A Unified Controller for Interconnection of Heterogeneous, Multi-DG Mini/Microgrids With Varying Dynamic Characteristics

Abstract

Realizing the necessity and benefits of integrated operation of multiple microgrids (MGs), this article proposes a unified controller for the interconnection of MGs energized with a variety of distributed generators (DGs), including both rotating machine-based and inverter-based interfacing systems. The developed controller adopts an embedded loop approach that corrects the frequency and phase errors adaptively, thereby eliminating the need for multiloop sequential controllers, and accelerating the alignment of the phase and frequency of incoming MG with that of the existing/reference MG system. The controller tuning process is simplified with the incorporation of rate of change of frequency and an aggregated modeling approach in the design, which enhanced the flexibility and robustness. Care has been taken such that the developed philosophy shall be generic, so that it can be scalable and can be applied to the interconnection of any two MGs, irrespective of the type and number of DGs within each MG, and their time-varying responses. The performance of the developed controller is verified through various numerical simulations and is validated through experiments on a power-hardware-in-loop-based test bed for seamless interconnection, undisturbed power deliveries, and stable post-interconnection operations.