Battery system operation device, battery system operation method, and program

Abstract

To provide a battery system operation device capable of proposing appropriate system expansion timing for a secondary battery system.SOLUTION: A battery system operation device 100 is provided with: a battery deterioration calculation unit 102 for calculating a first transition prediction which is a transition prediction of a future deterioration degree of a first battery group and a second transition prediction which is a transition prediction of a future deterioration degree of a second battery group having a different deterioration degree from the first battery group; a battery deterioration degree comparison unit 103 for calculating, based on the first and second transition predictions, equality condition fulfillment timing that is timing when the first and second battery groups satisfy a predetermined equality condition; and a system expansion timing calculation unit 105 for determining or proposing, based on the equality condition fulfillment timing, system expansion timing that is timing for adding a secondary battery to a battery system.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a battery system operation device, a battery system operation method, and a program.

Background Art

[0002] As the main power source of renewable energy such as wind power and solar power progresses toward the realization of a carbon-neutral society, the introduction of stationary battery energy storage systems (BESS) as battery systems responsible for adjustment power to eliminate system instability is advancing. In the power storage system, the available battery capacity decreases due to the deterioration of the secondary battery during its operation. Therefore, it is necessary to design the initial capacity of the system in anticipation of the deterioration of the secondary battery with respect to the battery capacity that the power storage system should cover. However, if a system is designed to mount an excessive number of batteries for stable operation, the introduction cost of the power storage system will increase. Therefore, as a method for reducing the introduction cost of the power storage system, system augmentation is used, in which the margin of the initial capacity with respect to the battery capacity that the system should cover is designed to be small, and batteries are appropriately added according to the deterioration of the secondary battery to ensure the capacity of the entire power storage system. As an example, Non-Patent Document 1 describes a method for determining the expansion timing in the operation method of a battery system including system augmentation.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

[0004] In the above-mentioned technology, however, there is a demand for being able to propose a more appropriate system expansion timing for a secondary battery system. The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a battery system operation device, a battery system operation method, and a program that can propose an appropriate system expansion timing for a secondary battery system. [Means for solving the problem]

[0005] In order to solve the above problems, the battery system operation device of the present invention is characterized by comprising a battery deterioration calculation unit that calculates a first transition prediction which is a transition prediction of a future deterioration level of a first battery group included in a battery system and having one or more secondary batteries, and a second transition prediction which is a transition prediction of a future deterioration level of a second battery group included in the battery system and having a different deterioration level from the first battery group, a battery deterioration level comparison unit that calculates an equality condition satisfaction time, which is the time when the first and second battery groups will satisfy a specified equality condition, based on the first and second transition predictions, and a system expansion time calculation unit that determines or proposes a system expansion time, which is the time to add a secondary battery to the battery system, based on the equality condition satisfaction time. Effect of the Invention

[0006] According to the present invention, it is possible to propose an appropriate system expansion timing for a secondary battery system.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Modes for Carrying Out the Invention

[0008] [Outline of Embodiment] A secondary battery system generally includes a plurality of secondary batteries. The sum of the battery capacities of these secondary batteries is called the system capacity Qs (see Fig. 1). Also, the minimum value allowed for the system capacity Qs is called the required value Qsmin. Applying the content of Non-Patent Document 1 described above, it is considered that the degradation of the secondary battery can be predicted, and the timing when the predicted system capacity Qs reaches the required value Qsmin can be predicted. And it is considered that an operation method is possible in which a secondary battery is added at that timing to increase the system capacity Qs.

[0009] Fig. 1 is a diagram showing an example of the transition of the system capacity Qs in a comparative example. Note that this comparative example applies the content of Non-Patent Document 1 described above. In Fig. 1, the system capacity Qs decreases according to the capacity characteristic Qs1 as time t elapses. And at time t1, since the system capacity Qs reaches the required value Qsmin, system expansion is performed by adding a new secondary battery to the secondary battery system at time t1 or before that. As a result, the subsequent system capacity Qs becomes as shown in the capacity characteristic Qs2, and the system capacity Qs can be continuously maintained above the required value Qsmin.

[0010] However, when system expansion is performed by connecting batteries with different operation histories, problems such as an increase in the life cycle cost of the battery system may occur. In view of such a point, the embodiment described later proposes the timing of system expansion for adding batteries so as to suppress the life cycle cost of the battery system.

[0011] [First Embodiment] 〈Configuration of Battery System BS〉 Fig. 2 is a diagram showing a configuration example of a battery system BS applied to the first embodiment. The battery system BS includes a plurality of (four in the illustrated example) banks 10-1 to 10-4. In the following description, a plurality of components, information, etc. having the same or similar functions and meanings may be denoted with the same reference numeral appended with "-" and alphanumeric characters, such as "bank 10-1, bank 10-2". However, when it is not necessary to distinguish these multiple components, etc., they may be denoted by omitting "-" and alphanumeric characters, such as "bank 10".

[0012] Banks 10-1 to 10-4 each include one PCS (Power Conditioning System) 11-1 to 11-4, one container 12-1 to 12-4, and a plurality of battery racks 14. Here, each battery rack 14 houses one or more secondary battery cells (not shown), and each container 12 is a housing that houses one or more battery racks 14. More specifically, container 12-1 of bank 10-1 houses battery racks 14-11, 14-12, 14-13, container 12-2 of bank 10-2 houses battery racks 14-21, 14-22, 14-23, container 12-3 of bank 10-3 houses battery racks 14-31, 14-32, 14-33, and container 12-4 of bank 10-4 houses battery racks 14-41, 14-42, 14-43.

[0013] The plurality of battery racks 14 housed in each container 12 are connected in parallel in this embodiment. However, in each container 12, these battery racks 14 may be connected in series. In the illustrated example, the battery system BS includes four banks 10-1 to 10-4, but the number of banks 10 may be changed according to the capacity and output required for the battery system BS. Also, in the illustrated example, one bank 10 includes three battery racks 14, but the number of battery racks 14 may be changed in the same manner.

[0014] <Configuration of the First Embodiment> FIG. 3 is a block diagram of a battery system operation device 100 (computer) according to the first embodiment. This battery system operation device 100 is a device that determines or proposes the timing for adding battery racks 14 in the battery system BS (see FIG. 2). In FIG. 3, the battery system operation device 100 includes a battery system information input unit 101, a battery degradation calculation unit 102 (battery degradation calculation process, battery degradation calculation means), a battery degradation degree comparison unit 103 (battery degradation degree comparison process, battery degradation degree comparison means), a battery system capacity calculation unit 104 (system expansion timing calculation process, system expansion timing calculation means), and a system expansion timing calculation unit 105.

[0015] Battery system information including secondary battery specification data DB, degradation state data DH, system configuration data DS, required value Qsmin (see FIG. 1) operation data DL, and economic index data DE is input to the battery system information input unit 101. The secondary battery specification data DB is data that defines the specifications of each battery rack 14 and the secondary batteries (not shown) built therein.

[0016] The degradation state data DH is data that defines the SOH (State of Health) of each battery rack 14. SOH includes various battery characteristics, including SOHQ for capacity and SOHR for resistance. SOHQ is generally expressed as a percentage, with a value of 100 for a new battery before degradation, and the value gradually decreases with degradation. On the other hand, SOHR is also generally expressed as a percentage, with a value of 100 for a new battery before degradation, and the value gradually increases with degradation.

[0017] The system configuration data DS includes the number of battery racks 14 in series and in parallel, the number of PCS11, etc. The operation data DL is time-series data such as current values, voltage values, input / output energy values, and temperature in the battery system BS and each battery rack 14. The economic index data DE is data on economic indicators for cost calculation, including device cost, operation and maintenance cost, electricity rate, discount rate, etc.

[0018] Based on the input secondary battery specification data DB, the battery degradation calculation unit 102 stores degradation prediction model data DM that determines the change state of SOH. In the degradation prediction model data DM, a degradation prediction model based on the physical mechanism of the battery is applied. However, the degradation prediction model data DM is not limited to this, and a semi-empirical model or a machine learning model may be applied.

[0019] Then, the battery degradation calculation unit 102 uses the history of the battery state such as SOH of each current and past battery rack 14, the operation history of each current and past battery rack 14, and the degradation prediction model data DM to calculate the future change in SOH of each battery rack 14. In this embodiment, among the SOHs, SOHQ is particularly applied as an index of battery degradation. Thereby, the battery degradation calculation unit 102 calculates the SOHQ transition characteristics in each battery rack 14. However, the index of battery degradation is not limited to SOHQ, and SOHR or SOH defined by paying attention to other characteristics may be applied.

[0020] The battery degradation degree comparison unit 103 compares the SOHQ transition curves of the individual battery racks 14 obtained by the battery degradation calculation unit 102. In particular, the battery degradation degree comparison unit 103 calculates the equal condition fulfillment time when two or more battery racks 14 originally having different SOHQs reach a time in the future when the SOHQ satisfies a predetermined equal condition, and the value of the SOHQ of these battery racks 14 at that time. Here, the "predetermined equal condition" means that the relative ratio of the SOHQs of these battery racks 14 falls within a predetermined range, and this "predetermined range" can be, for example, "±10%", "±5%", "±2%", etc. In the following description, "satisfying the predetermined equal condition" may be referred to as "substantially equal".

[0021] The battery system capacity calculation unit 104 calculates the change in the system capacity Qs of the entire battery system BS based on the SOHQ transition curves of the individual battery racks 14 obtained by the battery degradation calculation unit 102. The system expansion timing calculation unit 105 calculates the system expansion timing at which the battery rack 14 should be added based on the relationship among the substantially equal information of the individual battery SOHQs obtained by the battery degradation degree comparison unit 103, the transition of the system capacity Qs obtained by the battery system capacity calculation unit 104, and the required value Qsmin.

[0022] That is, the system expansion timing calculation unit 105 selects, as the system expansion timing, the time when the condition that the SOHQs of the plurality of battery racks 14 are substantially equal is satisfied in addition to the condition that the system capacity Qs is equal to or greater than the required value Qsmin. Further, the system expansion timing calculation unit 105 calculates the life cycle cost when the system expansion is performed at the designated system expansion timing. The life cycle cost can be, for example, the levelized cost of storage (LCOS). However, the system expansion timing calculation unit 105 is not limited to LCOS, and may calculate other indexes representing the life cycle cost of the battery system.

[0023] FIG. 4 is a hardware configuration diagram of the battery system operation device 100. The input device 201 is a device for inputting various data, and can be configured by, for example, a keyboard, a mouse, a touch pad, a battery rack ball, etc. The functional unit of the battery system information input unit 101 is realized by this input device 201. The storage device 204 can be configured by, for example, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, a hard disk, an optical disk, etc. A part or all of the storage device 204 may be provided integrally with the computer 202. Stored in this storage device 204 are various data input by the user, parameters for predicting battery degradation, programs for causing the computer 202 to execute battery degradation, system expansion timing evaluation, cost calculation, etc.

[0024] The computer 202 is a device that performs numerical analysis using the input data, and implements the battery degradation calculation unit 102, battery degradation degree comparison unit 103, battery system capacity calculation unit 104, and system expansion timing calculation unit 105 in FIG. 3. By executing a predetermined calculation program, the computer 202 reads out the input battery system information, the pre-prepared degradation prediction model data DM, etc., and executes calculation processing using these to calculate the system expansion timing. Note that the computer 202 may be a device in which a predetermined calculation program used for numerical analysis is directly incorporated into an arithmetic circuit, or may be a device that reads and executes a predetermined calculation program stored externally. Also, the computer 202 may have a function of executing various processes such as display processing.

[0025] The computer 202 can be configured by various calculation devices such as an arithmetic circuit such as an integrated circuit, and a CPU (Central Processing Unit) incorporating a memory and a register. The display device 203 is a device that displays the calculation results obtained by the computer 202, and displays various information to the user based on the commands of the computer 202. The display content may be the numerical value itself, or may be a distribution display using colors, textures, etc. corresponding to the numerical values. For example, based on the commands of the system expansion timing calculation unit 105 (see FIG. 3), the display device 203 displays the SOHQ transition curves Q14, Q16 (see FIG. 6) described later, other predicted values of battery degradation, changes in battery system capacity, life cycle cost, the system expansion timing to be determined or proposed, etc. The display device 203 is configured by, for example, a liquid crystal display, a plasma display, an organic EL display, a cathode ray tube, etc.

[0026] FIG. 5 is a diagram showing a configuration example of the battery system BS after system expansion. When it is predicted that the system capacity Qs will fall below the required value Qsmin due to the capacity degradation of the battery system BS, all the battery racks 14 included in the bank 10-4 before expansion (see Fig. 2) are rearranged to other banks 10. That is, as shown in Fig. 5, for the banks 10-1, 10-2, 10-3, the battery racks 14-41, 14-42, 14-43 are rearranged respectively. As a result, for example, the battery rack 14-41 is connected in parallel to the battery racks 14-11, 14-12, 14-13. These battery racks 14-11 to 14-43 provided before the system expansion are collectively referred to as the battery rack group Ga (the first battery group).

[0027] In addition, as shown in Fig. 5, for the empty space in the bank 10-4 generated by this rearrangement, other battery racks 14-51, 14-52, 14-53 are added. Thereby, the system capacity Qs of the entire battery system BS can be increased. These added battery racks 14-51, 14-52, 14-53 are collectively referred to as the battery rack group Gb (the second battery group). Here, the number of the battery racks 14 to be added may be changed according to the capacity to be increased by the system expansion. Also, it is preferable that the SOHQ of the added battery rack group Gb is "100", that is, in an undeteriorated state. However, if a larger SOHQ than the battery rack group Ga can be ensured, the SOHQ of the battery rack group Gb may be a value less than "100".

[0028] In the system expansion method shown in Fig. 5, there is no need to add a new PCS11 to the battery system BS, and there is an advantage that the cost at the time of expansion can be suppressed. As a result of the inventors' intensive research, it is preferable to combine the change in the system capacity Qs of the battery system BS and the change in the degradation degree of the battery racks 14 constituting the system. Thereby, in the system expansion in the form of connecting the battery racks 14 having different operation histories, the system expansion is possible while suppressing the life cycle cost of the battery system BS.

[0029] Fig. 6 is a diagram showing an example of the SOHQ transition curve in the first embodiment. In FIG. 6, the horizontal axis represents time t, and the vertical axis represents the SOHQ [%] of the battery rack 14. The SOHQ transition curve Q12 represents the transition of the SOHQ of the battery rack group Ga initially installed. When there are a plurality of banks 10 as in the example of FIG. 2, by equally allocating the load to each bank 10, the SOHQ of any battery rack 14 in the battery system BS can be changed, for example, along the curve Q12. In the illustrated example, at time t10, it is assumed that the first system expansion is performed as shown in FIG. 5. After time t10, the SOHQ of the battery rack group Ga changes along the curve Q14 (first transition prediction) starting from time t10. On the other hand, a larger load than that of the battery rack group Ga is allocated to the added battery rack group Gb after time t10.

[0030] Then, the SOHQ of the battery rack group Gb changes, for example, along the SOHQ transition curve Q16 (second transition prediction) in the figure. According to the curve Q16, the SOHQ at time t10 is 100 [%], and the subsequent curve Q16 drops more steeply than the curve Q14. And at time t15 (when the equal condition is satisfied), the SOHQ transition curves Q14 and Q16 intersect. Therefore, at time t15 and in its vicinity, the above-described equal condition is satisfied. The curves Q14 and Q16 can be predicted by the battery degradation calculation unit 102 (see FIG. 3). Thereby, the battery degradation degree comparison unit 103 can predict time t15 in advance during the operation of the battery system BS after time t10. Note that the SOHQ transition curve Q17 shows the change in the SOHQ of the battery rack group Gb when it is assumed that the same load as before time t15 is continuously applied to the battery rack group Gb.

[0031] Here, the total sum of the battery capacities of the battery rack group Ga is called the battery capacity C a (not shown). For example, when the SOHQ of the battery racks 14 belonging to the battery rack group Ga is the same, the value obtained by multiplying the total sum of the initial capacities of these battery racks by the SOHQ is the battery capacity C a . Similarly, the total sum of the battery capacities of the battery rack group Gb is called the battery capacity C b (not shown).

[0032] The system expansion timing calculation unit 105 determines a coefficient k that satisfies the following [Equation 1] a , k b and sets the load sharing of the battery rack groups Ga and Gb according to the ratio of the coefficient k a , k b .

Equation

[0033] In [Equation 1], the coefficient k a , k b is a coefficient that determines the ratio of the load distribution borne by the battery rack groups Ga and Gb to the overall load of the battery system BS. There are multiple combinations of the coefficient k a , k b that satisfy [Equation 1]. Therefore, the battery degradation calculation unit 102 outputs combinations of various coefficients k a , k b , that is, combinations of multiple types of SOHQ transition curves Q14 and Q16 corresponding to various load distribution candidates. As a result, the battery degradation degree comparison unit 103 calculates the equal condition fulfillment time (for example, time t15) corresponding to various load distribution candidates. For example, if a value greater than "1" is set for the coefficient k b , according to the relationship of [Equation 1], the coefficient k a will be a value less than "1". Thus, the load of each battery rack 14 in the battery rack group Gb can be adjusted to be greater than the load of each battery rack 14 in the battery rack group Ga.

[0034] As a result of such adjustment, as described above, the slope of the curve Q16 after time t10 is greater than the slope of the curve Q14, and at time t15, the curves Q14 and Q16 intersect. This means that, as described above, the above-mentioned equal conditions are satisfied at time t15 and in its vicinity. Therefore, it is advisable to execute the second system expansion, for example, at time t15, within the period when this equal condition is satisfied.

[0035] In the second system expansion, similar to the first system expansion, battery racks 14-51, 14-52, and 14-53 belonging to bank 10-4 (in other words, included in the battery rack group Gb) may be relocated to banks 10-1, 10-2, and 10-3 respectively. Then, a new battery rack 14 (not shown) may be added to the emptied bank 10-4.

[0036] By performing the second system expansion near the time t15 when the intersection points of the curves Q14 and Q16 appear in this way, the SOHQ of all the battery racks 14 belonging to banks 10-1, 10-2, and 10-3 can be made substantially the same value. And after the time t15, the load of the newly added battery rack 14 belonging to bank 10-4 may be made relatively large, and the load of the existing battery racks 14 belonging to banks 10-1, 10-2, and 10-3 may be made relatively small.

[0037] As a result, in the illustrated example, the SOHQ of the newly added battery rack 14 belonging to bank 10-4 drops steeply as shown by the SOHQ transition curve Q20. Also, the SOHQ of the battery racks 14 belonging to banks 10-1, 10-2, and 10-3 gradually decreases as shown by the SOHQ transition curve Q18 starting from the time t15.

[0038] FIG. 7 is a diagram showing an example of the change in the system capacity Qs in the first embodiment. The capacity characteristic Qs30 shown by the solid line in the figure is the system capacity Qs realized when the SOHQ of each battery rack 14 changes as shown in FIG. 6. That is, as a result of the first and second system expansions being performed at the times t10 and t15, the capacity characteristic Qs30 rises at these times, and in the other periods, the capacity characteristic Qs30 gradually decreases. The capacity characteristic Qs32 shown by the dashed line indicates the transition of the system capacity Qs when the system expansion is not performed.

[0039] In Fig. 7, focusing on the required value Qsmin of the system capacity Qs, at time t15, the capacity characteristic Qs30 does not fall below the required value Qsmin. Therefore, it is possible to continue operating the battery system BS without system expansion after time t15. In that case, the system capacity Qs decreases along the capacity characteristic Qs34 starting from time t15, and the capacity characteristic Qs34 reaches the required value Qsmin at time t20.

[0040] Here, the comparative example will be described again. As described in Fig. 1, in the comparative example, the timing when the system capacity Qs reaches the required value Qsmin is selected as the timing of system expansion. Therefore, in the comparative example, the operation of the battery system BS is continued without system expansion at time t15 shown in Fig. 7, and time t20 is selected as the timing of the second system expansion.

[0041] As shown in Fig. 6, in this embodiment, since it is assumed that the second system expansion is performed at time t15, the curve Q16 ends at time t15. However, in the comparative example, since the second system expansion is not performed at time t15, the SOHQ of the battery racks 14-51, 14-52, 14-53 decreases along the curve Q17 shown in Fig. 6. That is, compared with the SOHQ of the other battery racks 14 that change along the SOHQ transition curve Q18, the SOHQ of the battery racks 14-51, 14-52, 14-53 will decrease significantly.

[0042] In the comparative example, in order to execute the second system expansion at time t20 in FIG. 7, the battery racks 14-51, 14-52, 14-53 with a significantly reduced SOHQ will be relocated to banks 10-1, 10-2, 10-3. Here, when the SOHQs of a plurality of battery racks 14 belonging to a certain bank 10 and interconnected are different, when the battery rack 14 with a relatively small SOHQ reaches the usage limit Qmin (60% in the example of FIG. 8 described later), it is necessary to review the operation of the bank 10. In other words, the system expansion timing calculation unit 105 determines or proposes the equal condition fulfillment time as the system expansion time on the condition that the SOHQs of the battery rack groups Ga and Gb at the equal condition fulfillment time (for example, time t15) are all equal to or higher than the usage limit Qmin.

[0043] In this case, when the SOHQ of a certain specific battery rack 14 reaches "60%", even if the SOHQs of other battery racks 14 are greater than "60%" and they can still be used, at that time, the life of the bank 10 will be limited by a certain specific battery rack 14 whose SOHQ has reached "60%". That is, a certain specific battery rack 14 whose SOHQ has reached "60%" becomes the bottleneck. Also, when a plurality of battery racks 14 are connected in series within the bank 10, the capacity of the bank 10 is determined by the battery rack 14 with the smallest SOHQ. Therefore, even before the life of the bank 10 reaches, there is also a problem that the capacity reduction of the bank 10 becomes significant.

[0044] In contrast, according to the present embodiment, system expansion can be executed at a timing when the SOHQ of the existing battery rack 14 included in a certain bank 10 and the SOHQ of the battery rack 14 transferred to that bank 10 are substantially equal. Thereby, it is possible to prevent in advance the problem caused by a plurality of battery racks 14 with different SOHQs belonging to the same bank 10. In the above example, the timing when the SOHQ becomes "60%" is used as the usage limit Qmin. However, depending on the characteristics of the secondary battery and the criteria for system operation, a value of SOHQ other than "60%" may be used as the usage limit Qmin. Further, an index other than SOHQ may be applied to define the usage limit of the battery rack 14.

[0045] FIG. 8 is an example in which the transition of the minimum SOHQ of the battery rack 14 in the battery system BS is calculated. The SOHQ transition curve Q22 is an example of the transition of the minimum SOHQ according to the present embodiment. That is, the curve Q22 is an example of the transition in the case where the second system expansion is performed at the time t15 (see FIG. 7) when the SOHQ of each battery rack 14 is substantially equal. Further, the SOHQ transition curve Q24 is an example of the transition of the minimum SOHQ according to the comparative example. That is, the curve Q24 is an example of the transition in the case where the second system expansion is performed at the time t20 when the SOHQ of each battery rack 14 is not substantially equal. Also, the usage limit Qmin of the battery rack 14 is assumed to be "60%".

[0046] In both of the curves Q22 and Q24, the battery rack 14 having the smallest SOHQ in the battery system BS reaches the usage limit Qmin earlier than the other battery racks 14. According to the curve Q22 of the present embodiment, the timing of reaching the usage limit Qmin is the time t35. On the other hand, according to the curve Q24 of the comparative example, the timing of reaching the usage limit Qmin is the time t30, which is earlier than the curve Q22 of the present embodiment. Therefore, according to the present embodiment, the long life of the battery system BS can be realized compared with that of the comparative example.

[0047] FIG. 9 is an example of the change in the system capacity Qs of the entire battery system BS in the operation of FIG. 8. The capacity characteristic Qs42 shows the transition of the system capacity Qs according to the present embodiment. Also, the capacity characteristic Qs44 indicated by the dashed line shows the transition of the system capacity Qs according to the comparative example. As described above, in the comparative example, the second system expansion is performed at time t20. After that, the system capacity Qs according to the capacity characteristic Qs42 of the comparative example becomes larger than that of the capacity characteristic Qs42 of the present embodiment. However, as described in FIG. 8, in the comparative example, the battery rack 14 having the smallest SOHQ reaches the usage limit Qmin at time t30. On the other hand, according to the present embodiment, the operation of the battery system BS can be continued until time t35. Therefore, if it is sufficient to satisfy the condition that "the system capacity Qs is equal to or greater than the required value Qsmin", it is preferable to perform the operation along the capacity characteristic Qs42 of the present embodiment.

[0048] Next, the life cycle cost LCOS will be described. The life cycle costs LCOS of the present embodiment and the comparative example can be calculated by the following [Equation 2].

Equation

[0049] In [Equation 2], n is the year after the operation of the battery system BS, the initial value thereof is "1", and it is a value incremented by "1" every year. N is the final year of the period for which the life cycle cost LCOS is calculated. CAPEX(n) is the equipment cost in year n, and in the first year (n = 1), it includes the introduction cost of the battery system BS. Also, in subsequent years, it includes the system expansion cost. OPEX(n) is the operation cost in year n, and includes maintenance costs and the like. ECC(n) is the charging cost in year n, and includes the electricity charge required when charging the battery system BS. Eout(n) is the output energy in year n. d is the discount rate when converting costs and energy into present values.

[0050] In this way, for each year n, the cost and the output energy Eout(n) are converted into present values, summed up over the total operating period, and the ratio of the two is calculated, whereby the life cycle cost LCOS can be calculated. The life cycle cost LCOS is the system cost per unit energy. Therefore, it is preferable for the user of the battery system BS to introduce and operate the battery system BS so that the life cycle cost LCOS becomes small during the desired operating period.

[0051] FIG. 10 is an example of calculating the transition of the life cycle cost in the present embodiment and the comparative example. The transition curve LC1 in FIG. 10 is the transition of the life cycle cost LCOS according to the present embodiment. Also, the transition curve LC2 is the transition of the life cycle cost LCOS according to the comparative example. In the present embodiment, as a result of performing the second system expansion at time t15, the transition curve LC1 becomes higher than the transition curve LC2 before and after time t15. However, thereafter, the transition curve LC1 becomes lower than the transition curve LC2. Thus, according to the present embodiment, in the long term, the life cycle cost LCOS can be suppressed as compared with the comparative example.

[0052] [Second Embodiment] Next, the battery system operation device according to the second embodiment will be described. The configuration of the battery system operation device according to the second embodiment is the same as that of the first embodiment (see FIG. 3), except for the points described below. As described above with reference to FIG. 6, the coefficient k a , k b Since there are a plurality of combinations of, the slope of the SOHQ transition curves Q14 and Q16 and the intersection timing of the two can be adjusted by adjusting the coefficient k a , k b . Therefore, in the present embodiment, the one with the smallest life cycle cost LCOS is selected from among a plurality of candidates of the SOHQ transition curves Q14 and Q16 and applied.

[0053] FIG. 11 is a diagram showing an example of the SOHQ transition curve in the second embodiment. The SOHQ transition curve Q12 in FIG. 11 is the same as that shown in FIG. 6. Also, the SOHQ transition curves Q14A and Q16A are examples of the curves Q14 and Q16 when the coefficients k a , k b are changed, and the timing at which the curves Q14A and Q16A intersect is defined as time t17 (equal condition fulfillment period). Also, the SOHQ transition curve Q18A represents the transition of the SOHQ of the existing battery rack 14 provided before the second system expansion at time t17. Further, the SOHQ transition curve Q20A represents the transition of the SOHQ of the newly added battery rack 14 when the second system expansion is performed at time t17.

[0054] The system expansion timing calculation unit 105 of the present embodiment calculates the life cycle cost LCOS based on each operation condition for a plurality of candidates for the system expansion timing (for example, time t15 in FIG. 6 and time t17 in FIG. 11) that differ depending on the load distribution conditions. Then, the system expansion timing calculation unit 105 adopts, as the system expansion timing, the one with the minimum life cycle cost LCOS among the plurality of candidates for the system expansion timing. Thereby, it is possible to select the system expansion timing that can most suppress the life cycle cost LCOS.

[0055] In other words, the system expansion timing calculation unit 105 selects, as the curves Q14 and Q16 to be actually applied, the combination of various coefficients k a , k b , that is, the combination of the SOHQ transition curves Q14 and Q16 corresponding to the load distribution candidates, in which the system capacity Qs is equal to or greater than the required value Qsmin at the equal condition fulfillment period (for example, time t15) and the life cycle cost is the smallest. Then, the system expansion timing calculation unit 105 may determine or propose, as the system expansion timing, the equal condition fulfillment period (for example, time t15) based on the selected curves Q14 and Q16.

[0056] In the above-described example, one of the candidates for the system expansion timing based on different load distributions was selectively selected. However, a plurality of candidates may be adopted together as the system expansion timing. For example, among four different banks 10, curves Q14 and Q16 (see FIG. 6) may be applied to two of the banks 10, and curves Q14A and Q16A (see FIG. 11) may be applied to the remaining two banks 10. In this case, for example, both the time t15 in FIG. 6 and the time t17 in FIG. 11 can be adopted as the system expansion timing. In this way, by dispersing the system expansion timing over a plurality of times, the life cycle cost LCOS may be further suppressed.

[0057] [Third Embodiment] Next, a battery system operation device according to the third embodiment will be described. The configuration of the battery system operation device according to the third embodiment is the same as that of the first and second embodiments (see FIG. 3), except for the points described below. In this embodiment, the user inputs a maintenance schedule via the battery system information input unit 101. This maintenance schedule includes a maintainable period, which is a period during which maintenance work on the battery system BS is possible.

[0058] When expanding the battery system BS, it is necessary to connect the battery rack 14 whose SOHQ has decreased due to deterioration to a bank 10 different from the previous bank 10. It is necessary to secure the working time for changing the installation location of the battery rack 14, changing the setting of the connection cable, etc. Since the battery system BS cannot be operated during these operations, it is necessary to plan a maintenance schedule and secure a maintainable period.

[0059] Therefore, when calculating the system expansion timing, the system expansion timing calculation unit 105 of the present embodiment determines or proposes, as the system expansion timing, a candidate within the maintainable period among a plurality of candidates for the system expansion timing (for example, time t15 in FIG. 6 and time t17 in FIG. 11) that differ depending on the load distribution conditions. Further, when there are a plurality of candidates belonging to the maintainable period, the system expansion timing calculation unit 105 calculates the life cycle cost LCOS for each of them, and determines or proposes, as the system expansion timing, the one with the minimum life cycle cost LCOS.

[0060] [Effects of the Embodiment] As described above, according to the embodiment described above, the battery system operation device 100 includes a battery degradation calculation unit 102 that calculates a first transition prediction (Q14), which is a prediction of the future degradation degree transition of a first battery group (Ga) included in the battery system BS and having one or more secondary batteries, and a second transition prediction (Q16), which is a prediction of the future degradation degree transition of a second battery group (Gb) included in the battery system BS and having a degradation degree different from that of the first battery group (Ga); a battery degradation degree comparison unit 103 that calculates, based on the first and second transition predictions (Q14, Q16), an equal condition satisfaction timing (such as t15, t17, etc.) at which the first and second battery groups (Ga, Gb) satisfy a predetermined equal condition; and a system expansion timing calculation unit 105 that determines or proposes, based on the equal condition satisfaction timing (such as t15, t17, etc.), a system expansion timing, which is a timing for adding secondary batteries to the battery system BS. Thereby, since the system expansion timing can be determined or proposed based on the equal condition satisfaction timing (such as t15, t17, etc.) at which the first and second battery groups (Ga, Gb) satisfy a predetermined equal condition, an appropriate system expansion timing can be proposed for the secondary battery system.

[0061] Further, the battery degradation calculation unit 102 calculates the first and second transition predictions (Q14, Q16) for each of the load distribution candidates which are a plurality of candidates for load distribution for the first and second battery groups (Ga, Gb). The battery degradation degree comparison unit 103 calculates the equal condition fulfillment times (t15, t17, etc.) for each of the load distribution candidates. The system expansion timing calculation unit 105 further has a function of calculating the life cycle cost LCOS corresponding to each load distribution candidate, and a function of selecting any one of the load distribution candidates based on the life cycle cost LCOS. It is more preferable to determine or propose the system expansion timing based on the equal condition fulfillment times (t15, t17, etc.) corresponding to the selected load distribution candidate. Thereby, since any one of the plurality of equal condition fulfillment times (t15, t17, etc.) corresponding to the load distribution candidates which are a plurality of candidates for load distribution can be selected based on the life cycle cost LCOS, a more appropriate system expansion timing can be determined or proposed.

[0062] Furthermore, the battery system operation device 100 further includes a battery system information input unit 101 having a function of inputting a maintainable period which is a period during which maintenance work of the battery system BS is possible. The system expansion timing calculation unit 105 preferably selects the load distribution candidate with the minimum life cycle cost LCOS from among the load distribution candidates whose corresponding equal condition fulfillment times (t15, t17, etc.) are included in the maintainable period, and determines or proposes the system expansion timing. Thereby, since the load distribution candidate with the minimum life cycle cost LCOS can be selected from among the load distribution candidates whose equal condition fulfillment times (t15, t17, etc.) belong to the maintainable period, a more appropriate system expansion timing can be determined or proposed.

[0063] Also, it is more preferable that the battery degradation calculation unit 102 calculates the first and second transition predictions (Q14, Q16) using the history of the past degradation degrees of the first and second battery groups (Ga, Gb) and the past operation history. Thereby, since accurate first and second transition predictions (Q14, Q16) can be obtained, a more appropriate system expansion timing can be determined or proposed.

[0064] Further, it is more preferable that the system expansion timing calculation unit 105 determines or proposes the system expansion timing based on the equalization condition fulfillment times (t15, t17, etc.) on the condition that the degradation degrees of the first and second battery groups (Ga, Gb) at the equalization condition fulfillment times (t15, t17, etc.) both satisfy a predetermined condition (SOHQ ≧ Qmin). Thereby, since the system expansion timing can be determined or proposed within the range where the first and second battery groups (Ga, Gb) function properly, a more appropriate system expansion timing can be determined or proposed.

[0065] Further, it is more preferable that the system expansion timing calculation unit 105 further has a function of displaying the first and second transition predictions (Q14, Q16) and the system expansion timing on the screen of the display device 203. Thereby, the user can recognize the first and second transition predictions (Q14, Q16) and the system expansion timing via the display device 203.

[0066] [Modification Example] The present invention is not limited to the above-described embodiments, and various modifications are possible. The above-described embodiments are exemplified for easy understanding and explanation of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, a part of the configuration of each embodiment can be deleted, or other configurations can be added or replaced. Also, the control lines and information lines shown in the figures indicate those considered necessary for explanation, and do not necessarily show all the control lines and information lines required in the product. In practice, it may be considered that almost all the configurations are interconnected. Possible modifications to the above embodiments are, for example, as follows.

[0067] (1) Since the hardware of the battery system operation device 100 in each of the above embodiments can be realized by a general computer, a program or the like for executing the various processes described above may be stored in a storage medium (a computer-readable recording medium on which the program is recorded) or distributed via a transmission path.

[0068] (2) The various processes described above were described as software processes using a program in the above embodiment, but part or all of them may be replaced with hardware processes using an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0069] (3) The various processes executed in the above embodiment may be executed by a server computer via a network not shown, and the various data stored in the above embodiment may also be stored in the server computer.

Explanation of Signs

[0070] 100 Battery system operation device (computer) 101 Battery system information input unit 102 Battery degradation calculation unit (battery degradation calculation process, battery degradation calculation means) 103 Battery degradation degree comparison unit (battery degradation degree comparison process, battery degradation degree comparison means) 105 System expansion timing calculation unit (system expansion timing calculation process, system expansion timing calculation means) 203 Display device BS Battery system Ga Battery rack group (first battery group) Gb Battery rack group (second battery group) Q14 SOHQ transition curve (first transition prediction) Q16 SOHQ transition curve (second transition prediction) t15 Time (equal condition fulfillment time) t17 Time (equal condition fulfillment time) LCOS Life cycle cost

Claims

1. A first transition prediction which is a prediction of the future deterioration degree transition of a first battery group included in the battery system and having one or more secondary batteries, and a second battery group included in the battery system and having a deterioration degree different from that of the first battery group. A battery deterioration calculation unit that calculates a second transition prediction that is a prediction of the future deterioration degree transition; A battery deterioration degree comparison unit that calculates an equal condition fulfillment time, which is a time when the first and second battery groups satisfy a predetermined equal condition, based on the first and second transition predictions; A system expansion time calculation unit that determines or proposes a system expansion time, which is a time to add a secondary battery to the battery system, based on the equal condition fulfillment time; A battery system operation device characterized by comprising the above.

2. The battery deterioration calculation unit calculates the first and second transition predictions for each of a plurality of load distribution candidates, which are load distributions for the first and second battery groups. The battery deterioration degree comparison unit calculates the equal condition fulfillment time for each of the load distribution candidates. The system expansion time calculation unit Has a function of calculating a life cycle cost corresponding to each of the load distribution candidates; Further includes a function of selecting any one of the load distribution candidates based on the life cycle cost, and Determines or proposes the system expansion time based on the equal condition fulfillment time corresponding to the selected load distribution candidate. The battery system operation device according to claim 1, characterized by comprising the above.

3. Further includes a battery system information input unit having a function of inputting a maintenance possible period, which is a period during which maintenance work of the battery system is possible. The system expansion time calculation unit selects the load distribution candidate having the minimum life cycle cost from among the load distribution candidates whose corresponding equal condition fulfillment time is included in the maintenance possible period, and determines or proposes the system expansion time. The battery system operation device according to claim 2, characterized by comprising the above.

4. The battery deterioration calculation unit calculates the first and second transition predictions using the past deterioration degree history and the past operation history of the first and second battery groups. The battery system operation device according to any one of claims 1 to 3, characterized by comprising the above.

5. The system expansion timing calculation unit determines or proposes the system expansion timing based on the equalization condition fulfillment timing, on the condition that the degradation degrees of the first and second battery groups at the equalization condition fulfillment timing both satisfy a predetermined condition. The battery system operation device according to claim 4, characterized in that.

6. The system expansion timing calculation unit further has a function of displaying the first and second transition predictions and the system expansion timing on the screen of a display device. The battery system operation device according to claim 5, characterized in that.

7. A battery degradation calculation process for calculating a first transition prediction which is a prediction of the future degradation degree transition of a first battery group included in the battery system and having one or more secondary batteries, and a second transition prediction which is a prediction of the future degradation degree transition of a second battery group included in the battery system and having a degradation degree different from that of the first battery group; A battery degradation degree comparison process for calculating an equalization condition fulfillment timing which is the timing when the first and second battery groups satisfy a predetermined equalization condition based on the first and second transition predictions; A system expansion timing calculation process for determining or proposing a system expansion timing which is the timing for adding secondary batteries to the battery system based on the equalization condition fulfillment timing, and causing a computer to execute the process. A battery system operation method, characterized in that.

8. A computer, A battery degradation calculation means for calculating a first transition prediction which is a prediction of the future degradation degree transition of a first battery group included in the battery system and having one or more secondary batteries, and a second transition prediction which is a prediction of the future degradation degree transition of a second battery group included in the battery system and having a degradation degree different from that of the first battery group; A battery degradation degree comparison means for calculating an equalization condition fulfillment timing which is the timing when the first and second battery groups satisfy a predetermined equalization condition based on the first and second transition predictions; A system expansion timing calculation means for determining or proposing a system expansion timing which is the timing for adding secondary batteries to the battery system based on the equalization condition fulfillment timing; A program for causing the computer to function as such.

Images