Research On Parallel Node Electrical Monitoring Of Distributed Photovoltaic System

With the rapid development of photovoltaic industry,the power quality and reliability of distributed photovoltaic power station have brought new challenges to the safe and reliable operation of power grid.The real-time monitoring system of photovoltaic power station came into being and has a broad application market.The electrical monitoring technology of parallel network is the core of the real-time monitoring system of photovoltaic power station.The research difficulties are signal denoising and power quality analysis,and fault recording multi threshold trigger technology.In view of these problems,the following work is carried out in this paper:1.This paper designs a real-time monitoring program for photovoltaic power plants.The monitoring system focuses on the data sampling layer,processing layer and display layer,and introduces the three-layer system in detail.Among them,for the data sampling layer,this article focuses on the selection of data collectors,the principle of data acquisition,and the data preprocessing scheme based on wavelet threshold denoising.The signal-to-noise ratio is used as a reference standard.The selection criteria of noise method and threshold are carried out theoretical analysis and related simulation experiments,and finally the best de-noising scheme is obtained,and the wavelet transform parameter values for denoising of grid-connected AC signals are obtained.2.For the power quality analysis module of the data processing layer,this paper designs a specific analysis process for power quality,using fast Fourier transform(FFT)to extract signal feature quantities,and the principle of modulus maximum value to classify signal disturbances,and calculate Disturbance parameters such as voltage fluctuation frequency,harmonic distortion rate,voltage deviation value,etc.,complete the whole process analysis of power quality.3.Regarding the fault recording function in the data processing layer,this paper aims at the problem that short-term disturbance may cause the recording error.Based on the single threshold start algorithm of the fault recording and the gray correlation theory,a composite system in photovoltaic power station is proposed.Threshold-triggered active variable frequency fault recorder start method.This start method analyzes the anti-malfunction and resistance-to-motion correlation analysis of the common analog quantities used in the current fault record criterion to obtain the best anti-malfunction for each analog quantity.And resist the dynamic factor,realize the composite threshold judgment of the fault recorder trigger,and finally put forward the comprehensive fault recorder start criterion based on single threshold and compound threshold,and carry out the active and grading adjustment of the system sampling frequency in real time to achieve high-time implementation and high accuracy.Disturbance recorder function.4.For the data display layer,this paper designs a data display interface based on Labview.The display system integrates data management,power quality monitoring,and photovoltaic power generation operation monitoring modules to achieve human-computer interaction.