JP5925554B2 - Control device, control system, and control method - Google Patents

Description

  The present invention relates to a control device that includes a solar cell and controls a storage battery that supplies power to an electric power load, a control system that includes the solar cell and the storage battery, and a control method.

  With the background of environmental issues and economic demands, examples of introducing solar power generation systems to households are increasing. For example, Patent Document 1 describes an example of a photovoltaic power generation system. In general, in a solar power generation system, power generated by a solar cell is supplied to a power load such as a household electric appliance, and the surplus is reversely flowed to a commercial power supply system (hereinafter referred to as a system) and sold.

  Since a solar power generation system that sells surplus generated power has limited economic merit, a system that sells more generated power has been proposed. For example, by installing a storage battery in a solar power generation system, power is purchased and stored from the grid at night when solar power cannot be generated, and the stored power is consumed during the day, while solar power is generated. Can be sold to the system as much as possible.

JP 2005-192282 A

  In the system as described above, in order to sell the generated power as much as possible, it is necessary to store electricity sufficiently at night so that the generated power does not have to be charged for the power consumption during the day. For this purpose, it is necessary to charge the storage battery with a certain amount of charging current.

  On the other hand, the storage battery used in the system as described above is likely to deteriorate due to frequent charge and discharge. Then, the cost for replacement of the storage battery becomes a problem. Here, it is known that the rate of deterioration of the storage battery is generally correlated with the charge / discharge current. For example, as shown in FIG. 1, the larger the charge / discharge current, the faster the deterioration (the smaller the number of cycles that can be charged / discharged), and the lower the charge / discharge current, the slower the deterioration (the more the number of cycles that can be charged / discharged). Then, in order to suppress the speed of deterioration of the storage battery, it is desirable to reduce the charge / discharge current amount.

  Thus, the storage battery has a conflicting request for charge / discharge current.

  An object of the present invention made in view of the above is to provide a storage battery control device and a control system for charging a storage battery with a current that can efficiently sell power generated by solar power generation and suppress the deterioration rate of the storage battery. And it is providing the control method of a storage battery.

In order to solve the above-described problem, a control device according to one aspect of the present invention provides a power generation state detection that detects at least the start and end of power generation based on generated power output to a grid when a solar cell performs power generation. A charge amount detection unit that detects a charge amount of a storage battery that is charged by a charge current from the system and supplies power to a power load, and at the start of charging, at a past start time of the power generation and the charge amount And a charging control unit for determining the charging end time and charging current of the storage battery to charge the storage battery so that a predetermined charging amount is reached by the next start of power generation.

  In a preferred aspect of the present invention, the charge control unit sets the end time of the power generation as the start time of the charge, and sets the start time of the power generation as the end time of the charge.

  In a preferred aspect of the present invention, the charging control unit obtains the charging start time based on one or both of the past end time and first time of the power generation and information acquired from another device. .

  In another preferable aspect of the present invention, when the past end time of the power generation is earlier than the first time, the charge control unit sets the start time of the charge as the first time.

  In a preferred aspect of the present invention, when the power generation start time is later than the second time, the charge control unit sets the charge end time as the second time.

  In a preferred aspect of the present invention, the power generation state detection unit acquires the generated power from a current between the solar cell and the system.

  The aspect of this invention is a control system which has said solar cell, a storage battery, and a control apparatus.

  As described above, the solution of the present invention has been described as an apparatus. However, the present invention can be realized as a method, a program, and a storage medium storing the program, which are substantially equivalent thereto, and the scope of the present invention. It should be understood that these are also included. Note that each step of the method or program uses an arithmetic processing unit such as a CPU or a DSP as necessary in data processing, and the input data, processed / generated data, etc. are stored in an HDD, memory, etc. Is stored in the storage device.

For example, a storage battery control method that implements the present invention as a method includes a step of detecting at least the start and end of the power generation based on the generated power output to the system when the solar cell generates power, and from the system The power generation starts next based on the step of detecting the charge amount of the storage battery that is charged by the charging current and supplies the power to the power load, and at the start of charging, based on the past start time of the power generation and the charge amount Charging the storage battery by determining an end time and a charging current for charging the storage battery so that a predetermined amount of charge is reached by the time .

  According to the embodiment described below, the storage battery can be charged with a charging current that can efficiently sell the power generated by solar power generation and suppress the deterioration rate of the storage battery.

It is a figure which shows the characteristic of a storage battery. It is a figure which shows the structural example of the solar energy power generation system to which the control apparatus in this embodiment is applied. 3 is a diagram illustrating a detailed configuration example of a control unit 218 of a power storage control device 212. FIG. FIG. 6 is a flowchart for explaining the operation of a charging control unit 304. It is a flowchart for demonstrating the determination process of electric power generation start time and end time. It is a figure which shows the example of electric power when the control method of this embodiment is performed. It is a figure which shows the example of the electric power in the system which does not use a storage battery. It is a flowchart figure which shows the determination process of the electric power generation start time and end time in a 1st modification. It is a figure which shows the structural example of the solar energy power generation system in a 2nd modification. It is a flowchart figure which shows the determination process of the electric power generation start time and end time in a 2nd modification.

  Embodiments of the present invention will be described below.

  FIG. 2 shows a configuration example of a photovoltaic power generation system to which the control device in the present embodiment is applied. This solar power generation system 20 is installed, for example, in a home or various commercial and industrial facilities. The photovoltaic power generation system 20 includes a solar cell 200, a power conditioner 208 that controls its output, a breaker 220 that is connected to the grid 202, and a current sensor that detects current between the power conditioner 208 and the breaker 220. 209, a power storage control device 212 that charges the storage battery 204 with electric power supplied from the system 202 or discharges the storage battery 204, and the storage battery 204.

  Solar cell 200 is configured, for example, such that power generation units having photoelectric conversion cells are connected in a matrix and output a predetermined short-circuit current (for example, 20 A (ampere)). The type of solar cell 200 is not limited as long as it is capable of photoelectric conversion, such as a silicon-based polycrystalline solar cell, a silicon-based single crystal solar cell, or a thin-film solar cell such as CIGS. The solar cell 200 generates electric power according to its configuration and the amount of sunlight.

  The power conditioner 208 includes a booster circuit that boosts the DC power generation voltage generated by the solar battery 200 to a predetermined voltage, and an inverter that converts the DC voltage into AC and outputs the AC voltage. For example, when the output voltage of the solar battery 200 is 100V, the voltage is boosted to 300 to 400V. The boosted DC voltage is converted into, for example, a single-phase three-wire sine wave output of 200 V / 200 V and output.

  The power storage control device 212 includes an inverter 214 that performs bidirectional conversion between AC power and DC power, a converter 216 that boosts or decreases an input voltage, and a control unit 218 that controls them. Inverter 214 converts AC power supplied from system 202 into DC power and outputs it to converter 216, and converts DC power output from converter 216 into AC power and outputs it to power load 206. Converter 216 reduces the output voltage of inverter 214 and outputs a charging current having a set current value to storage battery 204. Thus, the storage battery 204 is charged. Converter 216 boosts the output voltage of storage battery 204 and outputs the boosted voltage to inverter 214. Thus, the storage battery 204 is discharged. This power storage control device 212 is an example of a “control device” in the present embodiment.

  Control unit 218 controls the current passing through converter 216 and / or inverter 214 to control the charging current of storage battery 204. The control unit 218 is, for example, a microcomputer, and includes a storage medium that stores a control program and a CPU (Central Processing Unit) that executes a control procedure according to the control program. Further, the control unit 218 acquires the output current of the power conditioner 208 from the current sensor 209 and uses it for controlling the charging current. The control unit 218 may acquire the generated power from the power conditioner 208 in addition to or instead of the current sensor 209. For example, the power storage control device 212 and the power conditioner 208 are provided with a communication unit that performs wired or wireless communication with each other, and the communication unit on the power storage control device 212 side acquires the generated power from the power conditioner 208 side to the control unit 218. It is possible to send.

  The storage battery 204 is, for example, a lithium ion battery in which a plurality of cells are connected in series, or a nickel metal hydride battery. The voltage sensor 205 that detects the voltage of the storage battery 204 sends the detection result to the control unit 218.

  The power load 206 is a power load that consumes power. For example, various electric appliances such as air conditioners, microwave ovens, and televisions used in homes, machines such as air conditioners and lighting fixtures used in commercial and industrial facilities, Lighting equipment, etc.

  In the configuration as described above, the solar cell 200 automatically performs power generation in an amount corresponding to sunlight. The photovoltaic power generation system 20 generates power during a time period in which a certain amount of sunlight that can be generated by solar power is obtained, that is, a daytime period from sunrise to sunset, and sells the generated power in a reverse flow to the system 202. To do. On the other hand, the solar power generation system 20 charges the storage battery 204 with the electric power acquired from the system 202 at the time when there is no sunshine necessary for power generation or in a minute time period, that is, from the sunset to the next morning sunrise. In the following description, the start and end of power generation are, for example, when the amount of power generated by the solar cell 200 reaches a certain reference power and when it falls below this. The reference power can be arbitrarily set based on the configuration of the solar cell 200 through experiments and simulations.

  Further, the solar power generation system 20 supplies power from the storage battery 204 to the power load 206 when the solar battery 200 generates power. By doing so, the generated power can be sold efficiently. Furthermore, when charging the storage battery 204, the power storage control device 212 suppresses the charging current in a range in which the storage battery 204 is in a fully charged state, for example, until the solar battery 200 starts power generation. By doing so, the power to be supplied to the power load 206 during the solar power generation can be reliably charged in the storage battery 204, and the amount of power consumed by the power load 206 due to a shortage of the charge amount is generated by It is possible to avoid a situation where the power acquired (purchased) from 202 is supplemented. Further, the deterioration of the storage battery 204 can be delayed within such a range.

  FIG. 3 shows a detailed configuration example of the control unit 218 of the power storage control device 212. The control unit 218 includes a power generation state detection unit 300, a charge amount detection unit 302, and a charge control unit 304. The power generation state detection unit 300, the charge amount detection unit 302, and the charge control unit 304 correspond to a control process executed by the control unit 218.

  The power generation state detection unit 300 detects the power generation state, that is, the end and start of power generation, based on the generated power output to the system 202 when the solar cell 200 generates power. The power generation state detection unit 300 detects the end and start of power generation based on the output current of the power conditioner 208 acquired from the current sensor 209, for example. For example, when the current exceeds a preset reference value, the start of power generation is detected, and when the current falls below the reference value, the end of power generation is detected. Further, the power generation state detection unit 300 may acquire the generated power from the power conditioner 208 and detect the end and start of power generation based on this.

  The charge amount detection unit 302 detects the charge amount of the storage battery 204. For example, the charge amount detection unit 302 detects the charge amount based on the voltage of the storage battery 204 acquired from the voltage sensor 205.

  When the power generation of the solar battery 200 is completed, the charge control unit 304 determines whether the storage battery 204 has a predetermined charge amount until the next power generation starts based on the past start time and the charge amount of power generation. Charging start and end times and charging current are determined. The charging control unit 304 acquires time from a timer circuit provided in the control unit 218. In addition, the charging control unit 304 stores, in a memory in the control unit 218, a history of power generation start time determined by a procedure described later. In addition, for example, when the storage battery 204 is a storage battery charged with 10% to 90% SOC (charged state), SOC 80% is the predetermined charge amount. Charging control unit 304 then sets the determined charging current set value in converter 216 or inverter 214, and charges storage battery 204 from the determined start time to end time.

FIG. 4 is a flowchart for explaining the operation of the charging control unit 304. The procedure shown in FIG. 4 is executed, for example, when the power generation state detection unit 300 detects the end of power generation of the solar cell 200 in the time zone of one day.
The charging control unit 304 determines the power generation start time and end time (S402). Here, the details of the power generation start time and end time determination processing will be described with reference to FIG.

  FIG. 5 is a flowchart for explaining the process of determining the power generation start time and the end time. The procedure shown in FIG. 5 corresponds to the subroutine of step S402 in FIG. The charge control unit 304 acquires a history of past power generation start times and end times, for example, power generation start times and end times for the past one week (S502). The history period to be acquired can be appropriately set according to the memory capacity and the like. Next, the charging control unit 304 sets the earliest power generation start time in the past week to the power generation start time in the processing cycle, that is, the next morning power generation start time (S504). Then, the charging control unit 304 sets the latest power generation end time, that is, the time when the power generation state detection unit 300 detects the latest power generation end as the power generation end time in the processing cycle (S506).

Returning to FIG. 4, in step S < b > 404, the charging control unit 304 sets the power generation end time determined in step S < b > 402 as the charge start time and the power generation start time as the charge end time (S < b > 404). Then, the charging control unit 304 determines a charging current (S406), and charges the storage battery 204 according to the determined charging start / end time and charging current (S408).

  In addition, even if the time when the sunshine necessary for power generation can be changed due to weather conditions, the earliest power generation time from the history of a certain period in the past can be used in step S504 in FIG. This makes it possible to leave a margin for safety and to perform control closer to safety so that charging is surely terminated before power generation is started.

The charging control unit 304 calculates the charging current by, for example, the following formula F1 based on the past start time and the amount of charge of power generation. Here, a calculation formula based on a constant voltage constant current (CVCC) method is shown. The CVCC method is a method in which charging is performed at a constant current at the start of charging, and charging is performed at a constant voltage when a predetermined voltage (for example, 4.1 V (volt) in the case of a lithium ion battery) is reached.
Formula F1: CT = CP / TM / R / V
Here, each parameter is as follows.
TM: Charging time (= charging end time-charging start time)
V: DC voltage CP of storage battery 204: power capacity to be charged (= predetermined charge amount−current charge amount)
R: Ratio of change point to charging time in CVCC control CT: Charging current

Here, for example, when the system 202 is 200 V, the rated output of the inverter 214 is 5.5 kW, the charge capacity of the storage battery 204 is 6.3 kWh, and 5.04 kWh with a discharge depth of 80% is used (that is, CP = 5.04 kWh), a specific example is shown in which charging starts at 23:00 and ends charging at 6:00 the next morning. Here, it is assumed that V = 180 V and R = 80%. Then, the charging current CT is as follows.
CT = 5040/7 / 0.8 / 180 = 5 (A)
According to such a charging current, the storage battery 204 can be charged to an 80% charged state in 7 hours from 23:00 to 6:00.

  Here, for example, when charging is performed with the maximum possible current when the system 202 is 200 V and the rated output of the inverter 214 is 5.5 kw, the charging current becomes 30.55 A. Further, the charging current when the charging capacity of the storage battery 204 is 6.3 kWh and the voltage is 180 V is 35 A. When compared with these, the charging current obtained by the method of the present embodiment is smaller. Therefore, according to this embodiment, the charging current when charging the storage battery 204 to a predetermined charge amount can be suppressed, and the speed of deterioration of the storage battery 204 can be suppressed.

As a modification of the above formula F1, the following formula F2 in which the charging time TM is defined by the time R ′ from the start of charging to the change point of CVCC is possible.
Formula F2: CT = CP / (TM−R ′) / V

  FIG. 6 is a diagram illustrating an example of electric power when the storage battery control method of the present embodiment is executed. 6A and 6B show an example in which the solar cell 200 generates power from 5:30 to 18:00, the storage battery 204 is discharged, and the storage battery 204 is charged from 18:00 to 5:30 in the next morning. It is.

  FIG. 6A shows a transition 60 of the power consumption and a transition 62 of the generated power when the horizontal axis represents elapsed time and the vertical axis represents the power consumption of the power load 206 and the generated power of the solar cell 200. Here, power for charging the storage battery 204 is included in the power consumption.

  On the other hand, FIG. 6B shows the case where the positive direction of the vertical axis is the power to be purchased from the system 202 (power purchase), and the negative direction is the power to be sold by reverse flow to the system 202 (power sale). A transition 64 of power charged in the storage battery 204, a transition 66 of power consumption acquired from the system 202 and consumed by the power load 206, and a transition 68 of generated power sold to the system 202 are shown. As shown in FIG. 6B, in the time zone from 5:30 to 18:00 when power generation is performed, all generated power is sold (68).

  Here, for comparison with the present embodiment, FIG. 7 shows an example of a case in which the power consumption of the power load is covered by solar power generation and the surplus is sold to the system in a system that does not use a storage battery. FIG. 7A corresponds to FIG. 6A and shows a transition 60 ′ of power consumption and a transition 62 of generated power. Here, the transition 62 of the generated power is the same as in the case of FIG. FIG. 7B corresponds to FIG. 6B, and shows a transition 66 ′ of power consumption acquired from the system 202 and consumed by the power load 206, and a transition 68 ′ of generated power sold to the system 202. Show. In FIG. 7B, in the time zone from 5:30 to 18:00 during power generation, the electric power indicated by the hatched portion in 62 of FIG. . Thus, when not using a storage battery, all generated electric power is not sold. In this regard, as described above, according to the present embodiment, since all the generated power can be sold, the economic merit for the user can be improved.

  In addition, according to the present embodiment, charging is performed while suppressing the charging current so that the necessary amount of charge can be achieved by utilizing the entire time period from the end of power generation to the start, so that the deterioration of the storage battery can be delayed. it can.

[Modification 1]
In the first modification, when the power generation end time is earlier than a predetermined time, the charging control unit 304 sets the charging start time as the predetermined time. In general, the power charge of the system 202 varies depending on the time zone. For example, a relatively expensive rate is set in the time zone including the daytime from 6:00 to 23:00, and from 23:00 to 6:00 the next morning. There are cases where relatively inexpensive rates are set. In such a case, when the power generation end time is earlier than the start time of the inexpensive charge time zone, if charging is started from the power generation end time, power is purchased at an expensive charge, and the economic merit is reduced. In order to avoid such a situation, in this embodiment, the start time of charging is set to the start time of an inexpensive toll zone. By doing so, it is possible to avoid impairing the economic merit.

In the first modified example, instead of or in addition to the above, when the power generation start time is later than a predetermined time, the charging control unit 304 sets the charging end time as the predetermined time. For example, when the power generation start time is later than the end of the inexpensive charge time zone, if charging is performed until the power generation start time, power is purchased at an expensive charge. Therefore, in this case, in this embodiment, the end time of charging is set to the end time of an inexpensive toll time zone. By doing so, it is possible to avoid impairing the economic merit.

  FIG. 8 is a flowchart for explaining the power generation start time and end time determination processing in the first modification. The procedure shown in FIG. 8 is a modification of the procedure shown in FIG. 5, and corresponds to the subroutine of step S402 in FIG.

The charging control unit 304 acquires, for example, the power generation start time and end time for the past one week from the past history (S802). Next, the charging control unit 304 sets the earliest power generation start time in the past week to the variable “A” (S804), and the most recent power generation end time, that is, the power generation state detection unit 300 detects the latest power generation end time. The time is set to a variable “B” (S806).

If the power generation start time set in the variable “A” is later than the power generation start time threshold, that is, the end time of the inexpensive toll time zone (YES in S808), the charging control unit 304 includes the power generation start time threshold, That is, the end time of the inexpensive charge time zone is set as the power generation start time in the processing cycle (S810). On the other hand, when the power generation start time set in the variable “A” is equal to or earlier than the power generation start time threshold (NO in S808), the charging control unit 304 sets the power generation start time set in the variable “A”, that is, The earliest power generation start time in the past week is set as the power generation start time in the processing cycle (S811).

Next, when the power generation end time set in the variable “B” is earlier than the power generation end time threshold, that is, the start time of the inexpensive toll time zone (YES in S812), the charging control unit 304 includes the power generation end time threshold, That is, the start time of the inexpensive charge time zone is set as the power generation end time in the processing cycle (S814). On the other hand, when the power generation end time set in the variable “B” is equal to or later than the power generation end time threshold (NO in S812), the charging control unit 304 sets the power generation end time set in the variable “B”, that is, The latest power generation end time is set as the power generation end time in the processing cycle (S816).

  By determining the charge start time and the charge end time based on the power generation end time and the power generation start time set by such a procedure, when the power generation end time is earlier than the start time of the relatively inexpensive fee period The charge start time can be set to the start time of an inexpensive charge time zone, and when the power generation start time is earlier than the end time of the relatively inexpensive charge time zone, the charge end time is set to the end time of the inexpensive charge time zone Can be set. By doing so, it is possible to avoid impairing the economic merit.

[Modification 2]
In the second modification, the charging control unit 304 obtains the charging start time based on information acquired from another device. The information acquired from another device is, for example, weather information acquired from another server device via a public communication line such as the Internet.

  FIG. 9 shows a configuration example of the photovoltaic power generation system 20 in the second modification. The configuration example in FIG. 9 is the same as the configuration example shown in FIG. 2, the control device 90 configured to be able to communicate with the control unit 218 of the power storage control device 212 by wireless or wired, the public communication line 92 to which the control device 90 is connected, In addition, a server 94 connected to the public communication line 92 is added. The same components as those in FIG. 2 are denoted by the same reference numerals as those in FIG.

  In the second modification, the control device 90 is an information processing device such as a personal computer, for example. The public communication line 92 is, for example, an internet line. The server 94 is a server of a business operator that provides weather information. In such a configuration, the control device 90 acquires the latest weather information from the server 94 via the public communication line 92. Then, the control device 90 sends the acquired weather information to the control unit 218.

  Then, in the control unit 218, the charging control unit 304 determines the power generation start time based on the latest weather information instead of or in addition to the power generation start time in the past fixed period (for example, one week). For example, if the most recent weather information indicates that the next day's weather is cloudy or rainy, that is, if the time for obtaining sunshine is likely to be delayed, a constant value is set for the earliest power generation start time in the past week. The added time is set as the power generation start time. The constant value is, for example, an arbitrary value that is several minutes to several tens of minutes and is determined in advance. By doing so, the time when power generation is actually started can be accurately predicted, and efficient charging becomes possible.

  FIG. 10 is a flowchart for explaining the power generation start time and end time determination processing in the second modification. The procedure shown in FIG. 10 is a modification of the procedure shown in FIG. 5 and corresponds to the subroutine of step S402 in FIG. The charging control unit 304 acquires weather information for the next day (S1002). Then, the charging control unit 304 acquires, for example, the power generation start time and end time for the past one week from the past history (S1003). Next, the charging control unit 304 calculates the power generation start time in the processing cycle from the earliest power generation start time and weather information in the past week (S1004). Then, the charging control unit 304 sets the latest power generation end time, that is, the time when the power generation state detection unit 300 detects the latest power generation end as the power generation end time in the processing cycle (S1006).

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each means, each step, etc. can be rearranged so that there is no logical contradiction, and a plurality of means, steps, etc. can be combined or divided into one. .

  As described above, according to the present embodiment, the storage battery can be charged with a charging current that can efficiently sell the power generated by solar power generation and can suppress the deterioration rate of the storage battery.

20: Solar power generation system 200: Solar battery 202: System 204: Storage battery
206: Power load 212: Power storage control device 218: Control unit 300: Power generation state detection unit 302: Charge amount detection unit 304: Charge control unit

Claims (8)

A power generation state detection unit that detects at least the start and end of the power generation based on the generated power output to the grid when the solar cell generates power;
A charge amount detection unit that detects a charge amount of a storage battery that is charged by a charging current from the system and supplies power to a power load;
At the start of charging, the charging end time and charging current of the storage battery are determined based on the past start time of the power generation and the charge amount so that a predetermined charge amount is obtained until the next generation of power generation is started. And a charge control unit for charging the storage battery. In claim 1,
The charging control unit is a control device in which the power generation end time is set as the charging start time, and the power generation start time is set as the charging end time.   In claim 1,
  The charge control unit obtains the start time of the charge based on one or both of the end time of the power generation, the first time, and information acquired from another device.
Control device.   In claim 3,
  When the power generation end time is earlier than the first time, the charge control unit sets the charge start time as the first time.
Control device. In any of claims 1, 3, or 4
When the start time of the power generation is later than a second time, the charge control unit is a control device that sets the end time of the charge as the second time. In any one of Claims 1 thru | or 5,
The said power generation state detection part is a control apparatus which acquires the said generated electric power from the electric current between the said solar cell and the said system | strain.   A control system comprising the solar cell, storage battery, and control device according to claim 1. Detecting at least the start and end of the power generation based on the generated power output to the grid when the solar cell generates power;
Detecting a charge amount of a storage battery that is charged by a charging current from the system and supplies power to an electric load; and
At the start of charging, the charging end time and charging current of the storage battery are determined based on the past start time of the power generation and the charge amount so that a predetermined charge amount is obtained until the next generation of power generation is started. And a step of charging the storage battery.

Images