JPWO2019188889A1 - Power storage system and charge control method - Google Patents

Abstract

In a power storage system having a multi-parallel storage battery module, a simpler configuration suppresses variations in the charging state between storage battery rows due to equal charging. The power storage system (100) is provided and supported for each of the storage battery rows and a multi-parallel storage battery module (2) in which a plurality of storage battery rows (20) including at least one lead storage battery cell (200) are connected in parallel. A switch (4_1 to 4_n) connected in series between the storage battery array and the AC / DC converter (3) and a control device (1) are provided, and the control device turns on the switch to perform the AC / DC. By supplying power from the conversion device to the storage battery row, uniform charging is performed to bring the storage battery row into a fully charged state, and it is determined for each storage battery row whether or not the uniform charging is completed. It is characterized in that the switch of the storage battery row determined to have completed uniform charging is turned off.

Description

The present invention relates to a power storage system and a charge control method, for example, a power storage system that controls charging of a lead storage battery, and a charge control method that controls charging of a lead storage battery.

Lead-acid batteries deteriorate in capacity due to repeated charging and discharging for a long period of time. In a power storage system using a lead-acid battery, in order to remove sulfation, which is one of the causes of deterioration of the lead-acid battery, the lead-acid battery is regularly charged evenly to a fully charged state.

In recent years, due to the demand for larger capacity of lead-acid batteries, a single lead-acid battery cell (single battery) or a storage battery row (also referred to as a "string") in which a plurality of lead-acid battery cells are connected in series is connected in parallel. Power storage systems equipped with parallel storage battery modules are becoming widespread.

In a conventional power storage system equipped with a multi-parallel storage battery module, uniform charging is managed for the entire multi-parallel storage battery. Therefore, due to the characteristics (internal resistance) and temperature of the lead-acid battery cell itself in each storage battery row, the charging current flowing between the storage battery rows varies during uniform charging, resulting in a storage battery row that is overcharged or undercharged. However, there is a problem that the deterioration of the multi-parallel storage battery module progresses.

As a conventional technique for solving this problem, a charge / discharge control device (chopper) for controlling the charge / discharge amount is connected between the AC / DC converter (PCS: Power Conversion System) and the storage battery row, and the charge / discharge control device (chopper) is connected to each storage battery row. There is known a technique for preventing overcharging or insufficient charging during uniform charging by adjusting the charge / discharge amount of the corresponding storage battery row of the charged / discharged control device (see Patent Document 1).

Japanese Patent No. 6247039

However, in the prior art disclosed in Patent Document 1 described above, it is necessary to provide a charge / discharge control device for adjusting the charge / discharge amount of each storage battery row for each storage battery row, which causes a problem that the cost of the power storage system increases. There is.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to have a simpler configuration in a power storage system including a multi-parallel storage battery module, and to vary the charging state between storage battery rows due to uniform charging. Is to suppress.

The power storage system according to a typical embodiment of the present invention controls the transfer of power between a multi-parallel storage battery module in which a plurality of storage battery rows including at least one lead storage battery cell are connected in parallel and the multi-parallel storage battery module. The AC / DC conversion device, a switch provided for each storage battery row and connected in series between the corresponding storage battery row and the AC / DC conversion device, and the state of the storage battery row are monitored for each storage battery row. A control device for controlling the on / off of the switch is provided, and the control device fully charges the storage battery row by turning on the switch and supplying power from the AC / DC conversion device to the storage battery row. It is characterized in that even charging for the state is performed, and whether or not the equal charging is completed is determined for each storage battery row, and the switch of the storage battery row determined to be completed is turned off. And.

According to the power storage system having the multi-parallel storage battery module according to the present invention, it is possible to suppress the variation in the charging state between the storage battery rows due to uniform charging with a simpler configuration.

It is a figure which shows the structure of the power storage system which concerns on one Embodiment of this invention. It is a flow chart which shows the flow of the charge control method at the time of equal charge in the power storage system which concerns on embodiment. It is a figure for demonstrating the charge control method at the time of equal charge in the power storage system which concerns on embodiment. It is a figure for demonstrating the charge control method at the time of equal charge in the power storage system which concerns on embodiment. It is a figure for demonstrating the charge control method at the time of equal charge in the power storage system which concerns on embodiment. It is a figure for demonstrating the charge control method at the time of equal charge in the power storage system which concerns on embodiment. It is a timing chart which shows the charge current and discharge current of the storage battery row (lead-acid battery) at the time of equal charge. It is a figure which shows the relationship between the charge current of the storage battery row and the charge state (SOC) in the constant voltage charging period at the time of performing uniform charge by the constant voltage-constant current charging method or the constant power-constant current charging method. It is a figure which shows an example of the temporal change of the charging current which flows in each storage battery row at the time of performing uniform charge by a constant current-constant voltage charging system.

1. 1. Outline of Embodiment First, an outline of a typical embodiment of the invention disclosed in the present application will be described. In the following description, as an example, reference numerals on drawings corresponding to the components of the invention are described in parentheses.

[1] The power storage system (100) according to a typical embodiment of the present invention is a multi-parallel connection in which a plurality of storage battery rows (20, 20_1 to 20_n) including at least one lead storage battery cell (200) are connected in parallel. The storage battery module (2), the AC / DC conversion device (3) that controls the transfer of power of the multi-parallel storage battery module, and the AC / DC conversion device that is provided corresponding to each storage battery row and corresponds to the storage battery row and the AC / DC conversion device. The control device includes a switch (4-1 to 4_n) connected in series between them, and a control device (1) that monitors the state of the storage battery row for each storage battery row and controls on / off of the switch. By turning on the switch and supplying power from the AC / DC conversion device to the storage battery row, equal charging is performed to bring the storage battery row into a fully charged state, and the uniform charging is performed for each storage battery row. It is characterized in that it is determined whether or not the charging is completed, and the switch of the storage battery row that is determined to have completed the uniform charging is turned off.

[2] In the power storage system, the control device uses the integrated value of the charging current of the storage battery row after the completion of the uniform charging performed last time and the storage battery row after the completion of the uniform charging performed last time. When the ratio to the integrated value of the discharge current of the above becomes a predetermined value, it may be determined that the uniform charging of the storage battery row is completed.

[3] In the power storage system, the control device reduces the charging current of the storage battery row to a predetermined value (Ith) during the constant voltage charging period in which the storage battery row is charged by the constant voltage in the uniform charging. In this case, it may be determined that the uniform charging of the storage battery row is completed.

[4] In the power storage system, in the uniform charging, charging of the storage battery row is started by a constant current, and after the voltage of the storage battery row reaches a predetermined voltage, the constant current that charges the storage battery row by a constant voltage- It may be carried out by a constant voltage charging method.

[5] In the power storage system, in the uniform charging, charging of the storage battery row is started by a constant power, and after the voltage of the storage battery row reaches a predetermined voltage, the constant power that charges the storage battery row by a constant voltage- It may be carried out by a constant voltage charging method.

[6] The charge control method according to a typical embodiment of the present invention is a multi-parallel storage battery module in which a plurality of storage battery rows (20, 20_1 to 20_n) including at least one lead storage battery cell (200) are connected in parallel. (2), an AC / DC converter (3) that controls the transfer of power of the multi-parallel storage battery module, and an AC / DC converter (3) that is provided corresponding to each storage battery row and is provided between the corresponding storage battery row and the AC / DC converter. The multiple in a power storage system including a switch (4-1 to 4_n) connected in series and a control device (1) that monitors the state of the storage battery row for each storage battery row and controls on / off of the switch. A charging control method for a parallel storage battery module, wherein the control device turns on the switch and supplies power from the AC / DC conversion device to the storage battery row to make the storage battery row fully charged. The first step (S1) for starting charging, the second step (S2) for the control device to determine whether or not the uniform charging is completed for each storage battery row, and the control device for the uniform charging. It is characterized by including a third step (S3) of turning off the switch of the storage battery row determined to be completed.

[7] In the charge control method, in the second step, the integrated value of the charging current of the storage battery row after the uniform charging performed last time by the control device and the uniform charging performed last time are completed. Then, when the ratio of the discharge current of the storage battery row to the integrated value becomes a predetermined value, the step of determining that the uniform charging of the storage battery row is completed may be included.

[8] In the charge control method, in the second step, the charging current of the storage battery row is reduced during the constant voltage charging period in which the control device charges the storage battery row by the constant voltage in the uniform charging. When the value (Ith) is reached, the step of determining that the uniform charging of the storage battery row is completed may be included.

[9] In the charge control method, in the uniform charging, charging of the storage battery row is started by a constant current, and after the voltage of the storage battery row reaches a predetermined voltage, the storage battery row is charged by the constant current. -It may be carried out by a constant voltage charging method.

[10] In the charge control method, in the uniform charging, charging of the storage battery row is started by a constant power, and after the voltage of the storage battery row reaches a predetermined voltage, the constant power is charged by the constant voltage. -It may be carried out by a constant voltage charging method.

2. Specific Examples of Embodiments Hereinafter, specific examples of embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals will be given to the components common to each embodiment, and the repeated description will be omitted. In addition, it should be noted that the drawings are schematic, and the relationship between the dimensions of each element, the ratio of each element, etc. may differ from the reality. Even between drawings, there may be parts where the relationship and ratio of dimensions are different from each other.

<< Embodiment 1 >>
FIG. 1 is a diagram showing a configuration of a power storage system according to an embodiment of the present invention.
The power storage system 100 shown in the figure is, for example, a power storage system including a lead storage battery for cycle use. For example, the power storage system 100 supplies power to the load 6 from the power supply unit 5 (commercial power supply) during normal operation, and supplies power to the load 6 from the lead storage battery for power supply backup when a power failure occurs.

The power supply unit 5 is a functional unit that supplies electric power to the power storage system 100 and the load 6. The power supply unit 5 is, for example, a commercial power source. In addition to the commercial power source, the power supply unit 5 may have a power generation facility that generates electric power based on renewable energy such as photovoltaic power generation (PV: Photovoltaics).

The power storage system 100 includes a storage battery module 2, an AC / DC conversion device 3, switches 4_1 to 4_n (n is an integer of 2 or more), and a control device 1.

The storage battery module 2 includes a lead storage battery configured to be able to charge and discharge electric power. The storage battery module 2 is a multi-parallel storage battery module in which a plurality of storage battery rows including at least one lead storage battery cell are connected in parallel.

Specifically, as shown in FIG. 1, the storage battery module 2 has a structure in which a plurality of storage battery rows 20_1 to 20_n in which m (m is an integer of 1 or more) lead storage battery cells 200 are connected in series are connected in parallel. have. Hereinafter, the storage battery module 2 is also referred to as a “multi-parallel storage battery module 2”. Further, when the respective storage battery rows 20_1 to 20_n are not distinguished, it may be simply referred to as "storage battery row 20".

Further, the storage battery module 2 includes a voltage sensor 201 that measures the output voltage (storage voltage) of each storage battery row 20_1 to 20_n, and a current sensor 202 that measures the charge current and discharge current of each storage battery row 20_1 to 20_n. It is provided for each column 20_1 to 20_n.

The AC / DC conversion device (hereinafter, also referred to as “PCS (Power Conditioning System)) 3 is controlled by a control device 1 described later, and converts power between the power supply unit 5, the storage battery module 2, and the load 6 to each other. , A power conversion unit that controls the transfer of electric power between the power supply unit 5, the storage battery module 2, and the load 6.

For example, the PCS 3 converts the alternating current power (AC) from the power supply unit 5 into direct current power (DC) and supplies it to the storage battery module 2. The PCS3 includes, for example, a DC / DC converter, an AC / DC converter (AC / DC), a switch circuit, and the like.

Switches 4-1 to 4_n are devices for switching connection and disconnection between the PCS 3 and the multi-parallel storage battery module 2. As shown in FIG. 1, the switches 4_1 to 4_n are provided corresponding to each of the storage battery rows 20_1 to 20_n, and are connected in series between the corresponding storage battery rows 20_1 to 20_n and the PCS3. The switches 4_1 to 4_n are, for example, electromagnetic switches (relays).

The control device 1 is a device that comprehensively controls the entire power storage system 100. The control device 1 monitors the state of each storage battery row 20_1 to 20_n for each storage battery row 20_1 to 20_n, and controls the on / off of the switches 4_1 to 4_n.

As shown in FIG. 1, the control device 1 includes a monitoring unit 11, a storage battery management unit 12, and a switch control unit 13.
The monitoring unit 11 is a data processing device that sequentially acquires the physical quantities measured by the voltage sensor 201 and the current sensor 202 of the multi-parallel storage battery module 2 and monitors the state of the multi-parallel storage battery module 2 based on the physical quantities. The monitoring unit 11 is, for example, a BMU (Battery Management Unit).

The storage battery management unit 12 is a device that controls the overall control of each component of the power storage system 100. The storage battery management unit 12 is, for example, an EMS (Energy Management System).
Specifically, the storage battery management unit 12 controls the charge / discharge of the multi-parallel storage battery module 2 by driving the PCS3. For example, the storage battery management unit 12 uses various charging methods such as a constant current-constant voltage charging (CCCV) method and a constant power-constant voltage charging method based on the monitoring result of the multi-parallel storage battery module 2 by the monitoring unit 11. Equal charging of the storage battery module 2 is performed.

Here, in the constant current-constant voltage charging (CCCV) method, charging of the storage battery rows 20_1 to 20_n is started by a constant current, and after the voltage of the storage battery rows 20_1 to 20_n reaches a predetermined voltage, the storage battery row is driven by a constant voltage. It is a charging method for charging 20_1 to 20_n.

Further, in the constant power-constant voltage charging method, charging of the storage battery rows 20_1 to 20_n is started by constant power, and after the voltage of the storage battery rows 20_1 to 20_n reaches a predetermined voltage, the storage battery rows 20_1 to 20_n are charged by the constant voltage. It is a charging method for charging.

The switch control unit 13 is a functional unit that switches on / off of switches 4_1 to 4_n in response to an instruction from the monitoring unit 11 or the storage battery management unit 12. For example, when the switches 4_1 to 4_n are relays, the switch control unit 13 is a signal generation circuit that generates a drive signal for switching on / off of the relay in response to an instruction from the monitoring unit 11 or the storage battery management unit 12. is there.

The monitoring unit 11 and the storage battery management unit 12 include, for example, a processor such as a CPU (Central Processing Unit) as hardware resources, a storage device such as a RAM (Random Access Memory) or a ROM (Read Only Memory), and an I / F. In a data processing device having a peripheral circuit such as a circuit, the processor controls the peripheral circuit by executing various operations according to a program stored in the storage device.

In order to prevent deterioration of the lead-acid batteries constituting the multi-parallel storage battery module 2, the control device 1 periodically executes uniform charging to fully charge the storage battery rows 20_1 to 20_n of the multi-parallel storage battery module 2.

The control device 1 turns on the switches 4_1 to 4_n and supplies electric power from the PCS 3 to the storage battery rows 20_1 to 20_n to perform uniform charging to fully charge the storage battery rows 20_1 to 20_n, and the storage battery row 20_1 It is determined whether or not the equal charging is completed every ~ 20_n, and the switches 4_1 to 4_n of the storage battery rows 20_1 to 20_n which are determined to have completed the equal charging are turned off.

Hereinafter, the charge control method at the time of uniform charging in the power storage system 100 will be described in detail with reference to the drawings.

FIG. 2 is a flow chart showing a flow of a charge control method at the time of uniform charging in the power storage system 100. 3A to 3D are diagrams for explaining a charge control method at the time of uniform charging in the power storage system 100.

Here, as shown in FIGS. 3A to 3D, the multi-parallel storage battery module 2 in the power storage system 100 has three storage battery rows 20_1 to 20_3 having four (m = 4) lead-acid battery cells 200 connected in series. Will be described by taking an example of having a structure in which the above are connected in parallel.

Further, in FIGS. 3A to 3D, the charging currents of the storage battery rows 20_1 to 20_3 during uniform charging are set to I1, I2, and I3, respectively, and I2> I1> I3 due to variations in the characteristics of the storage battery rows 20_1 to 20_3. Suppose there is. Note that the voltage sensor 201 and the current sensor 202 are not shown in FIGS. 3A to 3D.

First, as shown in FIG. 3A, the control device 1 starts uniform charging of the storage battery rows 20_1 to 20_3 by turning on the switches 4_1 to 4_3 and supplying power from the PCS 3 to the storage battery rows 20_1 to 20_3 (step). S1).

For example, the monitoring unit 11 requests the storage battery management unit 12 to execute uniform charging. The storage battery management unit 12 turns on (or confirms that the switches 4_1 to 4_3 are turned on) via the switch control unit 13 in response to a request from the monitoring unit 11, and also performs a predetermined charging method (for example, confirming that the switches are turned on). , Constant current-constant voltage charging method), the PCS3 is driven to start supplying electric power to the storage battery rows 20_1 to 20_3.

Next, the control device 1 determines whether or not there are storage battery rows 20_1 to 20_3 for which uniform charging has been completed (step S2). Specifically, the monitoring unit 11 measures the output voltage and current of each storage battery row 20_1 to 20_3 acquired from the voltage sensor 201 and the current sensor 202 of each storage battery row 20_1 to 20_3, and the storage battery row 20_1 to 20_3 It is determined whether or not the equal charging of the above is completed. The specific determination method will be described later.

In step S2, when the storage battery rows 20_1 to 20_3 for which uniform charging has been completed do not exist, the control device 1 continues equal charging of each storage battery row 20_1 to 20_3.

On the other hand, in step S2, when the storage battery rows 20_1 to 20_3 for which uniform charging has been completed exists, the control device 1 turns off the switches 4_1 to 4_3 of the storage battery rows 20_1 to 20_3 for which uniform charging has been completed (step S3). ..

For example, in the case of the above example, since the charging currents of the storage battery rows 20_1 to 20_3 during uniform charging have a relationship of I2> I1> I3, the storage battery row 20_2 having the largest charging current I2 is first fully charged. When the monitoring unit 11 determines that the uniform charging of the storage battery row 20_2 is completed, the monitoring unit 11 notifies the storage battery management unit 12 of that fact. Upon receiving the notification, the storage battery management unit 12 instructs the switch control unit 13 to release control (off) the switch 4_2, and as shown in FIG. 3B, the switch control unit 13 controls the release of the switch 4_2. Then, the storage battery row 20_2 is disconnected from the PCS3.

Next, the control device 1 determines whether or not uniform charging of all the storage battery rows 20_1 to 20_3 is completed (step S4). If the uniform charging of all the storage battery rows 20_1 to 20_3 is not completed, the process returns to step S2, and the above-described processes from step S2 to step S4 are executed again.

For example, after the uniform charging of the storage battery row 20_2 is completed and the storage battery row 20_2 is disconnected from the PCS3, the charging currents of the storage battery rows 20_2 and 20_3 during the uniform charging have a relationship of I1> I3. Therefore, the storage battery row 20_1 is fully charged next to the storage battery row 20_1. When the monitoring unit 11 determines that the uniform charging of the storage battery row 20_1 is completed, the monitoring unit 11 notifies the storage battery management unit 12 of that fact. Upon receiving the notification, the storage battery management unit 12 instructs the switch control unit 13 to release control (off) the switch 4_1, and as shown in FIG. 3C, the switch control unit 13 controls the release of the switch 4_1. Then, the storage battery row 20_1 is disconnected from the PCS3. Immediately after this, even charging of the storage battery row 20_3 is still continued, so the process returns to step S2 again.

After that, when the storage battery row 20_3 is fully charged, the monitoring unit 11 notifies the storage battery management unit 12 that the uniform charging of the storage battery row 20_3 is completed. Upon receiving the notification, the storage battery management unit 12 instructs the switch control unit 13 to release control (off) the switch 4_3, and as shown in FIG. 3D, the switch control unit 13 controls the release of the switch 4_3. Then, the storage battery row 20_3 is disconnected from the PCS3. As a result, uniform charging of all the storage battery rows 20_1 to 20_3 is completed.

In step S4, when the control device 1 determines that the equal charging of all the storage battery rows 20_1 to 20_3 is completed, the control device 1 ends the control for equal charging of the multi-parallel storage battery module 2 (step S5).
By the above procedure, the power storage system 100 according to the present embodiment is uniformly charged.

Next, a method for determining the completion of uniform charging will be described.
Two examples are shown below as a method for determining the completion of uniform charging according to the present embodiment.

First, a first example of a method for determining the completion of uniform charging by the power storage system 100 will be described.
As a first example, in the control device 1, the integrated value of the charging current of the storage battery row 20 since the last uniform charging was completed and the discharge current of the storage battery row 20 since the last uniform charging was completed. When the ratio with the integrated value reaches a predetermined value, it is determined that the uniform charging of the storage battery row 20 is completed.

FIG. 4 is a timing chart showing the charge current and the discharge current of the storage battery row 20 (lead-acid battery) at the time of uniform charging. In FIG. 4, the vertical axis represents current and the horizontal axis represents time. Further, reference numeral 302 represents a charging current of the storage battery row 20, and reference numeral 303 represents a discharging current of the storage battery row 20.

First, the monitoring unit 11 of the control device 1 starts integrating the charging current and the discharging current for each of the storage battery rows 20_1 to 20_n at the timing when the uniform charging is completed. For example, in FIG. 4, at time t31 when uniform charging is completed, the monitoring unit 11 starts integrating the charging currents of the storage battery rows 20_1 to 20_n and also starts integrating the discharge currents of the storage battery rows 20_1 to 20_n. ..

Next, the monitoring unit 11 calculates the ratio of the integrated value of the charging current and the integrated value of the discharging current for each of the storage battery rows 20_1 to 20_n. Specifically, the ratio of the integrated value of the charging current to the integrated value of the discharge current is calculated.

Next, the monitoring unit 11 determines whether or not the calculated ratio has reached the ratio reference value for each of the storage battery rows 20_1 to 20_n.

Here, the ratio reference value is a value that serves as a reference for determining the end of the constant voltage charging period in uniform charging. In general, uniform charging is overcharged so as to be 100% or more (for example, 104%) with respect to the discharge capacity. Therefore, the ratio reference value is preferably set to a value exceeding 100%, for example, a value in the range of 101% to 104%.

When there is no storage battery row 20 whose ratio has reached the ratio reference value, the monitoring unit 11 continues to integrate the charging current and the discharging current for each storage battery row 20_1 to 20_n. On the other hand, when there is a storage battery row 20 whose calculated ratio has reached the ratio reference value, the monitoring unit 11 determines that the uniform charging of the storage battery row 20 whose calculated ratio has reached the ratio reference value has been completed. The monitoring unit 11 repeatedly executes the above process until a determination result indicating that uniform charging is completed for all the storage battery rows 20_1 to 20_n is obtained.

By executing the data processing in the above procedure, it is possible to determine whether or not the uniform charging is completed for each of the storage battery rows 20_1 to 20_n.

Next, a second example of a method for determining the completion of uniform charging by the power storage system 100 will be described.
As a second example, in the constant voltage charging period in which the storage battery row 20 is charged by the constant voltage in uniform charging, the control device 1 reduces the charging current of the storage battery row 20 to a predetermined value, the storage battery row 20 It is determined that the equal charging is completed.

FIG. 5 shows the charging current and the charging state (SOC: State Of Charge) of the storage battery row 20 in the constant voltage charging period when uniform charging is performed by the constant voltage-constant current charging method or the constant power-constant current charging method. It is a figure which shows the relationship.

As shown in FIG. 5, when the storage battery is charged at a constant voltage, the charging current tends to decrease as it approaches full charge. Therefore, it is possible to detect the completion of uniform charging by monitoring the charging current for each storage battery row 20 during the constant voltage charging period in uniform charging. For example, the monitoring unit 11 determines that uniform charging is completed when the charging current of each storage battery row 20_1 to 20_n decreases and reaches a predetermined threshold value Is during the constant voltage charging period.

FIG. 6 is a diagram showing an example of a temporal change in the charging current flowing through each storage battery row when uniform charging is performed by the constant current-constant voltage charging method.
As described above, in the storage battery rows 20_1 to 20_3, the charging current at the time of constant current charging may vary depending on the temperature and the characteristics (internal resistance) of the lead storage battery cell 200 itself. For example, consider the case where I2>I1> I3 as in the above example.

The monitoring unit 11 of the control device 1 monitors the charging current of each storage battery row 20_1 to 20_3. In the case of the above example, since I2> I1> I3, the charging current I2 of the storage battery row 20_2 first reaches the threshold value Is. When the monitoring unit 11 detects that the charging current I2 of the storage battery row 20_2 has reached the threshold value Is, it determines that the uniform charging of the storage battery row 20_2 is completed.

Next, since I1> I3, the charging current I1 of the storage battery row 20_1 then reaches the threshold value Is. When the monitoring unit 11 detects that the charging current I1 of the storage battery row 20_1 has reached the threshold value Is, it determines that the uniform charging of the storage battery row 20_1 is completed.

Finally, the charging current I3 of the storage battery row 20_3 then reaches the threshold Is. When the monitoring unit 11 detects that the charging current I3 of the storage battery row 20_3 has reached the threshold value Is, it determines that the uniform charging of the storage battery row 20_3 is completed.

In this way, by monitoring the charging current in the constant voltage charging period at the time of uniform charging for each storage battery row 20, it is possible to determine whether or not equal charging is completed for each storage battery row 20.

In the case of the constant power-constant voltage charging method, it is possible to determine whether or not uniform charging is completed for each storage battery row 20 by the same method.

As described above, the power storage system 100 according to the present embodiment is provided corresponding to the multi-parallel storage battery module 2 in which the storage battery rows 20_1 to 20_n including at least one lead storage battery cell 200 are connected in parallel, and the storage battery rows 20_1 to 20_n. Control to monitor the status of the switches 4_1 to 4_n connected in series between the corresponding storage battery rows 20_1 to 20_n and the AC / DC converter (PCS) 3 and the storage battery rows 20_1 to 20_n for each storage battery row 20_1 to 20_n. It is provided with the device 1. The control device 1 performs uniform charging by turning on switches 4_1 to 4_n and supplying power from the PCS 3 to the storage battery rows 20_1 to 20_n, and determines whether or not uniform charging is completed for each storage battery row 20_1 to 20_n. Then, the switches 4_1 to 4_n of the storage battery rows 20_1 to 20_n, which are determined to have completed uniform charging, are turned off.

According to this, the power supply from the PCS 3 to the storage battery rows 20_1 to 20_n, which is performed during uniform charging, can be controlled for each storage battery row 20_1 to 20_n. Even if the charging current flowing through each storage battery row 20_1 to 20_n varies during uniform charging due to characteristics (internal resistance), temperature, etc., each storage battery row 20_1 to 20_n can be fully charged. It will be possible. As a result, it is possible to prevent the storage battery rows 20_1 to 20_n from being overcharged or insufficiently charged due to the variation in the charging current during uniform charging, so that the deterioration of the multi-parallel storage battery module 2 can be suppressed. It will be possible.

Further, since the power storage system 100 has a configuration in which power supply and cutoff from the PCS 3 to each storage battery row 20_1 to 20_n at the time of uniform charging is switched by switches 4_1 to 4_n, the above-mentioned prior art of Patent Document 1 As described above, since it is not necessary to separately provide a complicated charge / discharge control device for adjusting the charge / discharge amount of each storage battery row for each storage battery row, it is possible to suppress an increase in the cost of the power storage system as compared with the conventional technology. ..

Therefore, according to the power storage system 100 according to the present embodiment, it is possible to suppress the variation in the charging state between the storage battery rows due to uniform charging and suppress the deterioration of the multi-parallel storage battery module by a simpler configuration. ..

Further, in the power storage system 100, the control device 1 has the integrated value of the charging currents of the storage battery rows 20_1 to 20_n since the last uniform charging was completed and the storage battery rows 20_1 to 20_1 after the last uniform charging was completed. When the ratio to the integrated value of the discharge current of 20_n becomes a predetermined value, it is determined that the uniform charging of the storage battery rows 20_1 to 20_n is completed.

According to this, regardless of the charging method of equal charging, it is possible to more accurately determine whether or not equal charging is completed for each storage battery row 20.

Further, in the power storage system 100, when the charging current of the storage battery rows 20_1 to 20_n decreases to a predetermined value during the constant voltage charging period in which the storage battery rows 20_1 to 20_n are charged by the constant voltage in the uniform charging. It is determined that the uniform charging of the storage battery rows 20_1 to 20_n is completed.

According to this, in a power storage system that employs a constant voltage charging method that performs constant voltage charging just before the end of uniform charging, such as a constant current-constant voltage charging method and a constant power-constant voltage charging method, it is easier and more accurate. It is possible to determine whether or not equal charging is completed for each storage battery row 20.

<< Expansion of embodiment >>
The inventions made by the present inventors have been specifically described above based on the embodiments, but it goes without saying that the present invention is not limited thereto and can be variously modified without departing from the gist thereof. No.

For example, in the above-described embodiment, the constant current-constant voltage charging method and the constant power-constant voltage charging method have been exemplified as the charging methods having a constant voltage charging period for uniform charging, but the present invention is not limited thereto.

For example, first constant current charging is performed, and after the storage battery voltage reaches a predetermined threshold, constant current charging at a current value lower than the previous current value is repeated a plurality of times, and finally, constant current charging is performed at a predetermined voltage. A multi-stage charging method may be used in which voltage charging is performed to restore the lead-acid battery to a fully charged state.

For example, the control device 1 determines that uniform charging of the storage battery rows 20_1 to 20_n is completed when the charging current of the storage battery rows 20_1 to 20_n decreases to a predetermined value during the constant voltage charging period of the multi-stage charging method. By doing so, it is possible to more easily and accurately determine whether or not uniform charging is completed for each storage battery row 20 as in the case of the constant current-constant voltage charging method and the constant power-constant voltage charging method.

1 ... Control device, 2 ... Storage battery module (multi-parallel storage battery module), 3 ... AC / DC conversion device (PCS), 4_1 to 4_n ... Switch, 5 ... Power supply unit, 6 ... Load, 11 ... Monitoring unit, 12 ... Storage battery management Unit, 13 ... Switch control unit, 20, 20_1 to 20_n ... Storage battery row, 100 ... Power storage system, 200 ... Lead-acid battery cell, 201 ... Voltage sensor, 202 ... Current sensor, Is ... Threshold (predetermined value).

Claims (10)

A multi-parallel storage battery module in which a plurality of storage battery rows including at least one lead-acid battery cell are connected in parallel, and
An AC / DC converter that controls the transfer of power to the multi-parallel storage battery module,
A switch provided corresponding to each storage battery row and connected in series between the corresponding storage battery row and the AC / DC conversion device.
A control device that monitors the state of the storage battery row for each storage battery row and controls the on / off of the switch is provided.
The control device turns on the switch and supplies electric power from the AC / DC conversion device to the storage battery row to perform uniform charging for fully charging the storage battery row, and for each storage battery row, the control device performs uniform charging. A power storage system characterized in that it is determined whether or not equal charging is completed, and the switch of the storage battery row determined that equal charging is completed is turned off. In the power storage system according to claim 1,
In the control device, the integrated value of the charging current of the storage battery row after the completion of the uniform charging performed last time and the integrated value of the discharge current of the storage battery row after the completion of the uniform charging performed last time A power storage system characterized in that when the ratio reaches a predetermined value, it is determined that the uniform charging of the storage battery row is completed. In the power storage system according to claim 1,
In the constant voltage charging period in which the storage battery row is charged by the constant voltage in the uniform charging, the control device performs the uniform charging of the storage battery row when the charging current of the storage battery row decreases to a predetermined value. A power storage system characterized in that it is determined to be completed. In the power storage system according to claim 3,
The uniform charging is performed by a constant current-constant voltage charging method in which charging of the storage battery row is started by a constant current and the storage battery row is charged by a constant voltage after the voltage of the storage battery row reaches a predetermined voltage. A storage battery system featuring. In the power storage system according to claim 3,
The uniform charging is performed by a constant power-constant voltage charging method in which charging of the storage battery row is started by a constant power, and after the voltage of the storage battery row reaches a predetermined voltage, the storage battery row is charged by a constant voltage. A storage battery system featuring. A multi-parallel storage battery module in which a plurality of storage battery rows including at least one lead storage battery cell are connected in parallel, an AC / DC conversion device for controlling the transfer of power of the multi-parallel storage battery module, and a corresponding to each storage battery row are provided. A switch connected in series between the corresponding storage battery row and the AC / DC conversion device, and a control device that monitors the state of the storage battery row for each storage battery row and controls on / off of the switch. This is a charging control method for the multi-parallel storage battery module in a power storage system.
A first step in which the control device turns on the switch and supplies electric power from the AC / DC conversion device to the storage battery row to start uniform charging for making the storage battery row fully charged.
A second step in which the control device determines whether or not the uniform charging is completed for each storage battery row, and
A charging control method comprising the third step of turning off the switch of the storage battery row, which is determined to have completed the uniform charging. In the charge control method according to claim 6,
In the second step, the integrated value of the charging current of the storage battery row after the control device completes the uniform charging performed last time and the discharge of the storage battery row after the uniform charging performed last time is completed. A charging control method comprising a step of determining that the uniform charging of the storage battery row is completed when the ratio to the integrated value of the current reaches a predetermined value. In the charge control method according to claim 6,
The second step is the storage battery when the charging current of the storage battery row decreases to a predetermined value during the constant voltage charging period in which the control device charges the storage battery row by the constant voltage in the uniform charging. A charge control method comprising the step of determining that the equal charge of a row is complete. In the charge control method according to claim 8,
The uniform charging is performed by a constant current-constant voltage charging method in which charging of the storage battery row is started by a constant current and the storage battery row is charged by a constant voltage after the voltage of the storage battery row reaches a predetermined voltage. A charge control method characterized by. In the charge control method according to claim 8,
The uniform charging is performed by a constant power-constant voltage charging method in which charging of the storage battery row is started by a constant power, and after the voltage of the storage battery row reaches a predetermined voltage, the storage battery row is charged by a constant voltage. A charge control method characterized by.

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