Island Detection Method Based On Positive Feedback Active Frequency Offset Method

With the progress of social economy and the improvement of people’s living standard,energy depletion and environmental deterioration have become increasingly serious problems of globalization.In this context,renewable energy has been booming,among which solar energy has become the most important alternative form of fossil energy due to its many advantages.Solar photovoltaic power generation technology is an important way of solar energy utilization,and in recent years,solar photovoltaic power generation is the most rapid growth,the future of the new photovoltaic power generation project focus will be transformed from centralized to distributed.One hazard that must be taken into account in distributed photovoltaic power generation systems is the island effect.Firstly,the principles of passive method and active method are analyzed and compared.After comparing their advantages and disadvantages,the active frequency method is selected to be improved to meet the requirements of islet detection.The four most commonly used blind area coordinate systems are analyzed and their advantages and disadvantages are compared.Then the coordinate system method is chosen to describe the detection blind area of the improved algorithm.Secondly,after studying the active frequency migration detection method with positive feedback,an improved algorithm is proposed.Aiming at the situation that the power quality is affected due to the large disturbance current in the traditional active frequency migration method with positive feedback,the improved algorithm can make the voltage frequency offset beyond the threshold faster after detecting the island.Based on the working mechanism of the traditional positive feedback active frequency migration method,the feedback function is reset,the migration times are strengthened,and the parameter improvement degree is improved.Through modeling and simulation,the direct influence of the experimental parameters in this method on the effect of isling detection and power quality is deeply analyzed.Finally,using Matlab modeling software,the driving positive feedback active frequency migration method and the improved positive feedback active frequency migration method are simulated and analyzed respectively.The simulation results show that the speed of isling detection is improved,the blind area of isling detection is reduced and the total distortion rate of harmonic current is reduced after the positive feedback function is reset.