JP7660407B2 - Power conditioner - Google Patents

Description

The present invention relates to a power conditioner that connects a photovoltaic power generation device and a charge/discharge device to a power line that is connected to a power grid.

Patent document 1 (JP 2020-156239 A) describes a power conditioner (hybrid power conditioner 13) that connects a solar power generation device (solar power generation unit 11) and a charge/discharge device (storage battery 10) to a power line that is connected to a power grid. In the invention described in Patent document 1, in the first operation mode, power from the power grid and power from the fuel cell are not charged to the charge/discharge device, so it is guaranteed that the power charged to the charge/discharge device is power originating from the solar power generation device. Note that in the second operation mode, power from the power grid and power from the fuel cell are charged to the charge/discharge device, so it is not guaranteed that the power charged to the charge/discharge device is only power originating from the solar power generation device.

JP 2020-156239 A

As in the invention described in Patent Document 1, if it were possible to charge the charge/discharge device with the power of a power generation device such as a fuel cell, this would be advantageous in that the remaining charge of the charge/discharge device could be increased. In particular, in the case of an abnormal state such as a power outage in the power grid, it would be advantageous if the surplus power of the power generation device could be charged by the charge/discharge device.

Another problem is that the solar output power of the solar power generation device may increase or decrease rapidly in a short period of time, for example, depending on the weather. If the solar output power of the solar power generation device increases or decreases rapidly in a short period of time, there is a high possibility that the reverse flow power to the power grid or the power received from the power grid will increase or decrease rapidly in a short period of time. However, if a charging/discharging device is also provided, it may be possible to reduce the increase or decrease in the reverse flow power to the power grid by increasing the discharge power or decreasing the charging power of the charging/discharging device in response to a decrease in the solar output power of the solar power generation device, or by decreasing the discharge power or increasing the charging power of the charging/discharging device in response to an increase in the solar output power of the solar power generation device. However, when the charging/discharging device is operated in this way, i.e., when power is also reversely flowed from the charging/discharging device to the power grid, it may be necessary for the remaining charge of the charging/discharging device to originate from the generated power of the solar power generation device.

The present invention was made in consideration of the above problems, and its purpose is to provide a power conditioner that can ensure that the power flowing back to the power grid originates from the solar power generation device while allowing the charging/discharging device to be charged with power originating from a power source other than the solar power generation device as necessary.

A characteristic configuration of a power conditioner according to the present invention for achieving the above object is a power conditioner that connects a photovoltaic power generation device and a charge/discharge device to a power line that is connected to a power grid,
When in a normal state in which power is normally supplied from the power system to the power line, the system operates in a state in which charging of the charging/discharging device is permitted in a state that satisfies a charge limiting condition that the charging power to the charging/discharging device is equal to or less than the power generation power of the solar power generation device, and does not permit charging of the charging/discharging device in a state in which the charge limiting condition is not satisfied, and permits the discharge power of the charging/discharging device to be supplied to the power system ;
When an abnormal state occurs in which power is not normally supplied from the power system to the power line, permitting charging to the charging/discharging device in a state in which the charging restriction condition is not satisfied;
After the abnormal state is changed to the normal state, a reverse flow limiting process is performed to limit the supply of power stored in the charging/discharging device during the abnormal state to the power grid .

According to the above characteristic configuration, the power conditioner operates in a state where it permits charging of the charging/discharging device in a state where the charging power to the charging/discharging device is equal to or less than the power generated by the photovoltaic power generation device and does not permit charging of the charging/discharging device in a state where the charging/discharging device is not permitted to satisfy the charging/discharging device. In other words, if the charging power to the charging/discharging device is equal to or less than the power generated by the photovoltaic power generation device, when charging power to the charging/discharging device, only a part or all of the power generated by the photovoltaic power generation device is charged to the charging/discharging device, and power originating from a power source other than the photovoltaic power generation device is not charged to the charging/discharging device. Therefore, by charging the charging/discharging device in a state where the charging power to the charging/discharging device is equal to or less than the power generated by the photovoltaic power generation device in a normal state and satisfying the charging limiting condition, it is possible to ensure that the power charged to the charging/discharging device is power originating from the photovoltaic power generation device. Furthermore, even if the power conditioner operates in a state where it permits the discharge power of the charging/discharging device to be supplied to the power grid, it is possible to ensure that the power supplied to the power grid is power originating from the photovoltaic power generation device.
Therefore, a power conditioner can be provided that can charge a charging/discharging device with power originating from a power source other than a solar power generation device as necessary, while ensuring that power flowing back to the power grid originates from the solar power generation device.

In addition, according to this characteristic configuration, when the power conditioner is in an abnormal state, it allows charging to the charging/discharging device in a state that does not satisfy the charging limit condition. Therefore, it is possible to ensure a sufficient remaining charge of the charging/discharging device. Furthermore, after the power conditioner transitions from the abnormal state to the normal state, it performs a reverse power flow limiting process that limits the supply of power that was charged to the charging/discharging device during the abnormal state to the power grid. Therefore, even if power that does not originate from the photovoltaic power generation device is charged to the charging/discharging device during the abnormal state, it is possible to prevent the power from being supplied to the power grid.

Another characteristic configuration of the power conditioner according to the present invention is to obtain a transition state remaining amount, which is a charge remaining amount of the charging/discharging device at a time when the abnormal state transitions to the normal state,
The reverse flow limiting process is such that, after transitioning from the abnormal state to the normal state, the remaining charge amount at the time of transition is set to a provisional lower limit value of the remaining charge amount of the charging/discharging device, and discharging from the charging/discharging device is permitted while the remaining charge amount of the charging/discharging device is set to be equal to or greater than the provisional lower limit value.

According to the above characteristic configuration, the power conditioner, after transitioning from an abnormal state to a normal state, sets the remaining charge amount at transition, which is the remaining charge amount of the charging/discharging device at the time of transition from the abnormal state to the normal state, as a provisional lower limit of the remaining charge amount of the charging/discharging device, and permits discharge from the charging/discharging device while setting the remaining charge amount of the charging/discharging device to equal to or greater than the provisional lower limit, as a reverse power flow limiting process. In other words, even if the remaining charge amount at transition includes power that does not originate from the photovoltaic power generation device, it is guaranteed that the power is not apparently discharged.

Another characteristic configuration of the power conditioner of the present invention is that, as the reverse flow limiting process, after transitioning from the abnormal state to the normal state, a predetermined power load unit is used to consume power, thereby reducing the remaining charge of the charging/discharging device to a lower discharge limit value.
Here, after the reverse power flow limiting process is completed, the power stored in the charge/discharge device may be permitted to be supplied to the power grid.

According to the above characteristic configuration, even if the remaining charge at the time of transition includes electricity that does not originate from the solar power generation device, it is guaranteed that all of that electricity is consumed by the power load unit and is not discharged to the power grid.

Another characteristic configuration of the power conditioner according to the present invention is to obtain a transition state remaining amount, which is a charge remaining amount of the charging/discharging device at a time when the abnormal state transitions to the normal state,
As the reverse flow limiting process,
permitting discharge from the charging/discharging device for a predetermined period while keeping the remaining charge of the charging/discharging device equal to or greater than a tentative lower limit, and after the predetermined period has elapsed, performing a lower limit value reduction process to reduce the remaining charge of the charging/discharging device to a new tentative lower limit value that is smaller than the current tentative lower limit value by consuming power using a predetermined power load unit, said lower limit value reduction process being repeated until said tentative lower limit value becomes a discharge lower limit value of the charging/discharging device;
The tentative lower limit value after the transition from the abnormal state to the normal state is set to the transition state residual charge amount.

According to the above characteristic configuration, even if the remaining charge at the time of transition contains power that does not originate from the photovoltaic power generation device, it is guaranteed that the power is not apparently discharged. Furthermore, even if the remaining charge at the time of transition contains power that does not originate from the photovoltaic power generation device, it is guaranteed that the power is all repeatedly consumed in the power load unit by the lower limit value reduction process and is not discharged to the power grid.

Another characteristic feature of the power conditioner of the present invention is that it sets an authorization period during which the discharge power of the charging/discharging device is permitted to be supplied to the power grid, and operates in a state in which the discharge power of the charging/discharging device is not permitted to be supplied to the power grid outside of the authorization period.

According to the above characteristic configuration, it is possible to set an authorization period during which the discharge power of the charging/discharging device is permitted to be supplied to the power grid, and a period during which the discharge power of the charging/discharging device is not permitted to be supplied to the power grid.

Another characteristic feature of the power conditioner of the present invention is that the permission period is a period other than the purchase period during which the power generated by the solar power generation device is purchased under the feed-in tariff system.

During the purchase period of the power generated by the photovoltaic power generation device under the Feed-in Tariff (FIT) system, it may be required to limit the power that is allowed to flow back to the power grid to only the power generated by the photovoltaic power generation device. In addition, even if the remaining charge of the charge/discharge device is only the power originating from the photovoltaic power generation device, it may be required to limit the discharge power of the charge/discharge device from flowing back to the power grid.
Therefore, in this characteristic configuration, the power conditioner operates in accordance with the feed-in tariff system by operating periods other than the purchase period during which the generated electricity from the solar power generation system is purchased under the feed-in tariff system as permission periods during which the discharged electricity from the charging/discharging device is permitted to be supplied to the power grid.

1 is a diagram showing a configuration of a power supply system in which a power conditioner is provided. 1 is a diagram showing a configuration of a power supply system in which a power conditioner is provided. FIG. 11 is a diagram illustrating a reverse power flow limiting process. FIG. 11 is a diagram illustrating a reverse power flow limiting process. FIG. 11 is a diagram illustrating a reverse power flow limiting process.

First Embodiment
Hereinafter, a power supply system provided with a power conditioner 20 according to a first embodiment of the present invention will be described with reference to the drawings.
Fig. 1 and Fig. 2 are diagrams showing the configuration of a power supply system in which a power conditioner 20 of the first embodiment is provided. Specifically, Fig. 1 shows a normal state (i.e., during grid-connected operation) in which power is normally supplied from a power system 1 to a power line 2, and Fig. 2 shows an abnormal state (i.e., during independent operation) in which power is not normally supplied from the power system 1. In Fig. 1 and Fig. 2, the locations where power is being supplied are indicated by thick lines.

As shown in the figure, the power supply system includes a power line 2 connected to a power grid 1, a solar power generation device 13, a charge/discharge device 12, and a fuel cell device 4, and a power load device 3 is connected to the power line 2. A connection point to the power grid 1 is provided on the upstream side of the power line 2, and a first connection point 5 and a second connection point 6 are provided on the power line 2 in that order downstream from the connection point to the power grid 1. In addition, the power supply system includes a power conditioner 20 that connects the solar power generation device 13 and the charge/discharge device 12 to the power line 2.

A first switching unit 10 is provided between the power conditioner 20 and the first connection point 5. A second switching unit 11 is provided between the first connection point 5 and the second connection point 6 in the middle of the power line 2. The first switching unit 10 switches the connection destination of the power conditioner 20 to the first connection point 5 of the power line 2 or the second switching unit 11. Specifically, as shown in FIG. 1, when the contact a and the contact b of the first switching unit 10 are connected, the power conditioner 20 is connected to the first connection point 5. In this case, the contact a and the contact c are connected in the second switching unit 11. Also, as shown in FIG. 2, when the contact a and the contact c of the first switching unit 10 are connected, the power conditioner 20 is connected to the second switching unit 11. In this case, the contact a and the contact b are connected in the second switching unit 11.

The power conditioner 20 includes a power conditioner circuit section 21 having electrical circuits such as a DC/DC conversion circuit and a DC/AC conversion circuit configured using semiconductor switching elements, etc., and a power conditioner control section 22 that controls the operation of the power conditioner circuit section 21. The solar power generation device 13 is a device that receives sunlight and generates power, and is connected to the power conditioner circuit section 21. The charge/discharge device 12 is a device that can discharge power stored in a charge/discharge section such as a storage battery, and charge power to the charge/discharge section, and is connected to the power conditioner circuit section 21.

The power conditioner 20 controls the operation of outputting the power generated by the solar power generation device 13 to the power line 2, and the operation of charging and discharging the charge/discharge device 12. The power conditioner 20 can control the power generated by the solar power generation device 13, for example, by maximum power tracking control, and supply the generated power to the power line 2. In addition, the power conditioner 20 can charge the charge/discharge device 12 with part or all of the power generated by the solar power generation device 13. The power conditioner 20 can also charge the charge/discharge device 12 with power received from the power line 2.

The fuel cell device 4 and the power load device 3 are connected to the second connection point 6. The fuel cell device 4 has a fuel cell section, such as a solid oxide fuel cell (SOFC) or a polymer electrolyte fuel cell (PEFC), and a fuel cell control section that controls the operation of the fuel cell section. The fuel cell device 4 also has a power conversion section that converts the power generated in the fuel cell section into power of the desired voltage, frequency, and phase, and outputs it to the second connection point 6 of the power line 2. The fuel cell device 4 may also be equipped with a fuel reformer that generates hydrogen or the like as a fuel gas to be supplied to the fuel cell section through a reforming process.

The fuel cell device 4 can perform load following operation and constant output operation. For example, when the fuel cell device 4 performs load following operation, it adjusts the output power to the power line 2 so that the power measured by the power measurement unit 9 becomes zero. When the fuel cell device 4 performs constant output operation, it supplies a predetermined output power to the power line 2. When the fuel cell device 4 performs constant output operation, if the power supplied from the fuel cell device 4 to the second connection point 6 of the power line 2 is greater than the power consumption of the power load device 3, the surplus power is supplied from the second connection point 6 toward the upstream second switching unit 11. On the other hand, if the power supplied from the fuel cell device 4 to the second connection point 6 of the power line 2 is less than the power consumption of the power load device 3, the shortage power is supplied from the second switching unit 11 toward the second connection point 6.

The operation of the first switching unit 10 and the second switching unit 11 is controlled by the power conditioner 20. For example, when the voltage measured by the voltage measuring unit 8 is equal to or higher than a predetermined lower limit voltage, the power conditioner control unit 22 determines that the power supply from the power system 1 to the power line 2 is normal, and switches the first switching unit 10 to a state in which the contacts a and b are connected, and switches the second switching unit 11 to a state in which the contacts a and c are connected, as shown in FIG. 1. When the voltage measured by the voltage measuring unit 8 is lower than the lower limit voltage, the power conditioner control unit 22 determines that the power supply from the power system 1 to the power line 2 is abnormal, and switches the first switching unit 10 to a state in which the contacts a and c are connected, and switches the second switching unit 11 to a state in which the contacts a and b are connected, as shown in FIG. 2.

In the power supply system of this embodiment, when the power conditioner 20 is in a normal state in which power is normally supplied from the power grid 1 to the power line 2, it operates in a state in which it permits charging of the charging/discharging device 12 in a state that satisfies the charging limiting condition that the charging power to the charging/discharging device 12 is equal to or less than the power generated by the solar power generation device 13, does not permit charging of the charging/discharging device 12 in a state in which the charging limiting condition is not satisfied, and permits the discharged power of the charging/discharging device 12 to be supplied to the power grid 1.

To be more specific, the power conditioner 20 is transmitted information about the charging/discharging power to the charging/discharging device 12, which can be measured by the power measurement unit 14, and information about the power generated by the solar power generation device 13, which can be measured by the power measurement unit 15. In the normal state shown in FIG. 1, the power conditioner control unit 22 allows charging to the charging/discharging device 12 in a state that satisfies the charging limiting condition that the charging power to the charging/discharging device 12 is equal to or less than the power generated by the solar power generation device 13, and operates the power conditioner circuit unit 21 in a state that does not allow charging to the charging/discharging device 12 in a state that does not satisfy the charging limiting condition. By performing such control, it is guaranteed that all of the remaining charge in the charging/discharging device 12 is power originating from the solar power generation device 13.

In addition, in the normal state shown in FIG. 1, the power conditioner control unit 22 allows the discharge power of the charge/discharge device 12 to be supplied to the power grid 1. Even in this case, since it is guaranteed that all of the remaining charge of the charge/discharge device 12 originates from the photovoltaic power generation device 13, even if the discharge power of the charge/discharge device 12 is supplied to the power grid 1 in response to, for example, a discharge command, it is guaranteed that the power originates from the photovoltaic power generation device 13.

When there is an abnormal state in which power supply from the power system 1 to the power line 2 is not being performed normally, the power conditioner control unit 22 permits charging to the charging/discharging device 12 in a state in which the above-mentioned charging restriction conditions are not satisfied. In other words, in the abnormal state shown in FIG. 2, power originating from the fuel cell device 4 can be charged to the charging/discharging device 12. In the abnormal state, the charging/discharging device 12 is not connected to the power system 1, so even if power originating from the fuel cell device 4 is being charged to the charging/discharging device 12, the discharged power of the charging/discharging device 12 is not supplied to the power system 1.

In this embodiment, even if the power originating from the fuel cell device 4 is charged to the charge/discharge device 12 during an abnormal state, the power originating from the fuel cell device 4 is not supplied to the power grid 1 due to the reverse flow limiting process performed by the power conditioner control unit 22 in the subsequent normal state. Specifically, after transitioning from the abnormal state to the normal state, the power conditioner control unit 22 performs a reverse flow limiting process that limits the supply of the power that was charged to the charge/discharge device 12 during the abnormal state to the power grid 1.

Figure 3 is a diagram explaining the reverse power flow limiting process performed by the power conditioner 20 of the first embodiment, and shows an example of the change over time in the remaining charge of the charge/discharge device 12. As shown in the figure, while the remaining charge of the charge/discharge device 12 is increasing in an abnormal state before time t1, the remaining charge may have included power originating from the fuel cell device 4.

Therefore, after transitioning from the abnormal state to the normal state at time t1, the power conditioner control unit 22 acquires the transition remaining charge amount, which is the remaining charge amount of the charge/discharge device 12 at the time of transition from the abnormal state to the normal state, and stores this value in the storage unit 23. Then, as a reverse power flow limiting process, after transitioning from the abnormal state to the normal state, the power conditioner control unit 22 sets the transition remaining charge amount as a provisional lower limit value of the remaining charge amount of the charge/discharge device 12, and permits discharge from the charge/discharge device 12 while keeping the remaining charge amount of the charge/discharge device 12 equal to or greater than the provisional lower limit.

For example, in FIG. 3, in the normal state after time t1, the power conditioner control unit 22 causes the charge/discharge device 12 to charge/discharge within a range in which the remaining charge of the charge/discharge device 12 does not become smaller than the provisional lower limit. By performing such control, even if the charge/discharge device 12 is charged with power originating from the fuel cell device 4 during an abnormal state, the discharged power of the charge/discharge device 12 is not supplied to the power grid 1 during the normal state. In other words, even if power that does not originate from the photovoltaic power generation device 13 is included in the remaining charge at the time of transition, it is guaranteed that the power is not apparently discharged.

Second Embodiment
The power conditioner 20 of the second embodiment differs from the above-mentioned embodiment in the content of the reverse power flow limiting process. The reverse power flow limiting process performed by the power conditioner 20 of the second embodiment will be described below, but a description of the same configuration as the above-mentioned embodiment will be omitted.

Figure 4 is a diagram explaining the reverse power flow limiting process performed by the power conditioner 20 of the second embodiment, and shows an example of the change over time in the remaining charge of the charge/discharge device 12. As shown in the figure, while the remaining charge of the charge/discharge device 12 is increasing in an abnormal state before time t1, the remaining charge may have included power originating from the fuel cell device 4.

Therefore, as a reverse power flow limiting process, after the power conditioner control unit 22 transitions from an abnormal state to a normal state at time t1, the power conditioner control unit 22 consumes power using a specified power load unit to reduce the remaining charge of the charge/discharge device 12 to a discharge lower limit value. For example, after time t1, the power conditioner control unit 22 discharges power from the charge/discharge device 12 while monitoring whether the received power supplied from the power system 1 to the first connection point 5, measured by the power measurement unit 7, is zero or has a positive sign, thereby reducing the remaining charge. In this case, the discharged power of the charge/discharge device 12 is consumed by the power load device 3, which is the above-mentioned power load unit connected to the power line 2. Then, when the remaining charge of the charge/discharge device 12 has decreased to a specified discharge lower limit value, the power conditioner control unit 22 allows the power charged in the charge/discharge device 12 to be supplied to the power system 1. In this way, even if the remaining charge of the charging/discharging device 12 at time t1 includes power originating from the fuel cell device 4, it is guaranteed that all of that power is consumed by the power load section and is not discharged to the power grid 1. Then, it is guaranteed that after time t2, the remaining charge of the charging/discharging device 12 does not include power originating from the fuel cell device 4.

Third Embodiment
The power conditioner 20 of the third embodiment differs from the above-mentioned embodiments in the content of the reverse power flow limiting process. The reverse power flow limiting process performed by the power conditioner 20 of the third embodiment will be described below, but a description of the same configuration as the above-mentioned embodiments will be omitted.

Figure 5 is a diagram explaining the reverse power flow limiting process performed by the power conditioner 20 of the third embodiment, and shows an example of the change over time in the remaining charge of the charge/discharge device 12. As shown in the figure, while the remaining charge of the charge/discharge device 12 is increasing in an abnormal state before time t1, the remaining charge may have included power originating from the fuel cell device 4.

Therefore, after the power conditioner control unit 22 transitions from the abnormal state to the normal state at time t1, it acquires the remaining charge at transition, which is the remaining charge of the charge/discharge device 12 at the time of transition from the abnormal state to the normal state, and stores the value in the storage unit 23. Then, as a reverse power flow limiting process, the power conditioner control unit 22 allows discharge from the charge/discharge device 12 for a predetermined period while keeping the remaining charge of the charge/discharge device 12 equal to or greater than the provisional lower limit, and after the predetermined period has elapsed, it repeats a lower limit value reduction process in which a process is performed to reduce the remaining charge of the charge/discharge device 12 to a new provisional lower limit value that is smaller than the current provisional lower limit value by consuming power using a predetermined power load unit (power load device 3) until the provisional lower limit value becomes the discharge lower limit value of the charge/discharge device 12. Here, the provisional lower limit value after transition from the abnormal state to the normal state is set to the remaining charge at transition.

For example, the power conditioner control unit 22 permits charging and discharging from the charge/discharge device 12 while keeping the remaining charge of the charge/discharge device 12 equal to or greater than the first tentative lower limit between time t1 and time t3 in FIG. 5. Then, after time t3, the power conditioner control unit 22 performs a lower limit reduction process between time t3 and time t4, in which the power conditioner control unit 22 discharges power from the charge/discharge device 12 while monitoring that the received power supplied from the power system 1 to the first connection point 5, as measured by the power measurement unit 7, is zero or has a positive sign, i.e., that no reverse power flow is occurring from the power line 2 to the power system 1.

After the remaining charge of the charge/discharge device 12 reaches the second tentative lower limit at time t4, the power conditioner control unit 22 performs a reverse power flow limiting process by permitting discharge from the charge/discharge device 12 for a predetermined period (between time t4 and time t5) while keeping the remaining charge of the charge/discharge device 12 at or above the second tentative lower limit, and then, after the predetermined period has elapsed, performs a lower limit reduction process between time t5 and time t6 in which a process is performed to reduce the remaining charge of the charge/discharge device 12 to a new tentative lower limit (discharge lower limit) that is smaller than the current second tentative lower limit by consuming power using a predetermined power load unit.

The power conditioner control unit 22 determines that the provisional lower limit value has become the discharge lower limit value of the charge/discharge device 12 at time t6, and ends the reverse power flow limiting process. After the reverse power flow limiting process ends, the power conditioner control unit 22 allows the power stored in the charge/discharge device 12 to be supplied to the power grid 1.

<Another embodiment>
＜1＞
In the above embodiment, specific examples of the configurations of the power conditioner 20 and the power supply system have been given and explained, but these configurations can be changed as appropriate.
For example, although the power supply system has been illustrated as including the fuel cell device 4, it may include other types of power generation devices.

＜2＞
In the above embodiment, the power conditioner 20 may set an permission period during which the discharged power of the charging/discharging device 12 is permitted to be supplied to the power grid 1, and may operate in a state in which the discharged power of the charging/discharging device 12 is not permitted to be supplied to the power grid 1 except during the permission period. This permission period is a period other than the purchase period during which the power generated by the photovoltaic power generation device 13 is purchased under the feed-in tariff system.

For example, during the purchase period of the power generated by the photovoltaic power generation device 13 under the FIT system (feed-in tariff system), it may be required to limit the reverse flow to the power grid 1 to only the power generated by the photovoltaic power generation device 13. In addition, even if the remaining charge of the charge/discharge device 12 is only power originating from the photovoltaic power generation device 13, it may be required to limit the reverse flow of the discharged power of the charge/discharge device 12 to the power grid 1. In such a case, the power conditioner 20 may set an allowed period during which the discharged power of the charge/discharge device 12 is permitted to be supplied to the power grid 1 and store it in the memory unit 23, and may operate in a state in which the discharged power of the charge/discharge device 12 is not permitted to be supplied to the power grid 1 except during the allowed period. The allowed period during which the discharged power of the charge/discharge device 12 is permitted to be supplied to the power grid 1 may be a period other than the feed-in tariff period, i.e., a period after the end of the feed-in tariff period. As a result, the power conditioner 20 prohibits the discharged power of the charging/discharging device 12 from being supplied to the power grid 1 during the feed-in tariff period, and allows the discharged power of the charging/discharging device 12 to be supplied to the power grid 1 after the feed-in tariff period ends.

＜3＞
In the above embodiment, in the case of an abnormal state in which power is not being supplied normally to the power line 2, an example has been described in which the fuel cell device 4 is connected to the power conditioner circuit unit 21 in a state in which it is electrically disconnected from the power grid 1 by connecting the contact c of the first switching unit 10 and the contact b of the second switching unit 11 as shown in Fig. 2, but the manner in which the fuel cell device 4 and the power conditioner circuit unit 21 are connected in the case of an abnormal state can be changed as appropriate. For example, a separate connection line that can directly connect the fuel cell device 4 to the power conditioner circuit unit 21 may be provided, and the two may be electrically connected using the connection line in the case of an abnormal state.

＜4＞
In the above third embodiment, an example was described in which the lower limit lowering process was performed twice, but the number of times the lower limit lowering process is performed until the remaining charge of the charge/discharge device 12 reaches the discharge lower limit can be set appropriately.

＜5＞
In the above embodiment, the power load device 3 connected to the power line 2 is illustrated as an example of a power load unit used to reduce the remaining charge of the charge/discharge device 12 in the reverse flow limiting process, but other devices may also be used as the power load unit.

＜6＞
The configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, provided that no contradiction arises. Furthermore, the embodiments disclosed in this specification are illustrative, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope that does not deviate from the purpose of the present invention.

The present invention can be used in a power conditioner that can ensure that the power flowing back to the power grid originates from the solar power generation device while allowing power originating from a power source other than a solar power generation device to be charged into a charging/discharging device as necessary.

1 Power system 2 Power line 3 Power load device (power load section)
12 Charging/discharging device 13 Photovoltaic power generation device 20 Power conditioner

Claims (7)

A power conditioner that connects a photovoltaic power generation device and a charge/discharge device to a power line that is connected to a power grid,
When in a normal state in which power is normally supplied from the power system to the power line, the system operates in a state in which charging of the charging/discharging device is permitted in a state that satisfies a charge limiting condition that the charging power to the charging/discharging device is equal to or less than the power generation power of the solar power generation device, and does not permit charging of the charging/discharging device in a state in which the charge limiting condition is not satisfied, and permits the discharge power of the charging/discharging device to be supplied to the power system ;
When an abnormal state occurs in which power is not normally supplied from the power system to the power line, permitting charging to the charging/discharging device in a state in which the charging restriction condition is not satisfied;
After the abnormal state transitions to the normal state, the power conditioner performs a reverse flow limiting process that limits the power that was charged in the charging/discharging device during the abnormal state from being supplied to the power grid . A transition state of charge of the charging/discharging device at a time when the abnormal state transitions to the normal state is acquired;
2. The power conditioner of claim 1, wherein, as the reverse power flow limiting process, after transitioning from the abnormal state to the normal state, the remaining charge at the time of transition is set to a provisional lower limit value of the remaining charge of the charging/discharging device, and discharging from the charging/discharging device is permitted while the remaining charge of the charging/discharging device is set to be equal to or greater than the provisional lower limit. 2. The power conditioner of claim 1, wherein, as the reverse power flow limiting process, after transitioning from the abnormal state to the normal state, a predetermined power load unit is used to consume power to reduce the remaining charge of the charging/discharging device to a lower discharge limit value. The power conditioner according to claim 3 , wherein after the reverse power flow limiting process is completed, the power stored in the charge/discharge device is permitted to be supplied to the power grid. A transition state of charge of the charging/discharging device at a time when the abnormal state transitions to the normal state is acquired;
As the reverse flow limiting process,
permitting discharge from the charging/discharging device for a predetermined period while keeping the remaining charge of the charging/discharging device equal to or greater than a tentative lower limit, and after the predetermined period has elapsed, performing a lower limit value reduction process to reduce the remaining charge of the charging/discharging device to a new tentative lower limit value that is smaller than the current tentative lower limit value by consuming power using a predetermined power load unit, said lower limit value reduction process being repeated until said tentative lower limit value becomes a discharge lower limit value of the charging/discharging device;
The power conditioner according to claim 1 , wherein the temporary lower limit value after the state transitions from the abnormal state to the normal state is set to the transition state remaining amount. The power conditioner according to any one of claims 1 to 5, which sets an authorization period during which the discharge power of the charging/discharging device is permitted to be supplied to the power grid, and operates in a state in which the discharge power of the charging/ discharging device is not permitted to be supplied to the power grid outside the authorization period. The power conditioner according to claim 6 , wherein the permission period is a period other than a purchase period during which the power generated by the photovoltaic power generation device is purchased under a feed-in tariff scheme.

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