Methods for multi-functional converter control in micro-grid

The operation of micro-grid based renewable energy usually considers efficiency and economy in comprehensive. The control strategy based on master micro-source (MS) constant voltage constant frequency (CVCF) networking is introduced. The voltage and frequency of micro-grid is established by the master MS, and the slave MS operated on the maximum power point tracking mode, in order to achieved micro-grid efficient and economic operation. For improving the function of each MS in micro-grid, a multi-functional convertor operation strategy is proposed. According to this strategy, the master MS has the function of forming micro-grid and switching to the public grid seamlessly, while the slave MS has that of MPPT and energy exchange. The seamless transfer technology for micro-grid is introduced. The control strategy of master MS constant voltage constant frequency networking is used in the grid seamless transfer. The grid-connected and off-grid processes of the MS control topology are analyzed and experimentally studied. The results have showed the effectiveness of proposed control technology, which has the advantages of less impact on local sensitive load, easy hardware implementation and good system stability.