Energy management system and its control method

Abstract

To provide an energy management system that can properly initiate hot water storage operation. [Solution] An energy management system that manages the exchange of power between a solar power generation system, an HP-type water heater, and other equipment comprises a first detection unit that detects the amount of power generated by the solar power generation system, a second detection unit that detects the amount of power consumed by the other equipment, and an operation planning unit for the HP-type water heater. When performing hot water storage operation during daytime hours, the operation planning unit determines whether to start hot water storage operation of the HP-type water heater if the difference between the amount of power generated by the solar power generation system and the amount of power consumed by the other equipment is greater than the amount of power consumed when the HP-type water heater is operating at its minimum capacity. In this case, the operation planning unit determines whether to start hot water storage operation of the HP-type water heater during daytime hours by predicting that the amount of power generated is 0 or increasing based on the rate of change in the amount of power generated, and predicting that the amount of power consumed by the other equipment is 0 or decreasing based on the rate of change in the amount of power consumed by the other equipment.

Description

Technical Field

[0001] The present invention relates to a technique for reducing surplus power of solar power generation by controlling a storage-type water heater.

Background Art

[0002] As a conventional technique for controlling a storage-type water heater to generate hot water using the power of solar power generation, for example, those described in Patent Document 1 and Patent Document 2 are known.

[0003] Patent Document 1 discloses a system including a solar power generation means that generates power using sunlight, a CO2 heat pump water heater, and a remote control for controlling the water heater. In the system, weather prediction information is obtained from a server by weather information acquisition means, and when the acquired weather information meets the set conditions, the power for boiling water by the CO2 heat pump water heater is switched and controlled to use the power of solar power generation instead of the late-night power of commercial power, so as to operate the CO2 heat pump water heater with the power of natural energy.

[0004] Patent Document 2 discloses that when the current surplus power becomes equal to or greater than a first predetermined value of 0 or more, the water heater starts a boosting operation. If the current surplus power does not become equal to or greater than the first predetermined value, the water heater does not start the boosting operation. It is disclosed that the first predetermined value is preferably a value greater than or equal to the minimum power consumption of the water heater during the boosting operation.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In Patent Document 1, the switching between nighttime and daytime water heating was performed based on weather forecast information, and the water heating time and start time were also planned based on the forecast information. As a result, there were cases where daytime water heating operation could not be carried out as planned depending on the weather on the day. Similarly, in Patent Document 2, there were cases where water heating operation (hot water storage operation) could not be started properly depending on the weather on the day and the status of self-consumption of electricity.

[0007] The present invention was made to solve the aforementioned problems and aims to provide an energy management system and a control method thereof that can appropriately start hot water storage operation. [Means for solving the problem]

[0008] To solve the aforementioned objectives, the present invention provides an energy management system for managing the exchange of power between a solar power generation means, an HP-type water heater, and other equipment, wherein the energy management system comprises a first detection unit for detecting the amount of power generated by the solar power generation means, a second detection unit for detecting the amount of power consumed by the other equipment, and an operation planning unit for the HP-type water heater, wherein the operation planning unit, in the operation plan, when performing hot water storage operation during daytime hours, if the difference between the amount of power generated by the solar power generation means and the amount of power consumed by the other equipment is greater than the amount of power consumed when the HP-type water heater is operated at its minimum capacity, the operation planning unit determines when to start hot water storage operation of the HP-type water heater during daytime hours by predicting that the amount of power generated is 0 or increasing based on the rate of change of the amount of power generated, and predicting that the amount of power consumed by the other equipment is 0 or decreasing based on the rate of change of the amount of power consumed by the other equipment, and performs hot water storage operation of the HP-type water heater. Other aspects of the present invention will be described in the embodiments described below. [Effects of the Invention]

[0009] According to the present invention, the hot water storage operation can be started appropriately. [Brief explanation of the drawing]

[0010] [Figure 1] This figure shows an example of the configuration of an energy management system according to the embodiment. [Figure 2A] This figure shows the change in power consumption when the heating amount of a CO2 heat pump water heater is changed under standard ambient temperature and water supply temperature conditions. [Figure 2B] This figure shows the change in power consumption of a CO2 heat pump water heater when the outside air temperature is changed under standard heating rate and water supply temperature conditions. [Figure 2C] This shows the change in power consumption when the water supply temperature of a CO2 heat pump water heater is changed under standard heating rate and ambient temperature conditions. [Figure 3] This figure shows the control flow of the energy management system according to the embodiment. [Figure 4A] This figure shows the relationship between the amount of electricity generated by solar power generation systems and the amount of electricity consumed by household appliances other than CO2 heat pump water heaters, when the weather forecast is sunny and the amount of electricity generated by solar power generation systems is high during the morning and midday hours. [Figure 4B] Figure 4A shows the power consumption associated with the storage operation of a CO2 heat pump water heater. [Figure 5A] This diagram shows the relationship between the amount of electricity generated by solar power generation systems and the amount of electricity consumed by household appliances other than CO2 heat pump water heaters, when the weather forecast is rain and the amount of electricity generated by solar power generation systems is low during the morning and midday hours. [Figure 5B] Figure 5A shows the power consumption associated with the storage operation of a CO2 heat pump water heater. [Figure 6A] This figure shows the relationship between the amount of electricity generated by solar power generation systems and the amount of electricity consumed by household appliances other than CO2 heat pump water heaters, when the weather forecast is sunny and the amount of electricity generated by solar power generation systems is low during the morning and midday hours. [Figure 6B] Figure 6A shows the power consumption associated with the storage operation of a CO2 heat pump water heater. [Figure 7A] This diagram shows the relationship between the amount of electricity generated by solar power generation systems and the amount of electricity consumed by household appliances other than CO2 heat pump water heaters, when the weather forecast is rain and the amount of electricity generated by solar power generation systems is high during the morning and midday hours. [Figure 7B] FIG. 7A is a diagram showing the power consumption associated with the hot water storage operation of the CO2 heat pump water heater. [Figure 8] FIG. 5 is a diagram showing the hardware configuration of the energy management device according to the embodiment. [Figure 9] FIG. 8 is a diagram showing an example of the functional configuration of the energy management device according to the embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, specific operation examples of the system described in this embodiment are merely examples, and are not particularly limited to these operations.

[0012] (Configuration of the Embodiment) FIG. 1 is a diagram showing an example of the configuration of an energy management system EMS according to the embodiment. The energy management system EMS shown in FIG. 1 is composed of an energy management device 100, a broadband router 800, and an information input device 900. The CO2 heat pump water heater 500 (HP type water heater) and other home appliances 600 (for example, refrigerator, air conditioner, washing machine) that are controlled by the energy management device 100 are connected via a communication adapter 700. Note that the other home appliances 600 are examples of "other devices".

[0013] By connecting the controlled devices and the energy management device 100 as described above, it is possible to monitor the energy consumed and generated by the controlled devices and to operate / stop the devices. Further, the energy management device 100 is connected to an external service 1000 via a broadband router 800 and an Internet network line, and an information input device 900 that enables a user to individually control the devices is connected.

[0014] Since the energy management device 100 connects a solar power generation device 200 (solar power generation means), a CO2 heat pump water heater 500, and other household appliances 600 via a network, it can monitor the total amount of power generation during solar power generation and the total energy consumption used by the other household appliances 600.

[0015] Note that the solar power generation device 200 is connected to a distribution board 400 via a power conditioner 300, and the CO2 heat pump water heater 500 and other household appliances 600 are also connected to the distribution board 400.

[0016] Furthermore, the energy management device 100 is provided with a function of learning the heat demand amount used by the user in a day, creating a database, and storing it. As a result, the energy management device 100 of the present embodiment can estimate and command the heating amount and heating time required for the instruction when the CO2 heat pump water heater 500 performs a boiling-up operation during the late-night time zone and the daytime time zone.

[0017] Also, the energy management device 100 has a database (not shown) on the cloud or locally that learns and stores the heat demand amount used by the user in a day and the timing (heat demand pattern) at which the user uses heat. With this database, the energy management device 100 can distribute the required heat demand amount for each time zone when the water heater is scheduled to operate when creating an operation plan for the CO2 heat pump water heater 500. Furthermore, it makes it possible to estimate the heating amount of the boiling-up operation in each time zone from the heat demand amount and the scheduled operation time.

[0018] Furthermore, the energy management device 100 has a function to input the electricity rate pattern of the user's contracted electricity charges via an information input device 900 (user interface) or a cloud-based user interface (not shown) (for example, an IT device such as a smartphone) and store it in a database. This function allows the energy management device 100 to select a time period when commercial electricity prices are low and issue a command to the CO2 heat pump water heater 500 to start heating, even when natural energy is insufficient and the CO2 heat pump water heater 500 must be operated with commercial electricity.

[0019] Furthermore, the energy management device 100 of this embodiment has an estimation function that estimates the amount of energy consumed when the CO2 heat pump water heater 500 is in operation, based on the heating amount, the outside air temperature, and the temperature of the water supplied to the CO2 heat pump water heater 500. This function allows the amount of energy consumed by the CO2 heat pump water heater 500 to be evaluated before operation. The energy management device 100 can monitor the amount of electricity generated by the solar power generation device 200 and the energy consumption of other home appliances 600.

[0020] Surplus electricity = Amount of solar power generated - Energy consumption of other household appliances (1) With this definition, it is possible to determine whether or not the CO2 heat pump water heater 500 can operate by comparing the estimated amount of energy consumed by the CO2 heat pump water heater 500 with the amount of surplus electricity and heating. For example, Estimated energy consumption of surplus power-CO2 heat pump water heater ≥ 0 (2) In this case, a decision-making function can be implemented to determine whether or not to operate the CO2 heat pump water heater 500.

[0021] Here, the CO2 heat pump water heater 500 is a device composed of two units: a heat pump unit 510 and a hot water storage unit 520. The CO2 heat pump water heater 500 is a hot water storage type device that supplies hot water by generating the required amount of hot water in advance using the heat pump unit 510 and storing the generated hot water in the hot water storage unit 520. It is a device that can process the time of hot water generation and hot water supply separately.

[0022] The heat pump unit 510 generates hot water as follows: Outside air is blown into the heat exchanger 514 by the fan 515 and flows into the heat exchanger 514. The outside air blown into the heat exchanger 514 and the CO2 refrigerant flowing inside the heat exchanger 514 via the expansion valve 513 exchange heat, and the heat from the outside air is transferred to the CO2. The refrigerant that has absorbed heat from the outside air flows into the compressor 511, where it is heated and compressed, and then flows into the water heat exchanger 512. Low-temperature water supplied from the bottom of the hot water storage tank 522 by the pump 521 flows into the water heat exchanger 512, and the incoming low-temperature water and the high-temperature CO2 refrigerant flowing in from the compressor 511 exchange heat, generating hot water. The generated hot water is returned to the hot water storage tank 522 via the water pipe 523, and when the user opens the water tap 524 or shower tap, an amount of hot water corresponding to the opening of the tap or water tap 524 is supplied from the top of the hot water storage tank 522.

[0023] As described above, the power consumption during the heating operation of the CO2 heat pump water heater 500 is affected by changes in the amount of heat being heated, the ambient temperature, and the water supply temperature. In order to operate the CO2 heat pump water heater 500 within the surplus power of solar power generation, an estimation model is needed that takes into account the effects of the amount of heat being heated, the ambient temperature, and the water supply temperature to determine the appropriate power consumption for the heating operation.

[0024] Figure 2A shows the change in power consumption when the heating rate of a CO2 heat pump water heater is changed under standard ambient temperature and water supply temperature conditions. Figure 2B shows the change in power consumption when the ambient temperature of a CO2 heat pump water heater is changed under standard heating rate and water supply temperature conditions. Figure 2C shows the change in power consumption when the water supply temperature of a CO2 heat pump water heater is changed under standard heating rate and ambient temperature conditions.

[0025] Figures 2A, 2B, and 2C show that the power consumption of the CO2 heat pump water heater 500 increases with increasing heating rate, decreases with increasing ambient temperature, and increases with increasing water supply temperature. It also shows that the power consumption of the CO2 heat pump water heater 500 is greatly affected by changes in heating rate. Therefore, in this embodiment, the base power consumption for changes in heating rate is estimated, and the effects of other parameters are modeled as increases relative to the base power consumption. The base power consumption is estimated using equation (3).

[0026] Standard power consumption = C0 × heating amount (standard ambient temperature, standard water supply temperature) + C1 (3) Here, C0 and C1 are constants, and C0 has a value of ≥ 0. The amount of electricity consumed by the CO2 heat pump water heater when the heating amount is equivalent to the heating amount used to estimate the standard power consumption, and other parameters change, is estimated using equation (4).

[0027] Power consumption = Standard power consumption + C2 × (Outside temperature - Standard outside temperature) +C3×(feed water temperature - standard feed water temperature)+C4 (4) Here, C2, C3, and C4 are constants, and C2 ≤ 0 and C3 ≥ 0. Because the CO2 heat pump water heater 500 has the functions described above, the generation of hot water and the utilization of hot water (heat utilization) can be processed as separate operations.

[0028] In other words, the water heater power consumption estimation unit 15 (see Figure 9) of the energy management device 100 uses the heating amount of the water heater, the ambient temperature during water heater operation, and the water supply temperature during water heater operation as parameters, and estimates the power consumption as a model that linearly combines the changes in heating amount, ambient temperature, and water supply temperature. It is preferable to estimate power consumption in which the constant terms for heating amount and water supply temperature have positive values, and the constant term for ambient temperature has a negative value. Note that the estimation model can be created using a model in which the results of the linear combination model described above are managed as point sequence data, and the same effect can be achieved.

[0029] In the energy management system constructed with the above configuration, the energy management device 100 operates according to the control flow shown in Figure 3.

[0030] Figure 3 shows the control flow of the energy management system according to the embodiment. In step S100, the energy management device 100 (HEMS) requests and obtains information from an external service provider and a database (DB1) to generate an operation plan at a fixed time before the start of the CO2 heat pump water heater 500's heating operation during the nighttime hours.

[0031] In step S101, the external service provider that receives the information request command reports weather information (weather forecast, outside temperature, etc.) to the energy management device 100, and the energy management device 100 acquires the weather information.

[0032] In step S102, the database that receives the information request command reports to the energy management device 100 the heat demand pattern (amount of heat demand, timing of demand occurrence) information (DB1) that the CO2 heat pump water heater 500 must process within 24 hours after the operation planning time, and the contract rate pattern (DB2) of the commercial electricity contracted by the user. The energy management device 100 then acquires the heat demand pattern and the contract rate pattern.

[0033] In step S110, the energy management device 100 (HEMS) generates an operation plan based on the weather information, heat demand pattern, and contracted power pattern obtained in steps S101 and S102.

[0034] As an operating plan, for example, the energy management device 100 uses weather information to set the system to a two-part operation mode, which, when the weather information is "sunny," issues a command to start operation of the CO2 heat pump water heater 500 during the morning and daytime hours, based on the amount of power generated, the amount of power consumed other than by the CO2 heat pump water heater 500, the amount of surplus power, and the electricity rate pattern, after operation during the nighttime hours.

[0035] Furthermore, if the weather is anything other than sunny, the energy management device 100 searches for a time when electricity rates are lower during the morning and daytime hours based on the contract rate pattern obtained in step S102, and sets the CO2 heat pump water heater 500 to a two-part operation mode, using the searched time as the start time of operation.

[0036] For example, with the planned generation time set to 0:00, the heating operation period is divided into two parts: the heat demand handled by the heating operation during the nighttime period is from 5:00 to 17:00 (5:00 to 17:59), and the heat demand handled by the heating operation during the daytime period is from 18:00 to 4:00 the following day (18:00 to 4:59).

[0037] In such cases, the amount of heating (kWh) during the nighttime hours is estimated using formula (5), assuming the start time of the heating operation is 1:00 and the end time is 5:00. Heating amount = Heat demand from 5am to 5pm / (End time of boiling operation - Start time of boiling operation) (5)

[0038] If the estimated heating amount is significantly lower than the amount of heating that allows the CO2 heat pump water heater 500 to operate efficiently, the boiling time is estimated using formula (6) based on the heating amount. Heating time = Heat demand from 5am to 5pm / Amount of heating that can be done with high efficiency (6) Then, the start time of boiling is estimated using equation (7). Water boiling start time = 5:00 - boiling time (7)

[0039] As described above, in step S110, the energy management device 100 determines the number of divisions for the boiling operation, the amount of heating required for each boiling operation, and the amount of heating and boiling operation time during the nighttime hours, and then proceeds to step S120.

[0040] For example, in step S100, the energy management device 100 acquires weather forecast information before the start of the off-peak electricity period using the weather information acquisition unit 14 (see Figure 9), and in step S110, when the weather forecast information acquired by the weather information acquisition unit 14 (see Figure 9) matches the preset weather information (when clear weather is expected), the energy management device 100 can generate an operation plan that suppresses hot water storage operation using off-peak electricity and generates hot water using the power of the solar power generation means.

[0041] Furthermore, when generating an operating plan for the HP-type water heater, the energy management device 100 can use weather forecast information acquired by the weather information acquisition unit 14 (see Figure 9) to determine whether to store hot water using daytime electricity generated by the solar power generation means, nighttime electricity purchased from the grid, or both of the daytime and nighttime electricity, and then generate an operating plan for the HP-type water heater.

[0042] In step S120, the energy management device 100 issues a command to the CO2 heat pump water heater 500 to start heating operation during the nighttime hours. In step S200, the CO2 heat pump water heater 500, having received a command to start heating, begins the heating operation, performs the heating operation for the commanded amount of heat, then ends the heating operation and reports the completion of the heating operation to the energy management device 100. Upon receiving the report of completion of the heating operation from the CO2 heat pump water heater 500, the energy management device 100 proceeds to step S130.

[0043] In step S130, the energy management device 100 requests information on the amount of power being generated at the current time from the solar power generation device 200, requests information on the amount of energy being consumed at the current time from other home appliances 600, and requests an estimated value of the energy consumption of the CO2 heat pump from the HP hot water power consumption estimation model (HP hot water power consumption estimation unit held by the energy management device 100).

[0044] In step S300, the solar power generation device 200, which has been requested to provide information on the amount of power generated, reports the amount of power generated at the current time to the energy management device 100. In step S400, the other household appliances 600 that have been requested to provide energy consumption information report the current energy consumption information to the energy management device 100.

[0045] In step S131, the HP water heater power consumption estimation model estimates the amount of heating. For example, the amount of heating is estimated as follows: The heating operation time is defined as the time from the current time (start of heating operation) to the end of the minimum time period of the contracted power rate plan, and the amount of heating (kWh) is estimated using equation (8). Heating amount = Heat demand from 6 PM to 4 AM / Heating operation time (8)

[0046] The energy consumption of the CO2 heat pump water heater 500 is estimated using equation (9), based on the estimated heating amount of the CO2 heat pump water heater 500, the current ambient temperature, and the water supply temperature. Power consumption (energy consumption of CO2 heat pump water heater) =f(heating amount of CO2 heat pump water heater, current outside air temperature, current water supply temperature) (9)

[0047] From steps S131, S300, and S400, the energy management device 100 obtains the amount of electricity generated by solar power generation, the amount of electricity consumed by other household appliances, and the amount of electricity consumed for the expected heating amount of the CO2 heat pump water heater 500 at the current time. In control step S130, the energy management device 100 estimates the surplus power using formula (10). Then it proceeds to step S132. Surplus electricity = Amount of solar power generated - Amount of electricity consumed by other power generation equipment (10)

[0048] In step S132, the energy management device 100 calculates the surplus power and the estimated power consumption of the CO2 heat pump water heater, Estimated power consumption of surplus power-CO2 heat pump water heater ≥ 0 (11) Evaluate whether it matches the criteria or not.

[0049] In other words, equation (11) means that when hot water storage operation is performed during daytime hours, the difference between the amount of electricity generated by the solar power generation means (solar power generation device) and the amount of electricity consumed by other household appliances is greater than the amount of electricity consumed when the HP type water heater is operating at its minimum capacity.

[0050] If the conditions of equation (11) are satisfied, compare the amount of solar power generated one time step ago with the amount of power generated at the current time, and evaluate the increase or decrease in the amount of power consumed by other household appliances one time step ago with the amount of power consumed at the current time. Increase in solar power generation ≥ 0 AND power consumption of other household appliances ≤ 0 (12) Determine whether or not it matches the criteria.

[0051] If the conditions of equations (11) and (12) are met, the energy management device 100 determines that it is possible to operate the CO2 heat pump water heater 500 using solar power generation and issues a command to the CO2 heat pump water heater 500 to start the heating operation. The amount of heat and heating operation time used in the command for heating operation may be estimated values ​​as follows.

[0052] In other words, the decision to start hot water storage operation during daytime hours means that the HP-type water heater will operate when the power generation is predicted to be zero or increasing based on the rate of change in power generation, and the power consumption of other home appliances is predicted to be zero or decreasing based on the rate of change in power consumption of other home appliances.

[0053] Surplus power - f (estimated heating amount, current ambient temperature, current water supply temperature) ≥ 0 After estimating the corresponding estimated boiling and heating amount, Heating time = Heat demand from 6 PM to 4 AM / Estimated boiling heat amount

[0054] If the operating conditions based on surplus power, power generation amount, and power consumption pattern are not met, the energy management device 100 further makes the following determination of whether or not to operate in step S132.

[0055] The current time falls within the minimum daytime rate period of your contracted electricity plan. If the conditions are met, the heating operation time is calculated using formula (13) with the time from the current time to the end of the minimum charge period of the electricity rate plan as the heating operation time, and the process proceeds to step S140. Heating amount = Heat demand from 6 PM to 4 AM / Heating operation time (13)

[0056] The criteria for determining whether or not to drive, as described above, will be explained in detail below using Figures 4A to 7B. The lower sections of Figures 4A to 7B show the time-dependent changes in specific contract electricity rate patterns.

[0057] (Example of hot water storage operation 1) Figure 4A shows the relationship between the amount of electricity generated by the solar power generation system 200 and the amount of electricity consumed by other home appliances 600 other than the CO2 heat pump water heater, when the weather information is sunny and the amount of electricity generated by the solar power generation system 200 is high during the morning and midday hours. Figure 4B is a diagram that adds the amount of electricity consumed by the CO2 heat pump water heater 500 during hot water storage operation to Figure 4A.

[0058] In Figure 4A, the hourly change in the amount of power generated by the solar power generation system 200 increases from sunrise (5:00) to 11:00, while the power consumption of other household appliances 600, excluding the CO2 heat pump water heater, decreases after 5:00. It can be seen that 7:00 is the time when the increase in solar power generation ≥ 0, the power consumption of other household appliances ≤ 0, and the surplus power ≥ 0 are met. At this point, the energy management device 100 refers to the amount of power generated, power consumed, and surplus power from the previous step, so the energy management device 100 issues a command to start the heating operation of the CO2 heat pump water heater 500 during the morning / daytime period after 8:00.

[0059] Figure 4B also shows the power consumption (HP power consumption) associated with the storage operation of the CO2 heat pump water heater 500. From Figure 4B, it can be seen that the heating operation of the CO2 heat pump water heater 500 is possible within the surplus power. In other words, when it is not possible to sell or store the solar power generated, the surplus power from solar power generation can be reduced.

[0060] (Example of hot water storage operation 2) Figure 5A shows the relationship between the amount of electricity generated by the solar power generation system 200 and the amount of electricity consumed by other home appliances 600 other than the CO2 heat pump water heater, when the weather information is rain and the amount of electricity generated by the solar power generation system 200 is low during the morning and midday hours. Figure 5B is a diagram that also shows the amount of electricity consumed by the CO2 heat pump water heater 500 during hot water storage operation, as shown in Figure 5A.

[0061] In Figure 5A, if the weather forecast is rain and it rains during the morning and midday hours, the amount of power generated by the solar power generation device 200 will not increase sufficiently, so there is no time when the increase in solar power generation amount ≥ 0, the amount of power consumed by other home appliances ≤ 0, and the amount of surplus power ≥ 0 are met. At the time of generating the operation plan in step S110, the energy management device 100 specifies the time when the CO2 heat pump water heater 500 will start heating operation based on the contracted power rate pattern, and therefore issues a command to start heating operation of the CO2 heat pump water heater 500 when the predetermined time is reached.

[0062] Figure 5B shows the power consumption associated with the storage operation of the CO2 heat pump water heater 500. In this example of storage operation, it can be seen that heating operation is started based on the contracted power pattern, regardless of surplus power. Furthermore, the CO2 heat pump water heater 500 selects the heating amount to satisfy the required heating amount in the shortest possible time.

[0063] (Example of hot water storage operation 3) Figure 6A shows the relationship between the amount of electricity generated by the solar power generation system 200 and the amount of electricity consumed by other household appliances 600 other than the CO2 heat pump water heater, when the weather information is sunny and the amount of electricity generated by the solar power generation system 200 is small during the morning and midday hours. Figure 6B is a diagram that also shows the amount of electricity consumed by the CO2 heat pump water heater 500 during hot water storage operation, as shown in Figure 6A.

[0064] In Figure 6A, the hourly change in the amount of power generated by the solar power generation system 200 increases from sunrise (5:00) until 11:00, while the power consumption of other household appliances 600 other than the CO2 heat pump water heater decreases after 7:00. On the other hand, because the absolute value of the amount of solar power generated is small (for example, the amount of solar power generated at 7:00 is small), the time when surplus power ≥ 0 is met is delayed. As a result, the energy management device 100 issues a command to start heating operation of the CO2 heat pump water heater 500 during the morning and daytime hours, based on the start time of operation specified by the contracted electricity rate pattern.

[0065] Figure 6B also shows the power consumption associated with the storage operation of the CO2 heat pump water heater 500. In this storage operation example, as in Figure 5B, regardless of surplus power, the heating operation of the CO2 heat pump water heater 500 starts based on the contracted power pattern, and the operation selects the heating amount to satisfy the required heating amount in the shortest possible time.

[0066] (Example of hot water storage operation 4) Figure 7A shows the relationship between the amount of electricity generated by solar power generation equipment and the amount of electricity consumed by household appliances other than the CO2 heat pump water heater, when the weather information is rain and the amount of electricity generated by solar power generation equipment is high during the morning and midday hours. Figure 7B is a diagram that adds the amount of electricity consumed by the CO2 heat pump water heater during its hot water storage operation to Figure 7A.

[0067] In Figure 7A, if the weather forecast is rain, the energy management device 100, at the time of generating the operation plan in step S110, specifies the time when the CO2 heat pump water heater 500 will start heating operation based on the contracted electricity rate pattern. Therefore, when the predetermined time is reached, it issues a command to start heating operation of the CO2 heat pump water heater 500.

[0068] Figure 7B shows the power consumption associated with the storage operation of the CO2 heat pump water heater 500. It can be seen that in this storage operation, heating operation starts based on the contracted power pattern, regardless of surplus power. Furthermore, the operation of the CO2 heat pump water heater 500 selects the heating amount to satisfy the required heating amount in the shortest possible time.

[0069] As described above, by managing the operation of the CO2 heat pump water heater 500 with the energy management device 100, it becomes possible to operate the system in a way that minimizes energy costs even in the event of sudden weather changes, while simultaneously consuming the amount of electricity generated by the solar power generation device 200 for self-consumption.

[0070] Returning to Figure 3, in step S140, the energy management device 100 issues a command to the CO2 heat pump water heater 500 to perform a boiling and heating operation. Upon receiving the command to perform a boiling and heating operation, the CO2 heat pump water heater 500 performs a boiling and heating operation in step S210 using the estimated boiling and heating amount and heating time. In step S210, the CO2 heat pump water heater 500, having completed the boiling and heating operation, issues an operation completion report to the energy management device 100, and the process moves to step S140 to confirm that the CO2 heat pump water heater 500 has completed operation normally.

[0071] With the configuration and control method described above, this embodiment makes it possible to monitor the amount of electricity generated from renewable energy sources and changes in contracted electricity rates. As a result, it becomes possible to appropriately determine whether or not to operate the CO2 heat pump water heater, thereby suppressing the increase in costs due to the use of commercial electricity and the opportunity to feed back electricity generated by solar power to the commercial power supply without consuming it. In other words, by controlling the CO2 heat pump water heater (storage-type water heater), it is possible to reduce surplus electricity generated by solar power.

[0072] In the embodiments of the present invention, the boiling time was described as being controlled by dividing it into two parts. However, it is clear that the effects of the present invention can be obtained even if the boiling time is divided into multiple parts.

[0073] Similarly, although this embodiment describes a method of control using electricity rate plans, it is clear that the same effect can be obtained with a method that allows for free fluctuations rather than fixed electricity rate plans. Furthermore, commercial electricity rate patterns are just one example; any pattern where rates are set higher for morning and daytime hours than for nighttime hours will exhibit the same effect.

[0074] According to this embodiment, as shown in Figure 6A, if the amount of sunlight is insufficient, contrary to the forecast, and power generation is insufficient, requiring the use of commercial power, it is possible to prevent the CO2 heat pump from being operated during peak hours when electricity rates are high. Even if there is sufficient sunlight, if the weather differs from the forecast and natural energy cannot be used to operate the CO2 heat pump water heater, appropriate hot water storage operation can be performed.

[0075] According to this embodiment, it becomes possible to monitor the amount of electricity generated from renewable energy sources and changes in contracted electricity rates. As a result, it becomes possible to appropriately determine whether or not to operate the CO2 heat pump water heater, thereby suppressing cost increases due to the use of commercial electricity and the opportunity to feed electricity generated by solar power back into the commercial power supply without consuming it.

[0076] Figure 8 shows the hardware configuration of the energy management device 100 according to the embodiment. The control device 1200 shown in Figure 8 is one of the realization forms of the control flow shown in Figure 3. The control device 1200 includes a memory 1201, a processor 1202, a storage device 1203 such as an HD (Hard Disk), a communication unit 1204 such as a NIC (Network Interface Card), and a user interface unit 1205. As an example of a processor, a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit) can be considered, but other semiconductor devices may also be used as the main entity that performs the predetermined processing.

[0077] Then, the program stored in the storage device 1203 is loaded into the memory 1201, and the loaded program is executed by the processor 1202. The control device 1200 may have a user interface unit 1205, which may include a display, touch panel, mouse, and keyboard.

[0078] Figure 9 shows an example of the functional configuration of the energy management device 100 according to the embodiment. As shown in Figure 9, it includes a first detection unit 11 that detects the amount of power generated by the solar power generation means, a second detection unit 12 that detects the amount of power consumed by other home appliances, an HP type water heater operation planning unit 13, a weather information acquisition unit 14 that acquires weather forecast information, a water heater power consumption estimation unit 15 that estimates the power consumption of the water heater from the operating status of the HP type water heater, and a power contract charge acquisition unit 16 that acquires power contract charges from power companies, etc.

[0079] The energy management system (EMS) according to this embodiment is an energy management system that manages the exchange of power between a solar power generation system, an HP-type water heater, and other home appliances. It consists of an energy management device 100, a broadband router 800, and an information input device 900. The system is constructed by connecting the energy management device 100 to the controlled solar power generation system 200, CO2 heat pump water heater 500 (HP-type water heater), and other home appliances 600 (air conditioners, washing machines, refrigerators, lighting, etc.) via a communication adapter 700.

[0080] As described above, by connecting the controlled equipment and the energy management device 100, it is possible to monitor the energy consumed and generated by the controlled equipment and to operate or stop the equipment. Furthermore, the energy management device 100 is provided with a function to connect to an external service 1000 via a broadband router 800 and an internetwork line. In this embodiment, a function is provided to learn and store in a database the amount of heat demand used by the CO2 heat pump water heater 500 in a day, a function is provided to store in a database the electricity rate pattern to which the user has a contract, a function is provided to estimate the energy consumption consumed when the CO2 heat pump water heater is operating, and a function is provided to determine whether or not to operate the CO2 heat pump water heater during the daytime.

[0081] By configuring and controlling the devices as described above, this embodiment limits the controlled devices from the solar power generation system 200 and the CO2 heat pump water heater 500 to other household appliances 600. This allows monitoring of the amount of power generated and the energy consumed by devices other than the CO2 heat pump water heater when determining whether or not to operate the CO2 heat pump water heater during the daytime. As a result, the energy management device 100 according to this embodiment can accurately recognize the amount of power that can be used by the CO2 heat pump water heater 500 (surplus power).

[0082] Furthermore, in this embodiment, a broadband router 800 is connected, providing a function to connect to external information services via the internet. As a result, in this embodiment, when generating the operation plan, expected weather information can be used, and water heating operation patterns such as heating only during nighttime hours, or heating during both nighttime and daytime hours can be generated.

[0083] Furthermore, in this embodiment, a function is provided to learn, database, and store the amount of heat demand used by the user in a day. As a result, the energy management device 100 of this embodiment can estimate the amount of heat and heating time that the CO2 heat pump water heater 500 will heat during nighttime and daytime hours.

[0084] Furthermore, in this embodiment, an estimation method is provided to estimate the amount of energy consumed when the CO2 heat pump water heater is in operation, based on the heating amount, the outside air temperature, and the temperature of the water supplied to the CO2 heat pump water heater. This makes it possible to evaluate the amount of energy consumed by the CO2 heat pump water heater before operation, and by comparing the surplus power with the energy consumed by the CO2 heat pump water heater 500, it is possible to accurately determine whether or not the CO2 heat pump water heater 500 can be operated.

[0085] Furthermore, a function has been added to create a database of the electricity rate patterns that users have contracted. This allows users to operate the CO2 heat pump water heater 500 using commercial electricity by selecting low-cost time periods.

[0086] Although this embodiment was described as an energy management system, the control method for the energy management system that manages the exchange of power between the solar power generation means, the HP type water heater, and other equipment (other home appliances) has the following characteristics. The energy management system includes a first detection unit 11 for detecting the amount of power generated by the solar power generation means (solar power generation device 200), a second detection unit 12 for detecting the amount of power consumed by other home appliances, and an operation planning unit 13 for the HP-type water heater. In the operation plan, when performing hot water storage operation during daytime hours, if the difference between the amount of power generated by the solar power generation means and the amount of power consumed by other home appliances is greater than the amount of power consumed when the HP-type water heater is operating at its minimum capacity, the operation planning unit 13 will perform hot water storage operation of the HP-type water heater. As a decision to start hot water storage operation during daytime hours, the system predicts that the amount of power generated will be 0 or increasing based on the rate of change of the amount of power generated, and predicts that the power consumed by other home appliances will be 0 or decreasing based on the rate of change of the power consumed by other home appliances. This allows for the appropriate start of hot water storage operation. The energy management device 100 of the energy management system has the same effect even when it is on the cloud.

[0087] While the above embodiments described the case where the present invention is applied to a home, the "other equipment" may differ as appropriate when the present invention is installed in a relatively small office, workplace, shop, etc., such as one that includes a solar power generation system and an HP-type water heater. Furthermore, although the HP type water heater was described in the embodiment as a CO2 heat pump water heater 500 using carbon dioxide, a natural refrigerant, the HP type water heater may also use flammable natural refrigerants such as propane, isobutane, or propylene. [Explanation of Symbols]

[0088] 11 First detection unit 12 Second detection unit 13. Operation Planning Department 14 Weather Information Acquisition Department 15. Water heater power consumption estimation unit 16. Electricity Contract and Charge Acquisition Department 100 Energy Management Systems (HEMS) 200 Solar power generation equipment (solar power generation means) 300 Power Conditioner 400 distribution board 500 CO2 heat pump water heater (HP type water heater) 510 Heat Pump Unit 511 Compressor 512 Water heat exchanger 513 Expansion valve 514 Heat exchanger 515 Fans 520 Hot water storage unit 521 Pump 522 Hot water storage tank 523 Water Piping 524 Water tap 600 Other home appliances (other equipment) 700 Communication Adapter 800 Broadband Router 900 Information input devices (user interfaces) 1000 External Services EMS Energy Management System

Claims

1. An energy management system that manages the exchange of electricity between a solar power generation system, an HP-type water heater, and other equipment, The aforementioned energy management system is A first detection unit for detecting the amount of power generated by the aforementioned solar power generation means, A second detection unit that detects the power consumption of other devices, The HP type water heater includes an operation planning unit, The operation planning unit, in its operation plan, determines that when performing hot water storage operation during daytime hours, if the difference between the amount of power generated by the solar power generation means and the amount of power consumed by the other equipment is greater than the amount of power consumed when the HP-type water heater is operated at its minimum capacity, then when performing hot water storage operation of the HP-type water heater, As a decision to start the hot water storage operation during daytime hours, the HP-type water heater will start the hot water storage operation if, based on the rate of change of the power generation amount, the power generation amount is predicted to be zero or increasing, and based on the rate of change of the power consumption of the other equipment, the power consumption of the other equipment is predicted to be zero or decreasing. An energy management system characterized by the following features.

2. In the energy management system according to claim 1, further, Equipped with a weather information acquisition unit that acquires weather forecast information, The aforementioned weather information acquisition unit acquires weather forecast information before the start of the off-peak electricity period. The aforementioned operation planning unit generates an operation plan that, when the acquired weather forecast information matches the pre-set weather information, suppresses hot water storage operation using off-peak electricity and generates hot water using the electricity from the solar power generation means. An energy management system characterized by the following features.

3. In the energy management system according to claim 1, further, A water heater power consumption estimation unit that estimates the power consumption of the water heater based on the operating status of the aforementioned HP-type water heater, It includes a weather information acquisition unit that acquires weather forecast information, The water heater power consumption estimation unit estimates the power consumption of the water heater using the heating amount of the water heater, the outside air temperature during water heater operation, and the water supply temperature during water heater operation. An energy management system characterized by the following features.

4. In the energy management system according to claim 3, The estimated power consumption increases with increasing heating capacity of the water heater, decreases with increasing ambient temperature during water heater operation, and increases with increasing water supply temperature during water heater operation. An energy management system characterized by the following features.

5. In the energy management system according to claim 3, The aforementioned water heater power consumption estimation unit uses the heating amount of the water heater, the ambient temperature during water heater operation, and the water supply temperature during water heater operation as parameters to estimate power consumption as a model that linearly combines the changes in heating amount, ambient temperature, and water supply temperature. The constant terms for heating amount and water supply temperature have positive values, while the constant term for ambient temperature has a negative value. An energy management system characterized by the following features.

6. In the energy management system according to claim 2 or claim 3, When generating an operation plan for the HP-type water heater, the operation planning unit uses weather forecast information acquired by the weather information acquisition unit to determine whether to store hot water using daytime electricity, nighttime electricity, or both daytime and nighttime electricity generated by the solar power generation means, and then generates an operation plan for the HP-type water heater. An energy management system characterized by the following features.

7. A control method for an energy management system that manages the exchange of electricity between a solar power generation system, an HP type water heater, and other equipment, The aforementioned energy management system is A first detection unit for detecting the amount of power generated by the aforementioned solar power generation means, A second detection unit that detects the power consumption of other devices, The HP type water heater includes an operation planning unit, The operation planning unit, in its operation plan, determines that when performing hot water storage operation during daytime hours, if the difference between the amount of power generated by the solar power generation means and the amount of power consumed by the other equipment is greater than the amount of power consumed when the HP-type water heater is operated at its minimum capacity, then when performing hot water storage operation of the HP-type water heater, As a decision to start the hot water storage operation during daytime hours, the HP-type water heater will start the hot water storage operation if, based on the rate of change of the power generation amount, the power generation amount is predicted to be zero or increasing, and based on the rate of change of the power consumption of the other equipment, the power consumption of the other equipment is predicted to be zero or decreasing. A control method for an energy management system characterized by the following.

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