Synthetic inertia using synchronous machines interfaced with power electronic converters

In this paper a novel solution is proposed to improve the overall inertial response in a power system. The presented idea consists of grid-interfacing synchronous generators (SGs) of decommissioned power plants with a back-to-back high-power electronic converter (PEC). This system is able to maximize the amount of synthetic inertia which can be provided from such an energy storage unit; specifically, it has been shown through simulation studies that the proposed solution (PEC+SG) is able to provide inertia equivalent to tens of parallel direct-connected SGs of the same type. For this solution, an efficient control system has been developed in order to virtually increase the amount of global inertia in the network while respecting practical limitations of large SGs. The proposed solution has been studied both in a single-machine as well as a multi-machine system, where in the latter case, effectiveness of the proposed system in power oscillation damping (POD) has been demonstrated. Throughout this study, and for various modes of operation, a comparison between the inertial provision of the power electronic interfaced decommissioned synchronous generator (DSG) and the direct grid connection of the same DSG is provided. The validity of the proposed solutions has been verified via simulation studies in the MATLAB/Simulink environment.