Impact of Renewables on Grid Strength, Transient Stability, and Grid Operation Characterization

Increasing amounts of inverter based resources (IBR) are being added to the grid. With environmental and climate change concerns, even more is projected to be added. Many companies and regions are setting goals for high levels of renewables. As IBR are added to the grid, it changes how the power system responds to disturbances. With less traditional synchronous machines on the system, this decreases the inertia and can add stability concerns. Studies are required to know how power systems will respond to the change in generation resources. This dissertation contributes to studying transient stability and grid strength on the North American transmission system to help determine the future state of the system. Monitoring of the power system is also important to provide awareness of the system state. Especially as the generation mix changes and uncertainties are added to the grid, it is vital to have an accurate understanding of whether the system is in normal operation or experiencing stress. It is important to have early awareness of system stress to be able to prevent instability. This dissertation will also explore potential methods to monitor for early awareness of system stress. This dissertation documents the efforts to study and monitor current and future changes on the power system. Chapter 1 presents a study of the impact of high penetration of IBR on grid strength, in both the Eastern Interconnection (EI) and Western Interconnection (WI). Chapter 2 documents a study of the impact of high photovoltaic (PV) penetration on transient stability in the Electric Reliability Council of Texas (ERCOT) System. And Chapter 3 describes an effort to study active power and voltage angle data on the Southern Company system in order to investigate voltage angle difference as an indicator of early event awareness due to stress on the system caused by power flow through an interface