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Journal Article•DOI•

Some applications of phasor measurements to adaptive protection

TL;DR: In this paper, the application of microprocessor-based phasor measurements to novel adaptive protection schemes is presented, in which relay characteristics are modified in response to external signals and conditions in the system.
Abstract: The application of microprocessor-based phasor measurements to novel adaptive protection schemes is presented. The concepts of digital adaptive protection in which relay characteristics are modified in response to external signals and conditions in the system, are examined. The importance of real-time phasor measurements in adaptive protection systems is illustrated by two examples. The first involves obtaining synchronizing information about phasor measurements to be used for current differential protection of a multithermal line. By estimating the reference angles for the phasor measurements the effect of synchronized sampling can be obtained without the expense of synchronizing equipment. The second use is the adaptive setting of out-of-step blocking and tripping. Traditional approaches experience problems because the settings are, of necessity, compromises based on offline studies. By reacting to real-time phasor measurements from selected buses in interconnection, it is shown that improved out-of-step blocking and tripping is possible. >
Citations
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Journal Article•DOI•
TL;DR: In this paper, a modified zero-crossing method using curve fitting of voltage samples is proposed, and polynomial fitting of the discrete Fourier transform (DFT) quasi-stationary phasor data for calculation of the rate of change of the positive sequence phase angle.
Abstract: Three new techniques for frequency measurement are proposed. The first is a modified zero-crossing method using curve fitting of voltage samples. The second method is based on polynomial fitting of the discrete Fourier transform (DFT) quasi-stationary phasor data for calculation of the rate of change of the positive sequence phase angle. The third method operates on a complex signal obtained by the standard technique of quadrature demodulation. All three methods are characterized by immunity to reasonable amounts of noise and harmonics in power systems. The performance of the proposed techniques is illustrated for several scenarios by computer simulation. >

379 citations

Journal Article•DOI•
TL;DR: In this article, a method for the computation of fault location in two and three-terminal high voltage lines is presented based on digital computation of the three-phase current and voltage 60/50 Hz phasors at the line terminals.
Abstract: A method for the computation of fault location in two- and three-terminal high voltage lines is presented. It is based on digital computation of the three-phase current and voltage 60/50 Hz phasors at the line terminals. The method is independent of fault type and insensitive to source impedance variation or fault resistance. Furthermore, it considers the synchronization errors in sampling the current and voltage waveforms at the different line terminals. The method can be used online following the operation of digital relays or offline using data transferred to a central processor from digital transient recording apparatus. The authors start with a two-terminal line to explain the principles and then present the technique for a three-terminal line. The technique was first tested using data obtained from a steady-state fault analysis program to evaluate the convergence, observability, and uniqueness of the solution. The technique was then tested using EMPT-generated transient data. The test results show the high accuracy of the technique. >

366 citations

Proceedings Article•DOI•
Arun G. Phadke1•
06 Oct 2002
TL;DR: Synchronized phasor measurements (PMU) were introduced in mid-1980s as discussed by the authors and have been receiving considerable attention from researchers in the field of wide-area measurements in power systems using PMUs and other measuring instruments.
Abstract: Synchronized phasor measurements (PMU) were introduced in mid-1980s. Since then, the subject of wide-area measurements in power systems using PMUs and other measuring instruments has been receiving considerable attention from researchers in the field. This paper provides a historical overview of the PMU development. It is pointed out that the PMU is a direct descendant of the symmetrical component distance relay introduced in the late 1970s. From the early prototypes of the PMU built at Virginia Tech, a commercial product evolved which has been installed in the field at various locations around the world. Applications of PMU measurements to power system operation and control remains a very important subject for current research.

355 citations

Journal Article•DOI•
TL;DR: This bibliography will aid academic researchers and practicing engineers in adopting appropriate topics and will stimulate utilities toward development and implementation of software packages.
Abstract: Phasor measurement units (PMUs) are rapidly being deployed in electric power networks across the globe. Wide-area measurement system (WAMS), which builds upon PMUs and fast communication links, is consequently emerging as an advanced monitoring and control infrastructure. Rapid adaptation of such devices and technologies has led the researchers to investigate multitude of challenges and pursue opportunities in synchrophasor measurement technology, PMU structural design, PMU placement, miscellaneous applications of PMU from local perspectives, and various WAMS functionalities from the system perspective. Relevant research articles appeared in the IEEE and IET publications from 1983 through 2014 are rigorously surveyed in this paper to represent a panorama of research progress lines. This bibliography will aid academic researchers and practicing engineers in adopting appropriate topics and will stimulate utilities toward development and implementation of software packages.

239 citations

Journal Article•DOI•
TL;DR: The use of digital techniques to adapt transmission system protection and control to real-time power system changes is investigated and adaptive strategies that minimize the compromises required and thereby optimize system performance are presented.
Abstract: The use of digital techniques to adapt transmission system protection and control to real-time power system changes is investigated. The discussion covers transmission system protection philosophy, transmission line protection, relay settings, transformer protection, and automatic reclosing. The tradeoff between dependability and security is examined, as well as the various conflicting criteria embodied in transmission line protection. Adaptive strategies that minimize the compromises required and thereby optimize system performance are presented. >

218 citations

References
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Journal Article•DOI•
TL;DR: In this paper, the frequency and rate-of-change of frequency at the bus can also be determined from the positive sequence voltage phase angle, and the theoretical basis of these computations and results of experiments performed in the AEP power system simulation laboratory are also outlined.
Abstract: With the advent of Substation Computer Systems dedicated to protection, control and data logging functions in a Substation, it becomes possible to develop new applications which can utilize the processing power available within the substation. The microcomputer based Symmetrical Component Distance Relay (SCDR) described in the references cited at the end of this paper possesses certain characteristics which facilitate real-time monitoring of positive sequence voltage phasor at the local power system bus. With a regression analysis the frequency and rate-of-change of frequency at the bus can also be determined from the positive sequence voltage phase angle. This paper describes the theoretical basis of these computations and describes results of experiments performed in the AEP power system simulation laboratory. Plans for future field tests on the AEP system are also outlined.

906 citations

Journal Article•DOI•
TL;DR: In this paper, the authors present a state estimation algorithm for the IEEE 118 bus system, which involves an admittance-like matrix with the sparsity of the admittance matrix and converges in one step with the same amount of computation as one iteration of existing estimators.
Abstract: The recent introduction of microprocessors into substations for protection and control makes it possible to measure positive sequence voltage phasors and positive sequence transmission line current phasors in real time. It is necessary to synchronize sampling clocks in various substations in order to put the phasors on a common reference. Techniques for synchronizing sampling along with a method for obtaining positive sequence phasors from samples are reviewed. Although it is possible to use these direct measurements in conventional state estimation algorithms, considerable advantage accrues if the state estimation is reformulated in terms of direct measurements of phasor voltages and currents. The resulting estimation algorithm involves an admittance like matrix with the sparsity of the admittance matrix. The new matrix is real rather than complex even for small X/R ratios for the lines. The algorithm requires no assumptions as to decoupling, flat voltage profiles, small resistance, etc. The algorithm converges in one step with the same amount of computation as one iteration of existing estimators. Examples are given for the IEEE 118 bus system.

437 citations

Journal Article•DOI•
TL;DR: In this article, a review of the techniques for obtaining positive sequence voltage phasors from samples is presented, and techniques for clock synchronization for direct measurement of state vector are reviewed.
Abstract: Recent introduction of microcomputers in substations to assume all substation tasks including protections makes possible accurate real-time measurements of positive sequence voltage phasors. Since static state estimators use measurements of line flows and injections to estimate the positive sequence voltage phasors it is clear that direct measurement of the state vector may be used to enhance state estimation. In order to obtain simultaneous measurements of different buses it is necessary to synchronize sampling clocks at different locations. After reviewing the techniques for obtaining positive sequence phasors from samples. techniques for clock synchronization are reviewed. Data volume reductions possible with direct measurement of state are examined and static state estimators which incorporate direct measurements are presented. Simulation results for the IEEE 118 bus system are presented.

201 citations

Journal Article•DOI•
TL;DR: In this article, the authors derived the performance equation of a high speed distance relay which is based upon the theory of symmetrical components, and a single equation was shown to be adequate for handling all types of faults which are likely to occur on a three-phase power system.
Abstract: The paper derives the performance equation of a high speed distance relay which is based upon the theory of symmetrical components. A single equation is shown to be adequate for handling all types of faults which are likely to occur on a three-phase power system. Errors created by system loading and fault-path resistance are considered. A numerical example illustrates the principle of operation of the relay. The relay is especially suited to a digital computer based protection system.

185 citations

Journal Article•DOI•
P. Bonanomi1•
TL;DR: In this paper, a simple and economical technique for measuring voltage phase angles and generator shaft angles is reviewed, and the principle is briefly exposed and its practical operation is illustrated by an experiment in a real power system.
Abstract: A simple and economical technique for measuring voltage phase angles and generator shaft angles is reviewed. The principle is briefly exposed and its practical operation is illustrated by an experiment in a real power system. Due to the importance of accurate time for this application a short survey on time dissemination systems is included. The main part of the paper is devoted to the possible applications of phase angle measurements for the control and monitoring of power systems. The discussion deals with various topics and makes ample reference to available literature. The paper is intended as an information survey for assessing the practical significance of phase angle measurements

75 citations