JP2016208660A - Control device and control method for DC power supply system - Google Patents

Abstract

An object of the present invention is to maintain a high SOC of a storage battery while effectively utilizing surplus power of a solar power generation device. A control device 52 of a DC power supply system 10 includes a solar power generation device 30 that generates power to be supplied to a communication device 20 (load), and is consumed by a load among the power generated by the solar power generation device 30. The DC power supply system 10 is provided with a storage battery 40 for charging surplus power that is not used and supplying power to the communication device 20 by discharging. The control device 52 includes a control unit 53 that controls the discharge of the storage battery 40 so that the SOC of the storage battery 40 becomes the return SOC (set level) before the charging of the storage battery 40 is started every day. The SOC is the SOC of the storage battery 40 that can charge the storage battery 40 with the maximum surplus electric energy that can be generated in one day in a predetermined period of two days or more. [Selection] Figure 2

Description

  The present invention relates to a control device and a control method for a DC power supply system, and more specifically, to a control device and a control method provided in a DC power supply system including a solar power generation device.

  In recent years, the use of natural energy such as solar power generation has attracted attention, and solar power generation devices are often installed in facilities and houses. At present, most of the DC power generated by the photovoltaic power generation apparatus is converted into AC by a power conditioner and used. In this case, since there are many devices and facilities that operate with direct current, a DC-AC-DC conversion loss occurs. In order to reduce this conversion loss, a direct-current power supply system is drawing attention (for example, see Patent Document 1 below).

  An outline of a conventional DC power supply system for a radio base station will be described with reference to FIG. As shown in FIG. 1, a conventional DC power supply system 1 includes a photovoltaic power generation device 3, a storage battery 4, a rectifier 5 that converts AC power from a commercial power source 6 into DC power, and outputs DC power (arrows). AR1 to AR3) is provided with a communication device (load) 2 supplied. The solar power generation device 3 is directly connected to, for example, a 48V bus (conceptually shown as a node N in FIG. 1), and the generated power of the solar power generation device 3 is preferentially supplied to the communication load 2.

JP 2014-42417 A

  If a power conditioner is used for a solar power generation device, when the generated power exceeds the load on the facility, it can be effectively utilized by, for example, flowing backward to the grid. However, in the DC power supply system, when the amount of power generated by the photovoltaic power generation device exceeds the load on the facility, surplus power is released as heat and cannot be used effectively. As a means to solve this, it is conceivable to use surplus power of the solar power generation device by charging / discharging the storage battery. However, the storage battery of communication equipment (such as a base station for wireless communication) is normally charged in a high state from the viewpoint of disaster countermeasures. It is desirable that In order to charge the surplus power of the photovoltaic power generator, it is necessary to reduce the charging rate of the storage battery (hereinafter referred to as SOC (State Of Charge)) in advance. From the viewpoint of. Currently, no clear algorithm has been proposed to determine the appropriate SOC for a storage battery.

  The present invention has been made in view of the above problems, and provides a control device and a control method for a DC power supply system that can maintain the SOC of a storage battery high while effectively utilizing surplus power of a solar power generation device. The purpose is to do.

  A control device of a DC power supply system according to one aspect of the present invention charges a solar power generation device that generates power to be supplied to a load, and surplus power that is not consumed by the load among the power generated by the solar power generation device. And a storage battery for supplying power to the load by discharging, and a control device provided in the DC power supply system, the SOC of the storage battery is set every day before the charging of the storage battery is started The control means for controlling the discharge of the storage battery so as to reach a level, the set level of the storage battery capable of charging the storage battery with the maximum surplus electric energy that can be generated in one day of a predetermined period of two days or more SOC.

  A control method according to an aspect of the present invention includes a solar power generation device that generates power to be supplied to a load, and a surplus power that is not consumed by the load among the power generated by the solar power generation device and is loaded by discharging. And a storage battery for supplying power to the storage battery, and a control method executed by a direct-current power supply system that controls the discharge of the storage battery so that the SOC of the storage battery reaches a set level before the charging of the storage battery is started And a step of repeating the controlling step every day, and the set level can charge the storage battery with the maximum surplus electric energy that can be generated in one day of a predetermined period of two days or more. SOC of a storage battery.

  According to the control device and the control method of the DC power supply system described above, the storage battery is discharged so that the SOC of the storage battery reaches a set level every day before the charging of the storage battery is started. If the SOC of the storage battery is discharged to the set level, the surplus power generated in one day can be charged to the storage battery. Therefore, the surplus power of the solar power generation device can be used effectively. Here, the set level is the SOC of the storage battery that can charge the storage battery with the maximum surplus electric energy that can be generated in one day in a predetermined period of two days or more. The set level may be set as high as possible, and may be, for example, the upper limit value of the SOC of the storage battery that can charge the storage battery with the maximum surplus electric energy that can be generated in one day. For example, in this way, even if it is a long period of two days or more, the photovoltaic power generation apparatus is simply executed by discharging the storage battery every day so that the SOC of the storage battery becomes a set level. The SOC of the storage battery can be maintained high while effectively utilizing the surplus power.

  The maximum surplus power amount may be determined as the amount of power obtained by subtracting the minimum power consumption amount that can be consumed by the load from the maximum power generation amount that can be generated by the photovoltaic power generation apparatus in one day of the predetermined period. By determining the maximum surplus power amount in this way, a more appropriate setting level can be obtained.

  The maximum power generation amount may be a power amount calculated based on past weather information at the installation point of the solar power generation device. By calculating the maximum power generation amount in this way, a more appropriate setting level can be obtained.

  The control means may cause the storage battery to discharge an amount of power equal to the amount of power charged to the storage battery with surplus power on that day until charging of the storage battery is started with surplus power the next day. Even with such simple control, the SOC of the storage battery can be returned to the SOC of the storage battery before charging, that is, the set level.

  The control means discharges the storage battery so that the average SOC of the storage battery becomes maximum after the storage battery is charged with surplus power on the day until the storage battery starts charging with surplus power the next day. May be controlled. Thereby, the state where SOC of a storage battery is high can be maintained for a long time.

  The control device of the DC power supply system further includes detection means for detecting that surplus power is no longer generated in a time zone in which the photovoltaic power generator can generate power, and the control means is electrically connected to the load and the storage battery. Control means for controlling the discharge of the storage battery by controlling the output voltage of the rectifier that supplies power toward the load and the storage battery, and when the detection means detects that no surplus power is generated, the output of the rectifier You may control the output voltage of a rectifier so that a voltage may become equal to the voltage of a storage battery. Thereby, the state where the SOC of the storage battery is high at the time when charging with surplus power is completed can be maintained for a long time.

  The control device of the DC power supply system further includes a calculation unit that calculates a time required for the storage battery to discharge the amount of power equal to the amount of power charged to the storage battery by surplus power on the day, and the control unit calculates Based on the time calculated by the means, the discharge of the storage battery may be completed immediately before the storage battery is charged with surplus power the next day. Thereby, for example, since the timing of discharge can be delayed as much as possible, a state where the SOC of the storage battery is high can be maintained for a long time.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to maintain SOC of a storage battery highly, utilizing the surplus electric power of a solar power generation device effectively.

It is a figure which shows schematic structure of the conventional DC power supply system. It is a figure showing a schematic structure of a direct-current power supply system provided with a control device concerning an embodiment. It is a figure which shows the hard block structure of a control part. 3 is a timing chart conceptually showing a first operation of the DC power supply system. It is a flowchart which shows the 2nd operation | movement of a DC power supply system. 6 is a timing chart conceptually showing a second operation of the DC power supply system. 12 is a timing chart conceptually showing a third operation of the DC power supply system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

  FIG. 2 is a diagram illustrating a schematic configuration of a DC power supply system in which the control device according to the embodiment is provided. DC power supply system 10 includes a communication device 20, a solar power generation device 30, a storage battery 40, and a rectifier 50. The control device according to the present embodiment is realized as a control device 52 included in a rectifier 50 described later.

  The communication device 20 is a load that operates by receiving power, and includes a radio base station. This load differs from a load such as a general home or office, in particular, in that DC power is consumed and in that the fluctuation of power consumption is small and can be regarded as almost constant.

  The solar power generation device 30 is a power generation device that receives direct sunlight and generates DC power having a magnitude corresponding to the amount of solar radiation, and includes a solar panel and the like. In the DC power supply system 10, the solar power generation device 30 generates power to be supplied to the communication device 20. The solar power generation device 30 generates DC power having a magnitude corresponding to the amount of solar radiation. The output voltage of the solar power generation device (solar power generation device output voltage Vpv) is set to a constant voltage (for example, 55 V).

  In the DC power supply system 10, the storage battery 40 charges power (surplus power) that is not consumed by the communication device 20 among the power generated by the solar power generation device 30. The storage battery 40 supplies power to the communication device 20 by discharging.

  The power line PL is a bus line that electrically connects the communication device 20, the solar power generation device 30, the storage battery 40, and the rectifier 50. The bus voltage is controlled to be a voltage (for example, 48 V) that does not exceed the rated voltage (for example, 57 V) of communication device 20. Power line PL includes a power line PL1 and a power line PL2. The power line PL1 is a part that connects the communication device 20 and the solar power generation device 30 to a terminal T2 of a rectifier 50 described later. The power line PL2 is a part that connects the storage battery 40 and a terminal T3 of a rectifier 50 described later.

  The rectifier 50 is a power conversion device that converts AC power into DC power and outputs it. In DC power supply system 10, rectifier 50 is electrically connected to communication device 20 and storage battery 40, converts AC power from commercial power supply 6 into DC power, and outputs the DC power to communication device 20 and storage battery 40. The rectifier 50 includes terminals T1 to T3, a rectifier 51, a control device 52, a current detector 56, a voltage detector 57, and a relay RL.

  The terminal T <b> 1 is an input terminal to which AC power is input and is connected to the commercial power source 6. The terminal T <b> 2 is an input / output terminal that receives DC power or outputs DC power, and is connected to the communication device 20 and the solar power generation device 30. Similarly to the terminal T2, the terminal T3 is an input / output terminal and is connected to the storage battery 40. Thereby, the communication apparatus 20, the solar power generation device 30, and the storage battery 40 are electrically connected through the power line PL, the terminals T2 and T3, and the relay RL. Note that the relay RL is opened to prevent overcharging of the storage battery 40, and is normally closed (conductive state).

  The rectifier 51 converts AC power input to the terminal T1 into DC power. The rectifier 51 is configured by combining, for example, a rectifier circuit and a voltage conversion circuit (a boost circuit or a step-down circuit). The voltage of the DC power output from the rectifier 51 is the output voltage of the rectifier 50 (rectifier output voltage Vrc), and can be adjusted by controlling the circuit that constitutes the rectifier 51.

  The control device 52 controls the DC power supply system 10 by controlling elements included in the rectifier 50, in particular, the rectifying unit 51. The control device 52 controls the rectifying unit 51 using, for example, a control signal.

  Control device 52 includes a control unit 53, a calculation unit 54, a storage unit 55, a current detection unit 56, and a voltage detection unit 57. Here, the control unit 53 will be described, and the calculation unit 54, the storage unit 55, the current detection unit 56, and the voltage detection unit 57 will be described in detail later.

  The control unit 53 is a part (control means) that performs overall control of the control device 52. In particular, the control unit 53 controls the discharge of the storage battery 40. The storage battery 40 is discharged by controlling the rectifier 51 to adjust the rectifier output voltage Vrc. Specifically, before the charging of the storage battery 40 is started, the control unit 53 discharges until the SOC of the storage battery 40 reaches the regression SOC. The storage battery 40 is discharged every day. The regression SOC is a value (set level) set for the SOC of the storage battery 40 in the DC power supply system 10. The regression SOC is the SOC of the storage battery 40 that can charge the storage battery 40 with the maximum surplus electric energy that can be generated in one day in the predetermined period. The regression SOC may be set as high as possible, and may be, for example, the upper limit value of the SOC of the storage battery that can charge the storage battery with the maximum surplus electric energy that can be generated in one day. The value of the regression SOC is stored in the storage unit 55. The surplus power amount is a value obtained by integrating surplus power generated in one day. The predetermined period is a period of two days or more, and may be, for example, a period of several weeks to several months or several years.

  According to the control of the control unit 53 described above, for example, before the charging of the storage battery 40 is started every day, the storage battery 40 can be discharged so that the SOC of the storage battery 40 becomes the regression SOC. If the SOC of the storage battery 40 is discharged to the return SOC, all the surplus power generated in one day can be charged to the storage battery 40. Therefore, the surplus power of the solar power generation device 30 can be used effectively. For example, the regression SOC is an upper limit value of the SOC of the storage battery 40 (that is, the highest possible SOC) that can charge the storage battery 40 with the maximum surplus electric energy that can be generated in one day in a predetermined period of two days or more. . Based on the regression SOC determined by such an algorithm, the storage battery 40 is discharged so that the SOC of the storage battery 40 becomes the regression SOC every day even for a long period of two days or longer. Only by executing the control, the SOC of the storage battery 40 can be maintained high while effectively utilizing the surplus power of the solar power generation device 30.

  The maximum surplus power amount is determined as the amount of power obtained by subtracting the minimum power consumption amount that can be consumed by the communication device 20 from the maximum power generation amount that can be generated by the solar power generation device 30 in one day of the predetermined period. Yes. The maximum amount of generated power that can be generated by the solar power generation device 30 may be the amount of power calculated based on past weather information at the installation point of the solar power generation device 30. The weather information includes, for example, solar radiation data and temperature data. Based on the past weather information and the design data (or experimental data) of the solar power generation device 30, the generated power of the solar power generation device 30 at the installation point can be predicted. The amount of generated power can be calculated. The minimum power consumption that can be consumed by the communication device 20 is calculated based on, for example, design data or experimental data of the communication device 20. As described above, since the power consumption of the communication device 20 is substantially constant, the power consumption amount (= minimum power consumption amount) of the communication device 20 can be calculated simply by adding time to the constant power consumption. Thus, by determining the maximum surplus power amount and calculating the maximum generated power amount, the regression SOC can be set to a more appropriate level.

  Here, the hardware configuration of the control unit 53 will be described with reference to FIG. As shown in FIG. 3, the control unit 53 physically includes one or more CPUs (Central Processing Units) 61, a RAM (Random Access Memory) 62 and a ROM (Read Only Memory) 63 that are main storage devices. Hardware such as a communication module 66 that is a data transmission / reception device, an auxiliary storage device 67 such as a semiconductor memory, an input device 68 that receives user input such as an operation panel (including operation buttons) and a touch panel, and an output device 69 such as a display It is comprised as a computer provided with. The function of the control unit 53 is, for example, by reading one or a plurality of predetermined computer software (programs) on hardware such as the CPU 61 and the RAM 62, thereby controlling the communication module 66, the input device 68, This can be realized by operating the output device 69 and reading and writing data in the RAM 62 and the auxiliary storage device 67.

[First control]
An example of the control method executed by the control unit 53 described above will be described. In this control, the control unit 53 causes the storage battery 40 to discharge an amount of power equal to the amount of power charged in the storage battery 40 with surplus power on that day until charging of the storage battery 40 is started with surplus power the next day. Such a simple control becomes possible by setting the above-described regression SOC to an appropriate level.

  FIG. 4 is a timing chart conceptually showing the operation of the DC power supply system 10. In FIG. 4, “SOC” indicates the SOC of the storage battery 40. “Vpv” indicates the photovoltaic power generator output voltage Vpv of the photovoltaic power generator 30. “Vrc” indicates the rectifier output voltage Vrc of the rectifier 50. “Pload” indicates the power consumption of the communication device 20. “Ppv” indicates the generated power of the solar power generation device 30. Note that the timing chart of FIG. 4 is conceptually shown and does not necessarily match the actual one. For example, “Ppv” actually changes, for example, in a curve according to changes in solar radiation, and other values also change accordingly.

Explaining an example of the condition, the maximum value (maximum output) of the generated power Ppv of the solar power generation device 30 is 100 W, and the power consumption Pload of the communication device 20 is 70 W. The regression SOC is 60%, and the SOC of the storage battery 40 is initially the regression SOC. The storage battery voltage Vbat (regression voltage V ₀ ) when the SOC of the storage battery 40 is equal to the regression SOC is 49V. Rectifier output voltage Vrc of the rectifier 50 is set to a regression voltage _{V 0.} The photovoltaic power generator output voltage Vpv is set to 55V. It is assumed that the generated power Ppv of the solar power generation device 30 is the maximum output when the weather is fine and the amount of solar radiation is the largest during the day.

  First, at time t1, the solar power generation device 30 starts power generation, and the generated power Ppv starts to increase. The time t1 is the sunrise time, for example, around 5:00 to 7:00. Since the generated power Ppv here is smaller than the power consumption Pload of the communication device 20, all the generated power Ppv is consumed by the communication device 20. Note that only the generated power Ppv of the solar power generation device 30 is insufficient with respect to the power consumption Pload of the communication device 20, but the amount of power (insufficient power) is covered by the rectifier 50. This is because the storage battery voltage Vbat of the storage battery 40 is equal to the rectifier output voltage Vrc of the rectifier 50, and the storage battery 40 is in a floating charge state. In the floating charge state, the SOC of the storage battery 40 is maintained at that level (that is, the regression SOC).

  At time t2, the generated power Ppv of the solar power generation device 30 exceeds the power consumption Pload of the communication device 20. The time t2 is a time after a while since sunrise, for example, around 8:00. Of the generated power Ppv of the solar power generation device 30, the power that exceeds the power consumption Pload of the communication device 20 is surplus power. When surplus power is generated, charging of the storage battery 40 is started, and the SOC of the storage battery 40 starts to rise. At the same time, the storage battery voltage Vbat of the storage battery 40 also starts to rise. Since the storage battery voltage Vbat exceeds the rectifier output voltage Vrc, the storage battery 40 is not in a floating charge state.

  At time t3, the generated power Ppv of the solar power generation device 30 becomes maximum. At this time, since the generated power Ppv is 100 W and the power consumption Pload of the communication device 20 is 70 W, the difference of 30 W is charged to the storage battery 40 as surplus power. After the time t3, the generated power Ppv of the solar power generation device 30 starts to decrease.

  At time t4, the generated power Ppv of the solar power generation device 30 is lower than the power consumption Pload of the communication device 20. The time t4 is a time when the sunset has begun, for example, around 16:00. Of the power consumption Pload of the communication device 20, the amount of power that exceeds the power generation power Ppv of the solar power generation device 30 is insufficient power. When the insufficient power is generated, the storage battery 40 starts to be discharged. This is because the storage battery voltage Vbat of the storage battery 40 is larger than the rectifier output voltage Vrc of the rectifier 50 due to charging after time t2. When the discharge of the storage battery 40 is started, the SOC of the storage battery 40 starts to decrease. At the same time, the storage battery voltage Vbat of the storage battery 40 also starts to decrease.

  At time t5, the power generation by the solar power generation device 30 ends, and the generated power Ppv becomes zero. The time t5 is, for example, around 17:00 to 19:00. Here, since the storage battery voltage Vbat of the storage battery 40 is still higher than the rectifier output voltage Vrc of the rectifier 50, the discharge of the storage battery 40 and the decrease in the SOC continue.

  At time t6, the storage battery voltage Vbat of the storage battery 40 decreases to the rectifier output voltage Vrc of the rectifier 50. Thereby, SOC of the storage battery 40 turns into regression SOC. Moreover, the storage battery 40 will be in a floating charge state. The power consumption of the communication device 20 is covered by the power from the rectifier 50.

  After time t6, since the storage battery 40 is in a floating charge state, the SOC of the storage battery 40 is maintained at the regression SOC. Thus, the control by the control device 52 on the first day is completed, and the same process (that is, the process after time t1) is executed again on the next day.

  As described above, according to the control described with reference to the timing chart of FIG. 4, the storage battery 40 is charged with the surplus power of the day until the charging of the storage battery 40 is started with the surplus power the next day (until time t <b> 1). An amount of power equal to the amount of power (the amount of power charged during times t2 to t4) (the amount of power discharged during times t4 to t6) is discharged from the storage battery 40. By setting the regression SOC to an appropriate level, even with such simple control, the SOC of the storage battery 40 is kept high so that the SOC of the storage battery 40 does not fall below the regression SOC. Can be used effectively.

[Second control]
Next, another example of the control method executed by the control unit 53 will be described. In this control, after the discharge of the storage battery 40 by the surplus power is completed on the same day, the control unit 53 has the maximum SOC level of the storage battery 40 until the discharge of the storage battery 40 is started by the surplus power the next day. Thus, the discharge of the storage battery 40 is controlled. In such control, a calculation unit 54, a current detection unit 56, and a voltage detection unit 57 shown in FIG. 2 are further used.

  The current detection unit 56 functions as a detection unit that detects that surplus power is not generated in a time zone in which the solar power generation device 30 can generate power. This detection is performed, for example, by detecting a current flowing from the node N2 toward the terminal T2. When such a current is detected, the surplus power is not generated, so that the rectifier 50 starts to output power toward the communication device 20 or the storage battery 40 starts to discharge. It is because it shows.

  The current detection unit 56 also detects a current between the rectification unit 51 and the node N2. When such a current is detected, a state in which power is supplied from the rectifier 50 to the communication device 20 instead of supplying power to the communication device 20 by discharging the storage battery 40 is shown. In other words, the storage battery 40 is in a floating charge state and its SOC is maintained.

  When it is detected by the current detection unit 56 that surplus power is no longer generated, the control unit 53 causes the rectifier output voltage of the rectifier 50 so that the rectifier output voltage Vrc of the rectifier 50 becomes equal to the storage battery voltage Vbat of the storage battery 40. Vrc is controlled.

  The calculation unit 54 is a time (discharge time) required for the storage battery 40 to discharge an amount of power equal to the amount of power charged in the storage battery 40 by surplus power on the day (hereinafter, also simply referred to as “surplus power amount”). Is a part (calculation means) for calculating. The calculation of the surplus power amount charged in the storage battery 40 is performed based on the current value and the voltage value detected by the current detection unit 56 and the voltage detection unit 57. The calculation of the surplus power may be performed by the control device 52.

  Specifically, first, the calculation unit 54 calculates the value of the current flowing from the terminal T2 toward the node N2 and the voltage value detected by the voltage detection unit 57 among the current values detected by the current detection unit 56. By multiplying, the charging power of the storage battery 40 is calculated. Then, the surplus power amount charged in the storage battery 40 is calculated by multiplying the charging power by the charging time. Furthermore, the calculation unit 54 calculates the discharge time by dividing the surplus power amount charged in the storage battery 40 by the power consumption Pload of the communication device 20. That is, this discharge time is the time taken for the communication device 20 to consume surplus power charged in the storage battery 40.

  The control unit 53 controls the discharge of the storage battery 40 based on the discharge time calculated by the calculation unit 54 so that the discharge of the storage battery 40 is completed before the storage battery 40 is charged with surplus power the next day. To do.

  The control described above will be described with reference to FIGS. FIG. 5 is a flowchart showing an example of processing executed by the control device 52, and FIG. 6 is a timing chart conceptually showing the operation of the DC power supply system 10. Examples of conditions are the same as those in the flowchart described above with reference to FIG. Further, the description of the same parts as those described above with reference to FIG. 4 is omitted.

  First, the process executed in steps S1 to S5 will be described. These processes are executed between times t12 and t15.

  First, the control device 52 determines whether or not it is a time zone in which surplus power can be generated (a time zone between times t12 and t14) (step S1). The time zone in which surplus power can be generated is 8:00 to 16:00, and is stored in advance in the storage unit 55, for example. When it is a time zone in which surplus power can be generated (step S1: YES), the control device 52 advances the process to step S2. When that is not right (step S1: NO), the control apparatus 52 advances a process to step S6.

  In step S2, control device 52 determines whether or not a decrease in bus voltage (voltage of power line PL) is detected. This determination is made based on a change in voltage detected by the voltage detector 57. For example, at time t12, the generated power Ppv of the solar power generation device 30 exceeds the power consumption Pload of the communication device 20, and surplus power is generated. Therefore, the SOC of the storage battery 40 and the storage battery voltage Vbat begin to increase. When the generated power Ppv of the solar power generation device 30 is 90 W, 70 W of the power is supplied to the communication device 20, and the remaining 20 W of power is charged to the storage battery 40 as surplus power. Since the bus voltage depends on the storage battery voltage Vbat, a decrease in the bus voltage is not detected at this time. At time t13, the generated power Ppv of the solar power generation device 30 becomes maximum. At this time, since the generated power Ppv is 100 W and the power consumption Pload of the communication device 20 is 70 W, the difference of 30 W is charged to the storage battery 40 as surplus power. On the other hand, at time t14, the generated power Ppv of the solar power generation device 30 is lower than the power consumption Pload of the communication device 20, and therefore no surplus power is generated. At that time, the discharge of the storage battery 40 is started, and the bus voltage decreases. When a decrease in bus voltage is detected (step S2: YES), the control device 52 advances the process to step S3. When that is not right (step S2: NO), the control apparatus 52 returns a process to step S1 again. After time t12 and before reaching time t14, the processes of steps S1 and S2 are repeatedly executed.

  In step S3, the control device 52 determines whether or not there is a rectifier output. For example, when the current detection unit 56 detects that the magnitude of the current from the rectifier 50 toward the node N2 exceeds a predetermined current, the control device 52 outputs the power from the rectifier 50 (there is a rectifier output). Judge. The state where such a current is flowing indicates that the storage battery 40 is in a floating charge state. On the other hand, when there is no rectifier output, since the power consumption Pload of the communication device 20 is covered by the discharge of the storage battery 40, the SOC of the storage battery 40 is reduced. Therefore, the process proceeds so that control for increasing the rectifier output voltage Vrc (for example, if the storage battery voltage Vbat is increased to 51 V, the rectifier output voltage Vrc is increased to 51 V) is executed. It is done. Specifically, when there is no rectifier output (step S3: NO), the control device 52 advances the process to step S4. Otherwise, if there is a rectifier output (step S3: YES), the control device 52 returns the process to step S1 again.

  If it is determined in step S3 that there is no rectifier output, the controller 52 determines whether or not the rectifier output voltage Vrc is less than a threshold value (step S4). The threshold value here is the upper limit value (57 V) of the operating voltage of the communication device 20, and is stored in advance in the storage unit 55, for example. When rectifier output voltage Vrc is less than the threshold value (step S4: YES), control device 52 advances the process to step S4. When that is not right (step S4: NO), the control apparatus 52 returns a process to step S1 again.

  If it is determined in step S4 that the rectifier output voltage Vrc is less than the threshold value, the control device 52 increases the rectifier output voltage Vrc by ΔV (step S5). ΔV is set to about 0.1 V, for example, so that the rectifier output voltage Vrc can be finely adjusted. After the process of step S4 is completed, the control apparatus 52 returns a process to step S1 again. By repeatedly executing the processing of steps S1 to S4, the rectifier output voltage Vrc becomes equal to or higher than the storage battery voltage Vbat (for example, 51 V). Since these processes are executed in a short time by computer control, they are completed with almost no time elapsed from the time t14. Therefore, in FIG. 6, the illustration of the state in which the rectifier output voltage Vrc increases after time t14 is omitted.

  Next, the process executed in steps S6 to S11 will be described. These processes are executed between time t15 and time t21 (time t21 is the time of the next day and corresponding to the time t11 of the day).

  If it is determined in the previous step S1 that it is not a time zone in which surplus power can be generated, the control device 52 calculates the amount of charging power (step S6). Specifically, control device 52 or calculation unit 54 calculates the amount of power charged in storage battery 40 based on the current value and the voltage value detected by current detection unit 56 and voltage detection unit 57. Since this calculation is performed when the time zone (time t11 to t14) in which surplus power can be generated is passed, the amount of power charged in the storage battery 40 by the surplus power of the day is obtained.

  Next, the control device 52 calculates the discharge start time (step S7). Specifically, the calculation unit 54 calculates the discharge time by dividing the amount of power charged in the storage battery 40 by the power consumption Pload of the communication device 20. And the calculation part 54 calculates the time (after-mentioned time t16) only the calculated discharge time from the start time (time t21) of the time slot | zone when surplus electric power can generate | occur | produce on the next day as a discharge start time.

  For example, assuming that the rectifier output voltage Vrc (= storage battery voltage Vbat) is 51 V, the amount of power (charge amount) charged in the storage battery 40 at that time is 1000 Wh, and the charge amount at a regression voltage of 49 V (ie, regression SOC) is 860 Wh. If there is (the value of this charge amount is stored in the storage unit 55), it can be seen that the amount of power of 140 Wh is the amount of power charged by surplus power. In this case, the time of 2 hours is calculated as the discharge time by dividing 140 Wh by 70 W, which is the power consumption Pload of the communication device 20.

  Next, the control device 52 determines whether or not it is a discharge start time (step S8). Specifically, it is determined whether or not the current time is the discharge start time calculated in the previous step S6. If it is the discharge start time (step S8: YES), the control device 52 advances the process to step S8. When that is not right (step S8: NO), the control apparatus 52 performs the process of step S7 again, for example after the control apparatus 52 waits for a process only for predetermined | prescribed wait time. For example, while the processes of steps S6 to S8 are being performed, at time t15, the power generation of the solar power generation device 30 ends, and the generated power Ppv becomes zero.

When it is determined that the discharge start time in step S8, the controller 52 sets the rectifier output voltage Vrc regression voltage V ₀ (step S9). And control device 52 judges whether charge of a storage battery started (Step S10). When charging of the storage battery starts (step S10: YES), the control device 52 advances the process to step S10. When that is not right (step S10: NO), the control apparatus 52 waits for a process, for example only for predetermined wait time, Then, performs the process of step S9 again.

  In step S11, the control device 52 determines whether or not charging of the storage battery is completed. For example, the control device 52 determines that the charging of the storage battery 40 is completed immediately before the start time (time t21) of the time zone in which surplus power can be generated. Alternatively, if the SOC of the storage battery 40 is configured to be detectable, it may be determined that charging of the storage battery 40 has been completed in response to the SOC of the storage battery 40 becoming a regression SOC. In any case, when the charging of the storage battery 40 is completed, the SOC of the storage battery 40 becomes a regression SOC. When charging of the storage battery is completed (step S11: YES), the control device 52 returns the process to step S1 again. Otherwise (step S11: NO), for example, after waiting for a predetermined wait time, the process of step S11 is executed again.

  As described above, according to the control described with reference to the flowchart of FIG. 5 and the timing chart of FIG. 6, after the discharge of the storage battery 40 is completed with surplus power on the same day (step S1 → S2, time 14), surplus power on the next day. Thus, the SOC of the storage battery 40 is maintained as high as possible in the time period between the start of discharging of the storage battery 40 (steps S6 to S11, time t21). This also means that the discharge of the storage battery 40 is controlled so that the average SOC level of the storage battery 40 in that time zone (the average value of the SOC between time t14 and time t21) becomes maximum. .

  Specifically, when it is detected by the current detection unit 56 that surplus power is no longer generated (step S2), the control unit 53 causes the rectifier output voltage Vrc of the rectifier 50 to be equal to the storage battery voltage Vbat. 50 rectifier output voltage Vrc is controlled. Thereby, the state where the SOC of the storage battery 40 is high at the time when charging with surplus power is completed (time t14) can be maintained for a long time.

  Further, the control unit 53 discharges the storage battery 40 based on the discharge time calculated by the calculation unit 54 so that the discharge of the storage battery 40 is completed before the charging of the storage battery 40 is started by surplus power the next day. Is controlled (steps S7 to S11). Thereby, since the timing of discharge of the storage battery 40 can be delayed as much as possible (time t14 → time t16), the state where the SOC of the storage battery 40 is high can be maintained for a long time.

  Therefore, in the communication device 20 including a radio base station or the like, high-efficiency power supply by the DC power supply system 10 is possible, and power generation by the solar power generation device 30 is ensured while ensuring the SOC of the storage battery 40 as a backup power source. It is possible to make maximum use of the amount, and it is possible to reduce power demand while considering disaster countermeasures such as power outages. Further, by uniquely determining the charge / discharge control regardless of the environment or weather, it is possible to keep costs low without adding new hardware such as a pyranometer, which is external information for charge / discharge control.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, the following modifications may be used as the embodiment of the present invention.

  That is, in the above embodiment, the charge / discharge control of the storage battery 40 by the control of the rectifier output voltage Vrc has been described. However, when the wireless base station is provided with the charge / discharge control device for the storage battery 40, the rectifier output voltage Vrc You may implement by charge / discharge control of the storage battery 40 using the charging / discharging control apparatus instead of control.

  Moreover, although the said embodiment was equipped with the current sensor (current detection part 56) and the voltage sensor (voltage detection part 57) inside the rectifier 50, you may install these outside the rectifier 50.

  In the above embodiment, information from the outside such as weather forecast and solar radiation amount prediction is not received, and the regression SOC is determined from past statistical information. And the regression SOC may be determined. For example, when it is raining tomorrow and power generation cannot be expected (that is, when it is predicted that no surplus power will be generated), it is possible to secure a backup time during a disaster by setting the regression SOC to 100%. It is desirable from the viewpoint of disaster countermeasures.

  Moreover, although the said embodiment was what utilizes the surplus electric power of the solar power generation device 30 in the direct-current power supply system 10, this does not need to be limited to a wireless base station.

  Moreover, in the said embodiment, as an example, the upper limit of SOC of the storage battery 40 which can charge the storage battery 40 with the maximum surplus electric energy which can generate | occur | produce in the 1st of a predetermined period was set as regression SOC. When such a regression SOC (hereinafter referred to as “first regression SOC”) is set, the power generation amount of the solar power generation device 30 can be maximized on a daily basis. When the power consumption Pload of the battery 40 is small, the discharge is not completed in the time zone in which the surplus power is not generated (for example, from time t4 in FIG. 4 to time t2 on the next day), and the SOC of the storage battery 40 is It may not return to 1 regression SOC. In such a case, the power generation amount of the solar power generation device 30 is estimated from past data on an annual basis, taking into consideration the discharge power amount of the storage battery 40 determined by the communication load (power consumption of the communication device 20), The regression SOC may be set to a second regression SOC that is lower than the first regression SOC so that surplus power can be charged. Specifically, for example, using the value obtained by subtracting the amount of discharge power determined by the communication load from the maximum surplus power amount is the amount of power per day that may exceed the first regression SOC, By multiplying the amount of electric power that may exceed the number of consecutive clear days recorded at the installation site, the maximum electric energy that may exceed the first regression SOC is obtained, and the amount of the maximum electric energy is What is necessary is just to obtain | require SOC which made low regression SOC of 1 as 2nd regression SOC.

  For example, as shown in FIG. 7, after the time t4 when surplus power is no longer generated, after the time t31 when surplus power starts to be generated on the next day, the storage battery 40 is stored by the surplus power on the previous day. Even if the amount of power charged to 40 (the amount of power charged between times t2 and t4) cannot be discharged, if the regression SOC is set to the second regression SOC, the next day All the surplus power can be charged in the storage battery 40.

  DESCRIPTION OF SYMBOLS 10 ... DC power supply system, 20 ... Communication apparatus (load), 30 ... Solar power generation device, 40 ... Storage battery, 50 ... Rectifier, 51 ... Rectifier, 52 ... Controller, 53 ... Controller (control means), 54 ... Calculation unit (calculation unit), 55 ... storage unit, 56 ... current detection unit (detection unit), 57 ... voltage detection unit (detection unit).

Claims (8)

A solar power generation device that generates power to be supplied to a load, and a storage battery that charges surplus power that is not consumed by the load among the power generated by the solar power generation device and supplies power to the load by discharging A control device provided in a DC power supply system comprising:
Control means for controlling the discharge of the storage battery so that the SOC of the storage battery reaches a set level before the charging of the storage battery is started every day,
The set level is the SOC of the storage battery capable of charging the storage battery with a maximum surplus power amount that can be generated in one day of a predetermined period of two days or more.
Control device for DC power supply system.   The maximum surplus power amount is determined as a power amount obtained by subtracting a minimum power consumption amount that can be consumed by the load from a maximum power generation amount that can be generated by the solar power generation device in one day of the predetermined period. The control device for a DC power supply system according to claim 1.   The control device for a DC power supply system according to claim 2, wherein the maximum power generation amount is a power amount calculated based on past weather information at an installation point of the solar power generation device.   The control means causes the storage battery to discharge an amount of power equal to the amount of power charged to the storage battery by surplus power on the same day until charging of the storage battery is started by surplus power on the next day. The control apparatus of the direct-current power system of any one of these.   The control means is configured so that an average SOC level of the storage battery is maximized after charging of the storage battery is completed with surplus power on the same day until charging of the storage battery is started with surplus power on the next day. The control device for a DC power supply system according to any one of claims 1 to 4, which controls discharge of the storage battery. Detecting means for detecting that the surplus power is no longer generated in a time zone in which the solar power generation device can generate power; and
The control means is control means for controlling discharge of the storage battery by controlling an output voltage of a rectifier that is electrically connected to the load and the storage battery and supplies electric power toward the load and the storage battery, 6. The DC power supply according to claim 5, wherein when the detection unit detects that the surplus power is not generated, the output voltage of the rectifier is controlled so that the output voltage of the rectifier becomes equal to the voltage of the storage battery. System control unit. A calculation means for calculating a time required for the storage battery to discharge the amount of power equal to the amount of power charged to the storage battery by surplus power on the day,
7. The direct current according to claim 5, wherein the control unit completes the discharge of the storage battery immediately before the charging of the storage battery is started with surplus power on the next day based on the time calculated by the calculation unit. Power system control unit. A solar power generation device that generates power to be supplied to a load, and a storage battery that charges surplus power that is not consumed by the load among the power generated by the solar power generation device and supplies power to the load by discharging A control method executed by a DC power supply system comprising:
Controlling the discharge of the storage battery so that the SOC of the storage battery is at a set level before the charging of the storage battery is started;
Repeating the controlling step every day;
Including
The set level is the SOC of the storage battery capable of charging the storage battery with a maximum surplus power amount that can be generated in one day of a predetermined period of two days or more.
Control method.

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