Power storage device

Abstract

To provide a power storage device capable of suppressing a peak of reverse flow power to a power system.SOLUTION: A power storage device 15 includes a power storage section 15a and a charge / discharge control section 15b controlling the charge / discharge of the power storage section 15a. When it is predicted that surplus power, which can be derived by subtracting load power of a power load 14 provided in a facility 10 from power generated by a solar cell device 13, does not increase in a future predetermined charging permitted time zone, the charge / discharge control section 15b performs large power charging control of charging the generated surplus power into the power storage section 15a with the maximum charge power that can be charged in the power storage section 15a, during the whole period of the charging permitted time zone, and when it is predicted that the surplus power increases in the charging permitted time zone, the charge / discharge control section performs small power charging control of charging the generated surplus power with predetermined charge power smaller than the maximum charge power, at least early in the charging permitted time zone.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electricity storage device that is installed together with a solar cell device in a facility that can receive a supply of electric power from a power grid. [Background technology]

[0002] There are systems in which solar cell devices and power storage devices are installed in facilities such as residences and offices. When many facilities equipped with such systems are connected to a power grid, the time periods when the power generated by the solar cell devices at each facility is high, i.e., the time periods when surplus power is generated at the facilities, are almost simultaneous, so the total amount of reverse flow power supplied from the many facilities to the power grid can become very large.

[0003] Various attempts have been made to reduce power consumption during peak hours of power consumption by power loads connected to the power grid (so-called peak cutting), but in order to stabilize the power grid, as mentioned above, it is also necessary to reduce extreme increases in power flowing back from facilities to the power grid.

[0004] Patent Document 1 (Patent Publication No. 7284559) describes suppressing extreme increases in the amount of electricity received from the power grid (peak cutting) in facilities equipped with solar cell devices and power storage devices, but does not describe suppressing extreme increases in the amount of electricity flowing back into the power grid.

[0005] Patent Document 2 (Japanese Patent No. 7073639) describes suppressing surplus power supplied to the power grid by reducing the power generated by power generation facilities and increasing the power demand of demand facilities (such as storage batteries). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 7284559 [Patent Document 2] Patent No. 7073639 Summary of the Invention [Problem to be solved by the invention]

[0007] Patent Document 2 describes how surplus power supplied to the power grid can be reduced by charging a storage battery. However, the storage capacity of a typical power storage device is often smaller than the amount of surplus power generated in a facility in one day on sunny days, when the power generated by a solar cell device is high. Therefore, once the power storage device is fully charged, it cannot store any more power, and the surplus power flows back to the power grid.

[0008] Fig. 6 is a graph showing an example in which surplus power generated is charged at the maximum charging power that the power storage device can charge. In the figure, the dashed lines show the time trends of surplus power and power shortage, and the solid line shows the time trends of reverse flow power to the power grid. Note that the surplus power is a value that can be derived by subtracting the load power of the power load from the power generated by the solar cell device, and the power shortage is a value that can be derived by subtracting the power generated by the solar cell device from the load power of the power load.

[0009] As shown in the figure, at time t20, surplus power is generated and charging to the power storage device begins. Between time t20 and time t21, the generated surplus power is smaller than the maximum charging power of the power storage device, so all of the generated surplus power is charged to the power storage device. As a result, between time t20 and time t21, the reverse flow power is zero. Thereafter, after time t21, the generated surplus power becomes greater than the maximum charging power of the power storage device, so part of the surplus power is charged in the power storage device at the maximum charging power, and the remainder is reverse flowed to the power grid. At time t22, the power storage device is fully charged, and thereafter charging by the power storage device is no longer possible. As a result, between time t22 and time t23, all of the generated surplus power is reverse flowed to the power grid.

[0010] When charging is performed as shown in FIG. 6, charging to the energy storage device cannot be performed at the predicted maximum surplus time tm, when the surplus power is greatest. This predicted maximum surplus time tm can be considered to be the time when the power generated by the solar cell device is greatest. Therefore, it is considered that the reverse flow power is greatest at roughly the same time period in many facilities connected to the power grid. In other words, the power supplied to the power grid by multiple facilities becomes very large at the same time period, which may cause instability in the power supply and demand balance in the power grid.

[0011] The present invention has been made in view of the above-mentioned problems, and has an object to provide a power storage device that can suppress peaks of reverse flow power to a power grid. [Means for solving the problem]

[0012] A characteristic configuration of the power storage device according to the present invention for achieving the above object is a power storage device provided together with a solar cell device in a facility that can receive power supply from a power grid, the power storage device comprising: a power storage unit and a charge / discharge control unit that controls charging and discharging of the power storage unit; The charge / discharge control unit when it is predicted that the surplus power that can be derived by subtracting the load power of the power load provided in the facility from the power generated by the solar cell device will not be large during a predetermined future charging permission time slot, a large charging control is performed to charge the generated surplus power to the power storage unit at a maximum charging power that can be charged to the power storage unit during the entire period of the charging permission time slot, When it is predicted that the surplus power will be large during the charging permission time period, small charging control is performed to charge the generated surplus power with a predetermined small charging power that is smaller than the maximum charging power, at least at the beginning of the charging permission time period.

[0013] According to the above characteristic configuration, when it is predicted that the surplus power will not increase during the charging permission time slot, the charge / discharge control unit performs large charge control to charge the surplus power generated during the charging permission time slot to the power storage unit at the maximum charging power. In this way, even if all of the surplus power is charged to the power storage unit when the surplus power does not increase, it is expected that the time required for the power storage unit to reach a fully charged state will be longer. Furthermore, when the surplus power is predicted to be large during the charging permission time slot, the charge / discharge control unit performs small charge control to charge the surplus power generated during the charging permission time slot to the power storage unit with a predetermined small charging power that is smaller than the maximum charging power, at least at the beginning of the charging permission time slot. In this way, because at least a portion of the surplus power generated during at least the beginning of the charging permission time slot is charged to the power storage unit with the small charging power, it is expected that the time required for the power storage unit to reach a fully charged state will be longer during that time. In other words, the effect of continuously suppressing peaks in reverse flow power to the power grid can be maintained for a longer period of time. Therefore, it is possible to provide a power storage device that can suppress peaks of reverse power flow to the power grid.

[0014] Another characteristic configuration of the energy storage device according to the present invention is that, when the maximum value of the predicted amount of solar radiation for each of the plurality of unit periods constituting the permitted charging time period is smaller than the reference amount of solar radiation, the charge / discharge control unit predicts that the surplus power will not increase during the permitted charging time period and performs the large charge control, and when the maximum value of the predicted amount of solar radiation for each of the plurality of unit periods during the permitted charging time period is equal to or greater than the reference amount of solar radiation, the charge / discharge control unit predicts that the surplus power will increase during the permitted charging time period and performs the small charge control.

[0015] If the weather is sunny, the amount of solar radiation increases, resulting in an overall increase in the power generated by the solar cell device on that day. On the other hand, if the weather is rainy, for example, the amount of solar radiation decreases, resulting in an overall decrease in the power generated by the solar cell device. Therefore, if the weather is sunny, the amount of solar radiation for each of the multiple unit periods that make up the charging permission time slot also increases overall, which is expected to increase the overall power generated by the solar cell device for each unit period and increase the overall surplus power. Similarly, if the weather is rainy, for example, the amount of solar radiation for each of the multiple unit periods that make up the charging permission time slot also decreases overall, which is expected to decrease the overall power generated by the solar cell device for each unit period and decrease the overall surplus power. Furthermore, because the maximum predicted amount of solar radiation for each of the multiple unit periods that make up the charging permission time slot is known in advance, if the maximum predicted amount of solar radiation for each future unit period, such as the next day, is greater than the reference amount of solar radiation, it can be predicted that the surplus power will be large during the charging permission time slot on that day. On the other hand, if the maximum predicted amount of solar radiation for each unit period is smaller than the reference amount of solar radiation, it can be predicted that the surplus power will be small during the charging permission time slot on that day.

[0016] Therefore, in this characteristic configuration, if the maximum value of the predicted amount of solar radiation for each of the multiple unit periods that make up the charging permission time period is smaller than the reference amount of solar radiation, the charge / discharge control unit predicts that the surplus power will not increase during the charging permission time period and performs large charge control; and if the maximum value of the predicted amount of solar radiation for each of the multiple unit periods during the charging permission time period is equal to or greater than the reference amount of solar radiation, the charge / discharge control unit predicts that the surplus power will increase during the charging permission time period and performs small charge control.

[0017] Another characteristic configuration of the power storage device according to the present invention is that the charging permission time period includes a first time period including a predicted maximum surplus time when the surplus power is predicted to be maximum within the charging permission time period, and a second time period that is temporally earlier than the first time period, When performing the small charge control, the charge / discharge control unit charges the surplus power actually generated during the charge permission time slot with a maximum charge power that does not exceed a predetermined target charge power, The target charging power in the first time period is the maximum charging power or a first charging power smaller than the maximum charging power, and the target charging power in the second time period is a second charging power as the small charging power smaller than the first charging power.

[0018] According to the above characteristic configuration, when the charge / discharge control unit performs small charge control in response to a prediction that surplus power will be large during a charging permission time slot, the charge / discharge control unit charges the power storage unit with a first charging power that is the maximum charging power or smaller as the target charging power during a first time slot that is later in time, and charges the power storage unit with a second charging power that is a small charging power smaller than the first charging power as the target charging power during a second time slot that is earlier in time. In this way, because at least a portion of the surplus power generated during the second time slot that is early in the charging permission time slot is charged to the power storage unit with the second charging power (small charging power), it is expected that the time required for the power storage unit to reach a fully charged state will be longer during that time slot. Then, during the subsequent first time slot, the charge / discharge control unit charges the power storage unit with the first charging power that is larger than the second charging power, thereby making it possible to suppress reverse flow power to the power grid more effectively than during the second time slot.

[0019] Another characteristic configuration of the energy storage device according to the present invention is that, when the charge / discharge control unit performs the small charge control, the surplus power actually generated during the permitted charging time period is charged with a maximum charge power that does not exceed the small charge power that is smaller than the maximum charge power.

[0020] According to the above characteristic configuration, when the charge / discharge control unit performs small charge control in response to a prediction that the surplus power will be large during the charging permission time slot, the charge / discharge control unit charges the surplus power actually generated during the charging permission time slot with the maximum charging power that does not exceed the small charging power that is smaller than the maximum charging power. In other words, it is expected that the time required for the power storage unit to reach a full charge state will be longer than when the surplus power is charged with the maximum charging power, while suppressing an increase in reverse flow power to the power grid. [Brief explanation of the drawings]

[0021] [Figure 1]FIG. 1 is a diagram showing a configuration of a facility in which a power storage device is installed. [Figure 2] 10 is an example of a time transition of a power shortage and a power surplus. [Figure 3] 10 is an example of time transition of power shortage, power surplus, and reverse flow power. [Figure 4] 10 is an example of time transition of power shortage, power surplus, and reverse flow power. [Figure 5] 10 is an example of time transition of power shortage, power surplus, and reverse flow power. [Figure 6] 10 is an example of time transition of power shortage, power surplus, and reverse flow power. DETAILED DESCRIPTION OF THE INVENTION

[0022] First Embodiment A power storage device 15 according to a first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the configuration of a facility 10 in which a power storage device 15 of this embodiment is installed. As shown in the figure, a power line 12 installed in facility 10, such as a residence or a business, is connected to a power grid 1. In facility 10, a solar cell device 13, a power storage device 15, and a power load 14 are connected to power line 12. In this manner, power storage device 15 is installed together with solar cell device 13 in facility 10 that can receive a supply of power from power grid 1. Devices such as power storage device 15 installed in facility 10 can be connected to an information communication line 2 outside facility 10 via router 11.

[0023] The power storage device 15 includes a power storage unit 15a and a charge / discharge control unit 15b that controls charging and discharging of the power storage unit 15a. In this embodiment, the power storage device 15 also includes a storage unit 15c that stores information. The power storage unit 15a can be realized using a device that can charge and discharge power, such as a secondary battery.

[0024] The solar cell device 13 can be realized using an element that converts light energy into electrical energy. Although not shown, the solar cell device 13 also includes a power conversion circuit that converts the power output from the element into a desired power.

[0025] The power load 14 is various devices that consume power, such as lighting equipment and air conditioning equipment, that are installed in the facility 10.

[0026] The measurement results of the power measurement unit 16 provided on the power line 12 are transmitted to the power storage device 15. The power measured by the power measurement unit 16 is the power supplied from the power system 1 to the power line 12 of the facility 10. In this embodiment, the solar cell device 13, the power storage device 15, and the power load 14 are connected to the power line 12, and therefore the power measured by the power measurement unit 16 is the value obtained by subtracting the power generated by the solar cell device 13 and the discharge power of the power storage device 15 from the load power of the power load 14. Alternatively, the power measured by the power measurement unit 16 is the value obtained by subtracting the power generated by the solar cell device 13 from the load power of the power load 14 and the charging power of the power storage device 15.

[0027] The charge / discharge control unit 15b of the power storage device 15 knows the discharge power that the power storage unit 15a discharges to the power line 12 or the charge power that the power storage unit 15a charges from the power line 12, and therefore can refer to the measurement results of the power measurement unit 16 to determine the surplus power that can be derived by subtracting the load power of the power load 14 from the power generated by the solar cell device 13, or the shortage power (i.e., negative surplus power) that can be derived by subtracting the power generated by the solar cell device 13 from the load power of the power load 14. Then, the charge / discharge control unit 15b stores information indicating the time transition of the shortage power and surplus power generated in the facility 10 in the memory unit 15c.

[0028] The measurement results of power measurement unit 17 provided on power line 12 are transmitted to power storage device 15. The power measured by power measurement unit 17 is a value obtained by subtracting the discharge power of power storage device 15 from the load power of power load 14. Alternatively, the power measured by power measurement unit 17 is a value obtained by adding the load power of power load 14 and the charge power of power storage device 15. Because charge / discharge control unit 15b knows the discharge power discharged by power storage unit 15a to power line 12 or the charge power charged from power line 12, it can determine the load power of power load 14 by referring to the measurement results of power measurement unit 17. Then, charge / discharge control unit 15b stores information indicating the time transition of the load power of power load 14 in memory unit 15c.

[0029] The power storage device 15 can acquire information on the time transition of the predicted amount of solar radiation via the information communication line 2 from the information providing server 3, which provides information on the time transition of the predicted amount of solar radiation. For example, if a predetermined charging permission time period is set, such as from 6:00 to 18:00, the power storage device 15 can acquire information on the predicted amount of solar radiation for each of multiple unit periods (e.g., every 30 minutes, every hour, etc.) that make up the charging permission time period. In addition, the storage unit 15c stores a program that derives a predicted value of the power generated by the solar cell device 13 for each unit period based on the predicted amount of solar radiation for the unit period. Therefore, the charge / discharge control unit 15b can derive a predicted value of the power generated by the solar cell device 13 for each of multiple unit periods that make up the charging permission time period based on the predicted amount of solar radiation for each of the multiple unit periods that make up the charging permission time period.

[0030] For example, if the weather is sunny, the amount of solar radiation increases, resulting in an overall increase in the power generated by the solar cell device 13 on that day; if the weather is rainy, for example, the amount of solar radiation decreases, resulting in an overall decrease in the power generated by the solar cell device 13 on that day. In particular, when focusing on the maximum value of the predicted amount of solar radiation for each of the multiple unit periods that make up the charging permission time slot, the maximum value of the predicted amount of solar radiation for each of the multiple unit periods increases on sunny days, and decreases on rainy days, for example. Therefore, when the weather is sunny and the amount of solar radiation for each unit period is large, that is, when the power generated by the solar cell device 13 increases, it can be said that the surplus power that can be derived by subtracting the load power of the power load 14 from the power generated by the solar cell device 13 increases (or the deficit power that can be derived by subtracting the power generated by the solar cell device 13 from the load power of the power load 14 decreases). On the other hand, when the weather is rainy and the amount of solar radiation per unit period is small, i.e., when the power generated by the solar cell device 13 is small, the surplus power that can be derived by subtracting the load power of the power load 14 from the power generated by the solar cell device 13 will be small (or the deficit power that can be derived by subtracting the power generated by the solar cell device 13 from the load power of the power load 14 will be large).

[0031] Fig. 2 shows an example of time trends in the predicted values ​​of power shortage and power surplus that will occur in facility 10. In Fig. 2, the dashed lines show an example of time trends in the predicted values ​​of power shortage and power surplus on days when the predicted value of power generation by solar cell device 13 is large, and the dashed-dotted lines show an example of time trends in the predicted values ​​of power shortage and power surplus on days when the predicted value of power generation by solar cell device 13 is small. As shown in the figure, on days when the power generation by solar cell device 13 is large, the surplus power is large and the power shortage is small, and on days when the power generation by solar cell device 13 is small, the surplus power is small and the power shortage is large.

[0032] The charge / discharge control unit 15b can set the unit period in which the predicted value of power generation by the solar cell device 13 is maximum among the derived multiple unit periods as the predicted maximum surplus period in which surplus power is predicted to be maximum within the charging permission time slot. Furthermore, the charge / discharge control unit 15b can set a predetermined time (e.g., a midpoint time) within the predicted maximum surplus period as the predicted maximum surplus time in which surplus power is predicted to be maximum within the charging permission time slot. For example, if the unit period in which the predicted value of power generation by the solar cell device 13 is maximum is the period from 1:00 PM to 2:00 PM, the charge / discharge control unit 15b can set this period as the predicted maximum surplus period. Furthermore, the charge / discharge control unit 15b can set 1:30 PM, which is the midpoint of the predicted maximum surplus period from 1:00 PM to 2:00 PM, as the predicted maximum surplus time. In FIG. 2, the predicted maximum surplus time tm is shown for days when the predicted value of power generation by the solar cell device 13 is large (dashed line) and days when the predicted value of power generation by the solar cell device 13 is small (chain dotted line).

[0033] The power storage device 15 can be charged with power from the power line 12. Therefore, in the power storage device 15, a predetermined time period during which the solar cell device 13 can generate power is stored in the memory unit 15c as a charging permission time period during which the power storage unit 15a can be charged with power from the power line 12. In Fig. 2, the period from 6:00 to 18:00 is shown as the charging permission time period.

[0034] If the charge / discharge control unit 15b predicts that the surplus power that can be derived by subtracting the load power of the power load 14 installed in the facility 10 from the power generated by the solar cell device 13 will not be large during a specified future charging permission time period, it performs large charging control to charge the generated surplus power to the power storage unit 15a at the maximum charging power that the power storage unit 15a can charge for the entire period of the charging permission time period, and if the surplus power is predicted to be large during the charging permission time period, it performs small charging control to charge the generated surplus power at a specified small charging power that is smaller than the maximum charging power, at least at the beginning of the charging permission time period.

[0035] As described above, the charge / discharge control unit 15b can derive a predicted value of the power generated by the solar cell device 13 for each of the plurality of unit periods constituting the charging permission time zone based on the predicted amount of solar radiation for each of the plurality of unit periods constituting the charging permission time zone. Here, if the maximum value of the predicted amount of solar radiation for each of the plurality of unit periods constituting the charging permission time zone is large, it can be said that the maximum value of the predicted value of the power generated by the solar cell device 13 for each of the plurality of unit periods also becomes large. In addition, it can be said that an increase in the power generated by the solar cell device 13 also means an increase in surplus power. Therefore, in this embodiment, if the maximum value of the predicted amount of solar radiation for each of the plurality of unit periods constituting the charging permission time zone is smaller than the reference amount of solar radiation, the charge / discharge control unit 15b predicts that the surplus power will not increase during the charging permission time zone and performs large-volume charging control during that charging permission time zone. On the other hand, if the maximum value of the predicted amount of solar radiation for each of the plurality of unit periods during the charging permission time zone is equal to or greater than the reference amount of solar radiation, it predicts that the surplus power will increase during the charging permission time zone and performs small-volume charging control during that charging permission time zone.

[0036] [Large charge control] FIG. 3 shows an example of the time transition of the power shortage, surplus power, and reverse flow power from the facility 10 to the power grid 1 on a day when the power generation of the solar cell device 13 is low. In FIG. 3, the time transition of the power shortage and surplus power is indicated by a dashed line, and the time transition of the reverse flow power is indicated by a solid line. In this case, the charge / discharge control unit 15b predicts that the surplus power will not increase during the charging permission time slot based on the fact that the maximum predicted amount of solar radiation for each of the multiple unit periods constituting the charging permission time slot is smaller than the reference amount of solar radiation, and performs large-scale charge control during the charging permission time slot. In the example shown in FIG. 3, the charge / discharge control unit 15b performs large-scale charge control to charge the surplus power at the maximum charging power between time t1 and time t2. As a result, all of the surplus power is charged to the power storage unit 15a, and the reverse flow power from the facility 10 to the power grid 1 becomes zero.

[0037] [Small charge control] FIG. 4 illustrates an example of time trends of power shortage, power surplus, and reverse flow power from the facility 10 to the power grid 1 on a day when the power generation of the solar cell device 13 is high. In FIG. 4, the time trends of power shortage and power surplus are indicated by dashed lines, and the time trends of reverse flow power are indicated by solid lines. In this case, the charge / discharge control unit 15b predicts that surplus power will be large during the charging permission time slot based on the fact that the maximum value of the predicted solar radiation amount for each of multiple unit periods during the charging permission time slot is equal to or greater than the reference solar radiation amount, and performs small-scale charging control during the charging permission time slot. In this embodiment, the charging permission time slot includes a first time slot including a predicted maximum surplus time when the surplus power is predicted to be largest during the charging permission time slot, and a second time slot that precedes the first time slot. In the example illustrated in FIG. 4, the charge / discharge control unit 15b sets the first time slot including the predicted maximum surplus time tm and the second time slot not including the predicted maximum surplus time tm. For example, the charge / discharge control unit 15b sets the period from time t4, which is a set time (for example, 1 hour and 30 minutes) before the predicted maximum surplus time tm, to the last time (6:00 p.m.) of the charging permission period as the first period, and sets the period from the first time (6:00 a.m.) of the charging permission period temporally before the first period to time t4 as the second period.

[0038] When performing small charge control, the charge / discharge control unit 15b charges the surplus power actually generated during the charging permission time slot with the maximum charge power that does not exceed a predetermined target charge power. The target charge power during the first time slot is the maximum charge power or a first charge power that is smaller than the maximum charge power, and the target charge power during the second time slot is a second charge power that is a small charge power that is smaller than the first charge power.

[0039] 4, during the second time slot between time t3 and time t4, charge / discharge control unit 15b charges power storage unit 15a with surplus power at second charging power that is smaller than the maximum charging power, so there is a time slot during which only a portion of the surplus power is charged to power storage unit 15a, and the uncharged surplus power flows backward to power grid 1. Therefore, the total amount of charging power during the second time slot does not increase, and power storage unit 15a is not fully charged even at time t4, which is the end of the second time slot.

[0040] Thereafter, in the first time slot between time t4 and time t6, charge / discharge control unit 15b charges power storage unit 15a with the surplus power at the maximum charging power, and therefore the amount of power flowing backward to power grid 1 after time t4 is significantly reduced. In particular, even at the predicted maximum surplus time tm, when the surplus power is predicted to be at its maximum, the amount of backward flow power is small. Note that at time t5, power storage unit 15a is fully charged, and therefore charging to power storage unit 15a is no longer possible, and thereafter the amount of backward flow power from facility 10 to power grid 1 increases.

[0041] As described above, when it is predicted that the amount of surplus power will not increase during the charging permission time slot, the charge / discharge control unit 15b performs large-charge control to charge the power storage unit 15a with the maximum charging power generated during the charging permission time slot. In this manner, even if all of the surplus power is charged to the power storage unit 15a when the amount of surplus power is not large, it is expected that the period required for the power storage unit 15a to reach a fully charged state will be extended. In other words, the effect of continuously suppressing the peak of reverse flow power to the power grid 1 can be maintained for a long period of time. Furthermore, when it is predicted that the amount of surplus power will increase during the charging permission time slot, the charge / discharge control unit 15b performs small-charge control to charge the power storage unit 15a with a predetermined small charging power that is smaller than the maximum charging power, at least at the beginning of the charging permission time slot. In this manner, because at least a portion of the surplus power generated during at least the beginning of the charging permission time slot is charged to the power storage unit 15a with the small charging power, it is expected that the period required for the power storage unit 15a to reach a fully charged state will be extended. That is, the effect of continuously suppressing the peak of the reverse flow power to the power grid 1 can be maintained for a long period of time. Therefore, it is possible to provide the power storage device 15 that can suppress the peak of the reverse flow power to the power grid 1. In this way, the power storage device 15 of this embodiment can reduce the reverse flow power at the predicted maximum surplus time tm, when the surplus power is predicted to be at its maximum. That is, it can contribute to the stabilization of the power grid 1.

[0042] Second Embodiment The power storage device 15 of the second embodiment differs from the above-described embodiment in the content of the small charge control when charging surplus power. The power storage device 15 of the second embodiment will be described below, but a description of the same configuration as in the above-described embodiment will be omitted.

[0043] Fig. 5 shows an example of the time trends of the power shortage, power surplus, and reverse flow power from the facility 10 to the power grid 1 on a day when the power generation of the solar cell device 13 is large. In Fig. 5, the time trends of the power shortage and power surplus are indicated by dashed lines, and the time trends of the reverse flow power are indicated by solid lines.

[0044] As in the above embodiment, when it is predicted that the surplus power will be large during the charging permission time slot, the charge / discharge control unit 15b performs small charge control to charge the power storage unit 15a with a predetermined small charge power that is smaller than the maximum charge power at least during the initial period of the charging permission time slot. In this embodiment, the small charge control is performed throughout the entire period including the initial period of the charging permission time slot. When performing small charge control, the charge / discharge control unit 15b charges the surplus power that actually occurs during the charging permission time slot with the maximum charge power that does not exceed the small charge power that is smaller than the maximum charge power.

[0045] 5, charge / discharge control unit 15b charges power storage unit 15a with small charging power that is smaller than the maximum charging power, so that in the time period between time t7 and time t8, only a portion of the surplus power is charged to power storage unit 15a, and the surplus power that is not charged flows backward to power grid 1. Therefore, the rate at which the amount of stored power in power storage unit 15a increases is slow, and it takes a long time for power storage unit 15a to reach a fully charged state.

[0046] Furthermore, since charging of the power storage unit 15a is performed even at the predicted maximum surplus time tm, when the surplus power is predicted to be the largest within the charging permission time period, the reverse flow power at the predicted maximum surplus time tm also becomes small. Note that, since the power storage unit 15a reaches the fully charged state at time t8, charging to the power storage unit 15a becomes impossible, and thereafter the reverse flow power from the facility 10 to the power grid 1 increases until time t9.

[0047] As described above, when the charge / discharge control unit 15b performs small charge control in response to a prediction that the surplus power will be large during the charging permission time slot, the surplus power actually generated during the charging permission time slot is charged with the maximum charging power that does not exceed the small charging power that is smaller than the maximum charging power. In other words, it is expected that the period required for the power storage unit 15a to reach a fully charged state will be longer than when the surplus power is charged with the maximum charging power, while suppressing an increase in the reverse flow power to the power grid 1.

[0048] <Another embodiment> In the above embodiment, the configuration of the power storage device 15 and the configuration of the system in which the solar cell device 13 and the power storage device 15 are provided in the facility 10 have been specifically described, but these configurations can be changed as appropriate.

[0049] In the above embodiment, an example has been described in which information handled by the power storage device 15, such as information indicating the time transition of power shortages and surpluses generated in the facility 10, information indicating the time transition of the load power of the power load 14, information about a program that derives a predicted value of the power generated by the solar cell device 13 in a unit period based on the predicted amount of solar radiation in the unit period, and information about a charging permission time period during which the power storage unit 15a can charge power from the power line 12, is stored in the memory unit 15c of the power storage device 15. However, such information may be stored in a single memory device separate from the power storage device 15 or may be stored separately in multiple devices. For example, such information may be stored in a memory unit of a server (not shown) connected to the information communication line 2, and the power storage device 15 may access the server to acquire the information.

[0050] In the above embodiment, the power storage device 15 of the present invention has been described using numerical examples, but these numerical values ​​are given for illustrative purposes only and can be changed as appropriate.

[0051] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradictions arise. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these, and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0052] INDUSTRIAL APPLICABILITY The present invention can be used in a power storage device that can suppress peaks of reverse power flow to a power grid. [Explanation of symbols]

[0053] 1: Power system 2: Information and communication lines 3: Information server 10: Facilities 11: Router 12: Power lines 13: Solar cell device 14: Power load 15: Power storage device 15a: Power storage unit 15b: Charge / discharge control unit 15c: Storage section 16: Power measurement section 17: Power measurement section

Claims

1. A power storage device provided together with a solar cell device in a facility that can receive power from a power grid, a power storage unit and a charge / discharge control unit that controls charging and discharging of the power storage unit; The charge / discharge control unit when it is predicted that the surplus power that can be derived by subtracting the load power of the power load provided in the facility from the power generated by the solar cell device will not be large during a predetermined future charging permission time slot, a large charging control is performed to charge the generated surplus power to the power storage unit at a maximum charging power that can be charged to the power storage unit during the entire period of the charging permission time slot, When the surplus power is predicted to be large during the charging permission time period, the power storage device performs small charging control to charge the generated surplus power with a predetermined small charging power that is smaller than the maximum charging power, at least at the beginning of the charging permission time period.

2. The charge / discharge control unit When a maximum value of the predicted amount of solar radiation for each of a plurality of unit periods constituting the charging permission time period is smaller than a reference amount of solar radiation, the surplus power is predicted not to be large during the charging permission time period, and the large-scale charging control is performed; 2. The power storage device according to claim 1, wherein when the maximum value of the predicted amount of solar radiation for each of the plurality of unit periods during the charging permission time period is equal to or greater than the reference amount of solar radiation, the power storage device predicts that the surplus power will be large during the charging permission time period and performs the small charging control.

3. the charging permission time period includes a first time period including a predicted maximum surplus time at which the surplus power is predicted to be maximum within the charging permission time period, and a second time period that is temporally earlier than the first time period; When performing the small charge control, the charge / discharge control unit charges the surplus power actually generated during the charge permission time slot with a maximum charge power that does not exceed a predetermined target charge power, 3. The power storage device according to claim 1, wherein the target charging power in the first time period is the maximum charging power or a first charging power smaller than the maximum charging power, and the target charging power in the second time period is a second charging power as the small charging power smaller than the first charging power.

4. 3. The power storage device according to claim 1, wherein, when performing the small charge control, the charge / discharge control unit charges the surplus power actually generated during the charging permission time period with a maximum charging power that does not exceed the small charge power that is smaller than the maximum charge power.

Images