Showing papers in "IEEE Transactions on Power Apparatus and Systems in 1979"
TL;DR: In this article, a load model, generation system, and transmission network which can be used to test or compare methods for reliability analysis of power systems is described. But the authors focus on the reliability of the power system and do not consider the transmission system.
Abstract: This report describes a load model, generation system, and transmission network which can be used to test or compare methods for reliability analysis of power systems. The objective is to define a system sufficiently broad to provide a basis for reporting on analysis methods for combined generation/transmission (composite) reliability.
2,289 citations
TL;DR: In this paper, the authors describe the development and evaluation of an analytical method for the direct determination of transient stability, which is based on the analysis of transient energy and accounts for the nature of the system disturbance as well as for the effects of transfer conductances on systenmbehavior.
Abstract: This paper describes the development and evaluation of an analytical method for the direct determination of transient stability. The method developed is based on the analysis of transient energy and accounts for the nature of the system disturbance as well as for the effects of transfer conductances onsystenmbehavior. It has been evaluated on a 10 generator 39 bus system and on a 20 generator 118 bus system. The method predicts critical clearing times for first swing transient stability which agree very closely with the results of simulations.
929 citations
TL;DR: A fast technique has been developed for the automatic ranking and selection of contingency cases for a power system contingency analysis study and results of this technique applied to different test systems are presented.
Abstract: A fast technique has been developed for the automatic ranking and selection of contingency cases for a power system contingency analysis study. A contingency list is built containing line and generator outages which are ranked according to their expected severity as reflected in voltage level degradation and circuit overloads. An adaptive contingency processorcan be set up by performing sequential contingency tests starting with the most severe contingencies at the top of the list and proceeding down the list, stopping when the severity goes below a threshold. Computational results of this technique applied to different test systems are presented.
466 citations
TL;DR: A linear programming method for security dispatch and emergency control calculations on large power systems is presented, which works directly with the normal power-system variables and limits, and incorporates the usual sparse matrix techniques.
Abstract: A linear programming (LP) method for security dispatch and emergency control calculations on large power systems is presented. The method is reliable, fast, flexible, easy to program, and requires little computer storage. It works directly with the normal power-system variables and limits, and incorporates the usual sparse matrix techniques. An important feature of the method is that it handles multi-segment generator cost curves neatly and efficiently.
396 citations
TL;DR: In this paper, a new algorithm suitable for calculating impedances from digitized voltages and currents sampled at a relay location is presented, where each input is assumed to be composed of a decaying d.c. component and components of the fundamental and harmonic frequencies.
Abstract: This paper presents a new algorithm suitable for calculating impedances from digitized voltages and currents sampled at a relay location. Each input is assumed to be composed of a decaying d.c. component and components of the fundamental and harmonic frequencies. Parameters of a digital filter determined by using the least error squares approach are then used to compute the real and imaginary components of the voltage and current phasors. Impedances as seen from a relay location are then calculated. The proposed algorithm was tested using the fault data recorded at the Regina South switching station of the Saskatchewan Power Corporation; some of the test results are included.
274 citations
TL;DR: This paper presents fast-decoupled state estimators, using also decoupled detection and identification of bad data, using the sparse inverse matrix method.
Abstract: This paper presents fast-decoupled state estimators, using also decoupled detection and identification of bad data. Bad data is eliminated by pseudo-measurement generation. This procedure avoids gain-matrix retriangulations or the use of modification techniques like Woodbury formula. In the identification process, the diagonal of the covariance matrix of the measurement residuals is calculated using the sparse inverse matrix method. Two main types of fast-decoupled estimators were tested : algorithm- decoupled and model-decoupled. The methods have been tested on IEEE 30-bus load-flow test system, and the FURNAS and CPFL systems that form part of the 835-bus interconnected 15 GW power system of the S.E. Brazil.
225 citations
TL;DR: In this paper, an analytical basis for the St. Clair line loadability curve is presented and the extension of its use into the EHV and UHV transmission area is discussed.
Abstract: This paper contains the development of an analytical basis for the St. Clair line loadability curve and presents the extension of its use into the EHV and UHV transmission area. A brief historical background describes the origin and pertinent aspects of the St. Clair curve including the fact that the old curve, originally intended for transmission voltages up to 330-kV, is derived empirically based upon practical considerations and experience. In order to extend the usefulness of such line loadability characteristics into the EHV and UHV range, a simplified representation of the system, which incorporates flexibility to include both line and system parameters, is utilized to compute maximum line loadability subject to assumed system performance criteria. It is shown that, for a reasonable and consistent set of assumptions, with regard to system parameters and performance criteria, EHV and UHV transmission line loadability characteristics are nearly identical to the original St. Clair curve. The paper further illustrates the relative influence of these assumptions on the derived characteristics, In particular, the electrical strength of the sending- and receiving-end systems is found to have an increasingly important influence on the loadability of transmission lines as the voltage class increases. The analytical approach to determination of transmission line loadability curves enables the user to examine specific situations and assumptions and to avoid possible misinterpretation of generalized conceptual guides-particularly in the EHV/UHV range where system parameters can have a significant impact on loadability.
201 citations
TL;DR: In this paper, the steady-state corona losses on HVDC transmission lines are estimated using knowledge of the electric field vector and of the space charge at the electrode surfaces.
Abstract: Analytical computation of steady-state corona losses on HVDC transmission lines presupposes knowledge of two quantities: of the electric field vector and of the space charge. Both quantities could be sought in the entire interelectrode space, but it is mandatory to know them at least at electrode surfaces.
172 citations
TL;DR: In this article, a primary feeder model using small area demand locations to represent nonuniform loads, and feeder segments having variable distribution costs and limited capacities is formulated, and the solution of problems having 1000 demand locations and 100 substations can be found in a fraction of a second by using a current fast upper bounded transshipment code.
Abstract: A primary feeder model using small area demand locations to represent nonuniform loads, and feeder segments having variable distribution costs and limited capacities is formulated The solution of problems having 1000 demand locations and 100 substations can be found in a fraction of a second by using a current fast upper bounded transshipment code The problem of restructuring the solution to satisfy other kinds of constraints is also discussed
164 citations
TL;DR: In this paper, the effect of curvature on the power consumption of a series-connected multiple-layer coil has been investigated with respect to power losses with the windings. But the authors did not consider the effects of the curvature of the coils.
Abstract: The classical one dimensional magnetic field and eddy current distribution ("proximity effect") within a series connected multiple layer coil is reexamined with regard to power losses withinthe windings. When the lengthand number of layers ina coilare fixed, the power dissipation within each layer can be minimized by choosing a specific radial thickness for each layer. Above or below this thickness, the losses within the winding increase. The conductor thickness which results in minimum dissipation depends on the relative position of the layer. When compared to a design having a constant thickness for each layer (chosen for minimum total dissipation), it is found that substantial savings in power consumption can be realized by employing a variable thickness of conductor. The one dimensional solution in cylindrical coordinates for the eddy current and skin effect in amultiple layer series connected coil is alsopresented. By solving the problem n cylindrical coordinates, the effect of curvature on the power consumption within each layer is apparent. This analysis should have application to the design of power transformers, armature windings, and inductors for power transmission lines.
144 citations
TL;DR: In this paper, two algorithms are described to solve the line overload problem in the Newton-Raphson and decoupled load flow programs, which can be used to determine the generation rescheduling and load curtailment pattern to alleviate line overloads.
Abstract: This paper deals with the problem of alleviating line overloads in a power system by generation rescheduling and load shedding. Mathematical models based on linearized relationships between line currents and state variables, and bus injected powers and state variables are systematically developed to considerthe line overload problem. Two algorithms are described to solve the models in the Newton-Raphson and decoupled load flow programs. The techniques developed can beused to determine the generation rescheduling and load curtailment pattern to alleviate line overloads. The approaches presented in this paper shouldprove useful in system security studies and reliability studies for examining line overload alleviation with minimum computational expense. The analytical results can also serve as an operating guide to the system dispatcher. In a companion paper, the effectiveness of these techniques in alleviating line overloads in several test systems is investigated.
TL;DR: The main contribution is a simple extension to the Ward-type equivalencing method that solves the boundary-bus designation problem and gives reliable and accurate results.
Abstract: Equivalent models for the external system in online load-flow studies are presented. The main contribution is a simple extension to the Ward-type equivalencing method that solves the boundary-bus designation problem and gives reliable and accurate results. The method can be applied equally well for off-line equivalencing, where it overcomes the need for buffer zones. Variations on this technique are investigated. The models require topology information, but no real-time measurement data, for the external system. The new methods have been verified by simulation on the IEEE 30 and 118 bus load-flow test systems and on the 835-bus interconnected 15 GW power system of S.E. Brazil.
TL;DR: In this paper, a method for allowing for the effects of variation of leakage current density caused by the proximity of parallel conductors, cross-connectors, angled conductors and end effects is presented.
Abstract: Equations presented in most papers on the computation of voltages at the surface of the earth near a buried energized electrode grid of bare wires are based on the assumption that leakage current density is the same at all points along the wire grid. This paper presents a method for allowing for the effects of variation of leakage current density caused by the proximity of parallel conductors, cross conductors, angled conductors, and end effects. Examples are presented showing the effect of the non-uniform leakage in some cases. The method given herein also can be used to compute surface voltages in the vicinity of electrodes composed of wires oriented at arbitrary angles, such as combinations of stars and polygons, and the resistance to ground of such electrodes.
TL;DR: In this article, a high-speed relay is expected to make a decision as to the severity or location of the fault, usually based on 60 Hz information, i.e. the phase and magnitude of 60 Hz voltage or current signals.
Abstract: During the first cycle or two following a power system fault, a high-speed protective relay is expected to make a decision as to the severity or location of the fault, usually based on 60 Hz information, i.e. the phase and magnitude of 60 Hz voltage or current signals. It is precisely at this time however that the signal is badly corrupted by noise, in the form of a dc offset or frequencies above 60 Hz.
TL;DR: Overall conclusions indicate that the parallel algorithm is always much faster and sometimes has better convergence characteristics than the classical trapezoidal integration algorithm.
Abstract: The numerical method presented in this paper permits the solution of differential equations by trapezoidal integration in a time of order log2 T, where T is the number of discrete time steps required for the solution. The number of required parallel processors is T/2. Linear and nonlinear examples are presented. The nonlinear example corresponds to a small stability problem. The classical trapezoidal integration algorithm is compared to the new parallel trapezoidal algorithm in terms of solution time requirements. Also, for the nonlinear example the comparison includes the number of iterations and convergence characteristics. Overall conclusions indicate that the parallel algorithm is always much faster and sometimes has better convergence characteristics. Potential limitations of the method are also discussed.
TL;DR: Frequency scanning employs an approximate technique which is efficient, and cost effective for the analysis of Subsynchronous Resonance (SSR). This technique is particularly suited to screening type studies to sort out the critical system conditions from the multitude of system conditions which can exist as discussed by the authors.
Abstract: Frequency scanning employs an approximate technique which is efficient, and cost effective for the analysis of Subsynchronous Resonance (SSR). This technique is particularly suited to screening type studies to sort out the critical system conditions from the multitude of system conditions which can exist. Following is a description of the frequency scanning technique, its use in analysis of SSR problems, correlation with field test results, and an example of data preparation and program application. In addition, a new analysis technique using circle diagrams is presented.
TL;DR: In this article, the effect of derivative gain and other governor parameters on the stability boundaries of a hydraulic turbine generating unit supplying an isolated load is investigated, and a general guide for optimum adjustment of derivative gains and other parameters is provided.
Abstract: The effect of derivative gain and other governor parameters on the stability boundaries of a hydraulic turbine generating unit supplying an isolated load is investigated. Root locus method is used for analysis of the effect of governor parameters on the dynamic behavior of the hydroelectric power system. A general guide for optimum adjustment of derivative gain and other parameters is provided.
[...]
TL;DR: In this paper, the authors provide a quantitative method for electric power utilities to predict the magnitude and duration of the peak demand following a power outage in cold weather, which is limited strictly to electrically heated homes.
Abstract: The primary purpose of this paper is to provide a quantitative method for electric power utilities to predict the magnitude and duration of the peak demand following a power outage in cold weather. The study is limited strictly to electrically heated homes. A model has been developed based on experimental data that predicts the power demand of any number of homes following a power outage. The authors believe that this information should influence both the design of the distribution system and the method of power restoration.
TL;DR: In this paper, the performance of insulators covered with snow or ice was investigated and it was shown that the AC and DC withstand voltages of snow-covered insulators were characterized by the conductivity of water melted from the snow.
Abstract: This paper describes the results of investigation made into the performance of insulators covered with snow or ice. The AC and DC withstand voltages of snow-covered insulators were characterized by the conductivity of water melted from the snow. The AC withstand voltage of ice-coated insulators was characterized by the length of icicles and conductivity of the water melted from the ice. And the switching impulse flashover voltage of snow-covered insulator strings was almost proportional to gap length between the arcing horns or the insulator strings. Flashover voltage of a 75% snow-covered insulator string, which means the worst case, was 40 ?65% of the positive wet flashover voltage of the clean insulator string.
TL;DR: In this paper, the equivalence of neglecting the pq terms in the synchronous reference frame is to neglect the p* and Aw terms in all other reference frames in R-L transmission systems, synchronous and induction machines.
Abstract: For more than four decades it has been thought that neglecting the so-called "ph terms" in Park's equations is equivalent to neglecting the electric transients due to the stator windings of a synchronous machine. Over the years, trial and error results have indicated that a more accurate prediction of synchronous machine performance could be obtained if the Aw(p6) terms in the stator voltage equations were also neglected. This paper provides a theoretical explanation of this experimental observation. In particular, it is established theoretically that in order to neglect the "stator transients" both the p* and Aw terms must be set equal to zero. This is accomplished by proving that the equivalence of neglecting the pq terms in the synchronous reference frame is to neglect the p* and Aw terms in all other reference frames. R-L transmission systems, synchronous and induction machines are considered.
TL;DR: In this paper, the problem of rescheduling generators and shedding loads in an emergency state is formulated as a nonlinear optimization problem and the desired solution is a set of control actions which, when applied, removes all the constraint violations such as abnormal voltages and line overloads with a minimum of re-scheduling and load shedding.
Abstract: The problem of rescheduling generators and shedding loads in an emergency state is formulated as a nonlinear optimization problem. The desired solution is a set of control actions which, when applied, removes all the constraint violations such as abnormal voltages and line overloads with a minimum of rescheduling and load shedding.
TL;DR: In this paper, the results of various real-time tests performed on the AEP-EHV System with the automatic contingency selection algorithm proposed in [1] are reported.
Abstract: Results of various real-time tests performed on the AEP- EHV System with the automatic contingency selection algorithm proposed in [1] are reported.
TL;DR: In this article, the authors investigated the streaming electrification in core type forced oil cooled power transformers, using a full-scale model transformer and various experimental models, and clarified that streaming electrical discharge occurs when the amount of local charge exceeds a certain limit.
Abstract: In this paper, the streaming electrification in core type forced oil cooled power transformers is investigated, using a full-scale model transformer and various experimental models. It has been clarified that streaming electrification in transformers is influenced mainly by flow rate, oil temperature, surface conditions of insulating materials and characteristics of insulating oil. Electrostatic discharge occurs eventually when the amount of local charge exceeds a certain limit.
TL;DR: Ontario Hydro's experience with diagnostic partial discharge tests on hydraulic generators over a period of five years shows that a reliable prediction of stator insulation condition can be made prior to physical examination.
Abstract: Ontario Hydro's experience with diagnostic partial discharge tests on hydraulic generators over a period of five years shows that a reliable prediction of stator insulation condition can be made prior to physical examination. "Action limit values" have been established to this end.
TL;DR: In this article, the results of an extensive study conducted using a computer program designed to determine grounding performance in two-layer soils are described and discussed, and the calculated grounding resistances, step and touch potentials are summarized in several charts which could be used conveniently for practical design purposes.
Abstract: The results of an extensive study conducted using a computer program designed to determine grounding performance in two-layer soils [1,2,3,5] are described and discussed. A variety of grounding grid configurations and two-layer soil conditions are analysed in detail. The calculated grounding resistances, step and touch potentials are summarized in several charts which could be used conveniently for practical design purposes. The results obtained prove that in general, conventional methods of analysis, such as the IEEE 80 method [4] which uses "Km & Ki" irregularity factors, fail to predict accurately grounding grid performance. Also, it is shown that there are certain grid configurations and/or burial depth, which lead to optimum touch or mesh potentials. Finally, it is shown that certain two-layer conditions will lead to considerably higher touch (or mesh) potentials than the other comparable alternatives.
TL;DR: In this article, an extension of the power transfer capacity calculation to the calculation of maximum power system loading is described. But the authors focus on the application to assessment of network adequacy and long range planning.
Abstract: This paper describes an extension of the power transfer capacity calculation to the calculation of maximum power system loading. This loading capability is a function of the generation and transmission capacity of the power system. The dc power flow equations provide a basis for the development of constraint equations necessary in the linear programming optimization of the generation-transmission system. An example is provided to illustrate the concepts of the load supplying capability of the power system, and the application to assessment of network adequacy and long range planning is discussed.
TL;DR: In this article, the role of impedance relaying in modern transmission line protection systems is discussed and a mathematical model of the relaying process in the presence of transient phenomena which accompany faults is presented.
Abstract: The paper reviews the role of impedance relaying in modern transmission line protection systems The speed and reach of the first zone of an impedance relay are identified as being the most important attributes of a relay The paper develops a mathematical model of the relaying process in the presence of transient phenomena which accompany faults It is shown that there is an uncertainty associated with the impedance estimated by a relay and this uncertainty depends upon the speed with which these estimates are made A quantitative relationship between the relay speed and its reach is obtained
TL;DR: In this article, the inherent features of typical distribution systems are discussed and models that more truly reflect the operational behaviour of such systems and their effect on the consumers are evaluated and the analysis of a typical system is included.
Abstract: Comparatively, distribution systems have received least consideration in the reliability evaluation of power systems although paradoxically they have the greatest average effect on loss of supply to the consumers. This paper discusses the inherent features of typical distribution systems and describes and evaluates models that more truly reflect the operational behaviour of such systems and their effect on the consumers. The analysis of a typical system is included which illustrates the additional and more meaningful results that can be achieved from the use of these improved system models.
TL;DR: In this paper, the authors investigated the conditions of occurrence of partial discharges which are caused by electrostatic charges in forced oil cooled core type transformers which are hereinafter called transformers.
Abstract: This paper deals with the investigation of some special features of the static electrification which is caused by oil flow, and the conditions of occurrence of the partial discharges which are caused by electrostatic charges in forced oil cooled core type transformers which are hereinafter called transformers in this paper.
TL;DR: The elementary phenomenon involved in flashover of high voltage insulators is the propagation of a discharge at the surface of an electrolyte as discussed by the authors, which leads to flashover when the required conditions are met.
Abstract: The elementary phenomenon involved in flashover of high voltage insulators is the propagation of a discharge at the surface of an electrolyte. The study reveals two requirements: 1-Electrical conditions (applied voltage and discharge current) have to be fulfilled so that the discharge can be sustained by the power source throughout the elongation process. 2-A physical mechanism has to be shown which the discharge and leads to flashover when the required conditions are met.