Current Issue:
Best Paper
In order to reward well written paper which makes major contribution to the field of power system control, the best paper is chosen from each released issue. All published papers are judged by Reviewers, Editors as well as Authors using the criteria of accomplishment, innovation, potential impact and presentation. The Author may nominate the best paper sending an email to our editorial office (psc@pwr.wroc.pl) giving details of the chosen paper - but note that Authors cannot vote for their own papers.
Editorial Board has a great honor and pleasure to introduce the Best Papers in particular issues:
2018 - Autumn Issue
CONTROLLING AUTORECLOSING ON OVERHEAD LINES WITH UNDERGROUND CABLE SECTIONS USING TRAVELING-WAVE FAULT LOCATION BASED ON MEASUREMENTS FROM LINE TERMINALS ONLY
The paper explains principles of fault locating based on traveling waves measured only at line terminals for hybrid lines comprising overhead and cable sections. The paper introduces an adaptive autoreclosing control logic to allow or cancel reclosing based on the location of the fault. The paper includes examples that explain and illustrate these principles.
Author(s):
B. KASZTENNY, A. GUZMÁN, M.V. MYNAM, T. JOSHI - Schweitzer Engineering Laboratories, Pullman, WA, USA
Download full text
2017 - Autumn Issue
ANALYSIS OF SYNCHROPHASOR ESTIMATION ERRORS
This paper discusses the analytical analysis of the synchrophasor estimation employed in electrical
systems. Short time Fourier transform with the phase locked loop and Taylor Fourier series are
analyzed for signals relating to different states which may occur in real power systems. The object
is the accurate phasor estimation regardless of the shape of input signal, what for some signal types is
cumbersome.
As a result of active and reactive power disturbance in a power system, the frequency deviation
and amplitude fluctuations may appear in power system signals. As a consequences of short circuits
or overvoltages signal changes occur. This leads to unacceptable errors in short time Fourier transform
resulting from Fourier transform properties. This paper presents character of occurring errors
and their consequences individually for any signal deviation.
Author(s):
Mirosław ŁUKOWICZ,
Szymon CYGAN - Department of Electrical Power Engineering, Wrocław University of Science and Technology, Wrocław, Poland.
Download full text
2016 - Spring Issue
OPTIMIZATION OF CURRENT MAGNITUDE ESTIMATORS BASED ON MARQUARDT–LEVENBERG ALGORITHM
Digital filtering, correlation methods, time delay methods, signal differentiation are the most commonly used methods of estimating fundamental
frequency orthogonal components utilized in magnitude estimators. The foundation for designing filters used in aforementioned methods are usually demanded
frequency responses or signal models with their parameters to be estimated. A weak point of both approaches is frequency-domain modelling ignoring time-domain
performance of the magnitude estimators. In order to fulfil the requirements of protection with the optimum speed for many different configurations, operating
conditions and construction features of power systems, it is necessary to develop magnitude estimator design methods aimed at modelling with respect to high-speed
response with simultaneous acceptable estimation accuracy in the steady state.
The article discusses the implementation of Levenberg–Marquardt algorithm to optimization of current magnitude estimators designed for power system
protection with the focus on estimators used in instantaneous overcurrent relays. The paper presents details of optimizing algorithm, power system model
used for acquisition of signal patterns and estimator performance analyzes.
Author(s):
Mirosław ŁUKOWICZ,
Krzysztof SOLAK,
Paweł WICHER,
Bernard Wiecha - Department of Electrical Power Engineering, Wrocław University of Science and Technology, Wrocław, Poland.
Download full text
2015 - Autumn Issue
ANALYSIS OF FERRORESONANCE OSCILLATIONS IN CAPACITIVE VOLTAGE TRANSFORMER
Analysis of ferroresonance oscillations in capacitive voltage transformer is presented. For this purpose an analytical
approach to ferroresonance is firstly introduced. With use of the harmonic balance method the condition for avoiding stable subharmonic
oscillations of the 3rd mode is stated. In the next step the ATP-EMTP simulation based investigations are carried out to find the
suppression circuit parameter (or parameters) which assure damping of the nonlinear oscillations in accordance to the requirements
of the standards. Two kinds of suppression circuits designed for the considered capacitive voltage transformer construction are investigated.
The possible chaotic phenomena resulting from nonlinear oscillations are also examined. The obtained results are presented and discussed.
Author(s):
Jan IZYKOWSKI,
Eugeniusz ROSOLOWSKI,
Piotr PIERZ - Department of Electrical Power Engineering, Wrocław University of Technology, Wrocław, Poland.
Download full text
2014 - Autumn Issue
TRANSITIONAL PROCESSES AT CAPACITIVE CURRENTS SWITCHING-OFF BY SINGLE AND DOUBLE-BREAK INTERRUPTERS OF VACUUM CIRCUIT BREAKERS
Vacuum circuit breaker technology based on double-break vacuum interrupters has become the most requirements
of high voltage circuit breakers that not environmentally harmful. The vacuum interrupter has an excellent ability to deal with
the steep rising part of the transient recovery voltage, which makes it faster in the current interruption process. This paper presents
results of computer simulations conditioned by capacitive currents switching-offs by using single and double interrupters
of vacuum circuit breakers. These results demonstrate that use of double-break circuit breakers leads to notable decreasing of switching
overvoltages and allows in the same time to meet the dielectric requirements for high voltage vacuum circuit breakers.
Author(s):
Tahir LAZIMOV - Electric Supply and Insulation Chair, Azerbaijan Technical University,
Esam SAAFAN - Electrical Engineering Department, Faculty of Engineering, University of El-Mansoura, Egypt
Download full text
2013 - Autumn Issue
PARK'S TRANSFORMATION BASED FORMULATION FOR POWER SYSTEMS TRANSIENTS DETECTION
This paper presents proposed developments of a new formulation and a full algorithm for transient
detection by applying Park's transformation. This approach consist in transforming three-phase
voltage or current signals into Park's components known as direct, quadrature, and zero axes components.
The input signals are local measurements of a power transmission or distribution system. Then,
transients are superimposed in three-phase signals that can be detected in Park's components through
the finite difference between samples. A full algorithm for the transient detection is presented and
envisions the possibility of being applied in real time. In order to demonstrate the proposed algorithm's
performance, four case studies are considered: capacitor energizing, distribution transformer
energizing, permanent resistive fault, and high impedance fault. These cases were simulated on
a typical Brazilian sub-transmission line using Alternative Transient Program. As demonstrated by
the case studies, the proposed formulation introduces further improvements for transient detection in
power systems.
Author(s):
Renato Gocalves FERRAZ,
Leonardo Ulises IURINIC,
Andre Daros FILOMENA and
Arturo Suman BRETAS - Electrical Engineering Department, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
Download full text
2013 - Spring Issue
TUTORIAL ON OPERATING CHARACTERISTICS OF MICROPROCESSOR-BASED MULTITERMINAL LINE CURRENT DIFFERENTIAL RELAYS
Line current differential (87L) protection schemes face extra challenges compared with other forms of differential protection, in addition to the traditional requirements of sensitivity, speed, and immunity to current transformer saturation. Some of these challenges include data communication, alignment, and security; line charging current; and limited communications bandwidth. To address these challenges, microprocessor-based 87L relays apply elaborate operating characteristics, which are often different than a traditional percentage differential characteristic used for bus or transformer protection. These sophisticated elements may include adaptive restraining terms, apply an Alpha Plane, use external fault detection logic for extra security, and so on. While these operating characteristics provide for better performance, they create the following challenges for users:
- Understanding how the 87L elements make the trip decision.
- Understanding the impact of 87L settings on sensitivity and security, as well as grasping the relationship between the traditional percentage differential characteristic and the various 87L operating characteristics.
- Having the ability to transfer settings between different 87L operating characteristics while keeping a similar balance between security and dependability.
- Testing the 87L operating characteristics.
Author(s):
Bogdan KASZTENNY,
Gabriel BENMOUYAL,
Hector J. ALTUVE and
Normann FISCHER - Schweitzer Engineering Laboratories, Inc.
Download full text
2012 - Spring Issue
GENERATOR SPLIT-PHASE PROTECTION
The stator winding of a hydrogenerator is often made up of coils with multiple turns in the same slot.
It is therefore possible for faults to develop between adjacent turns on the same phase (turn-toturn faults).
These faults cannot be detected by the stator differential protection because there is no difference between
the neutral- and terminal-side currents. Split-phase protection, an overcurrent element responding to the difference between
the currents in the winding parallel branches, is typically provided to detect these faults. Ideally, the split-phase element
should be sensitive enough to detect a single shorted turn. Despite the fact that the current in this turn can be six to seven
times the machine nominal current, the current seen by the split-phase protection can be quite small, in the order of one-twentieth
of the generator full-load current. In addition, a spurious split-phase current can be measured due to current transformer (CT) errors,
saturation during external faults in particular. Therefore, primary considerations in the application of split-phase protection
are the method of measuring the difference in the currents between the parallel branches and the proper selection of the CT used for this purpose.
Author(s):
Sungsoo KIM - Ontario Power Generation
Dale FINNEY,
Normann FISCHER, and
Bogdan KASZTENNY - Schweitzer Engineering Laboratories, Inc.
Download full text
2011 - Autumn Issue
PHASE-LOCKED LOOP TECHNIQUE SYSTEM WITH ORTHOGONAL SIGNAL GENERATOR FOR POWER ELECTRONICS CONTROLLERS
This paper presents a Phase-Locked Loop (PLL) scheme with Orthogonal Signal Generator (OSG).
The proposed technique enables to eliminate the influence of distortions from the observed signal on proper
determination of its parameters as a phase, magnitude or frequency. A simulation model of the system is developed
and results of investigation are provided. Some recommendations on the scheme settings for elimination of harmonic
and inter-harmonic components are also included. It was verified that the proposed PLL with OSG system can be
considered as an useful and effective tool in implementations that require a great accuracy of the phase angle
and frequency estimation. The system could be applied in three-phase power systems control units such as FACTS
converters or doubly-fed induction generators control scheme. Simulation results demonstrate the effectiveness
and robustness of the proposed solution.
Author(s):
Michal WYSZOMIRSKI and
Eugeniusz ROSOLOWSKI - Wroclaw University of Technology, Institute
of Electrical Power Engineering
Download full text
© Copyright by Oficyna Wydawnicza Politechniki Wroclawskiej, Wroclaw 2012
ISSN 2084-2201