KR102397597B1 - System for preventing ground faults and reverse currents in solar power generation systems - Google Patents

Abstract

The present invention relates to a system, in which a plurality of solar modules are connected in series in a plurality of strings and the plurality of strings are connected in parallel to each other, and which is configured to detect and prevent ground faults and reverse currents in a solar power generation system in which the strings are connected to an inverter through an output line. As an example, provided is a system for detecting and preventing ground faults and reverse currents, comprising: switch units individually installed between the output line and the strings; string current measurement units individually installed between the output line and the switch unit; a string voltage measurement unit installed between the switch unit and the strings; an output voltage measurement unit connected to the output line; and an integrated control unit which detects and determines a ground fault state for each string by controlling the operation of the switch unit according to a ground fault detection algorithm that is preset when a ground fault occurs, controls an on/off operation of the switch unit according to the current value measured by the string current measurement unit, and controls the on/off operation of the switch unit according to a comparison result of voltage values measured by the string voltage measurement unit and the output voltage measurement unit, respectively. The present invention can remove the diodes which cause fire and reduction in amount of generated power.

Description

SYSTEM FOR PREVENTING GROUND FAULTS AND REVERSE CURRENTS IN SOLAR POWER GENERATION SYSTEMS

An embodiment of the present invention relates to a ground fault and reverse current detection and prevention system of a solar power generation system.

RCM, RCD, etc. for detecting DC ground faults are installed in inverters or switchboards, etc. according to the recently changed laws and regulations of the photovoltaic power generation system, making the DC ground fault detection device mandatory. The whole system stops power generation. In this way, when a DC ground fault occurs in the photovoltaic power generation system, the entire system stops power generation and a lot of power generation loss may occur.

On the other hand, in the photovoltaic system, a reverse voltage prevention diode is installed in a connection panel or a string to prevent reverse voltage (or reverse current) for each string, respectively, but power loss occurs according to the diode forward voltage and forward current, and this power loss heat is generated by Although the heat generated in this way is appropriately designed with a heat dissipation structure for heat dissipation, the diodes may be damaged due to various causes, such as a defective diode unit, defective connection panel manufacturing, or a design that does not have a sufficient heat dissipation structure. Devices (DC breaker, DC fuse, etc.) have a limited current output from the photovoltaic module, so the breaker does not block or the fuse does not blow, which may lead to a fire.

In addition, heat generation of the diode for preventing reverse voltage may decrease system power generation efficiency. In general, the DC circuit breaker breaking current is selected within the range of 1.25 to 2.4 times the rated current, and the DC fuse breaking current is selected within the range of 1.5 to 2.4 times the rated current. does not exceed 1.1 times the rated current, so the fuse does not blow and the possibility of fire is very high.

As the installation of reverse voltage prevention diodes has emerged as a cause of reduced efficiency and fires, the law has recently been amended so that reverse voltage prevention diodes do not have to be installed in solar power generation systems (however, fuses must be installed at the + and - terminals).

Recently, many photovoltaic power generation systems have removed diodes from the connection panel, and in photovoltaic power generation systems that do not have reverse voltage prevention diodes, when partial shade occurs, reverse voltage is applied to the string connected in parallel to the string with a relatively low voltage. As a result, reverse current flows to the shaded string, which can shorten the lifespan of the solar module and sharply reduce the power generation efficiency.

과 같이 나타낼 수 있다.In the case of the diode-embedded photovoltaic power generation system of the past, a diode is connected in series at the end of the photovoltaic module series string and connected to the inverter in a structure connected in parallel with other series strings. At this time, the total current supplied to the inverter is

can be expressed as

로, 이때 인버터로 공급되는 전체 전류는

과 같으며, 해당 스트링은 발전하지 않고, 나머지 스트링들만 발전하게 된다.However, the amount of insolation of the photovoltaic module cannot be consistently the same, and shading may occur depending on various variables. Variables in shading may occur at any time by partial shading by clouds or by fallen leaves or other foreign matter. If partial shading occurs, a voltage difference between each string may occur. For example, if a specific string is shaded, the voltage of the corresponding string is relatively lower than that of other strings. At this time, the voltage difference between the strings occurs

In this case, the total current supplied to the inverter is

Same as , the corresponding string is not developed, only the remaining strings are developed.

However, recently, for reasons such as efficiency and fire, solar power generation systems that do not include diodes are being operated, and if there is no partial shading and the amount of insolation is constant, maximum power generation is possible without loss because there is no diode loss when there is no reverse voltage diode. .

However, the amount of insolation cannot be constant for various reasons, and if it is assumed that shading has occurred in a specific string, the voltage of the corresponding string is relatively lower than that of other strings. .

과 같다. 여기서, P_D는 역전압 방지용 다이오드가 내장된 태양광 발전 시스템의 발전량을 의미하고, P_Delss는 역전압 방지용 다이오드가 없는 태양광 발전 시스템의 발전량을 의미한다.At this time, the total current supplied to the inverter is

same as Here, P _D denotes the amount of power generation of the solar power generation system having a built-in reverse voltage prevention diode, and P _Delss denotes the generation amount of the solar power generation system without the reverse voltage prevention diode.

As such, when comparing the case with and without the diode for preventing reverse voltage (however, ignoring the loss of the diode for preventing reverse voltage), it can be seen that the amount of power generation is reduced when there is no diode despite the same amount of solar radiation. As a result, when there is no change in insolation, it can be seen that the power generation efficiency is relatively high when there is no diode, and when there is a change in insolation, it can be seen that the generation amount is relatively high when there is a diode.

Registered Patent Publication No. 10-1470349 (Registration Date: December 02, 2014) Registered Patent Publication No. 10-1560345 (Registration Date: October 07, 2015)

The embodiment of the present invention increases the quick response to DC ground fault detection in the photovoltaic power generation system, and uses real-time DC ground fault detection and the corresponding detection value to electrically cut off only the string where the ground fault occurs when a DC ground fault occurs to generate photovoltaic power without stopping. Removes the diode that causes fire and reduces power generation, detects the reverse current between strings in real time, and improves photovoltaic power generation performance through on/off control using switch elements, and photovoltaic power generation It provides a ground fault and reverse current detection and prevention system of a solar power generation system that facilitates maintenance for

In the system for detecting and preventing ground fault and reverse current of a photovoltaic power generation system according to an embodiment of the present invention, a plurality of strings formed by connecting a plurality of photovoltaic modules in series are connected in parallel with each other, and the strings are connected to an inverter through an output line To a system for detecting and preventing a ground fault and a reverse current in a solar power generation system connected to, a switch unit installed between the output line and the string, respectively; a string current measuring unit installed between the output line and the switch unit, respectively; a string voltage measuring unit installed between the switch unit and the string; an output voltage measuring unit connected to the output line; And when a ground fault occurs, the operation of the switch unit is controlled according to a preset ground fault detection algorithm to detect and determine the ground fault state for each string, and control the turn-off operation of the switch unit according to the current value measured through the string current measurement unit and an integrated control unit for controlling a turn-on operation of the switch unit according to a comparison result of voltage values measured by the string voltage measuring unit and the output voltage measuring unit, respectively.

In addition, the switch unit may include a relay circuit installed at the + terminal and the - terminal, respectively.

In addition, the integrated control unit sequentially turns off and then on the switch unit in the sequence for the string until a ground fault is not detected when a ground fault occurs, and the first ground fault detection algorithm operation to determine the string in which the ground fault has occurred. Second ground fault detection for determining that a ground fault has occurred in the output line when a ground fault is detected after turning off all of the switch units when a string in which a ground fault has occurred is not detected through the first ground fault detection algorithm If a ground fault is detected after performing an algorithm operation and turning off all the switch units, it is determined that a ground fault has occurred in two or more strings, and the switches are sequentially applied to the strings while maintaining the OFF state for all of the switch units. A third ground fault detection algorithm operation for determining a string in which a ground fault has occurred may be performed by sequentially turning on and then turning off the unit.

In addition, the integrated control unit subtracts the previous string current value measured immediately before the present from the current string current value currently measured through the string current measurement unit, and when the subtraction result is less than 0 and the current string current value is 0 or less , after turning off the corresponding switch unit installed in the string, subtracting the previous string voltage value measured immediately before the present from the current string voltage value currently measured through the string voltage measuring unit, and the output voltage is greater than 0 If it is equal to or greater than the output voltage value measured by the measurement unit, a reverse current detection and prevention operation for turning on the corresponding switch unit may be performed.

In addition, the integrated control unit detects an insulation resistance value and an insulation voltage value for the string, respectively, and calculates a ground fault current value based on the detected insulation resistance value and the insulation voltage value to determine whether the string has a ground fault. can be discerned.

In addition, the integrated control unit, a differential amplifier that receives each input and a division voltage applied through the division resistor respectively installed based on the neutral point of the string, amplifies and outputs a difference between the input division voltage, the differential amplifier An ADC that converts an analog voltage difference signal output through a digital signal to a digital signal, and a digital signal output through the ADC is compared with a preset reference signal. It is possible to determine whether a ground fault has occurred in the photovoltaic power generation system by using a comparator that outputs the generated signal.

According to the present invention, the solar power generation system maintains photovoltaic power generation without stopping by increasing the quick response to DC ground fault detection in the photovoltaic system and using real-time DC ground fault detection and the corresponding detection value to electrically cut off only the string where the ground fault occurs when a DC ground fault occurs. Removes the diodes that cause fire and reduces power generation, detects the reverse current between strings in real time, improves solar power generation performance through on/off control using switch elements, and It is possible to provide a system for detecting and preventing ground faults and reverse currents in a solar power system that facilitates maintenance.

1 is a circuit diagram illustrating an overall configuration of a ground fault and reverse current detection and prevention system and a ground fault detection and prevention operation according to an embodiment of the present invention.
2 is a view showing the direction of current flowing from each string to the inverter during normal operation of the photovoltaic system.
3 is a view illustrating a current direction in a first string when a reverse current occurs in a photovoltaic power generation system.
4 is a flowchart illustrating a control method of a switch unit for detecting and preventing reverse current of a ground fault and reverse current detection and prevention system according to an embodiment of the present invention.
5 is a graph illustrating a string current and a string voltage according to on/off of a switch unit according to an embodiment of the present invention.
6 is a diagram illustrating the determination of whether a ground fault has occurred by the integrated control unit according to an embodiment of the present invention.

Terms used in this specification will be briefly described, and the present invention will be described in detail.

The terms used in the present invention have been selected as currently widely used general terms as possible while considering the functions in the present invention, but these may vary depending on the intention or precedent of a person skilled in the art, the emergence of new technology, and the like. In addition, in a specific case, there is a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the corresponding invention. Therefore, the term used in the present invention should be defined based on the meaning of the term and the overall content of the present invention, rather than the name of a simple term.

In the entire specification, when a part "includes" a certain element, this means that other elements may be further included, rather than excluding other elements, unless otherwise stated. In addition, terms such as "...unit" and "module" described in the specification mean a unit that processes at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software. .

Hereinafter, with reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

1 is a circuit diagram illustrating the overall configuration of a ground fault and reverse current detection and prevention system and a ground fault detection and prevention operation according to an embodiment of the present invention, and FIG. 2 is an inverter in each string during normal operation of the solar power generation system. 3 is a view showing the direction of current in the first string when a reverse current occurs in a photovoltaic power generation system, and FIG. 4 is a ground fault and reverse current detection and prevention according to an embodiment of the present invention. It is a flowchart showing a control method of the switch unit for detecting and preventing reverse current of the system, FIG. 5 is a graph showing the string current and string voltage according to on/off of the switch unit according to an embodiment of the present invention, and FIG. 6 is the present invention It is a diagram illustrating the determination of whether a ground fault has occurred by the integrated control unit according to an embodiment of the present invention.

As shown in FIG. 1, the solar power generation system according to this embodiment includes a plurality of strings (1-String to N-String), and each string (1-String to N-String) is a plurality of solar cells. The optical modules may be connected in series and may be connected in parallel with each other. As described above, the plurality of strings 1-String to N-String connected in parallel may be connected to the inverter through the output line LO.

Referring to FIG. 1 , a ground fault and reverse current detection and prevention system 1000 according to an embodiment of the present invention includes a switch unit 100 , a string current measurement unit 200 , a string voltage measurement unit 300 , and an output voltage measurement It may include at least one of the unit 400 and the integrated control unit 500 .

The switch unit 100 may be installed between the output line LO and the strings 1-String to N-String, respectively. This switch unit 100 is configured to include 2 From A contact relay circuits installed in the + terminal and the - terminal respectively for electrical insulation for each string (1-String to N-String). response is possible.

The string current measuring unit 200 may be installed between the output line LO and the switch unit 100 , respectively. The string current measurement unit 200 may be used to determine an off condition of the switch unit 100 when a reverse current occurs.

The string voltage measuring unit 300 may be installed between the switch unit 100 and the strings 1-String to N-String. The string voltage measuring unit 300 may be used to determine a condition for turning on the switch unit 100 that is in an off state due to generation of a reverse current.

The output voltage measuring unit 400 may be connected to the output line LO, and may detect an output voltage Vout that is output from the strings 1-String to N-String and enters the inverter. The output voltage measuring unit 400 may also be used to determine a condition for turning on the switch unit 100 that is in an off state due to generation of a reverse current.

The integrated control unit 500 may operate to detect a ground fault and detect and prevent a reverse current. First, a ground fault detection operation will be described.

When a ground fault occurs in the photovoltaic system of this embodiment, the integrated control unit 500 controls the on/off operation of the switch unit 100 according to a preset ground fault detection algorithm, respectively, to control the string (1-String to N-) String) can detect and determine the ground fault state. To this end, the integrated control unit 500 controls the on/off operation of the switch unit 100 based on the preset first to third ground fault detection algorithms, respectively, and in any of the strings 1-String to N-String. It can be determined whether a ground fault has occurred and whether a ground fault has occurred in the output line (LO) other than the string (1-String to N-String).

The first ground fault detection algorithm sequentially turns off and then turns on the switch unit 100 in sequence for the strings (1-String to N-String) until a ground fault is not detected when a ground fault occurs, and a ground fault occurs. This is a method of detecting the string.

For example, after turning off the switch unit 100 installed in the first string (1-String), the insulation resistance value of the strings (2-String to N-String) except for the first string (1-String) and Each of the insulation voltage values is detected, and the ground fault current value is calculated based on the detected insulation resistance value and the insulation voltage value. It is possible to determine the presence or absence of a ground fault for each string. At this time, when the ground fault does not disappear (when the ground fault state is maintained), the switch unit 100 installed in the first string (1-String) is turned on, and then moves to the second string (2-String) and the second string The same process may be performed to determine whether a ground fault exists by turning off the switch unit 100 installed in (2-String). This process is carried out sequentially from the 1st string (1-String) to the Nth string (N-String), but when the specific string is turned off while performing until the ground fault disappears, if the ground fault disappears, it is said that a ground fault has occurred in the corresponding string. can be discerned.

At this time, when the integrated control unit 500 detects the occurrence of a ground fault in a specific string through the first ground fault detection algorithm, the state of the string may be transmitted to an external monitoring system, and the switch unit installed in the string in which the ground fault occurred (100) can be maintained in the turned-off state until the administrator check.

In the second ground fault detection algorithm, when a string in which a ground fault is generated is not detected through the first ground fault detection algorithm, that is, when a ground fault is still detected even after all of the switch units 100 are turned off (when the ground fault does not disappear) This is a method of determining or considering that a ground fault has occurred in the output line (LO). In this case, when it is determined that a ground fault has occurred in the output line LO through the second ground fault detection algorithm, the integrated control unit 500 may transmit such state information to an external monitoring system.

In the third ground fault detection algorithm, when a ground fault is not detected after turning off all of the switch units 100 , the strings (1-String to N-String) while maintaining an off state for all of the switch units 100 ), the switch unit 100 is sequentially turned on and then turned off in order to determine the string in which the ground fault has occurred.

For example, after turning on the switch unit 100 installed in the first string 1-String, the insulation resistance value and the insulation voltage value of the first string 1-String are detected, respectively, and the detected insulation resistance value A ground fault current value is calculated based on the over-insulation voltage value, and it can be determined whether a ground fault has occurred in the first string (1-String) based on the calculated ground fault current value. At this time, if a ground fault for the first string (1-String) is not detected, the switch unit 100 installed in the first string (1-String) is turned off, and then goes to the second string (2-String) 2 The switch unit 100 installed in the burn string (2-String) is turned on to detect an insulation resistance value and an insulation voltage value to determine whether a ground fault is present, and a ground fault current value based on the detected insulation resistance value and insulation voltage value It is possible to determine whether a ground fault has occurred in the second string (2-String) by calculating . Through this process, sequentially proceeding from the 1st string (1-String) to the Nth string (N-String) (ground fault inspection for all strings) and determining which string has a ground fault (determining which string has occurred more than 2 faults) )can do.

Meanwhile, the integrated control unit 500 detects an insulation resistance value and an insulation voltage value for the strings (1-String to N-String), respectively, and calculates a ground fault current value based on the detected insulation resistance value and insulation voltage value This was explained as being able to determine the presence or absence of a ground fault for each string. ~N-String), if the insulation resistance value for a specific string is relatively low, a ground fault has not yet occurred for the string, but it is judged that a ground fault is likely to occur and the ground fault for the string Prediction signals can also be transmitted to an external monitoring system.

When a string in which a ground fault has occurred is confirmed through the ground fault monitoring process as described above, the integrated control unit 500 may turn off the switch unit 100 for the string to selectively block only the corresponding channel.

Next, the operation of the integrated control unit 500 for detecting and preventing reverse current will be described.

The integrated control unit 500 controls the turn-off operation of the switch unit 100 according to the current value measured by the string current measurement unit 300 , and the string voltage measurement unit 300 and the output voltage measurement unit 400 . ), it is possible to control the turn-on operation of the switch unit 100 according to a comparison result of each measured voltage value.

As shown in FIG. 2 , when the photovoltaic power generation system operates normally (when reverse current does not occur), the power generated from each string (1-String to N-String) is transferred to the inverter through the output line LO. can be output as However, when shading occurs in at least a portion of the strings (1-String to N-String), for example, PV Module 11 to PV Module 13 as shown in FIG. 3, the power generation voltage of the first string (1-String) is output at a lower level than other strings (2-String~N-String), and at this time, the current gradually decreases with the first string (1-String), and after 0A, the first string (1-String) on the output line (LO) ), a reverse current phenomenon occurs. In this case, the integrated control unit 500 turns off the switch unit 100 installed in the first string (1-String), and when the shadow disappears, the switch unit 100 is turned on again so that the string can continue to generate power. let it be

Hereinafter, an operation control condition of the switch unit 100 for detecting and preventing reverse current will be described in more detail with reference to FIG. 4 .

The integrated control unit 500 subtracts the previous string current value (I _{S_1} ) measured immediately before the present from the current string current value (I _{S_0} ) currently measured through the string current measurement unit 300 to obtain a slope value (I_ _Slope ) ), and the result of subtraction, that is, if the corresponding slope value (I_ _Slope ) is less than 0 (I_ _Slope <0) and the current string current value (I _S0 ) is 0 or less (I _S0 ≤ 0A), the switch installed in the string The reverse current may be prevented by turning off the unit 100 . As such, it is desirable to turn off the corresponding relay when the reverse current is detected or the predicted string current becomes 0A. If the relay is turned off when current flows, the life of the corresponding relay may be shortened, and thus the shortening of the life of the corresponding relay may be minimized.

Meanwhile, the switch unit 100 may be configured as a relay circuit, and the off signal of the relay may be sampled at a time of 10 ms or less.

After the reverse current prevention operation as described above, the integrated control unit 500 performs the previous string voltage value (V _{S_1} ) measured immediately before the present from the current string voltage value (V _{S_0} ) currently measured through the string voltage measurement unit 300 . If the slope value (V_ _Slope ) is obtained, and the result of the subtraction, that is, the corresponding slope value (V_ _Slope ) is greater than 0 and greater than or equal to the output voltage value (Vout) measured through the output voltage measuring unit 400 , the corresponding switch unit 100 turns on so that the string can continue to develop. This is a process of confirming whether the off-line string meets a voltage condition that can be generated. The voltage across the string by the relay is an open-circuit voltage (Voc). Accordingly, when the open-circuit voltage Voc of the corresponding string is equal to or greater than the output voltage Vout, a condition for turning on the corresponding string is established. At this time, since the other strings (2-String to N-String) are in an on state, the voltage and output voltage of each string are the same (V1=V2??Vn=Vout).

5, when the current value of the first string becomes 0A, the first relay RLY1 is turned off, and thereafter, when the voltage V1 (opening voltage) of the first string becomes equal to or higher than the output voltage Vout That is, when the power generation voltage is restored, the No. 1 relay RLY1 is turned on so that the No. 1 string can be generated.

As shown in FIG. 6 , the integrated control unit 500 inputs a division voltage applied through the division resistors R2_1 and R2_2 and the division resistors R2_1 and R2_2 respectively installed based on the neutral point FG of the string, respectively. A differential amplifier 510 that receives, amplifies and outputs the difference between the input divided voltages, an analog digital converter (ADC) 520 that converts an analog voltage difference signal output through the differential amplifier into a digital signal (V _Diff ) 520, And by comparing the digital signal (V _Diff ) output through the ADC (520) with a preset reference signal (Ref_value1), when the value of the digital signal (V _Diff ) exceeds the value of the reference signal (Ref_value1), the ground fault occurrence signal It may be determined whether a ground fault has occurred in the solar power generation system through the output comparator 530 .

What has been described above is only one embodiment for implementing a system for detecting and preventing ground fault and reverse current of a photovoltaic system according to the present invention, and the present invention is not limited to the above embodiment, but in the claims below. As claimed, without departing from the gist of the present invention, it will be said that the technical spirit of the present invention exists to the extent that various modifications can be made by anyone with ordinary knowledge in the field to which the invention pertains.

1000: Earth fault and reverse current detection and prevention system of solar power generation system
100: switch unit
200: string current measurement unit
300: string voltage measurement unit
400: output voltage measurement unit
500: integrated control
R2_1, R2_2: Divider resistor
510: differential amplifier
520: ADC
530: comparator

Claims (6)

It relates to a system for detecting and preventing ground faults and reverse currents in a photovoltaic power generation system in which a plurality of solar modules are connected in series, a plurality of strings made up respectively are connected in parallel with each other, and the strings are connected to an inverter through an output line,
a switch unit installed between the output line and the string, respectively;
a string current measuring unit installed between the output line and the switch unit, respectively;
a string voltage measuring unit installed between the switch unit and the string;
an output voltage measuring unit connected to the output line; and
When a ground fault occurs, the operation of the switch unit is controlled in accordance with a preset ground fault detection algorithm to detect and determine the ground fault state for each string, and control the turn-off operation of the switch unit according to the current value measured through the string current measurement unit, , Ground fault and reverse current of the solar power generation system, characterized in that it comprises an integrated control unit for controlling the turn-on operation of the switch unit according to the comparison result of the voltage values measured through the string voltage measurement unit and the output voltage measurement unit, respectively detection and prevention systems.
According to claim 1,
The switch unit,
Ground fault and reverse current detection and prevention system of a photovoltaic power generation system, characterized in that it includes a relay circuit installed in the + stage and the - stage, respectively.
According to claim 1,
The integrated control unit,
When a ground fault occurs, the first ground fault detection algorithm operation is performed to determine the string in which the ground fault has occurred while sequentially turning off and then turning on the switch unit in the sequence for the string until the ground fault is not detected,
If a string in which a ground fault has occurred is not detected through the first ground fault detection algorithm, the second ground fault detection algorithm operation of determining that a ground fault has occurred in the output line when a ground fault is detected after turning off all the switches do,
If a ground fault is detected after turning off all of the switch units, it is determined that a ground fault has occurred in two or more strings, and the switch units are sequentially turned on in order for the strings while maintaining the OFF state for all of the switch units. A ground fault and reverse current detection and prevention system of a photovoltaic power generation system, characterized in that the third ground fault detection algorithm operation is performed to determine the string in which the ground fault has occurred while turning it off.
According to claim 1,
The integrated control unit,
A previous string current value measured immediately before the present is subtracted from the current string current value currently measured through the string current measurement unit, and if the subtraction result is less than 0 and the current string current value is 0 or less, the corresponding switch installed in the string After the unit is turned off, a previous string voltage value measured immediately before the present is subtracted from the current string voltage value currently measured through the string voltage measuring unit, and the output voltage measured through the output voltage measuring unit while the subtraction result is greater than 0 If the value is greater than the value, a ground fault and reverse current detection and prevention system of a photovoltaic power generation system, characterized in that performing a reverse current detection and prevention operation to turn on the corresponding switch unit.
According to claim 1,
The integrated control unit,
An insulation resistance value and an insulation voltage value for the string are detected, respectively, and a ground fault current value is calculated based on the detected insulation resistance value and the insulation voltage value to determine whether or not a ground fault exists for the string Ground fault and reverse current detection and prevention system in photovoltaic system.
According to claim 1,
The integrated control unit,
A differential amplifier that receives a division voltage applied through the division resistor and the division resistor respectively installed with respect to the neutral point of the string, amplifies and outputs a difference between the input division voltages, and an analog voltage output through the differential amplifier an ADC that converts the difference signal into a digital signal, and a comparator that compares the digital signal output through the ADC with a preset reference signal and outputs a ground fault signal when the value of the digital signal exceeds the value of the reference signal Ground fault and reverse current detection and prevention system of a photovoltaic power generation system, characterized in that it is determined whether a ground fault has occurred in the photovoltaic power generation system by using it.

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