JP2024018139A - Estimation device, estimation method and computer program - Google Patents

Abstract

An object of the present invention is to improve the accuracy of estimating deterioration of a power storage element. An estimation device for estimating deterioration of a power storage element does not substantially increase a deterioration value indicating deterioration during the initial period of operation of the power storage element, while the characteristics are maintained or improved. [Selection diagram] Figure 9

Description

The present invention relates to an estimation device, an estimation method, and a computer program for estimating deterioration of a power storage element.

Patent Document 1 discloses a technology that acquires time-series data of the state of charge (SOC) of a power storage element and estimates a deterioration value indicating deterioration of the power storage element so that it increases according to the magnitude of fluctuation in the SOC. ing.

JP2018-060828A

There is still room for improvement in order to increase the accuracy of estimating the deterioration of power storage elements.

One aspect of the present invention provides an estimation device, an estimation method, and a computer program that can improve the accuracy of estimating deterioration of a power storage element.

An estimation device for estimating deterioration of a power storage element according to one aspect of the present invention does not substantially increase a deterioration value indicating deterioration while the characteristics of the power storage element are maintained or improved during the initial operation of the power storage element. .

According to the above aspect, the accuracy of deterioration estimation can be improved by considering the maintenance/improvement of the characteristics of the power storage element observed in the initial stage of operation.

FIG. 1 is a diagram showing an overview of a remote monitoring system. FIG. 3 is a diagram illustrating an example of a hierarchical structure of a group of power storage modules and a connection form of communication devices. FIG. 2 is a block diagram showing the internal configuration of devices included in the remote monitoring system. FIG. 3 is a schematic diagram showing the operation of a deterioration simulator. It is a graph showing the relationship between the number of cycles and the capacity deterioration rate (deterioration value). It is a graph showing the transition of the capacity deterioration rate according to the magnitude of the SOC fluctuation of the power storage element in the early stage of operation. FIG. 3 is a diagram illustrating deterioration behavior when the magnitude of SOC fluctuation is changed during initial operation. 7 is a graph showing changes in capacity deterioration rate depending on temperature. FIG. 6 is a diagram illustrating a method for not substantially increasing the deterioration value while the characteristics of the power storage element are maintained or improved. 12 is a flowchart illustrating another calculation procedure for capacity deterioration rate. 11 is a diagram that provides supplementary explanation of the calculation procedure in FIG. 10. FIG.

An overview of the embodiment will be described below.
(1) The estimation device that estimates the deterioration of the power storage element does not substantially increase the deterioration value indicating deterioration while the characteristics of the power storage element are maintained or improved during the initial period of operation of the power storage element.

In this specification, a "power storage element" may include a plurality of power storage cells, a plurality of power storage modules (power storage packs), or a plurality of banks (strings). Alternatively, the "power storage element" may be a single power storage cell.
The "characteristics" may be the full charge capacity of the power storage element or the high rate characteristics, but are not limited thereto.
The "deterioration value" is preferably a capacity deterioration rate that indicates the degree of decrease in full charge capacity as a percentage. Alternatively, the "deterioration value" may be a value that reflects other deterioration factors such as an increase in internal resistance (ohmic resistance, non-ohmic resistance).
"Do not substantially increase the deterioration value" may mean that (a) the deterioration value is maintained at a value near zero while the characteristics of the electricity storage element are maintained or improved; b) By gradually increasing the deterioration value that has been set to a negative initial value, the deterioration value may not be increased to a positive value.

The present inventor focused on the fact that in electricity storage cells such as lithium ion batteries, the characteristics are maintained/improved, such as the full charge capacity increasing during the initial stage of operation (early stage of charge/discharge cycle), and the above-mentioned configuration was developed. I came up with this idea. The increase in full charge capacity is due to penetration of electrolyte into the positive electrode plate, negative electrode plate, separator, between the positive electrode plate or negative electrode plate and the separator, or due to charging and discharging of the storage cell (expansion of the positive electrode active material). This is presumed to be due to the fact that cracks occur in the secondary particles of the positive electrode active material due to shrinkage), increasing the surface area of the positive electrode active material that contributes to charge/discharge reactions, and improving high rate characteristics.
The conventional estimated straight line that simulates the deterioration value by starting to increase from the beginning of the cycle, shown by the solid line in Fig. may deviate from the straight line). This is because the conventional estimated straight line does not take into account the maintenance/improvement of the characteristics of the power storage element, which is observed in the initial stage of operation.
As shown by the approximate straight line indicated by the broken line in Figure 5, considering the maintenance/improvement of the characteristics of the energy storage element during the initial period of operation (for example, up to about 200 to 350 cycles), the deterioration value substantially increases during the operation period. By not allowing this, the accuracy of deterioration estimation can be improved.
The horizontal axis in FIG. 5 indicates the number of times (cycle number) that charging and discharging were repeated between SOC zero and 100%. The term "cycle" used herein is not limited to this example, and may be repeated partial charging and discharging in the range of SOC from zero to 100%.

(2) The estimation device according to (1) above may make a decision regarding an increase in the deterioration value based on the magnitude of a change in SOC (State of Charge) at an initial stage of operation of the power storage element. .

The present inventor discovered that different deterioration behavior occurs depending on the magnitude of SOC fluctuation in the initial stage of operation of a power storage element, and came up with the above configuration. With the above configuration, it is possible to improve the accuracy of estimating deterioration of the power storage element.

(3) In the estimation device according to (2) above, the greater the magnitude of the SOC fluctuation, the greater the full charge capacity of the power storage element at the initial stage of operation, and the more the full charge capacity of the power storage element is increased. , the deterioration value may be increased.

As shown in FIG. 6, the capacity deterioration rate of the power storage element in the initial stage of operation may take a negative value (that is, the full charge capacity increases) as the number of cycles increases. In FIG. 6, the solid line shows the change in capacity deterioration rate when the storage element is charged and discharged between SOC 75 and 100%, and the broken line shows the change in capacity deterioration rate when the storage element is charged and discharged between SOC 0 and 100%. The graph shows the change in capacity deterioration rate. There is a tendency that the larger the SOC fluctuation is, the larger the capacity deterioration rate of the power storage element in the initial stage of operation takes a negative value (that is, the full charge capacity increases). Therefore, by considering this tendency (reflecting it in the estimation), it is possible to improve the accuracy of estimating the deterioration of the power storage element.

(4) In the estimation device according to (2) or (3) above, the SOC of the power storage element fluctuates at a first magnitude (amplitude) until a predetermined number of cycles, and then becomes larger than the first magnitude. When the SOC of the power storage element fluctuates by a second magnitude, the full charge capacity of the power storage element at the initial stage of operation is increased based on the second magnitude, and the full charge capacity of the power storage element with increased full charge capacity is increased. , the deterioration value may be increased.

Line A in FIG. 7 shows the change in capacity deterioration rate when the storage element is charged and discharged at an SOC of zero to 100% from the start of operation. Line B in FIG. 7 indicates that after charging and discharging the storage element at a SOC of 75% to 100% as shown by the broken line, the storage element is charged and discharged to a SOC of 75% to 100% as shown by the solid line. This is the change in capacity deterioration rate when discharging. Even when the SOC of the power storage element fluctuates from the first magnitude to the second magnitude as shown by polygonal line A, the SOC of the power storage element fluctuates from the first magnitude to the second magnitude during the cycle as shown by polygonal line B. Even when the size changes, the full charge capacity of the power storage element tends to increase to the same extent. By considering this tendency (reflecting it in the estimation), it is possible to improve the accuracy of estimating the deterioration of the power storage element when the magnitude of SOC fluctuation changes during the cycle at the initial stage of operation.

(5) The estimating device according to any one of (1) to (4) above may determine the increase in the deterioration value based on the temperature at an initial stage of operation of the power storage element.

In this specification, "temperature" may be the surface temperature of the power storage element measured by a sensor, or may be the environmental temperature of the power storage element measured by a thermometer. Alternatively, the "temperature" may be the internal temperature of the power storage element estimated by simulation.
The present inventor discovered that different deterioration behavior occurs depending on the temperature at the initial stage of operation of a power storage element, and came up with the above configuration. The deterioration behavior of the energy storage cell when the temperature is 45°C, shown by the broken line in Figure 8 (an approximate straight line fitting the actual measured values indicated by the triangular points), is the same as the deterioration behavior of the energy storage cell when the temperature is 20°C, shown as the dashed line. The slope is larger than the deterioration behavior (approximate straight line fitting actual measured values indicated by round points). When the temperature is 45° C., there is a tendency for the capacity deterioration rate of the power storage element to take a larger negative value at the initial stage of operation (that is, the full charge capacity increases more). Therefore, by considering this tendency (reflecting it in the estimation), it is possible to improve the accuracy of estimating the deterioration of the power storage element.

(6) The estimation method for estimating the deterioration of the power storage element does not substantially increase the deterioration value indicating deterioration while the characteristics of the power storage element are maintained or improved during the initial operation of the power storage element.
(7) The computer program causes the computer that estimates the deterioration of the power storage element to perform processing that does not substantially increase the deterioration value indicating deterioration during the initial period of operation of the power storage element while the characteristics are maintained or improved. Let it run.

The above estimation method and computer program may be executed by a computer located close to the power storage element, or by a computer located away from the power storage element (for example, an ECU of a mobile object such as a vehicle equipped with the power storage element). (Electronic Control Unit), remote monitoring server, etc.).
Methods equivalent to the configurations described in (2) to (5) above may be applied to the above estimation method and computer program.

Hereinafter, embodiments will be specifically described with reference to the drawings.

FIG. 1 is a diagram showing an overview of a remote monitoring system 100. The remote monitoring system 100 remotely accesses information regarding power storage elements and power supply related devices included in each of the mega solar power generation system S, the thermal power generation system F, the wind power generation system W, and other distributed power sources not shown. is possible. An uninterruptible power supply (UPS) U provided in a data center or the like, a rectifier (DC power supply) or a converter D provided in a stabilized power supply system for railways, etc. may be remotely monitored. The uninterruptible power supply U, the DC power supply, or the converter D has a built-in or connected power storage element.

The mega solar power generation system S, the thermal power generation system F, and the wind power generation system W are provided with a power storage system 101 in which a power conditioner (PCS: Power Conditioning System) P is attached. The power storage system 101 may be configured by a plurality of containers C containing power storage module groups L. Alternatively, the power storage module group L and the power conditioner P may be placed inside a building (power storage room). The power storage module group L includes a plurality of secondary batteries such as lithium ion batteries.

In the remote monitoring system 100, a communication device 1 (see FIG. 2) is installed in each of the power storage systems 101 or devices (P, U, D, and a management device M described later) in the systems S, F, and W to be monitored. Connected. The remote monitoring system 100 includes a communication device 1, a server device 2 (information processing device) that collects information from the communication device 1, a client device 3 (terminal device) for viewing the collected information, and communication between the devices. and a network N which is a communication medium.

The communication device 1 may be a measurement monitor that communicates with a battery management unit (BMU) provided in a power storage element to receive information about the power storage element, or a controller compatible with ECHONET/ECHONETLite (registered trademark). good. The communication device 1 may be an independent device, or may be a network card type device that can be installed in the power conditioner P or the power storage module group L. One communication device 1 is provided for each group consisting of a plurality of power storage modules in order to acquire information about the power storage module group L in the power storage system 101.

The server device 2 includes a web server function, and presents information obtained from the communication device 1 installed/connected to each device to be monitored in response to access from the client device 3.

The network N includes a public communication network N1, which is the so-called Internet, and a carrier network N2 that realizes wireless communication according to a predetermined mobile communication standard. The public communication network N1 includes a general optical line, and the network N includes a dedicated line to which the server device 2 is connected. The carrier network N2 includes a base station BS, and the client device 3 can communicate with the server device 2 via the network N from the base station BS. An access point AP is connected to the public communication network N1, and the client device 3 can send and receive information from the access point AP to the server device 2 via the network N.

The power storage module group L of the power storage system 101 has a hierarchical structure. FIG. 2 shows an example of the hierarchical structure of the power storage module group L and the connection form of the communication device 1. The power storage module group L is configured, for example, in a hierarchical structure of power storage modules in which a plurality of power storage cells are connected in series, and banks in which a plurality of power storage modules are connected in series. In the example of FIG. 2, one management device M is provided for each of the banks numbered (#) 1 to N and for each bank group (also referred to as a domain) in which the banks are connected in parallel. A management device M installed in each bank communicates with a control board (CMU: Cell Management Unit) with a communication function built in each power storage module through serial communication, and collects measurement data ( current, voltage, temperature). Each bank management device M transmits measurement data obtained from each bank's power storage module to a management device M provided in the domain. The domain management device M aggregates information such as measurement data and detected abnormalities obtained from the management devices M of banks belonging to the domain.

Although details are not shown, the electricity storage cell may include a hollow rectangular parallelepiped case and a pair of cell terminals with different polarities provided on one side surface (terminal surface, upper surface) of the case. The case houses an electrode body formed by laminating a positive electrode, a separator, and a negative electrode, and an electrolyte (electrolytic solution).

The electrode body may be constructed by stacking a sheet-like positive electrode and a negative electrode with two sheet-like separators interposed therebetween, and winding them (vertically or horizontally). The separator is formed of a porous resin film. As the porous resin film, a porous resin film made of resin such as polyethylene (PE) or polypropylene (PP) can be used.

The positive electrode is an electrode plate in which a positive electrode active material layer is formed on the surface of a long strip-shaped positive electrode base material made of, for example, aluminum, an aluminum alloy, or the like. The positive electrode active material layer contains a positive electrode active material. As the positive electrode active material used in the positive electrode active material layer, a material capable of intercalating and deintercalating lithium ions can be used. As the positive electrode active material, for example, LiFePO ₄ is used, but the present invention is not limited thereto, and so-called ternary positive electrode active materials may also be used. The positive electrode active material layer may further contain a conductive additive, a binder, and the like.

The negative electrode is an electrode plate in which a negative electrode active material layer is formed on the surface of a long strip-shaped negative electrode base material made of, for example, copper or a copper alloy. The negative electrode active material layer contains a negative electrode active material. As the negative electrode active material, a material capable of intercalating and deintercalating lithium ions can be used. Examples of the negative electrode active material include graphite, hard carbon, and soft carbon. The negative electrode active material layer may further contain a binder, a thickener, and the like.

The electrolyte contained in the case together with the electrode body can be the same as that used in conventional lithium ion secondary batteries. For example, an electrolyte containing a supporting salt in an organic solvent can be used as the electrolyte. As the organic solvent, for example, aprotic solvents such as carbonates, esters, and ethers are used. As the supporting salt, for example, lithium salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ and the like are preferably used. The electrolyte may contain various additives such as, for example, a gas generating agent, a film forming agent, a dispersing agent, and a thickening agent.

The electricity storage cell is not limited to a prismatic cell, and may be a cylindrical lithium ion battery or a laminated (pouch type) lithium ion battery. The storage cell may be a lithium ion battery including a stacked electrode body instead of the wound electrode body. The storage cell may be an all-solid lithium ion battery using a solid electrolyte.

The remote monitoring system 100 uses the communication device 1 installed in each device to transmit information such as the SOC, state of health (SOH), etc., and detected abnormalities in the power storage cells, power storage modules, or banks of the power storage system 101. , server device 2 collects and presents the state of power storage system 101 based on the collected data.

FIG. 3 is a block diagram showing the internal configuration of devices included in the remote monitoring system 100. As shown in FIG. 3, the communication device 1 includes a control section 10, a storage section 11, a first communication section 12, and a second communication section 13. The control unit 10 is a processor using a CPU (Central Processing Unit), and uses built-in memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory) to control each component and execute processing.

The storage unit 11 uses nonvolatile memory such as flash memory. The storage unit 11 stores a device program 1P that the control unit 10 reads and executes. The device program 1P includes communication programs based on SSH (Secure Shell), SNMP (Simple Network Management Protocol), and the like. The storage unit 11 stores information such as information collected through processing by the control unit 10 and event logs. The information stored in the storage unit 11 can also be read out via a communication interface such as a USB whose terminal is exposed on the casing of the communication device 1 . The device program 1P stored in the storage section 11 may be one obtained by reading out the device program 4P stored in the recording medium 4 and copying it into the storage section 11.

The first communication unit 12 is a communication interface that realizes communication with a monitored device to which the communication device 1 is connected. The first communication unit 12 uses, for example, a serial communication interface such as RS-232C or RS-485. For example, the power conditioner P includes a control unit having a serial communication function compliant with RS-485, and the first communication section 12 communicates with the control unit. When the control boards included in the power storage module group L are connected by a CAN (Controller Area Network) bus and communication between the control boards is realized by CAN communication, the first communication unit 12 is a communication interface based on the CAN protocol. . The first communication unit 12 may be a communication interface compatible with the ECHONET/ECHONETLite standard.

The second communication unit 13 is an interface that realizes communication via the network N, and uses a communication interface such as Ethernet (registered trademark) or a wireless communication antenna. The control unit 10 can be communicatively connected to the server device 2 via the second communication unit 13 . The second communication unit 13 may be a communication interface compatible with the ECHONET/ECHONETLite standard.

In the communication device 1 configured in this way, the control unit 10 acquires, via the first communication unit 12, measurement data for the power storage element obtained by the device to which the communication device 1 is connected. The control unit 10 may function as an SNMP agent by reading and executing an SNMP program, and may respond to information requests from the server device 2.

The server device 2 uses a server computer and includes a control section 20, a storage section 21, and a communication section 22. In this embodiment, the server device 2 will be described as one server computer, but processing may be distributed among a plurality of server computers.
In this embodiment, the server device 2 functions as a deterioration simulator (estimation device) 2a, which will be described later.

The control unit 20 is a processor using a CPU or a GPU (Graphics Processing Unit), and uses built-in memories such as ROM and RAM to control each component and execute processing. The control unit 20 executes communication and information processing based on the server program 21P stored in the storage unit 21. The server program 21P includes a web server program, and the control unit 20 functions as a web server that provides web pages to the client device 3. The control unit 20 collects information from the communication device 1 as an SNMP server based on the server program 21P.

The storage unit 21 uses, for example, a hard disk or a nonvolatile memory such as a flash memory. The storage unit 21 stores the above-mentioned server program 21P and data processing program 22P. The server program 21P and data processing program 22P stored in the storage unit 21 may be obtained by reading out the server program 51P and data processing program 52P stored in the recording medium 5 and copying them into the storage unit 21.

The storage unit 21 stores measurement data of the power conditioner P and the power storage module group L of the power storage system 101 to be monitored, which is collected through the processing of the control unit 20 . The measurement data is associated with identification information (number) that identifies the power storage system 101 or the power conditioner P. The measurement data of the power storage module group L is stored according to the domain, bank, module, or cell hierarchical structure.

The communication unit 22 is a communication device that realizes communication connection and transmission and reception of information via the network N. Specifically, the communication unit 22 is a network card compatible with network N.

The client device 3 is a computer used by an operator such as a manager or a maintenance person of the power storage system 101 of the power generation systems S, F, and W. The client device 3 may be a desktop or laptop personal computer, or a so-called smartphone or tablet communication terminal. The client device 3 includes a control section 30, a storage section 31, a communication section 32, a display section 33, and an operation section 34.

The control unit 30 is a processor using a CPU. The control unit 30 causes the display unit 33 to display a web page provided by the server device 2 based on the client program 3P stored in the storage unit 31. The client program 3P is incorporated into a web page provided by the web server function of the server device 2, includes a script and a web browser program that are temporarily stored in the client device 3, and is based on the operation in the server device 2. This is a program for displaying web-based screens.

The storage unit 31 uses, for example, a hard disk or a nonvolatile memory such as a flash memory. The storage unit 31 stores various programs including a client program 3P. The client program 3P may be one that reads the client program 6P stored in the recording medium 6 and copies it into the storage unit 11.

The communication unit 32 uses a communication device such as a network card for wired communication, a wireless communication device for mobile communication that connects to the base station BS (see FIG. 1), or a wireless communication device that supports connection to the access point AP. . The control unit 30 is capable of communication connection or transmission and reception of information with the server device 2 via the network N by the communication unit 32 .

The display unit 33 uses a display such as a liquid crystal display or an organic EL (Electro Luminescence) display. The display unit 33 displays an image of a web page provided by the server device 2 through processing based on the client program 3P of the control unit 30. The display unit 33 is preferably a display with a built-in touch panel, but may be a display without a built-in touch panel.

The operation unit 34 is a user interface such as a keyboard and pointing device, or a voice input unit that can input and output data to and from the control unit 30 . The operation unit 34 may use a touch panel of the display unit 33 or a physical button provided on the housing. The operation unit 34 notifies the control unit 30 of operation information by the user.

In the remote monitoring system 100 configured as described above, the server device 2 monitors the states of the power conditioner P, the power storage module group L (management device M), the uninterruptible power supply U, and the rectifier D based on the data processing program 22P. Various information including information is periodically acquired from the communication device 1 and stored in the storage unit 21. The communication device 1 transmits status information about each power storage module group L with parent-child relationships associated with each other according to the hierarchical structure. The server device 2 displays a screen that visually represents the status of the system or device to be monitored based on the information acquired from the power storage element or each power supply related device using the communication device 1 according to the hierarchical structure of the power storage module group. Information is created, transmitted to the client device 3, and presented.

FIG. 4 is a schematic diagram showing the operation of the deterioration simulator 2a. When the deterioration simulator 2a acquires the SOC time series data and the temperature time series data as input data, it estimates (calculates) the deterioration value of the power storage element. As shown in FIG. 4, the time series data of SOC shows the fluctuation of SOC from time t1 to time tn (for example, the fluctuation of n SOC values at each time point), and the time series data of temperature shows the fluctuation of SOC from time t1 to time tn. The variation of temperature from t1 to time tn (eg, variation of n temperature values from time to time) is shown.

The deterioration simulator 2a can estimate the decrease in SOH (deterioration value) of the power storage element from time t1 to time tn based on the fluctuations in SOC and temperature from time t1 to time tn. If the SOH at time t1 is SOHt1 and the SOH at time tn is SOHtn, the deterioration value is (SOHt - SOHtn). That is, if the SOH at time t1 is known, the SOH at time tn can be determined based on the deterioration value. Here, the time t1 can be a certain time in the past, the present, or the future, and the time tn can be a time when a predetermined time has elapsed from the time t1 toward the future. The time difference between the time t1 and the time tn is a period for which the deterioration simulator 2a predicts deterioration, and can be set as appropriate depending on how far into the future the deterioration value is to be predicted. The time difference between time t1 and time tn can be, for example, one month, half a year, one year, or two years.

In the example of FIG. 4, temperature time series data is input to the deterioration simulator 2a, but instead of the temperature time series data, a representative temperature (for example, the average temperature from time t1 to time tn) is input to the deterioration simulator 2a. It may also be input to the simulator 2a.

The deterioration simulator 2a in this embodiment substantially reduces the deterioration value indicating deterioration (in this embodiment, the deterioration rate of full charge capacity) while the characteristics are maintained or improved during the initial operation of the power storage element. Do not increase. A specific example of a method for that purpose will be explained using FIG. 9.

FIG. 9 shows a method of maintaining the deterioration value at zero (without increasing the capacity deterioration rate as the number of cycles increases) while the characteristics of the power storage element are maintained/improved.

The deterioration simulator 2a estimates the extent to which the characteristics of the power storage element will be maintained/improved based on the magnitude of SOC fluctuation and temperature at the initial stage of operation of the power storage element, and calculates the capacity deterioration rate from any number of cycles to a positive value. Decide whether to increase the value. In the estimated straight line in FIG. 9, the capacity deterioration rate increases as a positive value from around 350 cycles. The capacity deterioration rate is maintained at zero until 350 cycles. In other words, the cycle deterioration value is maintained at zero while the full charge capacity of the power storage element increases.

The conventional estimated straight line shown as a broken line in FIG. 9 starts increasing from the beginning of the cycle to simulate the degradation value. The conventional estimated straight line does not take into account the maintenance/improvement of the characteristics of the power storage element that is observed in the initial stage of operation, and therefore deviates from the actual measured values shown by the triangular points. On the other hand, the estimated straight line according to this embodiment, shown by the solid line in FIG. 9, maintains the capacity deterioration rate at zero at the beginning of the cycle, and then changes the capacity deterioration rate to follow the approximate straight line fitted with the actual measured values. increase. In this way, the accuracy of deterioration estimation can be improved by considering maintenance/improvement of the characteristics of the power storage element at the initial stage of operation and not substantially increasing the deterioration value during the operation period. By improving the accuracy of deterioration estimation, it is possible to reduce the occurrence of events such as power storage system failures and unmet requirements, and it is also possible to perform appropriate preventive maintenance. It is preferable to centrally execute this estimation method in the server device 2 in the remote monitoring system 100 that monitors a plurality of power storage systems and devices as shown in FIG. This makes it possible to determine priorities and perform appropriate preventive maintenance with limited resources while suppressing increases in costs.

This technology is useful not only after the power storage system starts operating, but also when designing and proposing a power storage system. As shown by the broken line in Figure 9, if the deterioration of the energy storage element is overestimated using the conventional method, the requirements for the energy storage system (for example, the requirement to maintain a predetermined energy storage capacity (dischargeable amount of electricity) for more than 10 years) will not be satisfied. In order to do so, it is necessary to use more energy storage cells and energy storage modules than necessary. Therefore, the cost of the power storage system increases and loses cost competitiveness. On the other hand, if the method of this embodiment shown by the solid line in FIG. 9 is applied, future deterioration of the power storage element can be estimated with high accuracy, so it is possible to use the necessary and sufficient power storage cells and power storage modules to meet the requirements. , it is possible to build a highly cost-competitive energy storage system.

The method of FIG. 9 is suitably used when the operating environment is constant (the magnitude of SOC fluctuation is constant and the temperature is constant). On the other hand, the method of FIG. 10 can be suitably used when the SOC range or temperature changes during operation. The process in FIG. 10 may be executed at preset time intervals after the power storage element starts operating.

At the start of operation of the power storage element, in step S1 of FIG. 10, the cumulative capacity deterioration rate (hereinafter simply referred to as "capacity deterioration rate") D of the power storage element is set to zero. Further, the full charge capacity increase rate (hereinafter simply referred to as "initial capacity increase rate") E of the power storage element at the initial stage of operation is set to zero.

Next, in step S2, an approximate straight line ( Determine the slope a and the intercept b). The storage unit 21 (see FIG. 3) of the server device 2 may store data (for example, table data, functions, etc.) for determining an approximate straight line according to each SOC range and each temperature.

The approximate straight line for estimating deterioration will be explained in detail. The approximate straight line shown by the broken line in FIG. 5 is expressed by the equation y=ax+b. Here, y represents the capacity deterioration rate, and x represents the number of cycles. As shown in FIG. 8, the slope a of the approximate straight line changes depending on the temperature of the power storage element. The intercept b of the approximate straight line (capacity deterioration rate set to a negative value when the number of cycles is zero) changes depending on the SOC range of the power storage element shown in FIG. 6 and the temperature shown in FIG. 8.

In step S2, an approximate straight line (slope a, intercept b) for estimating deterioration is determined from data stored in the server device 2, depending on the SOC range and temperature of the power storage element at the time of calculation.

Next, in step S3, the increment d in the capacity deterioration rate from the previous calculation time is calculated using the slope a obtained in step S2 and the SOC fluctuation amount ΔSOC per unit time. That is, the increment d is calculated as d=a×ΔSOC.

Next, in step S4, it is determined whether the value obtained by adding the intercept b to the initial capacity increase rate E is greater than or equal to zero. If this value is greater than or equal to zero (S4: Yes), the period in which the characteristics of the electricity storage element are maintained or improved has already passed (corresponding to the state of the black dots in FIG. 11A), so in step S5, the previous Add the increment d to the capacity deterioration rate D at the time of calculation.

In step S4, if the value obtained by adding the intercept b to the initial capacity increase rate E is less than zero (S4: No), in step S6, the value obtained by adding the intercept b and the increment d to the initial capacity increase rate E is determined to be less than zero (S4: No). , determine whether it is greater than or equal to zero. If this value is greater than or equal to zero (S6: Yes), the period in which the characteristics of the electricity storage element are maintained or improved has just ended (corresponding to the state of the black dots in FIG. 11B), so in step S7, The initial capacity increase rate E, the intercept b, and the increment d are added to the capacity deterioration rate D at the time of the previous calculation. Further, −b, which is obtained by multiplying the intercept b (negative value) by a negative value, is substituted for the initial capacity increase rate E.

In step S6, if the value obtained by adding the intercept b and the increment d to the initial capacity increase rate E is less than zero (S6: No), it is within the period in which the characteristics of the energy storage element are maintained or improved (Fig. 11C), therefore, in step S8, the increment d is added to the initial capacity increase rate E at the time of the previous calculation.

By sequentially calculating the capacity deterioration rate using the method shown in FIG. 10, the accuracy of deterioration estimation can be improved even when the SOC range or temperature changes during operation.

The present invention is not limited to the embodiments described above, and can be modified as appropriate.
The estimation method and the computer program may be executed by the client device 3 instead of the server device 2 shown in FIG. 1, or may be executed by the communication device 1 or the management device M shown in FIG. 2.

2 Server device (information processing device)
2a Deterioration simulator (estimation device)
100 Remote monitoring system

Claims (7)

An estimation device for estimating deterioration of a power storage element,
An estimation device that does not substantially increase a deterioration value indicating deterioration while the characteristics of the power storage element are maintained or improved in the initial stage of operation. The estimating device according to claim 1, wherein the estimation device makes a decision regarding an increase in the deterioration value based on a magnitude of a change in SOC (State of Charge) at an initial stage of operation of the power storage element. 3. The larger the variation in SOC, the larger the full charge capacity of the power storage element at the initial stage of operation, and the higher the deterioration value of the power storage element whose full charge capacity has been increased. Estimation device. If the SOC of the power storage element fluctuates by a first magnitude until a predetermined number of cycles, and then the SOC of the power storage element fluctuates by a second magnitude larger than the first magnitude, the second magnitude The estimating device according to claim 2 or 3, wherein the full charge capacity of the power storage element at an early stage of operation is increased based on this, and the deterioration value of the power storage element whose full charge capacity has been increased is increased. The estimating device according to claim 1 or 2, wherein an increase in the deterioration value is determined based on temperature at an initial stage of operation of the power storage element. An estimation method for estimating deterioration of a power storage element, comprising:
An estimation method that does not substantially increase a deterioration value indicating deterioration while the characteristics of the power storage element are maintained or improved during the initial period of operation of the power storage element. A computer that estimates the deterioration of energy storage elements,
A computer program for executing a process that does not substantially increase a deterioration value indicating deterioration while the characteristics of the power storage element are maintained or improved during an initial period of operation of the power storage element.

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