Power management system

Abstract

To prevent a power adjustment amount from being significantly changed even if an offset value of a current sensor is calculated in an electric vehicle participating in power adjustment.SOLUTION: A server 200 of a power management system divides electric vehicles participating in power adjustment into a plurality of vehicle groups (S10). The server 200 allocates initial time τ for offset value learning, which is set to different values for each vehicle group (S12), or allocates a different learning cycle T to each vehicle group (S13). Since learning timing of an offset value differs for each vehicle group when power is adjusted, a large increase in the number of learning vehicles is suppressed and a large decrease in a charge amount or a discharge amount by power adjustment can be suppressed.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] For example, in Japanese Unexamined Patent Application Publication 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 battery current is calculated by setting the current flowing through the battery (power storage device) to zero at regular intervals.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, virtual power plants (VPPs) that use electric vehicles as energy resources have 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 devices of electric vehicles, and during a period when power demand is greater than power supply, the power stored in the power storage devices of electric vehicles is discharged, thereby balancing power supply and demand.

[0005] Thus, when using electric vehicles as power adjustment resources, calculating the offset value of the current sensor by setting the current flowing to the energy storage device to zero at predetermined intervals, as described in Patent Document 1, may result in ineffective power adjustment. For example, if the control specifications of multiple electric vehicles participating in power adjustment are the same, the period for calculating the offset value of the current sensor will be almost the same, so the timing at which the current flowing to the energy storage device is set to zero will be almost the same for multiple electric vehicles. As a result, the number of electric vehicles participating in power adjustment whose current flowing to the energy storage device becomes zero at the same time will increase, raising concerns that the amount of charge or discharge due to power adjustment will decrease significantly.

[0006] The purpose of this disclosure is to prevent the amount of power adjustment from changing significantly even if an offset value is calculated from the current sensor in an electric vehicle participating in power adjustment. [Means for solving the problem]

[0007] The power management system of this disclosure is a power management system that uses an electric vehicle equipped with an energy storage device as a power adjustment resource. The electric vehicle has a current sensor that detects the charging and discharging current of the energy storage device and a control device. The control device is configured to set the charging and discharging current to zero at predetermined intervals when the electric vehicle is not participating in power adjustment and to determine the offset value of the current sensor. The power management system includes a charge / discharge instruction means that instructs the electric vehicle to charge and discharge, and the charge / discharge instruction means instructs a vehicle participating in power adjustment on the timing to calculate the offset value of the current sensor.

[0008] In this configuration, the control device for the electric vehicle is configured to set the charge / discharge current to zero at predetermined intervals and determine the offset value of the current sensor when the electric vehicle is not participating in power adjustment. The power management system includes a charge / discharge instruction means for instructing the charging and discharging of the electric vehicle. The charge / discharge instruction means instructs vehicles participating in power adjustment on the timing to calculate the offset value of the current sensor. Since the charge / discharge instruction means instructs vehicles participating in power adjustment on the timing to calculate the offset value of the current sensor, the timing to calculate the offset value of the current sensor can be appropriately instructed so that the amount of power adjustment (amount of charge or discharge due to power adjustment) does not decrease significantly. [Effects of the Invention]

[0009] According to this disclosure, it becomes possible to prevent a significant change in the amount of power adjustment even when the offset value of the current sensor is calculated in an electric vehicle participating in power adjustment. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows a schematic overall configuration of the power management system according to this embodiment. [Figure 2] This is a schematic diagram of the electric vehicle's configuration. [Figure 3] Figures (A) to (D) illustrate the sequence of offset value learning timing instructions according to this 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 the 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.

[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. Server 200 corresponds to an example of the “charge / discharge instruction means” in this disclosure. 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.

[0015] Figure 2 is a schematic diagram of the electric vehicle 10. The electric vehicle 10 comprises a motor generator (MG) 1, a power transmission gear 2, drive wheels 3, and a power control unit (PCU) 4. The electric vehicle 10 also comprises a system main relay (SMR) 5, a power storage device 11, a monitoring unit 8, and an electronic control unit (ECU) 9, which is a control device. The MG 1 is, for example, an IPM motor, and has both the function of an electric motor and a generator. The output torque of the MG 1 is transmitted to the drive wheels 3 via the power transmission gear 2, which is configured to include a reduction gear and a differential gear.

[0016] When the electric vehicle 10 is braked, the MG1 is driven by the drive wheels 3, and the MG1 operates as a generator. In this way, the MG1 also functions as a braking device that performs regenerative braking, converting the kinetic energy of the electric vehicle 10 into electrical power. The regenerative power generated by the regenerative braking force in the MG1 is stored in the energy storage device 11. The PCU 4 is a power converter that converts power bidirectionally between the MG1 and the energy storage device 11.

[0017] The SMR5 is electrically connected to the power line connecting the energy storage device 11 and the PCU4. When the SMR5 is closed (ON) in response to a control signal from the ECU9, power can be exchanged between the energy storage device 11 and the PCU4. On the other hand, when the SMR5 is open (OFF), the electrical connection between the energy storage device 11 and the PCU4 is interrupted.

[0018] The energy storage device 11 is a rechargeable DC power source (secondary battery), and is composed of multiple single cells stacked and electrically connected in series, for example. The single cells may be lithium-ion batteries. The monitoring unit 8 includes a voltage sensor 81, a current sensor 82, and a temperature sensor 83. The current sensor 82 detects the current (charge / discharge current) IB that is input to and output from the energy storage device 11. The detection signals from each sensor are input to the ECU 9.

[0019] The electric vehicle 10 is equipped with an inlet 6, and the energy storage device 11 is capable of external charging and external power supply (external discharge) via the charging / discharging equipment 20. A charging / discharging relay 7 is electrically connected to the power line connecting the inlet 6 and the energy storage device 11, and switches between supplying and interrupting power between the inlet 6 and the energy storage device 11. When a connector (plug) 22 provided at the end of the charging / discharging cable 21 of the charging / discharging equipment 20 is connected to the inlet 6 and the charging / discharging relay 7 is closed (ON), the energy storage device 11 is charged (externally charged) from the power grid PG (external power source) via the charging / discharging equipment 20. In addition, the power stored in the energy storage device 11 is supplied (discharged) to an external load (for example, electrical equipment in facility 30) via the charging / discharging equipment 20.

[0020] When the power storage device 11 is externally charged or externally supplying power, the ECU 9 calculates the offset value of the current sensor 82. When starting external charging or external power supply, the ECU 9 opens (turns OFF) the charge / discharge relay 7 and the SMR 5 for a predetermined time tm (for example, 5 seconds) every predetermined period P (for example, every 15 minutes), sets the input / output current of the power storage device 11 to zero, obtains the offset value of the current sensor 82, and stores it in a memory (not shown). Hereinafter, obtaining the offset value of the current sensor 82 and storing it in the memory is also referred to as "learning of the offset value". If the input / output current of the power storage device 11 can be set to zero, the states of the charge / discharge relay 7 and the SMR 5 can be either. In this embodiment, it is assumed that each electric vehicle 10 included in the power management system 1 has the same configuration. However, the power management system 1 may include a plurality of types of vehicles having different configurations.

[0021] Each charge / discharge facility 20 is a charge / discharge facility installed within the premises of a facility 30 (for example, a house, a commercial facility, etc.). The charge / discharge facility 20 may be, for example, V2H equipment. Each charge / discharge facility 20 charges the power storage device 11 with the power supplied from the power grid PG, and supplies (discharges) the power stored in the power storage device 11 to the electrical loads of houses and each facility. Also, each charge / discharge facility 20 is capable of supplying (reverse power flow) the power stored in the power storage device 11 to the power grid PG. By connecting the charge / discharge cable 21 connected to the charge / discharge facility 20 to the inlet 6 of the electric vehicle 10, it becomes possible to transfer power between the charge / discharge facility 20 and the electric vehicle 10.

[0022] The server 200 includes a control device 210, a storage device 220, and a communication device 230, and is configured to be able to communicate with the server 100 and each electric vehicle 10 via the network NW. When the server 200 receives a request for power adjustment from the server 100, it creates a charge / discharge plan for each electric vehicle 10 and gives 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 of the server 200.

[0023] FIG. 3 is a diagram for explaining a sequence of offset value learning timing instructions according to the present embodiment. As shown in FIG. 3(A), when the server 200 receives a power adjustment request from the server 100, it recruits the electric vehicles 10 that can participate in the power adjustment together with information such as the type of power adjustment (charging or discharging (power supply)), the power adjustment time, and the adjusted power amount, and extracts the target vehicles participating in the power adjustment (S10). When the target vehicles participating in the power adjustment are extracted, the participating vehicles are divided (grouped) into a plurality of vehicle groups (S11). The number of groups may be arbitrary. For example, it may be 10 groups or 100 groups, and may be set according to the number of participating vehicles.

[0024] Next, the server 200 sets the learning timing of the offset value for each vehicle group (each group). For example, the first time τ, which is the timing to first execute the learning of the offset value from the start of the power adjustment, is allocated to each vehicle group (S12). As shown in FIG. 3(B), when the first time τ has elapsed from the start of the power adjustment, in the electric vehicle 10, the learning of the offset value is executed, and thereafter, the learning of the offset value is executed every learning cycle T. In this case, the learning cycle T may be a cycle corresponding to a predetermined period P (for example, 15 minutes) set by the ECU 9. The first time τ is set to a different value for each vehicle group (each group) and is a value different from the predetermined period P. Alternatively, as shown in FIG. 3(C), the server 200 allocates different learning cycles T to each vehicle group (each group) (S13). In this case, the learning cycle T is different from the predetermined period P (for example, 15 minutes) set by the ECU 9 and is set to a different value for each vehicle group.

[0025] When the first time τ or the learning cycle T is allocated with different values for each vehicle group, the allocated first time τ or learning cycle T is transmitted to the electric vehicle 10 (S14). When each electric vehicle 10 receives the allocated first time τ or learning cycle T, it sets the learning timing using the received first time τ or learning cycle T, and when the learning timing is reached during the power adjustment, it executes the offset learning.

[0026] Figure 3(D) shows the change in the number of vehicles learning the offset value during power adjustment. In Figure 3(D), the dashed line represents the number of electric vehicles 10 participating in power adjustment. The dashed line represents the change in the number of vehicles learning in the conventional technology, where offset learning is performed at predetermined intervals P set by the ECU 9. If the control specifications of the electric vehicles 10 are the same, the predetermined interval P is the same value, so the electric vehicles 10 participating in power adjustment start offset learning almost simultaneously. As a result, the number of vehicles learning increases significantly, as shown by the dashed line. During offset learning, the charge / discharge current of the energy storage device 11 is set to zero, so there is a concern that the amount of charge or discharge due to power adjustment will decrease significantly.

[0027] In this embodiment, the server 200 sets the learning timing for the offset value for each group of electric vehicles 10 participating in power adjustment. For example, an initial time τ, which is set to a different value for each group of vehicles, is assigned to each group of vehicles (S12), or a different learning period T is assigned to each group of vehicles (S13). Therefore, during power adjustment, the learning timing for the offset value differs for each group of vehicles according to the instructions of the server 200, so that the number of vehicles learning does not increase significantly, as shown by the solid line in Figure 3(D), and the amount of charge or discharge due to power adjustment does not decrease significantly.

[0028] In the above embodiment, a different initial time τ or a different learning period T was assigned to each vehicle group (each vehicle group). However, a different initial time τ or a different learning period T may be assigned to each electric vehicle 10 participating in power adjustment.

[0029] 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]

[0030] 1 Power Management System, 8 Monitoring Units, 9 ECUs, 10 Vehicles, 11 Energy Storage Devices, 20 Charging and Discharging Equipment, 30 Facilities, 81 Current Sensors, 100,200 Servers, NW Network, PG Power System.

Claims

[Claim 1] A power management system that uses electric vehicles equipped with energy storage devices as power adjustment resources, The electric vehicle has a current sensor for detecting the charging and discharging current of the energy storage device, and a control device. The control device is configured to determine the offset value of the current sensor by setting the charge / discharge current to zero at predetermined intervals when the energy storage device is being externally charged or externally powered. The power management system includes charge / discharge instruction means for instructing the charging and discharging of the electric vehicle, The charge / discharge instruction means divides the electric vehicles participating in the power adjustment into a plurality of vehicle groups, and instructs the electric vehicles participating in the power adjustment such that the initial time, which is the timing at which the offset value is first determined from the start of the power adjustment, or the predetermined period, differs for each vehicle group. or The charge / discharge instruction means is a power management system that instructs electric vehicles participating in the power adjustment to have a different initial time for determining the offset value from the start of the power adjustment, or a predetermined period, for each electric vehicle.

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