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Title: Active Protection Solutions for a Distribution Grid Dominated by Inverter Based Resources
Committee:
Dr. Divan, Advisor
Dr. Graber, Chair
Dr. Saeedifard
Abstract: The objective of this research is to develop intelligent and actively controlled overcurrent (OCP) and overvoltage protection (OVP) devices for power systems with a high penetration of inverter-based resources (IBRs), including but not limited to microgrids. This development is changing the grid paradigm, which is a predominantly radial structure that is centrally controlled and operated. As a result, this evolving grid structure poses new challenges for power system protection due to the change in fault characteristics in such IBR-rich grids. For OCP, the fault current magnitude is significantly limited and variable due to the inherent current limiting of inverters and the diversity of IBR connectivity during a fault. As a result, OCP devices must intelligently detect and trip fault currents while achieving proper protection coordination in dynamically evolving system topologies. For OVP against high energy transient surge events, such as lightning strikes, semiconductor devices in IBRs that are very sensitive to overvoltage must be protected within a small margin of the nominal ratings. At distribution level voltages, state-of-the-art devices, such as metal oxide varistors (MOVs), cannot clamp voltages within this tighter margin. Thus, a new stream of OCP and OVP solutions is needed to provide dynamic, intelligent, and active protection for IBR-dominated grid networks. This research study proposes two new concepts, the iFuse and the iMOV, which are designed to protect such systems in a decentralized fashion to avoid the need for complex, expensive, low-latency communication infrastructure. As a result, the proposed solutions could provide robust, scalable, low-cost OCP and OVP solutions for the modern IBR-rich grid.
