Reserch On Islanding Detection Method For Photovoltaic Grid-connected Power Generation System

With the rapid development of photovoltaic power generation technology,the penetration rate of distributed grid-connected power generation system based on renewable energy is increasing year by year.Distributed grid-connected power generation system can improve the flexibility and reliability of the power supply,but also produce islanding,cause serious harm to electrical equipment and personal safety,fast and reliable islanding detection method is very important for islanding prevention of distributed grid-connected power generation system.Therefore,island detection method of photovoltaic(pv)grid power generation system were studied.This paper analyzes the island detection technology of photovoltaic grid-connected power generation system,introduces the characteristics of existing island detection methods,and summarizes the advantages and disadvantages of active and passive detection methods.The equivalent circuit model of islanding effect is established,and the power relation expression is deduced to study the relationship between power,frequency and voltage when islanding effect occurs.At the same time,aiming at the island effect,the principle of island detection method under the condition of single inverter and multi inverter is analyzed.In view of the existing defect detection method based on maximum power tracking island,puts forward a applicable to the changeable environment based on the improved algorithm is a new method for the detection of bionic intelligent island,whales by improving the nonlinear strategy,introducing the chaos optimization algorithm,improve global exploration ability of the algorithm,and local accuracy,and through the benchmark test function with the original algorithm,the algorithm is verified effective Superiority.The experimental simulation platform of island detection is built,and the results show that the improved island detection method has better effectiveness and stability.Inverter island more than passive detection method in detecting the presence of dilution effect and the characteristics of the disturbance of power quality,combined with the wavelet signal,based on the analysis of the wavelet transform is applied to the inverter type island detection method,and the establishment of simulation model,validated in different cases,the results show that the improved island detection method has validity,and can identify false island.