Power management system

Abstract

To provide a power management system which can suppress significant change of a power adjustment amount when a plurality of electronic vehicles which calibrate a current sensor participate in power adjustment.SOLUTION: A power management system 1 comprises: a plurality of electric vehicles 10; and a server 200 (power transmission instruction device). Each of the plurality of electric vehicles 10 comprises a current sensor 12 which detects current which flows by external discharge (power transmission) and calibrates the current sensor 12 for every predetermined period. The server 200 adjusts start timing of the external discharge by at least a part of the plurality of electric vehicles 10 so that timing of calibration of the plurality of electric vehicles 10 deviates when it is predicted that resource total power (the total amount of a power amount to be exchanged by the power transmission) becomes smaller than a lower limit value (predetermined threshold) of an allowable range resulting from overlap of the timing of calibration of the plurality of electric vehicles 10.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This disclosure relates to a power management system.

Background Art

[0002] For example, in Japanese Patent Application Laid-Open No. 2009-171666 (Patent Document 1), during external charging of a plug-in hybrid vehicle (PHEV), the offset value of a current sensor that detects the battery current is calculated by setting the current flowing through the battery (power storage device) to zero at regular intervals (hereinafter referred to as calibration of the current sensor).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, a virtual power plant (VPP) that uses electric vehicles as energy resources has been used to balance power supply and demand. For example, during a period when power supply is greater than power demand, power is stored in the power storage device of the electric vehicle, and during a period when power demand is greater than power supply, the power stored in the power storage device of the electric vehicle is discharged to balance power supply and demand.

[0005]

[0006] The purpose of this disclosure is to provide a power management system that can suppress large changes in the amount of power adjustment when multiple electric vehicles that perform current sensor calibration are participating in power adjustment. [Means for solving the problem]

[0007] A power management system relating to one aspect of this disclosure is a power management system that uses a plurality of electric vehicles, each equipped with an energy storage device, as power adjustment resources, and comprises a plurality of electric vehicles and a power transmission instruction device that instructs each of the plurality of electric vehicles to perform power transmission including at least one of charging and discharging. Each of the plurality of electric vehicles includes a current sensor that detects the current flowing through power transmission, and performs calibration of the current sensor by setting the current flowing through power transmission to 0 at predetermined intervals during the power transmission period. When it is predicted that the total amount of energy exchanged by the plurality of electric vehicles through power transmission will be less than a predetermined threshold due to the overlapping calibration timings of the plurality of electric vehicles, the power transmission instruction device adjusts the start timing of power transmission by the plurality of electric vehicles so that the calibration timings of the plurality of electric vehicles are staggered.

[0008] In the power management system relating to the first aspect described above, if it is predicted that the total amount of power exchanged by power transmission between multiple electric vehicles will fall below a predetermined threshold due to the overlapping calibration timings of multiple electric vehicles, the start timing of power transmission by multiple electric vehicles is adjusted so that the calibration timings of the multiple electric vehicles are staggered. This suppresses the decrease in the total amount of power exchanged by power transmission due to the overlapping calibration timings of multiple electric vehicles. As a result, when multiple electric vehicles performing current sensor calibration participate in power adjustment, it is possible to suppress large changes in the amount of power adjustment. [Effects of the Invention]

[0009] According to this disclosure, when multiple electric vehicles performing current sensor calibration participate in power adjustment, it is possible to suppress large changes in the amount of power adjustment. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows a schematic overall configuration of a power management system according to one embodiment. [Figure 2] Figure 2(A) is the first figure showing the discharge sequence and total resource power of each vehicle before the discharge start timing adjustment. Figure 2(B) is the first figure showing the discharge sequence and total resource power of each vehicle after the discharge start timing adjustment. [Figure 3] Figure 3(A) is the second figure showing the discharge sequence and total resource power of each vehicle before the discharge start timing adjustment. Figure 3(B) is the second figure showing the discharge sequence and total resource power of each vehicle after the discharge start timing adjustment. [Figure 4] This figure shows the control sequence of a server in a power management system according to one embodiment. [Modes for carrying out the invention]

[0011] 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.

[0012] Figure 1 is a diagram showing a schematic overall configuration of the power management system according to this embodiment. Referring to Figure 1, the power management system 1 includes a power grid PG, a plurality of electric vehicles 10, a server 100, and a server 200. Note that server 200 is an example of the "power transmission instruction device" of this disclosure.

[0013] The power grid (PG) is a power network constructed by power plants and transmission / distribution facilities (not shown), and is maintained and managed by the power company. The power company is equivalent to the administrator of the power grid (PG). Server 100 is a server managed by the aggregation coordinator, and distributes power adjustment amounts to the resource aggregator at the request of the power company.

[0014] Server 200 is a computer that manages multiple electric vehicles 10 and is managed by a resource aggregator. Each of the multiple electric vehicles 10 is, for example, a BEV (Battery Electric Vehicle) and is equipped with a power storage device 11. Each electric vehicle 10 is used as a power adjustment resource and is configured to perform external charging and external discharging. In this embodiment, each electric vehicle 10 included in the power management system 1 is assumed to have the same configuration. However, the power management system 1 may include multiple types of vehicles having different configurations. Note that external charging and external discharging are examples of "power transmission" as defined in this disclosure.

[0015] Each of the multiple electric vehicles 10 includes a current sensor 12 that detects the current flowing due to external charging and external discharging. Each of the multiple electric vehicles 10 performs calibration of the current sensor 12 by setting the current flowing due to external charging and external discharging to 0 at predetermined intervals T1 (see Figure 2(A)). A period T2 (see Figure 2(A)) is provided between the start of external charging or external discharging and the first calibration. As shown in Figure 2(A), period T2 is longer than period T1. Period T2 may be less than or equal to period T1. Period T1 is an example of a "predetermined period" in this disclosure.

[0016] Referring again to Figure 1, each charging / discharging device 20 is a charging / discharging device installed on the premises of a facility 30 (for example, a residence and commercial facility). The charging / discharging device 20 may be, for example, a V2H device. Each charging / discharging device 20 charges the energy storage device 11 with power supplied from the power grid PG and supplies (discharges) the power stored in the energy storage device 11 to the electrical loads of the residence and each facility.

[0017] Server 200 includes a control device 210, a storage device 220, and a communication device 230, and is configured to communicate with server 100 and each electric vehicle 10 via network NW. When server 200 receives a power adjustment request from server 100, it creates a charge / discharge plan for each electric vehicle 10 and issues a charge / discharge instruction to each electric vehicle 10 based on the charge / discharge plan. Each electric vehicle 10 performs charge / discharge in cooperation with the charge / discharge facility 20 based on the charge / discharge instruction from server 200.

[0018] Here, as shown in Fig. 2(A), when the calibration of the current sensor 12 is performed simultaneously in a plurality of electric vehicles 10, the timing at which the current flowing due to external charging or external discharging becomes zero is the same in the plurality of electric vehicles 10. Therefore, there is a concern that the amount of charge or discharge due to power adjustment will significantly decrease.

[0019] Specifically, in the example shown in Fig. 2(A), due to the overlapping calibration timings of the current sensor 12 in vehicles A to D, the total resource power (discharge amount in this embodiment) is below the lower limit value of the allowable range centered on the approximate amount of power adjustment. The total resource power is an example of "the total amount of power transmitted and received by power transmission" in the present disclosure. Also, the lower limit value of the above allowable range is an example of "a predetermined threshold value" in the present disclosure. The allowable range is, for example, within ±10% of the approximate amount.

[0020] Therefore, in this embodiment, when server 200 anticipates that the total resource power will be smaller than the lower limit value of the allowable range due to the overlapping calibration timings of the plurality of electric vehicles 10, server 200 adjusts the start timing of external discharging (and external charging) by the plurality of electric vehicles 10 so that the calibration timings of the plurality of electric vehicles 10 are shifted. Server 200 determines whether the total resource power becomes smaller than the lower limit value of the allowable range due to the overlapping of the calibration timings of each vehicle at a predetermined timing. In Fig. 2(A) and Figs. 2(A), 3(A) and (B) described later, the period during which the external discharging of each of vehicles A to D is being executed is represented by a solid line in the rightmost column at the location where vehicles A to D are described.

[0021] In the example shown in FIG. 2(B), the server 200 first simultaneously starts the external discharges of vehicles A to D, and then stops the external discharges of vehicles A to D in that order. Further, the server 200 starts (restarts) the external discharges of vehicles A to D in that order. As a result, the start timings of the external discharges of vehicles A to D are dispersed. Since the calibration timing is uniquely determined based on the start timing of the external discharge, the calibration timings of vehicles A to D are shifted from each other. As a result, a decrease in the total resource power is suppressed. Thereby, the total resource power remains within the allowable range. The server 200 may perform the above determination, for example, before (or at the time of) simultaneously starting the external discharges of vehicles A to D.

[0022] Note that, as shown in FIG. 2(B), the server 200 does not necessarily simultaneously start the external discharges of vehicles A to D. For example, the start timing of the external discharge of at least one of vehicles A to D may be adjusted from the beginning of the power adjustment agreement period.

[0023] FIG. 3(A) is a diagram when the external discharge of vehicle D ends in the middle of the agreement period after the start timings of the external discharges of vehicles A to D are adjusted as in FIG. 2(B). In this case, the external discharge of vehicle E is started instead of vehicle D. In the example shown in FIG. 3(A), the calibration timings of vehicle B and vehicle E overlap.

[0024] In this case, as shown in the example in Figure 3(B), the server 200 prevents the calibration timings of vehicles B and E from overlapping by adjusting the discharge start timing of vehicle E. For example, if the calibration timings overlap occurs because vehicle E starts its external discharge immediately after vehicle D finishes its external discharge (see Figure 3(A)), the server 200 delays the start timing of vehicle E's external discharge by time t. Specifically, vehicle E starts its external discharge immediately after vehicle D finishes its external discharge, then stops the external discharge temporarily. Then, vehicle E resumes its external discharge at time t after vehicle D finishes its external discharge. This prevents the calibration timings of vehicles B and E from overlapping. Time t may be calculated by the server 200 based on the calibration timing of other electric vehicles 10, or it may be a preset fixed value. The server 200 may also make the above determination at the timing when vehicle D finishes its external discharge.

[0025] <Server control flow> Next, with reference to Figure 4, the control flow by the server 200 will be explained. In step S1, the server 200 (control device 210) calculates the amount of reduction in total resource power due to future calibration of the current sensor 12.

[0026] In step S2, the server 200 determines whether the future total resource power will be less than the lower limit of the above acceptable range, based on the decrease in total resource power calculated in step S1. If the future total resource power is less than the above lower limit (Yes in S2), the process proceeds to step S3. If the future total resource power will not fall below the above lower limit (No in S2), the process ends. In step S2, the determination may also be made based on the relationship between the decrease in total resource power itself and a predetermined threshold.

[0027] In step S3, the server 200 determines whether the total resource power at the current time (let's call it t1) after the period T1 (calibration interval) is below the lower limit. If the total resource power at the above time (t1+T1) is not below the lower limit (Yes in S3), the process proceeds to step S4. If the total resource power at the above time (t1+T1) is below the lower limit (No in S3), the process ends. Note that the process in step S3 is not required. Alternatively, in step S3, the determination may be made based on the relationship between the amount of decrease in total resource power at the above time (t1+T1) and a predetermined threshold.

[0028] In step S4, the server 200 selects the electric vehicle 10 that is causing a decrease in total resource power and adjusts (changes) the discharge start timing of the selected electric vehicle 10. After that, the process ends.

[0029] As described above, in this embodiment, when the server 200 predicts that the total resource power will fall below the lower limit of the allowable range due to the overlapping calibration timings of the multiple electric vehicles 10, it adjusts the start timing of external discharge (external charging) by the multiple electric vehicles 10 so that the calibration timings of the multiple electric vehicles 10 are staggered. As a result, the calibration timing is adjusted in conjunction with the adjustment of the start timing of external discharge (external charging), making it easy to resolve the overlap in calibration timings of the multiple electric vehicles 10.

[0030] In the above embodiment, an example was shown where the calibration period T1 and the period T2 from the start of discharge (charging) to the first calibration are the same for each of the multiple electric vehicles 10, but this disclosure is not limited to this. The above periods T1 (T2) may differ for each vehicle.

[0031] In the above embodiment, an example was shown in which the discharge start timing is adjusted while power adjustment is being performed by external discharge, but this disclosure is not limited to this. The charging start timing may also be adjusted while power adjustment is being performed by external charging.

[0032] Furthermore, the configurations of the above embodiments and each of the above modified examples may be combined with each other.

[0033] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure 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]

[0034] 1 Power management system, 10 Electric vehicle, 11 Energy storage device, 12 Current sensor, 200 Server (Power transmission instruction device), T1 Period (specified period).

Claims

[Claim 1] A power management system that uses multiple electric vehicles, each equipped with an energy storage device, as power adjustment resources, The aforementioned multiple electric vehicles, Each of the aforementioned plurality of electric vehicles is provided with a power transmission instruction device that instructs power transmission including at least one of charging and discharging, Each of the aforementioned multiple electric vehicles is It includes a current sensor that detects the current flowing due to the power transmission, During the power transmission period, at predetermined intervals, the current sensor is calibrated by setting the current flowing due to the power transmission to zero. The power transmission instruction device is When it is predicted that the total amount of power exchanged by the power transmission of the multiple electric vehicles will be less than a predetermined threshold due to the overlapping timing of the calibration of the multiple electric vehicles, A power management system that adjusts the start timing of power transmission by the plurality of electric vehicles so that the calibration timings of the plurality of electric vehicles are staggered from one another.

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