Control method, control system, and program for energy storage devices

Abstract

Make effective use of energy storage devices. [Solution] The control system 30 includes an information acquisition unit 51 that acquires the health status H(t) of the energy storage device at a target point in time within the operating period, and a calculation processing unit 52 that calculates a second value according to the health status H(t) of the energy storage device so that the capacity degradation of the energy storage device expected at the end of the operating period does not exceed an allowable value when the number of operating cycles of the energy storage device increases from a first value to a second value at the target point in time.

Description

Technical Field

[0001] The present disclosure relates to a technique for controlling a power storage device.

Background Art

[0002] Techniques for exchanging power with a power grid through discharging and charging of a power storage device have been proposed conventionally. For example, Patent Document 1 discloses a configuration in which the power discharged and charged by each battery system is controlled so that deterioration is equalized across a plurality of battery systems. Patent Document 2 discloses a configuration in which an integrated capacity is calculated according to capacity maintenance rate data up to the life of a battery and the rated capacity of the battery, and a charging control voltage is determined according to the integrated capacity.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The state of health (SOH) of a power storage device deteriorates over time during operation. At the design stage of a power storage device, it is assumed that the power storage device is operated so that the state of health reaches a predetermined allowable value when a predetermined operation period ends. However, for example, from the viewpoint of ensuring a margin in the state of health of the power storage device, the number of operation cycles is suppressed, and as a result, in practice, the operation period may end with a sufficient margin in the state of health up to the allowable value. If the power storage device can be utilized more effectively during the operation period, there is a possibility of further expecting benefits from power exchange with the power grid. In view of the above circumstances, one aspect of the present disclosure aims to effectively utilize a power storage device.

Means for Solving the Problems

[0005] To solve the above problems, a control method for an energy storage device according to one aspect of the present disclosure includes a control system that acquires the health status of the energy storage device at a target point in time within the operating period, and calculates a second value according to the health status of the energy storage device so that the capacity degradation of the energy storage device expected at the end of the operating period does not exceed an allowable value when the number of operating cycles of the energy storage device increases from a first value to a second value at the target point in time.

[0006] A control system according to one aspect of the present disclosure comprises an information acquisition unit that acquires the health status of the energy storage device at a target point in time within the operating period, and a calculation processing unit that calculates the second value according to the health status of the energy storage device so that the capacity degradation of the energy storage device expected at the end of the operating period does not exceed an allowable value when the number of operating cycles of the energy storage device increases from a first value to a second value at the target point in time.

[0007] A program according to one aspect of this disclosure causes a computer system to function as an information acquisition unit that acquires the health status of the energy storage device at a target point in time within the operating period, and a calculation processing unit that calculates the second value according to the health status of the energy storage device so that the capacity degradation of the energy storage device expected at the end of the operating period does not exceed an allowable value when the number of operating cycles of the energy storage device increases from a first value to a second value at the target point in time. [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram illustrating the configuration of a power system according to the first embodiment. [Figure 2] This is a block diagram illustrating the configuration of a control system. [Figure 3] This shows the time variation of the State of Health (SOH) of the energy storage device. [Figure 4] This is an explanatory diagram showing the time evolution of the total number of cycles M and the state of charge (SOC). [Figure 5]This is a block diagram illustrating the functional configuration of a control system. [Figure 6] This is a schematic diagram of reference image G1. [Figure 7] This is a flowchart of the management process. [Figure 8] This graph shows the relationship between the number of operation cycles N and the ratio α(N) in the second embodiment. [Figure 9] This is a flowchart of the management process in the second embodiment. [Figure 10] This is a flowchart of the management process in the third embodiment. [Figure 11] This is a schematic diagram of reference image G2. [Modes for carrying out the invention]

[0009] The embodiments for implementing this disclosure will be described with reference to the drawings. The embodiments described below are exemplary embodiments that may be envisioned when implementing this disclosure. Therefore, the scope of this disclosure is not limited to the embodiments described below.

[0010] 1. First Embodiment Figure 1 is a block diagram illustrating the configuration of a power system 100 according to the first embodiment of this disclosure. The power system 100 is a system that exchanges power (AC power) with a power grid 10. The power grid 10 is a distribution or transmission system for supplying power generated by power generation facilities (not shown), such as a thermal power plant or a nuclear power plant, to business facilities or consumers such as ordinary households.

[0011] As illustrated in Figure 1, the power system 100 comprises a power storage system 20 and a control system 30. The power storage system 20 is a power facility capable of discharging (i.e., supplying power to the power grid 10) and charging (receiving power from the power grid 10). The power system 100 may include multiple power storage systems 20. In a configuration in which the power system 100 includes multiple power storage systems 20, the configurations and operations illustrated below are adopted for each power storage system 20.

[0012] The power storage system 20 includes a power storage device 21, an adjustment device 22, and a voltage conversion device 23. The power storage device 21 is a system power storage battery that discharges and charges DC power. The type of the power storage device 21 is arbitrary. For example, a secondary battery such as a lithium-ion battery or a sodium-sulfur battery is exemplified as the power storage device 21. Note that the power storage device 21 may be composed of a plurality of power storage batteries.

[0013] The adjustment device 22 is a PCS (Power Conditioning System) that controls the discharge and charge of the power storage device 21. Specifically, the adjustment device 22 is a power conversion device that mutually converts the DC power that the power storage device 21 discharges or charges and the AC power that the voltage conversion device 23 converts. The voltage conversion device 23 converts the voltage of the AC voltage.

[0014] The control system 30 is a computer system (PMS: Power Management System) that controls the power storage system 20 (power storage device 21). Specifically, the control system 30 commands the power storage system 20 with the power value of the power that the power storage device 21 should discharge or charge (hereinafter referred to as "individual command value B"). The adjustment device 22 of the power storage system 20 causes the power storage device 21 to execute the discharge or charge of the DC power corresponding to the individual command value B. As described above, the control system 30 controls the power storage device 21 (power storage system 20).

[0015] FIG. 2 is a block diagram illustrating the configuration of the control system 30. As illustrated in FIG. 2, the control system 30 includes a control device 31, a storage device 32, a display device 33, and a communication device 34. Note that the control system 30 is realized by a single device or by a plurality of devices separately configured from each other.

[0016] The control device 31 is composed of one or more processors that control each element of the control system 30. Specifically, for example, the control device 31 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).

[0017] The storage device 32 is one or more memories that store the programs executed by the control device 31 and the data used by the control device 31. The storage device 32 is composed of a known recording medium such as a magnetic recording medium or a semiconductor recording medium. The storage device 32 may be composed of a combination of multiple types of recording media. A portable recording medium that is detachable from the control system 30 may be used as the storage device 32.

[0018] The display device 33 displays various images under the control of the control device 31. The display device 33 is composed of a display panel such as a liquid crystal panel or an organic EL (Electroluminescence) panel.

[0019] The communication device 34 transmits and receives signals to and from an external device by wire or wirelessly. For example, the communication device 34 communicates with the management system 40 in FIG. 1. The management system 40 is a computer system (EMS: Energy Management System) that manages power transactions in various power markets such as the wholesale power market or the demand-supply adjustment market. The communication device 34 receives the power command value A transmitted from the management system 40. The power command value A is the total value of the power to be exchanged with the power grid 10. The control system 30 calculates an individual command value B according to the power command value A and transmits the individual command value B to the energy storage system 20. Note that the management system 40 may be interpreted as an element of the power grid 100.

[0020] The communication device 34 communicates with the energy storage system 20 (specifically the adjustment device 22) via a communication network (not shown), such as a dedicated line. Specifically, the communication device 34 transmits an individual command value B to the energy storage system 20. The communication device 34 also receives the health status H(t) of the energy storage device 21 from the energy storage system 20. The health status H(t) is the ratio of the power capacity of the energy storage device 21 at any given time t to its initial power capacity. The health status H(t) is measured, for example, by a charge-discharge test during maintenance work (e.g., repair or replacement) of the energy storage device 21 and transmitted from the energy storage system 20 to the control system 30. For example, the health status H(t) is measured for each maintenance operation performed annually. Alternatively, in a configuration where the health status H(t) measured by the charge-discharge test is stored in the memory device 32, the control device 31 may obtain the health status H(t) from the memory device 32.

[0021] Figure 3 shows the time variation of the health condition H(t) of the energy storage device 21. The operating period P in Figure 3 is the period during which the energy storage device 21 is expected to be used. Specifically, the operating period P is a predetermined length (e.g., 20 years) from the start of operation t0 to the end of operation T on the time axis. The start of operation t0 is the time when the operation of the energy storage device 21 begins. The end of operation T is the time when the operating period P expires. Upon arrival of the end of operation T (i.e., the end of the operating period P), for example, the energy storage device 21 will be replaced.

[0022] As illustrated in Figure 3, the health status H(t) of the energy storage device 21 decreases over time during operation, with the value H(t0) at the start of operation t0 of the operating period P being its maximum value Hmax. The maximum value Hmax is, for example, 100%. In the design of the energy storage device 21, it is assumed that the health status H(t) changes over time so that it reaches its minimum value Hmin at the end of the operating period P T (H(T) = Hmin), as illustrated in Figure 3 as a hypothetical time change Vref. The minimum value Hmin of the health status H(t) is, for example, 70%.

[0023] However, the actual time variation V of the health level H(t) is influenced by various factors such as the operating method or installation environment of the energy storage device 21. Therefore, the actual time variation V of the health level H(t) differs from the design time variation Vref. Specifically, as illustrated in Figure 3, the health level H(t) may exceed the minimum value Hmin at the end of the operating period P T (H(T)>Hmin). In other words, the operating period P may end with sufficient margin remaining before the minimum value Hmin for the health level H(t). If the energy storage device 21 can be utilized more effectively within the operating period P, it will be possible to expect further revenue from power exchange with the power grid 10.

[0024] Taking the above circumstances into consideration, the control system 30 of the first embodiment increases the number of operating cycles N of the energy storage device 21 at an intermediate point within the operating period P, when it is expected that the health level H(t) will not reach the minimum value Hmin at the end of the operating period P, thereby bringing the time change V of the health level H(t) closer to the design time change Vref.

[0025] The number of operational cycles N is the upper limit of the number of discharge and charge cycles of the energy storage device 21 within a unit period (e.g., one day). In other words, the number of operational cycles N means the upper limit of the number of times the discharge and charge pair is repeated within a unit period. Specifically, the number of operational cycles N is the equivalent or virtual number (equivalent cycle count) obtained by converting the discharge and charge (charge depth) in a portion of the interval from the minimum to the maximum value of the State of Charge (SOC) into a set of charges from the minimum to the maximum value of the SOC and discharges from the maximum to the minimum value of the SOC, with each set being counted as one cycle.

[0026] Figure 4 is an explanatory diagram illustrating the time evolution of the total number of cycles M and the state of charge (SOC). The total number of cycles M is the sum of the number of cycles during the operation of the energy storage device 21. Figure 4 illustrates the time evolution of the total number of cycles M and the state of charge when the number of operating cycles N is set to the value N1, and when the number of operating cycles N is set to the value N2. The value N2 of the number of operating cycles N is greater than the value N1. For example, if the value N1 is set to "1" and the value N2 is set to "1.2".

[0027] As illustrated in Figure 4, the total number of cycles M when the number of operating cycles N is set to the value N2 exceeds the total number of cycles M when the number of operating cycles N is set to the value N1. Furthermore, the number of SOC fluctuations when the number of operating cycles N is set to the value N2 exceeds the number of SOC fluctuations when the number of operating cycles N is set to the value N1. Therefore, the revenue that the administrator (e.g., a power seller) can obtain through power trading using the energy storage device 21 with the number of operating cycles N set to the value N2 exceeds the revenue that can be obtained when the number of operating cycles N is set to the value N1. In other words, it is possible to increase the administrator's revenue by increasing the number of operating cycles N within the operating period P.

[0028] Figure 5 is a block diagram illustrating the functional configuration of the control system 30. The control device 31 implements multiple functions (information acquisition unit 51, arithmetic processing unit 52, display control unit 53) for controlling the energy storage system 20 by executing a program stored in the memory device 32.

[0029] The information acquisition unit 51 acquires the health status H(X) of the energy storage device 21 at a specific point in time t (hereinafter referred to as "target point in time X") within the operating period P. Specifically, the information acquisition unit 51 receives the health status H(X) transmitted from the energy storage system 20 via the communication device 34. The information acquisition unit 51 may also calculate the health status H(X) using the information received from the energy storage system 20. Furthermore, in a configuration where the health status H(t) measured by a charge / discharge test during maintenance work is stored in the storage device 32, the information acquisition unit 51 may acquire the health status H(X) at target point in time X from the storage device 32 when executing the management process described later (Figure 7). As illustrated above, the acquisition of the health status H(X) by the information acquisition unit 51 includes, for example, the calculation of the health status H(X) and the reading of the health status H(X) from the storage device 32, in addition to receiving the health status H(X) via the communication device 34.

[0030] The arithmetic processing unit 52 calculates a numerical value N2 for the number of operating cycles N according to the health status H(X) of the energy storage device 21 acquired by the information acquisition unit 51. The numerical value N2 is the numerical value of the number of operating cycles N that should be applied to the operation of the energy storage device 21 from the target time point X onward within the operating period P. In other words, the number of operating cycles N of the energy storage device 21 is updated from the default numerical value N1 to the numerical value N2 at the target time point X. The calculation of the numerical value N2 by the arithmetic processing unit 52 is described in detail below.

[0031] In Figure 3, the capacity degradation D(t) represents the decrease in capacity of the energy storage device 21. Specifically, the capacity degradation D(t) is the difference between the health level H(t0) (=Hmax) at the start of operation t0 of the operating period P and the health level H(t) at time t, as expressed by the following formula (1). Figure 3 illustrates the capacity degradation D(T) at the end of the operating period P T and the capacity degradation D(X) at the target time X.

number

[0032] As illustrated in Figure 3, the capacity degradation D(t) at any point t within the operating period P includes the cycle degradation Dc(t) and the storage degradation Ds(t). Specifically, the capacity degradation D(t) is the sum of the cycle degradation Dc(t) and the storage degradation Ds(t) (D(t) = Dc(t) + Ds(t)). The cycle degradation Dc(t) of the energy storage device 21 is expressed by the following formula (2), and the storage degradation Ds(t) is expressed by the following formula (3).

number

[0033] In equation (2), the symbol α represents the ratio of cycle degradation Dc(t) to capacity degradation D(t), and is set to a predetermined value between 0 and 1. Similarly, in equation (3), the symbol (1-α) represents the ratio of storage degradation Ds(t) to capacity degradation D(t), and is set to a predetermined value between 0 and 1.

[0034] The cycle degradation Dc(t) within the capacity degradation D(t) is the decrease in health H(t) caused by repeated discharge and charging by the energy storage device 21. In other words, cycle degradation Dc(t) is the degradation of power capacity that depends on the number of operating cycles N (or the total number of cycles M). Specifically, cycle degradation Dc(t) is proportional to the square root of the total number of cycles M at time t. Therefore, the cycle degradation Dc(X) at the target time X within the operating period P is expressed by the following formula (4).

number

[0035] The target time point X is expressed as a numerical value in years. Therefore, the interior of the square root (N1·365·X) in equation (4) represents the total number of cycles M when the energy storage device 21 is operated by the number of operation cycles N, which is the numerical value N1, during the period from the start of operation t0 (t=0) to the target time point X. The symbol C1 in equation (4) is the proportionality constant. By manipulating equation (4), the following equation (5) is derived to express the proportionality constant C1.

number

[0036] On the other hand, storage degradation Ds(t) of capacity degradation D(t) is a decrease in the health H(t) of the energy storage device 21 that progresses over time regardless of discharge and charge. In other words, storage degradation Ds(t) is a degradation of power capacity that does not depend on the number of operating cycles N (or total number of cycles M). Specifically, storage degradation Ds(t) is proportional to the square root of the operating time (storage days) of the energy storage device 21. Therefore, the storage degradation Ds(X) at the target time X within the operating period P is expressed by the following formula (6).

number

[0037] In equation (6), the interior of the square root (365·X) represents the number of days from the start of operation t0 (t=0) to the target time X. The symbol C2 in equation (6) is the proportionality constant. By manipulating equation (6), the following equation (7) is derived to express the proportionality constant C2.

number

[0038] As mentioned above, assuming that the number of operational cycles N increases from N1 to N2 at point X in the operational period P, the cycle degradation Dc(T) at the end of the operational period P is expressed by the following formula (8).

number

[0039] In equation (8), the first term inside the square root (N1·365·X) represents the total number of cycles M when the energy storage device 21 is operated with the number of operation cycles N specified by the numerical value N1 during the period from the start of operation t0 to the target time X within the operating period P. Similarly, the second term inside the square root in equation (8) (N2·365·(TX)) represents the total number of cycles M when the energy storage device 21 is operated with the number of operation cycles N specified by the numerical value N2 during the period from the target time X to the expiration time T (time length: TX) within the operating period P. In other words, the inside of the square root in equation (8) corresponds to the total number of cycles M over the entire operating period P.

[0040] Furthermore, the storage degradation Ds(T) at the end of the operating period P, time T, is expressed by the following formula (9).

number

[0041] The capacity degradation D(T) at the end of the operating period P is the expected decrease in the power capacity of the energy storage device 21 at the end of the operating period P T, assuming that the number of operating cycles N of the energy storage device 21 increases from a value N1 to a value N2 at the target time X. As expressed by the following formula (10), the capacity degradation D(T) at the end of the period T must not exceed a predetermined allowable value Dmax.

number

[0042] The allowable value Dmax, as illustrated in Figure 3, represents the capacity degradation D(T) at the expiration point T in the design time variation Vref of the health condition H(t) of the energy storage device 21. In other words, the allowable value Dmax is the difference between the health condition H(t0) (i.e., the maximum value Hmax) at the start of operation t0 of the operating period P and the health condition H(T) (i.e., the minimum value Hmin) at the expiration point T in the design time variation Vref (Dmax = Hmax - Hmin).

[0043] From the condition in equation (10) that the capacity degradation D(T), which is the sum of the cycle degradation Dc(T) in equation (8) to which the proportionality constant C1 in equation (5) is applied, and the storage degradation Ds(T) in equation (9) to which the proportionality constant C2 in equation (7) is applied, does not exceed the allowable value Dmax, the following equation (11) is derived, which represents the condition that the numerical value N2 after changing the number of operating cycles N must satisfy.

number

[0044] The arithmetic processing unit 52 in Figure 5 calculates the maximum value that satisfies formula (11) as the value N2 after changing the number of operating cycles N. In other words, the arithmetic processing unit 52 calculates the value N2 according to the health H(X) of the energy storage device 21 so that the capacity degradation D(T) of the energy storage device 21 expected at the end of the operating period P T does not exceed the allowable value Dmax when the number of operating cycles N of the energy storage device 21 increases from value N1 to value N2 at the target time X. Specifically, the arithmetic processing unit 52 calculates the value N2 of the number of operating cycles N so that the sum of the cycle degradation Dc(T) at the end of the operating period P T and the storage degradation Ds(T) at the end of the operating period T does not exceed the allowable value Dmax.

[0045] As can be understood from equation (11), the smaller the ratio α of cycle degradation Dc(t) to capacity degradation D(t), the greater the increase in the value N2 after changing the number of operating cycles N. Also, the closer the target time point X is to the expiration time T, the greater the increase in the value N2 after changing the number of operating cycles N. Furthermore, the closer the health H(X) at target time point X is to the health H(t0) (=Hmax) at the start of operation t0, the greater the increase in the value N2 after changing the number of operating cycles N.

[0046] As illustrated in Figure 5, the arithmetic processing unit 52 notifies the management system 40 of the changed numerical value N2 of the number of operating cycles N. Specifically, the arithmetic processing unit 52 transmits the numerical value N2 to the management system 40 via the communication device 34. The management system 40 sets the power command value A according to the changed numerical value N2 of the number of operating cycles N. For example, the management system 40 increases the power command value A as the changed numerical value N2 increases.

[0047] The display control unit 53 in Figure 5 displays an image representing the result of the processing described above on the display device 33. For example, the display control unit 53 displays the reference image G1 in Figure 6 on the display device 33. As illustrated in Figure 6, the reference image G1 is an image representing the time change V1 and time change V2 for the health level H(t)(SOH).

[0048] Time change V1 is a curve representing the temporal change in health H(t) when the energy storage device 21 is operated with an operating cycle number N of value N1 throughout the entire operating period P. On the other hand, time change V2 is a curve representing the temporal change in health H(t) when the operating cycle number N is increased from value N1 to value N2 at the target time X (present) within the operating period P.

[0049] In reference image G1, time changes V1 and V2 are displayed in contrast. That is, an administrator viewing reference image G1 can visually compare time changes V1 and V2. Specifically, time changes V1 and V2 are displayed side by side on the display device 33.

[0050] As described above, in the first embodiment, the time change V1 of the health status H(t) when the number of operating cycles N is maintained at a numerical value N1 throughout the entire operating period P, and the time change V2 of the health status H(t) when the number of operating cycles N is increased to a numerical value N2 at the target time point X, can be grasped intuitively or visually by, for example, the manager of the energy storage device 21.

[0051] Figure 7 is a flowchart of the operation (hereinafter referred to as "management process") by the control system 30 to manage the number of operational cycles N. The management process is executed each time the target time point X arrives at a predetermined period (for example, one year). The number of operational cycles N is cumulatively updated with each execution of the management process.

[0052] When the management process begins, the control device 31 (information acquisition unit 51) acquires the health status H(X) of the energy storage device 21 at the target time X (Sa1). The control device 31 (arithmetic processing unit 52) ​​calculates the numerical value N2 of the number of operating cycles N by performing the calculation using the formula (11) described above (Sa2). The control device 31 (arithmetic processing unit 52) ​​notifies the management system 40 of the numerical value N2 via the communication device 34 (Sa3). The control device 31 (display control unit 53) also displays the reference image G1 of Figure 6 on the display device 33 (Sa4). The specific procedure for the management process is as described above.

[0053] As explained above, in the first embodiment, the value N2 after increasing the number of operating cycles N at the target time X is calculated so that the capacity degradation D(T) of the energy storage device 21 expected at the end of the operating period P T does not exceed the allowable value Dmax. Therefore, by increasing the number of operating cycles N from value N1 to value N2 at the target time X within the operating period P, the energy storage device 21 can be effectively utilized within a range where the capacity degradation D(T) does not exceed the allowable value Dmax. As a result of utilizing the energy storage device 21, it is possible to increase the revenue from electricity trading using the energy storage device 21 compared to the case where the energy storage device 21 is operated with the number of operating cycles of value N1 throughout the entire operating period P.

[0054] In the first embodiment, the numerical value N2 is calculated such that the sum of the cycle degradation Dc(T), which depends on the number of operating cycles N, and the storage degradation Ds(T), which does not depend on the number of operating cycles N, of the capacity degradation D(T) at the expiration time T does not exceed the allowable value Dmax. Therefore, compared to a configuration in which only one of the cycle degradation Dc(t) or storage degradation Ds(t) is taken into account as the capacity degradation D(t) of the energy storage device 21, the numerical value N2 of the number of operating cycles N can be calculated with high accuracy.

[0055] 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.

[0056] In the first embodiment, a configuration in which the ratio α of cycle degradation Dc(t) to capacity degradation D(t) is set to a predetermined value is conveniently illustrated. In reality, the ratio α changes depending on the number of operating cycles N. Taking these circumstances into consideration, in the second embodiment, the ratio α(N) is controlled according to the number of operating cycles N.

[0057] Figure 8 is a graph showing the relationship between the number of operating cycles N and the ratio α(N). As illustrated in Figure 8, the ratio α(N) of cycle degradation Dc(t) of the energy storage device 21 tends to increase monotonically with respect to the number of operating cycles N. Specifically, the ratio α(N) can be approximately expressed by the following formula (12), where the number of operating cycles N is the variable.

number

[0058] In equation (12), the symbol α(1) represents the ratio α(N) of cycle degradation Dc(t) when the energy storage device 21 is operated at a rate of 1 cycle / day N (N=1). The arithmetic processing unit 52 calculates the ratio α(N) by performing the calculation in equation (12). That is, the arithmetic processing unit 52 sets the ratio α(N) of cycle degradation Dc(t) to capacity degradation D(t) to a value corresponding to the ratio α(1) corresponding to 1 cycle / day and the current rate of operation N of the energy storage device 21.

[0059] Figure 9 is a flowchart of the management process in the second embodiment. As illustrated in Figure 9, when the health status H(X) at the target time point X is obtained in the management process (Sa1), the control device 31 (arithmetic processing unit 52) ​​calculates the ratio α(N) by calculation of formula (12) (Sb1). Note that the order of obtaining the health status H(X) (Sa1) and calculating the ratio α(N) (Sb1) may be reversed.

[0060] The control device 31 (arithmetic processing unit 52) ​​calculates the numerical value N2 of the number of operation cycles N by performing calculations on formula (11) to which the ratio α(N) is applied (Sa2). That is, a variable ratio α(N) corresponding to the number of operation cycles N is applied as the ratio α in formula (11). Notification of the numerical value N2 to the management system 40 (Sa3) and display of the reference image G1 (Sa4) are the same as in the first embodiment.

[0061] The same effects as in the first embodiment are achieved in the second embodiment. Furthermore, in the second embodiment, the relationship between the ratio α(N) of cycle degradation Dc(t) to capacity degradation D(t) in the energy storage device 21 and the number of operating cycles N of the energy storage device 21 is taken into consideration.Therefore, the capacity degradation D(T) of the energy storage device 21 at the end of the operating period P, T, can be calculated with high accuracy.

[0062] 3. Third Embodiment Figure 10 is a flowchart of the management process in the third embodiment. As illustrated in Figure 10, when the value N2 after changing the number of operation cycles N is calculated (Sa2), the control device 31 (arithmetic processing unit 52) ​​calculates the first predicted revenue Y1 and the second predicted revenue Y2 (Sc1).

[0063] The first predicted revenue Y1 is the revenue that the administrator can obtain through electricity trading if the energy storage device 21 is operated for a number of operation cycles N, which is a numerical value N1, throughout the entire operating period P. The control device 31 (arithmetic processing unit 52) ​​calculates the first predicted revenue Y1 by performing a predetermined calculation that applies the numerical value N1.

[0064] The second predicted revenue Y2 is the revenue that the administrator can obtain through electricity trading during the operating period P if the number of operating cycles N is increased from value N1 to value N2 at the target time point X. The control device 31 (arithmetic processing unit 52) ​​calculates the second predicted revenue Y2 by performing a predetermined calculation that applies the values ​​N1 and N2. As can be understood from the explanation in Figure 4, the second predicted revenue Y2 is greater than the first predicted revenue Y1 (Y2 > Y1).

[0065] The control device 31 (display control unit 53) displays the reference image G2 on the display device 33 (Sc2). Figure 11 is a schematic diagram of the reference image G2. As illustrated in Figure 11, the reference image G2 includes the first predicted revenue Y1 and the second predicted revenue Y2. Specifically, the first predicted revenue Y1 and the second predicted revenue Y2 are displayed in comparison in the reference image G2. For example, the first predicted revenue Y1 and the second predicted revenue Y2 are displayed as bar graphs. Therefore, an administrator viewing the reference image G2 can visually compare the first predicted revenue Y1 and the second predicted revenue Y2. The reference image G1 and the reference image G2 are displayed in parallel or sequentially on the display device 33. The reference image G2 also includes the rate of increase U of the second predicted revenue Y2 relative to the first predicted revenue Y1.

[0066] The same effects as in the first embodiment are achieved in the third embodiment. Furthermore, in the third embodiment, the manager of the energy storage device 21 can intuitively or visually grasp, for example, the first predicted revenue Y1 when the number of operating cycles N is maintained at a numerical value N1 throughout the entire operating period P, and the second predicted revenue Y2 when the number of operating cycles N is increased at the target time point X.

[0067] 4. 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.

[0068] (1) In the third embodiment, the first predicted return Y1 and the second predicted return Y2 for the entire investment period P were displayed on the display device 33. However, the period covered by the first predicted return Y1 and the second predicted return Y2 is not limited to the entire investment period P. For example, the annual return within the investment period P, or the return for the period from the target time X to the maturity time T within the investment period P, may be calculated as the first predicted return Y1 or the second predicted return Y2.

[0069] (2) In the third embodiment, a configuration was shown in which the control system 30 (arithmetic processing unit 52) ​​calculates the first predicted revenue Y1 and the second predicted revenue Y2. However, the entity that calculates the first predicted revenue Y1 and the second predicted revenue Y2 is not limited to the control system 30 (control device 31). For example, the management system 40 may calculate the first predicted revenue Y1 and the second predicted revenue Y2 in accordance with a numerical value N2 notified by the control system 30. In other words, the function of calculating the first predicted revenue Y1 and the second predicted revenue Y2 may be omitted from the control system 30.

[0070] (3) In the third embodiment, an example was given in which both reference image G1 and reference image G2 are displayed on the display device 33, but an example in which only reference image G2 is displayed is also conceivable. In other words, the display of reference image G1 may be omitted.

[0071] (4) The functions of the control system 30 in each of the above-described forms are realized through the cooperation of one or more processors constituting the control device 31 and the program stored in the storage device 32, as described above. The programs exemplified above can be provided in a form stored on a computer-readable recording medium and installed on a computer. The recording medium is, for example, a non-transitory recording medium, such as an optical recording medium (optical disc) like a CD-ROM, but also includes any known form of recording medium such as a semiconductor recording medium or a magnetic recording medium. Note that a non-transitory recording medium includes any recording medium except for transient propagation signals (transitory, propagating signals), and volatile recording media are not excluded. Furthermore, in a configuration in which a distribution device distributes a program via a communication network, the recording medium in which the distribution device stores the program corresponds to the non-transitory recording medium described above.

[0072] (5) The notation "the nth" (where n is a natural number) in this application is used solely as a formal and convenient label to distinguish each element in notation, and has no substantive meaning whatsoever. Therefore, there is no room for restrictive interpretation of the position or order of each element based on the notation "the nth".

[0073] 5. Addendum From the forms exemplified above, the following configuration can be understood, for example.

[0074] A control method for an energy storage device according to one aspect of this disclosure (Aspect 1) involves a control system that acquires the health status of the energy storage device at a target point in time within the operating period, and calculates a second value according to the health status of the energy storage device so that the capacity degradation of the energy storage device expected at the end of the operating period does not exceed an allowable value when the number of operating cycles of the energy storage device increases from a first value to a second value at the target point in time. In this aspect, the second value after the increase in the number of operating cycles at the target point in time is calculated so that the capacity degradation of the energy storage device expected at the end of the operating period does not exceed an allowable value. Therefore, by increasing the number of operating cycles from a first value to a second value at a target point in time within the operating period, the energy storage device can be effectively utilized within a range where the capacity degradation does not exceed an allowable value. As a result of utilizing the energy storage device, it is possible to increase revenue from electricity trading using the energy storage device compared to operating the energy storage device at the first value for the entire operating period.

[0075] In a specific example of Embodiment 1 (Embodiment 2), the control system further displays on a display device the change in health over time when the energy storage device is operated at the first value for the number of operating cycles over the entire operating period, and the change in health over time when the number of operating cycles is increased from the first value to the second value at the target time. According to the above embodiment, the change in health over time when the number of operating cycles is maintained at the first value over the entire operating period, and the change in health over time when the number of operating cycles is increased at the target time, can be grasped intuitively or visually, for example, by the manager of the energy storage device.

[0076] In a specific example of Embodiment 2 (Embodiment 3), the control system further calculates a first predicted revenue when the energy storage device is operated with the first value for the number of operating cycles throughout the entire operating period, and a second predicted revenue when the number of operating cycles is increased from the first value to the second value at the target time, and displays the first predicted revenue and the second predicted revenue on the display device. According to the above embodiment, the first predicted revenue when the number of operating cycles is maintained at the first value throughout the entire operating period, and the second predicted revenue when the number of operating cycles is increased at the target time, can be grasped intuitively or visually, for example, by the manager of the energy storage device.

[0077] In any specific example of Embodiments 1 to 3 (Embodiment 4), the calculation of the second value is performed such that the sum of the cycle degradation at the expiration date and the storage degradation at the expiration date does not exceed the allowable value. In the above embodiments, the second value is calculated such that the sum of the cycle degradation, which depends on the number of operating cycles, and the storage degradation, which does not depend on the number of operating cycles, does not exceed the allowable value. Therefore, the second value of the number of operating cycles can be calculated with high accuracy compared to a configuration in which only one of cycle degradation or storage degradation is taken into account as the capacity degradation of the energy storage device.

[0078] In the specific example of Embodiment 4 (Embodiment 5), in calculating the second value, the ratio of cycle degradation to capacity degradation is set to a value corresponding to the ratio of cycle degradation to capacity degradation when the energy storage device is operated at 1 cycle / day and the number of operating cycles. According to the above embodiment, the relationship in which the ratio of cycle degradation to capacity degradation in the energy storage device depends on the ratio corresponding to the number of operating cycles N at 1 cycle / day and the number of operating cycles of the energy storage device is taken into consideration, so that the capacity degradation of the energy storage device at the end of the operating period can be calculated with high accuracy.

[0079] A control system according to one aspect of the present disclosure (Aspect 6) comprises an information acquisition unit that acquires the health status of the energy storage device at a target point in time within the operating period, and a calculation processing unit that calculates the second value according to the health status of the energy storage device so that the capacity degradation of the energy storage device expected at the end of the operating period does not exceed an allowable value when the number of operating cycles of the energy storage device increases from a first value to a second value at the target point in time.

[0080] A program according to one aspect of this disclosure (Aspect 7) causes a computer system to function as an information acquisition unit that acquires the health status of the energy storage device at a target point in time within the operating period, and a calculation processing unit that calculates the second value according to the health status of the energy storage device so that the capacity degradation of the energy storage device expected at the end of the operating period does not exceed an allowable value when the number of operating cycles of the energy storage device increases from a first value to a second value at the target point in time. [Explanation of Symbols]

[0081] 100...Power system, 10...Power grid, 20...Energy storage system, 21...Energy storage device, 22...Regulator, 23...Transformer, 30...Control system, 31...Control device, 32...Storage device, 33...Display device, 34...Communication device, 40...Management system, 51...Information acquisition unit, 52...Calculation processing unit, 53...Display control unit.

Claims

1. The control system The health status of the energy storage device at the target point in time during the operating period is obtained. If the number of operating cycles of the energy storage device increases from the first value to the second value at the target time, the second value is calculated according to the health of the energy storage device so that the capacity degradation of the energy storage device expected at the end of the operating period does not exceed an allowable value. A method for controlling an energy storage device.

2. The control system further, The display device shows the change in health over time when the energy storage device is operated with the first value for the number of operating cycles over the entire operating period, and the change in health over time when the number of operating cycles is increased from the first value to the second value at the target time point. The control method of claim 1.

3. The control system further, The first predicted revenue is calculated when the energy storage device is operated with the first value for the number of operating cycles over the entire operating period, and the second predicted revenue is calculated when the number of operating cycles is increased from the first value to the second value at the target time. The first predicted revenue and the second predicted revenue are displayed on the display device. The control method of claim 2.

4. In calculating the second value mentioned above, The second value is calculated such that the sum of the cyclic degradation at the expiration date and the storage degradation at the expiration date of the aforementioned capacity degradation does not exceed the allowable value. The control method of claim 1.

5. In calculating the second value mentioned above, The ratio of cycle degradation to capacity degradation is set to a value corresponding to the ratio of cycle degradation to capacity degradation when the energy storage device is operated at a rate of 1 cycle / day, and the number of operating cycles. The control method of claim 4.

6. An information acquisition unit that acquires the health status of the energy storage device at a target point in time within the operating period, A calculation processing unit calculates the second value according to the health of the energy storage device so that the capacity degradation of the energy storage device expected at the end of the operating period does not exceed an allowable value when the number of operating cycles of the energy storage device increases from the first value to the second value at the target time, and A control system equipped with the following features.

7. An information acquisition unit that acquires the health status of the energy storage device at a target point in time during the operating period, and A calculation processing unit calculates the second value according to the health of the energy storage device so that the capacity degradation of the energy storage device expected at the end of the operating period does not exceed an allowable value when the number of operating cycles of the energy storage device increases from the first value to the second value at the target time, A program that makes a computer system function.

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