| As the installed scale of PV power plants continues to expand,PV array fault diagnosis has become a research hotspot.The analysis of PV array operation status is the basis of modeling and fault diagnosis,while fault diagnosis is the means to ensure the safe and economic operation of PV system.This paper focuses on how to realize a fault diagnosis method based on PV array operational state analysis that is more in line with the actual engineering needs,and conducts the following research:(1)In order to construct a high-precision mathematical model of PV arrays,online modeling and calculation of the working temperature of PV modules,online parameter identification of the electrical parameters of PV modules are realized,and finally the distribution characteristics of the electrical parameters of PV arrays under different operating conditions are elucidated using the established simulation model of PV arrays.The BP-ANN-based PV module operating temperature model is constructed,and the experimental results show that the accuracy of the method is significantly improved compared with that of the empirical formula,and the soft measurement of the PV module operating temperature is realized;the modeling and identification method of the PV module electrical parameters based on the typical operating conditions is proposed,and the data of the typical operating conditions are fitted,and the measured results prove that the error of the PV module electrical parameters calculated by this method under different The results show that the error of electrical parameters of PV modules calculated by this method under different environmental conditions is within 3%,and this method realizes online identification of electrical parameters of PV modules and improves the modeling accuracy;based on the above model,a simulation model of PV arrays is established,and the distribution of electrical parameters of PV arrays under typical fault conditions of PV arrays,shadowing and shading fault conditions is mastered,and the error of experimental results does not exceed 1.8%.(2)In order to grasp the influence of environmental factors on the power generation performance of PV arrays,the power generation performance of a large mountain PV system was studied,and the influence of spectral differences on the power generation performance of different PV modules was analyzed,and the calculation results showed that the spectral gain or loss of crystalline silicon PV modules was generally within 1%;the method of calculating the irradiance GTI of different angles of tilted surface with reference to the output power correction of the array was proposed,and the experimental results The experimental results show that the error is less than 19W/m2;through data statistics and finite element modeling,the effects of wind speed,ambient temperature and module technology differences on module operating temperature are investigated;the effects of ash accumulation on the power generation performance of PV arrays are investigated through empirical comparison;based on the above research,the performance index(PI)of PV arrays under different conditions is modified and used for PV arrays.The method makes full use of the electrical and environmental data collected from the PV system,and establishes the mathematical relationship between various environmental factors and the power generation performance of different PV arrays,and the results prove that the proposed modified PIcorr can effectively achieve the fault diagnosis of PV arrays.(3)Finally,based on the mathematical model of PV arrays and the law of the influence of environmental factors on the power generation performance of PV arrays,a dynamic alarm threshold fault diagnosis method is proposed to realize the threshold setting method and more accurate fault diagnosis that adapt to different working conditions.Combining the quantile calculation and time window technology,the dynamic alarm threshold setting is realized to adapt to the changes of environmental factors.By analyzing the law of dynamic change of PV array operating characteristics with environmental variables,the quantile method is used to set dynamic thresholds for PV array operating characteristics under different environmental conditions,and the dynamic thresholds are used to realize the judgment of PV array operating status.The dynamic alarm threshold method can reduce the false alarm and leakage rate to within 2.9%,which is much lower than the fixed alarm threshold.The method is based on historical statistics and environmental variables to set thresholds for electrical parameters,which effectively solves the problem of threshold setting based on human experience,and the method has good engineering practical value for common PV systems,providing a new solution for PV system operation and maintenance. |
