The Control Strategy Of Dual Mode Inverters In Microgrid

In recent years, microgrid grid is paid much attention to the social from all walks of life, it is a new suitable for renewable energy power generation network form after the distributed power generation. But as the energy grid power conversion between the interface of the equipment time and, inverter has been widely used in the new energy distributed power generation system and the microgrid. How to realize the parallel and network organization of many sets of inverter in microgrid and control the inverter flexible switching between the islands and grid modes is the hot issue also the difficulty in microgrid, but also related to the safe and stable operation of the microgrid. This thesis mainly reserch the method of the inverters parallel and network organization in microgrid, researching the inverter control strategy in the island and synchronize and discusses the mode of switching method. The main contents of this thesis are as follows:Firstly, after analyses of the traditional distributed generation system are different from the microgrid technology, this thesis sums up several existing applies to the microgrid, then analyze the advantages and applicability of the control strategies. Later, this paper proposes a kind of control the voltage type grid/island dual mode control strategy, and the control strategy belongs to the voltage type control method, and makes the inverter can switch smooth transition between the grid/island mode. This control strategy base on the droop control, so parallel inverter has the ability of power distribution. Control the voltage type grid/island dual mode control strategy in the island mode,rated given droop control strategy is the main control strategy, incorporated with the control strategy of the drooping power allocation and circulation inhibitory ability, also have the output capacity of the voltage amplitude, frequency stability in U/f control strategy, which makes the grid island operation, which can guarantee inverters power allocation and restrain the circulation between inverters, also be able to overcome weakness of the control voltage output frequency deviation in droop control. And in the grid state, inverter’s outer ring join in a power, make the inverter in the grid state achieve PQ control, inverter no longer provide voltage frequency support, only control the output power of inverter, to make full use of renewable energy effect. This paper built the microgrid inverter control system in the simulation model through the MATLAB/SIMULINK to validate the effectiveness and feasibility of the control strategy.Secondly, this paper design the hardware system of inverter, and introduced all the parts of the hardware system and calculation process, then built the actual experimental platform.Finally, this paper design thesoftware system, gives the control strategy and the software flow chart of each component of system, and operation in the experiment platform, obtained the related experimental data and waveform.