JP2015008559A - Junction box and photovoltaic power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photovoltaic power generation system in which abnormalities of a junction box can be found easily, by providing a junction box in which abnormalities of an output voltage sensor can be detected without providing an extra circuit for abnormality detection.SOLUTION: A junction box 4 for connecting a solar cell module 2 with a power conditioner 3 includes a plurality of booster units 41 each having a booster circuit 42, an input voltage sensor 44 of the booster circuit 42, an output voltage sensor 45 of the booster circuit 42, and a control section 43 of the booster circuit 42. The control section 43 of each booster unit 41 compares the detection value of each output voltage sensor 45 with the input voltage of a booster unit 41 having the largest input voltage, and if the difference goes above a predetermined value, determines that the output voltage sensor 45 of the booster unit 41 is abnormal, and controls an LED 46 to perform lighting operation.

Description

  The present invention relates to a junction box and a photovoltaic power generation system, and more particularly to a junction box with a booster circuit having a plurality of booster units in a casing, and a photovoltaic power generation system having the junction box.

  When connecting a plurality of solar cell modules to a power conditioner (system-connected inverter device), a connection box is provided between each solar cell module and the power conditioner (see, for example, Patent Document 1).

  This type of junction box includes a plurality of boosting units each having a booster circuit in a housing, and the output of each solar cell module is connected to the booster unit. The boost unit to which the solar cell module having the highest output voltage is connected (that is, the boost unit having the maximum input voltage) does not perform the boost operation, while the other boost units have their output voltages at the maximum input voltage. The output voltage of the plurality of solar cell modules is aligned in the connection box and is input to the power conditioner.

  By the way, in the connection box having such a configuration, in order to perform the above-described operation, each booster unit includes a booster circuit, a control unit that controls the boosting operation of the booster circuit, and an input voltage to the booster circuit. Although the input voltage sensor for detecting and the output voltage sensor for detecting the output voltage of the booster circuit are provided, the solar cell can be used regardless of whether the operation of the power conditioner is on or off due to the circuit configuration. If the module is generating electric power, voltage is applied to the output voltage sensor of each boosting unit, and it is difficult to detect a failure in which the output voltage sensor shows an abnormal value other than open / short.

Japanese Patent No. 4468371

  The present invention has been made in view of such conventional problems, and the object of the present invention is to provide a connection box that can detect an abnormality of an output voltage sensor without providing a special circuit for detecting an abnormality. It is to provide a solar power generation system that can easily detect an abnormality of a connection box by providing the connection box.

  To achieve the above object, a connection box according to claim 1 of the present invention is a connection box for connecting outputs of a plurality of solar cell modules to input terminals of a power conditioner, and includes a booster circuit, A plurality of boosting units each having an input voltage sensor that detects an input voltage of the booster circuit, an output voltage sensor that detects an output voltage of the booster circuit, and a control unit of the booster circuit are detected by the input voltage sensor. The booster circuit of the booster unit with the maximum input voltage stops the booster operation, while the booster circuits of the other booster units are configured to perform the booster operation so that their output voltages match the maximum input voltage. The control unit of each boosting unit compares the detected value of each output voltage sensor with the maximum input voltage, and the difference is not less than a predetermined value. When it is characterized in that the output voltage sensor of the booster unit is provided for determining the control structure to be abnormal.

  The connection box according to claim 1 is a connection box including a plurality of boosting units corresponding to the connection of a plurality of solar cell modules. The output voltage of each boosting unit is the input voltage of the boosting unit having the highest input voltage. Is used to detect whether there is an abnormality in the output voltage sensor of each boosting unit. Specifically, the control unit of each boosting unit compares the detected value of each output voltage sensor with the input voltage of the boosting unit having the highest input voltage, and if the difference between the two is equal to or greater than a predetermined value, the boosting unit The output voltage sensor is determined to be abnormal. Therefore, in the junction box according to claim 1, the output voltage sensor is simply changed by changing the software of the control unit of the existing booster unit without using a special circuit for detecting an abnormality of the output voltage sensor of each booster unit. Abnormalities can be detected.

  The junction box according to claim 2 of the present invention is the junction box according to claim 1, wherein each of the boosting units includes notifying means for notifying that when the output voltage sensor is determined to be abnormal. It is characterized by.

  In the junction box according to the second aspect of the present invention, each boosting unit is provided with notifying means for notifying the abnormality of the output voltage sensor, so that the boosting unit in which the abnormality of the output voltage sensor is detected can be easily identified and specified. be able to.

  The solar power generation system according to claim 3 of the present invention is a solar power generation system including a plurality of solar cell modules, and is a connection box for connecting each of the solar cell modules to a power conditioner. Or the connection box of 2 is provided.

  That is, in the photovoltaic power generation system according to claim 3, a function of detecting an abnormality of the output voltage sensor is provided in the boost unit provided in the connection box for connecting the plurality of solar cell modules to the power conditioner. Therefore, it is possible to provide a solar power generation system that can easily detect abnormality of the output voltage sensor.

  According to the present invention, the abnormality of the output voltage sensor of the boosting unit can be detected simply by changing the software of the control unit of the existing boosting unit, so that a connection box having an abnormality detection function of the output voltage sensor is provided at low cost. be able to.

  In addition, since each booster unit is provided with a notification means for notifying an abnormality of the output voltage sensor, it is possible to easily identify and identify a booster unit having an abnormality in the output voltage sensor, and to specify a failure during maintenance or the like. It can be done easily and quickly.

  According to the present invention, the control of the boosting unit (control of the boosting operation) based on the abnormal output voltage sensor is eliminated, so that the solar power generation system that can effectively use the power generation in the solar cell module without waste Can be provided.

It is a circuit block diagram which shows schematic structure of the solar energy power generation system using the connection box which concerns on this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of a photovoltaic power generation system 1 using a junction box according to the present invention. This solar power generation system 1 includes a plurality of solar cell modules 2 and a power condition for connecting the power generated by these solar cell modules 2 to a power system P such as a commercial power source (for example, single-phase AC 100 / 200V). The main part is composed of the main body 3 and the connection box 4 for connecting the outputs of the plurality of solar cell modules 2 to the power conditioner 3.

  The solar cell module 2 is configured by arranging a plurality of known solar cell modules, that is, a plurality of solar cells and packaging them. In the illustrated example, the solar cell module 2 includes four solar cell modules 2a to 2d. ing. The solar cell module 2 includes a solar cell string in which a plurality of solar cell modules are grouped.

  The power conditioner 3 is a grid-connected inverter device for linking DC power generated by the solar cell module 2 to the power system P, and the configuration of the power conditioner 3 is also known. That is, the power conditioner 3 includes a converter circuit unit 31 and an inverter circuit unit 32 as main parts. The converter circuit unit 31 boosts the DC voltage generated by the solar cell module 2, and the inverter circuit unit 32 It is comprised so that it may convert into alternating current power which can be connected with the electric power grid | system P. FIG.

  In FIG. 1, reference numeral 30 denotes an input terminal (input terminal) of the power conditioner 3 (specifically, the converter circuit unit 31), and an output of the connection box 4 described later is connected to the input terminal 30. Thus, the output of the solar cell module 2 is input to the power conditioner 3 via the connection box 4.

  The connection box 4 is a device for aligning the output voltages of the plurality of solar cell modules 2 and inputting them to the power conditioner, and is configured by housing a plurality of boosting units 41 in a box-shaped housing (not shown). ing. That is, in the junction box 4, the same number of boost units 41 (41a to 41d in the illustrated example) as the number of circuits of the solar cell modules 2 connected to the junction box 4 (four circuits 2a to 2d in the illustrated example). 4 circuits).

  Each of the boosting units 41a to 41d has the same circuit configuration as shown in FIG. Specifically, each of the booster circuits 41a to 41d is disposed on an independent electrical board (not shown), both of which are a booster circuit 42 and a microcomputer that controls the boosting operation of the booster circuit 42. (Control unit) 43, input voltage sensor 44 that detects the input voltage to the booster circuit 42, output voltage sensor 45 that detects the output voltage from the booster circuit 42, and notification means for notifying abnormality of the output voltage sensor 45 LED46 which comprises these.

  As described above, by using a circuit having the same configuration as each of the boosting units 41a to 41d, in the junction box 4 of the present embodiment, the manufacturing cost is reduced. In the following description, when the components of the boosting unit 41 are specified for each boosting unit, a to d are added to the end of the reference numerals like the boosting units 41a to 41d.

  Here, the configuration of each of the boosting units 41a to 41d will be described in more detail. The booster circuit 42 is configured by a known boost chopper circuit. The microcomputer 43 is configured to control a switching element (not shown) of the boost chopper circuit, and the microcomputer 43 controls the boost operation (including the stop of the boost operation) of the boost circuit 42. ing. In addition, the microcomputer 43 is configured to be communicable with the microcomputer 43 of the other boosting unit 41 in connection with the control of the boosting operation. The detection value of the input voltage sensor 44) can be acquired.

  The input voltage sensor 44 is arranged in front of the booster circuit 42, and is configured to detect a voltage input from the solar cell module 2 to the booster circuit 42 and input the detection result to the microcomputer 43. Further, the output voltage sensor 45 is arranged at the subsequent stage of the booster circuit 43, and is configured to detect the output voltage from the booster circuit 42 and input the detection result to the microcomputer 43. The boosting units 41a to 41d are connected at the subsequent stage of the output voltage sensor 45 and connected to the input terminal 30 of the power conditioner 3 as one output.

  The LED 46 is controlled to be turned on by the microcomputer 43. Specifically, the LED 46 is configured to perform a predetermined lighting operation when it is determined that the output voltage sensor 45 is abnormal in an abnormality determination process of the output voltage sensor 45 by the microcomputer 43 described later. .

Next, the operation of the junction box 4 configured as described above will be described.
In this connection box 4, the microcomputers 43 a to 43 d of the boosting units 41 a to 41 d monitor the input voltage to the other boosting unit 41 by communicating with the microcomputer 43 of the other boosting unit 41, and the boosting voltage that maximizes the input voltage is achieved. The microcomputer 43a of the unit 41a (here, it is assumed that the output voltage of the solar cell module 2a is the highest. The same applies to the following description) stops the boosting operation of the booster circuit 42a and keeps the input voltage as it is. Output.

  On the other hand, the microcomputers 43b to 43d of the other boosting units 41b to 41d respectively match the output voltages of the boosting circuits 42b to 42d with the input voltages of the boosting unit 41a (that is, the boosting unit having the maximum input voltage). The boost operation is controlled. That is, the other boosting units 41b to 41d are controlled by MPPT (maximum power point tracking) in accordance with the input voltage of the boosting unit 41a having the maximum input voltage.

  Here, regarding this boosting operation, in the present embodiment, a case has been described in which the microcomputers 43a to 43d of the boosting units 41a to 41d each independently determine whether or not to start the boosting operation. The determination of the start / stop of the operation can also be configured to cause the microcomputer 43 of any one boosting unit 41 to determine. In short, the boosting operation of the boosting unit 41 having the maximum input voltage is stopped, and the other boosting units 41 are configured to perform the boosting operation so that the input voltage matches the input voltage of the boosting unit having the maximum input voltage. Good.

  Next, an abnormality determination process for the output voltage sensor 45 in each of the boosting units 41a to 41d configured as described above will be described.

  In the junction box 4 shown in the present embodiment, the microcomputers 43a to 43d of the respective boosting units 41a to 41d determine whether or not there is an abnormality in the output voltage sensor 45 mounted on the own boosting unit 41 as follows. To do.

  That is, as described above, in the junction box 4 shown in the present embodiment, the boost unit 41a having the maximum input voltage does not perform the boost operation, and therefore the input voltage (maximum input voltage) = output voltage in the boost unit 41a. . Further, as described above, the subsequent stages of the boosting units 41a to 41d are wired so as to have one output, so that the output voltages of the boosting units 41b to 41d are all output voltage = the maximum input voltage. Should be.

  On the other hand, each microcomputer 43a-43d of each boosting unit 41a-41d grasps the maximum input voltage in connection with the control of the boosting operation described above.

  Each microcomputer 43a-43d determines abnormality of the output voltage sensor 45 using such known information. That is, each microcomputer 43a-43d compares the detected value of each output voltage sensor 45 and the said maximum input voltage, and if the difference is more than the predetermined value set beforehand, the output voltage sensor 45 of the said step-up unit 41 is concerned. Is determined to be abnormal. On the other hand, if the difference between the two is less than the predetermined value, the output voltage sensor 45 is determined to be normal.

  Then, as a result of this determination, the microcomputer 43 that has determined that the output voltage sensor 45 has an abnormality causes the LED 46 that the microcomputer 43 performs lighting control to perform a predetermined lighting operation (for example, the LED 46 continues to be lit), and outputs The voltage sensor 45 is notified that there is an abnormality. That is, as described above, in the present embodiment, the booster unit 41 is disposed on each independent electrical component board, and thus the LED 46 on the electrical component board of the booster unit 41 having an abnormality in the output voltage sensor 45. Only the lighting operation is performed, and the boosting unit 41 having an abnormality in the output voltage sensor 45 can be easily identified and specified.

  Thus, in the photovoltaic power generation system 1 provided with the junction box 4 according to the present invention, the hardware configuration of the boost unit 41 provided in the conventional junction box is not changed, and only the software of the microcomputer 43 of the boost unit 41 is changed. By doing so, the presence or absence of abnormality of the output voltage sensor 45 can be determined.

  The above-described embodiment shows a preferred embodiment of the present invention, and the present invention is not limited to this, and various design changes can be made within the scope of the invention.

  For example, in the above-described embodiment, the case where the connection box 4 is provided with the four boosting units 41a to 41d is shown, but the connection box 4 only needs to be provided with a plurality of boosting units 41. A configuration in which three or five boosting units are provided may be employed.

  Moreover, although the case where LED46 was used as an alerting | reporting means which alert | reports abnormality of the output voltage sensor 45 was shown in embodiment mentioned above, if it is an apparatus which can alert | report abnormality, alerting means other than LED (for example, liquid crystal display) It is also possible to use a sound generator such as a vessel or a buzzer.

  Further, in the above-described embodiment, the case where the notifying means for notifying the abnormality of the output voltage sensor 45 is arranged on the electrical board of each boosting unit 41 is shown, but the notifying means is independent of the electrical board of the boosting unit 41. (For example, the surface of the housing).

DESCRIPTION OF SYMBOLS 1 Photovoltaic power generation system 2, 2a-2d Solar cell module 3 Power conditioner 31 Converter circuit part 32 Inverter circuit part 41, 41a-41d Boosting unit 42, 42a-42d Boosting circuit 43, 43a-43d Microcomputer (control part)
44, 44a to 44d Input voltage sensor 45, 45a to 45d Output voltage sensor P Power system

Claims (3)

A connection box for connecting the outputs of a plurality of solar cell modules to the input end of the inverter,
A plurality of boosting units having a booster circuit, an input voltage sensor that detects an input voltage of the booster circuit, an output voltage sensor that detects an output voltage of the booster circuit, and a control unit of the booster circuit;
The booster circuit of the booster unit having the maximum input voltage detected by the input voltage sensor stops the boosting operation, while the booster circuits of the other booster units make their output voltages coincide with the maximum input voltage. In what is configured to perform a boost operation,
The control unit of each boosting unit compares the detected value of each output voltage sensor and the maximum input voltage, and if the difference is greater than or equal to a predetermined value, the output voltage sensor of the boosting unit is abnormal A junction box characterized by comprising a control configuration for judging.   2. The junction box according to claim 1, wherein each of the boosting units includes a notifying unit that notifies that when the output voltage sensor is determined to be abnormal. In a solar power generation system including a plurality of solar cell modules,
A solar power generation system comprising the connection box according to claim 1 or 2 as a connection box for connecting each solar cell module to a power conditioner.

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