CN112653393B - Control method and device for photovoltaic system IV diagnosis - Google Patents
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Abstract
The invention provides a control method and a device for photovoltaic system IV diagnosis, which relate to the technical field of photovoltaic power generation and comprise the following steps: starting IV scanning, and acquiring historical power generation data and a primary IV scanning result of the inverter; determining an occluded area occluded by a cloud layer generated by a photovoltaic system according to the historical power generation data and the primary IV scanning result, and determining a non-occluded time period of the occluded area; performing IV scanning on the occluded region again during the non-occlusion period. According to the method, the analysis of the historical power generation data of the inverter is combined with the IV diagnosis result, the shadow distribution of the cloud layer in the photovoltaic system is accurately analyzed, the cloud layer shielding influence is avoided according to the determined cloud layer movement characteristic, the IV fault diagnosis efficiency and accuracy are improved, the IV diagnosis can be applied in regions and time intervals, the misdiagnosis problem caused by irradiance change of the IV diagnosis in multi-cloud weather is solved, and the application scene is expanded.
Description
Technical Field
The invention relates to the technical field of photovoltaic power generation, in particular to a control method and device for photovoltaic system IV diagnosis.
Background
Renewable energy has gained widespread attention around the world, against the background of the global energy crisis and the growing severity of ecological environmental issues. Solar energy is one of the most critical clean energy sources because of its inexhaustible advantages. The solar photovoltaic power generation technology is one of important ways for effectively utilizing solar energy, so that the solar photovoltaic power generation technology has great theoretical significance and market value for the research of the photovoltaic power generation technology.
When building a photovoltaic power plant, the photovoltaic cells are generally operated in strings, parallel strings or a combination of strings and parallel strings to form a photovoltaic string. The output characteristic of the photovoltaic string is related to factors such as illumination intensity and outside temperature. The photovoltaic string can run in various external environments for a long time after being installed, and the problems of material aging, component failure and the like can be caused to the photovoltaic string under the conditions of wind, rain, sunshine and external artificial damage, so that the photovoltaic string breaks down to cause power generation accidents. Therefore, accurate fault detection is required to be performed on the photovoltaic string to remove the faults so as to ensure safe and stable operation of the photovoltaic power generation system.
The existing fault diagnosis of the photovoltaic string mainly comprises methods of infrared thermal Imaging (IR), IV scanning, EL, time domain reflection, capacitance to ground and the like. Currently, IR thermal imaging and IV scanning are the most widely used. Wherein, IR thermal imaging needs to take a picture with infrared camera, then discerns unusual heating element, and the cost is higher. The IV scanning technology directly utilizes the MPPT scanning function of the inverter to obtain the IV curve of the string group, diagnosis is carried out according to the fault characteristics of the IV curve, and cost is hardly increased. However, in the prior art, the IV fault diagnosis based on the inverter requires the IV scan in a clear weather. In cloudy weather, misdiagnosis is caused due to irradiance difference at different positions of a photovoltaic system, and the accuracy of normal IV fault diagnosis is affected.
Disclosure of Invention
To achieve at least some of the above objects, the present invention provides a method for controlling photovoltaic system IV diagnosis, which includes:
starting IV scanning, and acquiring historical power generation data and a primary IV scanning result of the inverter;
determining an occluded area occluded by a cloud layer generated by the photovoltaic system according to the historical power generation data and the primary IV scanning result, and determining a non-occluded time period of the occluded area;
performing IV scanning on the occluded region again during the non-occlusion period.
Further, before the starting the IV scan and obtaining the historical power generation data of the inverter and the initial IV scan result, the method further includes:
and starting the IV scanning when the irradiance or the working current is judged to meet the diagnosis condition.
Further, the determining an occluded area where the photovoltaic system generates cloud occlusion according to the historical power generation data and the primary IV scan result comprises:
judging whether the photovoltaic system generates cloud layer shielding or not according to the historical power generation data;
and when cloud layer shielding is judged to be generated, determining the shielded area according to the historical power generation data and the primary IV scanning result.
Further, the judging whether the photovoltaic system generates cloud shielding according to the historical power generation data comprises:
determining cloud layer shielding identification parameters from the historical power generation data;
determining a rate of change over time of the cloud cover identification parameter for each string of the photovoltaic system;
and when the change rate of the cloud layer shielding identification parameter of each group string along with the time is less than or equal to a first preset threshold value within a preset time period, judging that the photovoltaic system does not generate cloud layer shielding, otherwise, judging that the photovoltaic system generates cloud layer shielding.
Further, the cloud cover identification parameter includes an operating current of the inverter.
Further, the determining an occluded area of the photovoltaic system from the historical power generation data and the primary IV scan results comprises:
determining the working current of each group string of the photovoltaic system according to the historical power generation data and the primary IV scanning result;
and determining the corresponding group of strings with the low working current as the shielded area.
Further, the determining that the corresponding set of strings with the lower operating current is the occluded area comprises:
determining a boundary group string shielded by a cloud layer and an adjacent group string adjacent to the boundary group string and not shielded by the cloud layer according to the region with the low working current;
determining whether a current mismatch characteristic exists in the boundary string and the adjacent string according to the primary IV scanning result;
and when the current mismatch characteristic exists, determining the corresponding shielded area according to the step voltage length of the IV curve.
Further, the determining a non-occlusion period of the occluded region comprises:
determining the working current of each group string of the photovoltaic system according to the historical power generation data and the primary IV scanning result;
determining the moving direction and the moving speed of the cloud layer according to the change condition of the working current;
determining the non-occlusion period of the occluded region according to the moving direction and the moving speed.
Further, the determining the moving direction and the moving speed of the cloud layer according to the change condition of the working current comprises:
determining a difference in rate of change of the operating current for each of the strings;
determining a current change rate difference between each group string and an adjacent group string according to the change rate difference;
and determining the moving direction and the moving speed of the cloud layer according to the current change rate difference.
Further, when the current change rate difference is greater than a second preset threshold, it is determined that the cloud layer is removed from the group string, when the current change rate difference is less than the negative second preset threshold, it is determined that the cloud layer starts to shield the group string, and when the absolute value of the current change rate difference is less than or equal to the second preset threshold, it is determined that the cloud layer does not move.
Further, before performing the IV scan again on the occluded region in the non-occlusion period, the method further includes:
determining the shielding proportion of the shielded area in the photovoltaic system;
and when the shielding proportion is larger than or equal to a preset shielding threshold value, not carrying out IV scanning on the shielded area again.
Further, the performing the IV scan again on the occluded region during the non-occlusion period comprises:
determining the corrected working current of the shielded area according to the historical power generation data;
when the difference value between the working current corrected by the shielded area and the maximum working current of all the groups of strings under the corresponding inverter is less than or equal to a third preset threshold value, the diagnosis condition is met;
when the diagnostic condition is satisfied, performing IV scanning on the occluded region again in the non-occluded period.
Further, the determining the corrected operating current of the shielded area according to the historical power generation data includes:
and determining the date of no cloud layer shielding for different strings in the shielded area according to the historical power generation data, and determining the corrected working current by taking the ratio of the working current of the strings to the maximum string current at different moments of the day as a proportionality coefficient.
Further, the performing the IV scan again on the occluded region during the non-occlusion period comprises:
determining a specific voltage interval according to the IV curve of the shielded area;
and IV scanning the shielded area again in the specific voltage interval in the non-shielding period.
Further, the determining a specific voltage interval according to the IV curve of the occluded area includes:
and when the fact that the power loss exists is determined according to the IV curve of the shielded area, determining the voltage interval where the mismatch current is located as the specific voltage interval.
To achieve the above object, in a second aspect, the present invention provides a control device for photovoltaic system IV diagnosis, comprising:
the acquisition module is used for starting IV scanning and acquiring historical power generation data and a primary IV scanning result of the inverter;
the processing module is used for determining an occluded area occluded by a cloud layer generated by the photovoltaic system according to the historical power generation data and the primary IV scanning result, and determining a non-occluded time period of the occluded area;
and the control module is used for carrying out IV scanning on the shielded area again in the non-shielding period.
By using the control method or device for photovoltaic system IV diagnosis, the cloudy weather is identified and whether the cloud layer shielding condition is generated or not is judged through analyzing the historical power generation data of the inverter, the moving characteristics of the cloud layer are determined according to the collected power generation data and the primary IV scanning result, so that the region shielded by the cloud layer and the non-shielding time period not shielded by the cloud layer are accurately positioned, and the shielded region which is confirmed to be not influenced by the cloud layer any more is subjected to IV scanning again in the non-shielding time period, so that the efficiency and the accuracy of IV fault diagnosis are improved. According to the method, the calling analysis of the historical power generation data of the inverter is combined with the IV scanning result, the shadow distribution of the cloud layer in the photovoltaic system is accurately analyzed, the shielding influence of the cloud layer is avoided, the IV diagnosis is applied in different areas and different periods, the misdiagnosis problem caused by the irradiance change of the IV diagnosis in cloudy weather is solved, and the application scene of the IV diagnosis is expanded.
To achieve the above object, in a third aspect, the present invention provides a non-transitory computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements the control method for photovoltaic system IV diagnostics according to the first aspect of the present invention.
To achieve the above object, in a fourth aspect, the present invention provides a computing device, including a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor executes the program to implement the control method for photovoltaic system IV diagnosis according to the first aspect of the present invention.
The non-transitory computer-readable storage medium and the computing device according to the present invention have similar advantageous effects to the control method of the photovoltaic system IV diagnosis according to the first aspect of the present invention, and are not described herein again.
Drawings
Fig. 1 is a schematic flow diagram of a control method for photovoltaic system IV diagnostics according to an embodiment of the invention;
FIG. 2 is a flowchart illustrating a process of determining an occluded area according to an embodiment of the present invention;
FIG. 3 is a schematic flow chart illustrating a process of determining cloud shielding according to an embodiment of the present invention;
FIG. 4 is a flowchart illustrating a process of determining an occluded area generated by cloud occlusion according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of IV curves for a normal string and a current mismatched string according to an embodiment of the present invention;
fig. 6 is a schematic flow chart illustrating a process of determining a photovoltaic string blocked by a cloud layer according to an operating current according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of current mismatch characteristics according to an embodiment of the present invention;
FIG. 8 is a flowchart illustrating a process of determining a non-occlusion period according to an embodiment of the invention;
FIG. 9 is a flowchart illustrating a process of determining a cloud layer movement status according to an embodiment of the present invention;
FIG. 10 is a flow chart illustrating control of the IV scan again according to an embodiment of the invention;
FIG. 11 is a schematic diagram of an IV curve warping process for a photovoltaic string in an occluded area according to an embodiment of the present invention;
FIG. 12 is a schematic flow chart illustrating the IV scan again in a specific voltage interval according to an embodiment of the present invention;
fig. 13 is a schematic structural diagram of a control device for photovoltaic system IV diagnosis according to an embodiment of the present invention.
Detailed Description
Embodiments in accordance with the present invention will now be described in detail with reference to the drawings, wherein like reference numerals refer to the same or similar elements throughout the different views unless otherwise specified. It is to be noted that the embodiments described in the following exemplary embodiments do not represent all embodiments of the present invention. They are merely examples of apparatus and methods consistent with certain aspects of the present disclosure, as detailed in the claims, and the scope of the present disclosure is not limited in these respects. Features of the various embodiments of the invention may be combined with each other without departing from the scope of the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.
With the increasing deterioration of ecological environment, people are aware of the severity of environmental problems, and at the same time, people are aware of the fact that energy structures must be changed, and green renewable energy is used to gradually replace disposable energy, thereby achieving the purpose of protecting the environment. The development and utilization of new energy are good solutions, and photovoltaic power generation is representative of the new energy.
Solar heat utilization, solar heat power generation and solar photovoltaic power generation are the main utilization modes in the solar photovoltaic industry at present. And among them, photovoltaic power generation technology has advantages such as green cleanness, equipment are simple, the maintenance rate is low and modularization as one of the most mature power generation technology. The photovoltaic power generation not only can supplement the insufficient power consumption in the peak power consumption period, but also can be effectively and economically used as a power grid expansion technology as a distributed power supply to supplement the insufficient power consumption of a main power grid.
In the prior art, a fault diagnosis method for a photovoltaic string comprises the steps of carrying out infrared image shooting on the photovoltaic string by adopting an infrared imaging technology, and judging the running state of the photovoltaic string according to different imaging colors of the photovoltaic string at different temperatures under an infrared image; or the operation state of the photovoltaic string is judged according to the difference between the ground capacitance values of the photovoltaic string under the normal and fault conditions of the photovoltaic string. However, an IV scanning method is often used, and an MPPT scanning function of the inverter is used to obtain an IV curve of the string, and diagnosis is performed according to a fault characteristic of the IV curve. However, in the existing IV fault diagnosis, it is often required to perform IV scanning in a sunny and cloudless weather, and due to the fact that a cloud layer can shield a cluster in a cloudy weather, incident irradiance on different clusters is different, or irradiance difference between different components in the same cluster causes irradiance not to be on a same standard, so that diagnosis is of no reference significance, and a misdiagnosis situation may be caused. However, in an actual application scenario, for example, some regions may have less sunny weather in some seasons, so that the conventional IV fault diagnosis may be more limited, and the fault diagnosis of the photovoltaic string cannot be accurately performed under different weather conditions, which affects the reliability of the operation of the entire photovoltaic system.
According to the invention, through calling and analyzing the historical power generation data of the inverter and comparing the IV scanning data among the photovoltaic string strings, the photovoltaic string influenced by the cloud layer can be accurately identified, and the misdiagnosis problem caused by the misdiagnosis is reduced. And a control strategy is set to carry out IV scanning and diagnosis on the photovoltaic group string influenced by the cloud layer again, so that the influence of the cloud layer on IV diagnosis is eliminated, the IV diagnosis under the cloudy weather is realized, and the application scene of the function is widened.
Fig. 1 is a schematic flowchart of a control method for photovoltaic system IV diagnosis according to an embodiment of the present invention, including steps S1 to S3.
In step S1, an IV scan is initiated, and historical power generation data for the inverter and the primary IV scan results are obtained. In an embodiment of the present invention, the controller may issue an IV scan command to the inverter, for example, to initiate IV diagnostics. Obtaining a primary IV scanning result after IV scanning for a period of time, and sampling by using a data collection unit, such as various sensors, to obtain n pieces of historical power generation data of the inverter within a certain time period T, such as working voltage VmiOperating current ImiOutput power PmiEnergy efficiency ratio PriAnd power generation amount, etc. It can be understood that, in the embodiment of the present invention, the time period T may be selected to be 30 minutes, or may be set to be other preset time lengths according to actual needs, so that various operating parameters of the inverter can be reflected more accurately, which is not limited in the present invention.
It is understood that, in the embodiment of the present invention, before step S1, the method may further include: and judging whether the irradiance or the working current meets the diagnosis condition, and starting the IV scanning when the irradiance or the working current meets the diagnosis condition, wherein the irradiance is preferably more than 500W/m2, and the working current is preferably more than the maximum power point current value under 1/2 assembly STC.
In step S2, an occluded region where the photovoltaic system generates cloud occlusion is determined according to the historical power generation data and the primary IV scan result, and a non-occluded period of the occluded region is determined. Fig. 2 is a schematic flowchart illustrating a process of determining an occluded area according to an embodiment of the present invention, including steps S21 to S22.
In step S21, it is determined whether the photovoltaic system generates cloud cover according to the historical power generation data. Fig. 3 is a schematic flow chart illustrating a process of determining generation of cloud shielding according to an embodiment of the present invention, including steps S211 to S213.
In step S211, cloud cover identification parameters are determined from the historical power generation data. In the embodiment of the invention, the working current I of the inverter is selected from historical power generation data of the invertermiAnd the cloud layer shielding identification parameter is used for judging whether the photovoltaic string is in cloudy weather or not and determining the influence of the shielding caused by the cloud layer on the photovoltaic string.
In step S212, a rate of change of the cloud occlusion recognition parameter over time for each string of the photovoltaic system is determined. In the embodiment of the invention, for each group string in a photovoltaic system, n inverter data sampling points are determined within a certain time period T, and the working current at each sampling point is recorded as Imij(I1, 2, 3 … n, representing a sampling time point, and j 1, 2, 3 … m, representing a string of a certain group in the photovoltaic system), and determining the operating current ImijRate of change over time KijAs shown in the following formula:
it will be appreciated that the operating current ImiRate of change over time KijThe irradiance change condition of each group string in the time period T can be represented so as to judge whether the group string is in cloudy weather or not, and the photovoltaic group string is influenced by the shielding of a cloud layer due to the existence and the movement of the cloud layer.
In step S213, when the change rate of the cloud layer occlusion identification parameter of each group string with time is less than or equal to a first preset threshold value within a preset time period, it is determined that the photovoltaic system does not generate cloud layer occlusion, otherwise, it is determined that the photovoltaic system generates cloud layer occlusion. In the embodiment of the present invention, when | KijWhen | ≦ epsilon 1 (epsilon 1 is a first preset threshold), the photovoltaic string is describedAnd the irradiance change is small, and the photovoltaic string is judged not to be influenced by the cloud layer in the time period and not to be shielded by the cloud layer. It will be appreciated that, at this time, it is also possible to perform more precise positioning of the shaded area subsequently, since the photovoltaic string or the cloud remains uniform. When | Kij|>And when the irradiance is epsilon 1, the change of the irradiance on the photovoltaic string is large, and the influence of cloudy weather on the position of the photovoltaic string in the time period is judged to generate cloud layer shielding. In the embodiment of the invention, cloud weather identification is carried out on all photovoltaic group strings in a photovoltaic system in a time period T according to cloud layer shielding identification parameters, and when all the photovoltaic group strings meet the condition of | K |, the cloud weather identification is carried outijWhen | ≦ ε 1, it indicates that the whole photovoltaic system is in sunny and cloudless weather in the time period, and is not shielded by the cloud layer, otherwise, it is considered to be in cloudy weather, and there is a photovoltaic string shielded by the cloud layer, and a shielded area is generated.
It will be appreciated that the first predetermined threshold ε 1 may be selected in relation to the inverter sampling time interval and the absolute time of sampling. For example, the sampling time interval of the current main stream is 1min, 5min and 15min, or other shorter time, which is more beneficial to improving the cloud layer identification precision. Sampling absolute time such as morning, noon and afternoon is mainly reflected in the change rate of irradiance, and the change rate of irradiance is gradually increased when changing to the morning and afternoon respectively due to the small change rate of the irradiance at noon. In the embodiment of the present invention, the first preset threshold may not be a fixed value, but a sequence value of a table lookup, which is not limited in the present invention.
In step S22, when it is determined that cloud occlusion occurs, the occluded region is determined from the historical power generation data and the primary IV scan result. Fig. 4 is a flowchart illustrating a process of determining an occluded area generated by cloud occlusion according to an embodiment of the present invention, including steps S221 to S222.
In step S221, the operating current of each string of the photovoltaic system is determined according to the historical power generation data. In the embodiment of the invention, when cloud layer shielding is judged to be generated, the working current I of each group string of the photovoltaic system is determinedmiAnd drawing the photovoltaic at each sampling time within the time period TOperating current I of strings at different positions in the systemmiAnd the relation graph is used for judging the shielded area generated by the cloud layer according to the change condition of the relation graph.
In step S222, it is determined that the corresponding group of strings with the lower operating current is the shielded region according to the primary IV scan result. In embodiments of the present invention, a photovoltaic system may have a plurality of photovoltaic strings, each having a corresponding operating current at a different irradiance. When the cloud layer shields some photovoltaic strings, the working current of the photovoltaic strings becomes low, and the working current of the photovoltaic strings is not reduced without being influenced by the shielding of the cloud layer. Therefore, the shielded area can be determined according to the working current change conditions corresponding to the photovoltaic group strings at different positions in the photovoltaic system. Fig. 5 is a schematic diagram of IV curves of a normal pv string and a current mismatch pv string according to an embodiment of the present invention, where according to the initial IV scan result, a region with low current is shielded by a cloud layer, and a region with high current is not shielded by the cloud layer, so as to determine that the corresponding pv string shielded by the cloud layer is the shielded region. Fig. 6 is a schematic flow chart illustrating a process of determining a photovoltaic string blocked by a cloud layer according to a working current according to an embodiment of the present invention, which includes steps S2221 to S2223.
In step S2221, the boundary group string shielded by the cloud layer and the adjacent group string adjacent thereto and not shielded by the cloud layer are determined according to the region where the operating current is low. In the embodiment of the invention, the working current I is used for measuring the working currentmiAnalyzing the initial position of the cloud layer influence area and the corresponding photovoltaic group string information according to the change characteristics of time, namely determining a boundary group string (defined as SJ) shielded by the cloud layer and an adjacent group string (defined as SL) adjacent to the boundary group string and not shielded by the cloud layer according to the change condition of the working current of each photovoltaic group string, and analyzing the IV scanning curve.
In step S2222, it is determined whether a current mismatch characteristic exists between the boundary group string and the adjacent group string according to the primary IV scan result. In embodiments of the present invention, it is determined whether the boundary set string SJ and the adjacent set string SL have a current mismatch characteristic based on a graph of the results of the initial IV scan. FIG. 7 is a schematic diagram illustrating current mismatch characterization according to an embodiment of the present invention, wherein the current mismatch is characterized by conduction and carry-out of a bypass diode in a junction box of a photovoltaic string, which is represented by V in FIG. 71The dip corner feature of the IV curve shown here resembles a step change.
In step S2223, when the current mismatch feature exists, the corresponding shielded area is determined according to the step voltage length of the primary IV scan result. In the embodiment of the present invention, all the concave inflection points and the convex inflection points on the IV curve are detected, and then the voltage corresponding to each concave inflection point is counted (for example, V in fig. 7)1) And the voltage (V in FIG. 7) corresponding to the adjacent convex inflection point to the right of the concave inflection point2) Defining a voltage segment V1-V2The interval corresponds to the step section of the current mismatch string if the open-circuit voltage of the monolithic component is VmocThen the number of mismatched components N can be calculated as follows:
in the embodiment of the invention, when the boundary group string SJ and the adjacent group string SL have the current mismatch characteristic, the cloud layer has shielding effect on partial components of the boundary group string SJ and the adjacent group string SL, but the working current I is caused by inconsistent influence degreesmiThe difference in (a). The number of the influencing components can be determined according to the step voltage length of the IV curve, and the sizes and the position information of the components are combined, so that the position of a shielded area influenced by the cloud layer is accurately positioned.
In the embodiment of the invention, when the current mismatch characteristic exists in the boundary group string SJ and the current mismatch characteristic does not exist in the adjacent group string SL, it is indicated that the cloud layer has shielding influence on part of components of the boundary group string SJ, but does not have shielding influence on the adjacent group string SL, the number of influencing components can be determined according to the step voltage length of the primary IV scanning curve, and the component size and the position information are combined, so that the position of a shielded area influenced by the cloud layer is accurately positioned.
In the embodiment of the invention, when the boundary group string SJ and the adjacent group string SL have no current mismatch characteristic, but the working current ImiAnd differences exist, which indicate that cloud layers have shielding influence on all components of the boundary group string SJ and have no shielding influence on the adjacent group string SL, and the cloud layer influence boundary is located in an area between the boundary group string SJ and the adjacent group string SL. In the embodiment of the invention, the shielding area of the cloud layer on the photovoltaic system is generally considered to be large, for the region of the cloud layer boundary between two strings, the whole contour line of the cloud layer shielding can be drawn by referring to the positioning of the cloud layer on other strings, and for the missing part, the boundary positioning can be carried out by adopting an extending and supplementing method.
In the embodiment of the present invention, when the boundary string SJ has no current mismatch characteristic and the adjacent string SL has a current mismatch characteristic, it is described that the cloud layer has a shielding effect on all components of the boundary string SJ and a shielding effect on a part of components of the adjacent string SL. The number of the shielding assemblies can be determined according to the step voltage length of the IV curve, and the sizes and the position information of the assemblies are combined, so that the position of a shielded area influenced by the cloud layer is accurately positioned.
Fig. 8 is a flowchart illustrating a method for determining a non-occlusion period according to an embodiment of the invention, which includes steps S23 to S25.
In step S23, the operating current of each string of the photovoltaic system is determined according to the historical power generation data. In the embodiment of the invention, the working current I of the strings at different positions in the photovoltaic system at each sampling time within the time period T is determinedmiAnd the motion state of the cloud layer is used as a basis for judging the motion state of the cloud layer.
In step S24, the moving direction and moving speed of the cloud layer are determined according to the variation of the working current. In the embodiment of the invention, the moving direction and the moving speed of the cloud layer are obtained according to the change characteristics of the working current between photovoltaic group strings in the photovoltaic system at different sampling moments in the time period T. Fig. 9 is a flowchart illustrating a process of determining a cloud layer moving state according to an embodiment of the present invention, which includes steps S241 to S243.
In step S241, a difference in the rate of change of the operating current for each of the strings is determined. In the embodiment of the invention, for the ith time point, the working current I of the jth photovoltaic stringmijThe rate of change with time is recorded as KijFor the (I +1) th time point, the working current I of the jth photovoltaic stringm(i+1)jThe rate of change with time is recorded as K(i+1)j. Calculating the difference D of the current change rate of the ith time point and the (i +1) th time pointijAs shown in the following formula:
Dij＝K(i+1)j-Kij。
in step S242, a current change rate difference between each group string and its adjacent group string is determined according to the change rate difference. In the embodiment of the invention, based on the position information of the photovoltaic system string, the photovoltaic string (j +1), (j +2), (j +3) and (j +4) at the adjacent position of the jth photovoltaic string is obtained, the photovoltaic strings in the four directions of east, west, south and north with the nearest distance are corresponding, and the current change rate difference values of the photovoltaic strings are respectively calculated: di(j+1)、Di(j+2)、Di(j+3)、Di(j+4). When D is presenti(j+x)>E 2, (x ═ 1, 2, 3, 4) (e 2 is the second preset threshold), indicating that during this adjacent moment the irradiance of the string changes, increasing, indicating that the cloud is removed from the string. Also, when D is presenti(j+x)<-e 2, (x ═ 1, 2, 3, 4), indicating that during this adjacent moment the irradiance of the string changes, the irradiance decreases, indicating that at this moment the cloud enters the string, starts to occlude the string, or the degree of occlusion increases. When | Di(j+x)When | ≦ ε 2, it indicates that the irradiance of the (j + x) th photovoltaic string adjacent to the (j) th photovoltaic string is also stable during this period, and the cloud layer does not move.
In step S243, the moving direction and the moving speed of the cloud layer are determined according to the current change rate difference. In the embodiment of the invention, the jth photovoltaic string is taken as the center, the photovoltaic string gradually expands to the periphery, and the current change rate difference D of adjacent moments is calculatedi(j+x)Up to the current changeChange rate difference Di(j+x)Is not in [ - ε 2, ε 2]When the cloud layer shadow moving speed is within the range, the moving direction of the cloud layer can be judged based on the change characteristics of the difference values of different positions, the accurate region position of the cloud layer shadow in the photovoltaic system is obtained based on the group string physical position, the sampling time interval and the boundary group string IV diagnosis result, and the moving speed of the cloud layer is calculated. In the embodiment of the invention, epsilon 2 represents the difference value of irradiance change obtained after difference calculation according to different sampling moments, and the value is related to the shielding degree of the cloud layer and the irradiance after the cloud layer is moved away. Irradiance requirements based on IV scanning, typically greater than 500W/m2Therefore, the second preset threshold ε 2 may be preferable to be set at 200W/m2The irradiance change difference value of, e 2 may preferably be: maximum operating current I in all strings in the systemmX 15%, as a preferred value.
It can be understood that parameters such as working current, working voltage, output power and the like of sampling points of the whole photovoltaic system in a time period T can be intelligently analyzed based on statistical analysis of big data, cloud layer affected areas are located by using methods such as fuzzy classification and the like, and the moving direction and moving speed of a cloud layer are determined, which is not limited by the invention.
In step S25, the non-occlusion period of the occluded area is determined according to the moving direction and the moving speed. In the embodiment of the invention, the moving direction and the moving speed of the cloud layer can be determined according to the working current, the distribution characteristics of the cloud layer are determined according to the moving direction and the moving speed, and then at least two cloud layer occlusion images can be drawn according to the working current acquired at different sampling moments. For the photovoltaic string with occlusion determined by the IV scanning, the time when the photovoltaic string is not affected by the cloud occlusion can be determined according to the cloud occlusion image drawn at different moments, the moving speed and the moving direction of the cloud, namely the non-occlusion time delta t of the occluded area.
In step S3, the occluded region is again IV scanned during the non-occluded period. Fig. 10 is a flowchart illustrating the control of re-performing the IV scan according to the embodiment of the present invention, which includes steps S31 to S33.
In step S31, the operating current corrected by the shielded area is determined from the historical power generation data. In the embodiment of the invention, for the IV scanning data obtained at different sampling moments, because the irradiance on the photovoltaic string is inconsistent at different moments, the working currents obtained at different moments are corrected to avoid the influence of the irradiance on the photovoltaic string.
In the embodiment of the invention, for different strings in the shielded area, the date of non-cloud layer shielding is determined according to the historical power generation data, and the corrected working current is determined according to the ratio of the working current of the strings at different moments of the day to the maximum string current as a proportionality coefficient. Fig. 11 is a schematic diagram illustrating an IV curve warping process for a photovoltaic string in an occluded area according to an embodiment of the present invention. In the embodiment of the invention, the historical power generation data of the inverter is called, the date of a sunny day is filtered and screened, the ratio of the working current of the photovoltaic string at each sampling moment of the day to the maximum string current corresponding to the sampling moment is obtained and recorded as the correction coefficient KiCorrecting the current value of the IV scanning data, wherein the corrected electrical working current is Imi×KiThe voltage remains unchanged. It can be understood that for IV data scanned at different times, a uniform normalization process of irradiance and necessary data patching process are required to achieve complete output of an IV curve.
It can be understood that, in the embodiment of the present invention, the historical power generation data of the inverter includes a plurality of power generation data of the inverter within a certain time period, which are used for determining whether a cloudy occlusion occurs, and also includes a plurality of historical power generation data in units of days, which are used for normalization of subsequent IV data.
It can be understood that, in the embodiment of the present invention, historical power generation data of the inverter may also be collected in advance, and the result may be called when the IV scan diagnosis is started, so that the time for IV diagnosis may be effectively saved.
In step S32, when the difference between the corrected operating current of the blocked region and the maximum operating current of all the strings under the corresponding inverter is less than or equal to a third preset threshold, a diagnostic condition is satisfied. In the embodiments of the present inventionMonitoring the power generation data of the inverter at each sampling moment in real time, preferably the working current Imi. Calculating regular working current I of abnormal stringmiThe difference value between the maximum value of the working current of all the groups of the inverter and the maximum value of the working current of all the groups of the inverter is recorded as delta ImWhen Δ ImWhen the current value is less than or equal to epsilon 3 (epsilon 3 is a third preset threshold value), the irradiance received by all the photovoltaic string under the inverter is consistent, the diagnosis condition is met at the moment, and the photovoltaic string with the abnormal IV diagnosis (namely, the shielded area) can be subjected to IV scanning in a specific voltage interval. It is understood that when Δ Im>When epsilon 3, the photovoltaic string is influenced by the cloud cover, and has a difference with the irradiance received by other photovoltaic strings under the inverter, at the moment, the sampling moment is added with a time period, and the working current I is continuously carried outmiMonitoring and comparing delta ImAnd (6) judging.
It can be understood that the third preset threshold value epsilon 3 is a difference value between the current of the abnormal photovoltaic string (shielded area) monitored by the inverter and the maximum current of all photovoltaic strings in the system, and can be obtained through self-learning based on the historical power generation data of the inverter, that is, different values are obtained at different times, so that the third preset threshold value is a value which changes along with time and can be given by adopting a table look-up method, but the invention is not limited thereto.
In step S33, when the diagnostic condition is satisfied, IV scanning is performed again on the occluded region during the non-occlusion period. In the embodiment of the invention, after the non-occlusion period Δ t of the occluded region is determined, when the IV data meets the re-diagnosis condition, the occluded region is scanned again by IV. It will be appreciated that the determination of whether the IV scan condition is met again may be made based on the following comparison: comparing characteristic parameters of all photovoltaic group strings in the current IV scanning, and comparing characteristic parameters of the same photovoltaic group string in previous and subsequent IV scanning for multiple times, wherein the characteristic parameters can be: short-circuit current IscOpen circuit voltage VocMaximum power point current ImMaximum power point voltage VmMaximum power PmIV curve mismatch inflection point characteristics (presence or absence of inflection point, inflection point position). For example: twice before and after the same photovoltaic group stringAnd inflection points exist on the IV curve, but the positions of the inflection points are not consistent, so that the cloud layer still influences the photovoltaic string and does not meet the diagnosis condition.
It is understood that, in the embodiment of the present invention, the scan interval may not be limited, and the IV scan data may be scanned from the open-circuit voltage to the short-circuit current, or other voltage intervals. Different scanning schemes can be set according to actual requirements, and the invention is not limited to this.
In the embodiment of the invention, the specific voltage interval can be determined according to the IV curve of the shielded area to perform IV scanning again. Fig. 12 is a flowchart illustrating an IV scan performed again in a specific voltage interval according to an embodiment of the present invention, including steps S331 to S332.
In step S331, a specific voltage interval is determined according to the IV curve of the shielded region. In the embodiment of the invention, when the fact that the power loss exists is determined according to the IV curve of the shielded area, the voltage interval where the mismatch current is located is determined to be the specific voltage interval. In the embodiment of the invention, the working current I in the power generation parameters of the inverter is monitored in real time in the IV scanning time periodmiWhen Δ I is detectedmAnd when the voltage is less than or equal to epsilon 3, controlling to execute the IV scanning again in a specific voltage interval of the IV curve, wherein the method for determining the specific voltage interval comprises the following steps: in an abnormal group string (shielded area) diagnosed by IV for the first time, current mismatch detection is carried out according to inflection point characteristics on an IV curve, and when the current loss occurs, a voltage interval where mismatch current on the IV curve is located is identified and determined as a specific voltage interval.
In the embodiment of the present invention, the dip inflection point may be obtained by deriving the IV curve to identify the current mismatch characteristic, and the dip inflection point may also be identified by the concavity and the convexity of the IV curve to determine the current mismatch, which is not limited in the present invention. The specific voltage interval is 0V to the voltage corresponding to the rightmost sunken inflection point, as shown in FIG. 5 as [0, V ]1]. In the embodiment of the invention, it is preferable to perform the IV scan in the specific voltage interval to reduce the IV scan time, and since the IV scan is performed again only in the specific voltage interval, data is missing in a part of the voltage interval, and it is necessary to use the number of the previous IV scanAnd repairing according to the data. As shown in FIG. 5, the IV curve of the cloud-shielded string has a current mismatch characteristic, and when the string has no cloud shielding, an IV scan of a specific voltage interval, i.e., the voltage interval [0, V ] in FIG. 5, is performed1]Then in the voltage interval [ V ]1，Voc]Is missing and needs to be patched based on previous IV data. Using the cloud layer occlusion cluster IV curve and the non-cloud layer occlusion cluster IV curve in FIG. 5 at V1The current ratio of the point is recorded as KG, and the cloud layer shielding group string IV curve is positioned in the voltage interval V1，Voc]The current value of (2) is multiplied by the ratio coefficient KG, and the voltage is kept unchanged, namely, the current value is converted into IV data when no cloud layer is shielded. And finally obtaining the complete IV curve of the cloud-free layer shielding group string through repairing.
It can be understood that, when there is no power loss, the ratio of the operating current of each group string to the maximum group string operating current obtained based on the historical power generation data of the inverter on a clear day is corrected by multiplying the current in the IV data of the abnormal group string by the ratio as shown in fig. 11, and the voltage is kept unchanged, thereby completing the adjustment and correction processing of the IV data.
In step S332, IV scanning is performed again on the shielded region in the specific voltage interval during the non-shielding period. In the embodiment of the invention, after the non-shielding time interval delta t and the specific voltage interval of the shielded area are determined, when the IV data meet the condition of diagnosing again, the shielded area is scanned again by IV.
In this embodiment of the present invention, before step S3, the method may further include determining an occlusion ratio of the occluded region in the photovoltaic system, and when the occlusion ratio is greater than or equal to a preset occlusion threshold, performing no IV scan on the occluded region again. In the embodiment of the invention, when it is determined that the weather is cloudy, whether the IV scanning condition is met again or not is judged according to the shielding degree of the cloud layer on the whole photovoltaic system, when the shielding area of the cloud layer on the whole photovoltaic system is larger than or equal to S, namely the shielding proportion is larger than or equal to a preset shielding threshold value, the cloud layer shielding is serious, the diagnosis condition is not met, the initial state is returned, and the next IV scanning instruction is waited; otherwise, the IV scanning condition in the cloudy weather is met, and the IV scanning is executed again. It can be understood that S is the shielding area of the cloud layer on the photovoltaic system, when S is too large, the IV diagnosis algorithm cannot acquire the optimal normal photovoltaic string, and secondly, when S is too large, the cloud layer is too large in shielding and is not suitable for IV diagnosis. S may be preferably 50% for the purpose of improving accuracy and efficiency of diagnosis, but the present invention is not limited thereto.
It is understood that after performing the IV scan and the fault diagnosis in the cloudless weather or performing the IV diagnosis again in the cloudy weather, "normal" is output when it is determined that the photovoltaic system has no fault, and the corresponding fault type is output when it is determined that the photovoltaic system has a fault. The fault diagnosis here mainly includes: data processing and diagnostic algorithms, wherein the data processing essentially comprises: de-duplication, sorting, de-noising, interpolation, smoothing, fitting processing and the like. The diagnosis algorithm mainly identifies faults according to fault characteristic values, for example, current mismatch faults can be identified by inflection point characteristic values through the concavity and convexity of an IV curve, and non-current mismatch faults can be identified through model comparison, which is not limited by the invention.
In the embodiment of the invention, based on the cloud layer distribution characteristics, the global IV scanning can be executed firstly, and the photovoltaic string influenced by the cloud layer is subjected to IV scanning and diagnosis again in a specified time period. The method can also be used for performing IV scanning and diagnosis on partial photovoltaic group strings in an area and time period which are not shielded by the cloud layer based on the cloud layer distribution characteristics, and selecting the time period which is not influenced by the cloud layer for IV diagnosis on the photovoltaic group strings influenced by the cloud layer, namely completing IV fault diagnosis on different photovoltaic group strings in different areas and time periods.
By adopting the control method for the photovoltaic system IV diagnosis provided by the embodiment of the invention, the cloudy weather is identified and whether the cloud layer shielding condition is generated or not is judged through analyzing the historical power generation data of the inverter, the moving characteristics of the cloud layer are determined according to the collected power generation data and the primary IV scanning result, so that the region shielded by the cloud layer and the non-shielding time period not shielded by the cloud layer are accurately positioned, and the IV scanning of the specific voltage interval is performed again on the shielded region which is confirmed to be not influenced by the cloud layer any more in the non-shielding time period, thereby improving the efficiency and the accuracy of the IV fault diagnosis. According to the method, the calling analysis of the historical power generation data of the inverter is combined with the IV scanning result, the shadow distribution of the cloud layer in the photovoltaic system is accurately analyzed, the shielding influence of the cloud layer is avoided, the IV diagnosis is applied in different areas and different periods, the misdiagnosis problem caused by the irradiance change of the IV diagnosis in cloudy weather is solved, and the application scene of the IV diagnosis is expanded.
The embodiment of the second aspect of the invention also provides a control device for photovoltaic system IV diagnosis. Fig. 13 is a schematic structural diagram of a control apparatus 1300 for photovoltaic system IV diagnosis according to an embodiment of the present invention, including an obtaining module 1301, a processing module 1302, and a control module 1303.
The obtaining module 1301 is configured to start an IV scan, and obtain historical power generation data of the inverter and a primary IV scan result.
The processing module 1302 is configured to determine an occluded region occluded by a cloud layer generated by the photovoltaic system according to the historical power generation data and the primary IV scan result, and determine a non-occluded time period of the occluded region.
The control module 1303 is configured to perform an IV scan on the occluded region again during the non-occlusion period.
In this embodiment of the present invention, the processing module 1302 is further configured to determine cloud occlusion identification parameters from the historical power generation data; determining a rate of change over time of the cloud cover identification parameter for each cluster of the photovoltaic system; and when the change rate of the cloud layer shielding identification parameter of each group string along with the time is less than or equal to a first preset threshold value within a preset time period, judging that the photovoltaic system does not generate cloud layer shielding, otherwise, judging that the photovoltaic system generates cloud layer shielding.
In this embodiment of the present invention, the processing module 1302 is further configured to determine an operating current of each string of the photovoltaic system according to the historical power generation data; determining the moving direction and the moving speed of the cloud layer according to the change condition of the working current; determining the non-occlusion period of the occluded region according to the moving direction and the moving speed.
For more specific implementation of each module of the control apparatus 1300 for photovoltaic system IV diagnosis, reference may be made to the description of the control method for photovoltaic system IV diagnosis of the present invention, and similar beneficial effects are obtained, and therefore, no further description is provided herein.
An embodiment of the third aspect of the invention proposes a non-transitory computer-readable storage medium on which a computer program is stored which, when executed by a processor, implements the control method for photovoltaic system IV diagnostics according to the first aspect of the invention.
Generally, computer instructions for carrying out the methods of the present invention may be carried using any combination of one or more computer-readable storage media. Non-transitory computer readable storage media may include any computer readable medium except for the signal itself, which is temporarily propagating.
A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device.
Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C + +, and conventional procedural programming languages, such as the "C" programming language or similar programming languages, and in particular may employ Python languages suitable for neural network computing and TensorFlow, PyTorch-based platform frameworks. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider).
An embodiment of the fourth aspect of the present invention provides a computing device, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the program, the processor implements the control method for photovoltaic system IV diagnosis according to the first aspect of the present invention. It is to be understood that the computing device of the present invention may be a server or a computationally limited terminal device.
The non-transitory computer readable storage medium and the computing device according to the third and fourth aspects of the present invention can be implemented with reference to the content specifically described in the embodiment of the first aspect of the present invention, and have similar beneficial effects to the control method for photovoltaic system IV diagnosis according to the embodiment of the first aspect of the present invention, and are not repeated herein.
While embodiments of the present invention have been shown and described above, it should be understood that they have been presented by way of example only, and not limitation, and that various changes, modifications, substitutions and alterations can be made by those skilled in the art without departing from the scope of the present invention.
Claims (18)
1. A control method for photovoltaic system IV diagnosis is characterized by comprising the following steps:
starting IV scanning, and acquiring historical power generation data and a primary IV scanning result of the inverter;
determining an occluded area occluded by a cloud layer generated by a photovoltaic system according to the historical power generation data and the primary IV scanning result, wherein the occluded area comprises: determining the change rate of cloud layer shielding identification parameters along with time according to the historical power generation data, and judging whether the photovoltaic system generates cloud layer shielding or not according to the change rate, wherein the change rate is used for representing the irradiance change condition of the string; and determining a non-occlusion period for the occluded region, comprising: determining the movement characteristics of a cloud layer according to the historical power generation data, and determining the non-occlusion time period of the occluded region according to the movement characteristics;
performing IV scanning on the occluded region again during the non-occlusion period.
2. The control method for photovoltaic system IV diagnosis according to claim 1, wherein before the starting IV scan and obtaining the historical power generation data of the inverter and the result of the initial IV scan, the method further comprises:
and starting the IV scanning when the irradiance or the working current is judged to meet the diagnosis condition.
3. The method of claim 1, wherein determining the occluded area of the photovoltaic system that is occluded by the cloud based on the historical power generation data and the primary IV scan comprises:
judging whether the photovoltaic system generates cloud layer shielding or not according to the historical power generation data;
and when cloud layer shielding is judged to be generated, determining the shielded area according to the historical power generation data and the primary IV scanning result.
4. The control method for photovoltaic system IV diagnosis according to claim 3, wherein the determining whether the photovoltaic system generates cloud cover according to the historical power generation data comprises:
determining cloud layer shielding identification parameters from the historical power generation data;
determining a rate of change over time of the cloud cover identification parameter for each string of the photovoltaic system;
and when the change rate of the cloud layer shielding identification parameter of each group string along with the time is less than or equal to a first preset threshold value within a preset time period, judging that the photovoltaic system does not generate cloud layer shielding, otherwise, judging that the photovoltaic system generates cloud layer shielding.
5. The control method for photovoltaic system IV diagnosis according to claim 4, wherein the cloud cover identification parameter comprises an operating current of the inverter.
6. The control method of photovoltaic system IV diagnosis according to claim 3, wherein the determining of the occluded area of the photovoltaic system from the historical power generation data and the primary IV scan results comprises:
determining the working current of each group string of the photovoltaic system according to the historical power generation data;
and determining the corresponding group of strings with low working current as the shielded area according to the primary IV scanning result.
7. The control method of photovoltaic system IV diagnosis as claimed in claim 6, wherein the determining the corresponding set of strings with low operating current as the occluded area comprises:
determining a boundary group string shielded by a cloud layer and an adjacent group string adjacent to the boundary group string and not shielded by the cloud layer according to the region with the low working current;
determining whether a current mismatch characteristic exists in the boundary string and the adjacent string according to the primary IV scanning result;
and when the current mismatch characteristic exists, determining the corresponding shielded area according to the step voltage length of the primary IV scanning result.
8. The control method for photovoltaic system IV diagnostics according to any of the claims 1-7, wherein the determining a non-occlusion period for the occluded region comprises:
determining the working current of each group string of the photovoltaic system according to the historical power generation data;
determining the moving direction and the moving speed of the cloud layer according to the change condition of the working current;
determining the non-occlusion period of the occluded region according to the moving direction and the moving speed.
9. The control method for photovoltaic system IV diagnosis according to claim 8, wherein the determining the moving direction and the moving speed of the cloud layer according to the variation of the working current comprises:
determining a difference in rate of change of the operating current for each of the strings;
determining a current change rate difference between each group string and an adjacent group string according to the change rate difference;
and determining the moving direction and the moving speed of the cloud layer according to the current change rate difference.
10. The control method for photovoltaic system IV diagnostics according to claim 9, characterized in that it is determined that cloud cover is removed from the cluster when the current rate of change difference is greater than a second preset threshold, that cloud cover starts to cover the cluster when the current rate of change difference is less than the negative second preset threshold, and that cloud cover is not moved when the absolute value of the current rate of change difference is less than or equal to the second preset threshold.
11. The control method for photovoltaic system IV diagnosis according to any one of claims 1-7, further comprising, before the IV scanning the occluded region of the pair of non-occluded periods again:
determining the shielding proportion of the shielded area in the photovoltaic system;
and when the shielding proportion is larger than or equal to a preset shielding threshold value, not carrying out IV scanning on the shielded area again.
12. The control method for photovoltaic system IV diagnosis according to any one of claims 1 to 7, wherein the IV scanning the occluded region again during the non-occlusion period comprises:
determining the corrected working current of the shielded area according to the historical power generation data;
when the difference value between the working current corrected by the shielded area and the maximum working current of all the groups of strings under the corresponding inverter is less than or equal to a third preset threshold value, the diagnosis condition is met;
when the diagnostic condition is satisfied, performing IV scanning on the occluded region again in the non-occluded period.
13. The control method for photovoltaic system IV diagnostics according to claim 12, wherein the determining the modified operating current for the occluded region from the historical power generation data comprises:
and determining the date of non-cloud layer shielding according to the historical power generation data for different strings in the shielded area, and determining the corrected working current according to the ratio of the working current of the strings at different moments in the day to the maximum string current as a proportionality coefficient.
14. The method of controlling photovoltaic system IV diagnostics according to claim 12, wherein the IV scanning the occluded region again during the non-occluding period comprises:
determining a specific voltage interval according to the IV curve of the shielded area;
and IV scanning the shielded area again in the specific voltage interval in the non-shielding period.
15. The method of claim 14, wherein determining the specific voltage interval according to the IV curve of the shaded region comprises:
and when the fact that the power loss exists is determined according to the IV curve of the shielded area, determining the voltage interval where the mismatch current is located as the specific voltage interval.
16. A control device for photovoltaic system IV diagnostics, comprising:
the acquisition module is used for starting IV scanning and acquiring historical power generation data and a primary IV scanning result of the inverter;
the processing module is used for determining an occluded area occluded by a cloud layer generated by the photovoltaic system according to the historical power generation data and the primary IV scanning result, and comprises: determining the change rate of cloud layer shielding identification parameters along with time according to the historical power generation data, and judging whether the photovoltaic system generates cloud layer shielding or not according to the change rate, wherein the change rate is used for representing the irradiance change condition of the string; and determining a non-occlusion period for the occluded region, comprising: determining the movement characteristics of a cloud layer according to the historical power generation data, and determining the non-occlusion time period of the occluded region according to the movement characteristics;
a control module to perform IV scanning again on the occluded region during the non-occluded period.
17. A non-transitory computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements a control method for photovoltaic system IV diagnostics according to any one of claims 1-15.
18. A computing device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor, when executing the program, implements a control method for photovoltaic system IV diagnostics according to any one of claims 1 to 15.
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| CN202011446396.4A CN112653393B (en) | 2020-12-09 | 2020-12-09 | Control method and device for photovoltaic system IV diagnosis |
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| CN113326667B (en) * | 2021-08-03 | 2021-12-10 | 深圳格瑞特新能源有限公司 | Solar cell panel fault diagnosis method and system |
| CN113612444A (en) * | 2021-08-03 | 2021-11-05 | 阳光新能源开发有限公司 | Shielding diagnosis method for photovoltaic module |
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