JP2018026906A - Inspection method for photovoltaic power generation module and inspection device used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method and inspection device for photovoltaic power generation module, capable of easily and exactly verifying power generation performance of a photovoltaic power generation module during power transmission without stopping power transmission.SOLUTION: The inspection method for a photovoltaic power generation module M, to which a plurality of cells c1 to c18 are electrically connected in series, includes: identifying the pair of cells c1, c18 along a current flow, measuring a surface potential difference of the identified cell using a pair of surface potential sensors S1, S2 with a reference potential in common and evaluating the performance of the photovoltaic power generation module M according to the potential difference.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an inspection method and an inspection apparatus for a photovoltaic power generation module.

In a power generation system using a solar power generation module, a large number of power generation modules are connected in series and in parallel. Each power generation module is configured by connecting a plurality of power generation cells in series.
In such a power generation system, if any of the cells connected in series fails, the overall power generation capability is significantly reduced. Therefore, if a defective cell or a power generation module including a defective cell is left unattended, the amount of power generation is reduced, resulting in a large economic loss.

Therefore, it is important to confirm whether or not the power generation module has a normal power generation capacity.
And in order to evaluate the capability of a module, conventionally, the IV characteristic was sometimes measured. This IV characteristic represents the relationship between current and voltage during power generation in each cell.

JP 9-186212 A JP 2006-118983 A

However, in order to measure the IV characteristics, it was necessary to stop power transmission and connect the measurement terminal to the power output terminal. In other words, it is impossible to measure while transmitting power.
Thus, since power transmission must be stopped each time the power generation module is inspected, an economic loss occurs. In particular, in a facility in which a large number of modules are connected in series, it is uneconomical that power transmission must be stopped while all the modules are inspected one by one.
In addition, in order to measure the IV characteristic in an arbitrary module unit, it is necessary to temporarily disconnect a part of the wiring connected in series, and it is not always easy to measure.

On the other hand, an inspection method for detecting the current value of the power generation cell in a non-contact manner without stopping power transmission is also considered. This method uses a magnetic field generated by a current flowing in the wiring. Therefore, it is necessary to match the direction of the current measuring device with the direction of the magnetic field or current wiring.
However, it is not easy to adjust the direction of the measuring device to a predetermined direction during measurement. In particular, when the power generation module is at a high place, it is almost impossible for the measurer to reach his / her hand and make the measuring device correspond to a specific cell and to accurately align the direction. And if the direction of the measuring instrument is dispersed, the reliability of the detected current value is lowered.

  An object of the present invention is to provide a solar power generation module inspection method and an inspection apparatus used therefor that can easily and accurately confirm power generation performance without stopping power transmission.

  1st invention is the test | inspection method of the photovoltaic power generation module which electrically connected the some cell in series, Comprising: A pair of cells are specified from the said cell group connected in series, The surface between the specified cells The potential difference is measured by a pair of surface potential sensors having a common reference potential, and the performance of the photovoltaic power generation module is evaluated according to the potential difference.

A second invention is an inspection apparatus for a photovoltaic power generation module in which a plurality of cells are electrically connected in series, and at least a pair of surface potential sensors that detect the surface potential of the cells connected in series in a non-contact manner. And a calculation unit that calculates the potential difference between the pair of cells based on the detection value of each surface potential sensor and outputs the calculation result. The calculation unit is connected to the calculation unit. The surface potential sensor is characterized in that a reference potential portion is connected and the reference potential is shared.
When the number of surface potential sensors connected to the calculation unit is three or more, there are a plurality of pairs of cells in which a potential difference is calculated.

  According to a third aspect of the present invention, the surface potential sensor includes a detection electrode for inducing charge in accordance with the surface potential of the opposing cell, and a leg portion for maintaining a spacing between the detection electrode and the cell. It is characterized by that.

The fourth invention is characterized in that the reference potential portion connected to the surface potential sensor is grounded.
The cell surface potential measured in the present invention includes that measured through glass or a back sheet provided on the cell surface.

According to the first invention, it is possible to confirm whether or not the power generation state between these cells is normal by measuring the surface potential difference between the pair of cells connected in series without contact. In addition, this method does not measure the output power of the cell, but measures the surface potential in a non-contact manner, so that it can be measured even during power transmission, and the power generation performance can be easily evaluated only by the magnitude of the potential difference.
If abnormal cells with low power generation capacity are included between the pair of cells, these cells cannot exhibit the desired power generation performance, so the potential difference between the cells should be smaller than the normal potential difference. It is. If the potential difference between the cells is measured using a non-contact type surface potential sensor, it can be determined from the value whether or not an abnormal cell is included, and as a result, a module comprising a cell group between the pair of cells. It will be possible to inspect the performance.

  In addition, in the present invention, the reference potential portions of the pair of surface potential sensors that measure the potential difference are shared. Therefore, each surface potential sensor measures a potential with respect to a common reference potential, and can accurately detect a potential difference that is a difference between them. For example, when the reference potential part is grounded for each surface potential sensor, the value of the surface potential measured by each surface potential sensor is measured unless the potentials of the reference parts of both surface potential sensors are true ground potentials. Includes an error, and the potential difference between the surface potentials detected by each surface potential sensor also includes an error.

However, according to the present invention, since the reference potentials of the pair of surface potential sensors are shared, when the surface potential sensors detect potentials with respect to the same reference potential and calculate the potential difference between them, the reference potentials described above are used. No matter how many are there, it is canceled and an accurate potential difference can be calculated.
In addition, during the measurement of the potential difference, the reference potential of each surface potential sensor is set to the same ground potential, so there is no need to search for and connect to the ground potential each time. Go up.

According to the second invention, the potential difference between a specific pair of cells among the cells connected in series can be measured accurately and with good workability. Then, the power generation performance of the cell and the performance of the power generation module can be inspected based on the measured potential difference.
In particular, in the present invention, since the reference potential part of the surface potential sensor connected to the calculation unit is connected and shared, the potential difference calculated by the calculation unit does not include the influence of the reference potential error or fluctuation. Therefore, an accurate measurement value can be obtained.
Further, it is not necessary to accurately maintain the reference potential portion at the ground potential at the time of measurement, and the inspection workability is improved.
Furthermore, when three or more surface potential sensors are connected to the calculation unit, a plurality of potential differences between cells can be measured simultaneously with a plurality of pairs of a plurality of sets of surface potential sensors. In this case, since multiple potential differences can be measured simultaneously, the environmental conditions such as sunlight and temperature are constant when measuring these potential differences, and the measured potential differences can be compared without worrying about the effects of the environmental conditions. it can.

According to the third invention, the distance between the surface of the cell to be measured and the detection electrode can be kept constant, and more accurate surface potential measurement can be performed. If the facing distance between the detection electrode and the cell changes, the amount of charge induced in the detection electrode by the charged cell changes, but the distance between the detection electrode and the cell surface is determined by the legs of the present invention. Can be held. Therefore, the surface potential can be measured under certain conditions, and variations in measured values can be eliminated. Further, it is not necessary for the measurer to hold the detection electrode by hand during the measurement, and the workability of the measurement is improved.
In addition, since the distance between the detection electrodes of the pair of surface potential sensors and the cell surface to be measured can be kept equal, the detection conditions of the pair of surface potential sensors can be made the same and measured by these surface potential sensors. The accuracy of the potential difference is also increased.

According to the fourth aspect of the invention, it is possible to prevent the measurer from receiving electric shock due to the charge induced in the detection device by the surface potential of the cell.
In this case as well, since the reference potential parts of all the surface potential sensors are connected and shared, all the surface potential sensors detect the surface potential value based on the common ground potential. As in the case of the present invention, an accurate potential difference measurement is possible.

It is a block diagram of the solar energy power generation system of 1st Embodiment. It is a top view of the power generation module of a 1st embodiment. It is a block diagram of the inspection apparatus of a 1st embodiment. It is an equivalent circuit diagram of the inspection apparatus of the first embodiment. It is an equivalent circuit schematic of the inspection apparatus of 2nd Embodiment. It is a block diagram of the inspection apparatus of 3rd Embodiment.

1 to 4 show a first embodiment of the present invention.
In the first embodiment, the power generation modules M1, M2,... Used in the photovoltaic power generation system shown in FIG. 1 are inspected using the inspection devices shown in FIGS.
In the above photovoltaic power generation system, a plurality of modules M1, M2,... Are connected in series to form one string B1, B2,. Is connected to the connection box A. And the electric power generated by all the modules M1, M2,... Connected in series to the connection box A is sent from the connection box A to the power transmission destination.
In the following description, the modules M1, M2,... And the strings B1, B2,. Let's use B.

As shown in FIG. 1, the string B is configured by connecting a plurality of modules M in series, and each module M is configured by connecting a plurality of power generation cells c1 to c18 in series as shown in FIG. Has been. The connection order of these cells c1 to c18 is in numerical order, and the connection state is shown by thin lines in FIG.
In addition, connection terminals p1 and p2 for connecting to other adjacent modules M are provided at both ends of the cells c1 to c18 connected in series, and the adjacent modules M are connected via the connection terminals p1 and p2. They are connected to each other.
The cells c1 to c18 all have the same power generation performance in the initial state, and the power generation amount in all the modules M and the power generation amount in the string B units are substantially equal.

In the solar power generation system configured as described above, when light is applied to the surface of each module M, each cell generates power, and each cell has a potential corresponding to the generated voltage.
However, since the cells c1 to c18 are all connected in series in one string B, the potential of each cell increases in the order of connection.
For example, in the first string B1, the potential increases sequentially from the cell c1 to the cell c18 of the module M1, and the potential of the cell c1 of the module M2 connected downstream is higher than the cell c18 of the module M1. . The potential of the most downstream cell c18 of the most downstream module M3 is the highest.
Here, upstream and downstream are based on the connection order of cells connected in series, and the connection box A is the most downstream.

  As described above, the potentials of the cells c1 to c18 vary depending on the connection position. However, as described above, since all the cells c1 to c18 have the same power generation performance, each cell generates power. The power generation amount is equal, and the potential difference between a pair of cells having the same number of cells included in the connection path should be constant. For example, the potentials of the cells of the modules M1, M2, and M3 are all different, but the potential difference between the cells c1 and c18 of the module M1 and the potential difference between the cells c1 and c18 of the module M2 are both 18 If all the cells c1 to c18 are functioning normally with a potential difference according to the amount of power generated by the cells c1 to c18, the potential difference becomes a constant value and should be equal.

Accordingly, as described above, if a pair of cells are specified from a group of cells connected in series and the potential difference between them is measured, the function of the cells between them can be inspected.
Note that the inventors of the present invention have already confirmed that the potential of each of the cells c1 to c18 can be measured as a surface potential by another experiment.

Next, in the system of FIG. 1, the inspection apparatus of the present invention shown in FIGS. 3 and 4 will be described by taking as an example the measurement of the potential difference between the cells c1 and c18 in the module M1.
In the inspection apparatus shown in FIG. 3, a pair of direct current amplification type surface potential sensors S <b> 1 and S <b> 2 are connected to the apparatus body 1.
The apparatus main body 1 includes a calculation unit 2 that calculates a potential difference between a pair of cells according to the detection values input from the surface potential sensors S1 and S2, and a display unit 3 that displays the calculation result. Yes.

The surface potential sensors S1 and S2 are sensors for detecting the surface potential of the opposite charged object, and both the surface potential sensors S1 and S2 have the same configuration. The principle of detecting these surface potentials is the same as that of a general surface potential measuring device.
That is, each of the DC amplification type surface potential sensors S1 and S2 has the detection electrodes 4 and 5 in which charges are induced by the electric field formed by the opposite charged objects, and the amount of charges induced in the detection electrodes 4 and 5. Detection circuits 6 and 7 for detection are provided.
Then, a potential value or the like corresponding to the amount of charge detected by the detection circuits 6 and 7 is input to the calculation unit 2 of the apparatus main body 1, and each surface potential sensor S1, S1 is calculated based on the input value. The surface potential difference of the object facing S2 is calculated.

As shown in FIG. 4, the detection circuits 6 and 7 include a capacitor C for accumulating induced charges induced in the detection electrodes 4 and 5, and detect potential differences V1 and V2 between the opposing electrodes of the capacitor C. I am trying to output.
The potential differences V1 and V2 are potential differences with respect to the reference electrodes 8 and 9, respectively, in the capacitor C with respect to the reference electrodes 8 and 9 on the opposite side of the detection electrode 4. That is, the reference electrode 8 is a reference potential portion of one surface potential sensor S1, and the reference electrode 9 is a reference potential portion of the other surface potential sensor S2. These reference electrodes 8 and 9 are connected to each other by a conducting wire 10 so as to have the same potential.

In addition, the said conducting wire 10 can be provided in the apparatus main body 1 by guide | inducing the conducting wire connected to each reference electrode 8 and 9 in the apparatus main body 1. FIG.
Further, a ground terminal (not shown) is connected to the conductive wire 10, and the ground terminal is connected to a ground terminal outside the apparatus body 1. Accordingly, the surface potential sensors S1 and S2 detect the surface potentials V1 and V2 of the charged objects facing the detection electrodes 4 and 5, using the common ground potential as a reference potential.

Further, the casing of each of the surface potential sensors S1 and S2 includes a leg portion 11 (see FIG. 3), and when measuring the potential difference, the leg portion 11 is installed on the module surface 12, and the module surface 12 and the detection electrode 4 are disposed. , 5 is kept at a predetermined value.
Then, the surface potential can be measured under the same conditions by making the distance from the module surface 12 to one detection electrode 4 equal to the distance from the module surface 12 to the other detection electrode 5. I am doing so.

A method for inspecting, for example, the cell of the module M1 of the string B1 during transmission of generated power using the inspection apparatus described above will be described.
First, one surface potential sensor S1 is provided on the surface of the module M1 so that the detection electrode 4 faces the cell c1, and the other surface potential sensor S2 is provided on the surface of the module M1, and the detection electrode 5 is provided so as to face the cell c18 (see FIGS. 3 and 4).

Thus, if a pair of surface potential sensors S1 and S2 are installed on each module M1, the apparatus main body 1 is operated.
Then, the detection circuits 6 and 7 are operated, and potentials V1 and V2 corresponding to the induced charges induced in the detection electrodes 4 and 5 are input to the calculation unit 2. In the calculation unit 2 to which the potentials V1 and V2 are input, the potential difference ΔV = V1−V2 is calculated based on these and displayed on the display unit 3.

This potential difference ΔV is a potential difference between the most upstream cell c1 of the module M1 and the most downstream cell c18 of the module M1. This potential difference ΔV corresponds to the power generated by all the cells c1 to c18 of the module M1, which is a cell group between the cell c1 and the cell c18. For example, if any cell in the module M1 fails, the amount of power generation is reduced by the amount of the failed cell and the potential is lowered, so the potential difference ΔV becomes smaller than the intended potential difference. .
Therefore, the measurer can determine whether or not the power generation function of the module M1 is normal based on the value of the potential difference ΔV displayed on the display unit 3.
As for the other module M, the performance can be judged by measuring the potential difference between the pair of cells c1 and c18 in the module M in the same manner as described above.

Further, in the first embodiment, the reference potential portion of the pair of surface potential sensors S1, S2 is shared by the conducting wire 10, so that the calculation unit 2 can have any value of the potential of the reference potential portion. It is possible to accurately detect the potential difference ΔV calculated in step 1, that is, the potential difference between the pair of cells c1 and c18.
This is because the surface potential detected by each of the surface potential sensors S1 and S2 is a potential difference from the reference potential which is the potential of the conductor 10. However, if the reference potential is common, the potential difference is not related to the value. This is because the reference potential is canceled when calculating ΔV.

If the reference potentials of the surface potential sensors S1 and S2 are separately grounded, the detected surface potential values include errors unless they are set to strict ground potentials. The measurement accuracy of the potential difference ΔV between the pair of cells calculated based on the above also falls. However, according to the first embodiment, since the reference potentials of both the surface potential sensors S1 and S2 are common, the potential difference ΔV is accurately determined even if the lead wire 10 is grounded or floating without being grounded. It can be measured.
As described above, in the first embodiment, by using the non-contact type surface potential sensors S1 and S2, the power generation module M can be accurately inspected without stopping power transmission.

Moreover, since each surface potential sensor S1, S2 is provided with the said leg part 11, the distance of the detection electrodes 4 and 5 of both sensors and the module surface 12 can be kept equal. Therefore, both sensors S1 and S2 can detect the surface potential under the same conditions, and a more accurate inspection is possible.
Note that the potential difference therebetween varies depending on the number of cells connected between the pair of cells to be measured, but any number of cells between the pair of cells for measuring the potential difference may be used. In any case, the quality of the cell between the pair of cells can be determined by comparing the measured potential difference ΔV with the standard potential difference. The standard potential difference is a value of a potential difference during power generation of a normal cell.

However, even if the standard potential difference is not known, if the number of cells between a pair of cells that measure the surface potential is the same, and the potential difference is measured at multiple locations, the measured values are compared and You can also find For example, the measured values of the potential difference between the cells c1, c18 of the modules M1, M2, M3,... Can be compared, and the module M lower than the potential difference of the other modules M can be determined as an abnormal module.
Further, the boundary of the module M may be included between a pair of cells to be measured. For example, the cell c1 of the module M1 and the cell c1 of the module M2 can be measured, and the performance of the module M1 including the cell group between them can be determined. Furthermore, if the cell c1 of the module M1 and the cell c18 of the module M3 are measured, the potential difference of the entire string B1 can be measured, and the performance in units of strings can be determined.

On the other hand, if the number of cells between a pair of cells to be measured is reduced, abnormal cells can be pinpointed.
However, if a faulty or deteriorated abnormal cell is found, if it is not replaced in units of cells, it is reasonable to use a replaceable unit, for example, a module M unit as an inspection unit. First, the potential difference is measured in units of the string B, and when the abnormal string B is specified, the number of cells between the pair of cells for measuring the potential difference is gradually reduced for the module M in the string B. If the measurement is performed, the abnormal module M and the abnormal cell can be efficiently identified with a small number of measurements.

In the first embodiment, the reference potential portion shared by the conductive wire 10 is set to the ground potential. However, the reference potential portion may not be set to the ground potential. However, if the reference potential portion is grounded, the measurer will not be shocked by the charge leaked from the conducting wire 10. Further, if the casing of the apparatus main body 1 is connected to the reference potential portion and simultaneously set to the ground potential, electric shock can be prevented more reliably.
The surface potential sensors S1 and S2 may be any sensor as long as the surface potential of the charged object can be detected without contact.

The second embodiment shown in FIG. 5 is an inspection apparatus using AC amplification type surface potential sensors S1 and S2 provided with detection circuits 13 and.
The detection circuits 13 and 14 are circuits for detecting displacement current values I1 and I2 flowing through a resistor R connected to the detection electrodes 4 and 5, respectively. Specifically, a chopper or rotating sector (not shown) is provided between the detection electrodes 4 and 5 and the cell to be measured, and the chopper or rotating sector is continuously displaced so that the detection electrodes 4 and 5 Change the induced charge. Then, the displacement current value flowing through the resistor R is detected according to the change and input to the calculation unit 2.
The calculation unit 2 calculates the potential of the detection electrodes 4 and 5 based on the input current values I1 and I2, and calculates a potential difference ΔV that is the difference between them.

As described above, in the second embodiment, the detection circuits 13 and 14 of the AC amplification type surface potential sensors S1 and S2 are different from the detection circuits 6 and 7 of the first embodiment, but other configurations are the first embodiment. Is the same.
That is, also in the second embodiment, the reference potential portion serving as the reference of the potential of the detection electrodes 4 and 5, that is, the side opposite to the detection electrodes 4 and 5 in the resistor R is connected by the conductive wire 15. Common potential is used.

Therefore, also in the second embodiment, when the calculation unit 2 calculates the potential difference ΔV, the error of the reference potential can be canceled and the potential difference can be accurately measured. Since the performance of the module M can be determined from this potential difference, an accurate inspection can be performed without stopping power transmission in a power generation system including a plurality of modules M.
The second embodiment is also the same as the first embodiment in that electric shock can be prevented by grounding the conducting wire 15 and setting the reference potential to the ground potential.

In the first and second embodiments, the pair of surface potential sensors S1 and S2 are connected to the calculation unit 2 of the apparatus body 1. However, only one pair of surface potential sensors are connected to the calculation unit 2. Any number of pairs is acceptable. And like the said embodiment, the reference potential of all the surface potential sensors connected to the said calculating part 2 needs to be shared.
If three or more surface potential sensors are connected to the computing unit 2 to the computing unit 2, three or more surface potentials can be measured simultaneously. From these detected values, the computing unit 2 calculates the potential difference between a pair of cells. Two or more can be calculated.

For example, in the third embodiment shown in FIG. 6, three surface potential sensors S <b> 1, S <b> 2 and S <b> 3 are connected to the calculation unit 2. In the third embodiment, the surface potentials V1, V2, and V3 of the three cells can be simultaneously detected by these surface potential sensors S1, S2, and S3. Then, the calculation unit 2 can calculate the potential difference ΔV1 = V1−V2, the potential difference ΔV2 = V2−V3, and the potential difference ΔV3 = V1−V3 from these potential values V1, V2, and V3. Thus, if three or more surface potential sensors are provided, a plurality of potential differences ΔV between a pair of cells can be measured simultaneously. The state of the power generation module M or the cell can be grasped from the measured potential difference.
In addition, this 3rd Embodiment is the same structure as the said 1st Embodiment except the number of the surface potential sensors connected to the calculating part 2. FIG. However, the surface potential sensors S1, S2, and S3 are not limited to the direct current amplification type, and any one such as an alternating current amplification type surface potential sensor as in the second embodiment may be used.

In particular, if measurement is performed with the same number of cells between the surface potential sensors S1 and S2 and between S2 and S3, the power generation capacity can be determined by comparing the potential differences ΔV1 and ΔV2.
For example, as shown in FIG. 6, when the surface potential sensors S1, S2, and S3 are opposed to the cells c1, c1, and c1 of the modules M1, M2, and M3, respectively, and the surface potential is measured, the potential difference is obtained. The performance of the module M1 can be grasped by ΔV1, and the performance of the module M2 can be grasped by ΔV2. If there is a difference between the two potential differences ΔV1 and ΔV2, it can be determined that there is a high possibility that an abnormal cell is included in the module having the smaller potential difference.

Moreover, since the plurality of potential differences ΔV1 and ΔV2 are values measured at the same time, environmental conditions such as sunlight and temperature at the time of measurement are equal, and comparison can be made without considering the influence of the environmental conditions.
In addition, when measuring a plurality of potential differences with three or more surface potential sensors, the calculation unit 2 may set in advance in the calculation unit 2 which surface sensor should calculate the potential difference. It may be set each time. The calculation unit 2 distinguishes which surface potential sensor is used for the calculated calculation result and displays the result on the display unit 3.
Further, even when the number of surface potential sensors increases, more accurate measurement can be performed by keeping the distances of all the surface potential sensors equal to the module surface.

  The present invention is particularly useful when testing the performance of a photovoltaic power generation system to which a large number of power generation modules are connected.

DESCRIPTION OF SYMBOLS 1 (Inspection apparatus) apparatus main body 2 calculating part 3 display part 4,5 detection electrode 6,7 detection circuit 8 reference electrode 9 reference electrode 10 (reference potential part) conducting wire 11 leg 12 module surface 13, 14 detection circuit 15 ( Reference potential portion) Conductive wires S1, S2, S3 Surface potential sensors c1, c2,... Cell M (for power generation) module

Claims (4)

A method for inspecting a photovoltaic power generation module in which a plurality of cells are electrically connected in series,
Identify a pair of cells from the series connected cells,
A method for inspecting a photovoltaic power generation module, wherein the surface potential difference of a specified cell is measured by a pair of non-contact type surface potential sensors having a common reference potential, and the performance of the photovoltaic power generation module is evaluated according to the potential difference. An inspection device for a photovoltaic module in which a plurality of cells are electrically connected in series,
At least a pair of surface potential sensors that detect the surface potential of the cells connected in series in a non-contact manner;
The surface potential sensor is connected, and based on the detection value of each surface potential sensor, the potential difference between the pair of cells is calculated and a calculation unit that outputs the calculation result,
The surface potential sensor connected to the calculation unit is a solar power generation module inspection apparatus to which a reference potential unit is connected and the reference potential is shared.   The said surface potential sensor is provided with the detection electrode by which an electric charge is induced | guided | derived according to the surface potential of the opposing cell, and the leg part for maintaining the opposing space | interval of this detection electrode and the said cell. Solar photovoltaic module inspection equipment.   The said surface potential sensor is a test | inspection apparatus of the solar power generation module of any one of Claims 1-3 by which the said reference potential part connected was earth | grounded.

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