Abstract: The second order generalized integrator-frequency locked loop（SOGI-FLL）is usually used to realize virtual inertia control of the energy storage converter（ESC）. However,However, it is easy to be disturbed by the characteristic sub-harmonics contained in the grid voltage and has the problem of high frequency ripple. To deal with this problem,this paper investigates an improved virtual inertia control method using a frequency adaptive notch filter based improved SOGI-FLL（ISOGI-FLL）,which takes into full consideration the limited filtering capacities of the SOGI-FLL. In addition,the parameter design method of ISOGI-FLL is presented. Its effectiveness is verified and analyzed by Matlab/Simulink simulation results. Finally,the proposed strategy is demonstrated in detail and validated with a mircogrid consisting of a 440 kW-diesel generator set and two 100 kVA-ESCs under various conditions.