JP2018121450A - Charge and discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charge and discharge device that improve charge and discharge efficiency by suppressing the remaining capacity of a storage battery from decreasing in low-load operation in a nighttime electric power time zone.SOLUTION: A charge and discharge device 1 comprises a control part 18 which generates and outputs to a power converter a target charge and discharge electric power command value specifying a target electric power value in charging and discharging of a storage battery by the power converter. The control part 18 comprises: an electric power command value setting part 23 which sets an electric power purchase command value as a target value of purchased electric energy based upon electric energy detected by first to third power detectors, nighttime electric power time zone data representing a nighttime electric power time zone of cheapest purchased electric energy from a commercial system in a day, current time data, and meteorological data; and a purchased electric power control part 22 which controls the power converter in electric power purchase by generating a target charge and discharge electric power command value based upon a difference between the electric power purchase command value and a purchased electric power value in electric power purchase detected by the first electric power detector.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a charge / discharge device connected to a storage battery mounted on an automobile.

  In recent years, a power supply system called a V2H system (Vehicle to Home) that uses an in-vehicle battery for driving an electric vehicle as a residential load is becoming widespread. Hereinafter, the “electric vehicle” may be simply referred to as “EV (Electric Vehicle)”, and the “vehicle battery for driving the electric vehicle” may be simply referred to as “EV battery”. The charging / discharging device used in such a power supply system provides surplus power to the EV battery when the power obtained by subtracting the residential load power from the power generated by the solar power generation system on a daytime sunny day becomes surplus. Charge. In addition, the charging / discharging device supplies power stored in the EV battery to the home load when the power obtained by subtracting the home load power from the power generated by the solar power generation system on a cloudy day or at night becomes insufficient. Make up for the shortage of electricity. In addition, the charging / discharging device purchases power during the nighttime when electricity is cheap and charges the EV battery, and supplies the electricity stored in the EV battery to the home load during daytime when electricity is high. Make up for the shortfall.

  In this way, by charging the EV battery with the electric power generated by the solar power generation system and the electric power purchased at night when the electricity bill is cheap, and supplying power to the residential load when necessary, In the future, self-sufficiency and economic efficiency are expected to be kept to a minimum with the purchase of electricity from commercial systems. In order to realize self-sufficiency life and economic efficiency while minimizing the purchase of electricity from such commercial grids, although it depends on the power generation capacity and weather of the solar power generation system, it depends on the residential load. It is necessary that sufficient power can be obtained from the solar power generation system, and surplus power generated by the solar power generation system is left without being sold. A battery capacity that can be stored without any problem is required. An EV battery generally has a large battery capacity, and it is assumed that the EV is connected to a charge / discharge device. However, the EV battery is suitable for a system that realizes a self-sufficient life.

  The charging / discharging device disclosed in Patent Document 1 includes a weather prediction unit that acquires a predicted value of a parameter relating to sunlight based on weather data acquired from a weather sensor, and an instruction frequency of charge / discharge control of the storage battery based on the predicted value. Create an initial operation plan for the storage battery with the instruction frequency determination unit to be determined and the charge / discharge amount instruction value for each time interval representing the instruction frequency, and evaluate the initial operation plan based on a predefined evaluation function to optimize operation An optimization unit that creates a plan, and a communication unit that transmits an optimal operation plan to the controller.

JP 2014-236541 A

  In order to realize self-sufficiency life and economic efficiency while minimizing the purchase of electricity from commercial systems, it is necessary to devise a method that does not reduce the remaining battery capacity of the EV battery as much as possible during the daily charge / discharge cycle. is there. In general, the remaining battery capacity increases due to charging of surplus power during the day, and decreases due to power supply at night. However, when the electric power stored in the EV battery is exhausted before the charging with surplus power on the next day is started, the charging / discharging operation of the charging / discharging device is stopped, and the household load is supplied with the purchased electric power. In addition, when the electric power stored in the EV battery is exhausted, a large amount of surplus power is required to return the battery remaining capacity to a certain remaining capacity level.

  In-home loads that operate during night hours tend to drive in a low-load state. When the stored power is supplied to the home load that is operated in such a low load state, the decrease in the remaining battery capacity is often considered to be small, but in reality, the power converter provided in the charge / discharge device at night The conversion efficiency in the time zone is lower than that in the daytime time zone. For this reason, the reduction in the remaining battery capacity increases as much as the conversion efficiency decreases. Further, the EV battery is normally in a fully charged state by forced charging operation in which power is purchased during the night time period and the EV battery is forcibly charged. For this reason, surplus power generated by solar power generation the next day is not stored in the EV battery, but must be sold to the grid side.

  In the technique disclosed in Patent Document 1, an optimal operation plan is transmitted to the controller based on weather data, but this does not take into account the conversion efficiency of the power converter during low-load operation in the night time zone. Therefore, when charging / discharging of the storage battery is performed in a state where the remaining capacity of the storage battery is reduced during low load operation during the nighttime power hours, compared to the case where charging / discharging of the storage battery is performed in a state where the remaining capacity of the storage battery is high, When the charge / discharge efficiency is lowered and the surplus power of the next day is charged to the storage battery, the surplus power for charging the storage battery cannot be purchased, and the energy efficiency of the entire power supply system is further improved. It was desired.

  This invention is made in view of the above, Comprising: It aims at obtaining the charging / discharging apparatus which suppresses the fall of the remaining capacity of a storage battery and improves charging / discharging efficiency at the time of low load driving | running | working at night electric power hours. To do.

  In order to solve the above-described problems and achieve the object, a charging / discharging device according to the present invention converts DC power supplied from a storage battery into AC power, converts AC power into DC power, and supplies the battery to the storage battery. A power converter, a first power detector for detecting a power value of AC power supplied from the commercial system and AC power supplied from the commercial system, a second power detector for detecting generated power, When the power converter charges and discharges the storage battery based on the third power detector that detects the AC power output from the power converter and the amount of power detected by each of the first to third power detectors A control unit that generates a target charge / discharge power command value that specifies the target power value of the power and outputs the target charge / discharge power command value to the power converter. And the amount of power purchased from the commercial grid is the highest in the day A purchased power command value setting unit for setting a purchased power command value, which is a target value of the purchased power amount, based on nighttime power time zone data indicating current nighttime power time zone, current time data, and weather data; A power converter at the time of power purchase by generating a target charge / discharge power command value based on a difference between the power purchase power command value and the power purchase power value detected at the time of power purchase detected by the first power detector. And a purchased power control unit for controlling the power.

  The charging / discharging device according to the present invention has an effect that charging / discharging efficiency can be improved by suppressing a decrease in the remaining capacity of the storage battery during low-load operation during the nighttime power hours.

Configuration diagram of charge / discharge device according to embodiment A diagram for explaining the operation of minimum power purchase when surplus power is generated Diagram for explaining the operation of minimum power purchase when insufficient power is generated A diagram for explaining the operation of minimum power purchase when there is insufficient power at low load The figure which shows the change of the surplus electric power when the minimum electric power purchase operation is performed continuously for one day, and the change of battery remaining capacity The figure which shows the change of the surplus electric power, and the change of battery remaining capacity when the power purchase minimum operation and the forced charge operation are performed in combination in one day The figure which shows an example of a 1-day operation | movement of the power purchase minimum operation performed with the charging / discharging apparatus which concerns on embodiment. The figure which shows an example of a 1 day operation | movement of the electric power purchase minimum operation and forced charge operation which are performed with the charging / discharging apparatus which concerns on embodiment. The flowchart which shows the control action of the charging / discharging driving | operation in the charging / discharging apparatus which concerns on embodiment

  Hereinafter, a charge / discharge device according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a configuration diagram of a charge / discharge device according to an embodiment. A power supply system 100 illustrated in FIG. 1 includes a charge / discharge device 1 according to an embodiment, a solar cell array 6, and a solar power generation system 7. A solar power generation system 7 is connected to the charge / discharge device 1, and a solar cell array 6 is connected to the solar power generation system 7.

  The photovoltaic power generation system 7 is a power conditioner that converts the power generated by the solar cell array 6 into AC power and outputs the AC power. The commercial power 5 connected to the charge / discharge device 1 and the residential load 4 and at least one of the power converters 17 included in the charge / discharge device 1. The in-house load 4 can be exemplified by a refrigerator, lighting, cooking equipment, a telephone, a television, or audio.

  EV2 is connected to charging / discharging device 1 through charging / discharging connector cable 2a. A storage battery 3 that is a DC power source for driving the EV 2 is mounted on the EV 2. In the present embodiment, the EV 2 is illustrated as an example of a vehicle on which the storage battery 3 is mounted. However, the vehicle on which the storage battery 3 is mounted is not limited to an electric vehicle, such as a plug-in hybrid vehicle or a plug-in hybrid electric vehicle. A car equipped with a secondary battery may be used.

  The charging / discharging device 1 includes a received power detector 11 that is a first power detector, a photovoltaic power detector 12 that is a second power detector, a reverse power detector 13, a self-sustained disconnector 14, 3 includes a charge / discharge power detector 15, a grid disconnector 16, a power converter 17, and a control unit 18. The control unit 18 sets a target when the power converter 17 charges and discharges the storage battery 3 based on the amount of power detected by each of the received power detector 11, the photovoltaic power generation detector 12, and the charge / discharge power detector 15. A target charge / discharge power command value 22 a for designating the power value is generated and output to the power converter 17. Details of the configuration of the control unit 18 will be described later.

  The received power detector 11 is arranged in the third electric circuit 43. The third electric circuit 43 is an electric circuit through which AC power supplied from the commercial system 5 to the power converter 17 and AC power supplied from the solar power generation system 7 to the commercial system 5 flow. The received power detector 11 detects AC power flowing through the third electric circuit 43 when selling power to the commercial system 5 or purchasing power from the commercial system 5, and uses the detected power value as the purchased power value 11a. To the control unit 18.

  The self-standing disconnector 14 is a switch that is disposed on the third electric circuit 43 and opens / closes AC power flowing through the third electric circuit 43, and is controlled by the control unit 18.

  The photovoltaic power detector 12 is disposed on the second electric path 42. The second electric circuit 42 includes AC power supplied from the solar power generation system 7 to the commercial system 5, power supplied from the solar power generation system 7 to the residential load 4, and power conversion from the solar power generation system 7 to the power converter 17. It is an electric circuit through which at least one electric power with the electric power supplied to flows.

  The photovoltaic power detector 12 detects AC power flowing through the second electric circuit 42 and outputs the detected power value to the control unit 18.

  The reverse power detector 13, the grid disconnector 16, and the charge / discharge power detector 15 are arranged in the first electric circuit 41. The first electric circuit 41 is an electric circuit through which AC power supplied from the solar power generation system 7 to the in-home load 4 or the power converter 17 and AC power supplied from the power converter 17 to the in-home load 4 flow.

  The reverse power detector 13 is an AC power detector for monitoring that the reverse power does not flow from the power converter 17 to the commercial system 5, and outputs the detected power value to the controller 18.

  The interconnecting disconnector 16 is a switch that opens and closes AC power flowing through the first electric circuit 41, and is controlled by the control unit 18.

  The charge / discharge power detector 15 detects the AC power flowing through the first electric circuit 41 when the charge / discharge power detector 15 performs the charge / discharge operation, and outputs the detected power value to the control unit 18.

  The power values detected by the received power detector 11, the reverse power detector 13, and the charge / discharge power detector 15 are input to the purchased power command value setting unit 23 of the control unit 18.

  The power converter 17 is bidirectional power conversion means. The power converter 17 operates according to the purchased power command value 23 a output from the purchased power command value setting unit 23 included in the control unit 18. The purchased power command value 23a is a target value of the purchased power amount. The power converter 17 converts the AC power supplied from the commercial system 5 or the photovoltaic power generation system 7 into DC power based on the purchased power command value 23a, and outputs the converted DC power. A second power conversion function for converting the DC power supplied from EV2 into AC power based on the value 23a and outputting the AC power. Hereinafter, the operation mode in which the power converter 17 is operated by the first power conversion function is referred to as “first operation mode”, and the operation mode in which the power converter 17 is operated by the second power conversion function is “second operation mode”. May be referred to as an “operation mode”. Since the structure of the bidirectional | two-way power conversion function of the power converter 17 is well-known, description is omitted.

  The control unit 18 includes a difference unit 20, a reverse power control unit 21, a purchased power control unit 22, a purchased power command value setting unit 23, a difference unit 24, and a storage unit 28.

  The storage unit 28 includes nighttime power time zone data 25 indicating a nighttime power hour zone in which the electricity bill of the power company is low, current time data 26 indicating the current time, and weights for determining a charging power value during forced charging operation. The weather data 27 that is a coefficient is stored. The nighttime power time zone data 25, the current time data 26 and the weather data 27 are a data group used when the purchased power command value setting unit 23 selects a target power value of the purchased power. The operation of the purchased power command value setting unit 23 will be described later.

  These data groups are transmitted from the display operation remote controller 30 which is a remote controller arranged near the charge / discharge device 1 or transmitted from the cloud server 31. In particular, since the weather data 27 is information that changes every moment, it is desirable that the weather data 27 is the latest data transmitted from the cloud server 31 via the Internet. The display operation remote controller 30 is a user interface, transmits a driving command from the user to the charging / discharging device 1, and receives driving state information, remaining battery capacity information, and vehicle connection state information output from the charging / discharging device 1. The information is displayed on a liquid crystal screen (not shown).

  Below, operation | movement of the control part 18 is demonstrated in detail. Hereinafter, a state in which power is supplied from the solar power generation system 7 but no power is supplied from the commercial system 5 is referred to as “at the time of power failure”. A state in which power is supplied from the commercial system 5 is referred to as “at the time of non-power failure”. In addition, since there is no supply of power from both the solar power generation system 7 and the commercial system 5, a state in which the power stored in the storage battery 3 of the EV 2 is supplied to the home load 4 is referred to as “during independent operation”. A state in which the power converter 17 charges the EV 2 storage battery 3 using AC power supplied from the solar power generation system 7 or the commercial system 5 is referred to as “at the time of charging”. In addition, a state in which the storage battery 3 is discharged in order to drive the in-home load 4 using the electric power stored in the storage battery 3 of the EV 2 is referred to as “during discharge”.

  The controller 18 links the charging / discharging device 1 to the commercial system 5 by turning on the self-sustained disconnector 14 when there is no power outage or when there is a power outage but no independent operation is performed. Moreover, the control part 18 operate | moves so that the charging / discharging apparatus 1 may be disconnected from the commercial system | strain 5 by turning off the independent disconnector 14 at the time of an independent operation. Further, at the time of charging, the control unit 18 operates to output the target charge / discharge power command value 22a to the power converter 17 and turn on the grid disconnector 16. Further, the control unit 18 operates to turn off the grid disconnector 16 when stopping the operation of the power converter 17.

  The control unit 18 uses the power values detected by the received power detector 11, the solar power generation power detector 12, and the reverse power detector 13 from the generated power of the solar power generation system 7 to determine the load of the home load 4. The difference power obtained by subtracting the power consumption is calculated.

  When the differential power shows a negative value, that is, the power supplied from the photovoltaic power generation system 7 is lower than the power consumption of the home load 4 and the power supplied to the home load 4 is insufficient. In this case, the control unit 18 does not purchase power from the commercial system 5, and operates the power converter 17 in the second operation mode described above to supply the shortage power to the home load 4.

  When the difference power shows a positive value, that is, when the power supplied from the solar power generation system 7 is higher than the power consumption of the home load 4 and the power supplied to the home load 4 is surplus and surplus power is generated. The control unit 18 charges the storage battery 3 with surplus power by operating the power converter 17 in the first operation mode without selling power to the commercial system 5.

  As described above, the control unit 18 includes a minimum power purchase operation mode for suppressing power sale to the commercial system 5 and power purchase from the commercial system 5. In the power purchase minimum operation mode, in order to control the sold power and the purchased power to be 0 [kW], first, the target value that is the purchased power command value 23a of the purchased power command value setting unit 23 is set to 0. [KW]. The difference unit 20 obtains a difference between the purchased power value 11 a detected by the received power detector 11 and the purchased power command value 23 a output from the purchased power command value setting unit 23. The purchased power control unit 22 receives the difference output from the differentiator 20 as an input, and the target charge / discharge power command value for the power converter 17 so that the purchased power value 11a becomes the purchased power command value 23a. 22a is output to perform feedback control.

  When a reverse power flow to the commercial system 5 occurs due to the AC power output from the power converter 17, the reverse power control unit 21 outputs a correction value based on the power value detected by the reverse power power detector 13. . The subtractor 24 corrects the target charge / discharge power command value 22a with the correction value output from the reverse power control unit 21. As a result, the charge / discharge device 1 performs feedback control to suppress reverse power.

  The purchased power command value setting unit 23 obtains surplus power or insufficient power using the nighttime power time zone data 25, the current time data 26 and the weather data 27 stored in the storage unit 28, and obtains the target power of the purchased power. It operates so as to change the purchased power command value 23a, which is a value.

  FIG. 2 is a diagram for explaining the operation of the minimum power purchase operation when surplus power is generated. The upper side of FIG. 2 shows the power supplied from the solar power generation system 7, the power sold to the commercial grid 5, and the power supplied to the home load 4 when the power converter 17 is stopped. The direction of the arrow represents the direction in which each power flows, and the size of the arrow represents the magnitude of each power. The lower side of FIG. 2 shows the power supplied from the photovoltaic power generation system 7, the power charged in the storage battery 3, and the power supplied to the home load 4 when the power converter 17 is in the minimum power purchase operation. . The direction of the arrow represents the direction in which power flows, and the size of the arrow represents the magnitude of power. The graph on the right side of FIG. 2 shows the relationship between surplus power and purchased power command value.

  When the power supplied from the solar power generation system 7 is higher than the power consumption of the home load 4 and the power supplied to the home load 4 is surplus and surplus power is generated, the charging / discharging device 1 is commercial Power is sold to the grid 5, and power is purchased from the commercial grid 5 at the time of the minimum power purchase operation. The surplus power at the time when the operation of the power converter 17 is stopped is sold to the commercial system 5, and is present at the position of the circle on the graph shown on the right side of FIG.

  When the power converter 17 starts the minimum power purchase operation, the target power of the power purchase command value 23a is set to 0 [kW], and the surplus power that has been sold to the commercial grid 5 is converted into the power converter. 17, the storage battery 3 is charged, and surplus power moves from the mark “◯” to the mark “Δ” on the graph shown on the right side of FIG.

  FIG. 3 is a diagram for explaining the operation of the minimum power purchase operation when insufficient power is generated. The upper side of FIG. 3 shows the power supplied from the solar power generation system 7, the power purchased from the commercial grid 5, and the power supplied to the home load 4 when the power converter 17 is stopped. The direction of the arrow represents the direction in which each power flows, and the size of the arrow represents the magnitude of each power. The lower side of FIG. 3 shows the power supplied from the solar power generation system 7, the power discharged from the storage battery 3, and the power supplied to the home load 4 when the power converter 17 is in the minimum power purchase operation. . The direction of the arrow represents the direction in which power flows, and the size of the arrow represents the magnitude of power. The graph on the right side of FIG. 3 shows the relationship between the insufficient power and the purchased power command value.

  When the power supplied from the photovoltaic power generation system 7 is lower than the power consumption of the home load 4 and the power supplied to the home load 4 is insufficient, the charging / discharging device 1 is in a state where the operation is stopped. In addition to feeding power from the solar power generation system 7 to the home load 4, power is purchased from the commercial system 5. Insufficient power at the time of stopping the operation of the power converter 17 is purchased from the commercial system 5 and is present at the position of the circle on the graph shown on the right side of FIG.

  Moreover, when it becomes an insufficiency electric power state, the charging / discharging apparatus 1 performs the electric power feeding from the power converter 17 to the household load 4 in addition to the electric power feeding from the solar power generation system 7 to the household load 4 at the time of the minimum power purchase operation. . When the power converter 17 starts the minimum power purchase operation, the target power of the power purchase command value 23a is set to 0 [kW], and insufficient power corresponding to the power purchased from the commercial grid 5 is generated from the storage battery 3. The insufficient power is covered by the discharged electric power and moves from a circle to a triangle on the graph shown on the right side of FIG.

  FIG. 4 is a diagram for explaining the operation of the minimum power purchase operation when insufficient power is generated at low load. On the left side of FIG. 4, in order from the top, a diagram showing the flow of power when the power converter 17 is stopped, a diagram showing the power flow when the power converter 17 is in a minimum power purchase operation, and a power converter 17 is a diagram showing another example of the flow of power during the minimum power purchase operation. The direction of the arrow shown in each of the three figures represents the direction in which power flows, and the size of the arrow represents the magnitude of power.

  On the right side of FIG. 4, in order from the top, the power converter 17 shows a graph showing the relationship between the insufficient power and the purchased power command value, and a graph showing the characteristics of the power conversion efficiency with respect to the output power of the power converter 17. Indicated. The horizontal axis of the lower right graph indicates the value of the AC output power of the power converter 17. The vertical axis of the lower right graph indicates the power conversion efficiency when the power converter 17 converts DC power into AC power, that is, the power conversion efficiency when the power converter 17 operates in the second operation mode. In general, the power conversion efficiency of the power converter 17 rapidly decreases in a region where the value of the AC output power of the power converter 17 is equal to or lower than a specific power value α [kW]. Of the AC output power of the power converter 17, a region having a specific power value α [kW] or less is referred to as a “low load region”.

  When the operation state of the home load 4 is a low load in the insufficient power state, the insufficient power when the operation of the power converter 17 is stopped is purchased from the commercial system 5 and is shown in the upper right of FIG. Above, it exists at the position of the circle.

  When the power purchase minimum operation time is started, the target power of the power purchase command value 23a is set to 0 [kW], and the insufficient power corresponding to the power purchased from the commercial grid 5 is caused by the power discharged from the storage battery 3. Covered and insufficient power moves from a circle to a triangle on the graph shown in the upper right of FIG.

  As shown in the lower right graph of FIG. 4, the conversion efficiency of the power converter 17 when the operation state of the home load 4 is in a low load region having a power value α [kW] or less is the operation state of the home load 4. A value lower than the power conversion efficiency when in a load region higher than the low load region is shown. Therefore, even if the output power to the alternating current side of the power converter 17 is a small value, the input power on the direct current side of the power converter 17 becomes relatively large. Therefore, as the alternating current output power decreases, the storage battery 3 The decrease in the remaining battery capacity is not reduced.

  As shown in another example at the time of the minimum power purchase operation in FIG. 4, even if the power consumption of the home load 4 is large, the generated power of the solar power generation system 7 is large. Even when the absolute value of the power obtained by subtracting the power consumption is equal to or less than the specific power value α [kW], the AC output power output from the power converter 17 is a value in the low load region.

  FIG. 5 is a diagram illustrating a change in surplus power and a change in remaining battery capacity when the minimum power purchase operation is continuously performed for one day. The upper side of FIG. 5 shows the relationship between the surplus power when the power converter 17 is stopped and the purchased power command value. Further, the upper side of FIG. 5 shows the relationship between the surplus power and the purchased power command value during the minimum purchased power operation. The lower side of FIG. 5 shows a change in the remaining battery capacity when the minimum power purchase operation is continuously performed for one day.

  The surplus power or the insufficient power when the power converter 17 is stopped is indicated by a combination of a solid line and a circle “◯”. The surplus power or the insufficient power when the target power of the purchased power command value 23a is set to 0 [kW] is indicated by a combination of a dotted line and a triangle “Δ”.

  According to FIG. 5, in the surplus power state where solar power generation increases in the daytime, the remaining battery capacity of the storage battery 3 increases due to surplus charging, and in the insufficient power state at night, the storage battery 3 discharges, Battery remaining capacity decreases. In the nighttime power hours when the electricity bill of the power company is low, the power consumption of the home load 4 is small, but in the case of low load output, that is, when the shortage power is in the range of 0 to α [kW], As described above, the power conversion efficiency of the power converter 17 is low. Therefore, in the nighttime power hours, the DC power supplied to the power converter 17 becomes relatively large, and the consumption of the power stored in the storage battery 3 becomes large. Accordingly, the remaining battery capacity during the nighttime power hours is smaller than the remaining battery capacity during the daytime hours.

  FIG. 6 is a diagram illustrating a change in surplus power and a change in remaining battery capacity when the minimum power purchase operation and the forced charging operation are performed in one day. The upper side of FIG. 6 shows the relationship between the surplus power and the purchased power command value when the minimum purchased power operation is performed at a time other than the nighttime power time zone. Further, the upper side of FIG. 6 shows the relationship between the surplus power and the purchased power command value when the forced charging operation and the minimum purchased power operation are performed in the nighttime power hours. The lower side of FIG. 6 shows changes in the remaining battery capacity when the minimum power purchase operation and the forced charging operation shown in the upper side of FIG. 6 are performed.

  The surplus power or the insufficient power when the power converter 17 is stopped is indicated by a combination of a solid line and a circle “◯”. The surplus power or the insufficient power when the target power of the purchased power command value 23a is set to 0 [kW] is indicated by a combination of a dotted line and a triangle “Δ”. The surplus power or the insufficient power in the forced charging operation when the target power of the purchased power command value 23a is set to 10 [kW] is indicated by a combination of a dotted line and a square “□”.

  In FIG. 6, it is assumed that the minimum power purchase operation is performed during the day, the forced charge operation is performed during the night power hours, and the operation of the power converter 17 is stopped during the full charge due to the timer setting. . In FIG. 6, the target power of the purchased power command value 23a at the time of the minimum power purchase operation is set to 0 [kW], and the target power of the purchased power command value 23a at the time of the forced charging operation is 10 [kW] as an example. ] Is set.

  At the time of the minimum power purchase operation, in the surplus power state in which solar power generation increases in the daytime, the remaining battery capacity of the storage battery 3 increases due to surplus charging, and in the shortage power state at night, the storage battery 3 discharges, whereby the storage battery 3 The remaining battery capacity is reduced.

  In the nighttime power hours when the electricity bill of the power company is low, forced charging operation is started by setting the timer. Thereby, the storage battery 3 is forcibly charged so as to approach the target power of the purchased power command value 23a. However, if the charge value that can be output from the power converter 17 is equal to or less than the target power, the charge value is limited by the output charge value.

  When the remaining battery capacity of the storage battery 3 is fully charged due to forced charging, the operation of the power converter 17 is stopped until the next minimum power purchase operation is started due to the timer setting. As a result, the remaining battery capacity during the nighttime power hours increases to 100% than the remaining battery capacity during the daytime hours. In this state, when the minimum power purchase operation is started on the next day, even if the surplus power state by solar power generation is reached, the surplus power cannot be stored in the storage battery 3 and must be sold to the grid side. .

  The charging / discharging device 1 according to the present embodiment is made to solve the problems described with reference to FIGS. 5 and 6. The charging / discharging device 1 operates the power converter 17 so as not to use up the remaining battery capacity when supplying the power of the storage battery 3 to the home load 4 in the night time zone, which is generally in a low load power state, The power converter 17 is operated so that the storage battery 3 is not fully charged by the purchased power in the time period so that excess power generated the next day cannot be charged into the storage battery 3.

  FIG. 7 is a diagram illustrating an example of an operation of one day of the minimum power purchase operation performed by the charge / discharge device according to the embodiment. On the upper side of FIG. 7, the relationship between the surplus power when the power converter 17 is stopped and the purchased power command value is shown. Moreover, the upper side of FIG. 7 shows the relationship between the surplus power and the purchased power command value during the minimum purchased power operation. The lower side of FIG. 7 shows a change in the remaining battery capacity when the minimum power purchase operation is continuously performed for one day.

  The surplus power or the insufficient power when the power converter 17 is stopped is indicated by a combination of a solid line and a circle “◯”. The surplus power or the insufficient power when the target power of the purchased power command value 23a is dynamically set to the value selected by the purchased power command value setting unit 23 is indicated by a combination of a dotted line and a triangle “Δ”. .

  In the charging / discharging device 1 according to the embodiment, the target power of the purchased power command value 23a is not always set to 0 [kW], but the nighttime power time zone data 25 and the current time data 26 shown in FIG. Thus, the value selected by the purchased power command value setting unit 23 is dynamically set. A specific example of the setting method will be described. A setting table is recorded in advance in the purchased power command value setting unit 23. In the setting table, a plurality of times in the nighttime power time zone data 25 are associated with a purchased power command value 23a corresponding to a target power value corresponding to the plurality of times, and the purchased power command When the nighttime power time zone data 25 and the current time data 26 are input to the value setting unit 23, the purchased power command value setting unit 23 uses the target power corresponding to each time in the nighttime power zone as the purchased power command. Output as value 23a.

In FIG. 7, the setting conditions for the purchased power command value 23a are as follows.
(1) Outside the hours other than the nighttime power hours, the charging / discharging device 1 outputs a purchased power command value 23a with 0 [kW] as a target value.
(2) In the case of a nighttime power time zone and a low load output (0 to α [kW]), the purchased power command value setting unit 23 controls the power to the home load 4 while suppressing the discharge of the storage battery 3. In order to cover the above with electric power purchase, the electric power purchase command value 23a having a target value that is the same as the state of surplus power or insufficient power at the time of operation stop is output. That is, the purchased power command value setting unit 23 outputs a purchased power command value 23a that follows the target value when the operation is stopped.
(3) In the case of a nighttime power time zone and a normal load output (α [kW] or more), the charging / discharging device 1 sets the target power value so that the output power becomes 0 [kW]. The value 23a is output.

  In the surplus power state in which solar power generation increases in the daytime, the remaining battery capacity of the storage battery 3 increases due to surplus charging, and in the insufficient power condition at night, the remaining battery capacity of the storage battery 3 decreases due to the discharge of the storage battery 3. .

  In the nighttime hours when the electricity bill of the power company is low, when the power consumption of the home load 4 is low load output, the power conversion efficiency of the power converter 17 becomes low as described above, and the power stored in the storage battery 3 The consumption of increases. Therefore, the charging / discharging device 1 does not perform power supply to the home load 4 by the storage battery 3, and causes surplus power or insufficient power to follow. That is, the charging / discharging device 1 supplies the purchased power to the home load 4.

  When the power consumption of the home load 4 is a normal load output (α [kW] or more), the power conversion efficiency is high. Therefore, the charging / discharging device 1 supplies power to the home load 4 by the storage battery 3, thereby remaining battery capacity. It works so as not to use up. As a result, the battery remaining capacity in the night power hours shown in FIG. 7 is maintained at a value close to 50%.

  FIG. 8 is a diagram illustrating an example of one-day operation of the minimum power purchase operation and the forced charge operation performed by the charge / discharge device according to the embodiment. The upper side of FIG. 8 shows the relationship between the surplus power and the purchased power command value when the minimum purchased power operation is performed at a time other than the nighttime power time zone. Further, the upper side of FIG. 8 shows the relationship between the surplus power and the purchased power command value when the forced charging operation and the minimum purchased power operation are performed during the nighttime power hours. The lower side of FIG. 8 shows changes in the remaining battery capacity when the minimum power purchase operation and the forced charging operation shown in the upper side of FIG. 8 are performed.

  The surplus power or the insufficient power when the power converter 17 is stopped is indicated by a combination of a solid line and a circle “◯”. The surplus power or the insufficient power when the target power of the purchased power command value 23a is set to 0 [kW] is indicated by a combination of a dotted line and a triangle “Δ”. The surplus power or the insufficient power in the forced charging operation when the target power of the purchased power command value 23a is set to 10 [kW] is indicated by a combination of a dotted line and a square “□”.

  In FIG. 8, the minimum power purchase operation is performed during the daytime due to the timer setting, and the minimum power purchase operation and the forced charge operation are performed during the night power hours. The operation at the time of the minimum power purchase operation is the same as the operation described in FIG. The forced charging operation is set at night when the electricity bill is cheap. The target power of the purchased power command value 23a in this case is selected by the purchased power command value setting unit 23 in FIG. 1, and the target power is multiplied by a weighting factor of weather data by 10 [kW] (Max.). Β [kW], which is the calculated value, is set.

  The purchased power command value setting unit 23 receives the weather data 27 transmitted from the display operation remote controller 30 or the cloud server 31. The weather data 27 is information for predicting the weather of the next day. Specifically, the weather data 27 is data including a solar radiation amount predicted value indicating the solar radiation amount of the next day. Based on this data, a weighting factor is set such that the numerical value is low when the next day's weather is bad and the numerical value is high when the weather is good. For example, when the weighting factor is a small value “0” to “1”, and the next day's weather is bad, it is not possible to charge the storage battery 3 with surplus power by the solar power generation system 7, so the remaining battery capacity The value is in the vicinity of “1” so that becomes higher than usual. When the next day's weather is good, it can be expected that surplus power from the solar power generation system 7 is charged into the storage battery 3, and thus the value is near “0” so that the remaining battery capacity becomes lower than usual. However, since the efficiency of the power converter 17 is reduced at low load charging, the operation is performed so that a limit is applied at α [kW]. The graph on the lower right of FIG. 8 shows the relationship between the weighting factor set in this way and the target power of the purchased power command value 23a.

  FIG. 9 is a flowchart showing the control operation of the charge / discharge operation in the charge / discharge device according to the embodiment. The charge / discharge operation is the aforementioned minimum power purchase operation (charge / discharge) or forced charge operation (charge only). The charging / discharging device 1 adds up the power detected by each of the received power detector 11, the photovoltaic power detector 12 and the charging / discharging power detector 15, and obtains the power consumption of the home load 4 from the sum (S1). ). The charging / discharging device 1 obtains surplus power (plus) or insufficient power (minus) from the difference power obtained by subtracting the power supplied to the home load from the photovoltaic power (S2).

  Next, the purchased power command value setting unit 23 obtains a purchased power command value 23a (S3). As shown in FIG. 7, the selection condition at the time of the minimum power purchase operation is 0 [kW] as a target value if it is not in the night power hours. In addition, in the case of a nighttime power time zone and a low load output (insufficient power is 0 to α [kW]), the surplus power or the power that follows the insufficient power is the target value. Further, in the case of a nighttime power time zone and a normal load output (α [kW] or more), 0 [kW] is a target value.

  As shown in FIG. 8, the selection condition at the time of the forced charging operation is 10 [kW] (Max.) As a target value if it is outside the night power hours, and 10 [kW] (Max. Max.) Is β [kW], which is a value obtained by multiplying the weighting coefficient of the weather data by the weather data.

  Next, the difference unit 20 obtains the difference between the purchased power or the sold power detected by the received power detector 11 and the purchased power command value 23a (S4). The purchased power control unit 22 calculates a target charge / discharge power command value 22a corresponding to the difference (S5), and the purchased power control unit 22 outputs the charge / discharge current of the power converter 17 so that the difference becomes zero. Is feedback-controlled (S7). The reverse flow power detector 13 monitors that the reverse flow power does not flow out to the commercial system 5 side, and in the case of reverse flow, the reverse flow power control unit 21 corrects the target charge / discharge power command value 22a so as not to reverse flow ( S6). As a result of the charge / discharge current control in S7, when the operation of the power converter 17 is not stopped (step S8, No), the control unit 18 returns to the process of S1 and stops the operation of the power converter 17 (step S8, Yes), the control unit 18 ends the process.

  As described above, according to the charging / discharging device 1 according to the embodiment, when the power purchase minimum operation is performed in the nighttime power hours when the electricity bill of the power company is low, the power consumption of the home load is low load output (insufficient) When the power is 0 to α [kW]), the power conversion efficiency is poor, and the reduction in the remaining battery capacity becomes large. For this reason, at the time of low load output, power supply is not performed, and surplus (insufficient) power tracking, that is, operation is performed so as to cover the home load by power purchase. In addition, when the power consumption of the home load is a normal load output (α [kW] or more), the power conversion efficiency is good, and thus the home load is operated by supplying power. Since the remaining battery capacity of the day operates so as not to be used up with respect to the original remaining battery capacity, it is possible to efficiently charge and discharge within the battery capacity range without stopping the minimum power purchase operation due to overdischarge. is there.

  Further, when the forced charging operation is performed in the nighttime power hours when the electricity bill of the power company is low, the target power of the purchased power command value operates so as to be set to a value multiplied by a weighting factor of weather data. When the next day's weather is bad, it is not expected that the surplus power from the solar power generation system will be charged to the in-vehicle battery for driving, so the remaining battery capacity will be higher than normal, and the next day's weather will be If it is good, it can be expected that the surplus power generated by the photovoltaic power generation system will be charged into the on-vehicle battery for driving, so that the remaining battery capacity is lower than usual. Therefore, there is an effect that more surplus power can be charged on the next day.

  In the description of the present embodiment, the example using the storage battery 3 mounted on the EV 2 has been described. However, the storage battery 3 has the same effect even when a stationary storage battery is used.

  The configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

  DESCRIPTION OF SYMBOLS 1 Charging / discharging apparatus, 2a Charging / discharging connector cable, 3 Storage battery, 4 Home load, 5 Commercial system, 6 Solar cell array, 7 Solar power generation system, 11 Received power detector, 11a Purchased power value, 12 Solar power generation Detector, 13 Reverse power detector, 14 Stand-alone disconnector, 15 Charge / discharge power detector, 16 Interconnection disconnector, 17 Power converter, 18 Control unit, 20 Difference unit, 21 Reverse power control unit, 22 Power purchase power control unit, 22a Target charge / discharge power command value, 23 Power purchase power command value setting unit, 23a Power purchase power command value, 24 Differential, 25 Night power time zone data, 26 Current time data, 27 Weather data , 28 storage unit, 30 display operation remote control, 31 cloud server, 41 first electric circuit, 42 second electric circuit, 43 third electric circuit, 100 power supply system.

Claims (6)

A power converter that converts DC power supplied from a storage battery into AC power, converts AC power into DC power, and supplies the power to the storage battery;
A first power detector for detecting a power value of AC power supplied from the commercial system and AC power supplied from the commercial system;
A second power detector for detecting generated power;
A third power detector for detecting AC power output from the power converter;
Based on the amount of power detected by each of the first to third power detectors, a target charge / discharge power command value that specifies a target power value when the power converter charges / discharges the storage battery is generated. A controller for outputting to the power converter,
The controller is
The amount of electric power detected by each of the first to third electric power detectors, the night electric power time zone data indicating the night electric power time zone in which the electric energy purchased from the commercial grid is the cheapest in one day, and the current time Based on the data and weather data, a purchased power command value setting unit for setting a purchased power command value that is a target value of the purchased power amount,
Based on the difference between the purchased power command value and the purchased power value at the time of purchase detected by the first power detector, the target charge / discharge power command value is generated, A purchased power control unit for controlling the power converter;
A charge / discharge device comprising:   The purchased power command value setting unit is configured to use the purchased power based on the nighttime power time zone data, the current time data, and the weather data transmitted from a server or a remote controller provided outside the charging / discharging device. The charge / discharge device according to claim 1, wherein a command value is set. The purchased power command value setting unit is set such that the residential load is in a low power consumption state when the output power value of the power converter is equal to or lower than a specific power value in the nighttime power time zone. ,
The purchased power command value setting unit sets the purchased power command value so as to suppress discharge from the storage battery when the power converter operates in the low power consumption state. Or the charging / discharging apparatus of 2.   The charge / discharge device according to claim 3, wherein the specific power value is a power value determined by a conversion efficiency of the power converter.   The power purchase power command value setting unit sets the power purchase power command value using a predicted amount of solar radiation obtained from the weather data in forced charging for charging the storage battery during night power hours. The charge / discharge device according to claim 1 or 2, characterized in that   The charging / discharging device according to claim 5, wherein the power purchase command value setting unit uses the predicted amount of solar radiation indicating the amount of solar radiation on the next day.

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