Research On Fault Diagnosis Method Of Crystalline Silicon Photovoltaic Modules Based On ?-? Characteristics Analysis

With the rapid development of photovoltaic(PV)power generation technology,large-scale PV power stations have been put into operation one after another.Since PV modules are installed in outdoor environments and are continuously exposed to harsh environmental conditions,various fault problems are becoming increasingly prominent.The fault of the PV system has seriously affected the power generation efficiency of the system,and even caused a series of safety problems,which increased the economic cost of operation and maintenance,so its reliability has also attracted more and more attention.As the core component of the PV power generation system,the reliability of PV modules is the key to the performance of the entire system.Therefore,fault diagnosis of PV modules is becoming more and more important.Aiming at the fault of PV modules,through field investigations of several common fault types of polycrystalline silicon PV modules in actual PV power plants,multiple sets of faulty module samples are collected.According to whether the bypass diode in the module is turned on,the fault is divided into two types: mismatch and non-mismatch.Wherein the mismatch including shadow,hot spot,and glass crack faults,and non-mismatch include aging,diode short circuits,and potential induced degradation(PID)faults.Comparing the two PV cell models,the model with reverse bias characteristic can better reflect the working state of the cell under reverse bias.By testing the ?-? characteristic curves of PV modules with different fault types,the characteristics and parameter changes of the modules under different faults are analyzed,and the fault features under different fault states are extracted.The concavity and convexity of the ?-? curve of non-mismatched modules does not change,and the key parameters change.Due to the conduction of the bypass diode in the PV module,the ?-? curve of the mismatch fault module has the characteristics of inflection point and step,and the concavity and convexity of the curve changes.The fault diagnosis of PV module is divided into non-mismatch and mismatch diagnosis.For the diagnosis of non-mismatch faults,a key parameter discrimination method and an optimal PV module discrimination method are proposed.Diagnosis methods for mismatch faults include methods based on ?-? curve concavity and convexity and diagnosis methods based on ?-? curve division and regional feature points.Through the combination of non-mismatch and mismatch fault diagnosis methods,the above-mentioned faults of the PV module can be diagnosed.Combined with the distributed PV power generation system with the power optimizer of the ?-? scanning function,examples and analysis of the above fault diagnosis methods of PV module are carried out.The results show that the proposed fault diagnosis methods have high accuracy,good applicability and high practical application value.