JP6753469B2 - Power storage device and power supply system - Google Patents

Description

The present invention relates to a power storage device and a power supply system.
This application claims priority based on Japanese Application No. 2016-177716 filed on September 12, 2016, and incorporates all the contents described in the Japanese application.

Many power generation systems that use both power generation equipment such as photovoltaic power generation and storage batteries have already been proposed (see, for example, Patent Documents 1 to 4). For example, even for small-scale consumers such as ordinary households, it is considered that the power supply should be as independent as possible from the commercial power system by equipping not only the photovoltaic power generation equipment but also the storage battery. In addition, even if a solar power generation facility is not installed, by installing a storage battery, it is possible to cope with a peak shift and effectively use the electricity at night time when the unit price of electric energy is cheap. As such a storage battery for electric power, a lithium ion battery is generally used.

Japanese Unexamined Patent Publication No. 2004-180467 Japanese Unexamined Patent Publication No. 2012-139019 Japanese Unexamined Patent Publication No. 2013-5584 Japanese Unexamined Patent Publication No. 2013-172495

According to one expression, the present invention is a storage battery connected to an AC electric circuit to which a load in a consumer and a commercial power system are connected and connected to the grid, and is a storage battery and a storage battery for managing the charging state of the storage battery. A management unit, a power conversion unit having a function of converting AC to DC to charge the storage battery, and a function of discharging the storage battery to convert DC to AC and supplying power to the AC electric circuit, and the power conversion unit. To charge and discharge the storage battery and charge the storage battery, the power conversion unit performs a charging operation at a preset charging end time at a pace at which charging to a desired remaining amount is completed. It is a power storage device including a control unit.

Further, according to another expression, the present invention includes an AC electric circuit to which a commercial electric power system is connected, a load in a consumer connected to the AC electric circuit, a solar power generation panel, and the solar power generation panel. A power supply system including a power conditioner that converts an output into AC generated power and sends it to the AC electric circuit, and a power storage device connected to the AC electric current and connected to the grid. The power storage device includes a storage battery and a storage battery. It has a storage battery management unit that manages the charging state of the storage battery, a function of converting alternating current into alternating current to charge the storage battery, and a function of discharging the storage battery to convert direct current into alternating current to supply power to the alternating current path. When the power conversion unit and the power conversion unit are controlled to charge and discharge the storage battery to charge the storage battery, the charging to a desired remaining amount is completed at a preset charging end time. It is a power supply system equipped with a control unit for performing a charging operation by a power conversion unit.

It is a single line connection diagram which shows the circuit structure of a power-source system. It is a single line connection diagram which shows other circuit configurations of a power-source system. It is a single line connection diagram which shows the other circuit configuration of a power-source system. It is a graph which shows an example of the change of the power consumption of one day (weekday) as the sum of a large number of consumers. It is a figure which shows an example of charge / discharge and power supply of a storage battery when there is no solar power generation. It is a figure which shows an example of charge / discharge and power supply of a storage battery when there is solar power generation. This is an example of a flowchart of the operation performed by the control unit on the bidirectional inverter when the power storage device is used as shown in FIGS. 5 and 6. It is a figure which shows an example of charge / discharge and power supply of a storage battery at the time of charging even in the daytime in the power-source system which has the solar power generation as shown in FIG. This is an example of a flowchart of the operation performed by the control unit on the bidirectional inverter when the power storage device is used as shown in FIG. For comparison, it is a graph which shows an example of daily charge / discharge in a conventional power storage device. It is a graph which shows an example of the daily charge / discharge of the power storage device in the power source system which does not have a photovoltaic power generation. It is a graph which shows an example of the daily charge / discharge of the power storage device in the power supply system in the case of having solar power generation and giving priority to selling power. It is a graph which shows an example of the daily charge / discharge of the power storage device in the power supply system in the case of having solar power generation and giving priority to self-consumption. It is a graph which shows other example of daily charge / discharge of the power storage device in a power source system in the case of having solar power generation and giving priority to self-consumption. It is a graph which shows an example of the daily charge / discharge of the power storage device in the power source system which does not have solar power generation, for example, when there are three kinds of electric energy charge unit prices per day.

[Problems to be solved by the present disclosure]
Storage batteries for electric power are still expensive products for home use, and the larger the storage capacity, the more expensive they are. Therefore, in consideration of the power consumption of the average consumer, it is considered preferable from the viewpoint of cost performance to fully utilize the storage battery having a small storage capacity (for example, about 3 kWh).

On the other hand, such a small-capacity storage battery tends to be fully charged as soon as it starts charging at night. If the battery is fully charged and waits until the next discharge opportunity while the voltage is high, the constituent materials inside the battery are likely to deteriorate, and therefore the life is shortened. Even if a small-capacity storage battery is used in consideration of price, if the life is short as a result, it is not much different from the high price.

In view of such conventional problems, it is an object of the present disclosure to enable a storage battery for electric power to be used for as long as possible by devising how to use it.

[Effect of the present disclosure]
According to the present disclosure, it is possible to extend the life of the storage battery.

[Summary of Embodiment]
The gist of the embodiment of the present invention includes at least the following.

(1) This is a power storage device connected to an AC electric circuit to which a load in a consumer and a commercial power system are connected, and is connected to a storage battery, a storage battery management unit for managing the charging state of the storage battery, and a storage battery management unit. Controlling a power conversion unit having a function of converting alternating current into alternating current to charge the storage battery and a function of discharging the storage battery to convert direct current into alternating current and supplying power to the alternating current path, and the power conversion unit. When charging / discharging the storage battery and charging the storage battery, a control unit that causes the power conversion unit to perform a charging operation at a preset charging end time at a pace at which charging to a desired remaining amount is completed. It is a power storage device equipped with.

The power storage device configured as described above makes the charging pace to a desired remaining amount set to the preset charging end time to complete the charging. As a result, charging can be completed intentionally late, so that the time required for the fully charged storage battery to wait until the next discharge starts can be shortened. As a result, it is possible to extend the life of the storage battery.

(2) Further, in the power storage device of (1), the nighttime electric energy charge unit price is applied to the consumer, and the control unit is the storage battery during the nighttime time which is the nighttime electric energy charge unit price. The power conversion unit may perform the charging operation at the pace at which charging to a desired remaining amount is completed at the charging end time of the next day.
In this case, the power storage device can be charged during the nighttime when the unit price of electric energy is cheap, and the charging pace to the desired remaining amount can be adjusted to the charging end time of the next day. Let it be completed. As a result, for example, if the fully charged storage battery is immediately started to be discharged, the life of the storage battery can be extended by reducing the standby time. In addition, even when the discharge starts at the start time of the time zone when the electricity charge is high in the daytime, the waiting time until the charged storage battery starts to discharge is shortened as compared with the case where the charging is completed early at night. be able to.

(3) Further, in the power storage device of (2), the charging end time may be the end time of the night time.
In this case, charging can be completed only with electric power having a low electric energy charge unit price, and the storage battery can be discharged during a time period when the electric energy charge unit price is normal or relatively high.

(4) Further, in the power storage device of (2) or (3), the generated power of photovoltaic power generation is supplied to the AC electric circuit, and the storage battery having the desired remaining amount is used in the daytime excluding the night time. The configuration may be such that the average daily power consumption of the consumer in time is charged.
In this case, the storage battery after the charging is completed can basically cover the amount of power required by the consumer only by the amount of power output by itself. Therefore, all the generated power of photovoltaic power generation can be sold.

(5) Further, in the power storage device of (2) or (3), the generated power of photovoltaic power generation is supplied to the AC electric circuit, and in the daytime time excluding the nighttime time, the control unit receives the generated power. Is less than the self-consumption of the consumer, the shortage of power is supplied to the load from the storage battery, and when the generated power is more than the self-consumption of the consumer, the surplus The power conversion unit may be operated so as to charge the storage battery with the generated power.
In this case, the storage battery is charged by using the generated power of the photovoltaic power generation that exceeds the self-consumption power, and the self-consumption power is covered or supplemented by the storage battery during the time when the photovoltaic power generation is not performed or the generated power is low. be able to. In this way, except when the storage battery is being charged at night, it is possible to put power in and out of the storage battery to make full use of the storage battery and to avoid purchasing power from the commercial power system as much as possible.

(6) Further, in any of the power storage devices (2) to (5), for example, when charging starts in the night time, either when the night time starts or when the storage battery stops discharging. Is slower.
In this case, even if the storage battery stops discharging before the start time of the night time, which is the unit price of the nighttime electric energy, the battery is charged by waiting until the start time and charging at a cheap unit price. On the contrary, if the battery can still be discharged even at the start time, the battery is continuously discharged and charged after the time when the discharge is stopped. In this way, the electric power of the storage battery can be fully utilized, and the electric energy charge for charging can be suppressed.

(7) Further, in the power storage device according to any one of (2) to (6), the desired remaining amount on the next day may fluctuate based on the weather forecast.
In this case, for example, if the next day is sunny and a lot of photovoltaic power generation can be expected, the remaining amount of the storage battery by charging at night time is reduced, and the next day is cloudy or rainy, and a lot of photovoltaic power generation is generated. When electric power cannot be expected, it is possible to store an appropriate amount of electric power without excess or deficiency by increasing the remaining amount.

(8) Further, in any of the power storage devices (1) to (5), when the control unit discharges the storage battery, the power is generated at a pace at which the discharge is completed at the next charging start time. The discharge operation may be performed by the conversion unit.
In this case, for example, the storage battery that has been discharged until the discharge is stopped can be charged immediately without waiting. That is, it contributes to extending the life of the storage battery by reducing the standby time.

(9) From another point of view, this is the AC electric circuit to which the commercial power system is connected, the load in the consumer connected to the AC electric circuit, the solar power generation panel, and the output of the solar power generation panel. A power supply system including a power conditioner that converts an AC power source into AC generated power and sends it to the AC electric circuit, and a power storage device connected to the AC electric current and connected to the grid. The power storage device includes a storage battery and the above. Electric power having a storage battery management unit that manages the charging state of the storage battery, a function of converting alternating current into alternating current to charge the storage battery, and a function of discharging the storage battery to convert direct current into alternating current to supply power to the alternating current circuit. When the conversion unit and the power conversion unit are controlled to charge and discharge the storage battery to charge the storage battery, the power is charged at a pace at which charging to a desired remaining amount is completed at a preset charging end time. It is a power supply system including a control unit for performing a charging operation by a conversion unit.

The power storage device in the power supply system as described above makes the charging pace to a desired remaining amount set to the preset charging end time to complete the charging. As a result, charging can be completed intentionally late, so that the time required for the fully charged storage battery to wait until the next discharge starts can be shortened. As a result, it is possible to extend the life of the storage battery by reducing the standby time.

(10) The power storage device can also be expressed as follows.
That is, it is a power storage device connected to an AC electric circuit to which a load in a consumer and a commercial power system are connected, and is connected to the system. A power conversion unit having a function of converting and charging the storage battery and a function of discharging the storage battery to convert DC into alternating current and supplying power to the alternating current path, and a power conversion unit that controls the power conversion unit to charge the storage battery. When the storage battery is discharged and charged, the power conversion unit is provided with a control unit that suppresses charging to a desired remaining amount at a preset charging end time. It is a power storage device.

[Details of Embodiment]
Hereinafter, a power supply system including a power storage device according to an embodiment of the present invention will be described with reference to the drawings.

<< Circuit configuration and operation of power supply system and power storage device >>
FIG. 1 is a single-line connection diagram showing a circuit configuration of the power supply system 100. In the figure, the commercial power system 3 is connected to the AC electric circuit 2 in the distribution board 1 of the consumer. This consumer is a so-called nighttime electricity contract consumer, and a discounted nighttime electricity unit price is applied at a set nighttime.
Further, a power conditioner 5 is connected to the photovoltaic power generation panel 4. The power conditioner 5 is connected to the AC electric circuit 2.

A consumer load 7 is connected to the AC circuit 2 in the distribution board 1 via a circuit breaker 6. The circuit breaker 6 is normally closed. Although only one system of the circuit breaker and the load is shown here for simplification of the illustration, the circuit breaker and the load are actually connected to the AC circuit 2 over a plurality of systems.

Further, a grid-connected power storage device 8 is connected to the AC electric circuit 2. In the power storage device 8, a bidirectional inverter 9 as a “power conversion unit” is connected to an AC electric circuit 2 via an interconnection relay (opening / closing unit) 10. The storage battery 11 is connected to the bidirectional inverter 9 via the opening / closing unit 12. The storage battery 11 is, for example, a lithium ion battery. The storage battery 11 is provided with a BMS (Battery Management System) 13 as a “storage battery management unit”. The BMS 13 can also be integrated with the control unit 14. The voltage sensor 16 that detects the voltage of the AC electric circuit 2 is provided in, for example, the power storage device 8.

The BMS 13 has acquired various information related to the storage battery 11, such as a state of charge (SOC) of the storage battery 11, a terminal voltage, a cell voltage, and a temperature. The information is sent to the control unit 14. The control unit 14 controls the switching operation of the bidirectional inverter 9 and the opening / closing operation of the interconnection relay 10 and the opening / closing unit 12. Normally, both the interconnection relay 10 and the opening / closing section 12 are closed.

Further, a current sensor 15 is provided on the electric circuit connecting the commercial electric power system 3 and the AC electric circuit 2 in the distribution board 1. The measurement outputs of the current sensor 15 and the voltage sensor 16 are sent to the control unit 14, and based on these, the control unit 14 detects the electric power passed between the commercial power system 3 and the distribution board 1. Can be done.
The control unit 14 includes, for example, a computer, and the computer executes software (computer program) to realize a necessary control function. The software is stored in a storage device (not shown) of the control unit 14.

In FIG. 1, during photovoltaic power generation by the photovoltaic power generation panel 4, the power conditioner 5 is performing grid interconnection operation, and the output (DC) of the photovoltaic power generation panel 4 is converted into alternating current generated power. It is sent to the electric line 2. The generated power can be consumed in-house by the load 7 of the consumer, and if there is surplus power, the commercial power system 3 can be reverse tide (power sold) and the storage battery 11 can be charged. The bidirectional inverter 9 when charging the storage battery 11 converts alternating current to direct current based on the control of the control unit 14.

During the time when solar power is not generated (mainly at night), the commercial power system 3 can supply power to the load 7. Further, the storage battery 11 can be discharged to supply the power consumption of the load 7 from the power storage device 8. The bidirectional inverter 9 when discharging the storage battery 11 converts from direct current to alternating current based on the control of the control unit 14. The storage battery 11 at night can be charged by the electric power of the commercial power system 3.

Although the circuit connection for supplying power to the specific load during a power failure of the commercial power system 3 is omitted in FIG. 1, the above-mentioned power storage device 8 supplies power to the specific load during a power failure of the commercial power system 3. It has a function that can be used. Further, in the case of a power failure in the daytime, the independent output of the power conditioner 5 can be supplied to a specific load.

FIG. 2 is a single-line connection diagram showing another circuit configuration of the power supply system 100. The difference from FIG. 1 is that the photovoltaic power generation panel and the power conditioner are not provided, and the other points are the same as those in FIG. In this case, the storage battery 11 of the power storage device 8 can be charged only by the commercial power system 3. The power supply to the load 7 can be provided from the power storage device 8 in addition to the commercial power system 3 within the range of the self-consumption power of the load 7.

FIG. 3 is a single-line connection diagram showing still another circuit configuration of the power supply system 100. The difference from FIG. 1 is that the control unit 14 can obtain information from the information processing device 17 provided outside the power storage device 8.
The power conditioner 5 and the control unit 14 can communicate with the information processing device 17. The power conditioner 5 sequentially sends the generated power data to the information processing device 17. The information processing device 17 acquires the weather information of the customer's area through, for example, the Internet 18. Then, the information processing device 17 stores and averages the weather and the amount of power generated per day in association with each other to improve the accuracy of the association. In addition, the correspondence is updated sequentially to follow the change of seasons.

From such a correspondence between the past weather and the amount of generated power, the amount of generated power can be estimated if the weather is known. Then, the information processing device 17 can acquire the weather forecast information and predict the amount of power generated on the next day based on the information. The control unit 14 can determine the power to be stored in the storage battery 11 based on the expected power generation amount of the next day that the information processing device 17 has.

<< Example of daily power change in consumers >>
Next, FIG. 4 is a graph showing an example of changes in power consumption per day (weekdays) as a total of a large number of consumers in the region. In this example, the power consumption is high in the morning from 6:00 to 8:00, and in the afternoon from 16:00 to 22:00.
On the other hand, the generated power of photovoltaic power generation gradually rises in the morning and gradually decreases in the evening. It depends on the weather, season, location, etc., but on average, the generated power increases from 10:00 to 14:00.

<< Introduction to charging and discharging storage batteries >>
When there is no photovoltaic power generation as in the power supply system 100 of FIG. 2, the storage battery 11 is charged only at night time (for example, from 23:00 to 7:00) when the unit price of electric energy is low. During the other daytime hours, the storage battery 11 is discharged to supply electric power to the load 7. When the electric power generated by the discharge of the storage battery 11 cannot cover the electric power required for the load 7, the commercial electric power system 3 supplies the insufficient electric power.
FIG. 5 is a diagram showing an example of charging / discharging and power supply of the storage battery 11 in such a case. The storage battery 11 is charged by purchasing electricity from the commercial power system 3 at night time when the unit price of electric energy is low.

Even when there is power generated by photovoltaic power generation as in the power supply system 100 of FIG. 1, the storage battery 11 is charged at night time (for example, from 23:00 to 7:00) when the unit price of electric energy is low. During the other daytime hours, the storage battery 11 is discharged to supply electric power to the load 7. When the electric power generated by the discharge of the storage battery 11 can cover the electric power required for the load 7, all the electric power generated by the photovoltaic power generation can be sold. If the power generated by the discharge of the storage battery 11 cannot cover the power required for the load 7, the shortage will be supplemented by the generated power.
FIG. 6 is a diagram showing an example of charging / discharging and power supply of the storage battery 11 in such a case. The storage battery 11 is charged by purchasing electricity from the commercial power system 3 at night time when the unit price of electric energy is low. Other than this night time, the storage battery 11 discharges the stored electric power. When the electric power generated by the discharge of the storage battery 11 can cover the electric power required for the load 7, all the electric power generated by the photovoltaic power generation can be sold. That is, this is how to use the power storage device 8 with priority on selling power.

FIG. 7 is an example of a flowchart of the operation performed by the control unit 14 on the bidirectional inverter 9 when the power storage device 8 is used as shown in FIGS. 5 and 6. In FIG. 7, first, the control unit 14 determines whether or not it is daytime (step S1). The daytime time is a time when the unit price of electric energy is normal, for example, from after 7:00 to just before 23:00. If it is not daytime (that is, nighttime) in step S1, the control unit 14 determines whether it is nighttime (step S3), and if it is nighttime, bidirectionally so as to charge the storage battery 11. The inverter 9 is operated (step S4). Steps S1 → S3 → S4 → S1 are repeated until the daytime time is reached.

When the daytime is reached in step S1, the control unit 14 operates the bidirectional inverter 9 so as to discharge the storage battery 11 (step S2). Subsequently, the control unit 14 determines whether or not it is night time (step S3). When it is not night time (that is, daytime time) in step S3, the control unit 14 repeats steps S1 → S2 → S3 → S1 until night time is reached.

Next, FIG. 8 is a diagram showing an example of charging / discharging and power supply of the storage battery 11 when charging is performed even in the daytime in the power supply system 100 having solar power generation as shown in FIG. In the figure, the storage battery 11 is charged at night time (this is referred to as the first time). At the end of the night time, the storage battery 11 starts discharging. Then, the shortage of power obtained by subtracting the generated power from the self-consumed power in the period t1 when the generated power of the photovoltaic power generation is not yet sufficient is covered by the discharge of the storage battery 11.

After the elapse of the period t1, when the generated power of the photovoltaic power generation exceeds the self-consumption power, all the self-consumption power can be covered by the generated power, and surplus power is generated. Therefore, the storage battery 11 is charged with this surplus electric power (second time). This charging compensates for the power lost due to the discharge during the period t1. Next, in the evening, when the generated power drops to the self-consumption power, in the subsequent period t2, the shortage power obtained by subtracting the generated power from the self-consumption power is covered by the discharge of the storage battery 11. The generated power becomes 0 after the end of the period t3, and thereafter, the self-consumption is covered by discharging the storage battery 11 until the night time. At night time, the storage battery 11 can be charged.

FIG. 9 is an example of a flowchart of the operation performed by the control unit 14 on the bidirectional inverter 9 when the power storage device 8 is used as shown in FIG. In FIG. 9, first, the control unit 14 determines whether or not it is daytime (step S11). If it is not daytime (that is, nighttime) in step S11, the control unit 14 determines whether it is nighttime (step S15), and if it is nighttime, bidirectionally so as to charge the storage battery 11. The inverter 9 is operated (step S16). Steps S11 → S15 → S16 → S11 are repeated until the daytime time is reached.

When the daytime is reached in step S11, the control unit 14 determines whether or not the generated power exceeds the self-consumption (step S12). If the value does not exceed (No), the control unit 14 operates the bidirectional inverter 9 so as to discharge the storage battery 11 (step S14). Subsequently, the control unit 14 determines whether or not it is night time (step S15). When it is not night time (that is, daytime time) in step S15, the control unit 14 repeats steps S11 → S12 → S14 → S15 → S11 until night time is reached.

When the generated power exceeds the self-consumption power, the control unit 14 operates the bidirectional inverter 9 so as to charge the storage battery 11 (step S13). Subsequently, the control unit 14 determines whether or not it is night time (step S15). When it is not night time (that is, daytime time) in step S15, the control unit 14 repeats steps S11 → S12 → S13 → S15 → S11 until night time is reached. In the evening, when the generated power does not exceed the self-consumption power, the processing of the control unit 14 repeats steps S11 → S12 → S14 → S15 → S11 until night time.

When the night time is reached in step S15, the control unit 14 subsequently charges the storage battery 11 by the end of the night time.

<< How to charge the storage battery >>
Here, how to charge the storage battery 11 will be described in detail.
The control unit 14 sets the time when the storage battery 11 is fully charged to the end time of the night time. That is, the storage battery 11 is charged so that the desired remaining amount (SOC) is reached at the same time as the end of the night time. After the start of the night time, the control unit 14 sets the charging pace so that the difference between the desired remaining amount at the completion of charging and the current remaining amount becomes 0 at the same time as the end of the night time. In other words, charging is performed at a pace at which charging to a desired remaining amount is completed at a preset charging end time.

The reason for this charging method is to avoid a situation in which charging is completed early and there is a long time before the end of night time. As a result, the waiting time until the discharge starts in the fully charged state can be shortened as much as possible (ideally 0). By shortening the standby time, it is possible to prevent the life of the storage battery 11 from being shortened, and the storage battery 11 can be used for a longer period of time. Further, according to the contract, if there is a time zone in which the unit price of the electric power charge is relatively high in the daytime, the storage battery 11 can be started to be discharged at the start time of the time zone. In this case, there is a waiting time from the completion of charging, but since the waiting time is relatively short as compared with the case where the charging is completed early at night, it is possible to suppress the shortening of the life of the storage battery 11 and make it longer. The storage battery 11 can be used for a period of time.
Similarly, when charging the storage battery 11 with the surplus power of the photovoltaic power generation in the daytime, charging is performed at a pace at which charging to a desired remaining amount is completed at a preset charging end time.

<< Specific example of daily charging / discharging >>
Next, a specific example of charging / discharging will be described using a graph.

(Reference example)
FIG. 10 is a graph showing an example of daily charging / discharging in a conventional power storage device for comparison. In the figure, the horizontal axis is the time of day (24 hours), and the vertical axis is SOC [%]. The uphill part of the polygonal line of the graph represents charging, and the downhill part represents discharging. The way of reading the figure is the same in FIGS. 11 and 11 described later.

In FIG. 10, charging is performed during the night time from 23:00 to 7:00, when the unit price of electric energy is cheap. Here, assuming that the SOC is 0% at 23:00 when the power of the storage battery is used up, charging is started from 23:00, which is the start time of the night time. When charging is performed with a constant power, the SOC reaches 100% (fully charged) at about 1:30 the next day, and charging is completed.

After reaching the fully charged state, the storage battery is in the standby state until 7:00, which is the end time of the night time, and waits for about 5.5 hours until 7:00, when the battery is fully charged. The length of this standby time contributes to shortening the life of the storage battery. At 7 o'clock, the discharge starts, and after that, the stored power is released by 23:00, and the SOC becomes 0%.
To be precise, SOC is a value of SOC that causes discharge to stop rather than 0%, but for the sake of brevity, it will be described as 0% (the same shall apply hereinafter).

Next, charging / discharging of the power storage device 8 (FIGS. 1 to 3) according to the present embodiment will be described with reference to FIGS. 11 to 14.

(Without solar power generation)
FIG. 11 is a graph showing an example of daily charging / discharging of the power storage device 8 in the power supply system 100 having no photovoltaic power generation as shown in FIG. Charging is performed during the night time from 23:00 to 7:00, when the unit price of electricity is cheap. Assuming that the power of the storage battery 11 is used up and the SOC is 0% at 23:00, charging starts at 23:00, which is the start time of night time. Here, the control unit 14 sets the charging pace so that charging is completed at 7:00 the next morning. For example, assuming that the battery capacity of the storage battery 11 is 3 kWh, 3000/8 = 375 [W] to charge the SOC from 0% to 100% over 8 hours from 23:00 to 7:00 the next morning. ] To charge.

By charging at a pace calculated based on such a charging completion time, the storage battery 11 reaches a state of 100% SOC at 7:00 the next morning, and charging is completed. Discharge starts at the same time as charging is completed, and after that, the stored power is released by 23:00, and the SOC becomes 0%. The discharge may be a constant output as shown in the figure, or the output may be changed according to the fluctuation of the self-consumption power.

In this way, the power storage device 8 charges during the nighttime when the unit price of electric energy is cheap, and sets the pace of charging up to the desired remaining amount of SOC 100% at the discharge start time (7) of the next day. Make sure that charging is completed at the same time. As a result, the time for the storage battery 11 that has been fully charged to stand by in that state can be set to zero. Therefore, it is possible to extend the life of the storage battery 11 by reducing the standby time.

The purpose of charging at a pace at which charging to a desired remaining amount is completed at a preset charging end time is ideally to make the standby time 0, but it is completely 0. Is not essential for the effect. For example, even if the time when charging is completed is 7 hours and several minutes before and there is a waiting time of several minutes, there is no big difference, and substantially the same effect is obtained. In addition, by completing the charging at the end time of the night time, it is possible to complete the charging with only the electricity whose electric energy charge is cheap, and it is possible to discharge the storage battery at the same time as the normal electric energy charge unit price. ..

Further, in the above example, when the storage battery 11 is discharged during the daytime from 7:00 to 23:00, the discharge operation is performed at a pace at which the discharge is completed at the next charging start time (23:00). .. As a result, the storage battery 11 that has been discharged until the discharge is stopped can be charged immediately without waiting. That is, this also contributes to extending the life of the storage battery 11 by reducing the standby time (this also applies to the examples of FIGS. 12 to 15 described below).

(If there is solar power generation and priority is given to selling electricity)
Next, FIG. 12 is a graph showing an example of daily charging / discharging of the power storage device 8 in the power supply system 100 having photovoltaic power generation as shown in FIG. It should be noted that this consumer has an average daily electric energy consumption of, for example, 2.7 kWh in the daytime, and 90% of the battery capacity of the storage battery 11 is 3 kWh.

Charging is performed during the night time from 23:00 to 7:00, when the unit price of electricity is cheap. Assuming that the power of the storage battery 11 is used up and the SOC is 0% at 23:00, charging starts at 23:00, which is the start time of night time. Here, the control unit 14 sets the charging pace so that the charging is completed at 7:00 the next morning and the SOC value at that time is 90%. For example, assuming that the battery capacity of the storage battery 11 is 3 kWh, it takes 8 hours from 23:00 to 7:00 the next morning to charge the SOC from 0% to 90% (3000 × 0.9). / 8 ≈ 338 [W] for charging.

By charging at a pace calculated based on the charging completion time and the SOC at that time, the storage battery 11 reaches a state where the SOC reaches 90% at 7:00 the next morning, and the charging is completed. Discharge starts at the same time as charging is completed, and after that, the stored power is released by 23:00, and the SOC becomes 0%. The discharge may be a constant output as shown in the figure, or the output may be changed according to the fluctuation of the self-consumption power.

In this way, the power storage device 8 charges during the nighttime when the unit price of electric energy is cheap, and sets the charging pace up to the desired remaining amount of SOC 90% at the discharge start time (7) of the next day. Make sure that charging is completed at the same time. As a result, the time for the fully charged storage battery to stand by in that state can be reduced to zero. Therefore, it is possible to extend the life of the storage battery 11 by reducing the standby time. As in the above description with respect to FIG. 11, the waiting time is ideally 0, but in reality, it may be as short as possible. In addition, by completing charging and starting discharging at the end time of night time, charging can be completed with only electricity with a low electric energy charge, and the storage battery is discharged at the same time as the normal electric energy charge unit price is reached. be able to.

In addition, since the average daily power consumption of the consumer during the daytime is charged as the desired remaining amount at the time of charging completion, the storage battery 11 after charging is basically the amount of power output by itself. Only can cover the amount of electricity required by consumers. In this case, all the generated power of the photovoltaic power generation can be sold. When the unit price of selling electricity is relatively high, such usage is advantageous.

(If there is solar power generation and priority is given to self-consumption _1)
Next, FIG. 13 is a graph showing an example of daily charging / discharging of the power storage device 8 in the power supply system 100 having photovoltaic power generation as shown in FIG.

Charging is performed during the night time from 23:00 to 7:00, when the unit price of electricity is cheap. Here, the charging completion time is adjusted to the end time of the night time, but the charging start time is not always the start time of the night time. That is, the charging start time in the night time is the later of the night time start time and the storage battery 11 when the discharge is stopped. Charging is also performed during the daytime.

Specifically, assuming that the power of the storage battery 11 is used up at 0 o'clock (24:00) and the SOC is 0%, charging is started from 0 o'clock. Here, the control unit 14 sets the charging pace so that the charging is completed at 7:00 the next morning and the SOC value at that time is, for example, 50%. In this case, assuming that the battery capacity of the storage battery 11 is 3 kWh, it takes 7 hours from 0:00 to 7:00 the next morning to charge the SOC from 0% to 50% (3000 × 0.5). ) / 7 ≈ 215 [W] for charging. Here, 50% is set to supply power from the power storage device 8 to the load 7 of the consumer during the time zone from 7:00 to 10:00, and the generated power of the photovoltaic power generation will exceed the self-consumption power. It is based on the idea that the SOC should be 0% at 10 o'clock.

That is, the storage battery 11 reaches a state where the SOC reaches 50% at 7 o'clock, and charging is completed. Discharge starts at the same time as charging is completed, and after that, the stored power is released and the SOC becomes 0% at 10 o'clock. The discharge may be a constant output as shown in the figure, or the output may be changed according to the fluctuation of the self-consumption power.

Next, from 10:00 to 16:00, the storage battery 11 is charged by the surplus power generated by the photovoltaic power generation. The control unit 14 sets the charging pace so that, for example, charging is completed at 16:00 and the SOC value at that time is 100%. This charge is to prepare for the amount of power that is expected to be needed from evening to night. To charge the SOC from 0% to 100% over 6 hours from 10:00 to 16:00, charge at 3000/6 = 500 [W].

At 16:00, discharge starts at the same time as charging is completed, and thereafter, the stored power is released by 24:00 (0:00), and the SOC becomes 0%. The discharge may be a constant output as shown in the figure, or the output may be changed according to the fluctuation of the self-consumption power. It will be night time at 23:00, but priority will be given to discharge, that is, self-consumption. On the contrary, even if the storage battery 11 stops discharging before the start time of the night time, it waits until the start time of the night time and charges at a low unit price. In this case, a standby time occurs in a state where the discharge is stopped, so it is preferable to shorten this standby time as much as possible.
In this way, the electric power of the storage battery 11 can be fully utilized, and the electric energy charge for charging can be suppressed.

Also in the case of FIG. 13, the power storage device 8 charges during the night time when the electric energy charge unit price is cheap, and the charging pace up to the desired remaining amount of SOC 50% is set to the discharge start time of the next day. Make sure that charging is completed at (7 o'clock). As a result, the time for the fully charged storage battery to stand by in that state can be reduced to zero. Therefore, it is possible to extend the life of the storage battery 11 by reducing the standby time. As in the above description with respect to FIG. 11, the waiting time is ideally 0, but in reality, it may be as short as possible. In addition, by completing charging and starting discharging at the end time of night time, charging can be completed with only electricity with a low electric energy charge, and the storage battery is discharged at the same time as the normal electric energy charge unit price is reached. be able to.

Further, in the case of FIG. 13, the value of SOC at the end of the night time is suppressed so that the surplus power of the photovoltaic power generation can be charged. Therefore, the SOC can be reduced to 0% at 10 o'clock, and then the system can be prepared to charge the surplus power of the photovoltaic power generation. Further, here as well, the power storage device 8 sets the charging pace up to the desired remaining amount of SOC 100% at the time of charging completion to the preset charging end time (16:00) to complete charging. As a result, the time for the storage battery 11 that has been fully charged to stand by in that state can be set to zero. Therefore, it is possible to extend the life of the storage battery 11 by reducing the standby time.
In addition, after 16:00, electric power can be supplied to the load of the consumer.

In this way, the storage battery 11 is charged by using the generated power of the photovoltaic power generation that exceeds the self-consumption power, and the self-consumption power in the time zone when the photovoltaic power generation is not performed or the generated power is low is used by the storage battery 11. Can be covered or supplemented. Therefore, except when the storage battery 11 is being charged at night, it is possible to put power in and out of the storage battery 11 to make full use of the storage battery 11 and to avoid purchasing power from the commercial power system 3 as much as possible. With such a usage pattern of the storage battery, it is possible to realize a state close to self-sufficiency of electric power in the consumer. Further, according to the usage pattern of the storage battery as shown in FIG. 13, the effect of saving the electric energy charge can be enhanced by operating the small-capacity storage battery 11 by charging and discharging two cycles a day (this is). The same applies to FIG. 14 described later.)

(If there is solar power generation and priority is given to self-consumption _2)
Next, FIG. 14 is a graph showing an example of daily charging / discharging of the power storage device 8 in the power supply system 100 having photovoltaic power generation as shown in FIG. The charge and discharge are basically the same as those in FIG. 13, except that the desired remaining amount when the storage battery charge is completed is changed based on the weather forecast information.

Charging is performed during the night time from 23:00 to 7:00, when the unit price of electricity is cheap. The charging completion time is adjusted to the end time of the night time, but the charging start time is not always the start time of the night time. That is, the charging start time in the night time is the later of the night time start time and the storage battery 11 when the discharge is stopped. FIG. 14 shows an example in which the start time of charging is the start time of night time. Charging is also performed during the daytime.

Specifically, assuming that the power of the storage battery 11 is used up at 23:00 and the SOC is 0%, charging starts at 23:00. Here, the control unit 14 sets the charging pace so that the charging is completed at 7:00 the next morning and the SOC value at that time is, for example, 80%. In this case, assuming that the battery capacity of the storage battery 11 is 3 kWh, it takes 8 hours from 23:00 to 7:00 the next morning to charge the SOC from 0% to 80% (3000 × 0.8). ) / 8 = 300 [W]. Here, the reason why it is set to 80% is that it is predicted that the generated power after 7 o'clock is not large in consideration of the weather forecast.

That is, the control unit 14 refers to the data of the expected power generation amount based on the information of the weather forecast of the next day held by the information processing device 17, and determines the required SOC value at 7:00 the next morning. For example, if the weather forecast is fine, a large amount of power generation can be expected after 7 o'clock, so for example, as shown in FIG. 13, the SOC at 7 o'clock may be, for example, 50%. However, if the weather forecast is cloudy or rainy, a large amount of power generation cannot be expected, so it is necessary to raise the SOC level at 7 o'clock.

In FIG. 14, the storage battery 11 reaches a state where the SOC reaches 80% at 7 o'clock, and charging is completed. Discharge starts at the same time as charging is completed, and after that, the stored power is released, and the SOC becomes 30% at 10 o'clock. The discharge may be a constant output as shown in the figure, or the output may be changed according to the fluctuation of the self-consumption power.

Next, from 10:00 to 16:00, the storage battery 11 is charged by the surplus power generated by the photovoltaic power generation. The control unit 14 sets the charging pace so that, for example, charging is completed at 16:00 and the SOC value at that time is 100%. This charge is to prepare for the amount of power that is expected to be needed from evening to night. To charge the SOC from 30% to 100% over 6 hours from 10:00 to 16:00, charge at (3000 × 0.7) / 6 = 350 [W].

At 16:00, discharging starts at the same time as charging is completed, and thereafter, the stored power is released by 23:00, and the SOC becomes 0%. The discharge may be a constant output as shown in the figure, or the output may be changed according to the fluctuation of the self-consumption power.

Also in the case of FIG. 14, the power storage device 8 charges during the night time when the electric energy charge unit price is cheap, and the charging pace up to the desired remaining amount of SOC 80% is set to the discharge start time of the next day. Make sure that charging is completed at (7 o'clock). As a result, the time for the fully charged storage battery to stand by in that state can be reduced to zero. Therefore, it is possible to extend the life of the storage battery 11 by reducing the standby time. As in the above description with respect to FIG. 11, the waiting time is ideally 0, but in reality, it may be as short as possible. In addition, by completing the charging at the end time of the night time, it is possible to complete the charging with only the electricity whose electric energy charge is cheap, and it is possible to discharge the storage battery at the same time as the normal electric energy charge unit price. ..

Further, in the case of FIG. 14, the value of SOC at the end of the night time is determined so that the surplus power of the photovoltaic power generation expected based on the weather forecast can be charged. Therefore, the storage battery 11 can be charged without excess or deficiency in consideration of the weather forecast. After 10 o'clock, it is possible to prepare for charging the surplus power of photovoltaic power generation. Further, here as well, the power storage device 8 sets the charging pace up to the desired remaining amount of SOC 100% at the time of charging completion to the preset charging end time (16:00) to complete charging. As a result, the time for the storage battery 11 that has been fully charged to stand by in that state can be set to zero. Therefore, it is possible to extend the life of the storage battery 11 by reducing the standby time.
In addition, after 16:00, electric power can be supplied to the load of the consumer.

In this way, the storage battery 11 is charged by using the generated power of the photovoltaic power generation that exceeds the self-consumption power, and the self-consumption power in the time zone when the photovoltaic power generation is not performed or the generated power is low is used by the storage battery 11. Can be covered or supplemented. Therefore, except when the storage battery 11 is being charged at night, it is possible to put power in and out of the storage battery 11 to make full use of the storage battery 11 and to avoid purchasing power from the commercial power system 3 as much as possible. With such a usage pattern of the storage battery, it is possible to realize a state close to self-sufficiency of electric power in the consumer.

(For other contracts)
It is most preferable that the standby time is 0, but even if it is unavoidable that a standby time occurs in operation, a certain effect of extending the life can be obtained by shortening the standby time.
FIG. 15 is a graph showing an example of daily charging / discharging of a power storage device 8 in a power supply system 100 that does not have solar power generation, for example, when there are three types of electric energy charge unit prices per day. The unit price of electricity is, in descending order, for example, "daytime" from 10:00 to 17:00, "living time" from 7:00 to 10:00 and 17:00 to 23:00, and "nighttime" from 23:00 to 7:00. (Night time) ".

Charging is performed at night time from 23:00 to 7:00, when the unit price of electricity is cheap. Assuming that the power of the storage battery 11 is used up and the SOC is 0% at 23:00, charging starts at 23:00, which is the start time of the night time. Here, the control unit 14 sets the charging pace so that charging is completed at 7:00 the next morning. For example, assuming that the battery capacity of the storage battery 11 is 3 kWh, 3000/8 = 375 [W] to charge the SOC from 0% to 100% over 8 hours from 23:00 to 7:00 the next morning. ] To charge.

By charging at a pace calculated based on such a charging completion time, the storage battery 11 reaches a state of 100% SOC at 7:00 the next morning, and charging is completed. At the same time as the charging is completed, the living time is reached, but the storage battery 11 stands by without being discharged in preparation for the daytime when the unit price of electric energy is the highest. When the daytime starts at 10 o'clock, the discharge starts, and after that, the stored electric power is released by 23:00, and the SOC becomes 0%. The discharge may be a constant output as shown in the figure, or the output may be changed according to the fluctuation of the self-consumption power.

In this way, the power storage device 8 charges during the nighttime when the unit price of electric energy is cheap, and the pace of charging up to the desired remaining amount of SOC 100% is set to the nighttime end time of the next day ( Make sure that charging is completed at 7 o'clock). Then, the fully charged storage battery 11 waits without being discharged until the start of the daytime. In this case, there is a waiting time from the completion of charging, but the waiting time is relatively shorter than the case where charging is completed early at night (for example, when charging is completed at 1:30 am), so the storage battery It is possible to suppress the shortening of the life of the storage battery 11 and use the storage battery 11 for a longer period of time.

《Supplementary note》
It should be understood that the embodiments disclosed this time are exemplifications in all points and not restrictive. The scope of the present invention is indicated by the claims and is intended to include all modifications within the meaning and scope equivalent to the claims.

1 Distribution board 2 AC power system 3 Commercial power system 4 Photovoltaic panel 5 Power conditioner 6 Circuit breaker 7 Load 8 Power storage device 9 Bi-directional inverter 10 Interconnection relay 11 Storage battery 12 Opening / closing part 13 BMS
14 Control unit 15 Current sensor 16 Voltage sensor 17 Information processing device 18 Internet 100 Power supply system

Claims (8)

It is a power storage device that is connected to an AC electric circuit to which the generated power of photovoltaic power generation is supplied and is connected to the load of the consumer and the commercial power system, and is connected to the grid.
With a storage battery
A storage battery management unit that manages the charging state of the storage battery,
A power conversion unit having a function of converting alternating current into direct current to charge the storage battery and a function of discharging the storage battery to convert direct current into alternating current and supplying power to the alternating current electric circuit.
When the storage battery is charged and discharged by controlling the power conversion unit to charge the storage battery, charging by the power conversion unit is performed at a pace at which charging to a desired remaining amount is completed at a preset charging end time. and a control unit to perform the operation,
The charging operation in one day includes a first charging operation that is less than the charging upper limit value based on the commercial power system and a second charging operation up to the charging upper limit value based on the generated power. apparatus. The nighttime electricity charge unit price is applied to the customer.
The control unit charges the storage battery during the night time, which is the unit price of the nighttime electric energy charge, and at the charging end time of the next day, the power conversion unit completes charging to a desired remaining amount. The power storage device according to claim 1, wherein the first charging operation is performed according to the above . The power storage device according to claim 2, wherein the charging end time in the first charging operation is the end time of the night time. The power storage device according to claim 2, wherein the start of charging in the night time is the later of the start time of the night time and the time when the storage battery is stopped from discharging . The power storage device according to any one of claims 2 to 4, wherein the desired remaining amount on the next day varies based on the weather forecast with respect to the first charging operation . Any one of claims 1 to 5, wherein when the storage battery is discharged, the control unit performs a discharge operation by the power conversion unit at a pace at which the discharge is completed at the next charging start time. The power storage device described in. AC power lines to which commercial power systems are connected and
The load on the consumer connected to the AC electric circuit and
Solar power panel and
A power conditioner that converts the output of the photovoltaic power generation panel into AC power and sends it to the AC circuit.
A power supply system including a power storage device connected to the AC electric circuit and connected to the grid.
The power storage device
With a storage battery
A storage battery management unit that manages the charging state of the storage battery,
A power conversion unit having a function of converting alternating current into direct current to charge the storage battery and a function of discharging the storage battery to convert direct current into alternating current and supplying power to the alternating current electric circuit.
When the storage battery is charged and discharged by controlling the power conversion unit to charge the storage battery, charging by the power conversion unit is performed at a pace at which charging to a desired remaining amount is completed at a preset charging end time. Equipped with a control unit that operates
The charging operation in one day includes a first charging operation that is less than the charging upper limit value based on the commercial power system and a second charging operation up to the charging upper limit value based on the generated power. system. It is a power storage device that is connected to an AC electric circuit to which the generated power of photovoltaic power generation is supplied and is connected to the load of the consumer and the commercial power system, and is connected to the grid.
With a storage battery
A storage battery management unit that manages the charging state of the storage battery,
A power conversion unit having a function of converting alternating current into direct current to charge the storage battery and a function of discharging the storage battery to convert direct current into alternating current and supplying power to the alternating current electric circuit.
When the storage battery is charged and discharged by controlling the power conversion unit to charge the storage battery, the power conversion unit uses power suppressed so as to complete charging to a desired remaining amount at a preset charging end time. Equipped with a control unit that performs charging operation by
The charging operation in one day includes a first charging operation that is less than the charging upper limit value based on the commercial power system and a second charging operation up to the charging upper limit value based on the generated power. apparatus.