Power control system

Abstract

To provide a power control system capable of adjusting power balance on a power transmission grid using an electric vehicle parked at a parking facility.SOLUTION: A power control system 1 comprises a plurality of parking facilities 3 connected to a power transmission grid 2, a monitoring device 4 monitoring a frequency F of a voltage of the power transmission grid 2, a control device 6 communicatively connected to the monitoring device 4 and the plurality of parking facilities 3 via a communication network 5, and charge / discharge control devices 31b-34b controlling charging or discharging of an electric vehicle 8. The control device 6 controls the charge / discharge control devices 31b-34b so that the charge rate of the electric vehicle 8 parked at the parking facility 3 does not reach 100% when the frequency F of the voltage of the power transmission grid is within a predetermined range close to a target frequency Ft.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power control system, and more particularly to a power control system using a parking facility where electric vehicles can be parked.

Background Art

[0002] In recent years, electric vehicles (EVs: Electric Vehicles) that use electricity as an energy source and an electric motor as a power source have been increasingly popular. In addition, hybrid vehicles (HV: Hybrid Vehicles) that also have an internal combustion engine (engine) as a power source in addition to an electric motor have been increasingly popular. Hereinafter, in this specification, "electric vehicle" shall include both electric vehicles (EVs) and hybrid vehicles (HV).

[0003] Current electric vehicles generally have a secondary battery (storage battery) that can be charged from an external power source, and supply electricity from the secondary battery to an electric motor to drive it. As such electric vehicles become more popular, a plurality of electric vehicles will be parked in a parking facility.

[0004] For example, in view of the fact that the total power output from each battery built into each of a plurality of electric vehicles is comparable to the power for driving a parking device, the invention described in Patent Document 1 discloses drawing power from parked electric vehicles and supplying it to a parking device or a power transmission network.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The invention described in the above-mentioned Patent Document 1 is characterized in how to draw out the power charged from the electric vehicles parked in each parking device. In the invention described in Patent Document 1, it is described that a higher-level controller connected to the power grid is provided, and such a controller communicates various communication contents to the parking device based on the power supply and demand balance of the power grid, etc.

[0007] However, in the invention described in Patent Document 1, how to judge the power supply and demand balance of the power grid and how to control a plurality of parking devices based on such power supply and demand balance are not disclosed.

[0008] The present invention was devised in view of such problems, and an object thereof is to provide a power control system capable of adjusting the power balance of the power grid by using electric vehicles parked in a parking facility.

Means for Solving the Problems

[0009] According to the present invention, it includes a plurality of parking facilities connected to the power grid, a monitoring device for monitoring the frequency of the voltage of the power grid, and a control device communicably connected to the plurality of parking facilities and the monitoring device. Each of the parking facilities includes a power source capable of charging the parked electric vehicle and a charge and discharge control device for controlling the charging or discharging of the electric vehicle. The control device is configured to control the charge and discharge control device so that the charging rate of the electric vehicle parked in the parking facility does not reach 100% when the frequency of the voltage of the power grid is within a predetermined range close to the target frequency. A power control system is provided, which is characterized by this.

[0010] The charge and discharge control device may be configured to end charging when the charging rate reaches a preset value.

[0011] Further, according to the present invention, there are provided a plurality of parking facilities connected to a power transmission network, a monitoring device for monitoring the frequency of the voltage of the power transmission network, and a control device communicably connected to the plurality of parking facilities and the monitoring device. Each of the parking facilities includes a power source capable of charging a parked electric vehicle and a charge / discharge control device for controlling charging or discharging of the electric vehicle. The control device is configured to output a charging command instructing the parking facility to charge the parked electric vehicle when the frequency of the voltage of the power transmission network is within a predetermined range close to a target frequency. There is provided a power control system characterized by this.

[0012] The control device may be configured to output a charging command instructing the parking facility to charge the parked electric vehicle when the frequency of the voltage of the power transmission network is higher than the target frequency.

[0013] The parking facility may be a parking facility capable of accommodating at least one or more of the electric vehicles.

Advantages of the Invention

[0014] According to the power control system according to the present invention described above, since the charging or discharging of the electric vehicle parked in the parking facility is performed based on the fluctuation of the frequency of the voltage of the power transmission network, the power balance of the power transmission network can be adjusted by using the electric vehicle parked in the parking facility.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 3. Here, FIG. 1 is an overall configuration diagram showing a power control system according to an embodiment of the present invention. FIG. 2 is a diagram showing an example of a control flow of the control device.

[0017] A power control system 1 according to an embodiment of the present invention includes, for example, as shown in FIG. 1, a plurality of parking facilities 3 connected to a power transmission network 2, a monitoring device 4 that monitors the frequency F of the voltage of the power transmission network 2, and a control device 6 communicably connected to the monitoring device 4 and the plurality of parking facilities 3 via a communication network 5.

[0018] The power transmission network 2 is, for example, a commercial power network of three-phase alternating current 6.6 kV. The power transmission network 2 is, for example, a power system with a frequency of 50 Hz (eastern Japan) or a power system with a frequency of 60 Hz (western Japan). Therefore, when the power transmission network 2 is a power system with a frequency of 50 Hz, the target frequency of the voltage is 50 Hz, and when the power transmission network 2 is a power system with a frequency of 60 Hz, the target frequency of the voltage is 60 Hz. In addition, a power plant 7, which is a power supply source, is connected to the power transmission network 2.

[0019] The parking facility 3 is a parking facility capable of charging the parked electric vehicle 8. The parking facility 3 may be a self-propelled parking device or a mechanical parking device as long as it is capable of charging. In addition, the parking facility 3 may be a household parking facility capable of accommodating only one vehicle, or a large-scale parking facility capable of accommodating 100 or more vehicles. The electric vehicle 8 is, for example, an electric vehicle (EV) or a hybrid vehicle (HV).

[0020] In the embodiment shown in FIG. 1, for convenience of explanation, a case where four parking facilities 3, namely, a first parking facility 31, a second parking facility 32, a third parking facility 33, and a fourth parking facility 34, are connected to the power transmission network 2 is illustrated. The number of parking facilities 3 connected to the power transmission network 2 is preferably as large as possible, and ideally, it is preferably on the scale of hundreds of thousands or millions of units.

[0021] The first parking facility 31 to the fourth parking facility 34 are provided with, for example, power sources 31a to 34a capable of charging the parked electric vehicle 8, and charge / discharge control devices 31b to 34b for controlling the charging or discharging of the electric vehicle 8.

[0022] The power sources 31a to 34a are storage batteries installed in each of the first parking facility 31 to the fourth parking facility 34 and are connected to the power transmission network 2. The power sources 31a to 34a are provided with a converter for converting the alternating voltage supplied from the power transmission network 2 into a direct current voltage. Further, the power sources 31a to 34a are provided with an inverter for converting electricity from a direct current voltage into an alternating voltage and supplying it to the power transmission network 2.

[0023] The charge / discharge control devices 31b to 34b are connected to the communication network 5 and have functions such as maintaining a constant charge amount of the power sources 31a to 34a, supplying electricity from the power sources 31a to 34a to the parked electric vehicle 8 to charge the electric vehicle 8, and supplying the electricity stored in the secondary battery (storage battery) of the parked electric vehicle 8 to the power transmission network 2 via the power sources 31a to 34a.

[0024] Note that the specific configuration for charging the electric vehicle 8 at each parking facility 3 and the specific configuration for supplying electricity from the electric vehicle 8 to the power transmission network 2 are described in, for example, Japanese Patent Application Laid-Open No. 2013-42634 (Patent Document 1), etc., and thus detailed description is omitted in this specification.

[0025] The monitoring device 4 is a sensor that monitors whether the frequency F of the voltage of the power transmission network 2 is higher than the target frequency Ft or the frequency F of the voltage of the power transmission network 2 is lower than the target frequency Ft. The frequency F measured by the monitoring device 4 is transmitted to the control device 6 via the communication network 5. Note that the communication network 5 is a communication network capable of mutual data communication such as the so-called Internet.

[0026] Incidentally, it is known that the frequency F of the voltage of the power transmission network 2 is determined by the balance between demand (load amount) and supply (power generation amount). For example, if the supply (power generation amount) is large, the frequency tends to be high, and if the demand (load amount) is large, the frequency tends to be low. Since the demand (load amount), which is the amount of electricity used, is constantly changing, the frequency F of the voltage of the power transmission network 2 also constantly changes.

[0027] The power company adjusts the power generation amount so that the amount of change in this frequency F is within ±0.1 to ±0.2 Hz with respect to the target frequency (50 Hz or 60 Hz). This adjustment of the power generation amount is performed at the power plant 7 of the power transmission network 2. Since the power plant 7 is usually a thermal power plant, an increase in the power generation amount means an increase in the amount of fuel used, leading to an increase in the amount of carbon dioxide generated.

[0028] The power control system 1 according to the present embodiment uses the electric vehicles 8 parked in a plurality of parking facilities 3 as a means for adjusting the amount of change in this frequency F to be within ±0.1 to ±0.2 Hz with respect to the target frequency (50 Hz or 60 Hz).

[0029] In this way, by using the electricity charged in the electric vehicle 8 as part of the social infrastructure, it is possible to reduce the amount of fuel used and the amount of carbon dioxide generated in the thermal power plant, and improve the added value of the electric vehicle 8.

[0030] Based on the signal (measurement result) transmitted from the monitoring device 4, when the frequency F of the voltage of the power transmission network 2 is higher than the target frequency Ft, the control device 6 outputs a charging command instructing the electric vehicle 8 parked at the parking facility 3 to be charged, and when the frequency F of the voltage of the power transmission network 2 is lower than the target frequency Ft, the control device 6 outputs a discharging command instructing the electric vehicle 8 parked at the parking facility 3 to be discharged.

[0031] The control device 6 controls the charging and discharging of the electric vehicle 8 based on, for example, the control flow shown in FIG. 2. The frequency F of the voltage of the power grid 2 is periodically monitored by the monitoring device 4 (monitoring step Step1). Then, the control device 6 determines whether the frequency F measured by the monitoring device 4 is higher or lower than the target frequency Ft (first determination step Step2).

[0032] In the first determination step Step2, when it is determined that F > Ft, since the supply (power generation amount) is larger than the demand (load amount), it means that there is excess power. Therefore, the control device 6 outputs a charging command instructing the parking facility 3 to charge the electric vehicle 8 parked therein (charging command step Step3).

[0033] The parking facility 3 (for example, the first parking facility 31 to the fourth parking facility 34) that has received the charging command charges the electric vehicle 8 parked by the charge-discharge control devices 31b to 34b (charging step Step4).

[0034] The control device 6 determines whether the frequency F measured by the monitoring device 4 has approached the target frequency Ft (second determination step Step5). Whether the frequency F has approached the target frequency Ft may be determined by whether the measured frequency F has reached the target frequency Ft, or may be determined by whether the measured frequency F has reached a range having a certain width with respect to the target frequency Ft (for example, a range within ±0.1 Hz with respect to the target frequency Ft).

[0035] When the control device 6 determines that the frequency F has not yet approached the target frequency Ft (No), it continues to charge the electric vehicle 8, and when it determines that the frequency F has approached the target frequency Ft (Yes), it outputs an end command instructing the end of charging of the electric vehicle 8 to the parking facility 3 (charging end command step Step6).

[0036] Upon receiving the termination command, the parking facilities 3 (for example, the first to fourth parking facilities 31 to 34) terminate the charging of the parked electric vehicles 8 by the charge-discharge control devices 31b to 34b (charging termination step Step7). Note that the charge-discharge control devices 31b to 34b may terminate the charging of the parked electric vehicles 8 without waiting for the termination command from the control device 6 when the charging rates of all the parked electric vehicles 8 reach a preset value (for example, any value within the range of 80 to 100%).

[0037] On the other hand, in the first determination step Step2, if it is determined that F < Ft, since the supply (power generation amount) is smaller than the demand (load amount), it means that there is insufficient power. Therefore, the control device 6 outputs a discharge command instructing the parking facilities 3 to discharge the parked electric vehicles 8 (discharge command step Step8).

[0038] Upon receiving the discharge command, the parking facilities 3 (for example, the first to fourth parking facilities 31 to 34) discharge the parked electric vehicles 8 by the charge-discharge control devices 31b to 34b and supply electricity to the power grid 2 (discharge step Step9).

[0039] The control device 6 determines whether the measured frequency F has approached the target frequency Ft (third determination step Step10). Whether the frequency F has approached the target frequency Ft may be determined by whether the measured frequency F has reached the target frequency Ft, or may be determined by whether the measured frequency F has reached a range having a certain width with respect to the target frequency Ft (for example, a range within ±0.1 Hz with respect to the target frequency Ft).

[0040] When the control device 6 determines that the frequency F has not yet approached the target frequency Ft (No), it continues to discharge the electric vehicle 8, and when it determines that the frequency F has approached the target frequency Ft (Yes), it outputs an end command instructing the end of the discharge of the electric vehicle 8 to the parking facility 3 (discharge end command step Step11).

[0041] Upon receiving the termination instruction, the parking facilities 3 (e.g., the first parking facility 31 to the fourth parking facility 34) terminate the discharge of the parked electric vehicle 8 by the charge and discharge control devices 31b to 34b (discharge termination step Step12). Note that the charge and discharge control devices 31b to 34b may terminate the discharge of the electric vehicle 8 without waiting for the termination instruction from the control device 6 when the charge rate of all the parked electric vehicles 8 reaches a preset value (e.g., any value within the range of 0 to 20%).

[0042] According to such a control flow, the parked electric vehicle 8 in the parking facility 3 can be charged or discharged based on the fluctuation of the frequency F of the voltage of the power grid 2. Also, by using the above-described control flow, when the frequency F of the voltage of the power grid 2 is higher than the target frequency Ft, the parked electric vehicle 8 in the parking facility 3 can be charged, and when the frequency F of the voltage of the power grid 2 is lower than the target frequency Ft, the parked electric vehicle 8 in the parking facility 3 can be discharged.

[0043] According to the power control system 1 and the power control method according to the above-described embodiment, since the parked electric vehicle 8 in the parking facility 3 is charged or discharged based on the fluctuation of the frequency F of the voltage of the power grid 2, the power balance of the power grid 2 can be adjusted by using the parked electric vehicle 8 in the parking facility 3.

[0044] In the above-described embodiment, instructions to charge or discharge are output to all the parking facilities 3 (e.g., the first parking facility 31 to the fourth parking facility 34), but priority orders for charging or discharging may be set based on the charge rate or charge capacity of the parking facilities 3 and instructions may be output accordingly. Here, FIG. 3 is a diagram showing an example of a priority order setting method of the control device.

[0045] Now, for the sake of convenience of explanation, assume that the number of vehicles that can be accommodated in the first parking facility 31 is 50, the number of vehicles that can be accommodated in the second parking facility 32 is 30, the number of vehicles that can be accommodated in the third parking facility 33 is 30, and the number of vehicles that can be accommodated in the fourth parking facility 34 is 10.

[0046] Also, if the battery capacity of the electric vehicle 8 is 50 kWh, the total battery capacity of the first parking facility 31 is 2500 kWh, the total battery capacity of the second parking facility 32 is 1500 kWh, the total battery capacity of the third parking facility 33 is 1500 kWh, and the total battery capacity of the fourth parking facility 34 is 500 kWh.

[0047] Here, as shown in Fig. 3, if the charging rate of the first parking facility 31 is 30%, the charging capacity is 750 kWh and the available capacity is 1750 kWh. Also, if the charging rate of the second parking facility 32 is 50%, the charging capacity is 750 kWh and the available capacity is 750 kWh. Also, if the charging rate of the third parking facility 33 is 80%, the charging capacity is 1200 kWh and the available capacity is 300 kWh. Also, if the charging rate of the fourth parking facility 34 is 100%, the charging capacity is 500 kWh and the available capacity is 0 kWh.

[0048] Note that information such as the charging rate of each parking facility 3 (the first parking facility 31 to the fourth parking facility 34) and the number of parking spaces of the electric vehicle 8 is periodically transmitted from the charge-discharge control devices 31b to 34b to the control device 6 via the communication network 5.

[0049] In this state, when outputting a charging command from the control device 6, the priority may be set in order from the parking facility 3 with a large available battery capacity, and the charging command may be output. In the first example shown in Fig. 3, since the available capacity has the relationship of the first parking facility 31 > the second parking facility 32 > the third parking facility 33 > the fourth parking facility 34, the priority is set in the order of the first parking facility 31 → the second parking facility 32 → the third parking facility 33 → the fourth parking facility 34. Note that no charging command may be output to the fourth parking facility 34 with no available battery capacity.

[0050] Also, when outputting a discharge command from the control device 6, the priority may be set in order from the parking facility 3 with a large charging capacity of the battery, and the discharge command may be output. In the first example shown in Fig. 3, the charging capacity has the relationship of the third parking facility 33 > the second parking facility 32 = the first parking facility 31 > the fourth parking facility 34.

[0051] At this time, when the charging capacities are the same, for example, the priority of the one with the higher charging rate may be set higher. Therefore, during discharging, as shown in the figure, the priorities are set in the order of the third parking facility 33 → the second parking facility 32 → the first parking facility 31 → the fourth parking facility 34.

[0052] In the power control system according to this embodiment, since the charging and discharging of the electric vehicle 8 are performed according to the power balance of the power transmission network 2, when the parked electric vehicle 8 is fully charged (charging rate 100%), it cannot respond to the charging command from the control device 6. Therefore, the charge / discharge control devices 31b to 34b may prevent the parked electric vehicle 8 from being fully charged. For example, the upper limit of the charging rate of the electric vehicle 8 can be set to 80%.

[0053] Since the power control system 1 according to the above-described embodiment utilizes the battery of the electric vehicle 8 for social infrastructure based on the power balance of the power transmission network 2, the understanding and cooperation of the owner of the electric vehicle 8 are required. Therefore, it is preferable that the parking facility 3 is a monthly parking facility where users are identified and regular parking for a certain period of time is expected.

[0054] However, the power control system 1 according to this embodiment is not limited to monthly parking facilities, and can also be widely applied to parking facilities of commercial facilities, companies, etc. by taking measures such as reducing parking fees.

[0055] The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

Explanation of Reference Numerals

[0056] 1 Power control system 2 Power transmission network 3 Parking facility 4 Monitoring device 5 Communication network 6 Control device 7 Power plant 8 Electric vehicle 31 First parking facility 32 Second parking facility 33 Third parking facility 34 Fourth parking facility 31a~34a Power supply 31b~34b Charge and discharge control device Step1 Monitoring step Step2 Judgment step Step2 First judgment step Step3 Charge command step Step4 Charging step Step5 Second judgment step Step6 Charge end command step Step7 Charge end step Step8 Discharge command step Step9 Discharging step Step10 Third judgment step Step11 Discharge end command step Step12 Discharge end step

Claims

1. A plurality of parking facilities connected to a power transmission network, a monitoring device that monitors the frequency of the voltage of the power transmission network, and a control device communicably connected to the plurality of parking facilities and the monitoring device, wherein each of the parking facilities includes a power source capable of charging a parked electric vehicle and a charge / discharge control device that controls charging or discharging of the electric vehicle, and the control device is configured to control the charge / discharge control device so that the charging rate of the electric vehicle parked at the parking facility does not reach 100% when the frequency of the voltage of the power transmission network is within a predetermined range close to a target frequency. A power control system characterized by the above.

2. The power control system according to claim 1, wherein the charge / discharge control device is configured to terminate charging when the charging rate reaches a preset value.

3. A plurality of parking facilities connected to a power transmission network, a monitoring device that monitors the frequency of the voltage of the power transmission network, and a control device communicably connected to the plurality of parking facilities and the monitoring device, wherein each of the parking facilities includes a power source capable of charging a parked electric vehicle and a charge / discharge control device that controls charging or discharging of the electric vehicle, and the control device is configured to output a charging command instructing to charge the electric vehicle parked at the parking facility when the frequency of the voltage of the power transmission network is within a predetermined range close to a target frequency. A power control system characterized by the above.

4. The power control system according to claim 3, wherein the control device is configured to output a charging command instructing to charge the electric vehicle parked at the parking facility when the frequency of the voltage of the power transmission network is higher than the target frequency.

5. The power control system according to claim 1 or 3, wherein the parking facility is a parking facility capable of accommodating at least one or more of the electric vehicles.

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