Analysis of AC dispatchable microgrid during grid-connected and isolated modes transitions

Abstract

This paper analyses operation mode transitions of a dispatchable microgrid based on Diesel gensets connected to back-to-back converter working as grid-supplying or grid-forming. A structure to determine the operation mode is based on abnormal frequency and grid voltage level and its dynamical behaviour is depicted. Besides, a smooth phase adjusting is designed to allow reconnection of grid utility without interruption. Considerations of current and voltage controllers applied in this AC microgrid are addressed. Simulation results are presented to show the effectiveness of proposed scheme, complying with clearing time and synchronization parameter limits recommended by IEEE Std. 1547-2003.