About: Impedance matching is a(n) research topic. Over the lifetime, 21532 publication(s) have been published within this topic receiving 254271 citation(s).
01 Feb 1980-
Jr. Ralph W. Wyndrum1•Institutions (1)
01 Jul 1965-
01 Jan 1994-
Abstract: 1 Basic Concepts 2 Transformers 3 The Synchronous Machine 4 Series Impedance of Transmission Lines 5 Capacitance of Transmission Lines 6 Current and Voltage Relations on a Transmission Line 7 The Admittance Model and Network Calculations 8 The Impedance Model and Network Calculations 9 Power Flow Solutions 10 Symmetrical Faults 11 Symmetrical Components and Sequence Networks 12 Unsymmetrical Faults 13 Economic Operation of Power Systems 14 Zbus Methods in Contingency Analysis 15 State Estimation of Power Systems 16 Power System Stability
01 Sep 1996-Medical & Biological Engineering & Computing
TL;DR: It is concluded that the patient's skin should be abraded to reduce impedance, and measurements should be avoided in the first 10 min after electrode placement, to allow satisfactory images.
Abstract: A computer simulation is used to investigate the relationship between skin impedance and image artefacts in electrical impedance tomography. Sets of electrode impedance are generated with a pseudo-random distribution and used to introduce errors in boundary voltage measurements. To simplify the analysis, the non-idealities in the current injection circuit are replaced by a fixed common-mode error term. The boundary voltages are reconstructed into images and inspected. Where the simulated skin impedance remains constant between measurements, large impedances (> 2k omega) do not cause significant degradation of the image. Where the skin impedances 'drift' between measurements, a drift of 5% from a starting impedance of 100 omega is sufficient to cause significant image distortion. If the skin impedances vary randomly between measurements, they have to be less than 10 omega to allow satisfactory images. Skin impedances are typically 100-200 omega at 50 kHz on unprepared skin. These values are sufficient to cause image distortion if they drift over time. It is concluded that the patient's skin should be abraded to reduce impedance, and measurements should be avoided in the first 10 min after electrode placement.
Jian Sun1•Institutions (1)
05 Apr 2011-IEEE Transactions on Power Electronics
Abstract: Grid-connected inverters are known to become unstable when the grid impedance is high. Existing approaches to analyzing such instability are based on inverter control models that account for the grid impedance and the coupling with other grid-connected inverters. A new method to determine inverter-grid system stability using only the inverter output impedance and the grid impedance is developed in this paper. It will be shown that a grid-connected inverter will remain stable if the ratio between the grid impedance and the inverter output impedance satisfies the Nyquist stability criterion. This new impedance-based stability criterion is a generalization to the existing stability criterion for voltage-source systems, and can be applied to all current-source systems. A single-phase solar inverter is studied to demonstrate the application of the proposed method.