JP6545629B2 - Inspection apparatus and inspection method for solar power generation device - Google Patents

Description

  The present invention relates to an inspection apparatus and inspection method for a solar power generation device, and more particularly to an inspection device and inspection method suitable for inspection of a solar cell module used in a solar power generation device.

  In solar power generation, since the use of facilities, such as a solar power generation device in connection with power generation, is assumed for 20 years or more, the device and method of maintaining facilities are important. In Japan, there is a fixed-price purchase system as a subsidy system that determines the purchase price of energy, and if it is 10 KW or more, the purchase period is set to 20 years. Therefore, it is possible to shorten the recovery period of the initial investment in the facility and to increase the profit thereafter by keeping the facility maintenance cost required for the maintenance of the facility low during this purchase period. On the other hand, when appropriate maintenance is not performed, the amount of generated power (the amount of generated power) decreases, and a situation occurs in which the revenue from selling electricity decreases.

  The solar power generation apparatus is installed on a vast site so as to be able to receive sufficient sunlight to generate electric power from sunlight. In order to indicate that it is installed on a large site, a power plant using a solar power generation apparatus is referred to as a solar power generation site in the present specification.

  In order to perform maintenance of the solar power generation apparatus, a monitoring facility that constantly monitors the amount of generated power may be introduced at the solar power generation site. In this case, it is possible in principle to detect abnormality or deterioration of the solar power generation apparatus by the monitoring facility. However, even if an abnormality or deterioration is detected, it is not always determined that it is preferable to maintain it. For example, it is necessary to determine the necessity of maintenance based on the balance between the decrease in the power sale income caused by the decrease in the amount of generated power caused by abnormality or deterioration and the expense when performing maintenance. In this case, in order to estimate the expense required for maintenance, the presence or absence of abnormality or deterioration alone is insufficient, and it is required to appropriately determine the progress state of the abnormality or deterioration.

  Such an appropriate determination of the progress of abnormality or deterioration is not only required for routine maintenance. For example, also when deciding how to buy and sell a solar power generation site and how to handle a solar power generation site after the sale of electricity, it is required to appropriately determine the progress status of abnormality and deterioration. That is, after appropriately grasping the progress of abnormality or deterioration of the solar power generation apparatus, the trading price and the policy after the sale of electricity are determined, and a business is performed in which the transaction is performed. It is assumed that such a quotient will be made regularly from now on. That is, with the liberalization of power generation, the power generation business is not limited to the power company, and is opened to other than the power company. Therefore, trading of solar power generation sites will also be conducted. As long-term income is promised by the fixed tariff system, solar power generation sites will be treated as financial products like real estate etc. When thinking in this way, the main factor that determines the trading price that corresponds to the transaction price is the expected value of the revenue from power sales that can be expected in the future.

  Also, when the fixed price purchase period has passed, how to treat the photovoltaic power generation site will be determined by, for example, the selling price at that time and the expected amount of generated power. Since the amount of power generation that can be expected can be estimated by the progress of abnormality or deterioration of the solar power generation apparatus, when the fixed price purchase period has passed, the progress of abnormality or deterioration, and the solar power generation site Depending on the cost of removing the solar power generation equipment, the treatment of the solar power generation site will be determined.

  As described above, it is important to appropriately grasp the progress of abnormality and deterioration in the solar power generation apparatus, not only in routine maintenance but also in deciding the treatment method of the solar power generation site, and a technique therefor is necessary.

  The inspection apparatus of the solar cell used for a solar power generation device is described in patent document 1, for example.

International Publication WO2014 / 181388A1 International Publication WO2011 / 156527A1

  A solar power generation device includes a large number of solar cell (hereinafter also referred to as PV) modules. These PV modules are installed on the site of a photovoltaic power generation site, each of which receives sunlight and converts it into DC power. Each of the PV modules includes a plurality of solar cell elements (hereinafter, also referred to as silicon cells or simply cells) constituted by a semiconductor such as silicon, and a tab wiring connecting the plurality of silicon cells, and a plurality of silicon The cell and the tab wiring are sealed in one package.

  The PV module is installed at an outdoor place where sunlight is directly irradiated. Therefore, failure or deterioration is induced by long-term use. The following are known as factors causing failure or deterioration in the PV module. The irradiation of sunlight causes discoloration and deterioration of the resin material forming the package. The moisture that infiltrates mainly through the back surface resin sheet of the package causes corrosion in the metal wiring portion forming the electrodes and the like. In addition, stress such as wind pressure causes cracks in the silicon cell. In addition, breakage or the like occurs on the glass surface of the package due to throwing of stones by crows and the like.

  Besides the above-mentioned factors, the factor of deterioration is present, and the main factor of deterioration is an increase in wiring resistance caused by heat expansion and contraction due to a change in temperature of day and night. This is caused by the thermal expansion coefficient difference of the materials constituting the PV module. For example, although the tab wiring connecting between the silicon cells is mainly formed by the solder covered wiring, the junction between the tab wiring and the silicon cell peels off due to thermal expansion and contraction. In addition, in order to obtain good electrical contact between the tab wiring and the silicon cell, a junction between a silver paste electrode (bus bar electrode) and a current collecting electrode (finger electrode) formed on the silicon cell But it is broken by heat expansion and contraction. Due to the peeling, disconnection, etc., the PV module is deteriorated due to the temperature change, and the wiring resistance is increased.

  Maintenance of a solar power generation device is performed based on monitoring of the amount of generated power, but it is difficult to grasp the progress of deterioration in monitoring. By monitoring, it is possible to grasp the transition of the instantaneous value and the actual value of the generated energy, and to detect the presence or absence of abnormality or deterioration based on the grasped value. If an abnormality or deterioration is detected by this monitoring, visual observation or measurement of the electrical characteristics is performed, and a portion where the abnormality or deterioration is identified is identified based on the result, and maintenance is performed. As a technique used here, there are a sensing technique of generated electric energy and a curve trace technique of measuring characteristics of a solar cell. With such a technology, although it is possible to obtain an instantaneous value of the amount of generated power, it is not always easy to detect the presence or absence of abnormality or deterioration. This is because in the solar power generation apparatus, the amount of generated power changes significantly in a short time due to changes in the amount of solar radiation and the temperature, so that it is difficult to detect except when abnormality or deterioration greatly progresses.

  In addition, since the deterioration of the PV module caused by the above-described temperature change occurs in the PV module, it can not be determined visually.

  It is also conceivable to conduct an inspection of the PV module with a highly sensitive inspection method. Here, as a highly sensitive inspection method, for example, an inspection method using an infrared (hereinafter also referred to as IR) image or an electroluminescent (hereinafter also referred to as EL) image is used. These high sensitivity inspection methods are used, for example, when a manufacturer providing a PV module inspects a PV module indoors before providing the PV module (shipping process).

  It is also conceivable to use such a highly sensitive inspection method for inspection for maintenance outdoors such as at a photovoltaic power generation site. By using such a highly sensitive inspection method, highly sensitive deterioration detection is possible, but it is still difficult to know the progress of deterioration.

  An example of an inspection method using an IR image will be described as a high sensitivity inspection method. Here, a case where an infrared thermography camera (hereinafter also referred to as an IR camera) is used to acquire an IR image will be described. In the PV module, when the wiring resistance is increased due to abnormality or deterioration, the amount of heat generation in the area (location) where the wiring resistance is increased will be increased. By using an IR camera, by acquiring an IR image in the PV module, it is possible to detect heat generation due to abnormality or deterioration with high sensitivity. However, it is difficult to identify the point of deterioration, and it is also difficult to estimate the cause of the deterioration. For example, the detection accuracy of a temperature change that can be detected by an IR camera is generally less than 1K (Kelvin) and high sensitivity. However, in the case of using an IR camera for practical maintenance outdoors, it is common for the observation object to be extensive and the temperature distribution in the thermal image to have a complicated appearance. In addition, the generated heat is diffused from the heat generation location, and along with this, the infrared light emission location is expanded. Therefore, it becomes difficult to specify, for example, one or more heat generation points. As a result, in the inspection, at the stage where the temperature change can be caught, it becomes difficult to identify the deteriorated portion. Since it is difficult to identify the location of degradation, it is also difficult to estimate the cause of degradation based on the location of degradation.

  Next, the case where the inspection method using an EL image is used outdoors will be described. Although the EL image gives a lot of information, it is not always easy to interpret the information, and it is particularly difficult to discuss it in relation to the output deterioration. In addition, in order to generate EL, it is necessary to flow a current in the opposite direction to that at the time of power generation. Therefore, it is difficult to stop power generation and connect a power supply. Therefore, it is practical to use the inspection method using the EL image in the inspection process before shipping the PV module.

  As exemplified above, when the PV module is degraded, the wiring resistance increases and the heat generation amount increases. That is, deterioration or abnormality basically involves heat generation. Therefore, the inventor considered that it is desirable to use a highly sensitive detection of heat generation and a technology capable of identifying the cause thereof as an inspection device of a solar power generation device. Moreover, the inventor considered that lock-in thermography was suitable as such a technique. Lock-in thermography is described, for example, in Patent Document 2. At present, it is practically used when the object to be inspected is small, such as failure analysis of LSI (semiconductor integrated circuit device), but for large objects such as PV modules, it is at the research level. It remains in use.

  In lock-in thermography, an object (sample) is periodically heated, and an IR image is acquired in synchronization with the period to obtain a thermal image of the object. By performing data processing using the periodicity of a plurality of IR images acquired periodically, it is possible to detect only periodic heat generation at an object with extremely high sensitivity. In this case, the detection sensitivity reaches mK (millikelvin). Moreover, since the periodic change of IR image acquired in time series is used for analysis, it becomes possible to exclude the influence of ambient temperature (environmental temperature). Also, even if the temperature around the heat generation location changes due to heat diffusion, the temperature change of the heat generation location itself is larger, so the temperature of the heat generation location is selected by selecting the heat generation cycle earlier than the heat diffusion time scale. Changes can be discerned from temperature changes around it. For this reason, it is possible to identify the heat generation point extremely locally. By identifying the heat generation location, it becomes easy to estimate the heat generation cause. Further, since it is possible to specify the heat generation location, it is also possible to grasp, for example, the number of heat generation locations, and it is also suitable for diagnosing the progress of deterioration. However, according to the study of the present inventor, it has been found that there are several problems in using the lock-in thermographic technique at a photovoltaic site.

  That is, in the lock-in thermography, in order to cause the object to generate heat periodically, the object is periodically energized or periodically irradiated with infrared light. In the case of applying to a solar power generation site, it is necessary to perform periodical energization or light irradiation including infrared rays to one PV module in a state where power generation is stopped, and to acquire an IR image. Alternatively, if an IR image is to be acquired during power generation operation, periodical energization or light irradiation is similarly performed on a unit called a string in which about 15 to about 20 PV modules are connected in series. To obtain an IR image. Even in this case, in the case where periodical energization is used, it is necessary to connect a power source performing periodical energization to the string in a state where power generation is temporarily stopped. If the PV module or string is periodically energized, it is necessary to resume power generation after acquiring the IR image. In addition, since a large number of PV modules need to be energized, a large-capacity power source is required as an inspection apparatus.

  On the other hand, it is not necessary to stop power generation if periodic light irradiation is used instead of periodical energization. However, in this case, it is necessary to irradiate uniform light (for example, infrared rays) to a large area formed by a plurality of PV modules. Therefore, the inspection apparatus becomes a large and expensive apparatus.

  As described above, when applying lock-in thermography at a photovoltaic power generation site, it is necessary to once stop power generation and connect a power supply that performs periodic energization, and a large-capacity power supply is required. Become. Alternatively, there is a problem that light must be irradiated using a large-scale inspection apparatus.

  In addition, although patent document 1 has shown the disconnection abnormality location identification technique which used the magnetic sensor, the test | inspection apparatus of the PV module which used heat detection is not described.

  An object of the present invention is to provide an inspection device capable of inspecting a solar power generation device with a simple configuration.

  The above and other objects and novel features of the present invention will be apparent from the description of the present specification and the accompanying drawings.

  The outline of typical ones of the inventions disclosed in the present application will be briefly described as follows.

  According to one embodiment, an inspection device of a solar power generation device including a plurality of solar cell modules and a conversion device for converting power generated by the plurality of solar cell modules into commercial power is a plurality of solar cell modules Heat generation is detected in response to a trigger signal, a cycle of power change of a plurality of solar cell modules caused by conversion by a photographing device and a conversion device is detected, and a trigger signal is formed in synchronization with the detected cycle A trigger signal forming device is provided. The inspection of the solar power generation device is performed on the basis of the heat generation images of the plurality of solar cell modules captured in synchronization with the cycle of the power change.

  When converting direct current power generated by the solar cell module into commercial power by the conversion device, the direct current power of the solar cell module changes at a cycle corresponding to a predetermined frequency of the conversion device. This change in power spreads to the solar cell module, and the solar cell module generates heat in accordance with the cycle of the change in power. Therefore, the solar cell module generates heat periodically in synchronization with the predetermined frequency of the conversion device. The period of the power change is detected, and the heat generation image in the solar cell module is photographed by the photographing device by the trigger signal synchronized with the detected period, whereby the heat generation image having periodicity synchronized with the periodic heat generation in the solar cell module It is possible to obtain In this case, since the power change of the solar cell module is used as the power for heat generation, it is not necessary to stop the power generation, and a power supply for periodically energizing to generate heat of the solar module is not required. Therefore, it becomes possible to inspect a solar power generation device with a simple inspection device.

  Further, according to one embodiment, an inspection device of a solar power generation device provided with a plurality of solar cell modules and a conversion device for converting power generated by the plurality of solar cell modules into commercial power is a plurality of solar power generation devices. Trigger signal forming device for forming a trigger signal in synchronization with a cycle of power change of a plurality of solar cell modules generated by conversion by a conversion device and an imaging device for capturing heat in response to a trigger signal in a battery module Equipped with The inspection of the solar power generation device is performed on the basis of the heat generation images of the plurality of solar cell modules captured in synchronization with the cycle of the power change.

  The solar cell module generates heat periodically in synchronization with a predetermined frequency of the conversion device. With the trigger signal synchronized with this cycle, it is possible to obtain a heat generation image having periodicity synchronized with periodic heat generation in the solar cell module by photographing the heat generation image in the solar cell module by the photographing device. Also in this case, since the power change of the solar cell module is used as the power for heat generation, it is not necessary to stop the power generation, and a power supply for periodically energizing to generate heat of the solar module is not required. Therefore, it becomes possible to inspect a solar power generation device with a simple inspection device.

  Furthermore, according to one embodiment, a method of inspecting a photovoltaic power generation device including a plurality of solar cell modules and a conversion device for converting the power generated by the plurality of solar cell modules into commercial power is performed by the conversion device It has a forming step of forming a trigger signal synchronized with the cycle of the power change of the plurality of solar cell modules generated by the conversion, and a photographing step of photographing heat generation in the plurality of solar cell modules by the photographing device in synchronization with the trigger signal. .

  In the forming step, the trigger signal synchronized with the cycle of the power change of the solar cell module is formed, and in the photographing step, the heat generation of the solar cell module is photographed in synchronization with the trigger signal. As a result, without stopping the power generation, it is possible to easily inspect the solar power generation device without performing periodic energization in order to heat the solar light module.

  The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

  It is possible to provide an inspection device capable of inspecting a solar power generation device with a simple configuration.

FIG. 1 is a block diagram showing a configuration of a solar power generation apparatus according to Embodiment 1. It is a block diagram which shows the structure of a solar cell array. It is a top view which shows the structure of a solar cell module. It is a circuit diagram showing composition of a power conditioner. It is a wave form diagram which shows the current waveform which flows through direct-current power wiring. FIG. 1 is a block diagram showing a configuration of an inspection apparatus according to Embodiment 1; (A)-(D) are waveform diagrams which show operation | movement of the test | inspection apparatus concerning Embodiment 1. FIG. (A)-(D) are waveform diagrams which show operation | movement of the test | inspection apparatus concerning the modification 1 of Embodiment 1. FIG. (A)-(D) are waveform diagrams which show operation | movement of the test | inspection apparatus concerning the modification 2 of Embodiment 1. FIG. (A)-(D) are waveform diagrams which show operation | movement of the test | inspection apparatus concerning the modification 2 of Embodiment 1. FIG. FIG. 7 is a block diagram showing a configuration of an inspection apparatus according to Embodiment 2. (A)-(E) are waveform diagrams which show operation | movement of the test | inspection apparatus concerning Embodiment 2. FIG.

  Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Note that, in all the drawings for describing the embodiments, in principle, the same reference numerals are given to the same parts, and the repetitive description thereof will be omitted in principle.

Embodiment 1
<Configuration of solar power generation device>
FIG. 1 is a block diagram showing the configuration of the solar power generation apparatus according to the first embodiment. In FIG. 1, reference numeral 100 denotes a solar power generation device, and ACA denotes a system to which commercial power generated by the solar power generation device is supplied. The grid ACA includes power reception facilities of a plurality of customers, and the commercial power generated by the photovoltaic power generation apparatus 100 is supplied to the plurality of power reception facilities in the grid ACA.

  The solar power generation device 100 includes a plurality of PV arrays 101-1 to 101-n, a power conditioning system (Power Conditioning System, hereinafter, also referred to as a PCS device or conversion device) PCS, and an isolation transformer TT. In addition, there also exists a solar power generation device which is not provided with the insulation transformer, and the presence or absence is irrelevant to the present invention.

  The plurality of PV arrays 101-1 to 101-n are not particularly limited, but have the same configuration as one another, and are connected in parallel to the PCS device PCS via the DC power line DCL. The PV arrays 101-1 to 101-n have the same configuration, so the configuration will be described using the PV array 101-1 as a representative. The PV array 101-1 includes an assembly of PV modules 102-0 to 102-nn which will be described later with reference to FIGS. 2 and 3. In the first embodiment, each of the PV modules 102-00 to 102-nn is arranged in a matrix at the site of the photovoltaic power generation site so as to receive sunlight. Each of the PV modules 102-00-102-nn generates DC power from the irradiated sunlight. The DC power generated by each PV module is supplied to the PCS device PCS via the DC power line DCL.

  Similarly to the PV array 101-1, each of the remaining PV arrays 101-2 to 101-n also generates DC power generated by the PV modules included in each PV array through the DC power wiring DCL. , PCS apparatus PCS power supply. Thereby, DC power is supplied to the PCS device PCS in parallel from each of the PV arrays 101-1 to 101-n.

  Although the configuration of the PCS device PCS will be described later with reference to FIG. 4, the PCS device PCS converts DC power supplied via the DC power wiring DCL into commercial power to convert AC power wiring (feed line ) Supply power to ACL1. Commercial power is AC power having a predetermined frequency, for example, in Japan, AC power having a frequency of 50 Hz or 60 Hz. Although not particularly limited, in the first embodiment, AC power line ACL1 is connected to isolation transformer TT, and insulation transformer TT is connected to system ACA via AC power line (feed line) ACL2. That is, commercial power is supplied from the AC electrode wiring ACL1 to the AC power wiring ACL2 and is further supplied to the system ACA in a state where the space between the AC power wirings ACL1 and ACL2 is electrically isolated by the isolation transformer TT.

  The generated DC power is converted by the PCS device PCS into AC power having a predetermined frequency (for example, 50 Hz or 60 Hz). When the solar power generation apparatus 100 is considered to be configured by a DC circuit that processes DC power and an AC circuit that processes AC power, the DC circuits include a plurality of PV arrays connected by DC power wiring DCL. It can be considered as being constituted by 101-1 to 101-n and a part of the PCS apparatus PCS. In this case, the AC circuit is configured by an insulation transformer TT, a part of the PCS apparatus PCS connected to the insulation transformer TT by an AC power line ACL1, and a system ACA connected to the insulation transformer TT by an AC power line ACL2. Can be regarded as In the first embodiment, an example in which the insulating transformer TT is installed is shown, but the insulating transformer TT may not be installed.

  Thereby, the DC power generated by the PV arrays 101-1 to 101-n is converted to commercial power which is AC power by the PCS device PCS, and the commercial power is supplied to a plurality of power receiving facilities in the grid ACA. It will be

<Configuration of PV array>
Next, the configuration of the PV arrays 101-1 to 101-n will be described. FIG. 2 is a block diagram showing the configuration of the PV array. Here, the configuration of the PV array 101-1 shown in FIG. 1 is shown in FIG.

  As described in FIG. 1, the PV array 101-1 includes PV modules 102-00 to 102-nn arranged in a matrix. Although the DC power wiring DCL is shown as a single wiring in FIG. 1, DC power wiring (hereinafter also referred to as positive power wiring) DCL (+) for supplying DC power of the positive electrode and DC power of the negative electrode are supplied. A DC power wiring (hereinafter, also referred to as a negative power wiring) DCL (−) is provided. The PV modules 102-00 to 102-nn constituting the PV array 101-1 are connected between the positive power wiring DCL (+) and the negative power wiring DCL (−).

  Although not particularly limited, in FIG. 2, a plurality of PV modules (for example, 102-00 to 102-0 n and 102-n to 102-nn) arranged in the same row have positive power wiring DCL (+) and negative power. The wirings DCL (−) are connected in series with each other. In the present specification, such PV modules connected in series are referred to as a string PVS. Since the PV array 101-1 has 0 to n-1 columns, the strings PVS-0 to n-1 columns configured by the PV modules 102-00 to 102-0 n arranged in 0 columns It will have n strings PVS up to the string PVS-n constituted by the arranged PV modules 102-n to 102-nn. In FIG. 2, a string PVS-n constituted by PV modules 102-n to 102-nn connected in series with one another is clearly indicated by a broken line. In other words, the strings PVS-0 to PVS-n are connected in parallel to each other between the positive power wiring DCL (+) and the negative power wiring DCL (-), and as a collection of strings PVS, a PVS array 101-1 is comprised.

  The number of PV modules constituting the string PVS or / and the number of strings connected in parallel are determined for each photovoltaic power generation site. As will be described later using FIG. 3, each of the PV modules 102-00 to 102-nn has a plurality of silicon cells connected in series with one another. Each of these silicon cells generates DC power by receiving sunlight. As an example, each of the PV modules 102-00 to 102-nn comprises 60 pieces of 150 mm square polysilicon cells which are most representative for industrial use. In this case, the open circuit voltage of each PV module is approximately 36 to 38 V, and the short circuit current is 8 to 9 A.

  The number of such PV modules (for example, 14 to 16) determined in accordance with the system design is connected in series to form one string PVS. In this case, the open circuit voltage of the string PVS is approximately 500 to 600 V, and the short circuit current is 8 to 9 A. When operating the string at an operation point that outputs the maximum power, the string PVS outputs a current of about 8 A at a voltage of about 400 to 500 V. Such a string PVS is connected in parallel between the positive power wiring DCL (+) and the negative power wiring DCL (−) as shown in FIG. As a result, 8 A × parallel number of currents are supplied to the PCS device PCS via the DC power line DCL.

  Although not particularly limited, in the first embodiment, a string PVS in which 14 PV modules are connected in series is connected in parallel, and will be described as an example of a photovoltaic power generation site with an output power of 50 kW.

  Although the PV array 101-1 has been described as an example, each of the other PV arrays 101-2 to 101-n has the same configuration, so the description will be omitted.

<Configuration of PV module>
Next, the configuration of the PV modules 102-00 to 102-nn will be described. The configurations of the PV modules 102-00 to 102-nn have the same configuration as each other, so only one PV module will be described here. The reference numeral of the PV module to be described is 102. FIG. 3 is a plan view showing the configuration of the PV module 102. As shown in FIG. As described above, the PV module 102 includes a plurality of solar cell elements (silicon cells) and tab interconnections connecting the plurality of silicon cells, and the plurality of silicon cells and the tab interconnections are combined into one package. It is sealed.

  Although not particularly limited, in the first embodiment, in the PV module 102, 60 silicon cells are arranged in a matrix of 10 rows × 6 columns. Because they are arranged in a matrix, it can be considered that an array is configured by 60 silicon cells. FIG. 3 is a plan view of the surface irradiated with sunlight as viewed from the direction of the irradiation of sunlight. In FIG. 3, each of PVC-0 to PVC-59 shows a silicon cell. In the figure, in order to prevent the drawing from being complicated, only the silicon cells arranged on the left and right (first and sixth columns) of the array are denoted by reference numerals PVC-0 to PVC-9 and reference numeral PVC-50. -PVC-59 is attached. Since the silicon cells PVC-0 to PVC-59 have the same configuration, they will be described here by taking the silicon cell PVC-0 as a representative.

  The silicon cell PVC-0 has a main surface and a back surface opposite to the main surface, and for example, a first silicon layer and a second silicon layer having different conductivity types are stacked between the main surface and the back surface. ing. In this case, the main surface of the first silicon layer is the main surface of the silicon cell PVC-0, the back surface of the first silicon layer is stacked on the main surface of the second silicon layer, and the back surface of the second silicon layer is silicon It becomes the back of cell PVC-0. A plurality of current collection electrodes (finger electrodes) are formed in parallel to each other on the main surface and the back surface of the silicon cell PVC-0. Moreover, the bus-bar electrode (silver paste electrode) which connects between several finger electrodes is formed in the main surface of silicon cell PVC-0.

  In FIG. 3, the main surfaces of the silicon cells PVC-0 to PVC-59 are visible. The silicon cell PVC-0 will be described. In FIG. 3, on the main surface of the silicon cell PVC-0, finger electrodes extending in the lateral direction and arranged in parallel in the longitudinal direction are formed. In FIG. 3, the finger electrodes formed on the main surface are shown by broken lines. In addition, in order to avoid that a drawing becomes complexity, in FIG. 3, the code | symbol FGD is attached | subjected only with respect to the finger electrode arrange | positioned most upper side and lower side. Further, in FIG. 3, the bus bar electrodes BBD formed on the main surface of the silicon cell PVC-0 extend in the longitudinal direction and are formed in parallel to each other in the lateral direction. The bus bar electrode BBD and the finger electrode FGD are connected at the intersections thereof.

  An electrode is generally formed on the entire surface of the back surface of the silicon cell PVC-0. The other silicon cells PVC-1 to PVC59 are also similar to the silicon cell PVC-0.

  In FIG. 3, each of TBD-1 to TBD-7 indicates a tab wiring. In the first embodiment, silicon cells PVC-0 to PVC-59 are connected in series between tab interconnections TBD-1 and TBD-7. That is, the tab interconnections arranged in parallel in the longitudinal direction from the tab interconnection TBD-1 are connected through solder on the bus bar electrodes BBD formed on the main surface of the silicon cell PVC-0. A tab wiring connected to the back surface electrode of -0 is wired on the main surface of silicon cell PVC-1 through between silicon cells PVC0 and PVC1, and is connected to the bus bar electrode BBD formed on PVC-1 via a solder ing. The tab wiring connected to the back surface of silicon cell PVC-1 via solder is routed to the main surface of silicon cell PVC-2 through the space between silicon cells PVC1 and PVC2, and on the main surface of silicon cell PVC-2 It connects to the bus-bar electrode BBD formed in these through solder.

  Thereafter, bus bar electrodes BBD formed on the respective main surfaces of silicon cells PVC-3 to PVC-59 are similarly connected to electrodes formed on the back surface of silicon cells connected in series via tab wiring. ing. Tab wires TBD-2 to TBD-6 are used to connect between tab wires connected on bus bar electrodes formed in silicon cells. The back electrode of silicon cell PVC-50 and tab wiring TBD-7 are connected. Since silicon cells PVC-0 to PVC-59 are connected in series, DC power generated by each silicon cell is added and is generated between tab interconnections TBD-1 and TBD-7. .

  The tab wires TBD-1 and TBD-7 are two electrode cables corresponding to a positive electrode and a negative electrode disposed outside the module via an electrode extraction mechanism generally referred to as a junction box disposed on the back surface of the PV module. And each connected. The DC power generated in the PV module is taken out through the electrode cable. For example, when the PV module shown in FIG. 3 is the PV module 102-00 shown in FIG. 2, for example, the tab wiring TBD-1 is connected to the positive electrode power wiring DCL (+) through the electrode cable. Further, the tab wiring TBD-7 is connected to the tab wiring TBD-1 in the PV module 102-01 (not shown in FIG. 2) disposed next to the PV module 102-00 through the electrode cable. Thus, the silicon cells in the PV modules 102-00 to 102-0 n arranged in the string PVS-0 are connected in series between the positive power wiring DCL (+) and the negative power wiring DCL (-). Connected to The same is true for other strings.

  The DC power generated between the positive power wiring DCL (+) and the negative power wiring DCL (−) is input to the PCS device PCS. The PCS device PCS has an inverter circuit, and converts the input DC power into commercial power (AC power) by this inverter circuit. Since the DC power wiring DCL and the AC power wiring ACL1 are electrically connected via the inverter circuit, ripple noise synchronized with the operating frequency of the inverter circuit is also superimposed on the DC power wiring DCL.

<Configuration of PCS Device>
FIG. 4 is a circuit diagram showing a basic configuration of the PCS apparatus PCS. The PCS apparatus PCS comprises a plurality of circuit blocks, but in FIG. 4 only the portion of the inverter circuit that converts DC power to commercial power is shown by the broken line IVC.

  The inverter circuit IVC includes an oscillation circuit OSC and insulated gate bipolar transistors (hereinafter, also referred to as IGBTs or simply transistors) T1 to T4. Although AC power line ACL1 is shown by one power supply line in FIG. 1, AC power line ACL1 is shown as a pair of AC power lines ACL1-A and ACL1-B in FIG. .

  Transistor T1 is connected between positive power wiring DCL (+) and AC power wiring ACL1-A, and transistor T2 is connected between negative power wiring DCL (-) and AC power wiring ACL1-A. There is. Transistor T3 is connected between positive power wiring DCL (+) and AC power wiring ACL 1-B, and transistor T4 is connected between negative power wiring DCL (-) and AC power wiring ACL 1-B. It is done. A diode may be connected in series or in parallel to each IGBT depending on the control mode of the inverter circuit.

  When the diodes are connected in series, diodes are connected between the collectors of T1 and T3 (in the figure, T1-C, T3-C) and DCL (+) in the direction in which current flows into the IGBT. Ru. Further, diodes are respectively connected between the emitters of T2 and T4 (in the figure, T2-E and T4-E) and DCL (-) so that current flows from the IGBT.

  On the other hand, when the diodes are connected in parallel, from the collector side between the emitter (T1-E to T4-E in the drawing) and the collector (T1-C to T4-C) of each IGBT The diodes are connected in such a direction that current does not flow to the emitter side. Furthermore, a reactor or a capacitor for smoothing the output may be connected to ACL1 in accordance with the control mode of the inverter circuit. These diodes and reactors are omitted in FIG. The oscillation circuit OSC is a pulse width modulation (PWM) from a reference sine wave having the same frequency as the frequency of the commercial power supply and a modulation wave having a frequency higher than this (hereinafter also referred to as an inverter frequency at the operating frequency of the inverter circuit). Generate a PWM signal for control. The oscillation circuit OSC further forms clock signals IC1, IC2, / IC1 and / IC2 for driving the IGBT which is a switching element of the inverter from the PWM signal. Here, the clock signal / IC1 is a clock signal obtained by inverting the phase of the clock signal IC1, and the clock signal / IC2 is a clock signal obtained by inverting the phase of the clock signal IC2.

  The transistors (switches) T1 and T2 are switch-controlled to be alternately turned on by the clock signals IC1 and / IC1 formed by the oscillation circuit OSC. Further, the transistors (switches) T3 and T4 are switch-controlled to be alternately turned on by the clock signals IC2 and / IC2 generated by the oscillation circuit OSC. As a result, in synchronization with clock signals IC1 and / IC1 having an inverter frequency, AC power line ACL1-A is electrically connected to positive power line DCL (+) or negative power line DCL via transistor T1 or T2. It will be connected to-). Similarly, in synchronization with clock signals IC2 and / IC2 having an inverter frequency, AC power line ACL1-B is electrically connected to positive power line DCL (+) or negative power line DCL via transistor T3 or T4. It will be connected to-).

  Thereby, for example, DC power supplied to the positive electrode power wiring DCL (+) is transferred to the AC power wiring ACL1-A or ACL1-B via the transistor T1 or T3. At this time, DC power supplied to the negative electrode power wiring DCL (−) is transmitted to the AC power wiring ACL1-A or ACL1-B via the transistor T2 or T4. As a result, DC power is converted into AC power in synchronization with the inverter frequency and supplied to the AC power lines ACL1-A and ACL1-B.

  Since the transistors T1 to T4 are turned on in synchronization with the inverter frequency, the DC power lines DCL (DCL (+) and DCL (-)) are synchronized with the inverter frequency to change the AC power line ACL1 (ACL1-A). , ACL 1-B), and ripple noise synchronized with the inverter frequency is superimposed on the DC power lines DCL (DCL (+), DCL (-)).

  In order to confirm that the ripple noise is superimposed on the DC power line DCL, the current at the node indicated by the symbol A in FIG. 2 was measured in the positive electrode power line DCL (+) of the DC power line DCL. FIG. 5 is a waveform diagram showing a current waveform of node A shown in FIG. In the figure, the horizontal axis indicates time, and the vertical axis indicates current.

  This measurement is performed by sandwiching the portion of the node A of the positive electrode power wiring DCL (+) with the measurement portion of the clamp ammeter. At this time, the solar power generation device continues the power generation and is not stopped. The inverter frequency in the inverter circuit IVC is, for example, a frequency of several kHz, and is a stable frequency in order to form commercial power of an accurate frequency. The clamp ammeter is selected to follow a relatively high frequency capable of measuring the inverter frequency (several kHz).

  Referring to FIG. 5, it can be seen that the current at node A changes periodically and changes due to ripple noise synchronized to the inverter frequency. From the period of the current waveform shown in FIG. 5, it is understood that the inverter frequency in the inverter circuit IVC of the PCS device PCS used at the measured solar power generation site is 4 kHz.

<Inspection device>
FIG. 6 is a block diagram showing the configuration of the inspection apparatus according to the first embodiment. In the same figure, a part of the solar power generation device 100 shown in FIG. 1 is also shown for convenience of explanation. That is, in FIG. 6, 101-1 to 101-n, PCS, DCL and ACL1 correspond to PV array 101-1 to 101-n, PCS device PCS, DC power wiring DCL and AC power wiring ACL1 shown in FIG. Each corresponds. Since these have already been described, in principle, the description will be omitted.

  In FIG. 6, reference numeral 600 denotes an inspection apparatus for inspecting the solar power generation apparatus 100. The inspection apparatus 600 includes a clamp current meter KDT, a computer PC, an IR camera (infrared thermographic camera, imaging device) IRC, and input / output boards IOB1 and IOB2.

  The clamp ammeter KDT is disposed so as to sandwich the DC power wiring DCL. The DC power wiring DCL includes the positive power wiring DCL (+) and the negative power wiring DCL (-) as shown in FIG. 2, but in the first embodiment, it is the same as that described in FIG. In addition, the clamp ammeter KDT sandwiches a predetermined portion of the positive electrode power wiring DCL (+). When the solar power generation device 100 is generating power, ripple noise synchronized with the inverter frequency of the inverter circuit IVC of the PCS device PCS is superimposed on the positive electrode power wiring DCL (+). The clamp ammeter KDT outputs a detection current IDT synchronized with the change in current in the positive electrode power wiring DCL (+).

  The input / output board IOB1 receives the detection current IDT which is an analog signal, converts it into a digital signal, and supplies it to the computer PC. Although not particularly limited, the input / output board IOB1 has a digital filter. Only the high frequency component of the input detection current IDT is extracted by this digital filter, and a pulse signal corresponding to the extracted high frequency component is supplied to the computer PC as a digital signal corresponding to the detection current IDT. By extracting the high frequency component from the detection current IDT, it becomes possible to extract the change of the current in the detection current IDT. Thus, the pulse signal supplied from the input / output board IOB1 to the computer PC is synchronized with the current change measured by the clamp ammeter KDT, and the frequency of the pulse signal corresponds to the frequency of the current change measured by the clamp ammeter KDT. It will be done. That is, the frequency of the pulse signal supplied from the input / output board IOB1 to the computer PC corresponds to the inverter frequency in the PCS device PCS.

  The computer PC supplies the start signal of the frequency corresponding to the pulse signal supplied from the input / output board IOB1 to the input / output board IOB2. The input / output board IOB2 corresponds to the frequency of the supplied start signal, and supplies a pulse signal matched to the level of the trigger input of the IR camera IRC to the IR camera IRC as a trigger signal TGS.

  The IR camera IRC captures images in the PV arrays 101-1 to 101-n in response to the trigger signal TGS. That is, in synchronization with the cycle of the trigger signal TGS, the IR camera IRC captures a heat generation image in the PV arrays 101-1 to 101-n. Data on the heat generation image in the PV arrays 101-1 to 101-n obtained by imaging is supplied to the computer PC. The computer PC processes the data concerning the heat generation image, and based on the data obtained by the processing, checks the presence / absence and progress of abnormality / deterioration in the solar power generation apparatus 100. In the first embodiment, PV arrays 101-1 to 101-n in solar power generation apparatus 100 are particularly inspected by inspection apparatus 600. The input / output boards IOB1 and IOB2 may share one input / output board, or the functions of the input / output boards IOB1 and IOB2 may be provided in the computer PC.

  As described above, when the PV modules constituting the PV array deteriorate, the wiring resistance increases and the amount of heat generation increases. That is, deterioration or abnormality basically involves heat generation.

  According to the first embodiment, it is possible to inspect (diagnose) the progress of deterioration of the PV module at the solar power generation site without using the power generation, using the heat generation of the PV module.

  In solar power generation, power is supplied to the grid (power grid) ACA in order to use the obtained DC power. At that time, DC power is converted to AC power of commercial frequency by the PCS device PCS. This conversion is performed by the switching operation of the inverter circuit IVC connected between the DC circuit and the AC circuit at high speed. Therefore, the direct current circuit electrically connected to the inverter circuit IVC is affected by the switching operation. This influence appears as superposition of ripple noise having an inverter frequency for performing switching operation. Since the outputs of a large number of PV modules are collected in the PCS apparatus PCS to handle large power, ripple noise superimposed on the DC power wiring DCL from the inverter circuit IVC also becomes large.

  For example, when a silicon-based PV module with an output of about 250 W is operating at the optimum operating point, the current flowing to the string in which the PV modules are connected in series is 7 to 8 A in fine weather, but the ripple noise to be superimposed is It may reach about 1A. At this time, since the voltage between terminals of the PV module is about 30 V, a power fluctuation (power change or DC power change) of about 30 W is generated, which is 10% of the output of the PV module. This power change (power fluctuation, DC power change) causes the PV module to operate with a deviation from the optimum operating point, and as a result, of the energy of sunlight incident on the PV module, the energy of the power fluctuation due to ripple noise The rate of conversion to electricity and heat will change periodically. The power change generated by the ripple noise generated by the conversion operation by the PCS device PCS becomes the power change (DC power change) of the PV module. In this case, the cycle of the power change of the PV module is synchronized with the cycle of the ripple noise and has the same frequency.

  If two PV modules with large thermal energy of 30 W per PV module and a calorific value difference of 30 W in steady state are aligned, it is possible to sufficiently detect and identify the PV modules that generate heat with an IR camera It is. Since the heat generation fluctuates in synchronization with the inverter frequency of the inverter circuit IVC, it is extremely difficult to detect the heat generation amount difference in an IR camera which takes pictures regardless of the inverter frequency of the inverter circuit IVC.

  The ripple noise superimposed by the inverter circuit IVC matches the inverter frequency of the inverter circuit IVC. Therefore, as shown in FIG. 5, the frequency of the ripple noise is stable. In the first embodiment, this ripple noise is detected on the DC circuit side and used as a trigger signal for imaging with the IR camera IRC, and inspection is performed based on the data of the captured heat image. That is, ripple noise detected on the DC circuit side is used as a synchronization signal for lock-in thermography. Thus, periodic heat generation in the PV module caused by the ripple noise can be detected by lock-in thermography using the frequency of the ripple noise as a synchronization signal.

  It is not necessary to stop power generation at the photovoltaic site as the power changes caused by ripple noise are used as power to periodically heat the PV module. That is, it is possible to conduct an inspection using a lock-in thermography technique while power generation is continued. In order to do this, in the first embodiment, the trigger signal TGS is generated from the ripple noise superimposed on the DC circuit of the photovoltaic power generation site, and is input as a synchronization signal to the IR camera IRC. Get an image. A lock-in thermographic image can be obtained by data processing of the plurality of IR images obtained according to a conventional lock-in thermographic technique.

<< IR Camera Configuration >>
The IR camera IRC according to the first embodiment captures an infrared image in response to the trigger signal TGS. The IR camera IRC includes a trigger input terminal to which a trigger signal is supplied, a sensor, and a processing circuit that processes an image signal from the sensor. For example, in response to the trigger signal TGS supplied to the trigger input terminal rising from the low level to the high level, the sensor supplies an image signal corresponding to the infrared image being illuminated at that time to the processing circuit The image signal is processed by the processing circuit and supplied to the computer PC as an infrared image.

  In the IR camera IRC, time is required to capture an infrared signal above the sensor's minimum sensitivity. In this specification, this time is referred to as a time constant of the IR camera IRC. In addition, it is also necessary to transfer the signal acquired by the sensor as data for each pixel constituting an infrared image from the IR camera IRC to the computer PC. The time for transferring the captured signal as data for each pixel is referred to herein as data transfer time (Integration time) of the IR camera IRC. It is desirable that the time constant of the IR camera IRC used in the first embodiment be shorter than the period of the ripple noise frequency described above. In addition, an imaging function for imaging in synchronization with the supplied trigger signal is required. Furthermore, it is desirable that the frame rate of the IR camera IRC be high.

  The sensors (infrared sensors) included in the IR camera IRC can be roughly classified into a quantum type (cooled type) and a thermal type (uncooled type). The thermal type detects a temperature change due to the irradiated infrared light. An example of this thermal sensor is a sensor (bolometer) using amorphous silicon. On the other hand, the quantum type detects an electrical phenomenon caused by the irradiated infrared light. An example of a quantum type sensor is a sensor using a compound semiconductor. Since an IR camera using a thermal sensor is required to detect a temperature change caused by infrared irradiation, the time for capturing a signal, that is, the time constant of the IR camera, is longer than that of a quantum sensor. Become. Therefore, in the first embodiment, in order to shorten the time constant of the IR camera IRC, it is desirable to use an IR camera provided with a quantum type sensor. However, an IR camera using a thermal sensor may be used as long as it operates following the frequency required for lock-in thermography.

<Operation of inspection device>
FIG. 7 is a waveform diagram showing the operation of the inspection apparatus 600 shown in FIG. In FIG. 7, the horizontal axis indicates time. Here, FIG. 7 (A) shows the current in the DC power wiring measured by the clamp ammeter KDT. Since this current changes in accordance with ripple noise, it is shown as a ripple noise waveform in FIG. 7 (A). The vertical axis in FIG. 7A indicates the current. In FIG. 7A, IS indicates the current value (DC current) of the DC power wiring DCL when ripple noise is not superimposed. By superimposing the ripple noise, the current value in the DC power wiring DCL increases or decreases in synchronization with the ripple noise, using the current value IS as a reference value (hereinafter also referred to as a reference value IS). In FIG. 7A, the peak value when the current value increases is shown as IS-U, and the peak value when the current value decreases is shown as IS-D. The increase and decrease of the current in the DC power wiring DCL periodically occur in synchronization with the ripple noise. In FIG. 7A, the period is indicated as T with respect to the periodic change of current in the DC power wiring DCL.

  FIG. 7B shows the waveform of the trigger signal TGS outputted from the input / output board IOB2, and the vertical axis shows a voltage. Further, FIG. 7C schematically shows a time constant of the IR camera IRC, and FIG. 7D schematically shows a data transfer time of the IR camera IRC.

  When the current in the DC power wiring DCL changes due to ripple noise, the detection current IDT from the clamp ammeter KDT changes as shown in FIG. 7A. When the detected current IDT becomes higher than the reference value IS at time t0, a detection signal is output from the input / output board IOB1. Based on this detection signal, the computer PC and the input / output board IOB2 start the trigger signal TGS from the low level. Change to high level.

  In response to the trigger signal TGS supplied to the trigger input terminal changing from the low level to the high level, the IR camera IRC starts imaging from time t1 slightly delayed from time t0. The acquisition of infrared light by the sensor is continuously performed also for the time constant of IR camera IRC (time between time t1 and time t2). At the timing (time t2) when the time constant has elapsed, the data of the pixel is transferred from the sensor to the computer PC. That is, the pixel data is supplied to the computer PC in the data transfer period between time t2 and time t3 in FIG. 7D.

  In the example of the waveform shown in FIG. 7, the above-described operation is repeated each time the current in the DC power wiring DCL becomes higher than the reference value IS. As a result, an infrared image captured in synchronization with the period T of the ripple noise is supplied to the computer PC. That is, a plurality of infrared images synchronized in time with ripple noise and supplied in time series are supplied to the computer PC. By examining a plurality of infrared images supplied in time series in the computer PC, it is possible to inspect the PV module.

  In this case, the PV module is supplied with a current that changes with respect to the reference value IS. Therefore, inspection can be performed without providing a power source that causes the PV module to generate heat periodically.

  When the time constant of the IR camera IRC is longer than one cycle of ripple noise, the infrared image captured by the IR camera IRC becomes an image of a PV module generated by multiple cycles of ripple noise. Therefore, the time constant of the IR camera IRC is required to be shorter than one cycle of ripple noise. In the first embodiment, as described above, the time constant of the IR camera IRC is made short by using the IR camera provided with the quantum type sensor.

  Although it is desirable that the data transfer time of the IR camera IRC is also short, it is not essential that it be shorter than one ripple noise cycle. For example, a storage circuit is provided in the IR camera IRC, and an infrared image captured by the sensor during a time constant period is sequentially stored in the storage circuit. The infrared image stored in the storage circuit is later supplied to the computer PC, and the inspection is performed by the computer PC. By doing this, it is not necessary to sequentially supply the infrared image captured by the sensor to the computer PC, and it is not essential to make the data transfer time of the IR camera IRC shorter than one ripple noise cycle. .

<Modification 1>
FIG. 7 shows the case where an infrared image is taken by the IR camera IRC each time ripple noise rises. That is, the case is shown where an infrared image is taken in the entire period of ripple noise. The frame rate of the IR camera IRC is generally one to two digits lower than the frequency of ripple noise. In this case, for example, the frequency of the trigger signal TGS is set by the computer PC to be lower than the frame rate of the IR camera IRC. In the first modification, the frequency of the trigger signal TGS is made lower than the frame rate of the IR camera IRC.

  FIG. 8 is a waveform chart showing the operation of the inspection apparatus 600 according to the first modification. FIG. 8A is a waveform diagram showing a ripple noise waveform as in FIG. 7A. Since FIG. 8A is the same as FIG. 7A, the description is omitted. FIG. 8 (B) shows the waveform of the trigger signal TGS formed by the computer PC and the input / output board IOB2, FIG. 8 (C) schematically shows a time constant, and FIG. 8 (D) shows data transfer The time is shown schematically.

  In the first modification, the computer PC forms a trigger signal every two periods of ripple noise. That is, in FIG. 8, the trigger signal TGS is formed in the first period (0 to 1T) of ripple noise and the third period (2T to 3T), and the computer PC is in the second period (1T to 2T). The trigger signal TGS is not formed. This makes it possible to form a trigger signal of a frequency lower than the frame rate of the IR camera IRC, and it is possible to periodically acquire an infrared image.

  Here, an example in which the trigger signal is formed every two cycles has been described, but it is possible to further extend the cycle where the trigger signal is formed by increasing the second cycle (1T to 2T) shown in FIG. It is. Even in this case, the trigger signal is synchronized with the ripple noise.

  Further, although it has been described that the cycle of the trigger signal TGS is made longer by the computer PC, the present invention is not limited to this. For example, the cycle of the trigger signal TGS may be extended by the input / output boards IOB1 and IOB2.

<Modification 2>
When using lock-in thermography techniques, it is desirable to acquire multiple infrared images during one cycle of changing the heat to be inspected. It is because it becomes possible to reduce the noise which does not have periodicity by superimposing the some infrared image acquired in this way.

  FIG. 9 is a waveform diagram showing waveforms in the case of acquiring a plurality of infrared images in one cycle of ripple noise. In FIG. 9, the horizontal axis indicates time. FIG. 9A is a waveform diagram showing a ripple noise waveform as in FIG. 7A. Unlike FIG. 7 (A), for convenience of explanation, FIG. 9 (A) shows a waveform of one cycle T of ripple noise. In one cycle T of the ripple noise, the computer PC and the input / output board IOB2 form a plurality of trigger signals TGS.

  For example, in one cycle of ripple noise, six trigger signals that differ in phase by 30 degrees are formed as shown in FIG. 9B. For each trigger signal, an infrared image at that time is captured during the time constant period shown in FIG. 9C. The captured infrared image is transferred to the computer PC at the data transfer time shown in FIG. 9 (D). This makes it possible to acquire a plurality of infrared images in the period of one period T of ripple noise, and has periodicity by performing processing of superposing these on the computer PC based on the lock-in thermographic method. It becomes possible to remove no noise.

  As described in the first modification, when the frame rate of the IR camera IRC is lower than the ripple noise frequency, as shown in FIG. 9, multiple infrared images are acquired in one ripple noise period. It will be difficult to do. That is, when the frame rate of the IR camera IRC can not follow the frequency of the ripple noise, it becomes difficult to acquire a plurality of infrared images during one cycle of the ripple noise. In this case, a plurality of infrared images at different timings may be acquired in a plurality of periods of ripple noise, and the plurality of acquired infrared images may be data equivalent to a plurality of infrared images in one period of ripple noise. .

  FIG. 10 is a waveform diagram showing an operation when the frame rate of the IR camera IRC can not follow the frequency of the ripple noise. Also in FIG. 10, the horizontal axis indicates time. FIG. 10A shows a ripple noise waveform as in FIG. 7A. 10 (B) shows the waveform of the trigger signal, FIG. 10 (C) schematically shows the time constant, and FIG. 10 (D) schematically shows the data transfer time.

  In the second modification, the computer PC performs processing for sequentially adding a predetermined delay time to the rise timing of ripple noise indicated by the detection signal from the input / output board IOB1, and adding the predetermined delay time. At the obtained timing, trigger signals are sequentially formed.

  Here, in order to facilitate the description, the case where the period of the ripple noise and the period of the frame rate of the IR camera IRC are the same will be described.

  When a predetermined delay time is not added by the computer, a trigger signal formed by computer PC and input / output board IOB2 is formed at each timing of time t0, time 1T, and time 2T in FIG. 10 (B). It will be On the other hand, in the second modification, the predetermined delay time a is sequentially added. That is, after the trigger signal is formed at the timing of time t0, the trigger signal is formed at the timing (1T + a) obtained by adding a predetermined delay time a to the time 1T. Next, a trigger signal is formed at a timing (2T + 2a) obtained by adding one cycle T and a predetermined delay time a to the timing (1T + a).

  Thus, while the infrared image is acquired by the sensor between time t1 and t2 in the first cycle, the delay time a is taken as the offset time in the second cycle, and only the offset time (delay time a) The infrared image is acquired by the sensor between the delayed times t1 and t2. In the third cycle, the delay time 2a is an offset time, and an infrared image is acquired by the sensor between times t1 and t2 delayed by this offset time. That is, an infrared image when heat is generated due to the ripple noise can be obtained at a timing shifted by each offset time with the predetermined delay time as the offset. A plurality of (three in FIG. 10) infrared images thus obtained are processed as equivalent to a plurality of infrared images acquired in a period of ripple noise of one cycle. This makes it possible to reduce non-periodic noise.

  For convenience of explanation, it is assumed that the period of ripple noise and the period of frame rate of IR camera IRC are the same, but if the periods are different, the delay time is offset as well, and the infrared rays of the timing when the offset time is offset It is possible to acquire an image, and it is possible to reduce non-periodic noise.

  Further, although an example in which the predetermined delay time is added by the computer PC has been described, the present invention is not limited to this. For example, predetermined delay times may be added by the input / output boards IOB1 and IOB2.

  Furthermore, instead of adding a predetermined delay time, as described in the first modification, a cycle that does not generate a trigger signal may be added (introduced). For example, the period in which the trigger signal is not generated may be sequentially increased. In this case, in the repeated ripple noise, a period that does not generate a trigger signal is added such that a period that generates a trigger signal exists at mutually different timings.

  Although the case where the frame rate of the IR camera IRC is lower than the frequency of the ripple noise has been described, the present invention is not limited to this. For example, when the frame rate of the IR camera IRC is higher than the frequency of ripple noise, and the number of infrared images to be acquired in one cycle of ripple noise is increased, a plurality of ripple noise cycles are generated at different timings. Make it possible to acquire an infrared image. A plurality of infrared images acquired in this manner may be equivalently treated as an infrared image in ripple noise of one cycle.

  The infrared image data transferred to the computer PC is processed in the computer PC, but this data processing may be performed in the same manner as in the usual lock-in thermography. The process by lock-in thermography is described, for example, in patent document 2.

  The data transferred to the computer PC corresponds to an infrared image observed when the PV module generates heat in synchronization with the ripple noise at a timing synchronized with the ripple noise.

  In the first embodiment, the period of ripple noise is detected, and imaging of an infrared image is performed by the trigger signal TGS having a period having a predetermined relationship with the period of ripple noise. The period of the ripple noise and the period of the trigger signal TGS are not required to be the same, as it is only necessary to synchronize the heat generation of the PV module due to the ripple noise and the imaging of the infrared image. That is, FIG. 7 shows the case where the period of the ripple noise and the period of the trigger signal TGS are the same, but as shown in FIGS. 8 to 10, the period of the pull noise and the period of the trigger signal have a predetermined relationship. Just do it. In other words, a timing signal of a cycle corresponding to the cycle of ripple noise may be used as the trigger signal TGS, or a signal based on this timing signal may be formed and used as the trigger signal TGS.

Second Embodiment
FIG. 11 is a block diagram showing an inspection device of a solar power generation apparatus according to a second embodiment. In Embodiment 1, the example which forms the trigger signal of IR camera IRC by measuring the ripple noise which is superimposed on DC power wiring DCL and transmitted to the DC circuit has been described. The ripple noise is generated by the oscillator circuit OSC described in FIG. In order to stabilize the frequency of the commercial power, the inverter frequency of the clock signal formed by the oscillator circuit OSC is set to a stable predetermined frequency. Therefore, the frequency of the ripple noise is also a stable frequency. In the second embodiment, the frequency of the ripple noise is measured in advance. The frequency of this pre-measured ripple noise is used to form the trigger signal of the IR camera IRC. Therefore, in the second embodiment, when inspecting a solar power generation apparatus, it is not necessary to measure the ripple noise transmitted to the direct current circuit.

  In FIG. 11, 600-2 has shown the test | inspection apparatus which test | inspects a solar power generation device. Similarly to FIG. 6, FIG. 11 also shows a part of the solar power generation apparatus. That is, in FIG. 11, 101-1 to 101-n, PCS, DCL and ACL1 correspond to PV arrays 101-1 to 101-n, PCS device PCS, DC power wiring DCL and AC power wiring ACL1 shown in FIG. Each corresponds. Since these have already been described, in principle, the description will be omitted.

  The inspection apparatus 600-2 includes a computer PC, an input / output board IOB2, and an IR camera IRC.

  The frequency of ripple noise measured in advance is set in the computer PC. For example, at a photovoltaic power generation site, the frequency of ripple noise supplied to the DC circuit is measured. This measures the current flowing through the DC power line DCL, for example, by a clamp ammeter KDT as shown in FIG. The result of the measurement is recorded in the logger. One period of ripple noise is determined by the logger, and the frequency of the ripple noise is determined from the determined period of time, and set in the computer PC. The configuration for measuring the frequency of ripple noise is not limited to this. For example, if the logger has a Fourier transform function or the like, the result of the measurement may be transformed by the Fourier transform function to obtain the ripple noise frequency.

  The computer PC forms a start signal synchronized with the set frequency of ripple noise. The activation signal is adjusted by the input / output board IOB2 to match the IR camera IRC, and is output as the trigger signal TGS from the input / output board IOB2. In response to the trigger signal TGS, the IR camera IRC captures infrared images in the plurality of PV modules, and supplies data obtained by the capturing to the computer PC. The computer PC performs data processing on the supplied data. Based on the result of data processing, inspection of a photovoltaic power generation device (PV module) is performed.

  In the second embodiment, although not particularly limited, the computer PC measures timing according to a program and forms a start signal at timing according to the set ripple noise frequency. Therefore, it is possible to easily adjust the frequency of the start signal and add a delay time by changing the program without preparing new hardware.

  Of course, the trigger signal TGS may be generated without using the computer PC and the input / output board IOB2. For example, a trigger generation device that operates independently of the solar power generation device may be used. In this case, the trigger generation device may be, for example, a function generator that generates a trigger signal having the same frequency as ripple noise, or a pulse generation circuit that is self-made by self-creating a pulse generation circuit that generates such a trigger signal. May constitute a trigger generation device. If the power supply for operating the function generator can be secured, the configuration using the function generator is the easiest method. In addition, if the pulse generation circuit operates with a battery, it is possible to achieve miniaturization.

  FIG. 12 is a waveform diagram showing the operation of the inspection apparatus according to the second embodiment. Also in FIG. 12, the horizontal axis indicates time. FIG. 12A shows the current in the DC power wiring DCL, as in FIG. 7A. The ripple noise is superimposed on the reference value IS, and the current flowing through the DC power wiring DCL changes periodically due to the ripple noise. Each of FIG. 12 (B) to FIG. 12 (E) shows the waveform of the trigger signal TGS. In the second embodiment, trigger signal TGS is generated regardless of ripple noise that appears as a change in current in DC power line DCL. Therefore, the phase difference between the ripple noise and the trigger signal can not be controlled. That is, in the first embodiment, since the ripple noise is detected and the trigger signal is formed, it is possible to control the phase difference between the ripple noise and the trigger signal, but in the second embodiment, It is difficult to control this phase difference.

  Therefore, in the second embodiment, trigger signals having various phases are formed as shown in FIG. 12 (B) to FIG. 12 (E) depending on the timing at which the inspection device 600-2 starts the inspection. It will be done. For example, in FIG. 12B, as in FIG. 7B, an infrared image at that time is captured at a timing when ripple noise rises. On the other hand, in FIG. 12C, the trigger signal is generated at the timing when the ripple noise amplitude is close to the positive peak value (IS-U), and the infrared image at that time is taken. Further, in FIG. 12D, the trigger signal is generated at the timing when the amplitude of the ripple noise is near the negative peak value (IS-U), and the infrared image at that time is taken. Further, in FIG. 12E, the trigger signal is generated at the timing when the amplitude of the ripple noise is near the reference value (IS), and the infrared image at that time is taken. That is, it will be photographed at an arbitrary timing.

  However, from the viewpoint of lock-in thermography, it is possible to acquire an infrared image at any timing, and no particular problem occurs. That is, at any timing, the PV module generates heat (generation of heat) or dissipation due to ripple noise in the DC power wiring DCL at that time, and an infrared image at that time is acquired become. Also, if imaging is performed again, it is possible to change the phase difference between the trigger signal and the ripple noise, so that imaging may be performed again as needed. Furthermore, as described in FIG. 10, a predetermined delay time may be added to the trigger signal. Thus, it is possible to change the phase difference between the trigger signal and the ripple noise by adding a delay time. In this case, unlike in FIG. 10, the predetermined delay time to be added may be variable.

  The same modification as that of the first modification and the second modification of the first embodiment can be performed on the inspection apparatus 600-2 according to the second embodiment. For example, the frequency of the trigger signal may be set lower than the frequency of the ripple noise as described in FIG. 8 based on the magnitude relationship between the frame rate and the frequency of the ripple noise. Further, as described with reference to FIG. 10, when a predetermined delay time is set to the trigger signal, infrared images are acquired at different time positions in a cycle over a plurality of cycles of ripple noise, and a plurality of images are captured within one cycle. It may be treated as equivalent data. However, in the second embodiment, since the trigger signal is generated independently instead of using the ripple noise as a reference, it is necessary to determine the period in which the trigger signal is not generated or to insert a delay time. .

  Similar to the first embodiment, the obtained data can be subjected to data processing in accordance with ordinary lock-in thermography to obtain a lock-in thermographic image.

Third Embodiment
In the third embodiment, inspection of a PV module is performed at a photovoltaic power generation site using an unmanned aerial vehicle (hereinafter also referred to as a UAV). Since the solar power generation site is a vast site, it is desirable to conduct an inspection using a UAV.

  As described in the second embodiment, the trigger signal having the same frequency as the ripple noise can be independently formed without measuring the current flowing through the DC power line DCL in the solar power generation device. By means of this independently formed trigger signal, it is possible to capture an infrared image by means of the IR camera IRC.

  In the third embodiment, the computer PC, the input / output board IOB2, the IR camera IRC and the rechargeable battery for supplying power to these devices shown in FIG. 11 are mounted on the UAV.

  The maximum loadable weight (payload) of the UAV is, for example, 6 kg. As a computer PC, for example, a lightweight node personal computer is about 1 kg. The IR camera IRC has, for example, an auto-focusing function, and a camera capable of photographing at a frame rate of 100 Hz is about 3.8 kg. As a rechargeable battery, one having a capacity of 150 Wh and about 1.17 kg exists. Assuming that the power consumption of the IR camera IRC is 30 W, if the rechargeable battery is fully charged, shooting for about 30 minutes can be expected. The input / output board IOB2 is configured of, for example, a card type input / output device attachable to a notebook computer. Since the card type input / output devices are lightweight, even if they are mounted on the UAV, it is possible to make the weight not exceed the payload. The UAV mounted with these devices is made to fly above the solar power generation site, and while flying, as described in the second embodiment, an infrared image in the PV module is taken by the IR camera IRC. Note that the computer PC can also be regarded as a control device because the imaging of the IR camera IRC is controlled by the activation signal generated by the computer PC.

  In addition, when a stable flight can not be expected in terms of weight, for example, the rechargeable battery is changed to a lightweight one. The acquisition of the infrared image may be performed as in the second embodiment. A plurality of acquired infrared images can be taken into a notebook computer, and a desired infrared image can be obtained in the same manner as ordinary lock-in thermography. Also, after the flight, the IR camera IRC may be recovered and data processing may be performed.

  In this way, lock-in thermographic techniques can be applied from above the solar power generation site to determine the progress of degradation of the PV module.

  Although the clamp ammeter has been described as an example of detecting the current in the DC power wiring DCL, the present invention is not limited to this. As a configuration for detecting the current, for example, a current detection sensor using a Hall element, a current detection sensor of a current transformer type, or the like can be used.

  The PV module generates DC power, and the DC power line DCL transmits DC power. Therefore, it can be considered that a DC circuit is configured by a plurality of PV modules and DC power lines. In this case, since the AC power lines ACL1 and ACL2 transmit AC power, it can be considered that an AC circuit is configured by the AC power lines ACL1 and ACL2. When considered in this way, the PCS device can be considered as a power converter that connects a DC circuit to an AC circuit.

  When considered in this way, one embodiment is an inspection device of a solar power generation device including a DC circuit composed of a plurality of solar cell modules and a power conversion device for connecting the DC circuit to an AC circuit. It is disclosed. In this case, the inspection apparatus is a Hall element or a current transformer type current detection sensor (for example, clamp ammeter KDT) for detecting a direct current of the solar power generation apparatus, and a pulse signal (trigger signal) using the output of the current detection sensor as an input. A pulse signal generator (for example, a computer PC and input / output boards IOB1 and IOB2) for generating the image signal, and an image pickup device (IR) having an infrared detector as an image pickup element (sensor) that operates with the pulse signal (trigger signal) as an imaging trigger Camera IRC). The periodical power fluctuation generated in the DC circuit with the operation of the power conversion device is detected by the current detection sensor, and the pulse signal output from the pulse signal generation device is photographed in synchronization with the periodic power fluctuation as a photographing trigger. The inspection of the photovoltaic device is performed based on the infrared image of the solar cell module.

  In addition, when the inspection apparatus described in the embodiment is viewed from the viewpoint of the inspection method, in the embodiment, a converter that converts power generated by a plurality of PV modules and a plurality of PV modules into commercial power ( The inspection method of the solar power generation device provided with PCS apparatus PCS) will be disclosed. In this case, the inspection method includes a forming step of forming the trigger signal TGS and a photographing step of photographing. Here, the forming step forms the trigger signal TGS synchronized with the cycle of the power change of the plurality of PV modules 102-00 to 102-nn caused by the conversion by the conversion device (PCS device PCS). Further, in the photographing process, the heat generation in the plurality of PV modules 1020-0 to 102-nn is photographed by the photographing device (IR camera IRC) in synchronization with the trigger signal TGS.

  From the point of view of the inspection method, the forming step can be regarded as comprising a detecting step of detecting the cycle of the power change of the PV module. Further, in the third embodiment, the inspection method is to be implemented in an unmanned aerial vehicle.

  Although the embodiment has described an example in which the computer PC and the input / output board IOB2 are used as a trigger signal forming device for forming the trigger signal TGS supplied to the IR camera IRC, the present invention is not limited to this.

  As mentioned above, although the invention made by the present inventor was concretely explained based on an embodiment, the present invention is not limited to the above-mentioned embodiment, and can be variously changed in the range which does not deviate from the gist. Needless to say.

100 Photovoltaic power generation device 101-1 to 101-n Solar cell array 102-00 to 102-nn Solar cell module 600 Inspection device ACA System ACL1, ACL2 AC power wiring DCL DC power wiring IOB1, IOB2 I / O board IRC IR camera KDT Clamp ammeter PC computer PCS power conditioner TGS trigger signal

Claims (6)

An inspection device of a solar power generation device, comprising: a plurality of solar cell modules; and a converter for converting power generated by the plurality of solar cell modules into commercial power,
The conversion device is connected between a DC power wiring connected to the plurality of solar cell modules and an AC power wiring for supplying the commercial power, and is switch-controlled at a predetermined cycle to thereby control the power. A plurality of switches for converting to the commercial power;
The inspection device of the solar power generation device is
A photographing device for photographing heat generation in the plurality of solar cell modules in response to a trigger signal;
A trigger that detects a cycle of a change in power of the plurality of solar cell modules based on a change in a signal generated in the DC power wiring by conversion by the conversion device, and forms the trigger signal in synchronization with the detected cycle. A signal forming device,
Equipped with
The inspection apparatus of the solar power generation device which test | inspects the said solar power generation device based on the heat_generation | fever image in these solar cell modules imaged synchronizing with the period of the said electric power change. In the inspection apparatus of the solar power generation device according to claim 1,
The inspection apparatus for solar power generation device, wherein the trigger signal forming device forms a signal having the same cycle as the detected cycle as the trigger signal. In the inspection apparatus of the solar power generation device according to claim 1,
The inspection apparatus for a solar power generation device, wherein the trigger signal forming device forms a signal of a cycle having a predetermined relationship with a detected cycle as the trigger signal. In the inspection apparatus of the solar power generation device according to claim 1,
The heat generation in the plurality of solar cell modules due to the periodic power change corresponds to the periodic heat generation of the sample in the lock-in thermography, and the photography of the heat generation image in response to the trigger signal is the infrared image in the lock-in thermography An inspection device for solar power generation equipment, equivalent to acquisition of An inspection method of a solar power generation device, comprising: a plurality of solar cell modules; and a conversion device for converting power generated by the plurality of solar cell modules into commercial power,
The conversion device is connected between a DC power wiring connected to the plurality of solar cell modules and an AC power wiring for supplying the commercial power, and is switch-controlled at a predetermined cycle to thereby control the power. A plurality of switches for converting to the commercial power;
The inspection method of the solar power generation device is
Forming the trigger signal synchronized with the cycle of the power change of the plurality of solar cell modules based on the change of the signal generated in the direct current power wiring by the conversion by the conversion device;
An imaging step of imaging heat generated by the plurality of solar cell modules by an imaging device in synchronization with the formed trigger signal;
And an inspection method. In the inspection method according to claim 5 ,
The inspection method, wherein the forming step includes a detecting step of detecting a cycle of power change of the plurality of solar cell modules.

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