Distributed Control Alternatives of Modular Power Converters for Hybrid DC/AC Microgrids

Ahstract-This paper proposes a distributed control alternative for modular power converters. The focus is on the use of single-phase power units with embedded control capabilities, namely intelligent Power Electronics Building Block (iPEBB) for power conversion in hybrid DC/ AC microgrids. The distributed control is achieved by the use of a versatile controller inside each iPEBB, so that they can operate independently by controlling their own voltage(s)/current(s). For the management of the entire system, a central controller is integrated into the control scheme. The central controller is in charge of the application-level control of the modular power converter, so that it determines the role of each iPEBB and commands the references to achieve the control goals. As a demonstration of the proposed approach, the control of a 4-wire 4-leg STATCOM using 4 independent power units is shown in this paper. For the implementation of the iPEBB control system, two different approaches are evaluated: Proportional-Resonant (PR) and Repetitive Control (RC) alternatives. Analysis is done using direct discrete design. Different simulations as well as experimental results are performed in order to validate the proposed system. The study considers communication delays between the central controller and the iPEBB as well as internal reconstruction of the reference from the central controller command.