Research On Fault Identification Method Of DC Series Arc In Photovoltaic System

Relying on its advantages of no fuel consumption and no pollution,photovoltaic power generation had made an important contribution to easing the pressure brought by global warming and the increasing shortage of traditional fossil energy.In recent years,the PV industry had witnessed rapid growth,and at the same time,it faced problems such as aging of some equipment,which was likely to lead arc failure at a large number of connection points,even bring about serious fire.Considering that the output characteristics of PV cells and gaseous fault arc were greatly affected by the surrounding environmental factors,it was more difficult to detect the arc fault.Therefore,it was necessary to extract the characteristic quantity of the arc fault and make a correct judgment on it.This paper mainly focuses on the DC side series arc fault of PV system.First of all,according to the UL1699 B standard,it established a PV system arc-fault test platform to collect normal and three different states of arc fault working current,and the data can be processed by MATLAB and other application software.Moreover,in the time domain,by analyzing the mean and variance of the current signal,this paper argues that PV systems series dc arc fault was a transition process of two kinds of stationary random signal,which will work under the various states of dimensionless current with finally normalization.The mutation quantity of the current signal was set to fault discriminant basis,through a series of transformation to improve this method.By analyzing distribution of the working current signal in the frequency domain,the information entropy of the fault arc was determined by using fast Fourier transform,that was to extract the amount of collected data information.Finally,the time-frequency domain combined detection method is adopted,and a 5% margin is set to ensure the reliability of the detection device.Through the optimization of the detection design,the identification of the four working states of the PV system is preliminarily realized.Moreover,it was found that the environmental factors and the system itself did not interfere with the identification results,thus verifying the feasibility of the identification method.