An optimal virtual inertia controller to support frequency regulation in autonomous diesel power systems with high penetration of renewables

This paper addresses the problem of frequency control in autonomous diesel-based power system with high penetration of renewables. Usually, small power systems with high penetration of renewable energies are supplied by one or two small diesel generators, resulting in a system with a relatively low moment of inertia, and which can be susceptible to significant frequency variations. However, frequency regulation can be supported by modifying the inertial response of the system in an artificial way, i.e., by adding a virtual inertia. The latter can be performed by controlling the power electronics interface of a distributed generator or an energy storage unit. In this work, a controller is designed to provide the optimal virtual inertia which minimizes, according to the proposed performance index, variations in the fundamental frequency as well as in the power flow through the energy storage system. The optimal controller is compared by simulations with other virtual inertia control strategies.