JP7600574B2 - Battery storage system and method for controlling battery storage system - Google Patents

Description

This disclosure relates to a storage battery system and a method for controlling a storage battery system.

2. Description of the Related Art A battery storage system that is interconnected with a commercial power grid and stores electricity in a battery is sometimes used in combination with a power generation device such as a solar power generation device (see, for example, Patent Document 1).
The battery storage system has a limiting function for limiting reverse power flow to the commercial power grid. To achieve this limiting function, the battery storage system has a current sensor for monitoring the power flow of the output of the system itself.
Furthermore, the battery storage system monitors the power generated by the power generation device in order to control the system itself and to output the power to an operator of the system, and therefore the battery storage system also includes a current sensor required to obtain the power generated by the power generation device.

JP 2013-51834 A

The above-mentioned storage battery system may be additionally installed at a consumer facility where a power generation device is already installed.
Fig. 9 is a diagram showing a conventional configuration in which a storage battery system is installed in a consumer facility in which a power generation device is installed. Fig. 9 shows a case in which the power generation device is operated in a so-called single power generation mode.
Single power generation is an operation mode in which discharge of the storage battery system is limited when the power generation device is supplying generated power to the AC power circuit.

9, a storage battery system 100 is connected to an AC electric circuit 106 that connects a power system 102 and a load 104. The AC electric circuit 106 is a single-phase three-wire system.
The battery storage system 100 includes a power storage device 110 connected between an existing power generation device 108 and a load 104, a current sensor 112 provided between the power system 102 and the power generation device 108, and a current sensor 116 provided on a branch path 114 extending from the AC circuit 106 to the power generation device 108.

The current sensor 112 is a sensor for monitoring the current flow of the output of the system itself, and includes current transformers (CTs) 112u and 112w provided on the U-line and W-line constituting the AC electric circuit 106.
The current sensor 116 is used to determine the generated power of the power generation device 108. The current sensor 116 includes a CT 116a provided in the branch path 114.

When the power generation device 108 is in a single power generation mode, the power generation device 108 does not generate power and the storage device 110 does not discharge power at the same time. Therefore, the current sensor 112 can be used to monitor the current flow of the output of the system itself.

FIG. 10 is a diagram showing a conventional configuration in which a storage battery system is installed in a consumer facility in which a power generation device is installed, and shows a case in which the power generation device is operated in a so-called double power generation mode.
Double power generation is an operation mode that allows the battery system to discharge while the power generation device supplies generated power to the AC circuit.
In the case of double power generation, even when the power generation device 108 is generating power, the power may be discharged from the system. For this reason, a current sensor 112 that monitors the output flow of the system is provided between the power generation device 108 and the power storage device 110. In addition, a current sensor 116 that is used to calculate the generated power of the power generation device 108 is provided between the power grid 102 and the power generation device 108.

In this way, when a storage battery system 100 is additionally installed at a consumer facility where a power generation device is already installed, the installation positions of each current sensor will differ depending on the operating mode of the power generation device (single power generation or double power generation).
In other words, it is necessary to install each current sensor in a position that corresponds to the operation mode of the power generation device. Therefore, there is a possibility that construction errors such as installing each current sensor in an incorrect position may occur. In this case, it is necessary to reinstall each current sensor in an appropriate position, which makes the installation work complicated.

This disclosure has been made in light of these circumstances, and aims to provide a storage battery system that can reduce the occurrence of construction errors.

The battery system according to the embodiment is a battery system that is connected to an AC circuit in which a power generation device is connected between a power grid and a load, and includes a first current sensor that measures the current in a portion of the AC circuit that is closer to the power grid than the connection point of the power generation device, a second current sensor that measures the current in a portion of the AC circuit that is closer to the load than the connection point of the power generation device, a battery, a charge/discharge unit that is connected to the portion of the AC circuit that is closer to the load than the first current sensor and charges/discharges the battery, and a selection unit that selects one of the measurement values of the first current sensor and the second current sensor as a measurement value for monitoring the current flow of the AC circuit when the battery is discharging.

In another embodiment, a control method for a storage battery system is a control method for a storage battery system having a storage battery that is connected to an AC circuit in which a power generation device is connected between a power grid and a load, and includes a selection step of selecting, as a measurement value for monitoring the AC circuit when the storage battery is discharged, one of a measurement value of a first current sensor that measures the current in a portion of the AC circuit closer to the power grid than the connection point of the power generation device and a measurement value of a second current sensor that measures the current in a portion of the AC circuit closer to the load than the connection point of the power generation device, and a discharge control step of controlling the discharge of the storage battery using the measurement value selected in the selection step.

The present disclosure can be realized as a program for causing a computer to execute the steps that are the characteristic processes described above.

This disclosure makes it possible to reduce the occurrence of construction errors.

FIG. 1 is a diagram showing an equipment configuration in a consumer facility in which a storage battery system according to a first embodiment is installed. FIG. 2 is a block diagram showing a configuration example of the power storage device. FIG. 3 is a front view showing an example of an operation panel of a remote controller (hereinafter, referred to as a "remote control"). FIG. 4 is a flowchart showing an example of a process performed by the control device of the present embodiment. FIG. 5 is a diagram showing an example of a selection screen displayed on the liquid crystal display unit. FIG. 6 is a diagram showing the equipment configuration in a consumer facility in which a storage battery system according to the second embodiment is installed. FIG. 7 is a diagram showing the equipment configuration in a consumer facility in which a storage battery system according to the third embodiment is installed. FIG. 8 is a diagram showing the equipment configuration in a consumer facility in which a storage battery system according to the fourth embodiment is installed. FIG. 9 is a diagram showing a conventional configuration in which a storage battery system is installed in a consumer facility in which a power generation device is installed, and shows a case in which the power generation device is operated as a single power generation device. FIG. 10 is a diagram showing a conventional configuration in which a storage battery system is installed in a consumer facility in which a power generation device is installed, and shows a case in which the power generation device is operated in double power generation mode.

First, the contents of the embodiment will be listed and described.
[Overview of the embodiment]
(1) A storage battery system according to an embodiment is a storage battery system that is connected to an AC circuit in which a power generation device is connected between a power grid and a load, and includes a first current sensor that measures a current in a portion of the AC circuit that is closer to the power grid than a connection point of the power generation device, a second current sensor that measures a current in a portion of the AC circuit that is closer to the load than the connection point of the power generation device, a storage battery, a charge/discharge unit that is connected to the portion of the AC circuit that is closer to the load than the first current sensor and charges and discharges the storage battery, and a selection unit that selects one of the measurement value of the first current sensor and the measurement value of the second current sensor as a measurement value for monitoring the current flow of the AC circuit when the storage battery is discharging.

According to the above configuration, the first current sensor is provided closer to the power grid than the connection point of the power generator, and the second current sensor is provided closer to the load than the connection point of the power generator, and the current flow in the AC circuit is monitored based on the measurement value selected by the selection unit, so that after both current sensors are provided in the AC circuit, one of the first current sensor and the second current sensor can be selected as the current sensor for monitoring the current flow in the AC circuit. Furthermore, the measurement value of the other current sensor can be used together with the measurement value of the other current sensor to determine the generated power of the power generator.
In other words, the roles of the first current sensor and the second current sensor can be switched depending on the operation mode of the power generation device (single power generation or double power generation) while leaving the sensor arrangement unchanged.
As a result, regardless of the operation form of the power generation device, the installation positions of the first current sensor and the second current sensor can be standardized, and the occurrence of construction errors such as installing the current sensor in an incorrect position can be suppressed.
Note that single power generation is an operating mode in which discharging of the battery system is restricted when the power generation device is supplying generated power to the AC circuit, and double power generation is an operating mode in which discharging of the battery system is permitted when the power generation device is supplying generated power to the AC circuit.

(2) The above-mentioned storage battery system may further include an input unit that accepts operational input from an operator of the storage battery system, and the selection unit may be configured to select either the measurement value of the first current sensor or the measurement value of the second current sensor in response to the operational input.
In this case, for example, when installing the battery storage system, even if the operating mode of the power generation equipment is unknown, by providing both current sensors to the AC circuit and then providing operational input to the input unit, it is possible to select measurement values appropriate for monitoring the current according to the operating mode of the power generation equipment.
Furthermore, even if it becomes necessary to change the operation mode of the power generation equipment from single generation to double generation, or from double generation to single generation after the storage battery system is installed, by providing operational input to the input unit, it is possible to select appropriate measurement values for monitoring the tide flow according to the operation mode of the power generation equipment.

(3) The above-mentioned storage battery system may further include a calculation unit that calculates the generated power of the power generation device based on the measurement value of the first current sensor and the measurement value of the second current sensor, and an output unit that outputs the generated power of the power generation device.
In this case, the control unit can output the generated power of the power generation device obtained from the measurement value of the first current sensor and the measurement value of the second current sensor to an operator of the system.

(4) In the above-described storage battery system, the output unit may include a display unit that displays and outputs the power generated by the power generation device. In this case, the power generated by the power generation device can be output by display.

(5) In the above storage battery system, the charge/discharge unit may be connected to a portion of the AC current path closer to the load than the second current sensor.
In this case, if the operation mode of the power generation device is single power generation, when the measurement value of the first current sensor indicates reverse flow, it can be determined that the discharged power of the storage battery is flowing reversely.
Furthermore, if the power generation device is operated in a double power generation mode, when the measurement value of the second current sensor indicates reverse power flow, it can be determined that the discharged power of the storage battery is flowing reversely.
Therefore, it is possible to appropriately monitor whether or not the discharged power of the storage battery is flowing in reverse.

(6) In the storage battery system, the charge/discharge unit may be connected between the first current sensor and the second current sensor in the AC current path.
In this case, the power generated by the power generation device can be calculated by subtracting the discharge power of the system from the difference between the power obtained from the measurement value of the first current sensor and the power obtained from the measurement value of the second current sensor. Therefore, it is possible to monitor whether the power of the storage battery is flowing in reverse based on the power generated by the power generation device and the measurement value of the first current sensor.
In addition, when switching the measurement value for monitoring the power flow of the AC circuit from that of the first current sensor to that of the second current sensor, it is possible to monitor whether the power of the storage battery is flowing in reverse by changing only the position of the second current sensor while leaving the position of the first current sensor as it is. This prevents the installation positions of the two current sensors from being confused, and suppresses the occurrence of construction errors such as installing the two current sensors in the wrong positions.

(7) In the above storage battery system, the AC circuit may be a single-phase three-wire circuit including a neutral wire, and either the first current sensor or the second current sensor may include two sensor elements that detect current flowing through two power lines other than the neutral wire, and the other of the first current sensor or the second current sensor may include one sensor element that detects current flowing through one of the two power lines other than the neutral wire to which the power generation device is connected.
In this case, of the first current sensor and the second current sensor, the current sensor used as the current sensor for monitoring the power flow of the AC current path needs to detect the currents flowing through the two power lines.
On the other hand, for a current sensor used to calculate the power generated by a power generator, the power generated by the power generator can be calculated by providing a sensor element on one of the two power lines other than the neutral line to which the power generator is connected. In this case, the number of sensor elements can be reduced compared to when sensor elements are provided on both of the two power lines other than the neutral line.

(8) The above-mentioned battery storage system may include a plurality of the power generation devices. In this case, the power generated by the plurality of power generation devices can be calculated by adding them together.

(9) Another embodiment of a control method for a storage battery system is a control method for a storage battery system having a storage battery that is connected to an AC circuit in which a power generation device is connected between a power grid and a load, and includes a selection step of selecting one of a measurement value of a first current sensor that measures the current in a portion of the AC circuit that is closer to the power grid than the connection point of the power generation device and a measurement value of a second current sensor that measures the current in a portion of the AC circuit that is closer to the load than the connection point of the power generation device as a measurement value for monitoring the AC circuit when the storage battery is discharged, and a discharge control step of controlling the discharge of the storage battery using the measurement value selected by the selection step.

[Details of the embodiment]
Hereinafter, preferred embodiments will be described with reference to the drawings.
At least a part of each of the embodiments described below may be combined in any manner.
[Regarding the first embodiment]
FIG. 1 is a diagram showing an equipment configuration in a consumer facility in which a storage battery system according to a first embodiment is installed.
In FIG. 1, a storage battery system 1 is connected to an AC circuit 6 that connects a single-phase three-wire commercial power system 2 and a load 4 at a consumer facility.
The AC electric circuit 6 includes three power lines: a U line, an O line (neutral line), and a W line.

The consumer load 4 includes a load connected to the U phase (between the U- and O-lines), a load connected to the W phase (between the W- and O-lines), and a load connected to the U- and W-lines.
In the following description, the commercial power system 2 side of the AC circuit 6 is referred to as the "upstream" side, and the load 4 side is referred to as the "downstream" side.

In addition to the storage battery system 1 , a first power generation device 8 and a second power generation device 10 are connected to the AC circuit 6 .
The first power generation device 8 is, for example, a solar power generation device, and is connected between the UW lines.
The second power generation unit 10 is, for example, a home cogeneration system equipped with a fuel cell power generation unit, and is connected between lines W and O.
The first power generating device 8 and the second power generating device 10 each include a power conditioner (not shown) for interconnecting with the commercial power grid 2, and a power generating unit (not shown) for generating power. The power generated by the power generating unit is configured to be supplied to the load 4 via the AC circuit 6.

The storage battery system 1 includes a power storage device 14 , a first current sensor 16 , a second current sensor 18 , and a remote control 20 .
The first current sensor 16 and the second current sensor 18 are provided in the AC circuit 6 .
The first current sensor 16 is provided upstream (on the commercial power system 2 side) of the connection points 8u, 8w of the first power generation device 8. In other words, the first current sensor 16 is provided between the commercial power system 2 and the connection points 8u, 8w of the first power generation device 8. Thus, the first current sensor 16 detects the current flowing between the commercial power system 2 and the connection points 8u, 8w.
The first current sensor 16 includes a sensor element 16u provided on the U line and a sensor element 16w provided on the W line. The sensor elements 16u and 16w detect the currents flowing through the U line and the W line.
The sensor elements 16u and 16w are connected to the power storage device 14. The sensor elements 16u and 16w provide outputs (measurement values) indicating the results of detecting the current to the power storage device 14. The measurement values of the sensor elements 16u and 16w include information indicating the current value of the current flowing through the AC circuit 6 (the U line and the W line) and information indicating the power flow of the current.

The second current sensor 18 is provided downstream (toward the load 4) of the connection point 10w of the second power generation device 10 that is connected to the downstream side of the first power generation device 8. In other words, the second current sensor 18 is provided between the connection points 8u, 10w and the load 4. Therefore, the second current sensor 18 detects a current flowing between the connection points 8u, 10w and the load 4.
The second current sensor 18 includes a sensor element 18u provided on the U line and a sensor element 18w provided on the W line. The sensor elements 18u and 18w detect the currents flowing through the U line and the W line.
The sensor elements 18u and 18w are connected to the power storage device 14. The sensor elements 18u and 18w provide outputs (measurement values) indicating the results of detecting the current to the power storage device 14. The measurement values of the sensor elements 18u and 18w include information indicating the current value of the current flowing through the AC circuit 6 (the U line and the W line) and information indicating the power flow of the current.

Sensor elements 16u, 16w, 18u, and 18w may, for example, be configured as clamp-type CTs (Current Transformers). If sensor elements 16u, 16w, 18u, and 18w are configured as clamp-type CTs, they can be easily attached and detached.

The power storage device 14 is connected downstream (toward the load 4) of the second current sensor 18. In other words, the power storage device 14 is connected between the second current sensor 18 and the load 4.

FIG. 2 is a block diagram showing an example of the configuration of the power storage device 14. As shown in FIG.
In FIG. 2 , the power storage device 14 includes a storage battery 24 , a power conversion unit 26 , and a control device 28 .
The storage battery 24 is, for example, a lithium ion battery. The storage battery 24 is connected to the AC circuit 6 via a power conversion unit 26.
The power conversion unit 26 has a bidirectional inverter circuit and a DC/DC converter built in. The power conversion unit 26 is connected to the AC power line 6, and has a function as a charge/discharge unit that is interconnected with the AC power line 6 and performs power conversion to charge and discharge the storage battery 24.
The power conversion unit 26 performs power conversion from DC to AC when discharging power from the storage battery, and performs power conversion from AC to DC when charging power to the storage battery.

Moreover, the power conversion unit 26 provides the control device 28 with information on the voltage, current, etc. that the power conversion unit 26 detects for power conversion.
The control device 28 controls the power conversion unit 26 based on information from the power conversion unit 26 in addition to the measured values from the first current sensor 16 and the second current sensor 18 .
The information from the power conversion unit 26 includes the current value of the current flowing through the branch lines 14 u and 14 w connecting the power conversion unit 26 and the AC circuit 6 , and the voltage of the AC circuit 6 .

The control device 28 has a function of controlling the power conversion unit 26 and controlling the charging and discharging of the storage battery 24 by the power conversion unit 26. The control device 28 is configured to perform load following control based on the measurement values from the first current sensor 16 and the second current sensor 18 and information from the power conversion unit 26 so that the discharged power of the system 1 (storage battery 24) is not reversed.

The control device 28 functionally includes a selection unit 28a and a calculation unit 28c.
The selection unit 28a has the function of selecting either the measurement value of the first current sensor 16 or the measurement value of the second current sensor 18 as the measurement value for monitoring the current flow in the AC circuit 6 when the storage battery 24 is discharging.
The measurement value selected by the selection unit 28 a is used to monitor the reverse flow of power from the storage battery 24 .
The calculation unit 28c has the function of calculating information to be output to the operator of the system 1, such as the generated power of the power generation devices 8, 10 and the purchased and sold power, based on the measurement values from the first current sensor 16 and the second current sensor 18 and information from the power conversion unit 26.

The control device 28 may be configured by a computer having a processor such as a CPU (Central Processing Unit) and a storage unit, or may be configured by a hardware circuit capable of realizing some or all of the functions of the control device 28. The control device 28 may also be configured by combining the computer and the hardware circuit. When the control device 28 includes a computer, the storage unit stores a computer program to be executed by the CPU, etc. The CPU realizes each of the above-mentioned functional units of the control device 28 by reading the computer program recorded on a computer-readable non-transitory recording medium such as the storage unit.

The remote control 20 is connected to the power storage device 14 by wire or wirelessly, and is installed inside a consumer's home or the like. Therefore, the remote control 20 has a housing separate from the power storage device 14. The remote control 20 has an input unit 20a that accepts operation input by an operator of the system 1, and an output unit 20b that displays various information to output to the operator.
FIG. 3 is a front view showing an example of an operation panel of the remote control 20. As shown in FIG.
As shown in FIG. 3, an operation panel 30 of the remote control 20 is provided with an operation switch group 32 including a plurality of operation switches operated by an operator, a liquid crystal display unit 34, and four display changeover switches 36.
The input unit 20a (FIG. 2) includes an operation switch group 32 and a control unit (not shown) that controls the operation switch group 32. The operation switch group 32 accepts operation inputs by an operator. The control unit of the operation switch group 32 gives the control device 28 a command corresponding to the accepted operation input by the operator.
The control device 28 that receives the command performs an operation based on the command.

The output section 20b (FIG. 2) includes the liquid crystal display section 34 of the operation panel 22 and four display changeover switches 36.
The liquid crystal display unit 34 outputs a display based on a command from the control device 28. Furthermore, when the liquid crystal display unit 34 receives information related to power provided from the control device 28, it displays the information related to power. The four display changeover switches 36 correspond to the power generated in the consumer's facility, the power consumed, the power bought and sold, and the power charged and discharged by the storage battery 10b. When any of the four display changeover switches 36 is operated by an operator, the liquid crystal display unit 34 displays and outputs the power value corresponding to the operated display changeover switch 36.

As described above, the calculation unit 28c calculates the values of each type of power (generated power, consumed power, purchased and sold power, and charging and discharging power of the storage battery 24) within the consumer in which the system 1 is installed, based on information from the first current sensor 16, the second current sensor 18, and the power conversion unit 26.

Here, the grid power Pgrid, which is the power exchanged between the commercial power grid 2 and the consumer, is calculated from the measurement value (current value) of the first current sensor 16 and the voltage of the AC circuit 6 obtained from the power conversion unit 26. In other words, the grid power Pgrid is calculated by adding up the power calculated from both the sensor element 16u and the sensor element 16w. This grid power Pgrid indicates the power being bought and sold.

Moreover, the generated current of the power generation devices 8 and 10 is obtained by subtracting the current value indicated by the measurement value of the second current sensor 18 from the current value indicated by the measurement value of the first current sensor 16 .
Therefore, the generated power Ppv of the power generation device is calculated from the generated current value of the power generation device 8, 10 obtained based on the measurement value of the first current sensor 16 and the measurement value of the second current sensor 18, and the voltage of the AC circuit 6 obtained from the power conversion unit 26. The generated power Ppv is calculated by subtracting the combined value of the power obtained from both sensor elements 18u and 18w from the combined value of the power obtained from both sensor elements 16u and 16w.
The generated power Ppv is the sum of the generated power of the first power generating unit 8 and the generated power of the second power generating unit 10 .

The charging/discharging power Pinv of the storage battery 24 is obtained from the power conversion unit 26 .
The power consumption Pload of the load 4 is calculated by the following formula.
Power consumption Pload = Pgrid + Ppv + Pinv

It should be noted that the above values Pgrid, Ppv, Pinv, and Pload each have a positive value when a current flows in the direction of the arrow shown in FIG.
That is, the grid power Pgrid (traded power) indicates a positive value when the current is in the forward flow.
Moreover, the generated power Ppv indicates a positive value when power is being generated.
Moreover, the charge/discharge power Pinv indicates a positive value during discharging.

The calculation unit 28c causes the liquid crystal display unit 34 of the remote control 20 to display the various power values thus determined.
This allows the control device 28 to output the generated power of the power generation devices 8, 10 obtained from the measurement value of the first current sensor 16 and the measurement value of the second current sensor 18 to the operator.

In addition, in this embodiment, multiple power generation devices (power generation devices 8, 10) are provided between the first current sensor 16 and the second current sensor 18, so the generated power Ppv based on the measured values of the first current sensor 16 and the second current sensor 18 can be obtained as the sum of the generated power of the first power generation device 8 and the generated power of the second power generation device 10.

In addition, since the first current sensor 16 and the second current sensor 18 in this embodiment both include sensor elements provided on both the U line and the W line, even if the first power generating device 8 connected between the U-W lines and the second power generating device 10 connected between the W-O lines are both connected to the AC circuit 6, it is possible to detect the current generated by both power generating devices 8, 10, and to calculate the generated power Ppv, which is the sum of the generated power of the first power generating device 8 and the generated power of the second power generating device 10.

FIG. 4 is a flowchart showing an example of a process performed by the control device 28 of the present embodiment.
The control device 28 charges and discharges the storage battery 24 depending on the situation, but FIG. 4 only describes a case where the control device 28 causes the storage battery 24 to discharge power.
First, when an operator of the system 1 starts up the system 1 from a stopped state, the control device 28 causes the liquid crystal display unit 34 of the remote control 20 to display a selection screen for allowing the operator to select whether the operation mode of the power generation units 8, 10 is single power generation or double power generation (step S1 in Figure 4), and accepts operation input by the operator via the remote control 20 (step S2 in Figure 4).

FIG. 5 is a diagram showing an example of a selection screen displayed on the liquid crystal display unit 34. As shown in FIG.
5 includes a single power generation display 40a indicating one option, "single power generation," and a double power generation display 40b indicating the other option, "double power generation." Either one of the displays 40a, 40b has a selection display 40c indicating that the other one has been selected.
The selection display 40c is a rectangular display surrounding either one of the displays 40a, 40b. In Fig. 5, the single power generation display 40a is surrounded by the selection display 40c, which indicates that the single power generation display 40a is selected.
The selection display 40c can be switched by the operator operating the operation switch group 32 to select either of the displays 40a, 40b.

When the operator performs an operation to confirm the selection while the single power generation display 40a is selected, the control unit that controls the operation switch group 32 provides information indicating that the single power generation display 40a has been selected to the control device 28. Also, when the operator performs an operation to confirm the selection while the double power generation display 40b is selected, the control unit provides information indicating that the double power generation display 40b has been selected to the control device 28.
In this way, the present system 1 displays a selection screen on the LCD display unit 34 to allow the operator to select whether the operation mode of the power generation devices 8, 10 is single generation or double generation, and accepts the operation input selected by the operator (single generation or double generation) via the operation switch group 32.
Here, a case where single power generation is selected will be described.

Note that single power generation refers to an operation mode in which discharging of the storage battery system 1 is restricted when the power generation devices 8 and 10 are supplying generated power to the AC power circuit 6 .
Further, double power generation is an operation mode in which the storage battery system 1 is permitted to discharge while the power generation devices 8 and 10 are supplying generated power to the AC circuit 6. In either operation mode, reverse flow of the discharged power of the storage battery 24 to the commercial power grid 2 is restricted.
The operation of the power generation devices 8 and 10 is determined by a contract or the like with the electric power company that manages the commercial power system 2 .

Returning to FIG. 4, when an operational input to select single power generation is received in step S2, the selection unit 28a of the control device 28 selects the first current sensor 16 as the sensor to be used for monitoring the current of the AC power path 6 (step S3 in FIG. 4).
In the subsequent processes, the selector 28 a uses the measurement value of the first current sensor 16 as the measurement value to be used for monitoring the power flow of the AC power line 6 .
When an operational input to select double power generation is received in step S2, the selector 28a of the control device 28 selects the second current sensor 18 as the sensor to be used for monitoring the power flow of the AC power path 6.

Next, the control device 28 acquires the measured values of the first current sensor 16 and the second current sensor 18 and information from the power conversion unit 26 (step S4 in FIG. 4), and causes the storage battery 24 to discharge (step S5).
The control device 28 controls the discharge of the storage battery 24 based on the measurement values obtained in step S4 and information from the power conversion unit 26.

In step S5, the control device 28 performs load following control so that the discharged power of the storage battery 24 does not flow backward.
In this case, the control device 28 controls the discharge of the storage battery 24 based on the measurement value of the first current sensor 16 selected by the selector 28a as the power flow monitoring sensor.
Here, since single power generation is selected, the power generation devices 8 and 10 are not generating power in principle when discharging the storage battery 24. Therefore, the control device 28 performs control so that the power flow indicated by the measurement value of the first current sensor 16 does not become a reverse power flow. This is because if the power flow indicated by the measurement value of the first current sensor 16 becomes a reverse power flow, this indicates that the discharged power of the storage battery 24 is flowing in reverse.

For example, the control device 28 controls the discharge of the storage battery 24 so that the measured value of the first current sensor 16 is in the range of 5% or more of the power consumption Pload of the load 4, resulting in a forward current flow. This makes it possible to prevent the discharged power of the storage battery 24 from flowing in reverse due to errors that occur during control.

Here, when single power generation is selected, the selection unit 28a selects the first current sensor 16 (its measurement value) because it is preferable to monitor the power flow of the AC circuit 6 at a location closer to the commercial power system 2.
When single power generation is selected, the first current sensor 16, which is upstream of the second current sensor 18, is selected as the sensor for monitoring the power flow. Therefore, even if the power generation devices 8, 10 are discharging power into the storage battery 24 while generating power, it is possible to determine whether the discharged power of the storage battery 24 is flowing in reverse based on the measurement value of the first current sensor 16.
For this reason, when single power generation is selected, the first current sensor 16 is selected by the selection unit 28a.

After completing step S5, the control device 28 returns to step S4 and repeats the same process.
In this manner, the control device 28 controls the discharging of the storage battery 24 by the power conversion unit 26 .

In the above description, the case where single power generation is selected has been described. The case where double power generation is selected will now be described.
As described above, when an operational input to select double power generation is received in step S2, the selection unit 28a of the control device 28 selects the second current sensor 18 as the sensor to be used for monitoring the current of the AC circuit 6 (step S3 in Figure 4).
In the subsequent processes, the selector 28 a uses the measurement value of the second current sensor 18 as the measurement value to be used for monitoring the power flow of the AC power line 6 .

Next, the control device 28 of the control device 28 acquires the measured values of the first current sensor 16 and the second current sensor 18 and information from the power conversion unit 26 (step S4 in FIG. 4), and causes the storage battery 24 to discharge (step S5).

In step S5, the control device 28 performs load following control so that the discharged power of the storage battery 24 does not flow backward.
In this case, the control device 28 controls the discharge of the storage battery 24 based on the measurement value of the second current sensor 18 selected by the selection unit 28a as the power flow monitoring sensor.
The power storage device 14 and the load 4 are connected downstream of the second current sensor 18. Therefore, the control device 28 performs control so that the power flow indicated by the second current sensor 18 does not become reverse power. This is because, regardless of the generated power of the power generation devices 8, 10, if the measured value indicated by the second current sensor 18 becomes reverse power flow, it indicates that the discharged power of the storage battery 24 is flowing reversely.
Therefore, when double power generation is selected, the second current sensor 18 is selected by the selection unit 28a.

Even when double power generation is selected, the control device 28 controls the discharge of the storage battery 24 so that the measurement value of the second current sensor 18 is in the range of 5% or more of the power consumption Pload of the load 4 and the forward current flow is achieved.

According to the storage battery system 1 configured as described above, the first current sensor 16 is provided on the commercial power system 2 side of the connection points 8u, 8w of the first power generation device 8, the second current sensor 18 is provided on the load 4 side of the connection point 10w of the second power generation device 10, and the current flow of the AC circuit 6 is monitored based on the measurement value selected by the selection unit 28a, so that after both current sensors 16, 18 are provided on the AC circuit 6, either one of the first current sensor 16 and the second current sensor 18 can be selected as the current sensor for monitoring the current flow of the AC circuit 6. Furthermore, the measurement value of the other current sensor can be used, together with the measurement value of one current sensor, to obtain the generated power of the power generation devices 8, 10.
In other words, the positions of the first current sensor 16 and the second current sensor 18 can be left unchanged, but the roles of the first current sensor 16 and the second current sensor 18 can be switched depending on the operation mode (single power generation or double power generation) of the power generation devices 8, 10.
As a result, regardless of the operation form of the power generation devices 8, 10, the installation positions of the first current sensor 16 and the second current sensor 18 can be standardized, thereby preventing the occurrence of construction errors such as installing the current sensor in an incorrect position.

In other words, to install the storage battery system 1 at a consumer's facility, the first current sensor 16 is provided closer to the commercial power grid 2 than the power generation devices 8 and 10, and the second current sensor 18 is provided closer to the load 4 than the power generation devices 8 and 10. After providing both current sensors 16 and 18, an input is given to the control device 28 to select either the measurement value of the first current sensor 16 or the measurement value of the second current sensor 18, and the selection unit 28a is caused to select either the measurement value of the first current sensor 16 or the measurement value of the second current sensor 18 as the measurement value to be used in controlling the discharge of the storage battery 24.

In addition, in this embodiment, the selection unit 28a is configured to select either the measurement value of the first current sensor 16 or the measurement value of the second current sensor 18 as the measurement value to be used for discharge control of the power conversion unit 26, in response to an operational input by an operator received by the input unit 20a (operation switch group 32).
Therefore, for example, when installing the storage battery system 1 at a consumer's premises where power generation devices 8, 10 are already installed, even if the operation mode of the power generation devices 8, 10 is unknown, by providing both current sensors 16, 18 to the AC circuit 6 and then providing operational input to the operation switch group 32, it is possible to select a measurement value (current sensor) appropriate for monitoring the current depending on the operation mode of the power generation devices.
Furthermore, even if it becomes necessary to change the operation mode of the power generation equipment from single generation to double generation, or from double generation to single generation after the storage battery system is installed, by providing operational input to the operation switch group 32, it is possible to select a measurement value (current sensor) appropriate for monitoring the tidal current in accordance with the operation of the power generation equipment 8, 10.

In addition, in this embodiment, the power conversion unit 26 is connected between the second current sensor 18 and the load 4 , and is connected downstream of the second current sensor 18 (on the load 4 side).
In this case, if the operation mode of the power generation devices 8, 10 is single power generation, when the measurement value of the first current sensor 16 indicates reverse flow, it can be determined that the discharged power of the storage battery 24 is reverse flow. Also, if the operation mode of the power generation devices 8, 10 is double power generation, when the measurement value of the second current sensor 18 indicates reverse flow, it can be determined that the discharged power of the storage battery 24 is reverse flow.
Therefore, it is possible to appropriately monitor whether or not the discharged power of the storage battery 24 is flowing in reverse.

[Regarding the second embodiment]
FIG. 6 is a diagram showing the equipment configuration in a consumer facility in which a storage battery system 1 according to the second embodiment is installed.
This embodiment differs from the first embodiment in that the power storage device 14 is connected between the second power generation device 10 and a second current sensor 18 .

In this embodiment, the power generation devices 8 and 10 as well as the power storage device 14 are connected between the first current sensor 16 and the second current sensor 18 .
In this case, the generated power Ppv of the power generation devices 8, 10 can be calculated using a current value obtained by subtracting the current value based on the measurement value of the second current sensor 18 and the current value of the current discharged from the storage device 14 from the current value based on the measurement value of the first current sensor 16.

Therefore, in the case of single power generation, it is possible to monitor whether or not the power of the storage battery 24 is flowing in reverse, based on the power generated by the power generation devices 8 and 10 and the measurement value of the first current sensor 16 .
In addition, when changing the operational mode of the power generation devices 8, 10 from single power generation to double power generation and switching the current sensor for monitoring the current flow of the AC circuit 6 from the first current sensor 16 to the second current sensor 18, it is necessary to position the second current sensor 18 downstream of the storage device 14.
In this embodiment, by changing the location of the second current sensor 18 while leaving the location of the first current sensor 16 unchanged, it is possible to monitor the flow of discharged power from the storage battery 24. Therefore, there is no confusion about the installation positions of the two current sensors 16, 18, and it is possible to suppress the occurrence of construction errors such as installing the two current sensors 16, 18 in incorrect positions.

[Regarding the third embodiment]
FIG. 7 is a diagram showing an equipment configuration in a consumer facility in which a storage battery system 1 according to the third embodiment is installed.
This embodiment differs from the first embodiment in that a second power generating device 10 is connected between the UW lines, and in that a second current sensor 18 includes only a sensor element 18u.

In FIG. 7 , the operation mode of the power generation devices 8 and 10 is single power generation, and the first current sensor 16 is selected as the current sensor for monitoring the power flow of the AC power line 6 .
In this embodiment, the first current sensor 16 includes two sensor elements 16u and 16w that detect the currents flowing through the two power lines other than the O line (neutral line). The second current sensor 18 used to calculate the power generated by the power generation devices 8 and 10 includes one sensor element 18u that detects the current flowing through the U line to which the power generation devices 8 and 10 are connected.

In this embodiment, since the first power generating device 8 and the second power generating device 10 are both connected between the U-W lines, even if the second current sensor 18 includes only the sensor element 18u, the power generation power Ppv of the power generating devices 8 and 10 can be calculated from the difference between the current value based on the measurement value of the first current sensor 16 (sensor elements 16u, 16w) and the current value based on the measurement value of the second current sensor 18 (sensor element 18u).

In this manner, the current sensor (first current sensor 16) used as a current sensor for monitoring the power flow of the AC power line 6 needs to detect the current flowing through the U line and the W line.
On the other hand, with regard to the current sensor (second current sensor 18) used to determine the power generated by the power generation devices 8, 10, the power generated by the power generation devices 8, 10 can be determined by providing a sensor element in either one of the two power lines (U line or W line) other than the neutral line to which the power generation devices 8, 10 are connected.
Therefore, according to this embodiment, the number of sensor elements can be reduced compared to the first embodiment, in which both the first current sensor 16 and the second current sensor 18 include sensor elements 16u, 16w, 18u, and 18w that detect the currents flowing through the U line and the W line.

In addition, when the operational mode of the power generation devices 8, 10 is changed from single power generation to double power generation and the current sensor for monitoring the current flow of the AC circuit 6 is switched from the first current sensor 16 to the second current sensor 18, it is necessary to add a sensor element 18w provided on the W line as a component of the second current sensor 18.
In contrast, in the present embodiment, the arrangement of the sensor elements 18u of the first current sensor 16 and the second current sensor 18 remains the same, and only the sensor element 18w is provided, so there is no confusion about the installation positions of the two current sensors 16, 18, and the occurrence of construction errors such as installing the two current sensors 16, 18 in incorrect positions can be suppressed.

[Regarding the Fourth Embodiment]
FIG. 8 is a diagram showing the equipment configuration in a consumer facility in which a storage battery system 1 according to the fourth embodiment is installed.
This embodiment differs from the first embodiment in that the power generation device 11 is connected between the lines W and O, and in that the first current sensor 16 is configured to include only a sensor element 16w.

In FIG. 8 , the operation mode of the power generation device 11 is double power generation, and the second current sensor 18 is selected as the current sensor for monitoring the power flow of the AC power line 6 .
In this embodiment, the second current sensor 18 includes two sensor elements 18u and 18w that detect the currents flowing through the two power lines other than the O line (neutral line). The first current sensor 16 used to calculate the power generated by the power generation device 11 includes one sensor element 16w that detects the current flowing through the W line to which the power generation device 11 is connected.

In this embodiment, since the power generation device 11 is connected between the W-O lines, even if the first current sensor 16 includes only the sensor element 16w, the power generation power Ppv of the power generation device 11 can be calculated from the difference between the current value based on the measurement value of the first current sensor 16 (sensor element 16w) and the current value based on the measurement value of the second current sensor 18 (sensor element 18w).

In the case of this embodiment, as in the third embodiment, the number of sensor elements can be reduced compared to the case where both the first current sensor 16 and the second current sensor 18 include sensor elements 16u, 16w, 18u, and 18w that detect the currents flowing through the U line and the W line.

In this embodiment, when the current sensor for monitoring the current flow of the AC circuit 6 is switched from the second current sensor 18 to the first current sensor 16 in response to changing the operating mode of the power generation device 11 from double power generation to single power generation, the arrangement of the sensor element 16w of the first current sensor 16 and the second current sensor 18 remains the same, and a sensor element 16u for detecting the current of the U line is provided in the first current sensor 16. This prevents confusion over the installation positions of the two current sensors 16, 18, and suppresses the occurrence of construction errors such as installing the two current sensors 16, 18 in the wrong positions.

〔others〕
It should be noted that the embodiments disclosed herein are illustrative in all respects and are not restrictive.
In each of the above embodiments, the case where the system is interconnected to a single-phase three-wire commercial power system 2 has been described, but the system may also be configured to be interconnected to a single-phase two-wire power system.

In addition, in each of the above embodiments, the selection unit 28a is configured to select one of the measurement values of the first current sensor 16 and the measurement value of the second current sensor 18 as the measurement value to be used for the discharge control of the power conversion unit 26 in response to an operation input by an operator received by the input unit 20a (operation switch group 32). However, this is not limited to this. For example, if the power storage device 14 is equipped with a communication device such as a mobile communication device for communicating with an external device other than the remote control 20, the selection unit 28a can be configured to select one of the measurement values of the first current sensor 16 and the measurement value of the second current sensor 18 in response to a command given from the external device via the communication device.

In addition, in each of the above embodiments, the output unit 20b outputs the power value by displaying it on the liquid crystal display unit 34, but if a speaker, printer, or the like is provided, the power value may be output by voice or printing. Furthermore, the display unit that displays the power value may be configured to include a display device other than a liquid crystal device.

The scope of the present invention is indicated by the claims, not by the meaning described above, and is intended to include all modifications within the scope of the claims and meanings equivalent thereto.

1 Storage battery system 2 Commercial power system 4 Load 6 AC circuit 8 First power generation device 8u Connection point 8w Connection point 10 Second power generation device 10b Storage battery 10w Connection point 11 Power generation device 14 Storage battery 14u Branch line 14w Branch line 16 First current sensor 16u Sensor element 16w Sensor element 18 Second current sensor 18u Sensor element 18w Sensor element 20 Remote control 20a Input section 20b Output section 22 Operation panel 24 Storage battery 26 Power conversion section (charging/discharging section)
28 Control device 28a Selection unit 28c Calculation unit 30 Operation panel 32 Operation switch group 34 Liquid crystal display unit 36 Display changeover switch 40 Selection screen 40a Single power generation display 40b Double power generation display 40c Selection display Pgrid System power Pinv Charge/discharge power Pload Power consumption Ppv Generated power

Claims (5)

A storage battery system that is connected to an AC circuit having a power generation device that allows reverse power flow to the power system between a power system and a load,
a first current sensor that measures a current in a portion of the AC current circuit that is closer to the power grid than a connection point of the power generation device;
a second current sensor that measures a current in a portion of the AC current circuit that is closer to the load than a connection point of the power generation device;
A storage battery,
a charge/discharge unit connected to a portion of the AC current path closer to the load than the first current sensor, and configured to charge and discharge the storage battery;
a selection unit that selects, depending on whether an operation mode of the storage battery system is a first operation mode that limits discharging of the storage battery system when power generated by the power generation device is supplied to the AC electric circuit, or a second operation mode that allows discharging of the storage battery system when power generated by the power generation device is supplied to the AC electric circuit, a measurement value of the first current sensor in the first operation mode and a measurement value of the second current sensor in the second operation mode, as a measurement value for monitoring the current flow of the AC electric circuit when the storage battery is discharging,
When the operation mode of the storage battery system is the first operation mode, the second current sensor is disposed to measure a current in a portion of the AC current path on the load side relative to a portion to which the charge/discharge unit is connected,
When the operation mode of the storage battery system is the second operation mode, the second current sensor is arranged to measure the current between the part of the AC circuit to which the charging/discharging unit is connected and the connection point of the power generation device. a calculation unit that calculates a generated power of the power generation device based on a measurement value of the first current sensor and a measurement value of the second current sensor;
The battery system according to claim 1 , further comprising: an output unit that outputs the generated power of the power generation device. The storage battery system according to claim 2 , wherein the output unit includes a display unit that displays and outputs the generated power of the power generation device. The battery system according to claim 1 , further comprising a plurality of the power generation devices. A control method for a storage battery system having a storage battery connected to an AC circuit connected to a power generation device that allows reverse power flow to the power system between a power grid and a load, comprising:
a selection step of selecting, depending on whether an operation mode of the storage battery system is a first operation mode that limits discharge of the storage battery system when power generated by the power generation device is supplied to the AC electric circuit, or a second operation mode that allows discharge of the storage battery system when power generated by the power generation device is supplied to the AC electric circuit, a measurement value of a first current sensor that measures a current in a portion of the AC electric circuit closer to the power grid than a connection point of the power generation device in the first operation mode, and a measurement value of a second current sensor that measures a current in a portion of the AC electric circuit closer to the load than a connection point of the power generation device in the second operation mode, as a measurement value for monitoring the AC electric circuit when the storage battery is discharging;
a discharge control step of controlling discharge of the storage battery by using the measurement value selected by the selection step,
When the operation mode of the storage battery system is the first operation mode, the second current sensor is disposed to measure a current in a portion of the AC current path on the load side relative to a portion to which the charge/discharge unit is connected,
A control method for a storage battery system, wherein, when the operation mode of the storage battery system is the second operation mode, the second current sensor is arranged to measure the current between a portion of the AC circuit to which the charging/discharging unit is connected and a connection point of the power generation device.

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