Power storage system, and control program and control method thereof

Abstract

To provide a power storage system capable of charging a plurality of capacitors with high charging efficiency, and to provide a control program and a control method thereof.SOLUTION: The power storage system includes a plurality of power storage elements, power wiring to which a power source is connected, a plurality of power converters that perform power conversion between the power wiring and the corresponding power storage element, a state detector that detects a state of the plurality of power storage elements, and a controller. In a case where the plurality of power storage elements are charged by the power of the power supply, the controller acquires a power value of the power supply connected to the power wiring, selects, from among the plurality of power converters, some power converters of which the corresponding power storage elements satisfy a predetermined condition as power supply target power converters so that a total capacity of the power converters supplied with power from the power wiring among the plurality of power converters is equal to or less than an upper limit value determined according to the power value of the power supply, performs power supply to the power supply target power converters, and stops power supply to the remaining power converters.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a power storage system, a control program, and a control method thereof. [Background technology]

[0002] In a power storage system installed in an electric propulsion vessel, a power generation plant, or the like, when multiple power storage devices are connected to one power line, each of the multiple power storage devices may be connected to the power line via a corresponding power converter.

[0003] The following Patent Document 1 describes that when charging a plurality of such capacitors, charging is stopped in order from the capacitor whose charging voltage has reached a preset value. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4148468 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the method of Patent Document 1, the power supplied to each power converter during charging may not be appropriate for the capacity of the power converter. Therefore, there is room for improvement in Patent Document 1 to improve the charging efficiency for multiple capacitors.

[0006] The present disclosure has been made in view of the above, and has an object to provide a power storage system capable of charging a plurality of power storage devices with high charging efficiency, and a control program and control method thereof. [Means for solving the problem]

[0007] A power storage system according to one aspect of the present disclosure comprises a plurality of capacitors, a power wiring to which a power source for charging the plurality of capacitors is connected, a plurality of power converters connected to each of the plurality of capacitors and performing power conversion between the power wiring and the corresponding capacitors, a state detector that detects the state of the plurality of capacitors, and a controller. When charging the plurality of capacitors using power from the power source, the controller acquires the power value of the power source connected to the power wiring, and selects some of the plurality of power converters as power converters to be supplied with power, the state of the corresponding capacitors of which meets predetermined conditions, so that the total capacity of the power converters to which power is supplied from the power wiring is below an upper limit value determined according to the power value of the power source. The controller supplies power to the power converters to be supplied with power, and stops the supply of power to the remaining power converters.

[0008] A control program according to another aspect of the present disclosure is a control program for a power storage system including a plurality of electric storage devices, a power wiring to which a power source for charging the plurality of electric storage devices is connected, a plurality of power converters connected to each of the plurality of electric storage devices and performing power conversion between the power wiring and the corresponding electric storage device, a state detector for detecting the state of the plurality of electric storage devices, and a controller, wherein when the plurality of electric storage devices are to be charged using power from the power source, the control program causes the controller to acquire a power value of the power source connected to the power wiring, and selects some of the plurality of power converters whose corresponding states of the electric storage devices satisfy predetermined conditions as power converters to be supplied with power so that the total capacity of the power converters to be supplied with power from the power wiring is equal to or less than an upper limit value determined according to the power value of the power source, and causes the controller to supply power to the power converters to be supplied with power, and stops the supply of power to the remaining power converters.

[0009] A control method according to another aspect of the present disclosure is a control method for a power storage system including a plurality of electric storage devices, a power wiring to which a power source for charging the plurality of electric storage devices is connected, a plurality of power converters connected to each of the plurality of electric storage devices and performing power conversion between the power wiring and the corresponding electric storage device, a state detector for detecting the state of the plurality of electric storage devices, and a controller, wherein when the plurality of electric storage devices are charged using power from the power source, the power value of the power source connected to the power wiring is obtained, and some power converters from the plurality of power converters whose states of the corresponding electric storage devices satisfy predetermined conditions are selected as power converters to be supplied with power so that the total capacity of the power converters among the plurality of power converters to which power is supplied from the power wiring is below an upper limit value determined according to the power value of the power source, and power is supplied to the power converters to be supplied with power, and power supply to the remaining power converters is stopped. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to charge a plurality of capacitors with high charging efficiency. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a power storage system according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a flowchart showing an example of the flow of the charging process in this embodiment. [Figure 3] FIG. 3 is a diagram showing a charging state of a capacitor different from that shown in FIG. 1 in the power storage system shown in FIG. [Figure 4] FIG. 4 is a block diagram showing a schematic configuration of a power storage system according to a first modification of an embodiment of the present disclosure. [Figure 5] FIG. 5 is a block diagram showing a schematic configuration of a power storage system according to a second modification of an embodiment of the present disclosure. [Figure 6] FIG. 6 is a block diagram showing a schematic configuration of a power storage system according to a third modification of an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments will be described in detail with reference to the drawings. Note that, in the following, the same or corresponding elements will be designated by the same reference numerals throughout the drawings, and redundant description thereof will be omitted.

[0013] [Embodiment Mode] 1 is a block diagram showing a schematic configuration of a power storage system according to an embodiment of the present disclosure. Power storage system 1 in this embodiment includes multiple power storage devices 21, 22, 23, and 24. In this embodiment, an example is shown in which power storage system 1 includes four power storage devices 21, 22, 23, and 24.

[0014] The multiple electricity storage devices 21, 22, 23, and 24 include secondary batteries, capacitors, or the like. The multiple electricity storage devices 21, 22, 23, and 24 may differ from one another in terms of type, capacity, charging speed, and the like. In this embodiment, the multiple electricity storage devices 21, 22, 23, and 24 are capable of supplying electric power to motors that drive propulsion units of the electric propulsion vessel. That is, the electricity storage system 1 including the multiple electricity storage devices 21, 22, 23, and 24 is installed inside the vessel. In this embodiment, the propulsion units include a first propulsion unit 41 and a second propulsion unit 42.

[0015] For example, the first propulsion unit 41 and the second propulsion unit 42 are propulsion propellers. Therefore, the motors include a first motor 43 that drives the first propulsion unit 41 and a second motor 44 that drives the second propulsion unit 42. Note that the configuration of the propulsion system including the propulsion units and motors is not limited to this. For example, the propulsion system may be configured to drive one propulsion unit with two motors 43, 44.

[0016] The power storage system 1 includes a power wiring 3 to which a power source for charging the multiple power storage devices 21, 22, 23, and 24 is connected. The power wiring 3 includes an AC wiring 31 and a DC wiring 32. A first motor 43 and a second motor 44 are connected to the DC wiring 32 via power converters 45 and 46. The DC wiring 32 includes a first DC wiring 32a to which a power converter 45 connected to the first motor 43 is connected, and a second DC wiring 32b to which a power converter 46 connected to the second motor 44 is connected. The power converters 45 and 46 convert DC power supplied to the DC wiring 32 into AC power and supply it to the motors 43 and 44.

[0017] The AC wiring 31 includes a first AC wiring 31a connected to a first DC wiring 32a via a power converter 51, and a second AC wiring 31b connected to a second DC wiring 32b via a power converter 52. The first AC wiring 31a and the second AC wiring 31b are connected to each other via a circuit breaker 33. The power converters 51 and 52 convert AC power supplied to the AC wiring 31 into DC power and supply it to the DC wiring 32.

[0018] The power storage system 1 includes a plurality of power converters 61, 62, 63, and 64 that perform power conversion between the plurality of battery packs 21, 22, 23, and 24 and the power wiring 3. The plurality of power converters 61, 62, 63, and 64 are connected to the plurality of battery packs 21, 22, 23, and 24, respectively. The plurality of power converters 61, 62, 63, and 64 are connected to the power wiring 3. Of the plurality of power converters 61, 62, 63, and 64, two power converters 61 and 62 are connected to a first DC wiring 32a, and the remaining two power converters 63 and 64 are connected to a second DC wiring 32b. Hereinafter, the power converters 61 and 62 connected to the first DC wiring 32a may be referred to as first power converters, and the power converters 63 and 64 connected to the second DC wiring 32b may be referred to as second power converters.

[0019] As described above, in the present embodiment, the multiple battery packs 21, 22, 23, 24 include a first battery pack group 2a that mainly supplies power to the first motor 43 that drives the first propulsion unit 41, and a second battery pack group 2b that mainly supplies power to the second motor 44 that drives the second propulsion unit 42. The first battery pack group 2a includes the battery packs 21 and 22, and the second battery pack group 2b includes the battery packs 23 and 24. The power wiring 3 includes a first power wiring 3a for supplying power to the first battery pack group 2a and a second power wiring 3b for supplying power to the second battery pack group 2b. The first power wiring 3a includes a first AC wiring 31a and a first DC wiring 32a. The second power wiring 3b includes a second AC wiring 31b and a second DC wiring 32b.

[0020] A power source 8 for charging the multiple electricity storage devices 21, 22, 23, and 24 is connected to the AC wiring 31. In the present embodiment, the power source 8 is a power supply facility on land. The power source 8 is an AC power source. The power storage system 1 includes a power supply wiring 81 that connects a power cable 8a extending from an outboard power source 8 to the power wiring 3. More specifically, the power storage system 1 includes a connection terminal 82 that is connected to an end of the power supply wiring 81, and the power cable 8a is connected to the connection terminal 82. The power supply wiring 81 connects the connection terminal 82 to the AC wiring 31. In the example of FIG. 1 , the power supply wiring 81 is connected to the second AC wiring 31b, but instead of or in addition to this, the power supply wiring 81 may be connected to the first AC wiring 31a. A transformer 83 that transforms the voltage of the power supplied from the power source 8 is installed in the power supply wiring 81.

[0021] The power storage system 1 includes a controller 9. The controller 9 includes a processing circuit 91 that performs various types of signal processing. The processing circuit 91 includes a computer such as a microcontroller, a personal computer, or a PLC (Programmable Logic Controller). More specifically, the processing circuit 91 includes a processor, a memory, and peripheral circuits. The processor includes, for example, a CPU or an MPU. The memory includes, for example, a ROM, a RAM, a register, non-volatile storage, and the like. The peripheral circuits include an input / output interface, and the like. The controller 9 may be connected to an operation input device that performs predetermined input, a monitor that displays the control status, a speaker that outputs audio, and the like.

[0022] It should be noted that the functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, application-specific integrated circuits (ASICs), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuitry. In this specification, a circuit, unit, means, or module is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where hardware is a processor, which is considered a type of circuit, the circuit, unit, or means is a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0023] A control program for controlling the controlled objects is stored in the memory of the controller 9. The controller 9 controls the controlled objects based on the control program. As described above, various calculations executed by the controller 9 based on the control program are realized by the processing circuit 91. The controlled objects of the controller 9 include multiple power converters 61, 62, 63, and 64 connected to the battery storage devices 21, 22, 23, and 24. Furthermore, the controlled objects of the controller 9 may include other power converters 45, 46, 51, and 52 or motors 43 and 44, etc. The controller 9 may be configured as one controller that controls multiple controlled objects, or may be configured by two or more controllers.

[0024] In the electricity storage system 1 configured as described above, the power source 8 is connected to the connection terminal 82, thereby enabling charging of the plurality of electricity storage devices 21, 22, 23, and 24. The controller 9 starts the charging process after the power source 8 is connected to the connection terminal 82. The controller 9 selects the electricity storage device to be charged from the plurality of electricity storage devices 21, 22, 23, and 24.

[0025] For this purpose, the energy storage system 1 includes a state detector that detects the states of the plurality of battery packs 21, 22, 23, and 24. In this embodiment, the state detector includes a plurality of state detectors 101, 102, 103, and 104 corresponding to the plurality of battery packs 21, 22, 23, and 24. The battery states detected by the state detectors 101, 102, 103, and 104 include the charging rate, charging speed, normality, and the like. The charging rate is also referred to as SOC (State of Charge). For example, the charging speed can be obtained by measuring the current flowing through the battery packs 21, 22, 23, and 24 during charging. The normality is an index indicating the degree of deterioration or the normality of the battery packs 21, 22, 23, and 24. For example, the normality may be an index whose numerical value decreases as the deterioration progresses. Alternatively, for example, the normality may be a binary index that indicates that charging is not possible in a state where the battery pack is severely deteriorated or malfunctioning, and that charging is possible in other states. The states of the capacitors detected by the state detectors 101, 102, 103, and 104 are sent to the controller 9 as state signals D1, D2, D3, and D4.

[0026] Furthermore, a power detector 84 that measures the input power value supplied to the power wiring 3 is interposed in the power supply wiring 81 between the transformer 83 and the power wiring 3. The input power value detected by the power detector 84 is transmitted to the controller 9, which will be described later, as a power detection signal D5.

[0027] 2 is a flowchart showing an example of the flow of charging processing in this embodiment. The controller 9 receives status signals D1, D2, D3, and D4 and acquires the statuses of the plurality of capacitors 21, 22, 23, and 24 (step S1). The controller 9 determines whether each of the capacitors 21, 22, 23, and 24 satisfies a predetermined condition, and extracts the capacitors that satisfy the predetermined condition (step S2).

[0028] For example, the predetermined condition includes any one of the following: the charging rate is less than a predetermined upper limit charging rate, the charging speed is equal to or greater than a predetermined reference speed, and the normality indicator indicates that charging is possible. The normality indicator indicates that connection is impossible when, for example, the capacitors 21, 22, 23, 24 are in a state of poor connection, poor charging, or a state in which a predetermined error has occurred.

[0029] The controller 9 selects, from among the plurality of power converters 61, 62, 63, and 64, some power converters whose states of the power storage devices 21, 22, 23, and 24 satisfy predetermined conditions as selectable power converters.

[0030] The storage device of the controller 9 stores in advance the capacities of the multiple power converters 61, 62, 63, 64. The capacities of the power converters 61, 62, 63, 64 indicate the magnitude of the power supplied from the power line 3 to the corresponding battery, and are expressed in units of, for example, kW. For example, the capacities of the multiple power converters 61, 62, 63, 64 connected to the battery are set to be the same as or approximately the same as the capacities of the power converters 45, 46 that are connected to the DC line 32 to which the power converters 61, 62, 63, 64 are connected and that supply power to the motors 43, 44 that drive the propulsion units 41, 42. This is to efficiently supply power from the multiple battery storage units 21, 22, 23, 24 to the motors 43, 44 for the propulsion units 41, 42.

[0031] On the other hand, the value of the power supplied from the power source 8 to the power wiring 3 is not necessarily equal to or greater than the capacity of the multiple power storage devices 21, 22, 23, and 24. The capacity of the power cable 8a or the power wiring 81 connecting the power source 8 and the connection terminal 82 is determined based not only on the charging time for the power storage devices 21, 22, 23, and 24 but also on the cost of the equipment, ease of handling, space available on board, and the like. In particular, depending on the ship, sufficient charging is possible while the ship is at anchor, and therefore there may not be a strong demand for a short charging time for the power storage system 1 installed on the ship. Therefore, the capacity of the power cable 8a or the power wiring 81 may be smaller than the capacity of the multiple power converters 61, 62, 63, and 64 due to requirements other than the charging time.

[0032] For example, in the example of FIG. 1, the capacity of each of the four power converters 61, 62, 63, and 64 corresponding to the four battery storage devices 21, 22, 23, and 24 is X [kW], i.e., the total capacity of the four power converters 61, 62, 63, and 64 is 4X, and the capacity of the power supply wiring 81 is X / 2 [kW]. In this case, when the four power converters 61, 62, 63, and 64 are charged simultaneously, the power supplied to each power converter is X / 8 [kW]. In other words, only 1 / 8 of the power is supplied to each power converter 61, 62, 63, and 64 relative to its capacity. In the power converters 61, 62, 63, and 64, the closer the converted power is to the capacity of the power converters 61, 62, 63, and 64, i.e., the closer it is to the rated value, the better the power conversion efficiency.

[0033] In this way, if the capacitors 21, 22, 23, and 24 are charged with power that is small relative to the capacity of the power converters 61, 62, 63, and 64, the power conversion efficiency deteriorates and power loss due to heat generation increases. Furthermore, when all of the capacitors 21, 22, 23, and 24 are charged, even with a small amount of power, all of the corresponding power converters 61, 62, 63, and 64 generate heat, which also reduces the efficiency.

[0034] This problem becomes more pronounced as the number of batteries included in one battery storage system 1 increases. For example, if one battery storage system 1 includes 10 batteries, and the capacity of each of the 10 power converters connected to these batteries is X [kW], and the capacity of power supply wiring 81 is X / 2 [kW], then the power supplied to each battery when charging the 10 power converters simultaneously will be X / 20 [kW]. In this case, each power converter will be supplied with power that is significantly lower than its capacity, further reducing efficiency.

[0035] Therefore, the controller 9 selects some of the power converters 61, 62, 63, 64 whose states of the corresponding capacitors 21, 22, 23, 24 satisfy predetermined conditions as power converters to be supplied with power, so that the total capacity of the power converters 61, 62, 63, 64 to which power is supplied from the power wiring 3 is equal to or less than an upper limit value determined according to the power value of the power source 8 (step S3).

[0036] In this case, the controller 9 acquires the power value of the power source 8 connected to the power line 3. The power value of the power source 8 may be stored in advance in a memory of the controller 9, or may be input by a user using an operation input device connected to the controller 9. Alternatively, the input power value measured by the power detector 84 may be acquired as the power value of the power source 8. Alternatively, a database relating to combinations of the locations of power supply equipment and the power values ​​of the power supply equipment may be stored in an external storage device, and the controller 9 may access the external storage device via a predetermined communication network and query the database to acquire the power value of the power supply equipment that will be the power source 8.

[0037] The controller 9 reads out the capacities of one or more selectable power converters determined based on the state determination result, and selects a power converter to be supplied with power from the selectable power converters so that the sum of the capacities of the selected power converters is equal to or less than an upper limit value determined according to the acquired power value of the power source 8 and is the combination closest to the power value of the power source 8.

[0038] When there are multiple combinations, the controller 9 can select a combination including a power converter with a higher priority from the multiple combinations according to the priorities set for the power converters. The priorities may be set in advance for the multiple power converters 61, 62, 63, 64, or may be determined based on the states of the corresponding battery devices 21, 22, 23, 24. For example, the controller 9 may set a higher priority for a power converter corresponding to a battery with a lower charging rate, or may set a higher priority for a power converter corresponding to a battery with a slower charging rate.

[0039] In this embodiment, the upper limit of the total capacity of the power converters to be supplied with power is set so that the power supplied to each of the power converters to be supplied with power is equal to or greater than a lower limit determined based on the capacity of each power converter. In this embodiment, the lower limit is set to X / 4. In this case, when the power of power source 8 is X / 2 [kW], controller 9 determines that the number of power converters to be supplied with power is two or less out of four power converters 61, 62, 63, and 64, each with a capacity of X [kW]. In other words, the upper limit of the total capacity of the power converters to be supplied with power is set to 2X [kW].

[0040] Furthermore, controller 9 selects the first power converters and second power converters to be supplied with power so that the difference between the total capacity of the first power converters supplied with power from first power wiring 3a and the total capacity of the second power converters supplied with power from second power wiring 3b falls within a predetermined range. In this embodiment, the four power converters 61, 62, 63, and 64 have the same capacity, so the predetermined range can be set to a range based on 0.

[0041] 1, all of the battery storage devices 21, 22, 23, and 24 are determined as selectable power converters, and among them, the power converters 61 and 63 corresponding to the battery storage devices 21 and 23 are selected as power converters to be supplied with power. The controller 9 supplies power to the power converters 61 and 63 to be supplied with power, and stops the power supply to the remaining power converters 62 and 64 (step S4).

[0042] In this embodiment, the controller 9 transmits, as control signals C1 and C3, operation execution signals ON to the power converters 61 and 63 to be supplied with power, for executing power conversion operations in the power converters 61 and 63. As a result, the power converters 61 and 63 to be supplied with power execute power conversion operations, and power is supplied to the power converters 61 and 63 to be supplied with power. For example, the power converters 61, 62, 63, and 64 each include a plurality of switching elements. In this case, the operation execution signals ON are switching control signals that switch on or off each switching element in the corresponding power converter.

[0043] Meanwhile, the controller 9 transmits, as control signals C2 and C4, operation stop signals OFF to the remaining power converters 62 and 64 to prevent the power converters 62 and 64 from performing power conversion operations. This stops the power conversion operations of the power converters 62 and 64 other than the power supply target, and power supply to the power converters 62 and 64 other than the power supply target is stopped. Note that instead of transmitting operation stop signals as control signals C2 and C4, the controller 9 may not transmit the control signals C2 and C4.

[0044] As a result, power is supplied from the first power wiring 3a to power converter 61 functioning as the first power converter, and the corresponding battery 21 is charged. Also, power is supplied from the second power wiring 3b to power converter 63 functioning as the second power converter, and the corresponding battery 23 is charged. At this time, the total capacity of power converters 61 and 63 supplied with power from power wiring 3 is 2X [kW], and the power supplied from power source 8 to each power converter 61 and 63 is X / 4 [kW]. Also, the difference between the total capacity of the first power converters and the total capacity of the second power converters is zero.

[0045] The controller 9 monitors the charge rates of the capacitors 21, 23 corresponding to the power converters 61, 63 supplied with power from the power line 3 (step S5). When the charge rates of these capacitors 21, 23 reach or exceed a predetermined value (Yes in step S5), the controller 9 determines whether or not there is a capacitor that can be charged, i.e., that satisfies a predetermined condition and has not yet been charged (step S6).

[0046] If there is a chargeable but not charging battery (Yes in step S6), the controller 9 stops the power supply to the power converter connected to the battery whose charging rate is equal to or greater than a predetermined value, and switches the battery to be charged by supplying power to the power converter with the highest priority among the power converters 62, 64 that were not selected as the power converter to be supplied with power (step S7). If there is no chargeable but not charging battery (No in step S6), the controller 9 stops the power supply to the power converter connected to the battery whose charging rate is equal to or greater than a predetermined value, and ends the charging process. If one power storage system 1 includes a large number of battery devices, the battery to be charged may be switched multiple times. The predetermined value of the charging rate may be set, for example, to an upper limit charging rate that is set as a predetermined condition for the battery.

[0047] For example, when priorities are set for the power converters according to the power receiving rates of the power storage devices, the controller 9 selects the power converter with the lowest charging rate of the corresponding power storage device as the new power supply target.

[0048] Fig. 3 is a diagram showing the charging state of a capacitor different from that shown in Fig. 1 in the power storage system shown in Fig. 1. In this embodiment, when the charging rate of capacitor 21 is equal to or higher than a predetermined value, controller 9 switches control signals C1 and C2 to terminate charging of capacitor 21 and start charging of capacitor 22. Furthermore, when the charging rate of capacitor 23 is equal to or higher than a predetermined value, controller 9 switches control signals C3 and C4 to terminate charging of capacitor 23 and start charging of capacitor 24.

[0049] According to the above configuration, some power converters whose states of corresponding capacitors 21, 22, 23, 24 satisfy predetermined conditions are selected from the plurality of power converters 61, 62, 63, 64 so that the total capacity of the power converters among the plurality of power converters 61, 62, 63, 64 to which power is supplied from power wiring 3 is equal to or less than an upper limit value determined according to the power value of power source 8. When the selected power converters are supplied with power from power wiring 3, some of the capacitors among the plurality of capacitors 21, 22, 23, 24 that are connected to the selected power converters are charged.

[0050] Therefore, even if the capacity of the power cable 8a or power wiring 81 between the power source 8 and the power wiring 3 is smaller than the capacity of the multiple power converters 61, 62, 63, 64, the power supplied to each power converter can be made larger than when the power is supplied simultaneously to all of the power converters 61, 62, 63, 64. In the above example, the power supplied from the power source 8 to each power converter is doubled compared to when the power is supplied simultaneously to all of the power converters 61, 62, 63, 64.

[0051] This makes it possible to increase the power conversion efficiency of the power supplied to the power converter when charging the capacitors. Higher power conversion efficiency also reduces the proportion of power loss due to heat generation in the power converter. Furthermore, by reducing the number of capacitors to be charged simultaneously, the number of power converters performing power conversion simultaneously can be reduced, and overall power loss due to heat generation in the power converters can also be reduced. As described above, according to this embodiment, multiple capacitors 21, 22, 23, and 24 can be charged with high charging efficiency.

[0052] Furthermore, according to the present embodiment, the upper limit of the total capacity of the power converters to be supplied with power is set so that the power supplied to each of the power converters to be supplied with power is equal to or greater than a lower limit determined based on the capacity of each power converter. This makes it possible to set an upper limit based on the capacity of each power converter, and to charge the plurality of electricity storage devices 21, 22, 23, and 24 with high charging efficiency.

[0053] Furthermore, according to the present embodiment, the power converters to be supplied with power are selected so as to reduce the difference in capacity between the power converters supplied with power between the power wirings 3a, 3b of the two systems of the propulsion units 41, 42. As a result, even if charging must be suddenly stopped and operation of the power capacitors 21, 22, 23, 24 must be started, for example, when the ship on which the power capacitors 21, 22, 23, 24 are installed must urgently depart port, the charging rates of the power capacitors belonging to the respective systems of the propulsion units 41, 42 can be balanced, allowing for stable operation.

[0054] Furthermore, according to this embodiment, when the charging rate of a battery being charged reaches or exceeds a predetermined value, the power converter to which power is supplied is switched so as to charge a battery that has not yet been charged. This makes it possible to prevent the charging time required to charge all of the chargeable battery 21, 22, 23, 24 from becoming longer.

[0055] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various improvements, changes, and modifications are possible within the scope of the spirit of the present disclosure.

[0056] [Other embodiments] For example, in the above embodiment, an example is shown in which the power storage system 1 includes four power storage devices 21, 22, 23, and 24, but the number of power storage devices may be two or three, or may be five or more. In the present disclosure, the number of power storage devices is defined as a number equal to the number of power converters connected to the power line 3. In other words, a power storage device connected to one power converter is counted as one, regardless of the number of units included therein.

[0057] Furthermore, in the above embodiment, onshore power supply equipment has been described as the power supply 8 for charging the electricity storage devices 21, 22, 23, and 24, but this is not limiting. For example, the power supply 8 may be a power supply arranged onboard the ship. In the above embodiment, the electricity storage system 1 includes generators 111 and 112 that generate electricity based on the rotational power of the propulsion devices 41 and 42. These generators 111 and 112 may be used as the power supply 8 for charging the electricity storage devices 21, 22, 23, and 24. The electricity storage system 1 also includes power detectors 121 and 122 that measure the power generated by the generators 111 and 112. When the generators 111 and 112 are used as the power supply 8, the controller 9 acquires the power value detected by the power detectors 121 and 122 as the power value of the power supply 8. Furthermore, for example, an onboard power supply such as a fuel cell may be connected to the power line 3 as the power supply 8 when the electricity storage devices 21, 22, 23, and 24 are being charged.

[0058] Furthermore, power cables 8a with different capacities in the power source 8 may be connected to the connection terminal 82 that connects the external power source 8. For example, in the power storage system 1 mounted on a ship, the output power of the power source 8 or the capacity of the power cable 8a may differ depending on the port of call of the ship.

[0059] In addition, in the above embodiment, an example has been shown in which the power value of the power source 8 is entirely used as charging power for the storage batteries 21, 22, 23, and 24, but when the power source 8 is connected to the power wiring 3, the power source 8 may also be used as a power source for power loads such as onboard equipment connected to the power wiring 3.

[0060] Fig. 4 is a block diagram showing a schematic configuration of a power storage system according to a first modification of an embodiment of the present disclosure. In Fig. 4, the same components as those in Fig. 1 are denoted by the same reference numerals, and description thereof will be omitted. The power storage system 1B shown in Fig. 4 has the same configuration as the power storage system 1 shown in Fig. 1, except that a power load 141 is connected to the AC wiring 31.

[0061] When charging the battery devices 21, 22, 23, and 24, if the power load 141 is connected to the power line 3, the charging power for charging the battery devices 21, 22, 23, and 24 is a value obtained by subtracting the value of the load power consumption supplied to the power load 141 from the power value of the power source 8. In this case, the controller 9 may acquire the power value of the power source 8 and the value of the load power consumption, and calculate the value of the charging power from these values. For this purpose, the power storage system 1B includes a load power consumption detector 142 that detects the value of the load power consumption supplied from the power source 8 to the power load 141 connected to the power line 3. The load power consumption detector 142 transmits a load detection signal D6 including the value of the load power consumption to the controller 9.

[0062] The controller 9 may select the power converter to be supplied with power so that the total capacity of the power converters connected to the power line 3 is equal to or less than an upper limit value corresponding to the calculated value of the charging power. According to this, when power is supplied to the power load 141 while charging the battery packs 21, 22, 23, and 24, even if the value of the charging power changes in accordance with the load power consumption, which changes from time to time, the battery packs 21, 22, 23, and 24 can be charged with high charging efficiency corresponding to the value of the charging power. Note that, while the example in FIG. 4 shows an example in which the power load 141 is connected to the first AC line 31a, in addition to or instead of this, the power load 141 may be connected to the second AC line 31b or the DC line 32.

[0063] Furthermore, in the above embodiment, the power converters 61, 62, 63, and 64 have the same capacity, but they may have different capacities.

[0064] In addition, in the above embodiment, an example was shown in which the power wiring 3 was divided into two systems, the first power wiring 3a and the second power wiring 3b, but the power wiring 3 may be a single system or may include three or more systems.

[0065] In addition, in the above embodiment, an example was given of a case where the power wiring 3 is divided into two systems, the first power wiring 3a and the second power wiring 3b, and at least one capacitor belonging to each system is charged, but instead, one of the systems may be selected and controlled to charge at least one capacitor belonging to that system.

[0066] Furthermore, in the above embodiment, an example has been shown in which the power wiring 3 includes the AC wiring 31 and the DC wiring 32, but it may include only either the AC wiring 31 or the DC wiring 32. Fig. 5 is a block diagram showing a schematic configuration of a power storage system according to a second modification of an embodiment of the present disclosure. In Fig. 5, the same components as those in Fig. 1 are denoted by the same reference numerals, and description thereof will be omitted.

[0067] 5, the power wiring 3 includes a first DC wiring 32a which is the first power wiring, and a second DC wiring 32b which is the second power wiring. A power converter 130 which converts AC power supplied from the power source 8 into DC power is interposed in the power supply wiring 81. This converts the AC power from the power source 8 into DC current and supplies it to the power wiring 3 which is the DC wiring. Similarly, generators 111 and 112 are also connected to the power wiring 3 via power converters 131 and 132.

[0068] In this way, the same charging process as in the above embodiment can be applied even when a power supply system is directly connected to the power wiring 3, which is a DC wiring to which the power converters 61, 62, 63, 64 to which the electricity storage devices 21, 22, 23, 24 are connected. Note that AC wiring may be connected to the first DC wiring 32a and the second DC wiring 32b via power converters.

[0069] Furthermore, in the above embodiment, an example has been given of a mode in which the power converter supplied with power from the power line 3 is switched so as to charge a not-yet-charged battery as needed when the charging rate of the battery being charged reaches or exceeds a predetermined value, but this is not limiting. For example, the controller 9 may divide the power converters that satisfy a predetermined condition into a plurality of groups in which the total capacity of the power converters in each group is equal to or less than an upper limit value determined according to the power value of the power source 8, and perform control to switch the power converter to be supplied with power for each group so that power is supplied from the power line 3 to the plurality of groups in a predetermined order.

[0070] For example, in the energy storage system 1 of FIG. 1 , if power converters 61 and 63 are grouped as a first group and power converters 62 and 64 are grouped as a second group, even if the state of charge of one of the energy storage devices 21 corresponding to the power converters 61 and 63 in the first group reaches or exceeds a predetermined value, it is not necessary to connect the power converter 62 of the second group to the power wiring 3 instead of the power converter 61. However, even in this case, the power supply to the power converter 61 corresponding to the energy storage device 21 whose state of charge has reached or exceeds the predetermined value is stopped. Thereafter, when the state of charge of the remaining energy storage devices 23 in the first group reaches or exceeds the predetermined value, the power converters 62 and 64 of the second group are simultaneously supplied with power from the power wiring 3. Even in this control mode, the plurality of energy storage devices 21, 22, 23, and 24 can be charged with high charging efficiency.

[0071] In addition, in the above embodiment, the power conversion operation of the power converters 61, 62, 63, and 64 is controlled to start or stop the supply of power to each of the power converters 61, 62, 63, and 64, but this is not limiting. Fig. 6 is a block diagram showing a schematic configuration of a power storage system according to a third modification of an embodiment of the present disclosure. In Fig. 6, the same components as those in Fig. 1 are assigned the same reference numerals, and description thereof will be omitted.

[0072] 6 includes a plurality of switches 71, 72, 73, and 74 corresponding to a plurality of power converters 61, 62, 63, and 64. A power wiring 3 is connected to each of the plurality of switches 71, 72, 73, and 74. The plurality of switches 71, 72, 73, and 74 switch between connecting and disconnecting the corresponding power converters 61, 62, 63, and 64 to and from the power wiring 3. For example, the plurality of switches 71, 72, 73, and 74 include contactors that open and close electrical paths using electromagnetic force.

[0073] Of the multiple power converters 61, 62, 63, 64, two power converters 61, 62 are connected to the first DC wiring 32a via corresponding switches 71, 72, and the remaining two power converters 63, 64 are connected to the second DC wiring 32b via corresponding switches 73, 74.

[0074] In this case, the controller 9 controls the multiple switches 71, 72, 73, and 74 to connect the power converters to be supplied with power to the power line 3 and to disconnect the remaining power converters from the power line 3. For example, if the power converters 61 and 63 are the power converters to be supplied with power, the controller 9 sends control signals C1 and C3 to the switches 71 and 73 to close the switches 71 and 73, and sends control signals C2 and C4 to the switches 72 and 74 to open the switches 72 and 74, as shown in Fig. 6. Similarly, if the power converters 62 and 64 are the power converters to be supplied with power, the controller 9 sends control signals C2 and C4 to the switches 72 and 74 to close the switches 72 and 74, and sends control signals C1 and C3 to the switches 71 and 73 to open the switches 71 and 73.

[0075] Even in this configuration, even if the capacity of power cable 8a or power wiring 81 between power source 8 and power wiring 3 is smaller than the capacity of multiple power converters 61, 62, 63, 64, the power supplied to each power converter can be made larger than when power is supplied simultaneously to all power converters 61, 62, 63, 64. This allows multiple electricity storage devices 21, 22, 23, 24 to be charged with high charging efficiency.

[0076] It should be noted that a plurality of switches may be disposed between the plurality of power converters 61, 62, 63, 64 and the corresponding battery cells 21, 22, 23, 24. In this case, the controller 9 may control the plurality of switches to connect the power converters to be supplied with power to the power line 3 and disconnect the remaining power converters from the power line 3.

[0077] In addition, in the above embodiment, the power storage system 1 is mounted on a ship, but this is not limiting. For example, the power storage system 1 of the present disclosure may be applied to moving bodies other than ships, such as vehicles and aircraft, or may be applied to fixed facilities such as various plants.

[0078] The control program in the above embodiment may be configured as a program product that is provided by downloading from an external computer or recorded on a non-transitory recording medium that is readable by a computer, or may be configured as a computer product in which the control program is pre-installed.

[0079] Summary of this disclosure [Item 1] A power storage system according to one aspect of the present disclosure comprises a plurality of capacitors, a power wiring to which a power source for charging the plurality of capacitors is connected, a plurality of power converters connected to each of the plurality of capacitors and performing power conversion between the power wiring and the corresponding capacitors, a state detector that detects the state of the plurality of capacitors, and a controller. When charging the plurality of capacitors using power from the power source, the controller acquires the power value of the power source connected to the power wiring, and selects some of the plurality of power converters as power converters to be supplied with power, the state of the corresponding capacitors of which meets predetermined conditions, so that the total capacity of the power converters to which power is supplied from the power wiring is below an upper limit value determined according to the power value of the power source. The controller supplies power to the power converters to be supplied with power, and stops the supply of power to the remaining power converters.

[0080] According to the above configuration, some of the power converters whose states of corresponding capacitors satisfy a predetermined condition are selected from the plurality of power converters so that the total capacity of the power converters to which power is supplied from the power wiring is equal to or less than an upper limit value determined according to the power value of the power source. When the selected power converters are supplied with power from the power wiring, some of the plurality of capacitors connected to the selected power converters are charged.

[0081] Therefore, the power supplied to each power converter can be made larger than when it is supplied to all power converters simultaneously. This makes it possible to increase the power conversion efficiency of the power supplied to the power converter when charging the storage battery. Higher power conversion efficiency also reduces the proportion of power loss due to heat generation in the power converter. Furthermore, by reducing the number of storage batteries that are charged simultaneously, the number of power converters that perform power conversion simultaneously can be reduced, and overall power loss due to heat generation in the power converters can also be reduced. As a result, multiple storage batteries can be charged with high charging efficiency.

[0082] [Item 2] In the power storage system of item 1, the upper limit value may be set so that the power supplied to each of the power converters to be supplied with power connected to the power line is equal to or greater than a lower limit value determined based on the capacity of each power converter. This makes it possible to set an upper limit value based on the capacity of each power converter, and to charge multiple power storage devices with high charging efficiency.

[0083] [Item 3] In the energy storage system of item 1, the controller may supply power to the power converter to be supplied with power by causing the power converter to perform a power conversion operation in the power converter, and may stop the supply of power to the remaining power converters by not causing the remaining power converters to perform a power conversion operation in the power converter.

[0084] [Item 4] The energy storage system of item 1 may include a plurality of switches that switch between connecting or disconnecting each of the plurality of power converters to or from the power wiring, and the controller may control the plurality of switches to connect the power converter to be supplied with power to the power wiring and disconnect the remaining power converters from the power wiring.

[0085] [Item 5] Any of the energy storage systems of items 1 to 4 may include a power supply wiring that connects the power source and the power wiring, the plurality of energy storage devices may be installed on a ship, and the power source may be an onshore power supply facility connected to the power supply wiring.

[0086] [Item 6] The power storage system of any one of items 1 to 5 may include a power supply wiring that connects the power supply and the power wiring, and the capacity of the power supply wiring may be smaller than the capacity of the plurality of power converters.

[0087] [Item 7] In the power storage system of any one of items 1 to 6, the multiple power storage devices may be installed in a vessel, the power wiring may include a first power wiring connected to a first motor that electrically drives a first propulsion unit and a second power wiring connected to a second motor that electrically drives a second propulsion unit, the multiple power converters may include two or more first power converters connected to the first power wiring and two or more second power converters connected to the second power wiring, and the controller may select the first power converters and the second power converters to be supplied with power so that a difference between the total capacity of the first power converters supplied with power from the first power wiring and the total capacity of the second power converters supplied with power from the second power wiring is within a predetermined range. In this case, the power converters to be supplied with power are selected so that the difference in capacity of the power converters supplied with power between the power wirings of the two propulsion units is small. This means that even if charging must be stopped suddenly and the storage devices must be put into operation, for example, when a ship on which the storage devices are installed must urgently depart port, the charging rates of the storage devices belonging to each system of the propulsion unit can be balanced, allowing for stable operation.

[0088] [Item 8] In the power storage system of any one of items 1 to 7, the state detector may detect the charge rates of each of the plurality of power storage devices as the state of the plurality of power storage devices, and the controller may preferentially select a power converter connected to a power storage device with a lower charge rate among the plurality of power storage devices as the power storage device to be supplied with power, and when the charge rate of a corresponding power storage device among the power storage devices to be supplied with power reaches or exceeds a predetermined value, stop power supply to the power converter corresponding to the corresponding power storage device, and execute power supply to a power converter that is not selected as the power storage device to be supplied with power and is associated with the power storage device with the lowest charge rate among the power storage devices. This makes it possible to prevent the charging time required to charge all of the chargeable power storage devices from becoming long.

[0089] [Item 9] The power storage system of any one of items 1 to 8 may include a load power consumption detector that detects a value of load power consumption supplied from the power source to a power load connected to the power line, and the controller may calculate a value of charging power by subtracting the value of the load power consumption from the power source power value, and may select some power converters from the plurality of power converters, whose corresponding states of the battery satisfy predetermined conditions, as power converters to be supplied with power, so that a total capacity of the power converters supplied with power from the power line among the plurality of power converters is equal to or less than an upper limit value determined according to the value of the charging power. According to this, when power is supplied to the power load while charging the battery, even if the value of the charging power changes in accordance with the load power consumption that changes each time, the battery can be charged with high charging efficiency according to the value of the charging power.

[0090] [Item 10] A control program according to another aspect of the present disclosure is a control program for a power storage system including a plurality of electric storage devices, a power wiring to which a power source for charging the plurality of electric storage devices is connected, a plurality of power converters connected to each of the plurality of electric storage devices and performing power conversion between the power wiring and the corresponding electric storage device, a state detector for detecting the state of the plurality of electric storage devices, and a controller, wherein when the plurality of electric storage devices are to be charged using power from the power source, the control program causes the controller to acquire a power value of the power source connected to the power wiring, and selects some of the plurality of power converters whose corresponding states of the electric storage devices satisfy predetermined conditions as power converters to be supplied with power so that the total capacity of the power converters to be supplied with power from the power wiring is equal to or less than an upper limit value determined according to the power value of the power source, and causes the controller to supply power to the power converters to be supplied with power, and stops the supply of power to the remaining power converters.

[0091] [Item 11] A control method according to another aspect of the present disclosure is a control method for a power storage system including a plurality of electric storage devices, a power wiring to which a power source for charging the plurality of electric storage devices is connected, a plurality of power converters connected to each of the plurality of electric storage devices and performing power conversion between the power wiring and the corresponding electric storage device, a state detector for detecting the state of the plurality of electric storage devices, and a controller, wherein when the plurality of electric storage devices are charged using power from the power source, the power value of the power source connected to the power wiring is obtained, and some power converters from the plurality of power converters whose states of the corresponding electric storage devices satisfy predetermined conditions are selected as power converters to be supplied with power so that the total capacity of the power converters among the plurality of power converters to which power is supplied from the power wiring is below an upper limit value determined according to the power value of the power source, and power is supplied to the power converters to be supplied with power, and power supply to the remaining power converters is stopped. [Explanation of symbols]

[0092] 1, 1B, 1C, 1D Energy Storage System 3 Power wiring 3a 1st power wiring 3b 2nd power wiring 8 Power 9 Controller 21, 22, 22, 24 Capacitor 41 1st propulsion machine 42 2nd propulsion machine 43 First motor 44 Second motor 61, 62, 63, 64 Power converter connected to the capacitor 71, 72, 73, 74 Switches 81 Power wiring 101,102,103,104 State detector 141 Power load 142 Load Power Consumption Detector

Claims

1. A plurality of capacitors; power wiring to which a power source for charging the plurality of capacitors is connected; a plurality of power converters connected to the plurality of electric storage devices, respectively, for converting power between the power lines and the corresponding electric storage devices; a state detector for detecting a state of the plurality of capacitors; a controller; When charging the plurality of capacitors with the power of the power source, the controller acquiring a power value of the power source connected to the power line; a power storage system which selects some power converters from the plurality of power converters as power converters to be supplied with power, the power converters having states of their corresponding capacitors satisfying predetermined conditions, so that a total capacity of the power converters to be supplied with power from the power wiring among the plurality of power converters is equal to or less than an upper limit value determined in accordance with the power value of the power source, and supplies power to the power converters to be supplied with power, and stops the power supply to the remaining power converters.

2. 2. The power storage system according to claim 1, wherein the upper limit value is set so that the power supplied to each of the power converters to be supplied with power is equal to or greater than a lower limit value determined based on a capacity of each power converter.

3. The controller causing the power converter to perform a power conversion operation, thereby supplying power to the power converter; The power storage system according to claim 1 , wherein the power supply to the remaining power converter is stopped by causing the remaining power converter not to perform a power conversion operation thereof.

4. a plurality of switches for switching between connection and disconnection between each of the plurality of power converters and the power wiring; The power storage system according to claim 1 , wherein the controller controls the plurality of switches to connect the power converter to be supplied with power to the power line and to disconnect the remaining power converters from the power line.

5. a power supply wiring that connects the power supply and the power wiring; the plurality of capacitors are installed in a ship, The power storage system according to claim 1 , wherein the power source is a land-based power supply facility connected to the power supply wiring.

6. a power supply wiring that connects the power supply and the power wiring; The power storage system according to claim 1 , wherein a capacity of the power supply wiring is smaller than a capacity of the plurality of power converters.

7. the plurality of capacitors are installed in a ship, the power wiring includes a first power wiring connected to a first motor that electrically drives a first propulsion unit, and a second power wiring connected to a second motor that electrically drives a second propulsion unit, the plurality of power converters include two or more first power converters connected to the first power wiring and two or more second power converters connected to the second power wiring; The controller 5. The energy storage system according to claim 1, wherein the first power converter and the second power converter to be supplied with power are selected so that a difference between a total capacity of the first power converters supplied with power from the first power wiring and a total capacity of the second power converters supplied with power from the second power wiring falls within a predetermined range.

8. the state detector detects the charge rate of each of the plurality of capacitors as the state of the plurality of capacitors; The controller a power converter connected to a battery with a lower charging rate among the plurality of battery accumulators is preferentially selected as the power converter to be supplied with power; 5. The power storage system according to claim 1, wherein, when a charging rate of a corresponding battery among the power converters to be supplied with power reaches or exceeds a predetermined value, power supply to the power converter corresponding to the battery is stopped, and power is supplied to a power converter that has a corresponding battery with the lowest charging rate among the power converters that have not been selected as the power converters to be supplied with power.

9. a load power consumption detector that detects a value of load power consumption supplied from the power supply to a power load connected to the power wiring; The controller calculating a charging power value by subtracting the load power consumption value from the power value of the power source; 5. The power storage system according to claim 1, wherein some power converters whose states of the corresponding capacitors satisfy predetermined conditions are selected as power converters to be supplied with power, from among the plurality of power converters, so that a total capacity of the power converters to which power is supplied from the power wiring is equal to or less than an upper limit value determined according to the value of the charging power.

10. A plurality of capacitors; power wiring to which a power source for charging the plurality of capacitors is connected; a plurality of power converters connected to the plurality of electric storage devices, respectively, for converting power between the power lines and the corresponding electric storage devices; a state detector for detecting a state of the plurality of capacitors; A control program in a power storage system including a controller, When the plurality of capacitors are charged with the power of the power source, the control program causes the controller to acquiring a power value of the power source connected to the power line; a control program that selects some power converters from the plurality of power converters as power converters to be supplied with power, the states of the corresponding capacitors of which satisfy predetermined conditions, so that the total capacity of the power converters to which power is supplied from the power wiring among the plurality of power converters is equal to or less than an upper limit value determined in accordance with the power value of the power source, and executes power supply to the power converters to be supplied with power, and stops power supply to the remaining power converters.

11. A plurality of capacitors; power wiring to which a power source for charging the plurality of capacitors is connected; a plurality of power converters connected to the plurality of electric storage devices, respectively, for converting power between the power lines and the corresponding electric storage devices; a state detector for detecting a state of the plurality of capacitors; A control method for a power storage system including a controller, When the plurality of capacitors are charged with the power of the power source, acquiring a power value of the power source connected to the power line; a control method for selecting, from the plurality of power converters, some power converters whose states of the corresponding capacitors satisfy predetermined conditions as power converters to be supplied with power, so that the total capacity of the power converters to which power is supplied from the power wiring is equal to or less than an upper limit value determined according to the power value of the power source; supplying power to the power converters to be supplied with power, and stopping the supply of power to the remaining power converters.

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