Control systems and management systems

Abstract

This reduces the possibility that the command values ​​distributed to each energy storage unit will be very small. [Solution] The control system 40 is a control system for controlling an energy storage system that adjusts the active power at the point of combination with the power grid by using a plurality of energy storage units, each including an energy storage device that discharges and charges DC power. The system comprises a command calculation unit 51 that calculates a total DC power command value Cp, which is the sum of the power that the energy storage devices in the plurality of energy storage units should discharge or charge; a command distribution unit 52 that calculates an active power distribution value P[m] from the total DC power command value Cp to be distributed to each of the plurality of energy storage units; and an operation instruction unit 53 that instructs each of the plurality of energy storage units to set the active power distribution value P[m] for that energy storage unit. The command distribution unit 52 distributes the power distribution value calculated for the first energy storage unit among the plurality of energy storage units to one or more energy storage units other than the first energy storage unit when the power distribution value calculated for the first energy storage unit among the plurality of energy storage units is within a first range.

Description

Technical Field

[0001] The present disclosure relates to a technique for controlling a plurality of power storage devices.

Background Art

[0002] For example, a technique for controlling a plurality of power storage devices according to a command value of power to be exchanged with a power system has been conventionally proposed. For example, Patent Document 1 discloses a configuration for controlling charging and discharging of each storage battery according to a command value based on a charging request or a discharging request in a storage battery system including a plurality of banks each composed of an AC-DC converter and a storage battery.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the command value for instructing charging or discharging of each power storage device is a non-zero numerical value that is sufficiently small (hereinafter referred to as "minute value"), problems such as inability to accurately measure the charge amount or discharge amount of each power storage device are assumed. In view of the above circumstances, one aspect of the present disclosure aims to reduce the possibility that the command value distributed to each power storage unit becomes a minute value.

Means for Solving the Problems

[0005] To solve the above problems, a control system according to one aspect of the present disclosure is a control system for controlling an energy storage system that adjusts power at a point of combination with a power system by a plurality of energy storage units, each including an energy storage device that discharges and charges DC power, comprising: a command calculation unit that calculates a total DC power command value which is the sum of the power that the energy storage devices in the plurality of energy storage units should discharge or charge; a command distribution unit that calculates a power distribution value to be distributed to each of the plurality of energy storage units from the total DC power command value; and an operation instruction unit that instructs each of the plurality of energy storage units on the power distribution value of the energy storage unit, wherein the command distribution unit distributes the power distribution value calculated for a first energy storage unit among the plurality of energy storage units to one or more energy storage units other than the first energy storage unit when the power distribution value calculated for a first energy storage unit among the plurality of energy storage units is a value within a first range.

[0006] A management system according to one aspect of the present disclosure comprises a power storage system that adjusts the active power at the point of combination with a power grid by a plurality of power storage units, each including a power storage device that discharges and charges DC power, and a control system that controls the power storage system, wherein the control system comprises a command calculation unit that calculates a total DC power command value which is the sum of the power that the power storage devices in the plurality of power storage units should discharge or charge, a command distribution unit that calculates a power distribution value to be distributed to each of the plurality of power storage units from the total DC power command value, and an operation instruction unit that instructs each of the plurality of power storage units on the power distribution value of the power storage unit, wherein the command distribution unit distributes the power distribution value calculated for the first power storage unit among the plurality of power storage units to one or more power storage units other than the first power storage unit when the power distribution value calculated for the first power storage unit among the plurality of power storage units is a value within a first range. [Brief explanation of the drawing]

[0007] [Figure 1] This is a block diagram illustrating the configuration of the management system according to the first embodiment. [Figure 2] This is a block diagram illustrating the configuration of a control system. [Figure 3] This is a block diagram illustrating the functional configuration of a control system. [Figure 4] This is an equivalent circuit diagram that virtually integrates multiple energy storage units. [Figure 5] This is a diagram illustrating the operation of the command calculation unit. [Figure 6] This is a diagram illustrating the operation of the command calculation unit. [Figure 7] This is a block diagram illustrating the configuration of the command distribution unit. [Figure 8] This is a specific example of how the distribution processing unit operates when the total DC power command value indicates discharge. [Figure 9] This is an explanatory diagram illustrating the relationship between the active power distribution value and the combined point power. [Figure 10] This is a specific example of how the distribution processing unit operates when the total DC power command value indicates charging. [Figure 11] This is an explanatory diagram illustrating the relationship between the active power distribution value and the combined point power. [Figure 12] This is a flowchart of the control process. [Figure 13] This is an explanatory diagram regarding the numerical range of the active power distribution value in the second embodiment. [Figure 14] This is a flowchart illustrating the operation of the command distribution unit in the second embodiment. [Figure 15] This is an explanatory diagram illustrating the specific procedure for the first restriction process. [Figure 16] This is an explanatory diagram showing the change in the limit value during the first limit processing. [Figure 17] This is an explanatory diagram illustrating the specific procedure for the second restriction processing. [Figure 18] This is an explanatory diagram showing the changes in the limit value during the second limit processing. [Figure 19] This is a diagram illustrating the temporal changes in power distribution values ​​and limit values. [Figure 20] This is a block diagram illustrating the configuration of the management system according to the third embodiment. [Figure 21] This is a block diagram illustrating the configuration of the management system according to the fourth embodiment. [Figure 22] It is a block diagram exemplifying the configuration of the power storage unit in the fifth embodiment.

Embodiments for Carrying Out the Invention

[0008] Embodiments for implementing the present disclosure will be described with reference to the drawings. The embodiments described below are exemplary embodiments assumed when implementing the present disclosure. Therefore, the scope of the present disclosure is not limited to the embodiments exemplified below.

[0009] 1. First Embodiment FIG. 1 is a block diagram exemplifying the configuration of a management system 100 according to the first embodiment. The management system 100 is a system that exchanges AC power with the power grid 10. The power grid 10 is, for example, a power distribution system or a power transmission system for supplying AC power generated by power generation equipment 23 (not shown), such as a thermal power plant or a nuclear power plant, to consumers such as business facilities or ordinary households. The management system 100 is connected to the power grid 10 at the integration point 11. The integration point 11 is a connection point corresponding to the boundary between the power grid 10 and the management system 100.

[0010] As illustrated in FIG. 1, the management system 100 includes a substation facility 21, a load facility 22, a power storage system 30, and a control system 40. The power storage system 30 is a power facility that exchanges AC power with the power grid 10.

[0011] The substation 21 is a power facility that aggregates the outputs of multiple energy storage units U[m] constituting the energy storage system 30 and the inputs of the load equipment 22, and transforms the voltage of the AC power exchanged between these and the combination point 11 using a transformer. Note that the transformer in the substation 21 may be omitted. The load equipment 22 consists of various loads (in-house loads) that operate by consuming power supplied from the energy storage system 30 or the power grid 10. For example, the load equipment 22 includes various equipment that supplies control power, operating power, or auxiliary power to each element of the management system 100 (substation 21, energy storage system 30, or control system 40). Specifically, examples of load equipment 22 include: an in-house transformer that transforms the voltage supplied from the substation 21; a DC power supply that supplies control power or operating power to the substation 21 or AC / DC converter 322; an uninterruptible power supply (UPS) that supplies power in the event of an abnormality; a power supply that supplies auxiliary power (e.g., driving power required for auxiliary equipment such as air conditioning equipment) or control power to the energy storage device 31; an oil pump or cooling fan used in the substation 21 or AC / DC converter 322; communication equipment used for security telephones with the power company, etc.; lighting equipment or air conditioning equipment installed on the premises or in buildings, etc.; a measurement system that measures environmental information such as temperature or humidity; or various fire-fighting equipment (smoke detectors, heat detectors, fire alarms, etc.). Note that load equipment 22 may be omitted.

[0012] The energy storage system 30 of the first embodiment is composed of a plurality of energy storage units U[m] (m=1 to 5). For convenience, in the following description, a configuration in which the energy storage system 30 includes five energy storage units U[1] to U[5] will be used as an example. However, the number of energy storage units U[m] constituting the energy storage system 30 can be arbitrarily changed.

[0013] Each of the multiple energy storage units U[m] is a power facility capable of charging and discharging electricity. As illustrated in Figure 1, each energy storage unit U[m] comprises an energy storage device 31 and a power adjustment device 32. The energy storage device 31 is a secondary battery that discharges and charges DC power. The type of energy storage device 31 is arbitrary, but examples include lithium-ion batteries and sodium-sulfur batteries.

[0014] The power conditioning device 32 is a PCS (Power Conditioning System) that controls the discharge and charging of the energy storage device 31. Specifically, the power conditioning device 32 comprises a transformer 321 and an AC / DC converter 322. The transformer 321 converts the voltage of the AC power. The AC / DC converter 322 converts between DC power and AC power. Specifically, the AC / DC converter 322 converts the DC power supplied by the discharge of the energy storage device 31 into AC power, and the transformer 321 converts the voltage of the AC power after conversion by the AC / DC converter 322 and supplies it to the combination point 11. The transformer 321 also converts the voltage of the AC power supplied from the power system 10, and converts the AC power after transformation by the transformer 321 into DC power and supplies it to the energy storage device 31. As described above, the energy storage system 30 adjusts the active power at the point of integration 11 with the power system 10 using multiple energy storage units U[m], including the energy storage device 31. The transformer 321 may be omitted. Alternatively, multiple energy storage units U[m] may share a single transformer 321.

[0015] The control system 40 is a computer system (PMS: ​​Power Management System) that controls the energy storage system 30. Specifically, the control system 40 instructs each energy storage unit U[m] of the energy storage system 30 to have an active power distribution value P[m]. Each energy storage unit U[m] causes the energy storage device 31 to discharge or charge DC power corresponding to the active power distribution value P[m]. The active power distribution value P[m] is the power value of AC power that the energy storage unit U[m] should discharge or charge. Specifically, a positive value of the active power distribution value P[m] corresponds to a command for discharge (i.e., power supply from the energy storage unit U[m] to the combination point 11), and a negative value of the active power distribution value P[m] corresponds to a command for charge (i.e., power reception from the combination point 11 by the energy storage unit U[m]). Alternatively, a negative value of the active power distribution value P[m] may correspond to a command for discharge, and a positive value of the active power distribution value P[m] may correspond to a command for charge.

[0016] Figure 2 is a block diagram illustrating the configuration of the control system 40. As illustrated in Figure 2, the control system 40 comprises a control device 41, a storage device 42, and a transmitting / receiving device 43. The control system 40 can be implemented as a single device or as a group of devices configured separately from each other.

[0017] The control device 41 consists of one or more processors that control each element of the control system 40. Specifically, the control device 41 is composed of one or more types of processors, such as a PLD (Programmable Logic Device), a CPU (Central Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit).

[0018] The storage device 42 is one or more memories that store programs executed by the control device 41 and data used by the control device 41. The storage device 42 is composed of known recording media, such as magnetic recording media or semiconductor recording media. The storage device 42 may be composed of a combination of multiple types of recording media. A portable recording media that can be attached to and detached from the control system 40 may be used as the storage device 42.

[0019] The transceiver 43 transmits and receives signals to and from external devices via wired or wireless means. Specifically, the transceiver 43 communicates with each energy storage unit U[m] (specifically, the power adjustment device 32) via a communication network (not shown), such as a dedicated line. For example, the active power distribution value P[m] is transmitted from the transceiver 43 to each energy storage unit U[m]. The signals exchanged between the transceiver 43 and each energy storage unit U[m] (specifically, the power adjustment device 32) may be either digital or analog signals.

[0020] Figure 3 is a block diagram illustrating the functional configuration of the control system 40. The control device 41 executes a program stored in the memory device 42 to realize multiple functions (command calculation unit 51, command distribution unit 52, operation instruction unit 53) for controlling multiple energy storage units U[m].

[0021] As illustrated in Figure 3, the control system 40 receives a basic command value C0. The basic command value C0 is the command value for the active power (hereinafter referred to as "combination point power") at the combination point 11 with the power system 10. In other words, the basic command value C0 is the total value of the power to be discharged or charged by the entire management system 100. In addition to indicating the numerical value of the combination point power, the basic command value C0 also indicates the direction of power (discharge / charge) to the combination point 11 by sign. Specifically, the power supply from the energy storage system 30 to the combination point 11 (i.e., discharge by the energy storage unit U[m]) is indicated by a positive number, and the power reception from the combination point 11 by the energy storage system 30 (i.e., charging by the energy storage unit U[m]) is indicated by a negative number.

[0022] The basic command value C0 is transmitted to the control system 40 from an external system that manages the electricity market, such as the wholesale electricity market or the supply and demand adjustment market. In other words, the basic command value C0 is the total value of electricity that the management system 100 should trade in various electricity markets.

[0023] The command calculation unit 51 in Figure 3 calculates the total DC power command value Cp from the basic command value C0. The total DC power command value Cp is a command value obtained by adding the power loss from the energy storage device 31 of each energy storage unit U[m] to the combination point 11 to the basic command value C0. Specifically, the total DC power command value Cp specifies the total value of DC power that each energy storage device 31 should generate so that the power at the combination point is maintained at the basic command value C0 even if there is a power loss from each energy storage device 31 to the combination point 11. In other words, the total DC power command value Cp is the total value of DC power that the energy storage devices 31 in multiple energy storage units U[m] should discharge or charge in order to realize the basic command value C0.

[0024] Figure 4 is an equivalent circuit diagram that virtually integrates multiple energy storage units U[m]. As illustrated in Figure 4, the energy storage devices 31 in multiple energy storage units U[m] are equivalently replaced by a single energy storage device 31eq, and the power regulators 32 in multiple energy storage units U[m] are equivalently replaced by a single power regulator 32eq.

[0025] As illustrated in Figure 4, the total DC power command value Cp calculated by the command calculation unit 51 is the total value of DC power that the energy storage device 31eq should discharge or receive. As can be understood from the above explanation, the total DC power command value Cp can also be expressed as a value obtained by equivalently converting the AC power to be set at the combination point 11 (i.e., the combination point power specified by the basic command value C0) into DC power generated by the energy storage device 31.

[0026] As illustrated in Figure 4, in the path from the energy storage device 31 of each energy storage unit U[m] to the synthesis point 11, transformation losses X1, load losses X2, and conversion losses X3 occur.

[0027] The substation loss X1 is the power loss caused by the voltage transformation by the substation equipment 21. In other words, the substation loss X1 is the loss (e.g., load loss and no-load loss) that occurs due to the voltage transformation between the AC voltage between the energy storage system 30 and the substation equipment 21 and the voltage at the combination point 11.

[0028] The substation loss X1 is calculated by adding the calculated copper loss that occurs in the transformer of the substation equipment 21 when power equivalent to the basic command value C0 passes through the combination point 11, and the iron loss that occurs in the transformer of the substation equipment 21 when voltage is applied to the substation equipment 21. Stray load loss or dielectric loss of the transformer in the substation equipment 21 may also be added to the substation loss X1. The substation loss X1 may also be calculated by the absolute difference between the power at the combination point 11 equivalent to the basic command value C0 (or the value measured by a power meter installed at the combination point 11) and the value measured by a meter installed at the input of the substation equipment 21. In addition, line loss between the energy storage system 30 and the substation equipment 21 may be added to the substation loss X1.

[0029] The load loss X2 is the power loss caused by the power consumption of the load equipment 22. In other words, the load loss X2 corresponds to the active power consumed by the load equipment 22. The load loss X2 is calculated, for example, according to the measured value measured by a measuring instrument. Alternatively, the load loss X2 may be calculated according to a pre-set planned value for the load equipment 22. In addition, line losses between the energy storage system 30 and the load equipment 22 may be added to the load loss X2.

[0030] The conversion loss X3 is the total power loss obtained by summing the conversion losses x[m] caused by the power adjustment device 32 in each energy storage unit U[m] across multiple energy storage units U[m]. The conversion loss x[m] in each energy storage unit U[m] is the loss that occurs due to the conversion between the DC power between the energy storage device 31 and the power adjustment device 32 and the AC power between the control system 40 and the substation equipment 21.

[0031] The conversion loss x[m] is the sum of the losses of the transformer 321 (e.g., load loss and no-load loss) and the AC / DC converter 322 in the energy storage unit U[m]. Line losses between the transformer 321 and the AC / DC converter 322 may also be added to the conversion loss x[m].

[0032] The loss of transformer 321 is calculated by adding the calculated copper loss of transformer 321 that occurs when power equivalent to the active power distribution value P[m] passes through transformer 321 to the iron loss of transformer 321 that occurs when voltage is applied to transformer 321. Stray load loss or dielectric loss of transformer 321 may also be added to the conversion loss x[m]. Alternatively, the loss of transformer 321 may be calculated by the absolute difference between the power equivalent to the active power distribution value P[m] input to transformer 321 (or the value measured by a power meter installed at the input of transformer 321) and the value measured by a power meter installed at the output of transformer 321.

[0033] The loss of the AC / DC converter 322 is calculated, for example, by the absolute difference between the active power distribution value P[m] (or the value measured by a power meter installed on the AC side of the AC / DC converter 322) and the measured value of the DC power.

[0034] Figures 5 and 6 are explanatory diagrams of the operation of the command calculation unit 51. Figure 5 shows the operation of the command calculation unit 51 when discharge by the energy storage system 30 is instructed by the basic command value C0 (C0>0). As illustrated in Figure 5, the command calculation unit 51 calculates the total DC power command value Cp by adding the power loss (X1+X2+X3), which includes the substation loss X1, load loss X2, and conversion loss X3, to the basic command value C0. In Figure 5, the conversion loss x[m] of each energy storage unit U[m] is "1", so the conversion loss X3 is "5" is illustrated as an example.

[0035] Figure 6 shows the operation of the command calculation unit 51 when charging by the energy storage system 30 is instructed by the basic command value C0 (C0 < 0). The basic command value C0 is a negative number, while the substation loss X1, load loss X2, and conversion loss X3 are positive numbers. Even when charging by the energy storage system 30 is instructed by the basic command value C0, the command calculation unit 51 calculates the total DC power command value Cp by adding the power loss (X1 + X2 + X3), which includes the substation loss X1, load loss X2, and conversion loss X3, to the basic command value C0, similar to the case in Figure 5.

[0036] In other words, the command calculation unit 51 calculates the total DC power command value Cp by adding the substation loss X1, load loss X2, and conversion loss X3 to the basic command value C0, as expressed by the following formula (1).

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[0037] The command distribution unit 52 in Figure 3 calculates the command value of active power (hereinafter referred to as "active power distribution value P[m]") that should be distributed to each of the multiple energy storage units U[m] from the total DC power command value Cp. The active power distribution value P[m] is the command value of AC power that each energy storage unit U[m] should discharge (P[m]>0) or charge (P[m]<0).

[0038] The operation instruction unit 53 instructs each of the multiple energy storage units U[m] to determine the active power distribution value P[m] for that energy storage unit U[m]. Specifically, the operation instruction unit 53 transmits the active power distribution value P[m] calculated by the command distribution unit 52 to the energy storage unit U[m] via the transceiver 43.

[0039] Figure 7 is a block diagram illustrating the specific configuration of the command distribution unit 52. As illustrated in Figure 7, the command distribution unit 52 comprises a coefficient setting unit 521, a limit value setting unit 522, and a distribution processing unit 523.

[0040] The coefficient setting unit 521 sets a distribution coefficient K[m] (K[1] to K[5]) for each of the multiple energy storage units U[m]. Each distribution coefficient K[m] is a positive number representing the ratio of the total DC power command value Cp that the energy storage unit U[m] should be responsible for. In the first embodiment, the coefficient setting unit 521 sets the distribution coefficient K[m] according to the specifications or state of each energy storage device 31, for example.

[0041] The limit value setting unit 522 sets limit values ​​L[m] (L[1] to L[5]) for each of the multiple energy storage units U[m]. Each limit value L[m] is a numerical value for limiting the active power distribution value P[m] to a predetermined range. The limit value L[m] includes a limit value L[m]_d (d:discharge) related to the discharge of the energy storage device 31 and a limit value L[m]_c (c:charge) related to the charging of the energy storage device 31. In the first embodiment, the limit value setting unit 522 sets the limit value L[m] according to the specifications or state of each energy storage device 31, for example.

[0042] The distribution processing unit 523 calculates the active power distribution value P[m] to be distributed to each energy storage unit U[m] from the total DC power command value Cp. In the first embodiment, the distribution processing unit 523 distributes the total DC power command value Cp to a plurality of active power distribution values ​​P[m] according to the distribution coefficient K[m] set by the coefficient setting unit 521 for each energy storage unit U[m] and the limit value L[m](L[m]_d, L[m]_c) set by the limit value setting unit 522 for each energy storage unit U[m].

[0043] Figures 8 to 11 are explanatory diagrams of the operation of the distribution processing unit 523. First, Figure 8 shows a specific example of the operation of the distribution processing unit 523 when the total DC power command value Cp indicates discharge (Cp > 0).

[0044] In step Sa1, the distribution processing unit 523 calculates the power distribution value Pa[m] to be distributed to each energy storage unit U[m] from the total DC power command value Cp, according to the distribution coefficient K[m] of each energy storage unit U[m]. Specifically, the distribution processing unit 523 calculates each power distribution value Pa[m] such that each power distribution value Pa[m] is a ratio corresponding to the distribution coefficient K[m].

[0045] For example, the distribution processing unit 523 calculates each power distribution value Pa[m] by the following formula (2). That is, the distribution processing unit 523 calculates each power distribution value Pa[m] by multiplying the ratio of each distribution coefficient K[m] to the sum of multiple distribution coefficients K[m] (K[1]~K[5]) ΣK[m] by the total DC power command value Cp of the discharge exemplified in Figure 5. As can be understood from the above explanation, according to the first embodiment, the total DC power command value Cp can be distributed to each of the multiple energy storage units U[m] according to the distribution coefficient K[m] of each energy storage unit U[m].

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[0046] The power distribution value Pa[m] calculated in step Sa1 may exceed the discharge limit value L[m]_d. When the total DC power command value Cp indicates discharge, the power distribution value Pa[m] exceeds the limit value L[m]_d if the power distribution value Pa[m] is greater than the limit value L[m]_d (Pa[m]>L[m]_d). For example, Figure 8 illustrates a case where the power distribution value Pa[1] (=50) of energy storage unit U[1] exceeds the limit value L[1]_d (=40), and the power distribution value Pa[2] (=40) of energy storage unit U[2] exceeds the limit value L[2]_d (=30).

[0047] The distribution processing unit 523 distributes the total excess value E1, which is the sum of the excess values ​​(Pa[m]-L[m]_d) for one or more energy storage units U[m] whose power distribution value Pa[m] exceeds the limit value L[m]_d, to each of the one or more energy storage units U[m] whose power distribution value Pa[m] does not exceed the limit value L[m]_d (Sa2~Sa5).

[0048] Specifically, in step Sa2 of Figure 8, the distribution processing unit 523 calculates the total excess value E1 by summing the difference between the power distribution value Pa[m] and the limit value L[m]_d (i.e., the excess value) for one or more energy storage units U[m] whose power distribution value Pa[m] exceeds the limit value L[m]_d. In the situation shown in Figure 8, the total excess value E1 is calculated as "20", which is the sum of the excess value of energy storage unit U[1] (Pa[1]-L[1]_d), "10", and the excess value of energy storage unit U[2] (Pa[2]-L[2]_d), "10".

[0049] In step Sa3, the allocation processing unit 523 calculates the total available power E2 by summing the difference (i.e., margin) between the limit value L[m]_d and the power allocation value Pa[m] for one or more of the multiple energy storage units U[m] whose power allocation value Pa[m] does not exceed the limit value L[m]_d. In the situation shown in Figure 8, the total available power E2 is calculated as "30", which is the sum of the margin value (L[4]_d-Pa[4]) of energy storage unit U[4], "10", and the margin value (L[5]_d-Pa[5]) of energy storage unit U[5], "20".

[0050] In step Sa4, the allocation processing unit 523 calculates an additional allocation value ΔP[m] for one or more energy storage units U[m] whose power allocation value Pa[m] does not exceed the limit value L[m]_d. Specifically, the allocation processing unit 523 calculates each additional allocation value ΔP[m] by performing the following calculation using formula (3a). That is, the allocation processing unit 523 calculates the additional allocation value ΔP[m] by multiplying the total excess value E1 by the ratio of each margin value (L[m]_d-Pa[m]) to the total available power E2.

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[0051] In step Sa5, the allocation processing unit 523 calculates the power allocation value Pb[m] for each energy storage unit U[m]. That is, each power allocation value Pa[m] is updated to the power allocation value Pb[m]. Specifically, for one or more energy storage units U[m] whose power allocation value Pa[m] exceeds the limit value L[m]_d, the allocation processing unit 523 sets the limit value L[m]_d as the updated power allocation value Pb[m]. In addition, for one or more energy storage units U[m] whose power allocation value Pa[m] does not exceed the limit value L[m]_d, the allocation processing unit 523 calculates the updated power allocation value Pb[m] by adding an additional allocation value ΔP[m] to the power allocation value Pa[m]. For energy storage units U[m] among multiple energy storage units U[m] where the power distribution value Pa[m] and the limit value L[m]_d are equal, the power distribution value Pa[m] is adopted as the power distribution value Pb[m]. The power distribution value Pb[m] is the command value of the DC power that the energy storage device 31 of each energy storage unit U[m] should discharge.

[0052] In step Sa6, the distribution processing unit 523 calculates the active power distribution value P[m] by subtracting the conversion loss x[m] in each energy storage unit U[m] from the power distribution value Pb[m] calculated for each energy storage unit U[m] (P[m]=Pb[m]-x[m]). In other words, the active power distribution value P[m] is the command value of the active power that the energy storage unit U[m] should discharge, as described above. The operation by which the distribution processing unit 523 calculates the active power distribution value P[m] when the total DC power command value Cp indicates discharge (Cp>0) is as described above.

[0053] As described above, between each energy storage unit U[m] and the combination point 11, a substation loss X1 due to the substation equipment 21 and a load loss X2 due to the load equipment 22 occur. As illustrated in Figure 9, the substation loss X1 and load loss X2 are reduced from the sum of the active power distribution values ​​P[m] calculated by the above procedure ΣP[m], and as a result, AC power equivalent to the basic command value C0 (=130) is supplied from the management system 100 to the combination point 11.

[0054] Figure 10 shows a specific example of the operation of the allocation processing unit 523 when the total DC power command value Cp indicates charging (Cp < 0).

[0055] In step Sa1, the distribution processing unit 523 calculates the power distribution value Pa[m] to be distributed to each energy storage unit U[m] from the total DC power command value Cp, according to the distribution coefficient K[m] of each energy storage unit U[m]. Specifically, the distribution processing unit 523 calculates each power distribution value Pa[m] such that each power distribution value Pa[m] is a ratio corresponding to the distribution coefficient K[m]. That is, as shown in formula (2) above, the distribution processing unit 523 calculates each power distribution value Pa[m] by multiplying the ratio of each distribution coefficient K[m] to the sum of multiple distribution coefficients K[m] (K[1]~K[5]) ΣK[m] by the total DC power command value Cp of charging exemplified in Figure 6.

[0056] The power distribution value Pa[m] calculated in step Sa1 may exceed the charging limit value L[m]_c. When the total DC power command value Cp indicates charging, the case where the power distribution value Pa[m] exceeds the limit value L[m]_c means the case where the power distribution value Pa[m] is less than the limit value L[m]_c (Pa[m]<L[m]_c). For example, in FIG. 10, the power distribution value Pa[4] (= -40) of the power storage unit U[4] exceeds the limit value L[4]_c (= -30), and the power distribution value Pa[5] (= -50) of the power storage unit U[5] exceeds the limit value L[5]_c (= -40) are illustrated cases.

[0057] The distribution processing unit 523 distributes the total excess value E1, which is the sum of the excess values (Pa[m] - L[m]_c), to each of one or more power storage units U[m] among the plurality of power storage units U[m] whose power distribution value Pa[m] exceeds the limit value L[m]_c (Sa2 to Sa5).

[0058] Specifically, in step Sa2 of FIG. 10, the distribution processing unit 523 calculates the total excess value E1 by summing the difference (i.e., the excess value) between the power distribution value Pa[m] and the limit value L[m]_c for one or more power storage units U[m] among the plurality of power storage units U[m] whose power distribution value Pa[m] exceeds the limit value L[m]_c. In the situation of FIG. 10, "-20", which is the sum of "-10", the excess value (Pa[4] - L[4]_c) of the power storage unit U[4], and "-10", the excess value (Pa[5] - L[5]_c) of the power storage unit U[5], is calculated as the total excess value E1.

[0059] In step Sa3, the allocation processing unit 523 calculates the total available power E2 by summing the difference (i.e., margin) between the limit value L[m]_c and the power allocation value Pa[m] for one or more energy storage units U[m] whose power allocation value Pa[m] does not exceed the limit value L[m]_c. In the situation shown in Figure 10, the total available power E2 is calculated as "-30", which is the sum of the margin value (L[1]_c-Pa[1]) of energy storage unit U[4], "-20", and the margin value (L[2]_c-Pa[2]) of energy storage unit U[2], "-10".

[0060] In step Sa4, the allocation processing unit 523 calculates an additional allocation value ΔP[m] for one or more energy storage units U[m] whose power allocation value Pa[m] does not exceed the limit value L[m]_c. Specifically, the allocation processing unit 523 calculates each additional allocation value ΔP[m] by performing the following calculation using formula (3b). That is, the allocation processing unit 523 calculates the additional allocation value ΔP[m] by multiplying the total excess value E1 by the ratio of each margin value (L[m]_c-Pa[m]) to the total available power E2.

number

[0061] In step Sa5, the allocation processing unit 523 calculates the power allocation value Pb[m] for each energy storage unit U[m]. That is, each power allocation value Pa[m] is updated to the power allocation value Pb[m]. Specifically, for one or more energy storage units U[m] whose power allocation value Pa[m] exceeds the limit value L[m]_c, the allocation processing unit 523 sets the limit value L[m]_c as the updated power allocation value Pb[m]. In addition, for one or more energy storage units U[m] whose power allocation value Pa[m] does not exceed the limit value L[m]_c, the allocation processing unit 523 calculates the updated power allocation value Pb[m] by adding an additional allocation value ΔP[m] to the power allocation value Pa[m]. For energy storage units U[m] among multiple energy storage units U[m] where the power distribution value Pa[m] and the limit value L[m]_c are equal, the power distribution value Pa[m] is adopted as the power distribution value Pb[m]. The power distribution value Pb[m] is the command value of the DC power that the energy storage device 31 of each energy storage unit U[m] should charge.

[0062] In step Sa6, the distribution processing unit 523 calculates the active power distribution value P[m] by subtracting the conversion loss x[m] in each energy storage unit U[m] from the power distribution value Pb[m] calculated for each energy storage unit U[m] (P[m]=Pb[m]-x[m]). In other words, the active power distribution value P[m] is the command value of the active power that the energy storage unit U[m] should charge, as described above. The operation by which the distribution processing unit 523 calculates the active power distribution value P[m] when the total DC power command value Cp indicates charging (Cp<0) is as described above.

[0063] As described above, between each energy storage unit U[m] and the combination point 11, a substation loss X1 due to the substation equipment 21 and a load loss X2 due to the load equipment 22 occur. As illustrated in Figure 11, the substation loss X1 and load loss X2 are reduced from the sum of the active power distribution values ​​P[m] calculated by the above procedure ΣP[m], and as a result, AC power equivalent to the basic command value C0 (=-170) is supplied from the combination point 11 to the management system 100.

[0064] Figure 12 is a flowchart of the overall operation of the control system 40 (hereinafter referred to as "control process"). For example, the control process in Figure 12 is repeated at a predetermined cycle.

[0065] When control processing begins, the control device 41 (command calculation unit 51) acquires the basic command value C0 (S1). The control device 41 (command calculation unit 51) calculates the total DC power command value Cp by adding power losses, including substation loss X1, load loss X2, and conversion loss X3, to the basic command value C0 (S2).

[0066] The control device 41 (command distribution unit 52) ​​calculates the active power distribution value P[m], which is the command value of the power to be distributed from the total DC power command value Cp to each of the multiple energy storage units U[m] (S3). A specific example of the process for calculating the active power distribution value P[m] is as described above with reference to Figures 8 and 10. The control device 41 (operation instruction unit 53) instructs each of the multiple energy storage units U[m] to have the active power distribution value P[m] for that energy storage unit U[m] (S4).

[0067] Furthermore, if the energy storage system 30 includes an energy storage unit U[m] that responds with DC power in response to a DC power command, the control device 41 (operation instruction unit 53) may instruct the energy storage unit U[m] to provide the power distribution value Pb[m] calculated for the energy storage unit U[m]. Also, if the energy storage system 30 includes an energy storage unit U[m] that responds with the active power at a point between the transformer 321 and the AC / DC converter 322 in response to an active power command at that point, the control device 41 (operation instruction unit 53) may instruct the energy storage unit U[m] to provide a value obtained by subtracting the loss of the transformer 321 in the energy storage unit U[m] from the power distribution value Pb[m] calculated for the energy storage unit U[m].

[0068] As explained above, in the first embodiment, the total DC power command value Cp is calculated by adding power losses, including the conversion loss X3 due to the conversion between DC power discharged or charged by the energy storage device 31 and AC power, and the transformation loss X1 due to the voltage transformation between the substation equipment 21 and the energy storage system 30, to the basic command value C0, and the total DC power command value Cp is allocated to each energy storage unit U[m]. Therefore, compared to an embodiment in which the basic command value C0 is allocated to each energy storage unit U[m] without considering the transformation loss X1 and the conversion loss X3, the effective power allocation value P[m] instructed to each energy storage unit U[m] can be calculated appropriately. When the basic command value C0 is small, the influence of the conversion losses (X1~X3) on the basic command value C0 increases relatively, so the configuration of the first embodiment in which the transformation loss X1 and the conversion loss X3 are taken into account in the basic command value C0 is particularly effective.

[0069] Furthermore, in the first embodiment, the total excess value E1, which is the sum of the excess values ​​of one or more energy storage units U[m] whose power distribution value Pa[m] exceeds the limit value L[m], is distributed to each of the one or more energy storage units U[m] whose power distribution value Pa[m] does not exceed the limit value L[m]. Therefore, while maintaining the combined point power at the basic command value C0, the power distributed to each energy storage unit U[m] can be suppressed to stay within the limit value L[m] range.

[0070] 2. Second Embodiment A second embodiment of this disclosure will now be described. For elements whose function is the same as in the first embodiment in each of the embodiments described below, the same reference numerals as in the first embodiment will be used, and detailed descriptions of each will be omitted as appropriate.

[0071] FIG. 13 is an explanatory diagram regarding the numerical range of the effective power distribution value P[m] in the second embodiment. As illustrated in FIG. 13, in the second embodiment, a first range R1 and a second range R2 (R2_d, R2_c) are defined in the numerical range of the effective power distribution value P[m]. The first range R1 is a range with a predetermined width including the numerical value 0. Specifically, the first range R1 is a range between the threshold value T1_d and the threshold value T1_c (T1_c ≦ P[m] ≦ T1_d). The threshold value T1_d is greater than the threshold value T1_c. The threshold value T1_d is a predetermined positive number indicating the discharge of the power storage unit U[m] (T1_d > 0) and corresponds to the upper limit value of the first range R1. On the other hand, the threshold value T1_c is a predetermined negative number indicating the charge of the power storage unit U[m] (T1_c < 0) and corresponds to the lower limit value of the first range R1.

[0072] The second range R2 is a range adjacent to the first range R1. Specifically, the second range R2 includes a discharge range R2_d and a charge range R2_c. The discharge range R2_d is a range adjacent to the positive side of the first range R1, and the charge range R2_c is a range adjacent to the negative side of the first range R1.

[0073] Specifically, the discharge range R2_d is a range between the aforementioned threshold value T1_d and a predetermined threshold value T2_d (T1_d < P[m] ≦ T2_d). The threshold value T2_d is a positive number greater than the threshold value T1_d (T2_d > T1_d) and corresponds to the upper limit value of the discharge range R2_d. The threshold value T1_d is the lower limit value of the discharge range R2_d. Note that the width |T2_d - T1_d| of the discharge range R2_d is smaller than the width |T1_d - T1_c| of the first range R1. However, a form in which the width of the discharge range R2_d is greater than the width of the first range R1, or a form in which the width of the discharge range R2_d is common to the width of the first range R1 is also assumed.

[0074] On the other hand, the charging range R2_c is a range (T2_c ≦ P[m] < T1_c) between the aforementioned threshold value T1_c and a predetermined threshold value T2_c. The threshold value T2_c is a negative number less than the threshold value T1_c (T2_c < T1_c) and corresponds to the lower limit value of the charging range R2_c. The threshold value T1_c is the upper limit value of the charging range R2_c. Note that the width |T1_c - T2_c| of the charging range R2_c is less than the width |T1_d - T1_c| of the first range R1. However, a form in which the width of the charging range R2_c exceeds the width of the first range R1 or a form in which the width of the charging range R2_c and the width of the first range R1 are the same is also assumed. Also, the width of the discharging range R2_d and the width of the charging range R2_c may be the same or different.

[0075] When the active power distribution value P[m] of each power storage unit U[m] is a positive or negative minute value, there is a problem that numerical values regarding states such as voltage or charge rate cannot be accurately measured for each power storage device 31. The first range R1 is a range including minute values in which the above problems can occur among the numerical ranges of the active power distribution value P[m]. That is, the first range R1 is expressed as a numerical range to be avoided in operation for the active power distribution value P[m].

[0076] FIG. 14 is a flowchart illustrating the operation of the command distribution unit 52 in the second embodiment. The process of FIG. 14 is executed in step S3 of the control process illustrated in FIG. 12.

[0077] The command distribution unit 52 first calculates a provisional power distribution value Pb[m] of each power storage unit U[m] by the same method as in the first embodiment (S31). Specifically, the command distribution unit 52 calculates an initial power distribution value Pa[m] of the power storage unit U[m] by distributing the total DC power command value Cp according to the distribution coefficient K[m] (Sa1), and calculates the power distribution value Pb[m] of each power storage unit U[m] by distributing the excess with respect to the limit value L[m] among the power distribution values Pa[m] to other power storage units U[m] (Sa2 to Sa5).

[0078] The command distribution unit 52 determines whether any of the multiple power distribution values ​​Pb[m] calculated for different energy storage units U[m] are within the first range R1 (S32). If any of the multiple power distribution values ​​Pb[m] are within the first range R1 (S32: YES), the command distribution unit 52 performs the first limiting process (S33). The first limiting process is the process of allocating the power distribution value Pb[m] that is within the first range R1 to the other power distribution values ​​Pb[m]. Details of the first limiting process will be described later.

[0079] On the other hand, if none of the multiple power distribution values ​​Pb[m] are within the first range R1 (S32:NO), the command distribution unit 52 determines whether any of the multiple power distribution values ​​Pb[m] are within the second range R2 (discharge range R2_d or charge range R2_c) (S34).

[0080] If any of the multiple power distribution values ​​Pb[m] is within the second range R2 (S34: YES), the command distribution unit 52 executes the second restriction process (S35). The second restriction process restricts the redistribution of power distribution values ​​Pb[m] that fall within the second range R2 from the other power distribution values ​​Pb[m]. Details of the second restriction process will be described later.

[0081] When the first limiting process (S33) or the second limiting process (S35) is executed, the command distribution unit 52 calculates the active power distribution value P [m] by subtracting the conversion loss x [m] from each power distribution value Pb [m] after each process, similar to step Sa6 illustrated in the first embodiment (S36).

[0082] Furthermore, if none of the multiple power distribution values ​​Pb[m] fall within the range R1 or the range R2 (S34:NO), the command distribution unit 52 calculates the active power distribution value P[m] by subtracting the conversion loss x[m] from the calculated power distribution value Pb[m] for each energy storage unit U[m] (S36). Once the active power distribution value P[m] for each energy storage unit U[m] has been calculated using the above procedure, the command distribution unit 52 terminates the process shown in Figure 14.

[0083] The specific procedures for the first and second restriction processes are described below. In the following explanation, we assume that the threshold T1_d for the first range R1 is 5, the threshold T1_c for the first range R1 is -5, the threshold T2_d for the second range R2 is 8, and the threshold T2_c for the second range R2 is -8, as illustrated in Figure 13.

[0084] [First restriction processing (S33)] Figure 15 is an explanatory diagram illustrating the specific procedure of the first limiting process. In Figure 15, it is assumed that the power distribution value Pb[5] of energy storage unit U[5] among multiple energy storage units U[m] is a value within the first range R1 (Pb[5]=5). In the following explanation, energy storage unit U[5] is an example of the "first energy storage unit".

[0085] When the first limiting process is initiated, the command distribution unit 52 changes the limit value L[5]_d of the energy storage unit U[5] to 0 (S331). That is, the command distribution unit 52 changes the limit value L[5]_d of the energy storage unit U[5] to 0 if the power distribution value Pb[m] calculated for the energy storage unit U[5] is a value within the first range R1.

[0086] Figure 16 is an explanatory diagram of the change in the limit value L[5]_d in the first limiting process. As illustrated in Figure 16, the command distribution unit 52 changes the limit value L[5]_d of the energy storage unit U[5] to 0 over time. That is, the command distribution unit 52 continuously changes the limit value L[5]_d from a default value to 0 from the start to the end of the period Ta on the time axis.

[0087] As a result of changing the limit value L[5]_d to 0, the calculated power distribution value Pb[m] for energy storage unit U[5] exceeds the limit value L[5]_d. Therefore, the command distribution unit 52 distributes the power distribution value Pb[5] for energy storage unit U[5] (i.e., the excess amount of the power distribution value Pb[5] relative to the limit value L[5]_d) to each energy storage unit U[m] (U[1] to U[4]) other than the energy storage unit U[5] (S332 to S335). The process of distributing the power distribution value Pb[5] to each energy storage unit U[m] is the same as the process from step Sa3 to step Sa5 in the first embodiment.

[0088] Specifically, in step S332, the command distribution unit 52 calculates the total excess value E1 by summing the difference (i.e., the excess value) between the power distribution value Pa[m] and the limit value L[m]_d for one or more energy storage units U[m] whose power distribution value Pb[m] exceeds the limit value L[m]_d. In the situation shown in Figure 15, among the multiple energy storage units U[m], only the power distribution value Pb[5] of energy storage unit U[5] whose limit value L[5]_d has been changed to 0 exceeds the limit value L[5]_d. Therefore, the power distribution value Pb[5] of energy storage unit U[5] is calculated as the total excess value E1 (E1=Pb[5]).

[0089] In step S333, the command distribution unit 52 calculates the total available power E2 by summing the difference (i.e., margin) between the limit value L[m]_d and the power distribution value Pb[m] for each of the multiple energy storage units U[m] (U[1] to U[4]) except for energy storage unit U[5].

[0090] In step S334, the command distribution unit 52 calculates an additional distribution value ΔP[m] for each energy storage unit U[m] (U[1] to U[4]) other than energy storage unit U[5]. Specifically, the command distribution unit 52 calculates each additional distribution value ΔP[m] by performing the following calculation using formula (3c). That is, the command distribution unit 52 calculates the additional distribution value ΔP[m] by multiplying the ratio of each margin value (L[m]_d-Pb[m]) to the total available power E2 by the total excess value E1 (power distribution value Pb[5] for energy storage unit U[5]). [Number]

[0091] In step S335, the command distribution unit 52 updates the power distribution value Pb[m] for each energy storage unit U[m]. Specifically, for one or more energy storage units U[m] whose power distribution value Pb[m] exceeds the limit value L[m]_d, the command distribution unit 52 sets the limit value L[m]_d as the updated power distribution value Pb[m]. For example, if the limit value L[5]_d is changed to 0, the power distribution value Pb[5] for energy storage unit U[5] is updated to 0.

[0092] Furthermore, the command distribution unit 52 calculates the updated power distribution value Pb[m] by adding an additional distribution value ΔP[m] to the power distribution value Pb[m] for one or more energy storage units U[m] whose power distribution value Pb[m] does not exceed the limit value L[m]_d. For energy storage units U[m] whose power distribution value Pb[m] and limit value L[m]_d are equal, the previously calculated power distribution value Pb[m] is maintained. The conversion loss x[m] is subtracted from each power distribution value Pb[m] calculated using the above procedure to calculate the effective power distribution value P[m] for each energy storage unit U[m] (S36).

[0093] As explained above, in the second embodiment, if the power distribution value Pb calculated for energy storage unit U[5] is a value within the first range R1, the power distribution value Pb[5] is distributed to one or more energy storage units U[m] (U[1] to U[4]). In other words, the power distribution value Pb[5] for energy storage unit U[5] is changed to 0. Therefore, the possibility that the power distribution value Pb[m] for each energy storage unit U[m] will be a non-zero minute value within the first range R1 can be reduced.

[0094] Furthermore, in the second embodiment, the limit value L[5]_d of the energy storage unit U[5] changes to 0 over time over a predetermined period of time. That is, discontinuous fluctuations of the limit value L[5]_d are suppressed. Therefore, the possibility of sudden fluctuations in the combined point power due to sharp fluctuations in the limit value L[5]_d of each energy storage unit U[5] can be reduced.

[0095] [Second restriction processing (S35)] Figure 17 is an explanatory diagram illustrating the specific procedure of the second limiting process. In Figure 17, it is assumed that the power distribution value Pb[5] of energy storage unit U[5] among the multiple energy storage units U[m] is a value within the discharge range R2_d in the second range R2 (Pb[5]=8). In the following explanation, energy storage unit U[5] is an example of the "second energy storage unit".

[0096] When the second limiting process is initiated, the command distribution unit 52 changes the limit value L[5]_d of the energy storage unit U[5] to the currently calculated power distribution value Pb[5] (S351). That is, the command distribution unit 52 changes the limit value L[5]_d of the energy storage unit U[5] to the calculated power distribution value Pb[5] if the calculated power distribution value Pb[5] for the energy storage unit U[5] is within the second range R2.

[0097] Figure 18 is an explanatory diagram illustrating the change in the limit value L[5]_d in the second limiting process. As illustrated in Figure 18, the command distribution unit 52 changes the limit value L[5]_d of the energy storage unit U[5] to the power distribution value Pb[5] over time. That is, the command distribution unit 52 continuously changes the limit value L[5]_d from a default value to the power distribution value Pb[5] from the start to the end of the period Tb on the time axis.

[0098] The command distribution unit 52 performs the same calculations as the first limiting process (S33): calculating the total excess value E1 (S352), calculating the total available power E2 (S353), calculating the additional distribution value ΔP [m] for each energy storage unit U [m] (S354), and updating the power distribution value Pb [m] for each energy storage unit U [m] (S355).

[0099] As described above, the limit value L[5]_d of the energy storage unit U[5] is changed to the power distribution value Pb[5], so the difference (i.e., margin) between the limit value L[5]_d and the power distribution value Pb[5] in the energy storage unit U[5] is 0. Therefore, the additional distribution value ΔP[5] for the energy storage unit U[5] is 0. In other words, no additional distribution (S355) is performed for the power distribution value Pb[m] that has already been calculated for the energy storage unit U[5]. As described above, in the second embodiment, the energy storage unit U[5] is excluded from the distribution target of the additional distribution value ΔP[m], so additional distribution for the energy storage unit U[5] can be suppressed.

[0100] Furthermore, in the second embodiment, the limit value L[5]_d of the energy storage unit U[5] changes over time to the power distribution value Pb[5] over a predetermined period of time. That is, discontinuous fluctuations of the limit value L[5]_d are suppressed. Therefore, the possibility of sudden fluctuations in the combined point power due to sharp fluctuations in the limit value L[5]_d of each energy storage unit U[5] can be reduced.

[0101] Figure 19 is an explanatory diagram illustrating the temporal changes of each value (Pb[5], L[5]_d) related to the energy storage unit U[5] described above. In Figure 19, the initial power distribution value Pb[5] before updating by the first or second limiting process is represented by the symbol Pb[5]_1, and the updated power distribution value Pb[5] is represented by the symbol Pb[5]_2.

[0102] In Figure 19, it is assumed that the power distribution value Pb[5]_1 before the update decreases over time to 0 within the range of a positive number over time up to time t3, and then increases over time within the range of a positive number from time t3 onward.

[0103] The power distribution value Pb[5]_1 reaches the threshold T2_d of the second range R2 at time t1, and thereafter decreases over time within the second range R2. Therefore, from time t1 onward, the limit value L[5]_d changes over time from the initial value L0 to the power distribution value Pb[5]_1. Note that the initial value L0 is the default value set before processing by the first or second limiting process.

[0104] The power distribution value Pb[5]_1 reaches the threshold T1_d of the first range R1 at time t2, and thereafter decreases over time within the first range R1. Therefore, from time t1 onward, the limit value L[5]_d changes over time from the value at time t2 (power distribution value Pb[m]_1) to 0. By setting the limit value L[5]_d to 0, the updated power distribution value Pb[m]_2 is maintained at 0.

[0105] The change in the power allocation value Pb[5]_1 reverses from decreasing to increasing at time t3. Then, at time t4, the power allocation value Pb[5]_1 reaches the threshold T1_d of the first range R1, and thereafter increases over time within the second range R2. Therefore, from time t4 onward, the limit value L[5]_d changes over time from the value at time t4 (=0) to the power allocation value Pb[5]_1. Due to the increase in the limit value L[5]_d, the power allocation value Pb[5]_2 changes over time to the power allocation value Pb[5]_1 before the update.

[0106] The power distribution value Pb[5]_1 before the update reaches the threshold T2_d of the second range R2 at time t5, and thereafter increases over time within the second range R2. Therefore, from time t5 onward, the limit value L[5]_d changes over time to the initial value L0.

[0107] As described above, according to the second embodiment, the possibility that the power distribution value Pb[m]_2 of each energy storage unit U[m] will be a small value within the first range R1 can be reduced. In the above explanation, it was assumed that the power distribution value Pb[m] is a positive number (discharge), but the same process is performed even when the power distribution value Pb[m] is a negative number (charge).

[0108] 3. Third Embodiment Figure 20 is a block diagram illustrating the configuration of the management system 100 according to the third embodiment. As illustrated in Figure 20, the management system 100 of the third embodiment includes a power generation facility 23 in addition to the same elements as the first embodiment (Figure 1) (substation equipment 21, load equipment 22, energy storage system 30, control system 40).

[0109] The power generation facility 23 is a distributed power source that generates electricity using renewable energy, for example. For example, any type of power generation system that utilizes renewable energy can be used as the power generation facility 23, such as a solar power generation system that converts solar energy into electricity, a wind power generation system that converts wind energy into electricity, a geothermal power generation system that converts geothermal energy into electricity, a hydroelectric power generation system that converts hydroelectric energy into electricity, or a biomass power generation system that converts biomass energy into electricity. The power generation facility 23 may also be composed of multiple power generation systems with different power generation methods.

[0110] In each of the above-described embodiments, the command calculation unit 51 calculates the total DC power command value Cp by adding the power loss (X1+X2+X3), which includes the substation loss X1, load loss X2, and conversion loss X3, to the basic command value C0, as shown in formula (1) above. In the third embodiment, the command calculation unit 51 calculates the total DC power command value Cp by adding the active power generated by the power generation equipment 23 (hereinafter referred to as "generated active power value Gc") to the power loss (X1+X2+X3) in addition to the basic command value C0. Specifically, the command calculation unit 51 calculates the total DC power command value Cp by performing a calculation that includes adding the power loss (X1+X2+X3) to the basic command value C0 and subtracting the generated active power value Gc, as shown in formula (4) below.

number

[0111] The configuration and operation for calculating the active power distribution value P[m] for each energy storage unit U[m] from the total DC power command value Cp are the same as in the embodiments described above. According to the third embodiment, even in an environment where power generation equipment 23 is installed in parallel with multiple energy storage units U[m], the combined point power can be maintained at the basic command value C0 with high accuracy.

[0112] 4. Fourth Embodiment Figure 21 is a block diagram illustrating the configuration of the management system 100 according to the fourth embodiment. As illustrated in Figure 21, the power adjustment device 32 in each energy storage unit U[m] of the fourth embodiment is a DC / DC converter that converts DC power to DC power of a different voltage value. That is, each energy storage unit U[m] of the fourth embodiment supplies or receives DC power. In the fourth embodiment, the conversion loss X3 applied to the calculation of the total DC power command value Cp includes a value obtained by summing the power loss caused by power conversion by the power adjustment device 32 across multiple energy storage units U[m].

[0113] As illustrated in Figure 21, an AC / DC converter 24 is installed between the substation 21 and the energy storage system 30. The AC / DC converter 24 is an AC / DC converter that converts DC power and AC power to each other. AC power is exchanged between the AC / DC converter 24 and the substation 21, and DC power is exchanged between the AC / DC converter 24 and each energy storage unit U[m]. In the above configuration, the substation loss X1 is the power loss caused by power conversion by the substation 21 and the AC / DC converter 24.

[0114] The management system 100 of the fourth embodiment includes load equipment 22a and load equipment 22b. Load equipment 22a is installed in parallel with a plurality of energy storage units U[m], similar to load equipment 22 of the first embodiment. Load equipment 22b is connected between the AC / DC converter 24 and the substation 21. The load loss X2 of the fourth embodiment is the sum of the power loss in load equipment 22a and the power loss in load equipment 22b.

[0115] In the fourth embodiment, as in the first embodiment, the command calculation unit 51 calculates the total DC power command value Cp by adding the power loss (X1+X2+X3), which includes the substation loss X1, load loss X2, and conversion loss X3, to the basic command value C0. The power generation equipment 23 of the third embodiment may also be added to the fourth embodiment. 5. Fifth Embodiment Figure 22 is a block diagram illustrating the configuration of each energy storage unit U[m] in the fifth embodiment. As illustrated in Figure 65, the energy storage unit U[m] of the fifth embodiment includes load equipment 33 in addition to the same elements as in the aforementioned embodiments (energy storage device 31, power adjustment device 32). The load equipment 33 consists of various loads that operate by consuming the power supplied from the power adjustment device 32. For example, the load equipment 33 is a power supply device that generates auxiliary power or control power used within the energy storage unit U[m].

[0116] In the fifth embodiment, the conversion loss x[m] of each energy storage unit U[m] includes the losses of the transformer 321 and the AC / DC converter 322 (and also line losses), plus the active power X31 of the load equipment 33 in the energy storage unit U[m]. That is, the conversion loss X3 in the fifth embodiment includes the sum of the active power X31 of the load equipment 33 in multiple energy storage units U[m]. The active power X31 of the load equipment 33 is measured, for example, by a measuring instrument (not shown) installed in each energy storage unit U[m].

[0117] 6. Variations The following are examples of specific modifications that may be added to each of the embodiments exemplified above. Two or more embodiments may be arbitrarily selected from the following examples and merged as appropriate, provided they do not contradict each other.

[0118] (1) In the second embodiment, an example was given in which the first range R1 and the second range R2 (R2_d, R2_c) are fixed ranges, but the first range R1 or the second range R2 may be variable ranges. For example, the control device 41 (command distribution unit 52) ​​controls the range width of the first range R1 or the second range R2 to be variable by changing each threshold (T1_d, T2_d, T1_c, T2_c) in Figure 12 in response to instructions from the administrator of the management system 100.

[0119] (2) In the second embodiment, an example was given in which the threshold T2_d exceeds the threshold T1_d. In this embodiment, a discharge range R2_d (second range R2) with a range width corresponding to the difference between the threshold T2_d and the threshold T1_d is secured. However, the threshold T2_d may be set to a value equal to the threshold T1_d. When the thresholds T2_d and T1_d are equal, the discharge range R2_d disappears (range width = 0). Therefore, the second limiting process caused by the power distribution value Pb[m] being a value within the discharge range R2_d is not performed.

[0120] In the second embodiment, a form in which the threshold value T2_c is lower than the threshold value T1_c is exemplified. In the above form, a charging range R2_c (second range R2) with a range width corresponding to the difference between the threshold value T1_c and the threshold value T2_c is ensured. However, the threshold value T2_c may be set to the same numerical value as the threshold value T1_c. When the threshold value T2_c and the threshold value T1_c are equal, the charging range R2_c disappears (range width = 0). Therefore, the second restriction process caused by the power distribution value Pb[m] being a numerical value within the charging range R2_c is not executed.

[0121] Furthermore, the threshold value T1_d, which is the upper limit value of the first range R1, and the threshold value T1_c, which is the lower limit value, may be set to the same numerical value. When the threshold value T1_d and the threshold value T1_c are equal, the first range R1 disappears (range width = 0). Therefore, the first restriction process caused by the power distribution value Pb[m] being a numerical value within the first range R1 is not executed.

[0122] As described in the above examples, in a state where each threshold value is set to a different numerical value (T2_c < T1_c < T1_d < T2_d), as exemplified in the second embodiment, the first restriction process and the second restriction process are executed according to the relationship between the first range R1 or the second range R2 (R2_d, R2_c) and the power distribution value Pb[m]. On the other hand, in a state where each threshold value is set to the same numerical value (T2_c = T1_c = T1_d = T2_d = 0), the first restriction process and the second restriction process are invalidated. As understood from the above description, the control device 41 (command distribution unit 52) operates in either the first operation mode (T2_c < T1_c < T1_d < T2_d) in which the first restriction process and the second restriction process are enabled or the second operation mode (T2_c = T1_c = T1_d = T2_d = 0) in which the first restriction process and the second restriction process are invalidated.

[0123] The operation mode of the control device 41 is selected, for example, according to an instruction from the administrator of the management system 100. When the first operation mode is instructed, the control device 41 activates the first limiting process and the second limiting process by setting each threshold value to different numerical values (T2_c < T1_c < T1_d < T2_d). On the other hand, when the second operation mode is instructed, the control device 41 deactivates the first limiting process and the second limiting process by setting each threshold value to equal numerical values (T2_c = T1_c = T1_d = T2_d = 0).

[0124] (3) Two or more embodiments selected from the plurality of embodiments exemplified above may be arbitrarily combined. The configurations exemplified in each of the above embodiments may be implemented without assuming the configurations of other embodiments.

[0125] (4) The functions of the control system 40 according to the above-described embodiment are realized, as described above, by the cooperation of one or more processors constituting the control device 41 and the program stored in the storage device 42. The programs exemplified above can be provided in a form stored in a computer-readable recording medium and installed on a computer. The recording medium is, for example, a non-transitory recording medium, and an optical recording medium (optical disk) such as a CD-ROM is a preferred example, but any known form of recording medium such as a semiconductor recording medium or a magnetic recording medium is also included. Note that the non-transitory recording medium includes any recording medium except a transitory, propagating signal, and a volatile recording medium is not excluded. Also, in a configuration where a distribution device distributes a program via a communication network, the recording medium storing the program in the distribution device corresponds to the non-transitory recording medium described above.

[0126] (5) The description of "the nth" (n is a natural number) in this application is used only as a formal and convenient identifier (label) for distinguishing each element in notation and has no substantial meaning. Therefore, there is no room for limited interpretation of the position or order of each element based on the notation of "the nth".

[0127] 7. Addendum From the forms exemplified above, the following configuration can be understood, for example.

[0128] A control system according to one aspect of the present disclosure (Aspect 1) is a control system for controlling an energy storage system that adjusts power at a point of combination with a power grid using a plurality of energy storage units, each including an energy storage device that discharges and charges DC power, comprising: a command calculation unit that calculates a total DC power command value which is the sum of the power that the energy storage devices in the plurality of energy storage units should discharge or charge; a command distribution unit that calculates a power distribution value to be distributed to each of the plurality of energy storage units from the total DC power command value; and an operation instruction unit that instructs each of the plurality of energy storage units on the power distribution value of the energy storage unit, wherein the command distribution unit distributes the power distribution value calculated for the first energy storage unit among the plurality of energy storage units to one or more energy storage units other than the first energy storage unit when the power distribution value calculated for the first energy storage unit is a value within a first range. In other words, the power distribution value of the first energy storage unit is changed to 0. Therefore, the possibility of the power distribution value of each energy storage unit becoming a very small value can be reduced.

[0129] In a specific example of Embodiment 1 (Embodiment 2), the command distribution unit sets a limit value for each of the plurality of energy storage units, and for one or more energy storage units whose power distribution value exceeds the limit value of that unit, the total excess value obtained by summing the excess values ​​is distributed to one or more energy storage units whose power distribution value does not exceed the limit value of that unit. If the power distribution value calculated for the first energy storage unit is within the first range, the limit value of the first energy storage unit is changed to 0. In the above embodiment, the power distributed to each energy storage unit can be suppressed to within the limit value range while maintaining the total DC power command value. Furthermore, for the first energy storage unit whose power distribution value is within the first range, the limit value is changed to 0, resulting in the power distribution value of the first energy storage unit being distributed to the other energy storage units. Therefore, the possibility of the power distribution value of each energy storage unit becoming a small value can be reduced.

[0130] In a specific example of Embodiment 2 (Embodiment 3), the command distribution unit changes the limit value of the first energy storage unit to 0 over time. In this embodiment, the limit value of the first energy storage unit changes to 0 over time over a predetermined period of time. That is, discontinuous fluctuations of the limit value are suppressed. Therefore, the possibility of sudden fluctuations in the active power at the composite point due to sharp fluctuations in the limit values ​​of each energy storage unit can be reduced.

[0131] In a specific example of Embodiment 2 or Embodiment 3 (Embodiment 4), the command distribution unit changes the limit value of the second energy storage unit to the power distribution value calculated for the second energy storage unit among the plurality of energy storage units if the calculated power distribution value is within the second range adjacent to the first range. In the above embodiment, since the limit value is changed to the power distribution value for the second energy storage unit whose power distribution value is within the second range among the plurality of energy storage units, the power distribution value of the second energy storage unit does not exceed the limit value. In other words, the second energy storage unit is excluded from the allocation of the excess power distribution value relative to the limit value of each energy storage unit. As described above, additional allocation to the second energy storage unit can be suppressed.

[0132] In a specific example of Embodiment 4 (Embodiment 5), the command distribution unit changes the limit value of the second energy storage unit to the power distribution value over time. In the above embodiment, the limit value of the second energy storage unit changes to the power distribution value over time over a predetermined period of time. That is, discontinuous fluctuations of the limit value are suppressed. Therefore, the possibility of sudden fluctuations in the active power at the composite point due to sharp fluctuations in the limit values ​​of each energy storage unit can be reduced.

[0133] In any specific example of Embodiments 1 to 5 (Embodiment 6), the command calculation unit calculates the total DC power command value by adding power losses, including conversion losses due to the conversion between DC power and AC power, and transformation losses due to the voltage transformation between the substation between the energy storage system and the synthesis point and the energy storage system, to the basic command value of the active power. In the above embodiments, the total DC power command value is calculated by adding power losses, including conversion losses due to the conversion between DC power discharged or charged by the energy storage device and AC power, and transformation losses due to the voltage transformation between the substation and the energy storage system (i.e., losses caused by the voltage transformation between the AC voltage between the energy storage system and the substation and the synthesis point voltage at the synthesis point), to the basic command value, and the total DC power command value is allocated to each energy storage unit. Therefore, compared to a configuration in which the basic command value is allocated to each energy storage unit without considering conversion losses between DC power and AC power, and substation losses between the energy storage system and substation equipment, the effective power allocation value instructed to each energy storage unit can be calculated appropriately. When the basic command value is small, the influence of conversion losses and substation losses on the basic command value increases relatively, so the configuration of this disclosure, in which conversion losses and substation losses are taken into account in the basic command value, is particularly effective.

[0134] A management system according to one aspect of the present disclosure (Aspect 7) comprises a power storage system that adjusts the active power at the point of combination with a power system by a plurality of power storage units, each including a power storage device that discharges and charges DC power, and a control system that controls the power storage system, wherein the control system comprises a command calculation unit that calculates a total DC power command value which is the sum of the power that the power storage devices in the plurality of power storage units should discharge or charge, a command distribution unit that calculates a power distribution value to be distributed to each of the plurality of power storage units from the total DC power command value, and an operation instruction unit that instructs each of the plurality of power storage units on the power distribution value of the power storage unit, wherein the command distribution unit distributes the power distribution value calculated for the first power storage unit among the plurality of power storage units to one or more power storage units other than the first power storage unit when the power distribution value calculated for the first power storage unit among the plurality of power storage units is a value within a first range. [Explanation of Symbols]

[0135] 100...Management system, 10, 10a, 10b...Power system, 11, 11a, 11b...Combination point, 21, 21a, 21b...Substation equipment, 22, 22a, 22b...Load equipment, 23...Power generation equipment, 24...AC / DC converter, 30...Energy storage system, 31...Energy storage device, 32...Control device, 33...Load equipment, 321...Transformer, 322...AC / DC converter, 40...Control system, 41...Control device, 42...Memory device, 43...Transmitting / receiving device, 51...Command calculation unit, 52...Command distribution unit, 521...Coefficient setting unit, 522...Limit value setting unit, 523...Distribution processing unit, 53...Operation instruction unit.

Claims

1. A control system for controlling an energy storage system that adjusts power at the point of integration with a power grid by using multiple energy storage units, including energy storage devices that discharge and charge DC power, A command calculation unit that calculates a total DC power command value which is the sum of the power to be discharged or charged by the energy storage devices in the plurality of energy storage units, A command distribution unit calculates the power distribution value to be distributed to each of the plurality of energy storage units from the total DC power command value, The system comprises an operation instruction unit that instructs each of the plurality of energy storage units on the power distribution value of said energy storage unit, The command distribution unit, when the power distribution value calculated for the first energy storage unit among the plurality of energy storage units is within a first range, distributes the power distribution value to one or more energy storage units other than the first energy storage unit among the plurality of energy storage units. Control system.

2. The command distribution unit, A limit value is set for each of the aforementioned multiple energy storage units. For one or more of the aforementioned energy storage units whose power distribution value exceeds the limit value of that unit, the total excess value obtained by summing the excess values ​​is distributed to each of the one or more of the aforementioned energy storage units whose power distribution value does not exceed the limit value of that unit. If the power distribution value calculated for the first energy storage unit is within the first range, the limit value for the first energy storage unit is changed to 0. The control system according to claim 1.

3. The command distribution unit changes the limit value of the first energy storage unit to 0 over time. The control system of claim 2.

4. The command distribution unit, If the power distribution value calculated for the second energy storage unit among the plurality of energy storage units is a value within the second range adjacent to the first range, the limit value of the second energy storage unit is changed to that power distribution value. The control system of claim 2.

5. The command distribution unit changes the limit value of the second energy storage unit to the power distribution value over time. The control system according to claim 4.

6. The command calculation unit calculates the total DC power command value by adding power losses, including conversion losses due to the conversion between DC power and AC power, and transformation losses due to the voltage transformation between the energy storage system and the substation equipment between the power storage system and the point of convergence, to the basic command value of the active power. The control system according to claim 1.

7. A power storage system that adjusts the active power at the point of integration with the power grid by using multiple power storage units, including power storage devices that discharge and charge DC power, The system comprises a control system for controlling the aforementioned energy storage system, The control system is A command calculation unit that calculates a total DC power command value which is the sum of the power to be discharged or charged by the energy storage devices in the plurality of energy storage units, A command distribution unit calculates the power distribution value to be distributed to each of the plurality of energy storage units from the total DC power command value, The system comprises an operation instruction unit that instructs each of the plurality of energy storage units on the power distribution value of said energy storage unit, The command distribution unit, when the power distribution value calculated for the first energy storage unit among the plurality of energy storage units is within a first range, distributes the power distribution value to one or more energy storage units other than the first energy storage unit among the plurality of energy storage units. Management system.

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