WO2021149395A1

WO2021149395A1 - Power conditioner

Info

Publication number: WO2021149395A1
Application number: PCT/JP2020/046483
Authority: WO
Inventors: 祐樹石倉; 寛幸安井; 浩平柴田
Original assignee: 株式会社村田製作所
Priority date: 2020-01-22
Filing date: 2020-12-14
Publication date: 2021-07-29
Also published as: JP7243869B2; JPWO2021149395A1

Abstract

The present disclosure provides a power conditioner making it possible to efficiently make use of energy generated by a solar panel. The power conditioner (12) is provided with: a PV converter (21) for converting power generated by a solar panel (11) and outputting the converted power to a DC high-voltage bus (30); an inverter (22) for converting the power of the DC high-voltage bus (30) to AC power and outputting the AC power to a system power line (13); a storage battery (28) capable of both charging from and discharging to the DC high-voltage bus (30); and a control unit (29) for controlling the PV converter (21) and the inverter (22) and controlling the charging current to the storage battery (28). The control unit (29) charges the storage battery (28) with the charging current having a first current value when the electricity storage amount of the storage battery (28) is less than a first threshold value, and charges the storage battery (28) with the charging current having a second current value greater than the first current value when the electricity storage amount is greater than or equal to the first threshold value.

Description

Power conditioner

This disclosure relates to a power conditioner.

Conventionally, a photovoltaic power generation system is installed in a general household, for example, and is equipped with a power conditioner that converts the power generated by the solar panel into AC power and outputs it. Further, the power conditioner having a storage battery charges the storage battery with surplus power, converts the power stored in the storage battery into AC power during the time when the solar panel does not generate power, and outputs the power (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2018-098820

By the way, the internal resistance value of a storage battery changes depending on the amount of charge (storage amount), and a loss occurs according to the internal resistance value. When charging in a region where the internal resistance value is high, there is a problem that the energy generated by the solar panel cannot be efficiently used.

The purpose of this disclosure is to provide a power conditioner that enables efficient use of energy generated by solar panels.

The power conditioner, which is one aspect of the present disclosure, is a PV converter that converts the generated power of the solar panel and outputs it to the DC high-voltage bus, and converts the power of the DC high-pressure bus into AC power and outputs it to the grid power line. The control unit includes an inverter, a storage battery capable of charging and discharging the DC high-pressure bus, and a control unit that controls the PV converter and the inverter and also controls the charging current to the storage battery. When the stored amount of the storage battery is less than the first threshold value, the storage battery is charged with the charging current of the first current value, and when the stored amount is equal to or more than the first threshold value, the second current value larger than the first current value is used. The storage battery is charged with the charging current of.

According to this configuration, when the storage amount of the storage battery is less than the first threshold value, the charging current for the storage battery is set as the first current value, so that the internal resistance loss due to the internal resistance of the storage battery is reduced and the power generated by the solar panel is reduced. In other words, the energy generated by the solar panel can be used efficiently.

In the power conditioner, the control unit ends the surplus power during the period in which the surplus power of the difference between the generated power of the solar panel and the power consumption of the electric device operating by the AC power is generated. It is preferable to control the charging current so that the storage battery is fully charged according to the timing of charging.

According to this configuration, when the generated power of the solar panel is smaller than the power consumption of the electric device and the discharge power from the rechargeable battery is required, the storage battery is fully charged, so that the discharge due to natural discharge is small. The stored power of the storage battery can be used efficiently.

In the above power conditioner, the control unit charges the storage battery with a charging current having a third current value smaller than the second current value when the amount of electricity stored is greater than or equal to the second threshold value larger than the first threshold value. At the same time, the storage battery is fully charged at the timing when the surplus power ends during the period in which the surplus power of the difference between the generated power of the solar panel and the power consumption of the electric device operating by the AC power is generated. It is preferable to set the third current value so as to be.

In the above power conditioner, the control unit makes the generated power smaller than the power consumption during the period in which the surplus power is generated based on the position data and the date data of the installation location of the power conditioner. It is preferable to obtain the generation end time at which the surplus power ends and control the charging current so that the storage battery is fully charged at the generation end time.

According to this configuration, the storage battery can be fully charged when the discharge power is required according to the installation position of the solar panel and the power conditioner, and the stored power of the storage battery can be efficiently used.

In the above power conditioner, it is preferable that the control unit receives the weather data of the installation location from the outside and controls the charging current based on the weather data.

According to this configuration, the influence of the weather at the installation location can be reduced.

In the above power conditioner, it is preferable that the control unit detects fluctuations in power consumption by the electric device operating on the AC power and controls the charging current according to the load.

In the above power conditioner, it is preferable that the control unit detects fluctuations in power consumption by the electric device operating on the AC power and controls the inverter so as to maintain the charging current.

In the above power conditioner, it is preferable that the control unit acquires the temperature of the storage battery and does not supply the charging current to the storage battery when the temperature is lower than the predetermined temperature.

Further, the power conditioner of another disclosure is a PV converter that converts the generated power of the solar panel and outputs it to the DC high-pressure bus, and an inverter that converts the power of the DC high-pressure bus into AC power and outputs it to the grid power line. The control unit includes a storage battery capable of charging and discharging the DC high-pressure bus, and a control unit that controls the PV converter and the inverter and also controls the charging current to the storage battery. The storage battery is charged with the charging current of a predetermined value, and when the stored amount of the storage battery exceeds a predetermined value, the storage battery is charged with a charging voltage of a predetermined value, and a constant current constant voltage control is performed, and the solar panel is used. During the period in which surplus power is generated, which is the difference between the generated power of the electric device and the power consumption of the electric device, the predetermined value of the charging current is set so as to fully charge the storage battery at the timing when the surplus power ends. Set.

According to this configuration, when the generated power of the solar panel is smaller than the power consumption of the electric device and the discharge power from the rechargeable battery is required, the storage battery is fully charged, so that the discharge due to natural discharge is small. The stored power of the storage battery can be used efficiently. Further, since the charging current set in this way is smaller than the charging current according to the rating of the storage battery, the internal resistance loss due to the internal resistance of the storage battery can be reduced, and the energy generated by the solar panel can be efficiently utilized. ..

The power conditioner includes a bidirectional DC-DC converter connected between the DC high-pressure bus and the storage battery, and the control unit controls the bidirectional DC-DC converter to control the storage battery. It is preferable to control the charging current.

According to this configuration, the charging current for the storage battery can be easily controlled by controlling the bidirectional DC-DC converter.

In the power conditioner, the storage battery is directly connected to the DC high-pressure bus, the grid power line is connected to an electric device that consumes the AC power, and the storage battery is the power generated by the solar panel and the power generated by the solar panel. It is preferable that the charging current is charged by the surplus power of the difference from the power consumption of the electric device, and the control unit controls the inverter to control the charging current.

According to this configuration, the charging current for the storage battery can be easily controlled by controlling the inverter.

According to one aspect of the present disclosure, it is possible to provide a power conditioner that enables efficient utilization of energy generated by a solar panel.

Block circuit diagram of the power conditioner. The waveform diagram which shows the power generation amount, the load amount, and the electricity storage amount of 1st Embodiment. The waveform diagram which shows the power generation amount, the load amount, and the electricity storage amount of 1st Embodiment. The waveform diagram which shows the power generation amount, the load amount, and the electricity storage amount of 1st Embodiment. A characteristic diagram showing the relationship between the amount of electricity stored and the internal resistance. A characteristic diagram showing the relationship between temperature and internal resistance. The waveform diagram which shows the power generation amount, the load amount, and the electricity storage amount of the 2nd Embodiment. A block circuit diagram showing a power conditioner of a modified example.

(First Embodiment)
Hereinafter, the first embodiment will be described.

As shown in FIG. 1, the photovoltaic power generation system 10 of the present embodiment has a solar panel 11 and a power conditioner 12 connected to the solar panel 11. The photovoltaic power generation system 10 is installed in, for example, a general household. The power conditioner 12 is connected to a system power line 13 of a general household via a distribution board or the like (not shown), and the system power line 13 is connected to a commercial power system 14. The commercial power system 14 is a power distribution system through which an electric power company transmits electric power. An electric device (simply referred to as "device") 15 is connected to the grid power line 13 as an indoor load. The electric device 15 is connected to a power line laid indoors or an outlet installed indoors via a distribution board. The electric device 15 is, for example, an electric device such as a lighting, a television, a refrigerator, a washing machine, an air conditioner, a microwave oven, and the like. The photovoltaic power generation system 10 may be installed in a commercial facility, a factory, or the like.

The power conditioner 12 converts the DC power generated by the solar panel 11 into AC power and outputs it. Then, the power conditioner 12 interconnects or disconnects the solar panel 11 and the commercial power system 14.

The power conditioner 12 includes a PV converter 21, an inverter 22, a filter 23, a grid interconnection relay (simply referred to as “relay”) 24, a DC-DC converter 25, a rectifier 26, a bidirectional DC-DC converter 27, and a storage battery 28. It has a control unit 29. The PV converter 21 and the inverter 22 are connected to each other via a DC high voltage bus 30.

The PV converter 21 is a step-up chopper circuit controlled by the control unit 29, and includes a smoothing capacitor. The PV converter 21 boosts and smoothes the DC voltage input from the solar panel 11 and outputs it to the DC high-voltage bus 30. The PV converter 21 includes a switching element. The control unit 29 adjusts the pulse width of the control signal that turns on and off the switching element of the PV converter 21 by, for example, a pulse width modulation (PWM) method. Then, the control unit 29 controls the PV converter 21 so that the desired output power is output from the PV converter 21 to the DC high-voltage bus 30.

The inverter 22 is a DC / AC conversion circuit that operates by a control signal from the control unit 29. The inverter 22 converts the DC power of the DC high-voltage bus 30 into AC power that can be connected to the commercial power system 14. The converted AC power is output to the grid power line 13 via the filter 23 and the grid interconnection relay 24. The inverter 22 includes a switching element. The control unit 29 outputs a control signal having a frequency synchronized with the commercial power system 14, adjusts the pulse width of the control signal by, for example, a PWM method, and drives the switching element. The output power of the inverter 22 is changed depending on the pulse width of the control signal. That is, the control unit 29 controls the inverter 22 to output desired AC power from the inverter 22 to the system power line 13. Further, the inverter 22 converts the AC power of the commercial power system 14 into DC power and outputs it to the DC high-voltage bus 30. Similar to AC power, the control unit 29 controls on / off of a plurality of switching elements included in the inverter 22 by a control signal, and outputs desired DC power from the inverter 22 to the DC high-voltage bus 30. The filter 23 reduces the high frequency component of the AC power output from the inverter 22.

The DC-DC converter 25 is, for example, a step-down circuit and outputs the operating voltage of the control unit 29. The DC-DC converter 25 converts the DC voltage of the DC high-pressure bus 30 or the DC voltage supplied from the rectifier 26 into a DC voltage suitable for the operation of the control unit 29. The control unit 29 operates based on the DC voltage supplied from the DC-DC converter 25, and controls the PV converter 21, the inverter 22, and the grid interconnection relay 24. The grid interconnection relay 24 is, for example, a normally open electromagnetic relay, and the control unit 29 controls the closed state and the open state of the grid interconnection relay 24 by a control signal. The grid interconnection relay 24 connects and disconnects the grid power line 13, that is, the electric device 15, and the commercial power system 14 with respect to the inverter 22. The photovoltaic power generation system 10 is connected to the commercial power system 14 by the closing operation of the grid interconnection relay 24, and is disconnected by the opening operation of the grid interconnection relay 24.

The storage battery 28 of this embodiment is connected to the DC high-voltage bus 30 via a bidirectional DC-DC converter 27.

The storage battery 28 is a battery that can be charged and discharged. The storage battery 28 is, for example, a lithium ion battery.

The bidirectional DC-DC converter 27 is, for example, a buck-boost circuit that converts the DC power of the DC high-pressure bus 30 into DC power for charging the storage battery 28. Further, the bidirectional DC-DC converter 27 converts the DC power discharged from the storage battery 28 into DC power having a voltage corresponding to the DC high-voltage bus 30. The bidirectional DC-DC converter 27 includes a switching element. The control unit 29 outputs a control signal for driving the switching element on and off, and adjusts the pulse width of the control signal by, for example, a PWM method. When the switching element is turned on and off by the control signal, the bidirectional DC-DC converter 27 converts the DC power of the DC high-pressure bus 30 into the charging power of the storage battery 28, or converts the discharge power from the storage battery 28 into the DC high-pressure bus 30. Convert to DC power.

The storage battery 28 has a battery management unit (BMU: battery management unit) 28a. The battery management unit 28a calculates the amount of electricity stored in the storage battery 28. Further, the battery management unit 28a detects the temperature of the storage battery. The amount of electricity stored in the storage battery 28 is indicated by the SOC (State of Charge) of the storage battery 28. The amount of electricity stored in the storage battery 28 may be indicated by, for example, the voltage value between the terminals of the storage battery 28. The battery management unit 28a outputs a detection signal including the amount of electricity stored, the temperature, and the like.

The control unit 29 includes, for example, a CPU 31, a memory 32, and a peripheral circuit 33, which are connected to each other via an internal bus 34. The memory 32 includes a ROM and a RAM. The memory 32 stores a processing program executed by the CPU 31, various data required for processing, and various data temporarily stored by executing the processing program. The peripheral circuit 33 includes at least one circuit for operating the CPU 31. In the circuit included in the peripheral circuit 33, for example, a circuit that generates a clock signal for the operation of the control unit 29, a clock circuit that indicates the time, and detection signals of various sensors and storage batteries included in the power conditioner 12 are input. It includes an interface circuit, a communication circuit that communicates with the outside of the power conditioner 12 such as the Internet by wire or wirelessly, and the like. The CPU 31 directly accesses the peripheral circuit 33 to read the information (data) required for executing the processing program, or reads the information (data) stored in the memory 32 from the peripheral circuit 33. The information (data) stored in the memory 32 includes, for example, information stored in the memory 32 from an external terminal connected to the peripheral circuit 33.

The information (data) stored in the memory 32 includes the location information of the installation location of the photovoltaic power generation system 10, the date, the time, the device information of the solar panel 11, the device information of the storage battery 28, and the like. The device information of the solar panel 11 includes the maximum generated power according to the number of installed panels, and the like.

The control unit 29 controls the PV converter 21 and the inverter 22 so that the CPU 31 executes a processing program to output AC power to the grid power line 13 based on the generated power of the solar panel 11. Further, the control unit 29 charges the storage battery 28 based on the surplus power which is the difference between the generated power of the solar panel 11 and the power consumption of the electric device 15 connected to the grid power line 13. -Controls the DC converter 27, the PV converter 21, and the inverter 22. Further, the bidirectional DC-DC converter 27 and the inverter 22 are used so that the AC power based on the discharge power of the storage battery 28 is output to the grid power line 13 when the power consumption of the electric device 15 exceeds the power generated by the solar panel 11. Control.

The generated power of the solar panel 11 can be calculated from the input voltage and input current of the PV converter 21. The control unit 29 calculates the generated power of the solar panel 11 based on the input voltage and the input current detected by the voltage sensor 41 and the current sensor 42 provided on the input side of the PV converter 21. A voltage sensor and a current sensor may be provided on the output side of the PV converter 21, and the generated power of the solar panel 11 may be calculated from the output voltage and the output current of the PV converter 21. Regarding the power consumption of the electric device 51, for example, a power sensor 51 is provided on a distribution board (not shown) to which the electric device 15 is connected, and the power consumption can be obtained by the amount of power detected by the power sensor 51.

The charge control for the storage battery 28 will be described in detail.

As described above, the control unit 29 charges the storage battery 28 based on the surplus electric power. The surplus power is generated when the generated power of the solar panel 11 is larger than the power consumption of the electric device 15. The solar panel 11 starts power generation at sunrise and ends power generation at sunset. The control unit 29 controls the bidirectional DC-DC converter 27 and the like so as to charge the storage battery 28 based on the surplus electric power between the sunrise time and the sunset time.

The upper part of FIG. 2 shows an example of changes in the generated power L31 and the power consumption L32 in one day (24 hours). The time Ts at which the generated power L31 of the solar panel 11 that has started power generation becomes larger than the power consumption L32 is defined as the generation start time at which surplus power is generated, and the time Te at which the generated power L31 is smaller than the power consumption L32 is defined as the generation end time. do.

The control unit 29 performs charge control for charging the storage battery 28 during the period from the generation start time Ts to the generation end time Te. For example, the control unit 29 charges the storage battery 28 by a constant current constant voltage charging (CCCV) method that manages the charging current and the charging voltage of the storage battery 28. Further, the control unit 29 adjusts the charging current based on the stored amount of the storage battery 28 in the period of supplying the managed charging current to the storage battery 28. The charging current and charging voltage for the storage battery 28 can be obtained, for example, by a current sensor 43 and a voltage sensor 44 provided between the bidirectional DC-DC converter 27 and the storage battery 28.

More specifically, the control unit 29 acquires the amount of electricity stored from the storage battery 28. In the present embodiment, the amount of electricity stored is a percentage indicated by the SOC of the storage battery 28. The control unit 29 charges the storage battery 28 with a charging current of less than a predetermined value when the SOC is less than a predetermined value, and charges the storage battery 28 with a charging current of a predetermined value or more when the SOC is a predetermined value or more. Controls the DC-DC converter 27. A predetermined value for comparing SOCs is stored in the memory 32 of the control unit 29 as, for example, a first threshold value. The first threshold value is set according to the internal resistance of the storage battery 28. In a lithium ion battery, the value of internal resistance changes according to the amount of electricity stored and the temperature. 5 and 6 show the relationship between SOC (storage amount), internal resistance, and temperature in a lithium ion battery. In FIG. 5, the horizontal axis is the SOC and the vertical axis is the value of the internal resistance. The characteristic lines L11, L12, and L13 shown in FIG. 5 show the characteristics when the temperature of the storage battery 28 is high in this order. In FIG. 6, the horizontal axis represents the temperature and the vertical axis represents the value of the internal resistance. The characteristic lines L21, L22, L23, and L24 shown in FIG. 6 show the characteristics when the SOC is high in this order.

In the characteristic line L11 of FIG. 5, the internal resistance of the storage battery 28 increases sharply as the SOC decreases at a predetermined temperature. At the temperature of the characteristic line L11, the internal resistance is large in the range where the SOC is low. The loss due to the internal resistance of the storage battery 28 is “internal resistance value × current squared”. Therefore, the control unit 29 acquires the SOC of the storage battery 28 and sets the charging current of the storage battery 28 to less than a predetermined value in the range where the SOC is low. In the present embodiment, the low SOC range is defined as, for example, "less than 30%". That is, the first threshold value is set to "30%".

Further, the control unit 29 sets a value smaller than 1C of the storage battery 28, for example 0.2C, as a predetermined value, and sets a value less than this predetermined value (first current value, for example 0.1C) as the value of the charging current. 1C is a current value at which the discharge ends in 1 hour when a cell having a capacity of a nominal capacity value is discharged with a constant current.

The lower part of FIG. 2 shows the SOC curve L33 in the charge control according to the present embodiment and the SOC curve L34 of the comparative example.

As shown in the lower part of FIG. 2, when the SOC is less than the first threshold value, the control unit 29 sets the current value less than the predetermined value as the first current value (for example, 0.1C) smaller than the predetermined value, and sets the first current value. The bidirectional DC-DC converter 27 is controlled so as to charge the storage battery 28 with a value charging current. By reducing the current value of the charging current, the internal resistance loss during charging can be reduced. Further, by reducing the current value of the charging current, the amount of heat generated by the storage battery 28 can be reduced.

Then, when the SOC becomes equal to or higher than the first threshold value “30%”, the control unit 29 charges the storage battery 28 with a charging current having a second current value (for example, 0.25C) larger than a predetermined value. Controls the DC converter 27.

When the voltage between the terminals of the storage battery 28 becomes equal to the rated voltage value of the storage battery 28, the control unit 29 controls the charging current so that the voltage between the terminals of the storage battery 28 becomes a constant voltage. The charging current is an output current from the bidirectional DC-DC converter 27 toward the storage battery 28. The control unit 29 controls the charging current by controlling the bidirectional DC-DC converter 27. By this constant voltage charging, the SOC of the storage battery 28 gradually increases, and the battery becomes fully charged (SOC = 100%).

In the present embodiment, the control unit 29 controls the charging current so that the storage battery 28 is fully charged by the above-mentioned generation end time Te. It is preferable to control the charging current so that the storage battery 28 is fully charged at the generation end time Te. The storage battery 28 may be fully charged at the generation end time Te, and may be fully charged within a range from the generation end time Te to a predetermined time (for example, about 30 minutes) before.

In this case, as shown in FIG. 2, when the SOC of the storage battery 28 becomes equal to or higher than the second threshold value (for example, 70%) larger than the first threshold value, the current amount of the charging current is controlled. For example, the control unit 29 calculates the time between the time T11 at which the SOC becomes the second threshold and the generation end time Te, and sets the charging current to a third current value smaller than the second current value according to the time. The bidirectional DC-DC converter 27 is controlled in this way. By supplying the charging current of the third current value to the storage battery 28, the amount of heat generated in the storage battery 28 can be suppressed. Further, by fully charging the storage battery 28 at the generation end time Te, the storage battery 28 can be efficiently used.

The SOC curve L34 of the comparative example shown in the lower part of FIG. 2 shows the case where the storage battery is charged with a charging current of 0.25C. In general, a storage battery is often charged with a charging current having a value corresponding to the rating so that the storage battery is fully charged within a predetermined charging time. In this case, the storage battery 28 is fully charged at a time considerably earlier than the time when the generated power L31 becomes lower than the power consumption L32 (generation end time Te). The amount of electricity stored in the storage battery 28 decreases due to natural discharge. In the photovoltaic power generation system, there is an advantage in using the electric device 15 by the discharge power from the storage battery 28 when the electric device 15 cannot be used due to the power generated by the solar panel 11. Therefore, as in the comparative example, when the battery is fully charged at a time considerably earlier than the generation end time Te, the storage amount of the storage battery decreases due to natural discharge at the generation end time Te, and electricity is charged only for a time corresponding to the storage amount. The device 15 cannot be used. On the other hand, in the present embodiment, since the storage battery 28 is fully charged at the generation end time Te, the usage time of the electric device 15 is longer than that of the comparative example because the amount of stored electricity does not decrease. That is, in the photovoltaic power generation system 10 of the present embodiment, the storage battery 28 can be used more efficiently.

The SOC of the storage battery 28 is reduced by the use of the electric device 15, that is, the power consumption indicated by the power consumption L32, and is in a completely discharged state. The completely discharged state of the storage battery 28 is a state in which the SOC is 0 (%) or close to 0 (%). In the example shown in FIG. 2, the storage battery 28 is in a completely discharged state at 24:00. Therefore, the storage battery 28 is charged from the completely discharged state by the generated power of the solar panel 11 on the next day.

[Period when surplus power is generated]
As described above, the period in which the surplus power is generated is a period in which the generated power L31 of the solar panel 11 is larger than the power consumption L32 of the electric device 15, and is from a time later than the sunrise time (generation start time Ts). It is until the time earlier than sunset (occurrence end time Te). The sunrise time and the sunset time differ from the standard time depending on the installation location (for example, longitude) of the photovoltaic power generation system 10, the season, and the like. Therefore, the control unit 29 calculates the generation start time and the generation end time based on the position data, the date data, and the power consumption data related to the installation location. For the position data, for example, the latitude and longitude of the installation location of the photovoltaic power generation system 10 can be calculated by including the GPS (Global Positioning System) receiver in the peripheral circuit 33. Further, when the photovoltaic power generation system 10 is installed, it may be set in the memory 32 from an external terminal owned by the operator.

The date data is stored in the memory 32 as a calendar. As the current time, a clock circuit included in the peripheral circuit 33, a time calculated based on a radio wave received by a GPS receiver, a time received by the Internet, or the like can be used.

The control unit 29 obtains the time when the solar panel 11 starts power generation and the time when the power generation ends based on the position data and the date data. As the power consumption data, the data of the average household power consumption can be used as the power consumption data. Further, the power consumption data may be corrected depending on the type and number of the electric devices 15 installed in the home where the photovoltaic power generation system is installed. Further, the power consumption data for each day of the week may be stored in the memory 32 based on the date data. Further, the standard power consumption data and the correction data according to the date and the day may be stored in the memory 32, and the power consumption data for the day may be calculated from the standard power consumption data and the correction data. ..

The control unit 29 calculates the generation start time Ts and the generation end time Te based on the power generation start time, the power generation end time, and the power consumption data. Then, the control unit 29 sets the above-mentioned first current value, second current value, and third current value. For example, since the outside air temperature is lower and the temperature of the storage battery 28 is lower in winter than in summer, the internal resistance value is higher. Therefore, the internal resistance loss can be reduced by reducing the first current value in winter as compared with summer. Further, in the summer, the time from the occurrence start time Ts to the occurrence end time Te is longer than in the winter. Therefore, by making the second current value smaller than the above-mentioned 1C, the calorific value of the storage battery 28 can be suppressed. When the temperature of the storage battery 28 is equal to or lower than a predetermined value (for example, 10 ° C.), the control unit 29 controls the bidirectional DC-DC converter 27 so as not to supply the charging current to the storage battery 28. Thereby, the influence on the storage battery 28 at a low temperature can be reduced.

The generated power in the solar panel 11 differs depending on the season and the weather, and the generation start time Ts and the generation end time Te change. Therefore, the control unit 29 acquires the weather data related to the installation location, for example, via the Internet. The control unit 29 calculates the occurrence start time Ts and the occurrence end time Te based on the weather data. Then, the control unit 29 can fully charge the storage battery by setting the above-mentioned first current value, second current value, and third current value.

[Fluctuation of power consumption]
The control unit 29 can also control the charging current for the storage battery 28 based on the amount of power consumed by the electric device 15. As shown in FIG. 3, the power consumption of the electric device 15 may temporarily fluctuate with respect to the average power consumption data. Due to the temporary increase in power consumption, the surplus power is reduced. In this case, the control unit 29 reduces the charging current for the storage battery 28 to cope with the temporary increase in power consumption. As a result, the increase in SOC becomes moderate. Then, when the timing when the SOC becomes equal to or higher than the second threshold value or the temporary increase in power consumption disappears, the control unit 29 controls the third current value, for example, by increasing the number as compared with the example shown in FIG. , The storage battery 28 can be fully charged by the generation end time Te.

Further, the control unit 29 may control the inverter 22 so as to maintain the charging current when the surplus power is reduced due to a temporary increase in power consumption. That is, in order to maintain the charging current, the alternating current supplied from the power conditioner 12 to the system power line 13 may be reduced. As a result, even if the power consumption temporarily increases, it is possible to suppress a decrease in the charging capacity.

[Fluctuation of generated power]
The power generated by the solar panel 11 changes depending on the amount of solar radiation. For example, thick clouds that do not easily allow sunlight to pass through may block sunlight on the solar panel 11. In this case, as shown in FIG. 4, the amount of power generation is temporarily reduced, and the surplus power is reduced. In this case, the control unit 29 reduces the charging current for the storage battery 28 to secure the AC power to be supplied to the system power line 13. As a result, the increase in SOC becomes moderate. Then, the control unit 29 controls the third current value, for example, by increasing the number as compared with the example shown in FIG. 2, the storage battery 28 can be fully charged by the generation end time Te.

As described above, according to the present embodiment, the following effects are obtained.

(1-1) The power conditioner 12 is a PV converter 21 that converts the generated power of the solar panel 11 and outputs it to the DC high-pressure bus 30, and a grid power line 13 that converts the power of the DC high-pressure bus 30 into AC power. The inverter 22, the storage battery 28 capable of charging and discharging the DC high-pressure bus 30, and the control unit 29 that controls the PV converter 21 and the inverter 22 and controls the charging current to the storage battery 28. Be prepared. When the stored amount of the storage battery 28 is less than the first threshold value, the control unit 29 charges the storage battery 28 with the charging current of the first current value, and when the stored amount is equal to or more than the first threshold value, the second is larger than the first current value. The storage battery 28 is charged with the charging current of the current value. According to this configuration, when the storage amount of the storage battery 28 is less than the first threshold value, the charging current for the storage battery 28 is set as the first current value, thereby reducing the internal resistance loss due to the internal resistance of the storage battery 28 and the solar panel. The energy generated by the above can be used efficiently.

(1-2) The control unit 29 fully charges the storage battery 28 at the timing when the surplus power is generated, which is the difference between the generated power of the solar panel and the power consumption of the electric device 15. The charging current is controlled so as to. According to this configuration, when the power generated by the solar panel is smaller than the power consumed by the electric device 15 and the discharge power from the rechargeable battery is required, the storage battery 28 is fully charged, so that the discharge due to natural discharge occurs. The amount of electricity stored in the storage battery 28 can be efficiently used.

(1-3) When the amount of electricity stored is equal to or greater than the second threshold value, the control unit 29 charges the storage battery 28 with the charging current of the third current value, and also determines the power generated by the solar panel and the power consumed by the electric device 15. The third current value is set so that the storage battery 28 is fully charged at the timing when the surplus power ends in the period during which the surplus power is generated. According to this configuration, when the power generated by the solar panel is smaller than the power consumed by the electric device 15 and the discharge power from the rechargeable battery is required, the storage battery 28 is fully charged, so that the discharge due to natural discharge occurs. The amount of electricity stored in the storage battery 28 can be efficiently used.

(1-4) In the control unit 29, the power generated by the solar panel is larger than the power consumed by the electric device 15 as the period during which the surplus power is generated based on the position data and the date data of the installation location of the power conditioner. The generation start time when the surplus power is generated and the generation end time when the generated power becomes smaller than the power consumption and the surplus power ends are obtained, and the charging current is controlled so that the storage battery 28 is fully charged at the generation end time. According to this configuration, the storage battery 28 can be fully charged when the discharge power is required according to the installation position of the solar panel and the power conditioner, and the stored power of the storage battery 28 can be efficiently used.

(1-5) The control unit 29 receives the weather data of the installation location from the outside and controls the charging current based on the weather data. According to this configuration, the influence of the weather at the installation location can be reduced.

(Second Embodiment)
Hereinafter, the second embodiment will be described.

In this second embodiment, the control of the charging current by the control unit 29 is different from that in the first embodiment. Therefore, the description of the components in the second embodiment will be omitted, and the control of the charging current by the control unit 29 will be described.

The control unit 29 keeps the charging current constant in the constant current control for the storage battery 28, and fully charges the storage battery 28 at the generation end time Te based on the generation start time Ts and the generation end time Te (SOC = 100%). One current value is calculated so as to be. The control unit 29 controls the bidirectional DC-DC converter 27 so as to supply the charging current of one calculated current value to the storage battery 28. As a result, as shown in the lower part of FIG. 7, the SOC curve L33 in the present embodiment rises with a constant slope, and then becomes 100 [%] at the generation end time Te by constant voltage control. Therefore, by fully charging the storage battery 28 at the generation end time Te, the storage voltage of the storage battery 28 can be efficiently used.

Further, the current value of the charging current supplied to the storage battery 28 has a gentler slope than the SOC curve L34 of the comparative example, and the current value of the charging current is smaller than that of the comparative example. Therefore, the internal resistance loss at the start of charging the storage battery 28 in the completely discharged state can be reduced. Further, since the current value of the charging current is smaller than that in the case of charging with the charging current according to the rating, the amount of heat generated by the storage battery 28 can be reduced.

(2-1) The control unit 29 of the present embodiment keeps the charging current constant in the constant current control for the storage battery 28, and at the storage battery 28 at the generation end time Te based on the generation start time Ts and the generation end time Te. Is calculated as one current value so as to be fully charged (SOC = 100%). In this way, by fully charging the storage battery 28 at the generation end time Te, the storage voltage of the storage battery 28 can be efficiently used.

(2-2) The current value of the charging current supplied to the storage battery 28 has a gentler slope than the SOC curve L34 of the comparative example, and the current value of the charging current is smaller than that of the comparative example. Therefore, the internal resistance loss at the start of charging the storage battery 28 in the completely discharged state can be reduced. Further, since the current value of the charging current is smaller than that in the case of charging with the charging current according to the rating, the amount of heat generated by the storage battery 28 can be reduced.

(Change example)
In addition, each of the above-mentioned embodiments may be carried out in the following embodiments. Each of the above embodiments and the following modified examples can be implemented in combination with each other within a technically consistent range.

-As shown in FIG. 8, the storage battery 28 may be directly connected to the DC high-voltage bus 30. In this case, the bidirectional DC-DC converter 27 shown in FIG. 1 is omitted. The charging current for the storage battery 28 can be controlled by the difference between the output power of the PV converter 21 and the output power of the inverter 22. That is, the control unit 29 controls at least the inverter 22 of the PV converter 21 and the inverter 22 so as to supply the same charging current to the storage battery 28 as in the above embodiment.

-An external storage battery may be connected to the power conditioner 12. The control unit 29 may detect the presence or absence of an external storage battery and control the charging current for the external storage battery based on the SOC of the external storage battery.

-In each of the above embodiments, the current value of the charging current is set by the generation start time Ts and the generation end time Te, but the current value of the charging current may be set by other times. For example, the charging start time and the charging end time may be a time instructing the start of charging, a time set by a timer, or the like. The charging start time is preferably a time when sufficient surplus power is generated. The charging end time is preferably the above-mentioned generation end time Te. For example, the generation end time Te of the day is calculated based on the data stored in the memory 32, and the current amount of the charging current is set based on the time set by the timer or the like and the generation end time Te. As a result, the generated power of the solar panel 11 can be efficiently used, and the stored power of the storage battery 28 can be efficiently used.

10 Solar power generation system 11 Solar panel 12 Power conditioner 13 System power line 14 Commercial power system 15 Electrical equipment 21 PV converter 22 Inverter 23 Filter 24 System interconnection relay 25 DC-DC converter 26 Rectifier 27 Bidirectional DC-DC converter 28 Storage battery 28a Battery management unit 29 Control unit 30 DC high-voltage bus 31 CPU
32 Memory 33 Peripheral circuit 34 Internal bus 41 Voltage sensor 42 Current sensor 43 Current sensor 44 Voltage sensor 51 Power sensor L11 to L13 Characteristic line L21 to L24 Characteristic line L31 Generated power L32 Power consumption L33 SOC curve L34 SOC curve T11 Time Ts generation start Time Te generation end time

Claims

A PV converter that converts the power generated by the solar panel and outputs it to the DC high-voltage bus,
An inverter that converts the power of the DC high-voltage bus into AC power and outputs it to the grid power line.
A storage battery that can be charged and discharged for the DC high-voltage bus,
A control unit that controls the PV converter and the inverter, and also controls the charging current to the storage battery.
With
The control unit charges the storage battery with the charging current of the first current value when the stored amount of the storage battery is less than the first threshold value, and is larger than the first current value when the stored amount is equal to or more than the first threshold value. The storage battery is charged with the charging current of the second current value.
Power conditioner.
The control unit uses the storage battery in accordance with the timing at which the surplus power ends during the period in which the surplus power generated by the difference between the generated power of the solar panel and the power consumption of the electric device operated by the AC power is generated. The charging current is controlled so as to fully charge the battery.
The power conditioner according to claim 1.
When the amount of electricity stored is greater than or equal to the second threshold value than the first threshold value, the control unit charges the storage battery with a charging current having a third current value smaller than the second current value and generates electricity from the solar panel. During the period in which surplus power is generated, which is the difference between the power and the power consumption of the electric device operating on the AC power, the third current is so as to fully charge the storage battery at the timing when the surplus power ends. Set the value,
The power conditioner according to claim 1 or 2.
Based on the position data of the installation location of the power conditioner and the date data, the control unit generates the surplus power during the period in which the surplus power is generated, the generated power becomes smaller than the power consumption, and the surplus power ends. The end time is obtained, and the charging current is controlled so that the storage battery is fully charged at the end time of generation.
The power conditioner according to claim 3.
The power conditioner according to any one of claims 1 to 4, wherein the control unit controls the charging current based on the weather data of the installation location of the power conditioner.
The method according to any one of claims 1 to 5, wherein the control unit detects fluctuations in power consumption by an electric device operating on the AC power and controls the charging current according to the power consumption. Power conditioner.
The control unit detects fluctuations in power consumption by an electric device that operates on AC power, and controls the inverter so as to maintain the charging current, according to any one of claims 1 to 5. Described power conditioner.
The power conditioner according to any one of claims 1 to 7, wherein the control unit acquires the temperature of the storage battery and does not supply a charging current to the storage battery when the temperature is lower than a predetermined temperature.
A PV converter that converts the power generated by the solar panel and outputs it to the DC high-voltage bus,
An inverter that converts the power of the DC high-voltage bus into AC power and outputs it to the grid power line.
A storage battery that can be charged and discharged for the DC high-voltage bus,
A control unit that controls the PV converter and the inverter, and also controls the charging current to the storage battery.
With
The control unit charges the storage battery with the charging current of a predetermined value, and when the storage amount of the storage battery exceeds a predetermined value, performs constant current constant voltage control for charging the storage battery with a charging voltage of a predetermined value. During the period in which the difference between the generated power of the solar panel and the power consumption of the electric device operating on the AC power is generated, the storage battery is fully charged at the timing when the surplus power ends. To set the predetermined value of the charging current so as to
Power conditioner.
A bidirectional DC-DC converter connected between the DC high-voltage bus and the storage battery is provided.
The control unit controls the charging current for the storage battery by controlling the bidirectional DC-DC converter.
The power conditioner according to any one of claims 1 to 9.
The storage battery is directly connected to the DC high-voltage bus and
An electric device that consumes the AC power is connected to the grid power line.
The storage battery is charged by the charging current due to the surplus power of the difference between the generated power of the solar panel and the power consumption of the electric device.
The control unit controls the inverter to control the charging current.
The power conditioner according to any one of claims 1 to 9.