Westinghouse Electric

About: Westinghouse Electric is a company organization based out in Cranberry Township, Pennsylvania, United States. It is known for research contribution in the topics: Brake & Signal. The organization has 27959 authors who have published 38036 publications receiving 523387 citations.

UPFC-unified power flow controller: theory, modeling, and applications

Abstract: This paper describes the theory and the modeling technique of a flexible alternating current transmission systems (FACTS) device, namely, unified power flow controller (UPFC) using an Electromagnetic Transients Program (EMTP) simulation package. The UPFC, in this paper, consists of two solid-state voltage source inverters which are connected through a common DC link capacitor. Each inverter is coupled with a transformer at its output. The first voltage source inverter, known as a static synchronous compensator (STATCOM), injects an almost sinusoidal current, of variable magnitude, at the point of connection. The second voltage source inverter, known as a static synchronous series compensator (SSSC) injects an almost sinusoidal voltage, of variable magnitude, in series with the transmission line. This injected voltage can be at any angle with respect to the line current. The exchanged real power at the terminals of one inverter with the line flows to the terminals of the other inverter through the common DC link capacitor. In addition, each inverter can exchange reactive power at its terminals independently. The functionalities of the models have been verified.

Effect of cu-o layer spacing on the magnetic field induced resistive broadening of high-temperature superconductors

Abstract: For H‖c-axis, the magnetic field induced broadening of the resistive transitions of high-Tc superconductors (HTS) is shown to depend strongly on the Cu-O layer spacing. For the highly anisotropic HTS, we show experimental evidence that flux motion results from a thermally activated crossover from three dimensional (3D) vortex lines to 2D independent pancake-like vortices in the Cu-O layers, which is intrinsic to the material and occurs when kBT exceeds the Josephson coupling energy of these layers. At low temperatures, however, thermally activated conventional depinning (which can be sample dependent) or melting in the uncoupled 2D Cu-O layers is also required for flux motion. For YBa2Cu3O7, this dimensional crossover does not occur belowHc2, presumably because the conducting Cu-O chains short-circuit the Josephson interlayer coupling, leading to better superconducting properties in a magnetic field. These results show that strong interlayer coupling is a key to finding good alternatives.

Fracture energy of an epoxy composite system

Abstract: Fracture energy data are presented for an epoxy-alumina trihydrate composite system in which both the volume fraction and particle size of the dispersion were changed. These data show that the fracture energy of a brittle epoxy composite can be significantly increased by choosing the proper volume fraction and particle size of the dispersed second phase. The results are discussed in terms of several mechanisms which could account for the observed increase in fracture energy. A recently proposed mechanism of crack interaction with a second phase dispersion is qualitatively consistent with these results.

Composition and transport properties of SF 6 and their use in a simplified enthalpy flow arc model

Abstract: The equilibrium composition of SF 6 was calculated for temperatures from 1000 to 45 000°K and for pressures from 1 to 16 atm. The usual thermodynamic functions and transport properties were also computed. Considering the arc column in axially flowing gas as a plasma generator, the power balance and momentum conservation equations are formulated and solved with certain simplifying assumptions. The solution gives the developing flow and electrical parameters as a function of distance along the nozzle. Arc voltages are predicted which agree with available data. Clarification is given on two processes contributing to dielectric recovery: axial sweeping away of the arc channel, and its conductance decay by thermal diffusivity, during the current fall approaching current zero.