11 results on '"Liao, Yuan"'
Search Results
2. Online optimal transmission line parameter estimation for relaying applications
- Author
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Liao, Yuan and Kezunovic, Mladen
- Subjects
Algorithms -- Usage ,Power lines -- Properties ,Estimation theory ,Algorithm ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
Transmission line protective relaying algorithms usually require transmission line parameters as inputs and thus accuracy of line parameters plays a pivotal role in ensuring the reliable performance of relaying algorithms. Online estimation of line parameters is highly desirable and various methods have been proposed in the past. These methods perform well when the measurements utilized are accurate; they may yield erroneous results when the measurements contain considerable errors. Based on nonlinear optimal estimation theory, this paper puts forward an optimal estimator for deriving the positive sequence line parameters, capable of detecting and identifying the bad measurement data, minimizing the impacts of the measurement errors and thus significantly improving the estimation accuracy. The solution is based on the distributed parameter line model and thus fully considers the effects of shunt capacitances of the line. Case studies based on simulated data are presented for demonstrating the effectiveness of the new approach. Index Terms--Bad measurement detection and identification, distributed parameter line model, non-linear estimation theory, transmission line parameter estimation.
- Published
- 2009
3. Fault location for single-circuit line based on bus-impedance matrix utilizing voltage measurements
- Author
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Liao, Yuan
- Subjects
Algorithms -- Methods ,Electric fault location -- Methods ,Electric power transmission -- Methods ,Algorithm ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
Diverse transmission line fault location algorithms have been proposed in the past depending on measurements available. Existing algorithms usually require measurements captured from buses of a faulted line. By taking advantage of the bus-impedance matrix technique, this paper presents a possible fault location approach for single-circuit lines utilizing only voltage measurements from one or two buses, which may be distant from the faulted line. With the addition of a fictitious bus where the fault occurs, the transfer impedances of this bus and other buses are revealed as a function of the fault location. Based on the relationship between the bus voltage change due to fault and the transfer impedance, the fault location can be derived. Shunt capacitance of the line is ignored first and then fully considered based on distributed parameter line model. ElectroMagnetic Transients Program simulation studies have shown quite encouraging results. Index Terms--Bus-impedance matrix, distributed parameter line model, fault location, single-circuit transmission line.
- Published
- 2008
4. Optimal estimate of transmission line fault location considering measurement errors
- Author
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Liao, Yuan and Kezunovic, Mladen
- Subjects
Algorithms -- Usage ,Electric fault location -- Analysis ,Power lines -- Testing ,Algorithm ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
Various transmission line fault location algorithms have been proposed in the past depending on the measurements available. These algorithms perform well when the measurements utilized are accurate; they may yield erroneous results when the measurements contain considerable errors. In some cases, there are redundant measurements available for fault location purposes, and it may be possible to design an optimal estimator for the fault location based on nonlinear estimation theories. This paper aims at proposing a possible method for deriving an optimal estimate of the fault location that is capable of detecting and identifying the bad measurement data, minimizing the impacts of the measurement errors and thus significantly improving the fault location accuracy. The solution is based on the distributed parameter line model and thus fully considers the effects of shut capacitances of the line. Since field data are not available, case studies based on simulated data are presented for demonstrating the effectiveness of the new method. Index Terms--Bad measurement detection and identification, distributed parameter line model, fault location, nonlinear estimation theory, optimal estimator.
- Published
- 2007
5. Accurate Fault Location for Untransposed/Transposed Transmission Lines Using Sparse Wide-Area Measurements.
- Author
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Jiao, Xiangqing and Liao, Yuan
- Subjects
- *
ELECTRIC fault location , *ELECTRIC lines , *SHORT circuits , *PHASOR measurement , *MATHEMATICAL optimization - Abstract
This paper presents a new approach for locating short-circuit faults on untransposed transmission lines. Various fault-location algorithms have been proposed previously for transposed lines, which may not always be the case in practice. Existing methods usually require measurements recorded from one or two terminals of the faulted line, which may not be always available. To complement existing methods, this paper proposes a novel, general fault-location method for untransposed lines using sparse wide-area measurements, which is also applicable to transposed lines. Phasor measurement units are utilized to obtain the sparse wide-area synchronized measurements, which may be captured from buses far away from the faulted line. This method fully considers inherent unbalances of untransposed lines, and fully models shunt capacitances of lines based on a distributed parameter line model. Optimal estimation theory is exploited to make the most of available measurements for enhanced estimation. The method is able to locate faults on single-circuit and double-circuit line configurations, and is immune to fault resistances. Another feature of this method is that it does not require the fault type to be known. Extensive simulation studies using the Electromagnetic Transients Program have been performed, and quite accurate results have been achieved. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
6. Reducing Outages Through Improved Protection, Monitoring, Diagnostics, and Autorestoration in Transmission Substations—(69 kV and Above).
- Author
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Pickett, Bruce, Elkin, Paul, Benner, Carl, Carroll, Patrick, Hataway, Greg, Houser, Keith, Liao, Yuan, Martin, Aaron, Mulawarman, Adi, Mysore, Pratap, Ranieri, Mario, Sufana, Charles, Tengdin, John, Vico, Jakov, and Ware, Don
- Subjects
ELECTRIC power failures ,ELECTRIC substations ,ELECTRIC power transmission ,ELECTRIC relays ,ELECTRIC faults ,PREVENTION - Abstract
This paper primarily addresses the subject of reducing outages or reducing the outage duration, auto-restoration applications for transmission substations, (where “transmission” is defined as 69 kV and higher), and the subject of proactively preventing outages. This paper is a summary of the report of K3-WG for transmission systems. The contribution of this paper includes the presentation of the state-of-the-art, practical techniques and measures for preventing and reducing outages in transmission substations which, if properly adopted, can significantly improve transmission system reliability. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
7. A Fault-Location Algorithm for Series-Compensated Double-Circuit Transmission Lines Using the Distributed Parameter Line Model.
- Author
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Kang, Ning, Chen, Jiaxiong, and Liao, Yuan
- Subjects
PHASOR measurement ,FAULT currents ,POWER transmission ,ELECTRIC potential ,ELECTRIC lines - Abstract
A new fault-location algorithm for series-compensated double-circuit transmission lines utilizing two-terminal unsynchronized voltage and current measurements is presented in this paper. The mutual coupling between the parallel lines in the zero-sequence network is fully considered. The distributed parameter line model is adopted to fully take into account the shunt capacitance of the line. By formulating voltages and currents at the fault point in terms of the unknown fault location, boundary conditions under different fault types are used to derive the fault location. Two subroutines assuming the fault occurs on the left or right side of the series compensator are developed and the principle to identify the correct fault-location estimate is described. Matlab SimPowerSystems is employed to generate cases under diverse fault conditions for validating the proposed fault-ocation algorithm. Evaluation studies have shown that the proposed algorithm has achieved quite accurate results. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
8. Double-Circuit Transmission-Line Fault Location Utilizing Synchronized Current Phasors.
- Author
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Kang, Ning and Liao, Yuan
- Subjects
- *
ELECTRIC fault location , *ELECTRIC lines , *FAULT currents , *PHASOR measurement , *ELECTRON tube grids - Abstract
Fault location is considered as one of the essential techniques enabling a smart grid. This paper presents a novel fault location approach for double-circuit transmission lines. Various existing algorithms usually require measurements recorded from one or two terminals of the faulted line. However, when such measurements are not available, these methods are not applicable. To fill this gap, this paper proposes a fault location method by harnessing current measurements from one or more branches, which may not be necessarily taken from the faulted section. The currents from multiple branches are synchronized and can be obtained from phasor measurement units installed in the system. The bus impedance matrix technique is exploited to develop the new method. The shunt capacitance of the line is fully considered by utilizing the distributed parameter line model. The network data are assumed to be available. When multiple synchronized current measurements are available, an optimal estimator capable of identifying possible bad measurement data and, thus, further enhancing the fault location is also proposed. Quite accurate results have been achieved based on simulation studies. [ABSTRACT FROM PUBLISHER]
- Published
- 2013
- Full Text
- View/download PDF
9. Double-Circuit Transmission-Line Fault Location With the Availability of Limited Voltage Measurements.
- Author
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Kang, Ning and Liao, Yuan
- Subjects
- *
ELECTRIC lines , *ELECTRIC impedance , *ELECTRIC fault location , *ELECTRIC potential , *ELECTRIC measurements , *ELECTRONIC circuits , *DISTRIBUTED parameter systems - Abstract
This paper presents a new approach for locating short-circuit faults on a double-circuit transmission line. Various algorithms have been proposed previously that usually require measurements recorded from one or two buses of the faulted line. However, such measurements may not always be available in some scenarios, rendering inapplicability of existing methods. To complement existing methods, this paper proposes a novel, general fault-location method by harnessing voltage measurements at one or more buses, which may not be taken from the faulted line. The bus impedance matrix of each sequence network with the addition of a fictitious bus at the fault point can be derived as a function of the fault location. The fault location can then be obtained based on the bus impedance matrix and voltage measurements. The distributed parameter line model is utilized. The network data are assumed to be available so that the bus impedance matrix can be constructed. When multiple voltage measurements are available, an optimal estimator capable of identifying bad measurement data is also proposed for enhanced fault location. Since field data are not available at this time, simulated data are utilized for evaluation studies, and quite accurate results have been achieved. [ABSTRACT FROM PUBLISHER]
- Published
- 2012
- Full Text
- View/download PDF
10. Generalized Fault-Location Methods for Overhead Electric Distribution Systems.
- Author
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Liao, Yuan
- Subjects
- *
ELECTRIC fault location , *OVERHEAD electric lines , *ELECTRIC impedance , *ELECTRIC circuits , *ELECTRIC potential , *ELECTRIC charge , *ELECTRIC networks - Abstract
Various methods have been proposed in the past for locating faults on distribution systems, which generally entail iterative procedures. This paper presents novel fault-location algorithms for overhead distribution systems that provide a unified solution that eliminates or reduces iterative procedures applicable to all types of faults. Two types of methods, respectively, for nonradial systems and radial systems have been proposed by utilizing voltage and current measurements at the local substation. The proposed methods are based on the bus impedance matrix, through which the substation voltage and current quantities can be expressed as a function of the fault location and fault resistance, a solution to which yields the fault location. The methods are developed in phase domain and, consequently, are naturally applicable to unbalanced systems. The assumptions made are that the distribution network parameters and topology are known so that the bus impedance matrix can be developed. Simulation studies have demonstrated that both types of methods are accurate and quite robust to load variations and measurement errors. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
11. Guest Editorial Special Section on Frontiers of Power System Protection.
- Author
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Brahma, Sukumar, Das, Ratan, Kezunovic, Mladen, Liao, Yuan, Nair, Nirmal Kumar, Pradhan, Ashok, Redfern, Miles, and Belver, Inmaculada Zamora
- Subjects
POWER system simulation ,ELECTRIC power distribution grids ,ELECTRIC power conservation ,NONLINEAR analysis ,ELECTRICAL surge protection - Abstract
The papers in this special section was conceived with an aim of stimulating forward-looking and transformative ideas and methods that can lead to significant advances in power system protection. Protection is one of the fastest operating functions of a power system, and critical to safety of equipment, and stability of the system. Designed and refined through more than a century of experience, insight, and technological advances, design and implementation of protection has kept power systems exceptionally reliable, considering the fact that the power grid is the largest nonlinear dynamic system in the world, a large part of which is continuously exposed to weather. In recent times, advances in sensing, communication, and computing have potential to refine, or even redefine the conception and implementation of power system protection. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
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