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Showing papers in "IEEE Transactions on Power Apparatus and Systems in 1978"


Journal ArticleDOI
TL;DR: A method for determining the unit commitment schedule for hydro-thermal systems using extensions and modifications of the Branch and Bound method for Inteler Programming has been developed and significant features include its computational practicability for realistic systems and proper representation of reserves associated with different risk levels.
Abstract: A method for determining the unit commitment schedule for hydro-thermal systems using extensions and modifications of the Branch and Bound method for Inteler Programming has been developed. Significant features of the method include its computational practicability for realistic systems and proper representation of reserves associated with different risk levels. Contracts relating to power interchange have also been adequately modelled for such an approach.

372 citations


Journal ArticleDOI
TL;DR: In this article, the authors describe the development and evaluation of a method for identifying the coherency behavior of generators for various power system disturbances and use this information as a basis for forming dynamic equivalents which can be applied in transient stability studies.
Abstract: This paper describes the development and evaluation of a method for identifying the coherency behavior of generators for various power system disturbances. This information is used as a basis for forming dynamic equivalents which can be applied in transient stability studies.

364 citations


Journal ArticleDOI
E.P. Dick1, C.C. Erven1
TL;DR: In this article, a frequency response analysis (FRA) method was used to measure wind deformation in power transformers, and the results indicated that benchmark reference data was not always necessary to identify certain kinds of mechanical damage.
Abstract: Winding deformation in power transformers can be measured externally using a new frequency response analysis (FRA) method Field experience since 1975, on five separate transformers up to 550 MVA rating, 230kVclassindicatesthatthismethod hasadvantagesover the low voltage impulse (LVI) method as a practical maintenance tool. Results on suspect transformers indicate that benchmark reference data is not always necessary to identify certain kinds of mechanical damage.

314 citations


Journal ArticleDOI
TL;DR: In recent years, there has been a rapid increase in the number of thyristor-controlled shunt compensators used in industrial and utility systems for dynamic power factor correction and terminal voltage stabilization as mentioned in this paper.
Abstract: In recent years, there has been a rapid increase in the number of thyristor-controlled shunt compensators used in industrial and utility systems for dynamic power factor correction and terminal voltage stabilization. These thyristor-controlled shunt compensators function as variable reactances operated in both the inductive and capacitive domains.

293 citations


Journal ArticleDOI
TL;DR: In this article, the first paper in a two-part report on linear programming (LP) applied to power system security control calculations is presented, where both corrective and preventive security control strategies are dealt with.
Abstract: This is the first paper in a two-part report on linear programming (LP) applied to power system security control calculations. The advantages of an LP approach are complete computational reliabilit and very high speed, making it suitable for real-time or study-mode purposes. Both corrective and preventive security control strategies are dealt with. Active- power control is exercised over generators, phase shifters and hvdc links. Load shedding and emergency start-up of plant are included. Part I presents the basic LP formulation and algorithm, and gives the computational details necessary to obtain very fast solutions. Specific applications to practical power systems are described in Part II1.

248 citations


Journal ArticleDOI
TL;DR: In this article, a technique for the automatic formation of dynamic equivalents of generating units represented by detailed models is described, and a new technique is described for automatically forming dynamic equivalents for generating units.
Abstract: A new technique is described for the automatic formation of dynamic equivalents of generating units represented by detailed models.

210 citations


Journal ArticleDOI
TL;DR: In this article, a traveling wave approach is used to detect and determine the direction to a fault in a few milliseconds, and the first relay system was installed in the USA in Bonneville Power Administration's 500 kV system and represents a substantial contribution to present efforts to shorten fault clearing times as a method to improve system stability and power transfer capability.
Abstract: A new protective relay that solves many of the problems associated with the protection of EHV and future UHV systems is described. Based on a traveling wave approach the relay system operates at ultra high speed and can detect and determine the direction to a fault in a few milliseconds. The relay operating principle, design and application are presented as well as results from computer simulation studies and laboratory tests. The first relay system was installed in the USA in Bonneville Power Administration's 500 kV system and represents a substantial contribution to present efforts to shorten fault clearing times as a method to improve system stability and power transfer capability.

206 citations


Journal ArticleDOI
TL;DR: In this article, a field emission and equi-energy theory is proposed for tree initiation and a derived V-t characteristic explains experimental results better than the common power law (t?V-n) for lifetime.
Abstract: Initiation of electrical treeing in polyethylene is discussed with the emphasis of a charge injection and extraction process, which is considered to feature the incubation period during which there are no apparently visual change and no detectable partial discharges. Some evidences for the process are shown by electrical, thermal and optical liberation of charge injected from a metal electrode into polyethylene. Effects of metal work functions on tree formation are demonstrated. On the basis of the above find- ings, a field emission and equi-energy theory is proposed for tree initiation and a derived V-t characteristic explains experimental results better than the common power law (t ?V-n) for lifetime.

152 citations


Journal ArticleDOI
TL;DR: A practical approach of deriving stabilizing action comparable to that obtainable with accelerating power is described using measurement of electrical power and frequency of a voltage synthesized from machine terminal voltage and current.
Abstract: Use of accelerating power to provide damping of synchronous machine oscillations through supplementary control of excitation has significant advantages. However, true accelerating power derived from Mechanical and Electrical power presents difficult measurement problems. A practical approach of deriving stabilizing action comparable to that obtainable with accelerating power is described using measurement of electrical power and frequency of a voltage synthesized from machine terminal voltage and current.

151 citations


Journal ArticleDOI
TL;DR: This paper presents a new AC load flow method which is several to more than ten times faster than the N-R method and has the same memory requirement, mathematical complexity and accuracy as the N.R method.
Abstract: One of the most recognized load flow methods at present is the N-R(Newton-Raphson) method [1] with the sparsity techniques and suboptimal ordering [2]. This paper presents a new AC load flow method which is several to more than ten times faster than the N-R method and has the same memory requirement, mathematical complexity and accuracy as the N-R method. As an example, the convergence time for 118 bus system was only one eighth of the N-R method.

139 citations


Journal ArticleDOI
A. Miki1, T. Hosoya1, K. Okuyama1
TL;DR: In this paper, a calculation method for impulse voltage distribution in the complex winding arrangement encountered in large power transformers is presented, which takes into account the electrostatic and electromagnetic combinations of windings, and therefore permits a precise analysis of voltage response in the windings to which an impulse voltage is applied and of the transferred voltage in other windings.
Abstract: This paper presents a calculation method for impulse voltage distribution in the complex winding arrangement encountered in large power transformers. This method takes into account the electrostatic and electromagnetic combinations of windings, and, therefore, permits a precise analysis of voltage response in the windings to which an impulse voltage is applied and of the transferred voltage in other windings to which an impulse voltage is not applied directly.

Journal ArticleDOI
Y. G. Bae1
TL;DR: In this article, the authors developed an analytical method to determine the best capacitor locations, reactive compensation level, and yearly loss reductions under a wide range of annual reactive load conditions for use in distribution system design.
Abstract: This paper reports the development of an analytical method to determine the best capacitor locations, reactive compensation level, and yearly loss reductions under a wide range of annual reactive load conditions for use in distribution system design. The results show that, not only is more than 80 percent yearly loss reduction possible with non-switched capacitor banks, but also optimum reacttve-compensation level and maximum yearly loss reduction can be expressed in a simple mathematical equation.

Journal ArticleDOI
TL;DR: In this paper, a control system which modulates power on the Pacific HVDC Intertie to damp oscillations on the parallel Pacific AC Intertie is described, which significantly improves the damping of the Western interconnected power system, which has a long history of periods of negatively damped oscillations.
Abstract: Implementation and operating experience with a control system which modulates power on the Pacific HVDC Intertie to damp oscillations on the parallel Pacific AC Intertie is described. This system significantly improves the damping of the Western interconnected power system, which has had a long history of periods of negatively damped oscillations. The successful operation of dc modulation was a key factor in permitting an increase in the rating of the Pacific AC Intertie from 2100 MW to 2500 MW. This uprating results in large economic and energy conservation benefits.

Journal ArticleDOI
TL;DR: In the real time control of power system, the state estimation function plays a leading role and must detect and eliminate the grossly erroneous measurements.
Abstract: In the real time control of power system, the state estimation function plays a leading role. To perform its task, the estimator must detect and eliminate the grossly erroneous measurements.

Journal ArticleDOI
TL;DR: In this paper, several sources of uncertainty in electric power systems are incorporated into the dynamic stability analysis of the system, with the system model written in state variable notation, and the sensitivites of the eigenvalues of the associate matrix are used to calculate the statistics of eigenvalue locations.
Abstract: In this paper, several sources of uncertainty in electric power systems are incorporated into the dynamic stability analysis of the system. Operating point stability is considered, with the system model written in state variable notation. The sensitivites of the eigenvalues of the associate matrix are used to calculate the statistics of eigenvalue locations. When the uncertainties considered are approximated by the multivariate normal distribution, the probability of dynamic stability is computed using the generalized tetrachoric series. The principle advantages of this method over multiple runs of a deterministic stability study are rapid calculation times and the availability of consistently calculated probability of operating point stability figures.

Journal ArticleDOI
TL;DR: In this article, the definition of system voltage nomenclature, steady state system operation as affected by transmission line impedances, line and generator current unbalance, and the electrical environmental aspects of radio noise, audible noise, and electric fields at ground level are compared to representative 3-phase conditions.
Abstract: High phase order transmission (HPO), the use of more than the conventional three phases, is a unique approach to more efficiently using the overhead transmission rights-of-way. This paper addresses definition of system voltage nomenclature; steady state system operation as affected by transmission line impedances; line and generator current unbalance; and the electrical environmental aspects of radio noise, audible noise, and electric fields at ground level. Quantitative results for these areas are compared to representative 3-phase conditions.

Journal ArticleDOI
TL;DR: In this paper, an integral arc model is developed from first principles that relates the arc characteristics to the arc current, the channel geometry, and the properties of the channel material, and approximate scaling laws are derived for the arc field strength, the pressure in the channel and the wall evaporation rate.
Abstract: High current density (> 10 A mm-2) arcs in channels of solid material are determined by (i) arc induced evaporation of wall material, (ii) axial convection, and (iii) radiative energy transfer. Based on these processes, an integral arc model is developed from first principles that relates the arc characteristics to the arc current, the channel geometry, and the properties of the channel material. The model is shown to agree satisfactorily with measurements. For engineering applications approximate scaling laws are derived for the arc field strength, the pressure in the channel and the wall evaporation rate.

Journal ArticleDOI
TL;DR: In this article, a simple algorithm for the self and mutual inductance of coaxial circular coils, based on Bartky's transformation, is presented. But it is not applicable to all coils.
Abstract: A new simple algorithm is presented for the calculation of the self and mutual inductance of coaxial circular coils, based on Bartky's transformation. The algorithm is applicable over the entire range of coil sizes, shapes and degrees of coupling. It is extremely efficient and produces results to a specified and arbitrary accuracy. The method may be extended to calculate the inductance of coils of finite thickness using two-dimensional quadrature formulae.

Journal ArticleDOI
TL;DR: In this paper, the torsional stresses that occur in large steam turbine-generator shafts due to both planned and unplanned system switching operations are discussed and the benefits of single-pole breaker operation and dividing the output of large generators between different electrical systems are briefly mentioned.
Abstract: The torsional stresses that occur in large steam turbine- generator shafts due to both planned and unplanned system switching operations are discussed. These operations include routine line switching, reclosing line-to-ground faults by either triple-pole or single-pole breaker operation, reclosing line-to-line and three-phase faults, malsynchronization and load rejection. The calculation of cumulative fatigue of individual turbine-generator shafts from computer-plotted torsional swing traces is explained. The benefits of single-pole breaker operation and of dividing the output of large generators between different electrical systems are briefly mentioned.

Journal ArticleDOI
TL;DR: In this article, various factors controlling flashover of solid insulators in pressurized SF6, are reviewed and their influences in gas insulated systems are discussed from a practical point of view.
Abstract: Various factors controlling the flashover of solid insulators in pressurized SF6, are reviewed and their influences in gas insulated systems are discussed from a practical point of view. Flashover voltage of clean insulator surface is under the influence of the insulator-metal contact as well as the macroscopic electric field distortion due to the high dielectric permittivity of solid insulator. Conducting particles or even fine metal powder can reduce the flashover voltage. Their effects are strongly dependent on the position they are located, the size of the insulator and gas pressure. Humidity of SF, gas should be strictly governed in SF, gas insulated apparatuses, since the condensation of water can decrease flashover voltage considerably. Decomposition products of SF6 due to the arcing in switchgears are deleterious to epoxy insulators particularly when silica is used as their filler. The decomposition products decrease the leakage resistance on the insulation surface. The field strength near positive electrode is enhanced by the electrolytic effect in the surface conduction layer. In some extreme condition, it initiates tracking on the insulator surface.

Journal ArticleDOI
TL;DR: Partial discharges in transformers cause high frequency (ultrasonic) pressure pulses to propagate through the insulating media, similar in character to stress waves propagated in solids during crack formation (acoustic emission) as discussed by the authors.
Abstract: Partial discharges in transformers cause high frequency (ultrasonic) pressure pulses to propagate through the insulating media. These are similar in character to stress waves propagated in solids during crack formation (acoustic emission). The techniques involved in the detection of acoustic emission (AE) are shown to be well suited to the detection of emissions from partial discharges.

Journal ArticleDOI
TL;DR: An experimental station for research on lightning and lightning effects was built in the Massif Central (France) in 1973 as discussed by the authors, where the experimental procedure is an application of artificial triggering of lightning flashes by means of the wire and rocket technique, which has previously been shown to be valid by M. M NEWMAN.
Abstract: An experimental station for research on lightning and lightning effects was built in the Massif Central (France) in 1973. The experimental procedure is an application of artificial triggering of lightning flashes by means of the wire and rocket technique, which has previously been shown to be valid by M. M. NEWMAN.

Journal ArticleDOI
TL;DR: In this article, an extension of a well known technique for generating capacity evaluation which includes limited energy systems is illustrated by a simple numerical system example, where the authors show that the era of abundant energy is disappearing and that limitations must be included in conventional studies.
Abstract: Most generating capacity reliability studies assume that there are no inherent energy imitations and therefore concentrate on considering the effect of unit forced outages and uncertain load requirements. It appears, however, that the era of abundant energy is disappearing and that limitations must be included in conventional studies. This paper illustrates an extension of a well known technique for generating capacity evaluation which includes limited energy systems. The approach is illustrated by a simple numerical system example.

Journal ArticleDOI
TL;DR: In this article, the effects of wind, ice, fault currents, and phase spacer performance on conductor spacing are considered, and representative conductor spacings and terminal insulation levels are tabulated based on the foregoing analyses.
Abstract: High phase order transmission (HPO), the use of more than the conventional three phases, is a unique approach to more efficiently using the overhead transmission rights-of-way. This paper evaluates those areas which impact phase clearances and insulation requirements. Fault overvoltages, overvoltagees due to interphase coupling, switching surges, rate of rise of circuit breaker recovery voltage, and lightning performance are analyzed. Additionally, the effects of wind, ice, fault currents, and phase spacer performance on conductor spacing are considered. Representative conductor spacings and terminal insulation levels are tabulated based on the foregoing analyses.

Journal ArticleDOI
TL;DR: In this paper, a comprehensive method for planning reactive compensation in power systems so as to maintain voltages in acceptable ranges during contingencies is presented, which allows the addition of further VAR compensation as may be economically justified.
Abstract: This paper presents a comprehensive method for planning reactive compensation in power systems so as to maintain voltages in acceptable ranges during contingencies. The methodology allows the addition of further VAR compensation as may be economically justified. Reactive compensation considered consists of conventional shunt reactive compensation, synchronous condensers, as well as variable shunt reactive control devices called static VAR control devices. This work combines VAR optimization with static as well as with dynamic system performance evaluations. Necessary modelling of static VAR control devices for inclusion in dynamic performance programs is also given.

Journal ArticleDOI
TL;DR: In this article, a steady state equivalent of a power system for use in real-time operation is described, which is the result of applying Dimo's REI method for the reduction of the electrical network and also for the provision of a means for on-line calibration.
Abstract: This paper describes a new steady-state equivalent of a power system for use in real-time operation. The equivalent is the result of applying Dimo's REI method for the reduction of the electrical network and also for the provision of a means for on-line calibration. Although this new equivalent is intended for application in system operation, it would also be useful in planning studies.

Journal ArticleDOI
D. Povh1, W. Schultz1
TL;DR: In systems with pronounced resonance conditions and a low degree of damping, temporary overvoltages may develop when transformers are switched in or at fault clearing as discussed by the authors, which can occur e.g. in generator networks feeding HVDC stations and in high voltage cable systems.
Abstract: In systems with pronounced resonance conditions and a low degree of damping, temporary overvoltages may develop when transformers are switched in or at fault clearing. Overvoltages can occur e.g. in generator networks feeding HVDC stations and in high voltage cable systems.

Journal ArticleDOI
TL;DR: In this paper, the authors report the results of an experimental investigation concerning the impact of voltage reduction on the energy use and demand level as it relates to load composition, specifically that of the American Electric Power System.
Abstract: This paper reports the results of an experimental investigation concerning the impact of voltage reduction on the energy use and demand level as it relates to load composition, specifically that of the American Electric Power System.

Journal ArticleDOI
TL;DR: The Navajo Generating Station as mentioned in this paper is a coal-firing unit with three 800 MW coal-fired units of life removed from the turbine-generator shaft and is located in a remote area near Page, Arizona.
Abstract: / % Resultant oscillating voltages produced in the generator armature INTRODUCTION i -& reinforce mechanical system oscillations to the point where allowable 9 shaft stresses will be exceeded. Short duration transient generator The Navajo Project is a generation-transmission system jointly torques may produce high oscillatory shaft torques during system owned by Arizona Public Service Company, Los Angeles Department N electrical disturbances such as capacitor switching, line switching of Water and Power, Nevada Power Company, Salt River Project, \\ and fault clearing. The oscillatory build up is caused by the same Tucson Gas & Electric Company, and the United States Bureau of interaction as dynamic instability. Of these two problem areas, Reclamation. Salt River Project is the Operating Manager of the transient torques are the most difficult to control because of their Navajo Generating Station. fast rise time and close coupling with the mechanical system. The magnitude of transient torques is measured in terms of the amount The Generation Station consists of three 800 MW coal-fired units of life removed from the turbine-generator shaft. located in a remote area near Page, Arizona. Power from this station is delivered to load centers in Southern Arizona, Southern California, 4 The Salt River Project, the Navajo SSR Task Force, and the and Southern Nevada by way of three 500 kV transmission lines. General Electric Company have combined efforts to develop and The distance from the Navajo Plant to the load centers is about 260 apply a static device at the Navajo Generating Station that will promiles. Two of the Navajo transmission lines are about 260 miles long, tect the generators from subsynchronous resonance. The device is and the third has a 500 kV interconnection about 75 miles away a three-phase blocking filter made up of four parallel LC tank cirfrom the Navajo Station. See Figure 1. cuits in series per phase and connected between the ground neutral point and the low voltage end of each single-phase main step-up To transmit large amounts of power over these relatively long dis, transformer high side winding. Each filter phase has a current limittances, as required in the Western United States, maintaining steady ing reactor in series and voltage limiting varistor in parallel. The phystate and transient stability, series capacitors are applied to the trans%k sical arrangement of the filter is shown schematically in Figure 2. mission lines. This has proven to be a technically and economically t Component parts are mounted outdoors and consist of 1300 capafeasible way to reduce the net impedance between the generating -citor units, two reactor tanks and a varister tank per phase. source and the load without constructing additional transmission TW lines. However, series compensated transmission lines can create T RELAY resonance problems in the subsynchronous frequency range. XJ

Journal ArticleDOI
TL;DR: A new approach for the computation of electric fields is described, based on the application of optimization techniques to the charge simulation method, which proves to be more efficient, minimizing the time required to set up and implement a solution of this kind.
Abstract: A new approach for the computation of electric fields is described, based on the application of optimization techniques to the charge simulation method. The charge simulation technique is briefly considered and the optimized version is formulated. The potential distribution of the rod-plane configuration is solved as a sample problem for comparative purposes, and consideration is given to the solution of field distributions with non-axial symmetry. The new optimized approach proves to be more efficient, minimizing the time required to set up and implement a solution of this kind.