Synchronous Fault Compensator for Voltage Sensor-less Grid-Following Power Converters

During the last decade, the penetration of grid-connected RES systems has been in constant increase, forcing those systems interfaced to the electrical grid to improve and design new advanced controllers to maintain the power converter under control. The most extended control for grid-tied inverters is the so-called grid-following control. This structure allows the system to regulate the power exchange to the grid by means of following the electrical grid phase and magnitude. However, on a general basis, this algorithm does not provide any support to the electrical grid during faults, decreasing the overall stability of the system. Over the last few years, virtual synchronous machines (VSM) have been introduced into the power converter control, emulating the behavior of a synchronous generator and creating the so-called grid-forming power converter. This paper proposes a voltage sensor-less synchronous fault compensator that provides some of the synchronous generator features exclusively during transients.