5 research outputs found

    Analysis and Control of Neutral-Point Deviation in Three-Level NPC Converter Under Unbalanced Three-Phase AC Grid

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    Evaluation of the Performance of Grouting Materials for Saturated Riprap

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    In this study, four types of grout were developed to evaluate the effect of grouting of saturated riprap layers on ground water flow. The developed types of grout are divided into a quick-setting type and a general-type, and also into high and low viscosities. A number of grout tests were performed in a model acrylic chamber, 0.4 m in diameter and 2.0 m in length, for visual observation of injection. To reproduce the field flow condition of the saturated riprap layers (approach flow), the grout tests were carried out at 0 cm/s and 100 cm/s for the flow speed and 10 L/min for the grout injection speed after installing a flow injection opening on the lower part of the chamber. Based on the results of the grout tests, the injection of each grout in the saturated riprap layers was examined to find out the most effective grout

    Arc Stability Control of a High-Power Thyristor Rectifier System in a DC Arc Furnace

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    Fundamental features of the arc stability in a dc arc furnace of 720 V/100 kA/72 MW have been investigated. The Cassie-Mayr arc model has been employed and applied for the target dc arc furnace. In order to characterize the parameters of the Cassie-Mayr arc model and the behavior of unstable arc dynamics, the advanced arc simulations of magneto-hydrodynamics (MHD) have been performed. From the results of MHD simulation, the dc arc dynamic resistance is proposed to be an effective arc stability function reflecting the instability of dynamic arc behavior. A control strategy of the 12-pulse thyristor rectifier system to regulate the arc stability function is also proposed in this paper. The simulation and experimental results confirm the usefulness of the proposed dynamic arc resistance as the arc stability function along with the active control strategy. The proposed arc stability function can be regarded as an effective criterion for the overall power conversion system to maintain highly stable arcing operation leading to better productivity and reliability in a dc arc furnace

    Arc Stability Control of a High-Power Thyristor Rectifier System in a DC Arc Furnace

    No full text
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