JP6818566B2 - Charge / discharge device - Google Patents

Description

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

In recent years, a power supply system called a V2H system (Vehicle to Home), which uses an in-vehicle battery for driving an electric vehicle as a load in a house, is becoming widespread. In the following, the "electric vehicle" may be simply referred to as an "EV (Electric Vehicle)", and the "vehicle-mounted battery for driving an electric vehicle" may be simply referred to as an "EV battery". The charging / discharging device used in such a power supply system supplies surplus power to the EV battery when the power generated by the solar power generation system minus the in-house load power becomes surplus on a sunny day. Charge. In addition, the charging / discharging device supplies the power stored in the EV battery to the home load when the power generated by the solar power generation system minus the home load power becomes insufficient on a cloudy day or at night. By doing so, it makes up for the shortage of electricity. In addition, the charging / discharging device purchases electricity during the nighttime hours when the electricity bill is low and charges the EV battery, and supplies the power stored in the EV battery to the home load during the daytime hours when the electricity bill is high. Make up for the shortfall.

In this way, the power generated by the photovoltaic power generation system and the purchased power during the nighttime when the electricity bill is low are charged in the EV battery, and power is supplied to the in-house load when necessary. It is expected that the self-sufficient life and economic efficiency will be improved by minimizing the purchase of electricity from the commercial system. In order to realize a self-sufficient life and improvement of economic efficiency that minimizes the purchase of electricity from such commercial systems, it depends on the power generation capacity of the photovoltaic power generation system and the weather, but it depends on the load in the house. It is necessary that sufficient power can be obtained from the photovoltaic power generation system, and the surplus electricity generated by the photovoltaic power generation system is left over without being sold. It requires a battery capacity that can be stored without any problems. EV batteries generally have a large battery capacity, and it is premised that the EV is connected to a charging / discharging device, but EV batteries are suitable for a system that realizes a self-sufficient life.

The charging / discharging device disclosed in Patent Document 1 has a weather prediction unit that acquires predicted values of parameters related to sunshine based on weather data acquired from a weather sensor, and an instruction frequency for charge / discharge control of a storage battery based on the predicted values. An initial operation plan of the instruction frequency determination unit to be determined and a storage battery having an instruction value of charge / discharge amount for each time interval indicating the instruction frequency is created, and the initial operation plan is evaluated based on a predetermined evaluation function for optimum operation. It includes an optimization unit that creates a plan and a communication unit that transmits the optimum operation plan to the controller.

Japanese Unexamined Patent Publication No. 2014-236541

In order to realize a self-sufficient life and improved economic efficiency that minimizes the purchase of electricity from commercial systems, it is necessary to devise ways to minimize the remaining battery capacity of EV batteries during the daily charge / discharge cycle. is there. In general, the remaining battery capacity increases with the charging of surplus power during the day and decreases with the power supply at night. However, if the power stored in the EV battery is exhausted by the time the charging with the surplus power on the next day is started, the charging / discharging operation of the charging / discharging device is stopped, and the power purchased is supplied to the in-house load. Further, when the electric power stored in the EV battery is exhausted, a large amount of surplus electric power is required to return the remaining battery capacity to a certain remaining capacity level.

In-house loads that operate during the night hours generally tend to operate under low load conditions. When supplying stored power to the in-house load that operates under such a low load state, it is often thought that the decrease in the remaining battery capacity is small, but in reality, the power converter of the charge / discharge device is equipped at night. The conversion efficiency in the time zone is lower than the conversion efficiency in the daytime time zone. Therefore, the decrease in the remaining battery capacity increases as the conversion efficiency decreases. In addition, the EV battery is usually in a fully charged state by the forced charging operation in which the EV battery is forcibly charged by purchasing power during the night time. Therefore, the surplus power generated by the photovoltaic power generation on the next day is not stored in the EV battery and must be sold to the grid side.

In the technique disclosed in Patent Document 1, the optimum operation plan is transmitted to the controller based on the meteorological data, but the conversion efficiency of the power converter is not taken into consideration during the low load operation during the night time. Therefore, when the storage battery is charged and discharged while the remaining capacity of the storage battery is low during low-load operation during the nighttime power hours, compared to the case where the storage battery is charged and discharged while the remaining capacity of the storage battery is high. In addition to lowering the charging / discharging efficiency, when the surplus power of the next day is charged to the storage battery, the surplus power for charging the storage battery cannot be purchased, further improving the energy efficiency of the entire power supply system. It was desired.

The present invention has been made in view of the above, and an object of the present invention is to obtain a charge / discharge device that suppresses a decrease in the remaining capacity of a storage battery and improves charge / discharge efficiency during low-load operation during nighttime power hours. To do.

In order to solve the above-mentioned problems and achieve the object, the charging / discharging device according to the present invention converts the DC power supplied from the storage battery into AC power, converts the AC power into DC power, and supplies the AC power to the storage battery. A power converter, a first power detector that detects the power value of the AC power supplied from the commercial system and the AC power supplied to the commercial system , and a second power detector that detects the generated power. When the power converter charges and discharges the storage battery based on the amount of power detected by each of the third power detector that detects the AC power output from the power converter and the first to third power detectors. It is equipped with a control unit that generates a target charge / discharge power command value that specifies the target power value of the above and outputs it to the power converter, and the control unit is the amount of power detected by each of the first to third power detectors. Based on the nighttime power time zone data indicating the nighttime power time zone where the amount of power purchased from the commercial system is the cheapest in the day, the current time data, and the weather data, the purchase which is the target value of the amount of power purchased. Target charge / discharge based on the difference between the power purchase command value setting unit that sets the power command value, the power purchase command value, and the power purchase power value at the time of power purchase detected by the first power detector. It is characterized by including a power purchase power control unit that controls a power converter at the time of power purchase by generating a power command value.

The charging / discharging device according to the present invention has an effect that it is possible to suppress a decrease in the remaining capacity of the storage battery and improve the charging / discharging efficiency during low-load operation during the nighttime power hours.

Configuration diagram of the charging / discharging device according to the embodiment The figure for demonstrating the operation of the minimum power purchase operation when surplus power is generated. The figure for demonstrating the operation of the minimum power purchase operation when the power shortage occurs. The figure for demonstrating the operation of the minimum power purchase operation when the power shortage occurs at a low load. The figure which shows the change of surplus power and the change of the remaining battery capacity when the minimum power purchase operation is continuously performed for one day. The figure which shows the change of surplus power and the change of the remaining battery capacity when the minimum power purchase operation and the forced charge operation are performed in combination in one day. The figure which shows an example of the operation of one day of the minimum power purchase operation executed by the charge / discharge device which concerns on embodiment. The figure which shows an example of one day operation of the power purchase minimum operation and forced charge operation executed by the charge / discharge device which concerns on embodiment. A flowchart showing a control operation of charge / discharge operation in the charge / discharge device according to the embodiment.

Hereinafter, the charging / discharging device according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment.

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

The photovoltaic power generation system 7 is a power conditioner that converts the electric power generated by the solar cell array 6 into AC electric power and outputs the AC electric power to the commercial system 5 connected to the charging / discharging device 1 and a home load. It is supplied to at least one of 4 and the power converter 17 included in the charging / discharging device 1. Examples of the home load 4 include a refrigerator, lighting, cooking equipment, a telephone, a television, and audio.

The EV 2 is connected to the charging / discharging device 1 via the charging / discharging connector cable 2a. The EV 2 is equipped with a storage battery 3 which is a DC power source for driving the EV 2. In the present embodiment, EV2 is illustrated as an example of a vehicle equipped with the storage battery 3, but the vehicle equipped with the storage battery 3 is not limited to the electric vehicle, and is referred to as a plug-in hybrid vehicle or a plug-in hybrid electric vehicle. It may be an automobile equipped with a secondary battery.

The charging / discharging device 1 includes a received power detector 11 which is a first power detector, a solar power generation power detector 12 which is a second power detector, a reverse tide power detector 13, a self-sustaining power detector 14, and a second power detector. The charge / discharge power detector 15, the interconnection disconnector 16, the power converter 17, and the control unit 18, which are the power detectors of No. 3, are provided. The control unit 18 targets 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 solar power generation power detector 12, and the charge / discharge power detector 15. A target charge / discharge power command value 22a for designating a 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 the AC power supplied from the commercial system 5 to the power converter 17 and the AC power supplied from the photovoltaic power generation system 7 to the commercial system 5 flow. The received power detector 11 detects the 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 sets the detected power value as the purchased power value 11a. , Output to the control unit 18.

The self-sustaining liner 14 is a switch arranged on the third electric circuit 43 and opens and closes the AC power flowing through the third electric circuit 43, and is controlled by the control unit 18.

The photovoltaic power generation detector 12 is arranged in the second electric circuit 42. The second electric circuit 42 includes AC power supplied from the photovoltaic power generation system 7 to the commercial system 5, electric power supplied from the photovoltaic power generation system 7 to the home load 4, and a power converter 17 from the photovoltaic power generation system 7. It is an electric circuit through which at least one electric power and the electric power supplied to the electric power flow.

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

The reverse tide power detector 13, the interconnection 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 the AC power supplied from the photovoltaic power generation system 7 to the home load 4 or the power converter 17 and the AC power supplied from the power converter 17 to the home load 4 flow.

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

The interconnection disconnector 16 is a switch that opens and closes the 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 charge / discharge operation, and outputs the detected power value to the control unit 18.

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

The power converter 17 is a bidirectional power conversion means. The power converter 17 operates according to the power purchase power command value 23a output from the power purchase power command value setting unit 23 included in the control unit 18. The power purchase command value 23a is a target value of the power purchase amount. The power converter 17 has a first power conversion function that converts AC power supplied from the commercial system 5 or the solar power generation system 7 into DC power and outputs the power based on the power purchase power command value 23a, and the power purchase power command. It has a second power conversion function that converts DC power supplied from EV2 into AC power and outputs it based on the value 23a. In the following, 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". Operation mode ". Since the configuration of the bidirectional power conversion function of the power converter 17 is known, the description thereof is omitted.

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

The storage unit 28 contains nighttime power time zone data 25 indicating a nighttime power time zone in which the electricity bill of the electric power company is cheap, current time data 26 indicating the current time, and weights for determining the charging power value during forced charging operation. Meteorological data 27, which is a coefficient, is stored. The nighttime power time zone data 25, the current time data 26, and the weather data 27 are data groups used when the power purchase power command value setting unit 23 selects the target power value of the power purchase power. The operation of the power purchase 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 charging / discharging device 1, or is transmitted from the cloud server 31. In particular, since the weather data 27 is information that changes from moment to moment, it is desirable that it is the latest data transmitted from the cloud server 31 via the Internet. The display operation remote controller 30 is a user interface, transmits an operation command from the user to the charge / discharge device 1, and receives operation state information, battery remaining capacity information, and vehicle connection state information output from the charge / discharge device 1. , This information is displayed on a liquid crystal screen (not shown).

Hereinafter, the operation of the control unit 18 will be described in detail. In the following, a state in which power is supplied from the photovoltaic power generation system 7 but not supplied from the commercial system 5 is referred to as “during a power failure”. Further, the state in which power is supplied from the commercial system 5 is referred to as "non-power failure". Further, since there is no power supply from both the photovoltaic power generation system 7 and the commercial system 5, the state in which the power stored in the storage battery 3 of the EV 2 is supplied to the in-house load 4 is referred to as "independent operation". Further, the state in which the power converter 17 charges the storage battery 3 of the EV2 using the AC power supplied from the photovoltaic power generation system 7 or the commercial system 5 is referred to as “during charging”. Further, a state in which the storage battery 3 is discharged in order to drive the in-house load 4 by using the electric power stored in the storage battery 3 of the EV 2 is referred to as “during discharge”.

The control unit 18 connects the charging / discharging device 1 to the commercial system 5 by turning on the self-sustaining liner 14 when there is no power failure or when there is a power failure but the self-sustaining operation is not performed. Further, the control unit 18 operates so as to disconnect the charging / discharging device 1 from the commercial system 5 by turning off the self-sustaining demultiplexer 14 during the self-sustaining operation. Further, the control unit 18 outputs the target charge / discharge power command value 22a to the power converter 17 at the time of charging, and operates so as to turn on the interconnection disconnector 16. Further, the control unit 18 operates so as to turn off the interconnection disconnector 16 when the operation of the power converter 17 is stopped.

The control unit 18 uses the power values detected by each of the received power detector 11, the photovoltaic power detector 12, and the reverse tide power detector 13, and uses the power generated by the photovoltaic power generation system 7 to generate a load 4 in the house. Calculate the differential power after deducting the power consumption.

When the differential power shows a negative value, that is, the power supplied from the solar power generation system 7 becomes lower than the power consumption of the home load 4, and the power supplied to the home load 4 becomes insufficient. In this case, the control unit 18 operates the power converter 17 in the second operation mode described above without purchasing power from the commercial system 5, thereby supplying power to the in-house load 4 for the insufficient power.

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

In this way, the control unit 18 includes a power purchase minimum operation mode for suppressing the sale of power to the commercial system 5 and the purchase of power from the commercial system 5. In the power purchase minimum operation mode, in order to control the power sale power and the power purchase power to be 0 [kW], first, the target value which is the power purchase power command value 23a of the power purchase power command value setting unit 23 is set to 0. Let it be [kW]. In the diffifier 20, the difference between the power purchase power value 11a detected by the power receiving power detector 11 and the power purchase power command value 23a output from the power purchase command value setting unit 23 is obtained. The power purchase power control unit 22 receives the difference output from the diffifier 20 as an input, and sets the target charge / discharge power command value for the power converter 17 so that the power purchase power value 11a becomes the power purchase power command value 23a. 22a is output and feedback control is performed.

When the AC power output from the power converter 17 causes a reverse tide to the commercial system 5, the reverse tide power control unit 21 outputs a correction value based on the power value detected by the reverse tide power detector 13. .. The diffifier 24 corrects the target charge / discharge power command value 22a with the correction value output from the reverse tide power control unit 21. As a result, the charging / discharging device 1 is subjected to feedback control for suppressing the reverse tide.

The power purchase power command value setting unit 23 uses the nighttime power time zone data 25, the current time data 26, and the weather data 27 stored in the storage unit 28 to obtain surplus power or insufficient power, and obtains the target power of the power purchase power. It operates so as to change the power purchase 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. On the upper side of FIG. 2, when the power converter 17 is stopped, the power supplied from the photovoltaic power generation system 7, the power sold to the commercial system 5, and the power supplied to the home load 4 are shown. The direction of the arrow indicates the direction in which each electric power flows, and the size of the arrow indicates the magnitude of each electric 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 indicates the direction in which electric power flows, and the size of the arrow indicates the magnitude of electric power. The graph on the right side of FIG. 2 shows the relationship between the surplus power and the power purchase command value.

When the electric power supplied from the photovoltaic power generation system 7 becomes higher than the power consumption of the in-house load 4 and the electric power supplied to the in-house load 4 becomes surplus and surplus electric power is generated, the charging / discharging device 1 is commercialized when the operation is stopped. Power is sold to system 5, and power is purchased from commercial system 5 during the minimum power purchase operation. The surplus power when the operation of the power converter 17 is stopped is sold to the commercial system 5 and exists at the position marked with a 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 power command value 23a is set to 0 [kW], and the surplus power sold to the commercial system 5 is the power converter. The storage battery 3 is charged by 17, and the surplus power moves from the ◯ mark to the delta mark 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. On the upper side of FIG. 3, when the power converter 17 is stopped, the power supplied from the photovoltaic power generation system 7, the power purchased from the commercial system 5, and the power supplied to the home load 4 are shown. The direction of the arrow indicates the direction in which each electric power flows, and the size of the arrow indicates the magnitude of each electric power. The lower side of FIG. 3 shows the power supplied from the photovoltaic 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 indicates the direction in which electric power flows, and the size of the arrow indicates the magnitude of electric power. The graph on the right side of FIG. 3 shows the relationship between the insufficient power and the power purchase command value.

When the electric power supplied from the photovoltaic power generation system 7 becomes lower than the power consumption of the in-house load 4 and the electric power supplied to the in-house load 4 becomes insufficient, the charging / discharging device 1 is stopped. , In addition to supplying power from the photovoltaic power generation system 7 to the in-house load 4, power is purchased from the commercial system 5. The insufficient power when the operation of the power converter 17 is stopped is purchased from the commercial system 5 and exists at the position marked with a circle on the graph shown on the right side of FIG.

Further, in the case of insufficient power, the charging / discharging device 1 supplies power from the power converter 17 to the home load 4 in addition to power being supplied from the photovoltaic power generation system 7 to the home load 4 during the minimum power purchase operation. .. When the power converter 17 starts the minimum power purchase operation, the target power of the power purchase power command value 23a is set to 0 [kW], and the insufficient power corresponding to the power purchased from the commercial system 5 is generated from the storage battery 3. It is covered by the discharged power, and the insufficient power moves from the ○ mark to the △ mark 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 occurs at the time of low load. On the left side of FIG. 4, in order from the top, a diagram showing the power flow when the power converter 17 is stopped, a diagram showing the power flow when the power converter 17 is in the minimum power purchase operation, and a power converter. FIG. 17 is shown with a diagram showing another example showing the flow of electric power at the time of the minimum power purchase operation. The direction of the arrow shown in each of the three figures indicates the direction in which electric power flows, and the size of the arrow indicates the magnitude of electric power.

On the right side of FIG. 4, in order from the top, a graph showing the relationship between the insufficient power of the power converter 17 and the power purchase command value and a graph showing the characteristics of the power conversion efficiency with respect to the output power of the power converter 17 are shown. Shown. The horizontal axis of the lower right graph shows the value of the AC output power of the power converter 17. The vertical axis of the lower right graph shows 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. The power conversion efficiency of the power converter 17 generally drops sharply in a region where the AC output power value of the power converter 17 is equal to or less 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 there is insufficient power and the operating state of the in-house load 4 is low, the insufficient power when the power converter 17 is stopped is purchased from the commercial system 5 and is shown in the upper right graph of FIG. Above, it exists at the position marked with a circle.

When the minimum power purchase operation is started, the target power of the power purchase power command value 23a is set to 0 [kW], and the insufficient power corresponding to the power purchased from the commercial system 5 is generated by the power discharged from the storage battery 3. The supplied and insufficient power moves from the ○ mark to the △ mark 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 operating state of the in-house load 4 is in the low load region of the power value α [kW] or less depends on the operating state of the in-house load 4. It shows a value lower than the power conversion efficiency when the load region is higher than the low load region. Therefore, even if the output power of the power converter 17 to the AC side is small, the input power of the DC side of the power converter 17 is relatively large. Therefore, as the AC output power becomes smaller, the storage battery 3 The decrease in the remaining battery capacity of the battery is not small.

As shown in another example of the minimum power purchase operation in FIG. 4, even if the power consumption of the in-house load 4 is large, the generated power of the solar power generation system 7 is large, so that the generated power is changed to the in-house load 4. Even when the absolute value of the power after deducting 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 the value in the low load region.

FIG. 5 is a diagram showing changes in surplus power and changes in battery remaining 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 power purchase command value. Further, the upper side of FIG. 5 shows the relationship between the surplus power at the time of the minimum power purchase operation and the power purchase power command value. The lower side of FIG. 5 shows the change in the remaining battery capacity when the minimum power purchase operation is continuously performed for one day.

The surplus power or 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 insufficient power when the target power of the power purchase 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 in which the amount of photovoltaic power generation increases in the daytime, the remaining battery capacity of the storage battery 3 increases due to the surplus charging, and in the insufficient power state at night, the storage battery 3 is discharged to discharge the storage battery 3. Battery capacity is reduced. In the nighttime power hours when the electricity bill of the electric power company is low, even though the power consumption of the in-house load 4 is small, when the load output is low, that is, when the insufficient power is in the range of 0 to α [kW], the above-mentioned As described above, the power conversion efficiency of the power converter 17 is low. Therefore, in the nighttime power time zone, 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. Therefore, 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 showing a change in surplus power and a change in battery remaining capacity when the minimum power purchase operation and the forced charge operation are performed in combination in one day. The upper part of FIG. 6 shows the relationship between the surplus power and the power purchase command value when the minimum power purchase 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 power purchase command value when the forced charging operation and the minimum power purchase operation are performed during the nighttime power time zone. The lower side of FIG. 6 shows the change 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 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 insufficient power when the target power of the power purchase 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 insufficient power in the forced charging operation when the target power of the power purchase 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 in the daytime, the forced charging operation is performed in the nighttime power time zone, and the operation of the power converter 17 is stopped when the battery is fully charged, depending on the timer setting. .. Further, in FIG. 6, the target power of the power purchase power command value 23a during the minimum power purchase operation is set to 0 [kW], and the target power of the power purchase power command value 23a during the forced charging operation is 10 [kW] as an example. ] Is set.

During the minimum power purchase operation, the remaining battery capacity of the storage battery 3 increases due to surplus charging in the surplus power state where solar power generation increases in the daytime, and the storage battery 3 is discharged in the insufficient power state at night. Battery capacity is reduced.

In the nighttime power hours when the electricity bill of the electric power company is low, the forced charging operation is started by setting the timer. As a result, the storage battery 3 is forcibly charged so as to approach the target power of the power purchase power command value 23a. However, when the outputable charge value of the power converter 17 is equal to or less than the target power, the outputable charge value is limited.

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

The charging / discharging device 1 according to the present embodiment is made to solve the problems as described with reference to FIGS. 5 and 6. When the charging / discharging device 1 supplies the power of the storage battery 3 to the in-house load 4 in the night time zone, which is generally in a low load power state, the charging / discharging device 1 operates the power converter 17 so as not to use up the remaining battery capacity, and also operates at night. The power converter 17 is operated so that the storage battery 3 cannot be charged with the surplus power generated on the next day due to the storage battery 3 being fully charged by the power purchased during the time period.

FIG. 7 is a diagram showing an example of one-day operation of the minimum power purchase operation executed by the charging / discharging 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 power purchase command value is shown. Further, the upper side of FIG. 7 shows the relationship between the surplus power at the time of the minimum power purchase operation and the power purchase power command value. The lower side of FIG. 7 shows the change in the remaining battery capacity when the minimum power purchase operation is continuously performed for one day.

The surplus power or 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 insufficient power when the target power of the power purchase power command value 23a is dynamically set to the value selected by the power purchase power command value setting unit 23 is indicated by a combination of a dotted line and a triangle “△”. ..

In the charging / discharging device 1 according to the embodiment, the target power of the power purchase 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. Is dynamically set to the value selected by the power purchase power command value setting unit 23. A specific example of the setting method will be described. A setting table is recorded in advance in the power purchase 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 power purchase power command value 23a corresponding to the target power value corresponding to the plurality of times, and the power purchase 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 power purchase power command value setting unit 23 sets the target power corresponding to each time in the nighttime power time zone to the power purchase power command. Output as the value 23a.

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

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 and the remaining battery capacity of the storage battery 3 decreases. ..

In the nighttime power hours when the electricity bill of the electric power company is low, when the power consumption of the home load 4 is a 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 Consumption increases. Therefore, the charging / discharging device 1 does not supply power to the in-house load 4 by the storage battery 3, but follows the surplus power or the insufficient power. That is, the charging / discharging device 1 supplies the purchased electric 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 to obtain the remaining battery capacity. It works so as not to use up. As a result, the remaining battery capacity in the nighttime power time zone of FIG. 7 is maintained at a value close to 50%.

FIG. 8 is a diagram showing an example of one-day operation of the minimum power purchase operation and the forced charge operation executed by the charging / discharging device according to the embodiment. The upper part of FIG. 8 shows the relationship between the surplus power and the power purchase command value when the minimum power purchase 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 power purchase command value when the forced charging operation and the minimum power purchase operation are performed during the nighttime power time zone. The lower side of FIG. 8 shows the change 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 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 insufficient power when the target power of the power purchase 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 insufficient power in the forced charging operation when the target power of the power purchase power command value 23a is set to 10 [kW] is indicated by a combination of a dotted line and a square “□”.

In FIG. 8, according to the timer setting, the minimum power purchase operation is performed in the daytime, and the minimum power purchase operation and the forced charging operation are performed during the nighttime power time zone. The operation during the minimum power purchase operation is the same as the operation described with reference to FIG. 7. Forced charging operation is set at night when the electricity bill is cheap. The target power of the power purchase power command value 23a in this case is selected by the power purchase power command value setting unit 23 of FIG. 1, and the target power is multiplied by a weight coefficient of meteorological data of 10 [kW] (Max.). The value β [kW] is set.

The power purchase 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 meteorological 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 coefficient is set such that the numerical value is low when the weather is bad the next day and the numerical value is high when the weather is good. For example, when the weighting coefficient is a small value of "0" to "1", if the weather is bad the next day, it cannot be expected that the surplus power from the photovoltaic power generation system 7 will be charged to the storage battery 3, so the remaining battery capacity Is a value near "1" so that is higher than usual. Further, when the weather on the next day is good, it can be expected that the surplus power from the photovoltaic power generation system 7 will be charged to the storage battery 3, so that the value will be around "0" so that the remaining battery capacity will be lower than usual. However, since the efficiency of the power converter 17 decreases in low load charging, the power converter 17 operates so as to be limited by α [kW]. The lower right graph of FIG. 8 shows the relationship between the weighting coefficient set in this way and the target power of the power purchase power command value 23a.

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

Next, the power purchase power command value setting unit 23 obtains the power purchase power command value 23a (S3). As described in FIG. 7, the target value of the selection condition at the time of the minimum power purchase operation is 0 [kW] except during the nighttime power time zone. Further, in the nighttime power time zone and when the load output is low (insufficient power is 0 to α [kW]), the target value is surplus power or power that follows the insufficient power. Further, in the case of nighttime power time zone and normal load output (α [kW] or more), 0 [kW] is the target value.

As described in FIG. 8, the selection condition during the forced charging operation is 10 [kW] (Max.) As the target value except during the nighttime power time zone, and 10 [kW] (10 [kW]) during the nighttime power time zone. The target value is β [kW], which is the value obtained by multiplying Max.) By the weighting coefficient of the meteorological data.

Next, the differencer 20 obtains the difference between the purchased power or the sold power detected by the received power detector 11 and the power purchased power command value 23a (S4). The power purchase power control unit 22 obtains a target charge / discharge power command value 22a according to this difference (S5), and the power purchase power control unit 22 outputs the charge / discharge current of the power converter 17 so that the difference becomes 0. (S7). The reverse tide power detector 13 monitors the reverse tide power so that it does not flow out to the commercial system 5, and when the reverse tide occurs, the reverse tide power control unit 21 corrects the target charge / discharge power command value 22a so that the reverse tide does not occur ( S6). When the operation of the power converter 17 is not stopped as a result of the charge / discharge current control in S7 (steps S8, No), the control unit 18 returns to the process of S1 and stops the operation of the power converter 17 (step S8, No.). Yes), the control unit 18 ends the process.

As described above, according to the charging / discharging device 1 according to the embodiment, the power consumption of the in-house load is low (insufficient) in the case of the minimum power purchase operation during the nighttime power hours when the electricity bill of the electric power company is low. When the power is 0 to α [kW]), the power conversion efficiency is poor and the remaining battery capacity is greatly reduced. Therefore, at the time of low load output, power is not supplied, and it operates so as to cover the in-house load by following the surplus (insufficient) power, that is, by purchasing power. Further, when the power consumption of the in-house load is a normal load output (α [kW] or more), the power conversion efficiency is good, so that the in-house load is covered by power supply. Since the remaining battery capacity per day operates so as not to be used up with respect to the original remaining battery capacity, there is an effect that efficient charging / discharging can be performed within the range of the battery capacity without stopping the minimum power purchase operation due to over-discharging. is there.

Further, in the case of forced charging operation in the nighttime power time zone when the electricity cost of the electric power company is low, the target power of the power purchase power command value operates so as to be set to a value multiplied by the weight coefficient of the meteorological data. If the weather is bad the next day, it cannot be expected that the surplus power from the photovoltaic power generation system will be charged to the in-vehicle battery for driving, so the battery will operate so that the remaining capacity is higher than usual, and the weather on the next day will be In a good case, it can be expected that the surplus electric power generated by the photovoltaic power generation system is charged to the in-vehicle battery for driving, so that the remaining battery capacity is operated to be lower than usual. Therefore, there is an effect that the surplus power can be charged more on the next day.

In the description of this embodiment, an example in which the storage battery 3 mounted on the EV 2 is used has been described, but the storage battery 3 has the same effect even if a stationary storage battery is used.

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

1 Charge / discharge device, 2a Charge / discharge connector cable, 3 Storage battery, 4 Home load, 5 Commercial system, 6 Solar cell array, 7 Solar power generation system, 11 Power received power detector, 11a Power purchase power value, 12 Solar power generation power Detector, 13 reverse tide power detector, 14 self-sustaining disconnector, 15 charge / discharge power detector, 16 interconnection disconnector, 17 power converter, 18 control unit, 20 differential unit, 21 reverse tide 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 Nighttime power time zone data, 26 Current time data, 27 Meteorological data , 28 storage unit, 30 display operation remote control, 31 cloud server, 41 first electric wire, 42 second electric wire, 43 third electric wire, 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 it to the storage battery.
A first power detector that detects the power value of the AC power supplied from the commercial system and the AC power supplied to the commercial system , and
A second power detector that detects the generated power,
A third power detector that detects the AC power output from the power converter, and
Based on the amount of power detected by each of the first to third power detectors, the power converter generates a target charge / discharge power command value that specifies a target power value when charging / discharging the storage battery. It is equipped with a control unit that outputs to the power converter.
The control unit
The amount of power detected by each of the first to third power detectors, the nighttime power time zone data indicating the nighttime power time zone in which the amount of power purchased from the commercial system is the cheapest in the day, and the current time. Based on the data and the weather data, the power purchase command value setting unit that sets the power purchase command value, which is the target value of the power purchase amount, and the power purchase command value setting unit.
By generating the target charge / discharge power command value based on the difference between the power purchase command value and the power purchase power value at the time of power purchase detected by the first power detector, the power purchase time A power purchase power control unit that controls the power converter,
A charging / discharging device characterized by being equipped with. The power purchase power command value setting unit is 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 charging / discharging device according to claim 1, wherein a command value is set. The power purchase power command value setting unit is set to have a low power consumption state in the home load when the output power value of the power converter becomes equal to or less than a specific power value in the nighttime power time zone. ,
The power purchase command value setting unit is characterized in that when the power converter operates in the low power consumption state, the power purchase power command value is set so as to suppress discharge from the storage battery. Or the charging / discharging device according to 2. The charging / discharging device according to claim 3, wherein the specific power value is a power value determined by the conversion efficiency of the power converter. The power purchase power command value setting unit sets the power purchase power command value by using the solar radiation amount predicted value obtained from the weather data in the forced charging for charging the storage battery during the nighttime power time zone. The charging / discharging device according to claim 1 or 2. The charging / discharging device according to claim 5, wherein the power purchase command value setting unit uses the predicted value of the amount of solar radiation indicating the amount of solar radiation of the next day.

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