Fault Location Using Sparse Wide Area Measurements
Transmission line fault location allows quick repair of the damage caused by the fault and timely restoration of the line affected by the fault. Accuracy of the fault location is quite important since it affects repair crew’s ability to physically locate the damage part quickly. Typically, the desirable accuracy is to be able to locate a fault within a span of the transmission line towers. This paper presents a new fault location scheme which uses synchronized phasor measurements from different substations sparsely located near the region where the fault has occurred. When fault occurs different Intelligent Electronic Devices (IEDs) such as Phasor Measurement Units (PMUs) and Digital Fault Recorders (DFRs) connected to Global Positioning System (GPS) receivers and installed in some of the substations in the region will be automatically triggered by the change in monitored signals and will record corresponding current, voltage and status signals. Apart from these sparse measurements, the proposed method also uses SCADA PI Historian data which is utilized for tuning the power system model data with the pre-fault condition in real time information. The paper presents how the technique is implemented and shows test results using actual power system model as well as actual field data from a utility company that supported demonstration of the technique. The results are quite encouraging since the sparse measurement problem for such unique transmission line configurations does not allow any other known techniques to produce accurate and reliable results while the proposed technique produces satisfactory results.
The Fundamental Concept of Unified Generalized Model and Data Representation for New Applications in the Future Grid
The concept of interoperability of data and model as presented in this paper is viewed as being very useful for implementing variety of future applications related to power system monitoring, protection, control and operation. To illustrate the proposed concept, two applications are used: state estimation and fault location. Generalized State Estimators (GSEs) consider both measurements and switching device statuses as variables to be estimated. We propose a unified generalized state estimator that uses only one class of network objects (node-breaker), which would avoid model conversions, enables unified topology processing, and supports flexible forms of generalized estimation. The proposed Fault Location (FL) application uses different types of measured data which utilizes power system static data modeled using bus-branch. Significant number of mappings is required to correlate the measured data and model. It is shown that both applications will be simplified if unified generalized representation of data and model as suggested in this paper is utilized.
Pharmacokinetics of Mivacurium Isomers and Their Metabolites in Healthy Volunteers after Intravenous Bolus Administration
Background Previous studies report the pharmacokinetics of mivacurium isomers after an infusion using venous blood sampling. Although the extent of the mivacurium arterial‐venous gradient is not known, the sampling site is likely to influence mivacurium pharmacokinetic parameters because the drug is rapidly metabolized as it traverses the circulation. The objectives of this study were (1) to determine the pharmacokinetics of mivacurium isomers in healthy persons after intravenous bolus administration using intensive arterial blood sampling, and (2) to characterize the formation and elimination of mivacurium metabolites in human plasma. Methods Eight persons classified as American Society of Anesthesiologists physical status 1 or 2 who were scheduled to undergo elective surgery under balanced anesthesia received 0.15 mg/kg mivacurium chloride as an intravenous bolus. Arterial blood samples were collected every 10 s during the first 2 min and at frequent intervals for 4 h thereafter. Plasma concentrations of mivacurium isomers and their metabolites were determined by two stereoselective high‐performance liquid chromatographic methods coupled with fluorometric detection and noncompartmental pharmacokinetic parameters. Results Mean elimination half‐lives of the trans‐trans, cis‐trans, and cis‐cis isomers were 2.4, 2, and 28.5 min, respectively, with corresponding mean plasma clearances of 29.2, 45.7, and 6.7 ml [center dot] min‐1 [center dot] kg‐1. The volumes of distribution at steady state of the trans‐trans, cis‐trans, and cis‐cis isomers were 0.047, 0.054, and 0.189 l/kg, respectively. Plasma concentrations of monoester and alcohol metabolites peaked 25 s (median) after mivacurium injection, with half‐lives in the range of 90 min, except for the cis alcohol metabolite, which was only negligibly and transiently formed. Conclusions Substantial hydrolysis of mivacurium isomers by cholinesterases was confirmed by the rapid appearance of mivacurium metabolites in plasma. The intensive arterial sampling proved to be critical for the trans‐trans and cis‐trans isomers because the area under the curve between 0 and 2 min accounted for 75% and 86% of the total, respectively.