Energy storage system and control device

Abstract

Provided is an electricity storage system comprising: a plurality of power storage devices capable of discharging and charging direct current power; a plurality of power conversion devices that convert the direct current power stored in the plurality of power storage devices into power corresponding to the load, supplies power to the load on the basis of the direct current power stored in the plurality of power storage devices, converts the power of the load into direct current power corresponding to the plurality of power storage devices, and charges the plurality of power storage devices on the basis of the power on the load side; and a control device that controls power conversion operations of the plurality of power conversion devices, wherein the control device includes a conversion device determining unit that determines the power conversion device to which the operation command is to be transmitted, among the plurality of power conversion devices, and the conversion device determining unit determines the number of power conversion devices to which the operation command is to be transmitted, on the basis of information regarding states of the plurality of power storage devices and the plurality of power conversion devices. This provides an electricity storage system and a control device capable of suppressing power loss.

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a power storage system and a control device. [Background technology]

[0002] A known energy storage system includes a plurality of energy storage devices, a plurality of power conversion devices, and a control device. The plurality of power conversion devices are provided corresponding to each of the plurality of energy storage devices. Each power conversion device is connected to a respective energy storage device and also to a common load. Each power conversion device supplies power to the load based on the power stored in the respective energy storage device, and charges each energy storage device based on the power on the load side. The control device controls the power conversion operations of the plurality of power conversion devices.

[0003] Such a power storage system is used, for example, to suppress fluctuations in the frequency of a power grid. Each power conversion device is connected to the power grid using the power grid as a voltage source, and supplies power to the power grid and charges each power storage device with power from the power grid so as to suppress frequency fluctuations in the power grid. The power storage system is also used in electric vehicles such as electric locomotives and electric automobiles. Each power conversion device is connected to the motor of the electric vehicle as a load, supplies power to the motor, and charges each power storage device with regenerative energy from the motor.

[0004] The control device determines the output of each of the multiple power conversion devices based on the power required by the load, and operates each of the multiple power conversion devices based on the determined output. However, a control method that operates all of the multiple power conversion devices regardless of the amount of power required by the load results in large power loss due to the operation of the multiple power conversion devices. For this reason, it is desirable for the power storage system and the control device used therein to be able to suppress power loss. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3890168 [Patent Document 2] Patent No. 5924524 Summary of the Invention [Problem to be solved by the invention]

[0006] An embodiment of the present invention provides a power storage system and a control device that can suppress power loss. [Means for solving the problem]

[0007] According to an embodiment of the present invention, a power conversion system includes a plurality of power storage devices capable of discharging and charging DC power, a plurality of power conversion devices connected to the plurality of power storage devices and a load, the plurality of power conversion devices converting the DC power stored in the plurality of power storage devices into power corresponding to the load, supplying power to the load based on the DC power stored in the plurality of power storage devices, converting the power of the load into DC power corresponding to the plurality of power storage devices, and charging the plurality of power storage devices based on the power on the load side, and a control device controlling power conversion operations of the plurality of power conversion devices, wherein the control device includes an output value determination unit that determines a total value of active power and a total value of reactive power to be output from the plurality of power conversion devices, a conversion device determination unit that determines a power conversion device to which an operation command should be sent among the plurality of power conversion devices, and transmits the operation command to the power conversion device determined by the conversion device determination unit, and converts the operation command to the power conversion device determined by the conversion device determination unit, and a command transmitting unit that transmits a standby command to the remaining power electronics devices to which no command is to be transmitted, wherein the power electronics device determination unit has a priority list indicating priorities of the plurality of power electronics devices, the priority list having a plurality of data sets corresponding to each of the plurality of power electronics devices, and the plurality of data sets storing, in association with each other, priorities of the plurality of power electronics devices, identification information for identifying the plurality of power electronics devices, and information on states of the plurality of power storage devices and the plurality of power electronics devices, and the power electronics device determination unit determines the number of power electronics devices to which the operation command is to be transmitted, based on the total value of the active power and the total value of the reactive power determined by the output value determination unit and the information on the states of the plurality of data sets, and determines the determined number of power electronics devices from among the plurality of power electronics devices in order of highest priority in the priority list as the power electronics devices to which the operation command is to be transmitted. the information about the state includes information about the charge amount of the power storage device, information about a dischargeable amount of the power storage device, information about a chargeable amount of the power storage device, information about a capacitive reactive power outputable amount of the power conversion device, and information about an inductive reactive power outputable amount of the power conversion device, and when the output direction of the active power of the plurality of power conversion devices is a discharging direction in which power is supplied to the load, the conversion device determination unit performs an operation to add up the dischargeable amounts of the power conversion devices in descending order of priority in the priority list, and determines the number of power conversion devices whose added value of the dischargeable amount is equal to or greater than the total value of the active power determined by the output value determination unit as the number of power conversion devices required for active power; and when the output direction of the active power of the plurality of power conversion devices is a charging direction in which the power storage device is charged based on the power of the load, the conversion device determination unit performs an operation to add up the chargeable amounts of the power conversion devices in descending order of priority in the priority list, and determines the number of power conversion devices whose added value of the chargeable amount is equal to or greater than the total value of the active power determined by the output value determination unit as the number of power conversion devices required for active power. and when the reactive power output from the plurality of power conversion devices is capacitive reactive power, an operation is performed to add up the outputtable amounts of the capacitive reactive power in descending order of priority in the priority list, and the number of power conversion devices for which the value of the added outputtable amount of the capacitive reactive power is equal to or greater than the total value of the reactive power determined by the output value determination unit is determined as the number of power conversion devices required for reactive power; when the reactive power output from the plurality of power conversion devices is inductive reactive power, an operation is performed to add up the outputtable amounts of the inductive reactive power in descending order of priority in the priority list, and the number of power conversion devices for which the value of the added outputtable amount of the inductive reactive power is equal to or greater than the total value of the reactive power determined by the output value determination unit is determined as the number of power conversion devices required for reactive power; and the number of power conversion devices required for active power and the number of power conversion devices required for reactive power are compared, and the larger number is determined as the number of power conversion devices to transmit the operation command. A power storage system is provided. [Effects of the Invention]

[0008] According to the embodiments of the present invention, a power storage system and a control device that can suppress power loss are provided. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram schematically illustrating a power storage system according to an embodiment. [Figure 2] FIG. 2 is a block diagram schematically illustrating a control device according to the embodiment. [Figure 3] FIG. 10 is an explanatory diagram illustrating an example of a priority list. DETAILED DESCRIPTION OF THE INVENTION

[0010] Each embodiment will be described below with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In the present specification and the drawings, elements similar to those described above with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0011] FIG. 1 is a block diagram schematically illustrating a power storage system according to an embodiment. As shown in FIG. 1, the power storage system 2 includes a plurality of power storage devices 4, a plurality of power conversion devices 6, and a control device 10. The plurality of power storage devices 4 are capable of storing DC power, supplying (discharging) the stored DC power, and storing (charging) DC power again in response to an inflow of DC power greater than the stored DC power. The plurality of power storage devices 4 are, for example, devices using storage batteries. The plurality of power storage devices 4 may also be, for example, devices using capacitors. The plurality of power storage devices 4 may be any device capable of discharging and charging DC power.

[0012] The multiple power conversion devices 6 are provided corresponding to the multiple power storage devices 4, respectively. The number of the multiple power conversion devices 6 is, for example, the same as the number of the multiple power storage devices 4. The multiple power conversion devices 6 are connected to the multiple power storage devices 4, respectively. However, multiple power storage devices 4 may be connected to one power conversion device 6. The number of the multiple power conversion devices 6 does not necessarily have to be the same as the number of the multiple power storage devices 4.

[0013] The power storage system 2 further includes, for example, a plurality of transformers 12 and a transformer 14. The plurality of transformers 12 are provided corresponding to the plurality of power conversion devices 6, respectively. The plurality of power conversion devices 6 are connected to the plurality of transformers 12. The plurality of transformers 12 are connected to the transformer 14. The transformer 14 is connected to the power system PS. The plurality of power conversion devices 6 are connected to the power system PS, which is a load, via the transformers 12, 14, etc. A circuit breaker, more transformers, etc. may be provided between the power conversion device 6 and the power system PS. The configuration between the power conversion device 6 and the power system PS may be any configuration that allows the power conversion device 6 to be connected to the power system PS.

[0014] The power of the power system PS (load) is AC power. The power of the power system PS is, for example, three-phase AC power. However, the power of the power system PS (load) is not limited to AC power and may be DC power or the like.

[0015] The multiple power conversion devices 6 convert the DC power stored in the multiple power storage devices 4 into power compatible with the power grid PS, and also convert the power of the power grid PS into DC power compatible with the multiple power storage devices 4. The multiple power conversion devices 6 have, for example, multiple switching elements, and perform power conversion by switching the multiple switching elements. However, the multiple power conversion devices 6 may be configured in any way that allows for bidirectional conversion between converting the discharging direction of the multiple power storage devices 4 and converting the charging direction of the multiple power storage devices 4.

[0016] The plurality of power conversion devices 6 supply power to the power system PS based on the DC power stored in the plurality of power storage devices 4, and charge the plurality of power storage devices 4 based on the power on the power system PS side. In this way, the power storage system 2 suppresses, for example, frequency fluctuations in the power system PS.

[0017] The power storage system 2 further includes, for example, a measuring device 16. The measuring device 16 detects, for example, active power values, reactive power values, and voltage values at interconnection points between the plurality of power conversion devices 6 and the power system PS, and inputs the detected active power values, reactive power values, and voltage values to the control device 10.

[0018] The control device 10 controls the power conversion operations of the multiple power conversion devices 6. The control device 10 communicates with, for example, a measurement device 16 and acquires information on the active power value, reactive power value, and voltage value of the interconnection point from the measurement device 16. The control device 10 also acquires information on the states of the multiple power storage devices 4 and the multiple power conversion devices 6 by communicating with, for example, the multiple power storage devices 4 and the multiple power conversion devices 6. The control device 10 controls the operations of the multiple power conversion devices 6 based on the acquired information. The control device 10 controls the operations of the multiple power conversion devices 6 based on, for example, the acquired information so as to suppress frequency fluctuations in the power system PS.

[0019] The control device 10, for example, communicates with a plurality of power storage devices 4 to acquire information on the charge amount, dischargeable amount, and chargeable amount of the power storage device 4 as information on the state from each of the plurality of power storage devices 4. More specifically, the control device 10 communicates with BMUs (Battery Management Units) of the plurality of power storage devices 4 to acquire information on the charge amount, dischargeable amount, and chargeable amount from the BMUs of each power storage device 4.

[0020] In addition, the control device 10, for example, communicates with a plurality of power conversion devices 6 to acquire information on the amount of capacitive reactive power that the power conversion device 6 can output, information on the amount of inductive reactive power that the power conversion device 6 can output, and information on the operating status from each of the plurality of power conversion devices 6 as information on the status.

[0021] The amount of capacitive reactive power that the power conversion device 6 can output is, in other words, the upper limit of the reactive power output from the power conversion device 6. The amount of capacitive reactive power that the power conversion device 6 can output is, in other words, the amount of reactive power that increases the voltage at the interconnection point, out of the amount of reactive power that can be output from the power conversion device 6. The amount of inductive reactive power that the power conversion device 6 can output is, in other words, the lower limit of the reactive power output from the power conversion device 6. The amount of inductive reactive power that the power conversion device 6 can output is, in other words, the amount of reactive power that decreases the voltage at the interconnection point, out of the amount of reactive power that can be output from the power conversion device 6.

[0022] In other words, the capacitive reactive power is leading reactive power as viewed from the power system PS side (lagging reactive power as viewed from the power conversion device 6 side). In other words, the inductive reactive power is lagging reactive power as viewed from the power system PS side (leading reactive power as viewed from the power conversion device 6 side).

[0023] The information on the operating status indicates whether each power conversion device 6 is in an operating state, a standby state, or a stopped state. The operating state is a state in which the power conversion device 6 is performing a power conversion operation. In other words, the operating state is a state in which the power conversion device 6 is charging or discharging the electricity storage device 4.

[0024] The standby state is a state in which the power conversion device 6 stops the power conversion operation based on the control of the control device 10. For example, if the power conversion device 6 has a plurality of switching elements and is configured to perform the power conversion operation based on a gate signal (control signal) from the control device 10, the standby state is a gate block state in which the input of the gate signal from the control device 10 to the power conversion device 6 is stopped. In other words, the standby state is a pause state in which the power conversion operation of the power conversion device 6 is paused based on the control of the control device 10.

[0025] The stopped state is a state in which the power conversion device 6 cannot perform power conversion due to a device failure, etc. In other words, the stopped state is a failure state.

[0026] The control device 10 controls the operation of the multiple power conversion devices 6 based on the above-mentioned information. However, the information acquired by the control device 10 is not limited to the above, and may be any information necessary for controlling the multiple power conversion devices 6. The information included in the information about the states of the multiple power storage devices 4 and the multiple power conversion devices 6 is not limited to the above, and may be any information necessary for controlling the multiple power conversion devices 6.

[0027] FIG. 2 is a block diagram schematically illustrating a control device according to the embodiment. As shown in FIG. 2, the control device 10 includes an output value determination unit 20, a conversion device determination unit 22, and a command transmission unit 24.

[0028] The output value determination unit 20 determines the total value of active power and the total value of reactive power output from the multiple power conversion devices 6. The output value determination unit 20 determines the total value of active power and the total value of reactive power output from the multiple power conversion devices 6 by calculating the active power and reactive power required to suppress frequency fluctuations in the power system PS based on, for example, the active power value, reactive power value, and voltage value of the interconnection point input from the measurement device 16.

[0029] However, the method for determining the total value of active power and the total value of reactive power is not limited to the above. For example, the output value determination unit 20 may determine the total value of active power and the total value of reactive power based on a command value input from a higher-level controller or the like. The method for determining the total value of active power and the total value of reactive power may be any method depending on the system configuration of the power storage system 2, etc.

[0030] The converter determination unit 22 determines which power conversion device 6 to send an operation command to, from among the multiple power conversion devices 6. The converter determination unit 22 has a priority list 30 that indicates the priorities of the multiple power conversion devices 6. The converter determination unit 22 determines which power conversion device 6 to send an operation command to, from among the multiple power conversion devices 6, based on the priority list 30 and the total value of the active power and the total value of the reactive power determined by the output value determination unit 20.

[0031] After determining the power electronics device 6 to which the operation command is to be transmitted, the converter determination unit 22 inputs information about the determined power electronics device 6 to the command transmission unit 24.

[0032] The command transmitting unit 24 transmits an operation command to the power conversion devices 6 determined by the conversion device determining unit 22 based on the information input from the conversion device determining unit 22. The command transmitting unit 24 determines the active power and reactive power of each power conversion device 6, for example, by dividing the total value of the active power and the total value of the reactive power determined by the output value determining unit 20 by the number of devices determined by the conversion device determining unit 22, and transmits an operation command to the determined power conversion devices 6 so as to output the determined active power and reactive power.

[0033] Furthermore, the command transmitting unit 24 transmits standby commands to the remaining power conversion devices 6 among the plurality of power conversion devices 6 to which no operation command has been transmitted. The standby command is a command to stop the operation of the power conversion devices 6. In other words, the standby command is a command to put the power conversion devices 6 into a standby state. The standby command is, for example, a command to turn off a plurality of switching elements of the power conversion devices 6. The standby command is also sometimes called a gate block command or the like.

[0034] Furthermore, for example, if a circuit breaker or the like is provided between the power conversion device 6 and the power storage device 4 and between the power conversion device 6 and the transformer 12 (a branch point of a plurality of power conversion devices 6), the command transmitting unit 24 leaves the circuit breaker corresponding to the power conversion device 6 that sent the standby command in an on state when transmitting a standby command. In other words, when transmitting a standby command, the command transmitting unit 24 leaves the power conversion device 6 connected to the power storage device 4 and the power system PS, and stops only the operation of the power conversion device 6 by transmitting the standby command. The standby command is, for example, a command to stop the operation of the power conversion device 6 while allowing the power conversion device 6 to immediately operate.

[0035] The control device 10 operates at a predetermined control period, such as 100 ms. For example, the control device 10 acquires each piece of information at each control period, determines the total value of active power and the total value of reactive power to be output from the plurality of power conversion devices 6 at an output value determination unit 20, determines the power conversion device 6 to which an operation command is to be sent at a conversion device determination unit 22, and sends an operation command or a standby command to the plurality of power conversion devices 6 from a command transmission unit 24. In this way, the control device 10 controls the operation of the plurality of power conversion devices 6 at each predetermined control period.

[0036] FIG. 3 is an explanatory diagram illustrating an example of a priority list. 3, the priority list 30 has a plurality of data sets 30a corresponding to the plurality of power electronics devices 6, respectively. The plurality of data sets 30a store, in association with each other, the priorities of the plurality of power electronics devices 6, identification information for identifying the plurality of power electronics devices 6, and information on the states of the plurality of power storage devices 4 and the plurality of power electronics devices 6. The priority list 30 is, for example, table data in which these pieces of information are stored in association with each other.

[0037] The priority indicates the order of precedence for transmitting an operation command to the power electronics device 6 indicated by the identification information. The identification information is, for example, a unique device number assigned to each of the multiple power electronics devices 6 in order to identify the multiple power electronics devices 6. However, the identification information is not limited to this and may be any information that can identify each of the multiple power electronics devices 6.

[0038] The information regarding the state of the multiple power storage devices 4 and the multiple power conversion devices 6 includes, for example, information on the state of charge (SOC), information on the amount of dischargeable power, information on the amount of chargeable power, information on the amount of capacitive reactive power that can be output, information on the amount of inductive reactive power that can be output, and information on the operating status.

[0039] The information on the charge amount represents the charge amount of the power storage device 4 connected to the power conversion device 6 represented by the identification information. The information on the dischargeable amount represents the dischargeable amount of the power storage device 4 connected to the power conversion device 6 represented by the identification information. The information on the chargeable amount represents the chargeable amount of the power storage device 4 connected to the power conversion device 6 represented by the identification information. The information on the outputable amount of capacitive reactive power represents the outputable amount of capacitive reactive power of the power conversion device 6 represented by the identification information. The information on the outputable amount of inductive reactive power represents the outputable amount of inductive reactive power of the power conversion device 6 represented by the identification information.

[0040] The information on the operating status indicates the operating status of the power electronics device 6 indicated by the identification information. In other words, the operating status indicates whether the power electronics device 6 indicated by the identification information is in an operating state, a standby state, or a stopped state. For convenience, in FIG. 3, the operating state is indicated as "RUN," the standby state as "GB," and the stopped state as "STOP."

[0041] In this way, the priority list 30 is, for example, table data in which a plurality of data sets 30a corresponding to the plurality of power electronics devices 6 are arranged in order of priority. However, the information included in the data sets 30a is not limited to the above. The data sets 30a may further include, for example, other information.

[0042] The conversion device determination unit 22 determines the priorities of the multiple power electronics devices 6 in the priority list 30 according to the charge amounts of the multiple power storage devices 4. In this case, the conversion device determination unit 22 changes the priorities of the multiple power electronics devices 6 according to the output directions of the active powers of the multiple power electronics devices 6.

[0043] When the output direction of the active power of the plurality of power conversion devices 6 is a discharging direction in which power is supplied to the power grid PS, the conversion device determination unit 22 increases the priority of the power conversion device 6 in which the charge amount of the power storage device 4 is high. When the output direction of the active power of the plurality of power conversion devices 6 is a charging direction in which the power storage device 4 is charged based on the power of the power grid PS, the conversion device determination unit 22 increases the priority of the power conversion device 6 in which the charge amount of the power storage device 4 is low. This makes it possible to prevent a decrease in the charge amount or overcharging of the plurality of power storage devices 4.

[0044] The control device 10 periodically (e.g., at each control cycle) acquires information about the states of the plurality of power storage devices 4 and the plurality of power conversion devices 6, and inputs the acquired information to the conversion device determination unit 22. In other words, the conversion device determination unit 22 periodically acquires information about the states. For example, the conversion device determination unit 22 periodically communicates with the plurality of power storage devices 4 and the plurality of power conversion devices 6, thereby periodically acquiring information about the charge amount, dischargeable amount, chargeable amount, capacitive reactive power outputable amount, inductive reactive power outputable amount, and operating status of the power storage devices 4. Each piece of information is acquired in association with identification information. This allows the conversion device determination unit 22 to recognize each piece of information corresponding to each of the plurality of power conversion devices 6.

[0045] After acquiring the state information, the conversion device determination unit 22 updates the state information of the plurality of data sets 30a in the priority list 30 based on the acquired state information. As a result, the value of each item of the state information of the plurality of data sets 30a is updated to the current value of each power storage device 4 and each power conversion device 6.

[0046] When determining the power conversion device 6 to which an operation command is to be transmitted, the conversion device determination unit 22 determines, based on the total value of the active power output from the plurality of power conversion devices 6 determined by the output value determination unit 20, whether the output direction of the active power from the plurality of power conversion devices 6 is a direction to discharge from the plurality of power storage devices 4 or a direction to charge the plurality of power storage devices 4. For example, if the discharging direction is positive and the charging direction is negative, the conversion device determination unit 22 determines, based on the sign of the total value of the active power output from the plurality of power conversion devices 6, whether the output direction is a discharging direction or a charging direction.

[0047] In addition, when determining the power conversion device 6 to send an operation command, the conversion device determination unit 22 determines whether the direction is discharge or charge based on the sign of the total value of the active power, and determines whether the reactive power output from the multiple power conversion devices 6 is capacitive reactive power or inductive reactive power based on the total value of the reactive power output from the multiple power conversion devices 6 determined by the output value determination unit 20.

[0048] After the above determination, the converter determination unit 22 determines the number of power converters 6 to which an operation command is to be transmitted based on the priority list 30.

[0049] When the conversion device determination unit 22 determines that the direction of output of active power from a plurality of power electronics devices 6 is the discharge direction, it performs a calculation to add up the dischargeable amounts of the power electronics devices 6 in descending order of priority in the priority list 30. In this case, the conversion device determination unit 22 determines the number of power electronics devices 6 whose added dischargeable amount value (absolute value) is equal to or greater than the total value (absolute value) of the active power determined by the output value determination unit 20 as the number of power electronics devices 6 required for the active power.

[0050] For example, when the dischargeable amounts of five power conversion devices 6 in descending order of priority are added together, if the absolute value of the added dischargeable amounts is equal to or greater than the absolute value of the total active power, the conversion device determination unit 22 determines that the number of power conversion devices 6 required for active power is five.

[0051] At this time, the conversion device determination unit 22 excludes any power conversion device 6 that is in a stopped state from the calculation of adding up the dischargeable amounts, based on information on the operating status of each power conversion device 6 included in each data set 30a of the priority list 30. For example, if the operating status of the power conversion device 6 with the second highest priority is in a stopped state, the conversion device determination unit 22 excludes the second power conversion device 6 from the calculation, and adds up the dischargeable amounts of the power conversion device 6 with the first priority and the power conversion device 6 with the third priority.

[0052] On the other hand, when the conversion device determination unit 22 determines that the output direction of the active power of the multiple power electronics devices 6 is the charging direction, it performs a calculation to add up the chargeable amounts of the power electronics devices 6 in descending order of priority in the priority list 30. In this case, the conversion device determination unit 22 determines the number of power electronics devices 6 whose added chargeable amount value (absolute value) is equal to or greater than the total value (absolute value) of the active power determined by the output value determination unit 20 as the number of power electronics devices 6 required for the active power. At this time, the conversion device determination unit 22 excludes power electronics devices 6 that are in a stopped state from the calculation to add up the chargeable amounts, based on information on the operating status of each power electronics device 6 included in each data set 30a of the priority list 30.

[0053] When the conversion device determination unit 22 determines that the reactive power output from the multiple power electronics devices 6 is capacitive reactive power, it performs a calculation to add up the outputtable amounts of capacitive reactive power of the power electronics devices 6 in descending order of priority in the priority list 30. In this case, the conversion device determination unit 22 determines the number of power electronics devices 6 required for reactive power as the number of devices whose value (absolute value) of the added outputtable amount of capacitive reactive power is equal to or greater than the total value (absolute value) of the reactive power determined by the output value determination unit 20. At this time, the conversion device determination unit 22 excludes power electronics devices 6 that are in a stopped state from the calculation to add up the capacitive reactive power, based on information on the operating status of each power electronics device 6 included in each data set 30a of the priority list 30.

[0054] On the other hand, when the converter determination unit 22 determines that the reactive power output from the multiple power electronics devices 6 is inductive reactive power, it performs a calculation to add up the outputtable amounts of inductive reactive power of the power electronics devices 6 in descending order of priority in the priority list 30. In this case, the converter determination unit 22 determines the number of power electronics devices 6 required for reactive power as the number of devices whose value (absolute value) of the added outputtable amount of inductive reactive power is equal to or greater than the total value (absolute value) of the reactive power determined by the output value determination unit 20. At this time, the converter determination unit 22 excludes power electronics devices 6 that are in a stopped state from the calculation to add up the inductive reactive power, based on information on the operating status of each power electronics device 6 included in each data set 30a of the priority list 30.

[0055] After determining the number of power conversion devices 6 required for active power and the number of power conversion devices 6 required for reactive power, the conversion device determination unit 22 compares the number of power conversion devices 6 required for active power with the number of power conversion devices 6 required for reactive power, and determines the larger number as the number of power conversion devices 6 that will send operation commands.

[0056] After determining the number of power electronics devices 6 to which an operation command is to be transmitted, the conversion device determination unit 22 determines the determined number of power electronics devices 6 from among the multiple power electronics devices 6 in descending order of priority in the priority list 30 as the power electronics devices 6 to which an operation command is to be transmitted. However, based on information on the operating status of each power electronics device 6 included in each data set 30a of the priority list 30, the conversion device determination unit 22 excludes a power electronics device 6 that is in a stopped state from the power electronics devices 6 to which an operation command is to be transmitted.

[0057] For example, when the converter determination unit 22 determines that the number of power electronics devices 6 to which operation commands are to be sent is five, it determines the five power electronics devices 6 with the highest priorities in the priority list 30 as the power electronics devices 6 to which operation commands are to be sent. At this time, if the operation status of the power electronics device 6 with the fifth highest priority is in a stopped state, the converter determination unit 22 excludes the power electronics device 6 with the fifth highest priority from the power electronics devices 6 to which operation commands are to be sent, and adds the power electronics device 6 with the sixth highest priority to the power electronics devices 6 to which operation commands are to be sent.

[0058] As described above, after determining the power electronics device 6 to which an operation command is to be transmitted, the conversion device determination unit 22 inputs information about the determined power electronics device 6 to the command transmission unit 24. For example, the conversion device determination unit 22 inputs identification information of the determined power electronics device 6 to the command transmission unit 24, thereby enabling the command transmission unit 24 to identify the power electronics device 6 to which an operation command is to be transmitted.

[0059] The charge amounts of the multiple power storage devices 4 change depending on the operations of the multiple power conversion devices 6. For this reason, the conversion device determination unit 22 periodically updates the priorities of the multiple power conversion devices 6. For example, the conversion device determination unit 22 updates the priorities of the multiple power conversion devices 6 every time it periodically acquires information necessary for control. In other words, the conversion device determination unit 22 updates the priorities of the multiple power conversion devices 6 every control cycle of the control device 10. However, the cycle for updating the priorities does not necessarily have to be the same as the control cycle.

[0060] In updating the priority, the conversion device determination unit 22 first determines, based on the total value of the active power output from the multiple power conversion devices 6 determined by the output value determination unit 20, whether the direction in which the active power of the multiple power conversion devices 6 is output is to discharge the multiple storage devices 4 or to charge the multiple storage devices 4.

[0061] When the conversion device determination unit 22 determines that the output direction of the active power is the discharging direction, it increases the priority of the power conversion device 6 having a high charge amount of the power storage device 4. When the conversion device determination unit 22 determines that the output direction of the active power is the charging direction, it increases the priority of the power conversion device 6 having a low charge amount of the power storage device 4.

[0062] After determining the output direction of the active power, the conversion device determination unit 22 performs a sorting process on each data set 30a corresponding to each power conversion device 6 based on the charge amount information contained in each data set 30a in the priority list 30.

[0063] When the converter determination unit 22 determines that the output direction of the active power is the discharging direction, it rearranges the plurality of data sets 30a in descending order of the charge amount of the power storage device 4. This makes it possible to update the priorities of the plurality of power converters 6 in the priority list 30 so that the priority of the power converter 6 with the highest charge amount of the power storage device 4 is increased.

[0064] Furthermore, when the conversion device determination unit 22 determines that the output direction of the active power is the charging direction, it rearranges the multiple data sets 30a in ascending order of the charge amount of the power storage device 4. This makes it possible to update the priorities of the multiple power conversion devices 6 in the priority list 30 so that the priority of the power conversion device 6 with the lowest charge amount of the power storage device 4 is increased.

[0065] The conversion device determination unit 22 performs the sorting process by, for example, comparing the charge amounts of two adjacent data sets 30 a in each data set 30 a arranged in the order of priority in the priority list 30 .

[0066] When the output direction of the active power is the discharge direction, the conversion device determination unit 22 compares the charge amounts of two adjacent data sets 30a in the priority list 30 in order from the one with the highest priority, and rearranges the order of the two data sets 30a as necessary so that the power conversion device 6 with the higher charge amount has a higher priority.

[0067] At this time, the conversion device determination unit 22 sets a dead zone in the comparison of the charge amounts of two adjacent data sets 30a, for example. If the difference between the two charge amounts is equal to or greater than a predetermined value, the conversion device determination unit 22 swaps the order of the two data sets 30a.

[0068] For example, the converter determination unit 22 compares the data set 30a of the power electronics device 6 with the highest priority with the data set 30a of the power electronics device 6 with the second highest priority, and if the charge amount of the data set 30a corresponding to the power electronics device 6 with the second highest priority is higher by a predetermined value or more than the charge amount of the data set 30a corresponding to the power electronics device 6 with the highest priority, swaps the order of the two data sets 30a. That is, the priority of the power electronics device 6 that was second becomes the highest, and the priority of the power electronics device 6 with the highest becomes second.

[0069] The predetermined value is set to, for example, about 2% to 3% of the maximum amount of charge. This makes it possible to prevent the order of the data sets 30a of the two power electronics devices 6 from being frequently switched. For example, it is possible to prevent a power electronics device 6 that transmits an operation command from being frequently switched with a power electronics device 6 that transmits a standby command, which would cause a delay in the operation of the power electronics devices 6. However, it is not necessarily required to provide a dead band.

[0070] The conversion device determination unit 22 performs the above process sequentially from the power electronics device 6 with the highest priority to the power electronics device 6 with the second highest priority, and then compares the power electronics device 6 with the second highest priority to the power electronics device 6 with the third highest priority, and so on. As a result, when the output direction of active power is the discharging direction, the conversion device determination unit 22 rearranges the data sets 30a in descending order of charge amount. Note that, conversely to the above, when the output direction of active power is the discharging direction, the conversion device determination unit 22 may compare the charge amounts of the data sets 30a corresponding to two adjacent power electronics devices 6 in the priority list 30 in ascending order of priority.

[0071] When the output direction of active power is the charging direction, the conversion device determination unit 22 compares the charge amounts of the data sets 30a corresponding to two adjacent power electronics devices 6 in the priority list 30 in order from highest priority, and rearranges the order of the two data sets 30a as necessary so that the priority of the power electronics device 6 with the lowest charge amount is increased. In this way, when the output direction of active power is the charging direction, the conversion device determination unit 22 rearranges the data sets 30a in order from lowest charge amount. Note that, conversely to the above, when the output direction of active power is the charging direction, the conversion device determination unit 22 may compare the charge amounts of the data sets 30a corresponding to two adjacent power electronics devices 6 in the priority list 30 in order from lowest priority.

[0072] When the number of the plurality of power electronics devices 6 is N, the converter determination unit 22 performs the above-described process of comparing the charged amounts, for example, (N×(N−1)) / 2 times.

[0073] When comparing the charge amounts of two adjacent data sets 30a, the number of comparisons required to compare the charge amounts of all data sets 30a in the priority list 30 once is N-1. For example, if there are five power electronics devices 6, the number of comparisons required to compare the charge amounts of all data sets 30a in the priority list 30 once is four in total, including the first and second priorities, the second and third priorities, the third and fourth priorities, and the fourth and fifth priorities. This allows comparisons to be performed once for each of the charge amounts of the power electronics devices 6, from the highest priority to the lowest priority.

[0074] In this way, by performing comparisons N-1 times, it is possible to determine the power electronics device 6 with the highest priority or the power electronics device 6 with the lowest priority. For example, if the charge amounts of the data sets 30a are compared in order from highest priority, and the order of the two data sets 30a is rearranged as necessary so that the power electronics device 6 with the higher charge amount has a higher priority, it is possible to determine the power electronics device 6 with the lowest priority by performing comparisons N-1 times. Conversely, if the charge amounts are compared in order from lowest priority, and the order of the two data sets 30a is rearranged as necessary so that the power electronics device 6 with the higher charge amount has a higher priority, it is possible to determine the power electronics device 6 with the highest priority by performing comparisons N-1 times.

[0075] When making subsequent comparisons, the converter determination unit 22 repeats the same process for the remaining power electronics devices 6 excluding the determined power electronics device 6.

[0076] For example, if there are five power electronics devices 6, the fifth power electronics device 6 is determined by comparing the first and second priorities, the second and third priorities, the third and fourth priorities, and the fourth and fifth priorities. Then, the fourth power electronics device 6 is determined by comparing the first and second priorities, the second and third priorities, and the third and fourth priorities. Then, the third power electronics device 6 is determined by comparing the first and second priorities and the second and third priorities. Finally, the first and second power electronics devices 6 are determined by comparing the first and second priorities. This allows the power electronics devices 6 to be rearranged in order according to their charge amounts from first to fifth. In this case, the number of comparisons is 10 (4 times + 3 times + 2 times + 1 time), which is equal to (5 × (5 - 1)) / 2 = 10.

[0077] By rearranging the data as described above, the data sets 30a of the N power electronics devices 6 can be appropriately rearranged in an order according to the charge amounts by the number of times calculated from the above formula. This reduces the number of comparison operations compared to, for example, repeating (N-1) operations N times. The data sets 30a of the N power electronics devices 6 can be appropriately rearranged in an order according to the charge amounts with a relatively small number of operations.

[0078] The conversion device determination unit 22 periodically performs the process of comparing the charge amounts (N×(N-1)) / 2 times, and rearranges the data sets 30a in descending order of charge amount when the output direction of active power is the discharging direction, and rearranges the data sets 30a in descending order of charge amount when the output direction of active power is the charging direction.

[0079] For example, when updating the priority at each control cycle of the control device 10, the conversion device determination unit 22 performs the sorting process of each data set 30a as described above, and then determines the power conversion device 6 to which an operation command is to be sent, and inputs information about the determined power conversion device 6 to the command transmission unit 24.

[0080] However, the priority update period may be set to be longer than the control period. For example, the priority may be updated once every two or three control periods.

[0081] In the above example, the conversion device determination unit 22 sorts all of the data sets 30a at each priority update cycle in descending order of the charge amount of the power storage device 4 or in descending order of the charge amount of the power storage device 4. However, the sorting process of the charge amount after update is not limited to the above.

[0082] The conversion device determination unit 22 may, for example, compare the charge amounts of two adjacent data sets 30a in the priority list 30 in order from the side with the highest priority or the side with the lowest priority at each priority update period, and, if necessary, perform the process of rearranging the order of the two data sets 30a once for each of the multiple data sets 30a in the priority list 30.

[0083] That is, the conversion device determination unit 22 may perform the comparison in the above example N-1 times at each priority update cycle to determine the power electronics device 6 with the highest priority or the power electronics device 6 with the lowest priority. Note that even in this case, the conversion device determination unit 22 may provide a dead zone in the comparison of the charge amounts corresponding to two adjacent power electronics devices 6.

[0084] As in the above example, if all data sets 30a are rearranged at each priority update cycle, there is a possibility that the power conversion device 6 that sends an operation command and the power conversion device 6 that sends a standby command will be significantly swapped when the output direction of active power changes.

[0085] For example, if there are 10 power conversion devices 6, and an operation command is sent to five of the 10 power conversion devices 6 and a standby command is sent to the remaining five power conversion devices 6, if the output direction of active power changes, the power conversion devices 6 in operation and the standby power conversion devices 6 may switch places at once. In this case, there is a possibility that delays may occur in the operation of the multiple power conversion devices 6.

[0086] In contrast, if comparisons are made N-1 times at each priority update cycle, even if the output direction of active power changes, it is possible to prevent the power conversion device 6 that sends the operation command from being significantly switched with the power conversion device 6 that sends the standby command.

[0087] For example, if there are 10 power conversion devices 6, and operation commands are sent to five of the 10 power conversion devices 6 and standby commands are sent to the remaining five power conversion devices 6, when the output direction of active power changes, the power conversion devices 6 that send operation commands and the power conversion devices 6 that send standby commands can be swapped one by one in descending order of charge amount or descending order of charge amount at each priority update period. This makes it possible to prevent delays in the operation of the multiple power conversion devices 6.

[0088] The converter determination unit 22 may perform comparisons 2×(N-1) times, for example, at each priority update cycle. In this case, when the output direction of active power changes, the power electronics devices 6 that send operation commands and the power electronics devices 6 that send standby commands can be switched two by two at each priority update cycle in order of decreasing charge amount or decreasing charge amount. The number of comparisons by the converter determination unit 22 may be set to any number between N-1 and (N×(N-1)) / 2.

[0089] The priorities of the multiple power conversion devices 6 do not necessarily have to be determined based on the charge amounts of the multiple power storage devices 4. For example, in the power storage system 2, the capacities of the multiple power storage devices 4 and the multiple power conversion devices 6 may differ. In this case, the priorities of the multiple power conversion devices 6 may be determined according to the capacities of the multiple power storage devices 4 and the multiple power conversion devices 6. For example, the priorities of the multiple power conversion devices 6 may be determined in descending order of the capacities of the multiple power storage devices 4 and the multiple power conversion devices 6.

[0090] As described above, in the energy storage system 2 according to this embodiment, the conversion device determination unit 22 of the control device 10 determines the number of power conversion devices 6 to which to send an operation command based on the total value of active power and the total value of reactive power determined by the output value determination unit 20 and information on the states of the plurality of data sets 30a, and determines the determined number of power conversion devices 6 from among the plurality of power conversion devices 6 in descending order of priority in the priority list 30 as the power conversion devices 6 to which to send an operation command.

[0091] As a result, in the energy storage system 2 and the control device 10 according to this embodiment, it is possible to reduce the power loss associated with the operation of the multiple power conversion devices 6 compared to a control method in which all of the multiple power conversion devices 6 are operated regardless of the amount of power required by the power system PS (load).

[0092] For example, it is also conceivable to determine the number of power conversion devices 6 to transmit operation commands based on information on the rated capacity of active power per unit of the plurality of power conversion devices 6 and information on the rated capacity of reactive power per unit of the plurality of power conversion devices 6. However, in this case, if there is a difference between the amount of power that the power conversion device 6 can actually output and the rated capacity, there is a possibility that the required amount of power cannot be supplied to the load or each power storage device 4.

[0093] In the power storage system 2 and the control device 10 according to this embodiment, as described above, the conversion device determination unit 22 determines the number of power electronics devices 6 to which an operation command is to be transmitted, based on the total value of the active power and the total value of the reactive power determined by the output value determination unit 20 and information on the states of the plurality of data sets 30a. This makes it possible to more appropriately determine the number of power electronics devices 6 to which an operation command is to be transmitted, taking into consideration the respective states of the plurality of power storage devices 4 and the plurality of power electronics devices 6. Therefore, in the power storage system 2 and the control device 10 according to this embodiment, it is possible to more appropriately supply the required amount of power to the load or each power storage device 4, compared to a case where the rated capacity of the power electronics device 6 is used. For example, it is possible to more appropriately suppress frequency fluctuations in the power system PS while suppressing power loss due to the operation of the plurality of power electronics devices 6.

[0094] Furthermore, in the power storage system 2 and the control device 10 according to this embodiment, when the conversion device determination unit 22 determines a determined number of power conversion devices 6 from among the multiple power conversion devices 6 in descending order of priority in the priority list 30 as power conversion devices 6 to which an operation command is to be transmitted, the conversion device determination unit 22 excludes power conversion devices 6 in a stopped state from the power conversion devices 6 to which an operation command is to be transmitted, based on information on the operating status included in the state information. This makes it possible to more appropriately determine the number of power conversion devices 6 to which an operation command is to be transmitted, and to more appropriately supply the required amount of power to the load or each power storage device 4.

[0095] In addition, in the energy storage system 2 and the control device 10 according to this embodiment, when the direction is discharging, the conversion device determination unit 22 determines the number of units whose added dischargeable amount is equal to or greater than the total value of the active power as the number of power conversion devices 6 required for active power; when the direction is charging, the conversion device determination unit 22 determines the number of units whose added chargeable amount is equal to or greater than the total value of the active power as the number of power conversion devices 6 required for active power; when the direction is capacitive reactive power, the conversion device determination unit 22 determines the number of units whose added outputable amount of capacitive reactive power is equal to or greater than the total value of the reactive power as the number of power conversion devices 6 required for reactive power; when the direction is inductive reactive power, the conversion device determination unit 22 determines the number of units whose added outputable amount of inductive reactive power is equal to or greater than the total value of the reactive power as the number of power conversion devices 6 required for reactive power; and the number of power conversion devices 6 required for active power and the number of power conversion devices 6 required for reactive power are compared, and the larger number is determined as the number of power conversion devices 6 that transmit operation commands. This makes it possible to more appropriately determine the number of power electronics devices 6 to which operation commands are to be transmitted, and more appropriately supply the required amount of power to the load or each power storage device 4.

[0096] Furthermore, in the power storage system 2 and the control device 10 according to this embodiment, the conversion device determination unit 22 excludes a power conversion device 6 that is in a stopped state from the calculations for adding up the dischargeable amount, the chargeable amount, the capacitive reactive power, and the inductive reactive power, based on information about the operating condition included in the state information. This makes it possible to more appropriately determine the number of power conversion devices 6 to which an operation command is to be transmitted, and to more appropriately supply the required amount of power to the load or each power storage device 4.

[0097] In the above embodiment, the conversion device determination unit 22 acquires information about the states of the plurality of power storage devices 4 and the plurality of power conversion devices 6 by communicating with each of the plurality of power storage devices 4 and the plurality of power conversion devices 6. The information about the states of the plurality of power storage devices 4 and the plurality of power conversion devices 6 is not limited to the above, and may be acquired, for example, from a higher-level controller. The method of acquiring the information about the states may be any method that allows the conversion device determination unit 22 to appropriately acquire the information about the states.

[0098] Furthermore, in the above embodiment, an example is shown in which the power system PS is used as a load and the power storage system 2 is applied to the power system PS. The power storage system 2 is not limited to the power system PS, and may be applied to, for example, an electric vehicle such as an electric locomotive or an electric automobile. For example, the above-described power storage system 2 may be applied when a motor of an electric vehicle is used as a load and multiple power conversion devices 6 are connected to the motor, and power is supplied to the motor and multiple power storage devices 4 are charged by regenerative energy from the motor. The load to which the power storage system 2 is applied is not limited to the power system PS or an electric vehicle, and may be any load that can supply power to the load and charge multiple power storage devices 4 by power on the load side.

[0099] The present embodiment includes the following aspects. (Appendix 1) a plurality of power storage devices capable of discharging and charging DC power; a plurality of power conversion devices connected to the plurality of power storage devices and loads, converting DC power stored in the plurality of power storage devices into power corresponding to the loads, supplying power to the loads based on the DC power stored in the plurality of power storage devices, and converting power of the load into DC power corresponding to the plurality of power storage devices, and charging the plurality of power storage devices based on the power on the load side; a control device that controls the power conversion operations of the plurality of power conversion devices; Equipped with The control device an output value determination unit that determines a total value of active power and a total value of reactive power output from the plurality of power conversion devices; a converter determination unit that determines a power converter to which an operation command is to be transmitted from among the plurality of power converters; a command transmitting unit that transmits the operation command to the power electronics device determined by the converter determination unit and transmits a standby command to the remaining power electronics devices among the plurality of power electronics devices to which the operation command is not transmitted; and the converter determination unit has a priority list indicating priorities of the plurality of power converters, the priority list includes a plurality of data sets corresponding to each of the plurality of power electronics devices; the plurality of data sets store, in association with each other, priorities of the plurality of power electronics devices, identification information for identifying the plurality of power electronics devices, and information on states of the plurality of power storage devices and the plurality of power electronics devices; the conversion device determination unit determines the number of power conversion devices to which the operation command is to be sent, based on the total value of the active power and the total value of the reactive power determined by the output value determination unit and information about the states of the plurality of data sets, and determines the determined number of power conversion devices, among the plurality of power conversion devices, in descending order of priority in the priority list, as the power conversion devices to which the operation command is to be sent.

[0100] (Appendix 2) the information about the state includes information about the operating conditions of the plurality of power conversion devices, the information on the operating status indicates whether the plurality of power electronics devices are in an operating state, a standby state, or a stopped state; 2. The power storage system according to claim 1, wherein the conversion device determination unit, when determining a determined number of the power conversion devices from among the plurality of the power conversion devices in descending order of priority in the priority list as the power conversion devices to which the operation command is to be sent, excludes the power conversion devices in a stopped state from the power conversion devices to which the operation command is to be sent based on information on the operating status included in the information on the state.

[0101] (Appendix 3) the information on the state includes information on the charge amount of the power storage device, information on a dischargeable amount of the power storage device, information on a chargeable amount of the power storage device, information on a capacitive reactive power outputable amount of the power conversion device, and information on an inductive reactive power outputable amount of the power conversion device; The conversion device determination unit when the direction of output of the active power of the plurality of power electronics devices is a discharge direction, a calculation is performed to add up the dischargeable amounts of the power electronics devices in descending order of priority in the priority list, and the number of devices whose added value of the dischargeable amounts is equal to or greater than the total value of the active power determined by the output value determination unit is determined as the number of the power electronics devices required for the active power; when the direction of output of the active power of the plurality of power electronics devices is the charging direction, a calculation is performed to add up the chargeable amounts of the power electronics devices in descending order of priority in the priority list, and the number of devices whose added chargeable amounts are equal to or greater than the total value of the active power determined by the output value determination unit is determined as the number of the power electronics devices required for the active power; When the reactive power output from the plurality of power conversion devices is capacitive reactive power, a calculation is performed to add up the outputtable amounts of the capacitive reactive power in descending order of priority in the priority list, and the number of power conversion devices whose added outputtable amounts of the capacitive reactive power are equal to or greater than the total value of the reactive power determined by the output value determination unit is determined as the number of power conversion devices required for the reactive power; When the reactive power output from the plurality of power conversion devices is inductive reactive power, a calculation is performed to add up the outputtable amounts of the inductive reactive power in descending order of priority of the power conversion devices in the priority list, and the number of power conversion devices whose added outputtable amounts of the inductive reactive power are equal to or greater than the total value of the reactive power determined by the output value determination unit is determined as the number of power conversion devices required for the reactive power; 3. The power storage system according to claim 1, wherein the number of the power conversion devices required for active power is compared with the number of the power conversion devices required for reactive power, and the larger number is determined as the number of the power conversion devices to transmit the operation command.

[0102] (Appendix 4) the information about the state includes information about the operating conditions of the plurality of power conversion devices, the information on the operating status indicates whether the plurality of power electronics devices are in an operating state, a standby state, or a stopped state; 4. The energy storage system according to claim 3, wherein the conversion device determination unit excludes the power conversion device in the stopped state from the calculation of adding up the dischargeable amount, the calculation of adding up the chargeable amount, the calculation of adding up the capacitive reactive power, and the calculation of adding up the inductive reactive power, based on the information on the operating status included in the information on the state.

[0103] (Appendix 5) the information about the state includes information about the charge amount of the power storage device, 5. The energy storage system according to any one of appendixes 1 to 4, wherein the conversion device determination unit determines priorities of the plurality of power electronics devices in the priority list according to the charge amounts of the plurality of energy storage devices, and when the output direction of the active power of the plurality of power electronics devices is a discharging direction in which power is supplied to the load, the conversion device determination unit increases the priority of the power electronics device having a high charge amount of the energy storage device, and when the output direction of the active power of the plurality of power electronics devices is a charging direction in which the energy storage device is charged based on the power of the load, the conversion device determination unit increases the priority of the power electronics device having a low charge amount of the energy storage device.

[0104] (Appendix 6) The energy storage system according to claim 5, wherein the conversion device determination unit periodically acquires information related to the status, updates the information related to the status of the plurality of data sets based on the acquired information related to the status, and periodically updates the priorities of the plurality of power conversion devices in the priority list by sorting the charge amounts of the energy storage devices included in the updated information related to the status.

[0105] (Appendix 7) 7. The energy storage system according to claim 6, wherein the conversion device determination unit rearranges the plurality of data sets in descending order of charge amounts of the energy storage devices when the output direction of the active power of the plurality of power conversion devices is a discharging direction in which power is supplied to the load, and rearranges the plurality of data sets in descending order of charge amounts of the energy storage devices when the output direction of the active power of the plurality of power conversion devices is a charging direction in which the energy storage devices are charged based on the power of the load.

[0106] (Appendix 8) when the output direction of the active power is the discharge direction, the conversion device determination unit compares the charge amounts of the two adjacent data sets in the priority list in order from the side with the highest priority or the side with the lowest priority, and performs a process of rearranging the order of the two data sets as necessary so that the priority of the power conversion device with the higher charge amount is higher, once for each of the charge amounts of the power conversion device with the highest priority and the power conversion device with the lowest priority, thereby determining the power conversion device with the highest priority or the power conversion device with the lowest priority, and repeats the same process for the remaining power conversion devices excluding the determined power conversion device, thereby sorting the updated multiple data sets in order of highest charge amount by (N×(N−1)) / 2 times the number of comparisons, where N is the number of the multiple power conversion devices; the power conversion device determination unit, when the output direction of the active power is the charge direction, compares the charge amounts of the two data sets adjacent to each other in the priority list in order from the side with the highest priority or the side with the lowest priority, and rearranges the order of the two data sets as necessary so that the priority of the power conversion device with the lowest charge amount is increased, by performing this process once for each of the charge amounts of the power conversion device with the highest priority and the power conversion device with the lowest priority, thereby determining the power conversion device with the highest priority or the power conversion device with the lowest priority, and by repeating the same process for the remaining power conversion devices excluding the determined power conversion device, the plurality of data sets after update are rearranged in order from the side with the lowest charge amount with the number of comparisons being (N×(N−1)) / 2.

[0107] (Appendix 9) 9. The energy storage system according to claim 8, wherein the conversion device determination unit swaps the order of the two data sets when comparing the charge amounts of two adjacent data sets and the difference between the two charge amounts is equal to or greater than a predetermined value.

[0108] (Appendix 10) 8. The energy storage system according to claim 7, wherein the conversion device determination unit compares the charge amounts of two adjacent data sets in the priority list in order from the data set with the highest priority or the data set with the lowest priority at each update period of the information about the state, and performs a process of swapping the order of the two data sets as necessary, once for each of the plurality of data sets in the priority list.

[0109] (Appendix 11) A control device is connected to a plurality of power storage devices and a load, converts DC power stored in the plurality of power storage devices into power corresponding to the load, supplies power to the load based on the DC power stored in the plurality of power storage devices, converts power of the load into DC power corresponding to the plurality of power storage devices, and controls power conversion operations of a plurality of power conversion devices that charge the plurality of power storage devices based on power on the load side, an output value determination unit that determines a total value of active power and a total value of reactive power output from the plurality of power conversion devices; a converter determination unit that determines a power converter to which an operation command is to be transmitted from among the plurality of power converters; a command transmitting unit that transmits the operation command to the power electronics device determined by the converter determination unit and transmits a standby command to the remaining power electronics devices among the plurality of power electronics devices to which the operation command is not transmitted; Equipped with the converter determination unit has a priority list indicating priorities of the plurality of power converters, the priority list includes a plurality of data sets corresponding to each of the plurality of power electronics devices; the plurality of data sets store, in association with each other, priorities of the plurality of power electronics devices, identification information for identifying the plurality of power electronics devices, and information on states of the plurality of power storage devices and the plurality of power electronics devices; the conversion device determination unit determines the number of power conversion devices to which the operation command is to be sent, based on the total value of the active power and the total value of the reactive power determined by the output value determination unit and information about the states of the plurality of data sets, and determines the determined number of power conversion devices, among the plurality of power conversion devices, in descending order of priority in the priority list, as the power conversion devices to which the operation command is to be sent.

[0110] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

Claims

1. a plurality of power storage devices capable of discharging and charging DC power; a plurality of power conversion devices connected to the plurality of power storage devices and loads, converting DC power stored in the plurality of power storage devices into power corresponding to the loads, supplying power to the loads based on the DC power stored in the plurality of power storage devices, and converting power of the load into DC power corresponding to the plurality of power storage devices, and charging the plurality of power storage devices based on the power on the load side; a control device that controls the power conversion operations of the plurality of power conversion devices; Equipped with The control device an output value determination unit that determines a total value of active power and a total value of reactive power output from the plurality of power conversion devices; a converter determination unit that determines a power converter to which an operation command is to be transmitted from among the plurality of power converters; a command transmitting unit that transmits the operation command to the power electronics device determined by the converter determination unit and transmits a standby command to the remaining power electronics devices among the plurality of power electronics devices to which the operation command is not transmitted; and the converter determination unit has a priority list indicating priorities of the plurality of power converters, the priority list includes a plurality of data sets corresponding to each of the plurality of power electronics devices; the plurality of data sets store, in association with each other, priorities of the plurality of power electronics devices, identification information for identifying the plurality of power electronics devices, and information on states of the plurality of power storage devices and the plurality of power electronics devices; the converter determination unit determines the number of power electronics devices to which the operation command is to be transmitted, based on the total value of the active power and the total value of the reactive power determined by the output value determination unit and information about the states of the plurality of data sets, and determines the determined number of power electronics devices, among the plurality of power electronics devices, in descending order of priority in the priority list, as the power electronics devices to which the operation command is to be transmitted; the information on the state includes information on the charge amount of the power storage device, information on a dischargeable amount of the power storage device, information on a chargeable amount of the power storage device, information on a capacitive reactive power outputable amount of the power conversion device, and information on an inductive reactive power outputable amount of the power conversion device; The conversion device determination unit when the direction of output of the active power of the plurality of power electronics devices is a discharge direction for supplying power to the load, a calculation is performed to add up the dischargeable amounts of the power electronics devices in descending order of priority in the priority list, and the number of devices whose added value of the dischargeable amounts is equal to or greater than the total value of the active power determined by the output value determination unit is determined as the number of the power electronics devices required for the active power; when the direction of output of the active power of the plurality of power electronics devices is a charge direction in which the storage device is charged based on the power of the load, a calculation is performed to add up the chargeable amounts of the power electronics devices in descending order of priority in the priority list, and the number of devices whose added chargeable amounts are equal to or greater than the total value of the active power determined by the output value determination unit is determined as the number of the power electronics devices required for the active power; When the reactive power output from the plurality of power conversion devices is capacitive reactive power, a calculation is performed to add up the outputtable amounts of the capacitive reactive power in descending order of priority in the priority list, and the number of power conversion devices whose added outputtable amounts of the capacitive reactive power are equal to or greater than the total value of the reactive power determined by the output value determination unit is determined as the number of power conversion devices required for the reactive power; When the reactive power output from the plurality of power conversion devices is inductive reactive power, a calculation is performed to add up the outputtable amounts of the inductive reactive power in descending order of priority of the power conversion devices in the priority list, and the number of power conversion devices whose added outputtable amounts of the inductive reactive power are equal to or greater than the total value of the reactive power determined by the output value determination unit is determined as the number of power conversion devices required for the reactive power; a power storage system that compares the number of the power conversion devices required for active power with the number of the power conversion devices required for reactive power, and determines the larger number as the number of the power conversion devices to transmit the operation command.

2. the information about the state includes information about the operating conditions of the plurality of power conversion devices, the information on the operating status indicates whether the plurality of power electronics devices are in an operating state, a standby state, or a stopped state; 2. The power storage system according to claim 1, wherein the conversion device determination unit excludes the power conversion device in the stopped state from the calculation of the addition of the dischargeable amount, the calculation of the addition of the chargeable amount, the calculation of the addition of the capacitive reactive power, and the calculation of the addition of the inductive reactive power, based on the information on the operating status included in the information on the state.

3. the information about the state includes information about the charge amount of the power storage device, 2. The energy storage system according to claim 1, wherein the conversion device determination unit determines priorities of the plurality of power conversion devices in the priority list according to the charge amounts of the plurality of energy storage devices, and when the output direction of the active power of the plurality of power conversion devices is a discharging direction in which power is supplied to the load, the conversion device determination unit increases the priority of the power conversion device having a high charge amount of the energy storage device, and when the output direction of the active power of the plurality of power conversion devices is a charging direction in which the energy storage device is charged based on the power of the load, the conversion device determination unit increases the priority of the power conversion device having a low charge amount of the energy storage device.

4. the power storage system according to claim 3, wherein the conversion device determination unit periodically acquires information related to the status, updates the information related to the status of the plurality of data sets based on the acquired information related to the status, and performs a process of rearranging the amounts of charge of the power storage devices included in the updated information related to the status, thereby periodically updating the priorities of the plurality of power conversion devices in the priority list.

5. 5. The power storage system according to claim 4, wherein the conversion device determination unit rearranges the plurality of data sets in descending order of charge amounts of the power storage devices when the output direction of the active power of the plurality of power conversion devices is a discharging direction in which power is supplied to the load, and rearranges the plurality of data sets in descending order of charge amounts of the power storage devices when the output direction of the active power of the plurality of power conversion devices is a charging direction in which the power storage devices are charged based on the power of the load.

6. When the output direction of the active power is the discharge direction, the conversion device determination unit compares the charge amounts of the two adjacent data sets in the priority list in order from the side with the highest priority or the side with the lowest priority, and performs a process of rearranging the order of the two data sets as necessary so that the priority of the power conversion device with the higher charge amount is increased, once for each of the charge amounts of the power conversion device with the highest priority and the power conversion device with the lowest priority, thereby determining the power conversion device with the highest priority or the power conversion device with the lowest priority, and repeats the same process for the remaining power conversion devices excluding the determined power conversion device, thereby sorting the updated multiple data sets in order of decreasing charge amount by (N×(N−1)) / 2 times the number of comparisons, where N is the number of the multiple power conversion devices; When the output direction of the active power is the charge direction, the conversion device determination unit compares the charge amounts of the two adjacent data sets in the priority list in order from the side with the highest priority or the side with the lowest priority, and rearranges the order of the two data sets as necessary so that the priority of the power conversion device with the lowest charge amount is increased. This process is performed once for each of the charge amounts of the power conversion device with the highest priority and the power conversion device with the lowest priority, thereby determining the power conversion device with the highest priority or the power conversion device with the lowest priority, and by repeating the same process for the remaining power conversion devices excluding the determined power conversion device, the plurality of data sets after update are rearranged in order of decreasing charge amount with the number of comparisons being (N × (N - 1)) / 2 times.

7. 7. The energy storage system according to claim 6, wherein the conversion device determination unit swaps the order of the two data sets when a difference between the charge amounts of two adjacent data sets is equal to or greater than a predetermined value when comparing the charge amounts of the two data sets.

8. 6. The energy storage system according to claim 5, wherein the conversion device determination unit compares the charge amounts of two adjacent data sets in the priority list in order from the side with the highest priority or the side with the lowest priority at each update period of the information about the state, and performs a process of switching the order of the two data sets as necessary, once for each of the plurality of data sets in the priority list.

9. A control device is connected to a plurality of power storage devices and a load, converts DC power stored in the plurality of power storage devices into power corresponding to the load, supplies power to the load based on the DC power stored in the plurality of power storage devices, converts power of the load into DC power corresponding to the plurality of power storage devices, and controls power conversion operations of a plurality of power conversion devices that charge the plurality of power storage devices based on power on the load side, an output value determination unit that determines a total value of active power and a total value of reactive power output from the plurality of power conversion devices; a converter determination unit that determines a power converter to which an operation command is to be transmitted from among the plurality of power converters; a command transmitting unit that transmits the operation command to the power electronics device determined by the converter determination unit and transmits a standby command to the remaining power electronics devices among the plurality of power electronics devices to which the operation command is not transmitted; Equipped with the converter determination unit has a priority list indicating priorities of the plurality of power converters, the priority list includes a plurality of data sets corresponding to each of the plurality of power electronics devices; the plurality of data sets store, in association with each other, priorities of the plurality of power electronics devices, identification information for identifying the plurality of power electronics devices, and information on states of the plurality of power storage devices and the plurality of power electronics devices; the converter determination unit determines the number of power electronics devices to which the operation command is to be transmitted, based on the total value of the active power and the total value of the reactive power determined by the output value determination unit and information about the states of the plurality of data sets, and determines the determined number of power electronics devices, among the plurality of power electronics devices, in descending order of priority in the priority list, as the power electronics devices to which the operation command is to be transmitted; the information on the state includes information on the charge amount of the power storage device, information on a dischargeable amount of the power storage device, information on a chargeable amount of the power storage device, information on a capacitive reactive power outputable amount of the power conversion device, and information on an inductive reactive power outputable amount of the power conversion device; The conversion device determination unit when the direction of output of the active power of the plurality of power electronics devices is a discharge direction for supplying power to the load, a calculation is performed to add up the dischargeable amounts of the power electronics devices in descending order of priority in the priority list, and the number of devices whose added value of the dischargeable amounts is equal to or greater than the total value of the active power determined by the output value determination unit is determined as the number of the power electronics devices required for the active power; when the direction of output of the active power of the plurality of power electronics devices is a charge direction in which the storage device is charged based on the power of the load, a calculation is performed to add up the chargeable amounts of the power electronics devices in descending order of priority in the priority list, and the number of devices whose added chargeable amounts are equal to or greater than the total value of the active power determined by the output value determination unit is determined as the number of the power electronics devices required for the active power; When the reactive power output from the plurality of power conversion devices is capacitive reactive power, a calculation is performed to add up the outputtable amounts of the capacitive reactive power in descending order of priority in the priority list, and the number of power conversion devices whose added outputtable amounts of the capacitive reactive power are equal to or greater than the total value of the reactive power determined by the output value determination unit is determined as the number of power conversion devices required for the reactive power; When the reactive power output from the plurality of power conversion devices is inductive reactive power, a calculation is performed to add up the outputtable amounts of the inductive reactive power in descending order of priority of the power conversion devices in the priority list, and the number of power conversion devices whose added outputtable amounts of the inductive reactive power are equal to or greater than the total value of the reactive power determined by the output value determination unit is determined as the number of power conversion devices required for the reactive power; A control device that compares the number of power conversion devices required for active power with the number of power conversion devices required for reactive power, and determines the larger number as the number of power conversion devices to send the operation command.

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