阅读说明：本技术 一种光伏阵列故障检测方法 (Photovoltaic array fault detection method ) 是由 沈克强 滕腾 于 2018-07-27 设计创作，主要内容包括：本发明涉及一种光伏阵列故障检测方法,减少了所用电压传感器的数量,降低了故障检测系统的成本,保证了较高检测分辨度,并且通过数据采集系统和上位机,实现了对光伏阵列的实时在线检测,可以应用到大规模光伏阵列中,满足了实际应用中的多种需要。(The invention relates to a photovoltaic array fault detection method, which reduces the number of voltage sensors, lowers the cost of a fault detection system, ensures higher detection resolution, realizes real-time online detection of a photovoltaic array through a data acquisition system and an upper computer, can be applied to large-scale photovoltaic arrays, and meets various requirements in practical application.)

1. A photovoltaic array fault detection method is used for carrying out fault detection on N x M photovoltaic arrays and is characterized by comprising the following steps of, wherein M represents the number of strings in the photovoltaic arrays, M is an even number, and N represents the number of photovoltaic panels in each string of the photovoltaic arrays;

step A, detecting and obtaining a current value I on each string in the photovoltaic array₁、…、I_MAnd entering step B;

and B, sequentially detecting and obtaining the voltage U between the nodes of the 2l +1 th string and the 2l +2 th string in the photovoltaic array according to the sequence of the strings in the photovoltaic array_1,2l+1、…、U_n,2l+1、…、U_N-1,2l+1L is an integer, and

c, judging the current value I of each string in the photovoltaic array₁、…、I_MIf the voltage values are the same, indicating that the photovoltaic array works normally, and ending the fault detection method; otherwise, entering the step D;

step D, obtaining each current value I which is smaller than the rest current values_mI.e. individual fault currents I_mFor each fault current I_mAnd respectively obtaining the fault photovoltaic cell panel in each string according to the corresponding string, so as to realize the fault detection of the photovoltaic array.

2. The method of claim 1, wherein the method comprises: said step (c) isD, respectively aiming at each fault current I_mCorresponding strings are subjected to the following steps D1 to D3, and the detection of the faulty photovoltaic cell panel in each string is realized;

step D1, if m is 2l +1, proceeding to step D2; if m is 2l +2, go to step D3;

step D2., for the mth string in the photovoltaic array, executing the following steps D2-1 to D2-5, wherein i is greater than or equal to 1 and less than or equal to M, and i is not equal to M;

step D2-1, judge U_N-1,mWhether or not less than U_N-1,iAnd if yes, the Nth photovoltaic cell panel A in the mth string of the photovoltaic array is represented_N,_mIs a normal photovoltaic cell panel, otherwise represents the Nth photovoltaic cell panel A in the mth string of the photovoltaic array_N,mIs a faulty photovoltaic cell panel;

step D2-2. initialize k ═ N-1;

step D2-3, judge | U_k-1,i-U_k-1,mWhether | is greater than | U_k,i-U_k,mIf yes, the k th photovoltaic cell panel A in the mth string of the photovoltaic array is represented_k,mIs a normal photovoltaic panel, otherwise represents the kth photovoltaic panel A in the mth string of the photovoltaic array_k,mIs a faulty photovoltaic cell panel;

d2-4, judging whether k is equal to 2, if yes, entering the step D2-5; otherwise, updating the value of k by subtracting 1, and returning to the step D2-3;

d2-5, judging U_1,mWhether or not less than U_1,iAnd if yes, the 1 st photovoltaic cell panel A in the mth string of the photovoltaic array is represented_1,mFor normal photovoltaic panel, otherwise the 1 st photovoltaic panel A in the mth string of the photovoltaic array_1,mIs a faulty photovoltaic cell panel;

step D3, aiming at the mth string in the photovoltaic array, executing the following steps D3-1 to D3-5, wherein i is more than or equal to 1 and less than or equal to M, and i is not equal to M;

step D3-1, judge U_1,m-1Whether or not less than U_1,iAnd if yes, the Nth photovoltaic cell panel A in the mth string of the photovoltaic array is represented_N,mIs a normal photovoltaic cell panel, otherwise represents the Nth photovoltaic cell panel A in the mth string of the photovoltaic array_N,mIs a faulty photovoltaic cell panel;

step D3-2. initialize v ═ 1;

step D3-3, judge | U_v+1,i-U_v+1,m-1Whether | is greater than | U_v,i-U_v,m-1If yes, the method represents the Nth-v photovoltaic cell panel A in the mth string of the photovoltaic array_N-v,mIs a normal photovoltaic cell panel, otherwise represents the Nth-v photovoltaic cell panel A in the mth string of the photovoltaic array_N-v,mIs a faulty photovoltaic cell panel;

d3-4, judging whether v is equal to N-2, if yes, entering the step D3-5; otherwise, updating by adding 1 according to the value of v, and returning to the step D3-3;

d3-5, judging U_N-1,m-1Whether or not less than U_N-1,iAnd if yes, the 1 st photovoltaic cell panel A in the mth string of the photovoltaic array is represented₁,_mFor normal photovoltaic panel, otherwise the 1 st photovoltaic panel A in the mth string of the photovoltaic array_1,mIs a faulty photovoltaic cell panel.

Technical Field

The invention relates to a photovoltaic array fault detection method, and belongs to the technical field of photovoltaic array fault detection.

Background

At present, the fault detection method of the photovoltaic array mainly comprises an infrared image detection method, an electric signal detection method and a fault detection method based on a sensor. A certain temperature difference exists between the solar cell panels which work normally and work abnormally, and the infrared image detection method utilizes the temperature characteristic of the object to be detected to detect. The principle of the electrical signal detection method, such as the high-frequency signal injection method, is to inject a high-frequency signal into the photovoltaic cell panel, detect the reflected signal of the photovoltaic cell panel, and detect and locate the fault of the photovoltaic array according to different changes of the reflected signal. The fault detection method based on the sensor and various improvements made on the fault detection method realize online fault detection and positioning to a certain extent.

However, the infrared image detection method has the disadvantages of low detection precision, high equipment cost, poor real-time performance and the like, and the detection method based on the electric signal has self limitations, for example, the high-frequency signal injection method is used for detecting and positioning faults of the photovoltaic array, but the method has no real-time performance, has high requirements on equipment, has limited detection precision, and has the disadvantages of more sensors, low detection precision, difficult popularization of a detection structure in large-scale photovoltaic array application and the like.

Disclosure of Invention

The invention aims to solve the technical problem of providing a photovoltaic array fault detection method which realizes higher detection precision, can carry out real-time online detection on a photovoltaic array and can be popularized in large-scale photovoltaic array application.

The invention adopts the following technical scheme for solving the technical problems: the invention designs a photovoltaic array fault detection method, which is used for carrying out fault detection on an N x M photovoltaic array and comprises the following steps of, wherein M represents the number of strings in the photovoltaic array, M is an even number, and N represents the number of photovoltaic cell panels in each string of the photovoltaic array;

step A, detecting and obtaining a current value I on each string in the photovoltaic array₁、…、I_MAnd entering step B;

and B, sequentially detecting and obtaining the voltage U between the nodes of the 2l +1 th string and the 2l +2 th string in the photovoltaic array according to the sequence of the strings in the photovoltaic array_1,2l+1、…、U_n,2l+1、…、U_N-1,2l+1L is an integer, and

then entering step C;

c, judging the current value I of each string in the photovoltaic array₁、…、I_MIf the voltage values are the same, indicating that the photovoltaic array works normally, and ending the fault detection method; otherwise, entering the step D;

step D, obtaining each current value I which is smaller than the rest current values_mI.e. individual fault currents I_mFor each fault current I_mAnd respectively obtaining the fault photovoltaic cell panel in each string according to the corresponding string, so as to realize the fault detection of the photovoltaic array.

As a preferred technical scheme of the invention: in the step D, aiming at each fault current I_mThe corresponding strings are implemented as the following steps D1 to D3 to realize each stringDetecting a faulty photovoltaic panel in (1);

step D1, if m is 2l +1, proceeding to step D2; if m is 2l +2, go to step D3;

step D2., for the mth string in the photovoltaic array, executing the following steps D2-1 to D2-5, wherein i is greater than or equal to 1 and less than or equal to M, and i is not equal to M;

step D2-1, judge U_N-1,mWhether or not less than U_N-1,iAnd if yes, the Nth photovoltaic cell panel A in the mth string of the photovoltaic array is represented_N,mIs a normal photovoltaic cell panel, otherwise represents the Nth photovoltaic cell panel A in the mth string of the photovoltaic array_N,mIs a faulty photovoltaic cell panel;

step D2-2. initialize k ═ N-1;

step D2-3, judge | U_k-1,i-U_k-1,mWhether | is greater than | U_k,i-U_k,mIf yes, the k th photovoltaic cell panel A in the mth string of the photovoltaic array is represented_k,mIs a normal photovoltaic panel, otherwise represents the kth photovoltaic panel A in the mth string of the photovoltaic array_k,_mIs a faulty photovoltaic cell panel;

d2-4, judging whether k is equal to 2, if yes, entering the step D2-5; otherwise, updating the value of k by subtracting 1, and returning to the step D2-3;

d2-5, judging U_1,mWhether or not less than U_1,iAnd if yes, the 1 st photovoltaic cell panel A in the mth string of the photovoltaic array is represented_1,mFor normal photovoltaic panel, otherwise the 1 st photovoltaic panel A in the mth string of the photovoltaic array_1,mIs a faulty photovoltaic cell panel;

step D3, aiming at the mth string in the photovoltaic array, executing the following steps D3-1 to D3-5, wherein i is more than or equal to 1 and less than or equal to M, and i is not equal to M;

step D3-1, judge U_1,m-1Whether or not less than U_1,iAnd if yes, the Nth photovoltaic cell panel A in the mth string of the photovoltaic array is represented_N,mIs a normal photovoltaic cell panel, otherwise represents the Nth photovoltaic cell panel A in the mth string of the photovoltaic array_N,mIs a faulty photovoltaic cell panel;

step D3-2. initialize v ═ 1;

step D3-3, judge | U_v+1,i-U_v+1,m-1Whether | is greater than | U_v,i-U_v,m-1If yes, the method represents the Nth-v photovoltaic cell panel A in the mth string of the photovoltaic array_N-v,mIs a normal photovoltaic cell panel, otherwise represents the Nth-v photovoltaic cell panel A in the mth string of the photovoltaic array_N-v,mIs a faulty photovoltaic cell panel;

d3-4, judging whether v is equal to N-2, if yes, entering the step D3-5; otherwise, updating by adding 1 according to the value of v, and returning to the step D3-3;

d3-5, judging U_N-1,m-1Whether or not less than U_N-1,iAnd if yes, the 1 st photovoltaic cell panel A in the mth string of the photovoltaic array is represented_1,mFor normal photovoltaic panel, otherwise the 1 st photovoltaic panel A in the mth string of the photovoltaic array_1,mIs a faulty photovoltaic cell panel.

Compared with the prior art, the photovoltaic array fault detection method adopting the technical scheme has the following technical effects: the photovoltaic array fault detection method designed by the invention reduces the number of voltage sensors, lowers the cost of a fault detection system, ensures higher detection resolution, realizes real-time online detection of the photovoltaic array through the data acquisition system and the upper computer, can be applied to large-scale photovoltaic arrays, and meets various requirements in practical application.

Drawings

FIG. 1 is a schematic diagram of a series-parallel configuration of a generic photovoltaic array;

fig. 2 is a schematic diagram of an N x M photovoltaic array detection structure provided by the present invention;

fig. 3 is a schematic diagram of a 4 × 6 photovoltaic array detection structure provided by the present invention.

Detailed Description

The following description will explain embodiments of the present invention in further detail with reference to the accompanying drawings.

In practical photovoltaic power station applications, in order to obtain a large output current and output voltage, photovoltaic panels need to be connected in a certain connection manner for use. Common connection modes include a series connection mode, a parallel connection mode, a series-parallel connection mode, a full connection mode and a bridge connection mode, and most connection modes used in application are the series-parallel connection mode. In order to overcome the defects of the existing detection methods, the battery panel with the fault is quickly and accurately positioned. As shown in fig. 1, the connection mode of the cell panels in the embodiment of the present invention is a series-parallel connection mode, which is based on the consideration of popularization to an actual photovoltaic power station. And the internal resistance of the voltage sensor used in the detection structure can be considered to be infinite, so the influence on the whole photovoltaic array can be ignored.

As shown in FIG. 2, each branch is connected with a current sensor with the reading I₁，…，I_M. A voltage sensor is connected between each node between adjacent strings, and the voltage sensor reading between the first string and the second string is respectively U_1,1，U_2,1，…，U_N-1,1The voltage sensor reading between the third string and the fourth string is U respectively_1,3，U_2,3，…，U_N-1,3，U_(N-1)3By analogy, the reading of the voltage sensor between the M-1 th string and the M-th string is U respectively_1,M-1，U_2,M-1，…，U_N-1,M-1。

Under normal conditions, the current value of each branch should be the same, and the potential of the corresponding node on the branch should also be the same. When a certain component in the array fails, the current value of the group of strings is reduced, the reading of the voltage sensor connected with the strings has deviation compared with the reading of the voltage sensors connected with other normal strings, and the positioning of the failed component of the strings can be realized by comparing the deviation.

The invention designs a photovoltaic array fault detection method, which is used for carrying out fault detection on an N x M photovoltaic array and comprises the following steps of, wherein M represents the number of strings in the photovoltaic array, M is an even number, and N represents the number of photovoltaic cell panels in each string of the photovoltaic array;

step A, detecting and obtaining a current value I on each string in the photovoltaic array₁、…、I_MAnd proceeds to step B.

And B, sequentially detecting and obtaining the electricity between the nodes of the 2l +1 th string and the 2l +2 th string in the photovoltaic array according to the sequence of the strings in the photovoltaic arrayPress U_1,2l+1、…、U_n,2l+1、…、U_N-1,2l+1L is an integer, and

then step C is entered.

C, judging the current value I of each string in the photovoltaic array₁、…、I_MIf the voltage values are the same, indicating that the photovoltaic array works normally, and ending the fault detection method; otherwise, entering the step D.

Step D, obtaining each current value I which is smaller than the rest current values_mI.e. individual fault currents I_mFor each fault current I_mAnd respectively obtaining the fault photovoltaic cell panel in each string according to the corresponding string, so as to realize the fault detection of the photovoltaic array.

In the step D, the fault currents I are respectively aimed at_mAnd (4) executing the following steps D1 to D3 on the corresponding strings to realize the detection of the faulty photovoltaic panels in each string.

Step D1, if m is 2l +1, proceeding to step D2; if m is 2l +2, the process proceeds to step D3.

Step D2. executes the following steps D2-1 through D2-5 for the mth string in the photovoltaic array, where i is greater than or equal to 1 and less than or equal to M, and i is not equal to M.

Step D2-1, judge U_N-1,mWhether or not less than U_N-1,iAnd if yes, the Nth photovoltaic cell panel A in the mth string of the photovoltaic array is represented_N,mIs a normal photovoltaic cell panel, otherwise represents the Nth photovoltaic cell panel A in the mth string of the photovoltaic array_N,mIs a faulty photovoltaic cell panel.

Step D2-2. initialize k ═ N-1.

Step D2-3, judge | U_k-1,i-U_k-1,mWhether | is greater than | U_k,i-U_k,mIf yes, the k th photovoltaic cell panel A in the mth string of the photovoltaic array is represented_k,mIs a normal photovoltaic panel, otherwise represents the kth photovoltaic panel A in the mth string of the photovoltaic array_k,mIs a faulty photovoltaic cell panel.

D2-4, judging whether k is equal to 2, if yes, entering the step D2-5; otherwise, the value of k is updated by subtracting 1 and the step D2-3 is returned.

D2-5, judging U_1,mWhether or not less than U_1,iAnd if yes, the 1 st photovoltaic cell panel A in the mth string of the photovoltaic array is represented_1,mFor normal photovoltaic panel, otherwise the 1 st photovoltaic panel A in the mth string of the photovoltaic array_1,mIs a faulty photovoltaic cell panel.

And D3, executing the following steps D3-1 to D3-5 aiming at the mth string in the photovoltaic array, wherein i is more than or equal to 1 and less than or equal to M, and i is not equal to M.

Step D3-1, judge U_1,m-1Whether or not less than U_1,iAnd if yes, the Nth photovoltaic cell panel A in the mth string of the photovoltaic array is represented_N,mIs a normal photovoltaic cell panel, otherwise represents the Nth photovoltaic cell panel A in the mth string of the photovoltaic array_N,mIs a faulty photovoltaic cell panel.

Step D3-2. initialize v ═ 1.

Step D3-3, judge | U_v+1,i-U_v+1,m-1Whether | is greater than | U_v,i-U_v,m-1If yes, the method represents the Nth-v photovoltaic cell panel A in the mth string of the photovoltaic array_N-v,mIs a normal photovoltaic cell panel, otherwise represents the Nth-v photovoltaic cell panel A in the mth string of the photovoltaic array_N-v,mIs a faulty photovoltaic cell panel.

D3-4, judging whether v is equal to N-2, if yes, entering the step D3-5; otherwise, updating by adding 1 for the value of v, and returning to the step D3-3.

D3-5, judging U_N-1,m-1Whether or not less than U_N-1,iAnd if yes, the 1 st photovoltaic cell panel A in the mth string of the photovoltaic array is represented_1,mFor normal photovoltaic panel, otherwise the 1 st photovoltaic panel A in the mth string of the photovoltaic array_1,mIs a faulty photovoltaic cell panel.

By applying the photovoltaic array fault detection method designed by the invention, as shown in fig. 3, a 6 x 4 photovoltaic array detection structure is analyzed. Each string of modules is connected with a current sensor with the reading I₁、I₂、I₃、I₄. 5 voltage sensors are connected between two adjacent strings, 10 voltage sensors are needed by 4 branches, and the reading is shown in the figureThe labels are shown.

Comparing current sensor readings I₁、I₂、I₃、I₄The size of (2). If the mth string fails, I_m＜I_m'Where 0 < m '< 5 and m ≠ m', then the location of the failed component on the mth string is determined from the voltage sensor readings. Assuming that the 3 rd string fails, the determination process is as follows:

comparison U_5,3And U_5,1Size of (1), if U_5,3<U_5,1Then the photovoltaic cell panel A_5,3Normal, otherwise photovoltaic panel a_5,3A failure;

if U_4,1-U_4,3|>|U_5,1-U_5,3I, then photovoltaic panel a_4,3Normal, otherwise photovoltaic panel a_4,3A failure;

if U_3,1-U_3,3|>|U_4,1-U_4,3I, then photovoltaic panel a_3,3Normal, otherwise photovoltaic panel a_3,3A failure;

if U_2,1-U_2,3|>|U_3,1-U_3,3I, then photovoltaic panel a_2,3Normal, otherwise photovoltaic panel a_2,3A failure;

if U_1,1-U_1,3|>|U_2,1-U_2,3I, then photovoltaic panel a_1,3Normal, otherwise photovoltaic panel a_1,3A failure;

finally if U_1,3<U_1,1Then the photovoltaic cell panel A_1,3Normal, otherwise photovoltaic panel a_1,3And (4) failure.

By comparing the voltage difference one by one, whether each component of the string has a fault can be sequentially judged, so that the fault location of the string of components is realized, and the resolution is 1.

In summary, embodiments of the present invention provide a method for detecting a failure of a photovoltaic array, which reduces the number of voltage sensors used, reduces the cost of a failure detection system, ensures high detection resolution, and implements real-time online detection on the photovoltaic array through a data acquisition system and an upper computer, so that the method can be applied to a large-scale photovoltaic array, and meets various requirements in practical applications.

The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.