Research On Islanding Detection Technology Of Distributed Generation System

With the rapid growth of power load and the diversification of demand, which is based on wind power, photovoltaic power generation and fuel cell power generating unit of the distributed power generation technology in the world get sustainable development, and will be one of the main directions for the development of electric power in the future. Island is one of the main characteristics of distributed generation system. It has important theoretical and practical significance to study the technology of the isolated island detection. In this paper, the research on the detection technology based on the inverter in distributed generation system is studied:Firstly, the detection principle of several kinds of commonly used active frequency shift method were analyzed, and then proposed the mechanism of blind detection method based on active frequency offset and Sandia frequency offset.Secondly, as a criterion for the occurrence of islands based on the variation range of voltage amplitude, frequency, phase and voltage frequency was analyzed in detail, and then this paper proposed the island detection method based on active current interference. The time varying factor is introduced to ensure the accuracy of the isolated island detection. A simulation model is built in MATLAB/Simulink environment, the simulation results show that the proposed method can achieve fast detection of isolated island under the premise of ensuring the quality of output power.Finally, the inverter respectively based on the active frequency drift method and the Sandia frequency shift method and the Sandia frequency shift method for island detection performance was analyzed in detail, then a multiple inverter based on correlation and negative sequence voltage distribution was proposed. A simulation in MATLAB/Simulink environment tested and showed that multiple inverters in parallel operation with different detection method of frequency offsets than single detection has more excellent performance,it can be used as a criterion for the occurrence of islands by negative voltage distribution factors.