Research On Control Technology Of Grid-connection In DC Micro-grid

With the distributed generations such as solar, wind, biomass power generation booming, people have been paying more attention to grid-connection. To avoid the impact to grid when distributed power system connecting to grid, a conception of micro-grid was proposed, which means making the distributed power systems form micro-grid when connecting to grid. DC micro-grid is a system using DC distribution, which has the advantages of high reliability, high efficiency and low line loss, with no need for controlling voltage amplitude and phase. Control of grid-connection is the key technology for DC micro-grid connecting to grid.In this paper, a simulation model of DC micro-grid was built, which consists of solar generation module, wind power generation module, Energy storage module and grid connection module. Simulation results show that the control of each module was successful, and the energy management strategy in DC micro-grid for different modes was successful too.The control technology of grid-connection in DC Micro-grid is the main research object. If a three phase voltage source converter (VSC) was used as a grid-connected interface in DC micro-grid, the fluctuation of DC-bus voltage would appear during an unbalanced grid voltage dip or an abrupt load variation. This paper presented a circuit topology of grid-connected interface and researched its control method, which was modeled and simulated. The simulation results showed that the proposed configuration was able to ensure the capability of bi-directional power flowing and the stability of DC bus voltage. The interface has a high transient performance during faults and disturbance.Finally, Experimental platform based on digital control controller TMS320F2812was built up, The hardware parameters, the software program, control algorithm were designed. The experiment results verified the validity of the control method of Buck converter and three VSC.