DC Series Arc In Photovoltaic System Based On Parameter Identification

Recently,led by the dual carbon goal,the installed capacity of China’s distributed photovoltaic（DPV）generation showed explosive growth,but it also brought more complex application scenarios,making it more difficult to maintain and check the safety of the PV system.Among them,the detection of a series arc fault is more difficult and easily confused with the output fluctuation caused by the change in illumination temperature.Therefore,the characteristics of the PV system and its series DC arc faults are studied in this paper,and an arc fault detection method based on parameter identification is proposed.The main research contents are as follows:In this paper,the volt-ampere characteristics of PV cells and direct-current arcs and their influencing factors are introduced.Through the analysing of the equivalent circuit,it explains how the arc fault reduces the PV output and gives the changing rule of the operating point before and after the arc.Based on the mechanism of the DC fault arc and UL 1699B standard,the test platform is built,and the series arc fault test of the PV system is designed.According to the deviation of the operating point from the original volt-ampere characteristic curve after an arc fault occurs,a method for detecting the arc fault is proposed.C₁ and C₂ can describe the volt-ampere characteristic curve of the PV system.Solar irradiance S and temperature T can distinguish arc fault from normal environmental fluctuation.This paper also gives the flow chart and calculation method for identification of characteristic parameters during the operation of the PV system.To improve the recognition ability of the transient process and the adaptability to the environment,a method based on the fuzzy neural network was choosed.The Takagi-Sugeno type is established.After training and testing,a high-precision model of arc fault recognition is obtained.Compared with BP neural network,it has better performance in the recognition of the transient process.The off-line test shows that the proposed method is reliable and feasible for detecting series DC arc in the PV system.