JP2021145494A - Diagnostic device, diagnostic method, and program - Google Patents

Abstract

To make it possible to simply determine poor connection of wiring for connection between solar cell modules to improve construction quality in a photovoltaic power generation system.SOLUTION: A diagnostic device for performing diagnosis on a power generation state of a solar cell comprises a control unit for executing the steps of: acquiring a current voltage characteristic of the solar cell that is measured with a predetermined number of samples and on changes in a current value shifting due to increase or decrease in a voltage value; on the basis of a first characteristic value of one of a voltage value and a current value for each of sample points at which the current voltage characteristic is measured and a second characteristic value of the other, calculating a tilt of change in the second characteristic value shifting due to increase or decrease in the first characteristic value at the sample point; and performing a diagnosis on whether a power generation state of the solar cell is a normal state or an abnormal state on the basis of a determination result of magnitude comparison between an estimation second characteristic value estimated from a tilt of change with respect to a predetermined first characteristic value and a second characteristic value measured in the current voltage characteristic correspondingly to the predetermined first characteristic value.SELECTED DRAWING: Figure 7

Description

The present invention relates to a diagnostic device, a diagnostic method and a program capable of diagnosing the construction state of a photovoltaic power generation system using a solar cell.

In a photovoltaic power generation system using a solar cell that directly generates electricity using sunlight as an energy source, the current-voltage characteristic (also referred to as "IV characteristic") of the solar cell or the voltage generation power (PV characteristic). It is known that the operating state of the solar cell provided on a gantry, a rooftop, or the like is grasped based on the measurement result. For example, Patent Document 1 discloses a technique for simply acquiring a current-voltage characteristic that serves as a reference for determining an abnormality in a solar cell and determining an abnormality in the solar cell. The IV characteristics and PV characteristics of a solar cell are generally measured using an IV curve tracer.

Here, in the solar power generation system, the construction is carried out with a solar cell module as a constituent unit, which is modularized by arranging a plurality of power generation units called cells in series and parallel. In the construction of a photovoltaic power generation system, a string having a configuration in which a plurality of solar cell modules are connected in series, and a solar cell array (or simply "array") in which the strings are further connected in parallel are adopted. .. Then, a plurality of solar cell arrays are provided on a gantry, a rooftop, or the like according to the scale of the generated power.

Japanese Unexamined Patent Publication No. 2012-186409

As described above, the photovoltaic power generation system includes a plurality of solar cell modules. Therefore, the number of wires connected between the solar cell modules increases in proportion to the scale of the generated power. At the construction site of the photovoltaic power generation system, the normality / non-normality of the wiring state between the solar cell modules is judged by looking at the graph shape of the IV characteristic and the PV characteristic measured by the curve tracer. However, in order to judge the normality / non-normality of the wiring state between the positive battery modules from the above graph shape, it depends on the knowledge and experience of the operator, and the judgment quality varies. If a construction defect (forgetting wiring, connection error, etc.) occurs in the connection wiring between the solar cell modules, the amount of power generated will decrease, and the amount of power generated at the time of design cannot be obtained. Further, when a plurality of solar cell arrays are provided, the voltage balance between the arrays is lost, which may cause a failure of the solar cell modules constituting each array.

By the way, in the technique disclosed in Patent Document 1, the reference IV curve characteristic that serves as a reference for abnormality judgment is obtained from the rating of the solar cell module, and the difference between the area of the reference IV curve and the measured area of the measured IV curve is used. , Normal and abnormal are separated. Therefore, since each area is calculated and the reference IV curve is calculated, the processing cost related to the calculation is large. In addition, since the comparison is based on the area, if the area difference is small, it cannot be determined whether it is due to an environmental change such as a change in sunshine or a construction error.

The present invention has been made in view of the above problems, and an object of the present invention is to make it possible to easily identify a poor connection of wiring connecting solar cell modules and improve the construction quality in a photovoltaic power generation system. To provide technology.

The diagnostic device according to the present invention for solving the above problems is a diagnostic device for diagnosing whether the power generation state of a solar cell composed of a plurality of photovoltaic power generation modules is a normal state or an abnormal state. hand,
To acquire the current-voltage characteristics regarding the change in the current value that changes with the increase or decrease of the voltage value measured with a predetermined number of samples for the solar cell.
With the increase or decrease of the first characteristic value at the sample point, the current-voltage characteristic is based on one of the first characteristic values and the other second characteristic value of the voltage value or the current value for each measured sample point. To calculate the slope of the change in the second characteristic value that changes in
A magnitude comparison between the estimated second characteristic value estimated from the slope of the change with respect to the predetermined first characteristic value and the second characteristic value measured corresponding to the predetermined first characteristic value in the current-voltage characteristic. Based on the determination result, diagnosing whether the power generation state of the solar cell is in a normal state or an abnormal state, and
It is characterized by including a control unit that executes the above.

Here, when the "first characteristic value" is a voltage value, the "second characteristic value" is a current value, and when the "first characteristic value" is a current value, the "second characteristic value" is a voltage value. Is. As a result, when the first characteristic value is a voltage value from the short-circuit current (Isc) to the open circuit voltage (Voc), the change tendency of the current value that changes with the increase or decrease of the voltage value is shown IV. Curve In the shape of the curve, it is possible to determine the presence or absence of the step region g2c between the shoulder portion g2a and g2b where the decreasing tendency of the current value changes. When the wiring connecting the solar cell modules is poorly connected, the number of modules involved in power generation is different from the normal state, so that the difference in the number of modules occurs as a step region on the IV curve curve. According to the present invention, it is possible to diagnose the connection wiring state between the solar cell modules constituting the solar cell 30 after construction based on the presence or absence of the step region. Further, since the step region in the IV curve can be determined based on the slope Dp of the tangent line at each measurement point, it is not necessary to obtain the area of the measured IV curve and the area of the reference IV curve from the measured IV curve. In the present invention, the processing cost of the calculation related to the diagnosis can be reduced. According to the present invention, it is possible to determine the connection failure of the wiring connecting the solar cell modules based on the shape of the IV curve data, and the construction quality in the photovoltaic power generation system can be improved.

Further, in the present invention, the control unit uses the second characteristic value whose estimated second characteristic value is measured corresponding to the predetermined first characteristic value for each sample point where the current-voltage characteristic is measured. The number of sample points determined to be small may be counted, and when the ratio of the counted sample points to the total number of samples is equal to or less than the determination reference value, the power generation state of the solar cell may be diagnosed as a normal state. As a result, the influence of superimposed noise and the like during IV curve data measurement can be reduced. According to the present invention, it is possible to increase the accuracy of determining whether the connection wiring between the solar cell modules is normal or not.

Further, in the present invention, the control unit uses the second characteristic value whose estimated second characteristic value is measured corresponding to the predetermined first characteristic value for each sample point where the current-voltage characteristic is measured. The number of sample points determined to be small may be counted, and when the ratio of the counted sample points to the total number of samples exceeds the determination reference value, the power generation state of the solar cell may be diagnosed as an abnormal state. .. As a result, the influence of superimposed noise and the like during IV curve data measurement can be reduced. According to the present invention, it is possible to increase the accuracy of determining whether the connection wiring between the solar cell modules is normal or not.

Further, in the present invention, the control unit is based on the second characteristic value measured at the first sample point and the first characteristic value of the first sample point among the sample points at which the current-voltage characteristic is measured. The difference between the second characteristic value on the lower side and the second characteristic value on the lower side measured at the sample point adjacent to the lower side is less than the first threshold value, and the second characteristic value and the sample point adjacent to the higher side of the first sample point. When the difference from the second characteristic value on the higher side measured in 1 is less than the second threshold value, the first sample points may be thinned out. Here, the "low-order side" represents the low-voltage side when the first characteristic value is a voltage value, and represents the low-current side when the first characteristic value is a current value. The same applies to the "higher side".

As a result, it is possible to diagnose the normality / non-normality of the wiring state of the solar cells 30 constituting the photovoltaic power generation system 1 that connects the solar cell modules with each measurement point subjected to the thinning process as the processing target. According to the present invention, it is possible to reduce the detection of step error due to the influence of current measurement error and noise in the measured data related to the step determination, and it is possible to reduce the normal / non-normal construction state of the connection wiring between the solar cell modules. The normal judgment system can be enhanced.

Further, in the present invention, in the control unit, the estimated second characteristic value estimated from the slope of the change with respect to the predetermined first characteristic value in the sample points where the current-voltage characteristic is measured is the current-voltage characteristic. A group of consecutive sample points determined to be smaller than the second characteristic value measured corresponding to the predetermined first characteristic value in terms of characteristics is grouped, and a group of continuous sample points is grouped.
In the grouped sample point group, the difference second characteristic value, which is the difference between the lower second characteristic value measured at the lower sample point and the higher second characteristic value measured at the higher sample point, Based on the ratio of the first characteristic value to the reference second characteristic value at 0 value, it may be diagnosed whether the power generation state of the solar cell is a normal state or an abnormal state. Here, the "low-order side" represents the low-voltage side when the first characteristic value is a voltage value, and represents the low-current side when the first characteristic value is a current value. The same applies to the "higher side". Further, the "reference second characteristic value when the first characteristic value is 0" represents a "short circuit current value" when the first characteristic value is a voltage value, and "open circuit voltage" when the first characteristic value is a current value. Represents "value".

As a result, the current change width of the grouped measurement point group can be used as an evaluation target for determining the step, so that it is possible to reduce the error detection due to the influence of the size of the step. According to the present invention, it is possible to further improve the determination accuracy regarding the step determination, and the normal / abnormal diagnostic accuracy of the wiring state of the solar cells 30 constituting the photovoltaic power generation system 1 connecting between the solar cell modules. Can be increased.

Further, the present invention is a diagnostic method for diagnosing whether the power generation state of a solar cell composed of a plurality of photovoltaic power generation modules is a normal state or an abnormal state.
To acquire the current-voltage characteristics regarding the change in the current value that changes with the increase or decrease of the voltage value measured with a predetermined number of samples for the solar cell.
With the increase or decrease of the first characteristic value at the sample point, the current-voltage characteristic is based on one of the first characteristic values and the other second characteristic value of the voltage value or the current value for each measured sample point. To calculate the slope of the change in the second characteristic value that changes
A magnitude comparison between the estimated second characteristic value estimated from the slope of the change with respect to the predetermined first characteristic value and the second characteristic value measured corresponding to the predetermined first characteristic value in the current-voltage characteristic. Based on the determination result, diagnosing whether the power generation state of the solar cell is in a normal state or an abnormal state, and
It is characterized by including.

According to the present invention, when the first characteristic value is a voltage value from the short-circuit current (Isc) to the open circuit voltage (Voc), the change tendency of the current value that changes as the voltage value increases or decreases. In the shape of the IV curve curve showing the above, it is possible to determine the presence or absence of the step region g2c between the shoulder portions g2a and g2b where the decreasing tendency of the current value changes. If the wiring that connects the solar cell modules is poorly connected, the number of modules involved in power generation will differ from the normal state.
The difference in the number of modules will occur as a step region on the IV curve. This makes it possible to diagnose the connection wiring state between the solar cell modules constituting the solar cell 30 after construction based on the presence or absence of the stepped region. Further, since the step region in the IV curve can be determined based on the slope Dp of the tangent line at each measurement point, it is not necessary to obtain the area of the measured IV curve and the area of the reference IV curve from the measured IV curve. In the present invention, the processing cost of the calculation related to the diagnosis can be reduced. According to the present invention, it is possible to determine the connection failure of the wiring connecting the solar cell modules based on the shape of the IV curve data, and the construction quality in the photovoltaic power generation system can be improved.

Further, the present invention is a program to be executed by a computer for diagnosing whether the power generation state of a solar cell composed of a plurality of photovoltaic power generation modules is a normal state or an abnormal state.
To acquire the current-voltage characteristics regarding the change in the current value that changes with the increase or decrease of the voltage value measured with a predetermined number of samples for the solar cell.
With the increase or decrease of the first characteristic value at the sample point, the current-voltage characteristic is based on one of the first characteristic values and the other second characteristic value of the voltage value or the current value for each measured sample point. To calculate the slope of the change in the second characteristic value that changes
A magnitude comparison between the estimated second characteristic value estimated from the slope of the change with respect to the predetermined first characteristic value and the second characteristic value measured corresponding to the predetermined first characteristic value in the current-voltage characteristic. Based on the determination result, diagnosing whether the power generation state of the solar cell is in a normal state or an abnormal state, and
Is characterized by executing.

According to the program according to the present invention, when the first characteristic value is a voltage value, the current value changes as the voltage value increases or decreases from the short-circuit current (Isc) to the open circuit voltage (Voc). In the shape of the IV curve curve showing the change tendency of, it is possible to determine the presence or absence of the step region g2c between the shoulder portion g2a and g2b where the decrease tendency of the current value changes. When the wiring connecting the solar cell modules is poorly connected, the number of modules involved in power generation is different from the normal state, so that the difference in the number of modules occurs as a step region on the IV curve curve. This makes it possible to diagnose the connection wiring state between the solar cell modules constituting the solar cell 30 after construction based on the presence or absence of the step region. Further, since the step region in the IV curve can be determined based on the slope Dp of the tangent line at each measurement point, it is not necessary to obtain the area of the measured IV curve and the area of the reference IV curve from the measured IV curve. In the present invention, the processing cost of the calculation related to the diagnosis can be reduced. According to the program according to the present invention, it is possible to determine the connection failure of the wiring connecting the solar cell modules based on the shape of the IV curve data, and the construction quality in the photovoltaic power generation system can be improved.

According to the present invention, it is possible to determine the connection failure of the wiring connecting the solar cell modules, and it is possible to improve the construction quality in the photovoltaic power generation system.

It is a block diagram which shows the schematic structure of the solar power generation system which concerns on Example 1 of this invention. It is a figure explaining the relationship between the quantity of the solar cell module in Example 1 of this invention, and an IV curve. It is a figure explaining the relationship between the quantity of the solar cell module in Example 1 of this invention, and an IV curve. It is a figure explaining the change tendency of the IV curve in the abnormal state in Example 1 of this invention. It is a figure explaining the feature of the IV curve having a step region in Example 1 of this invention. It is a figure which shows an example of the hardware composition of the diagnostic apparatus in Example 1 of this invention. It is a block diagram which shows an example of the more detailed functional structure of the diagnostic apparatus in Example 1 of this invention. It is a figure which shows an example of various data in Example 1 of this invention. It is a figure explaining the process of obtaining the slope of a tangent line in Example 1 of this invention. It is a figure explaining the inside / outside determination of the tangent line with respect to the measurement point in Example 1 of this invention. It is a flowchart which shows an example of the diagnostic process in Example 1 of this invention. It is a block diagram which shows an example of the functional structure of the diagnostic apparatus which concerns on Example 2 of this invention. It is a figure which shows an example of the setting value for thinning in Example 2 of this invention. It is a figure explaining the thinning-out process in Example 2 of this invention. It is a flowchart which shows an example of the diagnostic process in Example 2 of this invention. It is a block diagram which shows an example of the functional structure of the diagnostic apparatus which concerns on Example 3 of this invention. It is a figure explaining the grouping process in Example 3 of this invention. It is a flowchart which shows an example of the diagnostic process in Example 3 of this invention.

[Application example]
Hereinafter, application examples of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a strategic configuration of a photovoltaic power generation system 1 that can cooperate with the diagnostic device 20 according to an application example of the present invention. FIG. 1 illustrates a solar cell 30, a commercial power system (also simply referred to as a system) 40, and a load 50 connected to a power conditioner (PCS) 10 constituting the photovoltaic power generation system 1. .. The diagnostic device 20 according to the application example of the present invention is connected to the power conditioner (PCS) 10 via a predetermined communication line.

As shown in FIG. 1, the solar cell 30 is constructed with the solar cell module 33, which is a module in which a plurality of cells 33a, which are power generation units, are series-paralleled and modularized, as a constituent unit. For example, the string 32 has a configuration in which one or more solar cell modules 33 are combined and connected in series via a bypass diode, and the solar cell array 31 has a configuration in which the strings 32 are combined and connected in parallel. .. The output current of each array constituting the solar cell 30 is input to the PCS 10 through the blocking diode 15. The PCS 10 is subjected to a power conversion unit 10a, which is a unit for converting DC power generated by the solar cell 30, into AC power, and an IV curve measurement process for measuring the IV characteristics of the solar cell 30. It is provided with a control unit 10b. The PCS 10 is provided with a current sensor 11 for detecting the total current input through each blocking diode and a voltage sensor 12 for detecting the voltage between the input terminals of the power conversion unit 10a. In the IV curve measurement process, the control unit 10b controls the power conversion unit 10a and responds to the input voltage (DCV) while changing the operating point voltage (input voltage (DCV) of the power conversion unit 10a). The input current (DCI) to be measured is measured. As a result of the measurement, a plurality of combinations of the input voltage value changed in a predetermined step unit and the input current value measured according to the input voltage value are acquired. The control unit 10b transmits the acquired measurement result to the diagnostic apparatus 20 as data indicating the IV characteristics of the solar cell 30.

As shown in FIGS. 2 to 5, when the state of the solar cell 30 is normal, the current value of the IV curve generally decreases gradually as the voltage increases, starting from the short-circuit current (Isc). Then, the generated output of the solar cell 30 changes to the maximum power point current (Impp) and the maximum power point voltage (Vmpp) of the maximum power point at which the maximum power is obtained. Then, after the maximum power point has passed, the current value of the IV curve changes relatively steeply as the voltage increases, and changes so as to reach the open circuit voltage (Voc). On the other hand, when the number of modules 33 constituting the array 31a of the solar cell 30 is different from the normal state (non-normal state), the gentle shape of the IV curve with the increase in voltage collapses, which is different from the normal state. The shape change caused by the decrease in the generated power of the number of modules will occur as a new shoulder portion on the IV curve.

The diagnostic device 20 according to the present application example determines the presence or absence of the step region g2c based on the data showing the IV characteristics of the solar cell measured via the PCS 10 after the construction of the solar cell 30. Specifically, as shown in FIG. 5, a tangent line is obtained for each measurement point, and an extension point in the inclination direction of the tangent line intersects with an IV curve that changes from a short-circuit current (Isc) to an open circuit voltage (Voc). Is determined. Then, the present diagnostic apparatus 20 diagnoses that the construction state of the wiring connecting the solar cell modules is an abnormal state when the step region g2c exists for the IV curve measured from the solar cell 30 after construction. do. As a result, based on the shape of the IV curve data, it becomes possible to determine the connection failure of the wiring connecting the solar cell modules, and the construction quality in the photovoltaic power generation system can be improved. Needless to say, even if the transition of the voltage value acquired as the data indicating the IV characteristic of the solar cell 30 is used, it can be evaluated in the same manner as the transition of the current value.

[Example 1]
Hereinafter, the diagnostic apparatus according to the embodiment of the present invention will be described in more detail with reference to the drawings.

<System configuration>
FIG. 1 is a block diagram showing a strategic configuration of a photovoltaic power generation system according to an embodiment of the present invention. The diagnostic device 20 in this embodiment is an information processing device that can be connected to the power conditioner (PCS) 10 constituting the photovoltaic power generation system 1 via a predetermined communication line. In the photovoltaic power generation system 1 according to the present embodiment, the power conditioner (hereinafter, also referred to as “PCS”) 10 is connected to the solar cell 30, the commercial power system (also simply referred to as a system) 40, and the load 50. It is a device to be used. The solar cell 30 is constructed with a solar cell module (hereinafter, also simply referred to as “module”) 33, which is a module in which cells 33a, which are power generation units, are series-paralleled in parallel, as a constituent unit. In the photovoltaic power generation system 1, a plurality of modules 33 are used in combination. As shown in FIG. 1, the string 32 has a configuration in which one or more solar cell modules 33 are combined and connected in series via a bypass diode, and the solar cell arrays 31a, 31b, 31c, and 31d are connected, respectively. It is a configuration in which strings 32 are combined and connected in parallel. In the solar cell 30 of FIG. 1, a solar cell array (hereinafter, also simply referred to as “array”) in which strings 32 in which three modules 33 are connected in series are further connected in parallel in three rows is arranged in four stages. Be prepared. In the following, the module configuration of the solar cell 30 shown in FIG. 1 will be adopted as an explanatory example, but the diagnosis target of the diagnostic apparatus 20 according to the present embodiment is not limited to the module configuration shown in FIG. For example, the one-stage array constituting the solar cell 30 may be nine modules 33 connected in series. The output current of each array constituting the solar cell 30 is input to the PCS 10 through the blocking diode 15.

The PCS 10 includes a power conversion unit 10a and a control unit 10b. The power conversion unit 10a is a unit for converting the DC power generated by the solar cell 30 into AC power, and is a DC / DC converter that boosts the DC power generated by the solar cell 30 and the boosted power. Is configured to include a DC / AC converter that converts AC power in synchronization with the commercial power system 40. As shown, the power converter 10a and the blocking diode 1 of each array
5 is connected so that the sum of the direct currents output through each blocking diode 15 is input to the power conversion unit 10a. Further, the PCS 10 is provided with a current sensor 11 for detecting the total current input through each blocking diode and a voltage sensor 12 for detecting the voltage between the input terminals of the power conversion unit 10a. The PCS 10 is also provided with sensors other than the current sensor 11 and the voltage sensor 12.

The control unit 10b is a unit including a processor (CPU, MPU, DSP, etc.), a gate driver, a communication interface circuit for communicating with the diagnostic device 20, and the like. The output of various sensors including the current sensor 11 and the voltage sensor 12 is input to the control unit 10b. In the control unit 10b, the power conversion unit 10a operates at the maximum power (current x voltage value) point or the optimum operating point at which the power output of the solar cell 30 is maximized, based on the information detected through various sensors. Maximum power point tracking (MPPT) is performed. Further, in this embodiment, the IV curve measurement process for measuring the IV characteristics of the solar cell 30 is performed through the control unit 10b.

In the IV curve measurement process, the control unit 10b controls the power conversion unit 10a and responds to the input voltage (DCV) while changing the operating point voltage (input voltage (DCV) of the power conversion unit 10a). The input current (DCI) to be measured is measured. As a result of the measurement, a plurality of combinations of the input voltage value changed in a predetermined step unit and the input current value measured according to the input voltage value are acquired. The control unit 10b transmits the acquired measurement result to the diagnostic apparatus 20 as data indicating the IV characteristics of the solar cell 30.

The diagnostic device 20 according to the present embodiment is an information processing device having a function of diagnosing the normal / abnormal state of the connection wiring between the modules constituting the solar cell with respect to the solar cell 30 included in the photovoltaic power generation system 1. .. In this diagnostic apparatus, it is diagnosed whether the connection state of the wiring connecting the modules is a normal state or an abnormal state based on the data indicating the IV characteristic measured through the control unit 10b. ..

2 and 3 are diagrams for explaining the relationship between the quantity of the solar cell modules 33 and the IV curve. 2 and 3 are based on IV characteristic data measured with different numbers of modules related to power generation in the solar cell 30 composed of the four-stage arrays 31a, 31b, 31c, and 31d shown in FIG. A curve graph (IV curve) is illustrated. In the following, the configuration form of n modules 33 connected in series is also referred to as "n straight", and the configuration form of m modules 33 connected in parallel in the same manner is also referred to as "m average". For example, the configuration of the module 33 of the array 31a shown in FIG. 1 is represented as "3 straight 3 average". In the IV curves illustrated in FIGS. 2 and 3, the vertical axis represents the normalized current value and the horizontal axis represents the normalized voltage value. Further, in FIGS. 2 and 3, the intersection of the IV curve and the vertical axis represents the short-circuit current (Isc) of the solar cell 30, and the intersection of the IV curve and the horizontal axis represents the open circuit voltage (Voc). ..

In FIG. 2, (a) exemplifies the IV curve measured when the configuration form of the module 33 constituting the array 31a is changed from 3 straight 3 rows to 1 straight 3 rows. Similarly, (b) shows the IV curve when the configuration of the module 33 of the array 31a is changed from 3 straight 3 to 1 straight 3, and (c) shows the module 33 of the array 31a. An example is an IV curve when the configuration form is changed from 3 straight 3 average to "3 straight 2 average + 1 straight 1 average". Further, FIG. 3 (a) shows an IV curve measured when the configuration form of the module 33 constituting the array 31a is changed from 3 straight 3 rows to 2 straight 3 rows, as shown in FIG. 3 (b). Is an example of an IV curve when the configuration form of the module 33 of the array 31a is changed from 3 straight 3 average to "3 straight 1 average + 2 linear 1 average + 1 linear 1 average". FIG. 3C exemplifies an IV curve when the configuration of the module 33 of the array 31a is changed from 3 straight 3 average to “3 straight 1 average + 1 linear 2 average”.

In the photovoltaic power generation system 1, when the state of the solar cell 30 is normal, the shape of the IV curve is generally smooth. That is, in the IV curve, starting from the short-circuit current (Isc), the current value gradually decreases as the voltage increases, and the maximum power point current of the maximum power point at which the power output of the solar cell 30 becomes the maximum power. (Impp) and the maximum power point voltage (Vmpp) change. Then, after the maximum power point has passed, the current value of the IV curve changes relatively steeply as the voltage increases, and changes so as to reach the open circuit voltage (Voc). On the IV curve, the portion where the decreasing tendency of the current value changes relatively sharply with the increase in voltage is also called the "shoulder portion", and the IV curve in the normal state has one shoulder portion. You can also do it.

On the other hand, as shown in FIGS. 2 and 3, when the number of modules 33 constituting the array 31a of the solar cell 30 is different from the normal state (non-normal state), the IV curve accompanying the voltage increase The gentle shape will collapse. Specifically, the shape change caused by the decrease in the generated power of the number of modules different from the normal state will occur as a new shoulder portion on the IV curve. For example, in the IV curve in the normal state, the decreasing tendency of the current value accompanying the voltage increase after the shoulder portion changes from a gradual decreasing tendency to a relatively steep decreasing tendency, and reaches the release voltage (Voc). .. On the other hand, in the IV curve in the abnormal state, the decreasing tendency of the current value due to the voltage increase changes from "gentle" to "steep" for each shoulder portion.

FIG. 4 is a diagram for explaining the change tendency of the IV curve in the abnormal state. In FIG. 4, the graph g1 shown by the alternate long and short dash line represents the transitional change of the IV curve in the normal state, and the graph g2 shown by the solid line represents the transitional change of the IV curve in the abnormal state. The vertical axis represents the current (A), and the horizontal axis represents the voltage (V). The intersection of the IV curve and the vertical axis represents the short-circuit current (Isc) of the solar cell 30, and the intersection of the IV curve and the horizontal axis represents the open circuit voltage (Voc).

In the graph g1 of FIG. 4, the shoulder portion g1a, which is a region in which the decreasing tendency of the current value changes with the increase in voltage, is exemplified. Then, in the IV curve (graph g2) in the abnormal state, the shoulder portion where the decreasing tendency of the current value changes as the voltage increases is the low voltage side region (shoulder portion g2a) and the high voltage side region (shoulder). It will occur in two places in the part g2b). As described above, the transition region g2c between the shoulder portions g2a and g2b that occurs in the IV curve in the abnormal state is referred to as “step region g2c” in the present embodiment. In the step region g2c, the decreasing tendency of the current value due to the increase in voltage once suddenly changes, and then shifts to a gradual decreasing tendency again. Then, the decreasing tendency changes to a steep decreasing tendency again after passing the shoulder portion g2b, and reaches the release voltage (Voc).

As described with reference to FIGS. 2 and 3, when the number of connections of the modules 33 constituting the solar cell 30 after construction is different from the normal state, a step region g2c is surely generated in the transition curve of the IV curve. become. Therefore, by determining the presence or absence of the step region g2c based on the data indicating the IV characteristic measured after the construction of the solar cell 30, it is possible to determine the connection failure of the wiring connecting the solar cell modules.

FIG. 5 is a diagram for explaining the characteristics of the IV curve having a stepped region. As shown in FIG. 5A, the shape of the IV curve when the solar cell 30 is in the normal state changes from the short-circuit current (Isc) to the open circuit voltage (Voc) with the maximum power point as the inflection point. It is a convex curve. Therefore, in the entire section where the IV characteristic data is measured, the tangent line obtained for each measurement point may intersect the IV curve that changes from the short-circuit current (Isc) to the open circuit voltage (Voc). No. On the other hand, as shown in FIG. 5B, when the step region g2c exists, a part of the tangent line obtained for each measurement point in the transition region between the shoulder portion g2a and g2b is a short-circuit current (Isc). ) To the open circuit voltage (Voc).

The diagnostic device 20 according to the present embodiment determines the presence or absence of the step region g2c based on the data indicating the IV characteristics of the solar cell measured via the PCS 10 after the construction of the solar cell 30. Specifically, as described in FIG. 5, a tangent line is obtained for each measurement point, and an IV curve in which an extension point existing in the inclination direction of the tangent line changes from a short-circuit current (Isc) to an open circuit voltage (Voc). Determine if it intersects with. Then, the present diagnostic apparatus 20 diagnoses that the construction state of the wiring connecting the solar cell modules is an abnormal state when the step region g2c exists for the IV curve measured from the solar cell 30 after construction. do.

<Device configuration>
FIG. 6 is a diagram showing an example of the hardware configuration of the diagnostic device 20. As shown in FIG. 6, the diagnostic device 20 is a computer including a processor 21, a main storage device 22, an auxiliary storage device 23, a communication IF 24, and an input / output IF 25 connected to each other by a connection bus 26 as components. The main storage device 22 and the auxiliary storage device 23 are recording media that can be read by the diagnostic device 20. Each of the above components may be provided in a plurality of components, or some components may not be provided.

The processor 21 is a central processing unit that controls the entire diagnostic device 20. The processor 21 is, for example, a CPU (Central Processing Unit), an MPU (Micro-Processing Unit), a DSP (Digital Signal Processor), or the like. The processor 21, for example, deploys a program stored in the auxiliary storage device 23 executably in the work area of the main storage device 22, and controls peripheral devices through the execution of the program to achieve a function that meets a predetermined purpose. I will provide a. However, some or all the functions provided by the processor 21 may be provided by an ASIC (Application Specific Integrated Circuit), a GPU (Graphics Processing Unit), or the like. Similarly, some or all of the functions are realized by a dedicated LSI (large scale integration) such as FPGA (Field-Programmable Gate Array), numerical arithmetic processor, vector processor, image processor, and other hardware circuits. May be good. In this embodiment, the processor 21 of the diagnostic device 20 is an example of a "control unit".

The main storage device 22 stores a program executed by the processor 21, data processed by the processor, and the like. The main storage device 22 includes a flash memory, a RAM (Random Access Memory), and a ROM (Read Only Memory). The auxiliary storage device 23 is a storage medium that stores programs executed by the processor 21 and the like, operation setting information, and the like. The auxiliary storage device 23 includes, for example, an HDD (Hard-disk Drive), an SSD (Solid State Drive), an EPROM (Erasable Programmable ROM), a flash memory, a USB memory, an SD (Secure Digital) memory card, and the like. The communication IF 24 is a communication interface for connecting the diagnostic device 20 and another device such as the PCS 10. The communication IF 24 can adopt an appropriate configuration according to the connection method with other devices. The input / output IF25 is an interface for inputting / outputting data to / from an input device and an output device connected to the diagnostic device 20. Through the input / output IF25, the diagnosis result is output to a display device such as an LCD of the diagnostic device 20 or an output device such as a printer connected to the diagnostic device 20. The diagnosis result regarding the normal / abnormal state of the solar cell 30 may be notified to other devices (smartphone, data server, PCS, etc.) connected through the communication IF 24.

<Functional configuration>
FIG. 7 is a block diagram showing an example of a more detailed functional configuration of the diagnostic apparatus 20 according to the present embodiment. The diagnostic device 20 according to the present embodiment has the IV curve data reading unit 110, the step detection set value holding unit 120, the determination standard holding unit 130, and the intersection presence / absence determination unit 1 as functional elements.
40, a step determination unit 150, a determination result display unit 160, and a determination result transmission unit 170 are provided. The diagnostic device 20 obtains the intersection of the IV curve and the tangent line at each measurement point by providing the above functional elements through the execution of the software program stored in the auxiliary storage device 23 or the like by the processor 21, and obtains the step area. The presence or absence of g2c is determined.

First, the IV curve data reading unit 110 acquires data (IV curve data) indicating the IV characteristics of the solar cell 30 provided at a predetermined location (such as a gantry or rooftop) from the PCS 10 connected through the communication IF 24. do. The acquired IV curve data is stored in a predetermined area of the auxiliary storage device 23 in association with, for example, date and time information, an identification number for identifying the PCS 10. FIG. 8A is a diagram showing an example of IV curve data of the solar cell 30 acquired by the PCS 10. In FIG. 8A, table-type IV curve data acquired by changing the operating point voltage in the operating region from the open circuit voltage (Voc) to the short circuit current (Isc) is illustrated. As shown in FIG. 8A, the IV curve data includes a sampling number (j) for changing the operating point voltage, a voltage value (voltage (V_j) [V]) associated with the number, and a current value ( It is composed of an electric current (I_j [A]).

Next, in the intersection presence / absence determination unit 140, the slope of the tangent line at each measurement point of the IV curve data acquired from the PCS 10 is obtained. FIG. 9 is a diagram illustrating a process of obtaining the inclination of the tangent line provided by the intersection presence / absence determination unit 140. In the present embodiment, the slope of the tangent line is the current difference (ΔIj) / voltage difference (ΔVj) between the adjacent point A adjacent to the low voltage side and the adjacent point C adjacent to the high voltage side at the sampling number (j). Demanded by.

The measurement points A, B, and C shown in FIG. 9 are the data of the measurement points adjacent to each other by the sampling number in the IV curve data acquired from the PCS10. In the diagnostic apparatus 20, the inclination of the measurement point B is the difference between the voltage value and the current value of the measurement point C adjacent to the high voltage side and the measurement point A adjacent to the low voltage side according to the following equation (3). Calculated by.
Db = (Ic-Ia) / (Vc-Va) ... Equation (3)
Here, "Db" represents the slope of the tangent line at the measurement point B, "Vx" represents the voltage value at the measurement point X, and "Ix" represents the current value at the measurement point X.

When the slope Dp of the tangent line at the measurement point P is obtained by the equation (3), the intersection presence / absence determination unit 140 determines the inside / outside of the tangent line. Here, the "inside / outside determination" refers to a determination as to whether or not the tangent line of the slope Dp obtained at the measurement point P intersects the IV curve and reaches the region distinguished by the curve curve. In the "inside / outside determination", a setting standard (set value for step detection) for determining whether or not the tangent line of the slope Dp obtained at the measurement point P reaches within the region distinguished by the IV curve curve. ) Is used. Such a setting reference is held by the step detection set value holding unit 120.

FIG. 10 is a diagram for explaining the inside / outside determination of the tangent line with respect to the measurement point P in this embodiment. As described with reference to FIG. 5B, in the IV curve acquired from the solar cell 30, when the step region g2c is present, at least the shoulder portion g2a formed on the low voltage side and the high voltage side are formed. Will have a shoulder portion g2b formed in. Then, a part of the tangent line obtained for each measurement point in the transition region between the shoulder portions g2a and g2b intersects the IV curve transitioning from the short-circuit current (Isc) to the open circuit voltage (Voc). .. Therefore, as shown in FIG. 10A, the tangent line of each measurement point does not intersect the IV curve in the region until the shoulder portion g2a formed on the low voltage side is reached, and the curve is concerned. It is outside the area distinguished by the curve. Further, in the transition region between the shoulder portions g2a and g2b, as shown in FIG. 10B, a part of the tangent line obtained for each measurement point intersects the IV curve and is distinguished by the curve curve. It will be in the area to be.

In FIG. 10 (a), at the measurement point P in the region until reaching the shoulder portion g2a shown in FIG. 5 (b), the tangent line T obtained at the measurement point P is the IV curve as shown by the broken line. It never intersects. On the other hand, in FIG. 10B, at the measurement point P in the region from the shoulder portion g2a to the shoulder portion g2b shown in FIG. 5B, the tangent line T obtained at the measurement point P is indicated by a broken line. It intersects the IV curve so that it is within the region distinguished by the curve curve. In the step determination in this embodiment, in order to specify whether or not the tangent T obtained at each measurement point intersects the IV curve, the determination point PThresh in which a constant voltage value is offset with respect to the measurement point P The magnitude of the measured current value and the current value (tangent current value) at the determination point PThresh by the tangent line T of the measurement point P are compared. Then, the comparison result of the measured current value and the tangential current value is held as the evaluation value Jp for each measurement point.

As shown in FIG. 10A, a constant offset voltage value for performing the step determination is given as a voltage distance d with respect to the measurement point P, and the step detection set value holding unit 120 is used as the “step detection set value”. Is held in. FIG. 8B exemplifies a step detection setting value held in a table format. As shown in FIG. 8B, the step detection set value is an offset voltage value set as a voltage distance (d) with respect to the measurement point P (“30V” is stored together with the unit in the figure example. The set value can be arbitrarily set according to the amount of power generated by the photovoltaic power generation system 1, the number of modules, the number of arrays, and the like.

Returning to FIG. 10, assuming that the measured current value at the judgment point PThresh is "ITresh" and the measured voltage value is "VThresh", the tangent current value at the judgment point PThresh (IT @ Thresh) is based on the tangent line T obtained at the measurement point P. Is expressed by the following equation (1).
IT @ Thresh = (Dp) x (VThresh) + ((Ip)-(Dp) x (Vp))
... Equation (1)
Here, "IT @ Thresh" represents the current value obtained by substituting the voltage value (measured voltage value: VThresh) of the judgment point PThresh into the linear equation of the tangent line T at the measurement point P, and "Dp" is the equation (Dp). It represents the tangential slope of the measurement point P obtained in 3). The determination point PThresh represents the sample point closest to the voltage value obtained by adding the step detection set value (d) to the voltage value (Vp) of the measurement point P. “Vx” and “Ix” represent the voltage value and the current value of the measurement point X.

When the tangent current value (IT @ Thresh) at the tangent determination point PThresh at the measurement point P is obtained by the equation (1), the intersection presence / absence determination unit 140 uses the following equation (2) to determine the inside / outside (step). Inside / outside judgment) is performed.
Step inside point: ITResh ＞ IT @ Thresh ・ ・ ・ Equation (2)
The result of the determination by the equation (2) is held in the evaluation value Jp for each measurement point. For example, as shown in FIG. 10A, when the tangent current value (IT @ Thresh) due to the tangent line T obtained at the measurement point P is larger than the measured current value “IThresh” at the determination point PThresh, the value indicates the outside of the step. (For example, "0") is held in the evaluation value Jp. On the other hand, as shown in FIG. 10B, when the tangent current value (IT @ Thresh) due to the tangent line T obtained at the measurement point P is smaller than the measured current value "ITresh" at the determination point PThresh, it is within the step. (For example, "1") is held in the evaluation value Jp. The intersection presence / absence determination unit 140 performs the arithmetic processing shown in the equations (1) to (3) on all the IV curve data acquired through the PCS 10, and evaluates each measurement point specified by the sampling number. Get Jp. The evaluation value Jp for each measurement point is delivered to the step determination unit 150.

In the step determination unit 150, the evaluation value Jp for each measurement point handed over from the intersection presence / absence determination unit 140 and the determination reference value for determining the presence / absence of the step held in the determination reference holding unit 130 are acquired. It is determined whether or not the step region g2c exists in the IV curve data.

The step determination unit 150 calculates a score value (J) for determining the presence or absence of a step from the evaluation value Jp for each measurement point handed over from the intersection presence / absence determination unit 140 using the following equation (4). ..
J = (ΣXp) / L ・ ・ ・ Equation (4)
Here, P represents a sampling number from 1 to N, and “Xp” represents an evaluation value Jp of each measurement point specified by the sampling number. "N" represents the sample score of the score calculation data. Therefore, "L" = "N". The step determination unit 150 divides the sum of the evaluation values Jp processed for each measurement point by the number of sample points to calculate the score value (J) related to the determination.

Then, the step determination unit 150 performs a magnitude comparison between the score value (J) obtained using the equation (4) and the determination reference value (Thr) held in the determination reference holding unit 130, and is obtained. It is determined whether or not the step region g2c exists in the IV curve data. The determination for the score value (J) is performed using the following equation (5). The determination reference value held by the determination reference holding unit 130 is illustrated in FIG. 8C. As shown in FIG. 8C, the determination reference value (Thr) is stored as a determination threshold value (“0.2” in the figure) with respect to the score value. Further, the determination reference value for evaluating the score value can be arbitrarily set according to the amount of power generation of the photovoltaic power generation system 1, the number of modules, the number of arrays, and the like.
J ≦ Thr ・ ・ ・ ・ Equation (5)

When the score value (J) is equal to or less than the determination reference value (Thr), the step determination unit 150 determines that the step region g2c does not exist in the IV curve data acquired from the solar cell 30. That is, the construction state of the connection wiring between the solar cell modules constituting the solar cell 30 is determined to be a normal state. On the other hand, when the score value (J) exceeds the determination reference value (Thr), it is determined that the step region g2c exists in the IV curve data acquired from the solar cell 30. That is, the construction state of the connection wiring between the solar cell modules constituting the solar cell 30 is determined to be an abnormal state in which a connection error or the like has occurred.

Returning to FIG. 7, the step determination unit 150 delivers the determination result processed based on the score value (J) and the determination reference value (Thr) to the determination result display unit 150 and the determination result transmission unit 160. The determination result display unit 150 displays the determination result on, for example, a display device such as an LCD included in the diagnostic apparatus 20. On the display screen of the diagnostic apparatus 20, for example, the normal / abnormal state of the wiring state connecting the solar cell modules is displayed together with the IV curve based on the data acquired from the PCS 10. Further, the determination result transmission unit 160 transmits the determination result to the PCS 10 connected to the diagnostic apparatus 20 and other devices (smartphone, server, etc.). The determination result is transmitted together with the acquired IV curve together with, for example, the identification information (identification number of the PCS10) for identifying the photovoltaic power generation system 1 and the date and time information. In the device connected to the diagnostic device 20, the diagnostic results relating to the normal / abnormal wiring state of the photovoltaic power generation system connecting between the solar cell modules are shown together with the IV curve based on the data acquired from the PCS 10. It will be possible to browse.

<Processing flow>
FIG. 11 is a flowchart showing an example of the diagnostic process provided by the diagnostic apparatus 20 according to the present embodiment. In the flow of FIG. 10, the normal / abnormal state of the wiring state connecting the solar cell modules is diagnosed based on the IV curve data acquired through the PCS10. The diagnostic device 20 acquires a voltage value and a current value (IV curve data) indicating the actually measured IV characteristics from the PCS 10 connected through the communication IF 24 (step S101), and stores the acquired IV curve data as auxiliary storage. The data is stored in a predetermined area of the device 23, and the process proceeds to step S102. In step S102, when the slope Dp of the tangent line at each measurement point of the acquired IV curve data is calculated using the equation (3), the process proceeds to step S103. In step S103, as described with reference to FIGS. 8, 9 and 10, it is determined whether or not the tangent of each measurement point intersects with the IV curve curve using equations (1) to (3). .. After the processing of step S103, the processing proceeds to step S104.

In step S104, when the score value (J) for determining the step is calculated using the equation (4), the process proceeds to step S105. In step S105, it is determined whether or not a step region exists on the acquired IV curve curve using the equation (5). For example, when the score value (J) is equal to or less than the judgment reference value (Thr), it is determined that the step region g2c does not exist in the IV curve data acquired through the PCS10. That is, it is determined that the construction state of the connection wiring between the solar cell modules constituting the solar cell 30 of the photovoltaic power generation system 1 to be diagnosed is a normal state. On the other hand, when the score value (J) exceeds the determination reference value (Thr), it is determined that the step region g2c exists in the IV curve data acquired through the PCS10. That is, the construction state of the connection wiring between the solar cell modules constituting the solar cell 30 of the photovoltaic power generation system 1 to be diagnosed is determined to be an abnormal state in which a connection error or the like has occurred. After the process of step S105, the process proceeds to step S106. In step S106, the determination result is displayed on a display unit such as a display device included in the diagnostic device 20, and is transmitted to another device (PCS10, smartphone, server, etc.) connected through the communication IF24 which is a communication unit. For example, in the device connected to the diagnostic device 20, the diagnostic result relating to the normal / abnormal of the wiring state connecting the solar cell modules for the photovoltaic power generation system is based on the data acquired from the PCS10 IV. It will be viewable along with the curve. When the process of step S106 is completed, this routine is temporarily terminated.

As described above, in this embodiment, the normal / abnormal wiring state of the solar cells 30 constituting the photovoltaic power generation system 1 connecting between the solar cell modules is determined based on the shape of the IV curve data. Can be diagnosed. Specifically, the slope Dp of the tangent line T at the measurement point can be obtained from each measured measurement point. Then, the current obtained from the measured current value at the determination point PThresh in which a constant voltage value (set value for step detection) is offset with respect to the measurement point P and the slope Dp of the tangent T with respect to the measured voltage value at the determination point. Compare with the value (tangential current value). When the tangent current value (IT @ Thresh) due to the tangent line T obtained at the measurement point P is larger than the measured current value "ITresh" at the determination point PThresh, a value indicating that it does not intersect the IV curve curve (for example, "0"). ) Is held as the evaluation value Jp. On the other hand, when the tangent current value (IT @ Thresh) due to the tangent line T obtained at the measurement point P is smaller than the measured current value "IThresh" at the determination point PThresh, a value indicating that it intersects the IV curve curve (for example, "IThresh"). 1 ”) is held as the evaluation value Jp. Then, the presence or absence of the step region is determined based on the sum of the evaluation values Jp held for the measurement points in all the sections where the IV curve data is measured.

In this embodiment, when the sum of the evaluation values Jp held for the measurement points in all the sections where the IV curve data is measured is equal to or less than the judgment standard, it is determined that the step region does not exist, and the solar cell 30 is configured. The construction status of the connection wiring between the solar cell modules is diagnosed as normal. Further, when the sum of the evaluation values Jp exceeds the judgment standard, it is determined that the step region exists, and the construction state of the connection wiring between the solar cell modules constituting the solar cell 30 is diagnosed as an abnormal state. As a result, in the present embodiment, it is possible to determine the connection failure of the wiring connecting the solar cell modules based on the shape of the IV curve data, and the construction quality in the photovoltaic power generation system can be improved.

Further, in the present embodiment, since the step region in the IV curve can be determined based on the slope Dp of the tangent line at each measurement point, it is not necessary to obtain the area of the measured IV curve and the area of the reference IV curve from the measured IV curve. good. According to this embodiment, the processing cost of the calculation related to the diagnosis can be reduced. Further, in the present embodiment, since the score value is calculated based on the sum of the evaluation values (Jp) calculated for each measurement point of the IV curve, for example, the influence of noise superimposed during the measurement of the IV curve data is affected. Can be reduced. According to this embodiment, it is possible to increase the accuracy of determining whether the connection wiring between the solar cell modules is normal or not.

[Example 2]
FIG. 12 is a block diagram showing an example of the functional configuration of the diagnostic apparatus 20 according to the second embodiment. In the second embodiment, the diagnostic device 20 further includes a thinning setting value holding unit 210 and a data thinning processing unit 220 as functional elements. In the diagnostic apparatus 20 according to the second embodiment, thinning processing is performed on the IV curve data acquired through the PCS 10 by the functions of the thinning set value holding unit 210 and the data thinning processing unit 220. In this embodiment, by performing the thinning process, it is possible to reduce the detection of the step error due to the influence of the current measurement error and noise in the actually measured data related to the step determination. According to this embodiment, it is possible to enhance the normal / abnormal determination system of the construction state of the connection wiring between the solar cell modules. In FIG. 12, a detailed description of the same configuration as that of the first embodiment will be omitted by using the same reference numerals, and differences from the first embodiment will be mainly described.

In FIG. 12, the data thinning processing unit 220 executes thinning processing on the IV curve data acquired through the PCS 10 according to the thinning setting value held in the thinning setting value holding unit 210, and the data after the thinning processing. Is handed over to the intersection presence / absence determination unit 140. Then, in the intersection presence / absence determination unit 140 of the present embodiment, the arithmetic processing shown in the equations (1) to (3) described in the first embodiment is performed based on the IV curve data thinned out according to the thinning setting value. Therefore, the evaluation value Jp for each measurement point is calculated.

FIG. 13 is a diagram showing an example of the thinning set value held in the thinning set value holding unit 210. In the thinning set value, the current width (ITr) set for reducing the fluctuation width due to the influence of current measurement error and noise is stored together with the unit. In FIG. 13, “0.08A” is set as the current width (ITr). The thinning setting value can be arbitrarily set according to the scale of the power generation amount, the number of modules, the number of arrays, etc. of the photovoltaic power generation system 1.

FIG. 14 is a diagram illustrating a thinning process for IV curve data. In FIG. 14, the measurement points p-1, p, and p + 1 are measurement points adjacent to the low voltage side and the high voltage side when the attention index (sampling number) is p. Let the measured current values of the measurement points p-1, p, and p + 1 be Ip-1, Ip, and Ip + 1, respectively. The data thinning processing unit 220 executes the thinning processing using the following equation (6) based on the current width (ITr) set as the thinning set value.
| Ip-Ip + 1 | <IThr, and | Ip-1-Ip | <IThr ... Equation (6)
That is, the IV curve so that the difference between the low voltage side p-1 adjacent to the point of interest p and the difference current value from the high voltage side p + 1 adjacent to the point of interest p are equal to or greater than the current width (IThr). Data is thinned out. The data thinning processing unit 220 executes data thinning until there are no measurement points satisfying the condition of the equation (6).

FIG. 15 is a flowchart showing an example of the diagnostic process provided by the diagnostic apparatus 20 according to the present embodiment. In the flow of FIG. 15, the normal / abnormal state of the wiring state connecting the solar cell modules is diagnosed based on the IV curve data acquired through the PCS10. The diagnostic device 20 acquires a voltage value and a current value (IV curve data) indicating the actually measured IV characteristics from the PCS 10 connected through the communication IF 24 (step S101), and stores the acquired IV curve data as auxiliary storage. The data is stored in a predetermined area of the device 23, and the process proceeds to step S111. In step S111, the thinning process of the measurement data represented by the equation (6) is executed based on the current width (ITr) set as the thinning set value. When there is no measurement point satisfying the condition of the equation (6) with respect to the acquired IV curve data, the process proceeds to step S102. In step S102 and subsequent steps, the same processing as in step S106 is executed from step S102 shown in FIG. When the process of step S106 is completed, this routine is temporarily terminated.

As described above, in the present embodiment, the thinning process for the IV curve data acquired through the PCS 10 is performed by the functions of the thinning setting value holding unit 210 and the data thinning processing unit 220. Then, the normal / abnormal state of the wiring connecting between the solar cell modules of the solar cell 30 constituting the photovoltaic power generation system 1 can be diagnosed by using the shape of the IV curve data subjected to the thinning process as the processing target. In this embodiment, by performing the thinning process, it is possible to thin out the measurement points having a change width less than the current width (ITr) set as the thinning set value. As a result, it is possible to reduce the detection of step error due to the influence of current measurement error and noise in the measured data related to the step judgment, and it is possible to judge whether the construction state of the connection wiring between the solar cell modules is normal / abnormal. The system can be enhanced. Further, according to the present embodiment, as compared with the first embodiment, the diagnosis is performed on the IV curve data that has been thinned out, so that the processing cost of the calculation related to the diagnosis can be further reduced. Become.

[Example 3]
FIG. 16 is a block diagram showing an example of the functional configuration of the diagnostic apparatus 20 according to the third embodiment. In the third embodiment, the diagnostic apparatus 20 further includes a data grouping function 310 as a functional element. In the diagnostic apparatus 20 according to the third embodiment, the data grouping process for determining the step is further performed on the IV curve data to which the thinning process described in the second embodiment has been performed. In this embodiment, by performing the grouping process, it is possible to reduce the step detection erroneous detection due to the influence of the step size (current fluctuation width). According to this embodiment, it is possible to further improve the determination accuracy regarding the step determination. In FIG. 16, the same configurations as those in the first and second embodiments will be omitted in detail by using the same reference numerals, and the differences from the second embodiment will be mainly described.

In FIG. 16, in the data grouping function 310, the evaluation value Jp for each measurement point for which the intersection presence / absence determination is performed on the IV curve data that has been thinned out is delivered from the intersection presence / absence determination unit 140. The data grouping function 310 executes the grouping process based on the inside / outside determination result (inside the step: 1, outside the step: 0) held in the evaluation value Jp handed over from the intersection presence / absence determination unit 140. The result of the grouping process is passed to the step determination unit 150 together with information indicating the number of formed groups as an evaluation value Yg for evaluating the current change width for each group.

FIG. 17 is a diagram illustrating a grouping process. In FIG. 17, the measurement point subjected to the thinning process is within the region (step) divided by the IV curve curve at the offset voltage position set by the set value for step detection based on the slope Dp of the tangent line T. An example is a measurement point as a result of determining (inside) or outside the area (outside the step). The result of the inside / outside determination based on the slope Dp of the tangent line T is held in the evaluation value Jp.

As shown in FIG. 17, in the data grouping function 310, the IV curve data grouping process is based on the determination value held in the evaluation value Jp, that is, “1” inside the step and “0” outside the step. I do. Specifically, when two or more measurement points whose value held in the evaluation value Jp is "1" are continuous, they are grouped as a measurement point group forming one step group. In FIG. 17, the step group 1 is formed by two consecutive measurement points, and the step group 2 is formed by three consecutive measurement points. There is a single measurement point determined to be within the step between the step group 1 and the step group 2, but the measurement point is determined to be within the step on the adjacent low voltage side or high voltage side. It is not grouped because there are no measured points.

Then, in the data grouping function 310, the voltage value and the current value for both ends (low voltage side measurement point and high voltage side measurement point) of the grouped measurement point group are recorded respectively. In the diagnostic apparatus 20 of the third embodiment, the voltage values and current values at both ends of the group are temporarily stored in a predetermined area of the main storage unit 22 in association with the sampling number that identifies the measurement point. ..

In FIG. 17, for example, the voltage value (VL1) and the current value (IL1) at the measurement points on the low voltage side forming the step group 1 and the voltage value (VH1) and the current value (IH1) at the measurement points on the high voltage side. ) And is recorded. Further, in the step group 2, the voltage value (VL2) and the current value (IL2) of the measurement points on the low voltage side among the measurement points forming the group, and the voltage value (VH2) at the measurement points on the high voltage side. ) And the current value (IH2) are recorded.

In the data grouping function 310 according to this embodiment, the evaluation value Yg for each step group is calculated using the following equation 7.
Yg = (IHg)-(ILg) ・ ・ ・ Equation (7)
Here, "g" represents a group number for identifying the grouped measurement point groups, and "G" represents the total number (number of groups) of the grouped measurement point groups. From the equation (7), the projected value (current change width) with respect to the current axis of each grouped measurement point group is obtained as an evaluation value.

In the step determination unit 150, the step determination process is performed based on the evaluation value Yg for evaluating the current change width for each group and the number of groups (G) handed over from the data grouping function 310. Specifically, the evaluation value Xp in the equation (4) is replaced with the evaluation value Yg, the number of samples (L) of the data for score calculation is replaced with the short-circuit current value (Isc), and the sum is based on the total number of groups. The score value J is calculated. The score value is determined by using the equation (5) as in the first embodiment. That is, when the score value J is equal to or less than the judgment reference value (Thr), it is determined that there is no step (the connection state of the inter-module wiring is normal), and if not, there is a step (the connection state of the inter-module wiring is abnormal). Judged.

FIG. 18 is a flowchart showing an example of the diagnostic process provided by the diagnostic apparatus 20 according to the present embodiment. In the flow of FIG. 18, the normal / abnormal state of the wiring state connecting the solar cell modules is diagnosed based on the step determination using the grouping process. In step S101, when the voltage value and the current value (IV curve data) indicating the actually measured IV characteristics are acquired from the PCS 10 in the same manner as in the second embodiment, the thinning process is performed (step S111). Proceeds to step S102. In steps S102 and S103, the same processing as in the first embodiment is performed, and as a result of the processing, the evaluation value Jp for each measurement point after the thinning process is delivered to step S121.

In step S121, grouping processing is performed on the measurement points determined to be within the step based on the determined value (“1” or “0”) of the delivered evaluation value Jp. As described with reference to FIG. 17, when two or more measurement points whose value held in the evaluation value Jp is "1" are continuous, they are grouped as a measurement point group forming one step group. NS. Then, the voltage value and the current value for the low voltage side measurement point and the high voltage side measurement point of the grouped measurement point group are extracted for each group. Then, based on the respective current values for the low voltage side measurement point and the high voltage side measurement point extracted for each group, the evaluation value Yg for each step group is obtained using the equation (7). In step S121, the evaluation value Yg and the number of groups G obtained for each step group are passed to step S104, and the process proceeds to step S104.

In step S104, the evaluation value Y for each step group delivered from step S121
The score value J for determining the step is calculated based on g, the number of groups G, and the short-circuit current value (Isc). Specifically, the evaluation value Xp in the equation (4) is replaced with the evaluation value Yg, the number of samples (L) of the data for score calculation is replaced with the short-circuit current value (Isc), and the sum is based on the total number of groups. The score value J is calculated. When the score value J is calculated, the process proceeds to step S105. In step S105 and subsequent steps, the same processing as in steps S105 to S106 shown in FIG. 11 is executed. When the process of step S106 is completed, this routine is temporarily terminated.

As described above, in the present embodiment, the function of the data grouping function 310 performs grouping processing on the IV curve data based on the determination values indicating the inside and outside of the step held in the evaluation value Jp. Will be. Then, a group of measurement points satisfying a predetermined condition (measurement points whose value held in the evaluation value Jp is "1" is continuous) is grouped, and the current change width in the group is evaluated for step determination. set to target. In this embodiment, since the current change width of the grouped measurement point group can be used as an evaluation target for determining the step, it is possible to reduce the error detection due to the influence of the size of the step. According to this embodiment, it is possible to further improve the determination accuracy regarding the step determination, and diagnose the normal / abnormal state of the wiring state of the solar cells 30 constituting the photovoltaic power generation system 1 connecting between the solar cell modules. It is possible to improve the accuracy.

In Examples 1 to 3, the evaluation is performed based on the transition of the current value acquired as the IV curve data, but similarly, based on the transition of the voltage value acquired as the IV curve data. Needless to say, it can be evaluated.

(others)
The above embodiment is merely an example, and the disclosure of the present embodiment may be appropriately modified and implemented without departing from the gist thereof. The processes and means described in the present disclosure can be freely combined and carried out as long as there is no technical contradiction.

Further, the processing described as being performed by one device may be shared and executed by a plurality of devices. Alternatively, the processing described as being performed by different devices may be performed by one device. In a computer system, it is possible to flexibly change what kind of hardware configuration (server configuration) is used to realize each function.

<< Computer-readable recording medium >>
A program that enables an information processing device or other machine or device (hereinafter referred to as a computer or the like) to realize any of the above functions can be recorded on a recording medium that can be read by a computer or the like. Then, the function can be provided by causing a computer or the like to read and execute the program of this recording medium.

Here, a recording medium that can be read by a computer or the like is a recording medium that can store information such as data and programs by electrical, magnetic, optical, mechanical, or chemical action and can be read from the computer or the like. To say. Among such recording media, those that can be removed from a computer or the like include, for example, a memory such as a flexible disk, a magneto-optical disk, a CD-ROM, a CD-R / W, a DVD, a Blu-ray disk, a DAT, an 8 mm tape, or a flash memory. There are cards etc. In addition, there are hard disks, ROMs, and the like as recording media fixed to computers and the like.

In addition, in order to make it possible to compare the constituent requirements of the present invention with the configurations of the examples, the constituent requirements of the present invention are described below with reference numerals in the drawings.
<Invention 1>
It is a diagnostic device (20) for diagnosing whether the power generation state of the solar cell (30) composed of a plurality of photovoltaic power generation modules (33) is a normal state or an abnormal state.
Acquiring the current-voltage characteristics of the solar cell (30) with respect to the change in the current value that changes with the increase or decrease of the voltage value, which is measured with a predetermined number of samples.
With the increase or decrease of the first characteristic value at the sample point, the current-voltage characteristic is based on one of the first characteristic values and the other second characteristic value of the voltage value or the current value for each measured sample point. To calculate the slope of the change in the second characteristic value that changes
A magnitude comparison between the estimated second characteristic value estimated from the slope of the change with respect to the predetermined first characteristic value and the second characteristic value measured corresponding to the predetermined first characteristic value in the current-voltage characteristic. Based on the determination result, diagnosing whether the power generation state of the solar cell (30) is in a normal state or an abnormal state, and
A diagnostic device (20) comprising a control unit (21) for executing the above.

1: Solar power generation system 10: Power conditioner (PCS)
10a: Power conversion unit 10b: Control unit 11: Current sensor 12: Voltage sensor 15: Blocking diode 20: Diagnostic device 21: Processor 22: Main storage device 23: Auxiliary storage device 24: Communication IF
25: Input / output IF
26: Connection bus 30: Solar cell 31: Solar cell array 32: String 33: Solar cell module 40: Commercial power system 50: Load 110: IV curve data reading unit 120: Step detection set value holding unit 130: Judgment standard holding Unit 140: Crossing presence / absence determination unit 150: Step determination unit 160: Judgment result display unit 170: Judgment result transmission unit 210: Thinning set value holding unit 220: Data thinning processing unit 310: Grouping function

Claims (7)

It is a diagnostic device that diagnoses whether the power generation state of a solar cell composed of a plurality of photovoltaic power generation modules is a normal state or an abnormal state.
To acquire the current-voltage characteristics regarding the change in the current value that changes with the increase or decrease of the voltage value measured with a predetermined number of samples for the solar cell.
With the increase or decrease of the first characteristic value at the sample point, the current-voltage characteristic is based on one of the first characteristic values and the other second characteristic value of the voltage value or the current value for each measured sample point. To calculate the slope of the change in the second characteristic value that changes in
A magnitude comparison between the estimated second characteristic value estimated from the slope of the change with respect to the predetermined first characteristic value and the second characteristic value measured corresponding to the predetermined first characteristic value in the current-voltage characteristic. Based on the determination result, diagnosing whether the power generation state of the solar cell is in a normal state or an abnormal state, and
A diagnostic device comprising a control unit for executing the above. The control unit determines that the estimated second characteristic value for each sample point at which the current-voltage characteristic is measured is smaller than the second characteristic value measured corresponding to the predetermined first characteristic value. The diagnostic device according to claim 1, wherein the points are counted and when the ratio of the counted sample points to the total number of samples is equal to or less than the determination reference value, the power generation state of the solar cell is diagnosed as a normal state. The control unit determines that the estimated second characteristic value for each sample point at which the current-voltage characteristic is measured is smaller than the second characteristic value measured corresponding to the predetermined first characteristic value. The diagnostic apparatus according to claim 1 or 2, wherein the points are counted and when the ratio of the counted sample points to the total number of samples exceeds the determination reference value, the power generation state of the solar cell is diagnosed as an abnormal state. .. The control unit
Among the sample points where the current-voltage characteristics were measured, the second characteristic value measured at the first sample point and the sample points adjacent to the lower side of the first characteristic value of the first sample point were measured. The difference from the second characteristic value on the lower side is less than the first threshold value, and the second characteristic value and the second characteristic value on the higher side measured at the sample points adjacent to the higher side of the first sample point. The diagnostic device according to any one of claims 1 to 3, wherein the first sample points are thinned out when the difference between the two is less than the second threshold value. In the control unit, the estimated second characteristic value estimated from the slope of the change with respect to the predetermined first characteristic value in the sample points where the current-voltage characteristic is measured is the predetermined second characteristic value in the current-voltage characteristic. In addition to grouping consecutive sample point clouds determined to be smaller than the second characteristic value measured corresponding to one characteristic value,
In the grouped sample point group, the difference second characteristic value, which is the difference between the lower second characteristic value measured at the lower sample point and the higher second characteristic value measured at the higher sample point, Any of claims 1 to 4, which diagnoses whether the power generation state of the solar cell is in a normal state or an abnormal state based on the ratio of the first characteristic value to the reference second characteristic value at 0 value. The diagnostic device according to paragraph 1. It is a diagnostic method for diagnosing whether the power generation state of a solar cell composed of a plurality of photovoltaic power generation modules is a normal state or an abnormal state.
To acquire the current-voltage characteristics regarding the change in the current value that changes with the increase or decrease of the voltage value measured with a predetermined number of samples for the solar cell.
With the increase or decrease of the first characteristic value at the sample point, the current-voltage characteristic is based on one of the first characteristic values and the other second characteristic value of the voltage value or the current value for each measured sample point. To calculate the slope of the change in the second characteristic value that changes
A magnitude comparison between the estimated second characteristic value estimated from the slope of the change with respect to the predetermined first characteristic value and the second characteristic value measured corresponding to the predetermined first characteristic value in the current-voltage characteristic. Based on the determination result, diagnosing whether the power generation state of the solar cell is in a normal state or an abnormal state, and
A diagnostic method comprising. It is a program to be executed by a computer that diagnoses whether the power generation state of a solar cell composed of multiple photovoltaic power generation modules is normal or abnormal.
To acquire the current-voltage characteristics regarding the change in the current value that changes with the increase or decrease of the voltage value measured with a predetermined number of samples for the solar cell.
With the increase or decrease of the first characteristic value at the sample point, the current-voltage characteristic is based on one of the first characteristic values and the other second characteristic value of the voltage value or the current value for each measured sample point. To calculate the slope of the change in the second characteristic value that changes
A magnitude comparison between the estimated second characteristic value estimated from the slope of the change with respect to the predetermined first characteristic value and the second characteristic value measured corresponding to the predetermined first characteristic value in the current-voltage characteristic. Based on the determination result, diagnosing whether the power generation state of the solar cell is in a normal state or an abnormal state, and
A program characterized by executing.

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