Research On Carrier Frequency Band Channel Characteristics Of Photovoltaic Module And Photovoltaic Module String

As a carrier communication method,photovoltaic modules can be used as a carrier for monitoring of the photovoltaic power station without the need to re-establish communication lines and low-cost advantages.In order to realize the carrier communication between the PV modules,it is necessary to study the characteristics of the carrier frequency band channel of the PV module and PV module string.In this paper,based on the research of the PV cells,PV module and PV module string of AC/DC equivalent circuit model and equivalent circuit model parameters calculation method,a method of fitting the impedance frequency characteristic curve of PV module by nonlinear least squares algorithm and calculating AC equivalent circuit parameters of carrier wave band of polysilicon PV module is given.According to the measured impedance characteristics and AC impedance equivalent circuit model of the PV module,the parameters of the AC equivalent circuit of the PV module in the absence of light and illumination are deduced.Compared with the existing calculation methods,this proposed method can not only characterize the variation of equivalent circuit parameters of PV module with frequency,but also the calculation process is simple and the calculation results are more accurate.The source and characteristics of serial channel noise of PV are analyzed in detail.The circuits for measuring the serial channel noise of PV module is designed,and then collect the inherent noise of the PV module string channel and the noise when the inverters are working,analyzes the noise from the time domain,frequency domain and time-frequency domain,summarizes the characteristics of noise.Finally,a model of PV module string channel noise based on PSO-BP neural network is given to model the channel noise,the measured noise is modeled by PSO-BP neural network.Then compared its modeling result with BP neural network,the PSO-BP is effective to model the PV module string channel noise.This paper establishes a theoretical basis for the design and communication protocol of follow-up filter in PV power plant monitoring system,and it is an important reference for future PV string as carrier channel mature applied to PV power station monitoring.