Showing papers in "IEEE Transactions on Power Apparatus and Systems in 1969"
TL;DR: In this article, the stability of synchronous machines under small perturbations is explored by examining the case of a single machine connected to an infinite bus through external reactance, and the results are shown to be similar to ours.
Abstract: The phenomena of stability of synchronous machines under small perturbations is explored by examining the case of a single machine connected to an infinite bus through external reactance.
1,939 citations
TL;DR: Electromagnetic transients in arbitrary single- or multiphase networks are solved by a nodal admittance matrix method based on the method of characteristics for distributed parameters and the trapezoidal rule of integration for lumped parameters.
Abstract: Electromagnetic transients in arbitrary single- or multiphase networks are solved by a nodal admittance matrix method. The formulation is based on the method of characteristics for distributed parameters and the trapezoidal rule of integration for lumped parameters. Optimally ordered triangular factorization with sparsity techniques is used in the solution. Examples and programming details illustrate the practicality of the method.
1,578 citations
TL;DR: In this article, a fundamental basis has been developed for the use of a time-shared stored-program digital computer to perform many of the electrical power-system protective-relay functions in a substation.
Abstract: A fundamental basis has been developed for the use of a time-shared stored-program digital computer to perform many of the electrical power-system protective-relay functions in a substation. Logic operations are given to detect a fault, locate it, and initiate the opening of the appropriate circuit breakers, whether the fault is in the station or on lines radiating from the station.
225 citations
TL;DR: In this paper, a numerical iterative method of computing the actual charge distribution around the conductor in the corona is presented, which is applicable to any general configuration for which the space-charge-free field can be calculated.
Abstract: Theoretical calculation of corona losses for practical unipolar dc transmission line configurations presents considerable difficulty because of the nonlinear nature of the equations describing the space-charge fields. The application of numerical methods to obtain solutions of practical interest is discussed. One of the difficulties in the analysis of space-charge fields is the determination of the actual charge distribution around the conductor in the corona. A numerical iterative method of computing this charge distribution is presented. The method is applicable to any general configuration for which the space-charge-free field can be calculated. The line- to-plane configuration is considered. A method of including the effect of conductor surface irregularities in the theoretical calculation of corona losses is outlined, and it is suggested that, by the same method, Popkov's formula may also be modified to make it applicable to lines with practical transmission-line conductors. Calculations by the method of analysis developed as well as by the modified Popkov equation are compared with experimental results.
192 citations
TL;DR: In this paper, a right cone representation for conventional double-circuit steel towers is proposed, and a theoretical analysis using field theory yields the surge impedance as Z = 60 ln (2/S) where S is the sine of the half-angle of the cone.
Abstract: Experimental and theoretical methods for determining the surge impedance of towers are presented. It is demonstrated that the values so obtained adequately describe the response of the tower when a transmission line is struck by lightning. A right cone representation for conventional double-circuit steel towers is proposed, and a theoretical analysis using field theory yields the surge impedance as Z= 60 ln (2/S) where S is the sine of the half-angle of the cone.
184 citations
TL;DR: In this article, it was shown with the aid of examples that transients for rotor quantities (rotor voltage, rotor current, etc.) can also be determined with satisfactory accuracy if calculations are based on equivalent diagrams correctly representing field and damper as well as stator circuits.
Abstract: The conventional diagram of the synchronous machine accurately represents only the stator circuit. It will be shown with the aid of examples that transients for rotor quantities (rotor voltage, rotor current, etc.) can also be predetermined with satisfactory accuracy if calculations are based on equivalent diagrams correctly representing field and damper as well as stator circuits.
175 citations
TL;DR: A unified approach to load-flow, minimum-loss, and economic dispatching problems is presented and a unconstrained minimization method is shown to coincide with the minimum of a function of the power system equations.
Abstract: A unified approach to load-flow, minimum-loss, and economic dispatching problems is presented. A load-flow solution is shown to coincide with the minimum of a function of the power system equations. An unconstrained minimization method, developed by Fletcher-Powell, is used to solve the load-flow problem. The method always finds a solution or indicates the nonexistence of a solution. Its performance is highly independent of the reference- slack bus position and requires no acceleration factors. Several constrained minimization techniques that solve the minimum-loss and economic dispatching problems are investigated. These include the Fiacco-McCormick, Lootsma, and Zangwill methods. The technique finally recommended is shown to be an extension of the method used to solve the load-flow problem. The approved IEEE test systems, and other systems whose response to conventional methods was known, have been solved.
151 citations
TL;DR: In this article, a stability analysis of a rectifier-inverter induction motor drive system is performed by neglecting the harmonic content of the stator voltages and applying Nyquist stability criterion to the small displacement equations obtained by linearization about an operating point.
Abstract: A stability study of a rectifier-inverter induction motor drive system is performed by neglecting the harmonic content of the stator voltages and applying Nyquist stability criterion to the small- displacement equations obtained by linearization about an operating point. This investigation reveals that system instability can occur over a wide speed range if the system parameters are improperly selected. It appears that the method of analysis presented in this paper is sufficient to predict stability of practical rectifier-inverter induction motor drive systems. Also, with slight modifications, this method of analysis can be applied to rectifier-inverter systems which supply reluctance-synchronous machines or synchronous machines.
136 citations
TL;DR: In this article, the root-locus criterion was used to identify regions of lightly damped operation in a symmetric induction machine. But, the results of an analog computer study were used to illustrate the modes of operation which occur within these regions.
Abstract: A stability study of an induction machine is performed by applying the root-locus criterion to the equations which describe the behavior of the machine during small displacements about a steady-state operating point. This investigation reveals that a symmetrical induction machine may become unstable at low speeds (low frequencies) even though balanced, constant amplitude, sinusoidal voltages are applied to the stator terminals. Regions of machine instability are established from the results of a digital computer study. The results of an analog computer study are included to illustrate the modes of operation which occur within these regions. Regions of instability for changes of system parameters are presented and discussed. Also, it is shown that the root- locus criterion can be utilized to identify regions of lightly damped operation.
134 citations
TL;DR: In this article, a centralized optimizing computational algorithm for the on-line control of voltage and reactive power is presented, where the body of the paper is divided into two parts: the main body is devoted to the analysis and the body is dedicated to the implementation of the algorithm.
Abstract: This paper presents a centralized optimizing computational algorithm for the on-line control of voltage and reactive power. The body of the paper is divided into two parts.
107 citations
TL;DR: In this paper, the response of stranded cables to exciting forces produced by wind is studied, and details of an analytical and experimental study of cable self-damping are presented, as well as an experimental model for self-deployment.
Abstract: The response of stranded cables to exciting forces produced by wind is studied here, and details of an analytical and experimental study of cable self-damping are presented.
TL;DR: In this article, a theoretical calculation of corona losses for bipolar dc transmission line configurations involves the analysis of the nonlinear ionized field in the interelectrode region.
Abstract: As in the case of unipolar corona, theoretical calculation of corona losses for bipolar dc transmission line configurations involves the analysis of the nonlinear ionized field in the interelectrode region. However, the complexity of the analysis is increased considerably because of the presence of ions of both polarities in the region.
TL;DR: In this paper, the effects of shunt compensation, on-load tap changing, and variations in allowable voltage levels on the reliability of a simple configuration are illustrated, and it is shown that the effect of storm associated failures on the system failure probabilities is dependent upon the degree of redundancy in the configuration under study.
Abstract: This paper illustrates the application of a conditional probability approach to the determination of a reliability index at any point in a composite system. A general design criterion is postulated in terms of quality of service rather than continuity. Using a Markov approach, it is shown that the effect of storm associated failures on the system failure probabilities is dependent upon the degree of redundancy in the configuration under study. The effects of shunt compensation, on-load tap changing, and variations in allowable voltage levels on the reliability of a simple configuration are illustrated. Using the techniques described in this paper, it is possible to arrive at a measure of steady-state adequacy for any point in a system and, particularly, at those points at which major transmission terminates and subtransmission begins.
TL;DR: Simplified representations of a rectifier-inverter induction motor drive system are established and verified by comparing the results obtained from a computer study using these representations to those obtained using a detailed simulation of the system as discussed by the authors.
Abstract: Simplified representations of a rectifier-inverter induction motor drive system are established and verified by comparing the results obtained from a computer study using these representations to those obtained using a detailed simulation of the system. It is shown that when all harmonic components are neglected the static drive system may be conveniently represented in the synchronously rotating reference frame. The computer simulation resulting from this type of representation can be readily implemented, and in many cases it will predict the system performance with sufficient accuracy. Also, in the analysis leading to these simplified representations, the operation of the inverter is analytically expressed in the synchronously rotating reference frame with the harmonic components due to the switching in the inverter included. These equations of transformation may be used to advantage in describing the interaction between the filter and the induction motor.
TL;DR: In this article, the electrostatic field of a system of infinitely long parallel cylindrical conductors is investigated, where each conductor is represented by a line charge at its center.
Abstract: The paper presents an investigation of the electrostatic field of a system of infinitely long parallel cylindrical conductors. Existing analytical techniques can be used only to solve rigorously the field of simple geometries such as a single conductor over a ground plane or inside a grounded cylinder and an isolated two-conductor bundle. Until now only approximate analytical solutions have been obtained for the more practical multiconductor systems; in these, each conductor is represented by a line charge at its center.
TL;DR: In this paper, a series of load-voltage tests performed on the Southern California Edison Company system are described and the test results are summarized and used as the basis for individual bus load representation.
Abstract: This paper emphasizes the need for a correct representation of electrical loads in stability studies. Several series of load-voltage tests performed on the Southern California Edison Company system are described. The test results are summarized and used as the basis for individual bus load representation.
TL;DR: In this article, a method of applying shunt capacitors for voltage control and peak loss reduction is discussed, and the concept is extended to the optimization of total monetary savings due to both peak loss and energy loss reductions.
Abstract: A method of applying shunt capacitors for voltage control and peak loss reduction is discussed. The concept is extended to the optimization of total monetary savings due to both peak loss and energy loss reductions. A computer program is developed to aid engineers in the application of such a method.
TL;DR: In this paper, a model of the power system load with the generation system model is proposed to calculate the availability, frequency of occurrence, and mean duration of the generation reserve states, and the results of this work are illustrated by continuation of a simple numerical example.
Abstract: This paper is a continuation of the work started in [1] and is aimed at incorporating a model of the power system load with the generation system model developed previously. Combination of this load and the generation model permits computation of the availability, frequency of occurrence, and mean duration of generation reserve, or margin states. The results of this work are illustrated by continuation of a simple numerical example begun in Part I. The most widely applied of the previously developed techniques for assessing generation system reliability, the loss-of-load and loss-of-capacity methods, assume fixed outage or load duration intervals. The present model, on the other hand, uses an exponential distribution of durations. The reserve margin states developed using the exponential distributions contain data giving both the availability of each margin state and the expected frequency of recurrence. Previous methods yield only the availability of the reserve margin states, or else availability and frequency data for generating capacity states, not considering the load. The method presented and illustrated may be extended t o consider the calculation of operating reliability or the inclusion of the effects of a simple transmission system.
TL;DR: In this paper, a method of predicting the 6th-harmonic electromagnetic torque of an induction motor arising from a rectifier-inverter power source is presented, including both the effects of harmonic variation rotor speed and inverter voltage.
Abstract: A method of predicting the 6th-harmonic electromagnetic torque of an induction motor arising from a rectifier-inverter power source is presented. This study includes both the effects of harmonic variation rotor speed and inverter voltage. Although only the 6th harmonic is considered, it is shown that this is sufficiently accurate to predict steady-state system performance for practical speed ranges and system parameters. This investigation reveals that the 6th-harmonic electromagnetic torque pulsation may, at low frequencies, be significantly greater than that predicted by a constant speed, constant voltage analysis heretofore employed, and may materially affect the performance of the system.
TL;DR: In this article, the effects of line loading and its power factor on the voltage and current profiles of the line and ganerator excitation have been included, and the inevitability of power-frequency overvoltages during faults is established.
Abstract: This paper provides additional theoretical information on half-wave-length power transmission. The analysis is rendered more general by consideration of a natural half-wave line instead of a short line tuned to half-wave. The effects of line loading and its power factor on the voltage and current profiles of the line and ganerator excitation have been included. Some of the operating problems such as charging of the line and synchronization of the half-wave system are also discussed. The inevitability of power-frequency overvoltages during faults is established. Stability studies have indicated that the use of switching stations is not beneficial. Typical swing curves are also presented.
TL;DR: Direct and quadrature-axis equivalent circuits for solid-rotor turbine generators were developed in this article to model important current-carrying paths in the rotor in addition to the excitation winding.
Abstract: Direct- and quadrature-axis equivalent circuits are developed for solid-rotor turbine generators. The equivalent circuits model, in considerable detail, important current-carrying paths in the rotor in addition to the excitation winding. Impedance equations are formulated so that a valid representation can be obtained over a wide range of frequencies. Operational solution of the equivalent circuits provides a powerful means for accurate analytical description of generator performance during many types of transient conditions, such as faults and other system disturbances, excitation system forcing, and asynchronous operation. In addition to providing improved accuracy of representation of generator terminal characteristics, solution of the circuits provides a wealth of valuable generator design information.
TL;DR: In this article, the feasibility of solving optimal load flow problems by means of nonlinear programming techniques has been previously demonstrated, and a new method by Powell for constrained minimization has claimed a better performance than existing methods.
Abstract: The feasibility solving optimal load flow problems by means of nonlinear programming techniques has been previously demonstrated. Recently, a new method by Powell for constrained minimization has claimed a better performance than existing methods. An investigation was carried out to test Powell's method on optimal load flow problems and results obtained confirm expectations. Powell's method and its accompanying Fletcher-Powell method, which performs the actual minimizations, are presented. The power system optimal load flow problem is discussed, and its equations are presented in the form required by the nonlinear programming approach. Finally, a numerical example on the IEEE 30- bus standard test system is presented in which an economic dispatching is accomplished with the new method. Computation time is small enough to permit the application of the method for dispatching at practical intervals of time.
TL;DR: In this paper, an analytical method called the incremental describing-function method is applied to the problem of ferroresonance in power systems for a certain class of problems, where the conditions can be shown to be essentially single phase.
Abstract: Ferroresonance is defined in a way corresponding to the more general expression "jump resonance." An analytical method called the incremental describing-function method is applied to the problem of ferroresonance in power systems for a certain class of problems. In general, the method is applicable when the conditions can be shown to be essentially single phase.
TL;DR: In this article, a very detailed description of the corona cycle results in a loss law which, in particular, shows the influence of the conductor capacity, and a more accurate calculation method is then described, the results of which agree very well with experience.
Abstract: After a brief description of the physical phenomena of ionization, charge movement, and ionic recombinations, a very schematic description of the corona cycle results in a loss law which, in particular, shows the influence of the conductor capacity. A more accurate calculation method is then described, the results of which agree very well with experience. This law enables the conductor losses to be determined beyond the critical voltage by the sole determination of its critical gradient.
TL;DR: In this paper, a series capacitor should be inserted in the remaining transmission lines when the fault is detected and removed by short circuiting when the time rate of change of power flow through the capacitor is zero or the rate for change of phase angle between line terminations is zero.
Abstract: Inserting and removing a series capacitor in a transmission line can remove the oscillatory transients due to a fault. The capacitor should be inserted in the remaining transmission lines when the fault is detected and removed by short circuiting when the time rate of change of power flow through the capacitor is zero or the rate of change of phase angle between line terminations is zero. The capacitor should be reinserted when the kinetic energy due to speed deviations equals the amount of kinetic energy that can be removed during the remaining swing to the target state independent of whether or not the line is restored to service.
TL;DR: In this paper, breakdown characteristics for both the noble and the more important molecular gases He, Ne, A, Kr, Xe, N2, H2, NH3, air, CO2, O2 (and Hg), particularly giving the probability of breakdown on which they are based, so that they can be used for dimensioning the relevant equipment.
Abstract: For the region pd<(pd)min, breakdown characteristics U2 = f(pd) are presented for both the noble and the more important molecular gases He, Ne, A, Kr, Xe, N2, H2, NH3, air, CO2, O2 (and Hg), particularly giving the probability of breakdown on which they are based, so that they can be used for dimensioning the relevant equipment. The design of vessel and electrode geometry which were introduced to determine these characteristics, and which have been tested up to a peak voltage of several hundred kilovolts, made it possible to study and describe the shape of the breakdown and flashover voltages relative to one another at pressures down to high vacuum (region of vacuum breakdown). They also provide an overall picture of the constructional facilities existing within the four following regions of ultimate stress, in which the breakdown voltage is determined by the ultimate electrical stressing of 1) the electrode surface (vacuum breakdown), 2) the insulator inside wall (internal flashover), 3) the insulator outside wall (external flashover), and 4) the gas path (Paschen breakdown). To express the probability of breakdown between 100 percent certainty (W = 1) and complete freedom from breakdown (W = 0), Poisson's formula may be used for the various breakdown mechanisms, i. e., for values of pd close to the respective kink and in the kinked part of the lefthand leg of the Paschen curve (regions 1-4 in Fig. 2), the value ?being proportional to the peak value of the applied voltage U.
TL;DR: In this paper, the dc circuit breaker is assumed to be an HVDC circuit breaker, and the functions to be assumed by such a circuit breaker are derived from its interaction with the electronic control and protection equipment.
Abstract: In the present stage of HVDC transmission technique, future applications may be outlined for which a multiterminal operation of HVDC converter stations would appear necessary or desirable. Simple problems, such as tapping of an HVDC transmission, can be solved by means of the known control and protection methods of the two-terminal operation. An unrestricted multiterminal operation, however, involves a number of additional requirements that relate to the control and protection equipment. For instance, it demands balancing of the reference values of all converter stations, which can be realized with a central electronic equipment. But it is also possible to indicate control methods for multiterminal operation that do not call for central reference value balancing and special communication facilities between the different stations. A problem of particular importance in multiterminal operation is the dc circuit breaker. The functions to be assumed by such an HVDC breaker may be derived from its interaction with the electronic control and protection equipment.
TL;DR: In this article, the authors propose to reduce the size of the system by the use of equivalents to represent portions of the network beyond the area of immediate interest, but their use offers the possibility of reducing the problem to manageable proportions.
Abstract: The reinforcement of power-system interconnections intensifies the need for stability studies. The growing complexity of the networks tremendously increases the difficulties of performing these investigations. Present computers are not capable of representing a major system pool in detail and producing a study in reasonable time and at reasonable cost. One possible solution is to reduce the size of the system by the use of equivalents to represent portions of the network beyond the area of immediate interest. Stability equivalents are not perfect, but their use offers the possibility of reducing the problem to manageable proportions.
TL;DR: In this article, the magnetizing inrush current for a single-phase transformer is derived and curves given for the peak, average, or rms current, and the theory can also be used for certain cases where there is direct current in a transformer winding and also for phase controlled rectifiers supplying a series resistance and inductance load.
Abstract: Formulas are developed and curves given for the magnetizing inrush current for a single-phase transformer. Series system inductance and resistance are included. The transformer is assumed to have no exciting current below saturation and constant saturated inductance above saturation. The formulas apply to circuits with either low or high resistance. The curves permit calculation of peak, average, or rms current, and show how these currents decay with time. The theory can also be used for certain cases where there is direct current in a transformer winding and also for certain types of phase controlled rectifiers supplying a series resistance and inductance load.
TL;DR: In this paper, the authors examined the phenomena which cause parasitic losses and developed analytical expressions to predict these losses in terms of the air gap field and the stator current, and showed that these losses can be high enough to absorb much of the developed torque.
Abstract: A major constraint on the performance prediction of a hysteresis machine arises from the parasitic losses associated with the rotor magnetic material. These losses can be high enough to absorb much of the developed torque, particularly for small sizes and large numbers of poles. In this paper the phenomena which cause parasitic losses are examined in detail. Analytical expressions are developed to predict these losses in terms of the air-gap field and the stator current.