Charge and discharge control method and charge and discharge control device

Abstract

To prevent the power demand of a facility that uses batteries of electric vehicles as storage batteries from exceeding a target power.SOLUTION: A prediction unit 21 of a power supply and demand management device 20 predicts a range of a power supply and demand amount from the start to the end of a control cycle for power consumption elements excluding an EV battery 50, among groups of power consumption elements in a power supply and demand system 1. An estimation unit 22 estimates a range of a power purchase amount by the entire group from the start to the end of the control cycle based on the range of the power supply and demand amount. A calculation unit 23 calculates a range of an evaluated power amount from the start to the end of the control cycle, indicating a difference between an average value per control cycle of a predetermined limit value for the power purchase amount by the entire group and the range of the power purchase amount. A charging and discharging control unit 24 stops charging of the EV battery 50 when a minimum value P of the range of the evaluated power amount from the start to the end of the control cycle, calculated by dividing the range of the evaluated power amount by the remaining time from the present to the end of the control cycle, is a negative (-) value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a charge / discharge control method and a charge / discharge control device. [Background technology]

[0002] Patent Document 1 proposes a power system that can reduce the processing load on a management device for multiple power conditioners while setting the power to be adjusted to a target value. In this proposal, an index value is calculated to control the individual output of each of multiple power conditioners in a power generation system that uses renewable energy so that the power to be adjusted becomes the target power. Each power conditioner calculates its individual target power based on an optimization problem using the calculated index value, and controls the output of each power conditioner so that the calculated individual target power is achieved. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017 / 150376 Summary of the Invention [Problem to be solved by the invention]

[0004] In facilities that use the batteries of electric vehicles connected to chargers as storage batteries, the facility's contracted power is set as a target power, and charging and discharging of the batteries of the electric vehicles are sometimes controlled so that the facility's power demand matches the target power. In this case, the output control of the power conditioner in Patent Document 1 can be applied to the charging and discharging control of the batteries of the electric vehicles. When the control in Patent Document 1 is applied to the charging and discharging control of the batteries, if the facility's power demand is less than the target power, the calculated index value is increased and the battery charge amount is increased, so that the facility's power demand approaches the target power. If the facility's power demand exceeds the target power, the calculated index value is decreased and the battery charge amount is reduced or the battery is discharged, so that the facility's power demand approaches the target power.

[0005] If the facility's power demand is lower than the target power and the battery charge amount is increased to bring the facility's power demand closer to the target power, the facility's power demand will quickly exceed the target power if power consumption by factors other than the facility's electric vehicles increases thereafter. It is desirable to avoid power demand exceeding the target power as much as possible so that power consumption does not exceed the contracted power.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent the power demand of a facility that uses the batteries of electric vehicles as storage batteries from exceeding a target power. [Means for solving the problem]

[0007] To solve the above-mentioned problems, a charge / discharge control method according to one embodiment of the present invention performs charge / discharge control of charge / discharge elements included in a group of power consumption elements for each control period. In the charge / discharge control for each control period, a range of power supply and demand from the start to the end of the control period is predicted for the power consumption elements excluding the charge / discharge elements of the group, and a range of purchased power from the start to the end of the control period is estimated based on the predicted range of power supply and demand. Furthermore, a range of evaluated power from the start to the end of the control period is calculated, which indicates the difference between the average value per control period of a predetermined limit value for purchased power for the entire group and the estimated range of purchased power. If the minimum value of the range of evaluated power, which indicates the range of power magnitude corresponding to the calculated range of evaluated power, is a negative (-) value, charging of the charge / discharge element is stopped. [Effects of the Invention]

[0008] According to the present invention, it is possible to prevent the power demand of a facility that uses the battery of an electric vehicle as a storage battery from exceeding a target power. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of the overall configuration of a power management system to which a charge / discharge control method according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is a flowchart of an example of the procedure of the charge / discharge control method according to the embodiment. [Figure 3] FIG. 3 is a flowchart of an example of the procedure of the charge / discharge control method according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating a specific example of charging control of an EV battery. [Figure 5] FIG. 5 is a diagram illustrating a specific example of charging control of an EV battery. [Figure 6] FIG. 6 is a diagram illustrating a specific example of charging control of an EV battery. [Figure 7] FIG. 7 is a diagram illustrating a specific example of charging control of an EV battery. [Figure 8] FIG. 8 is a flowchart of an example of a procedure in which the power supply and demand management device determines the charge amount for each EV battery based on the determined charging power. [Figure 9] FIG. 9 is a flowchart of an example procedure in which each EV charger determines the charge amount for each EV battery based on the determined charging power. [Figure 10] FIG. 10 is a diagram illustrating a specific example of discharge control of an EV battery. [Figure 11] FIG. 11 is a diagram illustrating a specific example of discharge control of an EV battery. [Figure 12] FIG. 12 is a diagram illustrating a specific example of discharge control of an EV battery. [Figure 13] FIG. 13 is a diagram illustrating a specific example of discharge control of an EV battery. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention and its modified examples will be described with reference to the drawings. In the drawings, identical parts are designated by the same reference numerals and their description will be omitted. With reference to FIG. 1, an example of the overall configuration of a power management system to which a charge / discharge control method according to an embodiment of the present invention is applied will be described. The power management system is a system that manages the supply and demand of power for the entire power supply and demand system 1 of a commercial facility, factory, etc. As shown in FIG. 1, the power management system includes the power supply and demand system 1, a power system monitoring and control system 2, and a power system 3.

[0011] The electricity supply and demand system 1 is a system that manages, for example, charges for electricity at a facility or a single demand location. The system may be a system in which multiple demand locations are virtually connected, rather than a single demand location. As shown in FIG. 1 , the electricity supply and demand system 1 includes power meters 10 and 30, an electricity supply and demand management device 20, an EV charger 40, a load 70, and a renewable energy power generation facility 80.

[0012] The power grid 3 is a power system that integrates power generation, transformation, transmission, and distribution to supply AC power from the power company to power-receiving equipment, and the EV charger 40, load 70, and renewable energy power generation equipment 80 correspond to the power-receiving equipment. The power grid 3 is connected to each of the EV charger 40, load 70, and renewable energy power generation equipment 80 via a power meter 10.

[0013] The power meter 10 measures the power of the power grid 3 consumed in the power supply and demand system 1 as the amount of power consumption. The power meter 10 also measures the power supplied from the power supply and demand system 1 to the power grid 3 as the amount of generated power. The amount of power obtained by subtracting the amount of generated power from the amount of consumed power is the amount of power purchased by the power supply and demand system 1 from the power grid 3.

[0014] The EV charger 40 is controlled by the power supply and demand management device 20 (described later) and is a charging and discharging facility that charges and discharges the EV battery 50, which is the battery of an electric vehicle. The EV charger 40 is connected to the EV battery 50 via, for example, a power connector, and charges the EV battery 50. The EV charger 40 also discharges the power stored in the EV battery 50 from the EV battery 50. Note that there are no particular limitations on the connection method between the EV charger 40 and the EV battery 50 or the charging and discharging method. The EV charger 40 may also be located inside the electric vehicle. Furthermore, the connection between the EV charger 40 and the power supply and demand management device 20 may be wired or wireless, or may be via the Internet, for example. The charging and discharging power of the EV battery 50 by the EV charger 40 can be measured for each EV battery 50 by a power meter 30.

[0015] The load 70 operates by receiving a supply of electric power. The load 70 may include either an uncontrollable load or a controllable load, or may include both. An uncontrollable load is a device or facility, such as a hair dryer, whose power demand (power consumption) cannot be controlled by an external command. On the other hand, a controllable load is a facility, such as an air conditioning facility or a lighting facility, whose power demand (power consumption) can be controlled by an external command.

[0016] The renewable energy power generation facility 80 is a solar power generation facility, a wind power generation facility, or the like, and is a facility whose generateable power varies over time.

[0017] FIG. 1 illustrates two EV chargers 40, one load 70, and one renewable energy power generation facility 80. The power supply and demand system 1 may include one or more EV chargers 40, two or more loads 70, and a renewable energy power generation facility 80. The power supply and demand system 1 may also include a non-renewable energy power generation facility and a storage battery not illustrated in FIG. 1. The non-renewable energy power generation facility is a facility whose generateable power does not change over time, such as a diesel power generation facility or a hydrogen fuel power generation facility. The storage battery stores power supplied from the power grid 3, the renewable energy power generation facility 80, or the non-renewable energy power generation facility. If the power supply and demand system 1 includes a non-renewable energy power generation facility and a storage battery, these also qualify as power receiving facilities. The power grid 3 is also connected to each of the non-renewable energy power generation facility and the storage battery via a power meter 10. The renewable energy power generation facility 80, the non-renewable energy power generation facility, and the storage battery may supply (discharge) power to the power grid 3 (this is called reverse power flow). Furthermore, EV charger 40 receives power from power grid 3 in accordance with instructions from power supply and demand management device 20. EV charger 40 may also discharge power from EV battery 50 in accordance with instructions from power supply and demand management device 20 and supply the power to power grid 3.

[0018] The power supply and demand management device 20 has a function (power supply and demand management function) of managing the power supply and demand of the entire group of power consumption elements of the power supply and demand system 1, including the EV batteries 50 of the electric vehicles connected to the EV charger 40, the load 70, and the renewable energy power generation equipment 80. The group of power consumption elements includes the EV charger 40, the EV batteries 50 of the electric vehicles connected to the EV charger 40, the load 70, and the renewable energy power generation equipment 80. Among the group of power consumption elements, the EV battery 50 corresponds to a charge / discharge element. If the power supply and demand system 1 includes the non-renewable energy power generation equipment and storage batteries described above, the non-renewable energy power generation equipment and storage batteries are included in the group of power consumption elements, and the storage batteries correspond to a charge / discharge element. The power supply and demand management device 20 also has a function (electric vehicle group power management function) of managing the power charged / discharged by the EV charger 40 to one or more EV batteries 50. The power supply and demand management device 20 has, for example, a general-purpose microcontroller. The microcontroller of the power supply and demand management device 20 includes a central processing unit (CPU) (not shown) having an input / output unit and an arithmetic unit, and a memory. The memory includes a read-only memory (ROM) and a random access memory (RAM). For example, the microcontroller can virtually configure multiple information processing circuits by having the CPU execute a program stored in the memory. The multiple information processing circuits of the power supply and demand management device 20 include a prediction unit 21, an estimation unit 22, a calculation unit 23, and a charge / discharge control unit 24 as multiple information processing units for realizing the power supply and demand management function and the electric vehicle fleet power management function. Each of the units 21 to 24 will be described later.

[0019] In the power supply and demand system 1 that purchases power from the power grid 3, one period that is the basis for calculating the contract power is used as a control period, and charge and discharge control is performed to keep the average purchased power for the control period within the contract power. For comparison with the present invention, the following describes a case where the output control of a power conditioner in Patent Document 1, which is cited as a prior art document, is applied to charge and discharge control of the battery of an electric vehicle within a facility.

[0020] In this case, charge / discharge control divides one control cycle into multiple unit cycles, and calculates the differential power for each unit cycle by subtracting the actual purchased power during that unit cycle from the target power. If the differential power for a certain unit cycle is a positive (+) surplus power, the charging power allocated to charging the battery among the actual purchased power is increased by the amount of the surplus power in the next unit cycle. If the differential power for a certain unit cycle is a negative (-) shortage power, the charging power allocated to charging the battery among the actual purchased power is reduced by the amount of the shortage power in the next unit cycle. In this charge / discharge control, the surplus power in a unit cycle is immediately consumed to charge the battery in the next unit cycle, so the average purchased power during the control cycle is always controlled to be close to the target power. In this charge / discharge control, if the facility's power consumption increases during the same control cycle after the battery charging power is increased, the average purchased power for the control cycle can easily exceed the target power.

[0021] In this charge / discharge control, if the difference in power in a certain unit cycle is surplus power, the battery charging power is increased in the next unit cycle, and if the difference in power is insufficient, the battery charging power is decreased in the next unit cycle. This can easily result in variations in the battery charging power for each unit cycle. In a unit cycle in which the battery charging power is low, the charging amount is reduced or charging is stopped even for batteries with a low state of charge. In a unit cycle in which the battery charging power is high, not only batteries with a low state of charge but also batteries with a high state of charge are charged. This type of charge / discharge control does not allow for efficient and focused charging of batteries with a low state of charge, making it difficult to make appropriate and effective use of purchased power. If purchased power cannot be effectively used, for example, when a facility's power consumption decreases, the contracted power cannot be fully consumed by simply adjusting the battery charging amount. If the contracted power is not fully consumed or a demand response request is triggered as a result, contractual penalties may be imposed.

[0022] Fluctuations in the power consumption of the facility described above may occur, for example, between normal business hours when company employees are present at work and after normal business hours when most employees leave the office. Even during normal business hours, fluctuations in the facility's power consumption may occur between lunch breaks and the time periods before and after lunch breaks. In facilities with solar power generation equipment, fluctuations in the amount of solar radiation may cause fluctuations in the facility's power consumption. In facilities where these situations are likely to occur, the average purchased power over a control period is particularly likely to exceed the target power due to the battery charge / discharge control described above, making it difficult to efficiently charge batteries with low states of charge and appropriately utilize the purchased power.

[0023] For these reasons, it is undesirable to supply charging power equally to the batteries of electric vehicles with low SOCs (low SOC (State of Charge) vehicles) and those with high SOCs (high SOC vehicles). However, in charge / discharge control that applies the control of Patent Document 1, charging power is supplied equally to each battery when the charging power of the batteries is high, resulting in equal charging of not only batteries with low SOCs but also batteries with high SOCs. To effectively utilize purchased power, it is desirable, for example, to supply more charging power to batteries of electric vehicles with low SOCs than batteries of electric vehicles with high SOCs. If charging power can be supplied preferentially to batteries with low SOCs, the possibility of charging the batteries with low SOCs with the necessary power before the electric vehicle departs increases. Furthermore, lowering the priority of supplying charging power to batteries with high SOCs delays the time it takes for batteries with high SOCs to reach full charge, making it easier to ensure a margin for adjusting the battery charge amount in preparation for fluctuations in power consumption at the facility.

[0024] The power supply and demand management device 20 constitutes a charge and discharge control device that performs charge and discharge control for the EV battery 50, which is a charge and discharge element, at each control cycle. In charge control of the EV battery 50 using the electric vehicle group power management function, the power supply and demand management device 20 performs control to supply charging power preferentially to electric vehicles with EV batteries 50 having a low state of charge. This control does not control charging the EV battery 50 with high charging power in a short period of time when the charging power is high, but rather control to continue charging the EV battery 50 with low charging power for a long period of time even when the charging power is low. When the EV battery 50 is charged with high charging power in a short period of time when the charging power is high, not only EV batteries 50 with low state of charge and high need for charging are charged uniformly, but also EV batteries 50 with high state of charge and low need for charging. When EV batteries 50 with low state of charge and low need for charging are continued to be charged for a long period of time even when the charging power is low, more charging power can be supplied to EV batteries 50 with high need for charging.

[0025] The prediction unit 21 of the power supply and demand management device 20 predicts the range of power supply and demand from the start to the end of a control period for the power consumption elements, excluding the EV battery 50, which is a charging and discharging element, among the group of power consumption elements in the facilities of the power supply and demand system 1. One control period may be, for example, 30 minutes. The prediction unit 21 can predict the power supply and demand for the power consumption elements, excluding the charging and discharging elements, based on the predicted range of power consumption by the load 70 and the predicted range of power generation by the renewable energy power generation facility 80, from the start to the end of the control period.

[0026] The range of power consumption by the load 70 can be predicted based on, for example, weather forecast information for the period from the start to the end of the control cycle. The power consumption by the load 70 may vary depending on the time of day. The range of power consumption by the load 70 may be predicted taking into account the time of day for the period from the start to the end of the control cycle. The power generation capacity of the renewable energy power generation facility 80 can be roughly estimated based on, for example, the time period from the start to the end of the control cycle, the season, etc. If the renewable energy power generation facility 80 is a solar power generation or wind power generation facility, for example, it may be possible to predict changes in power generation capacity over a local time width based on the movement of clouds during the period from the start to the end of the control cycle. The range of power generation capacity by the renewable energy power generation facility 80 may be predicted taking into account the time period from the start to the end of the control cycle, the season, or the movement of clouds during that period.

[0027] The estimation unit 22 estimates the range of the amount of power purchased by the entire group of power consumption elements of the power supply and demand system 1 from the start to the end of the control cycle based on the range of the power supply and demand predicted by the prediction unit 21. The amount of power purchased is the amount of power purchased by the power supply and demand system 1 from the power grid 3. The range of the amount of power purchased by the entire group of power consumption elements can be estimated by adding the predicted range of the amount of power purchased from the present to the end of the control cycle, Eothers,predict,lower to Eothers,predict,upper, to the actual amount of power purchased from the start of the control cycle to the present, Eothers,predict,lower, and Eothers,predict,upper, respectively. Eothers,predict,lower indicates the minimum value of the predicted range of the amount of power purchased from the present to the end of the control cycle, and Eothers,predict,upper indicates the maximum value. The actual amount of power purchased from the start of the control cycle to the present, Eused, can be obtained from the power meter 10. The predicted range of the amount of power purchased from the present to the end of the control cycle, Eithers,predict,lower to Eithers,predict,upper, can be calculated based on the predicted range of the amount of power purchased from the start to the end of the control cycle and the elapsed time from the start of the control cycle to the present. The predicted range of the amount of power purchased from the start to the end of the control cycle can be, for example, the range of power supply and demand from the start to the end of the control cycle predicted by the prediction unit 21.

[0028] The calculation unit 23 calculates the range of the evaluated energy from the start to the end of the control period. The evaluated energy represents the difference between Elimit, the average value per control period of the limit value set in advance for the amount of energy purchased by the entire group of power consumption elements in the energy supply and demand system 1, and the range of the amount of energy purchased estimated by the estimation unit 22. For example, if the contracted power is 50 kW and the control period is 30 minutes, the average value Elimit of the limit value for the amount of energy purchased is 50 kW × 0.5 h = 25 kWh. The range of the evaluated energy, Eused+Eothers,predict,lower to Eused+Eothers,predict,upper, is a range with {Elimit-(Eused+Eothers,predict,upper)} as the minimum value and {Elimit-(Eused+Eothers,predict,lower)} as the maximum value.

[0029] Charge / discharge control unit 24 stops charging of EV battery 50 when the minimum value of the range of evaluated power from the start to the end of the control cycle is a negative (-) value. The range of evaluated power refers to the range of power magnitude corresponding to the range of evaluated energy calculated by calculation unit 23, {Elimit-(Eused+Eothers,predict,upper)} to {Elimit-(Eused+Eothers,predict,lower)}. The range of evaluated power can be, for example, the range of evaluated energy calculated by calculation unit 23 divided by the remaining time Tremain from the present to the end of the control cycle. The minimum and maximum evaluated power values PEV,average,lower and PEV,average,upper are {Elimit-(Eused+Eothers,predict,upper)} / Tremain and {Elimit-(Eused+Eothers,predict,lower)} / Tremain, respectively, obtained by dividing the minimum and maximum evaluated energy values by the remaining time.

[0030] 2 and 3 are flowcharts showing an example of the procedure of a charge / discharge control method according to an embodiment of the present invention. This charge / discharge control method can be executed by the power supply and demand management device 20 using the units 21 to 24 in the power supply and demand system 1, for example. As shown in FIG. 2, in the charge / discharge control method according to the embodiment, the power supply and demand management device 20 acquires an average value Elimit of the limit value for the amount of power purchased per control cycle (step S1), and acquires the actual amount of power purchased Eused from the start of the control cycle to the present (step S3). The power supply and demand management device 20 further acquires a prediction range, Eothers,predict,lower to Eothers,predict,upper, of the amount of power purchased from the present to the end of the control cycle (step S5). The order of the steps S1 to S5 may be reversed, or some or all of the steps may be performed simultaneously in parallel. The power supply and demand management device 20 checks whether the minimum value PEV,average,lower of the range of evaluated power corresponding to the range of evaluated power calculated by the calculation unit 23 is a negative (-) value (step S7). If the minimum value PEV,average,lower is a negative (-) value (YES in step S7), the power supply and demand management device 20 performs processing not to charge the EV battery 50 connected to the EV charger 40 (step S9) and returns to step S3. If the minimum value PEV,average,lower is 0 or a positive (+) value (NO in step S7), the power supply and demand management device 20 performs processing to charge the EV battery 50 connected to the EV charger 40 (step S11) and returns to step S3.

[0031] As shown in FIG. 3, in the charging process for EV battery 50 (step S11 in FIG. 2), power supply and demand management device 20 checks whether the maximum value PEV,average,upper of the range of evaluated power is greater than the maximum charging output value PEV,cmax (step S21). The maximum charging output value PEV,cmax is the charging output value required to charge the EV batteries 50 of the maximum number of electric vehicles connected to the EV charger 40. By communicating with each EV charger 40 or each electric vehicle, power supply and demand management device 20 can grasp the charging state of the EV batteries 50 of each electric vehicle. The power supply and demand management device 20 can calculate the maximum charging output value PEV,cmax based on the grasped charging state of each EV battery 50.

[0032] If the maximum value PEV,average,upper is equal to or less than the maximum charging output value PEV,cmax (NO in step S21), the power supply and demand management device 20 checks whether the minimum value PEV,average,lower of the range of evaluated power is equal to or less than the minimum charging output value PEV,ctarget (step S23). The minimum charging output value PEV,ctarget is the charging output value required to charge the minimum number of EV batteries 50 that should be charged among the EV batteries 50 of electric vehicles connected to the EV charger 40. The minimum number of EV batteries 50 that should be charged may be, for example, EV batteries 50 whose state of charge has dropped to or near the minimum value of the allowable range and require immediate charging. The power supply and demand management device 20 can grasp the state of charge of the EV batteries 50 of each electric vehicle by communicating with each EV charger 40 or each electric vehicle. The power supply and demand management device 20 can calculate the minimum charging output value PEV,ctarget based on the grasped state of charge of each EV battery 50. If the minimum value PEV,average,lower is equal to or less than the minimum charge output value PEV,ctarget (YES in step S23), the process proceeds to step S31, which will be described later.

[0033] If the minimum value PEV,average,lower is greater than the minimum charging output value PEV,ctarget (NO in step S23), the power supply and demand management device 20 performs processing to charge the EV battery 50 of the EV charger 40 with charging power within the range of the evaluation power (step S25). Details of the charging processing in step S25 will be described later with reference to FIG.

[0034] If the maximum value PEV,average,upper is greater than the maximum charging output value PEV,cmax (YES in step S21), the power supply and demand management device 20 checks whether the minimum value PEV,average,lower of the range of evaluated power is equal to or less than the minimum charging output value PEV,ctarget (step S27). If the minimum value PEV,average,lower is greater than the minimum charging output value PEV,ctarget (NO in step S27), the power supply and demand management device 20 performs processing to charge the EV battery 50 of the EV charger 40 with charging power of the maximum charging output value PEV,cmax (step S29). The charging processing in step S29 allows all EV batteries 50 connected to the EV charger 40 to be charged. If the minimum value PEV,average,lower is equal to or less than the minimum charging output value PEV,ctarget (YES in step S27), the processing proceeds to step S31.

[0035] In step S31, the power supply and demand management device 20 performs processing to charge the EV batteries 50 of the EV charger 40 with charging power of the minimum value PEV,average,lower. In the charging processing of step S31, the minimum number of EV batteries 50 that should be charged out of the EV batteries 50 connected to the EV charger 40 can be charged at the slowest charging speed. The charging processing of the EV batteries 50 ends after step S25, step S29, or step S31.

[0036] Specific examples of charging control of EV battery 50 by power supply and demand management device 20 will be described with reference to FIGS. 4 to 6. FIG. 4 shows a case where the maximum value PEV,average,upper of the range of evaluated power is higher than the maximum charging output value PEV,cmax. Here, as shown in FIG. 4, a case where the minimum value PEV,average,lower of the range of evaluated power is a negative (-) value will be described. In this case, power supply and demand management device 20 does not charge EV battery 50 connected to EV charger 40. If the minimum value PEV,average,lower is negative (-), depending on future power consumption at the facility, the amount of purchased power under the contract power may not be enough, and discharging of EV battery 50 may be necessary. If charging EV battery 50 now results in discharging EV battery 50 later, this will result in unnecessary charging and discharging of EV battery 50, which will result in power loss. By not charging the EV battery 50 when the minimum value PEV,average,lower is negative (-), it is possible to prevent losses caused by unnecessary charging and discharging of the EV battery 50. This makes it possible to prevent the power demand of facilities that use the EV batteries 50 of electric vehicles as storage batteries from exceeding the target power.

[0037] Next, we will explain the case where the maximum value PEV,average,upper of the range of evaluated power is higher than the maximum charging output value PEV,cmax and the minimum value PEV,average,lower is a positive (+) value. In this case, the power supply and demand management device 20 charges the EV battery 50 connected to the EV charger 40. For example, if the minimum value PEV,average,lower is lower than the minimum charging output value PEV,ctarget, the power supply and demand management device 20 charges the EV battery 50 of the electric vehicle connected to the EV charger 40 with the charging power of the minimum value PEV,average,lower. Because the minimum value PEV,average,lower is lower than the minimum charging output value PEV,ctarget, in this charging, the minimum EV battery 50 to be charged among the EV batteries 50 of the electric vehicles connected to the EV charger 40 is charged at a low charging rate. In this charging, even if there is a possibility that the power available for charging the EV battery 50 will decrease in the future, by continuing to charge the minimum EV battery 50 at a low rate for a long period of time, it is possible to reliably charge EV batteries 50 with a low state of charge. In addition, during the period from the present to the end of the control cycle, a larger adjustment margin for the charge amount of the EV battery 50 can be secured to keep the amount of purchased power below the average limit value Elimit and to keep the average purchased power for the control cycle within the contracted power.

[0038] Next, we will explain the case where the maximum value PEV,average,upper of the range of evaluated power is higher than the maximum charging output value PEV,cmax and the minimum value PEV,average,lower is higher than the minimum charging output value PEV,ctarget. In this case, the power supply and demand management device 20 charges the EV batteries 50 of electric vehicles connected to the EV charger 40 with charging power of the maximum charging output value PEV,cmax. In this charging, the EV batteries 50 of all electric vehicles connected to the EV charger 40 are charged at a high charging rate. As the power that can be supplied to charge the EV batteries 50 increases further, the minimum value PEV,average,lower becomes higher than the maximum charging output value PEV,cmax, and the entire range of evaluated power becomes higher than the maximum charging output value PEV,cmax. In this situation, even if all EV batteries 50 are charged at a high rate, the facility will not be able to consume all of the contracted power. By charging all EV batteries 50 at high speed while the minimum value PEV,average,lower is lower than the maximum charging output value PEV,cmax, the contracted power amount can be effectively used to charge the EV batteries 50 and consumed efficiently.

[0039] FIG. 5 shows a case where the maximum value PEV,average,upper of the range of evaluated power is lower than the maximum charging output value PEV,cmax and higher than the minimum charging output value PEV,ctarget. Here, we will explain the case where the minimum value PEV,average,lower of the range of evaluated power is a negative (-) value, as shown in FIG. 5. In this case, the power supply and demand management device 20 performs control to stop charging of the EV battery 50. This control prevents losses caused by unnecessary charging and discharging of the EV battery 50, and prevents the facility's power demand from exceeding the target power.

[0040] Next, we will explain the case where the maximum value PEV,average,upper of the range of evaluated power is lower than the maximum charging output value PEV,cmax and higher than the minimum charging output value PEV,ctarget, and the minimum value PEV,average,lower is a positive (+) value. In this case, the power supply and demand management device 20 charges the EV battery 50 connected to the EV charger 40. For example, if the minimum value PEV,average,lower is lower than the minimum charging output value PEV,ctarget, the power supply and demand management device 20 charges the EV battery 50 of the electric vehicle connected to the EV charger 40 with the charging power of the minimum value PEV,average,lower. In this charging, the minimum EV battery 50 to be charged among the EV batteries 50 of the electric vehicle connected to the EV charger 40 is charged at a low charging rate. Even if there is a possibility that the power available for charging the EV battery 50 will decrease in the future, EV batteries 50 with a low state of charge can be reliably charged by continuing to charge the minimum EV battery 50 at a low rate for a long period of time. Furthermore, a larger margin for adjusting the charge amount of EV battery 50 can be secured during the period from the present to the end of the control cycle.

[0041] A case in which the maximum value PEV,average,upper of the range of evaluation power is lower than the maximum charging output value PEV,cmax and the minimum value PEV,average,lower is higher than the minimum charging output value PEV,ctarget will be described later with reference to FIG.

[0042] Fig. 6 shows a case where the maximum value PEV,average,upper of the range of evaluated power is lower than the minimum charge output value PEV,ctarget. Here, as shown in Fig. 6, a case where the minimum value PEV,average,lower of the range of evaluated power is a negative (-) value will be described. In this case, the power supply and demand management device 20 does not charge the EV battery 50 connected to the EV charger 40. By not charging the EV battery 50 when the minimum value PEV,average,lower is negative (-), it is possible to prevent losses from occurring due to unnecessary charging and discharging of the EV battery 50 and to prevent the facility's power demand from exceeding the target power.

[0043] Next, we will explain the case where the maximum value PEV,average,upper of the range of evaluated power is lower than the minimum charging output value PEV,ctarget and the minimum value PEV,average,lower is a positive (+) value. In this case, the power supply and demand management device 20 charges the EV battery 50 connected to the EV charger 40. Here, we will explain the case where the minimum value PEV,average,lower is lower than the minimum charging output value PEV,ctarget. In this case, the power supply and demand management device 20 charges the EV battery 50 of the electric vehicle connected to the EV charger 40 with charging power of the minimum value PEV,average,lower. In this charging, of the EV batteries 50 of the electric vehicles connected to the EV charger 40, the minimum EV batteries 50 that should be charged are charged at a low charging rate. Even if there is a possibility that the power that can be supplied to charge the EV batteries 50 will decrease in the future, by continuing to charge the minimum EV batteries 50 at a low rate for a long period of time, EV batteries 50 with a low state of charge can be reliably charged. Furthermore, a larger margin for adjusting the charge amount of EV battery 50 can be secured during the period from the present to the end of the control cycle.

[0044] If the maximum value PEV,average,upper and the minimum value PEV,average,lower of the range of evaluated power are negative (-) values, the minimum value PEV,average,lower is negative (-), so the power supply and demand management device 20 does not charge the EV battery 50 connected to the EV charger 40.

[0045] 7 shows a case where the maximum value of the evaluated power PEV,average,upper is lower than the maximum charging output value PEV,cmax and the minimum value PEV,average,lower is higher than the minimum charging output value PEV,ctarget. When the maximum value PEV,average,upper is lower than the maximum charging output value PEV,cmax, the power supply and demand management device 20 sets the charging power of the EV battery 50 closer to the maximum value PEV,average,upper as the maximum value PEV,average,upper increases and approaches the maximum charging output value PEV,cmax. As the maximum value PEV,average,upper decreases and moves away from the maximum charging output value PEV,cmax, the power supply and demand management device 20 sets the charging power of the EV battery 50 closer to the minimum value PEV,average,lower. If the minimum value PEV,average,lower is higher than the minimum charging output value PEV,ctarget, the power supply and demand management device 20 sets the charging power of the EV battery 50 closer to the minimum value PEV,average,lower as the minimum value PEV,average,lower decreases and approaches the minimum charging output value PEV,ctarget.The power supply and demand management device 20 sets the charging power of the EV battery 50 closer to the maximum value PEV,average,upper as the minimum value PEV,average,lower increases and moves away from the minimum charging output value PEV,ctarget.

[0046] In the example of Figure 7, power supply and demand management device 20 determines the value of the charging power for EV battery 50 as follows: Power supply and demand management device 20 calculates a maximum difference value, which is the difference between the maximum charging output value PEV,cmax and the maximum value PEV,average,upper, and calculates a minimum difference value, which is the difference between the minimum value PEV,average,lower and the minimum charging output value PEV,ctarget. Power supply and demand management device 20 sets the charging power for EV battery 50 to a value at a point obtained by proportionally dividing the range of evaluated power using the ratio between the absolute value of the maximum difference value and the absolute value of the minimum difference value.

[0047] By setting the charging power of the EV battery 50 to a value closer to the maximum value PEV,average,upper as the maximum value PEV,average,upper approaches the maximum charging output value PEV,cmax, the contracted power amount can be effectively utilized for charging the EV battery 50 and consumed efficiently. By setting the charging power of the EV battery 50 to a value closer to the minimum value PEV,average,lower as the maximum value PEV,average,upper deviates from the maximum charging output value PEV,cmax, the EV battery 50 can be prevented from discharging after charging and causing unnecessary loss. By setting the charging power of the EV battery 50 to a value closer to the minimum value PEV,average,lower as the minimum value PEV,average,lower approaches the minimum charging output value PEV,ctarget, the EV battery 50 can be reliably charged even if the power available for charging is reduced. The further the minimum value PEV,average,lower is from the minimum charging output value PEV,ctarget, the closer the charging power of the EV battery 50 is to the maximum value PEV,average,upper, so that the contracted power amount can be effectively used to charge the EV battery 50 and consumed efficiently.

[0048] A specific example of the case where the power supply and demand management device 20 performs the charge and discharge control described with reference to Figures 4 to 7 will be described below. For example, if 15 minutes have passed since the start of a 30-minute control cycle and the contracted power is 50 kW, the available power for the remaining 15-minute time period, Tremain, is 25 kWh. Here, the predicted range of the amount of power purchased from the present to the end of the control cycle, Eothers,predict,lower to Eothers,predict,upper, is set to 6 to 11 kWh, and the chargeable power that can be received by all EV batteries 50 connected to EV chargers 40 through charging is set to 20 kW. If the actual amount of power purchased from the start of the control cycle to the present, Eused, is 15 kWh, the remaining available power that can be consumed by the facility for the remaining 15-minute time period, Tremain, is 25 - 15 = 10 kWh. With a charging power of 20 kW, all EV batteries 50 connected to EV charger 40 can be charged with a total of 20 × (15 ÷ 60) = 5 kWh of electricity (chargeable energy) during the 15-minute remaining time Tremain. Because the remaining usable energy is greater than the chargeable energy, the remaining usable energy can also be consumed to charge EV batteries 50. However, during the remaining time Tremain, the facility may consume up to 11 kWh of electricity from the remaining usable energy, so in this case, the power supply and demand management device 20 performs charge and discharge control such that the EV batteries 50 are not charged.

[0049] If the prediction range of the amount of purchased power from the present to the end of the control cycle, (Eothers,predict,lower to (Eothers,predict,upper), is 6 to 8 kWh, even if the amount of power in the prediction range is consumed from the remaining amount of used power, 2 to 4 kWh of power is expected to remain. In this case, the power supply and demand management device 20 performs charge and discharge control to supply a total of 2 to 4 kWh of power for charging the EV battery 50 during the remaining 15-minute time, Tremain. The charging power in this case is (2 to 4) × (60 ÷ 15) = 8 to 16 kW.

[0050] When charging the EV batteries 50 of electric vehicles connected to the EV charger 40 with charging power determined by the power supply and demand management device 20, the charging power for the EV batteries 50 of each electric vehicle can be determined based on the state of charge of the EV batteries 50 of each electric vehicle, for example. The charging power for the EV batteries 50 of each electric vehicle may be determined by the power supply and demand management device 20, or each EV charger 40 may determine the charging power for the EV batteries 50 of the electric vehicle connected to it. Each electric vehicle may determine the charging power for its own EV battery 50 instead of each EV charger 40. Known methods can be used to determine the charging power for the EV batteries 50 of each electric vehicle.

[0051] As shown in Fig. 8, the average value Elimit of the limit value for the amount of power purchased for each control cycle is obtained (step S41). The power supply and demand management device 20 obtains the actual amount of power purchased Eused from the start of the control cycle to the present (step S43), and further obtains a prediction range Eothers,predict,lower to Eothers,predict,upper of the amount of power purchased from the present to the end of the control cycle (step S45). The above is the same as steps S1 to S5 in Fig. 2. The order of steps S41 to S45 may be reversed, or some or all of the steps may be performed simultaneously in parallel.

[0052] The power supply and demand management device 20 determines the total target power of the group of EV batteries 50 (step S47). The group of EV batteries 50 is a collective term for the EV batteries 50 of all electric vehicles in the power supply and demand system 1 that can be connected to the EV charger 40. The power supply and demand management device 20 determines the charge power determined by the charge and discharge control described with reference to Figures 4 to 7 as the total target power of the group of EV batteries 50.

[0053] The power supply and demand management device 20 acquires charging information and usage reservation information for the EV battery 50 for each electric vehicle (step S49). The charging information for the EV battery 50 includes information on the charge state of the EV battery 50. The usage reservation information is information indicating the future usage schedule for each electric vehicle. Using the usage reservation information, the power supply and demand management device 20 can predict, for example, when an electric vehicle is scheduled to be connected to the EV charger 40 and how long an electric vehicle connected to the EV charger 40 is scheduled to be connected to the EV charger 40. When there are multiple EV batteries 50 with low states of charge, the EV batteries 50 of electric vehicles that have been connected to the EV charger 40 for a short time need to be charged with higher charging power and in a shorter time than the EV batteries 50 of electric vehicles that have been connected for a longer time. The power supply and demand management device 20 determines the charging power for the EV battery 50 for each electric vehicle based on the acquired charging information and usage reservation information for the EV battery 50 (step S51).

[0054] By determining the charging power for the EV battery 50 of each electric vehicle based on the usage reservation information, the power supply and demand management device 20 can determine the charging power taking into consideration the presence of electric vehicles that will be connected to or disconnected from the EV charger 40 during charging control. In step S51, the power supply and demand management device 20 may determine the charging power for the EV battery 50 of each electric vehicle based only on the charging information of the EV battery 50, without obtaining the usage reservation information for the EV battery 50. By determining the charging power for the EV battery 50 of each electric vehicle based on the charging information, the power supply and demand management device 20 can determine the charging power taking into consideration the presence of EV batteries 50 that will become fully charged or whose discharge voltage will reach the discharge end voltage during charging control.

[0055] The power supply and demand management device 20 transmits the command value for charging power for the EV battery 50 determined for each electric vehicle to each EV charger 40 (step S53).

[0056] When each EV charger 40 receives the command value for charging power (step S61), it changes the target power for charge / discharge control of the EV battery 50 of the electric vehicle connected to it to the charging power command value corresponding to the EV battery 50 of that electric vehicle (step S63). The command value for charging power transmitted by the power supply and demand management device 20 may be received by the electric vehicle, and a controller (not shown) of the electric vehicle may change the target power for charge / discharge control of the EV battery 50 of the electric vehicle to the charging power of the received command value corresponding to its own EV battery 50. Signals may be transmitted and received between the power supply and demand management device 20 and the electric vehicle wirelessly, for example, or some of the signals may be transmitted wirelessly via the EV charger 40.

[0057] As shown in FIG. 9, when the charge amount of each EV battery 50 is determined by each EV charger 40 or each electric vehicle, the power supply and demand management device 20 performs the processes of steps S41 to S47 in FIG. 18. The power supply and demand management device 20 then acquires the total actual charging power of the EV batteries 50 from the start of the control cycle to the present (step S57). The total actual charging power of the EV batteries 50 is the total power supplied to charge the EV batteries 50 of each electric vehicle in the power supply and demand system 1 from the start of the control cycle to the present. The total actual charging power of the EV batteries 50 can be acquired, for example, based on the amount of power acquired from the power meter 30. The power supply and demand management device 20 creates a charging command index based on the total target power acquired in step S47 and the total actual charging power acquired in step S57, and transmits this to all EV chargers 40 (step S59). The charging command index can be, for example, an index indicating the total power that can be supplied to charge the EV batteries 50 from the present to the end of the control cycle.

[0058] When each EV charger 40 receives the charge command indicator (step S65), it calculates the target charge power for the EV battery 50 based on the received charge command indicator and its own status, which is the status of the EV battery 50 of the electric vehicle connected to it (step S67). The own status of the EV battery 50 may be, for example, a priority β indicating the degree to which charging of its own EV battery 50 is prioritized over charging of the EV batteries 50 of other electric vehicles. The priority β is, for example, held by the electric vehicle that has the EV battery 50 that is the target of the priority β. The EV charger 40 can obtain the priority β of the EV battery 50 from, for example, the electric vehicle connected to it. Each EV charger 40 changes the target power for charge / discharge control of the EV battery 50 of the connected electric vehicle to the target charge power calculated in step S67 (step S69).

[0059] When each electric vehicle determines the charging power for its own EV battery 50 instead of each EV charger 40, each electric vehicle receives the command value or charging command indicator sent by the power supply and demand management device 20. Upon receiving the command value or charging command indicator, the electric vehicle executes the processes corresponding to steps S61 and S63 in Figure 8 or steps S65 to S69 in Figure 9. While connected to the EV charger 40, the electric vehicle receives charging power from the EV charger 40 that is the target power determined by the electric vehicle, and charges its own EV battery 50.

[0060] Charging control in which each EV charger 40 or each electric vehicle determines the charging power for each electric vehicle's EV battery 50 based on a charging command index received from the power supply and demand management device 20 is generally referred to as autonomous control. When performing autonomous-type charging control, the power supply and demand management device 20 may not have a communication function for obtaining the state of charge of the EV battery 50 of each electric vehicle. In this case, the power supply and demand management device 20 cannot calculate the minimum charging output value PEV,ctarget and the maximum charging output value PEV,cmax based on the state of charge of each EV battery 50. When performing autonomous-type charging control, the power supply and demand management device 20, for example, assumes situations corresponding to the minimum charging output value PEV,ctarget and the maximum charging output value PEV,cmax, and assumes a charging command index corresponding to the assumed situation. The power supply and demand management device 20 can perform charging control of this embodiment by regarding the charging power corresponding to the assumed charging command index as the minimum charging output value PEV,ctarget and the maximum charging output value PEV,cmax.

[0061] Following the specific example of charging control of EV battery 50 by power supply and demand management device 20, a specific example of discharging control of EV battery 50 by power supply and demand management device 20 will be described with reference to FIGS.

[0062] The power supply and demand management device 20 controls the discharge of the EV battery 50 when at least a portion of the range of evaluated power is a negative (-) value. The minimum discharge output value PEV,dtarget in Figures 10 to 13 is the discharge output value obtained by adding up, for the EV batteries 50 of the electrically powered vehicles connected to the EV charger 40, the rated output of the power that the EV battery 50 can currently discharge, excluding the capacity required by the EV battery itself. The maximum discharge output value PEV,dmax is the discharge output value obtained by adding up, for the EV batteries 50 of the electrically powered vehicles connected to the EV charger 40, the rated output of all the power that the EV battery 50 can currently discharge, including the capacity required by the EV battery itself. In controlling the discharge of the EV battery 50 using the electrically powered vehicle group power management function, the power supply and demand management device 20 controls the EV battery 50 to discharge when the minimum value PEV,average,lower of the range of evaluated power is a low value that exceeds the minimum discharge output value PEV,dtarget. Through this discharge control, the power supply and demand management device 20 charges the EV batteries 50 of electric vehicles with a low state of charge, while preferentially discharging the EV batteries 50 of electric vehicles with a high state of charge.

[0063] 10 and 11 show a case where the maximum value PEV,average,upper of the range of evaluated power is a positive (+) value. Here, as shown in FIG. 10, a case will be described where the minimum value PEV,average,lower of the range of evaluated power is lower than the maximum discharge output value PEV,dmax. In this case, the power supply and demand management device 20 discharges the EV battery 50 of the electric vehicle connected to the EV charger 40 at the discharge power of the maximum discharge output value PEV,dmax. This discharge reduces the risk that the amount of purchased power will exceed the average limit value Elimit, even if the facility consumes the maximum amount of power in the predicted range during the period from the present to the end of the control cycle.

[0064] Next, we will explain the case where the maximum value PEV,average,upper of the range of evaluated power is a positive value, and the minimum value PEV,average,lower is higher than the maximum discharge output value PEV,dmax and lower than the minimum discharge output value PEV,dtarget. In this case, the power supply and demand management device 20 discharges the EV battery 50 of the electric vehicle connected to the EV charger 40 at the discharge power of the minimum value PEV,average,lower. This discharge makes it possible to make up for the shortfall in the amount of purchased power with the discharge power of the EV battery 50 with a high state of charge, while suppressing discharge from EV batteries 50 with a low state of charge.

[0065] Next, as shown in FIG. 11 , a case will be described in which the minimum value PEV,average,lower of the range of evaluated power is higher than the minimum discharge output value PEV,dtarget but is equal to or less than the minimum discharge output value PEV,dtarget. In this case, the power supply and demand management device 20 will not discharge the EV battery 50 of the electric vehicle connected to the EV charger 40. If the minimum value PEV,average,lower is higher than the minimum discharge output value PEV,dtarget and the maximum value PEV,average,upper is a positive (+) value, depending on the facility's future power consumption, the amount of purchased power under the contract power may be sufficient, making it unnecessary to discharge the EV battery 50. If discharging the EV battery 50 now results in a shortage of purchased power later, and the EV battery 50 is to be charged to bring the amount of purchased power closer to the contract power, this will result in unnecessary discharging and charging of the EV battery 50, which will result in power losses. By not discharging the EV battery 50 when the minimum value PEV,average,lower is higher than the minimum discharge output value PEV,dtarget and the maximum value PEV,average,upper is a positive (+) value, it is possible to suppress losses caused by unnecessary charging and discharging of the EV battery 50.

[0066] FIG. 12 shows a case where the maximum value PEV,average,upper of the range of evaluated power is a negative (-) value higher than the minimum discharge output value PEV,dtarget. Here, as shown in FIG. 12, a case will be described where the minimum value PEV,average,lower of the range of evaluated power is lower than the maximum discharge output value PEV,dmax. In this case, the power supply and demand management device 20 discharges the EV battery 50 of the electric vehicle connected to the EV charger 40 at the discharge power of the maximum discharge output value PEV,dmax. This discharge reduces the risk that the amount of purchased power will exceed the average limit value Elimit, even if the facility consumes the maximum amount of power in the predicted range during the period from the present to the end of the control cycle.

[0067] Next, we will explain the case where the maximum value PEV,average,upper of the range of evaluated power is a negative (-) value higher than the minimum discharge output value PEV,dtarget, and the minimum value PEV,average,lower is a value higher than the maximum discharge output value PEV,dmax and lower than the minimum discharge output value PEV,dtarget. In this case, the power supply and demand management device 20 discharges the EV battery 50 of the electric vehicle connected to the EV charger 40 at the discharge power of the minimum value PEV,average,lower. This discharge makes it possible to make up for the shortfall in the amount of purchased power with the discharge power of EV battery 50 with a high state of charge, while suppressing discharge from EV battery 50 with a low state of charge.

[0068] Next, we will explain the case where the maximum value PEV,average,upper and minimum value PEV,average,lower of the range of evaluated power are negative (-) values higher than the minimum discharge output value PEV,dtarget. In this case, the power supply and demand management device 20 discharges the EV batteries 50 of electric vehicles connected to the EV charger 40 at a discharge power of the maximum value PEV,average,upper, which is lower than the minimum value EV,average,lower. In this discharge, the EV batteries 50 of electric vehicles connected to the EV charger 40 with a higher state of charge are discharged at a slower discharge rate. Even if the facility's power consumption fluctuates within the predicted range, the fluctuation range is not large, so this discharge can reduce the amount of power discharged from the EV batteries 50 to make up for the shortfall in the amount of purchased power.

[0069] FIG. 13 shows a case where the maximum value PEV,average,upper of the range of evaluated power is a negative (-) value lower than the minimum discharge output value PEV,dtarget. Here, as shown in FIG. 13, a case where the minimum value PEV,average,lower of the range of evaluated power is lower than the maximum discharge output value PEV,dmax will be described. In this case, the power supply and demand management device 20 discharges the EV batteries 50 of electric vehicles connected to the EV charger 40 at the discharge power of the maximum discharge output value PEV,dmax. In this discharge, the EV batteries 50 of all electric vehicles connected to the EV charger 40 are discharged at a high discharge rate. This discharge reduces the risk of the amount of purchased energy exceeding the average limit value Elimit, even if the facility consumes the maximum amount of power in the predicted range from the present to the end of the control cycle.

[0070] Next, a case will be described in which the maximum value PEV,average,upper of the range of evaluated power is a negative (-) value lower than the minimum discharge output value PEV,dtarget, and the minimum value PEV,average,lower is a value higher than the maximum discharge output value PEV,dmax. In this case, the power supply and demand management device 20 discharges the EV batteries 50 of electric vehicles connected to the EV charger 40 at the discharge power of the minimum value PEV,average,lower. In this discharge, the EV batteries 50 of electric vehicles connected to the EV charger 40 with a higher state of charge are discharged at a high discharge rate. This discharge resolves the shortage of purchased power with the discharge power of the EV batteries 50, while preventing EV batteries 50 with a lower state of charge from discharging due to the shortage of purchased power.

[0071] In this embodiment, the power supply and demand management device 20 performs charge and discharge control of the EV battery 50 of an electric vehicle included in a group of power consumption elements in the facilities of the power supply and demand system 1 for each control period. The prediction unit 21 of the power supply and demand management device 20 predicts the range of power supply and demand from the start to the end of the control period for the power consumption elements excluding the EV battery 50 of the group. The estimation unit 22 estimates the range of power purchase amount Eused+Eothers,predict,lower to Eused+Eothers,predict,upper by the entire group of power consumption elements of the power supply and demand system 1 from the start to the end of the control period based on the range of power supply and demand predicted by the prediction unit 21. The calculation unit 23 calculates the range of evaluated power amount from the start to the end of the control period. The evaluated power amount indicates the difference between the average value Elimit for each control period of the limit value predetermined for the amount of power purchase by the entire group of power consumption elements of the power supply and demand system 1 and the range of power purchase amount estimated by the estimation unit 22. Charge / discharge control unit 24 stops charging EV battery 50 when the minimum value PEV,average,lower of the range of evaluated power from the start to the end of the control cycle is a negative (-) value. The range of evaluated power from the start to the end of the control cycle is a range whose minimum and maximum values are the minimum and maximum values of the range of evaluated power calculated by calculation unit 23 divided by the remaining time Tremain from the present to the end of the control cycle. By not charging EV battery 50 when the minimum value of the range of evaluated power is negative (-), it is possible to prevent losses due to unnecessary charging and discharging of EV battery 50. This makes it possible to prevent the power demand of facilities that use EV batteries 50 of electric vehicles as storage batteries from exceeding the target power.

[0072] Electricity supply and demand management device 20 controls the charging power of EV battery 50 between the minimum value PEV,average,lower and the maximum value PEV,average,upper of the range of evaluated power, where the minimum value PEV,average,lower of the range of evaluated power is 0 or a positive (+) value. This control prevents the facility's electricity demand from exceeding the target power due to charging of EV battery 50.

[0073] The power supply and demand management device 20 acquires the amount of power actually purchased Eused from the start of a control cycle to the present from the power meter 10. The power supply and demand management device 20 calculates the range of the predicted amount of power purchased from the present to the end of the control cycle, Eothers, predict, lower to Eothers, predict, upper, based on the range of power supply and demand predicted by the prediction unit 21. The power supply and demand management device 20 adds the predicted range of the amount of power purchased, Eothers, predict, lower to Eothers, predict, upper, to the actual amount of power purchased Eused to estimate the range of the amount of power purchased from the start to the end of the control cycle. By estimating the range of the amount of power purchased from the start to the end of the control cycle using the amount of power actually purchased Eused instead of the predicted value from the start to the present, the accuracy of estimating the range of the amount of power purchased can be improved.

[0074] When the maximum value PEV,average,upper of the range of evaluated power is greater than the maximum charging output value PEV,cmax, power supply and demand management device 20 controls the charging power of EV battery 50 to the maximum charging output value PEV,cmax. This control enables the contracted power amount to be used effectively to charge EV battery 50 and be consumed efficiently before the facility reaches a point where it cannot consume all of the contracted power amount.

[0075] When the minimum value PEV,average,lower of the range of evaluated power is greater than the minimum charging output value PEV,ctarget, power supply and demand management device 20 controls the charging power of EV battery 50 to a value greater than the minimum charging output value PEV,ctarget. This control allows the contracted power amount to be effectively used for charging EV battery 50, and consumed efficiently.

[0076] When the minimum value PEV,average,lower of the range of evaluated power is equal to or less than the minimum charging output value PEV,ctarget, the power supply and demand management device 20 controls the charging power of the EV battery 50 to the minimum charging output value PEV,ctarget. This control ensures that an EV battery 50 with a low state of charge can be reliably charged by continuing to charge the minimum EV battery 50 at a low rate for a long period of time, even if there is a possibility that the amount of power available for charging the EV battery 50 will decrease in the future. This control also ensures that there is more room for adjusting the amount of charging of the EV battery 50 during the period from the present to the end of the control cycle, so that the amount of purchased power is equal to or less than the average limit value Elimit and the average purchased power for the control cycle is within the contracted power.

[0077] When the minimum value PEV,average,lower of the range of evaluated power is greater than the minimum charging output value PEV,ctarget, the power supply and demand management device 20 controls the charging power of the EV battery 50 to a value closer to the minimum value PEV,average,lower as the minimum value decreases and approaches the minimum charging output value. This control ensures that an EV battery 50 with a low state of charge can be charged even if the power available for charging is reduced. When the minimum value PEV,average,lower of the range of evaluated power is greater than the minimum charging output value PEV,ctarget, the power supply and demand management device 20 controls the charging power of the EV battery 50 to a value closer to the maximum value PEV,average,upper as the minimum value increases and moves away from the minimum charging output value. This control allows the contracted power amount to be effectively used for charging the EV battery 50, allowing for efficient consumption.

[0078] When the maximum value PEV,average,upper of the range of evaluated power is equal to or less than the maximum charging output value PEV,cmax, the power supply and demand management device 20 controls the charging power of the EV battery 50 to a value closer to the maximum value PEV,average,upper as the maximum value increases and approaches the maximum charging output value. This control allows the contracted power amount to be used effectively for charging the EV battery 50, thereby ensuring efficient consumption. When the maximum value PEV,average,upper of the range of evaluated power is equal to or less than the maximum charging output value PEV,cmax, the power supply and demand management device 20 controls the charging power of the EV battery 50 to a value closer to the minimum value PEV,average,lower as the maximum value decreases and moves away from the maximum charging output value. This control prevents the EV battery 50 from discharging after charging, resulting in unnecessary loss.

[0079] The power supply and demand management device 20 calculates a maximum difference value, which is the difference between the maximum charging output value PEV,cmax and the maximum value PEV,average,upper, and calculates a minimum difference value, which is the difference between the minimum value PEV,average,lower and the minimum charging output value PEV,ctarget. The power supply and demand management device 20 controls the charging power of the EV battery 50 to a value at a point obtained by proportionally dividing the range of evaluated power using the ratio between the absolute value of the maximum difference value and the absolute value of the minimum difference value. This control makes effective use of the contracted power amount by charging the EV battery 50, reliably charges an EV battery 50 with a low state of charge, and achieves appropriate charging control that prevents unnecessary loss due to discharging of the EV battery 50 after charging.

[0080] When the minimum value PEV,average,lower of the range of evaluated power is a low value that exceeds the minimum discharge output value PEV,dtarget, the power supply and demand management device 20 controls the EV battery 50 to discharge. This control reduces the risk that the amount of purchased power will exceed the average limit value Elimit, even if the facility consumes the maximum amount of power in the predicted range during the period from the present to the end of the control cycle.

[0081] When the minimum value PEV,average,lower of the range of evaluated power is higher than the minimum discharge output value PEV,dtarget but is equal to or less than the minimum discharge output value PEV,dtarget, power supply and demand management device 20 performs control to stop discharging of EV battery 50. This control can prevent unnecessary loss by charging EV battery 50 after discharging.

[0082] In this embodiment, a case has been described in which the charge / discharge control method of the present invention is applied to the EV battery 50 of an electric vehicle. For example, if the electricity supply and demand system 1 has a stationary storage battery that stores electricity as a charge / discharge element, the charge / discharge control method of the present invention may be applied to charge / discharge control of the storage battery.

[0083] The above-described embodiment is an example of the present invention, and therefore 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]

[0084] 1. Electricity supply and demand system 20 Power supply and demand management device (charge and discharge control device) 21 Prediction Department 22 Estimation part 23 Calculation section 24 Charge / discharge control unit 40 EV charger (power consumption elements, charging / discharging equipment) 50 EV battery (power consumption element) 70 Load (power consumption element) 80 Renewable energy power generation facilities (electricity consumption elements)

Claims

1. A charge / discharge control method performed for each control period of a charge / discharge element included in a group of power consumption elements, comprising: predicting a range of power supply and demand from the start to the end of a control period of the power consumption elements excluding the charging and discharging elements of the group; estimating a range of the amount of purchased power from the start to the end of a control period based on the predicted range of the amount of power supply and demand; calculating a range of an evaluated amount of power from the start to the end of a control period, the range indicating a difference between an average value of a predetermined limit value for each control period regarding the amount of power purchased by the entire group and the range of the estimated amount of power purchased; When the minimum value of the range of the evaluation power indicating the range of the magnitude of the power corresponding to the calculated range of the evaluation power amount is a negative (−) value, charging of the charging / discharging element is stopped. A method for controlling charging and discharging of a charging and discharging element.

2. 2. A method for controlling charging and discharging of a charging and discharging element as described in claim 1, wherein when the minimum value of the range of the evaluation power is 0 or a positive (+) value, the charging power of the charging and discharging element is controlled to be between the minimum value and the maximum value of the range of the evaluation power.

3. Acquire the actual amount of purchased power from the start of the control period to the present for the entire group; Calculating a range of a predicted amount of purchased power from the present to the end of the control period based on the predicted range of power supply and demand; adding the acquired actual purchased amount of power to the calculated range of the predicted purchased amount of power, thereby estimating the range of the purchased amount of power from the start to the end of a control period; The method for controlling charging and discharging of a charging and discharging element according to claim 1 .

4. 2. The method for controlling charging and discharging of a charging and discharging element according to claim 1, wherein the charging and discharging element is a battery of at least one electric vehicle connected to charging and discharging equipment of a facility, and when a maximum value of the range of the rated power is greater than a maximum charging output value required to charge the batteries of a maximum number of the electric vehicles connected to the charging and discharging equipment, the charging power of the charging and discharging element is controlled to the maximum charging output value.

5. 2. The method for controlling charging and discharging of a charging and discharging element according to claim 1, wherein the charging and discharging element is a battery of at least one electric vehicle connected to charging and discharging equipment of a facility, and when a minimum value of the range of the rated power is greater than a minimum charging output value required to charge a minimum number of batteries to be charged among the batteries of the electric vehicles connected to the charging and discharging equipment, the charging power of the charging and discharging element is controlled to a value greater than the minimum charging output value, and when the minimum value of the range of the rated power is equal to or less than the minimum charging output value, the charging power of the charging and discharging element is controlled to the minimum value of the range of the rated power.

6. 6. A method for controlling charging and discharging of a charging and discharging element as described in claim 5, wherein, when the minimum value of the range of the evaluation power is greater than the minimum charging output value, the charging power of the charging and discharging element is controlled to a value closer to the minimum value of the range of the evaluation power as the minimum value decreases and approaches the minimum charging output value, and the charging power of the charging and discharging element is controlled to a value closer to the maximum value of the range of the evaluation power as the minimum value increases and moves away from the minimum charging output value.

7. 2. The method for controlling charging and discharging of a charging and discharging element according to claim 1, wherein the charging and discharging element is a battery of at least one electric vehicle connected to charging and discharging equipment of a facility, and when a maximum value of the range of rated power is equal to or less than a maximum charging output value required to charge the batteries of a maximum number of the electric vehicles connected to the charging and discharging equipment, the charging power of the charging and discharging element is controlled to a value closer to the maximum value of the range of rated power as the maximum value increases and approaches the maximum charging output value, and the charging power of the charging and discharging element is controlled to a value closer to the minimum value of the range of rated power as the maximum value decreases and departs from the maximum charging output value.

8. 8. The method for controlling charging and discharging of a charging and discharging element according to claim 6 or 7, further comprising: calculating a maximum difference value that is the difference between a maximum charging output value required to charge the batteries of a maximum number of the electric vehicles connected to the charging and discharging equipment and the maximum value; calculating a minimum difference value that is the difference between a minimum charging output value required to charge a minimum number of batteries of the electric vehicles connected to the charging and discharging equipment to be charged and the minimum value of the range of the evaluated power; and controlling the charging power of the charging and discharging element to a value at a point obtained by proportionally dividing the range of the evaluated power in accordance with a ratio between the absolute value of the maximum difference value and the absolute value of the minimum difference value within the range of the evaluated power.

9. 2. The method for controlling charging and discharging of a charging and discharging element according to claim 1, wherein the charging and discharging element is a battery of at least one electric vehicle connected to charging and discharging equipment of a facility, and the charging and discharging element is caused to discharge when the minimum value of the range of the evaluated power is a discharge power value that exceeds a minimum discharge output value that is a total rated power of batteries in a dischargeable charged state among the batteries of the electric vehicles connected to the charging and discharging equipment.

10. The method for controlling charging and discharging of a charging and discharging element according to claim 9 , wherein discharging of the charging and discharging element is stopped when the minimum value is a discharge power value equal to or less than the minimum discharge output value.

11. A charge / discharge control device that is performed at each control period of charge / discharge elements included in a group of power consumption elements, a prediction unit that predicts a range of power supply and demand from the start to the end of a control period of the power consumption elements excluding the charging and discharging elements of the group; an estimation unit that estimates a range of the amount of purchased power from the start to the end of a control period based on the predicted range of the amount of power supply and demand; a calculation unit that calculates a range of an evaluated amount of power from the start to the end of a control period, the range indicating a difference between an average value of a predetermined limit value for each control period regarding the amount of purchased power of the entire group and the range of the estimated amount of purchased power; a charge / discharge control unit that stops charging of the charge / discharge element when a minimum value of an evaluation power range indicating a range of power magnitude corresponding to the calculated range of the evaluation power amount is a negative (−) value; A charge / discharge control device for a charge / discharge element comprising:

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