A Seamless Transfer Strategy Of Islanded And Grid-connected Mode Switching For Microgrid Based On Droop Control

With the increasing depletion of traditional energy sources and the increasing serious environmental problems, new energy and renewable energy have been paid more and more attention by people. Distributed generation technology and microgrid technology have been the hot spot in the industrial and academic research area. Among these technologies, the control technology of the inverter and its parallel operation is an important component of the power electronics, and is also one of the key technologies about distributed generation and microgrid. The inverter parallel technology based on droop control can achieve a better dynamic and steady-state performance, and is flexible to expand. So it becomes the hot spot in inverter parallel aspect. This paper research and discuss the inverter parallel system based on droop control at islanded mode, grid-connected mode and the transferring between this two modes.First, a simple analysis of the voltage source inverter model is given, and it presents the design and optimization of the LC filter and the main hardware circuit. It has also detailed analysis the characteristics of the inverter parallel system based on droop control, elaborated the basic idea about droop control, and introduced an effective power calculation method. The experiment results could verify the correctness of system design. Finally, this paper focuses on the analysis of the inverter parallel system based on droop control at islanded operation and grid-connected operation, and proposes a transfer strategy from the islanded mode to the grid-connected mode. The good simulation results have been got.