Improvement And Evaluation Of Power Quality In Distributed Photovoltaic Grid Connection

Photovoltaic power generation technology is one of the major research trends in the application of solar energy.Therefore,photovoltaic power generation technology has become a research hotspot and trend in the world.With the rapid popularization of photovoltaic power generation,the related technologies for photovoltaic grid-connected power generation have important theoretical significance and high practical value.The research object of this paper is the photovoltaic grid-connected power generation system.The research focus of this paper is the improvement and evaluation of the power quality indicators in distributed photovoltaic grid-connection.Through reading previous literature in relevant fields,based on the analysis and summarization of predecessors’ research results on power quality issues,combined with the inherent characteristics of distributed photovoltaic power generation systems,a photovoltaic power generation system simulation model was established,and Fourier analysis tools were used to study distributed photovoltaic power generation.The problem of power quality of the main power distribution network connected to the power generation system of the grid and the improvement and evaluation methods of power quality are proposed.The specific research work has the following points:(1)The solar power generation technology was introduced.The structural characteristics of the distributed photovoltaic power generation system and the research status at home and abroad were reviewed.The possible effects of distributed photovoltaic power generation after grid connection were analyzed.(2)A brief introduction to power quality was conducted,and various standard documents for power quality in photovoltaic grid-connected power generation in China were collected,and the evaluation process and evaluation methods for power quality indicators in grid-connected power were put forward.(3)The principle and modeling method of fast Fourier transform are introduced,and its application advantages in power quality analysis are discussed.(4)Based on Matlab/Simulink platform,set up a simulation model of a single photovoltaic power station connected to the distribution network,and use the FFT tool in the software to analyze the single from the four aspects of harmonics,voltage deviation,voltage fluctuation and flicker,and three-phase unbalance.And then analyzing the impact of the photovoltaic power plant access to the distribution network,and finally propose a reactive power compensation method for the photovoltaic power station to access the distribution network.(5)Based on the Matlab/Simulink platform,set up a simulation model for a photovoltaic power generation system with multiple distributed photovoltaic power stations connected to a distribution network,and use the FFT tool in the software to analyze the harmonics,voltage deviations,and voltage fluctuations.And then analyzing the impact of photovoltaic power stations access to distribution network,and finally propose reactive power compensation method for photovoltaic power stations access distribution network.(6)This paper briefly introduces the possible hazards and causes of the connection of photovoltaic grid-connected power generation system into the distribution network.Then,through modeling and simulation,the method of using LC filter to improve harmonics in photovoltaic grid-connected grids is verified.The simulation results show that the LC filter used in this paper can improve the harmonic distortion in distributed photovoltaic gridconnected networks.Finally,the power quality improvement measures are proposed.