and an AC terminal 13 to which the system power supply 2 is connected, and performs electric power conversion bidirectionally between the DC terminal 12 and the AC terminal 13. It is a conversion device. When charging the storage battery 10, AC power input to the AC terminal 13 is converted into DC power by the bidirectional inverter circuit 11 and output from the DC terminal 12. On the other hand, when the storage battery 10 is discharged, the DC power input to the DC terminal 12 is converted into AC power by the bidirectional inverter circuit 11 and output from the AC terminal 13.

  For example, the bidirectional inverter circuit 11 includes a switching circuit, an AC filter, and a transformer (all not shown). The switching circuit is composed of a semiconductor switching element, for example, an FET (field effect transistor), and performs a switching operation so that the voltage at the AC terminal 13 is constant. Further, the switching operation is stopped based on the gate drive signal input from the interconnection control unit 15. The AC filter is a circuit element for shaping the AC output of the switching circuit to obtain a low distortion AC voltage. The transformer is a circuit element that is insulated from the system power supply 2 and boosts the AC output of the AC filter. The bidirectional inverter circuit 11 stops operating when the interconnection control unit 15 stops outputting the gate drive signal.

<SW21-23>
The interconnection switching SW 23 is a changeover switch for switching between interconnection operation and independent operation, and selectively connects the load 3 and the PV power conditioner 4 to either the system power supply side or the AC terminal 13 side. Specifically, the common terminal s0 connected to the load 3 and the PV power conditioner 4 is selectively connected to either the grid operation terminal s1 or the independent operation terminal s2. The interconnection operation terminal s1 is a terminal selected during the interconnection operation, and is connected to the system terminal 16 and the system SW21. On the other hand, the independent operation terminal s2 is a terminal selected during the independent operation and is connected to the independent SW 22.

  That is, when the system switch SW21 is turned on during the interconnecting operation in which the interconnecting switch SW23 is connected to the interconnecting operation terminal s1, the bidirectional inverter circuit 11, the system power supply 2, the load 3, and the PV power conditioner 4 are mutually connected. Can be connected. On the other hand, when the grid switching SW23 is connected to the autonomous operation terminal s2 side and the system SW21 is turned off and the autonomous SW22 is turned on, the bidirectional power supply circuit 2 is disconnected in the state where the system power supply 2 is disconnected. 3 and the PV power conditioner 4 can be connected to each other.

  The system SW21 is a switch for disconnecting the bidirectional inverter circuit 11 from the system power supply 2, and connects the AC terminal 13 and the system power supply 2 so as to be conductive. That is, the system SW 21 connects the system terminal 16 and the AC terminal 13 of the bidirectional inverter circuit 11 so as to be conductive. During the interconnection operation, the load 3 and the PV power conditioner 4 are connected to the system power supply 2 via the interconnection switching SW 23. In this state, if the system SW 21 is turned off, the PV power conditioner 4 is connected to the system power source 2 and the bidirectional inverter circuit 11 is not connected, and the solar battery 5 sells the generated power. It becomes possible.

  The independent SW 22 is a switch for connecting the bidirectional inverter circuit 11 to the load 3 and the PV power conditioner 4 during the independent operation, and connects the AC terminal 13 to the load 2 and the PV power conditioner 4 so as to be conductive. ing. That is, the independent SW 22 connects the independent operation terminal s2 of the interconnection switching SW 23 and the AC terminal 13 of the bidirectional inverter circuit 11 so as to be conductive. For this reason, when a power failure is detected, the self-supporting SW 22 is turned on, the bidirectional inverter circuit 11 is connected to the load 3 and the PV power conditioner 4, and power can be continuously supplied to the load 3 even during the power failure. For example, the system SW21, the self-supporting SW22, and the interconnection switching SW23 are electromagnetic relays that open and close electrical contacts using an electromagnet.

<Voltmeter 14>
The voltmeter 14 is a system voltage measuring unit that measures the voltage of the system power supply 2, and the measurement result is output to the interconnection control unit 15. Since the voltmeter 14 is disposed between the system SW 21 and the system terminal 16, the voltage waveform of the system power supply 2 can be correctly measured regardless of the operating states of the SWs 21 to 23.

<Interconnection Control Unit 15>
The interconnection control unit 15 detects a power failure and power recovery of the system power supply 2 based on the measurement result of the system voltage by the voltmeter 14 and controls the bidirectional inverter circuit 11 and the SWs 21 to 23 to perform the interconnection operation. The state, the self-sustaining operation state, the self-sustaining stop state, and the power generator linked operation state are switched.

  A power outage is a state in which the voltage level of the system power supply 2 is lower than a certain value continues for a certain time or more, and an instantaneous voltage drop in the system power supply 2 is different from a power outage. In addition, power recovery is that the voltage level of the system power supply 2 is almost restored to the state before the power failure.

  The interconnected operation state is an operation state in which the SWs 21 to 23 are interconnected and the bidirectional inverter circuit 11 and the PV power conditioner 4 are driven. The interconnection connection is a connection state in which the system SW 21 is turned on and the self-supporting SW 22 is turned off, and the system switching SW 23 is connected to the system power supply 2 side. In other words, in the grid connection, the grid switching SW 23 is switched to the grid operation terminal s1 side, and the grid power supply 2 is connected to the AC terminal 13, whereby the grid power supply 2, the load 3, the PV power conditioner 4, and the bidirectional power supply are connected. Inverter circuits 11 are connected to each other on a common line 6.

  The independent operation state is an operation state in which the SWs 21 to 23 are connected independently and the bidirectional inverter circuit 11 and the PV power conditioner 4 are driven. The independent connection is a connection state in which the system SW 21 is turned off and the independent switch 22 is turned on, and the interconnection switching SW 23 is connected to the AC terminal 13 side. That is, in the independent connection, the interconnection switching SW 23 is switched to the independent operation terminal s2 side, and the grid power supply 2 is disconnected from the AC terminal 13, whereby the power supplied from the storage battery 10 and the PV power conditioner 4 is supplied to the grid power supply 2. The load 3, the PV power conditioner 4 and the bidirectional inverter circuit 11 are connected to each other on the common line 6 while preventing reverse flow.

  The self-sustaining stop state is a state in which the SWs 21 and 22 are turned off and the bidirectional inverter circuit 11 and the PV power conditioner 4 are stopped. That is, in the self-sustaining stop state, the load 3 and the PV power conditioner 4 are disconnected from the system power supply 2 and the operations of the PV power conditioner 4 and the bidirectional inverter circuit 11 are stopped.

  The power generator interconnection operation state is an operation state in which SW 21 and 22 are turned off, the interconnection switching SW 23 is connected to the system power supply 2 side, and the PV power conditioner 4 is driven. In the power generation apparatus interconnection operation state, the storage battery 10 is disconnected from the system power supply 2 while the load 2 and the PV power conditioner 4 are connected to the system power supply 2, so that the electric power generated by the solar battery 5 is sold to the electric power company. It becomes possible to do.

  The interconnection control unit 15 restarts the power supply from the storage battery 10 to the load 3 after stopping the operation of the PV power conditioner 4 at the time of transition from the interconnection operation state to the self-sustained operation state. The output of the conditioner 4 is restarted.

  FIG. 2 is a diagram illustrating an example of the operation of the grid interconnection device 1 of FIG. 1. The system SW 21, the autonomous SW 22, and the interconnection in the interconnection operation state, the autonomous operation state, the autonomous stop state, and the power generation device interconnection operation state are illustrated. The operating states of the system switching SW 23, the bidirectional inverter circuit 11, and the PV power conditioner 4 are shown.

  The system SW21 is in an on state in the interconnected operation state, and is in an off state in the independent operation state, the autonomous stop state, and the power generator interconnected operation state. The self-supporting SW 22 is in an on state in the self-sustaining operation state, and is in an off state in the interconnecting operation state, the self-sustaining stop state, and the power generation device interconnected operation state. The interconnection switching SW 23 is on the system side, that is, the interconnection operation terminal s1 side in the interconnection operation state and the power generator interconnection operation state, and is on the inverter side, that is, the autonomous operation terminal s2 side in the autonomous operation state.

  Further, the interconnection switching SW 23 is indefinite in the self-sustaining stop state, and the connection state in the immediately preceding operation state is maintained. For example, when a power failure is detected and a transition is made from the grid operation state to the self-sustaining stop state, the system side. Further, when some abnormality or the like occurs during the self-sustaining operation and shifts to the self-sustaining stop state, it is on the inverter side. In addition, when the power recovery is detected and the self-sustained operation state is shifted to the self-sustained stop state, it is on the system side.

  Each of the bidirectional inverter circuit 11 and the PV power conditioner 4 is in an operating state in the interconnected operation state and the independent operation state, and is in a stopped state in the independent operation stop state. Further, in the power generator linked operation state, the bidirectional inverter circuit 11 is in a stopped state, and the PV power conditioner 4 is in an operating state.

  The interconnection control unit 15 detects a power failure and power recovery of the system power supply 2 and switches the operation state to either the interconnection operation state or the independent operation state. For this reason, the storage battery 10 is charged using the electric power supplied from the system power source 2 or the PV power conditioner 4 before the power failure or after the power recovery, or the storage battery 10, the system power source 2 or the PV power. The load 3 can be driven using the power supplied from the conditioner 4.

  In addition, during the self-sustained operation from power failure to power recovery, the power supplied from the PV power conditioner 4 is prevented while the power supplied from the storage battery 10 or the PV power conditioner 4 is prevented from flowing backward to the system power supply 2. Can be used to charge the storage battery 10 or drive the load 3 using the power supplied from the PV power conditioner 4 or the storage battery 10.

  In addition, the interconnection control unit 15 switches to the power generator interconnection operation state based on a user operation during the interconnection operation. In this power generator interconnection operation state, the storage battery 10 is disconnected from the system power supply 2 while the load 3 and the PV power conditioner 4 are connected to the system power supply 2, so that the electric power generated by the solar battery 5 is supplied to the power company. Can be sold.

  In addition, the interconnection control unit 15 provides the autonomous stop state during switching of the operation state when the operation state is switched among the interconnection operation state, the autonomous operation state, and the power generator interconnection operation state. That is, when switching an operation state between a connected operation state, a self-sustained operation state, and a power generator connected operation state, it is performed via a self-sustained stop state. For this reason, the bidirectional inverter circuit 11 and the PV power conditioner 4 can be temporarily stopped. That is, when the operation state is switched at the time of a power failure, power recovery, or the like, it is possible to satisfy the demand of the electric power company that the device connected to the common line 6 with the system power supply 2 must be stopped.

<Interconnection Control Unit 15>
FIG. 3 is a block diagram showing a configuration example of the interconnection control unit 15 in FIG. The interconnection control unit 15 includes a system state determination unit 151, a SW switching unit 152, and an inverter control unit 153. Based on the system voltage measured by the voltmeter 14, the system state determination unit 151 determines a power failure and power recovery of the system power supply 2 and outputs the determination results to the SW switching unit 152 and the inverter control unit 153.

  The SW switching unit 152 operates in any one of the interconnection operation state, the independent operation state, the autonomous stop state, or the power generator interconnection operation state by switching the SWs 21 to 23 based on the determination result of the system state determination unit 151. The state is switched and controlled. The inverter control unit 153 generates a gate drive signal based on the determination result of the system state determination unit 151 and outputs the gate drive signal to the bidirectional inverter circuit 11. The inverter control unit 153 shuts off the power supply from the storage battery 10 to the PV power conditioner 4 by stopping the output of the gate drive signal at the time of transition from the interconnection operation state to the self-sustained operation state, and thereafter for a certain period of time. When the time elapses, the power supply from the storage battery 10 to the PV power conditioner 4 is resumed by resuming the output of the gate drive signal.

  Further, the inverter control unit 153 stops the output of the gate drive signal at the time of transition from the independent operation state to the connected operation state or at the time of transition from the connected operation state to the independent operation state. 11 is temporarily stopped, and after a certain period of time has elapsed, the output of the bidirectional inverter circuit 11 is restarted by restarting the output of the gate drive signal.

  FIG. 4 is a timing chart showing an example of the operation of the system power supply 2, the bidirectional inverter circuit 11, the SWs 21 to 23, and the PV power conditioner 4 of FIG. This figure shows the operation of the grid interconnection device 1 at the time of power failure or power recovery of the grid power supply 2.

  In the connected operation state, the system SW21 is on, the independent SW22 is off, the connection switching SW23 is on the connection operation terminal s1 side, and the bidirectional inverter circuit 11 and the PV power conditioner 4 are in an operating state.

If the system power supply 2 at time t ₁ a transition from the non-power failure condition to the power outage, the voltage of the common line 6 is lowered, PV power conditioner 4 is determined that power failure condition, the PV power conditioner 4 in the stopped state To do. Further, the interconnection control unit 15 detects a power failure of the system power supply 2, stops the gate drive signal, stops the operation of the bidirectional inverter circuit 11 (time t ₂ ), and sets the self-sustained stop state. Thus, both the PV power conditioner 4 and the bidirectional inverter circuit 11 can be stopped, and the reverse power flow to the system power supply 2 can be prevented.

At the subsequent time t ₃ , the interconnection control unit 15 switches off the system SW 21, restarts the operation of the bidirectional inverter circuit 11 at the time t ₄ , and then stabilizes the output of the bidirectional inverter circuit 11. ₅ , the self-supporting SW 22 is switched to the ON state, and the interconnection switching SW 23 is switched to the inverter side. That is, at time t _5, the energy of the battery 10 is supplied is converted into AC power to the load 3 by the bidirectional inverter circuit 11, driving the load 3 is resumed.

  By switching the self-supporting SW 22 and the interconnection switching SW 23 after restarting the operation of the bidirectional inverter circuit 11, a time required for the AC output of the bidirectional inverter circuit 11 to be stabilized can be secured.

The PV power conditioner 4 determines that the power has been restored because the voltage is generated in the common line 6 when the power supply from the storage battery 10 is resumed by the switching of the interconnection switching SW 23 at the time t _5, so that the power is restored, and the time t ₆ Resume output at. At this time, the self-sustaining operation state starts.

  In the self-sustaining operation state, power is supplied from the PV power conditioner 4 and the storage battery 10 to the load 3, or the storage battery 10 is charged by surplus power of the PV power conditioner 4. In this way, the storage battery 10 only needs to be able to supply power to the load 3 alone for a short time until the PV power conditioner 4 resumes output after the occurrence of a power failure and before the autonomous operation state is reached. Since it is charged by the PV power conditioner 4, the capacity of the storage battery 10 may be small, and the entire apparatus can be made small and inexpensive.

On the other hand, if the system power source 2 at time t ₇ the transition from the power failure state to a non-power failure condition, the communication system control unit 15 detects the power recovery of the system power source 2, a bidirectional inverter circuit to stop the gate driving signal 11 Is stopped (time t ₈ ). At this time, the system SW 21 is off, the self-supporting SW 22 is on, and the interconnection switching SW 23 is on the inverter side. Therefore, when the bidirectional inverter circuit 11 is stopped, the system power source 2 is disconnected. Therefore, the power supply source to the load 3 is only the PV power conditioner 4, and the voltage supplied to the common line 6 cannot be detected. The PV power conditioner 4 determines that the power failure state has occurred again and stops. To. In this way, even when power is restored, the self-sustaining stop state is temporarily entered.

At time t ₉ , the interconnection control unit 15 switches the independent SW 22 to OFF, switches the interconnection switching SW 23 to the system side, and restarts the operation of the bidirectional inverter circuit 11 at the subsequent time t ₁₀ . at time _{t 11} the output is stable countercurrent inverter circuit 11 switches the system SW21 on. As described above, after the operation of the bidirectional inverter circuit 11 is stopped, the voltage level in the common line 6 is quickly reduced by switching the self-supporting SW 22 and the interconnection switching SW 23, and the PV power conditioner 4 is surely stopped. be able to.

  Further, by turning on the system SW21 after resuming the operation of the bidirectional inverter circuit 11, the time required for the AC output of the bidirectional inverter circuit 11 to be stabilized can be secured.

PV power conditioner 4 is, by the power supply from the battery 10 by the switching of the system SW21 at time t ₁₁ is resumed, the voltage level of the common line 6 is raised, thereby determining that power restoration, the time t ₁₂ Resume output at. At this point, the connected operation state starts. Thus, at the time of transition between the grid operation state and the independent operation state, the PV power conditioner 4 is always stopped, so that the PV power conditioner 4 and the bidirectional inverter circuit 11 are temporarily stopped. The reverse power flow to the grid power supply 2 is reliably prevented.

  Steps S101 to S109 in FIG. 5 are flowcharts showing an example of an operation at the time of interconnection operation in the grid interconnection device 1 in FIG. First, the PV power conditioner 4 detects the presence / absence of a voltage on the common line 6 (step S101), determines that a power failure is not detected, and stops output (steps S102 and S103). .

  In addition, the interconnection control unit 15 measures the voltage of the system power supply 2 with the voltmeter 14 and discriminates between power failure and power recovery. At this time, if a power failure is detected, the interconnection control unit 15 stops the gate drive signal, stops the bidirectional inverter circuit 11, and turns off the system SW21 (steps S104 and S105). At this time, the connected operation state ends and the self-sustaining stop state is entered.

  Next, the interconnection control unit 15 activates the bidirectional inverter circuit 11, turns on the independent SW 22, and then switches the interconnection switching SW 23 to the inverter side (steps S106 to S108). At this time, the load 3 is driven only by the power of the storage battery 10. When the power supply from the storage battery 10 is resumed by switching the interconnection switching SW 23, the PV power conditioner 4 determines that the voltage level of the common line 6 rises, thereby determining power recovery and restarting the output. . At this time, the self-sustaining operation state starts (step S109).

  Steps S201 to S209 in FIG. 6 are flowcharts illustrating an example of the operation during the autonomous operation in the grid interconnection device 1 in FIG. First, the interconnection control unit 15 measures the voltage of the system power supply 2 with the voltmeter 14 and discriminates power failure and power recovery (steps S201 and S202). At this time, if it is determined that the state is a non-power failure state, the interconnection control unit 15 stops the gate drive signal and stops the bidirectional inverter circuit 11 (step S203).

  Next, the PV power conditioner 4 detects the presence / absence of a voltage on the common line 6 (step S204). When no voltage exceeding a certain level is detected, the PV power conditioner 4 determines that a power failure has occurred and stops the output (step S205). . At this time, the self-sustained operation state ends and the self-sustained stop state is entered. Next, the interconnection control unit 15 turns off the independent SW 22 and switches the interconnection switching SW 23 to the system side (step S206).

  Next, the interconnection control unit 15 activates the bidirectional inverter circuit 11 and turns on the system SW21 (steps S207 and S208). When the power supply from the system power supply 2 is restarted by switching the system SW 21, the PV power conditioner 4 increases the voltage level of the common line 6, thereby determining power recovery and restarting output ( Step S209). At this point, the connected operation state starts.

  According to the present embodiment, power can be supplied from the system power supply 2 and the solar battery 5 to the load 3 while charging the storage battery 10 at the time of the grid operation before power failure or after power recovery. Moreover, at the time of self-sustained operation from power failure to power recovery, power can be supplied from the solar cell 5 and the storage battery 10 to the load 3 while preventing the power of the solar cell 5 and the storage battery 10 from flowing backward to the system power supply 2. it can. Further, even during the self-sustaining operation, the storage battery 10 can be charged using the power generated by the solar battery 5.

  Further, by connecting the storage battery 10 and the PV power conditioner 4 on the common line 6 via the bidirectional inverter circuit 11, only the output of the solar battery 5 is measured as AC power as distinguished from the output of the storage battery 10. be able to. For this reason, it becomes possible to sell the electric power generated by the solar cell 5 to the electric power company.

  Specifically, when the interconnection switching SW 23 is connected to the interconnection operation terminal s 1 side and the system SW 21 and the independent SW 22 are turned off, the bidirectional inverter circuit 11 and the storage battery 10 are disconnected from the common line 6, Then, the power generation device connected to the load 3 and the power generation device including the PV power conditioner 4 and the solar battery 5 is brought into a connected state. In this state, the configuration is the same as a so-called interconnection state that is widespread in ordinary households. Therefore, the power output to the common line 6 is clearly recognized as the generated power generated by the solar cell 5 and the PV power conditioner 4 that is completely unrelated to the storage battery 10.

  Since the electric power company prohibits the reverse flow of the electric power stored in the storage battery to the system power supply 2, generally, the sale of electric power from the type grid interconnection device provided with the storage battery is not permitted. This is because it is unreasonable to store power from the system power supply 2 to the storage battery 10 at night when the electricity rate is cheap and to sell power from the storage battery 10 to the system power supply 2 during the daytime. However, according to the present invention, although the storage battery 10 is provided, the storage battery 10 can be disconnected from the system. Therefore, if a power generation meter is attached on the common line 6, the power can be properly sold.

  In addition, although this embodiment demonstrated the example in case a power generator consists of the PV power conditioner 4 and the solar cell 5, this invention does not limit a power generator to this. For example, the present invention can also be applied to a grid interconnection device that receives power supply from a fuel cell that can continuously extract power using an electrochemical reaction. Or the structure which receives supply of electric power from the electric power generating apparatus which generates electric power using wind power or hydraulic power may be sufficient.

  Further, in the present embodiment, an example has been described in which the operation of the bidirectional inverter circuit 11 is temporarily stopped at the time of transition from the grid operation state to the self-sustained operation state. The linkage control is not limited to this. For example, after detecting a power failure of the system power supply 2, the system SW 21 is quickly switched off while maintaining the operation state of the bidirectional inverter circuit 11. It may be configured to switch.

DESCRIPTION OF SYMBOLS 1 Grid connection apparatus 2 Grid power supply 3 Load 4 PV power conditioner 5 Solar cell 6 Common line 10 Storage battery 11 Bidirectional inverter circuit 12 DC terminal 13 AC terminal 14 Voltmeter 15 Link control unit 16 System terminal 21 System SW
22 Independent SW
23 Interconnection switch SW

Claims (6)

A bidirectional inverter circuit having a DC terminal to which a storage battery is connected and an AC terminal to which a system power supply is connected, and performing bidirectional power conversion between the DC terminal and the AC terminal;
A common line including the AC terminal, a load and a power generation device respectively connected in parallel with the system power supply;
A system voltage measuring means for measuring the voltage of the system power supply;
A system switch for connecting the AC terminal and the system power supply in a conductive manner;
An interconnection switch for selectively connecting the load and the power generator to either the system power supply side or the AC terminal side;
Based on the measurement result of the system voltage measuring means, the power supply of the system power supply is detected to detect a power failure and power recovery, and the bidirectional control circuit, the system switch and the system control switch for controlling the system switching switch ,
The power generation device determines a power failure and a power recovery based on the voltage supplied to the common line, stops the output after the power failure determination, restarts the output after the power recovery determination,
The interconnection control means brings the system switch into a conductive state, makes the interconnection switch connected to the system power supply side, and drives the bidirectional inverter circuit and the power generator. Connected operation state,
With the system switch in a non-conducting state, the connection switch is connected to the AC terminal side as a self-supporting connection, and the self-operating state in which the bidirectional inverter circuit and the power generator are driven,
The system switch is in a non-conducting state, the grid changeover switch is connected to the system power supply side, and the power generator linked operation state in which the power generator is driven is switched.
When the operation state is switched among the above-mentioned interconnected operation state, the above-mentioned independent operation state, and the above-mentioned power generation device interconnected operation state, an independent stop state in which the above-described bidirectional inverter circuit is stopped is provided between the operation state switching. System interconnection device characterized by. It said interconnection control means, after the transition from the interconnected operation state by detecting a power failure in the self-supporting stop state, during the transition from free-standing stop state to autonomous operation state, connects the interconnection changeover switch to the AC terminal side 2. The grid interconnection apparatus according to claim 1 , wherein by performing control, power supply from the storage battery to the common line is started, and the power generation apparatus determines that power is restored and restarts output. The interconnection control means detects the power recovery and shifts from the self-sustained operation state to the self-sustained stop state. the system switching switch by controlling that is connected to the system power supply side, claim the power supply to the common line is resumed, the power generating device is characterized in that to resume the output is determined that the power recovery 2 The grid interconnection device described in 1. The interconnection control means detects a power failure, stops the bidirectional inverter circuit and the power generation device and shifts to a self-sustaining stop state, and then makes the grid switch and the interconnection switching switch the independent connection, and while performing control to switch the autonomous operation state by starting the bidirectional inverter circuit, after shifting to self stopped detect the power recovery is stopped the bidirectional inverter circuit and the power generating device, the system switch and the communication The system interconnection device according to any one of claims 1 to 3 , wherein the system changeover switch is set to the interconnection connection, and the bidirectional inverter circuit is activated to switch to the interconnection operation state. . The power generation device includes a solar cell that generates DC power using the photovoltaic effect, and a power conditioner that converts the DC power of the solar cell into AC power and controls the power generation efficiency of the solar cell. The grid interconnection device according to any one of claims 1 to 4 , wherein The storage battery, the grid interconnection device according to any one of claims 1 to 5, characterized in that it is charged and discharged by the bidirectional inverter circuit.

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