CN110176788B - Power storage system and power storage device - Google Patents
Power storage system and power storage device Download PDFInfo
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- CN110176788B CN110176788B CN201910117559.5A CN201910117559A CN110176788B CN 110176788 B CN110176788 B CN 110176788B CN 201910117559 A CN201910117559 A CN 201910117559A CN 110176788 B CN110176788 B CN 110176788B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
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Abstract
Provided are an electricity storage system and an electricity storage device, which can realize an inexpensive system that has high energy utilization efficiency and reduced risk. In the electric storage system, electric power exchange is performed between a plurality of electric storage devices connected to a DC connection bus in a unit of electric storage device to which a battery for storing direct-current electric power is connected, wherein the electric storage devices are connected to the DC connection bus via a first bidirectional DC/DC converter that can be set to a discharge operation based on a discharge characteristic in which a discharge current decreases with an increase in grid voltage of the DC connection bus or a charge operation based on a charge characteristic in which a charge current increases with the increase in grid voltage, and when a current in a discharge direction in the discharge characteristic is defined as positive and a current in a charge direction in the charge characteristic is defined as positive, the discharge characteristic and the charge characteristic are set to intersect.
Description
Technical Field
The present invention relates to a power storage system and a power storage device that exchange electric power between a plurality of power storage devices that are distributed.
Background
In recent years, as a method of utilizing natural energy, a shift to a self-consuming (home consumption) system rather than grid interconnection is expected. As a self-consuming system, for example, a power storage device that stores electric power generated by a solar cell device at a disaster prevention site is considered.
Further, an autonomous distributed power network in which these power storage devices are distributed has been studied, and a technique of performing exchange control of electric power between the power storage devices has been proposed (for example, see patent literature 1).
Patent document 1: japanese patent laid-open No. 2006-288162
However, in the related art, the control of power exchange between clients is centrally managed within the client group. Therefore, the power exchange control of the entire system cannot be performed due to the stoppage of the controller that centrally manages the power exchange control, and therefore there are problems in terms of system efficiency and risk management.
Disclosure of Invention
The present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide an electric storage system as follows: an inexpensive system with high energy utilization efficiency and reduced risk can be realized.
In the power storage system according to the present invention, in a power storage device to which a battery for storing direct-current power is connected, power exchange is performed between a plurality of power storage devices connected to a DC connection bus, and the power storage system includes: a first bidirectional DC/DC converter connected to the DC link bus; and a switching control unit that sets the first bidirectional DC/DC converter for charging or discharging, wherein the first bidirectional DC/DC converter individually controls charging or discharging by controlling a grid voltage of the DC link bus according to an output voltage characteristic in which, when a current in a discharging direction is defined as positive, a discharging characteristic has a negative slope in which the grid voltage increases due to a decrease in the discharging current, and when a current in a charging direction is defined as positive, a charging characteristic has a positive slope in which the grid voltage increases due to an increase in the charging current, and the discharging characteristic and the charging characteristic are set to intersect.
The power storage device according to the present invention is a power storage device connected between a battery storing direct-current power and a DC connection bus, and performs power exchange between the battery and another power storage device connected to the DC connection bus, and is characterized by comprising: a first bidirectional DC/DC converter connected to the DC link bus; and a switching control unit that sets the first bidirectional DC/DC converter for charging or discharging, wherein the first bidirectional DC/DC converter individually controls charging or discharging by controlling a grid voltage of the DC link bus according to an output voltage characteristic in which, when a current in a discharging direction is defined as positive, a discharging characteristic has a negative slope in which the grid voltage increases due to a decrease in the discharging current, and when a current in a charging direction is defined as positive, a charging characteristic has a positive slope in which the grid voltage increases due to an increase in the charging current, and the discharging characteristic and the charging characteristic are set to intersect.
According to the present invention, by switching only the bidirectional DC/DC converter connected to the DC connection bus between the discharging and charging modes, the power exchange between the power storage devices 1 can be controlled, and an advantage of being able to realize an inexpensive system with high energy utilization efficiency and reduced risk can be achieved.
Drawings
Fig. 1 is a block diagram showing a structural example of an embodiment of a power storage system according to the present invention.
Fig. 2 is a block diagram showing the structure of the power storage device shown in fig. 1.
Fig. 3 is an explanatory diagram illustrating a power exchange operation performed by the power storage device shown in fig. 1.
Fig. 4 is a graph showing output voltage characteristics of the first bidirectional DC/DC converter shown in fig. 2.
Fig. 5 is a flowchart illustrating the setting operation of the first bidirectional DC/DC converter by the switching control unit shown in fig. 2.
Description of the reference numerals
1: an electric storage device; 2: a storage battery; 3: a solar cell; 4: a load; 11: a first bidirectional DC/DC converter; 12: a second bidirectional DC/DC converter; 13: an MPPT DC/DC converter; 14: PCS; 15. 16: a current sensor; 17: a charge amount detection unit; 18: an exchange control unit; 19: a DC link; 20: a DC link bus; 31: a junction box; t1: a power exchange terminal; t2: a battery connection terminal; t3: a PV connection terminal; t4: and a load connection terminal.
Detailed Description
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, the same reference numerals are given to the structures showing the same functions, and the description thereof is omitted as appropriate.
Referring to fig. 1, the present embodiment is an electric storage system as follows: in this power storage system, power storage devices 1 connected to a battery 2 are connected in parallel using a DC connection bus 20 with the power storage devices 1 as 1 unit, and power exchange between the power storage devices 1 is performed. The DC connection bus 20 forms a DC grid that is not connected to a stable power source (power system or the like) in a non-electrified region, disaster prevention region or the like. Fig. 1 shows an example in which 3 power storage devices 1 are connected to DC link bus 20, but the number of power storage devices 1 connected to DC link bus 20 is not limited.
The power storage device 1 has a power exchange terminal T1, a battery connection terminal T2, a PV connection terminal T3, and a load connection terminal T4, respectively.
The power exchange terminal T1 is a terminal connected to the DC connection bus 20 and receiving and transmitting direct-current power. The battery connection terminal T2 is a terminal for charging and discharging the connected battery 2. The PV connection terminal T3 is a terminal that receives dc power generated by the solar cell 3 connected via the junction box 31. The load connection terminal T4 is a terminal that supplies power to the connected load 4.
Referring to fig. 2, power storage device 1 includes a first bidirectional DC/DC converter 11 (hereinafter, referred to as first DC/DC 11), a second bidirectional DC/DC converter 12 (hereinafter, referred to as second DC/DC 12), an MPPT DC/DC converter 13, a PCS 14, current sensors 15 and 16, a charge amount detection unit 17, and an exchange control unit 18. The first DC/DC11, the second DC/DC 12, the MPPT DC/DC converter 13, and the PCS 14 are connected together via a DC link 19.
The first DC/DC11 is connected between the power exchange terminal T1 and the DC link 19. As a result, as shown in fig. 3, a plurality of first DC/DC11 are connected in parallel to the DC connection bus 20.
The first DC/DC11 is set for charging or discharging, and is controlled by voltage (hereinafter referred to as grid voltage) control of the DC link bus 20 based on the output voltage characteristics (droop characteristics) shown in fig. 4.
In the output voltage characteristic shown in fig. 4, the discharge characteristic has a negative slope in which the discharge current decreases as the grid voltage increases, and is set to be equal to the grid voltage V 2 The discharge current is zero. The charging characteristic is set to be the specific grid voltage V 2 Low grid voltage V 1 The charging current is zero and the charging current increases with increasing grid voltage of the DC link bus 20. In fig. 4, the current in the charging direction is positive in the charging characteristic, and the current in the discharging direction is positive in the discharging characteristic.
As shown in fig. 3 (a), in a state in which 1 first DC/DC11 set for charging and 1 first DC/DC11 set for discharging are connected to each of the DC connection buses 20, as shown in fig. 4 (a), the charging is performedThe intersection of the electrical characteristic and the discharge characteristic is the operating point a. In this case, the grid voltage V at the operating point A a Is the specific grid voltage V 1 Large and specific grid voltage V 2 Low value. Then, the discharge current flowing from the power storage device 1 for which the first DC/DC11 is set to discharge is a (a), and the charge current flowing into the power storage device 1 for which the first DC/DC11 is set to charge is a (a), whereby the power exchange from 1 power storage device 1 to 1 power storage device 1 is performed.
As shown in fig. 3 (B), in a state in which N first DC/DC11 set for charging and 1 first DC/DC11 set for discharging are connected to the DC connection bus 20, as shown in fig. 4 (B), an intersection point of the charging characteristic and the discharging characteristic of the slope N times is an operating point B. In this case, the grid voltage V at the operating point B b Also is the specific grid voltage V 1 Large and specific grid voltage V 2 Low value. Then, the discharge current flowing from the 1 power storage devices 1 for which the first DC/DC11 is set to discharge is b (a), and the charge currents flowing into the N power storage devices 1 for which the first DC/DC11 is set to charge are b/N (a), respectively, so that the power exchange allocated from the 1 power storage devices 1 to the N power storage devices 1 is performed.
As shown in fig. 3 (C), in a state in which 1 first DC/DC11 set for charging and M first DC/DC11 set for discharging are connected to the DC connection bus 20, as shown in fig. 4 (C), an intersection point of the charging characteristic and the discharging characteristic of the slope of M times is an operating point C. In this case, the grid voltage V at the operating point C c Also is the specific grid voltage V 1 Large and specific grid voltage V 2 Low value. The discharge currents flowing from the M power storage devices 1 for which the first DC/DC11 is set to discharge are c/M (a), and the charge currents flowing into the 1 power storage devices 1 for which the first DC/DC11 is set to charge are c (a), and the M power storage devices 1 share the power exchange to the 1 power storage devices 1.
As described above, the grid voltage V at the operating points A-C a ～V c Are all the specific grid voltage V 1 Large and specific grid voltage V 2 Low value. Thus, when the discharge characteristic is to be dischargedGrid voltage V at zero flow 2 Set as the upper voltage limit value of the grid voltage, and set the grid voltage V at which the charging current is zero in the charging characteristic 1 When the voltage lower limit value of the grid voltage is set, the grid voltage is used in an appropriate range.
The second DC/DC 12 is a charge-discharge device that is connected between the battery connection terminal T2 and the DC link 19 and charges and discharges the battery 2 by DC link voltage constant control (fixed value control) of the DC link 19. When charging the battery 2, the second DC/DC 12 converts the direct current voltage of the DC link 19 into a voltage suitable for charging the battery 2 to charge the battery 2. When discharging from the battery 2, the second DC/DC 12 converts the direct-current voltage of the battery 2 into the direct-current voltage of the DC link 19, and discharges the battery 2.
The MPPT DC/DC converter 13 is a maximum power point tracking (MPPT: maximum Power Point Tracking) type DC/DC converter that is connected between the PV connection terminal T3 and the DC link 19 and that receives direct-current power generated by the solar cell 3. The MPPT DC/DC converter 13 outputs direct-current power received from the solar cell 3 to the DC link 19.
PCS 14 is a power regulator system as follows: is connected between the load connection terminal T4 and the DC link 19, and converts a direct current voltage of the DC link 19 into electric power suitable for the load 4 to be supplied to the load 4.
The current sensor 15 detects a charge/discharge current when the battery 2 is charged/discharged, and outputs the charge current to the charge amount detection unit 17.
The current sensor 16 detects the generated current Ipv of the solar cell 3 and outputs the detected current Ipv to the switching control unit 18.
As the charge level of the battery 2, the charge amount detection unit 17 calculates SOC (State of charge) as the charge amount of the battery 2 based on the charge/discharge current of the battery 2 detected by the current sensor 15. The charge amount detection unit 17 integrates the charge current and the discharge current of the battery 2, respectively, and calculates the SOC from the difference value thereof. The calculation of SOC may be calculated from the terminal voltage of the battery 2 or the like.
The exchange control unit 18 is an information processing unit such as a microcomputer having a CPU (Central Processing Unit: central processing unit), a ROM (Read Only Memory), a RAM (Random Access Memory: random access Memory), and the like. A control program is stored in the ROM. The CPU of the exchange control unit 18 reads out the control program stored in the ROM, and expands the control program in the RAM to operate.
The switching control unit 18 sets the first DC/DC11 to be either for discharging or for charging, depending on the power generation state of the solar cell 3 and the charge amount of the battery 2.
The following describes in detail the setting operation of the first DC/DC11 by the switching control unit 18 with reference to fig. 5.
Referring to fig. 5, in order to determine whether or not power generation of the solar cell 3 is performed, the exchange control unit 18 determines whether or not the generated current Ipv detected by the current sensor 16 is 0 (a) or less (step S101). Further, the presence or absence of power generation may be determined not based on the generated current Ipv but based on the output of a separately provided illuminometer, and the presence or absence of power generation may be determined based on the time.
When the generated current Ipv is 0 (a) or less in step S101, the switching control unit 18 determines that the solar cell 3 is in the non-generated state. Then, the exchange control unit 18 determines whether or not the SOC calculated by the charge amount detection unit 17 is a lower threshold TH for determining whether or not the remaining battery amount is sufficient 1 (e.g., 20%) or more (step S102).
When the SOC is the lower threshold TH in step S102 1 In the above case, the switching control unit 18 determines that the remaining battery level is sufficient, and sets the first DC/DC11 to be for discharge (step S103). This allows the DC connection bus 20 to be connected to a dischargeable state in which electric power can be exchanged with other power storage devices 1. Further, the second DC/DC 12 connected to the battery 2 is in a stable supply state of the load current Ir supplied to the load 4 and the first DC/DC11, because of the DC link voltage constant control.
When the SOC is smaller than the lower threshold TH in step S102 1 If the switching control unit 18 determines that the remaining battery level is insufficient, the first DC/DC11 is set to be used for charging (step S104). From the following componentsIn this state, the DC link bus 20 is connected to the other power storage device 1 and exchanges electric power. Further, the second DC/DC 12 connected to the battery 2 is in a steady supply state for the load current Ir and a steady charge state from the first DC/DC11, because of the DC link voltage constant control.
When the generated current Ipv exceeds 0 (a) in step S101, the switching control unit 18 determines that the solar cell 3 is in the power generation state. Then, the switching control unit 18 determines whether or not the SOC calculated by the charge amount detection unit 17 is an upper threshold TH for determining whether or not the remaining battery level is close to full charge 2 (e.g., 70%) or more (step S105). In addition, the upper threshold TH 2 Is set to be lower than the lower threshold TH 1 Large values.
When the SOC is the upper threshold TH in step S105 2 In the above case, the switching control unit 18 determines that the remaining battery level is near full charge, and sets the first DC/DC11 to be for discharge (step S103). This allows the DC connection bus 20 to be connected to and exchange electric power with other power storage devices 1. Since the second DC/DC 12 connected to the battery 2 is the DC link voltage constant control, it is in a stable supply state to the load current Ir and the first DC/DC11 when the total power generation amount Ic is less than zero, and is in a stable charge state of the generated power and a stable supply state to the first DC/DC11 when the total power generation amount Ic is zero or more. In addition, as shown in fig. 1, the total power generation amount when viewed from the MPPT DC/DC converter 13 and the PCS 14 is defined as Ic.
When the SOC is smaller than the upper threshold TH in step S105 2 If the battery remaining amount is not close to full charge but there is a surplus in electric power storage, the switching control unit 18 sets the first DC/DC11 as the charging source (step S104). Thereby, the rechargeable battery is connected to DC connection bus 20 and exchanges electric power with other power storage device 1. Since the second DC/DC 12 connected to the battery 2 is the DC link voltage constant control, it is in a stable supply state of the load current Ir and a stable charge state of the generated power when the total power generation amount Ic is less than zero, and is in a stable charge state of the generated power when the total power generation amount Ic is zero or more.
The exchange control unit 18 periodically performs the determinations of steps S101, S102, and S105, and executes the setting operation when the determinations of steps S101, S102, and S105 are changed. This allows the solar cell 3 to operate in accordance with the power generation state and the change in the charge amount of the battery 2.
Thus, in a state where the solar cell 3 does not generate electricity at night, the charge amount is sufficient and the SOC is the lower threshold TH 1 The above power storage device 1 stands by as a dischargeable state. Further, the SOC is smaller than the lower threshold value TH 1 The power storage device 1 of (a) can be shifted to a chargeable state and can receive exchange of electric power.
In a state where the solar cell 3 generates electricity during the daytime and the battery 2 is charged, the charge amount of the battery 2 is small and the SOC is smaller than the upper threshold TH 2 The power storage device 1 of (1) stands by as a chargeable state. Further, the SOC is the lower threshold value TH 1 The above power storage device 1 transitions from the chargeable state to the dischargeable state, and exchanges electric power with the power storage device 1 standing by in the chargeable state.
In the present embodiment, the description has been made of the case where the slopes of the discharge characteristic and the charge characteristic of the first DC/DC11 in each power storage device 1 are the same. However, the discharge characteristic and the charge characteristic can be controlled by controlling the slope to weight the charge/discharge amount. That is, when the first DC/DC11 having different slopes of the discharge characteristic are connected in parallel, the discharge amount of the first DC/DC11 having a larger slope of the discharge characteristic is larger. Similarly, when the first DC/DC11 having different slopes of the charging characteristic are connected in parallel, the charge amount of the first DC/DC11 having a larger slope of the charging characteristic is larger.
In the present embodiment, the first DC/DC11 of the power storage device 1 is set to either one of the charging and discharging states, but a stopped state may be set as a state between the charging and discharging states.
In this case, for example, a specific lower threshold TH is set 1 A small lower limit threshold (e.g., 10%), and is set to be smaller than the upper threshold TH 2 Large upper limit threshold (e.g，90％)。
In the case where the generated current Ipv is 0 (a) or less in step S101, the SOC may be set to the lower threshold TH 1 The discharge is set when the SOC is smaller than the lower threshold value TH 1 And is set to a stop state when the SOC is equal to or higher than the lower limit threshold value, and is set to be used for charging when the SOC is lower than the lower limit threshold value.
In the case where the generated current Ipv exceeds 0 (a) in step S101, the SOC may be set to be equal to or higher than the upper limit threshold value, and the SOC may be set to be lower than the upper limit threshold value and to be equal to or higher than the upper threshold value TH 2 The above state is set to a stop state, and the SOC is smaller than the upper threshold value TH 2 And is set for charging.
As described above, according to the present embodiment, the power storage system is provided in which power exchange is performed between the plurality of power storage devices 1 connected to the DC link bus 20 in the power storage device 1 to which the battery 2 storing DC power is connected as a basic unit, wherein the power storage device 1 is connected to the DC link bus 20 via the first DC/DC11, and the first DC/DC11 can be set to be used for discharging based on a discharging characteristic in which a discharging current decreases as a grid voltage of the DC link bus 20 increases or to be used for charging based on a charging characteristic in which a charging current increases as the grid voltage increases, and when a current in a discharging direction in the discharging characteristic is defined as positive and a current in a charging direction in the charging characteristic is defined as positive, the discharging characteristic and the charging characteristic are set to be crossed.
With this configuration, it is not necessary to perform centralized management of power exchange control, and small-sized power storage devices 1 can be distributed and installed for a self-consuming (home-consuming) system. Further, by switching only the first DC/DC11 connected to the DC connection bus 20 between the discharging and charging, the power exchange control between the power storage devices 1 can be performed, and an inexpensive system with high energy efficiency and reduced risk can be realized.
In the present embodiment, the grid voltage V is zero when the discharge current is zero in the discharge characteristic 2 Is set as the upper voltage limit value of the grid voltage, and is charged in the charging characteristicGrid voltage V at zero current 1 Is set as the lower voltage limit of the grid voltage.
With this structure, the grid voltage V at the operating points A to C a ～V c Are all the specific grid voltage V 1 Large and specific grid voltage V 2 Low value. Thus, the grid voltage is applied in an appropriate range.
The present embodiment further includes an exchange control unit 18, and the exchange control unit 18 sets the first DC/DC11 to be used for discharging when the charge amount of the battery 2 is equal to or greater than a threshold value, and sets the first DC/DC11 to be used for charging when the charge amount of the battery 2 is less than the threshold value, based on the charge amount of the battery.
With this configuration, the first DC/DC11 connected to the DC connection bus 20 can be switched between the discharge and charge according to the charge amount of the battery.
In the present embodiment, when the solar cell 3 is connected to the power storage device 1 as the power generation device, if the exchange control unit 18 determines that the solar cell 3 is in the non-power generation state, the charge amount in the battery 2 is the lower threshold TH for determining whether or not the power generation state is sufficient 1 In the above case, the first DC/DC11 is set for discharging, and the charge amount of the battery 2 is smaller than the lower threshold TH 1 In the case of (2), the first DC/DC11 is set to be used for charging, and when it is determined that the solar cell 3 is in the power generation state, the charge amount in the storage battery 2 is the upper threshold TH for determining whether or not the full charge is near 2 In the above case, the first DC/DC11 is set for discharging, and the charge amount of the battery 2 is smaller than the upper threshold TH 2 In the case of (2), the first DC/DC11 is set as a charging source.
With this configuration, the power exchange control can be changed appropriately at night and daytime when the power generation state of the solar cell 3 is changed.
Further, the present embodiment provides the power storage device 1, in which the power storage device 1 is connected between the battery 2 storing direct-current power and the DC link bus 20, and the other power storage device 1 connected to the DC link bus 20, and the power storage device 1 is connected to the DC link bus 20 via the first DC/DC11, and the first DC/DC11 can be set to be used for discharging based on a discharging characteristic in which a discharging current decreases with an increase in grid voltage of the DC link bus 20, or to be used for charging based on a charging characteristic in which a charging current increases with the increase in grid voltage, and in a case where a current in a discharging direction in the discharging characteristic is defined as positive and a current in a charging direction in the charging characteristic is defined as positive, the discharging characteristic and the charging characteristic are set to be crossed.
With this configuration, the power storage device 1 can be easily connected to a self-consuming (home-consumption) side power system without requiring centralized management of power exchange control. Further, by switching the first DC/DC11 connected to the DC connection bus 20 between the discharging and charging modes, the power exchange control with the other power storage device 1 can be performed, and an inexpensive system with high energy utilization efficiency and reduced risk can be realized.
The present invention has been described in detail with reference to specific embodiments, but the above embodiments are merely examples, and it is needless to say that the present invention can be modified and implemented without departing from the scope of the present invention.
Claims (6)
1. An electric storage system in which electric power exchange is performed between a plurality of electric storage devices connected to a DC connection bus in a unit of an electric storage device to which a battery for storing DC power is connected,
the plurality of power storage devices each include:
a first bidirectional DC/DC converter connected to the DC link bus; and
an exchange control unit that sets the first bidirectional DC/DC converter to be used for charging or discharging,
the first bidirectional DC/DC converter controls charging or discharging individually by control of a grid voltage of the DC link bus according to an output voltage characteristic in which a discharge characteristic has a negative slope in which the grid voltage increases due to a decrease in the discharge current when a current in a discharge direction is defined as positive, and a charge characteristic has a positive slope in which the grid voltage increases due to an increase in the charge current when a current in a charge direction is defined as positive, the discharge characteristic and the charge characteristic being set to intersect.
2. The electricity storage system according to claim 1, wherein,
the grid voltage at which the discharge current is zero in the discharge characteristic is set as a voltage upper limit value of the grid voltage, and the grid voltage at which the charge current is zero in the charge characteristic is set as a voltage lower limit value of the grid voltage.
3. The electricity storage system according to claim 1, wherein,
the switching control unit sets the first bidirectional DC/DC converter for discharging when the charge amount of the battery is equal to or greater than a threshold value, and sets the first bidirectional DC/DC converter for charging when the charge amount of the battery is less than the threshold value, based on the charge amount of the battery.
4. The electricity storage system according to claim 2, wherein,
the switching control unit sets the first bidirectional DC/DC converter for discharging when the charge amount of the battery is equal to or greater than a threshold value, and sets the first bidirectional DC/DC converter for charging when the charge amount of the battery is less than the threshold value, based on the charge amount of the battery.
5. The power storage system according to any one of claims 1 to 4, wherein,
when the power storage device is connected to the power generation device, the exchange control unit sets the first bidirectional DC/DC converter for discharging when the charge amount of the battery is equal to or greater than a lower threshold value for determining whether the battery is in a non-power generation state, sets the first bidirectional DC/DC converter for charging when the charge amount of the battery is less than the lower threshold value, and sets the first bidirectional DC/DC converter for discharging when the charge amount of the battery is equal to or greater than an upper threshold value for determining whether the battery is in a power generation state, and sets the first bidirectional DC/DC converter for charging when the charge amount of the battery is equal to or greater than an upper threshold value for determining whether the battery is in a full charge state.
6. An electric storage device that is connected between a battery that stores direct-current electric power and a DC connection bus and performs electric power exchange with other electric storage devices connected to the DC connection bus, the electric storage device characterized by comprising:
a first bidirectional DC/DC converter connected to the DC link bus; and
an exchange control unit that sets the first bidirectional DC/DC converter to be used for charging or discharging,
the first bidirectional DC/DC converter controls charging or discharging individually by control of a grid voltage of the DC link bus according to an output voltage characteristic in which a discharge characteristic has a negative slope in which the grid voltage increases due to a decrease in the discharge current when a current in a discharge direction is defined as positive, and a charge characteristic has a positive slope in which the grid voltage increases due to an increase in the charge current when a current in a charge direction is defined as positive, the discharge characteristic and the charge characteristic being set to intersect.
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| JP7472602B2 (en) | 2020-03-31 | 2024-04-23 | 株式会社Ｇｓユアサ | Energy storage system and energy storage device |
| CN116615854A (en) * | 2021-01-04 | 2023-08-18 | 国立大学法人东北大学 | Electric power system |
| JP7264181B2 (en) * | 2021-01-29 | 2023-04-25 | 株式会社豊田中央研究所 | power supply system |
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| CN110176788A (en) | 2019-08-27 |
| JP6458891B1 (en) | 2019-01-30 |
| JP2019146314A (en) | 2019-08-29 |
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