Information processing method, information processing apparatus, and computer program

Abstract

To provide a technique capable of correcting a measurement value of a current by a current sensor.SOLUTION: An information processing method includes acquiring a measurement value of a current of an energy storage device by a current sensor and a measurement value of a voltage of the energy storage device by a voltage sensor in time series, determining whether or not a stable period in which the acquired measurement value of the voltage is stable is equal to or longer than a predetermined time, and deriving a correction parameter for correcting the measurement value of the current based on the measurement value of the current in the stable period when it is determined that the stable period is equal to or longer than the predetermined time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an information processing method, an information processing device, and a computer program. [Background technology]

[0002] Energy storage devices are widely used in uninterruptible power supplies, DC or AC power supplies included in stabilized power supplies, etc. In addition, the use of energy storage devices is expanding in large-scale power systems that store electricity generated by renewable energy or existing power generation systems.

[0003] Many energy storage devices are provided with a current sensor for detecting the current flowing through the energy storage device. Generally, the detected value of the current sensor contains an error. Techniques for correcting the error of the current sensor have been proposed (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-207973 Summary of the Invention [Problem to be solved by the invention]

[0005] A new method for correcting the current measured by a current sensor is needed.

[0006] An object of one aspect of the present disclosure is to provide a technique capable of correcting a current measurement value obtained by a current sensor. [Means for solving the problem]

[0007] An information processing method according to one aspect of the present disclosure acquires, in time series, measurement values ​​of the current of a storage element measured by a current sensor and measurement values ​​of the voltage of the storage element measured by a voltage sensor, determines whether a stable period during which the acquired voltage measurement values ​​are stable is longer than a predetermined time, and if it is determined that the stable period is longer than the predetermined time, derives a correction parameter for correcting the current measurement value based on the current measurement value during the stable period.

[0008] An information processing device according to one aspect of the present disclosure includes a processing unit that acquires, in time series, measurement values ​​of the current of a storage element by a current sensor and measurement values ​​of the voltage of the storage element by a voltage sensor, determines whether a stable period during which the acquired voltage measurement values ​​are stable is longer than a predetermined time, and if it determines that the stable period is longer than the predetermined time, executes a process to derive a correction parameter for correcting the current measurement value based on the current measurement value during the stable period.

[0009] A computer program according to one embodiment of the present disclosure acquires, in time series, measurement values ​​of the current of a storage element measured by a current sensor and measurement values ​​of the voltage of the storage element measured by a voltage sensor, determines whether a stable period during which the acquired voltage measurement values ​​are stable is longer than a predetermined time, and if it is determined that the stable period is longer than the predetermined time, causes the computer to execute a process of deriving correction parameters for correcting the current measurement values ​​based on the current measurement values ​​during the stable period. [Effects of the Invention]

[0010] According to the present disclosure, a technique can be provided that can correct a measured current value. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of a remote monitoring system. [Figure 2] FIG. 2 is a diagram illustrating an example of a configuration of a container of the power storage system. [Figure 3] FIG. 2 is a diagram illustrating an example of an electrical connection configuration of a power storage system. [Figure 4]FIG. 1 is a block diagram illustrating an example of the configuration of an information processing device. [Figure 5] FIG. 10 is a diagram illustrating an offset error of a current sensor. [Figure 6] 10 is a flowchart illustrating an example of a processing procedure executed by an information processing device. [Figure 7] 10A and 10B are diagrams illustrating the effects of the method of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] (1) An information processing method according to one aspect of the present disclosure acquires, in time series, measurement values ​​of the current of a storage element measured by a current sensor and measurement values ​​of the voltage of the storage element measured by a voltage sensor, determines whether a stable period during which the acquired voltage measurement values ​​are stable is longer than a predetermined time, and if it is determined that the stable period is longer than the predetermined time, derives a correction parameter for correcting the measurement value of the current based on the measurement value of the current during the stable period.

[0013] The current flowing through an energy storage element is one of the important indicators of the element's state and is also widely used to estimate other indicators, such as the element's SOC (State of Charge) and remaining capacity. Accurate detection of the element's current is important to accurately grasp the element's state. The current of an energy storage element is usually detected using a current sensor attached to the element. Current sensors are prone to errors due to factors such as aging and external factors, and calibration is required to eliminate these errors.

[0014] For example, when performing zero-point calibration to eliminate offset errors, it is necessary to perform the calibration at the site where the current sensor is installed, with the operation of the storage element to which the current sensor is attached stopped. Furthermore, zero-point calibration must be performed for each current sensor. Performing such zero-point calibration is not easy. In recent years, energy storage systems using multiple current sensors and storage elements have become widespread. In particular, performing zero-point calibration for each current sensor in such energy storage systems is difficult, and calibration is rarely performed after the system is put into operation.

[0015] The inventors of the present application have studied the offset error (the difference between the actual value and the measured value) in multiple current sensors installed in a single energy storage system equipped with multiple energy storage elements. As a result, they have found that even when installed in the same energy storage system, the offset error that occurs is not uniform but is distributed over a wide range. They have also found that the spread of the offset error changes depending on the time measurement. It is important to perform correction to eliminate the error for each current sensor, and to perform correction periodically.

[0016] According to the information processing method (1) above, a correction parameter for eliminating a current offset error can be calculated based on the measured values ​​of current and voltage when the storage element is in operation. The current can be corrected using the correction parameter without stopping the operation of the storage element. The current sensor can be easily calibrated even after the storage system is in operation. Because the current can be corrected using the measured values ​​of current and voltage, the correction process can be performed remotely, reducing the burden required to correct the measured current values.

[0017] (2) In the information processing method of (1) above, the correction parameter may be derived based on the measured value of the current during the first stable period, and the derived correction parameter may be used to correct the measured value of the current during the period from when the first stable period reaches a predetermined time or longer until when the second stable period following the first stable period reaches a predetermined time or longer.

[0018] According to the information processing method (2) above, the current during a certain stable period can be corrected using a correction parameter based on the current during that period. By setting the period for correcting the current using the correction parameter to be within the above period, the current state during a more recent period can be reflected in the correction parameter, thereby improving the calculation accuracy of the correction parameter and the current correction accuracy. Using the corrected current leads to improved estimation accuracy of the SOC of the storage element, which is particularly susceptible to current errors.

[0019] (3) In the information processing method of (1) or (2) above, the correction parameter may be derived as an average value of the current measured from the start of the stable period until it is determined that the stable period is equal to or longer than a predetermined time.

[0020] According to the information processing method (3) above, the correction parameters can be calculated easily and accurately. The current measurement values ​​over a certain period from the start of the stable period are averaged, which takes into account the time-series changes in the current, improving the accuracy of the correction parameters. By setting the collection period of the current measurement values ​​to a sufficiently long period, the periodic state of the current measurement values ​​can be properly reflected in the correction parameters, improving the accuracy of the correction parameters.

[0021] (4) In the information processing method of (3) above, the average value may be calculated by sequential calculation using a newly obtained current measurement value and an average value of the current measurement values ​​up to the immediately preceding time.

[0022] According to the information processing method (4) above, calculations can be performed each time a new measurement value is acquired and the values ​​can be stored. This reduces calculation costs and speeds up processing compared to when all measurement values ​​acquired up to that point are added up and an average value is calculated each time a correction parameter is calculated.

[0023] (5) In the information processing method of (4) above, the sequential calculation may be started using a current measurement value at the start point of the stable period as an initial value.

[0024] According to the information processing method of (5) above, the current measurement value during the period from the start of the stable period can be reflected in the correction parameter, thereby improving the accuracy of the correction parameter. By starting calculation of the average value before calculating the correction parameter, the calculation process of the correction parameter can be performed quickly.

[0025] (6) In any one of the information processing methods (1) to (5) above, the correction parameters may be repeatedly derived from when it is determined that the stable period is equal to or longer than a predetermined time until the stable period ends.

[0026] According to the information processing method (6) above, the correction parameters can be updated at any time until the stable period ends, thereby improving the accuracy of the final correction parameters.

[0027] (7) In any one of the information processing methods (1) to (6) above, if it is determined that the first stable period is longer than a predetermined time, a first correction parameter based on a measurement value of the current during the first stable period may be derived, and if it is determined that the second stable period following the first stable period is longer than a predetermined time, a second correction parameter based on a measurement value of the current during the second stable period may be derived.

[0028] According to the information processing method (7) above, a new correction parameter can be generated each time the stable period exceeds a predetermined time. Therefore, even if the offset error of the current sensor changes over time, a correction parameter corresponding to the change over time can be obtained, and the current can be appropriately corrected.

[0029] (8) In any one of the information processing methods (1) to (7) above, the correction parameter may be derived for each current sensor in a system including a plurality of current sensors corresponding to a plurality of storage elements.

[0030] According to the information processing method (8) above, the current measurement value can be corrected for each of the multiple current sensors.

[0031] (9) An information processing device according to one embodiment of the present disclosure includes a processing unit that acquires, in time series, measurement values ​​of the current of a storage element by a current sensor and measurement values ​​of the voltage of the storage element by a voltage sensor, determines whether a stable period during which the acquired voltage measurement values ​​are stable is longer than a predetermined time, and, if it is determined that the stable period is longer than the predetermined time, executes a process of deriving a correction parameter for correcting the current measurement value based on the current measurement value during the stable period.

[0032] (10) A computer program according to one embodiment of the present disclosure acquires, in time series, measurement values ​​of the current of a storage element measured by a current sensor and measurement values ​​of the voltage of the storage element measured by a voltage sensor, determines whether a stable period during which the acquired voltage measurement values ​​are stable is longer than a predetermined time, and if it is determined that the stable period is longer than the predetermined time, causes a computer to execute a process of deriving a correction parameter for correcting the current measurement value based on the current measurement value during the stable period.

[0033] The present disclosure will be specifically described with reference to the drawings showing embodiments thereof.

[0034] (First embodiment) FIG. 1 is a schematic diagram of a remote monitoring system 100. The remote monitoring system 100 enables remote access to information relating to a power storage system 5 that is the target of remote monitoring. The remote monitoring system 100 includes an information processing device 1 as a main device. The information processing device 1 and an energy management system (EMS) 2 are connected to each other via a network MN so that they can communicate with each other. The information processing device 1 and an information terminal device 3 are connected to each other via a network N so that they can communicate with each other.

[0035] The information processing device 1 is a device capable of various information processing and information transmission / reception, such as a server computer, a personal computer, a quantum computer, etc. The information processing device 1 acquires measurement data including measurement values ​​of the voltage and current of the energy storage element 51 in the energy storage system 5, and executes processing to correct the measurement value of the current.

[0036] The EMS 2 includes a device (for example, a server computer, a personal computer, a quantum computer, etc.) capable of performing various information processing and transmitting and receiving information. The EMS 2 acquires measurement data of the energy storage elements 51 transmitted from the energy storage system 5 via the network N, and transmits the acquired measurement data to the information processing device 1. The EMS 2 may be integrated with the information processing device 1.

[0037] The information terminal device 3 is, for example, a personal computer, a smartphone, a tablet terminal, etc. The information terminal device 3 is used by, for example, a user of the power storage system 5, a manufacturer, a service provider, a maintenance provider, etc. The information terminal device 3 can receive, via the information processing device 1, corrected current measurement values, estimation results regarding the state of the power storage elements 51 based on the current measurement values, etc., and present them to the user.

[0038] The power storage system 5 of this embodiment is, for example, an ESS (Energy Storage System). The ESS includes a large number of power storage elements 51. The power storage system 5 may include a power supply-related device 52 such as a power conditioner. The ESS is installed alongside a power generation facility such as a solar power generation facility, a wind power generation facility, a hydroelectric power generation facility, a biomass power generation facility, a geothermal power generation facility, or a thermal power generation facility, stores the power supplied from the power generation facility, and supplies the stored power to a load. The power storage system 5 can be used to absorb fluctuations in the power generated by the power generation facility or for self-consumption of the stored power.

[0039] The power storage system 5 may be used for other purposes, for example, by being connected to a power grid (grid interconnection) and used to suppress voltage fluctuations and frequency fluctuations in the power grid, or by being installed on the premises of a power consumer such as a factory and used for energy management such as BCP (Business Continuity Plan) measures and peak shifting, or for power trading in the power market. The power storage system 5 may be used together with power converters such as converters and inverters in a backup power system (emergency power system).

[0040] The network N is the so-called Internet. The network N may include a carrier network that realizes wireless communication according to a predetermined mobile communication standard. The network N may also include a general optical fiber line.

[0041] The network MN is a local network for the manufacturer or maintenance company of the energy storage element 51. The network MN may be, for example, Ethernet (registered trademark) or an optical fiber line. The network MN may include a VPN (Virtual Private Network) and connect systems and EMSs 2 in different locations as a local network.

[0042] FIG. 2 shows an example of the configuration of a container C of the power storage system 5. The container C of the power storage system 5 houses multiple (e.g., nine) power storage panels. Although not shown, the power storage system 5 may be configured by omitting the container C and installing multiple power storage panels outdoors. Each power storage panel may include, for example, three banks. Each bank is configured by electrically connecting multiple power storage modules in series. A power storage module has multiple power storage cells connected in series. Three banks are connected in parallel with each other. A configuration in which multiple banks are connected in parallel is also called a domain. When the required output voltage is low (when the number of power storage modules connected in series can be reduced), the power storage panel may include, for example, six banks. The number of banks included in the power storage panel and the number of power storage modules included in each bank are selected arbitrarily. The power storage panel in FIG. 2 includes one domain, but may also include multiple domains. In this specification, the term "power storage element" may refer to a power storage cell, a power storage module, a bank, or a domain.

[0043] The energy storage module is configured by connecting multiple energy storage cells in series. In one example, the energy storage cells are lithium-ion secondary battery cells. Alternatively, the energy storage cells may be battery cells such as all-solid-state batteries, lead batteries, redox flow batteries, zinc-air batteries, alkaline manganese batteries, lithium-sulfur batteries, sodium-sulfur batteries, silver-zinc oxide batteries, nickel-metal hydride batteries, and molten salt thermal batteries, or may be capacitors. The number of energy storage cells constituting the energy storage module can be selected arbitrarily.

[0044] Fig. 3 shows an example of an electrical connection configuration of the power storage system 5. Fig. 3 shows an electrical connection configuration of one power storage board included in the power storage system 5. In the example of Fig. 3, the power storage board has three banks: bank #1, bank #2, and bank #3.

[0045] Each of the banks #1, #2, and #3 includes a bank management device 53, a current sensor 54, a voltage sensor 55, and the like.

[0046] Each bank is connected to the outside (such as a power supply source or a power supply destination) via a power circuit. For example, the power supply source to the bank is a power generation facility, and the power supply destination of the bank is a load. A power converter (not shown) may be provided between the bank and the power supply source or the power supply destination. The bank stores (charges) power supplied from the power supply source and supplies (discharges) the stored power to the external power supply destination.

[0047] The current sensor 54 measures the current flowing through each bank in time series. The current sensor 54 is, for example, a Hall sensor. The current sensor 54 is connected in series to the multiple power storage modules included in each bank and measures the current for each bank.

[0048] The voltage sensor 55 measures the voltage of each bank in time series. The voltage sensor 55 is provided for each power storage module and measures the voltage across the terminals of each power storage element 51 included in the power storage module. FIG. 3 shows an example in which a voltage sensor 55 is provided for each power storage module in the bank. Alternatively, the voltage sensor 55 may be provided for at least one power storage module in the bank. The voltage sensor 55 may be configured to detect the voltage of the power storage module, or may be configured to detect the voltage of the bank.

[0049] As shown in FIG. 3, the current sensor 54 and the voltage sensor 55 are preferably configured to measure measurement values ​​of detection objects of different scales (for example, the current for each storage module and the voltage for each storage element 51), but may also measure measurement values ​​of detection objects of the same scale (for example, the current and voltage for each storage module).

[0050] The current measurement value obtained by the current sensor 54 and the voltage measurement value obtained by the voltage sensor 55 are output to the bank management device 53. The current and voltage can be repeatedly acquired at an appropriate period, such as 0.1 seconds, 0.5 seconds, or 1 second. The measurement intervals and timing of the current and voltage may or may not be synchronized. The current sensor 54 and the voltage sensor 55 may be mounted on a control board having a communication function that complies with a predetermined communication protocol, and may communicate with the bank management device 53 via the control board. The installation positions and number of the voltage sensor 55 and the current sensor 54 can be changed as appropriate.

[0051] Each bank may further include other sensors, such as a temperature sensor that measures the temperature of the power storage element 51, an internal resistance sensor that measures the internal resistance of the power storage element 51, and the like.

[0052] The bank management device 53 is a device for monitoring the state of the bank. The bank management device 53 acquires measurement data including current measurements by a current sensor 54 and voltage measurements by a voltage sensor 55. The bank management device 53 monitors the state of the bank at each time by, for example, calculating the SOC of the bank based on the time-series data of the acquired measurement data.

[0053] The power storage system 5 includes a domain management device M and a communication device 6. The domain management device M and the communication device 6 may be housed in a control panel built into the container C, separate from the power storage panel.

[0054] The domain management device M is a device for monitoring the status of a domain (an entire bank). The domain management device M is connected to the bank management device 53 of each bank so that it can communicate with them. The domain management device M aggregates measurement data from the bank management device 53 of each bank belonging to the domain. An existing communication standard such as CAN (Controller Area Network) is used for communication between the domain management device M and each bank management device 53. Alternatively, communication standards such as LIN (Local Interconnect Network), ECHONET (registered trademark), and ECHONET Light (registered trademark) may be used.

[0055] The communication device 6 securely transmits data to the EMS2 (see FIG. 2) wirelessly or via a wired connection. The communication device 6 may be a network interface card. The domain management device M transmits measurement data of the energy storage elements 51 acquired from each bank management device 53 to the EMS2 via the communication device 6. The domain management device M or the communication device 6 may hold the measurement data for a predetermined period of time and transmit the measurement data to the EMS2 at predetermined time intervals.

[0056] The EMS 2 collects and stores the measurement data received from each power storage system 5. The measurement data of the power storage system 5 transmitted to the EMS 2 may be associated with identification information of the power storage element 51, identification information of the current sensor 54, identification information of the voltage sensor 55, connection configuration data, etc. The EMS 2 can identify which current sensor 54 or voltage sensor 55 in which power storage system 5 the data transmitted from the communication device 6 was detected by, and store the data together with the associated information.

[0057] 4 is a block diagram showing an example of the configuration of the information processing device 1. The information processing device 1 includes a processing unit 11, a storage unit 12, a communication unit 13, a display unit 14, and an operation unit 15. The information processing device 1 may be a single computer, or may be a computer system configured with multiple computers and peripheral devices. The information processing device 1 may be a virtual machine whose entity is virtualized, or may be a cloud.

[0058] The processing unit 11 includes one or more processors, such as a central processing unit (CPU), a microprocessing unit (MPU), or a graphics processing unit (GPU). The processing unit 11 includes a memory, such as a static random access memory (SRAM) or a dynamic random access memory (DRAM), which is a temporary storage medium. The processing unit 11 may include functions such as a timer that measures the elapsed time from when a measurement start instruction is given to when a measurement end instruction is given, a counter that counts numbers, and a clock that outputs date and time information. The CPU and other components included in the processing unit 11 read and execute various computer programs stored in the storage unit 12 to control each hardware component and cause the entire device to function as the information processing device 1 of the present disclosure. The processing unit 11 may be realized by software, or part or all of it may be realized by hardware, such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA).

[0059] The storage unit 12 includes a nonvolatile storage device such as a hard disk or a flash memory. The storage unit 12 may be separate from the information processing device 1 and may be one or more external storage devices connected externally. The storage unit 12 stores various computer programs and data referenced by the processing unit 11. The storage unit 12 of this embodiment stores a program 121 for causing a computer to execute processing related to correction of the current of the storage element 51, and a measurement DB (Data Base) 122. The program 121 may include a program for realizing a web server function. The processing unit 11 can use the program 121 to present various information to the information terminal device 3 via a web page and also fulfill the web server function of receiving information from a user.

[0060] A computer program (program product) including the program 121 may be provided by a non-transitory recording medium 1A on which the computer program is readably recorded. The recording medium 1A is a portable memory such as a CD-ROM, a USB memory, or an SD (Secure Digital) card. The processing unit 11 reads a desired computer program from the recording medium 1A using a reading device (not shown) and stores the read computer program in the storage unit 12. Alternatively, the computer program may be provided by communication. The program 121 may be a single computer program or may be composed of multiple computer programs. The program 121 may also be executed on a single computer or may be executed cooperatively by multiple computers.

[0061] The measurement DB 122 is a database that stores measurement data received from the power storage system 5. The measurement DB 122 stores, in chronological order, records that link information such as identification information of the power storage element 51, identification information of the current sensor 54, identification information of the voltage sensor 55, measurement date and time, and measurement data, using, for example, a data ID for identifying the measurement data as a key. The measurement data includes the current and voltage of the power storage element 51. Every time the processing unit 11 receives measurement data transmitted from the power storage system 5, it stores the received measurement data in the measurement DB 122 in chronological order.

[0062] The communication unit 13 includes a communication device that realizes communication via the network MN and the network N. The processing unit 11 transmits and receives data to and from the EMS 2 and the information terminal device 3 via the communication unit 13.

[0063] The display unit 14 includes a display device such as a liquid crystal display, an organic EL (Electro Luminescence) display, etc. The display unit 14 displays various information in accordance with instructions from the processing unit 11.

[0064] The operation unit 15 is an interface that accepts user operations. The operation unit 15 includes, for example, a keyboard, a mouse, a touch panel device with a built-in display, a speaker, a microphone, etc. The operation unit 15 accepts operation input from the user and sends a control signal to the processing unit 11 according to the operation content.

[0065] Hereinafter, the offset error of the current sensor will be described, followed by a method for correcting the measured current value according to this embodiment. In this embodiment, the information processing device 1 executes the correction process for the measured current value.

[0066] FIG. 5 illustrates the offset error of a current sensor. FIG. 5A shows a graph illustrating the change in current of a test cell over time. In FIG. 5A, the vertical axis of the graph represents current (unit: amperes (A)), the horizontal axis represents time (unit: seconds), and the solid line represents the measured value of the current detected by the current sensor. FIG. 5B shows an enlarged graph of the area (time period) indicated by the rectangular frame in the graph of FIG. 5A. FIG. 5C shows a graph illustrating the change in voltage of a test cell over time during the same time period as FIG. 5B. In FIG. 5C, the vertical axis of the graph represents voltage (unit: volts (V)), the horizontal axis represents time (unit: seconds), one solid line represents the measured value of the voltage detected by the voltage sensor, and the other solid line represents the voltage obtained by the trace test.

[0067] As shown in Figures 5A and 5B, a small current is detected even when the test cell is not actively charging or discharging. Figure 5C shows that during the time period when a small current is detected, the trace test voltage gradually increases, tracing the small current, while the actual detected voltage value barely changes. The lack of voltage change means that no current is actually flowing in or out of the test cell. When no current flows in or out, the actual current value is nearly zero, so the current detected during the time period when the voltage is barely changing can be considered an offset error. It is assumed that the offset error occurs continuously, not only during the time period when the voltage is barely changing, but also at other times.

[0068] As shown in Figure 5B, a small current, or offset error, occurs periodically during periods when the voltage is barely changing. By averaging the current value over a sufficiently long period when the voltage is barely changing, the averaged current value can be identified as the offset error. By removing this offset error from the measured current value, the measured current value can be made closer to the actual value.

[0069] In the method for correcting the measured current value of this embodiment, a stable voltage period is identified based on time-series data of the voltage and current of the storage element 51, and the measured current values ​​detected during the identified stable period are averaged to derive the offset error. The offset error corresponds to a correction parameter for correcting the measured current value. The corrected measured current value (corrected current value) is obtained by subtracting the obtained correction parameter from the measured current value.

[0070] The information processing device 1 derives a correction parameter for each current sensor 54 provided in the power storage system 5, and uses each derived correction parameter to correct the current detected by the current sensor 54 from which the correction parameter was derived. In this embodiment, each bank is provided with one current sensor 54 connected in the same series circuit as the power storage modules in the bank, and one correction parameter is calculated for each bank. The correction parameter for a specific bank is used to correct the measured value of the current of each power storage element 51 included in the specific bank.

[0071] In this specification, a stable period refers to a period during which the measured voltage value is stable and barely changes. The stable period may be, for example, a period during which the change in the measured voltage value is less than a predetermined value (e.g., 0.002 V). The change in the measured voltage value may be found by calculating the difference between the latest measured voltage value and the immediately previous measured voltage value.

[0072] The stable period is identified based on time-series data of the voltage of the energy storage element 51 that is the target of current correction. When calculating the correction parameter for each bank, the stable period may be identified for each bank based on the measured values ​​of the voltage corresponding to each of multiple energy storage modules or energy storage cells connected in the same series circuit. In this case, the stable period of the bank may be determined as a period that is commonly identified as a stable period for all or a predetermined number or more of the energy storage modules or energy storage cells in the bank. Alternatively, the stable period of the bank may be determined as a stable period based on the measured value of the voltage of a representative energy storage module or representative energy storage cell in the bank.

[0073] Calculation of the correction parameter begins when a predetermined time has elapsed since the start of the stable period. The predetermined time can be set appropriately, taking into account the time required for polarization elimination of the storage element 51 and for the voltage to sufficiently stabilize, and may be, for example, several tens of minutes to several hours. The correction parameter is obtained by calculating the average of all current measurement values ​​obtained from the start of the stable period to the calculation time of the correction parameter. The correction parameter may also be the arithmetic mean value obtained by dividing the sum of all current measurement values ​​obtained from the start of the stable period to the calculation time of the correction parameter by the number of measurement points. Alternatively, the total number of data points may be reduced by thinning out all current measurement values ​​during the period according to a predetermined rule.

[0074] The calculation of the correction parameters is continuously performed until the stable period ends. The correction parameters are updated as needed during the stable period. The obtained correction parameters are applied to the correction process from the time a predetermined time has elapsed since the start of the stable period until the time a predetermined time has elapsed since the start of the next stable period. When the predetermined time has elapsed since the start of the next stable period, new correction parameters based on the current are generated for the next stable period, and the new correction parameters are applied.

[0075] For example, as shown in FIG. 5A, assume that after the end of the first stable period, there is a period in which the voltage is unstable, followed by a second stable period in which the voltage stabilizes again. Calculation of the first correction parameter begins a predetermined time after the start of the first stable period, and calculation (updating) of the first correction parameter ends at the end of the first stable period. Using the obtained first correction parameter, current measurement values ​​collected from a predetermined time after the start of the first stable period until a predetermined time after the start of the second stable period are corrected. After a predetermined time after the start of the second stable period, a new second correction parameter is calculated based on the current measurement values ​​during the second stable period. Using the second correction parameter, current measurement values ​​collected from a predetermined time after the start of the second stable period until a predetermined time after the start of the third stable period following the second stable period are corrected.

[0076] In calculating the correction parameters, the average value of the current measurement values ​​is calculated by sequential calculation. The average value is calculated by sequential calculation using the current measurement value newly obtained when calculating the correction parameters and the average value of the current measurement values ​​up to that point. The sequential calculation starts when the stable period begins. The current measurement value at the start of the stable period is used as the initial value, and sequential calculation is performed every time a new measurement value is obtained to determine the average value, and the obtained average value is stored in memory unit 12. The correction parameters can be easily determined by calculating the average value of the new current measurement value at the time of calculation of the correction parameters and the previously stored average value.

[0077] 6 is a flowchart showing an example of a processing procedure executed by the information processing device 1. The processing unit 11 of the information processing device 1 executes the following processing in accordance with a program 121 stored in the storage unit 12. The processing unit 11 repeatedly executes the following processing, for example, at the timing when new measurement data is detected or at a predetermined correction timing.

[0078] The processing unit 11 of the information processing device 1 acquires the measurement values ​​of the current and voltage of the storage element 51 (step S11). The processing unit 11 acquires the measurement values ​​of the current and voltage by receiving measurement data including the current and voltage transmitted from the EMS 2. When the processing unit 11 acquires new measurement values ​​of the current and voltage, it stores the acquired measurement values ​​of the current and voltage in the measurement DB 122 in chronological order. This allows time-series data of the measurement values ​​of the current and voltage to be obtained. Alternatively, the processing unit 11 may acquire the measurement values ​​of the current and voltage by reading data previously stored in the measurement DB 122.

[0079] The processing unit 11 determines whether or not the current period is a stable period in which the voltage measurement values ​​are stable, for example, by determining whether or not the amount of change in the acquired time-series voltage measurement values ​​is less than a predetermined value (step S12). If it determines that the current period is not a stable period because, for example, the amount of change in the voltage measurement values ​​is equal to or greater than a predetermined value (S12: NO), the processing unit 11 resets the time count for the stable period (step S13). After the reset, the processing unit 11 proceeds to step S19. The processing unit 11 may end the processing.

[0080] For example, if it is determined that the stable period is occurring because the amount of change in the measured voltage value is less than a predetermined value (S12: YES), the processing unit 11 updates the time count for the stable period (step S14). If the time count for the stable period has not started, the processing unit 11 starts counting the time for the stable period in step S14.

[0081] The processing unit 11 calculates the average value of the current measurement values ​​by sequential calculation using the newly obtained current measurement value and the average value of the current measurement values ​​up to the immediately preceding time (step S15). The initial value for the sequential calculation of the average value is the current measurement value at the start point of the ongoing stable period. The processing unit 11 stores the calculated average value in the memory unit 12 (step S16). In step S16, the processing unit 11 may update the average value by storing the new average value in place of the previously stored average value.

[0082] The processing unit 11 determines whether the count time of the stable period is equal to or greater than a predetermined time (step S17). If it is determined that the count time of the stable period is less than the predetermined time (S17: NO), the processing unit 11 proceeds to step S19. The processing unit 11 may end the processing. Alternatively, the processing unit 11 may return to step S17 and wait until the count time of the stable period becomes equal to or greater than the predetermined time, or may end the processing.

[0083] If it is determined that the count time of the stable period is equal to or longer than the predetermined time (S17: YES), the processing unit 11 derives a correction parameter and stores the derived correction parameter (step S18). The information processing device 1 derives a correction parameter for each current sensor 54 provided in the power storage system 5. In step S18, the processing unit 11 may derive the correction parameter by reading out the average value stored in step S16. The processing unit 11 may update the correction parameter by storing a new correction parameter in place of the previously stored correction parameter.

[0084] The processing unit 11 corrects the measurement value of the current acquired in step S11 using the correction parameter (step S19) and calculates the corrected current value. The processing unit 11 calculates the corrected current value by dividing the measurement value of the current to be corrected by the correction parameter. If a new correction parameter is derived by the processing of step S18, the processing unit 11 calculates the corrected current value using the new correction parameter. If step S18 is skipped, the processing unit 11 calculates the corrected current value using the correction parameter that has already been calculated based on data from the immediately previous stable period.

[0085] The processing unit 11 outputs the calculated correction current value to an estimation unit that executes predetermined processing (step S20), and ends the processing. The estimation unit includes, for example, an estimation unit that estimates the SOC of the storage element 51 by a current integration method using the correction current value, and an estimation unit that estimates the state of the storage element 51 by an estimation model (for example, an equivalent circuit model that simulates voltage behavior, a model that estimates charge / discharge characteristics, a life prediction model, etc.) using the correction current value. The information processing device 1 may function as the estimation unit. The processing unit 11 may output a correction parameter instead of the correction current value. The processing unit 11 may output the correction current value or the correction parameter via the display unit 14.

[0086] The processing entity in the above-described flowchart is not limited. Some or all of the processing executed by the information processing device 1 may be executed by, for example, the bank management device 53, the domain management device M, the EMS 2, or the information terminal device 3.

[0087] The calculation of the correction parameters and the correction process of the measured current values ​​are preferably performed in real time, but may be performed after the fact for the measured current values ​​over a predetermined period. The correction and output process of the measured current values ​​may be performed at a timing independent of the derivation of the correction parameters.

[0088] FIG. 7 is a diagram illustrating the effect of the method of this embodiment. FIG. 7A shows a graph illustrating the change in SOC of a test cell over time. FIG. 7B shows a graph enlarging the area indicated by the rectangular frame in the graph of FIG. 7A. In FIGS. 7A and 7B, the vertical axis of the graph represents SOC (unit: %), and the horizontal axis represents time (unit: s). In FIGS. 7A and 7B, the curve for the proposed integration method represents the SOC calculated by the current integration method using current values ​​corrected by the method of this embodiment. The curve for the integration method represents the SOC calculated by the current integration method using current values ​​not corrected by the method of this embodiment. The curve for the maximum likelihood value represents the maximum likelihood value (effective true value) of SOC. With the proposed integration method, current correction using the method of this embodiment was performed after time t1 in FIG. 7B.

[0089] As shown in Figure 7, after time t1, the SOC value is properly corrected using the proposed integration method, approaching the maximum likelihood value, and it can be seen that the SOC does not rise as seen with the integration method. By using the corrected voltage value obtained by the method of this embodiment, it is possible to improve the accuracy of estimation processes that use current, such as SOC estimation.

[0090] The information processing method, the information processing device, and the computer program may be applied to applications other than stationary power storage devices, and may be applied to vehicles, for example.

[0091] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the scope of the claims and the scope equivalent to the claims. The sequences shown in each embodiment are not limited, and the order of each process may be changed within a range consistent with the present invention, and multiple processes may be executed in parallel. The entity that performs each process is not limited, and the process of each device may be executed by another device within a range consistent with the present invention.

[0092] The matters described in each embodiment can be combined with each other. In addition, the independent claims and dependent claims described in the claims can be combined with each other in any combination, regardless of the reference format. Furthermore, although the claims use a format in which a claim references two or more other claims (multiple claim format), this is not limited to this format. A multiple claim (multi-multi claim) that references at least one other multiple claim may also be used. [Explanation of symbols]

[0093] 100 Remote Monitoring System 1. Information processing equipment 11 Processing section 12 Storage section 13 Communications Department 14 Display section 15 Control section 121 Program (Computer Program) 1A Recording Media 5. Energy storage system 51 Energy storage element 54 Current Sensor 55 Voltage Sensor

Claims

1. A measurement value of a current of the storage element measured by a current sensor and a measurement value of a voltage of the storage element measured by a voltage sensor are acquired in time series; determining whether the stable period during which the acquired voltage measurement value is stable is equal to or longer than a predetermined time; If it is determined that the stable period is equal to or longer than a predetermined time, a correction parameter for correcting the measured value of the current is derived based on the measured value of the current during the stable period. An information processing method in which processing is performed by a computer.

2. deriving the correction parameter based on a measurement value of a current during a first stable period; Using the derived correction parameter, the measured value of the current during the period from when the first stable period reaches or exceeds a predetermined time until when the second stable period following the first stable period reaches or exceeds a predetermined time. The information processing method according to claim 1 .

3. The correction parameter is derived from an average value of the current measured during the period from the start of the stable period until it is determined that the stable period is equal to or longer than a predetermined time.

3. The information processing method according to claim 1.

4. The average value is calculated by sequential calculation using the newly obtained current measurement value and the average value of the current measurement value up to the immediately preceding time. The information processing method according to claim 3 .

5. The sequential calculation is started using the measured value of the current at the start point of the stable period as the initial value. The information processing method according to claim 4.

6. The correction parameter is repeatedly derived from the time when it is determined that the stable period is equal to or longer than a predetermined time until the stable period ends.

3. The information processing method according to claim 1.

7. deriving a first correction parameter based on a measurement value of a current during the first stable period when it is determined that the first stable period is equal to or longer than a predetermined time; When it is determined that the second stable period following the first stable period is equal to or longer than a predetermined time, the second correction parameter is derived based on the measured value of the current during the second stable period.

3. The information processing method according to claim 1.

8. The correction parameter is derived for each of the current sensors in a system including a plurality of the current sensors corresponding to a plurality of storage elements.

3. The information processing method according to claim 1.

9. A measurement value of a current of the storage element measured by a current sensor and a measurement value of a voltage of the storage element measured by a voltage sensor are acquired in time series; determining whether the stable period during which the acquired voltage measurement value is stable is equal to or longer than a predetermined time; If it is determined that the stable period is equal to or longer than a predetermined time, a correction parameter for correcting the measured value of the current is derived based on the measured value of the current during the stable period. A processing unit for executing processing is provided. Information processing device.

10. A measurement value of a current of the storage element measured by a current sensor and a measurement value of a voltage of the storage element measured by a voltage sensor are acquired in time series; determining whether the stable period during which the acquired voltage measurement value is stable is equal to or longer than a predetermined time; If it is determined that the stable period is equal to or longer than a predetermined time, a correction parameter for correcting the measured value of the current is derived based on the measured value of the current during the stable period. A computer program that causes a computer to perform a process.

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