JP7342927B2 - storage battery device - Google Patents

Description

The present disclosure relates to a power storage system.

BACKGROUND ART A power storage system is known that is connected to a power grid and can supply power once stored in a storage battery to a load via a power conversion device during a power outage or the like. Energy storage systems that are also connected to solar power generation systems and store the generated electricity are also known. In such a power storage system, once a power storage system with a predetermined capacity is installed, it may become necessary to store a large amount of power for some reason. Patent Document 1, mentioned below, discloses a technology that can easily increase the capacity of a backup power supply system after installation in an existing solar power generation system.

Referring to FIG. 1, a power storage system including a power storage unit 900 is connected to a power grid 910, and receives power supplied from the power grid 910 via a power conditioner (hereinafter referred to as a PCS (Power Conditioning System)). Converts alternating current to direct current and stores it in a storage battery (lithium ion secondary battery, etc.). The power stored in the storage battery is controlled by a remote controller (hereinafter referred to as remote control) 904, and is converted from direct current to alternating current by a PCS as needed, and is supplied to a load 912, which is an electrical appliance in a home or the like. Reverse flow detection CT sensors 906 and 908 are CT sensors for monitoring reverse flow in which current flows to the power system 910 side. Reverse current detection CT sensors 906 and 908 detect the current (alternating current) flowing through the installed power distribution line, and transmit corresponding information (current value, etc.) to power storage unit 900. Before supplying power, power storage unit 900 calculates power consumed by load 912 from information from reverse flow detection CT sensors 906 and 908. The power storage unit 900 uses a charging/discharging command value (hereinafter also simply referred to as a "command value") so that the power supplied from the power system 910 reaches the target value of purchased power set in advance in the power storage unit 900 by the remote controller 904. ) to determine. The PCS charges and discharges the storage battery according to the determined command value. For example, if the target power purchase value is 50W (watts) and the power consumed by load 912 is 500W, there will be a shortage of 450W (50W - 500W = -450W), so 450W will be transferred from power storage unit 900 to load 912. As supplied, the command value is set to 450W.

When power is being supplied from the power storage unit 900, the total value of the power calculated from the information of the reverse flow detection CT sensors 906 and 908 and the power being supplied by the power storage unit 900 is the power consumption of the load 912. Therefore, if the power calculated from the information of the reverse flow detection CT sensors 906 and 908, that is, the purchased power, falls below the target value, the power storage unit 900 adjusts the supplied power (command value) so that the purchased power reaches the target value. ) decrease.

In the existing power storage system shown in FIG. 1, an expansion unit consisting only of storage batteries is added to increase the power storage capacity. Referring to FIG. 2, the PCS of power storage unit 900 stores power supplied from power system 910 using the storage batteries of power storage unit 900 and expansion unit 902 in accordance with a setting change by remote controller 904. The electric power stored in the power storage unit 900 and the expansion unit 902 is converted from direct current to alternating current by the PCS as needed, and is supplied to a load 912 such as a home. By connecting the storage battery of the expansion unit 902 in parallel to the storage battery of the power storage unit 900, the power storage capacity increases. Therefore, a request for a relatively small capacity can be met with a single power storage unit 900, and if the required capacity is larger, it can be met by adding one, two, or three expansion units 902.

JP2017-28884A

However, since the expansion unit 902 has a different configuration from the power storage unit 900, it is necessary to manage the power storage unit 900 and the expansion unit 902 by giving them different product numbers. Further, it is also necessary to adjust the number of power storage units 900 manufactured and the number of expansion units 902 manufactured, which is complicated. Furthermore, although the capacity of the storage battery increases, the output capacity of the PCS does not change, so the expected effect on the increase in the number of storage batteries is small.

Therefore, the present disclosure provides a power storage device that can synchronize the timing of updating the command value of each power storage unit in a configuration in which a plurality of power storage units are connected in parallel to an electric power system, and can efficiently operate a plurality of power storage units. The purpose is to provide a system.

A power storage system according to an aspect of the present disclosure includes a first unit including a first storage battery and connected to the power grid, and a second unit including a second storage battery and connected to the power grid in parallel with the first unit. The first unit includes a sensor that detects a current supplied from the power system, and a control unit, and the first unit is configured to issue a first charging/discharging command to the first storage battery to prevent reverse power flow from occurring, based on the detected value of the sensor. The controller determines the total value obtained by adding the first charge/discharge command value and the second command value which is the charge/discharge command value of the second storage battery set in the second unit. The first command value, which is the charge/discharge command value for the first unit, and the second command value, which is the charge/discharge command value for the second unit, are newly determined by dividing, and the first command value is the newly determined charge/discharge command value for the second unit. The second unit updates the charging/discharging command value of the second storage battery with the newly determined second command value, and the first unit updates the charging/discharging command value of the second storage battery with the newly determined second command value. The timing of the update by the second unit is the same as the timing of the update by the second unit.

According to the present disclosure, in a power storage system having a configuration in which a plurality of power storage units are connected in parallel to an electric power system, the timing of updating the command value of each power storage unit can be synchronized, and the plurality of power storage units can be efficiently operated. becomes possible.

FIG. 1 is a block diagram showing the configuration of a conventional power storage system. FIG. 2 is a block diagram showing a configuration in which an extension unit is added to the power storage system of FIG. 1. FIG. 3 is a block diagram showing the configuration of a power storage system for grid connection according to an embodiment of the present disclosure. FIG. 4 is a sequence diagram illustrating the relationship between the operations of each part configuring the power storage system for grid connection according to the embodiment of the present disclosure. FIG. 5 is a graph showing update timing of command values. FIG. 6 is a flowchart showing the operation of the remote control shown in FIG. FIG. 7 is a flowchart showing the operation of the power storage unit of FIG. 3. FIG. 8 is a flowchart showing the operation of the expansion unit of FIG. FIG. 9 is a block diagram showing the configuration of a power storage system for grid connection that includes a solar power generation system.

[Description of embodiments of the present disclosure]
First, the contents of the embodiment of the present disclosure will be listed and explained. At least some of the embodiments described below may be combined arbitrarily.

(1) A power storage system according to an aspect of the present disclosure includes a first unit that includes a first storage battery and is connected to the power grid, and a second storage battery that is connected to the power grid in parallel with the first unit. a second unit, a sensor that detects the current supplied from the power system, and a control unit; The control unit determines the charging/discharging command value, and the control unit adds the first charging/discharging command value and the second command value, which is the charging/discharging command value of the second storage battery set in the second unit. The total value is divided to newly determine a first command value that is a charge/discharge command value for the first unit and a second command value that is a charge/discharge command value for the second unit. The second unit updates the charge/discharge command value of the second storage battery with the newly determined second command value, and updates the charge/discharge command value of the second storage battery with the newly determined second command value. The timing of the update by the unit and the timing of the update by the second unit are the same.

In order to solve the problems of the prior art described above, it is conceivable to add a power storage unit having the same configuration as power storage unit 900 instead of expansion unit 902 in FIG. 2 . The added power storage unit (hereinafter referred to as an additional power storage unit) is connected to the power grid 910 similarly to the power storage unit 900, and receives power supplied from the power grid 910 from AC via the PCS inside the additional power storage unit. It is converted to direct current and stored in the storage battery inside the additional power storage unit. The electric power stored in the storage battery of the additional power storage unit is controlled by the remote controller 904, and is converted from direct current to alternating current by the PCS as necessary and supplied to the load 912. The CT sensor for monitoring the reverse flow may be the reverse flow detection CT sensors 906 and 908 as in FIGS. 1 and 2. The overall command value P0 must be determined under restrictions that do not cause reverse power flow, and must be appropriately divided into a command value P1 for the power storage unit 900 and a command value P2 for the additional power storage unit (P0 = P1 + P2). be. For example, the command value P0 is divided so that the charging and discharging capacities are approximately the same (P1≈P2) so that either one of the power storage unit 900 and the additional power storage unit is not primarily used.

However, since the information (current values) from the reverse flow detection CT sensors 906 and 908 is not input to the additional power storage unit, the additional power storage unit needs to receive this information from the power storage unit 900. In that case, a problem arises in that the timing at which the command value is updated in power storage unit 900 is different from the timing at which the additional power storage unit receives information from power storage unit 900 and updates the command value in the additional power storage unit. If the update timing of the command value is different, the operation of the power storage system will not be in accordance with the original command value. If the timings at which the respective command values are updated between power storage unit 900 and the additional power storage unit are different, it may be determined that a reverse power flow is occurring, and the system protection relay may be disconnected.

Furthermore, in controlling communication between the remote controller 904, the power storage unit 900, and the additional power storage unit, the remote controller 904 and the power storage unit 900 alternately send commands, which makes the communication control complicated.

In contrast, in the power storage system according to an aspect of the present disclosure described above, in addition to being able to solve the problems of the prior art, the timing for updating the command value is different in the first unit and the second unit, so that the original command It is possible to prevent abnormalities that do not result in operations as expected, and it is possible to prevent communication control from becoming complicated.

(2) Preferably, the timing of the update by the first unit and the timing of the update by the second unit are zero-cross timings when the value of the AC voltage supplied from the power system becomes zero. Thereby, the timing of updating the command values can be more accurately aligned, and it is possible to further prevent an abnormality in which the timing of updating the command values is different and the operation does not follow the original command value.

(3) More preferably, the control unit newly determines the first command value and the second command value according to the charging and discharging history of the first storage battery and the charging and discharging history of the second storage battery. Thereby, the frequency of use (number of cycles) of the first unit and the second unit can be made to be approximately the same.

(4) More preferably, the control unit newly determines the first command value and the second command value according to the remaining capacity of the first storage battery and the remaining capacity of the second storage battery. Thereby, it is possible to prevent one of the first unit and the second unit from running out of power in a short period of time.

(5) Preferably, the control section is located outside the first unit and the second unit. Thereby, a remote control or the like can be used as the control section, and the current command values of the first unit and the second unit can be displayed on the remote control or the like and presented to the user.

[Details of embodiments of the present disclosure]
In the following embodiments, the same parts are given the same reference numbers. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

(Embodiment)
[overall structure]
Referring to FIG. 3, a grid-connected power storage system 100 according to an embodiment of the present disclosure includes a power storage unit 102 connected to a power grid 112, and an additional power storage unit 102 connected to a power grid 112 in parallel with the power storage unit 102. It includes a unit 104, a remote control 106 that communicates with the power storage unit 102 and the expansion unit 104, and reverse current detection CT sensors 108 and 110 arranged on the distribution line from the power system 112. The power storage unit 102 and the expansion unit 104 each include a PCS and a storage battery (such as a lithium ion secondary battery). The power storage unit 102 and the expansion unit 104 each convert the power supplied from the power system 112 from alternating current to direct current via the PCS and store it in an internal storage battery.

Each PCS of the power storage unit 102 and the expansion unit 104 includes a control section (CPU, microcomputer, etc.), a storage section (for example, a rewritable nonvolatile memory), and a communication section. Each PCS communicates with the communication unit of the remote controller 106 and receives instructions such as start/stop and various setting values (command values, etc. to be described later). Each PCS stores the received setting value in its storage unit, and uses it to perform a charging/discharging operation in response to an instruction from the remote controller 106.

The remote control 106 includes a control section (CPU, microcomputer, etc.), a storage section (for example, a rewritable nonvolatile memory), and a communication section. The remote control 106 communicates with the power storage unit 102 and the expansion unit 104, and stores the received information in the storage unit as appropriate.

Here, it is assumed that the power storage unit 102 and the expansion unit 104 have the same configuration and have the same storage battery capacity. That is, the power storage unit 102 and the expansion unit 104 are provided on the market as the same product. The electric power stored in the respective storage batteries of the power storage unit 102 and the expansion unit 104 is converted from direct current to alternating current by the PCS as necessary, and is supplied to a load 114, which is an electrical device in a home or the like.

The reverse current detection CT sensors 108 and 110 are CT sensors for monitoring reverse current, which is current flowing to the power grid 112 side. The reverse current detection CT sensors 108 and 110 detect the current (alternating current) flowing through the installed power distribution line, and transmit the corresponding information (current value, etc.) to the power storage unit 102. Before supplying power, the power storage unit 102 uses information from the reverse flow detection CT sensors 108 and 110 to determine the power being supplied from the power grid 112. The power storage unit 102 sets a charging/discharging command value for the entire grid-connected power storage system 100 so that the power supplied from the power grid 112 reaches the target power purchase value α set in advance in the power storage unit 102 by the remote controller 106. (hereinafter also referred to as total command value) P0 is determined. That is, at time t, the total command value P0 (=P-α) is determined so that P=α+P0, where P is the power obtained from the information from the reverse flow detection CT sensors 108 and 110. The total command value P0 is divided into a command value P1 for the power storage unit 102 and a command value P2 for the expansion unit 104, and these are set in the power storage unit 102 and the expansion unit 104, respectively. After that, if there is sufficient remaining capacity of the storage batteries of the power storage unit 102 and the expansion unit 104, the PCS of the power storage unit 102 supplies power to the load 114 according to the command value P1, and the expansion unit 104 supplies power to the load 114 according to the command value P2. 114. As a result, among the electric power to be supplied to the load 114, the electric power of the target value α is supplied from the electric power system 112, and the remaining electric power (P0=P1+P2) is supplied from the power storage unit 102 and the expansion unit 104.

When power is being supplied from the power storage unit 102 and expansion unit 104, the total value of the power determined from the information of the reverse flow detection CT sensors 108 and 110 and the power being supplied by the power storage unit 102 and expansion unit 104 is , the power consumption of the load 114, so if the power obtained from the information of the reverse flow detection CT sensors 108 and 110, that is, the purchased power, falls below the target value α, the power storage is adjusted so that the purchased power reaches the target value α. Unit 102 reduces the supplied power (command value).

With reference to FIG. 4, updating of command values in power storage unit 102 and expansion unit 104 will be described. In FIG. 4, time progresses downward. The update of the command value is mainly executed by the remote control 106.

Remote controller 106 transmits a command value information request (a code requesting a total command value) to power storage unit 102 . In response to this, power storage unit 102 calculates a command value to be transmitted and transmits it to remote controller 106. That is, as described above, the power storage unit 102 uses the power P supplied from the power grid 112 and the current command value P1 of the power storage unit 102, which is obtained using the information from the reverse flow detection CT sensors 108 and 110. The value (P+P1-α) obtained by adding and subtracting the target value α is transmitted to the remote controller 106 as a command value information response.

The remote controller 106 adds the received value (P+P1-α) and the command value P2 previously instructed to the expansion unit 104 and stored in the storage unit as described later, to obtain the total command value P0 (=P+P1-α). α+P2) is calculated. Subsequently, the remote controller 106 divides the total command value P0 by, for example, a predetermined ratio, calculates a new command value P1 _New for the power storage unit 102 and a command value P2 _New for the expansion unit 104, and applies each command. The value is sent to the power storage unit 102 and the expansion unit 104 as a control command value setting. The power storage unit 102 and the expansion unit 104 that have received the respective command values update the current command values with the received command values (P1 _New , P2 _New ) at the same timing. In order to update at the same timing, for example, as shown in FIG. 5, after receiving the new command value, the power storage unit 102 and the expansion unit 104 update at the zero cross of the most recent AC cycle.

FIG. 5 shows a voltage waveform supplied from the power system 112. Since the power storage unit 102 and the expansion unit 104 supply power by their respective PCSs in synchronization with the power supplied from the power system 112, the power storage unit 102 and the expansion unit 104 can receive power from the power system 112 that can be specified within each unit. A voltage waveform having the same phase as the supplied voltage waveform can be used to determine the update timing of the command value. For example, in period T1 in FIG. 5, when a command value is transmitted from the remote control 106 and received by the power storage unit 102 and the expansion unit 104, at zero cross A, the power storage unit 102 and the expansion unit 104 transmit their respective command values. Update. During period T2, when a command value is transmitted from remote control 106 and received by power storage unit 102 and expansion unit 104, power storage unit 102 and expansion unit 104 update their respective command values at zero cross B. Thereby, the power storage unit 102 and the expansion unit 104 can update their respective command values simultaneously. By updating at the zero cross of voltage waveforms of the same phase, there is no need to synchronize the clocks of the power storage unit 102 and the expansion unit 104, unlike when updating by specifying a time.

Although the case where the command value is updated at a zero cross where the voltage value changes from negative to positive has been described above, the present invention is not limited to this. For both the power storage unit 102 and the expansion unit 104, the initial value may be updated at the first zero cross that occurs after receiving the command value, and the command value may be updated at the zero cross where the voltage value changes from positive to negative. . For example, in the case of FIG. 5, it may be updated with zero cross C.

If a communication protocol that allows broadcasting is adopted for communication between the remote controller 106, the power storage unit 102, and the expansion unit 104, when the remote controller 106 divides the total command value P0 evenly, that is, P1 _New = P2. When _New = P0/2, the remote controller 106 may broadcast P0/2 as the command value without specifying individual units and transmitting the command value. As a result, the command value only needs to be transmitted once by the remote control 106, and the time required for the transmission process is shortened. The power storage unit 102 and the expansion unit 104 can receive the command value almost simultaneously, and can more reliably update the command value at the same zero cross.

Further, even if the remote controller 106 does not divide the total command value P0 evenly, the remote controller 106 may broadcast the command value. For example, if the structure of the transmission data is determined so that predetermined bits of data are stored in the order of P1 _New and P2 _New , the power storage unit 102 and expansion unit 104 that have received the transmission data will Command values addressed to each can be read out.

Note that the power storage unit 102 and the expansion unit 104 do not transmit a code (ACK code) for confirming that the command value transmitted from the remote controller 106 has been received. This is because if the ACK code is transmitted from the power storage unit 102 and the expansion unit 104 to the remote controller 106, updating of the command value will be delayed.

The processes performed by remote controller 106, power storage unit 102, and expansion unit 104 will be described in more detail with reference to FIGS. 6 to 8. The flowchart in FIG. 6 is executed by the remote controller 106. Specifically, the control section of the remote control 106 reads a predetermined program from the storage section inside the remote control 106 and executes it.

In step 300, the remote control 106 requests the power storage unit 102 to transmit a command value (command value information request in FIG. 5). In response, as described above, the power storage unit 102 returns a command value information response (FIG. 5).

In step 302, remote control 106 determines whether command value (P+P1-α) has been received from power storage unit 102. If so, control passes to step 304. Otherwise, step 302 is repeated.

In step 304, the remote controller 106 calculates the command value P1 _New for the power storage unit 102 and the command value P2 _New for the expansion unit 104, as described above, from the command value (P+P1-α) received in step 302.

In step 306, the remote controller 106 transmits the command value P1 _New and the command value P2 _New calculated in step 304 to the power storage unit 102 and the expansion unit 104, respectively (control command value setting in FIG. 5). At this time, the remote controller 106 stores the command value P2 _New for the expansion unit 104 in the storage section. The transmission may be performed by sending the corresponding command values to the power storage unit 102 and the expansion unit 104, respectively, or by broadcasting.

In step 308, remote controller 106 determines whether or not it has received an instruction to end. If it is determined that the instruction to end has been received, the remote control 106 transmits a stop instruction to the power storage unit 102 and the expansion unit 104, and then this program ends. Otherwise, control transfers to step 310. The instruction to end is given, for example, by the user operating the remote control 106.

In step 310, remote control 106 sets a timer to repeatedly perform the above process. Specifically, information representing the current time (hereinafter simply referred to as current time) is obtained and stored in the storage unit as the start time.

In step 312, the remote controller 106 determines whether a predetermined period of time has elapsed from the start time set in step 310. The predetermined time may be set in advance. Specifically, the current time is acquired, the start time stored in step 310 is read from the storage section, and it is determined whether the value obtained by subtracting the start time from the current time is greater than a predetermined time. If it is determined that the predetermined time has elapsed, control returns to step 300. Otherwise, step 312 is repeated.

As described above, the remote controller 106 acquires the command value from the power storage unit 102, calculates the total command value P0, and determines the command values (P1 _New , P2 _New ) for the power storage unit 102 and the expansion unit 104 from the total command value P0. However, the process of transmitting each command value to the power storage unit 102 and the expansion unit 104 can be repeated at predetermined time intervals.

The flowchart in FIG. 7 is executed by the power storage unit 102. Specifically, the control section of the power storage unit 102 reads a predetermined program from the storage section inside the power storage unit 102 and executes it.

In step 400, power storage unit 102 determines whether a command value transmission request has been received from remote controller 106. If it is determined that it has been received, control moves to step 402. Otherwise, step 400 is repeated.

In step 402, the power storage unit 102 calculates the command value (P+P1-α) at the current time using the information from the reverse tide detection CT sensors 108 and 110, as described above.

In step 404, power storage unit 102 transmits the command value (P+P1-α) calculated in step 404 to remote controller 106 (command value information response in FIG. 5).

In step 406, power storage unit 102 determines whether a command value (P1 _New ) has been received from remote controller 106. If it is determined that it has been received, control moves to step 408. Otherwise, control transfers to step 410.

In step 408, the power storage unit 102 updates the current command value with the command value (P1 _New ) received in step 406 at the first zero cross after receiving the command value, as described above (for example, the storage unit overwrite the command value stored in P1 _New ). The PCS of the power storage unit 102 outputs electric power according to the updated command value.

In step 410, power storage unit 102 determines whether it has received an instruction to end. If it is determined that a termination instruction has been received, this program terminates. Otherwise, control returns to step 400. The instruction to terminate is made, for example, by transmitting a stop instruction from the remote control 106 to the power storage unit 102.

As described above, the power storage unit 102 can send back a command value in response to a request from the remote controller 106, and can receive and update a new command value.

The flowchart in FIG. 8 is executed by the expansion unit 104. Specifically, the control unit of the expansion unit 104 reads a predetermined program from the storage unit inside the expansion unit 104 and executes it.

The flowchart in FIG. 8 is obtained by removing steps 400 to 404 from the flowchart in FIG. In FIG. 8, the processing of the steps with the same numbers as in FIG. 7 is the same as the processing in FIG. 7, except that the subject is changed from the power storage unit 102 to the expansion unit 104. Therefore, redundant explanations will not be repeated.

Like the power storage unit 102, the expansion unit 104 can update the current command value with the command value (P2 _New ) received in step 406 at the first zero cross after receiving the command value (for example, the storage overwrite the command value stored in the section with P2 _New ). The PCS of the expansion unit 104 outputs electric power according to the updated command value. Therefore, the power storage unit 102 and the expansion unit 104 can update their command values at the same timing.

[effect]
In the grid-connected power storage system 100 configured in which two power storage units 102 and expansion units 104, which are the same product, are connected in parallel, the command values instructed to each from the remote controller 106 can be updated at the same timing. Therefore, it is possible to prevent an abnormality in which the timing of updating the command value is different between the power storage unit 102 and the expansion unit 104, and the operation does not follow the original command value.

Furthermore, in a power storage system that does not include an expansion unit 104 and is configured with a power storage unit 102, when it becomes necessary to increase the power storage capacity, it is possible to easily increase the power storage capacity by connecting the expansion unit 104, which is the same product as the power storage unit 102. It is possible to increase the storage capacity. Therefore, the same product as the power storage unit 102 can be used as the expansion unit 104 for increasing the power storage capacity, and the power storage unit and the expansion unit can be managed using the same product number. There is no need to adjust the manufacturing numbers of each of the power storage unit 102 and the expansion unit 104. Furthermore, since the power storage system can be configured with a small power storage unit, it is less likely to be subject to restrictions such as installation location.

Further, since the remote control 106 plays a main role and specifies the command values for the power storage unit 102 and the expansion unit 104, the remote control 106 can display and present the current command values of the power storage unit 102 and the expansion unit 104 to the user, for example. can.

(Modified example)
Although the case where the remote controller calculates the total command value P0 has been described above, the calculation is not limited to this. For example, as described above, when transmitting the command values P1 _New and P2 _New from the remote controller 106 by broadcast, the power storage unit 102 receives and stores the command value P2 _New from the expansion unit 104, and then P0=P+P1- The total command value P0 can be calculated from α+P2 _New (P is the power supplied from the power system 112, P1 is the current command value of the power storage unit 102, and α is the target value). Therefore, for example, in the command value information request in FIG. 4, the remote controller 106 requests the power storage unit 102 to transmit the total command value P0, and the power storage unit 102 sends the total command value calculated as described above as a command value information response. The value P0 may be transmitted to the remote control 106. As a result, the remote controller 106 receives the total command value P0 from the power storage unit 102 without storing the command value sent to the expansion unit 104, divides it, and divides the total command value P0 into each of the power storage unit 102 and the expansion unit 104. A new command value can be determined and broadcasted. After each of the power storage unit 102 and the expansion unit 104 receives a new command value, the command value can be updated at the first zero cross of the supplied voltage waveform.

In the above description, a case has been described in which the remote control 106 mainly transmits command values for the power storage unit 102 and the expansion unit 104, but the present invention is not limited to this. The power storage unit 102 may play a main role in calculating and transmitting command values for the power storage unit 102 and the expansion unit 104. In that case, the power storage unit 102 and the expansion unit 104 may be configured to be able to communicate directly, and the power storage unit 102 may request the expansion unit 104 to transmit a command value. The power storage unit 102 can receive the command value P2 transmitted from the expansion unit 104 and calculate command values for each of the power storage unit 102 and the expansion unit 104. Regarding calculation of a new command value, the power storage unit 102 uses the current command value P1 of the power storage unit 102 and information from the reverse flow detection CT sensors 108 and 110 for the current command value P2 received from the expansion unit 104. The total command value P0 (=P1+P2+P-α) is calculated by adding the power P supplied from the power system 112 and subtracting the target value α. The power storage unit 102 uses the new command value P1 _New calculated by dividing the total command value P0, and transmits the new command value P2 _New to the expansion unit 104. The power storage unit 102 and the expansion unit 104 can update the command value at the same timing as described above. That is, after receiving the new command value P2 _New , the expansion unit 104 updates the command value at the first zero cross of the supplied voltage waveform, and the power storage unit 102 instructs the expansion unit 104 to receive the new command value P2 _New . After transmitting, it is sufficient to update its own command value at the first zero cross of the voltage waveform being supplied.

Further, the expansion unit 104 may play a main role in calculating the command values for the power storage unit 102 and the expansion unit 104. In that case, similar to the above, the power storage unit 102 and the expansion unit 104 are configured to be able to communicate directly, and the detection information of the reverse flow detection CT sensors 108 and 110 is input to the expansion unit 104 instead of being input to the power storage unit 102. do it. In this way, the expansion unit 104 requests the power storage unit 102 to transmit the command value, receives the command value P1 transmitted from the power storage unit 102, and transmits the command values of the power storage unit 102 and the expansion unit 104. It can be calculated. That is, the expansion unit 104 uses the current command value P1 received from the power storage unit 102, the current command value P2 of the expansion unit 104, and the information from the power system 112 obtained from the reverse current detection CT sensors 108 and 110. The total command value P0 (=P1+P2+P−α) can be calculated by adding the supplied electric power P and subtracting the target value α. The expansion unit 104 may transmit a new command value P1 _New calculated by dividing the total command value P0 to the power storage unit 102, and use the new command value P2 _New by itself. The power storage unit 102 and the expansion unit 104 can update the command value at the same timing as described above. That is, after receiving the new command value P1 _New , the power storage unit 102 updates the command value at the first zero cross of the supplied voltage waveform, and the expansion unit 104 instructs the power storage unit 102 to receive the new command value P1 _New . After transmitting, it is sufficient to update its own command value at the first zero cross of the voltage waveform being supplied.

When dividing the total command value P0 to calculate the command value P1 for the power storage unit 102 and the command value P2 for the expansion unit 104, the operation history (number of charging/discharging cycles) of each unit is taken into consideration and determined. It is preferable. For example, if an existing power storage system without an extension unit 104 is used for a certain period of time and then an extension unit 104 is added, the total command value P0 is divided so that the extension unit 104 is mainly used (P2 >P1). After that, when a certain period of time passes and the number of cycles of the expansion unit 104 becomes larger than the number of cycles of the power storage unit 102, the total command value P0 is divided so that the frequency of use of the power storage unit 102 becomes higher (P1>P2 ) is preferred. Thereby, the frequency of use (the number of charging/discharging cycles) of the power storage unit 102 and the expansion unit 104 can be made to be approximately the same.

In addition, when calculating the command value P1 for the power storage unit 102 and the command value P2 for the expansion unit 104 by dividing the total command value P0, the remaining capacity of the storage batteries of the power storage unit 102 and the expansion unit 104 are taken into consideration. It is preferable to decide. If a high command value is specified for a unit with low remaining capacity, the stored power will be used up in a relatively short time. Therefore, for example, it is preferable to divide the total command value P0 by the ratio of the remaining capacity of the power storage unit 102 and the expansion unit 104. Thereby, it is possible to prevent one of the power storage unit 102 and the expansion unit 104 from running out of power in a short period of time.

Further, the command value P1 for the power storage unit 102 and the command value P2 for the expansion unit 104 may be determined comprehensively in consideration of the operation history of each unit and the remaining capacity of the storage battery. Further, the user may be able to change the ratio of the command value P1 for the power storage unit 102 and the command value P2 for the expansion unit 104 by operating the remote control 106.

In the above, a case has been described in which the power storage system 100 for grid connection is configured with a total of two units (the power storage unit 102 and the expansion unit 104), but the present invention is not limited to this. Two or more expansion units 104 may be provided, and the total number of units may be three or more.

Moreover, as shown in FIG. 9, a power generation system may be connected. The grid-connected power storage system 130 includes, in addition to the configuration of the grid-connected power storage system 100, a solar power generation panel 132 and a PCS 134 connected to the power grid 112. Electric power generated by the solar power generation panel 132 is converted into alternating current by the PCS 134 and supplied to the load 114. If the power supplied from the PCS 134 is greater than the power consumed by the load 114 and there is surplus power, the surplus power is stored by the power storage unit 102 and the expansion unit 104. At this time, in the same way as above, by determining new command values (however, negative values) for the power storage unit 102 and the expansion unit 104 and updating the respective command values, the power storage unit 102 and the expansion unit 104 are set at a predetermined ratio. The expansion unit 104 can be charged.

Although the case where the remote control 106 stores the command value transmitted to the expansion unit 104 has been described above, the present invention is not limited to this. The remote controller 106 may request the expansion unit 104 in addition to the power storage unit 102 to transmit the command value. In this way, the remote controller 106 does not need to store the command value transmitted to the expansion unit 104. The remote controller 106 can calculate the total command value P0 (=P+P1-α+P2) from the command value P+P1-α received from the power storage unit 102 and the command value P2 received from the expansion unit 104.

Although the present disclosure has been described above by describing the embodiments, the above-described embodiments are merely examples, and the present disclosure is not limited to the above-described embodiments. The scope of the present disclosure is indicated by each claim, with reference to the description of the detailed description of the invention, and all changes within the meaning and scope equivalent to the words described therein are defined. include.

100, 130 Power storage system for grid connection 102, 900 Power storage unit 104, 902 Expansion unit 106, 904 Remote control 108, 110, 906, 908 Reverse tide detection CT sensor 112, 910 Power system 114, 912 Load 132 Solar power generation panel 134 PCS

Claims (7)

A storage battery device connected to an electric power system in parallel with other storage battery devices,
a power storage unit having a storage battery and connected to the power system;
a control unit;
The control unit divides the total value obtained by adding the charge/discharge command value of the storage battery and the charge/discharge command value set for the other storage battery device, and sets the charge/discharge command value for the power storage unit. newly determining a command value and a charge/discharge command value for the other storage battery device;
The storage battery device notifies the other storage battery device of the newly determined charge/discharge command value for the other storage battery device, and at the same time as the other storage battery device updates the charge/discharge command value. A storage battery device that updates a charge/discharge command value for the storage battery with the determined charge/discharge command value for the power storage unit. The storage battery device according to claim 1, wherein the electricity storage unit determines a charging/discharging command value for the storage battery based on a detection value of a sensor that detects the current supplied from the power system so that reverse power flow does not occur. 2. The timing of updating by the power storage unit and the timing of updating by the other storage battery device are timings of zero crosses when the value of the AC voltage supplied from the power system becomes zero. The storage battery device described in . The control unit may set a charge/discharge command value for the power storage unit and a charge/discharge command value for the other storage battery device according to the charge/discharge history of the storage battery and the charge/discharge history of the storage battery included in the other storage battery device. The storage battery device according to any one of claims 1 to 3, wherein the storage battery device is newly determined. The control unit updates a charging/discharging command value for the electricity storage unit and a charging/discharging command value for the other storage battery device according to the remaining capacity of the storage battery and the remaining capacity of a storage battery included in the other storage battery device. The storage battery device according to any one of claims 1 to 3, which is determined as follows. The storage battery device according to any one of claims 1 to 5, wherein the control section is arranged outside the power storage unit. The storage battery device according to any one of claims 1 to 5, wherein the control section is arranged inside the electricity storage unit.

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