Hot Spot Fault Diagnosis And Analysis Of Photovoltaic Modules

In recent years,China’s photovoltaic industry has been booming.The cumulative installation of photovoltaic power generation is increasing year by year.In the critical period of photovoltaic industry development,the operation and maintenance of photovoltaic power station becomes particularly important.Hot spot problem is one of the common failures of photovoltaic power generation system.It will not only significantly reduce the power generation efficiency of photovoltaic modules,but even affect the safety of photovoltaic power generation system in serious cases.Therefore,how to efficiently and accurately complete hot spot detection and study the influence of hot spot effect on photovoltaic system under different circumstances has become a hot topic in the photovoltaic field.Based on the hot spot fault images provided by cooperative photovoltaic power stations,this paper sets up a small photovoltaic power generation system as an experimental platform to conduct an in-depth study on the above issues.The main work of this paper is as follows:Firstly,I investigate the research status of hot spot fault detection and its influence on electrical performance at home and abroad.According to the basic structure of photovoltaic power generation system,I analyze the temperature difference characteristics and infrared imaging characteristics of photovoltaic modules.At the same time,I use the Simulink simulation module of MATLAB to simulate the photovoltaic array,and analyze the I-V curve and P-V curve of the simulated photovoltaic array,which provides a theoretical basis for subsequent hot spot fault identification and exploring the impact of hot spot fault on the electrical performance of photovoltaic modules.Secondly,I completed the segmentation algorithm for the photovoltaic module region in the infrared image.Infrared image usually contains many kinds of complex interference background information,such as thermal imager labeling,land,shadow and so on.The infrared characteristics of some interference backgrounds in infrared images are very similar to hot spots.In view of this situation,this paper proposes an area segmentation algorithm for photovoltaic modules based on Seg Net.I collected and produced the infrared image data set of photovoltaic modules and labeled module area by Label Me software.Then I train the model to segment the component region.Finally,the pixel level recognition accuracy reaches 96.83%.In addition,this paper also uses the traditional image processing algorithm K-means clustering algorithm for infrared image processing as a comparative experiment,which can prove that the proposed Seg Net based photovoltaic module region segmentation algorithm is more effective.Thirdly,I complete the hot spot detection algorithm in infrared image.The hot spot extraction experiment based on Otsu algorithm is completed.Through the limitations of the algorithm in the experimental results,I propose a hot spot extraction algorithm based on Otsu double threshold segmentation.Finally,the connected regions are extracted by the region connectivity method based on morphology,and the hot spots are located effectively.Finally,the accuracy of hot spot recognition is 97.46%.In addition,this paper also extracts the HOG features of the infrared image,and uses SVM to classify and recognize the image as a comparative experiment.Fourthly,I completed the analysis of the influence of hot spot effect on the electrical performance of photovoltaic modules.I classified and summarized the causes of hot spot failure of PV modules.Then I introduce the working principle of solar cells.On this basis,combined with I-V curve,I deeply analyzed the cause of hot spot failure caused by internal defects.Finally,by using different shielding materials,I studied the temperature rise and conversion efficiency of photovoltaic modules under the condition of shielding hot spots.In addition,I compared and analyzed the I-V curves between the PV modules with internal defects leading to hot spot failure and the PV modules with shadow shading leading to hot spot failure,which provided support for the healthy operation and maintenance of the subsequent PV modules.Lastly,I completed the hot spot online detection platform.I analyze the logic of the software system and divide the system into user management module and hot spot detection module.After the completion of the development,I tested the software system to ensure its normal operation.