Storage battery control system

Abstract

To provide a storage battery control system capable of obtaining a larger power transaction profit while an aggregator remotely controls storage batteries of a plurality of consumers.SOLUTION: In this storage battery control system, an aggregator 4 remotely controls the operation of a storage battery 21 in a consumer's facility 2 having a solar cell 20 and the storage battery 21, and the aggregator 4 performs a first mode in which reverse power flow discharge is performed when a power market value is higher than a threshold value and reverse power flow discharge is not performed when the power market value is not higher than the threshold value, and a second mode in which when a power generation amount of the solar cell 20 exceeds a personal consumption amount, the surplus power is stored in the storage battery 21, and when the power generation amount of the solar cell 20 is insufficient, the surplus power is compensated by personal discharge from the storage battery 21. The second mode is performed in a time zone in which the solar battery 20 generates power, and the first mode is performed in other time zones.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a storage battery control system. [Background technology]

[0002] Patent Document 1 describes a power supply system. The system in this document relates to a complex facility that receives power from a grid in one go and also has its own distributed power sources. The system aims to provide the benefits of private power generation using distributed power sources to both the owner of the complex facility and the multiple power supply destinations within the complex.

[0003] For this reason, the power supply system is equipped with a power detection means and a grid power detection means. The power detection means detects the power supplied to each power supply destination, and the grid power detection means detects the exchange of power between the entire complex and the grid. The charging / discharging or power generation of the distributed power sources is controlled based on the power supplied to each power supply destination. The electricity charges for each power supply destination and the return fee to the owner of the complex are calculated based on the power supplied to each power supply destination and the exchange of power for the entire complex. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-198696 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, it has been proposed that a third party aggregator remotely controls the storage batteries of multiple consumers equipped with solar cells and storage batteries. With the aggregator's intervention, the total surplus power generated by the solar cells of multiple consumers can be used as a virtual power plant for external use. However, the technology in Patent Document 1 is limited to providing services to complex facilities and is not capable of managing multiple consumers collectively.

[0006] An object of the present disclosure is to provide a storage battery control system that enables an aggregator to remotely control storage batteries of multiple consumers and obtain greater profits from electricity trading. [Means for solving the problem]

[0007] A battery control system according to one aspect of the disclosed technology is a battery control system in which an aggregator remotely controls the operation of a storage battery at a consumer having a solar cell and a storage battery. The aggregator has a battery control unit that controls the operation of the storage battery in one of two modes: a first mode in which reverse power discharge from the storage battery is performed when the market price of electricity is higher than a threshold value and reverse power discharge from the storage battery is not performed when the market price of electricity is lower than the threshold value; and a second mode in which, when the amount of power generated by the solar cell exceeds self-consumption, the surplus is stored in the storage battery and, when the amount of power generated by the solar cell is less than self-consumption, the shortfall is made up by self-discharge from the storage battery; and a mode switching unit that switches between the first mode and the second mode. The mode switching unit controls the battery in the second mode during times when the solar cell is generating power and in the first mode during times other than when the second mode control is performed.

[0008] In the storage battery control system of the above aspect, the storage battery control unit of the aggregator controls the operation of the storage battery of the consumer. The control by the storage battery control unit has a first mode and a second mode. In the first mode, reverse power discharge from the storage battery is performed when the electricity market price is higher than a threshold, and reverse power discharge from the storage battery is not performed in other cases. In the second mode, when the amount of power generated by the solar cell exceeds the amount of power self-consumption, the surplus is stored in the storage battery. This prepares for reverse power discharge in the first mode. When the amount of power generated by the solar cell is less than the amount of power self-consumption, the shortfall is made up by self-discharge from the storage battery. By switching the mode switching unit, control in the second mode is performed during times when the solar cell is generating power, and control in the first mode is performed at other times. This aims to allow consumers to obtain greater profits from selling electricity.

[0009] In the battery control system of the above aspect, it is further preferable that the mode switching unit switches from the second mode to the first mode when the time period during which the solar cell generates power ends, and switches from the first mode to the second mode when reverse flow discharge from the storage battery ends. In this way, the first mode can be used to prepare for reverse flow discharge around evening when the electricity market price is often set high. Also, the second mode can be used during the daytime when the electricity market price is low but the power generated by the solar cell is high.

[0010] In any of the above battery control systems, the aggregator preferably further includes an information acquisition unit that acquires a forecast of electricity market prices for at least one day in the future, and a timing determination unit that determines the start and end times of reverse flow discharge in the first mode based on the information acquired by the information acquisition unit, and the mode switching unit preferably switches from the second mode to the first mode when the time period in which the solar cell generates electricity ends only if there is a start time within the next 24 hours. This configuration makes it possible to appropriately determine the start and end times of reverse flow discharge by appropriately referencing the forecast schedule of electricity market prices. Furthermore, switching to the first mode is not necessary when reverse flow discharge is not scheduled. The information acquisition unit preferably also acquires at least the time of the next sunset from a public information network. [Effects of the Invention]

[0011] According to the disclosed technique, a battery control system is provided that enables an aggregator to remotely control the storage batteries of multiple consumers and obtain greater profits from electricity trading. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a block diagram illustrating a storage battery control system according to an embodiment. [Figure 2] 1 is a graph conceptually showing a daily power consumption pattern at a consumer. [Figure 3] FIG. 2 is a block diagram showing the functional configuration of an aggregator. [Figure 4] 4 is a flowchart of control of the storage battery control system according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment that embodies the disclosed technology will be described. Figure 1 shows the players that make up the storage battery control system according to this embodiment. As shown in Figure 1, the storage battery control system 1 of this embodiment includes a consumer 2, a retailer 3, and an aggregator 4. The consumer 2 has a solar cell 20 and a storage battery 21. The consumer 2 further has a smart meter 22. The smart meter 22 is basically a watt-hour meter that accumulates the amount of electricity that the consumer 2 has purchased from the retailer 3.

[0014] The consumer 2 can meet its own power demand with any of purchased power, power generated by the solar cell 20, and power stored in the storage battery 21. The power generated by the solar cell 20 can be used to meet the consumer's own power demand, to charge the storage battery 21, or to sell to the retailer 3. The power discharged from the storage battery 21 can be used to meet the consumer's own power demand, or to sell to the retailer 3. However, in this embodiment, the surplus power generated by the solar cell 20 that exceeds the consumer's own power demand is mainly used to charge the storage battery 21. The power sold to the retailer 3 is mainly performed by discharging from the storage battery 21.

[0015] The retailer 3 is a business that sells electricity in the electricity market to the consumers 2. It may be a power company itself or a business that specializes in retail sales. In this embodiment, the retailer 3 also purchases electricity from the consumers 2 through reverse power flow.

[0016] The aggregator 4 is a business operator that oversees the sale of electricity from consumers 2 to retailers 3. The aggregator 4 basically allows consumers 2 to sell electricity during times when it is more advantageous to purchase electricity from them than to procure it from the electricity market, and prevents them from selling electricity during times when it is less advantageous to purchase electricity from them. In this way, the aggregator 4 attempts to maximize the profits of the retailers 3, thereby maximizing its own profits and those of consumers 2. Although Figure 1 shows only one consumer 2, in reality, many consumers 2 are under the jurisdiction of the aggregator 4. As a result, the aggregator 4 and its associated consumers 2 as a whole appear as a virtual power plant from the perspective of the electricity market. A single business operator may function as both a retailer 3 and an aggregator 4.

[0017] Therefore, the aggregator 4 can instruct the storage battery 21 of the consumer 2 to perform reverse flow discharge. In other words, the aggregator 4 remotely controls the operation of the storage battery 21 of the consumer 2. Reverse flow discharge at the consumer 2 is basically performed based on a reverse flow discharge instruction from the aggregator 4. The reverse flow discharge instruction from the aggregator 4 can be transmitted directly to the storage battery 21 of the consumer 2, or can be transmitted via the storage battery business operator 5. The storage battery business operator 5 is a manufacturer or distributor of the storage battery 21, and is a business operator that individually manages the storage battery 21 after delivery to the consumer 2.

[0018] FIG. 2 shows the daily power consumption pattern at consumer 2. The horizontal axis of FIG. 2 represents the time of the day. The left half is morning and the right half is afternoon. The vertical axis represents the power value. FIG. 2 shows pattern A and pattern B. Pattern A is the pattern of power generated by solar cell 20. Hereinafter, this will be referred to as generated power A. Pattern B is the pattern of private power demand at consumer 2. Hereinafter, this will be referred to as private power demand B.

[0019] In Figure 2, time T1 is the sunrise time and time T2 is the sunset time. The period from time T1 to time T2 is the time period in one day when solar cell 20 generates power. Time T3 is the time when reverse power discharge from storage battery 21 to retailer 3 begins. Time T4 is the time when reverse power discharge ends. Time T5 is the time when the remaining power stored in storage battery 21 runs out and starts purchasing power from retailer 3.

[0020] The above-mentioned times T3 and T4 will now be described. Times T3 and T4 are instructed by the aggregator 4. The aggregator 4 is configured as shown in Figure 3. The functions of the aggregator 4 are divided into a storage battery control unit, a mode switching unit, an information acquisition unit, and a timing determination unit.

[0021] The function of the aggregator 4 as a storage battery control unit is to remotely control the operation of the storage battery 21. In this embodiment, the storage battery 21 operates in two modes: a first mode and a second mode. The first mode is a mode for obtaining profits from selling electricity by reverse power flow discharge. In the first mode, reverse power flow discharge is performed when the electricity market price is higher than a threshold value, and reverse power flow discharge is not performed when the electricity market price is lower than the threshold value. The threshold value will be described later.

[0022] The second mode is a mode in which the remaining amount of stored electricity is stored in the storage battery 21 as much as possible in preparation for reverse power flow discharge in the first mode. However, priority is given to self-consumption. Therefore, in the second mode, when the amount of power generated by the solar cell 20 exceeds the amount of self-consumption, the surplus is stored in the storage battery 21, and when the amount of power generated by the solar cell 20 is less than the amount of self-consumption, the shortfall is made up by self-discharge from the storage battery 21. Note that even in the first mode, self-discharge from the storage battery 21 for self-consumption is performed as long as there is remaining power stored in the storage battery 21.

[0023] The function of the aggregator 4 as a mode switching unit is to switch the operation of the storage battery 21 between the first mode and the second mode described above. In this embodiment, basically, the second mode control is performed during the time period when the solar cell 20 is generating power. The first mode control is performed during the time period other than the time period when the second mode control is performed. More specifically, when the time period when the solar cell 20 is generating power ends, the second mode is switched to the first mode. When the reverse power flow discharge from the storage battery 21 ends, the first mode is switched to the second mode.

[0024] The function of the aggregator 4 as an information acquisition unit is to acquire various information necessary for controlling the storage battery 21. Information used to control the storage battery 21 includes the electricity market price, sunset and sunrise times, etc. Information on the performance of reverse power flow discharge from the storage battery 21 is also acquired. This is for the purpose of tallying up the price for purchasing electricity from the consumer 2.

[0025] The electricity market price is the price at which the retailer 3 procures electricity from the electricity market. This price is different from the regular electricity rate, which is the price at which the retailer 3 sells electricity to the consumer 2. As a general trend, the electricity market price fluctuates more frequently than the regular electricity rate. It also fluctuates throughout the day. The electricity market price is often high in the evening after sunset. This is because the demand for electricity in the electricity market as a whole is high during this time. Furthermore, due to factors such as the day of the week, the fluctuations in the electricity market price throughout the day are not the same every day. Regular electricity rates basically have a constant unit price. The unit price at which the retailer 3 purchases reverse flow discharged electricity from the consumer 2 is set slightly higher than the regular electricity rate. This is to make it more advantageous for the consumer 2 to sell the electricity stored in the storage battery 21 rather than consume it for themselves.

[0026] The level of the electricity market price is a dominant factor that greatly influences the profits that the retailer 3 obtains from purchasing reverse power discharge. On the other hand, the electricity market price is largely determined by the electricity demand in the electricity market as a whole. For this reason, a schedule of electricity market prices for approximately one day into the future is always made public in advance. The information acquisition unit obtains this information from the electricity market via the retailer 3. Alternatively, it may be obtained from the Internet (public information network). For example, the Japan Electric Power Exchange (JEPX: https: / / www.jepx.jp), a general incorporated association, always displays the electricity market price (spot market price) for the next day.

[0027] The times of sunset and sunrise for each date are publicly known information. The information acquisition unit acquires this information from the Internet. Information on the performance of reverse power flow discharge from the storage battery 21 is acquired from the smart meter 22.

[0028] The function of the aggregator 4 as a timing determination unit is to determine the times T3 and T4 to be instructed to the storage battery 21. The aggregator 4 sets a threshold for executing reverse flow discharge for the electricity market price. The timing determination unit compares the expected electricity market price acquired by the information acquisition unit with the threshold. Time T3 is determined to be the time when the electricity market price rises and exceeds the threshold. Time T4 is determined to be the time when the electricity market price falls and falls below the threshold. For the reasons mentioned above, time T3 is often set around dusk after sunset. Time T4 is often a little later. The times determined here also include date information.

[0029] FIG. 2 will be explained in light of the above-mentioned functions of the aggregator 4. In FIG. 2, the generated power A shows a pattern of increasing around noon. Around noon, the generated power A exceeds the private power demand B. At this time, the storage battery 21 is operating in the second mode. Therefore, the surplus E obtained by subtracting the private power demand B from the generated power A is stored in the storage battery 21. The remaining amount of power stored in the storage battery 21 increases as long as the generated power A exceeds the private power demand B.

[0030] As evening approaches and generated power A falls below private power demand B, the remaining amount of stored power in storage battery 21 begins to decrease. This is because private power demand B is met by discharging. At time T2 (sunset time), the operation of storage battery 21 is switched from second mode to first mode. This is because, for the reasons mentioned above, there are often times after evening that are favorable for reverse flow discharge. Then, at time T3, reverse flow discharge begins. Reverse flow discharge continues until time T4.

[0031] At time T4, reverse power flow discharge ends. At the same time, the operation of storage battery 21 switches from the first mode to the second mode. At this point, the remaining amount of stored power in storage battery 21 has decreased significantly compared to time T2. Thereafter, the remaining amount of stored power in storage battery 21 continues to decrease by an amount corresponding to the amount of private power demand B being covered.

[0032] In Figure 2, it is assumed that the remaining power stored in the storage battery 21 is depleted at time T5 when the date changes. Therefore, from that point on, the household's power demand B is met by purchasing power from the retailer 3. The power purchase continues until generated power A exceeds household's power demand B after time T1.

[0033] The above is an overview of the consumer's daily power consumption pattern. While the surplus power E is being stored in the storage battery 21, it is possible that the remaining storage capacity of the storage battery 21 may become full. In this case, the consumer 2 will provide the surplus power E as is for reverse power flow, independent of remote control from the aggregator 4. However, in this situation, the market price of electricity is not very high. For this reason, it is more advantageous for the retailer 3 to concentrate reverse power flow discharge as much as possible within the range from time T3 to time T4.

[0034] The control of the storage battery 21 described above is shown in a flowchart in Figure 4. In the flow of Figure 4, the aggregator 4 first acquires information (S1). "Acquiring information" here refers to acquiring the aforementioned electricity market price schedule. The sunrise time T1 and sunset time T2 can also be acquired at this time. It is desirable to acquire at least the next sunset time T2 at this time.

[0035] Next, the aggregator 4 determines whether there is an advantageous period based on the acquired electricity market price (S2). An advantageous period is a period during which it is advantageous for the retailer 3 for the consumer 2 to discharge electricity through reverse power flow. In other words, it is a period during which the electricity market price is above a threshold. If there is no advantageous period in the acquired scheduled date (S2: No), this flow ends.

[0036] If there is an advantageous period (S2: Yes), the scheduled timing is set (S3). The scheduled timing refers to the aforementioned times T3 and T4. The start of the advantageous period is set to time T3, and the end of the advantageous period is set to time T4. As mentioned above, the date is also set. Next, it is determined whether the scheduled timing that has been set is for today (S4). Here, time T3 in particular is the subject of the determination. If the date of the set time T3 is not today (S4: No), the process waits until the date changes.

[0037] If the date of time T3 is today (S4: Yes), it is determined whether the current time is before sunset (S5). This is done by comparing the current time with the sunset time T2 of that day, which is publicly known information. If it is before sunset (S5: Yes), the system waits until time T2. If it is not before sunset, that is, if time T2 has arrived (S5: No), the operating mode is set to the first mode (S6). This switching to the first mode due to sunset (S6) is only performed if time T3 exists on that day. This is because the determination of S4: Yes has been made.

[0038] Next, it is determined whether the current time is before the start of reverse flow discharge (S7). That is, it is determined whether the current time is before the set time T3 described above. If it is before time T3 (S7: Yes), the process waits until time T3. If time T3 has arrived (S7: No), discharge begins (S8). Discharge here refers to reverse flow discharge from the storage battery 21.

[0039] Next, it is determined whether the current time is before the start of reverse flow discharge (S9). That is, it is determined whether the current time is before the set time T4 described above. If it is before time T4 (S9: Yes), the system waits until time T4 is reached. That is, reverse flow discharge continues. If time T4 has been reached (S9: No), discharge is terminated (S10). That is, reverse flow discharge is terminated. Furthermore, the operation mode is set to the second mode, and the flow is terminated (S11). This flow realizes the operation shown in FIG. 2.

[0040] In the above flow, reverse flow discharge is performed from S7: No to S9: No. This means that reverse flow discharge is performed from time T3 to time T4 in FIG. 2. This is the time period during which the market price of electricity is higher than the threshold. Therefore, performing reverse flow discharge during this time period is advantageous for the retailer 3. The control shown in FIG. 2 and FIG. 4 is performed by the aggregator 4 on the storage batteries 21 of multiple consumers 2. Note that if the remaining amount of stored electricity in the storage batteries 21 runs out during reverse flow discharge, the reverse flow discharge is terminated without waiting for time T4.

[0041] In the above flow, information acquisition in S1 may be performed continuously or periodically at certain intervals. It is desirable to perform it at least once a day at a fixed time. The determination in S4 as to whether it is today or not may be made on a calendar date, or the next 24 hours from the time of the determination may be considered as today. If it is not today (S4: No), it is possible to return to S1 and start over from acquiring information.

[0042] As described above in detail, according to this embodiment, reverse flow discharge is concentrated during advantageous time periods when the electricity purchase price is high, under the control of the aggregator 4. Therefore, control in the second mode is performed mainly during the daytime to accumulate the remaining amount of electricity stored in the storage battery 21, and control in the first mode is performed mainly at night to prepare for the arrival of advantageous time periods for reverse flow discharge. In this way, a storage battery control system 1 is realized in which the aggregator 4 remotely controls the storage batteries 21 of multiple consumers 2, and can provide each consumer 2 with a greater profit from selling electricity.

[0043] The threshold value is usually set higher than the electricity charges to consumers 2. This is because when the electricity market price is rising, it is more advantageous for the retailer 3 to purchase electricity from consumers 2 than to procure electricity from the electricity market. The threshold value may or may not be determined in advance as a fixed value. If it is not a fixed value, it only needs to be determined by the time the advantageous period is determined in S2 of FIG. 4. The threshold value may be determined by the aggregator 4 in accordance with the trend of fluctuations in the electricity market price, or it may be determined by the consumers 2.

[0044] Note that this embodiment is merely an example and does not limit the disclosed technology in any way. Therefore, the disclosed technology can naturally be improved and modified in various ways without departing from the spirit and scope of the invention. For example, the remote operation of the storage battery 21 by the aggregator 4 may be performed by sending an operation command from the aggregator 4 to the storage battery 21 at the appropriate timing, such as time T3 or time T4, or by transmitting only the determined timing, such as time T3 or time T4, from the aggregator 4 and allowing autonomous control within the consumer 2.

[0045] The switch to the second mode in S11 of FIG. 4 does not have to be immediately after the end of discharge in S10. The switch to the second mode should be made by sunrise time T1 at the latest. For the sunrise time T1 and sunset time T2, in addition to using publicly available information, the actual time at the location of consumer 2 may also be used. The actual time at the location of consumer 2 may be estimated from the power generation history of the solar cell 20 of consumer 2. The sunrise time T1 is not essential for control. [Explanation of symbols]

[0046] 1 Battery control system 2 Consumer 3. Retailers 4. Aggregators 20 Solar Cells 21 Storage battery 22 Smart Meter

Claims

1. A storage battery control system in which an aggregator remotely controls operation of a storage battery in a consumer having a solar cell and a storage battery, The aggregator a battery control unit that controls operation of the storage battery in one of a first mode in which reverse power discharge is performed from the storage battery when the market price of electricity is higher than a threshold value and reverse power discharge is not performed from the storage battery when the market price of electricity is lower than the threshold value, and a second mode in which, when the amount of power generated by the solar cell exceeds self-consumption, the surplus is stored in the storage battery and, when the amount of power generated by the solar cell is less than self-consumption, the shortfall is made up by self-discharge from the storage battery; a mode switching unit that switches between the first mode and the second mode, The mode switching unit performing the second mode control during a time period when the solar cell is generating power; A battery control system that performs the first mode control during a time period other than a time period during which the second mode control is performed.

2. 2. The battery control system according to claim 1, wherein the mode switching unit: When the time period during which the solar cell generates power ends, the second mode is switched to the first mode, The battery control system switches from the first mode to the second mode when reverse power flow discharge from the battery is completed.

3. The battery control system according to claim 1 or 2, The aggregator an information acquisition unit that acquires a forecast of electricity market prices for at least one day; a timing determination unit that determines a start time and an end time of reverse flow discharge in the first mode based on the information acquired by the information acquisition unit, The mode switching unit switches from the second mode to the first mode when the time period in which the solar cell is generating electricity ends only if the start time occurs within the next 24 hours from that time.

4. 4. The battery control system according to claim 3, wherein the information acquisition unit: A battery control system that obtains at least the next sunset time from a public information network.

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