KR20220049713A - the fault detection methods of PV panel using unit vector analysis for I-V curve - Google Patents

Abstract

The present invention relates to a PV panel fault detection method using a unit vector analysis method of an I-V curve, which is to detect a fault and an abnormal symptom of a PV panel of a solar power generation system. The PV panel fault detection method of the present invention comprises the steps of: measuring current (I) and voltage (V) of a PV panel; showing the measured current (I) and voltage (V) as an I-V graph; and showing a scaled I-V graph.

Description

The fault detection methods of PV panel using unit vector analysis for I-V curve

)와 개방전압(

)를 단위 크기인 1로 스케일링하고, 스케일링 후의 정상상태 스케일링 I-V 그래프와 스케일링 후의 이상상태 스케일링 I-V 그래프 상의 벡터값의 크기 차이를 계산하여 시각적 또는 데이터상에서 이상 여부에 대한 정보를 용이하게 제공하는 I-V 곡선의 단위 벡터해석법을 이용한 PV 패널의 고장 감지 방법에 관한 것이다.The present invention detects failures and abnormal signs of PV panels of a photovoltaic system and compares the IV graph of the PV panel in a normal state and the IV graph of the PV panel in an abnormal state in order to classify the failure type, scaling The method is used, but the angle of the vector value is divided into equal angles from 0 to 90 degrees, not simple scaling, and based on this, the short-circuit current (

) and open-circuit voltage (

) is scaled to 1, which is a unit size, and the difference in the magnitude of the vector values on the steady-state scaling IV graph after scaling and the abnormal-state scaling IV graph after scaling is calculated to easily provide information about whether there is an abnormality visually or data IV curve It relates to a failure detection method of a PV panel using the unit vector analysis method of

In December 2017, the Korean government announced the “Renewable Energy 3020 Implementation Plan” to increase the proportion of renewable energy generation to 20% by 2030. Among new and renewable energy, solar power accounts for the highest share, accounting for about 42% of the cumulative supply capacity of new and renewable energy in 2018.

In particular, the photovoltaic power generation system is emerging as an alternative to increase the energy self-sufficiency rate after the zero energy requirement was implemented. The solar power generation system has the advantage of being able to install on a small scale, and that maintenance and unmanned management are possible. Based on these advantages, as the use of solar power generation systems increases, interest in maintenance is also increasing.

The photovoltaic power generation system is largely composed of a PV module (PV panel), a junction box, an inverter, and a monitoring system. As a result of analyzing failures by component for solar power generation systems that have been installed for 4 years in Korea, the failure rate was 18% for PV modules, 65% for inverters, 1% for junction boxes, and 15% for monitoring.

The failure of the photovoltaic power generation system mainly occurs in inverters and modules, and the failure rate of inverters is particularly high. There are two types of inverter failure: an error that can be resolved with a self-protection function and a failure that stops operation. In other words, the inverter stops its operation when a failure that cannot be resolved by the self-protection function occurs, so the failure state of the inverter can be checked in the monitoring system.

1 is an equivalent circuit of a PV panel of a photovoltaic system.

2 is a graph showing I-V output characteristics and P-V output characteristics of a typical PV panel. As shown in Figure 2,

)가 흐르며, When the output terminal of the PV panel is short-circuited, the output of the PV panel

) flows,

)이 된다. When the output terminal of the PV panel is opened, the output voltage is the maximum open voltage (

) becomes

Failure of PV panel, a solar cell module, is classified into safety problems such as power degradation, fire, electric shock, physical danger, and secondary failure, which are states that cannot be returned to normal operation.

Since the failure of such PV panels shows a decrease in power, it is difficult to easily identify the failure, and it is difficult to diagnose the failure even with the naked eye, so performance and failure diagnosis through continuous monitoring are required.

The conventional fault diagnosis divides the power generation status into simple power generation normal, power generation abnormality (failure), and stop through the case where the power generation efficiency is less than the standard power generation efficiency and the case where the measured voltage and the measured current are out of a certain range of the reference voltage and the reference current. . And in the case of measuring the voltage and current for each string, a faulty string is distinguished through this.

3 shows an I-V graph for each failure type of a PV panel.

The failure types of PV panels include peeling, cracking, snail marks, hot spots, bypass diode failure, and potential induced degradation (PID).

)와 개방전압(

)를 단위 크기인 1로 스케일링하고, 스케일링 후의 정상상태 스케일링 I-V 그래프와 스케일링 후의 이상상태 스케일링 I-V 그래프 상의 벡터값의 크기 차이를 계산하여 시각적 또는 데이터상에서 이상 여부에 대한 정보를 용이하게 제공하는 I-V 곡선의 단위 벡터해석법을 이용한 PV 패널의 고장 감지 방법을 개발하기에 이르렀다.Therefore, in comparing the IV graph of the PV panel in the normal state and the IV graph of the PV panel in the abnormal state, the present inventor uses a scaling method, but divides the angle of the vector value into equal angles from 0 to 90 degrees, not simple scaling, Based on this, the short-circuit current (

) and open-circuit voltage (

) is scaled to 1, which is a unit size, and the difference in the magnitude of the vector values on the steady-state scaling IV graph after scaling and the abnormal-state scaling IV graph after scaling is calculated to easily provide information about whether there is an abnormality visually or data IV curve We have developed a failure detection method for PV panels using the unit vector analysis method of

[Document 1] Republic of Korea Patent No. 10-1639940 'PV panel monitoring device and method of solar power generation system', July 08, 2016 [Document 2] Republic of Korea Patent Publication No. 10-2018-0122177 'Solar multimeter, PV string and panel inspection method using the same', November 12, 2018

)와 개방전압(

)를 단위 크기인 1로 스케일링하고, 스케일링 후의 정상상태 스케일링 I-V 그래프와 스케일링 후의 이상상태 스케일링 I-V 그래프 상의 벡터값의 크기 차이를 계산하여 시각적 또는 데이터상에서 이상 여부에 대한 정보를 용이하게 제공하는 I-V 곡선의 단위 벡터해석법을 이용한 PV 패널의 고장 감지 방법을 제공하고자 한다. The present invention is proposed in order to solve the various problems of the prior art as described above. The purpose is to use the scaling method, but simple scaling, in comparing the IV graph of the PV panel in the normal state with the IV graph of the PV panel in the abnormal state in order to detect the failure and abnormal signs of the PV panel of the photovoltaic system. The angle of the vector value is divided into equal angles from 0 to 90 degrees, and based on this, the short-circuit current (

) and open-circuit voltage (

) is scaled to 1, which is a unit size, and the difference in the magnitude of the vector values on the steady-state scaling IV graph after scaling and the abnormal-state scaling IV graph after scaling is calculated to easily provide information about whether there is an abnormality visually or data IV curve The purpose of this study is to provide a method for detecting faults in PV panels using the unit vector analysis method of

In order to solve the above technical problem, the present invention is to detect failures and abnormal signs of a PV panel of a photovoltaic system,

)을 설정하여 상기 PV 패널의 전류(I)와 전압(V)을 측정하고,The resistance value (

) to measure the current (I) and voltage (V) of the PV panel,

After showing the measured current (I) and voltage (V) as an I-V graph,

일 때의

의 값을 얻고,Considering the IV graph as a vector on the first quadrant, 0 to 90 degrees are divided into equal angles and divided into N equal parts, so on the IV graph

when

get the value of

)와 개방전압(

)를 단위 크기인 1로 스케일링하되 상기

의 값이 스케일링된 스케일링 I-V 그래프로 도시하며,The short-circuit current on the IV graph (

) and open-circuit voltage (

) by the unit size of 1, but

Plotted as a scaled IV graph in which the values of

의 값의 크기인

의 값을 취득한 후,the above on the scaling IV graph

is the size of the value of

After getting the value of

의 값과의 차이를 계산하는 것을 특징으로 하는 I-V 곡선의 단위 벡터해석법을 이용한 PV 패널의 고장 감지 방법을 제공한다.On the scaling IV graph of the steady state measured in advance by the above process

It provides a method for detecting a failure of a PV panel using a unit vector analysis method of an IV curve, which is characterized by calculating the difference from the value of .

)와 개방전압(

)를 단위 크기인 1로 스케일링하고, 스케일링 후의 정상상태 스케일링 I-V 그래프와 스케일링 후의 이상상태 스케일링 I-V 그래프 상의 벡터값의 크기 차이를 계산하여 시각적 또는 데이터상에서 이상 여부에 대한 정보를 용이하게 제공하는 I-V 곡선의 단위 벡터해석법을 이용한 PV 패널의 고장 감지 방법을 제공한다. According to the present invention, in comparing the IV graph of the PV panel in the normal state with the IV graph of the PV panel in the abnormal state in order to detect the failure and abnormal signs of the PV panel of the photovoltaic system, a scaling method is used, but simple scaling The angle of the vector value other than 0 is divided into equal angles from 0 to 90 degrees, and based on this, the short-circuit current (

) and open-circuit voltage (

) is scaled to 1, which is a unit size, and the difference in the magnitude of the vector values on the steady-state scaling IV graph after scaling and the abnormal-state scaling IV graph after scaling is calculated to easily provide information about whether there is an abnormality visually or data IV curve A method for detecting failure of PV panels using the unit vector analysis method of

1 is an equivalent circuit of a PV panel of a photovoltaic system.
2 shows a typical IV graph.
3 shows an IV graph for each failure type of a PV panel.
4 is an overall conceptual diagram of a failure detection method of a PV panel using the unit vector analysis method of the IV curve of the present invention.
5 shows an IV graph in the present invention.
6 shows a step of determining the number of angle divisions in the present invention.
Figure 7 shows the internal resistance determination step of the measuring instrument in the present invention.
8 is a diagram illustrating a step of determining a vector value on an IV graph in the present invention.
9 shows the scaled IV graph and the vector analysis (the magnitude of the vector and the phase angle of the vector) determination step in the present invention.
10 shows an IV graph and an output graph before and after scaling of the steady-state current (I) and voltage (V) measured in advance in the present invention.
11 shows an IV graph and an output graph before and after scaling of the current (I) and voltage (V) measured to detect failure and abnormal signs due to the uniform peeling of the PV panel in the present invention.
12 is a graph showing a difference in the magnitude of the vector value of FIG. 11 based on the magnitude of the vector value of FIG. 10 .
13 is another example (bypass diode failure) of FIG. 11 .
14 is another example of FIG. 12 (bypass diode failure).

Hereinafter, the present invention will be described in more detail through embodiments in which the concept of the present invention as described above is preferably implemented in conjunction with the accompanying drawings.

4 is an overall conceptual diagram of a failure detection method of a PV panel using the unit vector analysis method of the I-V curve of the present invention.

The PV panel failure detection method using the unit vector analysis method of the I-V curve of the present invention is a method for classifying the introduced PV panel failure based on the I-V curve,

The vector analysis method (compare the size difference of vectors) is used.

In order to implement this method, I-V curve data in a normal state must first be secured as reference data.

This is a method of classifying failures by thinking of I-V curve data as one vector and detecting the difference in magnitude of vectors having the same phase angle.

When the I-V curve data is considered as a vector on the first quadrant, the open-circuit voltage (Voc) and the short-circuit current (Isc) can be interpreted as vectors having phase angles of 0 degrees and 90 degrees, respectively.

Since the x-axis and y-axis of the I-V curve mean voltage (V) and current (I), respectively, the slope means the reciprocal of resistance, that is, conductance.

, 0)이고, 이는 크기(

)가

이고 위상각이 0도인 벡터

를 의미하고, 이를 토대로 기울기는 0이고 무한대의 저항(즉, 기울기의 역수)을 의미함을 알 수 있다. For example, the coordinates of the open-circuit voltage data in the IV curve are (

, 0), which is the size (

)go

and a vector with a phase angle of 0 degrees

, and based on this, it can be seen that the slope is 0 and means infinite resistance (ie, the reciprocal of the slope).

)이고, 이는 크기(

)가

이고 위상각이 90도인 벡터

을 의미하고, 이를 토대로 기울기는 무한대이고 0의 저항(즉, 기울기의 역수)을 의미함을 알 수 있다.Similarly, the coordinates of the short-circuit current data are (0,

), which is the size (

)go

and a vector with a phase angle of 90 degrees

, and based on this, it can be seen that the slope is infinite and means zero resistance (ie, the reciprocal of the slope).

In the present invention, the method of acquiring I-V curve data for vector analysis can be summarized as follows.

)과 단락전류(

)를 측정하고 각 데이터를 벡터

와

으로 설정1) open voltage (

) and short-circuit current (

) and vector each data

Wow

set to

2) Decide how many data from 0 degrees to 90 degrees are to be analyzed (that is, if 90 degrees is expressed in N equal parts, it is analyzed as a total of N+1 data including 0 degrees)

의 결정3) for IV curve data acquisition

decision of

Therefore, when acquiring the I-V curve data, the resistance value is set for the phase angles having the same interval. By calculating the difference in the magnitude of the vector according to the phase angle in the I-V curve of the PV module that has been tested for failure based on the I-V curve of the normal PV module, the presence or absence of a failure and the type of failure can be determined.

Hereinafter, the present invention will be described in detail.

The failure detection method of a PV panel using the unit vector analysis method of the I-V curve of the present invention,

It is to detect failures and abnormal signs of PV panels of photovoltaic power generation systems.

)을 설정하여 상기 PV 패널의 전류(I)와 전압(V)을 측정하고,The resistance value (

) to measure the current (I) and voltage (V) of the PV panel,

After showing the measured current (I) and voltage (V) as an I-V graph,

일 때의

의 값을 얻고,Considering the IV graph as a vector on the first quadrant, 0 to 90 degrees are divided into equal angles and divided into N equal parts, so on the IV graph

when

get the value of

)와 개방전압(

)를 단위 크기인 1로 스케일링하되 상기

의 값이 스케일링된 스케일링 I-V 그래프로 도시하며,The short-circuit current on the IV graph (

) and open-circuit voltage (

) by the unit size of 1, but

Plotted as a scaled IV graph in which the values of

의 값의 크기인

의 값을 취득한 후,the above on the scaling IV graph

is the size of the value of

After getting the value of

의 값과의 차이를 계산하는 것을 특징으로 한다.On the scaling IV graph of the steady state measured in advance by the above process

It is characterized in that the difference with the value of is calculated.

5 shows an I-V graph in the present invention.

)와 개방전압(

)을 포함한 전류(I)와 전압(V)를 측정하여 I-V 그래프로 도시한 것이다.Specifically, Figure 5 shows the short-circuit current (

) and open-circuit voltage (

) including current (I) and voltage (V) are measured and shown as an IV graph.

은 on the drawing

silver

을 만족한다.

is satisfied with

6 shows a step of determining the number of angle divisions in the present invention.

일 때의

의 값을 얻는 단계를 도시한 것이다.Specifically, considering the IV graph as a vector on the first quadrant, 0 to 90 degrees are divided into equal angles and divided into N equal parts.

when

It shows the steps to obtain the value of .

이며,At this time

is,

이고,

ego,

이다.

am.

Since N is preferably 90,

A total of 91 data can be acquired between 0 and 90 degrees.

Figure 7 shows the internal resistance determination step of the measuring instrument in the present invention,

8 is a diagram illustrating a step of determining a vector value on an I-V graph in the present invention.

As shown,

)의 경우,The present invention provides an internal resistance (

)In the case of,

의 각도

이 상기 스케일링 후 각도가 상기

가 되도록 설정되는 것을 특징으로 한다.Vector value on the IV graph

angle of

After this scaling, the angle is

It is characterized in that it is set to become

Specifically,

이고,

ego,

이며,

is,

이므로,

Because of,

이 된다.

becomes this

9 shows the scaled I-V graph and the vector analysis (the magnitude of the vector and the phase angle of the vector) determination step in the present invention.

As shown,

이고,

ego,

이며,

is,

이다.

am.

10 shows an I-V graph and an output graph before and after scaling of the steady-state current (I) and voltage (V) measured in advance in the present invention.

Specifically, FIG. 10(a) is a graph before scaling, and FIG. 10(b) is a graph after scaling.

11 shows an I-V graph and an output graph before and after scaling of the current (I) and voltage (V) measured in order to detect failures and abnormal signs due to uniform peeling of the PV panel in the present invention.

Specifically, FIG. 11(a) is a graph before scaling, and FIG. 11(b) is a graph after scaling.

12 is a graph showing a difference in the magnitude of the vector value of FIG. 11 based on the magnitude of the vector value of FIG. 10 .

12 is a graph showing the uniform peeling state in FIG. 3,

Specifically, the y-axis represents the difference obtained by subtracting the magnitude of the vector value of FIG. 11(b) from the magnitude of the vector value of FIG.

That is, the present invention is scaled for each angle, so that a defect type such as uniform peeling can be directly obtained visually or as a data numerical value.

)의 최대값을 갖는 위상각이 최대전력 위상각보다 큰 특징을 보이고 최대전력 위상각 보다 작은 영역(즉, 개방전압에 가까운 영역)에서는 벡터크기의 차이가 0에 수렴하는 반면 최대전력 위상각보다. 큰 영역(즉, 단락전류에 가까운 영역)에서는 벡터크기의 차이가 일정 크기에 수렴하는 경향을 보인다. 이때, 단락전류의 차이가 정상적인 PV모듈과 균일박리 고장을 보이는 PV모듈의 차이를 설명하는 가장 핵심적인 요소임을 알 수 있다.In case of uniform peeling failure, the short-circuit current is lower than that of normal PV modules. This characteristic is due to the difference in vector size (

), the phase angle with the maximum value is larger than the maximum power phase angle, and in the region smaller than the maximum power phase angle (that is, the region close to the open-circuit voltage), the difference in vector magnitude converges to 0, whereas the . In a large region (ie, a region close to the short-circuit current), the difference in vector magnitude tends to converge to a certain magnitude. At this time, it can be seen that the difference in short-circuit current is the most important factor explaining the difference between a normal PV module and a PV module showing a uniform peeling failure.

13 is another example of FIG. 11 , and FIG. 14 is another example of FIG. 12 ,

A bypass diode failure is shown.

In case of a bypass diode failure, the open circuit voltage is lower than that of a normal PV module. 14, the difference in vector magnitude converges to 0 in a region larger than the maximum power phase angle (that is, a region close to the short-circuit current), whereas in a region smaller than the maximum power phase angle (that is, a region close to the open-circuit voltage) in FIG. The difference in vector size tends to converge to a certain size. At this time, it can be seen that the difference in open-circuit voltage is the most important factor explaining the difference between a normal PV module and a PV module showing bypass diode failure.

The present invention is applied and implemented in a PV panel failure detection device equipped with dedicated software and hardware.

Although the present invention has been described in relation to the preferred embodiment as mentioned above, various modifications and variations are possible without departing from the gist of the present invention, and can be used in various fields.

Accordingly, the claims of the present invention include modifications and variations that fall within the true scope of the invention.

Claims (2)

It is to detect failures and abnormal signs of PV panels of photovoltaic power generation systems.
The resistance value (

) to measure the current (I) and voltage (V) of the PV panel,
After showing the measured current (I) and voltage (V) as an IV graph,
Considering the IV graph as a vector on the first quadrant, 0 to 90 degrees are divided into equal angles and divided into N equal parts, so on the IV graph

when

get the value of
The short-circuit current on the IV graph (

) and open-circuit voltage (

) by the unit size of 1, but

Plotted as a scaled IV graph where the values of
the above on the scaling IV graph

is the size of the value of

After getting the value of
On the scaling IV graph of the steady state measured in advance by the above process

A method for detecting failure of a PV panel using a unit vector analysis method of an IV curve, characterized in that the difference with the value of is calculated.
In claim 1,
The internal resistance of the measuring instrument for measuring the current (I) and voltage (V) of the PV panel

)In the case of,
Vector value on the IV graph

angle of

After this scaling, the angle is

A method for detecting failure of a PV panel using a unit vector analysis method of an IV curve, characterized in that it is set to become

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