Study On The Anti-islanding Detection Based On Energy Storage Inverter

Distributed Generation has the advantages of saving investment, reducing energy consumption, less pollution, high reliability and flexibility. Today, with environmental friendly and energy sustainable development pursued, distributed generation is a supplement to the large power grid, having a good development trend. Energy storage inverter with large capacity can meet the grid’s scheduling need for peak load shifting. And as a kind of distributed power system can make effective use of the electricity. However, with the widely application of the distributed generation system, the probability of occurrence of islanding increases. The security problems caused by islanding can’t be ignored. In this paper, islanding detection technology of energy storage inverter is further studied.This paper introduces the research background, puts forward the significance of the research and summarizes some related issues of the research status at home and abroad. The main circuit topology, control strategy and working principle of the three-phase energy storage inverter system are introduced. Islanding is introduced, including its definition, principle and important problems on islanding detection. A comparison of different island commonly used detection methods is made. A single-phase inverter simulation model is put up to simulate two main detection methods: Active frequency drift(AFD), Mode Frequency Shift(SMS).So that the methods can be discussed in deep and non-detection zones(NDZ) area distribution under certain conditions can be presented.After analyzing the factor causing AFD of single-phase inverter can’t directly be used in three-phase inverter, an improved AFD combining characteristics of AFD and three-phase energy storage control is put forward. And its feasibility is verified in theory and simulation. Then based on relational features between reactive current and common point frequency f, adaptive islanding detection algorithm based on the parameters and direction of iq-f characteristic curve is proposed.The above-mentioned island detection algorithm and the key problems is simulated using Matlab and applied to experimental platform. The simulation and experimental results validate the validity of theoretical analyses and indicate that the proposed algorithm has adaptive direction and adaptive disturbance coefficient.