Operating Characteristic Analysis of Hybrid AC/DC Microgrid under Energy Internet

Abstract

In order to solve the problems about frequency fluctuation, power allocation between AC and DC sub-microgrid, and operation switching between island and grid-connection mode, a synthetically operation control strategy of hybrid AC/DC microgrid is presented in this paper. As the main converter in AC sub-microgrid, the control strategy of the storage converter adopts the voltage control type virtual synchronous generator (VSG). The bi-directional DC/AC converter coordinates the power exchange between the AC and DC sub-microgrid. And the storage units in DC sub-microgrid automatically and equally sharing power allocation. In addition, the smooth switching of the hybrid AC/DC microgrid is achieved through the pre-synchronization control unit. With MATLAB/Simulink software, it simulates and validates the operation characteristics and control strategies of the hybrid AC/DC microgrid under the grid-connection mode, island mode and different modes switching. The simulation results show that the synthetically operation control strategies can achieve power allocation, smooth switching and stable operation of the hybrid AC/DC microgrid.