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JP-2026075994-A - Charging and discharging system

JP2026075994AJP 2026075994 AJP2026075994 AJP 2026075994AJP-2026075994-A

Abstract

[Problem] To provide a charge/discharge system that can appropriately evaluate the value of the amount of electricity stored in a battery and perform discharge from or charge the battery accordingly. [Solution] In a charge-discharge system, the charge-discharge control unit 12 decides to discharge a remaining amount of stored energy to the AC line 2 that satisfies a low-price condition, where the remaining power unit price, which is the unit price of the remaining stored energy, determined by considering that the amount of self-discharged energy generated over the period from the charging time to the present time decreases, is lower than the external power unit price, which is the unit price of energy from an external power source G. The remaining power unit price is derived by dividing the product of the unit price of the energy taken in at the charging time of the charging event and the estimated stored energy, which is obtained by subtracting only the total amount of energy discharged from the battery 11b via the power conversion unit 11a from the amount of stored energy newly charged to the battery 11b at the charging time to the present time, by the value obtained by converting the remaining stored energy as energy on the AC line 2. [Selection Diagram] Figure 1

Inventors

  • 前田 和茂

Assignees

  • 大阪瓦斯株式会社

Dates

Publication Date
20260511
Application Date
20241023

Claims (13)

  1. A charge/discharge device is provided, which is connected to an AC line connected to a power grid and has a charge/discharge unit that charges and discharges power between itself and the AC line, and a charge/discharge control unit that controls the operation of the charge/discharge unit. A charging and discharging system in which a power load is connected to the aforementioned AC line, The charging and discharging unit comprises a storage battery for storing DC power and a power conversion unit for converting power between the storage battery and the AC line. A price information acquisition unit that acquires information about the price of electricity that can be supplied to the AC line from an external power source other than the storage battery, It is equipped with an information storage unit for storing information, The information storage unit stores, for each charging event in which the battery is charged from the AC line, information that shows the charging time, the remaining stored power amount which is the amount of power remaining in the battery at the current time out of the amount of stored power newly charged to the battery at the charging time by the charging event, information that shows the estimated stored power amount which is the amount of power obtained by subtracting only the total amount of power discharged from the battery to the AC line via the power conversion unit up to the current time from the amount of stored power newly charged to the battery at the charging time, and price information which shows the unit price per unit of power of the power taken in by the power conversion unit from the AC line to charge the stored power amount to the battery at the charging time. The charge/discharge control unit, The amount of remaining stored power included in the stored power information for each charging event is determined by considering that the amount of stored power newly charged into the battery at the charging time is continuously stored in the battery from the charging time to the present time, and that this amount is reduced by at least the amount of self-discharge power and standby power generated during the period from the charging time to the present time, and if the battery is discharged to the AC line via the power conversion unit, the amount of remaining stored power is determined by subtracting the total amount of power lost from the battery due to the discharge from the amount of stored power newly charged into the battery at the charging time. If predetermined discharge conditions are met, a discharge determination process is performed to determine whether or not to discharge the remaining stored energy from at least some of the charging events to the AC line. In the discharge determination process, by referring to the stored power information, if there is a remaining amount of stored power that satisfies the low-price condition, where the remaining power unit price, which is the unit price of the remaining stored power when that remaining stored power is supplied to the AC line, is lower than or equal to a predetermined value than the external power unit price, which is the unit price of the amount of power from the external power source that can supply power to the AC line at the current time, then it is decided to discharge the remaining stored power that satisfies the low-price condition to the AC line. A charge-discharge system in which the unit price of the remaining stored energy for each of the aforementioned charging events is derived by dividing the product of the unit price of the amount of energy taken in at the charging time of the charging event and the estimated amount of stored energy at the current time by the value obtained when the remaining stored energy at the current time is converted into energy on the AC line by the power conversion unit.
  2. The charge/discharge control unit, in the discharge determination process, refers to the stored power information and, if there are multiple amounts of remaining stored power from each of the charging events that satisfy the low-cost condition, decides to prioritize discharging the amount of remaining stored power from the charging event with the lower remaining power cost to the AC line. This is the charge/discharge system according to claim 1.
  3. The charge/discharge control unit, in the discharge determination process, refers to the stored power information and, if the remaining stored power amount for at least some of the charge events satisfies the low-cost condition, decides to discharge the remaining stored power amount that satisfies the low-cost condition stored in the battery to the AC line, according to claim 1.
  4. The charge/discharge control unit, in the discharge determination process, refers to the stored power information and, if the remaining stored power amount for each of the charge events satisfies the low-cost condition, determines to discharge the remaining stored power amount satisfying the low-cost condition to the AC line, according to claim 1.
  5. The charge/discharge control unit, in the discharge determination process, refers to the stored power information, If the charge level of the battery is below the first reference value, and the remaining amount of stored power for each of the charging events satisfies the low-cost condition, it is decided to discharge the remaining amount of stored power that satisfies the low-cost condition to the AC line. The charge-discharge system according to claim 1, wherein if the charge rate in the battery is greater than a first reference value, and the remaining amount of stored energy in at least some of the charging events satisfies the low-cost condition, the system determines to discharge the remaining amount of stored energy that satisfies the low-cost condition to the AC line.
  6. The charge/discharge control unit, in the discharge determination process, prohibits discharge from the battery to the AC line if the charge level of the battery is below a second reference value, even if there is a remaining amount of stored energy in each of the charge events that satisfies the low-cost condition. (Charge/discharge system according to any one of claims 1 to 5.)
  7. The charge/discharge control unit, in the discharge determination process, determines that if power supply from the power system to the AC line is not functioning normally at the current time, the remaining stored energy amount for each of the charge events satisfies the low-cost condition, according to any one of claims 1 to 5.
  8. A charge/discharge device is provided, which is connected to an AC line connected to a power grid and has a charge/discharge unit that charges and discharges power between itself and the AC line, and a charge/discharge control unit that controls the operation of the charge/discharge unit. A charging and discharging system in which a power load is connected to the aforementioned AC line, The charging and discharging unit comprises a storage battery for storing DC power and a power conversion unit for converting power between the storage battery and the AC line. A price information acquisition unit that acquires information about the price of electricity that can be supplied to the AC line from an external power source other than the storage battery, It is equipped with an information storage unit for storing information, The information storage unit stores, for each charging event in which the battery is charged from the AC line, information that shows the charging time, the remaining stored power amount which is the amount of power remaining in the battery at the current time out of the amount of stored power newly charged to the battery at the charging time by the charging event, information that shows the estimated stored power amount which is the amount of power obtained by subtracting only the total amount of power discharged from the battery to the AC line via the power conversion unit up to the current time from the amount of stored power newly charged to the battery at the charging time, and price information which shows the unit price per unit of power of the power taken in by the power conversion unit from the AC line to charge the stored power amount to the battery at the charging time. The charge/discharge control unit, The amount of remaining stored power included in the stored power information for each charging event is determined by considering that the amount of stored power newly charged into the battery at the charging time is continuously stored in the battery from the charging time to the present time, and that this amount is reduced by at least the amount of self-discharge power and standby power generated during the period from the charging time to the present time, and if the battery is discharged to the AC line via the power conversion unit, the amount of remaining stored power is determined by subtracting the total amount of power lost from the battery due to the discharge from the amount of stored power newly charged into the battery at the charging time. If predetermined charging conditions are met, a charging determination process is performed to determine whether or not to charge the battery with power supplied from the external power source to the AC line. In the charging determination process, by referring to the stored power information, if there is a remaining amount of stored power among the remaining stored power amounts of each charging event that satisfies the high-price condition, where the remaining power unit price, which is the unit price of the remaining stored power amount when that remaining stored power amount is supplied to the AC line, is higher than a predetermined value or more than the external power unit price, which is the unit price of the amount of power from the external power source that can supply power to the AC line at the current time, then it is decided to charge the battery with power supplied from the external power source to the AC line. A charge-discharge system in which the unit price of the remaining stored energy for each of the aforementioned charging events is derived by dividing the product of the unit price of the amount of energy taken in at the charging time of the charging event and the estimated amount of stored energy at the current time by the value obtained when the remaining stored energy at the current time is converted into energy on the AC line by the power conversion unit.
  9. The charge/discharge control unit, in the charge determination process, refers to the stored power information and, if the remaining stored power amount for at least some of the charge events satisfies the high-price condition, determines to charge the battery with power supplied from the external power source to the AC line, according to claim 8.
  10. The charge/discharge control unit, in the charge determination process, refers to the stored power information and, if the remaining stored power amount for each of the charge events satisfies the high-price condition, determines to charge the battery with power supplied from the external power source to the AC line, according to claim 8.
  11. The charge/discharge control unit, in the charge determination process, refers to the stored power information, If the charge level of the battery is below the third reference value, and the remaining amount of stored power for at least some of the charging events satisfies the high-price condition, it is decided to charge the battery with power supplied from the external power source to the AC line. The charge-discharge system according to claim 8, which determines to charge the battery with power supplied from the external power source to the AC line if the charge rate in the battery is greater than the third reference value, and if the remaining amount of stored power for each of the charging events satisfies the high unit price condition.
  12. The charging and discharging system according to claim 1 or 8, wherein the external power source is a power generation device connected to the power system and the AC line, and at least the power system is included.
  13. The charge/discharge control unit, when charging the AC line with power supplied from the power system and the power generator during a single charging event, calculates the unit price per unit of power of the amount of power taken in by the power conversion unit from the AC line at the time of charging based on the ratio of the amount of power from the power system and the ratio of the amount of power from the power generator to the amount of power taken in, and the unit price of the amount of power from the power system and the unit price of electricity sold from the power generator, according to claim 12.

Description

This invention relates to a charging and discharging system. Patent Document 1 (Japanese Patent No. 6210864) describes a system that determines whether or not to discharge from a power storage unit by considering the electricity purchase price at the time of charging the unit, the current electricity purchase price, and the power conversion efficiency when discharging from the power storage unit via an AC/DC converter. Specifically, if it is determined that the power conversion efficiency is equal to or greater than the ratio of the electricity purchase price at the time of charging (when the amount of energy is charged into the power storage unit) to the current electricity purchase price, a power discharge command is output to the power storage unit. Patent No. 6210864 This is a diagram showing the configuration of the charging and discharging system.This is an example of energy storage power information. A charge/discharge system according to an embodiment of the present invention will be described below with reference to the drawings. Figure 1 shows the configuration of a charge/discharge system. As shown in the figure, a charge/discharge system is provided in facilities such as residences and offices. The charge/discharge system is connected to an AC line 2 connected to a power grid 1 and comprises a charge/discharge unit 11 that charges and discharges power between itself and the AC line 2, and a charge/discharge control unit 12 that controls the operation of the charge/discharge unit 11. A power load 3 is connected to the AC line 2. In addition, in the example shown in Figure 1, a solar cell device 8 is also connected to the AC line 2. In the example shown in Figure 1, the solar cell device 8 is connected to the first connection point P1 of the AC line 2, and the charge/discharge device 10 and power load 3 are connected to the second connection point P2 of the AC line 2. The first connection point P1 is located upstream of the second connection point P2 (closer to the power system 1). In addition, a circuit breaker 20 is provided on the AC line 2 upstream of the first connection point P1. The circuit breaker 20 operates to open when power supply from the power system 1 to the AC line 2 is not functioning normally (for example, during a power outage in the power system 1), disconnecting the solar cell device 8, charge/discharge device 10, and power load 3 from the power system 1, and to close when power supply from the power system 1 to the AC line 2 is functioning normally. The charging/discharging unit 11 comprises a battery 11b that stores DC power and a power conversion unit 11a that converts power between the battery 11b and the AC line 2. In other words, the battery 11b is connected to the DC terminal of the power conversion unit 11a, and the AC line 2 is connected to the AC terminal. The charging/discharging device 10 includes an information storage unit 13 that stores the information being handled. Although not shown in the figures, the charging/discharging device 10 includes a battery management system (BMS), and as will be described later, the power consumed by the BMS is lost from the battery 11b as standby power. Similarly, the power consumed by the charging/discharging control unit 12 and the information storage unit 13 is also lost from the battery 11b as standby power. The battery 11b of the charging/discharging unit 11 is connected to the AC line 2 via the power conversion unit 11a. As a result, the charging/discharging device 10 can convert the amount of energy stored in the battery 11b into power of the desired voltage, frequency, and phase, and output it to the AC line 2. The battery 11b can be configured using, for example, a secondary battery such as a lithium-ion battery. The charging/discharging control unit 12 controls the operation of the power conversion unit 11a to control the output power (discharge power) from the battery 11b to the AC line 2, and the input power (charging power) from the AC line 2 to the battery 11b. Figure 1 shows that the amount of energy taken in by the power conversion unit 11a from the AC line 2 at the AC end is labeled as "taken energy W1". This taken energy W1 can be measured by the power sensor 11c. Furthermore, the amount of energy charged to the battery 11b by the power conversion unit 11a at the DC end is labeled as "stored energy W2". Additionally, the remaining stored energy at the DC end of the battery 11b is labeled as "W3", representing the amount of energy supplied by the power conversion unit 11a to the AC line 2 at the AC end. The information server 5 manages information about the price of electricity that can be supplied to the AC line 2 from an external power source G other than the storage battery 11b. The external power source G includes at least the power system 1, which is connected to the power system 1 and the AC line 2. In this embodiment, the external power source G includes the power system 1 and the solar cell device 8 as a