JP5205345B2 - Failure diagnosis system, failure diagnosis apparatus, failure diagnosis method, program, and storage medium - Google Patents

Description

  The present invention relates to a failure diagnosis system, a failure diagnosis device, a failure diagnosis method, a program, and a storage medium for estimating and diagnosing a failure location of a solar cell array, and in particular, a solar cell string in which a plurality of solar cell modules are connected in series. The present invention relates to a failure diagnosis system that estimates and diagnoses a failure location of a solar cell array.

  In general, it has been said that solar cells continue to function maintenance-free for over 20 years outdoors. In recent years, however, there have been reported cases such as failures and malfunctions such as a decrease in the output of solar cells due to aging. In order to clarify the cause of a failure or malfunction, measurement of open voltage, confirmation of the presence or absence of disconnection, measurement of current voltage (IV characteristics), presence or absence of changes in power generation characteristics, etc. have been manually confirmed. In addition, in order to narrow down candidates for a failure location, a method of visually finding a location (hot spot) at a high temperature using a thermo camera or the like has been employed.

  Recently, a technique has been developed for finding a failure point of a solar cell panel in a solar cell string in which solar cell modules are connected in series (see Patent Literature 1) and finding a disconnection location between solar cell modules (see Patent Literature 2). It is coming. The method described in Patent Document 1 will be specifically described as an example. FIG. 8 is a diagram showing an outline of a conventional failure diagnosis system 53 described in Patent Document 1. As shown in FIG. The input signal generation unit 55 generates a pulse wave that is an input signal to the solar cell string 3 that is a failure diagnosis target. The generated input signal is applied (input) to the solar cell string 3, and the actual measurement unit 57 obtains an actual measurement signal that is a combined signal of the reflected signal output from the solar cell string 3 and the input signal. In the solar cell array having a plurality of solar cell strings, the comparison unit 59 compares the actual measurement signal from the normal string 49 having no failure and the actual measurement signal from the failure string 51 having a failure to obtain a waveform of a difference signal. Here, since the waveforms of the actual measurement signal and the difference signal differ depending on the failure location and content of the failure string, it is possible in principle to diagnose the failure location of the solar cell string 3 using the pulse wave as an input signal. is there.

JP 2009-21341 A JP 2008-91828 A

  However, with the manual method, the cost and labor required for a large-scale photovoltaic power generation system are enormous, which is practically impossible to implement.

  Further, the methods described in Patent Document 1 and Patent Document 2 indicate the possibility of finding a failure location in a state where the measurement environment is strictly controlled. For this reason, it is difficult to say that these methods sufficiently consider the preconditions for performing failure diagnosis in the installation environment.

  That is, in the methods described in Patent Document 1 and Patent Document 2, the influence of a specific installation environment on the actual measurement signal is not considered. As will be described later, for example, the waveform of the actual measurement signal is greatly influenced and changed only by the length of the cable. Under a specific installation environment, there are enormous output signal waveforms that can be said to be infinite. It is impossible to prepare such an enormous output signal waveform in advance. In order to detect a fault location under a specific installation environment, it is necessary to develop a method capable of performing a fault diagnosis according to the installation environment.

  Further, the methods described in Patent Document 1 and Patent Document 2 do not show a specific determination process for the actual measurement signal of the solar cell string 3. There are many different environments for installing solar cells. For this reason, it is possible to grasp in advance the waveform of an infinite number of output signals for any combination of installation environment and failure location, etc., and diagnose the failure location only from the actual measurement signal obtained from the solar cell string subject to failure diagnosis. To do is not realistic.

  Therefore, an object of the present invention is to provide a failure diagnosis system and the like that take into consideration the influence of the installation environment in realizing the diagnosis by estimating the failure location of the solar cell array.

  The invention according to claim 1 is a failure diagnosis system for estimating and diagnosing a failure location of a solar cell array having a solar cell string in which a plurality of solar cell modules are connected in series, and an input applied to the solar cell string An input signal determining unit that determines a waveform of a signal, an input signal generating unit that generates the input signal determined by the input signal determining unit, and the input from the input signal generating unit to the solar cell string via a cable The input signal is applied to a virtual model that simulates an actual measurement unit that obtains an actual measurement signal that is an output signal when a signal is applied, and the input signal generation unit, the cable, and the solar cell string. A simulator unit that calculates a pseudo output signal that is an output signal in the case of being generated, and the pseudo output that is calculated from the actually measured signal. A comparison unit that compares with a signal, a matching rate calculation unit that calculates a matching rate that is a degree to which the actual measurement signal and the pseudo output signal are similar, from the comparison result output by the comparison unit, and a candidate for the virtual model, A library having a pseudo-failure database that stores parameters of a model corresponding to each failure location, and the input signal that matches the impedance of the cable with reference to the pseudo-failure database assuming the failure location of the solar cell string A parameter determination unit that determines the virtual model by determining a parameter value including a resistance value of the generation unit and a parameter of the cable length, and the accuracy rate calculated by the accuracy rate calculation unit is a predetermined value. If there is an assumed failure location that is greater than or equal to the value, the relevance ratio calculating unit determines that the assumed failure location is the solar cell array. It is estimated that failure location.

  The invention according to claim 2 is the fault diagnosis system according to claim 1, wherein the solar cell array has a plurality of solar cell strings connected in parallel, and the library is shipped when the solar cell strings are shipped. The comparison unit further includes an actual measurement signal from a normal string that does not have a failure among the plurality of solar cell strings included in the solar cell array, and the shipping database. The correction data is calculated by comparing with the actual measurement signal at the time of shipment of the normal string, the pseudo output signal is corrected using the correction data, and the comparison result is output.

  The invention according to claim 3 is the failure diagnosis system according to claim 1 or 2, wherein the library further includes a failure database that stores combinations of failure contents of solar cell strings measured in the past and measured signals. The precision calculation unit determines the predetermined value related to the precision by referring to the failure database, and if the precision is less than the predetermined value, the assumed failure location is Let the parameter determination unit assume different fault locations.

  The invention according to claim 4 is a failure diagnosis device for estimating and diagnosing a failure location of a solar cell array having a solar cell string in which a plurality of solar cell modules are connected in series, and an input signal to be generated is transmitted via a cable. A pseudo output signal that is an output signal when the input signal is applied to a virtual model that simulates the input signal generation unit, the cable, and the solar cell string applied to the solar cell array. A simulator unit for calculating, a comparison unit for comparing the pseudo output signal calculated by the simulator unit with an actual measurement signal that is an output signal when the input signal is applied to the solar cell string, and the comparison unit A matching rate calculation unit that calculates a matching rate that is a degree of similarity between the actual measurement signal and the pseudo output signal from the output comparison result; A library having a pseudo-failure database storing model parameters corresponding to each failure location, which is a candidate for the virtual model, and referring to the pseudo-failure database assuming the failure location of the solar cell string, the cable A parameter determination unit that determines the virtual model by determining a parameter value including a resistance value of the input signal generation unit that matches the impedance of the cable and a parameter of the length of the cable. If there is an assumed failure location where the calculated accuracy rate is equal to or greater than a predetermined value, the accuracy rate calculation unit estimates the assumed failure location as a failure location of the solar cell array.

  The invention according to claim 5 is a failure diagnosis method in a failure diagnosis device for estimating and diagnosing a failure location of a solar cell array having a solar cell string in which a plurality of solar cell modules are connected in series. Corresponds to each failure location, which is a candidate for a virtual model that simulates the input signal generation unit, the cable, and the solar cell string that apply the generated input signal to the solar cell array via a cable. A library having a pseudo-failure database that stores parameters of models to be matched, and the parameter determination means assumes the failure location of the solar cell string and matches the impedance of the cable with reference to the pseudo-failure database Including the resistance value of the input signal generator and the cable length parameter. Determining the virtual model by determining the parameter value, and a pseudo output signal that is an output signal when the simulation unit applies the input signal to the virtual model determined by the parameter determination unit A comparison means, a comparison means comparing an actual measurement signal that is an output signal when the input signal is applied to the solar cell string, and the pseudo output signal, and a matching ratio calculation means is the comparison means. Is calculated from the comparison result output by the calculation of a matching rate that is a degree of similarity between the actual measurement signal and the pseudo output signal, and if there is an assumed failure location where the matching rate is equal to or greater than a predetermined value, the assumed failure location is calculated. Estimating a failure location of the solar cell array.

  The invention according to claim 6 is a program for causing a computer to execute the failure diagnosis method according to claim 5.

  The invention according to claim 7 is a computer-readable recording medium on which the program according to claim 6 is recorded.

  The simulated fault database may store a finite number of standard parameter value combinations. The parameter determination unit may determine the virtual model by correcting the parameter value stored in the simulated fault database according to the setting environment, and / or the comparison unit may perform the simulation according to the setting environment. The output signal may be corrected for comparison.

  According to the invention according to each claim of the present application, the solar cell array is diagnosed including the installed cable and the resistance of the input signal generation unit. Therefore, it is possible to estimate the failure location of the solar cell array in the actual installation environment.

  Furthermore, since a solar cell array generally exists as a power source, a failure is detected based on DC characteristics such as the amount of power detected by a power conditioner, for example. Therefore, in the inspection at the time of shipment, an output signal whose signal intensity continues relatively unchanged has been used. The inspection based on the AC characteristics in a specific installation state has not been performed so far. On the other hand, the invention according to each claim of the present application estimates a failure location based on AC characteristics based on an output signal detected according to a change in an input signal under a specific installation environment. According to the invention according to each claim of the present application, the parameter determination unit refers to the pseudo-failure database, and includes parameters derived from the installation environment such as the cable length and the resistance value of the input signal generation unit. To determine the virtual model. Therefore, it is not necessary to prepare in advance an enormous output signal waveform that can be said to be infinite under a specific installation environment, and inspection based on AC characteristics is possible.

  Further, according to the invention according to claim 2, it is obtained by comparing an actual measurement signal from a normal string and an actual measurement signal at the time of shipment of the normal string among a plurality of parallel-connected solar cell strings of the solar cell. The pseudo output signal is corrected using the corrected data. The correction data includes the influence of the installation environment related to characteristics (resistance value, capacitance value, inductance value, etc.) depending on the length of the installed cable on the measured signal. Therefore, it is not necessary to input a parameter derived from the installation environment every time the failure diagnosis is performed, and it is possible to easily estimate and diagnose the failure location of the solar cell array in a specific installation environment.

  Furthermore, according to the invention according to claim 3, the relevance ratio calculating unit refers to a failure database storing past actual measurement signals, and then the failure of the solar cell array whose assumed failure location is the target of failure diagnosis The value of the matching rate between the actual measurement signal and the pseudo output signal to be satisfied to be estimated as a location is determined. In addition, if the calculated accuracy rate is less than a value determined based on past knowledge, the accuracy rate calculation unit causes the parameter determination unit to assume a failure location different from the assumed failure location. Therefore, the more reliable the accumulated past knowledge is, the more accurate the instruction to correct the failure location by the relevance ratio calculation unit becomes, and the reliability of the estimated failure location increases. That is, knowledge obtained from failure diagnosis under a specific installation environment is accumulated in the failure database, and this can be reflected in failure diagnosis. Therefore, it is possible to estimate the failure location of the solar cell array in a specific installation environment with higher accuracy.

It is a figure which shows the general structure of the installed photovoltaic power generation system. It is a figure which shows the outline | summary of a structure of a solar cell array. It is a block diagram which shows the outline | summary of the failure diagnosis system which concerns on this invention. It is a flowchart which shows the outline | summary of the failure diagnosis method based on this invention. It is a figure which shows an example of the circuit diagram which gives the virtual model used for simulation. It is a figure which shows the change of the pseudo output signal with respect to a failure location. It is a figure which shows the change of the pseudo output signal with respect to the length of a cable. It is a block diagram which shows the outline | summary of the conventional failure diagnosis system.

  Hereinafter, embodiments of the present invention will be described in detail.

  First, a solar power generation system that is a target of failure diagnosis will be described. FIG. 1 is a diagram illustrating a general configuration of an installed photovoltaic power generation system. FIG. 2 is a diagram showing an outline of the configuration of the solar cell array.

  As shown in FIG. 1, the solar cell array 1 installed in a building is generally installed outdoors such as a roof. Usually, the solar cell array 1 has a plurality of solar cell strings 3 connected in parallel, and each solar cell string 3 has a plurality of solar cell modules 5 connected in series. The electricity generated by the solar cell array 1 flows through the cable 7 as a direct current and reaches the power conditioner 11 via the relay terminal box 9. The power conditioner 11 displays the output level of the solar cell array 1 and converts the direct current output from the solar cell array into an alternating current. The current converted into alternating current is consumed by the distribution board 13 in the electrical load 15 in the house, or sold to the commercial power grid 19 via the watt-hour meter 17 for buying and selling power. Each device is also connected by a cable 7.

  Here, as shown in FIG. 2, in order to stably increase the output value of the solar cell array 1, the solar cell modules 5 are usually connected in series by the same manufacturer, and a plurality of solar cells. The strings 3 are connected in parallel in the relay terminal box 9. In FIG. 2, a diode 21 is provided between the relay terminal box 9 and each solar cell string 3 in order to prevent backflow of current to the solar cell array 1.

  By switching the connection so that only one solar cell string is connected in the relay terminal box 9, the output level for each solar cell string can be displayed on the power conditioner 11, for example. Further, when applying the input signal to the solar cell string 3 subject to failure diagnosis, the connection is switched so that only the solar cell string 3 subject to failure diagnosis is connected at the relay terminal box 9, and the input signal is applied. An actual measurement signal that is a combined signal of the reflected signal reflected from the solar cell string 3 to be diagnosed and the input signal is actually measured. As shown in FIG. 1, the relay terminal box 9 is usually installed near the ground. Therefore, a series of operations relating to failure diagnosis such as switching of the solar cell string 3 to be failed, signal application, and actual measurement are performed near the ground. Therefore, the failure diagnosis method according to the invention of the present application is trouble diagnosis in the installation environment, but it is less troublesome than the method of failure diagnosis performed manually by climbing on the roof and in a place with poor scaffolding. This is much easier to implement. This point has an excellent effect in finding one failed solar cell module 5 from among the solar cell modules 5 electrically connected in a matrix. This is especially important for large-scale systems such as mega solar.

  Hereinafter, a failure diagnosis system according to the present invention will be described with reference to FIG. FIG. 3 is a block diagram showing an outline of the failure diagnosis system according to the present invention.

  The failure diagnosis system 27 according to the present invention includes input signal information such as a waveform of an input signal applied to the power conditioner 11 that is an output display means for displaying the output level of the solar cell array 1 and the solar cell string 3 to be diagnosed. The input signal determination unit 29 that is an input signal determination unit that determines the input signal, the input signal generation unit 23 that is the input signal generation unit that generates the input signal, the impedance of the input signal generation unit 23, and the impedance of the target circuit for fault diagnosis An impedance matching resistor 30 for matching the input signal generator 23, a cable 31 which is a connection means for connecting between the input signal generator 23 and a device such as the solar cell array 1 to be diagnosed, and an input signal applied to the solar cell string 3 to be diagnosed An actual measurement unit 25 that is an actual measurement unit that obtains an actual measurement signal that is a combined signal of the reflected signal and the input signal that are sometimes output; The same input signal as that applied to the solar cell string 3 to be diagnosed is applied to a virtual model that simulates the generator 23, the impedance matching resistor 30, the cable 31, and the solar cell string 3 for simulation. A simulator unit 33 that is a simulation unit that calculates a pseudo output signal that is an output signal in the case of being performed, a comparison unit 35 that is a comparison unit that compares the actually measured signal with the calculated pseudo output signal, and a comparison unit A parameter value is determined by assuming a failure rate part of the solar cell string and a precision rate calculation unit 37 that is a precision rate calculation unit that calculates a precision rate that is a degree of similarity between the actual measurement signal and the pseudo output signal from the output comparison result. A parameter determination unit 39 that is a parameter determination means for determining a virtual model and various databases It comprises a library 41 is a storage unit.

  The database of the library 41 includes a pseudo fault database 43 that is a pseudo fault data storage unit that stores model parameters corresponding to each fault location that is a candidate for a virtual model, and an actual measurement signal at the time of shipment of the solar cell string 3. A shipping database 45 that is shipping data storage means for storing and a failure database 47 that is a failure data storage means for storing combinations of failure contents of solar cell strings 3 measured in the past and measured signals are included. In the following description, it is assumed that the solar cell array 1 to be diagnosed has a plurality of solar cell strings 3 connected in parallel, and a normal string 49 having no failure and a failure string 51 having a failure are included therein. It shall be. In FIG. 3, the failure location in the failure string is indicated by “x”.

  The parameter determination unit 39 refers to the pseudo failure database 43 to determine a parameter value that does not depend on the installation environment, and includes a resistance value of the input signal generation unit that matches the impedance of the cable 31 and a parameter of the length of the cable 31. The virtual model is determined by determining parameter values depending on the installation environment. The comparison unit 35 calculates correction data by comparing the actual measurement signal from the normal string and the actual measurement signal at the time of shipment of the normal string included in the shipping database, and corrects the pseudo output signal using the correction data and then compares the correction data. Output the result. The precision ratio calculation unit 37 refers to the failure database 47 to determine a predetermined value related to the precision ratio, and if the precision ratio is less than the predetermined value, parameter determination is performed for a failure location different from the assumed failure location. Let part 39 assume.

  As the input signal generator 23, a pulse generator is used. The pulse generator may include an impedance matching resistor 30. Using an oscilloscope as the actual measurement unit 25, an actual measurement signal that is a combined signal of the input signal and the reflected signal from the solar cell string 3 to be diagnosed is actually measured. At this time, by adopting a configuration in which the input signal from the input signal generation unit 23 is also applied to the oscilloscope as a reference signal, it is possible to take a difference between the actual measurement signal and the input signal and extract a pure reflection signal. The input signal generated by the input signal generation unit 23 is applied to the diagnosis target solar cell string 3 via the impedance matching resistor 30 and the cable 31. The reflected signal from the solar cell string 3 to be diagnosed is actually measured by the actual measurement unit 25 as an actual measurement signal that is a combined signal with the input signal without passing through the impedance matching resistor 30 via the cable 31. Here, the reason why the reflected signal does not pass through the impedance matching resistor 30 is to prevent attenuation of the reflected wave signal.

  The simulator unit 33, the comparison unit 35, the relevance ratio calculation unit 37, the parameter determination unit 39, and the library 41 are collected by a computer as a single failure diagnosis device (for example, the simulator unit 33 uses simulation software such as SPICE). Realized).

  Below, the procedure of failure diagnosis according to the present invention will be described with reference to FIG. FIG. 4 is a flowchart showing an outline of the failure diagnosis method according to the present invention.

  In step ST1, based on the output level for each solar cell string 3 displayed on the power conditioner 11, the fault string 51 that is constantly powered down is determined. At this time, it is determined in consideration of the years of use of the solar cell string 3 to be diagnosed, the output level and the service life guaranteed by the manufacturer, and environmental conditions such as climate and sunshine conditions. In addition, since the solar cell string 1 that is the object of failure diagnosis is installed outdoors, even in the normal string 49 that is not actually in failure, the sunlight is blocked by the shade or the like and the output level is lowered. It should be noted that it may seem like this.

  After determining the normal string 49 and the failure string 51, in step ST2, the comparison unit 35, which is a comparison means, ships the actual string signal of the normal string 49 and the solar cell string of the same product stored in the shipping database 45. Compare the actual measurement signal of the hour. Even if the normal string 49 is not faulty, there is aging deterioration. By this comparison, correction data for reflecting the change in the actual measurement signal due to the aging deterioration in the pseudo output signal is obtained. This correction data is meaningful correction data only when the normal string 49 and the failure string 51 are the same type of solar cell strings. Usually, in the solar cell array 1, the same type and the same number of solar cell strings 3 are connected in parallel to obtain a desired output. Therefore, it is possible to obtain meaningful correction data under normal installation conditions. .

  In step ST3, the parameter determination unit 39, which is a parameter determination unit, assumes a failure location of the failure string 51. Subsequently, in step ST4, the parameter determination unit 39 selects a model corresponding to the assumed fault location with reference to the simulated fault database 43 in which the virtual model candidate model is stored, and determines the parameter value. Determine the virtual model. In addition, about the parameter depending on an installation environment, the value determined here is a standard value. In step ST5, the simulator unit 33, which is a simulation means, calculates a pseudo output signal in the determined virtual model.

  In step ST6, the comparison unit 35, which is a comparison unit, corrects the pseudo output signal obtained in step ST5 using the correction data obtained in step ST2, compares the actual measurement signal with the pseudo output signal, and compares them. Output the result. Subsequently, in step ST7, the relevance ratio calculating unit 37, which is a relevance ratio calculating means, calculates the relevance ratio from the comparison result obtained in step ST6.

  In step ST8, the matching rate calculation unit 37, which is a matching rate calculation means, refers to the failure database 47 and estimates that the failure point assumed by the parameter determination unit 39 is the failure point of the solar cell array that is the target of failure diagnosis. Therefore, the value of the precision to be satisfied is determined, and it is determined whether or not the precision calculated in step ST7 is greater than or equal to the determined precision. If the calculated relevance ratio is equal to or greater than the determined relevance ratio value, in step ST9, the relevance ratio calculation unit 37 determines that the failure location assumed by the parameter determination unit 39 is a failure location in the failure string 51 to be diagnosed. Presume that there is. If the calculated precision ratio is less than the determined precision ratio value, in step ST10, the precision ratio calculation section 37 causes the parameter determination section 39 to assume another failure location, and the calculated precision ratio is determined. The process after step ST4 is repeated until a failure location that is equal to or greater than the value of the matching rate is obtained.

  In the failure diagnosis according to the present invention, it is important to construct a virtual model for simulating the solar cell string 3 in the installation environment. Therefore, the virtual model will be described with reference to FIG.

  FIG. 5 is a diagram illustrating an example of a circuit diagram for providing a virtual model used for the simulation. FIG. 5A is a circuit diagram showing the entire virtual model. FIG. 5B is a circuit diagram showing a circuit represented by “string” in FIG. 5A in which the solar cell string 3 and the cable 31 are connected in series. FIG.5 (c) is a circuit diagram of the solar cell module 5 represented by "PV" in FIG.5 (b). FIG. 5D is a circuit diagram of the cable 31 represented by “cable” in FIG. FIG. 5A also shows a pulse generator as the input signal generator 23 and an impedance matching resistor 30. Since the cable 31 shown in FIG. 5D has a constant length and a cross-sectional area, it also has an impedance component indicated by a capacitor and a coil.

  Here, in the electric circuit, the signal is reflected when the impedance is not matched (Science University Dictionary 2nd edition (International Science Foundation, published by Maruzen Co., Ltd., published on February 28, 2005, p. 96). )reference). In FIG. 5A, the pulse generator, the impedance matching resistor 30, and the “string” are connected in this order, the left end of the pulse generator is grounded, and the right end of the “string” is open. If the right end of the “string” is open, the impedance of the right end of the “string” can be regarded as infinite. When a signal is applied to the normal string 49, reflection from each solar cell module 5 included in the normal string 49 and reflection from the opposite end to which the signal of the normal string 49 is applied occur. On the other hand, in the fault string 51, the impedance changes according to the fault content at the fault location, and impedance mismatch occurs. For this reason, when a signal is applied to the fault string 51, the solar cell module 5 at the fault location reflects a signal different from that of the normal string 49, and a reflected wave different from that of the normal string is observed.

  Therefore, even if the input signal generation unit 23 applies the same input signal to the solar cell string 3, the reflected signal obtained by the actual measurement unit 25 is applied when applied to the normal string 49 and applied to the failure string 51. The waveform will be different. In addition, the waveform of the reflected signal obtained by the actual measurement unit 25 is different if the failure location and the failure content are different. Such a difference in the waveform of the reflected signal is caused by a change in impedance due to a disconnection failure or deterioration depending on the type of failure in addition to the failure location. In the virtual model described above, since the change in impedance according to the failure location is modeled, it is possible to obtain a pseudo output signal simulating an actual measurement signal affected by the installation environment by performing simulation.

  FIG. 6 is a diagram illustrating a change in the pseudo output signal with respect to the failure location of the solar cell string. FIG. 6A is a diagram illustrating a graph of a pseudo output signal obtained from a virtual model of a normal string 49 having 12 solar cell modules 5. 6 (b), (c), and (d) are obtained from a virtual model of a fault string 51 that has 12 solar cell modules 5 and in which the ninth, tenth, and eleventh solar cell modules have failed, respectively. It is a figure which shows the produced | generated pseudo output signal. FIG. 6 (e) is a diagram collectively showing the graphs of FIGS. 6 (a) to (d). In FIG. 6, the vertical axis represents the signal strength of the actual measurement signal, and the horizontal axis represents the elapsed time in measurement. That is, each graph in FIG. 6 represents a change over time in the signal intensity of the actual measurement signal.

  As shown in FIG. 6, the pseudo output signal output varies depending on the presence or absence of a failure in the solar cell string 3 or the failure location. Therefore, the comparison unit 35 compares the actual measurement signal output from the solar cell string 3 to be diagnosed with the failure and the pseudo output signal, thereby diagnosing the presence or absence of the failure or the failure location.

  FIG. 7 is a diagram illustrating a change in the pseudo output signal with respect to the length of the cable. 7 (a), (b), (c), and (d) show a failure string 51 in which 12 solar cell modules 5 are provided and the 10th solar cell module fails, as in FIG. 6 (c). It is a figure which shows the pseudo output signal obtained from the virtual model made into the object of failure diagnosis and having the length of the cable respectively 25m, 50m, 75m, and 100m. FIG.7 (e) is a figure which shows the graph of Fig.7 (a) to (d) collectively.

  As shown in FIG. 7, it can be seen that the pseudo output signals obtained from the virtual models having different cable lengths have greatly different waveforms. In particular, the waveform of the harmonic component is greatly influenced by the length of the cable. From FIG. 6 and FIG. 7, it can be seen that differences in cable length can sometimes result in greater output signal waveform differences than failure location differences. Therefore, failure diagnosis in consideration of the installation environment of the solar cell array is necessary. At least a failure diagnosis is necessary in consideration of the length of the cable connected to the solar cell array.

  In the embodiment, the parameter value derived from the installation environment related to the characteristics (resistance value, capacitance value, inductance value, etc.) depending on the length of the installed cable, etc. is calculated by the comparison unit 35 using the correction data. This is reflected by correction performed on the pseudo output signal. However, the parameter value derived from the installation environment only needs to be finally reflected in the pseudo output signal, and instead of using the correction data, for example, the parameter determination unit 39 is derived from the installation environment at every failure diagnosis. The corrected virtual model may be determined by changing the value of the parameter to be changed from the standard value in the model stored in the simulated fault database.

  In the embodiment, the comparison unit 35 corrects the pseudo output signal using the correction data. However, the difference between the actual measurement signal at the time of shipment and the actual measurement signal of the normal string only needs to be reflected in the pseudo output signal. For example, the parameter determination unit 39 uses the correction data output from the comparison unit 35 to correct the parameter value. The corrected virtual model may be determined.

  Further, in the embodiment, the relevance ratio calculation unit 37 performs processing for causing the parameter determination unit 39 to sequentially assume different failure points until a failure point where the calculated relevance rate is equal to or greater than the determined relevance rate value is obtained. I decided to do it. However, it suffices if an assumed failure location that gives a matching rate exceeding a predetermined value can be estimated as a failure location of the failure string 51. For example, the matching rate calculation unit 37 causes the parameter determination unit 39 to assume another failure location. Instead of performing the process of step ST10 of 4, the parameter determination unit 39 may determine the virtual models in all possible cases, and the processes of steps ST4 to ST9 in FIG. 4 may be performed using each virtual model. .

  Further, in the embodiment, the failure to be diagnosed is a failure in the solar cell modules 5, but may be a disconnection failure between the solar cell modules 5.

DESCRIPTION OF SYMBOLS 1 Solar cell array 3 Solar cell string 5 Solar cell module 11 Power conditioner 23 Input signal generation part 25 Actual measurement part 27 Fault diagnosis system 29 Input signal determination part 31 Cable 33 Simulator part 35 Comparison part 37 Conformity rate calculation part 39 Parameter determination part 41 Library 43 Pseudo Failure Database 45 Factory Database 47 Failure Database 49 Normal String 51 Failure String 52 Failure Diagnosis Device

Claims (7)

A failure diagnosis system for estimating and diagnosing a failure location of a solar cell array having a solar cell string in which a plurality of solar cell modules are connected in series,
An input signal determining unit for determining a waveform of an input signal applied to the solar cell string;
An input signal generation unit that generates the input signal determined by the input signal determination unit;
An actual measurement unit that obtains an actual measurement signal that is an output signal when the input signal is applied to the solar cell string from the input signal generation unit via a cable;
A simulator unit that calculates a pseudo output signal that is an output signal when the input signal is applied to a virtual model that simulates the input signal generation unit, the cable, and the solar cell string;
A comparison unit for comparing the actually measured signal with the calculated pseudo output signal;
A matching rate calculation unit that calculates a matching rate, which is a degree of similarity between the actual measurement signal and the pseudo output signal, from the comparison result output by the comparison unit;
A library having a pseudo-failure database for storing parameters of a model corresponding to each failure location, which is a candidate for the virtual model;
The parameter value including the resistance value of the input signal generation unit and the cable length parameter matching the impedance of the cable is determined by referring to the pseudo-failure database assuming the failure location of the solar cell string. A parameter determining unit that determines the virtual model by
If there is an assumed failure location where the accuracy rate calculated by the accuracy rate calculation unit is equal to or greater than a predetermined value, the accuracy rate calculation unit estimates the assumed failure location as a failure location of the solar cell array, Fault diagnosis system. The solar cell array has a plurality of solar cell strings connected in parallel,
The library further comprises a shipping database that stores actual measurement signals at the time of shipment of solar cell strings,
The comparison unit compares an actual measurement signal from a normal string that does not have a failure among a plurality of solar cell strings included in the solar cell array and an actual measurement signal at the time of shipment of the normal string included in the shipping database. The fault diagnosis system according to claim 1, wherein correction data is calculated, the pseudo output signal is corrected using the correction data, and the comparison result is output. The library further includes a failure database that stores combinations of failure contents and measured signals of solar cell strings that have been measured in the past,
The precision calculation unit
Determining the predetermined value associated with the precision by referring to the failure database;
If the precision ratio is less than the predetermined value, the parameter determination unit is assumed to be a failure location different from the assumed failure location,
The fault diagnosis system according to claim 1 or 2. A failure diagnosis device that estimates and diagnoses a failure location of a solar cell array having a solar cell string in which a plurality of solar cell modules are connected in series,
When the input signal is applied to a virtual model simulating the input signal generation unit that applies the input signal to be generated to the solar cell array via a cable, the cable, and the solar cell string for simulation. A simulator unit for calculating a pseudo output signal which is an output signal;
A comparison unit that compares the pseudo output signal calculated by the simulator unit with an actual measurement signal that is an output signal when the input signal is applied to the solar cell string;
A matching rate calculation unit that calculates a matching rate, which is a degree of similarity between the actual measurement signal and the pseudo output signal, from the comparison result output by the comparison unit;
A library having a pseudo-failure database for storing parameters of a model corresponding to each failure location, which is a candidate for the virtual model;
The parameter value including the resistance value of the input signal generation unit and the cable length parameter matching the impedance of the cable is determined by referring to the pseudo-failure database assuming the failure location of the solar cell string. A parameter determining unit that determines the virtual model by
If there is an assumed failure location where the accuracy rate calculated by the accuracy rate calculation unit is equal to or greater than a predetermined value, the accuracy rate calculation unit estimates the assumed failure location as a failure location of the solar cell array, Fault diagnosis device. A failure diagnosis method in a failure diagnosis apparatus for estimating and diagnosing a failure location of a solar cell array having a solar cell string in which a plurality of solar cell modules are connected in series,
The failure diagnosis device is a candidate for a virtual model that simulates an input signal generation unit that applies an input signal to be generated to the solar cell array via a cable, the cable, and the solar cell string. It has a library with a pseudo-fault database that stores model parameters corresponding to the fault location,
The parameter determining means refers to the pseudo-failure database assuming a failure location of the solar cell string, and includes a resistance value of the input signal generation unit that matches the impedance of the cable and a parameter of the cable length. Determining the virtual model by determining the determined parameter value;
A simulation means calculating a pseudo output signal that is an output signal when the input signal is applied to the virtual model determined by the parameter determination means;
A comparison means comparing the pseudo output signal with an actual measurement signal that is an output signal when the input signal is applied to the solar cell string;
The precision ratio calculating means calculates a precision ratio that is the degree that the actual measurement signal and the pseudo output signal are similar from the comparison result output by the comparison means, and the assumed failure location where the precision ratio is equal to or greater than a predetermined value. And a step of estimating the assumed failure location as a failure location of the solar cell array if there is any.   A program for causing a computer to execute the fault diagnosis method according to claim 5.   A computer-readable recording medium on which the program according to claim 6 is recorded.