The Virtual Synchronous Generator (VSG) improves the frequency stability by introducing the inertia, but it is complex and costly compared to the traditional grid connected mode of Distributed Generation (DG). Its inertia setting is also dispersed. So this paper studies how to increase the virtual inertia in the distributed generation grid connected system more easily and economically. Firstly, this paper analyzes the transient response process of VSG and decomposes the rotor inertia power through the power decoupling. Secondly, based on the characteristics of the rotor inertia power response and the running characteristics of the super capacitor, referring to Static Var Compensator (SVC), the concept of Static Inertia Compensator (SIC) is proposed. Lastly, the simulation model of the static inertia compensator is built in Matlab/Simulink to verify the effectiveness of the proposed idea. The results show that SIC can provide inertia power to the node by detecting the frequency variation. It can improve the inertia of the system and enhance the frequency stability of the system and achieve the effect of frequency stabilization of VSG. This work is supported by National Natural Science Foundation of China (No. 51777120).