A method for controlling the charging and discharging of a charging / discharging element, and a control device for charging and discharging of a charging / discharging element.

Abstract

To simultaneously achieve a target of a plurality of control modes by switching the plurality of control modes at appropriate timing.SOLUTION: In a power system 100 for supplying power from a power system 10 and renewable power generated by renewable energy to a load 5 consuming power and a plurality of charge / discharge elements EV1 and EV2, a charge / discharge control method for a charge / discharge element switches a peak cut mode and a renewable-energy utilizing mode. In the peak cut mode, charge / discharge power of the charge / discharge elements EV1 and EV2 is controlled so thar purchased power becomes contracted power by comparing power purchased from the power system 10 with contract power contracted to be purchased from the power system 10. In the renewable-energy utilizing mode, the charge / discharge elements EV1 and EV2 are charged by the renewable energy.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for controlling charge and discharge of a charge and discharge element, and an apparatus for controlling charge and discharge of a charge and discharge element.

Background Art

[0002] Patent Document 1 describes a photovoltaic power generation system including a plurality of solar cells and a plurality of power conditioners, and managing the plurality of power conditioners with a centralized management device. In such a photovoltaic power generation system, there are a plurality of control modes for achieving respective objectives, such as peak cut control for suppressing the peak value of purchased power supplied from the power grid, and renewable energy utilization control for charging a storage battery with power generated by solar cells.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional photovoltaic power generation system described above, switching between a plurality of control modes had to be performed manually by an operator. Therefore, there was a problem that the switching between a plurality of control modes could not be performed at an appropriate timing, and thus the objectives of the plurality of control modes could not be achieved simultaneously.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for controlling charge and discharge of a charge and discharge element and an apparatus thereof that can switch between a plurality of control modes at an appropriate timing and simultaneously achieve the objectives of the plurality of control modes.

Means for Solving the Problems

[0006] To solve the above-mentioned problems, a charge / discharge control method and apparatus for a charge / discharge element according to one aspect of the present invention compares the purchased electricity from the power grid with the contracted electricity to be purchased from the power grid. Based on the result of this comparison, the method switches between a peak-cut mode, which controls the charge / discharge power of the charge / discharge element so that the purchased electricity becomes the contracted electricity, and a renewable energy utilization mode, which charges the charge / discharge element with renewable energy. A control command value for contracted power is set so that the amount of purchased power consumed is equal to the amount of contracted power consumed over a predetermined period of time. A control command value for renewable power is also set so that the charging and discharging power is renewable power. The smaller of the two control command values ​​is selected as the control command value for controlling the charging and discharging power. [Effects of the Invention]

[0007] According to the present invention, it is possible to switch between multiple control modes at appropriate timings to simultaneously achieve the goals of multiple control modes. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a block diagram showing the configuration of a power system equipped with a charge / discharge control device according to the first embodiment. [Figure 2] Figure 2 shows the relationships between each power source in the power system shown in Figure 1. [Figure 3] Figure 3 is a flowchart showing the processing procedure for charge / discharge control by the charge / discharge control device according to the first embodiment. [Figure 4] Figure 4 is a flowchart showing the processing steps for charging and discharging electric vehicles. [Figure 5] Figure 5 shows an example of how each power level changes in the power system shown in Figure 1. [Figure 6] Figure 6 shows an example of the relationship between purchased electricity and contracted electricity. [Figure 7] Figure 7 shows an example of the changes in each power in the power system according to the first embodiment. [Figure 8] Figure 8 shows an example of the relationship between purchased electricity and contracted electricity in the power system according to the first embodiment. [Figure 9] Figure 9 shows an example of the relationship between renewable power and charging / discharging power in a power system according to the first embodiment. [Figure 10] FIG. 10 is a diagram showing an example of a control command value in the power system according to the first embodiment. [Figure 11] FIG. 11 is a diagram showing an example of changes in each power in the power system according to the second embodiment. [Figure 12] FIG. 12 is a diagram showing an example of the relationship between the purchased power and the contract power in the power system according to the second embodiment. [Figure 13] FIG. 13 is a diagram showing an example of the relationship between the renewable power and the charge / discharge power in the power system according to the second embodiment. [Figure 14] FIG. 14 is a diagram showing an example of a control command value in the power system according to the second embodiment. [Figure 15] FIG. 15 is a diagram showing an example of changes in each power in the power system according to the third embodiment. [Figure 16] FIG. 16 is a diagram showing an example of the relationship between the purchased power and the contract power in the power system according to the third embodiment. [Figure 17] FIG. 17 is a diagram showing an example of the relationship between the renewable power and the charge / discharge power in the power system according to the third embodiment. [Figure 18] FIG. 18 is a diagram showing an example of a control command value in the power system according to the third embodiment. [Figure 19] FIG. 19 is a diagram showing an example of changes in each power in the power system according to the fourth embodiment. [Figure 20] FIG. 20 is a diagram showing an example of the relationship between the purchased power and the contract power in the power system according to the fourth embodiment. [Figure 21] FIG. 21 is a diagram showing an example of the relationship between the renewable power and the charge / discharge power in the power system according to the fourth embodiment. [Figure 22] FIG. 22 is a diagram showing an example of a control command value in the power system according to the fourth embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0009] [First Embodiment] Hereinafter, a first embodiment to which the present invention is applied will be described with reference to the drawings. In the description of the drawings, the same parts are denoted by the same reference numerals and detailed description thereof will be omitted.

[0010] [Configuration of Power System] FIG. 1 is a block diagram showing the configuration of a power system including a charge / discharge control device according to the present embodiment. As shown in FIG. 1, the power system 100 includes a control server 1, a power grid 10, power receiving / supplying devices 3A and 3B, electric vehicles EV1 and EV2, a load 5, and a renewable energy supply facility 7. The power system 100 is a system that supplies power from the power grid 10 and renewable power generated from renewable energy to the load 5 that consumes power and the electric vehicles EV1 and EV2.

[0011] The power grid 10 is a power system that can control the flow of power from both the supply side and the demand side and optimize it. The power grid includes concepts such as smart grid, smart community, and microgrid or MEMS (Mansion Energy Management System) that manages the range from the energy supply source to the consumption part through a communication network within a limited range such as a business office or a factory. The power grid 10 includes a power network 11, electric wires 12, a transformer 14, and current measuring devices 15A and 15B shown in FIG. 1.

[0012] The power network 11 includes various power generation plants such as thermal power plants, nuclear power plants, and hydroelectric power plants, and substations that transform the voltage from several hundred thousand volts (V) to several thousand volts. The electric wire 12 is connected to the power network 11 via the current measuring device 15A and the transformer 14. Also, the electric wire 12 is connected to the power receiving / supplying devices 3A and 3B via the current measuring device 15B and is connected to the load 5 and the renewable energy supply facility 7. As an example of the transformer 14, a pole transformer (pole transformer) that changes the voltage applied to a high-voltage distribution line to a voltage used in a home or an office can be mentioned.

[0013] Current measuring devices 15A and 15B measure the current flowing through the power line 12 and calculate the power supplied via the power line 12 based on the measured current and the voltage of the power line 12. For example, current measuring device 15A calculates the purchased power from the power grid 10, and current measuring device 15B calculates the charge / discharge power being used to charge or discharge electric vehicles EV1 and EV2. This calculated power is transmitted to the control server 1.

[0014] Control Server 1 is a server that supplies power from the power grid 10 and renewable power to the load 5 and electric vehicles EV1 and EV2, and controls the charging and discharging of electric vehicles EV1 and EV2. Control Server 1 communicates with current measuring devices 15A and 15B to obtain purchased power and the charging and discharging power of electric vehicles EV1 and EV2. Control Server 1 also communicates with electric vehicles EV1 and EV2 to control the charging and discharging of electric vehicles EV1 and EV2. As shown in Figure 1, Control Server 1 is equipped with a charge / discharge control device 21, a broadcast transmission unit 23a, and a broadcast transmission device 23b.

[0015] The charge / discharge control device 21 controls the charging and discharging of electric vehicles EV1 and EV2. Specifically, the charge / discharge control device 21 switches between peak cut mode and renewable energy utilization mode by comparing the purchased electricity from the power grid 10 with the contracted electricity to be purchased from the power grid 10. Peak cut mode is a mode in which the charging and discharging power of electric vehicles EV1 and EV2 is controlled so that the purchased electricity becomes the contracted electricity. Renewable energy utilization mode is a mode in which electric vehicles EV1 and EV2 are charged with renewable electricity generated from renewable energy sources.

[0016] The charge / discharge control device 21 is a controller composed of a general-purpose electronic circuit including a microcomputer, microprocessor, and CPU, and peripheral devices such as memory. The charge / discharge control device 21 has a computer program installed for performing charge / discharge control processing. Each function of the charge / discharge control device 21 can be implemented by one or more processing circuits. The processing circuits include, for example, programmed processing devices including electrical circuits, and may also include devices such as application-specific integrated circuits (ASICs) or conventional circuit components arranged to perform the functions described in the embodiments.

[0017] The broadcast transmission unit 23a uses the broadcast transmission device 23b to broadcast the control signals generated by the charge / discharge control device 21 to all electric vehicles EV1 and EV2. For broadcast transmission, a wireless LAN (Local Area Network) such as Wi-Fi (registered trademark) or Bluetooth (registered trademark) can be used.

[0018] The power receiving devices 3A and 3B are pole-mounted or wall-mounted transformers connected to the power lines 12, and they supply power to and receive power from electric vehicles EV1 and EV2 to the power grid 11.

[0019] Load 5 refers to facilities such as buildings within businesses and factories that consume electricity. Load 5 is supplied with the necessary electricity as demand power.

[0020] The renewable energy supply equipment 7 is equipment for supplying renewable electricity generated from renewable energy sources, and is, for example, a solar power generation system equipped with solar panels. The renewable energy supply equipment 7 supplies renewable electricity to load 5 and electric vehicles EV1 and EV2. However, it is not limited to solar power generation; other power generation methods may be used as long as they are renewable energy sources.

[0021] The electric vehicles EV1 and EV2 are electrically connected to the power grid 11 via power receiving and supply devices 3A and 3B, and can receive power from the power grid 11 (charge) and transmit power to the power grid 11 (discharge). The electric vehicles EV1 and EV2 autonomously control the charging and discharging power according to the control command values ​​generated by the charge / discharge control device 21. Note that the number of electric vehicles is not limited to the two shown in Figure 1. The electric vehicles EV1 and EV2 are equipped with charge / discharge units 25A and 25B, respectively.

[0022] The charge / discharge units 25A and 25B determine the charge / discharge power for electric vehicles EV1 and EV2, respectively, and perform the charge / discharge. At this time, the charge / discharge units 25A and 25B receive electrical signals transmitted from the control server 1, determine the charge / discharge power based on the control command values ​​contained in the electrical signals, and perform the charge / discharge of electric vehicles EV1 and EV2.

[0023] In this embodiment, "electric vehicles EV1, EV2" are examples of "charge / discharge elements" that charge and discharge power via the power lines 12. The charge / discharge elements store the received power in a battery (including secondary batteries, storage batteries, and rechargeable batteries). "Charge / discharge elements" include all equipment and devices equipped with batteries, such as vehicles (including electric vehicles, hybrid vehicles, construction machinery, and agricultural machinery), railway vehicles, play equipment, tools, household products, and daily necessities. In this embodiment, an electric vehicle (EV) that runs using electricity as an energy source and a motor as a power source is given as an example of a charge / discharge element. However, the present invention is not intended to limit the charge / discharge elements to electric vehicles (EVs).

[0024] The term "charge / discharge element" indicates a unit configuration for charge / discharge control by the charge / discharge control device 21 according to the embodiment. That is, charge / discharge control according to the embodiment is performed using the charge / discharge element as a unit. For example, charge / discharge control is performed independently and in parallel for each of the multiple electric vehicles EV1 and EV2.

[0025] Next, with reference to Figure 2, the relationship between the power supplied and consumed in the power system 100 will be explained. As shown in Figure 2, the power system 100 is supplied with purchased electricity from the power grid 10 and renewable electricity generated by the renewable energy supply equipment 7. On the other hand, electric vehicles EV1 and EV2 are charged or discharged by charge / discharge power, and the power consumed by the load 5 is supplied as demand power. Therefore, in the power system 100, the power supplied is the sum of purchased electricity and renewable electricity, and the power consumed is the sum of charge / discharge power and demand power.

[0026] [Charge / Discharge Control Processing] Next, the charge / discharge control process performed by the control server 1 according to this embodiment will be described. Figure 3 is a flowchart showing the processing procedure of the charge / discharge control process.

[0027] As shown in Figure 3, in step S101, the charge / discharge control device 21 acquires power information. Specifically, the charge / discharge control device 21 acquires purchased electricity and the charge / discharge power of electric vehicles EV1 and EV2 from current measuring devices 15A and 15B, and acquires the demand power of load 5 and the renewable power of renewable energy supply equipment 7 via communication means such as a computer network.

[0028] In step S103, the charge / discharge control device 21 sets a target power based on the power information acquired in step S101. For example, if the system is set to peak cut mode after comparing purchased power with contracted power, the contracted power is set as the target power. If the system is set to renewable energy utilization mode, renewable power is set as the target power.

[0029] In step S105, the charge / discharge control device 21 sets control command values ​​for controlling the charge and discharge power of the electric vehicles EV1 and EV2. Details on how to set the control command values ​​will be described later.

[0030] In step S107, the charge / discharge control device 21 calculates power state information. For example, it calculates the charge / discharge power required for electric vehicles EV1 and EV2 based on the control command value set in step S105.

[0031] In step S109, the broadcast transmission unit 23a uses the broadcast transmission device 23b to broadcast an electrical signal (wireless signal) containing information such as control command values ​​and power status information to all electric vehicles EV1 and EV2.

[0032] In step S111, the charge / discharge control device 21 determines whether the charging and discharging of the electric vehicles EV1 and EV2 has been completed. If it has not been completed, it returns to step S101. If it has been completed, it terminates the charge / discharge control process according to this embodiment.

[0033] [Charging and discharging process] Next, we will explain the charging and discharging process performed in electric vehicles EV1 and EV2. Figure 4 is a flowchart showing the processing steps for the charging and discharging process.

[0034] As shown in Figure 4, in step S201, the charge / discharge units 25A and 25B receive electrical signals (wireless signals) broadcast from the broadcast transmission device 23b to the electric vehicles EV1 and EV2. The electrical signals include information such as power status information and control command values.

[0035] In step S203, the charging and discharging units 25A and 25B acquire the vehicle status of the electric vehicles EV1 and EV2, respectively. The vehicle status acquired includes, for example, the current charge level, the target charge level, and the end time of charging and discharging.

[0036] In step S205, the charge / discharge units 25A and 25B determine the charge / discharge power based on the current vehicle status of the electric vehicles EV1 and EV2, respectively. At this time, the charge / discharge units 25A and 25B determine the charge / discharge power according to the control command value set by the charge / discharge control device 21.

[0037] In step S207, the charging and discharging units 25A and 25B change their charging and discharging power respectively as the demand power and purchased power change and the peak cut mode and renewable energy utilization mode are switched.

[0038] In step S209, the charge / discharge units 25A and 25B determine whether the charging and discharging of the electric vehicles EV1 and EV2 has been completed, respectively. If it has not been completed, the process returns to step S201. If it has been completed, the charge / discharge process according to this embodiment is terminated.

[0039] [How to set control command values] Next, the method for setting the control command value by the charge / discharge control device 21 according to this embodiment will be described. In order to explain the method for setting the control command value, specific examples of demand power and purchased power will be described first. Figure 5 is a diagram showing an example of the demand power of the power system 100, and Figure 6 is a diagram showing an example of the purchased power of the power system 100.

[0040] As shown in Figure 5, the demand power Pa fluctuates, for example, and sometimes exceeds the contracted power Pb. The contracted power Pb is the power that is contracted to be purchased from the power grid 10 to be consumed by the power system 100. In the example in Figure 5, the renewable power Pc is a constant value.

[0041] Furthermore, as shown in Figure 6, purchased electricity Pd is calculated by subtracting renewable electricity Pc from demand electricity Pa, and like changes in demand electricity Pa, it fluctuates up and down, sometimes exceeding the contracted electricity Pb.

[0042] Next, we will explain how to set the control command values ​​by the charge / discharge control device 21 when the demand power and purchased power change as shown in Figures 5 and 6, referring to Figures 7 to 10. Figure 7 is a diagram showing an example of changes in each power in the power system 100. Figure 8 is a diagram showing an example of the relationship between purchased power and contracted power in the power system 100. Figure 9 is a diagram showing an example of the relationship between renewable power and charge / discharge power in the power system 100. Figure 10 is a diagram showing an example of the control command values ​​in the power system 100.

[0043] In this embodiment, the charge / discharge control device 21 is set to peak cut mode when the purchased power is greater than the contracted power, and a control command value is set so that the purchased power becomes the contracted power. Peak cut mode is a mode in which the charge / discharge power of electric vehicles EV1 and EV2 is controlled so that the purchased power becomes the contracted power, and the purchased power is controlled by setting the contracted power to the target power.

[0044] On the other hand, the charge / discharge control device 21 sets to renewable energy utilization mode when the purchased electricity is less than or equal to the contracted power, and sets control command values ​​so that the charge / discharge power becomes renewable power. The renewable energy utilization mode is a mode in which electric vehicles EV1 and EV2 are charged with renewable power, and the charge / discharge power is controlled by setting renewable power as the target power.

[0045] First, at time t0, as shown in Figure 8, the purchased power Pd is less than or equal to the contracted power Pb, so the system is set to renewable energy utilization mode, and the control command value S increases as shown in Figure 10, which causes the charging and discharging power Pe to increase so that it becomes renewable power Pc, as shown in Figure 9.

[0046] Subsequently, as shown in Figure 7, the demand power Pa increases, so at time t1, as shown in Figure 8, the purchased power Pd becomes greater than the contracted power Pb. Therefore, the charge / discharge control device 21 is set to peak cut mode and the control command value S is reduced so that the purchased power Pd becomes the contracted power Pb (Figure 10), and as a result the charge / discharge power Pe decreases as shown in Figure 9. After that, the charge / discharge power Pe becomes negative, and electric vehicles EV1 and EV2 discharge.

[0047] As shown in Figure 8, even at time t2, the purchased power Pd is greater than the contracted power Pb, so the control command value S decreases as shown in Figure 10. However, since there is no power available to discharge to the electric vehicles EV1 and EV2, the charge / discharge power Pe cannot decrease as shown in Figure 9. Therefore, as shown in Figure 8, the purchased power Pd increases after time t2.

[0048] At time t3, as shown in Figure 7, the demand power Pa began to decrease, and as shown in Figure 8, the purchased power Pd also decreased, and at time t4, the purchased power Pd became less than or equal to the contracted power Pb. Therefore, the system switched from peak cut mode to renewable energy utilization mode, and the target power was set to renewable power Pc, so the control command value S was set so that the charging / discharging power Pe increased to renewable power Pc.

[0049] At time t4, electric vehicles EV1 and EV2 are discharging, so as shown in Figure 9, the charge / discharge power Pe is negative, and there is a large difference between it and the renewable power Pc. Therefore, the control command value S becomes a command value that significantly increases the charge / discharge power Pe. However, as the control command value S increases and the charge / discharge power Pe increases, immediately afterward the purchased power Pd exceeds the contracted power Pb (Figure 8), so the system switches back to peak cut mode. As a result, the control command value S decreases again, and the charge / discharge power Pe also decreases. In this way, from time t4 onward, the system repeatedly switches between peak cut mode and renewable energy utilization mode, so as shown in Figures 9 and 10, the control command value S and the charge / discharge power Pe increase while repeatedly rising and falling in small increments.

[0050] Then, at time t5, the demand power Pa shown in Figure 7 decreases sufficiently, so the purchased power Pd stably falls below the contracted power Pb, as shown in Figure 8, and the system is set to renewable energy utilization mode. As a result, the control command value S is set so that the charging / discharging power Pe becomes renewable power Pc, as shown in Figure 10.

[0051] Subsequently, at time t6, as shown in Figure 8, the purchased power Pd becomes greater than the contracted power Pb again, so the system is set to peak cut mode. Therefore, the control command value S decreases so that the purchased power Pd decreases to the contracted power Pb (Figure 10), and as a result, the charge / discharge power Pe also decreases (Figure 9). In this way, the charge / discharge control device 21 switches between peak cut mode and renewable energy utilization mode and sets the control command value in accordance with the change in purchased power.

[0052] [Effects of the First Embodiment] As described in detail above, the charge / discharge control device 21 according to this embodiment switches between peak cut mode and renewable energy utilization mode by comparing purchased power Pd and contracted power Pb. This makes it possible to switch between multiple control modes at appropriate timings and simultaneously achieve the targets of multiple control modes. In other words, it is possible to switch between peak cut mode and renewable energy utilization mode at appropriate timings and control the system to meet the contracted power target of peak cut mode. Furthermore, it is also possible to charge the system to meet the renewable power target of renewable energy utilization mode.

[0053] Furthermore, in the charge / discharge control device 21 according to this embodiment, when the purchased power Pd is greater than the contracted power Pb, the device is set to peak cut mode and the control command value S is set so that the purchased power Pd becomes the contracted power Pb. On the other hand, when the purchased power Pd is less than or equal to the contracted power Pb, the device is set to renewable energy utilization mode and the control command value S is set so that the charge / discharge power Pe becomes the renewable power Pc. This allows the device to control the purchased power so that it does not exceed the contracted power, and also allows the electric vehicle to be charged with renewable power.

[0054] [Second Embodiment] A second embodiment to which the present invention is applied will be described below with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals, and detailed descriptions are omitted. The power system 100 according to this embodiment is the same as the configuration of the first embodiment shown in Figure 1.

[0055] In this embodiment, the method for setting the control command value differs from that of the first embodiment. When the difference between contracted power and purchased power is smaller than the difference between renewable power and charge / discharge power, the system is set to peak cut mode, and the control command value is set so that purchased power becomes contracted power. On the other hand, when the difference between contracted power and purchased power is greater than or equal to the difference between renewable power and charge / discharge power, the system is set to renewable energy utilization mode, and the control command value is set so that charge / discharge power becomes renewable power.

[0056] In the first embodiment, at time t4 in Figures 7-10, the purchased power Pd falls below the contracted power Pb, so the system switches to renewable energy utilization mode. However, as shown in Figure 9, there is a large difference between the charging / discharging power Pe and the renewable power Pc. Therefore, if the control command value S is set to raise the charging / discharging power Pe to the renewable power Pc, the charging / discharging power Pe will rise significantly. After that, the system repeatedly switches between peak cut mode and renewable energy utilization mode, so the control command value S and the charging / discharging power Pe will rise and fall in small increments, as shown in Figures 9 and 10.

[0057] On the other hand, in this embodiment, at time t4 in Figures 11-14, the difference between contracted power Pb and purchased power Pd (Figure 12) is smaller than the difference between renewable power Pc and charge / discharge power Pe (Figure 13). Therefore, the system does not switch to renewable energy utilization mode and remains in peak cut mode, so the control command value S is set so that purchased power Pd becomes contracted power Pb.

[0058] As a result, as shown in Figure 14, the control command value S does not suddenly rise sharply at time t4, and after time t4, the control command value S and the charge / discharge power Pe do not repeatedly rise and fall in small increments (Figures 13 and 14). Therefore, in this embodiment, after time t4, the control command value S and the charge / discharge power Pe can be increased stably, as shown in Figures 13 and 14.

[0059] Later, at time t5, the difference between the contracted power Pb and the purchased power Pd (Figure 12) becomes greater than or equal to the difference between the renewable power Pc and the charging / discharging power Pe (Figure 13). As a result, the system switches to the renewable energy utilization mode, and the control command value S is set so that the charging / discharging power Pe becomes renewable power Pc. In this way, the charging / discharging control device 21 switches to the mode with the smaller difference from the target power and sets the control command value.

[0060] [Effects of the second embodiment] As described in detail above, the charge / discharge control device 21 according to this embodiment is set to peak cut mode when the difference between contracted power and purchased power is smaller than the difference between renewable power and charge / discharge power, and the control command value is set so that purchased power becomes contracted power. On the other hand, when the difference between contracted power and purchased power is greater than or equal to the difference between renewable power and charge / discharge power, it is set to renewable energy utilization mode, and the control command value is set so that charge / discharge power becomes renewable power. As a result, the mode with the smaller difference from the target power can be selected and set, so that the control command value does not change significantly even when the mode is switched, and the charge / discharge power can be stabilized.

[0061] [Third Embodiment] A third embodiment to which the present invention is applied will be described below with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals, and detailed descriptions are omitted. The power system 100 according to this embodiment is the same as the configuration of the first embodiment shown in Figure 1.

[0062] In this embodiment, the method for setting the control command value differs from that of the first and second embodiments. A control command value for contracted power and a control command value for renewable power are set, and the smaller of these two control command values ​​is selected and used.

[0063] In the first and second embodiments, it was determined at each point in time whether the purchased power exceeded the contracted power. However, in actual power systems, the determination of whether the purchased power exceeds the contracted power is not based on whether the purchased power exceeds the contracted power instantaneously, but rather on whether the cumulative amount of energy over a predetermined period of time exceeds the contracted power. Therefore, even if the purchased power instantaneously exceeds the contracted power, there may still be a margin in the amount of energy consumed over a predetermined period of time, and it may not be fully utilized. Conversely, even if the purchased power instantaneously falls below the contracted power, the amount of energy consumed may still exceed the contracted power, and in this case, there is a risk of increasing the charging and discharging power despite exceeding the amount of energy consumed.

[0064] Therefore, in this embodiment, a control command value for contracted power is prepared, which is set so that the amount of purchased power consumed is equal to the amount of contracted power consumed over a predetermined period of time.

[0065] For example, as shown in Figure 18, the control command value S1 for contracted power is set so that the amount of purchased electricity becomes the contracted amount, and therefore at time t1 it is a larger value than the control command value S shown in Figure 14. The control command value S1 for contracted power can be set by calculating the integral value of purchased electricity and the integral value of contracted power to determine the amount of purchased electricity and the contracted amount.

[0066] Furthermore, the control command value for renewable power is a control command value set so that the charging and discharging power becomes renewable power. In other words, it is a control command value set considering only that the charging and discharging power becomes renewable power, without considering purchased electricity.

[0067] For example, the control command value S2 for renewable power is set so that the charge / discharge power Pe becomes renewable power Pc. Therefore, as the charge / discharge power Pe decreases as shown in Figure 17, the control command value S2 rises to the upper limit as shown in Figure 18. Thus, by using the control command value S2 for renewable power, the charge / discharge power Pe can be raised to the maximum renewable power Pc.

[0068] Of the control command values ​​set for contracted power and renewable power, the smaller of the two is selected and used as the transmission control command value S3 to be sent to the electric vehicles EV1 and EV2, as shown in Figure 18. In Figure 18, the control command value S2 for renewable power is selected from time t0 to t7, and the control command value S1 for contracted power is selected from time t7 onward. In this way, the charge / discharge control device 21 sets the control command value S1 for contracted power and the control command value S2 for renewable power, and selects and uses the smaller of these two control command values.

[0069] [Differentiation] In this embodiment, the selection of the transmission control command value S3 is performed by the charge / discharge control device 21 of the control server 1, but it may also be performed by the charge / discharge units 25A and 25B of the electric vehicles EV1 and EV2. In this case, the charge / discharge control device 21 generates a control command value S1 for contracted power and a control command value S2 for renewable power and transmits them to the charge / discharge units 25A and 25B. The received charge / discharge units 25A and 25B then select the smaller control command value and use it as the transmission control command value S3.

[0070] [Effects of the third embodiment] As described in detail above, the charge / discharge control device 21 according to this embodiment sets a control command value for contracted power, which is set so that the amount of purchased electricity is equal to the contracted power amount, and a control command value for renewable power, which is set so that the charge / discharge power is renewable power. The smaller of the two control command values ​​is then selected as the control command value. As a result, when the control command value for contracted power is selected, the contracted power amount can be fully utilized, and when the control command value for renewable power is selected, the electric vehicle can be rapidly charged with renewable power.

[0071] [Fourth Embodiment] A fourth embodiment to which the present invention is applied will be described below with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals, and detailed descriptions are omitted. The power system 100 according to this embodiment is identical in configuration to that of the first embodiment shown in Figure 1.

[0072] In this embodiment, the method for setting the control command value for renewable power differs from that of the third embodiment. In the third embodiment, as shown in Figure 17, the charging and discharging power Pe exceeded the renewable power Pc after time t5. However, since electric vehicles have a need to be charged using only renewable energy, it is sometimes better to charge them so that the charging and discharging power Pe does not exceed the renewable power Pc. Therefore, in this embodiment, the charging and discharging power Pe is controlled so that it does not exceed the renewable power Pc.

[0073] Specifically, when the regenerative power control command value S2 decreases, the charge / discharge control device 21 sets and maintains the regenerative power control command value S2 at the value of the currently selected control command value. As shown in Figure 17 of the third embodiment, when the charge / discharge power Pe exceeds the regenerative power Pc, the regenerative power control command value S2 decreases as shown in Figure 18. Therefore, the charge / discharge control device 21 monitors the regenerative power control command value S2, and when the current value decreases from the previous value, it sets and maintains the regenerative power control command value S2 at the value of the currently selected transmission control command value S3.

[0074] For example, as shown in Figure 21, at time t5, when the charge / discharge power Pe becomes the renewable power Pc, the renewable power control command value S2 decreases, and the renewable power control command value S2 is set to the value of the currently selected transmission control command value S3. Therefore, as shown in Figure 22, the value of the renewable power control command value S2 drops sharply to the value of the transmission control command value S3, and is maintained at that value until the contracted power control command value S1 decreases. As a result, as shown in Figure 21, the charge / discharge power Pe is maintained at the power value at time t5, and is controlled so as not to exceed the renewable power Pc. In this embodiment, the system monitors when the renewable power control command value S2 decreases, but it may also monitor when the charge / discharge power Pe exceeds the renewable power Pc.

[0075] [Differentiation] In this embodiment, the selection of the transmission control command value S3 is performed by the charge / discharge control device 21 of the control server 1, but it may also be performed by the charge / discharge units 25A and 25B of the electric vehicles EV1 and EV2. In this case, the charge / discharge control device 21 generates a control command value S1 for contracted power and a control command value S2 for renewable power and transmits them to the charge / discharge units 25A and 25B. The received charge / discharge units 25A and 25B then select the smaller control command value and use it as the transmission control command value S3.

[0076] Furthermore, the charging and discharging units 25A and 25B monitor the renewable power control command value S2, and when the renewable power control command value S2 decreases, they record the difference between the renewable power control command value S2 and the immediately preceding transmission control command value S3 as a correction value. Then, they set the renewable power control command value S2 by subtracting the correction value from the received renewable power control command value S2.

[0077] Furthermore, if the control command value S2 for renewable power changes, the correction value may increase. In that case, the control command value S2 for renewable power after subtracting the correction value will decrease, so the charge / discharge power Pe will not be charged up to the renewable power Pc. Therefore, if the correction value is large, it may be modified to decrease it. For example, the correction value may be reduced by about 1%. Also, if the charge / discharge units 25A and 25B have obtained the upper limit of the control command value S2 for renewable power, the correction value may be modified only when subtracting the correction value from the upper limit.

[0078] [Effects of the fourth embodiment] As described in detail above, the charge / discharge control device 21 according to this embodiment sets and maintains the renewable power control command value to the currently selected control command value when the renewable power control command value decreases. This allows the charge / discharge power to be controlled so as not to exceed the renewable power, thereby preventing the electric vehicles EV1 and EV2 from being charged with power other than renewable energy.

[0079] The embodiments described above are merely examples of the present invention. Therefore, the present invention is not limited to the embodiments described above, and various modifications are possible in forms other than those described above, as long as they do not depart from the technical spirit of the present invention, depending on the design and other factors. [Explanation of Symbols]

[0080] 1. Control Server 3A, 3B power receiving device 5 load 7. Renewable energy supply facilities 10 Power system 11 Power grid 12 Electric wire 14 Transformers 15A, 15B Current Measuring Device 21 Charge / Discharge Control Device 23a Broadcast transmission unit 23b Broadcast Transmitter 25A, 25B charge / discharge section EV1, EV2 electric vehicles 100 Power Systems

Claims

1. In a power system that supplies power from the power grid and renewable power generated from renewable energy to a power-consuming load and multiple charge / discharge elements, a charge / discharge control method for controlling the charging and discharging of the charge / discharge elements, By comparing the electricity purchased from the aforementioned power grid with the contracted electricity to be purchased from the aforementioned power grid, The system switches between a peak-cut mode, which controls the charging and discharging power of the charging and discharging element so that the purchased electricity becomes the contracted power, and a renewable energy utilization mode, which charges the charging and discharging element with renewable energy. A control command value for contracted power is set so that the amount of purchased power consumed is equal to the amount of contracted power consumed for a predetermined period of time, and a control command value for renewable power is set so that the charging and discharging power is equal to the renewable power. The control command value that is smaller than the control command value for the contracted power and the control command value for the renewable power is selected as the control command value for controlling the charging and discharging power. A method for controlling the charging and discharging of charging and discharging elements.

2. If the purchased electricity is greater than the contracted power, the system is set to peak cut mode, and a control command value is set to control the charging and discharging power so that the purchased electricity becomes the contracted power. When the purchased electricity is less than or equal to the contracted power, the system is set to the renewable energy utilization mode, and the control command value is set so that the charging and discharging power becomes renewable power. A method for controlling the charging and discharging of a charging and discharging element according to claim 1.

3. The system is set to peak cut mode when the absolute value of the difference between the contracted power and the purchased power is smaller than the absolute value of the difference between the renewable power and the charge / discharge power, and a control command value is set to control the charge / discharge power so that the purchased power becomes the contracted power. The renewable energy utilization mode is set when the absolute value of the difference between the contracted power and the purchased power is greater than or equal to the absolute value of the difference between the renewable power and the charging / discharging power, and the control command value is set so that the charging / discharging power becomes the renewable power. A method for controlling the charging and discharging of a charging and discharging element according to claim 1.

4. When the aforementioned control command value for renewable power decreases, the control command value for renewable power is set to the currently selected control command value and maintained. A method for controlling the charging and discharging of a charging and discharging element according to claim 1.

5. In a power system that supplies power from the power grid and renewable energy generated from renewable energy sources to a power-consuming load and multiple charge / discharge elements, a charge / discharge control device is provided, which includes a controller for controlling the charging and discharging of the charge / discharge elements. By comparing the electricity purchased from the aforementioned power grid with the contracted electricity to be purchased from the aforementioned power grid, The system switches between a peak-cut mode, which controls the charging and discharging power of the charging and discharging element so that the purchased electricity becomes the contracted power, and a renewable energy utilization mode, which charges the charging and discharging element with renewable energy. A control command value for contracted power is set so that the amount of purchased power consumed is equal to the amount of contracted power consumed for a predetermined period of time, and a control command value for renewable power is set so that the charging and discharging power is equal to the renewable power. The control command value that is smaller than the control command value for the contracted power and the control command value for the renewable power is selected as the control command value for controlling the charging and discharging power. Charge / discharge control device for charge / discharge elements.

Images