Showing papers in "IEEE Transactions on Power Apparatus and Systems in 1974"
TL;DR: In this paper, the authors extend the Dommel-Tinney approach by incorporating exact outage-contingency constraints into the method, to give an optimal steady-state-secure system operating point.
Abstract: The Dommel-Tinney approach to the calculation of optimal power-system load flows has proved to be very powerful and general. This paper extends the problem formulation and solution scheme by incorporating exact outage-contingency constraints into the method, to give an optimal steady-state-secure system operating point. The controllable system quantities in the base-case problem (e.g. generated MW, controlled voltage magnitudes, transformer taps) are optimised within their limits according to some defined objective, so that no limit-violations on other quantities (e. g. generator MVAR and current loadings, transmission-circuit loadings, load-bus voltage magnitudes, angular displacements) occur in either the base-case or contingency-case system operating conditions.
1,487 citations
TL;DR: This paper describes a simple, very reliable and extremely fast load-flow solution method that is attractive for accurate or approximate off-and on-line routine and contingency calculations for networks of any size, and can be implemented efficiently on computers with restrictive core-store capacities.
Abstract: This paper describes a simple, very reliable and extremely fast load-flow solution method with a wide range of practical application. It is attractive for accurate or approximate off-and on-line routine and contingency calculations for networks of any size, and can be implemented efficiently on computers with restrictive core-store capacities. The method is a development on other recent work employing the MW-?/ MVAR-V decoupling principle, and its precise algorithmic form has been determined by extensive numerical studies. The paper gives details of the method's performance on a series of practical problems of up to 1080 buses. A solution to within 0.01 MW/MVAR maximum bus mismatches is normally obtained in 4 to 7 iterations, each iteration being equal in speed to 1? Gauss-Seidel iterations or 1/5th of a Newton iteration. Correlations of general interest between the power-mismatch convergence criterion and actual solution accuracy are obtained.
1,447 citations
TL;DR: In this paper, the authors describe a method for evaluation of power flow which takes into consideration uncertainty of node data, the essence of the method is that the net loads are given as a set of values together with additional information on the frequency of its accuracy.
Abstract: The paper describes a method for evaluation of power flow which takes into consideration uncertainty of node data. The essence of the method is that the net loads are given as a set of values together with additional information on the frequency of its accuracy. The described mathematical model and the practtical application are discussed and an example given.
737 citations
TL;DR: In this paper, a numerical method for the computation of electrostatic fields is described, based on the use of fictitious line charges as particular solutions of Laplace's and Poisson's equations.
Abstract: A numerical method for the computation of electrostatic fields is described. The basis of the method is the use of fictitious line charges as particular solutions of Laplace's and Poisson's equations. Details are given of a digital computer program developed for field calculations by means of this method, and its application is illustrated by practical examples involving two-and three-dimensional geometries.
652 citations
TL;DR: In this article, an improved method for analyzing many types of unsymmetrical, as well as symmetrical, multiphase induction machines is presented, and the simulation of a 7.5-hp induction machine with two three-phase sets of stator windings fed from two six-step inverters illustrates the application of the method of analysis and shows how the machine torque characteristic may be improved by proper spacing of the winding sets.
Abstract: The steps in t he applied voltages of a three-phase, inverter-induction motor drive system cause undesirable pulsations in motortor By using multiple inverters connected to a multiphase machine with appropriate winding displacements, significant improvement in system performance is possible. The winding displacements required, however, are not necessarily the symmetrical displacements used in standard multiphase machines. This paper sets forth an improved method for analyzing many types of unsymmetrical, as well as symmetrical, multiphase induction machines. The simulation of a 7.5-hp induction machine with two three-phase sets of stator windings fed from two six-step inverters illustrates the application of the method of analysis and shows how the machine torque characteristic may be improved by proper spacing of the winding sets.
307 citations
TL;DR: This paper presents an economic dispatch procedure for allocating generation in a power system by the use of the Jacobian matrix with inherent simplicity and rapid convergence behavior which are characteristics particularly omportant for on-line implementation.
Abstract: This paper presents an economic dispatch procedure for allocating generation in a power system by the use of the Jacobian matrix. The major advantage of the procedure over other optimal dispatch procedures is its inherent simplicity and rapid convergence behavior which are characteristics particularly omportant for on-line implementation. Results obtained from an investigation of its convergence for the 118 bus IEEE system are given. Comparisons with the classical approach are conducted and logic for on-line implementation is presented.
166 citations
TL;DR: In this article, the field region is discretised by triangular Finite-elements and the solution to the field problem is obtained by minimizing the energy functional with respect to each of the vertex values of the vector potential.
Abstract: Analysis of the eddy-currentproblem in magnetic structures by the method of Finite-elements is presented. The linear diffusion equation representing the appropriate energy functional is described. The field region is discretised by triangular Finite-elements and the solution to the field problem is obtained by minimizing the energy functional with respect to each of the vertex values of the vector potential. Expressions for the magnetic field, electric field and eddy-current losses are presented. The method is applied to a few cases of engineering interest and compared with results of classical analysis and tests.
160 citations
TL;DR: A new method is proposed to solve a single-stage expansion problem for a transmission network, given future generation and load patterns, and alternative types of lines available, subject to overload, reliability and right-of-way constraints.
Abstract: A new method is proposed in this paper to solve a single-stage expansion problem for a transmission network, given future generation and load patterns, and alternative types of lines available, subject to overload, reliability and right-of-way constraints. The problem is formulated as a series of zero-one integer programs which are solved by an efficient branch-and-bound algorithm. Complexity is reduced by the concepts of optimal cost-capacity curves and screening algorithms. A sample study is shown and the method is implemented in a computer program.
153 citations
TL;DR: The convolution theorem of Fourier transformation theory provides an "exact" solution to the representation of frequency-dependent line constants of distributed-parameter transmission lines.
Abstract: The convolution theorem of Fourier transformation theory provides an "exact" solution to the representation of frequency-dependent line constants of distributed-parameter transmission lines. This paper emphasizes modelling aspects crucial to accurate and efficient numerical solution by digital computer, as part of a production electromagnetic transients program. Sample results simulating a field test are included.
135 citations
TL;DR: In this paper, the relationship between the resonance phenomenon and pulse response is explained and illustrated with practical examples for the standard test waveforms, and a proposed alternative switching surge waveform is examined for its effect on the internal response of transformer windings.
Abstract: Some recent transformer failures have been attributed to part-winding resonances excited by a form of switching surge voltage pulse which produced internal overvoltages. This paper takes a tutorial approach to relate a transformer winding to an equivalent electrical network which can exhibit resonant effects both at its terminals and internally. The relationship between the resonance phenomenon and pulse response is explained and illustrated with practical examples for the standard test waveforms. A proposed alternative switching surge waveform is examined for its effect on the internal response of transformer windings. The material presented should promote the understanding required for consideration of changes in standard test waveforms.
133 citations
TL;DR: The evaluation problem is defined in the framework of pattern recognition and methods to obtain security functions are outlined and simulation results on steady state and transient securities of the CIGRE 225 kv system are included.
Abstract: Security evaluation is becoming an important part of power system operation. This paper presents a feasible pattern recognition approach to security evaluation in power systems. The evaluation problem is defined in the framework of pattern recognition and methods to obtain security functions are outlined. Simulation results on steady state and transient securities of the CIGRE 225 kv system are included.
TL;DR: The diameter of craters formed by a vacuum discharge on a copper cathode was determined for single and multiple discharges in the current range of 4-230 A. The most probable current density in the cathode plane is a function of the current and is in the order of 108 A/cm2 as mentioned in this paper.
Abstract: The diameter of craters formed by a vacuum discharge on a copper cathode was determined for single and multiple discharges in the current range of 4-230 A. For a fixed current the crater diameter has values according a lognormal distribution solely determined by the current. Current chopping is characterized by the, forming of craters having one specific diameter (3,6 ?m). After splitting of a discharge the current is on the average equally divided over the partial discharges. The surface geometry influences the movement of the metal vapour discharge over the cathode, it does not affect the distribution of cratersizes. The most probable current density in the cathode plane is a function of the current and is in the order of 108 A/cm2.
TL;DR: In this paper, a method of calculating voltage oscillations in transformer windings during impulse test is presented, which can be used to calculate the voltage oscillation in transformer transformers.
Abstract: A method of calculating voltage oscillations in transformer windings during impulse test is presented.
TL;DR: In this article, a method is described for commiting generators and scheduling their output so as to comply with environmental objectives such as limitations on emission of oxides of sulfur and nitrogen, or discharge of heat into watercourses.
Abstract: A method is described for commiting generators and scheduling their output so as to comply with environmental objectives such as limitations on emission of oxides of sulfur, oxides of nitrogen or discharge of heat into watercourses. The limitations may apply to emissions or to resulting ambient concentrations and may apply simultaneously to more than one type of residual. The method depends on the use of monetary conversion factors. For each set of environmental objectives and each system load level, minimum operating costs are achieved. The examples presented are based on the characteristics of the generators in the Israeli power system.
TL;DR: In this article, a mathematical model which simulates the growth of a power system and determines the least cost expansion plan for a system of distribution substations is defined and a new approach employing linear and integer programming is used to optimize the system's substation capacities subject to the constraints of cost, load, voltage, and reserve requirements.
Abstract: This paper defines a mathematical model which simulates the growth of a power system and determines the least cost expansion plan for a system of distribution substations. A new approach employing linear and integer programming is used to optimize the system's substation capacities subject to the constraints of cost, load, voltage, and reserve requirements. The model has been successfully applied to a 1600 square mile urban area served by 70 distribution substations.
TL;DR: It is demonstrated that parameter inaccuracies can cause important limitations on on-line state estimation, and a recursive filtering-type algorithm is derived for this purpose to estimate inaccurate parameters.
Abstract: The problem of estimating the network and other parameters of a power system using on-line telemetry data is considered. It is demonstrated that parameter inaccuracies can cause important limitations on on-line state estimation. This can be corrected by processing collected on-line data in an off-line mode to estimate inaccurate parameters. A recursive filtering-type algorithm is derived for this purpose. Simulation results indicate the feasibility of parameter estimation and the effectiveness of the derived algorithm.
TL;DR: In this article, general recommendations for minimizing the treeing effect in PE and XLP cables as well as for testing these cables for tree development have been made based on numerous tests.
Abstract: Numerous polyethylene (PE) and crosslinked polyethylene (XLP) cable samples recovered from the field after one to seventeen years of service have been studied in relation to treeing phenomena. Special test circuits for laboratory growth of electrical and electro-chemical trees have been developed. Based on numerous tests, general recommendations for minimizing the treeing effect in PE and XLP cables as well as for testing these cables for tree development have been made.
TL;DR: In this paper, the authors summarized the significant problem areas of system disturbances and equipment effects due to geomagnetic storms, including increased VAR requirements and shifts in VAR flow, systemvoltage fluctuations, generation of harmonics, protective relayiing misoperations, and possible localized internal heating in transformers.
Abstract: Geomagnetic field fluctuations produce spurious, quasi-dc currents in power systems. The currents enter through system grounding points, and are of sufficient magnitude to cause half-cycle saturation in power transformers. These currents have been recorded and are summarized, and recommendations made in the significant problem areas of system disturbances and equipment effects due to geomagnetic storms. The major problem areas include increased VAR requirements and shifts in VAR flow, system-voltage fluctuations, generation of harmonics, protective relayiing misoperations, and possible localized internal heating in transformers. Recommendations relating to these effects have Pot been published previously.
TL;DR: In this paper, a new approach for the evaluation of substation and switching station reliability performance in terms of outage frequencies and durations is presented, where all realistic component failure modes are included in the reliability predictions.
Abstract: This paper presents a new approach for the evaluation of substation and switching station reliability performance in terms of outage frequencies and durations. All realistic component failure modes are included in the reliability predictions. The computer program described in the paper is fairly general. It performs failure modes and effects analysis and provides a concise and orderly description of the various combination of occurrences within the system that could result in an interruption. The application of the program is illustrated by considering two practical system examples. The concepts described are quite general and can be easily extended to the reliability evaluation of other power systems configurations.
TL;DR: In this paper, the complex power system is represented as a continuum, with transmission capacity and machine inertial uniformly distributed, and the propagation velocity and characteristic impedance are calculated for one and two dimensional propagation.
Abstract: Today's power systems tend to cover whole continents and the density of transmission facilities is continuously increasing. A disturbance produced in one point propagates to remote points of the system, it may be reflected at the boundaries and standing waves may build up. To obtain better insight into such phenomena, the complex power system is represented as a continuum, with transmission capacity and machine inertial uniformly distributed. One and two dimensional propagation are examined and analogies with travelling and standing electromagnetic waves are established. Propagation velocity and characteristic impedance are calculated. Resonance, and reflection-free terminations, acting as dynamic equivalents of surrounding systems, are also discussed as applications to the general theory. Results with the continuum representation are compared to those obtained for a discrete model to confirm the validity of the method.
TL;DR: In this paper, the dynamic interactions between mechanical and reactive modes of machines in a multi-machine power system are investigated in terms of machine angles, transient voltages, and coefficients which are functions of system parameters and operation conditions.
Abstract: In this paper the dynamic interactions between mechanical and reactive modes of machines in a multi-machine power system are investigated. The dynamic interactions are expressed in terms of machine angles, transient voltages, and coefficients which are functions of system parameters and operation conditions. The effect of the dynamic interaction can be examined by the electric torque loci on the A6-Aw phase plane. It is found that the interaction between the mechanical modes of machines has significant effect on stability characterized by the natural mechanical oscillation frequency and damping of individual machines.
TL;DR: In this paper, the self and mutual leakage inductance of transformer windings is calculated when the iron core is taken into account, and a method of solving this problem is presented.
Abstract: When calculating transient oscillations in transformer windings one has to know the self and mutual leakage inductances for sections of windings. This paper presents a method of solving this problem when the iron-core is taken into account.
TL;DR: In this paper, the behavior of an alternator with two 3-phase stator windings displaced by an angle e, is analyzed by means of an orthogonal transformation of the a, b, c; A, B, C; and fd variables into a new set: dl, ql, 01; d2, q2, 02; and Fd.
Abstract: To improve efficiency and alleviate certain limitations in large generators, two separate stator windings have been suggested. The behavior of an alternator with two 3-phase stator windings displaced by an angle e;, is analyzed by means of an orthogonal transformation of the a, b, c; A, B, C; and fd variables into a new set: dl, ql, 01; d2, q2, 02; and fd. For balanced operating conditions the differential equations with the new variables have time-indenendent coefficients. Thus a phasor diagram can be drawn using self and mutual reactances Xd, Xqv X12d and X12q, determined from flux linkages. The latter are based on flux plots obtained bysolving the quasi-Poissoniandifferentialequation. The characteristic parameters for a specific operating condition are calculated for a 1200 MVA, 24 kV, 60 Hz, two-pole turbogenerator, and test data are presented covering single circuit operation on a 2-circuit generator with 600 belts connected as an alternate pole and alternate belt type double winding machine.
TL;DR: In this article, the authors present a technique that simulates load and generation changes and outages of transmission lines and transformers using the sensitivity matrix of the basic system state, and the real and reactive power flowing in the system elements and voltages at all the system buses are then computed.
Abstract: This paper presents a technique that simulates load and generation changes and outages of transmission lines and transformers. The modification of power injected into the system buses, which would simulate the outage of a transmission element, is calculated using the sensitivity matrix of the basic system state. The real and reactive power flowing in the system elements and voltages at all the system buses are then computed. The proposed technique has been applied to the Saskatchewan Power Corporation system andto the combined SPC and Manitoba Hydro systems. The power flows and bus voltages calculatedby the proposed technique are compared with those obtained from the Newton Raphson load flows.
TL;DR: In this article, the statistical properties of ac and dc breakdown field strength of compressed SF6 were investigated on four gaps of different electrode area, ranging from 0.2 cm2 to 3000 cm2, and the breakdown characteristics were classified into four categories depending on the type of distribution and the characteristics of conditioning effect.
Abstract: This paper presents experimental results on the statistical properties of ac and dc breakdown field strength of compressed SF6. The experiment is performed on four gaps of different electrode area, ranging from 0.2 cm2 to 3000 cm2. Patterns of breakdown characteristics are classified into four categories depending on the type of distribution and the characteristics of conditioning effect. The criterion of the transition of these categories are discussed quantitatively.
TL;DR: In this paper, the dependence of the recovery speed on the pressure and on dI/dt was obtained, for both air and SF6, in a model interrupter of axial flow type employing a Laval nozzle.
Abstract: The dependence of the recovery speed on the pressure and on dI/dt was obtained, for both air and SF6, in a model interrupter of axial flow type employing a Laval nozzle. The measurements were carried out for pressures extending from 100-600 psi (6.8-41 atm) and for dI/dt values ranging from 5-30 A/?s. For both gases the recovery speed was found to increase with pressure, varying as the first power for air and as the 1.4 power for SF6. A stronger than expected dependence on dI/dt was also found for both air and SF6, the recovery speed varying inversely as the square in each case.
TL;DR: The paper reviews the criteria for the constrained optimization of real power; discusses practical approaches towards implementation; presents numerical results of tests on a large network model including the effects of convergence, external equivalents, and reference bus locations.
Abstract: As power systems have evolved in size and complexity so has the need for sophisticated and comprehensive real time control and dispatch techniques. Solutions presented in this paper are intended for on-line applications and are further designed to accommodate "network" as well as "nonnetwork" (e.g., environmental) and interacting operating restrictions. The paper reviews the criteria for the constrained optimization of real power; discusses practical approaches towards implementation; presents numerical results of tests on a large network model including the effects of convergence, external equivalents, and reference bus locations; proposes extensions to include reactive power dispatch and contingency constraints
TL;DR: In this paper, the performance of four conductor bundles -6 × 1.823, 6 ×1.998, 8 × 1, 63, and 8 ×1,823 -has been studied in outdoor test cages under conditions of heavy artificial rain and fair weather.
Abstract: As part of a general study on the possible use of UHV transmission lines in the range of 1200 kV for the James Bay Project, the corona performance of four conductor bundles -6 ×1. 823", 6 ×1. 998", 8 ×1. 63 " and 8 ×1.823"-has been studied in outdoor test cages under conditions of heavy artificial rain and fair weather. The radio interference, audible noise and corona losses of the four conductor bundles have been measured in the test cages, and the corresponding long line levels have been evaluated. The results show that of the four bundles tested the 8 ×1.63" conductor bundle gives the best corona performance. However, ice loading conditions may dictate the use of a six conductor bundle, in which case the 6 ×1.823" conductor bundle seems to give a marginally acceptable corona performance.
TL;DR: In this article, a physically realizable linear optimal controller in terms of easily measurable state variables for the stabilization of power system is developed, based on a fairly accurate fifth order synchronous machine and a first order voltage regulator.
Abstract: A physically realizable linear optimal controller in terms of easily measurable state variables for the stabilization of power system is developed in this paper. The controller is based on a fairly accurate fifth order synchronous machine and a first order voltage regulator. The transformation of the system equations into a cannonical form enables us to determine the weighting matrices Q and R of the quadratic cost function with simple procedure and to design an optimal controller which can stabilize a power system under widel. power range operating conditions. Transient response test on the nonlinear model proves the effectiveness of the linear control design.
TL;DR: Theoretical computation and experimental verification of the potential probe position in non homogeneous soil is presented in this article, where the experimental work was carried out on a twin layer laboratory model.
Abstract: Ground electrode resistance measurements are usually done by Fall of Potential method. The potential probe position (0.618 rule) has been calculated for homogeneous soil 1,2]. Theoretical computation and experimental verification of the potential probe position in non homogeneous soil is presented. The experimental work was carried out on a twin layer laboratory model [3,4,6].