Current-Referencing Electrified Synchronous Machine to Emulate a Synchronous Machine via a Voltage-Source Inverter

The gradual decrease of the grid inertia in contemporary power grids is one of the significant problems caused by the expansion of renewable energy sources. As the inertia provided by the kinetic energy in the rotating mass of conventional fossil fuel-based synchronous generator decreases, the stability of the grid frequency deteriorates. Virtual synchronous machines (VSMs) that emulate the properties of a conventional synchronous machine through voltage-source inverters have gained attention as a solution to support the grid frequency. In this study, a current-referencing electrified synchronous machine (CURESYM) is proposed as a new control method that allows an inverter to have properties of a conventional synchronous machine. The CURESYM supports grid frequency through the inertial and damping responses. In addition, the CURESYM regulates the current in the synchronous reference frame according to the intended transient response, which is separately determined from the inertial and damping responses. A droop control was also implemented via current references independent of the damping response. The performance of the CURESYM is verified through experiments. Furthermore, the advantages of the CURESYM are examined by comparing with existing VSM topologies.