JP7195767B2 - Determination method of deterioration of zinc battery - Google Patents

Description

One aspect of the present invention relates to a method for determining deterioration of a zinc battery.

Conventionally, a technique for determining deterioration of a storage battery is known. For example, Patent Literature 1 describes a method for estimating the state of deterioration of a rechargeable battery. This method comprises the steps of: generating a coulomb count value by integrating charging and discharging currents of the battery; monitoring the state of the battery; and detecting the change amount ΔX according to the state of the battery measured during the period in which the predetermined amount of charge is charged/discharged. and changing only

JP 2017-116522 A

Since the above estimation method considers the integrated value, it takes a long time to monitor a zinc battery using this estimation method. Therefore, it is desired to determine the deterioration of the zinc battery more easily.

A method for determining deterioration of a zinc battery according to one aspect of the present invention includes an acquisition step of acquiring the discharge capacity and the charge capacity in one cycle of the zinc battery, and a calculation of calculating a charge/discharge rate that is the ratio of the charge capacity to the discharge capacity. and a determination step of determining deterioration of the zinc battery based on the charge/discharge rate.

In this aspect, whether or not the zinc battery has deteriorated is determined based on the relationship between the discharge capacity and the charge capacity obtained in one cycle of the zinc battery. Since the determination can be made based on the information obtained in one cycle, deterioration of the zinc battery can be determined more easily.

According to one aspect of the present invention, deterioration of a zinc battery can be determined more easily.

1 is a diagram schematically showing an example of a configuration of a power storage system and its surroundings; FIG. 3 is a diagram showing the functional configuration of a general controller according to the embodiment; FIG. 4 is a flow chart showing the operation of the general controller according to the embodiment; 6 is a flowchart showing a specific example of determination processing; 4 is a graph showing an example of change in charge/discharge rate; 6 is a flowchart showing a specific example of determination processing; 6 is a flowchart showing a specific example of determination processing;

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

[Overall configuration of power storage system]
The power storage system 1 is a system that stores generated electricity and supplies the stored electricity as needed. The scene to which the power storage system 1 is applied is not limited, and for example, the power storage system 1 can be applied to both real estate and movable property. As an example of application to real estate, the power storage system 1 may manage electricity generated using renewable energy, and can be used in various places such as homes, offices, factories, and farms. As an example of application to movable property, the power storage system 1 may be installed as a power source in a moving object such as an automobile.

An overview of a power system including a power storage system 1 will be described with reference to FIG. 1 . FIG. 1 is a diagram schematically showing an example of the configuration of a power storage system 1 and its surroundings. The power storage system 1 is provided between a supply element 2 capable of supplying power to the power storage system 1 and a demand element 4 capable of receiving power from the power storage system 1 . A DC system including the power storage system 1 and the supply element 2 and an AC system including the demand element 4 are electrically connected via a PCS (Power Conditioning System) 3 . The power storage system 1, the supply element 2, and the PCS 3 are electrically connected via a DC (Direct Current) bus 6 through which direct current flows. The demand element 4 and the PCS 3 are electrically connected via an AC (Alternating Current) bus 7 through which alternating current flows. Electricity generated by the supply element 2 or electricity stored in the storage system 1 is supplied to the demand element 4 . The power storage system 1 may serve to mitigate fluctuations in power supply from the supply element 2 to the demand element 4 by using the storage battery as a cushion.

Supply element 2 is a device or facility capable of supplying power to power storage system 1 . The type of supply element 2 is not limited at all. For example, the supply element 2 may be a generator that uses renewable energy to generate electricity. The type of power generation method and power generation device is not limited at all, and for example, the power generation device may be a solar power generation device or a wind power generator. Alternatively, the feed element 2 may be a motor mounted on a mobile.

Demand element 4 is a device or facility capable of receiving power from power storage system 1 . The type of demand element 4 is also not limited at all. For example, the supply element may be an external power system, which is a commercial power supply facility that integrates generation, transformation, transmission, and distribution. For example, an external power grid is provided by a power company. Alternatively, demand element 4 may be a load, which is a collection of one or more appliances or devices that consume power. Examples of loads include a collection of one or more different household or commercial appliances and any component of any device.

The PCS 3 is a device that converts direct current electricity into alternating current, and is a type of power converter. PCS 3 has a DC terminal connected to DC bus 6 and an AC terminal connected to AC bus 7 .

The power storage system 1 includes a power storage device 10 , a power converter 20 and an integrated controller 30 . One power converter 20 corresponds to one power storage device 10, and these two devices are electrically connected via a DC bus. A set of corresponding power storage device 10 and power converter 20 can also be referred to as a power storage unit. In the example of FIG. 1, the power storage system 1 includes three sets of power storage devices 10 and power converters 20 (three power storage units), but the number of sets is not limited, and may be one, two, or four or more. When there are a plurality of power storage units, the performance of the power storage device 10 (e.g., rated capacity, response speed, etc.) and the performance of the power converter 20 (e.g., rated output, response speed, etc.) may be unified, It does not have to be unified. Overall controller 30 is communicatively connected to each power storage device 10 and each power converter 20 via communication line 40 .

The power storage device 10 is a device that converts electricity provided from the supply element 2 into chemical energy and stores the chemical energy, and is chargeable and dischargeable. Power storage device 10 can also be used to mitigate (smooth) fluctuations in the DC power provided from supply element 2 . The power storage device 10 includes a zinc battery (zinc secondary battery) 11 including a plurality of cells connected in series. Examples of zinc batteries 11 include, but are not limited to, nickel-zinc batteries, silver-zinc oxide batteries, and the like. The number of cells constituting the zinc battery 11 is not limited, and may be seven or eight, for example. Power storage device 10 further includes a control function such as a battery control unit (BCU), which allows data regarding power storage device 10 to be transmitted to overall controller 30 .

Power converter 20 is a device that controls charging and discharging of power storage device 10 . Power converter 20 receives an instruction signal (data signal) from overall controller 30 and controls charging and discharging of power storage device 10 based on the instruction signal. The power converter 20 stores electricity supplied from the supply element 2 in the power storage device 10 in the charge mode, discharges the power storage device 10 in the discharge mode to supply power to the outside, and performs charging and discharging in the stop state. No. Power converter 20 may be, for example, a DC/DC converter.

The general controller 30 is a computer (for example, a microcomputer) that controls the power storage device 10 and the power converter 20 . FIG. 2 is a diagram showing the functional configuration of the general controller 30. As shown in FIG. As shown in this figure, the general controller 30 comprises a processor 101, a memory 102, and a communication interface 103 as hardware devices. The processor 101 is a CPU, for example, and the memory 102 is a flash memory, for example. Each function of the general controller 30 is implemented by the processor 101 executing a program stored in the memory 102 . For example, the processor 101 executes a predetermined operation on data read from the memory 102 or data received via the communication interface 103, and outputs the operation result to another device, thereby Control. Alternatively, processor 101 stores the received data or operation results in memory 102 . The general controller 30 may be composed of one computer, or may be composed of a collection of a plurality of computers (that is, a distributed system).

The general controller 30 may be connected to the monitoring computer 8 via the communication network 41 . The configuration of communication network 41 is not limited, and may be constructed using at least one of the Internet and an intranet, for example. The monitoring computer 8 is a computer that monitors the status of the power storage system 1 . The type of monitoring computer 8 is not limited. For example, monitoring computer 8 may be a portable or stationary personal computer. Alternatively, the monitoring computer 8 may be a mobile terminal such as a high-performance mobile phone (smartphone), mobile phone, personal digital assistant (PDA), or tablet. The monitoring computer 8 may be part of the power storage system 1 or may be provided in a computer system separate from the power storage system 1 .

One of the features of the power storage system 1 is the method of determining the deterioration of the zinc battery, and this feature is realized particularly by the general controller 30 . The function and configuration of the general controller 30 relating to the determination process will be described below.

The processor 101 functions as an acquisition unit 31 , a calculation unit 32 , a determination unit 33 and an output unit 34 . The acquisition unit 31 is a functional element that acquires the discharge capacity and charge capacity in one cycle of the zinc battery 11 . In this specification, a charge-discharge cycle that is a combination of one charge performed over a certain period of time and one discharge performed over a period of time before or after the charging is simply referred to as a "cycle." Also called The calculator 32 is a functional element that calculates the charge/discharge rate, which is the ratio of the charge capacity to the discharge capacity. The determination unit 33 is a functional element that determines the state of deterioration of the zinc battery 11 based on the charge/discharge rate. The output unit 34 is a functional element that outputs data based on the determination. The deterioration state is a concept indicating how much the performance of the zinc battery 11 has deteriorated from the initial state (state at the time of manufacture). A typical deterioration of the zinc battery 11 is an internal short circuit caused by dendrites (needle-like or dendrite-like crystals) growing from the surface of the negative electrode (zinc electrode) breaking through the separator and reaching the positive electrode. The extent of deterioration of the zinc battery 11 can depend on the extent of dendrite growth.

Memory 102 stores information necessary for the operation of processor 101 . For example, memory 102 stores decision rules 35 . The determination rule 35 is information used to determine the deterioration state. The description method of the judgment rule 35 is not limited. For example, the determination rule 35 may be represented by any one of a formula, a threshold value, an algorithm, and a correspondence table, or may be represented by any combination of two or more of formulas, threshold values, algorithms, and a correspondence table. . Alternatively, decision rule 35 may be part of a program executed by processor 101 .

The decision rule 35 may be rewritable. For example, when power storage device 10 or zinc battery 11 is replaced with a different type, or when a new type of power storage device 10 or zinc battery 11 is added, the administrator can change memory 102 according to the configuration change. Rewrite the judgment rule 35 in . In this case, the administrator accesses the general controller 30 with a computer for management (not shown) via a predetermined communication network (not shown), and updates the general controller 30 with a new determination rule 35 reflecting the configuration change. may be transferred to This transfer rewrites the determination rule 35 in the memory 102 .

A communication interface 103 cooperates with the processor 101 to transmit and receive data. For example, the communication interface 103 cooperates with the acquisition unit 31 to receive data regarding the zinc battery 11 . Also, the communication interface 103 cooperates with the output unit 34 to transmit data based on the determination.

[Operation of general controller]
With reference to FIGS. 3 to 7, the operation of the general controller 30 will be described, and a method of determining deterioration of zinc batteries according to the present embodiment will be described. FIG. 3 is a flowchart showing an example of the operation of the general controller 30, specifically showing processing for one power storage device 10. FIG. 4, 6, and 7 are flow charts showing specific examples of determination processing. FIG. 5 is a graph showing an example of changes in charge/discharge rate.

In step S11, the acquisition unit 31 acquires the discharge capacity and charge capacity (both units are Ah) in one cycle of the zinc battery 11 (acquisition step). The discharge capacity and charge capacity in one cycle are a combination of the discharge capacity in one discharge performed over a certain period of time and the charge capacity in one charge performed over a period of time before or after the discharge. be. For example, the acquiring unit 31 may acquire the discharge capacity and the charge capacity in the cycle immediately before the current cycle, or may acquire the discharge capacity and the charge capacity in the cycle two or more cycles before the current cycle. Acquisition unit 31 may acquire the charged capacity and the discharged capacity from power storage device 10 or from another device.

In step S12, the calculator 32 calculates the charge/discharge rate, which is the ratio of the charge capacity to the discharge capacity (calculation step). In addition, although the charging/discharging rate is expressed in percentage in the present embodiment, expression in percentage is not essential. Assuming that the charge/discharge rate (%) is R, the discharge capacity (Ah) is _Cd , and the charge capacity (Ah) is _Cc , the charge/discharge rate is expressed by the following formula (1).
R= _Cc / _Cd *100 (1)

In step S13, the determination unit 33 determines the deterioration state of the zinc battery 11 based on the charge/discharge rate (determination step). A specific method for determining the deterioration state is not limited to one, and the determination unit 33 may determine the deterioration state using various methods.

FIG. 4 shows an example of determination processing (determination step). In step S111, the determination unit 33 compares the charge/discharge rate with the threshold value Ta. If the charge/discharge rate is less than Ta (NO in step S111), the process proceeds to step S112, and determination unit 33 determines that zinc battery 11 is in a normal state. A normal state means that the zinc battery 11 has not deteriorated or the degree of deterioration is negligibly small. On the other hand, if the charge/discharge rate is Ta or more (YES in step S111), the process proceeds to step S113, and determination unit 33 further compares the charge/discharge rate with threshold value Tb. This threshold Tb is a value larger than the threshold Ta.

Specific values of the threshold Ta and the threshold Tb are not limited. The inventors of the present invention have found that these thresholds can be set as follows in consideration of the characteristics of the zinc battery 11 . That is, when the charge/discharge rate is 101% or 102%, it can be said that the zinc battery 11 is normal. If the charge/discharge rate exceeds a higher value (eg, 105%), dendrites may be growing within the zinc battery 11 and thus the possibility of an internal short circuit should become a concern. If the charge/discharge rate is even higher (for example, if it exceeds 110%), the dendrite may have grown considerably, and it is expected that there is a high probability that an internal short circuit will occur in the relatively near future.

FIG. 5 shows actual test results regarding such changes in charge/discharge rate. In this test, a nickel-zinc battery with a rated capacity of 8 Ah, which is an example of a zinc battery, was operated at an ambient temperature of 25°C. First, the initial discharge capacity and initial charge capacity of the nickel-zinc battery were confirmed to determine the charge/discharge rate (step S1). Conditions for this confirmation (referred to as "check conditions") are shown below.
[Check condition (discharge)]
・Discharge to DC bus ・Depth of discharge (DOD): 100%
・Current: 8A
・Final voltage: 1.1V
・Sampling interval: 1 second [Check condition (charging)]
・Constant Current-Constant Voltage (CC-CV)
・Current: 8A (cutoff current: 0.4A)
・Voltage: 1.9V
・Pause time after charging: 12 hours or more ・Sampling interval: 1 second

After that, 50 cycles with a DOD of 50% were performed, and in each cycle, the discharge capacity and charge capacity were checked to obtain the charge/discharge rate (step S2). Conditions for confirmation in each cycle (referred to as "cycle conditions") are shown below.
[Cycle conditions (discharge)]
・Discharge to DC bus ・DOD: 50%
・Current: 2A
・Discharge capacity: 4 Ah
・Pause time after discharge: 0
・Sampling interval: 1 second [Cycle conditions (charging)]
・Constant current constant voltage (CC-CV)
・Current: 8A (cutoff current: 0.4A)
・Voltage: 1.9V
・Pause time after charging: 0
・Sampling interval: 1 second

Every time the above-described cycle with a DOD of 50% was performed 50 times, the discharge capacity and the charge capacity were checked under the above check conditions to obtain the charge/discharge rate (step S3). In this process, when the discharge capacity became less than 4 Ah, it was determined that the nickel-zinc battery had reached the end of its life, and when the discharge capacity remained at 4 Ah, steps S2 and S3 were repeated (step S4).

FIG. 5 shows the charge/discharge rate in each cycle obtained from the test consisting of these steps S1-S4. The vertical axis of the graph indicates the charge/discharge rate (%) under cycle conditions, and the horizontal axis indicates the number of cycles (1 to 300). The discharge capacity under the check conditions was about 8.1 Ah at the initial point (when the number of cycles was 0), and decreased to about 5.6 Ah when the number of cycles was 250. When the number of cycles reached 300, the discharge capacity under the check conditions reached 3.5 Ah.

In this test, the charge/discharge rate exceeded 105% for the first time at the 236th cycle (approximately 105.1%). After that, the charge/discharge rate continued to increase and exceeded 110% for the first time at the 259th cycle (about 110.2%). The charge/discharge rate continued to increase after that, reaching about 120.5% at the 300th cycle.

Based on the findings obtained from the above tests and the like, the threshold (second threshold) Ta may be, for example, a value between 103% and 109%, such as 103%, 104%, 105%, 106%, It may be 107%, 108% or 109%. The threshold (first threshold) Tb may be, for example, 110% or more, and may be, for example, 110%, 111%, 112%, or 113%.

Return to FIG. If the charge/discharge rate is equal to or higher than Tb (YES in step S113), the process proceeds to step S114, and determination unit 33 determines that zinc battery 11 is in the first deteriorated state. The first deterioration state refers to a state in which the degree of deterioration of the zinc battery 11 is relatively large. On the other hand, if the charge/discharge rate is less than Tb (NO in step S113), that is, if the charge/discharge rate is Ta or more and less than Tb, the process proceeds to step S115, and determination unit 33 determines that zinc battery 11 is the second battery. It is judged to be in a deteriorated state. The second deterioration state refers to a state in which the degree of deterioration of the zinc battery 11 is smaller than that of the first deterioration state. As long as this relationship is maintained, the specific meanings of the first deterioration state and the second deterioration state are not limited. For example, the first state of deterioration may correspond to a state in which dendrites are expected to grow to such an extent that an internal short circuit is likely to occur in the relatively near future. The second state of deterioration may correspond to a state in which dendrites are present, but dissolution of the dendrites due to discharge of the zinc electrode may improve the performance of the zinc battery 11 .

In the example shown in FIG. 4, the determination unit 33 determines the deterioration of the zinc battery 11 in two stages of the first deterioration state and the second deterioration state, but the determination unit 33 includes the first deterioration state and the second deterioration state. The deterioration of the zinc battery may be determined in three or more stages.

FIG. 6 shows another example of determination processing (determination step). In step S121, the determination unit 33 compares the charge/discharge rate with the threshold value Ta. If the charge/discharge rate is less than Ta (NO in step S121), the process proceeds to step S122, and determination unit 33 determines that zinc battery 11 is in a normal state.

On the other hand, if the charge/discharge rate is equal to or higher than Ta (YES in step S121), the process proceeds to step S123, and the determination unit 33 keeps the state (monitoring target state) that "the charge/discharge rate is equal to or higher than the threshold value Ta". to obtain the number n of occurrences. In other words, the determination unit 33 identifies how many cycles the monitored state has occurred consecutively. Each time the determination unit 33 determines the state of the zinc battery 11, the determination result is recorded in the memory 102 as a history, and by referring to the history in step S123, the number of times n can be obtained.

If the number of times n is less than the threshold value Tc (NO in step S124), the process proceeds to step S122, and determination unit 33 determines that zinc battery 11 is in a normal state. On the other hand, if the number of times n is greater than or equal to the threshold value Tc (YES in step S124), the process proceeds to step S125, and the determination unit 33 determines that the zinc battery 11 is in the first deteriorated state. A specific value of the threshold Tc is not limited, and may be set based on any criteria. For example, threshold Tc may be set in consideration of various factors such as the characteristics of zinc battery 11 .

Since the zinc that constitutes the negative electrode repeats deposition and dissolution, the dendrites do not necessarily grow monotonically over time, and the dendrites temporarily disappear (the amount of dendrites protruding from the negative electrode surface temporarily lower). Therefore, considering such characteristics of dendrites, the determining unit 33 may determine the state of deterioration of the zinc battery 11 based on a plurality of charging/discharging rates in a plurality of continuous charging/discharging cycles. If the charge/discharge rate continues to be relatively high, dendrites are expected to grow to a certain extent, and it can be determined that the zinc battery 11 has deteriorated to some extent.

FIG. 7 shows still another example of determination processing (determination step). In step S131, the determination unit 33 compares the charge/discharge rate with the threshold value Ta. If the charge/discharge rate is less than Ta (NO in step S131), the process proceeds to step S132, and determination unit 33 determines that zinc battery 11 is in a normal state. On the other hand, if the charge/discharge rate is Ta or more (YES in step S131), the process proceeds to step S133, and determination unit 33 further compares the charge/discharge rate with threshold value Tb (Tb>Ta). Specific values of the threshold Ta and the threshold Tb may be set in the same manner as in the example of FIG.

If the charge/discharge rate is equal to or higher than Tb (YES in step S133), the process proceeds to step S134, and determination unit 33 determines that zinc battery 11 is in the first deteriorated state.

On the other hand, if the charge/discharge rate is less than Tb (NO in step S133), the process proceeds to step S135, and the determination unit 33 keeps the state (monitoring target state) that "the charge/discharge rate is equal to or greater than the threshold value Ta". to obtain the number n of occurrences.

If the number of times n is less than the threshold value Tc (NO in step S136), the process proceeds to step S132, and determination unit 33 determines that zinc battery 11 is in a normal state. On the other hand, if the number of times n is greater than or equal to the threshold value Tc (YES in step S136), the process proceeds to step S134, and the determination unit 33 determines that the zinc battery is in the first deteriorated state.

The example shown in FIG. 7 can also be said to be a combination of the two techniques shown in FIGS.

6 and 7 include processing for determining deterioration of the zinc battery 11 based on the number of times the monitored condition occurs. As a modification of this process, the determination unit 33 replaces the number n of times the state (monitoring target state) that “the charge/discharge rate is equal to or greater than the threshold Ta” (monitoring target state) has occurred consecutively with “the charge/discharge rate is equal to or greater than the threshold Ta The deterioration state may be determined based on the cumulative number m of occurrences of the state (monitoring target state). That is, the determination unit 33 determines that the zinc battery 11 is in a normal state when the cumulative number of occurrences m is less than the threshold value Td, and determines that the zinc battery 11 is in the first deteriorated state when the cumulative number of occurrences m is equal to or greater than the threshold value Td. It may be determined that there is As noted above, dendrites may temporarily dissolve. However, regardless of whether the relatively high charge/discharge rate state occurred continuously or discontinuously, if many such states were detected, it is expected that the dendrites have grown to a certain extent. . Therefore, in such a case, the determination unit 33 may determine that the deterioration of the zinc battery 11 has progressed to some extent. A specific value of the threshold Td is not limited, and may be set based on any criteria. For example, threshold Td may be set in consideration of various factors such as the characteristics of zinc battery 11 .

Alternatively, the determination unit 33 may determine the deterioration state using both the number of consecutive occurrences and the cumulative number of occurrences. For example, the determination unit 33 counts both the number of consecutive occurrences n and the cumulative number of occurrences m. Then, the determination unit 33 determines that the zinc battery 11 is in the first deteriorated state when the number of consecutive occurrences n is equal to or greater than the threshold Tc or the cumulative number of occurrences m is equal to or greater than the threshold Td. In this case, it may be determined that the zinc battery 11 is in a normal state.

When using at least one of the number of continuous occurrences and the cumulative number of occurrences, the determination unit 33 may determine not only the first deterioration state but also the second deterioration state. For the number of consecutive occurrences n, the determination unit 33 uses two thresholds Tc _low and Tc _high (where Tc _low <Tc _high ). Then, the determination unit 33 determines that the zinc battery 11 is in the normal state when n<Tc _low , determines that the zinc battery 11 is in the second deteriorated state when Tc _low ≤ n<Tc _high , and determines that the zinc battery 11 is in the second deteriorated state when Tc _high ≤ In the case of n, the zinc battery 11 may be determined to be in the first deteriorated state. For the cumulative number of occurrences m, the determination unit 33 uses two thresholds Td _low and Td _high (where Td _low <Td _high ). Then, the determination unit 33 determines that the zinc battery 11 is in a normal state when m<Td _low , determines that the zinc battery 11 is in a second deteriorated state when Td _low ≦m<Td _high , and determines that Td _high ≦ In the case of m, the zinc battery 11 may be determined to be in the first deteriorated state. Even when at least one of the number of consecutive occurrences and the number of cumulative occurrences is used, the determination unit 33 may determine the deterioration of the zinc battery in three or more stages including the first deterioration state and the second deterioration state.

As described above, various methods can be adopted for determining the deterioration state. In any case, the determination unit 33 can determine the deterioration state of the zinc battery 11 using a predetermined determination rule 35 (for example, the determination rule 35 including the above threshold).

Returning to FIG. 3 , in step S<b>14 , the output unit 34 outputs data based on the determination by the determination unit 33 . The contents of the data are not limited. For example, the output unit 34 may transmit the determination result (for example, normal state, first deterioration state, or second deterioration state) to the monitoring computer 8 via the communication network 41 . The monitoring computer 8 may perform arbitrary processing such as displaying the judgment result on a monitor or storing it in a database. Alternatively, the output unit 34 may generate a stop instruction and transmit the stop instruction to the corresponding power storage device 10 when the determination result is the first deterioration state. "Send a stop instruction to the power storage device" means that the stop instruction is sent to the power storage device 10 or another device corresponding to the power storage device 10 in order not to charge or discharge the zinc battery 11. Say things. For example, the output unit 34 may transmit a stop instruction to the power converter 20 corresponding to the power storage device 10 via the communication line 40 . The zinc battery 11 of the stopped power storage device 10 is manually replaced with a new one, for example.

When the power storage system 1 includes a plurality of power storage devices 10, the overall controller 30 executes the processes of steps S11 to S14 for all power storage devices 10. FIG. The processes of steps S11 to S14 are repeatedly executed for one power storage device 10 (for example, in each charge/discharge cycle).

[program]
The determination program for causing the computer to function as the general controller 30 includes program codes for causing the computer to function as the acquisition unit 31 , the calculation unit 32 , the determination unit 33 and the output unit 34 . This determination program may be provided after being fixedly recorded in a tangible recording medium such as a CD-ROM, a DVD-ROM, or a semiconductor memory. Alternatively, the determination program may be provided via a communication network as a data signal superimposed on a carrier wave. The provided judgment program is stored in the memory 102, for example. The processor 101 cooperates with the memory 102 to execute the determination program, thereby realizing each of the functional elements described above.

[effect]
As described above, the method for determining deterioration of a zinc battery according to one aspect of the present invention includes an acquisition step of acquiring the discharge capacity and the charge capacity in one cycle of the zinc battery, and a charge capacity ratio of the charge capacity to the discharge capacity. It includes a calculation step of calculating a discharge rate and a determination step of determining deterioration of the zinc battery based on the charge/discharge rate.

In this aspect, whether or not the zinc battery has deteriorated is determined based on the relationship between the discharge capacity and the charge capacity obtained in one cycle of the zinc battery. Since the determination can be made based on the information obtained in one cycle, deterioration of the zinc battery can be determined more easily. Since the charge/discharge rate tends to change greatly when the performance of zinc batteries deteriorates, this method, which can determine the state of deterioration even from the charge/discharge rate of one cycle, is suitable for specifying zinc batteries. .

In a method for determining deterioration of a zinc battery according to another aspect, in the determining step, it may be determined that the zinc battery is in a deteriorated state when the charge/discharge rate is equal to or higher than a threshold. A simple process of comparing the charge/discharge rate to a threshold can determine the deterioration of a zinc battery.

In the method for determining deterioration of a zinc battery according to another aspect, in the determination step, if the charge/discharge rate is equal to or higher than the first threshold, the zinc battery is determined to be in the first deterioration state, and the charge/discharge rate is the second It may be determined that the zinc battery is in a second deteriorated state with a degree of deterioration smaller than that in the first deteriorated state when it is equal to or more than the threshold and less than the first threshold. The state of deterioration of zinc batteries can depend on the extent of dendrite growth. By determining the state of deterioration in multiple stages using a plurality of thresholds, it is possible to accurately determine the state of deterioration in consideration of such characteristics of zinc batteries.

In a method for determining deterioration of a zinc battery according to another aspect, the first threshold may be 110% or more, and the second threshold may be a value between 103% and 109%. By using such values as thresholds, it is possible to accurately determine the state of deterioration of the zinc battery.

In a method for determining deterioration of a zinc battery according to another aspect, in the determining step, deterioration of the zinc battery may be determined based on the number of occurrences of a monitored state in which the charge/discharge rate is equal to or greater than a threshold. Dendrites grow slowly in zinc batteries. By determining the deterioration state based on the history of the charge/discharge rate in multiple cycles (the number of times the charge/discharge rate was equal to or higher than the threshold), the deterioration state of such a zinc battery can be accurately determined. .

In the method for determining deterioration of a zinc battery according to another aspect, in the determination step, the zinc battery is determined to be in a deteriorated state when the number of times the monitored state has occurred continuously is equal to or greater than a predetermined threshold. You may By considering the number of consecutive occurrences of the monitored state, the state of deterioration of the zinc battery can be accurately determined.

In the method for determining deterioration of a zinc battery according to another aspect, the determining step determines that the zinc battery is in a deteriorated state when the cumulative number of occurrences of the monitored state is equal to or greater than a predetermined threshold. may By considering the accumulated number of occurrences of the monitored condition, the deterioration condition of the zinc battery can be accurately determined.

In a method for determining deterioration of a zinc battery according to another aspect, the zinc battery may be a nickel-zinc battery. In this case, deterioration of the nickel-zinc battery can be determined more easily.

[Modification]
The present invention has been described in detail based on its embodiments. However, the present invention is not limited to the above embodiments. Various modifications are possible for the present invention without departing from the gist thereof.

For example, the processing procedure of the zinc battery deterioration determination method executed by at least one processor is not limited to the example in the above embodiment. For example, some of the steps (processes) described above may be omitted, or the steps may be performed in a different order. Also, any two or more of the steps described above may be combined, and some of the steps may be modified or deleted. Alternatively, other steps may be performed in addition to the above steps.

When comparing the magnitude relationship between two numerical values in the power storage system 1, either of the two criteria of "greater than" and "greater than" may be used, and the two criteria of "less than" and "less than" may be used. You can use either of Selection of such a criterion does not change the technical significance of the process of comparing two numerical values.

In the above embodiment, the general controller 30 executes the zinc battery deterioration determination method, but part or all of this method may be performed manually.

REFERENCE SIGNS LIST 1 power storage system, 2 supply element, 3 PCS, 4 demand element, 6 DC bus, 7 AC bus, 8 monitoring computer, 10 power storage device, 11 zinc battery, 20 power converter, 30... Supervisory controller, 31... Acquisition unit, 32... Calculation unit, 33... Judgment unit, 34... Output unit, 35... Judgment rule, 40... Communication line, 41... Communication network.

Claims (5)

an obtaining step of obtaining the discharge capacity and charge capacity in one cycle of the zinc battery;
a calculating step of calculating a charge/discharge rate that is the ratio of the charge capacity to the discharge capacity;
a determination step of determining deterioration of the zinc battery based on the charge/discharge rate;
In the determination step, using a first rate threshold, a second rate threshold smaller than the first rate threshold , a first number threshold, and a second number threshold smaller than the first number threshold ,
When the number of occurrences of the monitoring target state in which the charge/discharge rate is equal to or greater than the second rate threshold and less than the first rate threshold is equal to or greater than the first threshold , the zinc battery is in the first deteriorated state . determine that there is
When the number of occurrences of the monitoring target state is equal to or greater than the second threshold value and less than the first threshold value, the zinc battery is in a second deteriorated state in which the degree of deterioration is smaller than that in the first deteriorated state. determine that there is
determining that the zinc battery is in the first deteriorated state when the charge/discharge rate is equal to or greater than the first rate threshold;
Method for determining deterioration of zinc batteries. the first percentage threshold is greater than or equal to 110% and the second percentage threshold is between 103% and 109%;
The method for determining deterioration of a zinc battery according to claim 1 . wherein the number of occurrences of the monitored condition includes a number of consecutive occurrences indicating the number of consecutive occurrences of the monitored condition;
wherein the first count threshold includes a first consecutive count threshold;
wherein the second count threshold includes a second consecutive count threshold;
In the determination step,
determining that the zinc battery is in the first deteriorated state when the number of consecutive occurrences is equal to or greater than the first consecutive number threshold;
Determining that the zinc battery is in the second deteriorated state when the number of consecutive occurrences is equal to or greater than the second consecutive number threshold and less than the first consecutive number threshold.
A method for determining deterioration of a zinc battery according to claim 1 or 2 . wherein the number of occurrences of the monitored condition includes a cumulative number of occurrences indicating a cumulative number of times the monitored condition has occurred;
wherein the first count threshold includes a first cumulative count threshold;
wherein the second count threshold includes a second cumulative count threshold;
In the determination step,
Determining that the zinc battery is in the first deterioration state when the cumulative number of occurrences is equal to or greater than the first cumulative number threshold,
Determining that the zinc battery is in the second deteriorated state when the cumulative number of occurrences is equal to or greater than the second cumulative number threshold and less than the first cumulative number threshold.
A method for determining deterioration of a zinc battery according to any one of claims 1 to 3 . the zinc battery is a nickel-zinc battery;
A method for determining deterioration of a zinc battery according to any one of claims 1 to 4 .

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