Virtual inertia is known as an inevitable part of the modern power systems, especially considering the increasing level of power electronic-based component and HVDC interconnection in the future gird. To cope with this challenging issue, a novel approach for modeling and analysis the effect of virtual inertia on frequency stability of multi area interconnected system is proposed. The proposed method is based on Virtual Synchronous Power (VSP) control strategy of HVDC interconnected systems. The presented work is focused on modeling and detailed sensitivity analysis of VSP-based HVDC concept in frequency control and automatic generation control task of interconnected power systems. In order to understand the influence of virtual inertia parameters, a set of sensitivity analysis is performed to identify the proper range of critical control parameters on the stability of the system. The effectiveness of the proposed concept on dynamic improvements is also validated through Matlab simulation of multi-area (two-area and three-area) test systems. The three-area test system is based on complex model of 39-bus, 10 generator test system.