Islanding Protection Method In Multi Photovoltaic Power Generation System Under The Mode Of Grid Connected Operation

Distributed photovoltaic power generation system has a lot of advantages,such as,low production cost,rich raw material resources,environmental protection,long service life of power generation equipment,high energy conversion efficiency and so on.At the present stage,fuel resources are increasingly exhausting and peak power load is sharply increasing.As the important supplement of the centralized power supply mode,distributed photovoltaic power generation system has a broad development space and great application value.However,island effect has the adverse effect on the public power grid,load and power generation system.From the perspective of the security and reliability of the power grid,it is necessary to detect island running state timely and stop the operation of the inverter.Research on accurate,reliable and rapid way of island detection is the precondition of anti-islanding function of grid-tied inverter,which has important theoretical and application value and our paper studies this research.In this paper,based on the photovoltaic power generation system island detection method,firstly,the characteristics of distributed photovoltaic power generation,the cause of island phenomenon and its harm,the importance of distributed photovoltaic power generation island detection and the research status of island detection methods domestic and overseas are introduced.Then,island detection methods of the present stage,island protection test and island strategy are analyzed and discussed.In the discussion of island detection methods,the application difference of certain island detection method in a single grid-tied inverter island detection and many grid-tied inverters island detection is involved,which lays the foundation for research on multi-photovoltaic system grid-tied island detection.In the analysis of island protection test,influence factors of anti-island performance,anti-island test equipment with test steps and anti-island test key indicators are involved.In the discussion of island strategy,the difference between distributed photovoltaic power generation systems running and distributed photovoltaic power generation systems out in the island state and their respective advantages and disadvantages are involved.Again,taking Sandia frequency deviation method,the active frequency shift method,synovial frequency deviation method as examples,multiple grid-tied inverters island detection performance with a single method or multiple methods is analyzed,mainly including the influence of load ratio and chopping coefficient,and the advantages and disadvantages of these methods are compared.Finally,based on the results of theoretical analysis,matlab is used to set up simulation model and verify the correctness of analysis results,which provides reference for the further research work on multiple photovoltaic system island detection method.