| In 2009, China proposed building a "strong and smart grid" project. According to the plan, the structure of China's future energy will change; the proportion of wind power, solar power, nuclear energy and some other kinds of distributed generation will greatly increase. But if the large number of distributed generation directly connect to the power grid will have cause an impact, so micro-grid technology has been widespread concerned.It introduces several common principles of distributed power generation and system structure, micro-grid concept and development at home and abroad. As the type of distributed generation and micro characteristics of a grid, inverters based on power electronics technology will be widely used in micro-grid. So how to solve the coordination between grid-connected inverter is a key to a micro power grid operation stably, and it is also the focus of this paper.In this paper, the characteristics of L, LC, LCL filters are compared by using frequency response. And summarizes the commonly used inverter control methods, and described how to select the LC, LCL filter parameter. And then establish grid-connected inverter model by using the instantaneous voltage and current double loop control and SPWM, design parameters of the controller, and adjust the controller parameters so that the output impedance of the inverter at the frequency will expressed as an inductance,so that it could be used in droop control.Then introduced the existing micro-grid control method, the micro source control consist of power control and voltage control, and using a detection method based on local power, and analysis the parameters of low pass filter used in power detection influence system stability by using small signal model. And design the droop controller based on droop theory, and designed power controller parameters based on standards. Using MATLAB / SIMULINK to simulate single and multi inverters parallel operation; and finally design the hardware based on DSP2812.
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