JP2017108558A - DC power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve efficient power supply even when a power failure occurs during DC power supply.SOLUTION: When a commercial power supply for supplying electric power to a communication apparatus 400 is under a power failure condition, a controller 301 adjusts a charging amount into a storage battery 304 on the basis of a voltage based on an output voltage of a photovoltaic power generation apparatus 200 performing power supply to the communication apparatus 400. Thus, when excessive power is produced at the photovoltaic power generation apparatus 200, the storage battery 304 can be charged, thereby efficiently utilizing the excessive power.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a DC power supply system that controls DC power.

  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 various facilities and houses. This solar power generation device can charge the storage battery while supplying the generated power to facilities, equipment, and the like.

  By the way, in general, most of the DC power generated by the photovoltaic power generation apparatus is used after being converted into AC by a power conditioner.

  In this case, at the time of a power failure such as a disaster, the DC power generated by the solar power generation device is not supplied to the communication device. From the viewpoint of securing a power source in the event of a disaster, a direct current power supply system is attracting attention in order to supply generated power to a communication device even during a power failure. For example, Patent Document 1 describes a DC power supply system including a rectifier that controls charging and discharging of a storage battery by changing an output voltage.

JP 2014-42417 A

  When 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 back into the system. However, in this DC power supply system, when the amount of power generated by the photovoltaic power generation device exceeds the load on the facility, a problem arises that surplus power is released as heat and cannot be used effectively. In particular, the study of effectively using the surplus power at the time of a power outage such as a disaster has not progressed much.

  Accordingly, in order to solve the above-described problems, an object is to provide a DC power supply system that can efficiently perform power supply processing when a power failure occurs when performing DC power supply.

  In order to solve the above-described problems, a DC power supply system of the present invention includes a solar power generation device that generates power by receiving sunlight, a storage battery that receives and stores power from the solar power generation device, and solar power. In a DC power supply system that includes a power consumption target that receives power supply from a power generation device or a storage battery, if the commercial power supply that supplies power to the power consumption target is out of power, supply power to the power consumption target Voltage measuring means for measuring the voltage based on the output voltage of the solar power generation device, and control means for adjusting the charge amount for the storage battery based on the voltage measured by the measuring means.

  According to the present invention, when a commercial power supply that supplies power to a power consumption target has a power failure, the voltage measured based on the output voltage of the photovoltaic power generation apparatus that supplies power to the power consumption target Based on this, the amount of charge for the storage battery is adjusted. Thereby, when surplus electric power is born in a solar power generation device, a storage battery can be charged and surplus electric power can be used efficiently.

  The DC power supply system further includes current measuring means for measuring a current flowing between the storage battery and the power consumption target, and the control means further includes a charge amount for the storage battery based on the current measured by the current measuring means. Adjust.

  According to the present invention, since the charge amount is adjusted based on the current, for example, it can be specified that the sudden power generation amount due to the passage of clouds or the like is decreasing, and the charge amount is appropriately adjusted. be able to.

  Further, in this DC power supply system, the control means is configured such that when the voltage measured by the voltage measuring means exceeds the threshold value and the current measured by the current measuring means indicates that the storage battery is charged, Increase the amount of charge for. Thus, when it can be considered that the surplus power is generated based on the voltage, the surplus power can be effectively utilized by increasing the charge power amount of the storage battery by a certain amount from the initial value.

  The DC power supply system further includes a rectifier including a power failure sensor that detects a power failure of the commercial power supply, and the voltage measurement unit measures the voltage when it is detected that the power failure has occurred.

  In this case, the charging current value is adjusted based on the voltage measured after the power failure sensor identifies that the power failure is continuing, so the charging current value should be adjusted when surplus power is considered to be generated. Can do.

  ADVANTAGE OF THE INVENTION According to this invention, when performing a DC power supply, when a power failure occurs, a power supply process can be performed efficiently.

It is a system configuration figure showing an outline of a direct-current power supply system. It is the figure which showed transition of the relationship between the electric power generation condition and electric power bus voltage in the solar power generation device. 3 is a block diagram showing a functional configuration of a battery unit 300. FIG. It is a figure which shows the hardware constitutions of the control part. It is a flowchart which shows operation | movement of the control part 301 in this embodiment. It is a figure which shows the service securing time in this embodiment.

  Embodiments of the present invention will be described with reference to the accompanying drawings. Where possible, the same parts are denoted by the same reference numerals, and redundant description is omitted.

  An overview of a conventional DC power supply system 10 for a radio base station will be described with reference to FIG. FIG. 1 is a system configuration diagram showing an outline of a DC power supply system. As shown in FIG. 1, the DC power supply system 10 includes a rectifier 100, a solar power generation device 200, a battery unit 300, a rectifier, and a communication device 400 (load).

  The rectifier 100 is a device that converts an alternating current supplied from the commercial power supply 500 into a direct current.

  The solar power generation device 200 is a device that generates power by receiving sunlight. This solar power generation device 200 is directly connected to the 48V bus, and the power generated by the solar power generation device 200 is preferentially supplied to the communication device 400.

  Battery unit 300 includes a storage battery that can be charged and discharged. The storage battery can be charged by receiving power supply from the commercial power supply 500 via the solar power generation device 200 or the rectifier 100. Moreover, when the commercial power source 500 has a power failure, charging can be performed by receiving power supply through the solar power generation device 200. That is, the storage battery stores power by receiving power supply from the solar power generation device 200. In addition, the storage battery of the battery unit 300 supplies power to the communication device 400 when the commercial power source 500 is out of power.

  The communication device 400 is a device that receives power supply from any one of the commercial power source 500, the photovoltaic power generation device 200, and the storage battery of the battery unit 300 and executes a communication function, and a load portion that consumes power (power consumption) Subject). In the present embodiment, the communication device 400 has a function for executing wireless communication in the wireless base station, but is not limited thereto.

  In such a DC power supply system 10, when the solar power generation apparatus 200 generates power that is equal to or higher than the power consumption of the communication apparatus 400 when the commercial power supply 500 fails, power is supplied from the battery unit 300 to the communication apparatus 400. Therefore, the bus voltage becomes the output voltage of the photovoltaic power generation apparatus 200. By detecting the change in the bus voltage, it is possible to know whether there is surplus power in the photovoltaic power generation apparatus 200.

  The basis for this will be described using a test graph. FIG. 2 is a diagram illustrating a relationship between the power generation state and the power bus voltage in the solar power generation device 200.

  As shown in FIG. 2, it is recognized that there is a correlation between the power generation status (output current) of the photovoltaic power generation apparatus 200 and the bus voltage in the battery unit 300. For example, irradiation is started by the sun from about 7 o'clock in the morning, and the output current in the solar power generation device 200 increases. The output current decreases from about 12:30 to about 14:30, which is the time when the photovoltaic power generation apparatus 200 was in the shaded part, but when the shaded part is removed, the output current rises again and reaches its peak. The output current gradually decreases until sunset.

  On the other hand, in FIG. 2, it can be seen that the voltage of the power bus in the battery unit 300 draws its waveform so as to correlate with the output current of the solar power generation device 200. In this embodiment, since power is supplied from the commercial power source 500, a voltage of about 51V is constantly applied to the power bus. However, when the power generation operation of the solar power generation apparatus 200 starts, the bus It can be seen that the voltage rises and a constant voltage is applied between 53V and 54V.

  Here, when the generated power generated by the solar power generation device 200 is higher than the power consumption (load) consumed in the communication device 400, surplus power is generated. In the present embodiment, as can be seen from the relationship between the power generation status of the photovoltaic power generation apparatus 200 and the bus voltage of the battery unit 300 shown in FIG. 2, solar power generation is performed by measuring the bus voltage in the battery unit 300. The amount of power generated by the device 200 can be grasped and the presence or absence of surplus power can be determined. And about the surplus electric power, the electric power generated by the solar power generation device 200 can be efficiently used by controlling the storage battery of the battery unit 300 to be charged. Specifically, control is performed to vary the charging current value for the storage battery in the battery unit 300.

  Next, functional configurations of the rectifier 100 and the battery unit 300 according to the present embodiment will be described. FIG. 3 is a block diagram illustrating functional configurations of the rectifier 100 and the battery unit 300. As illustrated in FIG. 3, the rectifier 100 includes a power failure sensor 101 (power failure sensor) and a rectification unit 102.

  The power failure sensor 101 is a part that detects a power failure of the commercial power source 500. The power failure sensor 101 inputs the detected result to the battery unit 300. Specifically, the power failure sensor 101 inputs an “ON” signal to the battery unit 300 if the commercial power source 500 is in a power failure, and sends an “OFF” signal to the battery unit 300 if the commercial power source 500 is not in a power failure. input.

  The rectifying unit 102 is a part that converts an alternating current supplied from the commercial power supply 500 into a direct current, and outputs the converted direct current to a 48V bus connected to the rectifying unit 102.

  Subsequently, a specific configuration of the battery unit 300 will be described. The battery unit 300 includes a control unit 301 (control unit) and a storage battery 304.

  Specifically, the control unit 301 is a BMS (Battery Management System), and is a part that monitors and controls the state of the storage battery 304. The control unit 301 includes a current / voltage sensor 302 (current measurement unit, voltage measurement unit) and a switch unit 303. The current / voltage sensor 302 is a part that measures a current of a direct current (a current flowing between the storage battery 304 and the communication device 400) flowing in a bus connecting the battery unit 300 and the communication device 400. The current / voltage sensor 302 is also a part that measures the voltage of a direct current flowing in a bus connecting the battery unit 300 and the communication device 400.

  Based on the current and voltage measured by the current / voltage sensor 302, the control unit 301 performs control to increase or decrease the charge amount for the storage battery 304. That is, the control unit 301 adjusts the amount of charge for the storage battery 304 based on the current and voltage measured by the current / voltage sensor 302 as described later. The control unit 301 stores an initial charge amount, a current charge amount, and a fluctuation value (for example, 0.1 A) that is a fluctuation value (a value to be increased or decreased).

  Here, the hardware configuration of the control unit 301 will be described with reference to FIG. As shown in FIG. 4, the control unit 301 physically includes one or more CPUs (Central Processing Units) 31, a RAM (Random Access Memory) 32 that is a main storage device, and a ROM (Read Only Memory) 33. Hardware such as a communication module 34 that is a data transmission / reception device, an auxiliary storage device 35 such as a semiconductor memory, an input device 36 that receives user input such as an operation panel (including operation buttons) and a touch panel, and an output device 37 such as a display It is comprised as a computer provided with.

  The function of the control unit 301 is, for example, by loading one or a plurality of predetermined computer software (programs) on hardware such as the CPU 31 and the RAM 32, thereby controlling the communication module 34, the input device 36, This can be realized by operating the output device 37 and reading and writing data in the RAM 32, ROM 33, and auxiliary storage device 35.

  The switch unit 303 is disposed on a bus between the storage battery 304 and the photovoltaic power generation apparatus 200. In order to control the discharge of the storage battery 304 during a power failure, the switch unit 303 is turned on and off to This is the part that performs connection control. The storage battery 304 is a storage battery that can be charged and discharged.

  In the battery unit 300 configured as described above, the control unit 301 that performs charging control will be further described.

  The control unit 301 detects that the commercial power supply 500 is out of power when the value of the voltage measured by the current / voltage sensor 302 is equal to or less than a predetermined voltage value (power outage voltage value) stored in advance. When the control unit 301 detects that the commercial power supply 500 is a power failure, the control unit 301 operates the switch unit 303 to discharge the storage battery 304.

  Based on the signal input from the power failure sensor 101, the control unit 301 determines whether or not the power failure continues. When the signal input from the power failure sensor 101 is “ON”, the control unit 301 determines that the power failure continues. Further, when the signal input from the power failure sensor 101 is “OFF”, the control unit 301 determines that the power failure has not occurred (the power failure has not continued).

  When it is determined that the power failure has not continued, the control unit 301 operates the switch unit 303 to stop the power failure discharge. On the other hand, when determining that the power failure continues, the control unit 301 acquires the current and voltage measured by the current / voltage sensor 302. That is, when it is detected by the power failure sensor 101 that a power failure has occurred, the voltage and current are measured.

  Control unit 301 adjusts the amount of charge for storage battery 304 when the acquired current value is greater than or equal to a pre-stored current value (when the battery state is a power failure discharge). For example, when the solar power generation device 200 generates power more than the power (load) consumed by the communication device 400 and is being charged, the control unit 301 increases the charge amount by a minute amount stepwise. Specifically, the control unit 301 sets a value obtained by adding the fluctuation value to the current charge amount as a new charge amount. As described above, when the control unit 301 generates power more than the amount of power (load) consumed by the communication device 400 and the current indicates that the storage battery 304 is charged, the control unit 301 determines the amount of charge for the storage battery 304. increase. As long as the condition for increasing the amount of charge is met, the control unit 301 repeats at a predetermined control interval. Note that the amount of charge to be increased may be constant or variable.

  Here, “when generating power more than the amount of power (load) consumed by the communication device 400” means that the battery unit 300 uses the fact that the voltage inside the battery unit 300 depends on the output voltage of the solar power generation device 200. It is assumed that the voltage measured by the current / voltage sensor 302 in the unit 300 exceeds a voltage threshold that can be considered to be dependent on the output voltage of the photovoltaic power generator 200.

  In addition, the control unit 301 changes the charge amount to an initial value when the solar power generation device 200 generates power more than the power (load) consumed by the communication device 400 and is not being charged. For example, even on a sunny day, the amount of power generated by the solar power generation device 200 may rapidly decrease due to temporary shadows such as clouds. In this case, the control unit 301 immediately switches from the charged state to the discharged state so that power supply to the communication device 400 is not interrupted. As described above, when switching from the charged state to the power failure discharge, the control unit 301 resets the charging current value to the initial value to cope with a sudden change in the power generation amount.

  In addition, when the acquired current value is equal to or greater than a predetermined value stored in advance, the control unit 301 is not generating more power than the power (load) consumed by the communication device 400 when the solar power generation device 200 generates power. If charging is not in progress, the charging power is reduced by a certain amount. As described above, as a result of repeatedly increasing the charge amount, in an ideal environment, the sum of the charge amount and the amount of power supplied to the communication device 400 competes with the power generated by the solar power generation device 200. As a result, the bus voltage indicates that power is not generated more than the power (load) consumed by the communication device 400. By detecting this, the control unit 301 decreases the charge amount. Note that the amount to be decreased may be constant or variable.

  Next, the operation of the control unit 301 of the battery unit 300 configured as described above will be described. FIG. 5 is a flowchart showing the operation of the battery unit 300 of the present embodiment. It is assumed that the control unit 301 has detected a power failure of the commercial power supply 500 as a premise.

  First, the control part 301 operates the switch part 303, and performs a power failure discharge (step S1). It is judged by the control part 301 whether the power failure is continuing (step S2). When the power failure continues (step S2: YES), the control unit 301 acquires the bus voltage and current via the current / voltage sensor 302 (step S3).

  The control unit 301 determines whether or not the battery state is a power failure discharge based on the current (step S4). If it is a power failure discharge (step S4: YES), the process proceeds to step S2. In addition, when the battery state is not blackout discharge (step S4: NO), the control unit 301 determines whether or not the bus voltage exceeds a threshold that can be considered to depend on the output voltage (step S5).

  If the bus voltage does not exceed the threshold value (step S5: NO), the control unit 301 determines whether charging is in progress based on the result measured by the current / voltage sensor 302 (step S6). If not charging (step S6: NO), the process moves to step S3. If charging is in progress, the control unit 301 sets a value obtained by subtracting the fluctuation value from the current charging value as a new charging current value (step S7). The control unit 301 performs charging using the charging current value as the new charging current value (step S8).

  In step S5, when the bus voltage exceeds the threshold value (step S5: YES), it is determined whether or not charging is being performed as in step S6 (step S9). If charging is not in progress (step S9: NO), the controller 301 sets the new charging current value as an initial value (step S10), and proceeds to step S8. If charging is in progress (step S9: YES), the control unit 301 sets a new charging current value by adding the fluctuation value to the current charging value (step S11), and proceeds to step S8.

  If it is determined in step S2 that the power outage is not continuing (step S2: NO), the control unit 301 operates the switch unit 303 to stop the power outage discharge (step S12) and restore power (step S13). The process is terminated.

  The processing result according to this flowchart will be described with reference to the graph shown in FIG. The vertical axis represents the charging rate, and the horizontal axis represents time. The graph G1 shows the charging rate by the conventional DC power supply system, and the graph G2 shows the graph showing the charging rate of the DC power supply system 10 according to the present embodiment.

  In the conventional 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. Therefore, as shown in the graph G1, after the occurrence of a disaster (after a power failure), the charging rate Decrease without increasing.

  On the other hand, also in the DC power supply system 10 according to the present embodiment, at night (for example, the period t1), the amount of power generated by the solar power generation device 200 does not exceed the load on the facility, so the charging rate of the storage battery 304 is reduced. However, in a sunny state (for example, the period t2), the DC power supply system 10 increases the charging amount in stages by using surplus power, so that the charging rate can be increased in stages. Further, since there is almost no surplus power in a cloudy and sunny state (for example, period t3), the DC power supply system 10 performs control so as to increase the charging rate more slowly than in the period t2. For example, the DC power supply system 10 performs control so as to decrease the charge amount.

  In the radio base station, even when the commercial power source 500 is out of power due to a disaster or the like, the power generation amount of the solar power generation device 200 can be utilized to the maximum and supplied to the communication device 400. Specifically, the service securing time can be extended by charging surplus power to the storage battery 304 while supplying generated power to the communication device 400 on a sunny day. In addition, even after the storage battery 304 is depleted, the resumption operation can be performed by charging the storage battery 304 with surplus power while supplying the generated power to the communication device 400. In addition, by uniquely determining the charge / discharge control regardless of the environment or weather, it is possible to keep costs low without requiring the addition of new hardware such as a pyranometer, which is external information for charge / discharge control.

  When surplus power is generated, that is, when all loads are covered only by the power generated by the solar power generation apparatus 200, the bus voltage is affected by the output voltage of the solar power generation apparatus 200. When the bus voltage is read by the current / voltage sensor 302 and it can be considered that surplus power is generated, the surplus power is utilized by increasing the charge power amount of the storage battery 304 by a certain amount from the initial value every control cycle. It is possible. In order to apply the control of charging the surplus power to the storage battery 304 at the time of a disaster, it is necessary to charge the surplus power and prevent the loss of the power supplied to the communication device 400 by charging the surplus power or more. is there. In charging control of surplus power at normal time, when charging more power than surplus power, power is supplied from the rectifier 100 for the excess, but power supply from the rectifier 100 cannot be expected during a power failure. Therefore, in order to avoid charging more than surplus power at the time of a power failure, it is required to make the control period of the charging power small, and to provide a small amount of increase in the charging power.

  In surplus power charging control at the time of a power outage, in order not to charge more power than surplus power, the amount of current generated is larger when the power generated by the solar power generation device 200 antagonizes the sum of the amount of charging power and the load of the communication device 400. In order to take out the power, the fact that the output voltage of the photovoltaic power generation apparatus 200 slightly decreases and falls below a predetermined bus voltage threshold is utilized. When falling below the predetermined bus voltage threshold, the control unit 301 decreases the amount of charging power by a certain amount. If the control interval is too long, it may not be able to sufficiently follow the change in power generation, so this antagonistic state may not be reached, and if the increased current value is sufficiently large, the antagonistic state will not be reached and charging of surplus power during a power failure Cannot be realized.

  In the above-described embodiment, the battery unit 300 includes a current sensor and a voltage sensor. However, the battery unit 300 may include a current sensor and a voltage outside the battery unit 300.

  In the above-described embodiment, the surplus power of the solar power generation device 200 is effectively used at the time of a power failure in the DC power supply system. However, the present invention is not limited to the wireless base station.

  In the above-described embodiment, the presence / absence of surplus power generation is detected by monitoring the bus voltage, but the presence / absence of surplus power generation may be detected by the PV output current. For example, in an ideal environment, when the PV output current is equal to the sum of the battery charge and the load, it is determined that surplus power is generated, and when the output current of the battery unit 300 is zero, surplus power is generated. Judge that

  In the above-described embodiment, the case where the control unit 301 determines whether or not the power failure of the commercial power source 500 continues based on the detection result by the power failure sensor 101 has been described. Instead of this, it may be determined whether or not the power failure of the commercial power supply 500 continues based on the current and voltage measured by the current / voltage sensor 302. For example, the current measured by the current / voltage sensor 302 is not more than a specified value (a value that can be regarded as not discharged), and the voltage measured by the current / voltage sensor 302 is a bus voltage that depends on the rectifier output voltage. In some cases, it may be determined that the power failure of the commercial power source 500 does not continue.

  This is because the output voltages of the storage battery 304, the rectifier 100, and the solar power generation device 200 satisfy “storage battery output voltage ≦ rectifier output voltage <solar power generation device output voltage”, so that the determination can be made as described above. it can. The relationship of “storage battery output voltage ≦ rectifier output voltage” is established so that the rectifier 100 can fully charge the storage battery 304. Further, the relationship of “rectifier output voltage <solar power generation device output voltage” is established so that the solar power generation device 200 can supply power to the communication device 400 with priority over the rectifier 100 (commercial power).

  Next, operational effects of the DC power supply system 10 of the present embodiment will be described.

  In the DC power supply system of the present embodiment, when the commercial power supply that supplies power to the communication device 400 has a power failure, the control unit 301 is configured to supply power to the communication device 400. Based on the voltage measured based on the output voltage, the charge amount for the storage battery 304 is adjusted. Thereby, when surplus electric power is produced in the solar power generation device 200, the storage battery 304 can be charged, and surplus electric power can be used efficiently.

  More specifically, the control unit 301 adjusts the charge amount based on the current measured by the current / voltage sensor 302. For example, as a result, the control unit 301 can specify that the rapid power generation amount due to the passage of clouds or the like is decreasing, and can appropriately adjust the charge amount.

  Further, when it can be considered that surplus power is generated based on the voltage, the control unit 301 increases the charge power amount of the storage battery by a certain amount from the initial value, so that the surplus power can be effectively utilized.

  Moreover, since the control part 301 adjusts a charging current value based on the voltage measured after specifying that the power failure has continued by the power failure sensor 101, when it can be considered that surplus electric power is generated, the charging current The value can be adjusted.

DESCRIPTION OF SYMBOLS 10 ... DC power supply system, 31 ... CPU, 32 ... RAM, 33 ... ROM, 34 ... Communication module, 35 ... Auxiliary storage device, 36 ... Input device, 37 ... Output device, 100 ... Rectifier, 200 ... Solar power generation device, DESCRIPTION OF SYMBOLS 300 ... Battery part 301 ... Control part 302 ... Current / voltage sensor 303 ... Switch part 304 ... Storage battery 400 ... Communication apparatus.

Claims (4)

A solar power generation device that generates power by receiving sunlight, a storage battery that receives and stores power from the solar power generation device, and a power consumption target that receives power supply from the solar power generation device or the storage battery In the included DC power supply system,
Voltage measuring means for measuring a voltage based on an output voltage of the solar power generation apparatus that supplies power to the power consumption target when a commercial power supply that supplies power to the power consumption target is interrupted When,
Control means for adjusting the amount of charge for the storage battery based on the voltage measured by the measuring means;
DC power supply system comprising: The DC power supply system further includes current measuring means for measuring a current flowing between the storage battery and the power consumption target,
2. The DC power supply system according to claim 1, wherein the control unit adjusts a charge amount of the storage battery based further on the current measured by the current measuring unit.   When the voltage measured by the voltage measuring means exceeds a threshold value and the current measured by the current measuring means indicates that the storage battery is charged, the control means determines the amount of charge for the storage battery. The DC power supply system according to claim 2, wherein the DC power supply system is increased. The DC power supply system further includes a rectifier including a power failure sensor that detects a power failure of the commercial power supply,
The DC power supply system according to any one of claims 1 to 3, wherein the voltage measuring unit measures the voltage when it is detected by the power failure sensor that a power failure has occurred.

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