Keywords

AC Microgrids, Distributed Control, Cybersecurity, Converter Interfaced Generations, Grid-forming, Grid-following

Abstract

AC microgrids have emerged as key solutions for integrating small-to medium-scale renewable energy resources and battery energy storage systems into modern distribution networks. These resources are connected to the grid through power electronic converters and their associated control system; therefore, they are referred to as converter interfaced generations (CIGs). As modern power systems experience increasing integration of these CIGs, it is critical that their control algorithms effectively regulate microgrid voltage and frequency, ensure fair active and reactive power sharing, and safely ride through abnormal events such as grid faults and overloads.

State-of-the-art microgrid control methods typically use PI control at the inverter-level and droop control at the primary level. However, the PI controllers cannot effectively track oscillating reference currents under unbalanced grid conditions and are prone to integrator windup during faults and overloads. Similarly, the droop control provides poor load-sharing performance in unbalanced and resistive microgrids, which are common in the distribution network. The droop control also leads to steady state error in frequency regulation.

To address these limitations, this dissertation proposes a nonlinear inverter-level controller and a droop-free distributed primary-level controller. The inverter-level controller is developed using the recursive feedback design principle on the AC side and the direct Lyapunov design principle on the DC side for a photovoltaic-based CIG. The distributed primary controller is developed using the cooperative control principle to construct consensus protocols for voltage and frequency regulation as well as fair active and reactive power sharing among CIGs. Since the communication network is integral to the distributed controller, the system is also vulnerable to cyberattacks, including false data injection and denial-of-service attacks. Accordingly, this dissertation further proposes a resilient distributed control framework based on the competitive interaction principle.

Completion Date

2026

Semester

Spring

Committee Chair

Zhihua Qu

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Electrical and Computer Engineering

Format

PDF

Document Type

Dissertation

Identifier

DP0053126

Release Date

5-15-2028

Download

Available for download on Monday, May 15, 2028

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