Energy Management System

Abstract

To provide an energy management system capable of reducing costs of power.SOLUTION: An energy management system 1 controls the buying and selling of grid power due to the charge / discharge of a power storage device 2 capable of storing grid power from an electric power grid 3 and power generated by a power generating device 4. The energy management system 1 includes: a prediction unit 11 that predicts, over a predetermined period of time, a time transition of an amount of power generation and a time transition of an amount of power demand; a planning unit 12 that plans an amount and timing of buying and selling of grid power in a predetermined period of time on the basis of predicted power supply and demand data and power buying and selling price data; and a control unit 13 that controls an amount and timing of the buying and selling of grid power on the basis of the power buying and selling plan. The planning unit 12 is configured to plan an amount and timing of the buying and selling of grid power so that the buying and selling of grid power is substantially completed on a changeover time.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an energy management system. [Background technology]

[0002] Patent Document 1 discloses a charge / discharge control device that controls the charge / discharge of a storage battery for charging grid power. In this charge / discharge control device, the amount and timing of charging / discharging the storage battery are controlled according to the magnitude relationship between the grid power purchase price and the power selling price, as well as the predicted value of the power demand of the consumer and the predicted value of the power generation amount of the power generation device. In addition, a control is proposed in which grid power is purchased and charged into the storage battery during low price time periods when the power purchase price is low in order to cover the power shortage expected during high price time periods when the power purchase price is high. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-4529 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the predicted value of the power demand of the consumer and the predicted value of the power generation amount of the power generation device may fluctuate according to the change of the situation. Therefore, it is considered that the actual power shortage may largely deviate from the predicted power shortage. In such a case, there is a concern that it may lead to wasteful purchase of power or insufficient purchase of power. As a result, there is room for improvement in terms of sufficient reduction of power costs.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an energy management system that can reduce power costs. [Means for solving the problem]

[0006] One aspect of the present invention is a power storage device (2, 20) capable of storing system power from a power grid (3) and power generated by a power generation device (4). Has The above grid power Electricity purchase An energy management system (1) for controlling a prediction unit (11) configured to predict a time transition of an amount of power generated by the power generation device and a time transition of an amount of power demand in a consumer (5) during a predetermined period; Based on the power supply and demand forecast data predicted by the forecasting unit and the power buying and selling price data related to the unit price of purchasing power from the power grid, Electricity purchase A planning unit (12) for planning the amount and timing of The above planning department planned Electricity purchase Based on the plan, Electricity purchase and a control unit (13) for controlling the amount and timing of The prediction unit is configured to sequentially update the power supply and demand prediction data within the predetermined period, The predetermined period includes a low power purchase price time period in which the power purchase price is relatively low, and a high power purchase price time period in which the power purchase price is higher than the low power purchase price time period, the planning unit calculates an amount of power shortage during the high power purchase price time period based on the time transition of the amount of power generated by the power generation device and the time transition of the amount of power demand at the consumer predicted by the prediction unit, and plans the power purchase plan such that the amount of power shortage is purchased from the power grid during the low power purchase price time period and charged into the power storage device; The planning unit is capable of changing the power purchase plan before a purchase price switching time when the low power purchase price time period is switched to the high power purchase price time period, The planning unit is configured to derive a charging time for the power storage device to charge the amount of power shortage from the amount of power shortage and the optimal charging power, and to plan a time obtained by subtracting the charging time from the purchase price switching time as a start time for purchasing the grid power to charge the power storage device. , in energy management systems. Another aspect of the present invention is an energy management system (1) having a power storage device (2, 20) capable of storing system power from a power grid (3) and power generated by a power generation device (4), and controlling a sale of the system power, a prediction unit (11) configured to predict a time transition of an amount of power generated by the power generation device and a time transition of an amount of power demand in a consumer (5) during a predetermined period; a planning unit (12) that plans an amount and timing of the sale of the grid power during the predetermined period based on power supply and demand forecast data predicted by the prediction unit and power buying and selling price data related to a unit price of the power sold to the power grid; a control unit (13) that controls an amount and a timing of selling the grid power based on the power selling plan planned by the planning unit, The prediction unit is configured to sequentially update the power supply and demand prediction data within the predetermined period, the predetermined period includes a low power selling price time period in which the power selling price is relatively low, and a high power selling price time period in which the power selling price is higher than the low power selling price time period, the planning unit calculates an amount of surplus power based on the time transition of the amount of power generated by the power generation device and the time transition of the amount of power demand at the consumer predicted by the prediction unit, calculates a planned amount of power sale from the amount of surplus power, and plans the power selling plan such that the planned amount of power sale is discharged from the power storage device and sold to the power grid during the high power selling price time period; The planning unit is capable of changing the power selling and purchasing plan before a selling price switching time when the low power selling price time period is switched to the high power selling price time period, The planning unit is configured to derive a discharge time for the planned amount of power to be sold from the power storage device based on the planned amount of power to be sold and the optimal discharge power, and to plan the time obtained by subtracting the discharge time from the selling price switching time as the start time for discharging power from the power storage device and selling it to the power grid. Effect of the Invention

[0007] In the energy management system, the planner is configured to plan the amount and timing of the buying and selling of the grid power so that the buying and selling of the grid power is substantially completed at the switching time when the unit price of the grid power is switched. This increases the possibility that the power buying and selling plan can be changed before the actual buying and selling of power starts when a situation changes. As a result, it is possible to suppress buying and selling of unnecessary power, and to reduce power costs.

[0008] As described above, according to the above aspect, it is possible to provide an energy management system that can reduce power costs. In addition, the symbols in parentheses described in the claims and the means for solving the problems indicate a correspondence with the specific means described in the embodiments described below, and do not limit the technical scope of the present invention. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a conceptual explanatory diagram of an energy management system according to a first embodiment. [Diagram 2] 1A is a diagram showing time trends of the electricity purchase price and the electricity selling price in the first embodiment, and FIG. 1B is a diagram showing electricity supply and demand forecast data. [Diagram 3] FIG. 4 is a flow diagram of processing in a planning unit in the first embodiment. [Figure 4] 1A is a diagram showing time trends of the power purchase price and the power selling price in the first embodiment, and FIG. 1B is a diagram showing power supply and demand forecast data and a power purchase plan. [Diagram 5] 4 is a diagram showing power supply and demand forecast data at 3:00 in the first embodiment. [Figure 6] 13A is a diagram showing time trends of the power purchase price and the power selling price in the second embodiment, and FIG. 13B is a diagram showing power supply and demand forecast data and a power purchase plan. [Figure 7] 13A is a diagram showing time trends of the power purchase price and the power selling price in the third embodiment, and FIG. 13B is a diagram showing power supply and demand forecast data and a power purchase plan. [Figure 8]FIG. 13 is a conceptual explanatory diagram of an energy management system according to a fourth embodiment. [Figure 9] 13A is a diagram showing time trends of the power purchase price and the power selling price in embodiment 4, and FIG. 13B is a diagram showing power supply and demand forecast data and a power purchase plan. [Figure 10] 13A is a diagram showing time trends in the electricity purchase price and the electricity selling price in embodiment 5, and FIG. 13B is a diagram showing electricity supply and demand forecast data. [Figure 11] FIG. 13 is a flow diagram of processing in a planning unit in the fifth embodiment. [Figure 12] 13A is a diagram showing time trends in the electricity purchase price and the electricity selling price in embodiment 5, and FIG. 13B is a diagram showing electricity supply and demand forecast data and an electricity selling plan. [Figure 13] 13 is a diagram showing power supply and demand forecast data as of 2 p.m. in the fifth embodiment. [Figure 14] 13A is a diagram showing time trends in the electricity purchase price and the electricity selling price in embodiment 6, and FIG. 13B is a diagram showing electricity supply and demand forecast data and an electricity selling plan. [Figure 15] 13A is a diagram showing time trends in the electricity purchase price and the electricity selling price in embodiment 7, and FIG. 13B is a diagram showing electricity supply and demand forecast data and an electricity selling plan. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Embodiment 1) An embodiment of an energy management system will be described with reference to FIGS. 1 to 5. FIG. 1 and 2, an energy management system 1 according to this embodiment is a system that controls buying and selling of grid power accompanying charging and discharging of a power storage device 2. The power storage device 2 can store grid power from a power system 3 and power generated by a power generation device 4.

[0011] As shown in FIG. 1, the energy management system 1 includes a prediction unit 11, a planning unit 12, and a control unit 13. The prediction unit 11 predicts the time transition of the amount of power generated by the power generation device 4 (see the dashed curve in FIG. 2(b)) and the time transition of the amount of power demand in the consumer 5 (see the solid curve in FIG. 2(b)) over a predetermined period.

[0012] The planner 12 plans the amount and timing of buying and selling of grid power for a predetermined period based on the power supply and demand forecast data and the power buying and selling price data. The power supply and demand forecast data is data on power supply and demand predicted by the forecaster 11 (see FIG. 2(b)). The power buying and selling price data is data on at least one of the unit price of purchasing power from the power grid 3 and the unit price of selling power to the power grid 3 (see FIG. 2(a)). The control unit 13 controls the amount and timing of buying and selling of grid power based on the power buying and selling plan prepared by the planner 12.

[0013] The planning unit 12 is configured to plan the amount and timing of buying and selling of grid power so that buying and selling of grid power is substantially completed at the switching time when the unit price of buying and selling of grid power is switched, as shown in Fig. 2. Note that buying and selling of grid power means one or both of buying power from the power grid 3 and selling power to the power grid 3.

[0014] In this embodiment, the power storage device 2 may be a storage battery such as a lithium ion battery. The power generation device 4 may be, for example, a solar power generation device, a wind power generation device, a hydroelectric power generation device, etc. In this embodiment, a case where a solar power generation device is used as the power generation device 4 will be described.

[0015] The prediction unit 11, the planning unit 12, and the control unit 13 are each, for example, a processor that executes a control program stored in the energy management system 1, and can be configured by a microcomputer, a dedicated circuit, or the like.

[0016] The prediction unit 11 calculates power supply and demand prediction data based on the power generation record of the power generation device 4, the power demand record of the consumer 5, etc. That is, the prediction unit 11 predicts the power supply and demand for a predetermined period to be predicted based on the relationship between various factors such as season, temperature, time, day of the week, weather forecast, etc., and past power generation records, past power usage records, etc. The prediction unit 11 obtains external data via a communication unit connected to a network such as the Internet or a LAN. The communication by this communication unit can be either wired communication or wireless communication, or both.

[0017] The power supply and demand forecast data calculated by the prediction unit 11 is input to the planning unit 12. The planning unit 12 further acquires power buying and selling price data from outside. The planning unit 12 also acquires external data via a communication unit connected to a network. This communication unit can also be either one or both of wired communication and wireless communication.

[0018] Furthermore, the planner 12 acquires information about the power storage device 2, such as the characteristics and state of the power storage device 2. Here, examples of the information about the power storage device 2 include the charge / discharge rate, charge / discharge power, device temperature, and the amount of power currently being charged of the power storage device 2. The planner 12 is directly or indirectly connected to the power storage device 2 by either or both of wired communication and wireless communication. The information about the power storage device 2 is also used to plan the amount and timing of buying and selling grid power.

[0019] As described above, the planner 12 plans the amount and timing of grid power trading so that grid power trading is substantially completed at the switching time when the unit price of grid power trading is switched. Here, "grid power trading is substantially completed at the switching time" includes, for example, not only the case where the completion time of grid power trading coincides with the switching time, but also the case where the completion time is somewhat earlier or later than the switching time. For example, the case where the completion time of grid power trading is within one hour either side of the switching time can also be included in the case where "grid power trading is substantially completed at the switching time." Alternatively, "the buying and selling of grid power is substantially completed at the switching time" may also include, for example, a case where 90% or more of the planned amount of power buying and selling is completed at the switching time.

[0020] The planner 12 also derives the charge / discharge time from the planned amount of grid power buying and selling and the optimal charge / discharge power. Then, the time obtained by subtracting the charge / discharge time from the switching time is planned as the start time of buying and selling of grid power. Here, the optimal charge / discharge power can be, for example, the maximum charge / discharge power of the storage device 2, the charge / discharge power that minimizes the loss of the storage device 2, or the maximum contracted power of the grid power. Note that the charge / discharge time means the charging time or the discharging time.

[0021] The power trading plan planned by the planner 12 is transmitted to the controller 13. Based on this power trading plan, the controller 13 controls the amount and timing of buying and selling of grid power. Specifically, the control unit 13 can control the amount and timing of buying and selling of grid power by using a charge / discharge signal that the control unit 13 transmits to the power storage device 2. The charge / discharge signal is, for example, a signal that instructs the power storage device 2 on what time and for how long to charge / discharge. The charge / discharge signal can be transmitted, for example, by either one or both of wired communication and wireless communication.

[0022] Next, an example of a control method by the energy management system 1 of this embodiment will be described with reference to Figs. 2 to 5. In this embodiment, as shown in Fig. 2(a), an example is shown in which the power purchase price of grid power fluctuates but the power selling price does not fluctuate. Also, here, it is assumed that the power purchase price is always higher than the power selling price. Also, the power buying and selling plan planned by the planning unit 12 is a plan of the amount and timing of power purchase, that is, a power buying plan. The predetermined period for which the prediction unit 11 predicts power supply and demand is 24 hours from the current time. However, the predetermined period is not limited to this.

[0023] As shown in Figure 2(a), the specified period includes low power purchase price time periods (in this embodiment, from midnight to 9:00 and from 21:00 to 24:00) when the power purchase price is relatively low, and high power purchase price time periods (in this embodiment, from 9:00 to 21:00) when the power purchase price is higher than the low power purchase price time periods.

[0024] First, an outline of the processing flow in the planning unit 12 will be described with reference to FIG. As shown in step S1 of the figure, the planning unit 12 calculates the amount of energy shortage during the high power purchase price time period based on the power supply and demand forecast data predicted by the prediction unit 11 (see FIG. 2(b)). Next, in step S2, the planning unit 12 calculates the charging time (e.g., 6 hours) from the amount of energy shortage calculated in step S1 and the optimal charging speed. Next, in step S3, the planning unit 12 calculates the time (e.g., 3:00) obtained by subtracting the charging time (e.g., 6 hours) from the purchasing price switching time (e.g., 9:00) as the power purchase start time. The processing by this planning unit 12 will be explained below.

[0025] The planning unit 12 calculates the amount of energy shortage during the high power purchase price period based on the time trend of the amount of power generated by the power generation device 4 predicted by the prediction unit 11 (see the dashed curve in Figure 2(b)) and the time trend of the amount of power demand at the consumer 5 (see the solid curve in Figure 2(b)).

[0026] Then, the planner 12 creates an electricity purchase plan such that the shortage amount of electricity is charged from the power grid 3 to the electricity storage device 2 during the low electricity purchase price time period. At the same time, the electricity purchase plan is created such that electricity purchase is completed at the purchase price switch time (9:00 in this embodiment) when the low electricity purchase price time period switches to the high electricity purchase price time period.

[0027] The planning unit 12 calculates the start time of grid power purchase so that the power purchase will be completed at the purchase price switching time as follows. First, the charging time is derived from the planned purchase amount of grid power, which is also the calculated power shortage, and the optimal charging power. Then, the time obtained by subtracting the charging time from the purchase price switching time is calculated as the start time of grid power purchase. In this way, the planning unit 12 plans the power purchase plan.

[0028] The power supply and demand prediction data by the prediction unit 11 is updated successively. That is, the power supply and demand prediction data is predicted based on information that may change, such as weather forecasts and temperature. Therefore, the power supply and demand prediction data may change with changes in such information. The power supply and demand prediction data shown in FIG. 2(b) is the power supply and demand prediction data as of 0:00.

[0029] As shown in the figure, the predicted value of the power demand changes over a predetermined period. The predicted value of the power generation also changes over a predetermined period. In cases where the power generation device 4 is a solar power generation device, the predicted value of the power generation is high during the day and is zero at night.

[0030] During times when the amount of power generated falls short of the amount of power demand, the power of the power storage device 2 is used or purchased from the power grid 3. On the other hand, during times when the amount of power generated exceeds the amount of power demand, surplus power is generated, which is either charged to the power storage device 2 or sold to the power grid. Here, the amount of charge in the power storage device 2 at midnight is assumed to be zero. Also, the surplus power is assumed to be charged to the power storage device 2 and not sold.

[0031] Assume that at midnight, the prediction unit 11 has obtained power supply and demand forecast data as shown in Fig. 2(b). According to this power supply and demand forecast data, there are times during the high power purchase price period when the power demand can be met with the amount of power generated by the power generation device 4 and when surplus power is generated. Area A1 in Fig. 2(b) represents the amount of surplus power at this time. Area A2 in the figure represents the amount of power demand that is met by power generation. Areas A5 and A6 in the figure represent the amount of power purchased from the grid.

[0032] On the other hand, there are some time periods during which the power demand cannot be met by the amount of power generated by the power generation device 4. Areas A3 and A4 in the figure represent the shortage of power that cannot meet the power demand by power generation during the high power purchase price time period. However, it is possible to meet at least a part of this area A4 with the surplus power stored in the power storage device 2 (see area A1).

[0033] That is, the surplus power can be charged to the power storage device 2. If a sufficient amount of surplus power is generated, at least a part of the power shortage in the time period after the surplus power is generated can be covered by the power stored in the power storage device 2. However, the power shortage in the time period before the surplus power is generated cannot be covered unless power is stored in the power storage device 2. Furthermore, if the power shortage in the time period when the power purchase price is high is to be covered directly by grid power, the power cost will be high.

[0034] Therefore, as shown in Fig. 4, grid power is purchased during the low power purchase price time slot before 9:00 and stored in the power storage device 2. Area A7 in Fig. 4(b) represents the amount of grid power purchased for charging the power storage device 2. The power stored in the power storage device 2 covers the power shortage during the high power purchase price time slot. In other words, during the high power purchase price time slot, the power demand that cannot be covered by power generation by the power generation device 4 is discharged from the power storage device 2 and supplied to the consumer 5. In this way, the planning unit 12 of the energy management system 1 predicts the amount of power shortage during the high power purchase price time slot and makes a plan to purchase that amount of power during the low power purchase price time slot.

[0035] 4(b), above the graph, charging and discharging of the power storage device 2 are conceptually shown. The arrows in the power storage device 2 indicate charging with upward arrows and discharging with downward arrows. As described above, the power purchase plan is created based on the power supply and demand forecast data as of midnight.

[0036] However, as described above, the power supply and demand forecast data may change over time. That is, the power supply and demand forecast data fluctuates with changes in various factors, such as changes in the weather forecast, changes in temperature, etc. For example, the power supply and demand forecast data at 3:00 may fluctuate to a forecast as shown in Fig. 5. According to the power supply and demand forecast data shown in the figure, the amount of power generated exceeds the amount of power demanded throughout the entire period of high power purchase prices.

[0037] Such fluctuations in the power supply and demand forecast data may occur, for example, when the weather forecast changes from cloudy at midnight to sunny at 3:00. In this case, the forecast for the amount of power generated by the photovoltaic power generation device increases significantly. In addition, for example, if consumer 5 is an ordinary household, the forecast for sunny weather may predict that the probability of the household going out will increase, resulting in a prediction that the household power demand will decrease.

[0038] Thus, in the power supply and demand forecast data shown in Fig. 5, the amount of power generated exceeds the amount of power demanded during the high power purchase price time period (here, 9:00 to 21:00). In other words, according to this power supply and demand forecast data, there will be no power shortage during the high power purchase price time period. Therefore, if the power purchase plan (see Fig. 4(b)) made at midnight is executed as is, excess power will be purchased.

[0039] Therefore, at 3 o'clock, the planning unit 12 re-plans the power purchase plan based on the power supply and demand forecast data predicted by the prediction unit 11. In the example shown here, the plan is to not purchase power. In addition, at a later time, the power supply and demand forecast data predicted by the prediction unit 11 may further fluctuate, and the planning unit 12 re-plans the power purchase plan in response to the fluctuation.

[0040] In this way, the power supply and demand forecast data predicted by the prediction unit 11 may fluctuate from moment to moment. Therefore, if grid power is purchased based on power supply and demand forecast data predicted in an early time period, power that is not actually required may be purchased.

[0041] Therefore, from the viewpoint of reducing power costs, it is desirable to plan and execute a power purchase plan based on the most recent power supply and demand forecast data possible, under the premise that power will be purchased during a low power purchase price time slot. Therefore, as described above, when the planner 12 plans the power purchase plan, it plans to purchase power during the last time slot of a low power purchase price time slot, as shown in Fig. 4. In other words, it plans the power purchase plan so that power purchases are completed at the purchase price switch time when the low power purchase price time slot switches to the high power purchase price time slot.

[0042] Specifically, as described above, the time obtained by subtracting the charging time from the purchasing price switching time is planned as the grid power purchasing start time. The charging time is calculated based on the optimal charging / discharging power of the power storage device 2 and the planned planned power purchase amount. In this embodiment, the optimal charging power is the maximum charging power of the power storage device 2. The maximum charging power is an inherent value of the power storage device 2, and is the maximum power that can be charged to the power storage device 2.

[0043] The optimum charging power may be, for example, the minimum-loss charging power of the storage device 2. The minimum-loss charging power is an inherent value of the storage device 2, and is the charging power at which the loss occurring during charging is the lowest. Usually, this minimum-loss charging power is a value smaller than the maximum charging power.

[0044] In this way, suppose that at midnight, the planning unit 12 calculates the charging time to be, for example, six hours. In this case, the power purchase plan has a power purchase start time of 3:00. Therefore, in this embodiment, as shown in Fig. 4(b), the plan is to purchase the amount of power obtained by adding the maximum charging power to the power demand amount from 3:00 to 9:00.

[0045] Then, as shown in Fig. 5, if there is no power shortage during the high power purchase price time period in the power supply and demand forecast data predicted by the prediction unit 11 at 3:00, the power purchase plan also changes. Then, the originally planned purchase of grid power by the control unit 13 can be canceled. This is because the plan has changed to not purchasing power before the power purchase start time (3:00 in this case) planned at midnight has passed. As a result, unnecessary power purchases can be prevented, and power costs can be reduced.

[0046] Next, the effects of this embodiment will be described. In the above energy management system 1, the planner 12 is configured to plan the amount and timing of power purchases so that the purchase of grid power is substantially completed at the purchase price switching time. This increases the possibility that the power purchase plan can be changed before the power purchase actually starts when a situation changes.

[0047] In other words, in the above example, let us suppose that the power purchase timing was planned to be early, such as between midnight and 6:00. Then, even if the power supply and demand forecast data changes to that shown in FIG. 5 at 3:00, power purchases will have already been made at 3:00, resulting in unnecessary power purchases. In contrast, if the power purchase timing had been planned between 3:00 and 9:00, the unnecessary power purchases in the above case can be avoided. As a result, it is possible to reduce unnecessary electricity purchases, and to reduce electricity costs.

[0048] The planner 12 plans the amount and timing of power purchases so that the purchase of grid power is substantially completed at the switching time. This makes it easier to change the power purchase plan in response to changes in the situation before the power purchase based on the power purchase plan is executed. In this case, the control unit 13 can control the amount and timing of power purchases based on the changed power purchase plan. This makes it possible to suppress excess grid power purchases and reduce power costs.

[0049] The planner 12 also derives the charge / discharge time from the planned amount of grid power purchased and the optimal charge / discharge power. Then, the time obtained by subtracting the charge / discharge time from the switching time is planned as the start time of grid power purchase. This makes it easy to accurately plan the power purchase plan so that power purchase is completed just before the switching time during the low power purchase price time period. As a result, it is possible to effectively suppress unnecessary power purchases and further reduce power costs.

[0050] In this embodiment, the power purchase plan is created so that the power purchase is completed at the power purchase price switching time, as shown in Fig. 4(b). Therefore, when the power purchase price fluctuates during a certain period, the power cost can be effectively reduced.

[0051] As described above, according to the present embodiment, it is possible to provide an energy management system that can reduce power costs.

[0052] (Embodiment 2) This embodiment is a case where the optimum charging power for the power storage device 2 changes during charging, as shown in FIG. In this embodiment, as in the first embodiment, a power purchase plan may be made to purchase power to be charged into the power storage device 2 from the power grid during a low power purchase price period in order to cover the power shortage during the high power purchase price period. In this case, the amount of power to be purchased is the amount of power to be charged into the power storage device 2 added to the power demand of the consumer 5.

[0053] Here, as in the first embodiment, if a plan is made to purchase power by adding the maximum charging power of the power storage device 2 to the power demand, it is assumed that the amount of purchased power may exceed the maximum contracted power with the power grid (e.g., a power company) when the power demand becomes relatively large. In such a case, therefore, a power purchase plan is made by setting the upper limit value of the purchased power to the maximum contracted power. In this case, when the maximum contracted power is reached, the charging power to the power storage device 2 becomes relatively small. Since the charging time becomes longer accordingly, a power purchase plan is made by bringing forward the power purchase start time so that the power storage device 2 can be charged with the shortage amount of power.

[0054] The maximum contracted power may be the maximum power that can be purchased at a specified power purchase price, for example, in addition to the maximum purchased power contracted with the power grid.

[0055] In addition, among the symbols used in the second and subsequent embodiments, the same symbols as those used in the previous embodiments represent the same components, etc. as those in the previous embodiments, unless otherwise specified. This embodiment also has the same effects as the first embodiment.

[0056] (Embodiment 3) As shown in FIG. 7, this embodiment is an embodiment of an energy management system 1 in which a hydrogen storage device is used as the electricity storage device 20.

[0057] A hydrogen storage device is a device that can convert electricity into hydrogen and store it, and also convert the stored hydrogen into electricity. For example, a hydrogen storage device can include a hydrogen conversion device that converts electricity into hydrogen, a fuel cell that converts hydrogen into electricity, and a hydrogen tank that stores hydrogen.

[0058] As the hydrogen conversion device, for example, an SOEC (i.e., a solid oxide electrolysis cell) can be used. As the fuel cell, for example, an SOFC (i.e., a solid oxide fuel cell) can be used. In addition, for example, a rSOFC (i.e., a reversible solid oxide fuel cell) capable of converting hydrogen to and from electricity can be included in the hydrogen storage device as a device having both the functions of a hydrogen conversion device and a fuel cell.

[0059] In this embodiment, the power storage device 20 is also used to store power to cover the power shortage during the high power purchase price period (see areas A3 and A4 in FIG. 7). However, compared to a storage battery such as a lithium-ion battery, the hydrogen storage device has a slower response to charging and discharging. Taking this difference in response into account, the planner 12 of the energy management system 1 needs to create the power purchase plan.

[0060] In this embodiment, the method of planning the power purchase plan by the planner 12 of the energy management system 1 is substantially the same as in embodiment 1. However, the method of calculating the charging time to the power storage device 20 is different from that in embodiment 1, and as a result, the method of calculating the power purchase start time is different.

[0061] That is, the charging rate of the electricity storage device 20, which is a hydrogen storage device, does not increase immediately after charging starts, but increases gradually. Therefore, as shown in Fig. 7(b), the electricity purchase plan is planned so that the amount of electricity purchased for charging the electricity storage device 20 gradually increases immediately after charging starts. Area A70 in the figure represents the amount of electricity purchased for charging the electricity storage device 20. Also, since the charging rate cannot be suddenly reduced when charging ends, the electricity purchase plan is planned so that the charging rate is gradually reduced so that charging is substantially completed at the purchase price switching time (9:00 in the example shown in Fig. 7).

[0062] The optimum charging power for optimally charging such a hydrogen storage device can be determined from various viewpoints. That is, for example, the optimum charging power can be the charging power according to a charging profile that allows charging to be completed in the shortest time. Alternatively, for example, the optimum charging power can be the charging power according to a charging profile that allows charging to be performed with the least loss. In the case of a hydrogen storage device such as this embodiment, these optimum charging powers usually vary over time.

[0063] The planner 12 may calculate the charging time as the time when the integral value of the optimal charging power, which changes with time, becomes the planned charging amount (i.e., the amount of power shortage during the high power purchase price time period).Then, the planner 12 may plan the time obtained by subtracting this charging time from the purchase price switching time as the power purchase start time.

[0064] Taking into consideration the above-mentioned storage characteristics of the hydrogen storage device, the power purchase plan shown in Fig. 7(b) calculates the charging time to be 4 hours and sets the power purchase start time to 5:00 a.m. However, it goes without saying that this is merely one example.

[0065] A case where electricity purchase, charging, and discharging are performed according to the electricity purchase plan shown in FIG. 7(b) will be described. First, at 5:00, which is the power purchase start time, purchasing of grid power for charging the power storage device 20 is started. In other words, purchasing of power equal to the power demand plus the charging amount is started at 5:00. Of the purchased power, the amount that exceeds the power demand by the consumer 5 is charged to the power storage device 20. This charging is performed by converting a part of the purchased power into hydrogen by a hydrogen conversion device in the hydrogen storage device and storing it in a hydrogen tank.

[0066] The charging of the power storage device 20 is completed during the low power purchase price time zone. That is, the purchase of power from the grid is completed at the time when the power purchase price changes (here, 9:00). After that, during the high power purchase price time zone from 9:00 to 21:00, there is a time zone in which the power demand is greater than the power generation (see areas A3 and A4). During this time zone, power is supplied from the power storage device 20 to the consumer 5. That is, the power shortage is covered by discharging the power storage device 20. At this time, hydrogen stored in the hydrogen tank is converted into power by a fuel cell, and the power is supplied to the consumer 5.

[0067] Furthermore, during the high power purchase price period, there are also time periods when the amount of electricity generated exceeds the amount of electricity demanded, and the surplus electricity at this time (see area A1) can also be charged to the electricity storage device 20, which is made up of a hydrogen storage device. Even after this surplus electricity is generated, there are time periods during the high power purchase price period when there is a power shortage (see area A4). This power shortage is similarly covered by the electricity in the electricity storage device 20.

[0068] In this way, in this embodiment, the power purchase plan at midnight can be planned, but as in the first embodiment, the power supply and demand forecast data can change from moment to moment. When the power supply and demand forecast data changes as shown in Fig. 5, there is no power shortage, and therefore it becomes unnecessary to charge the power storage device 20, i.e., to store hydrogen in the hydrogen storage device. Accordingly, the power purchase plan is changed and power purchases are canceled. Other than that, it is the same as the first embodiment.

[0069] In this embodiment, it is possible to effectively create a power purchase plan when a hydrogen storage device is used as the power storage device 20. In addition, the present embodiment has the same functions and effects as the first embodiment. In addition to the hydrogen storage device, other possible examples of the power storage device 20 with a slow charge / discharge response include a methane storage device, a pumped-storage power generation device, etc. In these cases, it is possible to create a power purchase plan similar to that of this embodiment.

[0070] (Embodiment 4) This embodiment is an embodiment of the energy management system 1 in which both a storage battery and a hydrogen storage device are used as the power storage devices 2, 20, as shown in Figs. For example, when the amount of power shortage during a time period when the power purchase price is high exceeds the amount of power that can be stored in the storage battery, a hydrogen storage device may be used as the supplementary power storage device 20. In this embodiment, the storage battery 2 is also referred to as the hydrogen storage device 20.

[0071] In this embodiment, the planning unit 12 plans how much power to charge each of the two power storage devices 2, 20 during the low power purchase price time period. Then, the charging time of each of the power storage devices 2, 20 is calculated from the planned charging amount and the device characteristics of each device. Based on this, the time obtained by subtracting the charging time of each of the power storage devices 2, 20 from the purchase price switching time is calculated as the power purchase start time for charging each of the power storage devices 2, 20.

[0072] 9(b), an area A7 represents the amount of power from the grid power purchased for charging the storage battery 2. Also in the same figure, an area A70 represents the amount of power from the grid power purchased for charging the hydrogen storage device 20.

[0073] As shown in the figure, the start time of electricity purchases for charging the storage battery 2 and the start time of electricity purchases for charging the hydrogen storage device 20 may differ from each other. In the figure, an example is shown in which the former is around 7:00 and the latter is around 5:00. The rest is the same as in the first and third embodiments. This embodiment also has the same effects as the first and third embodiments.

[0074] (Embodiment 5) This embodiment is an embodiment in which the planner 12 plans a power selling plan as shown in Figs. 10 to 13. As a premise of this embodiment, the electricity selling price fluctuates during a specified period. That is, the specified period has low electricity selling price time periods and high electricity selling price time periods. The low electricity selling price time periods are time periods when the electricity selling price is relatively low, and the high electricity selling price time periods are time periods when the electricity selling price is higher than the low electricity selling price time periods. In the example shown in FIG. 10(a), the high electricity selling price time period is from 12:00 to 20:00, and the other times are low electricity selling price time periods. Also, here, it is assumed that the electricity purchase price is always higher than the electricity selling price.

[0075] In this embodiment, as shown in FIG. 10(b), the amount of power generated exceeds the amount of power demand in the morning, resulting in surplus power. However, since the morning is a time period when the power selling price is low, the power is not sold and is charged to the power storage device 2. Then, during the time period when the power selling price is high, the power storage device 2 is discharged and sold. As described below, the power selling plan is designed so that the timing of this power selling is as late as possible during the time period when the power selling price is high. In FIG. 10(b), areas A11 and A12 represent the amount of surplus power. Area A13 in the same figure represents the amount of power demand that is met by power generation. Area A14 in the same figure represents the amount of power demand that cannot be met by power generation.

[0076] The process flow in the planning unit 12 will be outlined with reference to FIG. As shown in step S11 in the figure, the planning unit 12 calculates the amount of surplus power based on the power supply and demand forecast data predicted by the prediction unit 11 (see FIG. 10(b)). Next, in step S12, the planning unit 12 calculates the planned amount of power sale from the amount of surplus power calculated in step S11. Next, in step S13, the planning unit 12 calculates the discharge time (e.g., 6 hours) from the planned amount of power sale and the optimal discharge power. Next, in step S14, the time (e.g., 2 p.m.) obtained by subtracting the discharge time (e.g., 6 hours) from the selling price switching time (e.g., 8 p.m.) is calculated as the power sale start time. The processing by the planning unit 12 will be described below.

[0077] The planner 12 calculates the amount of surplus power (see area A11 in FIG. 10(b)) based on the time transition of the amount of power generated by the power generation device 2 and the time transition of the amount of power demand at the consumer 5 predicted by the predictor 11. The planner 12 calculates the planned amount of power to be sold from the amount of surplus power. The amount of surplus power considered here is the amount of surplus power in the area A11 in FIG. 10(b), and the amount of surplus power in the area A12 is not considered. In addition, the calculation of the planned amount of power to be sold also takes area A14 into consideration. This is because the power shortage in area A14 is covered by a portion of the surplus power in area A11 that has been charged to the storage device 2. In addition to these, the charging efficiency and discharging efficiency of the storage device 2, etc. are also taken into consideration in calculating the planned amount of power to be sold.

[0078] Then, as shown in Fig. 12(b), the planner 12 plans a power selling plan such that the planned amount of power selling (see area A17) is sold from the power storage device 2 to the power grid 3 during the high power selling price time slot. At the same time, the planner 12 plans the power selling plan such that the power selling is completed at the selling price switch time when the high power selling price time slot switches to the low power selling price time slot. In Fig. 12(b), the area A17 represents the planned amount of power selling from the power storage device 2 to the power grid 3.

[0079] The planner 12 calculates the start time of selling power to the power grid 3 so that the power selling will be completed at the selling price switching time as follows. First, the discharge time is derived from the planned power selling amount calculated in step S12 and the optimal discharge power. Then, the time obtained by subtracting the discharge time from the selling price switching time is calculated as the power selling start time. In this manner, the planner 12 plans the power selling plan.

[0080] For example, assume that the prediction unit 11 has obtained the power supply and demand prediction data shown in Fig. 10(b) as the power supply and demand prediction data predicted at midnight. According to this power supply and demand prediction data, the amount of power generated greatly exceeds the amount of power demand between midnight and 12:00, resulting in surplus power. Then, between 12:00 and 19:00, the amount of power demand exceeds the amount of power generated.

[0081] The periods from midnight to 12 noon and from 8 p.m. to midnight are low-price power selling periods. Therefore, it is desirable to temporarily charge the surplus power generated between midnight and 12 noon in the power storage device 2 and sell it between 12 noon and 8 p.m., which is the high-price period. In addition, it is also effective from the viewpoint of refraining from purchasing electricity to supply the power stored in the power storage device 2 to the consumer 5 to cover the power shortage during periods when the power demand exceeds the power generation.

[0082] However, as described above, the power supply and demand forecast data may change over time. That is, the power supply and demand forecast data fluctuates with changes in various factors such as temperature. For example, the power supply and demand forecast data at 2 p.m. may fluctuate to a forecast as shown in FIG. 13. According to the power supply and demand forecast data shown in the figure, the amount of power demand is significantly higher than the amount of power generated at least during the high power selling price period from 2 p.m. to 8 p.m.

[0083] According to this power supply and demand forecast data, the excess of power demand that cannot be met by the power generation of the power generation device 4 during the high power selling price time period has increased compared to the forecast at midnight. In this case, the power selling plan is revised and the power stored in the power storage device 2 is discharged to the consumer 5 to make up for the shortage of power demand. In this way, it is possible to avoid purchasing the shortage of power demand from the power grid 3 or to reduce the amount of power purchased. In this revised power selling plan, for example, it is also possible to sell to the power grid 3 only the amount of power surplus after supply to the consumer 5.

[0084] As described above, the power supply and demand forecast data predicted by the prediction unit 11 may fluctuate from moment to moment. Therefore, if power is sold based on power supply and demand forecast data predicted in an early time period, power that should have actually been supplied to the consumer 5 may end up being sold.

[0085] Therefore, from the viewpoint of reducing power costs, it is desirable to plan and execute a power selling plan based on the most recent power supply and demand forecast data, assuming that power will be sold during the high power selling price time slot. Therefore, as described above, when the planner 12 plans the power selling plan, the planner 12 plans the power selling plan so that power will be sold during the last time slot of the high power selling price time slot, as shown in Fig. 12. In other words, the power selling plan is planned so that power selling will be completed at the selling price switching time when the high power selling price time slot switches to the low power selling price time slot.

[0086] Specifically, as described above, the time obtained by subtracting the discharge time from the selling price switching time is planned as the start time of selling grid power. The discharge time is calculated based on the optimum discharge power of the storage device 2 and the planned amount of power to be sold. In this embodiment, the optimum discharge power is the maximum discharge power of the storage device 2. The maximum discharge power is an inherent value of the storage device 2, and is the maximum power that can be discharged.

[0087] The optimum discharge power may be, for example, the minimum-loss discharge power of the energy storage device 2. The minimum-loss discharge power is an inherent value of the energy storage device 2, and is the discharge power at which loss occurring during discharge is the lowest. Usually, this minimum-loss discharge power is a value smaller than the maximum discharge power.

[0088] In this way, suppose that at midnight, the planning unit 12 calculates the discharge time to be, for example, six hours. In this case, the power selling plan has a power selling start time of 2 p.m. Therefore, in this embodiment, the plan is to sell power from 2 p.m. to 8 p.m. with the maximum discharge power, as shown in FIG. 12(b).

[0089] Then, as shown in Fig. 13, if the power shortage during the high power selling price time period increases in the power supply and demand forecast data predicted by the prediction unit 11 at 2 p.m., the power selling plan also changes. Then, the initially planned power sale to the power grid 3 by the control unit 13 can be canceled or reduced. This is because the plan was changed to not sell power or to reduce the power selling before the power selling start time (2 p.m. in this example) planned at midnight passed. As a result, unnecessary power selling can be prevented, and power costs can be reduced.

[0090] In the above example, suppose that the timing of power sales was planned to be early, such as from 12:00 to 18:00. Even if the power supply and demand forecast data changes to that shown in Fig. 13 at 14:00, power sales have already progressed at 14:00, so power sales will be wasteful. In other words, in this case, while power is sold, it will be necessary to purchase power to make up for the shortage.

[0091] In contrast, if the timing of selling electricity is planned to be between 14:00 and 20:00, in the above case, it is possible to avoid unnecessary selling and purchasing of electricity. As a result, it is possible to suppress unnecessary buying and selling of electricity, and to reduce electricity costs.

[0092] The rest is the same as in the first embodiment. According to this embodiment, when the unit price of selling electricity fluctuates during a predetermined period, it is possible to effectively reduce the electricity cost. In addition, the same effects as those of the first embodiment are obtained.

[0093] (Embodiment 6) In this embodiment, as shown in FIG. 14, a power selling plan is created when a hydrogen storage device is used as the power storage device 20. In the embodiment, as shown in FIG. That is, similarly to the third embodiment, a hydrogen storage device is used as the electricity storage device 20, and similarly to the fifth embodiment, the timing of selling grid power and the like are planned.

[0094] In this embodiment, the method of planning the power selling plan by the planner 12 of the energy management system 1 is substantially the same as in the fifth embodiment. However, the method of calculating the discharge time to the power storage device 20 is different from that in the fifth embodiment, and as a result, the method of calculating the power selling start time is different.

[0095] That is, the discharge rate of the power storage device 20, which is a hydrogen storage device, does not increase immediately after the start of discharge, but increases gradually. Therefore, as shown in Fig. 14(b), the power selling plan is planned so that the power selling associated with the discharge of the power storage device 20 gradually increases immediately after the start of discharge. In the figure, area A170 represents the amount of power sold associated with the discharge of the power storage device 20. Also, since the discharge rate cannot be suddenly decreased at the end of discharge, the power selling plan is planned so that the discharge rate is gradually decreased and the power selling is substantially completed at the selling price switching time (8 p.m. in the example shown in Fig. 14).

[0096] The optimum discharge power for optimally discharging such a hydrogen storage device can be determined from various viewpoints. That is, for example, the optimum discharge power can be the discharge power according to a discharge profile that allows discharge to be completed in the shortest time. Alternatively, for example, the optimum discharge power can be the discharge power according to a discharge profile that allows discharge to be performed with the least loss. In the case of a hydrogen storage device such as this embodiment, these optimum discharge powers usually vary over time.

[0097] The planning unit 12 may calculate the time when the integral value of the optimal discharge power, which changes over time, becomes the planned amount of power to be sold as the discharge time. Then, the time obtained by subtracting this discharge time from the selling price switching time may be planned as the power selling start time.

[0098] Taking into consideration the above-mentioned storage characteristics of the hydrogen storage device, in the electricity sales plan shown in Fig. 14(b), the discharge time is calculated to be 6 hours, and the electricity sales start time is set to 14:00. However, it goes without saying that this is merely one example.

[0099] A case where power is sold according to the power selling plan shown in FIG. 14 will be described. At 2 p.m., the power selling start time, the power storage device 20 starts discharging and selling the power to the power grid. This discharging is performed by converting the hydrogen stored in the hydrogen tank into electricity using a fuel cell in the hydrogen storage device. This discharging of the power storage device 20 is completed during the high power selling price period. Other than that, it is the same as the first embodiment.

[0100] In this embodiment, it is possible to effectively create a power selling plan when a hydrogen storage device is used as the power storage device 20. In addition, the present embodiment has the same functions and effects as the fifth embodiment.

[0101] (Embodiment 7) In this embodiment, as shown in FIG. 15, a power selling plan is created when both a storage battery and a hydrogen storage device are used as the power storage devices 2, 20. In the embodiment shown in FIG. That is, similarly to the fourth embodiment, a storage battery and a hydrogen storage device are used as the power storage devices 2, 20, and the timing of selling grid power and the like are planned similarly to the fifth embodiment.

[0102] In this case, the planning unit 12 plans how much power to discharge from each of the two power storage devices 2, 20 and sell to the power grid during the high power selling price time period. Then, the discharge time of each of the power storage devices 2, 20 is calculated from the planned power selling amount and the device characteristics of each device. Based on this, the time obtained by subtracting the discharge time of each of the power storage devices 2, 20 from the selling price switching time is calculated as the power selling start time for discharging each of the power storage devices 2, 20.

[0103] 15(b), an area A17 represents the amount of power sold associated with the discharge of the storage battery 2. Also, in the same figure, an area A170 represents the amount of power sold associated with the discharge of the hydrogen storage device 20.

[0104] As shown in the figure, the start time of the power sale associated with the discharge of the storage battery 2 and the start time of the power sale associated with the discharge of the hydrogen storage device 20 may differ from each other. In the figure, an example is shown in which the former is around 16:00 and the latter is around 14:00. The rest is the same as in the fifth and sixth embodiments. This embodiment also has the same effects as the fifth and sixth embodiments.

[0105] The present invention is not limited to the above-described embodiments, and can be applied to various embodiments without departing from the gist of the present invention. [Explanation of symbols]

[0106] 1. Energy Management System 11 Prediction Department 12 Planning Department 13 Control section 2. Energy storage device 3 Power system 4. Power generation equipment 5 Consumer

Claims

1. An energy management system (1) having a power storage device (2, 20) capable of storing system power from a power grid (3) and power generated by a power generation device (4), and controlling the purchase of the system power, a prediction unit (11) that predicts a time transition of an amount of power generated by the power generation device and a time transition of an amount of power demand in a consumer (5) during a predetermined period; a planning unit (12) that plans an amount and timing of purchasing the grid power during the predetermined period based on power supply and demand forecast data predicted by the prediction unit and power purchase price data related to a unit price of purchasing power from the power grid; A control unit (13) that controls an amount and timing of purchasing the grid power based on the power purchase plan planned by the planning unit, The prediction unit is configured to sequentially update the power supply and demand prediction data within the predetermined period, The predetermined period includes a low power purchase price time period in which the power purchase price is relatively low, and a high power purchase price time period in which the power purchase price is higher than the low power purchase price time period, the planning unit calculates an amount of power shortage during the high power purchase price time period based on the time transition of the amount of power generated by the power generation device and the time transition of the amount of power demand at the consumer predicted by the prediction unit, and plans the power purchase plan such that the amount of power shortage is purchased from the power grid during the low power purchase price time period and charged into the power storage device; The planning unit is capable of changing the power purchase plan before a purchase price switching time when the low power purchase price time period is switched to the high power purchase price time period, and the planning unit is configured to derive a charging time for the energy storage device to handle the amount of energy shortage from the amount of energy shortage and the optimal charging power, and to plan a time obtained by subtracting the charging time from the purchasing price switching time as the start time for purchasing the grid power to charge the energy storage device.

2. An energy management system (1) having a power storage device (2, 20) capable of storing system power from a power system (3) and power generated by a power generation device (4), and controlling the sale of the system power, a prediction unit (11) that predicts a time transition of an amount of power generated by the power generation device and a time transition of an amount of power demand in a consumer (5) during a predetermined period; a planning unit (12) that plans an amount and timing of the sale of the grid power during the predetermined period based on power supply and demand forecast data predicted by the prediction unit and power buying and selling price data related to a unit price of the power sold to the power grid; A control unit (13) that controls an amount and timing of the sale of the grid power based on the power sale plan planned by the planning unit, The prediction unit is configured to sequentially update the power supply and demand prediction data within the predetermined period, the predetermined period includes a low power selling price time period in which the power selling price is relatively low, and a high power selling price time period in which the power selling price is higher than the low power selling price time period, the planning unit calculates an amount of surplus power based on the time transition of the amount of power generated by the power generation device and the time transition of the amount of power demand at the consumer predicted by the prediction unit, calculates a planned amount of power sale from the amount of surplus power, and plans the power selling plan such that the planned amount of power sale is discharged from the power storage device and sold to the power grid during the high power selling price time period; The planning unit is capable of changing the power selling and purchasing plan before a selling price switching time when the low power selling price time period is switched to the high power selling price time period, The energy management system is further configured such that the planning unit derives a discharge time for the planned amount of power to be sold from the power storage device from the planned amount of power to be sold and the optimal discharge power, and plans the time obtained by subtracting the discharge time from the selling price switching time as the start time for discharging power from the power storage device and selling it to the power grid.

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