Topic
Electrical impedance
About: Electrical impedance is a research topic. Over the lifetime, 36015 publications have been published within this topic receiving 371891 citations. The topic is also known as: electrical impedance & complex impedance.
Papers published on a yearly basis
Papers
More filters
TL;DR: It is shown that the conductivity distribution in the field can be estimated from the impedance data obtained for the body surface leads and the finite element model must be chosen properly to provide the unique solution.
Abstract: A simulation study of electrical impedance computed tomography is presented. This is an inverse problem. A field is discretized by the finite element method and an iterative approach derived from the sensitivity theorem is examined for leads taken on the field surface. It is shown that the conductivity distribution in the field can be estimated from the impedance data obtained for the body surface leads. Simulation suggests the availability and the limitation for impedance plethysmography application. The finite element model must be chosen properly to provide the unique solution.
283 citations
TL;DR: Investigating the electrical impedance properties of rat lung and other tissues ex vivo using Electrical Impedance Spectroscopy confirmed the close relationship between the structure and the functional characteristic and the impedance values were higher at low frequencies compared to those at high frequencies.
281 citations
TL;DR: In this paper, a new voltage instability risk indicator based on local phasor measurements at fast sampling rate is proposed, based on real-time computation of the Thevenin equivalent impedance of the classic electrical circuit given by an equivalent generator connected to an equivalent load impedance through an equivalent connecting impedance.
Abstract: This paper proposes a new voltage instability risk indicator based on local phasor measurements at fast sampling rate. The effectiveness of the indicator is analyzed at EHV load and ldquotransitrdquo buses. The risk criterion is based on the real-time computation of the Thevenin equivalent impedance of the classic electrical circuit given by an equivalent generator connected to an equivalent load impedance through an equivalent connecting impedance. The main contribution of the paper is the innovating algorithm utilized on the real-time adaptive identification of the Thevenin voltage and impedance equivalents. The algorithm performance is shown through a detailed sensitivity analysis. The paper presents important numerical results from the actual Italian EHV network.
280 citations
TL;DR: A comprehensive overview on the contributions and their classification on the inverter- and grid-side damping measures are presented and some promising damping methods for industrial applications will be discussed.
Abstract: Grid-tied voltage source inverters using LCL filter have been widely adopted in distributed power generation systems (DPGSs). As high-order LCL filters contain multiple resonant frequencies, switching harmonics generated by the inverter and current harmonics generated by the active/passive loads would cause the system resonance, and thus the output current distortion and oscillation. Such phenomenon is particularly critical when the power grid is weak with the unknown grid impedance. In order to stabilize the operation of the DPGS and improve the waveform of the injected currents, many innovative damping methods have been proposed. A comprehensive overview on those contributions and their classification on the inverter- and grid-side damping measures are presented. Based on the concept of the impedance-based stability analysis, all damping methods can ensure the system stability by modifying the effective output impedance of the inverter or the effective grid impedance. Classical damping methods for industrial applications will be analyzed and compared. Finally, the future trends of the impedance-based stability analysis, as well as some promising damping methods, will be discussed.
279 citations
07 Nov 2002
TL;DR: In this paper, a control method in the direct-quadrature (DQ) rotating frame for a single-phase inverter or PFC rectifier is proposed to provide an infinite control gain (theoretically), thus zero steady state error at its fundamental frequency to achieve superior steady state and dynamic performance.
Abstract: A control method in the direct-quadrature (DQ) rotating frame for a single-phase inverter or PFC rectifier is proposed to provide an infinite control gain (theoretically), thus zero steady state error at its fundamental frequency to achieve superior steady state and dynamic performance. This new control method transforms the physical "real circuit", in conjunction with an "imaginary orthogonal circuit", from the stationary frame to the DQ rotating frame so that the steady state voltage/current in the DQ frame become DC variables. The new control concept is validated through a single-phase grid simulator used for utility compatibility tests, as described in IEEE P1547 draft standard, IEEE Std 929, UL 1741 and NYSIR, for single-phase distributed generators (DG), such as residential fuel cell generators or photovoltaic power conditioning systems. Experimental results in steady state with programmable simulated utility line impedance are given along with the dynamic transient response for NYSIR type test. The control concept is also applicable to zero-sequence control for three-phase four-wire systems.
276 citations