Method for controlling charging and discharging of charging and discharging elements, and device for controlling charging and discharging of charging and discharging elements

Abstract

To keep a charge-discharge element that is charging and a charge-discharge element that is discharging from being present together in a power system.SOLUTION: A charging-discharging control method for charge-discharge elements includes: receiving a surplus amount (ΔPall fmax) of maximum power amount of charge and discharge by a plurality of charge-discharge elements (EV1, EV2, EV3 ...) connected to an electric wire (12) of a power system (10) and a surplus amount (ΔPall freq) of a frequency adjustment capacity corresponding to a system frequency of the power system; determining output characteristics corresponding to a level of priority (β) of charge and discharge relative to a system frequency (f) of which a value of the system frequency (f) that defines a boundary between charging and discharging remains the same regardless of the level of priority (β), on the basis of the level of priority and two received surplus amounts (ΔPall fmax), (ΔPall freq), where the level of priority (β)represents the degree to which charging or discharging of a charge-discharge element itself (EV1) is given higher priority than the other charge-discharge elements (EV2, EV3, ...); and charging or discharging at an output calculated on the basis of the determined output characteristics.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a method for controlling charging and discharging of a charging and discharging element, and a device for controlling charging and discharging of a charging and discharging element. [Background technology]

[0002] Patent Document 1 describes a technology for a power system frequency stabilization system. In this technology, the power system measures the system frequency and calculates the frequency adjustment capacity of the power system based on the deviation between the measured system frequency and a reference frequency. Furthermore, information according to the calculated frequency adjustment capacity is simultaneously transmitted from the power system to multiple power receiving amount control loads connected to the power system. Each power receiving amount control load measures its own system frequency and controls the amount of power received by each power receiving amount control load based on the measured system frequency, the information received from the power system, and the reference frequency.

[0003] In the technology of Patent Document 1, information simultaneously transmitted from the power grid to the power receiving amount control loads is determined based on the frequency response characteristics of the power receiving amount control loads. The frequency response characteristics of the power receiving amount control loads are response characteristics of the power receiving amount of the power receiving amount control loads to fluctuations in the system frequency.

[0004] Patent Document 1 also describes that the frequency response characteristics of the power receiving amount control load may be shifted in parallel so that the charge power at the reference frequency decreases during the time period when the power demand reaches its peak. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5598896 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, an electric vehicle is given as an example of an optimal load for controlling the amount of power received. In an electric vehicle, the charge / discharge output characteristics of the battery may be set according to the vehicle's own priority. The vehicle's own priority indicates the degree to which charging / discharging of the vehicle's own battery is given priority over charging / discharging of the batteries of other electric vehicles connected to the same power grid.

[0007] As described in the technology of Patent Document 1, regarding the parallel shift of frequency response characteristics, a method is adopted in which a base capacity according to the power consumption of the load on the power system is set according to the power demand, in addition to the frequency adjustment capacity which is set according to fluctuations in the system frequency.

[0008] If the base power is set separately from the frequency adjustment capacity, when an electric vehicle is used as a load for controlling the amount of received power, the power consumption of the electric vehicle fluctuates according to the priority. When the power consumption of the electric vehicle fluctuates, the base capacity fluctuates, and the boundary frequency between the charging output region and the discharging output region in the frequency response characteristics fluctuates. If the boundary frequency fluctuates according to the priority of the electric vehicle, for example, when multiple electric vehicles with different priorities are connected to a power system, electric vehicles that charge their batteries and electric vehicles that discharge their batteries will coexist on the power system. This coexistence is a factor that reduces the charging and discharging efficiency of the battery.

[0009] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to prevent charging and discharging elements from being mixed together in a power system. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, in a method for controlling charging and discharging of charging and discharging elements according to one embodiment of the present invention, a plurality of charging and discharging elements connected to an electric power line of a power system receive a maximum power margin for charging and discharging by the plurality of charging and discharging elements and a margin of a frequency adjustment capacity according to the system frequency of the power system. Based on a priority indicating a degree to which its own charging or discharging is prioritized over other charging and discharging elements and the two received margins, output characteristics are determined according to the priority of charging and discharging with respect to the system frequency, in which the value of the system frequency that is the boundary between charging and discharging is the same regardless of the priority, and charging or discharging is performed with an output calculated based on the output characteristics. Effect of the Invention

[0011] According to the present invention, it is possible to prevent a mixture of charging and discharging elements that charge and discharging elements that discharge on a power system. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing the configuration of a power system including a charge / discharge element to which a charge / discharge control method according to an embodiment of the present invention is applied. [Diagram 2] FIG. 2 is a block diagram showing the configuration of the charge / discharge control device for the electric vehicle shown in FIG. 1 and its peripheral devices. [Diagram 3] FIG. 3 is a graph showing charge / discharge output characteristics according to the priority of the electric vehicle determined by the characteristic determination unit in FIG. [Figure 4] FIG. 4 is a graph showing the charge / discharge output characteristics according to the priority of electric vehicles according to a comparative example, in which a frequency range occurs in which charging electric vehicles and discharging electric vehicles coexist. [Diagram 5] FIG. 5 is a flowchart showing the process steps executed by the charge / discharge control device of FIG. 1 in chronological order. [Figure 6] FIG. 6 is a graph showing that in the charge / discharge output characteristics according to the priority of an electric vehicle determined by the characteristic determination unit in FIG. 2, the higher the priority, the larger the discharge output in the discharge region. [Figure 7]FIG. 7 is a graph showing the charging output characteristics corrected by the characteristic correction unit of FIG. [Figure 8] FIG. 8 is a graph showing the charge / discharge output characteristics according to the priority of an electric vehicle in a comparative example, in which the output characteristics in which the charge output exceeds the maximum charge energy amount are shifted so that the charge output falls below the maximum charge energy amount. [Figure 9] FIG. 9 is a graph showing the charge / discharge output characteristics according to the priority of an electric vehicle, in which the output characteristics in which the charge output exceeds the maximum charge energy amount are determined by the characteristic determination unit in FIG. 2 so that the charge output falls below the maximum charge energy amount and the boundary between the charge region and the discharge region of the output characteristics is the same as that of the output characteristics of other priorities. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The following describes an embodiment and its modified examples, as well as specific examples to which the embodiment or its modified examples are applied, with reference to the drawings. In the description of the drawings, the same parts are given the same reference numerals, and the description thereof will be omitted.

[0014] (power system) With reference to FIG. 1, the configuration of an electric vehicle, each of which is equipped with a charge / discharge control device according to an embodiment, and a power system to which the electric vehicle is connected will be described.

[0015] The electric vehicles EV1 to EV3 (an example of a charge / discharge element) each include a charge / discharge control device according to an embodiment, and are electrically connected to a power grid 11 via a common electric wire 12. Other power consumption elements are also connected to the electric wire 12. The other power consumption elements and the electric vehicles EV1 to EV3 are elements that make up a load group to which power is supplied from the power system 10.

[0016] The electric vehicles EV1 to EV3 can receive (charge) power from a power grid 11 and transmit (discharge) power to the power grid 11 via electric wires 12. Each of the charge / discharge control devices autonomously controls the power (charge / discharge power) charged and discharged by the electric vehicle EV1 to EV3 in which it is mounted. The number of electric vehicles (EVs) connected to electric wires 12 and autonomously controlling the charge / discharge power is not limited to three as shown in FIG. 1.

[0017] The electric wire 12 is connected to the power grid 11 via a current measuring device 15 and a transformer 14. The electric vehicles EV1 to EV3 receive power from the current measuring device 15 side and transmit the power toward the current measuring device 15 side. An example of the transformer 14 is a pole transformer that changes the voltage applied to a high-voltage distribution line to a voltage used in homes, offices, etc.

[0018] The current measuring device 15 measures the current flowing through the electric wire 12, and calculates a current value (Pall_now) of the total charging / discharging power being charged or discharged by all of the electric vehicles EV1-EV3 via the electric wire 12, based on the measured current and the voltage of the electric wire 12. The current measuring device 15 also measures the system frequency (f) of the power system 10, based on the measured current. The system frequency (f) is the frequency of the current flowing through the electric wire 12.

[0019] The power system 10 is a power system that can control and optimize the flow of power from both the supply side and the demand side. The power system 10 is a concept that includes a smart grid, a smart community, and a microgrid or a MEMS (Mansion Energy Management System) that manages the energy supply source to the end consumption part through a communication network in a limited area such as an office or a factory. The power system 10 includes a power network 11, electric wires 12, a transformer 14, and a current measuring device 15 shown in FIG. 1. The power network 11 includes various power plants such as thermal, nuclear, and hydroelectric power plants, and substations that transform voltages from hundreds of thousands of volts (V) to several thousand volts.

[0020] In the embodiment, the power system 10 further includes an information transmission device 16. The information transmission device 16 is a computer or a server that controls and optimizes the flow of power from both the supply side and the demand side, and is connected to the current measurement device 15 via a computer network. Alternatively, various types of power information may be obtained from the current measurement device 15 via the power grid 11.

[0021] The information transmission device 16 has a calculation unit 17 that generates a signal requesting charging or discharging to all of the electric vehicles EV1 to EV3 based on various power information supplied from the power system 10, and a broadcast transmission unit 18a and a broadcast transmission device 18b that broadcast the signal generated by the calculation unit 17 to the electric vehicles EV1 to EV3.

[0022] The signal generated by the calculation unit 17 includes a request for charging or discharging all of the electric vehicles EV1 to EV3, that is, a “grid request.” The grid request is, for example, a differential power (ΔPall fmax) at the maximum frequency (fmax) of the power grid 10, which will be described later.

[0023] The maximum value of the total charging / discharging power (Pall_max) is the maximum amount of power that the electric vehicles EV1-EV3 as a whole can charge or discharge via the electric wires 12. The maximum value of the total charging / discharging power (Pall_max) is determined in advance. The current value of the total charging / discharging power (Pall_now) is the current value of the amount of power being charged or discharged by the electric vehicles EV1-EV3 as a whole via the electric wires 12. The charging / discharging control device according to the embodiment controls the charging / discharging output of the electric vehicles EV1-EV3 based on the constraint of the maximum value of the total charging / discharging power (Pall_max) so that the current value of the total charging / discharging power (Pall_now) does not exceed the maximum power (Pall_max).

[0024] The information transmitting device 16 receives the system frequency (f) of the power system 10 and the current value (Pall_now) of the total charge / discharge power measured by the current measuring device 15 via the computer network or the power grid 11. The information transmitting device 16 includes a storage device that stores data indicating basic output characteristics of the total charge / discharge power (Pall) relative to the system frequency (f) of the power system 10 and data indicating the maximum value of the total charge / discharge power (Pall_max).

[0025] The calculation unit 17 calculates the output characteristics of the total charge / discharge output with respect to the system frequency (f) of the power system 10, from the system frequency (f) measured by the current measurement device 15 and the calculated current value (Pall_now) of the total charge / discharge power. Furthermore, the calculation unit 17 calculates an estimate of the total charge / discharge power (Pall_fmax) of all the electric vehicles EV1 to EV3 at the maximum frequency (fmax) in the adjustment range of the system frequency (f), from the calculated output characteristics and the system frequency (f) measured by the current measurement device 15. The adjustment range of the system frequency (f) can be ±0.2 Hz when the reference frequency (fref) of the power system 10 is 50 Hz.

[0026] As shown in formula (1), calculation unit 17 calculates the differential power (ΔPall fmax) at the maximum frequency (fmax) by subtracting the estimated value of the total charging / discharging power at the maximum frequency (fmax) from the maximum value of the total charging / discharging power (Pall_max). In a situation where power system 10 is requesting charging of electric vehicles EV1-EV3, calculation unit 17 calculates the differential power of charging at the maximum frequency (fmax). The differential power of charging at the maximum frequency (fmax) is calculated by subtracting the estimated value of the total charging power transmitted to all of electric vehicles EV1-EV3 via electric wire 12 at the maximum frequency (fmax) from the maximum value of the total charging power that electric wire 12 can transmit to all of electric vehicles EV1-EV3.

[0027] On the other hand, in a situation where the power system 10 is requesting the electric vehicles EV1-EV3 to discharge, the calculation unit 17 calculates the discharge differential power at the maximum frequency (fmax). The discharge differential power at the maximum frequency (fmax) is calculated by subtracting an estimated value of the total charging power received from all of the electric vehicles EV1-EV3 via the electric wire 12 at the maximum frequency (fmax) from the maximum value of the total discharging power that the electric wire 12 can receive from all of the electric vehicles EV1-EV3. The differential power (ΔPall fmax) at the maximum frequency (fmax) is a positive value equal to or greater than 0, and is a concept that includes the charging differential power and the discharging differential power at the maximum frequency (fmax).

[0028] The situation in which the power system 10 requests the electric vehicles EV1 to EV3 to charge or discharge changes depending on the balance of power supply and demand in the power system 10. The information transmission device 16 uses data indicating the maximum value (Pall_max) of the total charging and discharging power read from the storage device and the differential power (ΔPall fmax) at the maximum frequency (fmax) calculated by the calculation unit 17 to calculate the differential power (ΔPall fmax) at the maximum frequency (fmax) as a value indicating the margin of the maximum amount of charging and discharging power. As a method for calculating the differential power (ΔPall fmax) at the maximum frequency (fmax), a method disclosed in International Publication No. 2020 / 194010 for calculating the differential power (ΔP) by subtracting the current value (Pall_now) of the total charging and discharging power from the maximum value (Pall_max) of the total charging and discharging power can be applied.

[0029]

number

[0030] Furthermore, the calculation unit 17 calculates the difference (ΔPall freq) in the frequency regulation capacity as a value indicating the margin of the frequency regulation capacity. The difference (ΔPall freq) in the frequency regulation capacity is a difference obtained by subtracting the actual value of the frequency regulation capacity (Pall freq) actually obtained between the minimum frequency and the maximum frequency (fmax) in the adjustment range of the system frequency (f) according to the output characteristics calculated by the calculation unit 17 from the theoretical value of the frequency regulation capacity (Pall freq) obtained between the minimum frequency and the maximum frequency (fmax) in the adjustment range of the system frequency (f) according to the basic output characteristics read from the storage device.

[0031] The broadcast transmission unit 18a uses the broadcast transmission device 18b to broadcast, to all the electric vehicles EV1 to EV3, an electric signal indicating the power difference (ΔPall fmax) at the maximum frequency (fmax) and the frequency adjustment capacity difference (ΔPall freq) calculated by the calculation unit 17. The power difference (ΔPall fmax) at the maximum frequency (fmax) and the frequency adjustment capacity difference (ΔPall freq) indicated by the electric signal broadcast by the broadcast transmission unit 18a are updated every time the information transmission device 16 repeats a processing cycle.

[0032] As a method of broadcast transmission, a wireless LAN (Local Area Network) such as Wi-Fi (registered trademark) or Bluetooth (registered trademark) can be used.

[0033] In the embodiment, the "electric vehicles EV1 to EV3" are an example of a "charging / discharging element" that charges and discharges electric power via the electric wire 12. The charging / discharging element stores the received electric power in a battery (including a secondary battery, a storage battery, and a rechargeable battery). The "charging / discharging element" includes all devices and equipment that are equipped with a battery, such as vehicles (including electric vehicles, hybrid vehicles, construction machinery, and agricultural machinery), railroad cars, playground equipment, tools, household products, and daily necessities. In the embodiment, an example of the charging / discharging element is an electric vehicle (EV) that uses electricity as an energy source and runs using a motor as a power source. However, it is not intended that the charging / discharging element in the present invention be limited to an electric vehicle (EV).

[0034] "Charge / discharge element" indicates a unit configuration of charge / discharge control by the charge / discharge control device according to the embodiment. That is, the charge / discharge control according to the embodiment is performed with the charge / discharge element as a unit. For example, the charge / discharge control is performed in parallel on each of the multiple electric vehicles EV1 to EV3 independently of each other.

[0035] (Electric Vehicles) 2, the configuration of the charge / discharge control device 23 and its peripheral devices mounted on each of the electric vehicles EV1-EV3, ... connected to the electric wire 12 will be described. Note that, hereinafter, of the electric vehicles EV1-EV3, ..., the electric vehicle EV1 will be described as an example, but the other electric vehicles EV2, EV3, ... have a similar configuration and can operate in the same way.

[0036] The electric vehicle EV1 is equipped with a receiving device 21 (receiving unit), a vehicle state acquisition device 22, a charging / discharging device 24, a motor 26, and a battery 25 as peripheral devices of a charging / discharging control device 23.

[0037] The receiving device 21 is a device that receives an electric signal (wireless signal) broadcast from the broadcast transmitting device 18b. The electric signal received by the receiving device 21 includes a signal requesting charging or discharging of all of the electric vehicles EV1 to EV3. This signal includes, as an example of a system request, a signal indicating a required value (Pfr) of the frequency regulation capacity of the power system 10, and a signal indicating an excess or shortage capacity (ΔPfr) of the frequency regulation capacity.

[0038] The vehicle state acquisition device 22 acquires information representing the state of the electric vehicle EV1. For example, the "state of the electric vehicle EV1" includes the current value (SOCnow) of the state of charge of the battery 25 equipped in the electric vehicle EV1, and a numerical value representing a request from the user of the electric vehicle EV1. The numerical value representing the request from the user of the electric vehicle EV1 is, for example, a target value (SOCgoal) of the state of charge of the battery 25, and the time to end charging and discharging of the electric vehicle EV1 (end time Td of charging and discharging). The remaining time (T) until the end time Td is the remaining time in which the electric vehicle EV1 can perform charging and discharging.

[0039] The charging / discharging device 24 is an on-board charger (OBC) and charges / discharges the battery 25 via the electric wire 12 under the control of the charging / discharging control device 23. The charging / discharging device 24 stores the received electric power in the battery 25. Alternatively, the charging / discharging device 24 may transmit the received electric power directly to the motor 26 serving as a drive source without storing the electric power in the battery 25. On the other hand, the charging / discharging device 24 discharges the electric power stored in the battery 25 or the electric power generated by the motor 26 to the power grid 11 via the electric wire 12.

[0040] The charging / discharging device 24 includes an ammeter 24a. The ammeter 24a measures the current flowing through the electric wire 12 at a position on the electric wire 12 to which the electric vehicle EV1 is connected. The position on the electric wire 12 to which the electric vehicle EV1 is connected is called the "receiving end" of the electric vehicle EV1. The charging / discharging device 24 can measure the system frequency (f) of the power system 10 at the receiving end of the electric vehicle EV1.

[0041] The battery 25 includes a secondary battery, a storage battery, or a rechargeable battery that stores the power received by the charge / discharge device 24. The motor 26 is a drive source of the electric vehicle EV1 that runs on the electric energy or power stored in the battery 25.

[0042] The charge / discharge control device 23 can be realized by using a microcomputer having a CPU (Central Processing Unit), a memory, and an input / output unit. A computer program for causing the microcomputer to function as the charge / discharge control device 23 is installed in the microcomputer and executed. This allows the microcomputer to function as a plurality of information processing units (31 to 38) included in the charge / discharge control device 23. Here, an example of realizing the charge / discharge control device by software is shown, but it is of course possible to configure the charge / discharge control device 23 by preparing dedicated hardware for executing each information process. The dedicated hardware includes devices such as application specific integrated circuits (ASICs) and conventional circuit components arranged to execute the functions described in the embodiments.

[0043] Although the charge / discharge control device 23, the receiving device 21, the vehicle state acquisition device 22, and the charge / discharge device 24 have been described as separate components, any two or more selected devices may be configured as one device. Alternatively, the multiple information processing units (31-38) may be divided and configured using two or more different devices. Furthermore, all or a part of the multiple information processing units (31-37) may be configured using other ECUs (Electronic Control Units) mounted on the electric vehicle EV1.

[0044] The charge / discharge control device 23 can apply the processing performed by the power receiving control device disclosed in International Publication No. 2020 / 194010 to other processing related to the charge / discharge control of the electric vehicle EV1, except for the processing related to the correction of the priority (β) shown below.

[0045] The charge / discharge control device 23 includes a charge / discharge request acquisition unit 31, a current information acquisition unit 32, a system frequency measurement unit 33, a priority calculation unit 34, a characteristic determination unit 35, a charge / discharge power calculation unit 36, and a charge / discharge control unit 37 as multiple information processing units (31 to 37).

[0046] The charge / discharge request acquisition unit 31 acquires, from the electrical signal received by the receiving device 21, information indicating the differential power (ΔPall fmax) at the maximum frequency (fmax) of the power system 10 as an example of a system request, and information indicating the difference in frequency adjustment capacity (ΔPall freq).

[0047] The current information acquiring unit 32 acquires the current value of the electric wire 12 measured by the ammeter 24 a of the charging / discharging device 24 at the connection end of the electric wire 12 to the electric vehicle EV 1 .

[0048] The system frequency measurement unit 33 measures the system frequency (f) of the electric wire 12 by using the current value of the electric wire 12 acquired by the current information acquisition unit 32.

[0049] The priority calculation unit 34 calculates the priority (β) of the electric vehicle EV1, which indicates the degree to which charging or discharging of the electric vehicle EV1 is prioritized over charging or discharging of other electric vehicles (EV2, EV3, ...), based on a numerical value representing the request of the user of the electric vehicle EV1 and the state of the electric vehicle EV1. Specifically, the priority calculation unit 34 calculates the priority (β) from the remaining time (T) from the current time (To) to the end time (Td) of charging or discharging using equation (2). In equation (2), N indicates the total number of electric vehicles to be charged or discharged. As a method for calculating the priority (β) using the current value (SOCnow) of the charging rate and the target value (SOCgoal) of the charging rate, the method disclosed in International Publication No. 2020 / 194010 can be used.

[0050]

number

[0051] The total number (N) of electric vehicles may be statistical data (quantity data) obtained by investigating the past charge / discharge history of the load group of the power system 10 including the electric vehicles connected to the electric line 12, or the total number (N) of electric vehicles may be estimated approximately from the current value (Pall_now) of the total charge / discharge power. The total number (N) is broadcast from the information transmission device 16 or a device associated with the information transmission device 16, similar to the differential power (ΔP). Alternatively, the total number (N) may be specified by location information or an identification signal of the charging system for electric vehicles.

[0052] The characteristic determination unit 35 determines the charge / discharge output characteristics of the electric vehicle EV1 with respect to the system frequency (f) based on the priority (β) calculated by the priority calculation unit 34 and the differential power (ΔPall fmax) and the frequency adjustment capacity difference (ΔPall freq) at the maximum frequency (fmax) of the power system 10 received by the receiving device 21. This output characteristic defines the charge / discharge output of the electric vehicle EV1 at each frequency within the adjustment range of the system frequency (f).

[0053] The characteristic determining unit 35 determines the charge / discharge output characteristics of the electric vehicle EV1 according to the priority (β).

[0054] If the output characteristics were such that the higher the priority (β), the larger the charge / discharge power (base power) secured separately from the frequency adjustment capacity, as in the output characteristics of the comparative example shown in Fig. 4, a frequency region would occur in the adjustment range of the grid frequency (f) where charging electric vehicles and discharging electric vehicles are mixed according to the output characteristics according to the priority (β). In this frequency region, power discharged from one electric vehicle is charged to another electric vehicle, so that the charge / discharge loss becomes large and the charge / discharge efficiency of the electric vehicles as a whole decreases.

[0055] Therefore, the characteristic determination unit 35 determines, as the output characteristic of the electric vehicle EV1, for example, an output characteristic in which the boundary between the charging region and the discharging region is the same system frequency (f) regardless of the priority (β), such as the output characteristics of each of the high, medium, and low priorities (β) shown in FIG. 3.

[0056] To distribute the total charging / discharging power of power system 10 to electric vehicle EV1 so that the boundary between the charging region and the discharging region is the same system frequency (f) regardless of the priority (β), it is necessary to distribute both the differential power (ΔPall fmax) available to electric vehicles EV1-EV3, ... at maximum frequency (fmax) and the frequency adjustment capacity (Pall freq) supplied by electric vehicles EV1-EV3, ... according to the priority (β) of electric vehicle EV1. The differential power (ΔPall fmax) is the intercept on the charging / discharging output axis of the output characteristic, and the frequency adjustment capacity (Pall freq) is the slope of the output characteristic.

[0057] If the power and slope used at the maximum frequency are distributed so that they are proportional to the priority (β) of electric vehicle EV1, then there will inevitably be one system frequency (f) at which the charge / discharge output becomes zero in the output characteristics of each priority (β). Expressed as a general formula, the charge / discharge output Pi at the system frequency (f) of each electric vehicle EVi is given by equation (3) as a function of the system frequency (f).

[0058]

number

[0059] Here, the subscript (subscript) "i" in formula (3) indicates each of the electric vehicles EV1 to EV3, . . .

[0060] In equation (3), if the differential power (ΔPall) and frequency regulation capacity (Pfreq) of all electric vehicles are distributed according to the priority βi of electric vehicle i, the element differential power (ΔPall,i) and element frequency regulation capacity (Pfreq,i) of each electric vehicle i are expressed by equation (4). In equation (4), "Btotal" is the sum of the priority βi of electric vehicle i.

[0061]

number

[0062] Applying equation (4) to the power difference (ΔPall) and frequency adjustment capacity (Pfreq) in equation (3) gives equation (5). In this equation, if the part on the right side excluding βi / Βtotal is "0", the charge / discharge output Pi of electric vehicle i becomes "0" regardless of the value of priority βi. Therefore, the characteristic determination unit 35 uses equation (3) to determine the charge / discharge output characteristic of electric vehicle EV1 in which the boundary between the charge region and the discharge region is the same system frequency (f) regardless of the priority (β).

[0063]

number

[0064] The charge / discharge power calculation unit 36 ​​calculates the element charge / discharge output of the electric vehicle EV1. Equation (6) can be used to calculate the element charge / discharge output. Equation (6) is an update equation for obtaining an update value (Pt+1) of the charge / discharge power (Pt) by multiple charge / discharge elements connected to the power grid from the differential power (ΔP) as the "grid request." In equation (6), the differential power (ΔP) is a value obtained by subtracting the current value (Pall_now) of the total charge / discharge power from the maximum value (Pall_max) of the total charge / discharge power of the power grid.

[0065]

number

[0066] In formula (6), the element power difference (βi×△P) is calculated by multiplying the power difference (△P) by the priority (βi) of the electric vehicle. The element power difference (β×△P) is then added to the element power difference (Pt) in the previous processing cycle, and a fixed power correction value (α×Pt) using a correction coefficient α for the current power difference (Pt+1) is subtracted to obtain the updated value of the element power difference (Pt). The subscripts (subscripts) “t” and “t+1” of the symbol “P” indicating the power difference (Pt) indicate the number of times the “processing cycle” is repeated. t is a positive integer including zero. By subtracting a fixed power correction value (α×Pt) when updating the element power difference (Pt), the power difference (△P) is less likely to become zero. An electric vehicle that wishes to start receiving power anew can start receiving power early.

[0067] By substituting the differential power (ΔPall fmax) and the frequency adjustment capacity difference (ΔPall freq) at the maximum frequency (fmax) received by the receiving device 21 into the charge / discharge power (Pt) in equation (6), the charge / discharge power calculation unit 36 ​​can calculate the updated value (ΔPt+1, all fmax) of the element differential power (ΔPt, all fmax) at the maximum frequency (fmax) and the updated value (ΔPt+1, all freq) of the element frequency adjustment capacity difference (ΔPt, all freq) according to the priority (β) of the electric vehicle (EV1).

[0068] The charge / discharge power calculation unit 36 ​​calculates the element charge / discharge output of its own EV1 using equation (3) from the calculated updated value of the element differential power (ΔPt+1, all fmax), the updated value of the element frequency adjustment capacity difference (ΔPt+1, all freq), and the system frequency (f) measured by the charge / discharge device 24.

[0069] The charge / discharge control unit 37 controls the charge / discharge device 24 so that the electric vehicle EV1 charges or discharges with the element charge / discharge output calculated by the charge / discharge power calculation unit 36. In this manner, the charge / discharge control device 23 controls the charge / discharge power (P) that is the power charged and discharged by the electric vehicle EV1, by repeating the process cycle of (a) to (f) shown below. (a) acquiring information indicating the differential power (ΔPt,all fmax) at the maximum frequency (fmax) and the differential in frequency adjustment capacity (ΔPt,all freq); (b) Calculate the priority (β) (c) Calculate the updated value (ΔPt+1,all fmax)(ΔPt+1,all freq) of the difference between the power difference (ΔPt,all fmax) at the maximum frequency (fmax) and the frequency adjustment capacity difference (ΔPt,all freq), and determine the charge / discharge output characteristics according to the priority (β); (d) Measure the system frequency (f) at the connection end. (e) determining the element charge / discharge output from the measured system frequency (f) and the updated values ​​(ΔPt+1,all fmax)(ΔPt+1,all freq) of the differential power (ΔPt,all fmax) and the frequency regulation capacity differential (ΔPt,all freq); (f) Controlling the charge / discharge device 24 so as to charge / discharge with the determined element charge / discharge output.

[0070] An example of a charge / discharge control method by the charge / discharge control device 23 in Fig. 2 will be described with reference to the flowchart in Fig. 5. This charge / discharge control method is executed by the charge / discharge control device 23 of each of the electric vehicles EV1-EV3, .... Note that a person skilled in the art can easily understand the specific steps of the charge / discharge control method by the charge / discharge control device 23 from the explanation of the specific configuration and function of the charge / discharge control device 23 in Fig. 2. Therefore, here, as the charge / discharge control method by the charge / discharge control device 23 in Fig. 2, the main processing operations of the charge / discharge control device 23 will be explained, and a detailed explanation of the processing operations will be omitted since it overlaps with the explanation with reference to Fig. 2.

[0071] First, in step S201, the priority calculation unit 34 calculates a priority (β) of charging and discharging from the current state of charge (SOCnow) of the battery 25 acquired by the vehicle state acquisition device 22, the scheduled departure time, and the like.

[0072] Proceeding to step S202, the charge / discharge power calculation unit 36 ​​calculates an update value (ΔPt+1, all fmax) of the element differential power (ΔPt, all fmax) at the maximum frequency (fmax) and an update value (ΔPt+1, all freq) of the element frequency adjustment capacity difference (ΔPt, all freq) according to the priority (β) of the electric vehicle (EV1).

[0073] Proceeding to step S203, the system frequency measurement unit 33 measures the system frequency (f) of the power line 12 using the current value of the power line 12 measured by the ammeter 24a. Proceeding to step S204, the charge / discharge power calculation unit 36 ​​determines the element charge / discharge output of the electric vehicle EV1 from the updated value (ΔPt+1, all fmax) of the element differential power (ΔPt, all fmax) at the maximum frequency (fmax), the updated value (ΔPt+1, all freq) of the element frequency adjustment capacity difference (ΔPt, all freq), the system frequency (f) of the power line 12 measured by the system frequency measurement unit 33, and the charge / discharge output characteristics determined by the characteristic determination unit 35.

[0074] Proceeding to step S205, the charge / discharge control unit 37 controls the charge / discharge device 24 so that the electric vehicle EV1 charges or discharges at the element charge / discharge output calculated by the charge / discharge power calculation unit .

[0075] According to the embodiment of the present invention, the following advantageous effects can be obtained.

[0076] Information transmission device 16 of power system 10 broadcasts the differential power (ΔPall fmax) at the maximum frequency (fmax) of the adjustment range of the system frequency (f) as a value indicating the margin of the maximum power amount for charging and discharging in power system 10, together with the frequency adjustment capacity difference (ΔPall freq) as a value indicating the margin of the frequency adjustment capacity of all electric vehicles EV1-EV3, .... Then, in each of electric vehicles EV1-EV3, ..., output characteristics that make the boundary between the charging region and the discharging region the same system frequency (f) regardless of the priority (β) are determined as the output characteristics of each electric vehicle EV1-EV3, ....

[0077] Therefore, electric vehicles of any priority level (β) will charge or discharge uniformly at the same system frequency (f). Therefore, the output characteristics according to the priority level (β) prevent the occurrence of a frequency region in which charging electric vehicles and discharging electric vehicles are mixed even at the same system frequency (f), and it is possible to prevent a decrease in the charging / discharging efficiency of electric vehicles EV1-EV3, ... in power system 10 as a whole due to charging / discharging losses.

[0078] (First Modification) In the above embodiment, the characteristic determination unit 35 determines a linear output characteristic spanning the charging region and the discharging region as shown in FIG. 3 according to the priority (β). In this output characteristic, the higher the priority (β) in the charging region, the larger the charging output, and in the discharging region, as shown in the area surrounded by the dashed line in FIG. 6, the higher the priority (β) is, the larger the discharging output is. In this case, the electric vehicles EV1-EV3, ..., which have a higher priority of the charging output, are more likely to discharge in the discharging region. Therefore, the priority (β) calculated by the priority calculation unit 34 may be made different between the charging region and the discharging region.

[0079] For example, as shown in Fig. 7, the priority (β) of all electric vehicles EV1-EV3,... may be reversed between the frequency domain where the electric vehicles EV1-EV3,... have a charging output and the frequency domain where the electric vehicles EV1-EV3,... have a discharging output. In this case, electric vehicles EV1-EV3,... that have a high priority (β) in the charging domain have a low priority (β) in the discharging domain. Conversely, electric vehicles EV1-EV3,... that have a low priority (β) in the charging domain have a high priority (β) in the discharging domain. For this reason, it is possible to make it more difficult for electric vehicles EV1-EV3,... that have a higher priority of charging output to discharge in the discharging domain.

[0080] The change to a different priority (β) may be made discontinuously at the timing when the system frequency (f) changes across the boundary between the charging region and the discharging region, or may be made continuously through multiple stages.

[0081] Furthermore, there are no constraints on the priority (β) in determining the charge / discharge output characteristics of each electric vehicle EV1-EV3, ... so that the boundary between the charge area and the discharge area is the same system frequency (f) regardless of the priority (β). Therefore, even if the priority (β) is made different between the charge area and the discharge area, it is possible to suppress a decrease in the charge / discharge efficiency of all electric vehicles EV1-EV3, ... in power system 10.

[0082] (Second Modification) In the above embodiment, the gradient of the output characteristic determined by the characteristic determination unit 35 according to the priority (β) increases as the priority (β) increases, as shown in Fig. 3. For this reason, depending on the magnitude of the gradient of the output characteristic, for example, the charging output on the maximum frequency side of the output characteristic corresponding to the high priority (β) may exceed the maximum charging energy of all of the electric vehicles EV1-EV3, ....

[0083] In this case, for example, it is conceivable to set an upper limit value to the priority (β) of the output characteristic whose charging output exceeds the maximum charging energy, and to shift the charging output so that it falls below the maximum charging energy, as in the output characteristic corresponding to the high priority (β) in the comparative example shown in Fig. 8. However, the system frequency (f) that is the boundary between the charging region and the discharging region of the shifted output characteristic of the high priority (β) will be a different frequency from the output characteristics of the other priorities (β).

[0084] Therefore, the priority calculation unit 34 may set an upper limit value for the priority (β) of the output characteristic whose charging output exceeds the maximum charging energy, and set the output characteristic corresponding to the high priority (β) whose charging output exceeds the maximum charging energy so that the charging output falls below the maximum charging energy and the boundary between the charging region and the discharging region of the output characteristic has the same frequency as the output characteristic of the other priority, as shown in Fig. 9. This upper limit value can be determined, for example, by an upper limit setting formula expressed by formula (7).

[0085]

number

[0086] This makes it possible to prevent the charging output from exceeding the maximum charging energy amount, while suppressing a decrease in the charging and discharging efficiency of all of the electric vehicles EV1-EV3, ... in the power system 10. In addition, by uniformly changing the electric vehicles EV1-EV3, ... whose charging output has reached the maximum charging energy amount to the same priority level (β), it becomes easier to prevent the boundary between the charging region and the discharging region from having different frequencies between the output characteristics of some priorities (β) and the output characteristics of other priorities.

[0087] Note that setting an upper limit value for the priority (β) in the second modified example is particularly effective when the ΔP term in equation (6) approaches zero. That is, characteristic determination unit 35 originally tries to make the slope of the output characteristics steeper for electric vehicles EV1-EV3, ... with higher priority (β), as shown in Fig. 3. For this reason, when the ΔP term in equation (6) approaches zero and the charging output of electric vehicles EV1-EV3, ... as a whole approaches the maximum charging energy amount, electric vehicles EV1-EV3, ... with higher priority (β) are not charged according to the output characteristics.

[0088] Therefore, when the ΔP term in equation (6) approaches zero, the priority calculation unit 34 sets an upper limit value for the priority (β), thereby making it difficult for the charge / discharge control unit 37 to issue control that causes a large charging output for electric vehicles EV1-EV3, ... that are in a situation where charging is difficult.

[0089] The above-described embodiment is merely an example of the present invention, and the present invention is not limited to the above-described embodiment, and various modifications can be made to the design and other aspects of the present invention without departing from the technical concept of the present invention. [Explanation of symbols]

[0090] 10 Power system 12 Electric wire 21 Receiving device 34 Priority calculation unit 35 Characterization Division 37 Charge / discharge control unit EV1, EV2, EV3, ... Electric vehicles

Claims

1. receiving a margin of maximum power amount for charging / discharging by a plurality of charging / discharging elements connected to an electric power line of the electric power system and a margin of frequency adjustment capacity according to a system frequency of the electric power system; Based on a priority indicating a degree to which charging or discharging of the charging or discharging element itself is prioritized over charging or discharging of other charging or discharging elements, and based on the received margin of the maximum power amount of the charging or discharging and the margin of the frequency adjustment capacity, a value of the system frequency that is a boundary between a charging region and a discharging region in the output characteristics of the charging or discharging element is determined according to the priority of charging or discharging for the system frequency, the value being the same regardless of the priority; Charging or discharging is performed at an output calculated based on the output characteristics. A method for controlling charging and discharging of a charging and discharging element.

2. The method for controlling charging and discharging of a charging and discharging element according to claim 1 , wherein the maximum amount of charging and discharging electric power in the output characteristics and the frequency adjustment capacity are in a proportional relationship between the output characteristics having different priorities.

3. The charge or discharge output based on the output characteristic is updated by the following formula, where the current charge / discharge power is Pt, the priority is βi, the margin of the maximum power amount of the charge / discharge is ΔP, and the correction coefficient for the current charge / discharge power is α. [006] The charge / discharge control method for a charge / discharge element according to claim 1 or 2, wherein the charge / discharge control method is performed by updating using the above formula.

4. A method for controlling charging and discharging of a charging and discharging element described in any one of claims 1 to 3, which determines the output characteristics based on the priority, which differs between the charging area and the discharging area.

5. A method for controlling charging and discharging of a charging and discharging element described in any one of claims 1 to 4, which determines the output characteristics based on the priority, which is reversed between the charging area and the discharging area.

6. 3. The method for controlling charging and discharging of a charging and discharging element according to claim 1, wherein an upper limit value is set for the priority when a charging output calculated based on the output characteristic reaches a maximum charging power of the power grid.

7. The charge or discharge output based on the output characteristic is updated by the following formula, where the current charge / discharge power is Pt, the priority is βi, the margin of the maximum power amount of the charge / discharge is ΔP, and the correction coefficient for the current charge / discharge power is α. [006] and updating the upper limit value using the following upper limit setting formula: [0070] The charge / discharge control method for a charge / discharge element according to claim 6,

8. A method for controlling charging and discharging of charging and discharging elements as described in claim 7, further comprising estimating the priority of the other charging and discharging elements based on a value of a margin ΔP of the maximum power amount of the charging and discharging in the update equation, and setting the upper limit value based on the estimated priority of the other charging and discharging elements.

9. a receiving unit that receives a margin of maximum power amount for charging and discharging by a plurality of charging and discharging elements connected to an electric line of a power system and a margin of frequency adjustment capacity according to a system frequency of the power system; a priority calculation unit that calculates a priority indicating a degree to which charging or discharging of the charging or discharging element itself is prioritized over charging or discharging of other charging or discharging elements; a characteristic determination unit that determines the output characteristic according to the priority of charging and discharging for the grid frequency, based on the priority, a margin of the maximum power amount of the charging and discharging, and a margin of the frequency adjustment capacity, such that the value of the grid frequency that is a boundary between a charging region and a discharging region in the output characteristic of the charging and discharging element is the same regardless of the priority; and A control unit that controls a charging or discharging output in the power system with an output calculated based on the output characteristics; A charge / discharge control device for a charge / discharge element comprising:

Images