Power storage device monitoring system and power storage device monitoring method

Abstract

To enable identification of error causes in estimation values of internal states of a power storage device.SOLUTION: A power storage device monitoring system 10 comprises: an estimation unit 111 that calculates an estimation value of a first type of internal state quantity being an internal state quantity by using a simulation model 121 simulating a power storage device 350 on the basis of measured values of physical parameters of the power storage device 350 and a calculated first type of internal state quantity being the internal state quantity of the power storage device 350 calculated from the measured values; and an analysis unit 112 that acquires the calculated first type of internal state quantity and identifies a cause of the error on the basis of a magnitude of an error between the calculated first type of internal state quantity and the estimation value of the first type of internal state quantity, and a frequency of occurrence of the error exceeding a predetermined value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power storage device monitoring system and a power storage device monitoring method for monitoring the state of a power storage device. [Background technology]

[0002] In order to reduce carbon dioxide emissions, the introduction of renewable energy sources is progressing. One of the impacts of adding renewable energy to the power generation mix is a decrease in the stability of the power grid. By introducing a power storage system, for example, by storing electricity during the daytime when solar power generation is high and releasing and supplying electricity during the nighttime when electricity demand is high, it is possible to increase the stability of the power grid. When introducing a power storage system, it is necessary to determine the capacity to ensure optimal use, and to optimize costs and operations.

[0003] Digital twins of energy storage systems are being introduced to optimize the capacity and operation of energy storage systems. Digital twins are digital (computer) replicas of an energy storage system. These digital twins simulate the behavior of the energy storage system and predict future internal state quantities such as the battery's State of Charge (SOC) and State of Health (SOH). These future predictions enable efficient operation of the power grid.

[0004] A technology for predicting the internal state quantity of a power storage device is an estimation device described in Patent Document 1. This estimation device includes an acquisition unit that acquires measurement data including the voltage of a storage element, the current flowing through the storage element, and the temperature related to the storage element, and an estimation unit that inputs the acquired measurement data to a state estimator constructed to simulate electrochemical and thermal phenomena of the storage element, and estimates the state of the storage element. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-054018 Summary of the Invention [Problem to be solved by the invention]

[0006] The estimation device described in Patent Document 1 makes it possible to calculate estimated values of SOC and open circuit potential (OCP). However, there is no description of the cause of errors in the estimated values or a method for identifying the cause. The present invention has been made in consideration of the above background, and aims to provide a power storage device monitoring system and a power storage device monitoring method that enable identification of the cause of error in the estimated value of the internal state of the power storage device. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the power storage device monitoring system of the present invention includes an estimation unit that calculates an estimate of a first-type internal state quantity, which is an internal state quantity, using a simulation model that simulates the power storage device, based on measured values of physical parameters of the power storage device and a calculated first-type internal state quantity, which is an internal state quantity of the power storage device calculated based on the measured values, and an analysis unit that acquires the calculated first-type internal state quantity and identifies the cause of the error based on the magnitude of the error between the calculated first-type internal state quantity and the estimated value of the first-type internal state quantity and the frequency of occurrence of the error exceeding a predetermined value. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a power storage device monitoring system and a power storage device monitoring method that enable identification of the cause of an error in an estimated value of the internal state of a power storage device. Problems, configurations, and effects other than those described above will become clear from the description of the following embodiments. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating the overall configuration of a power storage system including a power storage device monitoring system according to an embodiment of the present invention. [Figure 2] 1 is a diagram showing a configuration of a power storage module according to an embodiment of the present invention; [Figure 3] 1 is a diagram illustrating a configuration of a power storage rack according to an embodiment of the present invention. [Figure 4] 1 is a diagram illustrating a configuration of a power storage device according to an embodiment of the present invention. [Figure 5] 10 is a graph for explaining the processing of the analysis unit when aging deterioration is not taken into consideration according to the present embodiment. [Figure 6] 10 is a graph for explaining the processing of the analysis unit when aging deterioration is taken into consideration according to the present embodiment. [Figure 7] 10 is a flowchart of an analysis process according to the present embodiment. [Figure 8] FIG. 3 is a diagram illustrating a screen configuration of a monitoring screen according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] A power storage device monitoring system in a mode (embodiment) for carrying out the present invention will be described below. The power storage device monitoring system calculates estimated values of physical parameters (physical quantities) and internal state quantities of the power storage device using a mathematical model that simulates the power storage device. The power storage device monitoring system identifies the cause of the error based on the magnitude of the error between the estimated values and the measured values of the physical parameters or the internal state quantities calculated by the power storage device management system based on the measured values, and the frequency of the error. Causes of the error include the measurement system, external factors, and deterioration over time of the storage battery, etc.

[0011] By resolving the cause of the error, the energy storage device monitoring system will be able to estimate the future internal state quantities of the energy storage device with high accuracy, which will ultimately enable efficient operation of the power grid using the energy storage device.

[0012] <Configuration of the power storage system> 1 is a diagram showing the overall configuration of a power storage system 20 including a power storage device monitoring system 10 according to this embodiment. The power storage system 20 is connected to a power system 310 (power company system, power grid) via a grid interconnection point 320.

[0013] The power storage system 20 includes a transformer 330, a converter 340, a power storage device 350, and a power storage device monitoring system 10. The power storage device 350 is connected to the power grid 310 via a grid interconnection point 320, the transformer 330, and the converter 340. The transformer 330 changes the voltage of AC power. Generally, the voltage on the power grid 310 side is higher. The converter 340 converts DC power on the power storage device 350 side and AC power on the transformer 330 side, and vice versa. Generally, the converter 340 has a DC power transformation function.

[0014] <Electricity storage system: Electricity storage device> The power storage device 350 stores power and supplies it when demand is high. For example, the power storage device 350 stores power during the day when the amount of power generated by solar power generation is large and there is surplus power in the power grid 310, and supplies power at night when power demand is high. The power storage device 350 contributes to the operation of the power grid 310 by receiving and transmitting active power and reactive power. In other words, the power storage device 350 responds to increases and decreases in power demand by transmitting and receiving active power. It also contributes to the operation of the power grid 310 by generating reactive power that compensates for reactive power in the power grid 310.

[0015] An example of an electrochemical power storage device 350 is one that uses a storage battery. In addition, examples of power storage devices 350 that use a different principle from a storage battery, which stores electricity by converting it into chemical energy, include those that use a supercapacitor (electric double layer capacitor) or an electrolyzer (electrolyzer). The following explanation will be given using a storage battery as an example. The configuration of a power storage device 350 that is made up of a storage battery will be explained with reference to Figures 2 to 4.

[0016] 2 is a diagram showing the configuration of a power storage module 520 according to this embodiment. The power storage module 520 includes a plurality of battery cells 510. The battery cells 510 are the smallest components of the power storage device 350, and store electricity as other forms of energy and release the electricity. The battery cells 510 are connected in series and / or parallel to configure the power storage module 520. 3 is a diagram showing the configuration of a power storage rack 530 according to this embodiment. The power storage rack 530 is configured by connecting a plurality of power storage modules 520 in series.

[0017] 4 is a diagram showing the configuration of a power storage device 350 according to this embodiment. The power storage device 350 is configured by connecting a plurality of power storage racks 530 in series or in parallel. The voltage of the power storage device 350 is determined by the number of power storage racks 530 connected in series. The capacity of the power storage device 350 is determined by the number of power storage racks 530 connected in parallel. Generally, the power storage device 350 is housed in a container 540 or a room together with the power storage device monitoring system 10, but this is not limited to this.

[0018] <Electricity storage system: Electricity storage device monitoring system> Returning to Figure 1, we will continue to explain the power storage system 20. The power storage device monitoring system 10 is configured to include a measurement system 210, a power storage device management system 250, and a digital twin management device 100. The power storage device monitoring system 10 may include GUI devices 290 such as a display, a keyboard, and a mouse.

[0019] <Electricity storage device monitoring system: measurement system> The measurement system 210 measures voltage, current, ambient temperature, and the like in real time as physical parameters (first physical parameters) of the power storage device 350. The measurement system 210 may measure not only the power storage device 350 itself, but also the battery cells 510, power storage modules 520, and power storage racks 530 that make up the power storage device 350. The measurement system 210 sends the measured values of the first physical parameters to the power storage device management system 250 and the digital twin management device 100.

[0020] <Power storage device monitoring system: Power storage device management system> The power storage device management system 250 calculates an internal state quantity (first internal state quantity) of the power storage device 350 based on the measurement value of the first physical parameter, and transmits it to the digital twin management device 100. Examples of the first internal state quantity include, but are not limited to, the charging rate and the health / health level. The power storage device management system 250 may calculate internal state quantities not only for the power storage device 350 itself, but also for the battery cells 510, power storage modules 520, and power storage racks 530 that make up the power storage device 350, and transmit these to the digital twin management device 100. Note that with regard to the internal state quantities of the charging rate and health level, the charging rate may be referred to as a type 1 internal state quantity, and the health level may be referred to as a type 2 internal state quantity.

[0021] As described above, the power storage device monitoring system 10 includes the measurement system 210 and the power storage device management system 250. The measurements are the results of measurements of physical parameters of the power storage device 350 by the measurement system 210 . The calculated first type internal state quantity (charging rate) and the calculated second type internal state quantity (health level) are values calculated by the power storage device management system 250 based on measured values (actually measured values of current, voltage, etc.).

[0022] <Power storage device monitoring system: Digital twin management device> The digital twin management device 100 estimates the physical parameters (second physical parameters) and internal state quantities (second internal state quantities) of the power storage device 350 in the future based on the values of the first physical parameters and first internal state quantities of the power storage device 350 sent by the measurement system 210 and the power storage device management system 250. In other words, the digital twin management device 100 calculates and estimates the physical parameters and internal state quantities using a model (digital twin) that simulates the power storage device 350.

[0023] The first physical parameter and the first internal state quantity are collectively referred to as the first parameter. The second physical parameter and the second internal state quantity are collectively referred to as the second parameter. The first parameter is a physical parameter and an internal state quantity related to the power storage device 350. The second parameter is a physical parameter and an internal state quantity related to the digital twin.

[0024] The digital twin management device 100 is a computer and includes a control unit 110, a storage unit 120, and an input / output unit 180. A GUI device 290 is connected to the input / output unit 180. The input / output unit 180 includes a communication device and is capable of sending and receiving data to and from other devices such as the measurement system 210 and the power storage device management system 250. A media drive may also be connected to the input / output unit 180, enabling data exchange using a recording medium.

[0025] <Digital Twin Management Device: Memory Unit> The storage unit 120 is configured to include storage devices such as a read-only memory (ROM), a random access memory (RAM), and a solid-state drive (SSD). The storage unit 120 stores a simulation model 121, a deterioration model 122, an estimation result 123, and a program 128. The estimation result 123 stores a value of a second parameter estimated using the simulation model 121 and the deterioration model 122, which will be described later. The program 128 includes a description of an analysis process (see FIG. 7), which will be described later.

[0026] <Memory section: Simulation model> The simulation model 121 is a model used to estimate future values of a physical parameter (second physical parameter) and an internal state quantity (second internal state quantity) of the power storage device 350 based on the values of the first physical parameter and the first internal state quantity. The values of the first physical parameter and the first internal state quantity are not limited to current (latest) values, and may include past values (some or all may be past values). The estimated physical parameters include voltage, current, and temperature. The estimated internal state quantity is the state of charge (SOC, one type of internal state quantity). The simulation model 121 is, for example, an equivalent circuit model that represents a storage battery as an electric circuit, but is not limited to this and may be a model (mathematical model) that simulates electrochemical phenomena and thermal phenomena, and any type of model may be used.

[0027] <Memory section: Degradation model> The deterioration model 122 is a model used to estimate the internal state quantity of the power storage device 350 in the future based on the values of the first physical parameter and the first internal state quantity. The values of the first physical parameter and the first internal state quantity are not limited to current (latest) values, and may include past values (some or all may be past values). The estimated internal state quantity is the state of health (SOH, type 2 internal state quantity). The deterioration model 122 is a model that determines the degree of deterioration by, for example, comparing the results of a deterioration test conducted in a laboratory with the charge / discharge history of the power storage device 350, but is not limited to this and may be a model based on artificial intelligence or machine learning, and any type of model is acceptable. The calculated state of health is reflected as a parameter of the simulation model 121.

[0028] <Digital Twin Management Device: Control Unit> The control unit 110 includes a CPU (Central Processing Unit) and is equipped with an estimation unit 111, an analysis unit 112, and a parameter correction unit 113. The control unit 110 may also include a GPU (Graphics Processing Unit), an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), etc.

[0029] <Control section: Estimation section, parameter correction section> The estimation unit 111 estimates the voltage, current, temperature, state of charge, and state of health of the power storage device 350 in the future using the simulation model 121 and the degradation model 122, and stores the results in the estimation result 123. For example, the estimation unit 111 calculates an estimated value of the state of charge using the simulation model 121 at the timing when the first parameter is received from the measurement system 210 or the power storage device management system 250. Note that the rate of change of the state of health is slower than the rate of change of the state of charge. Therefore, the frequency of estimating the state of health may be lower than the frequency of estimating the state of health. The parameter correction unit 113 corrects the parameters of the simulation model 121. For example, the parameter correction unit 113 corrects the parameters of the simulation model 121 based on the soundness calculated by the estimation unit 111.

[0030] As described above, the power storage device monitoring system 10 includes an estimation unit 111 that calculates an estimated value of the first type internal state quantity (charging rate), which is an internal state quantity, using a simulation model 121 that simulates the power storage device 350, based on measured values of physical parameters of the power storage device 350 and the calculated first type internal state quantity (charging rate), which is an internal state quantity of the power storage device 350 calculated based on the measured values. In addition, the estimation unit 111 calculates an estimated value of the second type internal state quantity (health level), which is an internal state quantity of the power storage device 350, based on the measured value and the calculated first type internal state quantity, using a deterioration model 122 that simulates the deterioration over time of the power storage device 350.

[0031] <Control unit: Analysis unit> The analysis unit 112 compares the estimation result 123 with the current value of the first parameter, and if the error is large, analyzes the cause. More specifically, if the error is within a first threshold, the analysis unit 112 determines that there is no error. If the error exceeds the first threshold but is within a second threshold, the analysis unit 112 determines that there is an error in the measurement system 210. If the frequency of errors exceeding the second threshold is within a third threshold, the analysis unit 112 determines that there is an error due to external factors such as temperature. If the frequency of errors exceeding the second threshold is above a third threshold, the analysis unit 112 determines that there is an error due to aging of the power storage device 350, which includes a storage battery.

[0032] The frequency of occurrence of errors exceeding the second threshold is calculated, for example, as follows: A calculation target period of a first predetermined length is divided into N calculation unit periods of a second predetermined length. If the number of calculation unit periods in which errors exceeding the second threshold occurred exceeds a third threshold, the analysis unit 112 determines that the error is due to aging. For example, if the third threshold is N-1, the analysis unit 112 determines that the error is due to aging if errors exceeding the second threshold occurred in all calculation unit periods.

[0033] FIG. 5 is a graph for explaining the processing of the analysis unit 112 when aging degradation is not taken into consideration according to this embodiment. The horizontal axis is time, and the vertical axis is the state of charge (SOC). Graph 711 shows the state of charge estimated by the estimation unit 111 when aging degradation is not taken into consideration, and there is no change from the state of charge at time t0. Region 722 is a region where the difference from graph 711 is within a first threshold. Regions 721 and 723 are regions where the difference from graph 711 exceeds the first threshold and is within a second threshold.

[0034] Graph 713 shows the charge rate of the power storage device 350 calculated by the power storage device management system 250, and indicates that the actual charge rate decreases over time. More specifically, the error from graph 711 exceeds the first threshold at time t1, and exceeds the second threshold at time t2.

[0035] When the frequency of occurrence of errors exceeding the second threshold exceeds a third threshold, the analysis unit 112 determines that the cause of the large errors is aging deterioration of the power storage device 350. The analysis unit 112 prompts the operator of the power storage system 20 or the power storage device 350, who is the user of the power storage device monitoring system 10, to correct the parameters of the simulation model 121 or the deterioration model 122 so that a correct estimated value can be calculated. When the parameter correction unit 113 corrects the parameters in response to the operator's instruction, the graph 712 begins to show an estimated value of the charging rate.

[0036] FIG. 6 is a graph for explaining the processing of the analysis unit 112 when aging deterioration is taken into consideration according to this embodiment. The horizontal axis represents time, and the vertical axis represents the charging rate. Graph 731 shows the charging rate estimated by the estimation unit 111 when aging deterioration is taken into consideration, with the charging rate decreasing over time. Area 742 is an area where the difference from graph 731 is within a first threshold. Areas 741 and 743 are areas where the difference from graph 731 exceeds the first threshold and is within a second threshold.

[0037] Graph 733 shows the charge rate of the power storage device 350 calculated by the power storage device management system 250, and indicates that the actual charge rate decreases over time compared to the charge rate shown by graph 731. More specifically, the error from graph 731 exceeds the first threshold at time t6, and exceeds the second threshold at time t7.

[0038] When the frequency of occurrence of errors exceeding the second threshold exceeds a third threshold, the analysis unit 112 determines that the cause of the large errors is aging deterioration of the power storage device 350. The analysis unit 112 prompts the operator to correct the parameters of the simulation model 121 and the deterioration model 122 so that a correct estimated value can be calculated. When the parameter correction unit 113 corrects the parameters in response to the operator's instruction, the graph 732 begins to show an estimated value of the charging rate.

[0039] As described above, the power storage device monitoring system 10 acquires the calculated first-type internal state quantity (charging rate) and includes an analysis unit 112 that identifies the cause of the error based on the magnitude of the error between the calculated first-type internal state quantity and the estimated value of the first-type internal state quantity (charging rate) and the frequency of occurrence of the error exceeding a predetermined value (second threshold value). The analysis unit 112 also acquires a calculated second internal state quantity (health level), which is an internal state quantity of the power storage device 350 calculated based on the measurement values, and identifies the cause of the error based on the magnitude of the error between the calculated second internal state quantity and the estimated value of the second internal state quantity (health level), and the frequency of occurrence of errors exceeding a predetermined value (second threshold value).

[0040] If the occurrence frequency of an error exceeding a predetermined value (second threshold) is equal to or less than a predetermined frequency (third threshold), the analysis unit 112 identifies the cause of the error as an external factor and outputs it. If the frequency of occurrence of an error exceeding a predetermined value exceeds a predetermined frequency, the analysis unit 112 identifies the cause of the error as aging deterioration and outputs the result.

[0041] <Analysis processing> 7 is a flowchart of the analysis process according to this embodiment. The analysis process is executed at a predetermined timing, for example, when the first parameter is received from the measurement system 210 or the power storage device management system 250, or periodically. The process in which the analysis unit 112 analyzes the error between the estimation result 123 and the first parameter will be described with reference to FIG. 7.

[0042] In step S11, the analysis unit 112 calculates the error between the estimation result 123 and the first parameter. For example, the analysis unit 112 calculates the difference between the charging rate stored in the estimation result 123 and the charging rate calculated by the power storage device management system 250.

[0043] In step S12, if the error calculated in step S11 is equal to or less than the first threshold (step S11→YES), the analysis unit 112 proceeds to step S13, and if the error is greater than the first threshold (step S11→NO), the analysis unit 112 proceeds to step S14. In step S13, the analysis unit 112 determines that there is no error.

[0044] In step S14, if the error calculated in step S11 is equal to or less than the second threshold (step S14→YES), the analysis unit 112 proceeds to step S15, and if the error is greater than the second threshold (step S14→NO), the analysis unit 112 proceeds to step S16. In step S15, the analysis unit 112 determines that the cause of the error is an error in the measurement system 210.

[0045] In step S16, the analysis unit 112 calculates the occurrence frequency of errors exceeding the second threshold value. In step S17, if the occurrence frequency calculated in step S16 is less than or equal to the third threshold (step S17 → YES), the analysis unit 112 proceeds to step S18, and if the occurrence frequency is greater than the third threshold (step S17 → NO), the analysis unit 112 proceeds to step S19.

[0046] In step S18, the analysis unit 112 determines that the cause of the error is an external factor. In step S19, the analysis unit 112 determines that the cause of the error is deterioration of the power storage device 350 over time.

[0047] In step S20, the analysis unit 112 instructs the operator to take action depending on the cause (see monitoring screen 610 described later). For example, if the cause is an error in the measurement system 210, the analysis unit 112 instructs the operator to inspect the measurement system 210. If the cause is an external factor, the analysis unit 112 instructs the operator to review temperature countermeasures for the power storage device 350, for example. If the cause is deterioration over time, the analysis unit 112 instructs the operator to review parameters included in the simulation model 121 and the deterioration model 122.

[0048] ≪Monitoring screen≫ 8 is a screen configuration diagram of a monitoring screen 610 according to this embodiment. The analysis unit 112 displays the monitoring screen 610 on the display of the GUI device 290 (see FIG. 1). The current time is displayed in an area 611 at the top of the monitoring screen 610.

[0049] When the operator specifies parameters (physical parameters and internal state quantities) in the drop-down lists arranged in area 612, graphs of the parameters are displayed in area 613. In Fig. 8, the state of health (SOH) is specified, and area 613 displays a graph of the state of health calculated by power storage device management system 250 (graph on the left) and a graph of the state of health estimated by estimation unit 111.

[0050] The occurrence status of the error and the response are displayed in area 614. In Fig. 8, the error between the estimated value of the health state and the value calculated by the power storage device management system 250 is 16%, and the cause of the error is determined to be deterioration over time. To correct the error, an instruction is given to change the parameters of the deterioration model 122.

[0051] As described above, the analysis unit 112 outputs the monitoring screen 610 to the display device (see GUI device 290). The monitoring screen 610 includes at least one of the identified causes of the error and instructions for responding to the causes.

[0052] <Features of the power storage device monitoring system> The power storage device monitoring system 10 calculates estimated values of the physical parameters and internal state quantities of the power storage device 350 using a simulation model 121 and a degradation model 122 that simulate the power storage device 350. The power storage device monitoring system 10 identifies the cause of the error based on the magnitude of the error between the estimated values and the measured values of the physical parameters or the internal state quantities calculated by the power storage device management system 250 based on the measured values, and the frequency of the error. The cause of the error can be the measurement system 210, external factors such as temperature, or deterioration over time.

[0053] By resolving the cause of the error, the power storage device monitoring system 10 can estimate the future internal state quantity with high accuracy, which in turn enables efficient operation of the power system 310 using the power storage device 350.

[0054] <<Variation: Parameter Change>> In the above embodiment, the operator of the power storage device monitoring system 10 changes the parameters of the simulation model 121 using the parameter correction unit 113 in response to an instruction from the power storage device monitoring system 10. The parameter correction unit 113 may change the parameters of the simulation model 121 at a predetermined timing, for example, periodically.

[0055] Other variations Although several embodiments of the present invention have been described above, these embodiments are merely illustrative and do not limit the technical scope of the present invention. The present invention can take on various other embodiments, and various modifications such as omissions and substitutions can be made without departing from the spirit of the present invention. These embodiments and their modifications are included within the scope and spirit of the invention described in this specification, etc., and are included in the invention described in the claims and their equivalents. [Explanation of symbols]

[0056] 10. Power storage device monitoring system 20. Energy Storage System 100 Digital Twin Management Device 111 Estimation Department 112 Analysis Department 113 Parameter Modification Section 121 Simulation Model 122 Degradation Model 123 Estimation results 210 Measurement System 250 Power Storage Device Management System 290 GUI equipment (display device) 310 Power system 330 Transformer 340 Converter 350 Power Storage Device 610 Monitoring screen

Claims

1. an estimation unit that calculates an estimate of a first type internal state quantity, which is an internal state quantity of the power storage device, using a simulation model that simulates the power storage device, based on measured values of physical parameters of the power storage device and a calculated first type internal state quantity, which is an internal state quantity of the power storage device calculated based on the measured values; an analysis unit that acquires the calculated first type internal state quantity and identifies a cause of the error based on the magnitude of an error between the calculated first type internal state quantity and an estimated value of the first type internal state quantity and the frequency of occurrence of the error exceeding a predetermined value. Power storage device monitoring system.

2. The estimation unit calculating an estimated value of a second internal state quantity, which is an internal state quantity of the power storage device, using a deterioration model that simulates aging deterioration of the power storage device based on the measurement value and the calculated first internal state quantity; The analysis unit A calculated second internal state quantity, which is an internal state quantity of the power storage device calculated based on the measured value, is acquired, and a cause of the error is identified based on the magnitude of an error between the calculated second internal state quantity and an estimated value of the second internal state quantity and the frequency of occurrence of the error exceeding a predetermined value. The power storage device monitoring system according to claim 1 .

3. the first internal state quantity is a charging rate, The two types of internal state quantities are the health degree The power storage device monitoring system according to claim 2 .

4. Further comprising a measurement system and a power storage device management system; The measurement value is Measurement results of physical parameters of the power storage device by the measurement system; The calculated first type internal state quantity and the calculated second type internal state quantity are the value is calculated by the power storage device management system based on the measurement value, The analysis unit If the frequency of occurrence of the error exceeding the predetermined value is equal to or less than a predetermined frequency, the cause of the error is identified as an external factor and output; If the occurrence frequency of the error exceeding the predetermined value exceeds the predetermined frequency, the cause of the error is identified as aging deterioration and output. The power storage device monitoring system according to claim 2 .

5. The analysis unit Output the monitoring screen to a display device, The monitoring screen includes: The error information includes at least one of the identified causes of the error and instructions on how to deal with the causes. The power storage device monitoring system according to claim 3 .

6. The power storage device monitoring system A step of calculating an estimated value of a first type internal state quantity, which is an internal state quantity of the power storage device, using a simulation model that simulates the power storage device, based on measured values of physical parameters of the power storage device and a calculated first type internal state quantity, which is an internal state quantity of the power storage device calculated based on the measured values; acquiring the calculated first type internal state quantity, and identifying a cause of the error based on the magnitude of an error between the calculated first type internal state quantity and an estimated value of the first type internal state quantity and the frequency of occurrence of the error exceeding a predetermined value. A method for monitoring an electric power storage device.

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