Power management apparatus and power management method

In a server, an acquisition unit obtains, from a vehicle through a communication apparatus, history information indicating that demand and supply of electric power has been performed for a power grid PG, and information on the state of charge of a battery. A control unit determines priorities of a plurality of DERs for a DR request. The control unit determines a priority of the vehicle so that the vehicle is less likely to be selected for the DR request, when the SOC obtained by the acquisition unit has changed although the acquisition unit has not received the history information.

This nonprovisional application is based on Japanese Patent Application No. 2021-011920 filed on Jan. 28, 2021 with the Japan Patent Office, the entire content of which is hereby incorporated by reference.

BACKGROUND

Field

The present disclosure relates to a power management apparatus and a power management method, and, more particularly, to a power management apparatus and a power management method for managing demand response which requests multiple power adjustment resources electrically connectable to a power network to adjust supply and demand of electric power for the power network.

Description of the Background Art

For the power management apparatus and power management method as mentioned above, WO 2020/158592 discloses a server device selecting, using information on the reliability of electric power customers, a customer to be requested for a demand response (referred to as “DR” below). As used herein, the information on the reliability of a customer refers to a rate of achievement to a DR request (a percentage of the amount of electric power achieved during a DR request period to a requested amount of electric power) or a stay rate to a DR request (a rate per unit time of a period of time in which the amount of electric power responded to a DR request falls within a predetermined range (for example, plus or minus 20%) of a requested amount of electric power).

It is considered to actively use vehicles that have batteries mounted thereon, as power adjustment resources that can participate in DR. When a vehicle, participating in a DR, and a power management apparatus (server), managing the DR, exchange various information over wireless communications, the power management apparatus cannot appropriately obtain the information for use in DR from the vehicle if the communication condition is poor. As a result, appropriate adjustment of supply and demand of electric power may not be performed in response to the DR request. If appropriate adjustment of supply and demand of electric power is not performed in response to the DR request while the vehicle is participating in DR, a customer may suffer from drawbacks, such as being subjected to penalty.

SUMMARY

The present disclosure is made in view of the problem above, and an object of the present disclosure is to provide a power management apparatus and a power management method that can reduce drawbacks for a customer caused by appropriate adjustment of supply and demand of electric power not being performed in response to a DR request.

A power management apparatus according to the present disclosure is a power management apparatus for managing a DR which requests a plurality of power adjustment resources, electrically connectable to a power network, to perform adjustment of supply and demand of electric power for the power network. The plurality of power adjustment resources include a vehicle on which a battery is mounted. The power management apparatus includes: a communication apparatus that wirelessly communicates with the vehicle; an acquisition unit; and a control unit. The acquisition unit obtains, from the vehicle through the communication apparatus, history information indicating that the demand and supply of electric power has been performed for the power network, and information on a state of charge of the battery. The control unit determines priorities of the plurality of power adjustment resources for a request for the DR. When the acquisition unit has not obtained the history information even though the state of charge, obtained by the acquisition unit, has changed, the control unit determines a priority of the vehicle so that the vehicle is less likely to be selected for the request for the DR.

A power management method according to the present disclosure is a power management method for managing a DR which requests a plurality of power adjustment resources, electrically connectable to a power network, to perform adjustment of supply and demand of electric power for the power network. The plurality of power adjustment resources include a vehicle on which a battery is mounted. The power management method includes: wirelessly transmitting, from the vehicle to a server, history information indicating that the demand and supply of electric power has been performed for the power network; wirelessly transmitting, from the vehicle to the server, information on a state of charge of the battery; and determining priorities of the plurality of power adjustment resources for a request for the demand response. Determining the priorities includes determining a priority of the vehicle so that the vehicle is less likely to be selected for the request for the DR, when the server has not obtained the history information even though the state of charge of the battery, obtained by the server, has changed.

In the power management apparatus and power management method above, if the acquisition unit has not obtained the history information from the vehicle even though the state of charge of the battery has changed, the reliability of wireless communications between the power management apparatus and the vehicle is considered as being degraded, and the priority of the vehicle is determined so that the vehicle is less likely to be selected for a DR request. This can avoid a situation in which, despite the fact that the vehicle is participating in DR, no appropriate adjustment of supply and demand of electric power is performed in response to a DR request due to the degradation of the communication reliability. Therefore, according to the power management apparatus and the power management method, a customer can be prevented from suffering from drawbacks (such as being subjected to penalty) caused by appropriate adjustment of supply and demand of electric power not being performed in response to a DR request.

The history information may include information indicating at least one of start and end of changing of the battery from the power network.

The history information may include information indicating at least one of start and end of discharging of electric power from the battery to the power network.

The history information may include information indicating at least one of electrical connection and electrical disconnection between the power network and the vehicle.

If the history information as the above is not obtained from the vehicle, the communication reliability with the vehicle is considered as being degraded. Consequently, even though the state of charge of the battery of the vehicle has changed, the priority of the vehicle is determined so that the vehicle is less likely to be selected for the DR request. Accordingly, a customer can be prevented from suffering from drawbacks caused by appropriate adjustment of supply and demand of electric power not being performed in response to a DR request due to the degradation of the communication reliability.

A change in the state of charge of the battery may be a change since deactivation of a travel system of the vehicle until activation of the travel system of the vehicle.

The acquisition unit further may obtain location information of the vehicle from the vehicle. A change in the state of charge of the battery may be a change when the location information of the vehicle is constant.

The acquisition unit may further obtain a travel distance of the vehicle from the vehicle. A change in the state of charge of the battery may be a change when the travel distance of the vehicle is constant.

Such a change in the state of charge of the battery as the above is a change in the state of charge while the vehicle is being parked, and can indicate that the demand and supply of electric power has been performed for the power network. However, if the acquisition unit has not obtained the history information on demand and supply of electric power, the communication reliability is considered as being degraded, and the priority of the vehicle is determined so that the vehicle is less likely to be selected for the DR request the vehicle. Accordingly, a customer can be prevented from suffering from drawbacks caused by appropriate adjustment of supply and demand of electric power not being performed in response to a DR request due to the degradation of the communication reliability.

When an amount of change in the state of charge of the battery, obtained by the acquisition unit, exceeds a threshold and the acquisition unit has not obtained the history information, the control unit may determine the priority of the vehicle so that the vehicle is less likely to be selected for the request for the DR.

Since demand and supply of electric power is not performed for the power network while the vehicle is traveling, no history information is obtained. On the other hand, the state of charge of the battery is changed by the vehicle traveling. Thus, a change in the state of charge while the vehicle is traveling may end up determining the priority of the vehicle so that the vehicle is less likely to be selected for the DR request. Thus, as described above, if a change in state of charge is greater than the threshold, the priority of the vehicle is determined so that the vehicle is less likely to be selected for the DR request, thereby preventing the priority of the vehicle from being unnecessary lowered. It should be noted that, since an average amount of change in state of charge when demand and supply of electric power is performed for the power network is considered as being greater than average amount of change in state of charge while the vehicle is traveling (because electric power is discharged and charged while the vehicle is traveling), the threshold is appropriately set to a value that allows average amounts of change in the SOCs in the above two cases to be distinguishable, for example.

The history information may include information indicating that the battery has been charged from the power network. When the acquisition unit has not obtained the history information even though the state of charge, obtained by the acquisition unit, has risen, the control unit may determine the priority of the vehicle so that the vehicle is less likely to be selected for the request for the DR.

This can avoid a situation in which, despite the fact that the vehicle is participating in DR, the vehicle does not perform appropriate charging (electric power demand) in response to a DR request due to the degradation of the communication reliability. Accordingly, a customer can be prevented from suffering from drawbacks caused by charging of the battery not being performed in response to a DR request.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments according to the present disclosure will be described, with reference to the accompanying drawings. Note that the same reference signs are used to refer to the same or like parts, and the description thereof will not be repeated.

FIG.1is a diagram showing a configuration of a power management system which includes a power management apparatus according to an embodiment of the present disclosure. Referring toFIG.1, a power management system1includes: a power grid PG; a server30corresponding to a power management apparatus; an electric vehicle supply equipment (EVSE)40; a vehicle50; and a portable terminal80.

The vehicle50includes an inlet110, a charger-discharger120, a battery130, an electronic control unit (ECU)150, and a communication device180. The vehicle50is configured to transmit/receive electric power to/from the power grid PG through the inlet110. In other words, as the vehicle50is electrically connected to the EVSE40through the inlet110, the vehicle50can store electric power, which is supplied from the power grid PG, into the battery130, or supply the power grid PG with the electric power stored in the battery130. Note that, in the following, charging the battery130from the power grid PG by the EVSE40may be referred to as “external charging” and supplying the power grid PG with electric power stored in the battery130by the EVSE40may be referred to as “external electric power supply.”

The inlet110is configured to be electrically connected to a connector43of an electric power cable42extending from the EVSE40. As the connector43is connected to the inlet110, the vehicle50can receive electric power from the power grid PG, or supply electric power to the power grid PG. WhileFIG.1shows only the inlet110(and the charger-discharger120) that supports the powering scheme of the EVSE40, it should be noted that the vehicle50may include multiple inlets to support multiple types of power supply schemes (for example, an AC (alternate current) power supply scheme and a DC (direct current) power supply scheme).

The charger-discharger120includes: a relay (not shown) which is provided on a power path between the inlet110and the battery130and switches electrical connection/disconnection of the power path; and a power converter circuit (not shown). During external charging, the charger-discharger120converts the electric power, input from the inlet110, into electric power that has the voltage level of the battery130, and outputs the electric power to the battery130. During external electric power supply, on the other hand, the charger-discharger120converts the electric power discharged from the battery130into electric power having a voltage level appropriate for the external electric power supply, and outputs the electric power to the inlet110. For example, the power converter circuit is configured of a bidirectional converter.

The battery130includes a secondary battery, such as a lithium-ion secondary battery or a nickel-metal hydride secondary battery. During external charging, the battery130is charged with the supply of electric power output from the charger-discharger120. During external electric power supply, the battery130outputs to the charger-discharger120the electric power stored in the battery130. In this way, the electric power supplied from the power grid PG (the EVSE40) is stored in the battery130, and the electric power stored in the battery130is supplied to the power grid PG (the EVSE40), thereby allowing the vehicle50to function as a power adjustment resource that can respond to a DR request. The battery130is also capable of storing regenerative power generated by a travel motor (not shown) at the time of breaking of the vehicle.

The ECU150includes a processor (such as a central processing unit (CPU)), a random access memory (RAM), a read only memory (ROM), etc. (none of which are shown). The processor deploys programs stored in the ROM into the RAM, etc., and executes the programs. Various control processes performed by the ECU150are written in the programs stored in the ROM.

The ECU150performs various controls on the vehicle50. For example, the ECU150performs a traveling control on the vehicle50. The ECU150also performs a charging control and a discharging control on the battery130. In particular, in accordance with a DR request received from the server30through the communication device180, the ECU150performs the charging control and/or the discharging control on the battery130. The ECU150also collects various data, such as the state of charge (SOC) of the battery130, the location information of the vehicle50, and the remaining EV travel distance based on the SOC, and transmits the collected various data to the server30through the communication device180at a predetermined timing (at a time of system startup/shutdown, at a time of start/end of charging and discharging, or periodically). The controls performed by the ECU150will be described in detail below.

The communication device180includes a communication interface (I/F) for wireless communications with the server30. The ECU150can wirelessly communicate with the server30through the communication device180. The communication device180may include a data communication module (DCM) or 5G enabled communication I/F.

The portable terminal80corresponds to a terminal carried by a user of the vehicle50. The portable terminal80is configured to wirelessly communicate with the server30. The user of the vehicle50can output instructions from the portable terminal80to the server30so that, for example, the server30can obtain the various information (such as the SOC and the remaining travel distance) of the vehicle50. In the present embodiment, smartphone which includes a touch panel display is employed as the portable terminal80. However, the present disclosure is not limited thereto. Any portable terminal can be employed as the portable terminal80.

The power grid PG is a power network that is provided by an electric utility (for example, a power company). The power grid PG is electrically connected to multiple EVSEs, including the EVSE40, and supplies AC power to the EVSEs. The EVSE40includes a power supply circuit41, which converts electric power, supplied from the power grid PG, into one that is appropriate for external charging of the vehicle50. The power supply circuit41may include a sensor for detecting the charging power.

As the relay included in the charger-discharger120is closed, the battery130mounted on the vehicle50is electrically connected to the EVSE40. During the external charging, electric power is supplied from the power grid PG to the battery130via the power supply circuit41, the electric power cable42, the inlet110, and the charger-discharger120. During the external electric power supply, electric power is output from the battery130to the power grid PG via the charger-discharger120, the inlet110, the electric power cable42, and the power supply circuit41.

The server30includes a communication apparatus31, an acquisition unit32, a control unit33, and a storage unit34. The communication apparatus31includes a communication I/F for wireless communications with the communication device180included in the vehicle50. The communication apparatus31also includes a communication I/F for wireless communications with the portable terminal80.

The acquisition unit32obtains various information of the vehicle50through the communication apparatus31. The acquisition unit32obtains information, for example, the SOC of the battery130, the location information of the vehicle50, and the remaining travel distance, etc., and stores in the storage unit34the information associated with identification information (ID) for each vehicle. The acquisition unit32also obtains, from the vehicle50through the communication apparatus31, history information indicating that the vehicle50has carried out the demand and supply of electric power to the power grid PG, that is, history information indicating that the vehicle50has performed external charging or external electric power supply. The history information, for example, indicates start/end of the external charging or the external electric power supply, or that the connector43of the electric power cable42has been connected/disconnected to/from the inlet110. The details of the information obtained by the acquisition unit32and when the acquisition unit32obtains such information will be described in detail below.

The control unit33includes a processor (such as a CPU), a memory (a ROM and a RAM), an I/O buffer, etc. (none of which are shown). The processor deploys programs stored in the ROM into the RAM, etc., and executes the programs. Various processes performed by the control unit33are written in the programs stored in the ROM. The processes performed by the control unit33will be described below.

The storage unit34is configured to store various information. The information obtained by the acquisition unit32from the vehicle50is stored in the storage unit34, associated with the information (ID) for each vehicle. The storage unit34is configured of a hard disk drive (HDD) or a solid state drive (SSD), for example.

FIG.2is a detailed block diagram of the vehicle50shown inFIG.1. Referring toFIG.2, besides the inlet110, the charger-discharger120, the battery130, the ECU150, and the communication device180described with reference toFIG.1, the vehicle50further includes monitoring modules121,131, a travel drive unit160, and a navigation system (referred to as a “NAVI” below)170.

The monitoring module121includes various sensors for detecting conditions of the charger-discharger120, and outputs results of the detections to the ECU150. In the present embodiment, the monitoring module121is configured to detect voltage and current input to the charger-discharger120, and voltage and current output from the charger-discharger120.

The monitoring module131includes various sensors for detecting conditions of the battery130(for example, voltage, current, temperature, etc.), and outputs results of the detections to the ECU150. The monitoring module131may be a battery management system (BMS) that further has an SOC estimation function, a state of health (SOH) estimation function, a cell voltage equalization function, a diagnosis function, etc. for the battery130, in addition to the sensor functions above. Based on the outputs of the monitoring module131, the ECU150can obtain the conditions of the battery130.

The travel drive unit160includes a power control unit (PCU) and a motor generator (MG) (none of which are shown), and generates a travel driving force for the vehicle50, using the electric power stored in the battery130. The PCU includes, for example, an inverter and a converter (none of which are shown), and is controlled by the ECU150. The MG is a three-phase alternating-current (AC) motor generator, for example. The MG is driven by the PCU, and configured to rotate driving wheels W. The PCU drives the MG, using the electric power supplied from the battery130. The MG also regenerates electric power upon breaking of the vehicle, and supplies the generated electric power to the battery130.

The NAVI170includes a processor, a storage device, a touch panel display, and a global positioning system (GPS) module (none of which are shown). The storage device stores map information. For example, the touch panel display receives user input and displays a map and other information, etc. The GPS module is configured to receive a signal (referred to as a “GPS signal” below) from a GPS satellite. The NAVI170is capable of locating the position of the vehicle50, using the GPS signal. The NAVI170is configured to carry out a route search, based on the user input, to find a travel route (for example, a shortest route) from the current location of the vehicle50to a destination, and shows the travel route found through the route search on a map.

The ECU150includes a processor151, a RAM152, and a storage device153. The RAM152functions as a working memory temporality storing data processed by the processor151. The storage device153is configured to save the stored information. The storage device153includes, for example, a ROM and a rewritable nonvolatile memory. Besides programs, the storage device153stores information (maps, mathematical formulas, various parameters, etc.) which are used in the programs. Various controls at the ECU150are performed by the processor151executing the programs stored in the storage device153.

Specifically, the ECU150controls the travel drive unit160, thereby performing the traveling control on the vehicle50. The ECU150also controls the charger-discharger120, thereby performing the charging control and the discharging control on the battery130. The ECU150can perform the charging control and/or the discharging control, according to a DR request received from the server30through the communication device180.

The ECU150also calculates the SOC of the battery130from the voltage and current of the battery130which are obtained by the monitoring module131, and outputs the SOC to the storage device153. The ECU150also calculates a remaining travel distance for the vehicle50based on the SOC, and outputs the remaining travel distance to the storage device153. The ECU150also obtains the location information of the vehicle50from the NAVI170and outputs the location information to the storage device153.

The ECU150then reads the various information above from the storage device153at a predetermined timing, and transmits the various information to the server30through the communication device180. For example, the predetermined timing is at the time of an event, such as at a time of activation/deactivation of the vehicle system (such as at on/off of a start switch, etc.), the start/end of external charging, the start/end of external electric power supply, connection/disconnection between the connector43of the electric power cable42and the inlet110, or at a periodical timing.

Note that the various controls at the ECU150are not limited to be performed by software, and can be performed by dedicated hardware (electronic circuit).

FIGS.3and4are diagrams illustrating one example of information which is transmitted from the vehicle50to the server30.FIG.3shows one example of the information that is transmitted from the vehicle50to the server30at the activation/deactivation of the travel system. Referring toFIG.3, as a driver operates the start switch (not shown) and the travel system of the vehicle50is activated, the ECU150included in the vehicle50reads, from the storage device153, “travel start time” indicative of the time when the travel system of the vehicle50is activated, and information, such as “GPS location information,” “total travel distance,” and “SOC,” and transmits the “travel start time” and the information to the server30through the communication device180. Note that the GPS location information is information on the current location of the vehicle50obtained by the NAVI170. The total travel distance is a total distance traveled by the vehicle50up to the present time. The SOC is the current SOC of the battery130.

As the start switch is operated by the driver and the travel system of the vehicle50is deactivated, the ECU150reads from the storage device153a “travel end time” indicative of the time when the travel system of the vehicle50is deactivated, and information, such as the “GPS location information,” the “total travel distance,” the “SOC,” and transmits the “travel end time” and the information to the server30through the communication device180.

FIG.4shows one example of the information which is transmitted from the vehicle50to the server30at the time of an event irrelevant to the vehicle travel. Referring toFIG.4, “event type” indicates an event for which the information is transmitted to the server30, indicating that the event is external charging in this example. As the external charging starts, the ECU150reads from the storage device153the “event type,” and information, such as “time of occurrence” of the event, “GPS location information,” “SOC,” “available time period for external electric power supply,” a “remaining charging time,” “remaining EV travel distance,” and “charger-discharger state information,” and transmits the “event type,” and the information to the server30through the communication device180. Alternatively, the ECU150may collect the information above separately from the “event type.”

Note that the available time period for external electric power supply is a time remained during external electric power supply until the battery130becomes empty, and calculated based on the SOC and the magnitude of electric power supplied by the vehicle50. The remaining charging time is a time remained during external charging until the battery130is fully charged, and calculated based on the SOC and the magnitude of the charging power. The remaining EV travel distance is a distance that the vehicle50can travel with the electric power stored in the battery130, and calculated based on the SOC and the power consumption efficiency of the vehicle50(for example, a historic average value, etc.). The charger-discharger state information indicates a state of the charger-discharger120(activated/deactivated).

Referring, again, toFIG.1, the server30carries out DR to the vehicle50. Schematically, for example, if a server (not shown) of the power company managing the power grid PG requests the server30to adjust supply and demand, the server30determines the power capacity that the vehicle50can offer. Based on the capacity, the server30generates an implementation schedule for the vehicle50, and transmits a DR request to the vehicle50through the communication apparatus31.

As the vehicle50receives the DR request from the server30and is connected to the EVSE40, the vehicle50can charge the battery130(the external charging) with supply of electric power from the EVSE40(the power grid PG) or supply the EVSE40(the power grid PG) with the electric power stored in the battery130(the external electric power supply), according to the DR request. As the external charging or the external electric power supply is performed, the vehicle50transmits the information, shown inFIG.4, to the server30through the communication device180at the occurrence of a respective event (for example, at start/end of external charging).

At this time, if the wireless communication between the vehicle50and the server30is poor, the server30is unable to appropriately obtain from the vehicle50the information for use in the DR. As a result, appropriate adjustment of supply and demand of electric power may not be performed in response to the DR request. If appropriate adjustment of supply and demand of electric power is not performed in response to the DR request while the vehicle is participating in DR, the user of the vehicle50may suffer from drawbacks, such as being subjected to penalty.

Thus, in the present embodiment, if the wireless communication between the vehicle50participating in DR and the server30is determined to be poor, the priority of the vehicle50is lowered among power adjustment resources (referred to as “distributed energy resources (DERs)” below) participating in DR.

In other words, while DERs are requested for DR, the priority of each of DERs participating in DR is determined, considering response situations (a time when the DER is available, charging capability/electric power supply capability, etc.). In the present embodiment, despite the fact that the changes in SOC of the vehicle50are sensed, if the server30has not obtained the history information indicating that the vehicle50has performed external charging or external electric power supply from the vehicle50, the server30determines that the reliability of the communication with the vehicle50is degraded, and determines the priority of the vehicle50so that the vehicle50is less likely to be selected for a DR request.

This can avoid a situation in which, despite the fact that the vehicle50is participating in DR, no appropriate adjustment of supply and demand of electric power is performed in response to a DR request due to the degradation of the communication reliability. Accordingly, a customer (the user of the vehicle50) can be prevented from suffering from drawbacks (such as being subjected to penalty) caused by appropriate adjustment of supply and demand of electric power not being performed in response to a DR request.

In the present embodiment, for each vehicle participating in and registered in DR, the server30manages information (referred to as “DR information” below) for determining the priority of the vehicle for DR. Based on the DR information of each vehicle participating in DR, the server30determines the priority of the vehicle50for a DR request.

FIG.5is a diagram illustrating one example of the DR information managed for each vehicle by the server30. Referring toFIG.5, “UID” is identification information (ID) of the vehicle50, which is given to each vehicle when the vehicle is registered in participation in DR. “State of vehicle” indicates whether the vehicle50is available for a DR request by being connected to the EVSE40. The information is determined based on the activation/deactivation state of the travel system of the vehicle50and the location information, which are obtained from the vehicle50. The “state of vehicle” changes to available for DR when the travel system of the vehicle50is deactivated and the location information of the vehicle50indicates a location near the EVSE40(for example, home).

“SOC” is a most-recent SOC obtained from the vehicle50. The DR request includes an increase demand request (also referred to as a “posiwatt DR” below) requesting an increase in electric power demand from an electric power customer (the vehicle50), and a reduce demand request (also referred to as a “negawatt DR” below) requesting a reduction in electric power demand. Note that the negawatt DR is not limited to reduction in electric power demand, and also includes supply of electric power to the power grid PG. The lower the SOC of the vehicle50is, the highly available the vehicle50is for a posiwatt DR. The higher the SOC is, the highly available the vehicle50is for a negawatt DR. Thus, if a DR request is a posiwatt DR, the SOC being low raises the priority of the vehicle50for the DR request, and the SOC being high lowers the priority of the vehicle50for the DR request. In contrast, if a DR request is a negawatt DR, the SOC being low lowers the priority of the vehicle50for the DR request, and the SOC being high raises the priority of the vehicle50for the DR request.

“Communication reliability” indicates reliability of wireless communication between the vehicle50and the server30. As mentioned above, as the reliability of communication between the vehicle50and the server30is degraded, the vehicle50may not perform appropriate adjustment of supply and demand of electric power in response to a DR request. Therefore, the degradation of the communication reliability lowers the priority of the vehicle50for a DR request. In the present embodiment, the reliability of the communication with the vehicle50is determined to be poor if, although the server30has sensed changes in SOC of the vehicle50, the server30has not obtained the history information indicating that the vehicle50has performed external charging or external electric power supply from the vehicle50.

FIG.6is a diagram illustrating one example of priority information for a DR request. Referring toFIG.6, the priority information is managed by the server30, and indicates a priority of each user participating in DR. “UID-***” indicates a user ID of a user (a customer) corresponding to the priority. The priority information is updated based on the DR information for each vehicle shown inFIG.5.

FIGS.7and8are diagrams each illustrating one example method of determination of the priority of the vehicle50for a DR request. Referring toFIGS.5and7, X11 to X13 are indices respectively indicating degrees of “state of vehicle,” “SOC,” and “communication reliability” shown inFIG.5.

For example, the longer the time period for which the vehicle50is available for DR relative to a time period the DR request, a point farther away from the center X0 (outer side), the “state of vehicle” indicated by X11 is plotted to. This example shows that the vehicle50is available for DR for an entire period of time for which a DR request is made.

When the DR request is a posiwatt DR, the lower the SOC is, the outer side of the chart the “SOC” indicated by X12 is plotted to. When the DR request is a negawatt DR, the higher the SOC is, the outer side of the chart the “SOC” indicated by X12 is plotted to. The higher the reliability of the communication between the server30and the vehicle50is determined to be, the outer side of the chart the “communication reliability” indicated by X13 is plotted to. Stated differently, the “communication reliability” indicated by X13 is plotted to the inner side of the chart if the reliability of communication between the server30and the vehicle50is determined to be low.

Then, in this example, based on the area of the hatched region defined by the plots of X11 to X13, the priority of the vehicle50is determined. In other words, as compared to other vehicles, the greater the area of the hatched region, the higher the priority the vehicle50has, while the smaller the area of the hatched region, the lower the priority the vehicle50has.

FIG.8is a diagram illustrating a situation in which the reliability of the communication between the server30and the vehicle50is degraded. Referring toFIG.8, in this example, since the reliability of the communication between the server30and the vehicle50is degraded, “communication reliability” indicated by X13 is plotted to the inner side of the chart, as compared to the example ofFIG.7. Therefore, the area of the hatched region defined by the plots of X11 to X13 is smaller than the example ofFIG.7. In other words, the chart illustrated inFIG.8indicates that the vehicle50has a lower priority than the example shown inFIG.7.

The respective indices of X11 to X13 may be weighed. For example, the indices may be weighed so that the degradation of the communication reliability has a greater contribution to lowering the priority than the condition of the SOC has. The parameters determining the priority of the vehicle50for a DR request are not limited to X11 to X13, and other parameters may be included.

FIGS.9and10are flowcharts each illustrating one example procedure of a process of updating the priority of the vehicle50for a DR request. The flowchart ofFIG.9shows a procedure when a posiwatt DR is requested. The flowchart ofFIG.10shows a procedure when a negawatt DR is requested. The series of process steps illustrated in these flowcharts are performed by the server30, and is started once the server30obtains the various information (FIG.3) on the vehicle50from the vehicle50upon the deactivation of the travel system of the vehicle50.

Referring toFIG.9, as the travel system of the vehicle50is deactivated, the server30obtains the information on the SOC (will be referred to as S1) of the battery130from the information (FIG.3) transmitted from the vehicle50(step S10).

Subsequently, the server30determines whether the server30has received external charging start event and end event from the vehicle50(step S20). Specifically, the server30determines whether the server30has received the information (FIG.4) indicating that the event type is start and end of external charging from the vehicle50, after the travel system is deactivated. Upon receiving the external charging start event and end event (YES in step S20), the server30passes the process to END, without performing the subsequent process steps.

While the server30has not received at least one of the external charging start event and end event from the vehicle50(NO in step S20), the server30determines whether the travel system of the vehicle50is activated (step S30). Specifically, the server30determines whether the server30has received the various information (FIG.3) of the vehicle50from the vehicle50upon deactivation of the travel system. If the server30has not yet received the information and the travel system is being deactivated (NO in step S30), the process returns to step S20.

If the travel system of the vehicle50is determined to be activated in step S30(YES in step S30), the server30obtains the information on the SOC (will be referred to as S2) of the battery130from the information (FIG.3) transmitted from the vehicle50(step S40).

Subsequently, the server30calculates a difference ΔSOC (=S2−S1) between the SOC (S2) obtained in step S40and the SOC (S2) obtained in step S10, and determines whether ΔSOC is greater than a threshold Sth1(step S50). It should be noted that, since an average amount of increase in SOC during external charging is considered as being sufficiently greater than an amount of increase in SOC while the vehicle is traveling (in general, the SOC decreases while the vehicle is traveling), the threshold Sth1is appropriately set to a value that allows the SOCs in the above two cases to be distinguishable.

Then, if ΔSOC is determined to be greater than the threshold Sth in step S50(YES in step S50), the server30updates, by lowering, the priority of the vehicle50for the DR request (posiwatt DR) (step S60). Specifically, if the server30has not received at least one of the external charging start event and end event from the vehicle50(NO in step S20) although ΔSOC is greater than the threshold Sth1(YES in step S50), such a situation is determined as the reliability of communication being degraded between the server30and the vehicle50. Then, the server30updates, by lowering, the priority of the vehicle50for the DR request (posiwatt DR), based on the area of the hatched region defined by the plots of X11 to X13, as described with respect toFIGS.7and8.

While, in the above description, the case where the server30has not received at least one of the external charging start event and end event from the vehicle50is the condition under which the priority of the vehicle50is lowered, it should be noted that the condition may be that the server30has not received both the external charging start event and end event from the vehicle50.

The weight on the communication reliability in determination of the priority may be changed, depending on whether the server30has not received both the external charging start event and end event or one of both events.

Referring toFIG.10, a procedure when a negawatt DR is requested is now described. The process steps S210, S230, S240, and S260in the flowchart illustrated inFIG.10are the same as the process steps S10, S30, S40, and S60, respectively, illustrated inFIG.9.

In the flowchart, if obtained the information on the SOC (S1) of the battery130in step S210, the server30determines whether the server30has received external electric power supply start event and end event from the vehicle50(step S220). Specifically, after the travel system is deactivated, the server30determines whether the server30has received from the vehicle50the information (FIG.4) indicating that the event type is start and end of the external electric power supply. Then, if the server30receives the external electric power supply start event and end event (YES in step S220), the server30passes the process to END, without performing the subsequent process steps.

As long as the server30has not received at least one of the external electric power supply start event and end event from the vehicle50(NO in step S220), the server30passes the process to step S230.

If obtained the information on the SOC (S2) of the battery130in step S240, the server30calculates a difference ΔSOC (=S1−S2) between the SOC (S1) obtained in step S210and the SOC (S2) obtained in step S240, and determines whether ΔSOC is greater than a threshold Sth2(step S250).

Then, if ΔSOC is determined to be greater than the threshold Sth2in step S250(YES in step S250), the process is passed to step S260in which the priority of the vehicle50for the DR request (negawatt DR) is updated by being lowered. Specifically, if the server30has not received at least one of the external electric power supply start event and end event from the vehicle50(NO in step S220) although ΔSOC is greater than the threshold Sth2(YES in step S250), such a situation is determined as the reliability of communication being degraded between the server30and the vehicle50. Then, the server30updates, by lowering, the priority of the vehicle50for the DR request (negawatt DR), based on the area of the hatched region defined by the plots of X11 to X13, as described with respect toFIGS.7and8.

It should be noted that, since an average amount of decrease in SOC during external electric power supply is considered as being greater than an amount of decrease in SOC while the vehicle is traveling (because electric power is discharged and charged while the vehicle is traveling), the threshold Sth2is appropriately set to a value that allows average amounts of change in the SOCs in the above two cases to be distinguishable, for example.

While, in the example ofFIG.10, the case where the server30has not received at least one of the external electric power supply start event and end event from the vehicle50is the condition under which the priority of the vehicle50is lowered, it should be noted that the condition may be that the server30has not received both the external electric power supply start event and end event from the vehicle50.

The weight that is applied to the communication reliability when determining the priority may be changed, depending on whether the server30has not received both the external electric power supply start event and end event or one of both events.

As described above, in the present embodiment, if the server30has not obtained, even though the SOC of the battery130of the vehicle50has changed, the history information indicating that the vehicle50has performed external charging or external electric power supply, the reliability of wireless communications between the server30and the vehicle50is considered as being degraded, and the priority of the vehicle50is determined so that the vehicle50is less likely to be selected for a DR request. This can avoid a situation in which, despite the fact that the vehicle50is participating in DR, no appropriate adjustment of supply and demand of electric power is performed in response to a DR request due to the degradation of the communication reliability. Therefore, according to the present embodiment, a customer (the user of the vehicle50) can be prevented from suffering from drawbacks (such as being subjected to penalty) caused by appropriate adjustment of supply and demand of electric power not being performed in response to a DR request.

The embodiment above has been described with reference to using the information indicating the start/end of external charging or external electric power supply as the history information indicating that the vehicle50has performed demand and supply of electric power for the power grid PG, that is, the history information indicating that the vehicle50has performed the external charging or the external electric power supply. Information indicating connection/disconnection between the connector43of the electric power cable42and the inlet110may instead be used as the history information above.

FIG.11is a flowchart illustrating one example procedure of a process of updating the priority of the vehicle50for a DR request, according to Variation 1. The flowchart corresponds to the flowcharts illustrated inFIGS.9and10.

Referring toFIG.11, the process steps S310, S330, S340, and S360illustrated in the flowchart are the same as the process steps S10, S30, S40, S60, respectively, illustrated inFIG.9.

In the flowchart, if obtained the information on the SOC (S1) of the battery130in step S310, the server30determines whether the server30has received from the vehicle50a connect event and a disconnect event between the connector43of the electric power cable42and the inlet110(step S320). Specifically, after the travel system is deactivated, the server30determines whether the server30has received from the vehicle50the information (FIG.4) indicating that the event type is connection and disconnection between the connector43and the inlet110. Then, upon receiving a connect event and a disconnect event between the connector43and the inlet110(YES in step S320), the server30passes the process to END, without performing the subsequent process steps.

If the server30has not received at least one of a connect event and a disconnect event between the connector43and the inlet110from the vehicle50(NO in step S320), the server30passes the process to step S330.

If obtained the information on the SOC (S2) of the battery130in step S340, the server30calculates a difference |ΔSOC| between the SOC (S1) obtained in step310and the SOC (S2) obtained in step S340, and determines whether |ΔSOC| is greater than a threshold Sth (step S350).

Then, if |ΔSOC| is determined to be greater than the threshold Sth in step S350(YES in step S350), the process is passed to step S360in which the priority of the vehicle50for the DR request is updated by being lowered. Specifically, if the server30has not received at least one of a connect event and a disconnect event between the connector43and the inlet110from the vehicle50(NO in step S320) although |ΔSOC| is greater than the threshold Sth (YES in step S350), such a situation is determined as the reliability of communication being degraded between the server30and the vehicle50. Then, the server30updates, by lowering, the priority of the vehicle50for the DR request, based on the area of the hatched region defined by the plots of X11 to X13, as described with respect toFIGS.7and8.

As described above, Variation 1 yields the same advantages effects as the embodiment above.

While the embodiment above and Variation 1 have been described with reference to using a change in SOC (ΔSOC) since the travel system is deactivated until the travel system is next activated in order to determine the reliability of communication between the server30and the vehicle50, a change in SOC when the location of the vehicle50remains unchanged may instead be used.

FIG.12is a flowchart illustrating one example procedure of a process of updating the priority of the vehicle50for the DR request, according to Variation 2. The flowchart illustrates a procedure when a posiwatt DR is requested. The series of process steps illustrated in the flowchart is repeated at prescribed cycles.

Referring toFIG.12, the server30obtains the information on the vehicle50(the location information, the SOC of the battery130, etc.) from the information (FIG.4) that is periodically transmitted from the vehicle50(step S410). The server30then determines whether the location information on the vehicle50, obtained in step S410, has changed from the previous values (step S420). If the location of the vehicle has changed (YES in step S420), the process is passed to RETURN, without the subsequent series of process steps being performed.

If the location of the vehicle remains unchanged (NO in step S420), the server30determines whether the server30has received external charging start event and end event from the vehicle50(step S430). If the server30has received the external charging start event and end event (YES in step S430), the server30passes the process to RETURN, without performing the subsequent process steps.

If the server30has not received at least one of the external charging start event and end event from the vehicle50(NO in step S430), the server30calculates a difference ΔSOC (=S2−S1) between the current value (will be referred to as S2), obtained in step S410, and the previous value (will be referred to as S1) of the SOC, and determines whether ΔSOC is greater than a threshold Sth1(step S440).

Then, if the ΔSOC is determined to be greater than the threshold Sth1in step S440(YES in step S440), the server30updates, by lowering, the priority of the vehicle50for the DR request (posiwatt DR) (step S450). Specifically, if the server30has not received at least one of the external charging start event and end event from the vehicle50(NO in step S430) although the SOC has changed (ΔSOC>Sth1) (YES in step S440) while the vehicle50is being parked (the location information remains unchanged), such a situation is determined as the reliability of communication being degraded between the server30and the vehicle50. Then, the server30updates, by lowering, the priority of the vehicle50for the DR request (posiwatt DR), based on the area of the hatched region defined by the plots of X11 to X13, as described with respect toFIGS.7and8.

Note that, although not shown particularly, for a procedure when a negawatt DR is requested, the priority of the vehicle50for the DR request (negawatt DR) is updated by determining whether the server30has received external electric power supply start/end events in step S430, and determining whether ΔSOC=S1(previous value)−S2(current value) is greater than the threshold Sth1in step S440.

As described above, Variation 2 also yields the same advantages effects as the embodiment above.

Similarly to Variation 1 of the present embodiment, in Variation 2, information indicating connection/disconnection between the connector43of the electric power cable42and the inlet110may be used as the history information indicating that the vehicle has performed external charging or external electric power supply.

FIG.13is a flowchart illustrating one example procedure of a process of updating the priority of the vehicle50for a DR request, according to Variation 3. The flowchart corresponds to the flowchart illustrated inFIG.12.

Referring toFIG.13, the process steps S510, S520, and S550illustrated in the flowchart are the same as the process steps S410, S420, and S450, respectively, illustrated inFIG.12.

In the flowchart, if the location of the vehicle remains unchanged (NO in step S520), the server30determines whether the server30has received from the vehicle50a connect event and a disconnect event between the connector43of the electric power cable42and the inlet110(step S530). Specifically, the server30determines whether the server30has received from the vehicle50the information (FIG.4) indicating that the event type is connection and disconnection between the connector43and the inlet110. Then, upon receiving a connect event and a disconnect event between the connector43and the inlet110(YES in step S530), the server30passes the process to RETURN, without performing the subsequent process steps.

If the server30has not received at least one of a connect event and a disconnect event between the connector43and the inlet110from the vehicle50(NO in step S530), the server30calculates a difference |ΔSOC| between the current value of the SOC obtained in step S510and the previous value, and determines whether |ΔSOC| is greater than a threshold Sth (step S540).

Then, if |ΔSOC| is determined to be greater than the threshold Sth in step S540(YES in step S540), the process is passed to step S550, and the priority of the vehicle50for the DR request is updated by being lowered.

As described above, Variation 3 also yields the same advantages effects as the embodiment above.

While Variations 2 and 3 have been described, with reference to using changes in SOC (ΔSOC) when the location of the vehicle remains unchanged in order to determine the reliability of communication between the server30and the vehicle50, a change in travel distance of the vehicle50may instead be used.

FIG.14is a flowchart illustrating one example procedure of a process of updating the priority of the vehicle50for a DR request, according to Variation 4. The flowchart illustrates a procedure when a posiwatt DR is requested. The flowchart corresponds to the flowchart illustrated inFIG.12.

Referring toFIG.14, the process steps S610, S630to S650illustrated in the flowchart are the same as the process steps S410, S430to S450, respectively, illustrated inFIG.12.

In the flowchart, as the server30, in step S610, obtains the information on the vehicle50(including the location information, the SOC, the travel distance, etc.) from the information (FIG.4) that is periodically transmitted from the vehicle50, the server30determines whether the travel distance of the vehicle50has changed from the previous value (step S620). If the travel distance has changed (YES in step S620), the process is passed to RETURN, without the subsequent series of process steps being performed.

If the travel distance remains unchanged (NO in step S620), the server30passes the process to step S630in which the server30determines whether the server30has received external charging start event and end event from the vehicle50. The subsequent process steps are the same as those illustrated inFIG.12.

Note that, although not shown particularly, for a procedure when a negawatt DR is requested, the priority of the vehicle50for the DR request (negawatt DR) is updated by determining whether the server30has received external electric power supply start/end events in step S630, and determining whether ΔSOC=S1(previous value)−S2(current value) is greater than the threshold Sth1in step S640. In step S630, the server30may determine whether the server30has received connect/disconnect events between the connector43of the electric power cable42and the inlet110, instead of determining whether the server30has received the external charging start/end events.

As described above, Variation 4 also yields the same advantages effects as the embodiment above.

The presently disclosed embodiment and the variations thereof should be considered in all aspects as illustrative and not restrictive. The technical scope of the present disclosure is indicated by the appended claims, rather than by the embodiments above, and all changes that come within the scope of the claims and the meaning and range of equivalency of the claims are intended to be embraced within their scope.