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1. Real Time Simulation of Transient Overvoltage and Common-Mode during Line-to-Ground Fault in DC Ungrounded Systems

   https://doi.org/10.1109/IECON.2019.8927034  

   Vygoder, Mark; Gudex, Jacob; Cuzner, Robert; Milton, Matthew; Benigni, Andrea (October 2019, Annual Conference of the Industrial Electronics Society (IECON))

   Real Time (RT) simulation of Power Electronics (PE) allows engineers to interface real-time controls for controller hardware-in-the-loop CHiL. CHiL verification moves a design from Technology Readiness Level (TRL) 3 to TRL 4. For RT CHiL simulation of DC protection systems, the RT simulation platform must be able to simulate common mode behavior, various grounding schemes, and fault transients at sufficiently high resolution so as not to interfere with the protection system design. This paper demonstrates this capability using a Latency Based Linear Multistep Compount (LB-LMC) simulation method implemented in Field Programmable Gate Arrays (FPGAs), in order to achieve 50ns resolution of common mode behaviors, including Line-to-Ground (LG) overvoltages resulting from LG faults and fault recovery in ungrounded DC systems. This resolution in RT cannot be achieved with today's commercial off-the-shelf (COTS) RT CHiL platforms. Furthermore, this capability can be expanded to other grounding schemes and larger PE networks, enabling RT CHiL validation of protection schemes for networks of power electronic converters at TRL 4. 

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2. Dual State - Parameter Estimation for Series Arc Fault Detection on a DC Microgrid

   https://doi.org/10.1109/ECCE44975.2020.9235753  

   Gajula, Kaushik; Yao, Xiu; Herrera, Luis (October 2020, 2020 IEEE Energy Conversion Congress and Exposition (ECCE))

   null (Ed.)

   In this paper, a detection and localization technique based on dual State and Parameter Estimation (SE and PE respectively) for series dc arc faults is presented. Detection of series arc faults in dc microgrids is challenging due to its low fault current. By using the available set of sensor measurement data over a period of time, a Least Squares (LS) based SE algorithm estimates the dc microgrid's bus voltages and injection currents. Kalman Filter (KF) is then used to estimate the line conductances in the network, which are used to detect and localize (with respect to the faulted line) the series arc fault. Simulation results are presented with different case studies to demonstrate the robustness of the algorithm to normal operating conditions and different number and placement of sensors. Finally, Control Hardware in the Loop (CHIL) results are shown. 

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3. Detection and Localization of Series Arc Faults in DC Microgrids using Kalman Filter

   https://doi.org/10.1109/JESTPE.2020.2987491  

   Gajula, Kaushik; Herrera, Luis (April 2020, IEEE Journal of Emerging and Selected Topics in Power Electronics)

   DC networks are becoming more popular in a wide range of applications. However, the difficulty in detecting and localizing a high impedance series arc fault presents, a major challenge slowing the wider deployment of dc networks/microgrids. In this paper, a Kalman Filter (KF) based algorithm to monitor the operation of a dc microgrid by estimating the line admittances and consequently detecting/localizing series arc faults is introduced. The proposed algorithm uses voltage and current samples from the nodes in the distribution network to estimate the line admittances. By determining these values, it is possible to quickly isolate the faulted section and reconfigure the network after a fault occurs. Since, the disturbance caused by a high impedance series arc fault spreads across almost the entire microgrid, the KF algorithm is structured to detect the faulted line in the grid with precision. Simulation and Control Hardware in the Loop (CHIL) results are presented demonstrating the feasibility of implementation. 

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4. Short Circuit Fault Discrimination Using SiC JFET Based Self-Powered Solid State Circuit Breakers in a Residential DC Community Microgrid

   https://doi.org/10.1109/TIA.2020.2995114  

   Palaniappan, Karthik; Sedano, Willy; Vygoder, Mark; Hoeft, Nicholas; Cuzner, Rob; Shen, John (May 2020, IEEE Transactions on Industry Applications)

   This article identifies and validates the use of ultrafast silicon carbide (SiC) junction field effect transistor (JFET)-based self-powered solid-state circuit breakers (SSCBs) as the enabling protective device for a 340 Vdc residential dc community microgrid. These SSCBs will be incorporated into a radial distribution system in order to enhance fault discrimination through autonomous operation. Because of the nature and characteristics of short-circuit fault inception in dc microgrids, the time-current trip characteristics of protective devices must be several orders of magnitude faster than conventional circuit breakers. The proposed SSCBs detect short-circuit faults by sensing the sudden voltage rise between its two power terminals and draw power from the fault condition itself to turn off SiC JFETs and then, coordinate with no-load contacts that can isolate the fault. Depending upon the location of the SSCBs in the microgrid, either unidirectional or bidirectional implementations are incorporated. Cascaded SSCBs are tuned using a simple resistor change to enable fault discrimination between upstream high-current feeds and downstream lower current branches. Operation of one of the SSCBs and three in cascaded arrangements are validated both in simulation and with a hardware test platform. Thermal impact on the SSCB is discussed as well. The target application is a residential dc microgrid that will be installed as part of a revitalization effort of an inner city Milwaukee neighborhood. 

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5. Protecting Inverter-Based Resources: Transformer Configuration Impacts and Incremental Focused Directional Protection Enhancements

   Hasan, Abu_Shouaib; Fan, Rui (March 2025, IEEE GreenTech Conference)

   Inverter-based resources (IBRs) exhibit distinct short-circuit characteristics that challenge traditional protective relays designed for systems dominated by synchronous generators. While research often focuses on IBRs’ positive-sequence currents during faults, their zero- and negative-sequence responses under unsymmetrical faults remain underexplored. Factors such as transformer configurations and grounding methods further complicate the design of protection schemes relying on these sequence components. This paper enhances the understanding of IBR short-circuit behavior during both symmetrical and unsymmetrical faults and investigates the impact of various transformer configurations on these behaviors. We highlight the limitations of traditional protective relays in safeguarding IBRs due to their constrained fault current levels, minimal negative-sequence components, and, in many cases, the absence of zero-sequence currents. To address these challenges, a novel incremental focused directional protection scheme is introduced. This approach offers enhanced fault detection capabilities under the complex conditions posed by high renewable energy penetration and diverse transformer configurations. The proposed method provides a robust solution for ensuring reliable protection in modern power systems with high integration of IBRs, contributing to improved grid stability and resilience. 

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