Power Management System

Abstract

To suppress considerable reduction of a power adjustment amount regardless of participation in the power adjustment of the electric vehicle which executes specific control setting a charge / discharge current of a power storage device to zero.SOLUTION: A server 200 divides electric vehicles that participate in a power adjustment into a vehicle group A and a vehicle group B (S11). The vehicle group A executes offset learning of a current sensor, setting a charge / discharge current of a power storage device to zero in a fixed frequency after start of charge / discharge. The vehicle group B executes offset learning in a higher frequency than the fixed frequency during a predetermined period after start of charge / discharge and then executes offset learning in the fixed frequency. The server 200 instructs charge / discharge start timing in such a manner that the number of electric vehicles 10 to execute the offset learning at the same timing becomes equal to or less than a predetermined number and in such a manner that the electric vehicles 10 of the vehicle group B execute the offset learning at least once within a reaction time of the power adjustment (S12 and S13).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to power management systems. [Background technology]

[0002] For example, Japanese Patent Application Laid-Open No. 2009-171666 (Patent Document 1) describes that during external charging of a plug-in hybrid vehicle (PHEV), the current flowing to the battery (electrical storage device) is set to zero at regular intervals, and an offset value of a current sensor that detects the battery current is calculated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-171666 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, efforts have been made to equalize the supply and demand of electricity by using virtual power plants (VPPs) that use electric vehicles as energy resources. For example, during periods when the supply of electricity exceeds the demand for electricity, electricity is stored in the power storage devices of the electric vehicles, and during periods when the demand for electricity exceeds the supply of electricity, the stored electricity in the power storage devices of the electric vehicles is discharged, thereby equalizing the supply and demand of electricity.

[0005] When using an electric vehicle as a power adjustment resource, as described in Patent Document 1, if the current flowing through the power storage device is set to zero at predetermined time intervals and the offset value of the current sensor is calculated, power adjustment may not be performed properly. For example, if the control specifications of electric vehicles are the same, the cycle for calculating the offset value of the current sensor will be approximately the same, and therefore the timing at which the current flowing through the power storage device is set to zero may be approximately the same for all electric vehicles participating in power adjustment. As a result, the number of electric vehicles participating in power adjustment whose current flowing through the power storage device simultaneously becomes zero may increase, raising concerns that the amount of charge or discharge due to power adjustment may be significantly reduced.

[0006] In addition, there may be an electric vehicle that has a period set in which the offset value of the current sensor is calculated more frequently (the predetermined time is shorter) after the start of charging or discharging of the power storage device. In this case, there is a concern that the charging amount or discharging amount may be significantly reduced more frequently due to power adjustment.

[0007] An object of the present disclosure is to prevent a large decrease in the amount of power adjustment even when an electric vehicle that executes specific control by setting the charge / discharge current of a power storage device to zero participates in power adjustment. [Means for solving the problem]

[0008] The power management system disclosed herein uses a plurality of electric vehicles, each equipped with a power storage device, as power adjustment resources. Each electric vehicle has a control device configured to execute specific control by setting the charge / discharge current of the power storage device to zero at a predetermined frequency. The plurality of electric vehicles includes a first vehicle that executes the specific control at a constant frequency and a second vehicle that executes the specific control at a frequency higher than the constant frequency for a predetermined period from the start of charging / discharging of the power storage device. The power management system includes a charge / discharge instruction means that instructs the plurality of electric vehicles to charge / discharge. The charge / discharge instruction means instructs the timing of starting charge / discharge of each electric vehicle so that the number of electric vehicles that execute the specific control at the same time during power adjustment is equal to or less than a predetermined number, and also instructs the timing of starting charge / discharge of the second vehicle so that the second vehicle executes the specific control at least once within the response time of power adjustment.

[0009] In the present disclosure, "charging / discharging" includes performing at least one of "charging" and "discharging." Therefore, "charging / discharging start timing" refers to at least one of "charging start timing" and "discharging start timing." The response time is the allowable period from receiving a power adjustment command until the commanded adjustment amount is achieved.

[0010] The charge / discharge instruction means instructs the timing to start charge / discharge for each electric vehicle so that the number of electric vehicles that execute specific control at the same time during power adjustment is equal to or less than a predetermined number, thereby reducing the number of vehicles whose current flowing through the power storage devices simultaneously becomes zero during power adjustment. Also, the charge / discharge start timing is instructed so that the second vehicle executes specific control at least once within the response time of power adjustment, thereby reducing the frequency with which the current flowing through the power storage devices of multiple electric vehicles simultaneously becomes zero during power adjustment (after the response time has elapsed). [Effects of the Invention]

[0011] According to the present disclosure, even if an electrically powered vehicle that executes specific control by setting the charge / discharge current of the power storage device to zero participates in power adjustment, a large decrease in the amount of power adjustment can be suppressed. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing a schematic overall configuration of a power management system according to an embodiment of the present invention; [Figure 2] FIG. 1 is a schematic configuration diagram of an electric vehicle. [Figure 3] 10A to 10C are diagrams illustrating a sequence of instructions for instructing the start timing of charging and discharging according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and their description will not be repeated.

[0014] Fig. 1 is a diagram showing a schematic overall configuration of a power management system according to the present embodiment. Referring to Fig. 1, power management system 1 includes a power system PG, a plurality of electrically powered vehicles 10A, 10B, a server 100, and a server 200. Electrically powered vehicles 10A, 10B have the same basic configuration, and will be referred to as electric vehicle 10 unless otherwise distinguished.

[0015] The power system PG is a power network constructed by power plants and power transmission and distribution facilities (not shown), and is maintained and managed by a power company. The power company corresponds to the administrator of the power system PG. The server 100 is managed by an aggregation coordinator, and distributes power adjustment amounts to resource aggregators in response to requests from the power company.

[0016] The server 200 is a computer that manages a plurality of electric vehicles 10, and is managed by a resource aggregator. The server 200 corresponds to an example of a "charge / discharge instruction means" in the present disclosure. Each of the plurality of 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 be able to perform external charging and external discharging.

[0017] FIG. 2 is a schematic diagram of an electric vehicle 10. The electric vehicle 10 includes 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 includes 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 functions as both 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 includes a reduction gear, a differential device, and the like. When the electric vehicle 10 is braked, the MG 1 is driven by the drive wheels 3, operates as a generator, and regenerative power generated by regenerative braking force is stored in the power storage device 11. The PCU 4 is a power conversion device that converts power bidirectionally between the MG 1 and the power storage device 11.

[0018] The SMR 5 is electrically connected to a power line connecting the power storage device 11 and the PCU 4. When the SMR 5 is closed (ON) in response to a control signal from the ECU 9, power can be exchanged between the power storage device 11 and the PCU 4. On the other hand, when the SMR 5 is open (OFF), the electrical connection between the power storage device 11 and the PCU 4 is cut off.

[0019] The power storage device 11 is a rechargeable DC power supply (secondary battery) and is configured by stacking a plurality of single cells (battery cells) and, for example, electrically connecting them in series. The monitoring unit 8 includes a voltage sensor 81, a current sensor 82, and a temperature sensor 83. The current sensor 82 detects a current (charge / discharge current) IB input / output to / from the power storage device 11. The detection signals of each sensor are input to the ECU 9.

[0020] The electric vehicle 10 includes an inlet 6, and the power storage device 11 is capable of external charging and external power supply (external discharging) via a charging / discharging facility 20. A charging / discharging relay 7 is electrically connected to a power line connecting the inlet 6 and the power storage device 11, and switches between supplying and cutting off power between the inlet 6 and the power storage device 11. When a connector (plug) 22 provided at the end of a charging / discharging cable 21 of the charging / discharging facility 20 is connected to the inlet 6 and the charging / discharging relay 7 is closed (ON), the power storage device 11 is charged (externally charged) from a power grid PG (external power source) via the charging / discharging facility 20. Furthermore, the power stored in the power storage device 11 is supplied (discharged) to an external load (for example, electrical equipment in facility 30) via the charging / discharging facility 20.

[0021] The ECU 9 calculates an offset value of the current sensor 82 when the power storage device 11 is being externally charged or externally powered. When external charging or external power feeding starts, the ECU 9 opens (turns off) the charge / discharge relay 7 and the SMR 5 to set the input / output current of the power storage device 11 to zero, and then calculates an offset value of the current sensor 82 and stores it in a memory (not shown). Calculating the offset value of the current sensor 82 and storing it in a memory is also referred to as "offset learning." The offset learning corresponds to an example of the "specific control" of the present disclosure.

[0022] In this embodiment, the ECU 9 performs offset learning in different modes for the electrically powered vehicles 10A and 10B. When external charging or external power feeding starts, the ECU 9 of the electrically powered vehicle 10A opens (turns OFF) the charge / discharge relay 7 and the SMR 5 for a set time tm (for example, 5 seconds) at predetermined time intervals P0 (for example, every 15 minutes) to zero the input / output current of the power storage device 11 and performs offset learning. As long as the input / output current of the power storage device 11 can be zero, the states of the charge / discharge relay 7 and the SMR 5 do not matter. In this way, the offset learning is performed at a fixed frequency in the electrically powered vehicle 10A. The electrically powered vehicle 10A corresponds to the "first vehicle" in this disclosure.

[0023] When external charging or external power feeding starts, ECU 9 of electric vehicle 10B performs offset learning by setting the charge / discharge current of power storage device 11 to zero for a set time tm every predetermined time P1 (for example, every minute) for a predetermined period S (for example, 10 minutes) after the start of external charging or external power feeding. Then, after the predetermined period S has elapsed, ECU 9 performs offset learning by setting the input / output current of power storage device 11 to zero for a set time tm every predetermined time P0. Predetermined time P1 is shorter than predetermined time P0, and in electric vehicle 10B, the frequency of offset learning is higher during the predetermined period S from the start of charging / discharging compared to after the predetermined period S has elapsed. Electric vehicle 10B corresponds to the "second vehicle" in this disclosure.

[0024] Each charging / discharging equipment 20 is a charging / discharging equipment installed on the premises of a facility 30 (for example, a house, a commercial facility, etc.). The charging / discharging equipment 20 may be, for example, a V2H device. Each charging / discharging equipment 20 charges an electricity storage device 11 with power supplied from a power grid PG, and supplies (discharges) the power stored in the electricity storage device 11 to an electrical load in the house or each facility. Each charging / discharging equipment 20 is also capable of supplying (reverse power flow) the power stored in the electricity storage device 11 to the power grid PG. A charging / discharging cable 21 connected to the charging / discharging equipment 20 is connected to an inlet 6 of the electric vehicle 10, thereby enabling power to be exchanged between the charging / discharging equipment 20 and the electric vehicle 10.

[0025] 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 server 100 and each electric vehicle 10 via network NW. When server 200 receives a request for power adjustment from server 100, it creates a charge / discharge plan for each electric vehicle 10 and issues instructions to each electric vehicle 10 to charge or discharge based on the charge / discharge plan. Each electric vehicle 10 charges or discharges in cooperation with charging / discharging facility 20 based on the charge / discharge instructions from server 200.

[0026] Fig. 3 is a diagram illustrating the sequence of issuing a charge / discharge start timing instruction according to this embodiment. As shown in Fig. 3(A), when server 200 receives a request for power adjustment from server 100, server 200 solicits electrically powered vehicles 10 that can participate in the power adjustment along with information such as the type of power adjustment (charging or discharging (power supply)), the time of power adjustment, and the amount of power to be adjusted, and extracts target vehicles that will participate in the power adjustment (S10). Once the target vehicles that will participate in the power adjustment are extracted, the participating vehicles are divided into groups of electrically powered vehicles 10A and electric vehicles 10B (S11). Information (such as an ID) of each electric vehicle 10 is stored in storage device 220.

[0027] Next, the server 200 sets the timing to start charging and discharging for the electric vehicles 10 (S12). The server 200 sets the timing to start charging and discharging for each electric vehicle 10 so that the number of electric vehicles 10 that perform offset learning at the same time is equal to or less than a predetermined number. At the same time, the server 200 sets the timing to start charging and discharging for each electric vehicle 10B so that offset learning for electric vehicle 10B is performed at least once within the response time of power adjustment. The response time is the allowable period from when a command for power adjustment is received until the commanded adjustment amount (instructed amount) is achieved.

[0028] As shown in FIG. 3(B), the timing at which charge / discharge starts for each of electric vehicles 10B is set so that offset learning (see ● in FIG. 3(B)) is performed at least once within the response time of power adjustment (time t0 to time t1), so it is preferable that the timing at which charge / discharge starts for vehicle group B is set earlier than the timing at which charge / discharge starts for vehicle group A. As shown in FIG. 3(B), by having each electric vehicle 10 sequentially start charge / discharge, it is possible to keep the number of electric vehicles 10 that perform offset learning at the same time below a predetermined value. Furthermore, because offset learning for electric vehicle 10B is performed at least once within the response time, it is possible to reduce the frequency at which offset learning is performed simultaneously during power adjustment (adjustment period: after the response time has elapsed) (it is possible to reduce the frequency at which currents flowing through multiple power storage devices 11 simultaneously become zero).

[0029] Once the charge / discharge start timing is set, it is transmitted to the electric vehicles 10 (S13). Upon receiving the charge / discharge start timing, each electric vehicle 10 sets the charge / discharge timing for each electric vehicle 10, and starts charging / discharging the electricity storage device 11 when the charge / discharge start timing arrives.

[0030] FIG. 3(C) is a diagram showing the transition of the number of vehicles undergoing offset learning during power adjustment. In FIG. 3(C), the dashed line indicates the number of electric vehicles 10 participating in power adjustment. The dashed-dotted line indicates the transition of the number of vehicles undergoing learning in the prior art, showing a case where the timing at which each electric vehicle starts charging and discharging is approximately the same. The electric vehicles 10 participating in power adjustment start offset learning at approximately the same time. For this reason, as shown by the dashed-dotted line, the number of vehicles undergoing learning increases significantly. During offset learning, the charge / discharge current of the power storage device 11 is set to zero, which raises concerns that the amount of charge or discharge due to power adjustment may decrease significantly.

[0031] In this embodiment, the timings at which the electric vehicles 10 participating in power adjustment start charging and discharging are to start are set so that the number of electric vehicles 10 performing offset learning at the same time is equal to or less than a predetermined value. Therefore, as shown by the solid line in Fig. 3(C), a large increase in the number of vehicles to be learned is suppressed, and a large decrease in the amount of charge or discharge due to power adjustment can be suppressed.

[0032] In Figure 3(B), the dashed-dotted line indicates the commanded amount of power adjustment, and the solid line indicates the actual amount of power adjustment. Because the charge or discharge amount due to power adjustment does not decrease significantly, the actual amount falls within the allowable range indicated by the dashed line. By providing a slope to the commanded amount (dashed-dotted line) during the response time, the timing at which charge and discharge begin for electric vehicles 10 participating in power adjustment can be set so that the number of electric vehicles 10 performing offset learning at the same time is equal to or less than a predetermined value.

[0033] In addition, if the electrically powered vehicles 10 participating in the power adjustment include a vehicle that does not perform offset learning, the timing at which charging and discharging of that vehicle starts may be set to start after vehicle group A.

[0034] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0035] 1 Power management system, 8 Monitoring unit, 9 ECU, 10 Vehicle, 11 Energy storage device, 20 Charging / discharging equipment, 30 Facility, 81 Current sensor, 100,200 Server, NW network, PG power system.

Claims

[Claim 1] A power management system using a plurality of electric vehicles, each equipped with a power storage device, as power adjustment resources, comprising: Each of the plurality of electric vehicles has a control device, the control device is configured to execute specific control by setting a charge / discharge current of the power storage device to zero at a predetermined frequency; the plurality of electric vehicles include a first vehicle whose frequency is a constant frequency and a second vehicle whose frequency is higher than the constant frequency for a predetermined period from the start of charging / discharging of the power storage device, the power management system includes a charge / discharge instruction means for instructing the plurality of electric vehicles to charge / discharge, The charge / discharge instruction means during power adjustment, instructing the timing to start charging / discharging of each of the plurality of electric vehicles so that the number of electric vehicles that execute the specific control at the same time is equal to or less than a predetermined number; and an electric power management system that instructs the second vehicle to execute the specific control at least once within a response time of the electric power adjustment;

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