Showing papers on "Power-flow study published in 1981"
TL;DR: In this paper, a mathematical formulation of the optimal reactive power control (optimal VAR control) problem and results from tests of the algorithm are presented in order to minimize the real power losses in the system.
Abstract: A mathematical formulation of the optimal reactive power control (optimal VAR control) problem and results from tests of the algorithm are presented in this paper. The model minimizes the real power losses in the system. The constraints include the reactive power limits of the generators, limits on the load bus voltages, and the operating limits of the control variables, i.e., the transformer tap positions, generator terminal voltages and switchable reactive power sources. Real power economic dispatch is accomplished by standard techniques.
367 citations
TL;DR: In this paper, most of the excitation systems currently in widespread use on large, system connected generators in North America can be represented and used for large-scale system stability studies.
Abstract: Excitation system models suitable for use in large scale system stability studies are presented in this paper. With these models, most of the excitation systems currently in widespread use on large, system connected generators in North America can be represented.
349 citations
TL;DR: In this paper, a set of Generalized Generation Distribution Factor (GGDF) is developed to replace the conventional GDF's, which are especially suitable for constraint formulation in mathematical programning, such as optimal generation dispatch with security contingencies considered.
Abstract: A set of Generalized Generation Distribution Factors (GGDF's) is developed to replace the conventional Generation Shift Distribution Factors (GSDF's). This model relates the line flows with generations for a given network configuration. Being in an integral form, new flows on lines can be obtained directly without running load flows when total system generation changes. Conforming load change is also demonstrated. These new factors are especially suitable for constraint formulation in mathematical programning, such as optimal generation dispatch with security contingencies considered
263 citations
TL;DR: In this article, a technique for selecting the parameters of stabilizers in multimachine power systems is presented, which enables the selection of the stabilizers such that specified improvements in the damping ratios of the poorly damped modes of oscillation are realized approximately.
Abstract: This paper presents a technique for selecting the parameters of stabilizers in multimachine power systems. The technique enables the selection of the parameters of stabilizers such that specified improvements in the damping ratios of the poorly damped modes of oscillation are realized approximately. A numerical example of a multimachine system is presented to illustrate the proposed technique.
181 citations
TL;DR: In this article, the authors review experience in the control design and tuning of power system stabilizers for thermal generating units and highlight special problems encountered in obtaining satisfactory performance at a particular generating station due to specific generator characteristics.
Abstract: This paper reviews experience in the control design and tuning of power system stabilizers for thermal generating units. Special problems encountered in obtaining satisfactory performance at a particular generating station due to specific generator characteristics is highlighted. Analytical techniques used for establishing suitable stabilizer settings are described and their effectiveness in duplicating field measurements is demonstrated
115 citations
TL;DR: In this article, the authors discuss the phenomena by which geomagnetic induced currents are produced in power systems, the system and transformer modeling necessary for representing the effects, and the results of load-flow studies made with GIC present in a large interconnected power system in the northern United States and Canada.
Abstract: Large transient fluctuations in the earth's magnetic field can produce quasi-dc currents in electric power systems. These geomagnetically-induced currents (GIC's) cause half-cycle saturation in power transformers resulting in increased transformer var requirements. This paper discusses the phenomena by which GIC's are produced in power systems, the system and transformer modeling necessary for representing the effects, and the results of load-flow studies made with GIC present in a large interconnected power system in the northern United States and Canada. Results of the studies are compared with data recorded during a geomagnetic storm.
106 citations
TL;DR: In this article, the authors present an efficient approach to system restoration from a complete collapse under peak and light load conditions, developed at Potomac Electric Power Company (PEPCo).
Abstract: The extended duration of recent major power system disturbances have indicated the need for development of system restoration plans (SRP), which would minimize the time required for restoration of service. This paper presents an efficient approach to SRP, from a complete collapse under peak-and light-load conditions, developed at Potomac Electric Power Company (PEPCo). The method is based on: (a) the combined effort of operating personnel and system analysts, (b) the access to data available from the on-line computer facilities, and (c) the use of an interactive load flow program. The SRP development procedure and the results described in this paper are of general interest in that they can be adopted and applied to the other electric systems.
93 citations
01 Oct 1981
TL;DR: A review of the subject of electric power dispatching can be found in this article, where the authors show where dispatching fits into the hierarchy of power system operating and planning problems and provide an overview of the issues, concerns and practices of dispatching.
Abstract: This paper provides a review of the subject of electric power dispatching. In Section I we show where dispatching fits into the hierarchy of power system operating and planning problems. Section II provides an overview of the issues, concerns and practices of dispatching. Sections III-V are devoted to the algorithmic aspects of dispatching. Finally, in Section VI we highlight the conclusions reached in the proceeding sections and identify a number of research needs.
87 citations
TL;DR: In this paper, a simple and economical technique for measuring voltage phase angles and generator shaft angles is reviewed, and the principle is briefly exposed and its practical operation is illustrated by an experiment in a real power system.
Abstract: A simple and economical technique for measuring voltage phase angles and generator shaft angles is reviewed. The principle is briefly exposed and its practical operation is illustrated by an experiment in a real power system. Due to the importance of accurate time for this application a short survey on time dissemination systems is included. The main part of the paper is devoted to the possible applications of phase angle measurements for the control and monitoring of power systems. The discussion deals with various topics and makes ample reference to available literature. The paper is intended as an information survey for assessing the practical significance of phase angle measurements
75 citations
TL;DR: In this article, spectral analysis of system response to random load changes has become a standard engineering tool at the Bonneville Power Administration and has been used to estimate the required size for a superconducting electromagnetic storage device which will provide backup to HVDC Modulation.
Abstract: In recent years spectral analysis of system response to random load changes has become a standard engineering tool at the Bonneville Power Administration. Analysis of random fluctuations in power on the Pacific AC Intertie has provided information about the influence of system operating conditions upon the effectiveness of Pacific HVDC Intertie modulation, and about dynamic behavior of the western power system generally. This technique has also been used to estimate the required size for a superconducting electromagnetic storage device which will provide backup to HVDC Modulation, and has detected a major system mode 6 months before it was first observed in a transient disturbance
65 citations
TL;DR: In this paper, the success of many of these methods has hinged greatly on the use of the Z matrix reference to swing or an arbitrary ground tie, and a mathematical basis for these heuristic methods is provided.
Abstract: Fast linear load flows used in contingency analysis, interchange studies and many optimization schemes often utilize power distribution factors. The success of many of these methods has hinged greatly on the use of the Z matrix reference to swing or an arbitrary ground tie. This paper furnishes a mathematical basis for these heuristic methods.
01 May 1981
TL;DR: In this article, the generalized theory of electric power is presented, which makes it possible to estimate the operation of complex electric circuits, and new definitions have been found for various kinds of power occurring in such systems.
Abstract: The paper presents the generalized theory of electric power, which makes it possible to estimate the operation of complex electric circuits. Use has been made of the correlation analysis and new definitions have been found for various kinds of power occurring in such systems. It has been shown that both the active and the reactive power depend on the voltage-current correlation of the system. A new definition has been found for the distortion power, together with the condition which leads to its minimization.
TL;DR: In this paper, a method for reenergizing large portions of a blacked out electric power system with a minimum of switching and thus time to restoration is described, and results of a simulated system restart utilizing actual power system facilities are compared to power flow studies.
Abstract: Time is the crucial element in restorative state control for electric power systems. One method for reenergizing large portions of a blacked out electric power system with a minimum of switching and thus time to restoration, is described. Results of a simulated system restart utilizing actual power system facilities are compared to power flow studies. The simulation tests were performed on the Los Angeles Department of Water and Power (LADWP) system in order to verify the concept of utilizing generation operating at extremely low voltage to energize as large a part as possible of the unloaded bulk power transmission system located within the service area.
TL;DR: Development of a computer algorithm which can select one overall reactive power installation pattern that will satisfy system performance constraints for both base case and contingency conditions is discussed.
Abstract: This paper discusses development of a computer algorithm which can select one overall reactive power installation pattern that will satisfy system performance constraints for both base case and contingency conditions. The cost of installation and base case losses are minimized. In addition, existing controllers are fully utilized prior to any addition of new installation. The computing algorithm employs a reduced gradient method of optimization in conjunction with simplex and integer routines to solve the reactive power allocation problem. The resulting program has been tested on a sample Consolidated Edison system.
01 Dec 1981
TL;DR: In this paper, the Liapunov practical stability domain is estimated using the acceleration approach, which is shown to be reliable, straightforward, and computationally very fast for on-line stability assessment.
Abstract: We propose a systematic approach for estimating the Liapunov practical stability domain, along with some other fast techniques for transient stability analysis of power systems. The direct criterion thus derived is investigated and illustrated through a good number of simulations performed on several test systems and practical power networks. It is shown to be reliable, straightforward and computationally very fast. Besides being appropriate for conventional studies, the acceleration approach offers also another interesting possibility: the derivation of a transient stability index for on-line stability assessment and contingency evaluation.
TL;DR: In this article, a load-flow and short-circuit analysis of a coal mine power system is presented, where the topology of the dc network is constantly changing due to the movement of locomotives along the track.
Abstract: Many present-day industrial power systems have combined ac/dc power distribution systems. A typical example is a coal mine power system, where ac is used for running the mining equipment and dc is used for track haulage, etc. Also, the topology of the dc network is constantly changing due to the movement of locomotives along the track. Methods are described that can be used to carry out load-flow and short-circuit analyses of such a system.
TL;DR: In this article, the authors present a series prepared for use in Current Operations Problems (CoPs) forums with the goal of focusing the attention of the industry on high priority problems faced by those who are involved in the actual operation of power systems.
Abstract: This paper is one of a series prepared for use in Current Operations Problems (CoPs) forums with the goal of focusing the attention of the industry on high priority problems faced by those who are involved in the actual operation of power systems.
TL;DR: The hardware and the software of a multiprocessor system including the algorithm of the analysis of the power system analysis are discussed including the Gauss iterative method.
Abstract: As the technology of computer hardware advances, the speedup of power system analysis becomes more and more necessary In order to study about future power system analysis by parallel processing, we made a prototype of a multiprocessor system In this paper, after explaining the parallel processing in power system analysis, we will discuss the hardware and the software of a multiprocessor system including the algorithm of the analysis We solved the load flow problem as an example of the analysis and compared the multiprocessor system to a conventional sequential machine (COSMO 700-II) in regard to the calculation result The load flow method used in the multiprocessor system is the Gauss iterative method Each processor calculates the equations of each node in the power system As the number of nodes increases, the multiprocessor system becomes superior to the conventional sequential machine (COSMO 700-II) in terms of calculation speed
TL;DR: In this article, the authors provide a specification for the exchange of power plant and load data in five categories: generator data, excitation system data, power system stabilizer data, speed-governing system data and composite load data.
Abstract: This paper provides a specification for the exchange of power plant and load data in five categories: generator data, excitation system data, power system stabilizer data, speed-governing system data, and composite load data.
TL;DR: The new method presented in this paper, the coordination of the dc network's power transfers is simplified considerably to that of solving a linear matrix equation of order one Less than the number of converter terminals.
Abstract: The scheduling of the power transfers of a multiterminaL dc network to control the power distribution in certain ac lines of an ac-dc system requires coordination. With the new method presented in this paper, the coordination of the dc network's power transfers is simplified considerably to that of solving a linear matrix equation of order one Less than the number of converter terminals. The Losses, as well as the power limits of the converters, in the dc network are considered in the method of coordination. This method of coordination is combined with a standard ac-dc load-fLow, whose purpose is to estabLish the resuLtant operating point of the ac-dc system, to form an algorithm for scheduling the dc network's power transfers to control the power distribution in certain ac lines of an ac-dc system. The tests performed on a 5 dc terminaL, 30 ac bus, sample system showed that the power flows, close to the desired values, in a number of the ac Lines could be simultaneously obtained with just one iteration of the proposed algorithm. The algorithm proved to be efficient and effective in these tests. The algorithm can be used to plan dc network reinforcements to an ac network and is potentially suitable for the on-line application of networK flow control.
TL;DR: In this article, the authors describe the optimal power flow problem and progress toward its solution since its inception in theory to its present form and present and future applications of Optimal Power Flow programs in system planning and system operations and control.
Abstract: This paper describes the Optimal Power Flow problem and progress toward its solution since its inception in theory to its present form. Present and future applications of Optimal Power Flow programs in system planning, and system operations and control will be presented. The sensitivity calculation and application to optimal power flow theory will be presented.
TL;DR: A new approach for direct and compact derivation of sensitivity expressions in electrical power networks is presented utilizing a compact complex notation with a properly chosen complex state variable terminology.
Abstract: A new approach for direct and compact derivation of sensitivity expressions in electrical power networks is presented utilizing a compact complex notation with a properly chosen complex state variable terminology. It employs only complex matrix manipulations and exploits the elements of the Jacobian matrix already available from the solution of the load flow problem.
TL;DR: In this article, the authors present a method of analysis of power system reactive power and voltage control problems by means of known equivalent circuits of power systems and of power transformers with tap-changers.
Abstract: The paper presents a method of analysis of power system reactive power and voltage control problems by means of known equivalent circuits of power systems and of power transformers with tap-changers. The method yields insight into the physical effects of tap-changer operations on system reactive power flows and voltage changes and enables one to get reasonably good quantitative estimates of the magnitude of these changes. The method also yields insight into "optimum" strategies for tap-changer controllers in order to optimize transformer operation and enables one to determine tap-changer requirements for system control problems such as reactive power transfers between systems.
TL;DR: The problem of reducinm computer running times for bulk power system reliability calculations is solved by applying an implicit enumeration scheme to reduce the number of generation states tested and introducing an extremely fast linear optimization algorithm.
Abstract: The problem of reducinm computer running times for bulk power system reliability calculations is solved by applying an implicit enumeration scheme to reduce the number of generation states tested and introducing an extremely fast linear optimization algorithm.
TL;DR: In this paper, a digital simulator has been developed which incorporates nonlinear mathematical models for: a PWR, pressurizer, steam generator, coolant pumps, steam and hydro-turbines, synchronous machines, loads and other network components, plant controllers and speed governors.
Abstract: This work aims at modeling, simulating and analyzing the dynamic performance of the first egyptian pressurized water reactor nuclear power plant as a power supply in a forecasted national power system. A digital simulator has been developed which incorporates nonlinear mathematical models for: a PWR, pressurizer, steam generator, coolant pumps, steam and hydro-turbines, synchronous machines, loads and other network components, plant controllers and speed governors. The results obtained include: 1. The dynamic response of the nuclear plant following the forced outage of two of the feeding Transmission Lines (T.L's.), i.e. 21 % loss of the area power supply. 2. The overall system frequency behaviour following the disconnection of the PWR plant. 3. A comparison between Dynamic Energy Balance (DEB) frequency calculations of the overall power system (represented by its center of inertia) and the transient stability calculations of the nuclear plant system frequency following the loss of 28 % of the area power supply.
TL;DR: In this paper, a decoupled fonnulation for static state estimation in power systems is developed, and efficient state estimation algorithms for small as well as for large power systems are derived and shown to rapidly yield the required state vector.
Abstract: A new decoupled fonnulation for static state estimation in power systems is developed in this paper. Efficient state estimation algorithms for small as well as for large power systems are derived, and shown to rapidly yield the required state vector.
01 Jan 1981