WO2018033963A1 - Power conversion device and photovoltaic power generation system - Google Patents

Abstract

Provided is a power conversion device capable of effectively utilizing power generated by lightning during a power failure. The power conversion device is provided with: a main circuit that receives DC power output from a solar cell module, converts the DC power to AC power, and is interconnected with a power system; a capacitor connected to the input of the main circuit and storing power output from the solar cell module; a control circuit that outputs a stop signal generated when the operation of the main circuit is stopped and a power failure occurs in the power system; a detection circuit that detects that the solar cell module has generated power by lightning and then generates a power generation signal, and outputs, on the basis of the stop signal and the power generation signal, a detection signal indicating that backup by the solar cell module is possible; and a voltage stabilizing circuit that receives DC power from the capacitor via a switch driven by the detection signal and supplies a stabilized output voltage.

Description

Power converter and solar power generation system

Embodiments of the present invention relate to a power conversion device and a solar power generation system.

The solar power generation system includes a solar cell module and an inverter device that converts direct current into alternating current. The inverter device can convert the DC power generated by the solar cell module into AC power and use it as a commercial power source. The generated AC power is connected to a power system and supplies power to consumers.

Solar cells do not generate electricity during nighttime or in rainy weather, and do not generate power. Therefore, if you intend to use power during nighttime or rainy weather, it is necessary to store the power with power storage equipment. . Considering the investment and maintenance costs, it is often difficult to introduce power storage equipment.

There is a strong demand to obtain backup power supply in the event of a power outage, even if it does not aim for constant power supply by a solar power generation system. However, constructing a power storage facility for emergencies is less cost effective and less feasible.

Solar cells are known to generate power not only by sunlight but also by lightning. There has been a demand for the emergence of a power conversion device that can secure power supply regardless of power storage equipment by effectively using power generated by thunderlight.

JP 2014-90588 A

Embodiments provide a power conversion device and a solar power generation system that can effectively use power generated by lightning during a power failure.

According to the embodiment of the present invention, the power conversion device receives the DC power output from the solar cell module, converts the DC power into AC power, and connects the main circuit connected to the power system to the input of the main circuit. A capacitor for storing power output from the solar cell module; a control circuit for outputting a stop signal generated when the operation of the main circuit is stopped and the power system is interrupted; A detection circuit for generating a power generation signal by detecting that the battery module has generated power by lightning, and outputting a detection signal indicating that the solar cell module can be backed up based on the stop signal and the power generation signal; Voltage stabilization for supplying a stabilized output voltage by inputting DC power from the capacitor via a switch driven by the detection signal Comprising a road, a.

According to the embodiment of the present invention, a power failure of the power system is detected by the control circuit, lightning power generation is detected by the detection circuit, and the voltage stabilization circuit is operated using the generated power stored in the capacitor. be able to. Therefore, the electric power generated by lightning at the time of a power failure is effectively used.

FIG. 1 is a block diagram illustrating a power conversion apparatus according to the first embodiment. FIG. 2A is a table illustrating the output logic of the output signal of the level detection circuit of the power converter. FIG. 2B is a table illustrating the output logic of the stop signal output from the main circuit of the power converter. FIG. 2C is a table illustrating the output logic of the solar radiation amount signal supplied from the outside. FIG. 2D is a table illustrating the output logic of the timer signal output from the timer circuit of the power conversion device. FIG. 3 is a table illustrating an operation state of the power conversion apparatus. FIG. 4 is a block diagram illustrating a power conversion apparatus according to the second embodiment.

Each embodiment will be described below with reference to the drawings.
The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between the parts, and the like are not necessarily the same as actual ones. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
Note that, in the present specification and each drawing, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

(First embodiment)
FIG. 1 is a block diagram illustrating a power conversion apparatus according to this embodiment.
As shown in FIG. 1, the power conversion device 10 includes a main circuit 12, an input capacitor 14, a control circuit 16, a lightning light generation detection circuit 18, and a voltage stabilization circuit 22.

The power conversion device 10 is connected to the solar cell module 1 via an input terminal. The solar cell module 1 includes one or more solar cells. In the solar cell module 1, a necessary number of solar cells are connected according to the output of the photovoltaic power generation system 100. The solar cell module 1 used in the solar power generation system 100 is not limited to one. In a solar power generation system having a relatively small capacity of about several kW to about 10 kW for home use, one to a plurality of solar cell modules are installed on the roof of a house. The solar cell module 1 may be used in a wide area such as a rooftop of a building, or may be used in a solar power generation system (mega solar) having a large output capacity exceeding several hundred kW. In these cases, a solar cell array further including a plurality of a plurality of solar cell modules may be used.

Although not shown, in the case of a system in which a plurality of solar cell modules 1 are used, each string of the solar cell modules 1 is connected to a current collection box via a connection box. The current collection box collects the outputs of the plurality of solar cell modules and connects them to the power converter 10.

The power conversion device 10 is connected to the power system 6 through an output terminal. As in this example, the transformer 2 and the circuit breaker 4 may be connected between the power conversion device 10 and the power system 6. The power system 6 is, for example, a three-phase AC power system. In that case, the power converter device 10 is connected to the electric power system 6 through the output terminal corresponding to each phase of a three-phase alternating current. In the case of a smaller-scale photovoltaic power generation system, the power conversion device 10 may be linked to a single-phase low-voltage lamp line.

The power conversion device 10 is connected between the solar cell module 1 and the power system 6, and converts DC power into AC power and supplies it to the power system 6 in normal operation.

The power converter 10 includes emergency power terminals 10p and 10n. The emergency power supply terminals 10p and 10n output a DC voltage in this example. For example, an emergency light 9 is connected to the emergency power terminals 10p and 10n. The emergency light 9 is a lighting device with low power consumption using, for example, a semiconductor light emitting element (LED). The power conversion device 10 outputs DC power from the emergency power terminals 10p and 10n by using the fact that the solar cell module 1 generates power by thunderlight when the power system 6 is interrupted at night by a lightning strike or the like. 9 is lit.

The power conversion device 10 is connected to the host monitoring device 8 when used in a large-scale photovoltaic power generation system such as a mega solar. The host monitoring device 8 acquires solar radiation amount data Ds and temperature data from a solar radiation meter 7 and a thermometer (not shown) placed in the vicinity of the solar cell module 1. The host monitoring device 8 can also acquire current and voltage data output by each string via the connection box. Using these data acquired by the host monitoring device 8, the photovoltaic power generation system 100 can detect a failure or the like, and is operated under optimum conditions.

In the power conversion device 10 of the present embodiment, determination of clear weather, cloudy weather, rainy weather, or the like is performed by using the solar radiation amount data measured by the solar radiation meter 7. In the case of a smaller-scale photovoltaic power generation system that does not have the host monitoring device 8, the output of the pyranometer 7 or the like is directly input to the power conversion device 10 and is converted by a data processing circuit (not shown) or the like. The apparatus 10 processes solar radiation data and the like.

Below, the structure of the power converter device 10 of this embodiment is demonstrated in detail.
The main circuit 12 is connected to the solar cell module 1 via an input terminal, and is connected to the power system 6 via an output terminal. The main circuit 12 uses, for example, a self-extinguishing semiconductor switching element such as an IGBT (Insulated Gate Bipolar Transistor) to perform high-frequency switching of a DC voltage, and uses a filter to remove a harmonic component to obtain a desired AC voltage and AC current. Is output.

The input capacitor 14 is connected in parallel to the input of the main circuit 12. The input capacitor 14 is connected between the solar cell module 1 and the main circuit 12. The input capacitor 14 absorbs fluctuations in the current output from the solar cell module 1. Further, the input capacitor 14 absorbs fluctuations in the input voltage of the main circuit 12 due to a ripple current generated when power is supplied to the main circuit 12.

The input capacitor 14 stores the generated power and supplies it to a voltage stabilization circuit (Automatic Voltage Regulator, hereinafter referred to as AVR) 22 when the solar cell module 1 generates power by lightning.

The input capacitor 14 includes, for example, an electrolytic capacitor, and a film capacitor or the like may be connected in parallel to absorb the switching noise of the main circuit 12. The capacitance value of the input capacitor 14 is, for example, about several mF to 10 mF (several thousand μF to 10,000 μF) when the output capacity of the main circuit 12 is about 500 kW.

A discharge resistor 24 is connected to both ends of the input capacitor 14. The discharge resistor 24 discharges the electric charge accumulated in the input capacitor 14 from the viewpoint of safety when the main circuit 12 is interrupted due to overcurrent, overvoltage, or the like. In this example, one terminal of the changeover switch 20 is connected to the high potential side of the discharge resistor 24.

The other terminal of the changeover switch 20 is connected to the input of the AVR 22. The changeover switch 20 is controlled by the output of the lightning light generation detection circuit 18 and the connection is changed. The changeover switch 20 selects and connects either the discharge resistor 24 or the AVR 22 to the high potential side of the input capacitor 14. As will be described in detail later, when lightning occurs due to a lightning strike at night, the lightning power generation detection circuit 18 connects the high potential side of the input capacitor 14 and the AVR 22 by the changeover switch 20. During normal power generation by sunlight in the daytime, the lightning light generation detection circuit 18 connects the high potential side of the input capacitor 14 and the discharge resistor 24 by the changeover switch 20. Further, in the case of nighttime or cloudy weather, the lightning light generation detection circuit 18 connects the high potential side of the input capacitor 14 and the discharge resistor 24 by the changeover switch 20.

The control circuit 16 is connected to the main circuit 12. The control circuit 16 appropriately controls the main circuit 12 using detected data such as an input voltage, an output voltage, and an output current of the main circuit 12.

The control circuit 16 is connected to the lightning power generation detection circuit 18. When the DC voltage input to the main circuit 12 falls below a predetermined minimum operating voltage, the control circuit 16 stops the operation of the main circuit 12 and the power system 6 has a power failure. A stop signal Sh is output. In other cases, the stop signal Sh becomes H level. The stop signal Sh is supplied to the lightning power generation detection circuit 18.

The lightning power generation detection circuit 18 includes a voltage detector 31, a voltage level detection circuit 32, OR circuits 33 and 35, and a timer circuit 34.

The voltage detector 31 is connected to the input capacitor 14 in parallel. The voltage detector 31 is composed of a resistor connected in series, for example. The voltage detector 31 divides the voltage across the input capacitor 14 with a plurality of resistors, and outputs the divided voltage.

The voltage level detection circuit 32 is connected to the output of the voltage detector 31. The voltage level detection circuit 32 outputs a signal corresponding to whether or not the voltage output from the voltage detector 31 is within a predetermined range.

In this example, the voltage level detection circuit 32 outputs a high level (H level) output signal Sv when the output voltage of the voltage detector 31 is higher than the voltage corresponding to the lowest operating voltage of the main circuit 12. The voltage level detection circuit 32 outputs the H level output signal Sv even when the output voltage of the voltage detector 31 is lower than the voltage corresponding to the lowest operating voltage of the AVR 22. When the output voltage of the voltage detector 31 is higher than the voltage corresponding to the lowest operating voltage of the AVR 22 and lower than the voltage corresponding to the lowest operating voltage of the main circuit 12, the voltage level detection circuit 32 is low level. The (L level) output signal Sv is output.

The output of the voltage level detection circuit 32 is connected to one input of the OR circuit 33. An output signal Sv indicating whether or not the voltage across the input capacitor 14 is within the above range is input to one input of the OR circuit 33.

The OR circuit 35 inputs the stop signal Sh of the main circuit 12 output from the control circuit 16. Further, the OR circuit 35 receives the solar radiation amount signal Ss via the host monitoring device 8. Further, the OR circuit 35 receives the timer signal St output from the timer circuit 34.

In this example, the stop signal Sh is at the L level when the main circuit 12 is stopped and the power system 6 is out of power, and when the main circuit 12 is operating or the power system is not out of power. H level.

The solar radiation amount signal Ss supplied from the host monitoring device 8 is generated based on the solar radiation amount data Ds acquired by the solar radiation meter 7. In this example, the solar radiation amount signal Ss is at the H level when the solar radiation amount data Ds is equal to or greater than a predetermined value, and is at the L level when the solar radiation amount data Ds is smaller than the predetermined value. The solar radiation amount signal Ss is set to be H level when the solar radiation amount is large during daytime fine weather, and is set to L level when the solar radiation amount is small at night or overcast. The predetermined value of the amount of solar radiation can be set arbitrarily. In the above description, the host monitoring device 8 generates the solar radiation amount signal Ss based on the solar radiation amount data Ds. However, upon receiving the solar radiation amount data Ds from the host monitoring device 8, the power conversion device 10 receives the solar radiation amount data Ds. The quantity signal Ss may be generated.

The timer circuit 34 outputs an H level timer signal St in a predetermined time zone, and outputs an L level timer signal St in other times. In this example, the H level corresponds to the daytime period, and the L level corresponds to the nighttime period. The predetermined time zone can be freely set according to the installation location of the photovoltaic power generation system 100, the season of the location, and the like. For example, the timer circuit 34 may include in advance a table in which a daytime time zone and a nighttime zone are set in accordance with the calendar of the installation location.

OR circuit 35 outputs L level when stop signal Sh, solar radiation signal Ss, and timer signal St all become L level. The output of the OR circuit 35 is input to the OR circuit 33 together with the output of the voltage level detection circuit 32.

OR circuit 33 outputs detection signal Sdet of L level when output signal Sv of voltage level detection circuit 32 and the output of OR circuit 35 all become L level. That is, the OR circuit 33 outputs an L level when the voltage across the input capacitor 14 is within a predetermined range, the main circuit 12 is stopped, the power system 6 is out of power, it is nighttime, and the amount of solar radiation is small. To do. Except for this condition, the OR circuit 33 outputs the detection signal Sdet at the H level.

When the lightning power generation detection circuit 18 outputs an H level detection signal Sdet, the changeover switch 20 connects the high potential side of the input capacitor 14 to the discharge resistor 24. When the lightning power generation detection circuit 18 outputs the L level detection signal Sdet, the changeover switch 20 connects the high potential side of the input capacitor 14 to the input of the AVR 22.

The signals input to the OR circuit 35 of the lightning power generation detection circuit 18 do not have to input all the above signals. For example, the stop signal Sh and the timer signal St may be input to the OR circuit 35. Alternatively, a solar radiation amount signal Ss may be input instead of the timer signal St.

The AVR 22 inputs an unstable DC voltage and outputs a stabilized DC voltage. The AVR 22 is a power conversion circuit having a sufficiently small output capacity as compared with the main circuit 12. The output of the AVR 22 is connected to the emergency light 9 through the emergency power supply terminals 10p and 10n. The AVR 22 may be a dropper type regulator, but since the efficiency of the AVR 22 affects the lighting time of the emergency light 9, the AVR 22 is preferably a switching type DC-DC converter. The AVR 22 is not limited to a configuration that outputs a DC voltage, and may be an inverter device that outputs a stabilized AC voltage.

The AVR 22 preferably operates at a lower input voltage in order to effectively use the electric charge accumulated in the input capacitor 14. The input voltage range of the main circuit 12 is about 300V to 600V in the case of an output capacity of 500 kW, for example. Therefore, the input voltage input to the AVR 22 is about 10V to 300V. In order to realize such a wide input voltage range, a plurality of power supply devices may be used. For example, the input voltage range of the first power supply device is set to 150 V to 300 V, the input voltage range of the second power supply device is set to 10 V to 150 V, and an appropriate circuit system may be adopted depending on the input voltage range. Good. Alternatively, a topology such as a step-up / down power supply circuit in which a step-up power supply circuit and a step-down power supply circuit are cascade-connected may be used.

Note that the maximum input voltage at which the AVR 22 can operate need not match the minimum operating voltage of the main circuit 12. For example, when the minimum operating voltage of the main circuit 12 is 300V, the maximum operating voltage of the AVR 22 may be set to 200V or 350V.

Operation | movement of the power converter device 10 of this embodiment is demonstrated.
FIG. 2A is a table illustrating the output logic of the output signal of the level detection circuit of the power converter. FIG. 2B is a table illustrating the output logic of the stop signal output from the main circuit of the power converter. FIG. 2C is a table illustrating the output logic of the solar radiation amount signal supplied from the outside. FIG. 2D is a table illustrating the output logic of the timer signal output from the timer circuit of the power conversion device.
FIG. 3 is a table illustrating an operation state of the power conversion apparatus.
In this example, it is assumed that the minimum operating voltage of the main circuit 12 is 300V and the minimum operating voltage of the AVR 22 is 10V. The minimum operating voltage of the main circuit 12 and the AVR 22 is not limited to these values, and can be set appropriately.

As shown in FIG. 2A, when the voltage VIN across the input capacitor 14 is 0 V or more and 10 V or less, or 300 V or more, the voltage level detection circuit 32 outputs an H level output signal Sv. To do. When the voltage VIN across the input capacitor 14 exceeds 10V and does not reach 300V, the voltage level detection circuit 32 outputs an L level output signal Sv. In the normal operation of the power converter 10, when there is no output of the solar cell module 1 such as at night or cloudy weather, the discharge resistor 24 causes the voltage across the input capacitor 14 to be 0V to several volts. It is discharged. Therefore, in this case, the output signal Sv is at the H level.

As shown in FIG. 2B, when the main circuit 12 is stopped and the power system 6 is out of power, the stop signal Sh becomes L level. Even when the main circuit 12 is stopped, the stop signal Sh is at the H level when the power system 6 is not out of power. When the main circuit 12 is operating, the stop signal Sh is at the H level regardless of whether or not the power system 6 has a power failure.

As shown in FIG. 2 (c), the host monitoring device 8 outputs an H level solar radiation signal Ss when the solar radiation data Ds is equal to or greater than a threshold value TH. When the solar radiation amount data Ds is less than the threshold value TH, the host monitoring device 8 outputs an L level solar radiation amount signal Ss.

As shown in FIG. 2D, in this example, the timer circuit 34 outputs an L-level timer signal St in the time zone from 18:01 on the previous day to 5:59 on the current day. In the time zone from 6:00 to 18:00, the timer circuit 34 outputs an H level timer signal St. That is, the timer circuit 34 outputs an L-level timer signal St during the nighttime period, and outputs an H-level timer signal St during the daytime period. About the time which becomes a boundary of a night time zone and a daytime time zone, it can set appropriately according to the season, etc. of the area, country, the area, etc. in which the photovoltaic power generation system 100 is installed. The timer circuit 34 may include a table including a calendar. These times are set on the calendar, and the time may be read and set every day.

FIG. 3 shows the states of the above-described signals Sv, Sh, Ss, St for power generation by lightning, normal daytime, normal nighttime, and low solar radiation. Yes. FIG. 3 also shows how the detection signal Sdet of the lightning light generation detection circuit 18 is set by the signals Sv, Ss, Sh, St.

First, the operation during nighttime lightning power generation will be described.
When power generation by lightning occurs at night and the power system 6 is interrupted by lightning or the like, power backup is required. At night, the input capacitor 14 is discharged by the discharge resistor 24, and the voltage at both ends is lower than 10V. Therefore, the output signal Sv of the voltage level detection circuit 32 is at the H level. Thereafter, since the solar cell module 1 generates power by lightning, the voltage across the input capacitor 14 rises, and when the voltage exceeds 10 V, the output signal Sv of the voltage level detection circuit 32 is inverted to L. The L level output signal Sv is supplied to the OR circuit 33.

The voltage VIN across the input capacitor 14 has decreased, and the operation of the main circuit 12 has stopped. Further, when a power failure occurs in the power system 6 due to lightning or the like, the control circuit 16 outputs an L level stop signal Sh. The L level stop signal Sh is supplied to the OR circuit 35.

The solar radiation amount signal Ss is L level because the solar radiation amount data Ds is less than the threshold value TH because it is nighttime. The L level solar radiation amount signal Ss is supplied to the OR circuit 35.

The timer signal St of the timer circuit is L level because it is nighttime. The L level timer signal St is supplied to the OR circuit 35.

Since all three inputs (Sh, Ss, St) of the OR circuit 35 are at the L level, the OR circuit 35 outputs an L level signal, and this signal is supplied to the OR circuit 33.

Since the L level signal is input to the two inputs of the OR circuit 33, the detection signal Sdet of the OR circuit 33 is at the L level. Therefore, the changeover switch 20 connects the high potential side of the input capacitor 14 and the input of the AVR 22.

The AVR 22 supplies DC power to the emergency light 9 when a voltage that enables operation is input, and the emergency light 9 is turned on.

Although not shown, the stop signal Sh output by the control circuit 16 is at the H level when a power failure has not occurred during the lightning power generation. Therefore, the OR circuit 35 outputs an H level signal, and the detection signal Sdet output from the OR circuit 33 is at the H level. Therefore, since the changeover switch 20 connects the high potential side of the input capacitor 14 and the discharge resistor 24, the AVR 22 does not operate.

In addition, when lightning occurs other than at night, the timer signal St becomes H level, so that the detection signal Sdet of the lightning light generation detection circuit 18 becomes H level and the AVR 22 does not operate.

Next, the operation during sunny daytime will be described.
In the daytime, the signals Sv, Ss, Sh, St are all at the H level, and the detection signal Sdet of the lightning power generation detection circuit 18 is at the H level. Therefore, the changeover switch 20 connects the high potential side of the input capacitor 14 and the discharge resistor 24. Since direct current power is not supplied to the AVR 22, the AVR 22 does not operate and does not supply power to the emergency light 9.

Next, operation at night without lightning will be described.
At night without lightning, there is no output from the solar cell module 1 and the input capacitor 14 is discharged by the discharge resistor 24. The voltage level detection circuit 32 outputs an H level output signal Sv. Therefore, the lightning power generation detection circuit 18 outputs an H level detection signal Sdet. When the detection signal Sdet is at the H level, the changeover switch 20 connects the high potential side of the input capacitor 14 and the discharge resistor 24. Since direct current power is not supplied to the AVR 22, the AVR 22 does not operate and does not supply power to the emergency light 9.

Lastly, a description will be given of a state during cloudy or rainy daytime.
During daytime cloudy weather or rainy weather, the solar radiation amount signal Ss is at the L level, but all other signals are at the H level. Therefore, the lightning power generation detection circuit 18 outputs an H level detection signal Sdet. The changeover switch 20 connects the high potential side of the input capacitor 14 and the discharge resistor 24 by the detection signal Sdet at the H level. Depending on the characteristics of the solar cell module 1, an output may be generated during cloudy weather, but since the timer signal St is at H level, the detection signal Sdet of the lightning light generation detection circuit 18 is at H level. Therefore, the AVR 22 is not operated.

The operation and effect of the power conversion device of this embodiment will be described.
The power conversion device 10 according to the present embodiment includes a lightning power generation detection circuit 18. The lightning power generation detection circuit 18 can detect the voltage VIN across the input capacitor 14 and determine whether it is within a predetermined voltage range. The predetermined range is defined by an input voltage at which the AVR 22 can operate and an input voltage at which the main circuit 12 stops operating. The power converter 10 can determine that the lightning power generation can be used by the lightning power generation detection circuit 18 when the voltage VIN across the input capacitor 14 is within this range.

The lightning power generation detection circuit 18 is set with conditions for using lightning power generation. The conditions for using the lightning power generation are that the main circuit 12 is stopped, the power system 6 is cut off, the amount of solar radiation is low, the nighttime, and is detected by the lightning power generation detection circuit 18.

The power conversion device 10 of the present embodiment includes an AVR 22 that operates an emergency load such as the emergency light 9 when lightning power generation is detected. The power conversion device 10 can connect the AVR 22 to the input capacitor 14 based on the detection result of the lightning power generation detection circuit 18. Therefore, the AVR 22 can supply the lightning power generation stored in the input capacitor 14 to the emergency load for backup.

Since the lightning power generation detection circuit 18 can determine that lightning power generation cannot be used under conditions other than those described above, the operation can be stopped by disconnecting the AVR 22 when backup is not required. Therefore, it is possible to avoid the occurrence of power loss due to the operation of the AVR 22, and it is possible to realize a highly efficient solar power generation system 100.

Hereinafter, the effect of the power conversion device 10 of the present embodiment will be described using a specific example.
In the power conversion device 10 of the present embodiment, the power generated by lightning stored in the input capacitor 14 is converted to a constant voltage using AVR, and a preliminary load such as the emergency light 9 is driven. Such a preload driving time can be specifically calculated from the capacitance value CIN of the input capacitor 14 and the voltage VIN across the input capacitor 14 charged by lightning.

For example, assuming that the capacitance value CIN of the input capacitor 14 is 5000 μF, the voltage VIN charged by lightning power generation is 100 V, and all the charged charges can be supplied to the emergency light 9, it can be stored in the input capacitor 14. The energy Ec is as follows. Note that the power conversion loss of the AVR 22 is set to zero.

Ec = (1/2) × CIN × VIN ²
= (1/2) × 5000 × 10 ⁻⁶ [F] × (100 [V]) ² = 25 [J]

When a 100 mW emergency light 9 (for example, 5 V, 20 mA) is turned on, the lighting time is 25 [J] ÷ 100 [mW] = 250 [s]. In other words, the power conversion device 10 can turn on the emergency light 9 for about 4 minutes during a night power failure.

As described above, in the power conversion device 10 of the present embodiment, it is possible to detect power generation due to lightning at night and automatically switch to power supply to the emergency load by the AVR 22. The generated power can be used effectively.

(Second Embodiment)
In the case of the above-described embodiment, the power generated by lightning is stored in the input capacitor 14 and the voltage at both ends of the input capacitor 14 is detected to detect whether lightning is generated. The means for detecting lightning power generation is not limited to the above, and other means can be used.

FIG. 4 is a block diagram illustrating a power conversion apparatus according to this embodiment.
As shown in FIG. 4, the power conversion device 210 of this embodiment includes a current detection circuit 218. The current detection circuit 218 includes a current sensor 231 and a current level detection circuit 232. Since other components are the same as those in the first embodiment, the same reference numerals are given and detailed description is omitted.

The current sensor 231 is connected to the input bus 211 connected to the solar cell module 1 via the input terminal of the power converter 210. The current sensor 231 may include an instrument current transformer. The current sensor 231 detects the output current of the solar cell module 1 output from the current transformer for the instrument, and detects the current in a non-contact manner using a magnetoresistive element such as a Hall element. The current sensor 231 may use a voltage drop caused by a resistor.

The current level detection circuit 232 outputs an L level when the output signal of the current sensor 231 is larger than a predetermined threshold value, and outputs an H level when the output signal is less than the predetermined threshold value. Current level detection circuit 232 maintains an L level output when a current exceeding a predetermined threshold is detected. Although not shown, the current level detection circuit 232 may include, for example, a comparator and a latch circuit connected to the output of the comparator. In this case, the latch circuit may be reset at daytime by the output of the timer circuit 34.

The predetermined threshold is set based on the output current during normal operation of the solar cell module 1. The threshold value is set to a value sufficiently larger than the output current of the solar cell module 1 during normal operation. For example, the threshold value is set to 5 times the maximum current flowing through the input bus 211 of the solar cell module 1. This threshold value is set based on the result of measuring, in advance, the value of the output current during lightning power generation in the area where the solar power generation system 200 is installed.

Operation | movement of the power converter device 210 of this embodiment is demonstrated.
In the power converter 210 of the present embodiment, the solar cell module 1 outputs an output current having a large peak value, and when the output current exceeds a threshold value, the current level detection circuit 232 outputs the L level output signal Sv. Is output. As in the case of the first embodiment, the solar radiation amount signal Ss, the stop signal Sh, and the timer signal St are input to the OR circuit 35. Since these signals are all at L level when the amount of sunshine at night is small, the OR circuit 35 outputs L level.

Therefore, in the OR circuit 33, both of the two inputs are at the L level, and the detection signal Sdet is at the L level. With the detection signal Sdet, the changeover switch 20 connects the high potential side of the input capacitor 14 and the input of the AVR 22. The AVR 22 starts operation and supplies power to the emergency light 9.

During the daytime, etc., the current level detection circuit 232 outputs the H level output signal Sv, so that power is not supplied to the AVR 22.

The operation and effect of the power conversion device 210 of this embodiment will be described.
In addition to the same effects as those of the first embodiment, the power conversion device 210 of the present embodiment has the following effects.

The power converter 210 detects the presence or absence of power generation due to lightning by detecting the output current of the solar cell module 1 using the current sensor 231 and the current level detection circuit 232. The power generated by lightning of a general solar cell module is larger than the power generated by sunlight, and the output current is several times to 10 times that during normal operation. Therefore, it is easy to set a threshold value for lightning power generation output, and it is easy to detect the output current due to lightning. In the power conversion device 210 of the present embodiment, detection of thunderlight power generation can be simplified, and therefore a low-cost and highly reliable solar power generation system 200 can be realized.

In addition to detecting the current in the current sensor 231, the voltage across the input capacitor 14 as in the first embodiment may be detected as the lightning power generation detection condition.

According to the embodiment, there is provided a power conversion device that can effectively use the power generated by lightning during a power failure.

The embodiments of the present invention have been described above with reference to specific examples. However, embodiments of the present invention are not limited to these specific examples. For example, the specific configuration of each element included in the power conversion device, such as a main circuit, a control circuit, a lightning light generation detection circuit, and a voltage stabilization circuit, is appropriately selected from a known range by those skilled in the art. Are included in the scope of the present invention as long as they can be carried out in the same manner and the same effects can be obtained.
Moreover, what combined any two or more elements of each specific example in the technically possible range is also included in the scope of the present invention as long as the gist of the present invention is included.

In addition, all power conversion devices and photovoltaic power generation systems that can be implemented by those skilled in the art based on the power conversion device and the photovoltaic power generation system described above as embodiments of the present invention are also included in the present invention. As long as the gist is included, it belongs to the scope of the present invention.

In addition, in the category of the idea of the present invention, those skilled in the art can conceive of various changes and modifications, and it is understood that these changes and modifications also belong to the scope of the present invention. .

Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and the equivalents thereof. Further, the above-described embodiments can be implemented in combination with each other.

Claims (15)

1. DC power output from the solar cell module is input, converted into AC power, and connected to the power system,
   A capacitor that is connected to an input of the main circuit and stores electric power output from the solar cell module;
   A control circuit for outputting a stop signal generated when the operation of the main circuit is stopped and the power system is interrupted;
   A detection circuit that detects that the solar cell module has generated power by lightning, generates a power generation signal, and outputs a detection signal indicating that the solar cell module can be backed up based on the stop signal and the power generation signal When,
   A voltage stabilizing circuit for supplying a stabilized output voltage by inputting DC power from the capacitor via a switch driven by the detection signal;
   The power converter provided with.
2. The detection circuit generates a detection signal when a voltage detector that detects a voltage across the capacitor and a voltage detected by the voltage detector is lower than a lower limit value for the operation of the main circuit. The power converter of Claim 1 containing the determination circuit to perform.
3. The detection circuit includes a current detection circuit that detects a current output from the solar cell module; a determination circuit that generates the power generation signal when an output value of the current detection circuit is greater than a predetermined threshold; The power converter of Claim 1 containing.
4. The detection circuit further receives a time signal generated in a predetermined time zone, and connects the capacitor to the voltage stabilization circuit via the switch based on the stop signal, the power generation signal, and the time signal. The power conversion device according to claim 1.
5. The power converter according to claim 4, wherein the detection circuit further receives a solar radiation signal output from a solar radiation meter that measures the amount of solar radiation.
6. The power converter according to claim 1, wherein the voltage stabilizing circuit outputs a DC voltage.
7. The power converter according to claim 1, wherein the voltage stabilizing circuit outputs an alternating voltage.
8. The solar cell module;
   DC power output from the solar cell module is input, converted into AC power, and connected to the power system,
   A capacitor that is connected to an input of the main circuit and stores electric power output from the solar cell module;
   A control circuit for outputting a stop signal generated when the operation of the main circuit is stopped and the power system is interrupted;
   A detection circuit that detects that the solar cell module has generated power by lightning, generates a power generation signal, and outputs a detection signal indicating that the solar cell module can be backed up based on the stop signal and the power generation signal When,
   A voltage stabilizing circuit for supplying a stabilized output voltage by inputting DC power from the capacitor via a switch driven by the detection signal;
   A power conversion device including:
   Solar power generation system equipped with.
9. The detection circuit generates a detection signal when a voltage detector that detects a voltage across the capacitor and a voltage detected by the voltage detector is lower than a lower limit value for the operation of the main circuit. The photovoltaic power generation system of Claim 8 containing the determination circuit to perform.
10. The detection circuit includes a current detection circuit that detects a current output from the solar cell module; a determination circuit that generates the power generation signal when an output value of the current detection circuit is greater than a predetermined threshold; The solar power generation system of Claim 8 containing.
11. The detection circuit further receives a time signal generated in a predetermined time zone, and connects the capacitor to the voltage stabilization circuit via the switch based on the stop signal, the power generation signal, and the time signal. The photovoltaic power generation system according to claim 8.
12. The solar power generation system according to claim 11, wherein the detection circuit further inputs a solar radiation signal output from a solar radiation meter that measures the amount of solar radiation.
13. The solar power generation system according to claim 12, further comprising a monitoring device that generates the solar radiation signal.
14. The solar power generation system according to claim 8, wherein the voltage stabilization circuit outputs a DC voltage.
15. The solar power generation system according to claim 8, wherein the voltage stabilization circuit outputs an alternating voltage.

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