State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University), Beijing 102206, China

For the two levels of two-way charging machine, a kind of charge/discharge control strategy is proposed based on the virtual synchronous machine(VSM)in microgrid. First of all, the VSM is applied to control the first-level AC/DC converter, while introducing the virtual inertia, damping and excitation to make the charging machine possess the same operation characteristics as the synchronous machine. Secondly, an auxiliary frequency modulation algorithm is designed by using the active power-frequency operation curve to calculate the “correction of the active power reference” and change the power reference, which makes electrical vehicles participate in the primary and secondary frequency regulation of microgrid. Based on the MATLAB/Simulink, the microgrid model with electrical vehicles is developed. The results show that electric vehicles controlled by the proposed strategy can transmit electricity to the power system, which supports the inertia, damping, voltage and frequency, realizes the non-differential regulation of frequency in microgrid at independent mode, and improves the dynamic stability of microgrid.