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32 results on '"Ferrari, Maximiliano"'

13. Real-Time Model-Adaptive Relaying Applied to Microgrid Protection

Author

Ferrari, Maximiliano, primary, Smith, Travis, additional, Shepard, Neil, additional, Sundararajan, Aditya, additional, Herron, Drew, additional, Piesciorovsky, Emilio, additional, Snyder, Isabelle, additional, Ollis, Ben, additional, Hambrick, Josh, additional, Sticht, Chris, additional, and Marshall, Mike, additional

Published
2023
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17. Power Flow Models of Grid-Forming Inverters in Unbalanced Distribution Grids

Author

Li, Dingrui, Su, Yu, Wang, Fred, Olama, Mohammed, Ollis, Ben, and Ferrari, Maximiliano

Abstract

Load unbalance in electric distribution systems is unavoidable. Unbalanced load currents will lead to negative sequence (NS) voltages that may damage electric equipment. Unbalanced power flow analysis is a common tool to detect and mitigate NS voltage issues and requires accurate models of grid components. While traditional source models are available, grid-forming (GFM) inverter models are not well developed. GFM inverters implement various control strategies, which affect their power flow models. In this article, a novel GFM inverter model considering control effects is proposed. We show that for some control methods, unbalanced system loading will lead to unbalanced terminal voltages of the GFM inverters, which are modeled through an equivalent negative sequence impedance. The proposed models are initially validated using a simple test circuit. Then, they are applied in the power flow analysis on the IEEE 13-bus and 34-bus systems to demonstrate the accuracy improvement over the state-of-the-art. Using time-domain simulations as benchmarks, we show that the proposed models reduce the calculation error of negative sequence voltages by at least 25% in unbalanced distribution systems.

Published
2024
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32. Protection of Grid-Tied and Islanded Systems with High Penetration of Inverter-Based Resources

Author

Ferrari, Maximiliano F

Subjects
Microgrid protection, LVRT, adaptive protection, overcurrent protection, DFIGs, high current inverter, Electrical and Electronics, Power and Energy
Abstract

This dissertation proposes protection solutions to challenges introduced in power systems with high penetration of renewable energy sources. The distinct protection challenges that emerge in both islanded and grid-tied systems are explored. For islanded systems, the main protection challenge relates to the low-short circuit currents of inverter-based resources (IBRs). As a solution, a novel approach that addresses the root problem is proposed that can increase the short-circuit contribution of a generic voltage source converter. The proposed design allows the inverter to provide sustained short-circuit current to achieve fuse-relay and relay-to-relay coordination. Adaptive relaying for microgrid protection in islanded and grid-tied mode is analyzed. An adaptive relay adjusts the relay curves based on the available generation and the network topology. The model-adaptive relay is validated in hardware and hardware-in-the-loop (HIL) and was deployed at EPB control center microgrid. A power amplifier is designed to interface protective relays with protective relays, which is used to evaluate the model-adaptive relay in the laboratory. For grid-tied systems, this dissertation explores the impact of voltage dips in wind turbine doubly fed induction generator (DFIG) and photovoltaic (PV) systems while also presenting solutions to improve their low-voltage ride through (LVRT) capabilities. The development of a real-time simulator is validated against a physical DFIG testbed. The DFIG machine model is compared with physical measurements during balanced and unbalanced grid conditions. The validated model is then used to study the DFIG system during symmetrical and asymmetrical voltage sags and to evaluate LVRT strategies. Hardware modifications are applied to significatively increase the reactive power support of PV inverters and demonstrates that increasing the semiconductor’s current rating allows the PV inverter to ride through faults while enhancing their reactive power support during voltage sags. Through detailed electrothermal simulations, this design is shown to be capable of injecting three-times the inverter rated current for enough time to comply with established LVRT requirements.

Published
2023

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