A novel control scheme based on a new stochastic equivalent model of the power system, which provides flexible inertia constant to enable high penetration levels of microgrid (MG) generation, is proposed. The approach combines an adaptive energy storage system (ESS) dispatch strategy with an MG-controlled islanding scheme to provide frequency support for the host power grid. First, a center-of-gravity (COG) formulation of the inertia-control scheme is proposed, in which the unbalance torques between the control areas and the COG are used to reduce frequency deviations. An application example-based equivalent model of ESSs as seen from the grid side is then proposed that takes advantage of the ESS special attributes to contribute to inertial response. Simulation results on two test systems demonstrate the efficiency of the proposed control scheme to increase the host grid ability to efficiently integrate multiple MGs. Numerical tests suggest that the proposed control scheme increases system penetration level at least by 12%, which justifies the use of inertia emulation techniques to accommodate higher levels of distributed generation.
