Power interchanging system

Abstract

To provide a power interchanging system capable of ensuring a maximum amount of power without predicting a power generation amount of solar power generation or power need of a consumer.SOLUTION: A power interchanging system according to the present invention is a power interchanging system in which a power storage device has a short capacity for a power generation amount of solar power generation. In a case where surplus power is generated for a consumer possessing the solar power generation and the power storage device, power interchange is preferentially executed, but if the surplus power is still left, the power is stored in the power storage device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a power interchange system. [Background technology]

[0002] Patent Document 1 discloses a power distribution system in which a power flow sensor and a voltage sensor are installed at each consumer in a power interchange block to prevent the allowable current value of the power lines from exceeding or the voltage from deviating from a specified range, and the system controls the charging and discharging of each consumer's storage battery based on predictions of the amount of power generated by each consumer's solar power generation and power demand to prevent the above-mentioned exceedances and deviations from occurring. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6921529 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the power distribution system disclosed in Patent Document 1 requires a system for predicting the amount of power generated by solar power generation at consumers and their power demand, and there is room for improvement to more simply adjust the supply and demand balance.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a power interchange system that can secure the maximum amount of power without having to predict the amount of power generated by solar power generation or power demand at customers. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the objectives, the power interchange system of the present invention is a power interchange system in which the capacity of a power storage device is insufficient compared to the amount of power generated by solar power generation, and is characterized in that when surplus power occurs at a consumer that owns the solar power generation system and the power storage device, power interchange is carried out with priority, and if surplus power still remains, the power storage device is charged. [Effects of the Invention]

[0007] The power interchange system according to the present invention has the effect of being able to secure the maximum amount of power without having to predict the amount of power generated by photovoltaic power generation or power demand at the customer's facility. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing a power interchange system according to an embodiment. [Figure 2] FIG. 2 is a flowchart showing an example of control performed by each of the HEMS terminal and the power interchange server in the power interchange system according to the embodiment. [Figure 3] Figure 3 shows the usage status of solar power generation. [Figure 4] Figure 4 is a graph showing the utilization of surplus solar power generation. [Figure 5] FIG. 5 is a graph showing the usage status of the available capacity (3 [kWh]) of a BEV (electricity storage device). DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of a power interchange system according to the present invention will be described, but the present invention is not limited to the embodiment.

[0010] FIG. 1 is a diagram showing a power interchange system 10 according to an embodiment.

[0011] In a power interchange system 10 according to this embodiment, a HEMS terminal 5 monitors the amount of power generated by a photovoltaic power generation device 3 and the power demand at regular intervals in a plurality of homes 2 that are consumers constituting a power interchange group 1 and that receive power from a distribution system 7 via a distribution line 8. The HEMS terminal 5 notifies a power interchange server 6 via a communication network of the power surplus or shortage calculated from "power generation amount - power demand." The power interchange server 6 adds up the power surplus and shortage of all homes 2 in the power interchange system 10, sets the smaller of the surplus and shortage as interchange power, and allocates reverse flow power for power interchange to homes 2 that have a surplus. If the surplus power is greater than the allocated reverse flow power and the home 2 owns a power storage device 4 mounted on a BEV (electric vehicle) or the like, the surplus power is reverse-flowed and further stored in the power storage device 4.

[0012] As a result, in the power interchange system 10 according to the embodiment, the interchange of surplus power and the charging of the power storage device 4 can be brought closer to the ideal timing without predicting the amount of power generated by solar power generation and the power demand, thereby achieving both system cost reduction and the local production and consumption of more renewable energy.

[0013] Here, in the power interchange system 10 according to the embodiment, it is assumed that the residences 2 include a mixture of residences 2 that own both or either a photovoltaic power generation device 3 and a power storage device (storage battery) 4 mounted on a BEV (electrically-powered vehicle) or the like, and residences 2 that own neither. For example, assuming that the penetration rate of photovoltaic power generation devices 3 among detached houses in 2030 will be 25%, a power interchange group 1 can be created and surplus power can be exchanged with the remaining 75% of residences 2 that do not own photovoltaic power generation devices 3, thereby enabling more renewable energy to be produced and consumed locally in the power interchange group 1. With this background in mind, this embodiment will be described according to the flow shown in FIG. 2.

[0014] FIG. 2 is a flowchart showing an example of control performed by each of the HEMS terminal 5 and the power interchange server 6 in the power interchange system 10 according to the embodiment.

[0015] First, (1) HEMS terminal control (measurement) will be explained.

[0016] In step S101, the amount of power generated G_i [kWh] by the photovoltaic power generation device 3 and the amount of power demand D_i [kWh] by the residence 2 are measured for a certain period of time. Note that "_i" is a subscript that indicates the residence 2 in question. The measurement time is preferably short, such as one minute, to minimize the time lag with (3) HEMS terminal control (charging of the power storage device), which will be described later. Furthermore, to ensure consistency with other residences 2, the timing of the start and end of measurement is aligned within the power interchange group 1, for example, from 9:00:00 to 9:01:00, and is repeated every minute (e.g., 9:00 to 9:01, 9:01 to 9:02, etc.).

[0017] In step S102, the amount of surplus power PS and the amount of shortage power PL of photovoltaic power generation for a certain period of time are calculated, where PS_i=Max(G_i-D_i,0) and PL_i=Max(D_i-G_i,0).

[0018] In step S103, the surplus power and the shortage power for a certain period of time are transmitted to the power interchange server 6 via the communication network.

[0019] Next, (2) Power interchange server control will be described.

[0020] In step S201, the surplus power PS_i [kWh] and the shortage power PL_i [kWh] for the same time period are received from all the homes 2.

[0021] In step S202, the total surplus power PS [kWh] and the total power shortage PL [kWh] are calculated for the power interchange group 1. Note that PS = ΣPS_i and PL = ΣPL_i, where "Σ" is a calculation to calculate the total for the houses 2 in the power interchange group 1.

[0022] In step S203, the interchange power PI of the power interchange group 1 is calculated, where PI=Min(PS, PL).

[0023] In step S204, the reverse flow power PR_i [kWh] for power interchange between each residence 2 is calculated, where PR_i=PI×(PS_i / PS).

[0024] In step S205, the power interchange server 6 transmits the reverse flow power of each home 2 to each home 2.

[0025] Next, (3) HEMS terminal control (charging of power storage device) will be described.

[0026] In step S301, it is determined whether the home 2 in question owns a power storage device 4. Information on whether or not the home 2 owns a power storage device 4 is stored in a recording device built into the HEMS terminal 5 of each home 2, and this information is read to make the determination. If it is determined that the home 2 in question owns a power storage device 4 (Yes in step S301), the process proceeds to step S302. On the other hand, if it is determined that the home 2 in question does not own a power storage device 4 (No in step S301), the process ends. If a power storage device 4 is added to the home 2, the information in the HEMS terminal 5 of the home 2 in question is rewritten.

[0027] In step S302, the process waits for reception of the reverse flow power PR_i [kWh] of each residence 2 from the power interchange server 6, and after reception is complete, the process proceeds to step S303.

[0028] In step S303, the magnitude of surplus power PS_i and the magnitude of reverse flow power PR_i are compared. If the relationship of surplus power PS_i > reverse flow power PR_i is satisfied (Yes in step S303), the process proceeds to step S304. On the other hand, if the relationship of surplus power PS_i ≦ reverse flow power PR_i is satisfied (No in step S303), the process proceeds to step S305, where charging to the power storage device 4 is disabled and reception of the reverse flow power PR_i for the next time step is awaited.

[0029] In step S304, charging of the power storage device 4 of the house 2 is permitted by the surplus power obtained by subtracting the reverse flow power PR_i from the surplus power PS_i. In other words, the chargeable power PCA_i [kWh] is calculated by PCA_i = PS_i - PR_i. However, the final amount of power to be charged is determined according to constraints such as the available capacity of the power storage device 4 and the charger output.

[0030] The above is the process for one time step of the control in this embodiment. If the measurement time of the HEMS terminal 5 is one minute, the above process is repeated every minute.

[0031] A feature of the power management device of the embodiment is that even if the house 2 has a power storage device 4, when surplus power occurs, the device first exchanges power as much as possible, and if surplus power still remains, it is charged into the power storage device 4 of the house 2, thereby realizing what is called "interchange priority control."

[0032] Next, the effects of this embodiment will be described. Because an electric vehicle such as a BEV is both a power storage device 4 and a means of transportation, the capacity of the power storage device 4 is likely to be a constraint when charging with surplus solar power. This is because the available capacity of the power storage device 4 is often limited in order to ensure the power required for the electric vehicle's travel. Based on this, FIG. 3 shows the results of a trial calculation of the effects of this embodiment under the following assumptions. The assumptions for the power interchange group 1 and the simulation calculation are as follows: First, the ownership rate of solar power generation devices 3 among residences 2 is 25% and the power generation capacity is 4.5 kW / unit. Next, the ownership rate of BEVs (electrically-powered vehicles) among residences 2 is 7.5%, and residences 2 that own BEVs (electrically-powered vehicles) also own solar power generation devices 3, with the available capacity of the BEV's (electrically-powered vehicles) power storage devices 4 being 3 kWh / unit. Next, assume a day in spring when solar power generation is high.

[0033] The "interchange priority control" of the example of the present invention shown in Figure 3(a) results in less power sold (= power that is not interchanged or charged to the power storage device 4 and is instead reversely flowed outside the power interchange group 1) than the "charging priority control" shown as the reference example. In other words, it can be seen that the interchange priority control can achieve more local production and consumption of renewable energy. Note that in this embodiment, the charging priority control is defined as control in which, when a residence 2 owns a power storage device 4 and surplus power is generated, the power storage device 4 is first charged as much as possible, and if any surplus power still remains, it is exchanged with another residence 2.

[0034] Fig. 4 is a graph showing the usage status of surplus electricity generated by solar power generation. More specifically, Fig. 4(a) is a graph showing the relationship between the behavior of electricity interchange and electricity demand. Fig. 4(b) is a graph showing the relationship between the behavior of charging the BEV (electricity storage device 4) and electricity demand. Fig. 5 is a graph showing the usage status of the available capacity (3 [kWh]) of the BEV (electricity storage device 4).

[0035] The demand for electricity at the residence 2 is generally high in the morning and in the evening and nighttime, and low during the day. Even within the power interchange group 1, there is a tendency for power interchange to decrease as demand decreases during the daytime when there is a lot of surplus electricity generated by solar power generation. Therefore, in order to realize the local production and consumption of more renewable energy, it is important to be able to charge the electricity storage device 4 with surplus electricity during the daytime when it is difficult to interchange electricity. This is particularly important in situations where the capacity of the electricity storage device 4 is small relative to the surplus electricity.

[0036] In the interchange priority control of the present invention, surplus electricity is interchanged during the morning hours of 7:00 to 8:00, and charging of the storage device 4 is not performed. Instead, charging of the storage device 4 begins at 9:00 when electricity demand decreases, thereby realizing the ideal charging control of the storage device 4 described above.

[0037] This is because interchange priority control matches the characteristics of solar power generation, where there is a lot of surplus electricity during the day, while demand from the home 2 is conversely low, and a simple mechanism can ensure that the limited available capacity of the storage device 4 is maintained until daytime.

[0038] When solar power generation is not widespread in all homes 2 and power interchange is an effective means of expanding the use of renewable energy, and the storage capacity of storage devices 4 such as BEVs (electric vehicles) is not sufficient for surplus power, the present invention can provide control that allows more renewable energy to be produced and consumed locally at low cost without the need to predict power demand or solar power generation. [Explanation of symbols]

[0039] 1. Power Interchange Group 2. Housing 3. Solar power generation equipment 4. Energy storage device 5 HEMS terminal 6. Power interchange server 7 Power distribution system 8 minute wiring 10 Power interchange system

Claims

[Claim 1] A power interchange system in which the capacity of a power storage device is insufficient for the amount of power generated by solar power generation, This power interchange system is characterized in that when a consumer that owns the solar power generation system and the storage device has surplus electricity, it prioritizes power interchange, but if there is still surplus electricity, it charges the storage device.

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