Dissipativity-Based Co-Design of Distributed Controllers and Communication Topology for Resilient AC/DC Microgrids

ABSTRACT

Microgrids interconnect distributed generation (DG) units, transmission lines, and loads into a networked system that must operate reliably in both islanded and grid-connected modes. Two control objectives are central: accurate voltage regulation at each DG bus and proportional power sharing among the DGs. Droop control, the conventional solution, imposes an inherent trade-off between these objectives and its performance deteriorates in the presence of nonlinear loads and converter input limits. Distributed droop-free schemes eliminate this trade-off, but their performance depends critically on the underlying communication topology, which is typically selected a priori and independently of the controller design.

This talk presents a dissipativity-based framework in which the distributed controllers and the communication topology are co-designed simultaneously. Each subsystem, DG, line, and load, is characterized by its passivity indices, and closed-loop stability and performance of the interconnected system are certified by conditions on these indices together with the interconnection matrix. The resulting conditions are formulated as linear matrix inequalities (LMIs), so that the controller gains and the communication graph are obtained from the solution of a single convex optimization problem. The formulation further allows the communication cost to be balanced against closed-loop performance without any loss of the stability guarantees.

The talk covers the extension of this framework from linear DC microgrids to more realistic settings, including constant-power load, converter input saturation, and AC microgrids in the dq frame, where the control objectives extend to active and reactive power sharing and frequency synchronization. Simulation results on multi-DG testbeds in MATLAB/Simulink validate the proposed designs.

BIOGRAPHY

Mohammad Javad Najafirad is a Ph.D. candidate in the Department of Electrical and Computer Engineering at Stevens Institute of Technology, advised by Prof. Shirantha Welikala. His research develops dissipativity-based methods for the joint design of distributed controllers and communication topologies in AC and DC microgrids. His work has appeared at the European Control Conference (ECC) and the Conference on Decision and Control (CDC), and was a Best Paper Award finalist at the American Control Conference (ACC). He is an IEEE member and serves as a reviewer for the Power and Energy Society.