Power management system

Abstract

To facilitate implementation of required energy management using a plurality of electric vehicles that learns current sensor offset values.SOLUTION: A power management system includes a vehicle group including a plurality of electric vehicles and a control device that controls the vehicle group. Each of the plurality of electric vehicles includes a power storage device and a current sensor that detects a charge and discharge current of the power storage device, and sets the charge and discharge current to zero at predetermined timing to learn an offset value of the current sensor (S11 to S15). When causing the vehicle group to execute energy management through charging or discharging of the power storage device, the control device estimates power reduction due to the learning with regard to charging power or discharging power of the vehicle group, and determines a power command value to the vehicle group for energy management on the basis of the estimated power reduction (S22).SELECTED DRAWING: Figure 2

Description

Technical Field

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[0001] The present disclosure relates to a power management system.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2009-171666 (Patent Document 1) discloses a control device that starts charging a power storage device mounted on an electric vehicle, temporarily interrupts the charging at predetermined time intervals, and performs learning (learning of an offset value) for output correction of a current sensor provided in a charge / discharge path of the power storage device.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, it has been proposed to perform energy management of a power system using a plurality of electric vehicles equipped with power storage devices. However, when performing energy management by charging or discharging a power storage device on a plurality of electric vehicles, if at least one electric vehicle performs learning of the offset value of the current sensor described above, the charge / discharge current of the power storage device in that electric vehicle becomes zero (0 A), and there is a possibility that the charging power or discharging power may be insufficient for the required energy management.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to facilitate execution of required energy management using a plurality of electric vehicles that learn offset values of current sensors.

Means for Solving the Problems

[0006] A power management system according to one embodiment of the present disclosure comprises a group of vehicles including a plurality of electric vehicles and a control device for controlling the group of vehicles. Each of the plurality of electric vehicles has a power storage device and a current sensor for detecting the charging and discharging current of the power storage device, and is configured to learn the offset value of the current sensor by setting the charging and discharging current to zero at a predetermined timing. When the control device causes the group of vehicles to perform energy management by charging or discharging the power storage device, it estimates the power reduction due to learning with respect to the charging power or discharging power of the group of vehicles, and determines a power command value for the group of vehicles for energy management based on the estimated power reduction. [Effects of the Invention]

[0007] According to this disclosure, it becomes easier to perform the required energy management using multiple electric vehicles that learn the offset values ​​of current sensors. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows an overview of the power management system according to an embodiment of the present disclosure. [Figure 2] This is a diagram illustrating an energy management method according to an embodiment of the present disclosure. [Figure 3] This figure shows a comparison of the actual adjusted power values ​​for the example, modified example, and comparative example. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0010] Figure 1 is a diagram showing an overview of a power management system according to an embodiment of the present disclosure. Referring to Figure 1, the power management system according to this embodiment performs energy management of a power grid PG. This power management system includes a vehicle group 10G including a plurality of vehicles 10, a vehicle group 20G including a plurality of vehicles 20, a supply and demand management system 100 (hereinafter referred to as "system 100"), a resource management system 200 (hereinafter referred to as "system 200"), an electric vehicle management system 300 (hereinafter referred to as "system 300"), a plurality of power supply equipment 510, and a plurality of power supply equipment 520. System 300 includes a processor 310 and a storage device 320. Although not shown in the diagram, systems 100 and 200 also include a processor and a storage device, similar to system 300.

[0011] The power grid (PG) is a power network constructed by transmission and distribution equipment. Multiple power plants are connected to the power grid (PG). Each of the power supply equipment 510 and 520 is electrically connected to the power grid (PG) and receives power from the power grid (PG). Each of the vehicles 10 and 20 is an electric vehicle (xEV) equipped with a power storage device and is configured to run using the discharged power from the power storage device. When vehicles 10 and 20 are electrically connected to the power supply equipment 510 and 520, respectively (plug-in state), they can charge their onboard batteries (power storage devices) using power supplied from the power grid (PG) through the power supply equipment 510 and 520 (power from outside the vehicle).

[0012] Vehicle 10 and power supply equipment 510 are, respectively, V1G type (a type that unilaterally receives power from the power grid PG). Power supply equipment 510 is, for example, a plug-in type power supply equipment. Vehicle 20 and power supply equipment 520 are, respectively, V2G type (a type that exchanges power in both directions with the power grid PG). Power supply equipment 520 is, for example, a cable-integrated type power supply equipment. Each of vehicles 10 and 20 is, for example, a BEV (electric vehicle). However, it is not limited to this, and the types of electric vehicles (xEVs) included in each of vehicle groups 10G and 20G are arbitrary.

[0013] System 300 is configured to communicate with each electric vehicle included in vehicle groups 10G and 20G. System 300 may communicate with vehicles 10 and 20 via wired connections through power supply equipment 510 and 520, respectively, or it may communicate directly with each of vehicles 10 and 20 via wireless communication. In addition, each electric vehicle user carries a user terminal 30. System 300 also communicates with the user terminal 30. The user terminal 30 is, for example, a smartphone, but may be any other device.

[0014] Each electric vehicle and each power supply facility shown in Figure 1 is registered in system 300. The storage device 320 stores information about each registered electric vehicle (specifications, location, status, etc.), distinguishing it by the electric vehicle's identification information (vehicle ID). In addition, each electric vehicle's user terminal 30 is also registered in system 300, linked to the vehicle ID. For example, when a user enters a driving plan or charging plan for an electric vehicle into the user terminal 30, that plan is registered in system 300, linked to the electric vehicle's identification information. The storage device 320 also stores information about each registered power supply facility (specifications, location, etc.), distinguishing it by the power supply facility's identification information.

[0015] Hereafter, all electric vehicles managed by System 300 will be collectively referred to as "electric vehicle resources." System 300 calculates the unadjusted charge / discharge power (reference value) and the amount of power that the electric vehicle resources can adjust relative to that reference value (charge / discharge capacity) and transmits this information to System 200. System 200 manages multiple distributed energy resources (hereinafter referred to as "DERs"), including electric vehicle resources. Hereafter, all DERs managed by System 200 will be collectively referred to as "EM resources." EM resources further include DERs other than electric vehicle resources (for example, stationary energy storage devices). With respect to EM resources, System 200 calculates the unadjusted charge / discharge power (reference value) and the amount of power that the EM resources can adjust relative to that reference value (charge / discharge capacity) and transmits this information to System 100. Based on the reference value and charge / discharge capacity received from System 200, System 100 conducts transactions in the electricity market. System 100 settles electricity transactions and manages transaction records. Below, we will explain tertiary adjustment power-2 as an example of a commodity traded in the electricity market.

[0016] Third-tier adjustment power-2 is traded in the supply and demand adjustment market. In the supply and demand adjustment market, trading of third-tier adjustment power-2 takes place for each of the eight blocks, which are divided into three-hour units, for example, by bidding. System 100 places bids in the supply and demand adjustment market during the period from 12:00 to 14:00 on the day before the target block. Specifically, System 100 transmits bidding information, including the product (e.g., third-tier adjustment power-2), block (one of the eight blocks), reference value, and bid amount, to the market system (not shown). The results are then notified to System 100 at 15:00 on the bidding day. If the bid for the product is successful, a contract is concluded. The person who successfully bids for third-tier adjustment power-2 in the supply and demand adjustment market is obligated (contractual obligation) to adjust the power within the range from the reference value (kW) to the contracted amount (kW) (contract adjustment range).

[0017] When System 100 wins a bid for a product, it registers the reference value in the market system by the submission deadline (for example, one hour before the start time of the block in which the bid was won). System 100 sequentially receives market request signals from the market system requesting energy management for the block in which the bid was won (the contract period). The market request signals indicate the power request value that the market system arbitrarily requests within the contract adjustment range. During the contract period, System 100 performs energy management so that the actual adjusted power follows the power request value.

[0018] The market system verifies every 30 minutes (frames) that System 100 (the successful bidder) is adjusting according to the commands (market request signals) within the agreed adjustment range (response performance) during the contract period. If the power requirement changes during the contract period, the successful bidder changes the output to that value within the response time for the product requirement. However, the output may deviate from the power requirement as long as it is within the acceptable range. Also, if the power requirement remains the same during the contract period, the successful bidder will continue to output according to that power requirement for at least the duration of the product requirement. For tertiary adjustment power-2, the response time is within 45 minutes, and the duration is 3 hours (6 frames). If the successful bidder uses an energy storage device to perform energy management, the successful bidder's output will be charging (increased demand) or discharging (increased supply) corresponding to the requested energy management (product). If non-conformity to the requirements is found, the successful bidder will be subject to a prescribed penalty fee.

[0019] In the example shown in FIG. 1, the period from time t1 to time t2 corresponds to the agreed period, and the range from the reference value to the agreed quantity Y corresponds to the agreed adjustment range. Line L10 shows the transition of the power demand value. Line L11 shows a power value (lower limit value of the allowable range) that is smaller than the power demand value by the allowable width. Line L12 shows a power value (upper limit value of the allowable range) that is larger than the power demand value by the allowable width. The allowable width is, for example, 10% of the agreed quantity Y. The market system transmits a market demand signal to the winning bidder at time t0, which is 45 minutes before the response time from time t1. In the example shown in FIG. 1, the initial power demand value is the agreed quantity Y, and the power demand value is changed at time t3. The range from time t0 to the time when the response time elapses (response allowance A), the range from time t3 to the time when the response time elapses (response allowance B), and the range corresponding to the allowable width shown by lines L11 and L12 (increase / decrease allowance) correspond to the range that satisfies the requirements (allowable range).

[0020] When system 100 receives a market demand signal, it determines the adjustment amount (upper instruction amount) necessary to execute the energy management required by the market demand signal, and based on the obtained upper instruction amount, determines the power demand value (resource instruction amount) required for the EM resource. Then, system 100 transmits a first request signal indicating the agreed requirements (agreed quantity, agreed period, allowable range, etc.) and the resource instruction amount to system 200. When system 200 receives the first request signal, it determines the adjustment amount (charge / discharge required amount) necessary for the resource instruction amount, and based on the obtained charge / discharge required amount, determines the power demand value (fleet instruction amount) required for the electric vehicle resource. Then, system 200 transmits a second request signal indicating the agreed requirements and the fleet instruction amount to system 300. System 300 controls the electric vehicle resource so that the energy management required by the second request signal is executed by the process shown in FIG. 2 described later. According to such a hierarchical structure (tree structure), energy management can be requested from many consumers. The EM resource may function as a VPP (virtual power plant).

[0021] FIG. 2 is a diagram for explaining the energy management method according to this embodiment. "S" in the flowchart means step.

[0022] Referring to FIG. 2, each of the vehicles 10 and 20 includes a battery 51 (drive battery), an ECU (electronic control unit) 52, a current sensor 53 for detecting the current flowing through the battery 51, a voltage sensor 54 for detecting the voltage of the battery 51, and a temperature sensor 55 for detecting the temperature of the battery 51. The detection results by each sensor are input to the ECU 52. The ECU 52 includes a processor and a storage device (not shown), and records the detection results by each sensor in the storage device. Also, in each of the vehicles 10 and 20, when charging and discharging of the battery 51 (specifically, charging of the battery 51 by power from outside the vehicle or discharging of the battery 51 to outside the vehicle) is started, the ECU 52 starts the processing flow of S11 to S15 described below.

[0023] In S11, the ECU 52 determines whether the learning timing has arrived. In this embodiment, learning for output correction of the current sensor 53 is periodically executed. The learning timing arrives every time a predetermined time elapses during charging and discharging of the battery 51. When the learning timing arrives (YES in S11), learning is executed by the processing of S12 to S14.

[0024] In S12, the ECU 52 stops (interrupts) charging and discharging of the battery 51. As a result, the charging and discharging current of the battery 51 becomes zero (0 A). Subsequently, in S13, the ECU 52 learns (acquires and records) the offset value (output value when no current is flowing) of the current sensor 53. Then, the ECU 52 corrects (calibrates) the detection error of the current sensor 53 based on the obtained offset value. The ECU 52 may set a correction coefficient for the current sensor 53. After that, in S14, the ECU 52 resumes charging and discharging of the battery 51.

[0025] When the above learning (S12-S14) is performed, the process proceeds to S15. Also, even if the learning timing has not yet arrived (NO in S11), the process proceeds to S15. In S15, the ECU 52 determines whether or not the charging and discharging of the battery 51 is complete. If the charging and discharging of the battery 51 is to continue (NO in S15), the process returns to S11. On the other hand, when the charging and discharging of the battery 51 is complete (YES in S15), the above processing flow (S11-S15) ends.

[0026] When system 300 receives a second request signal requesting the start of EM (Energy Management), it starts the processing flow S21 to S25. System 300 causes the electric vehicle resources (a group of vehicles including multiple electric vehicles) to perform charging or discharging of the energy storage device (battery 51) corresponding to the energy management requested by the second request signal, in the manner described below.

[0027] In S21, the system 300 determines whether or not the instruction timing has arrived. The instruction timing arrives at the start of EM. Thereafter, the instruction timing arrives every predetermined time (for example, 1 minute). When the instruction timing arrives (YES in S21), the system 300 estimates the power drop in the vehicle group power (charging power or discharging power of the vehicle group) due to the aforementioned learning (calibration of the current sensor 53) in S22, and determines the power command value for the vehicle group for EM (Energy Management) based on the estimated power drop. As will be described in detail later, the system 300 determines the power command value for the vehicle group so that the vehicle group power falls within the allowable range set for the power request value. The system 300 then sends a control command to each electric vehicle used for EM so that the vehicle group power becomes the above power command value. The system 300 may also apportion the power command value for the vehicle group to each electric vehicle. Each electric vehicle performs charging or discharging of the energy storage device according to the control command from the system 300. However, when the aforementioned learning timing arrives, each electric vehicle will perform the aforementioned learning (S12-S14) regardless of the control command. In other words, in each electric vehicle, the aforementioned learning control takes precedence over the control command.

[0028] In the following S23, the system 300 determines whether or not the detection timing has arrived. If the detection timing has arrived (YES in S23), the system 300 detects the power value of the electric vehicle resources (vehicle group power) in S24. The system 300 may obtain the power value from each electric vehicle or from the power meters (e.g., smart meters) at each charging / discharging station. The detection timing arrives every predetermined time (e.g., 1 minute) after the start of EM.

[0029] In the following S25, system 300 determines whether or not EM (Energy Management) has finished. For example, EM ends when the agreed period (time t1 to time t2) has elapsed. If EM is to continue (NO in S25), the process returns to S21. If the agreed period ends (YES in S25), the above processing flow (S21 to S25) ends.

[0030] In the embodiment shown in Figure 2, the electric vehicle resource (vehicle group) performs an EM corresponding to the agreed amount Y. Line L20 shows the transition of the power request value requested by the second request signal. Line L21 shows the actual adjusted power (vehicle group power) by the vehicle group. In this example, multiple electric vehicles perform learning of the offset value of the current sensor 53 at the same time. In S22, the system 300 estimates the power reduction caused by the aforementioned learning. Then, the system 300 sets the power command value to the vehicle group higher than the power request value according to the estimated power reduction. By setting the power command value to the vehicle group higher than the power request value (e.g., agreed amount Y) according to the power reduction, the system 300 ensures that both the power value Y1 (power reduction due to learning) indicating the vehicle group power during learning and the power value Y2 (power value according to the power command value) indicating the vehicle group power when not learning are within an acceptable range. The difference between power value Y2 and power value Y1 shown in Figure 2 corresponds to the power reduction.

[0031] Figure 3 is a diagram comparing graphs showing the changes in vehicle group power for the example and modified example (lines L21, L21A) with a graph showing the changes in vehicle group power for the comparative example (line L22).

[0032] Referring to Figure 3, in the comparative example, the power command value to the vehicle group is determined in accordance with the power request value indicated by the second request signal. As a result, as shown by line L22, the actual adjusted power (vehicle group power) is lower than the acceptable range due to the power reduction caused by the aforementioned learning. In contrast, in the embodiment, the system 300 raises the power command value to the vehicle group to a level higher than the power request value in response to the power reduction caused by the aforementioned learning (S22). As a result, as shown by line L21, the vehicle group power remains within the acceptable range during the contract period.

[0033] As described above, the power management system according to this embodiment comprises a group of vehicles (groups 10G, 20G) including multiple electric vehicles, and a control device (system 300) that controls the group of vehicles. Each of the multiple electric vehicles has an energy storage device (battery 51) and a current sensor 53 that detects the charging and discharging current of the energy storage device, and learns the offset value of the current sensor 53 by setting the charging and discharging current to zero at a predetermined timing (S11~S15). When the control device causes the group of vehicles to perform energy management by charging or discharging the energy storage device, it estimates the power reduction due to the learning regarding the charging power or discharging power of the group of vehicles, and determines a power command value to the group of vehicles for energy management based on the estimated power reduction (S22). With this configuration, even if the charging power or discharging power of the group of vehicles decreases due to the above learning, the power command value to the group of vehicles is increased to compensate for the power reduction, thereby suppressing a shortage of charging power or discharging power for the requested energy management. Therefore, it becomes easier to perform the requested energy management using the multiple electric vehicles.

[0034] In the above embodiment, the power command value to the electric vehicle resources (vehicle group) is not changed unless the power request value changes. In contrast, in the modified example shown in Figure 3, the system 300 predicts the output reduction caused by the learning process and estimates the amount of power reduction caused by the learning process. Then, during the non-learning period, the system 300 determines the power command value to the vehicle group in accordance with the power request value indicated by the second request signal. During the learning period, the system 300 also increases the power command value to the vehicle group to a value higher than the power request value according to the estimated amount of power reduction. In other words, even if the power request value does not change, the system 300 controls the vehicle group based on different power command values ​​during the non-learning period and the learning period. Even with this modified example, as shown by line L21A, it is possible to keep the vehicle group power within an acceptable range during the contract period. When increasing the output in response to an output reduction, the V2H (Vehicle to Home) function, which allows for linear output changes, may also be utilized.

[0035] Alternatively, a TSO (Grid System Operator) may request energy management instead of the electricity market. Systems 100, 200, and 300 are each implemented on an on-premise server, but may also be implemented on the cloud. The functions of each system may be contained in a single device.

[0036] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the description of the embodiments above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0037] 10,20 Vehicles, 51 Batteries, 52 ECUs, 53 Current Sensors, 100 Supply and Demand Management Systems, 200 Resource Management Systems, 300 Electric Vehicle Management Systems, 510,520 Power Supply Equipment, PG Power Systems.

Claims

[Claim 1] A power management system including a group of vehicles including multiple electric vehicles and a control device for controlling the group of vehicles, Each of the aforementioned multiple electric vehicles has a power storage device and a current sensor that detects the charging and discharging current of the power storage device, and is configured to learn the offset value of the current sensor by setting the charging and discharging current to zero at a predetermined timing. The control device is a power management system that, when causing the group of vehicles to perform energy management by charging or discharging the energy storage device, estimates the power reduction due to the learning with respect to the charging power or discharging power of the group of vehicles, and determines a power command value to the group of vehicles for the energy management based on the estimated power reduction.

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