Power management device, power management system, and method for providing power service

Abstract

To provide a power management device that can easily equalize power supply and demand.SOLUTION: A power management device 100 includes a communication unit 103 (acquisition unit) that acquires information regarding power supply and demand in a power bank 200 (power storage device), and a processor 101 (control unit) that controls power received by an electric vehicle 10 from the power bank 200, and the processor 101 sets the power exchange ratio of the power received from the power bank 200 to the power supplied to the power bank 200 in accordance with the power supply and demand. Furthermore, the processor 101 determines the amount of power received by the electric vehicle 10 from the power bank 200 on the basis of the amount of power supplied from the electric vehicle 10 to the power bank 200 and the power exchange ratio.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a power management device, a power management system, and a method for providing power services. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2021-129441 (Patent Document 1) discloses a server that controls the charging and discharging of power between an electric vehicle and a charging and discharging station that are connected to each other. The charging and discharging controls level out the supply and demand of power in the power grid. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-129441 Summary of the Invention [Problem to be solved by the invention]

[0004] The server in Patent Document 1 does not take into consideration that charging and discharging of power is performed based on the power supply and demand status in the power grid. This can make it difficult to equalize power supply and demand. It is desirable to easily equalize power supply and demand.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a power management device, a power management system, and a method for providing power services that can easily equalize power supply and demand. [Means for solving the problem]

[0006] A power management device according to a first aspect of the present disclosure provides power services to a user having a power source capable of supplying power to a power storage device and a load capable of receiving power from the power storage device, and includes an acquisition unit that acquires power supply and demand in the power storage device, and a control unit that controls power received by the load from the power storage device. The control unit sets a power exchange ratio of power received from the power storage device to power supplied to the power storage device according to the power supply and demand, and determines the amount of power received by the load from the power storage device based on the amount of power supplied from the power source to the power storage device and the power exchange ratio.

[0007] As described above, in the power management device according to the first aspect of the present disclosure, the amount of power received by the load from the power storage device is determined based on the power exchange rate set according to the power demand. This allows the amount of power drawn by the electric vehicle from the power storage device to be set according to the power supply and demand. As a result, the power supply and demand can be easily equalized.

[0008] In the power management device according to the first aspect, preferably, the control unit reduces the amount of power received by the load from the power storage device by setting a lower power exchange rate as the power storage device has a greater power shortage. With this configuration, when the power storage device has a power shortage, the amount of power drawn by the electric vehicle from the power storage device can be reduced. As a result, when the power storage device has a power shortage (when power supply and demand is tight), power demand can be easily leveled.

[0009] In this case, preferably, when the amount of power supplied from the power source to the power storage device is greater than a predetermined first threshold, the control unit reduces the degree of decrease in the power exchange rate compared to when the amount of power supplied from the power source to the power storage device is less than the first threshold. With this configuration, it is possible to prevent excessive restrictions on the amount of power that can be drawn by a user who is supplying a relatively large amount of power to the power storage device.

[0010] In the power management device that reduces the degree of reduction in the power exchange rate when the amount of power supply is greater than a predetermined first threshold, preferably, the control unit does not reduce the power exchange rate when the amount of power supply from the power source to the power storage device is greater than a second threshold that is greater than the first threshold. With this configuration, it is possible to further prevent excessive restrictions on the amount of power that can be drawn by a user who is supplying a relatively large amount of power to the power storage device.

[0011] In the power management device according to the first aspect, the acquisition unit preferably acquires information on at least one of the amount of power stored in the power storage device, temperature, and season. The control unit determines power supply and demand based on the at least one piece of information. With this configuration, power supply and demand can be easily determined based on at least one of the amount of power stored in the power storage device, temperature, and season.

[0012] A management system according to a second aspect of the present disclosure includes a power storage device, a power source capable of supplying power to the power storage device, and a power management device that provides power services to a user having a load capable of receiving power from the power storage device. The power management device includes an acquisition unit that acquires power supply and demand in the power storage device, and a control unit that controls power received by the load from the power storage device. The control unit sets a power exchange ratio of power received from the power storage device to power supplied to the power storage device according to the power supply and demand, and determines the amount of power received by the load from the power storage device based on the amount of power supplied from the power source to the power storage device and the power exchange ratio.

[0013] In the management system according to the second aspect of the present disclosure, as described above, the amount of power received by the load from the power storage device is determined based on the power exchange rate set according to the power supply and demand, thereby providing a management system that can easily equalize the power supply and demand.

[0014] A management method according to a third aspect of the present disclosure is a method for providing an electric power service to a user having a power source capable of supplying power to a power storage device and a load capable of receiving power from the power storage device, the method including: acquiring power supply and demand in the power storage device; and setting a power exchange ratio of power received from the power storage device to power supplied to the power storage device according to the power supply and demand. The setting step includes determining an amount of power received by the load from the power storage device based on the amount of power supplied from the power source to the power storage device and the power exchange ratio.

[0015] In the management method according to the third aspect of the present disclosure, as described above, the amount of power received by the load from the power storage device is determined based on the power exchange rate set according to the power supply and demand. This makes it possible to provide a method for providing an electric power service that can easily level the power supply and demand. [Effects of the Invention]

[0016] According to the present disclosure, power supply and demand can be easily equalized. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram illustrating a configuration of a power management system according to an embodiment. [Figure 2] FIG. 10 is a diagram showing the power exchange ratio when there is no power shortage (temperature 20° C.). [Figure 3] FIG. 10 is a diagram showing the power exchange ratio during a power shortage (temperature 20° C.). [Figure 4] FIG. 10 is a diagram showing a state in which the degree of decrease in the power exchange rate is mitigated. [Figure 5] FIG. 10 is a diagram illustrating a state in which control for reducing the power exchange ratio is not executed. [Figure 6] FIG. 10 is a diagram showing the power exchange ratio during a power shortage (temperature 0° C.). [Figure 7] FIG. 2 is a sequence diagram illustrating a method for providing a power service by a power management system according to an embodiment. [Figure 8] FIG. 10 is a diagram illustrating a configuration of a power management system according to a modified example of an embodiment. 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 illustrating the configuration of a power management system 1 according to an embodiment of the present disclosure. The power management system 1 includes a power management device 100, a power bank 200, a plurality of electric vehicles 10, and a plurality of EVSEs (Electric Vehicle Supply Equipment) 20. Note that the power management system 1 may include only one each of the electric vehicles 10 and the EVSEs 20. The power bank 200 is an example of a "power storage device" in the present disclosure. The electric vehicles 10 are an example of a "power source" and a "load" in the present disclosure.

[0020] Electrically powered vehicles 10 include, for example, plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), and fuel cell electric vehicles (FCEVs). Electrically powered vehicles 10 may also include a data communication module (DCM) and a communication interface compatible with 5G (fifth generation mobile communication systems).

[0021] EVSE 20 refers to a vehicle power supply facility. Electrically-powered vehicle 10 is configured to be electrically connectable to EVSE 20. For example, by connecting a charging cable 21 connected to EVSE 20 to an inlet of electric vehicle 10, it becomes possible to exchange power between EVSE 20 and electric vehicle 10.

[0022] The electric vehicle 10 can supply power to the power bank 200. The electric vehicle 10 can also receive power from the power bank 200. Specifically, the electric vehicle 10 is electrically connected to the EVSE 20, thereby enabling the above-described power supply and power reception. Note that the electric vehicle 10 may perform the above-described power supply and power reception from the same EVSE 20 or from different EVSEs 20.

[0023] The power management device 100 is a device that provides power services to users who own electric vehicles 10. The power management device 100 is configured to manage information on a plurality of registered electric vehicles 10 (hereinafter also referred to as "vehicle information"), information on each registered user (hereinafter also referred to as "user information"), and information on registered EVSEs 20 (hereinafter also referred to as "EVSE information"). The user information, vehicle information, and EVSE information are distinguished by identification information (ID) and stored in a memory 102, which will be described later.

[0024] The user ID is identification information for identifying a user, and also functions as information (terminal ID) for identifying a mobile terminal (not shown) carried by the user. The power management apparatus 100 is configured to store information received from the mobile terminal separately for each user ID. The user information includes the communication address of the mobile terminal carried by the user and the vehicle ID of the electric vehicle 10 belonging to the user.

[0025] The vehicle ID is identification information for identifying the electric vehicle 10. The vehicle ID may be a license plate or a VIN (Vehicle Identification Number). The vehicle information includes the travel schedule of each electric vehicle 10.

[0026] The EVSE-ID is identification information for identifying the EVSE 20. The EVSE information includes the communication address of each EVSE 20 and the status of the electric vehicle 10 connected to each EVSE 20. The EVSE information also includes information indicating the combination of the electric vehicle 10 and the EVSE 20 that are connected to each other (for example, a combination of the EVSE-ID and the vehicle ID).

[0027] The user of the electric vehicle 10 can store (deposit) the power provided to the power bank 200 as his / her own personal power. The user can receive (draw) the personal power from the power bank 200 free of charge.

[0028] The user of the electric vehicle 10 can also store the power provided to the power bank 200 in the power bank 200 as shared power that can be received by other users. By providing the shared power to the power bank 200, the user can receive incentives such as money or points.

[0029] The total amount of power in the power bank 200 is the sum of the amount of power stored exclusively by each user and the amount of shared power.

[0030] The power management apparatus 100 includes a processor 101, a memory 102, and a communication unit 103. The processor 101 and the communication unit 103 are examples of the "control unit" and the "acquisition unit" of the present disclosure, respectively.

[0031] The memory 102 stores programs executed by the processor 101 as well as information used in the programs (for example, maps, formulas, and various parameters). The communication unit 103 includes various communication I / Fs. The processor 101 controls the communication unit 103. Specifically, the processor 101 communicates with the power bank 200, the DCM of the electric vehicle 10 (or the user's mobile terminal), and the EVSE 20 via the communication unit 103.

[0032] The communication unit 103 acquires information related to the supply and demand of power in the power bank 200. Specifically, the communication unit 103 acquires information about the amount of power stored in the power bank 200 from the power bank 200 via communication. The communication unit 103 also acquires information about the amount of power stored in the power bank 200 by the user for personal use (user's power supply amount) from the power bank 200 or the like. The communication unit 103 also acquires temperature information from a temperature sensor, a weather forecast center, or the like (not shown) via communication.

[0033] The processor 101 determines the power supply and demand in the power bank 200 based on information on the amount of power stored in the power bank 200 and information on the temperature, which information is acquired by the communication unit 103 .

[0034] However, conventional systems do not take into account that charging and discharging of electricity is performed based on the supply and demand status of electricity in the power grid (power bank). This can make it difficult to equalize the supply and demand of electricity. It is therefore desirable to easily equalize the supply and demand of electricity.

[0035] Therefore, in this embodiment, the processor 101 sets a power exchange ratio of power received from the power bank 200 to power supplied to the power bank 200 in accordance with power supply and demand. Then, the processor 101 determines the amount of power received by the electric vehicle 10 from the power bank 200 based on the amount of power supplied from the electric vehicle 10 to the power bank 200 and the power exchange ratio. In other words, the processor 101 sets an upper limit value for the amount of power that the electric vehicle 10 can receive from the power bank 200 based on the amount of power supplied and the power exchange ratio.

[0036] <When there is no power shortage / at the right temperature> 2 shows an example in which 1500 kWh of power is stored in the entire power bank 200, so there is no power shortage, and the air temperature is moderate (for example, 20° C.). In this example, the processor 101 determines that the power supply and demand of the power bank 200 is not tight (there is a surplus of power).

[0037] In this case, processor 101 sets the power exchange rate to 1. Here, it is assumed that the user of electric vehicle 10 stores 300 kW of power in power bank 200 as his / her own dedicated power amount (user's power supply amount). In this case, the user of electric vehicle 10 can receive (draw) from power bank 200 an amount of power that is 1 times 300 kWh (300 kWh).

[0038] Furthermore, the processor 101 reduces the amount of power received by the electric vehicle 10 from the power bank 200 by setting a lower power exchange rate as the power shortage in the power bank 200 increases (as the power supply and demand becomes tighter).

[0039] <When there is a power shortage / at the right temperature> 3 shows an example in which only 1000 kWh of power is stored in the entire power bank 200, resulting in a power shortage, and the temperature is 20° C. In this example, the processor 101 determines that the power supply and demand of the power bank 200 is tighter (there is a power shortage) than in the example shown in FIG.

[0040] In this case, processor 101 reduces the power exchange rate to a value smaller than 1 (for example, 0.5). Here, as in Fig. 2, it is assumed that the user of electric vehicle 10 stores 300 kW of power in power bank 200 as his / her own dedicated power amount (user's power supply amount). In this case, the user of electric vehicle 10 can receive (draw) from power bank 200 an amount of power that is 0.5 times 300 kWh (150 kWh).

[0041] 2 and 3 show an example in which the power exchange rate is set to less than 1 when the power supply and demand of the power bank 200 is tight, but the present disclosure is not limited to this. For example, the power exchange rate may be set to more than 1 when there is a surplus in the power supply (when there is surplus stored power in the power bank 200).

[0042] <Threshold of power supply amount> In addition, when the amount of power supplied from the electric vehicle 10 to the power bank 200 is greater than a predetermined first threshold, the processor 101 reduces the degree of decrease in the power exchange ratio compared to when the amount of power supplied from the electric vehicle 10 to the power bank 200 is less than the first threshold.

[0043] 4, similar to the example shown in Fig. 3, shows an example in which 1000 kWh of power is stored in the entire power bank 200, resulting in a power shortage, and the temperature is 20° C. In the example shown in Fig. 4, the amount of power supplied from the electric vehicle 10 (500 kWh) is greater than the amount of power supplied in the example shown in Fig. 3 (300 kWh).

[0044] Here, the first threshold value is assumed to be, for example, 400 kWh. The amount of power supplied from the electric vehicle 10 is greater than the first threshold value. In this case, the processor 101 reduces the degree of reduction in the power exchange rate by setting the power exchange rate to 0.8, which is higher than the power exchange rate (0.5) in the example shown in FIG. 3. As a result, the user of the electric vehicle 10 can receive (draw) from the power bank 200 an amount of power (400 kWh) that is 0.8 times 500 kWh.

[0045] Furthermore, the processor 101 does not reduce the power exchange rate when the amount of power supplied from the electric vehicle 10 to the power bank 200 is greater than a second threshold value that is greater than the first threshold value.

[0046] 5, similar to the example shown in FIG. 3 (and FIG. 4), shows an example in which 1000 kWh of power is stored in the entire power bank 200, resulting in a power shortage, and the temperature is 20° C. In the example shown in FIG. 5, the amount of power supplied from the electric vehicle 10 (750 kWh) is greater than the amount of power supplied in the example shown in FIG. 4 (500 kWh).

[0047] Here, the second threshold is assumed to be, for example, 700 kWh. In this case, the processor 101 sets the power exchange rate to 1. In other words, the processor 101 does not execute control to reduce the power exchange rate. As a result, the user of the electric vehicle 10 can receive (draw) from the power bank 200 an amount of power that is 1 times 750 kWh (750 kWh).

[0048] <When the temperature drops> In the example shown in Fig. 6, as in the example shown in Fig. 3, 1000 kWh of power is stored in the entire power bank 200, resulting in a power shortage. On the other hand, the temperature in the example shown in Fig. 6 is low (0°C), which is lower than the temperature (20°C) in the example shown in Fig. 3. In this case, the processor 101 determines that the power supply and demand of the power bank 200 is tighter (there is a power shortage) than in the example shown in Fig. 3.

[0049] In the example shown in Fig. 6, the processor 101 sets the power exchange rate to a value (e.g., 0.3) lower than the power exchange rate (0.5) in the example shown in Fig. 3. As a result, the user of the electric vehicle 10 can receive (draw) from the power bank 200 an amount of power that is 0.3 times 300 kWh (90 kWh).

[0050] The stepwise change in the power exchange ratio described above is merely an example. For example, the power exchange ratio may be changed linearly (continuously) based on the temperature, the amount of power supplied by the user, the total amount of power in the power bank 200, etc. For example, the power exchange ratio may decrease in proportion to a decrease in temperature.

[0051] (Method of providing electricity services) Next, a method for providing a power service by power management apparatus 100 will be described with reference to the sequence diagram of FIG.

[0052] In step S1 , the power management apparatus 100 acquires information on the amount of power in the power bank 200 from the power bank 200 via the communication unit 103 .

[0053] In step S2, the power management apparatus 100 acquires temperature information from a temperature sensor (not shown), a weather forecast center, or the like via the communication unit 103. The temperature sensor may be provided in the power management apparatus 100. Note that the processing of step S2 may be performed before the processing of step S1, or may be performed simultaneously with the processing of step S1.

[0054] In step S3, the power management device 100 acquires information on the amount of power supplied by the electrically powered vehicle 10 to the power bank 200 (the amount of power dedicated to each user) from the power bank 200. Note that the information on the amount of power supplied may be updated each time the electrically powered vehicle 10 supplies or receives power, and may be managed in the memory 102.

[0055] In step S4, the processor 101 determines the power supply and demand in the power bank 200 based on the information in steps S1 and S2.

[0056] In step S5, the processor 101 sets a power exchange ratio, which is the ratio of power received from the power bank 200 to power supplied to the power bank 200, based on the power supply and demand determined in step S4. Specifically, if it is determined in step S4 that the power supply and demand is tight (the power stored in the power bank 200 is insufficient) (see FIG. 3, etc.), the power exchange ratio is set to a value lower than 1. On the other hand, if it is determined that there is a surplus in the power supply (the power stored in the power bank 200 has surplus power), the power exchange ratio is set to a value higher than 1.

[0057] In step S6, the processor 101 determines whether the power exchange rate set in step S5 is less than 1. If the power exchange rate is less than 1 (Yes in S6), the process proceeds to step S7. If the power exchange rate is 1 or more (No in S6), the process proceeds to step S11.

[0058] In step S7, the processor 101 determines whether the amount of power supplied from the electric vehicle 10 to the power bank 200 is greater than a first threshold (for example, 400 kWh). If the amount of power supplied is greater than the first threshold (Yes in S7), the process proceeds to step S8. If the amount of power supplied is equal to or less than the first threshold (No in S7), the process proceeds to step S11.

[0059] In step S8, the processor 101 determines whether the amount of power supplied from the electric vehicle 10 to the power bank 200 is greater than a second threshold (for example, 700 kWh). If the amount of power supplied is greater than the second threshold (Yes in S8), the process proceeds to step S10. If the amount of power supplied is equal to or less than the second threshold (No in S8), the process proceeds to step S9.

[0060] In step S9, the processor 101 reduces the degree of reduction in the power exchange rate, thereby setting the power exchange rate to a value higher than the value set in step S5 and lower than 1.

[0061] In step S9, the processor 101 may change the degree of mitigation of the degree of decrease based on the amount of power supplied by the electrically powered vehicle 10. Specifically, the processor 101 may increase the degree of mitigation as the amount of power supplied is larger. Note that the degree of mitigation may be constant regardless of the amount of power supplied.

[0062] In step S10, the processor 101 does not execute the control to reduce the power exchange rate. Specifically, the processor 101 sets the power exchange rate to 1, regardless of the value of the power exchange rate set (reduced) in step S5.

[0063] In step S11, the processor 101 controls the EVSE 20 and the electric vehicle 10 so that the upper limit of the amount of power received by the electric vehicle 10 from the power bank 200 is determined based on the set power exchange ratio.

[0064] In step S12, power is exchanged between the electrically powered vehicle 10 and the EVSE 20 in a state where an upper limit value for the amount of power received by the electrically powered vehicle 10 is set based on the set power exchange ratio.

[0065] As described above, in this embodiment, the processor 101 sets the power exchange ratio of the power received from the power bank 200 to the power supplied to the power bank 200, in accordance with the power supply and demand of the power bank 200. Then, the processor 101 determines the amount of power received by the electric vehicle 10 from the power bank 200 based on the amount of power supplied from the electric vehicle 10 to the power bank 200 and the power exchange ratio. In this way, the power exchange ratio is set and the amount of received power is adjusted in accordance with the power supply and demand of the power bank 200. As a result, for example, when the power supply and demand is tight, the amount of received power is prevented from becoming relatively large. This makes it possible to easily equalize the power supply and demand.

[0066] Furthermore, the user of the electric vehicle 10 that provided a relatively large amount of power to the power bank 200 can receive an incentive to receive a relatively large amount of power, since the power exchange rate is set relatively high.

[0067] In the above embodiment, an example has been described in which the electrically powered vehicle 10 receives power from the power bank 200, but the present disclosure is not limited to this. The electrically powered vehicle 10 may also receive power from the power grid PG. This will be described in detail with reference to FIG. 8.

[0068] 8 is a diagram showing the configuration of a power management system 2 according to a modification of the above embodiment. The power management system 2 includes a power management device 300, a power system PG, a system management server 400, an electrically powered vehicle 10, and an EVSE 20. The power system PG is an example of the "power storage device" of the present disclosure.

[0069] The power system management server 400 manages the power supply and demand in the power system PG (power grid). The power system management server 400 transmits a request (supply and demand adjustment request) to the power management device 300 to adjust the power supply and demand of the power system PG based on the power generated and consumed by each power adjustment resource managed by the power system management server 400.

[0070] As one means for increasing or decreasing the amount of power supply and demand in the power system PG, the power management device 300 requests the electrically powered vehicle 10 to supply power to the power system PG (external power supply) or to be charged from the power system PG (external charging).

[0071] Unlike the above embodiment, the power management apparatus 300 acquires information about the power state of the power system PG based on information (supply and demand adjustment request) from the power system management server 400. The power management apparatus 300 then determines the power supply and demand of the power system PG based on the power state and temperature of the power system PG. Other control is the same as in the above embodiment, so a repeated description will not be given.

[0072] In the above embodiment, an example is shown in which a first threshold and a second threshold are set for the amount of power supplied to the user, but the present disclosure is not limited to this. Only one of the first threshold and the second threshold may be set. In other words, only one of control to mitigate the degree of decrease in the power exchange rate and control to not execute control to decrease the power exchange rate may be executed.

[0073] In the above embodiment, an example has been described in which the power supply and demand of the power bank 200 is determined based on the power amount and temperature of the power bank 200, but the present disclosure is not limited to this. The power supply and demand may also be determined based on the power amount and season of the power bank 200. For example, it may be determined that the power supply and demand in winter is tighter than the power supply and demand in other seasons (e.g., summer). Furthermore, the power supply and demand may also be determined based on any one of the power amount of the power bank 200, the temperature, and the season, or all of the power amount, the temperature, and the season.

[0074] The power exchange rate may also be set based on the SOC (State Of Charge) of the electrically powered vehicle 10. For example, when the SOC of the electrically powered vehicle 10 is relatively low, the power exchange rate may be reduced.

[0075] In the above embodiment, an example has been described in which the power exchange rate is adjusted based on the amount of power supplied to the power bank 200, but the present disclosure is not limited to this. For example, the power exchange rate may be adjusted based on the frequency with which the electric vehicle 10 supplies power to the power bank 200. Specifically, when the frequency with which power is supplied to the power bank 200 is relatively high, the degree of reduction in the power exchange rate may be reduced.

[0076] In the above embodiment, an example has been described in which the electrically powered vehicle 10 supplies power to the power bank 200 and receives power from the power bank 200, but the present disclosure is not limited to this. An electric device other than the electrically powered vehicle 10 (for example, a home generator) may supply power to the power bank 200 and receive power from the power bank 200. Furthermore, the electric device that supplies power to the power bank 200 and the electric device that receives power from the power bank 200 may be different from each other.

[0077] 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]

[0078] 1, 2 Power management system, 10 Electric vehicle (power source) (load), 100, 300 Power management device, 101 Processor (control unit), 103 Communication unit (acquisition unit), 200 Power bank (power storage device), PG Power system (power storage device).

Claims

1. A power management device that provides power service to a user having a power source capable of supplying power to a power storage device and a load capable of receiving power from the power storage device, an acquisition unit that acquires information regarding power supply and demand in the power storage device; a control unit that controls the power received by the load from the power storage device, The control unit setting a power exchange ratio of power received from the power storage device to power supplied to the power storage device according to the power supply and demand; determining an amount of power received by the load from the power storage device based on the amount of power supplied from the power source to the power storage device and the power exchange ratio; The more the power in the power storage device is deficient, the lower the power exchange rate is set, thereby reducing the amount of power received by the load from the power storage device; A power management device that, when the amount of power supplied from the power source to the storage device is greater than a predetermined first threshold, reduces the degree of decrease in the power exchange ratio compared to when the amount of power supplied from the power source to the storage device is less than the first threshold.

2. 2 . The power management device according to claim 1 , wherein the control unit does not reduce the power exchange rate when the amount of power supplied from the power source to the power storage device is greater than a second threshold value that is greater than the first threshold value.

3. the acquisition unit acquires at least one of information on the amount of power stored in the power storage device, a temperature, and a season; The power management device according to claim 1 , wherein the control unit determines the power supply and demand based on the at least one piece of information.

4. a power storage device; a power management device that provides power services to a user having a power source that can supply power to the power storage device and a load that can receive power from the power storage device; The power management device an acquisition unit that acquires information regarding power supply and demand in the power storage device; a control unit that controls the power received by the load from the power storage device, The control unit setting a power exchange ratio of power received from the power storage device to power supplied to the power storage device according to the power supply and demand; determining an amount of power received by the load from the power storage device based on the amount of power supplied from the power source to the power storage device and the power exchange ratio; The more the power in the power storage device is deficient, the lower the power exchange rate is set, thereby reducing the amount of power received by the load from the power storage device; A power management system that, when the amount of power supplied from the power source to the power storage device is greater than a predetermined first threshold, reduces the degree of decrease in the power exchange ratio compared to when the amount of power supplied from the power source to the power storage device is less than the first threshold.

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