JP2015195674A - Power storage battery assembly control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage battery assembly control system in which each of plural power storage battery units is controlled to be prevented from falling into overcurrent, overvoltage state when the plural power storage units are connected in parallel on a DC bus line and charged.SOLUTION: A power storage battery assembly control system 10 has plural power storage battery units 31, plural DC/DC converters 21 connected to the power storage battery units 31, a DC bus line 14 for connecting the power storage battery units 31 in parallel through the DC/DC converters 21, and PCS 13 which is connected and disposed between an external power line containing an external charging power source 11 and an external discharging load 12 and the DC bus line 14, and a control device 40. The control device 40 acquires the charging/discharging state of each power storage battery unit 31 and the conditions of the external charging power source 11 and the external discharging load 12, transmits a charging/discharging instruction to PCS 13, and transmits a charging/discharging start instruction or charging/discharging stop instruction for each power storage battery unit 31.

Description

  The present invention relates to a storage battery assembly control system that controls charging and discharging of a storage battery assembly to which a plurality of storage batteries are connected.

  A secondary battery such as a lithium-ion battery has a unit storage battery called a unit battery having a voltage between terminals of about 3 V to 4 V and a small charge / discharge current capacity. Therefore, a storage battery unit or the like obtained by unitizing a plurality of unit cells in series connection or parallel connection is used.

  In Patent Document 1, as a storage battery assembly control system, when a plurality of storage battery units are connected in parallel to a charge / discharge bus line of one power converter, the voltage of each storage battery unit is different. It is pointed out that current flows from higher to lower, and in some cases an excessive current occurs.

JP2012-205410A

  In addition to the indication of the fear of overcurrent in Patent Document 1, when a plurality of storage battery units are connected in parallel to the charge / discharge bus line of one power conversion device, the time when each storage battery unit is fully charged is not necessarily limited. Since they do not match, it may occur that the charging current concentrates on the storage battery unit that is not yet fully charged, resulting in an overvoltage.

  An object of the present invention is to provide a storage battery assembly control system capable of controlling each storage battery unit so as not to become overcurrent and overvoltage when a plurality of storage battery units are connected in parallel to a bus line and charged. .

  A storage battery assembly control system according to the present invention includes a plurality of storage battery units each provided with a storage battery, a plurality of DC / DC converters connected to each storage battery unit, and a plurality of storage battery units via each DC / DC converter. A DC bus line connected in parallel; a power converter connected between an external power line including an external charging power source and an external discharge load; and a DC bus line; and a control device. The charging / discharging state of the unit and the status of the external charging power source and the external discharging load are acquired, a charging / discharging command is transmitted to the power converter, and a charging / discharging start command or charging / discharging stop command is transmitted to each storage battery unit.

  According to the storage battery assembly control system configured as described above, charge / discharge control can be appropriately performed.

  According to the storage battery assembly control system configured as described above, each storage battery unit is not directly connected to the DC bus line, but is connected in parallel to the DC bus line via the DC / DC converter. Thereby, it becomes possible to perform an appropriate charging / discharging process etc. via a DC / DC converter according to the charging / discharging state of a storage battery unit, and it can control so that a storage battery unit does not become an overcurrent, an overvoltage, and an overdischarge.

It is a block diagram of the storage battery assembly control system in the embodiment according to the present invention. It is a figure which shows the detail of the DC / DC converter and storage battery unit in FIG. FIG. 2A is an overall configuration diagram, and FIG. 2B is an internal configuration diagram of a plurality of storage battery packs constituting the storage battery unit. (C) is a figure which shows the relationship between the step-down control voltage range of a DC / DC converter, the step-up control voltage range, and the DC bus line constant voltage command value with respect to the power converter device at the time of charge. It is a figure which shows the constant current charge and constant voltage charge with respect to a storage battery unit. In the storage battery assembly control system according to the embodiment of the present invention, FIG. FIG. 5 is a diagram illustrating control when one storage battery unit reaches a charging voltage defined by characteristics of the storage battery pack, following FIG. 4. FIG. 6 is a diagram illustrating control when all the storage battery units have reached a charging voltage defined by the characteristics of the storage battery pack, following FIG. 5. FIG. 7 is a diagram illustrating control when one storage battery unit reaches full charge, following FIG. 6. FIG. 8 is a diagram illustrating when all the storage battery units have reached full charge, following FIG. 7. In the storage battery assembly control system according to the embodiment of the present invention, FIG. FIG. 10 is a diagram illustrating control when one storage battery unit is discharged after FIG. 9. FIG. 11 is a diagram illustrating a time when all the storage battery units are discharged after FIG. 10.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. Below, although a lithium ion battery is demonstrated as a storage battery, secondary batteries other than this may be sufficient. For example, a nickel hydrogen battery, a nickel cadmium battery, or the like may be used. Since the storage battery assembly is for obtaining the voltage and current to correspond to the required power of the load, the number of unit cells constituting the storage battery assembly, the number of storage battery packs (BP) combining the unit cells, The number of storage battery units (BU) combined with the storage battery pack (BP) may be appropriate according to the specifications of the storage battery assembly control system.

  In addition, the power value, current value, voltage value, charge / discharge time, and the like described below are examples for explanation, and can be appropriately changed according to the specifications of the storage battery assembly control system. Below, the same code | symbol is attached | subjected to the same element in all the drawings, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a diagram illustrating a configuration of a storage battery assembly control system 10. In the storage battery assembly control system 10, an external charging power source 11 and an external discharge load 12 are connected to a PCS 13 that is a power converter, and the PCS 13 is connected to a DC bus line 14. Five storage battery units 31, 32, 33, 34, and 35 constituting the storage battery assembly 30 are connected in parallel to the DC bus line 14 via five DC / DC converters 21, 22, 23, 24, and 25. The In order to perform optimal charge / discharge control among the external charging power source 11, the external discharge load 12, and the storage battery assembly 30, the storage battery assembly control system 10 includes a PCS 13 and five DC / DC converters. This is a system for controlling the operations of 21, 22, 23, 24 and 25.

  FIG. 2 is a diagram showing a detailed configuration of one DC / DC converter 21 and one storage battery unit 31 connected thereto in FIG.

  In FIG. 1 and subsequent figures, the five DC / DC converters 21, 22, 23, 24, and 25 are abbreviated as “DC / DC 1 to 5”, and the five storage battery units 31, 32, 33, 34, and 35 are abbreviated. "BU1-5". In the following drawings, the power lines are indicated by thick lines and the signal lines are indicated by thin lines.

  The external charging power source 11 is an external commercial power source. The external commercial power source is a single-phase or three-phase AC power source, and it combines the power generated by various power generation methods such as hydropower generation, nuclear power generation, and thermal power generation according to fluctuations in power supply and demand. Supplied by the power company. Other external charging power sources such as solar power generation power and wind power generation power may be used.

  The external discharge load 12 is a device that operates by receiving supply of DC power. For example, the external discharge load 12 is a factory load, which includes mechanical equipment, general lighting, general air conditioning, kitchen appliances, office equipment such as servers and PCs, and factory air conditioning.

  The PCS 13 is a power conversion device. PCS is an abbreviation for Power Conditioner System. The PCS 13 is a device that performs power conversion between the AC power of the external charging power supply 11, the DC power of the storage battery assembly 30, and the DC power of the external discharge load 12. The PCS 13 performs conversion from AC power to DC power when charging the storage battery assembly 30 from the external charging power supply 11, and from DC power to AC power when returning power from the storage battery assembly 30 to the external charging power supply 11. It functions as a bi-directional AC / DC converter that can perform the conversion. Further, when the PCS 13 discharges from the storage battery assembly 30 to the external discharge load 12, the PCS 13 can perform voltage conversion for boosting or stepping down in order to match the voltage of the storage battery assembly 30 with the voltage of the external discharge load 12. Functions as a DC voltage converter.

  Note that when the external charging power supply 11 is DC power such as solar power generation or wind power generation, the PCS 13 is a bidirectional DC voltage converter capable of stepping up and down. As described above, the PCS 13 is a power conversion device having functions of bidirectional AC / DC power conversion and bidirectional DC voltage conversion. However, depending on the specifications of the storage battery assembly control system 10, the bidirectional AC / DC power conversion or the bidirectional DC voltage is used. Only one function of conversion may be provided. The PCS 13 is connected to the control device 40 through an appropriate signal line, and executes power conversion under the control of the control device 40.

  The DC bus line 14 is a power line that connects a plurality of storage battery units 31, 32, 33, 34, and 35 in parallel via DC / DC converters 21, 22, 23, 24, and 25.

  The five DC / DC converters 21, 22, 23, 24, and 25 are DC voltage converters connected in series to the five storage battery units 31, 32, 33, 34, and 35, respectively. Instead of connecting the five storage battery units 31, 32, 33, 34, 35 directly in parallel to the DC bus line 14, the storage battery units 31, 22, 23, 24, 25 are connected via the DC / DC converters 21, 22, 23, 24, 25. By connecting 32, 33, 34, and 35 to the DC bus line 14 in parallel, even if the voltages of the storage battery units 31, 32, 33, 34, and 35 are different, the DC bus line 14 is different due to the difference in voltage. The current can be prevented from flowing through.

  Each of the five storage battery units 31, 32, 33, 34, and 35 is a unit obtained by connecting a plurality of unit cells in series or in parallel by a predetermined connection method. Since all of the five storage battery units 31, 32, 33, 34, and 35 have the same configuration, description will be made using the storage battery unit 31. As shown in FIG. 2 (a), the storage battery unit 31 is configured by connecting storage battery pack rows in which a predetermined number of storage battery packs (BP) are connected in parallel in series at a predetermined number of stages. In the example of FIG. 2A, five storage battery packs (BP) are connected in parallel to form one storage battery pack row, and the storage battery pack rows are connected in eight stages in series to form one storage battery unit 31. The That is, one storage battery unit 31 includes (5 × 8 = 40) storage battery packs (BP).

  Each storage battery pack (BP) has the same structure, and as shown in FIG. 2 (b), a unit cell array in which a predetermined number of unit cells are connected in parallel is connected in series with a predetermined number of stages. Composed. In the example of FIG. 2B, 24 unit cells are connected in parallel to form one unit cell array, and the unit cell arrays are connected in 13 stages in series to form one storage battery pack (BP). . That is, one storage battery pack (BP) is composed of (24 × 13 = 312) unit cells.

Here, the unit cell is a lithium ion battery having a voltage between terminals of about 3V to about 4V. Therefore, the voltage between the terminals of one storage battery pack (BP) is {(about 3V to about 4V) × 13} = (about 39V to about 52V). The inter-terminal voltage V _BU of one storage battery unit 31 is {(about 39V to about 52V) × 8} = (about 312V to about 416V). This is an example, and differs depending on the unit cell specifications, the storage battery pack (BP) configuration specifications, the storage battery unit 31 configuration specifications, and the like.

  Returning to the description of the five DC / DC converters 21, 22, 23, 24, and 25 again. Since the DC / DC converters 21, 22, 23, 24, and 25 all have the same configuration, the DC / DC converter 21 connected to the storage battery unit 31 will be described. The DC / DC converter 21 includes a step-up unit 26 and a step-down unit 27.

  The boosting unit 26 operates when discharging the storage battery unit 31. When the storage battery unit 31 is discharged, when the state of charge (SOC) of the storage battery unit 31 is a high value that does not cause overdischarge, the discharge according to the discharge power value commanded to the PCS 13 or a predetermined value is determined. Discharge is performed at a constant discharge current value. The constant discharge current value is a value determined by the circuit configuration of the DC / DC converter 21 or the like.

  When the voltage of the DC bus line 14 decreases due to discharge, the boost unit 26 adjusts the amount of current that flows from the storage battery unit 31 to the DC bus line 14 so that the voltage of the DC bus line 14 falls within a predetermined boost control voltage range. To work. When the discharge power commanded to the PCS 13 is large, the voltage drop of the DC bus line 14 increases, and the amount of current that the boost unit 26 passes from the storage battery unit 31 to the DC bus line 14 increases. On the contrary, when the discharge power is small, the voltage drop of the DC bus line 14 is small, and the amount of current that the boosting unit 26 flows from the storage battery unit 31 to the DC bus line 14 is small.

FIG. 2A shows (about 420 V to about 430 V) as an example of the boost control voltage range. This value is an example for explanation, and may be a voltage value higher than about 416 V that is the upper limit value of the inter-terminal voltage V _BU of one storage battery unit 31. In the case of a configuration in which the number of storage battery packs (BP) connected in series is reduced, the inter-terminal voltage V _BU of the storage battery unit 31 is lowered, so that it can be set to a lower value.

  The step-down unit 27 operates when charging the storage battery unit 31. When the storage battery unit 31 is charged, if the SOC of the storage battery unit 31 is low enough to prevent overcharging, charging according to the charging power commanded to the PCS 13 or constant current charging at a predetermined constant charging current value (Constant Current Charging: CC Charging) is performed. The constant discharge current value is a value determined by the circuit configuration of the DC / DC converter 21 or the like.

  When the voltage of the DC bus line 14 increases due to charging, the step-down unit 27 adjusts the amount of current flowing from the DC bus line 14 to the storage battery unit 31 so that the voltage of the DC bus line 14 falls within a predetermined step-down control voltage range. To work. When the charging power commanded to the PCS 13 is large, the voltage rise of the DC bus line 14 increases, and the amount of current that the step-down unit 27 passes from the DC bus line 14 to the storage battery unit 31 increases. Conversely, when the charging power is small, the voltage rise of the DC bus line 14 is small, and the amount of current that the step-down unit 27 passes from the DC bus line 14 to the storage battery unit 31 is small.

  FIG. 2A shows (about 440 V to about 450 V) as an example of the step-down control voltage range. This value is also an example for indicating that the step-down control voltage range is higher than the step-up control voltage range, and may be a value other than this.

  FIG. 2C is a diagram showing the relationship between the step-down control voltage range and the step-up control voltage range. Here, a line indicated as 460 V in FIG. 2C is a value of a constant voltage command that the control device 40 outputs to the PCS 13 when the storage battery assembly 30 is charged, as will be described later. As shown in FIG. 2 (c), the value of the constant voltage command that the control device 40 outputs to the PCS 13 when the storage battery assembly 30 is charged is set higher than the upper limit of the step-down control voltage range of the step-down unit 27. The effect by setting in this way is mentioned later.

FIG. 3 is a diagram schematically showing CC charging and CV charging. The horizontal axis is time, t = t ₀ is the charge start time, t = t ₁ is the time for switching from CC charge to CV charge, and t = t ₂ is the charge end time. The vertical axis represents the charging current I and the voltage V between the terminals of the storage battery unit 31. As shown in FIG. 3, the period from t = t ₀ to t = t ₁ is a CC charging period in which charging is performed at a constant value of charging current I = I ₀ . Due to the CC charging, the inter-terminal voltage V of the storage battery unit 31 rises from the discharge end voltage V _S. When the terminal voltage V rises sufficiently and the time t = t ₁ that satisfies the standard such as the charging voltage specified by the characteristics of the storage battery pack (BP) is reached, the terminal voltage V = V ₀ falls below a certain value. Will continue charging. This is CV charging. The charging current I gradually decreases due to the CV charging, and the CV charging is stopped at a time t = t ₂ that satisfies a criterion such as having a longer time for further charging. This time is the charging end time.

In the case of FIG. 2A, until the voltage V between terminals reaches V = 416V, charging according to the charging power value commanded to the PCS 13 or CC charging is executed, and the time t when the voltage between terminals V reaches 416V is reached. CV charging is performed from = t _1. In the CV charging, the step-down unit 27 controls the current flowing from the DC bus line 14 to the storage battery unit 31 so that the voltage on the storage battery unit 31 side becomes a constant value (step-down output voltage limit value).

  Returning to FIG. 1 again, the control device 40 controls the operation of each element constituting the storage battery assembly control system 10 as a whole, and appropriately charges and discharges the storage battery assembly 30. Such a control device 40 can be a computer or the like.

  The control device 40 includes an external status acquisition unit 41 that acquires the status of the external charging power source 11 and the external discharge load 12, and a storage battery unit charge that acquires the SOC that is the charge / discharge status of the storage battery units 31, 32, 33, 34, and 35. A discharge state acquisition unit 42, a charge / discharge command transmission unit 43 that determines whether to charge or discharge the storage battery assembly 30 based on the acquired contents, and transmits a charge / discharge command to the PCS 13; And a charge / discharge start / stop command transmission unit 44 for transmitting a charge / discharge start command or a stop command to the DC / DC converters 21, 22, 23, 24, 25. The discharge start command or stop command is an operation start command or operation stop command for the boost unit 26, and the charge start command or stop command is an operation start command or operation stop command for the step-down unit 27.

  The external status acquisition unit 41 determines whether or not the external charging power source 11 is operating normally without a power failure and is capable of charging the storage battery assembly 30 and whether the external discharge load 12 is in operation for the storage battery assembly. It is determined whether power supply from 30 is required. These determinations are made by connecting the control device 40 to the external charging power source 11 and the external discharging load 12 through appropriate signal lines, and acquiring the state of the external charging power source 11 and the state of the external discharging load 12. For example, the current state is nighttime and the external discharge load 12 is in a stopped state, and the external charging power supply 11 has a power supply capacity. For example, 250 kW of power is supplied for about 2 hours. Acquire that it is possible.

  The storage battery unit charge / discharge state acquisition unit 42 acquires the SOC of the storage battery units 31, 32, 33, 34, and 35. For example, with respect to the storage battery units 31, 32, 33, 34, and 35, it is acquired that the SOC is in a low state to such an extent that any of the five storage battery unit arrays are not overcharged even if they are charged. The SOC of the storage battery unit is obtained by connecting the control device 40 and the storage battery pack (BP) or unit cell constituting each of the storage battery units 31, 32, 33, 34, 35 with an appropriate signal line, and for each storage battery pack (BP). The inter-terminal voltage or the inter-terminal voltage of each unit cell is acquired, and the SOC of the storage battery units 31, 32, 33, 34, and 35 is estimated and acquired from these. The current flowing through the storage battery pack (BP) or the voltage between the terminals of the unit cell may be acquired in accordance with or instead of the acquisition. Moreover, the temperature of a storage battery pack (BP) or the temperature of a unit cell can also be acquired.

  The charge / discharge command transmission unit 43 transmits the charge / discharge power amount to the PCS 13 as a charge / discharge command. For example, in the above case, a charge / discharge command is issued by transmitting the content of “charge power of 250 kW for 2 hours” to the PCS 13. Here, when discharging is performed, the discharge power amount represented by (discharge power amount = power × time) is transmitted to the PCS 13 as described above. The power value can be given as a charge / discharge command instead of the amount of power, the external status acquisition unit 41 can acquire the status of the external charging power supply 11 and the external discharge load 12 in real time, and the power value can be changed according to the status. it can.

  When charging is performed, charging is performed in accordance with the charging power value commanded to the PCS 13 in the initial stage of charging, so that a constant amount of power continues for a predetermined time (charging power amount = power × time). Is transmitted to the PCS 13. When charging proceeds to CV charging, for example, the content “continue charging so that the voltage on the storage battery unit 31 side is 416 V” is transmitted to the DC / DC converter 21. 416 V is a step-down output voltage limit value for the DC / DC converter 21. At this time, a constant voltage charging command is transmitted to the PCS 13 so that the voltage of the DC bus line 14 becomes a constant value higher than the upper limit value of the step-down control voltage range by a predetermined value. In the above example, since the upper limit value of the step-down control voltage range is 450V, the constant voltage charge command is 460V, which is higher than 450V by 10V, and the content of the constant voltage charge command is “DC bus line 14 becomes 460V. The content of “control the charging current to” is transmitted to the PCS 13.

  The reason for controlling the voltage of the DC bus line 14 to be higher than the upper limit value of the step-down control voltage range when shifting to CV charging is to allow the PCS 13 to control the voltage of the DC bus line 14. is there. In other words, the PCS 13 operates so as to adjust the amount of current flowing from the external charging power supply 11 to the DC bus line 14 and maintain the voltage of the DC bus line 14 at a predetermined voltage in accordance with a constant voltage charging command. At this time, the remaining four DC / DC converters 22, 23, 24, and 25 except for the DC / DC converter 21 that has shifted to the CV charge control of the storage battery unit 31 have constant current charge control at a predetermined constant charge current value ( (CC charge control). Even if any of the five storage battery units 31, 32, 33, 34, 35 is reduced in charging current value by CV charging or when it is fully charged, the PCS 13 adjusts the amount of current. On the other hand, CC charging can be continued without changing the charging current.

  Suppose that the charging power amount represented by (charging power amount = power × time) continues to be transmitted to the PCS 13 even after shifting to CV charging. In this case, when any of the storage battery units 31, 32, 33, 34, and 35 is fully charged, the storage battery unit stops its operation by the function of the charge / discharge start / stop command transmission unit 44. The total amount of (power x time) is concentrated in the other four storage battery units.

  Furthermore, when four of the five storage battery units are fully charged, the total amount of (charging power amount = power × time) is concentrated on the remaining one. Each of the storage battery units 31, 32, 33, 34, and 35 has an upper limit value of charging current, and the DC / DC converters 21, 22, 23, 24, and 25 limit the charging current. In this case, a charging current cannot flow, and the voltage of the DC bus line 14 exceeds the step-down control voltage range in order to protect the power value as the command value. The PCS 13 flows from the external charging power supply 11 to the DC bus line 14 by controlling the voltage of the DC bus line 14 to maintain a constant voltage value of 460 V that is higher than the upper limit value of the step-down control voltage range by a predetermined value. The amount of current can be adjusted. As a result, for example, it can be avoided that the total amount of (charging power amount = power × time) is concentrated on the remaining one storage battery unit, and charging can be continued safely.

  The charge / discharge start / stop command transmission unit 44 is in a state where the state acquired by the external state acquisition unit 41 is capable of charging / discharging the storage battery assembly 30, and the SOC acquired by the storage battery unit charge / discharge state acquisition unit 42 is When charging / discharging is accepted, a command to start charging / discharging the storage battery units 31, 32, 33, 34, 35 is transmitted to the DC / DC converters 21, 22, 23, 24, 25. Moreover, when charging / discharging progresses and the SOC acquired by the storage battery unit charging / discharging state acquisition unit 42 is in a state where it does not accept any more charging / discharging, a command to stop the operation of the storage battery unit is transmitted. . More specifically, the stop command for the discharge operation of the storage battery units 31, 32, 33, 34, 35 is an operation stop command for each booster unit 26 of the DC / DC converters 21, 22, 23, 24, 25, The stop command for the charging operation of the storage battery units 31, 32, 33, 34, 35 is an operation stop command for each step-down unit 27 of the DC / DC converters 21, 22, 23, 24, 25.

  Such a function can be realized by executing software in the control device 40. Specifically, it can be realized by executing a charge / discharge program in the control device 40. A part of the above functions may be realized by hardware.

  The operation of the above configuration will be described with reference to FIGS. These diagrams simplify the configuration diagram of FIG. 2, and further show the state of one PCS 13 and five DC / DC converters 21, 22, 23, 24, 25 from the upper side to the lower side of the page. FIG. Here, the content acquired by the external status acquisition unit 41 in the control device 40, the content acquired by the storage battery unit charge / discharge state acquisition unit 42, and the PCS 13 by the charge / discharge command transmission unit 43 in order from the upper side to the lower side of the page. Command contents to the five DC / DC converters 21, 22, 23, 24, 25 by the charge / discharge start / stop command transmission unit 44, five DC / DC converters 21, 22, 23, 24, 25 The control contents of were shown.

FIGS. 4 to 8 are diagrams showing the situation at the time of charging, FIG. 4 is when charging is started, and FIG. 5 is that the voltage V _BU between terminals of one storage battery unit 31 is defined from the characteristics of the storage battery pack (BP). When the charge voltage limit value (step-down output voltage limit value) is reached and the CV discharge is switched, FIG. 6 further proceeds and the inter-terminal voltage V _BU of all the storage battery units becomes the charge voltage limit value (step-down output voltage limit value). 7 shows the situation when one storage battery unit 31 is fully charged, and FIG. 8 shows the situation when all the storage battery units are fully charged and charging is completed.

  As an example in which the charging process is performed, at night, the external discharge load 12 is not in operation, and power supply from the storage battery unit is unnecessary, and the external charging power source 11 has surplus power, which is about 2 h at 250 kW. It is assumed that the power can be supplied.

  FIG. 4 shows a state at the start of charging, and the situation acquired by the external situation acquisition unit 41 does not require power supply to the external discharge load 12 as described above, and the external charging power supply 11 is about 2 h at 250 kW. Can be supplied. The state acquired by the storage battery unit charge / discharge state acquisition unit 42 is within a range in which the SOCs of the five storage battery units 31, 32, 33, 34, and 35 can be charged. “Chargeable” means a state in which overcharging is not performed even when charging is performed. The command to the PCS 13 by the charge / discharge command transmission unit 43 is “charge at 250 kW for 2 hours”. Commands to the five DC / DC converters 21, 22, 23, 24, and 25 by the charge / discharge start / stop command transmission unit 44 are "start charging" (start the operation of the step-down unit 27). As another embodiment, the command to the PCS 13 by the charge / discharge command transmission unit 43 may be “maintain the voltage of the DC bus line 14 at a constant 460 V and charge for 2 hours” as voltage control.

  In this case, the five DC / DC converters 21, 22, 23, 24, and 25 operate so that the voltage of the DC bus line 14 falls within a predetermined step-down control voltage range in accordance with the charging power value commanded to the PCS 13. The storage battery units 31, 32, 33, 34, and 35 are charged. Therefore, in order to charge the storage battery units 31, 32, 33, 34, and 35 at 250 kW for 2 hours, the PCS 13 converts the AC power of the external charging power source 11 into DC power for 2 hours.

  FIG. 5 is a diagram showing the control when the charging process proceeds from FIG. 4 and one storage battery unit 31 reaches the charge voltage limit value (step-down output voltage limit value) defined by the characteristics of the storage battery pack (BP). It is. Here, the command to the PCS 13 is changed to “keep the voltage of the DC bus line 14 constant at 460 V”, and the charging control for the storage battery unit 31 is switched to CV charging control. The storage battery units 32, 33, 34, and 35 are switched to CC charge control.

  In FIG. 6, the charging process further proceeds from FIG. 5, and all the storage battery units 31, 32, 33, 34, and 35 are set to the charging voltage limit value (step-down output voltage limit value) defined by the characteristics of the storage battery pack (BP). It is a figure which shows control when it reaches | attains. Here, CV charge control is performed on all the storage battery units 31, 32, 33, 34, and 35.

  FIG. 7 is a diagram showing the control when the charging process further proceeds from FIG. 6 and one storage battery unit 31 reaches full charge. The storage battery unit charge / discharge state acquisition unit 42 acquires this state, and based on this, the charge / discharge start / stop command transmission unit 44 instructs the DC / DC converter 21 that controls the storage battery unit 31 to perform “charge stop”. (Operation stop command for the step-down unit 27) is transmitted. The CV charging control is continued for the other DC / DC converters 22, 23, 24, and 25.

  FIG. 8 is a diagram showing the control when the charging process is further advanced than in FIG. 7 and all the storage battery units 31, 32, 33, 34, and 35 have reached full charge. The “charge stop” command from the charge / discharge start / stop command transmission unit 44 is transmitted to all the DC / DC converters 21, 22, 23, 24, and 25, thereby completing the charging process. In this way, by controlling the DC bus line 14 to have a constant voltage value of 460 V, any of the storage battery units can be safely charged, and without any overcurrent or overvoltage, all the storage battery units 31, 32 can be charged. , 33, 34, 35 can be fully charged.

  FIGS. 9 to 11 are diagrams showing the situation at the time of discharge, FIG. 9 is when discharge is started, FIG. 10 is when one storage battery unit 31 is at the end of discharge, and FIG. 11 is all storage battery units 31 and 32. , 33, 34, and 35 are diagrams illustrating a situation when the discharge is terminated.

  As an example in which the discharge treatment is performed, in the daytime, the mechanical equipment of the external discharge load 12 is in a full operation state, and power is insufficient to supply the cooling device to the full operation state, and it is necessary to supply power of about 2 h at 250 kW. There shall be.

  FIG. 9 shows a state at the start of discharge, and the state acquired by the external state acquisition unit 41 is a state where the external discharge load 12 needs to be supplied with electric power of about 2 h at 250 kW as described above. The state acquired by the storage battery unit charge / discharge state acquisition unit 42 is within a range in which the SOCs of the five storage battery units 31, 32, 33, 34, and 35 can be discharged. “Dischargeable” means a state in which overdischarge does not occur even if discharge is performed. The command to the PCS 13 by the charge / discharge command transmission unit 43 is “discharge at 250 kW for 2 hours”. The commands to the five DC / DC converters 21, 22, 23, 24, and 25 by the charge / discharge start / stop command transmission unit 44 are "start discharge" (start operation of the boosting unit 26). In this case, the five DC / DC converters 21, 22, 23, 24, and 25 perform discharge control so that the voltage of the DC bus line 14 falls within the boost control voltage range.

  FIG. 10 is a diagram showing the control when the discharge process proceeds from FIG. 9 and one storage battery unit 31 is discharged. The storage battery unit charge / discharge state acquisition unit 42 acquires this state, and based on this, the charge / discharge start / stop command transmission unit 44 instructs the DC / DC converter 21 that controls the storage battery unit 31 to stop discharging. (Step-up command for boosting unit 26) is transmitted. The other DC / DC converters 22, 23, 24, 25 continue the discharge control for the storage battery units 32, 33, 34, 35.

  If it becomes like this, since it will discharge with the remaining four storage battery units 32, 33, 34, and 35, the electric energy which can be discharged will reduce to 4/5. Therefore, the command to the PCS 13 is changed to “Discharge the remaining time of 2 h at 200 kW”. Thus, since the discharge power amount of the discharge command is changed according to the number of storage battery units that can be discharged, the discharge current from the storage battery units 32, 33, 34, and 35 does not become excessive.

  FIG. 11 is a diagram illustrating the control when the discharge process further proceeds than in FIG. 10 and all the storage battery units 31, 32, 33, 34, and 35 are discharged. The “discharge stop” command from the charge / discharge start / stop command transmission unit 44 is transmitted to all the DC / DC converters 21, 22, 23, 24, and 25, thereby ending the discharge process. In this way, when there is a storage battery unit that has stopped discharging, the amount of discharge power for the PCS 13 is changed according to the number of remaining dischargeable storage battery units, so that the discharge current from any storage battery unit becomes excessive. In addition, the discharge can be safely terminated for all the storage battery units 31, 32, 33, 34, and 35.

  The charging control and discharging control have been described above. When charging / discharging is stopped when neither charging nor discharging is performed, for example, it may occur that power is immediately supplied to the external discharge load 12 such as an important facility due to a power failure or the like. Therefore, even when charging / discharging is stopped, the operating state of the PCS 13 is set to the standby state, and the operating states of the booster units 26 of the DC / DC converters 21, 22, 23, 24, and 25 are also set to the standby state. Electric power for setting the standby state can be supplied from the storage battery units 31, 32, 33, 34, and 35. Alternatively, it may be supplied from the DC bus line 14 side. Alternatively, an AC / DC converter may be connected to the external charging power supply 11 via a UPS, and power may be supplied from the AC / DC converter. Through the UPS, it is possible to supply power for continuously maintaining the standby state even during a power failure.

  For example, instead of the external status acquisition unit 41 that acquires the status of the external charging power source 11 and the external charging load 12, the control device 40 discharges at 250 kW from 2 pm to 4 pm, from 1 am to 4 am It is good also as what has a charging / discharging schedule setting part like charging. Thereby, the storage battery assembly control system 10 can be charged / discharged according to the set charge / discharge schedule.

  When one storage battery unit is subjected to CV charge control, the constant voltage charge command is transmitted to the PCS 13. However, the constant voltage charge command may be transmitted to the PCS 13 from the charge start state.

10 storage battery assembly control system, 11 external charging power source, 12 external discharge load,
13 PCS (power conversion device), 14 DC bus line, 21, 22, 23, 24, 25 DC / DC converter, 26 step-up unit, 27 step-down unit, 30 storage battery assembly, 31, 32, 33, 34, 35 storage battery Unit, 40 control device, 41 external condition acquisition unit, 42 storage battery unit charge / discharge state acquisition unit, 43 charge / discharge command transmission unit, 44 charge / discharge start / stop command transmission unit.

Claims (5)

A plurality of storage battery units with storage batteries;
A plurality of DC / DC converters connected to each storage battery unit;
A DC bus line connecting the plurality of storage battery units in parallel via the DC / DC converters;
A power converter connected between an external power line including an external charging power source and an external discharge load and the DC bus line; and
A control device;
With
The controller is
Obtaining the charge / discharge state of each storage battery unit,
Sending a charge / discharge command to the power converter,
A storage battery assembly control system for transmitting a charge / discharge start command or a charge / discharge stop command to each of the storage battery units. In the storage battery assembly control system according to claim 1,
The control device is a storage battery assembly control system that acquires at least one status of the external charging power source or the external discharging load. In the storage battery assembly control system according to claim 1 or 2,
The controller is
At the time of charging, as the charging command, a constant voltage charging command is transmitted to the power converter so that the voltage of the DC bus line becomes a predetermined constant voltage,
A storage battery assembly control system that transmits, as the discharge command, discharge power or a discharge power amount to the power conversion device during discharge. In the storage battery assembly control system according to claim 3,
During the charging,
Each of the DC / DC converters
When the charging start command is received from the control device, constant current charging is performed within a predetermined current limit range for the storage battery unit connected to the DC / DC converter,
The charging current is controlled so that the voltage of the storage battery unit becomes a predetermined charging voltage so that charging proceeds and the voltage of the storage battery unit does not increase too much,
The controller is
The storage battery assembly control system, wherein the constant voltage charging command having a voltage higher than an upper limit voltage value of a control voltage range of the DC / DC converter is transmitted to the power conversion device as the charging command. In the storage battery assembly control system according to claim 4,
The controller is
Among the plurality of storage battery units, for the storage battery unit that is fully charged, a storage battery assembly control system that transmits the charge stop command for the storage battery unit to the DC / DC converter connected to the storage battery unit.

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