Power storage system

Abstract

To store more power in a power storage device in preparation for peak cuts in purchased power at a facility.SOLUTION: A power storage system includes: a power storage device installed in a facility such as a home that receives a supply of purchased power from a power system such as a power grid, power demand devices (air conditioners, heat pump water heaters, charging / discharging devices, and electric vehicles) that use power different from the power storage device, and a HEMS controller that manages the use of power in the power storage device and the demand devices. The HEMS controller includes a processor such as a CPU of a control unit. After limiting the use of purchased power in the demand devices (a step S122), the processor controls the power storage device to be charged (a step S125) if the remaining capacity stored in the power storage device is equal to or less than a predetermined value (YES in a step S124).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This disclosure relates to a power storage system, and in particular to a power storage system that is installed in a facility that receives power from a power grid and includes a power storage device, a power demand device that is different from the power storage device, and a management device that manages the use of power in the power storage device and the power demand device. [Background technology]

[0002] Conventionally, there have been energy storage systems installed in homes that include fixed storage batteries that store commercial power and power generated by power generation devices such as solar cells (see, for example, Patent Document 1). In such homes, the commercial power purchase contract may stipulate a basic charge based on the peak power of the power purchased at the home. In such cases, the purchased power is used at the home so as not to exceed the peak power. In the energy storage system of Patent Document 1, when charging an electric vehicle at the home, the amount of power that is expected to exceed the peak power when the electric vehicle is charged is charged in advance to the fixed storage battery based on information about the expected time the electric vehicle is expected to return home. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-062618 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology of Patent Document 1, when charging a fixed storage battery in advance, if there is a large demand for power from other devices installed in a facility such as a house, there is a risk that the fixed storage battery may not be charged with the amount of power required.

[0005] This disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a power storage system that can store more electricity in a power storage device in preparation for peak cutting of purchased power in a facility. [Means for solving the problem]

[0006] The power storage system according to the present disclosure is a system provided in a facility that receives a supply of purchased power from a power grid, and includes a power storage device, a power demand device different from the power storage device, and a management device that manages the use of power in the power storage device and the power demand device. The management device includes a processor. After limiting the use of purchased power by the demand device, the processor controls the power storage device to be charged when the remaining capacity stored in the power storage device is equal to or less than a predetermined value.

[0007] According to this configuration, after limiting the use of purchased power by a power demand device different from the power storage device installed in the facility, if the remaining capacity stored in the power storage device is equal to or less than a predetermined value, the power storage device is charged. As a result, it is possible to provide a power storage system that can store more power in the power storage device in preparation for peak cuts in purchased power in the facility.

[0008] The processor may perform control to limit the use of purchased power by the consumer equipment when peak shaving of purchased power is required in the facility.

[0009] With this configuration, it is possible to more reliably store more power in the power storage device in preparation for peak cuts in purchased power in the facility.

[0010] The processor may be configured to control charging of the storage device if, after restricting the use of purchased power in the demand device, the power demand in the demand device is less than a predetermined first power and the remaining capacity stored in the storage device is less than a predetermined value.

[0011] With this configuration, it is possible to more reliably store more power in the power storage device in preparation for peak cuts in purchased power in the facility.

[0012] The processor may be configured to control the power storage device to discharge power when the power demand of the demand device is equal to or greater than a predetermined second power that is equal to or greater than a predetermined first power after restricting the use of purchased power by the demand device.

[0013] According to this configuration, even if the use of purchased power by the demand equipment is restricted, power can be appropriately supplied to the demand equipment.

[0014] The processor may be configured to control the demand equipment to limit the use of purchased power when peak cutting of power usage is not required in the facility, when charging of the storage device is required, and when the power demand of the demand equipment is not less than a predetermined third power, and then control the storage device to charge when the power demand of the demand equipment becomes less than the predetermined third power.

[0015] With this configuration, it is possible to store more power in the power storage device in preparation for peak cuts in purchased power in the facility. [Effects of the Invention]

[0016] According to this disclosure, it is possible to provide a power storage system that can store more power in a power storage device in preparation for peak cuts in purchased power in a facility. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram illustrating an overall configuration of a power system according to an embodiment of the present invention. [Figure 2] 10 is a flowchart showing the flow of peak cut-related processing in this embodiment. [Figure 3] 10 is a graph showing changes in power consumption in a conventional house. [Figure 4] 10 is a graph showing a change in power consumption in a house after measures are taken in this embodiment. [Figure 5] 10 is a diagram showing a change in the amount of reduction in power consumption of an electrical device and a change in the SOC of a power storage device. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0019] Fig. 1 is a diagram schematically illustrating the overall configuration of a power system 1 according to this embodiment. As shown in Fig. 1, the power system 1 includes a house 10, a power grid 20, a smart meter 30, an electric vehicle 40, and a Home Energy Management System (HEMS) controller 100.

[0020] The power grid 20 is an electric power system consisting of power plants, transmission lines, substations, distribution lines, etc., and is managed by an electric power retailer or the like. The power grid 20 and the in-home power lines of the home 10 are connected via a smart meter 30. The smart meter 30 is an electronic watt-hour meter with a communication function, which measures the amount of electric power exchanged between the power grid 20 and the home 10, and periodically transmits the measured amount of electric power together with an identification code (ID) of the smart meter 30 to a server of the electric power retailer or the like.

[0021] In a house 10 connected to a power grid 20 via a smart meter 30, various electrical devices such as an air conditioner (heating and cooling device) 13, a heat pump water heater 14, a power storage device 15, a solar power generation device 16, and a charging / discharging device 17 are connected using in-home power lines via a distribution board 12. This allows these electrical devices to consume power supplied from the power grid 20, and allows power generated by the solar power generation device 16 and power discharged from an electric vehicle 40 to be supplied to the power grid 20 (reverse power flow).

[0022] The charging / discharging device 17 is capable of charging the battery 42 of the electric vehicle 40 and of transmitting power discharged from the electric vehicle 40 back to the power grid 20 by connecting the connector 171 at the end of the cable to the inlet 46 of the electric vehicle 40.

[0023] The electrically powered vehicle 40 is a battery electric vehicle (BEV) equipped with a battery 42. However, the type of electrically powered vehicle 40 may be any vehicle that can be connected to a charging / discharging device 17, and may be a plug-in hybrid electric vehicle (PHEV) or a plug-in fuel cell electric vehicle (FCEV).

[0024] The electric vehicle 40 includes an ECU (Electronic Control Unit) 41, a DCM (Data Communication Module) 45, a battery 42, a charger / discharger 43, and an inlet 46.

[0025] The battery 42 includes a secondary battery, such as a lithium-ion battery or a nickel-metal hydride battery, that can charge and discharge power, and a monitoring unit for the secondary battery. The monitoring unit monitors the state of the secondary battery (for example, voltage, current, temperature, etc.) and transmits the monitoring results to the ECU 41.

[0026] The inlet 46 can be connected to a connector for charging and discharging, such as the connector 171 of the charging and discharging device 17, and receives power supplied from the outside and outputs the power of the battery 42 to the outside.

[0027] When charging, the charger / discharger 43 converts AC power input to the inlet 46 into DC and charges the battery 42, and when discharging, it converts the DC power of the battery 42 into AC and discharges it from the inlet 46.

[0028] The DCM 45 wirelessly transmits information such as data from the ECU 41 to an external device, and transfers information such as data wirelessly transmitted from an external device to the ECU 41.

[0029] The ECU 41 includes a processor such as a CPU (Central Processing Unit) and a memory, and controls the entire electric vehicle 40 including the charger / discharger 43, the DCM 45, and the drive system.

[0030] The HEMS controller 100 includes a control unit 110, a memory unit 120, an operation unit 130, an output unit 140, and a communication unit 150, and manages the use of power by electrical appliances in the home 10. The output unit 140 includes a display and a speaker. The operation unit 130 includes a touch panel and other operation buttons formed on the surface of the display screen. The communication unit 150 has a communication function for communicating with external devices wirelessly or via a cable. The memory unit 120 includes a memory and stores programs and data used by the control unit 110. The control unit 110 includes a CPU as a processor, processes data from the memory unit 120 or the communication unit 150 or operation information from the operation unit 130, and outputs the processing results to the output unit 140, the memory unit 120, or the communication unit 150.

[0031] In a home 10 equipped with a power storage system including the above-described power storage device 15, a basic charge may be set in a commercial power purchase contract according to the peak power of power purchased at the home 10. In this case, the purchased power is used at the home 10 so as not to exceed the peak power. In this power storage system, when charging the electric vehicle 40 at the home 10, an amount that is expected to exceed the peak power when charging the electric vehicle 40 is charged in advance to the power storage device 15 based on information about the expected return time of the electric vehicle 40. When charging the power storage device 15 in advance, if there is a high demand for power from other electrical appliances provided in a facility such as the home 10, there is a risk that the amount of power required for the power storage device 15 cannot be charged.

[0032] Therefore, the power storage system is installed in a facility such as a home 10 that receives a supply of purchased power from a power system such as a power grid 20, and includes a power storage device 15, power demand devices different from the power storage device 15, and a HEMS controller 100 that manages the use of power in the power storage device 15 and the demand devices. The HEMS controller 100 includes a CPU in a control unit 110. After restricting the use of purchased power in the demand devices, the CPU in the control unit 110 controls the power storage device 15 to be charged if the remaining capacity stored in the power storage device 15 is equal to or less than a predetermined value.

[0033] As a result, after restricting the use of purchased power by power demand devices different from the power storage device 15 installed in the facility, if the remaining capacity stored in the power storage device 15 is equal to or less than a predetermined value, the power storage device 15 is charged. As a result, more power can be stored in the power storage device 15 in preparation for peak cuts in purchased power in the facility.

[0034] 2 is a flowchart showing the flow of peak cut-related processing according to this embodiment. Referring to FIG. 2, this peak cut-related processing is called from a higher-level processing by the CPU of the control unit 110 of the HEMS controller 100 and executed.

[0035] First, the CPU of control unit 110 determines whether or not it is now a predetermined cycle of determination timing (step S111). If it is determined that it is now the determination timing (YES in step S111), the CPU determines whether or not charging of power storage device 15 is required (step S112). This determination is made, for example, by determining whether or not the SOC or remaining energy of power storage device 15 is less than a predetermined value L0, and determines that charging is required if it is less than the predetermined value L0, and determines that charging is not required if it is equal to or greater than the predetermined value L0.

[0036] If it is determined that charging of the power storage device 15 is necessary (YES in step S112), the CPU of the control unit 110 determines whether the total power demand of the electrical appliances other than the power storage device 15 in the house 10 is less than a predetermined value L1 (step S113). If it is determined that the power demand is not less than the predetermined value L1 (NO in step S113), the CPU calculates the amount of demand reduction that can be achieved by the electrical appliances other than the power storage device 15, and shifts the control state of the other electrical appliances to a reduction mode that reduces the power demand by the calculated amount of demand reduction (step S114).

[0037] Next, as a result of the control in step S114, it is determined whether the total power demand of the other electrical devices is less than predetermined value L1 (step S115). If it is determined in step S115 that the power demand is less than predetermined value L1 (YES in step S115), or if it is determined in step S113 that the power demand is less than predetermined value L1 (YES in step S113), the CPU of control unit 110 controls distribution board 12 and power storage device 15 to charge power storage device 15 (step S116).

[0038] If it is determined that it is not the timing for determination (NO in step S111), if it is determined that charging of power storage device 15 is unnecessary (NO in step S112), if it is determined in step S115 that the power demand is no longer less than predetermined value L1 (NO in step S115), or after step S116, the CPU of control unit 110 determines whether or not the current time is a time when peak shaving is necessary to reduce the peak power of purchased power (step S121). A time when peak shaving is necessary is a time period when all power demands in facilities such as residence 10 are likely to exceed the peak power of the commercial power purchase contract, for example, a time period when power demand has exceeded a predetermined percentage (e.g., 80%) of the peak power during a predetermined period in the past (e.g., the past year).

[0039] If it is determined that peak cutting is necessary (YES in step S121), the CPU of the control unit 110 calculates the amount of demand reduction that can be achieved by electrical equipment other than the storage device 15, and transitions the control state of the other electrical equipment to a reduction mode that reduces the power demand by the calculated amount of demand reduction (step S122).

[0040] Next, as a result of the control in step S122, it is determined whether the total power demand of the other electrical devices is less than a predetermined value L2 (step S123). If it is determined that the power demand is less than the predetermined value L2 (YES in step S123), the CPU of control unit 110 determines whether the remaining amount of energy (remaining capacity) of power storage device 15 is less than a predetermined value L3 (step S124). If it is determined that the remaining capacity is less than the predetermined value L3 (YES in step S124), the CPU controls distribution board 12 and power storage device 15 to charge power storage device 15 (step S125).

[0041] On the other hand, if it is determined that the power demand is not less than the predetermined value L2 (NO in step S123), the CPU of the control unit 110 determines whether the power demand exceeds a predetermined value H2 (≧L2) (step S126). If it is determined that the power demand exceeds the predetermined value H2 (YES in step S126), the CPU controls the distribution board 12 and the power storage device 15 to discharge power from the power storage device 15 to another electrical device (step S127).

[0042] When it is determined that peak cutting is not necessary (NO in step S121), when it is determined that the remaining capacity of the power storage device 15 is not less than the predetermined value L3 (NO in step S124), when it is determined that the power demand does not exceed the predetermined value H2 after step S125 (NO in step S126), or after step S127, the CPU of the control unit 110 returns the processing to be executed to the higher-level processing that called this peak cutting-related processing.

[0043] FIG. 3 is a graph showing changes in power consumption in a conventional house 10. Referring to FIG. 3, the horizontal axis represents time, and the vertical axis represents average power consumption in each time period. The dashed line represents power consumption in the house 10 when power demand is not reduced. The dash-dotted line represents power consumption in the house 10 when the power demand of the air conditioner 13 is reduced. The solid line represents power consumption in the house 10 when the power demand of the air conditioner 13 is reduced and power is discharged from the power storage device 15.

[0044] Conventionally, for example, the power demand of the air conditioner 13 is reduced modestly (for example, by 2 kW) between 6:00 and 9:00, thereby reducing the average power demand of the electrical appliances in the house 10 from 7 kW to 5 kW.

[0045] Between 10:00 and 14:00, the average power demand increases to 11 kW, so the power demand of air conditioner 13 is reduced to the maximum (for example, -3 kW). As a result, the average power demand of the electrical appliances in house 10 becomes 8 kW. Furthermore, by discharging (for example, 3 kW) from power storage device 15, the average power demand of house 10 becomes the target demand of 5 kW.

[0046] After 3:00 PM, the average power demand decreases to 9 kW, and the power demand of air conditioner 13 is reduced to the maximum (for example, -3 kW). As a result, the average power demand of the electrical appliances in house 10 becomes 6 kW. However, the remaining capacity of power storage device 15 runs out, and power storage device 15 can no longer discharge, so the power demand cannot be reduced to the target demand of 5 kW.

[0047] FIG. 4 is a graph showing changes in power usage in house 10 after measures are taken in this embodiment. Referring to FIG. 4, the horizontal axis, vertical axis, and types of lines are the same as those in FIG. 3. For example, from 6:00 to 9:00 is determined to be a time when peak cutting is necessary in step S121 of FIG. 2, and step S122 is executed to reduce the power demand of air conditioner 13 to the maximum (for example, -3 kW). Here, the power demand becomes 4 kW, and it is determined in step S123 of FIG. 2 that the power demand is less than predetermined value L2 (=5 kW), which is the target demand, and step S125 is executed to charge power storage device 15 (here, charging with 1 kW, which is the difference between the power demand and the target demand).

[0048] Between 10:00 and 14:00, the average power demand increases to 11 kW, and the power demand of air conditioner 13 is reduced to the maximum (for example, -3 kW). As a result, the average power demand of the electrical appliances in house 10 becomes 8 kW. Furthermore, by discharging power from power storage device 15 (for example, 3 kW), the average power demand of house 10 becomes the target demand of 5 kW.

[0049] After 3:00 PM, the average power demand decreases to 9 kW, but in step S121 of FIG. 2, it is determined that peak shaving is necessary, and step S122 is executed to reduce the power demand of air conditioner 13 to the maximum extent (for example, -3 kW). As a result, the power demand of the electrical appliances in house 10 becomes 6 kW. Here, in step S123 of FIG. 2, it is determined that the power demand is not less than predetermined value L2 (= 5 kW), which is the target demand, and in step S126, it is determined that the power demand exceeds predetermined value H2 (= 5 kW). In this case, by executing step S127, discharge from power storage device 15 (here, discharge of 1 kW, which is the difference between the power demand and the target demand) is executed. As a result, the average power demand of house 10 becomes the target demand of 5 kW. In this case, because charging to power storage device 15 was executed between 6:00 AM and 9:00 AM, there is a surplus remaining in the capacity of power storage device 15, and therefore, discharging from power storage device 15 can continue until 10:00 PM.

[0050] FIG. 5 is a diagram showing changes in the amount of reduction in power consumption of electrical devices and changes in the SOC of power storage device 15. Referring to FIG. 5(A), the horizontal axis represents time, and the vertical axis represents the amount of reduction in power consumption of electrical devices. The dashed line represents changes in the amount of reduction in power consumption of air conditioner 13 in the past. The solid line represents changes in the amount of reduction in power consumption of air conditioner 13 after the measures of this embodiment are implemented. As shown in FIGS. 3 and 4, conventionally, the amount of reduction in power demand of air conditioner 13 was modest (for example, -2 kW) from 6:00 to 9:00, and was maximized (for example, -3 kW) from 10:00 onwards. After the measures of this embodiment are implemented, the amount of reduction in power demand of air conditioner 13 is maximized (for example, -3 kW) from 6:00 onwards.

[0051] Referring to FIG. 5(B), the horizontal axis represents time, and the vertical axis represents the SOC of power storage device 15. The dashed line represents the change in SOC of power storage device 15 in the conventional case. The solid line represents the change in SOC of power storage device 15 after the countermeasure of this embodiment is implemented. As shown in FIGS. 3 and 4, conventionally, power storage device 15 was not charged when peak shaving was required, so the SOC of power storage device 15 remained flat from 6:00 to 9:00. Furthermore, power storage device 15 was discharged after 10:00, so the SOC of power storage device 15 reached 0% at 3:00.

[0052] After the countermeasure in this embodiment is implemented, power storage device 15 is charged from 6:00 to 9:00, and the SOC of power storage device 15 increases. After 10:00, power storage device 15 is discharged as in the conventional case. After 15:00, the power demand of air conditioner 13 decreases, and the decrease in SOC becomes gradual. Since the SOC of power storage device 15 does not run out even after 15:00, the target demand can be maintained.

[0053] [Variations] (1) In the above-described embodiment, the facility is a residence 10 as shown in Fig. 1. However, the present invention is not limited to this, and the facility may be any other facility or may be a business establishment that conducts some kind of business.

[0054] (2) In the above-described embodiment, as shown in Fig. 1 and Fig. 2, the power storage device 15 is charged, and the power charged in the power storage device 15 is used in an electrical device other than the power storage device 15. However, the present invention is not limited to this. Instead of the power storage device 15 or together with the power storage device 15, the battery 42 of the electric vehicle 40 may be charged, and the power charged in the battery 42 may be used in an electrical device in a facility such as the house 10.

[0055] [summary] (1) As shown in FIG. 1, the power storage system is a system including a power storage device 15 provided in a facility such as a home 10 that receives a supply of purchased power from a power grid 20, power demand devices different from the power storage device 15 (e.g., an air conditioner 13, a heat pump water heater 14, a charging / discharging device 17, and an electric vehicle 40), and a HEMS controller 100 that manages the use of power in the power storage device 15 and the demand devices. As shown in FIG. 1, the HEMS controller includes a processor such as the CPU of the control unit 110. As shown in FIG. 2, after restricting the use of purchased power in the demand devices (e.g., step S122), the processor controls the power storage device to be charged (e.g., step S125) if the remaining capacity stored in the power storage device 15 is equal to or less than a predetermined value (e.g., YES in step S124).

[0056] As a result, after restricting the use of purchased power by power demand devices different from the power storage device 15 installed in the facility, if the remaining capacity stored in the power storage device 15 is equal to or less than a predetermined value, the power storage device 15 is charged. As a result, more power can be stored in the power storage device 15 in preparation for peak cuts in purchased power in the facility.

[0057] (2) As shown in FIG. 2, the processor may control the consumer equipment to limit the use of purchased power (e.g., step S122) when peak cutting of purchased power is required in the facility (e.g., YES in step S121).

[0058] This makes it possible to more reliably store more power in the power storage device 15 in preparation for peak cuts in purchased power in the facility.

[0059] (3) As shown in FIG. 2, after restricting the use of purchased power in the demand equipment, if the power demand in the demand equipment is less than a predetermined first power (for example, if YES in step S123) and if the remaining capacity stored in the power storage device 15 is less than or equal to a predetermined value (for example, if YES in step S124), the processor may control the power storage device 15 to be charged (for example, step S125).

[0060] This makes it possible to more reliably store more power in the power storage device 15 in preparation for peak cuts in purchased power in the facility.

[0061] (4) As shown in FIG. 2, after restricting the use of purchased power in the demand equipment, if the power demand in the demand equipment is equal to or greater than a predetermined second power (e.g., a predetermined value H2) that is equal to or greater than a predetermined first power (e.g., a predetermined value L2) (e.g., YES in step S126), the processor may control the storage device to discharge (e.g., step S127).

[0062] This allows power to be appropriately supplied to the demand equipment even when the use of purchased power by the demand equipment is restricted.

[0063] (5) As shown in FIG. 2, if the facility does not require peak cutting of power usage (for example, if YES in step S111), and if charging of the power storage device 15 is required (for example, if YES in step S112), and if the power demand of the demand equipment is not less than the predetermined third power (for example, if NO in step S113), the processor may control the demand equipment to limit the use of purchased power (for example, step S114), and then, if the power demand of the demand equipment becomes less than the predetermined third power (for example, if YES in step S115), control the demand equipment to charge the power storage device 15 (for example, step S116).

[0064] This allows more power to be stored in the power storage device 15 in preparation for peak cuts in purchased power in the facility.

[0065] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0066] 1 Power system, 10 House, 12 Distribution board, 13 Air conditioner, 14 Heat pump water heater, 15 Energy storage device, 16 Solar power generation device, 17 Charging / discharging device, 20 Power grid, 30 Smart meter, 40 Electric vehicle, 41 ECU, 42 Battery, 43 Charger / discharger, 45 DCM, 46 Inlet, 100 HEMS controller, 110 Control unit, 120 Memory unit, 130 Operation unit, 140 Output unit, 150 Communication unit, 171 Connector.

Claims

1. A power storage system provided in a facility that receives a supply of purchased power from a power grid, the power storage system including a power storage device, a power demand device different from the power storage device, and a management device that manages the use of power in the power storage device and the power demand device, the management device includes a processor; The processor controls the storage device to charge when the remaining capacity stored in the storage device is equal to or less than a predetermined value after restricting the use of purchased power by the consumer equipment.

2. The power storage system according to claim 1 , wherein the processor controls the consumer equipment to limit use of purchased power when peak shaving of purchased power is required in the facility.

3. 3. The energy storage system of claim 2, wherein the processor controls the energy storage device to be charged when, after restricting the use of purchased power in the demand equipment, the power demand in the demand equipment is less than a predetermined first power and when the remaining capacity stored in the energy storage device is less than a predetermined value.

4. 4. The energy storage system according to claim 3, wherein the processor controls the energy storage device to discharge when the demand for power in the demand equipment is equal to or greater than a predetermined second power that is equal to or greater than the predetermined first power after restricting the use of purchased power in the demand equipment.

5. 5. The energy storage system according to claim 1, wherein the processor controls the demand equipment to limit use of purchased power when peak power shaving is not required in the facility, when charging of the energy storage device is required, and when the power demand of the demand equipment is not less than a predetermined third power, and then controls the energy storage device to be charged when the power demand of the demand equipment becomes less than the predetermined third power.

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