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Abstract-To fully understand the dynamic performance of the multiple flexible ac transmission systems (FACTS) devices, a hardware setup is needed to complement software simulation for university research laboratories. This paper presents the schematic and basic controls of a reconfigurable FACTS system that can be used to realize the major voltage-sourced-converter FACTS topologies: the StatCom, the static synchronous series compensator (SSSC), and the unified power-flow controller (UPFC). Furthermore, the state models and control algorithms for the FACTS devices are proposed. The digital signal processor (DSP)-based control system enables new control methods to be rapidly implemented. The comparison of the experimental and simulation results is also provided to verify the proposed controls. The paper culminates in a list of suggested experiments appropriate for an elective/graduate course in electric power systems.Index Terms-Control, flexible ac transmission system, laboratory development.

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Power devices based on the wide-bandgap semiconductors SiC and GaN have many potential advantages compared to conventional Si-based switching devices, especially for renewable energy and smart grid applications. However, while these emerging devices have developed rapidly in recent years, many factors affecting their performance and reliability remain unknown. In this paper, we discuss some of the key results that have been obtained for both SiC-and GaN-based devices under Sandia National Lab's "post-Silicon" power electronics reliability program. State-of-the-art, commercially available 4H-SiC MOSFETs are evaluated for stability under high-temperature over-voltage and pulsed overcurrent conditions. The devices show maximum vulnerability under high-temperature off-state operation at high temperature. The room-temperature pulsed overcurrent operation results in degradation similar to that observed under high-temperature on-state DC conditions, presumably due to overheating of the device beyond its specified junction temperature. Prototype AlGaN/GaN HEMTs with ~1800 V breakdown are evaluated for stability under different bias conditions. Current collapse is observed and analyzed, and trapping components with very different time constants are found to be involved. The specific nature of degradation and recovery depends strongly upon the particular stress bias (gate vs. drain) condition applied.

A technique for characterizing trapped charge in silicon carbide (SiC) metal oxide semiconductor field effect transistors (MOSFETs) based only on the subthreshold I-V characteristics and its degradation under bias temperature stress is described. The method utilizes the large departure of the subthreshold slope from a constant value, due to large and exponentially rising DIT (density of interface traps) near band edges for SiC/SiO2 interface. Elevated bias-temperature stress experiments demonstrate the feasibility of separating ΔNIT (increase in interface trapped charge) from slow trapping components like ΔNOT (increase in oxide trapped charge) with minimal error due to extrapolation of subthreshold current to midgap potentials. A slow trap, dissimilar to either interface or oxide states close to the interface, dominates degradation at elevated temperature.