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Power Systems, IEEE Transactions on

Issue 1 • Date Feb. 1996

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Displaying Results 1 - 25 of 75
  • Bibliography on transmission access issues

    Page(s): 30 - 40
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    This paper presents a bibliography on issue related to transmission access in electric power systems. There are 233 citations referenced in this bibliography. View full abstract»

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  • Economic Issues [Transmission Access Issues]

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    This section of the paper describes some of the unresolved and partially unresolved economic issues associated withi transmission access. View full abstract»

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  • 1995 Combined Index IEEE Transactions on Energy Conversion, Vol. 10(T-EC 95)) IEEE Transactions on Power Delivery, Vol. 10(T-PWRD 95)) IEEE Transactions on Power Systems, Vol. 10 (T-PWRS 95)

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    Freely Available from IEEE
  • Estimation of steady-state unbalanced system conditions combining conventional power flow and fault analysis software

    Page(s): 422 - 427
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    In real three-phase power systems, their voltages and currents are not fully symmetrical. A method has been developed to estimate the effects of slight unbalanced network conditions for steady-state operation. A conventional power flow is followed by a linear incremental calculation using a three-phase model of the network. The unbalanced condition is handled like a multiple unbalanced fault. The process is illustrated for the case of a transformer bank with nonidentical single-phase units. The results show the effects of different transformer reactances and different voltage ratios, respectively View full abstract»

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  • Distribution system reconfiguration for loss reduction: an algorithm based on network partitioning theory

    Page(s): 504 - 510
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    The algorithm proposed in this paper provides the facility to achieve on-line distribution system reconfiguration for loss reduction. Based on partitioning the distribution network into groups of load busses, such that the line section losses between the groups of nodes are minimized, the proposed method overcomes the size restrictions imposed by previously described reconfiguration techniques. By dividing the distribution network into groups of busses, the combinatorial nature of the reconfiguration problem is overcome, while simultaneously minimizing losses. Computer simulations, of the proposed method, demonstrate the numerous benefits that are offered by the proposed reconfiguration algorithm View full abstract»

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  • Combined genetic algorithm/simulated annealing/fuzzy set approach to short-term generation scheduling with take-or-pay fuel contract

    Page(s): 128 - 136
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    This paper first develops a new formulation for short-term generation scheduling with take-or-pay fuel contract. In the formulation, a fuzzy set approach is developed to assist the solution process to find schedules which meet as closely as possible the take-or-pay fuel consumption. The formulation is then extended to also cover the economic dispatch problem when the fuel consumption is higher than the agreed amount in the take-or-pay contract. The extended formulation is combined with the genetic algorithms and simulated-annealing optimization methods for the establishment of new algorithms for the present problem. The new algorithms are demonstrated through a test example, in which the generation loadings of 13 generators in a practical power system are scheduled in a 24-hour schedule horizon View full abstract»

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  • State estimation for distribution systems with zero-injection constraints

    Page(s): 518 - 524
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    In this paper, a new fast decoupled state estimator with equality constraints is proposed for the three-phase distribution systems. The Lagrange multipliers were utilized to deal with the zero injections. The proposed method is based on the equivalent-current-measurement and rectangular coordinates. The method uses a compact constant-symmetric gain matrix which can be decoupled into two “identical” sub-gain matrices. The update and factorization of the gain matrix needs to be done only once. Tests have shown that the proposed low-storage method is efficient, accurate and robust in solving the unbalanced three-phase distribution systems View full abstract»

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  • Analytical modeling of thyristor-controlled series capacitors for SSR studies

    Page(s): 119 - 127
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    Thyristor-controlled series capacitors (TCSC) have dynamic characteristics that differ drastically from conventional series capacitors especially at frequencies outside the operating frequency range. Therefore suitable models are needed to properly study the applications of TCSC on a utility power system. An accurate analytical model of the TCSC which is valid in the frequency range from 0 Hz to twice the operating frequency is presented. The model incorporates the thyristor triggering logic, the synchronization system, and higher level control loops such as power oscillation damping loop. This model is suited for linearized analyses of a power system using frequency domain methods such as eigenvalues. It is particularly valuable in studying subsynchronous resonance (SSR) enables the utility industry to better evaluate interactions between TCSC and other devices View full abstract»

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  • Conceptual designs of AI-based systems for local prediction of voltage collapse

    Page(s): 137 - 145
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    Vulnerability of modern power systems to locally initiated voltage collapse gives rise to a need for methods to measure local voltage security and to predict voltage instability. The paper presents a novel architecture based on a suite of AI technologies and three-dimensional PQV surfaces which provides prediction of local voltage collapse and indices of system voltage security. Robustness and adaptation are demonstrated on difficult and realistic power system simulation models View full abstract»

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  • Object-oriented programming, C++ and power system simulation

    Page(s): 206 - 215
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    Application of OOP concepts and the C++ programming language to power system simulation has been explored. An efficient platform for power system simulation applications has been proposed. By emulating a physical power laboratory, a generic power network container has been built. A module, which can be used to solve sparse matrix equations of any data types, has been implemented. Two load flow applications, a DC load flow and an AC load flow, have been discussed. It is found that OOP based C++ load flow programs are as efficient as their nonOOP counterparts View full abstract»

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  • Synchronic modal equivalencing (SME) for structure-preserving dynamic equivalents

    Page(s): 19 - 29
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    A novel framework for dynamic equivalencing of interconnected power systems that the authors recently introduced in the context of classical swing-equation models is extended in this paper to detailed models in structure-preserving, differential/algebraic-equation form. The system is partitioned into a study area and one or more external areas on the basis of synchrony, a generalization of slow-coherency that forms one leg of their framework. Retaining a detailed model for a single reference generator from each external area, the dynamics of the remaining external generators are then modally equivalenced in the style of selective modal analysis; this modal equivalencing is the other leg of their framework. The equivalenced external generators are thereby collectively replaced by a linear multi-port “admittance”, which is easily represented using controlled current injectors at the buses of the replaced generators. The rest of the system model can be retained in its original nonlinear dynamic form. The approach is tested-with encouraging results-on the familiar third-order, 10-machine, 39-bus New England model, using an implementation in the EUROSTAG simulation package View full abstract»

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  • A preconditioned fast decoupled power flow method for contingency screening

    Page(s): 357 - 363
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    This paper proposes an efficient method for contingency screening in power systems. Contingency analysis requires substantial amounts of computational time in evaluating data for controlling generating units or power flows. In this paper, the Tchebychev iteration method of an indirect method is presented for solving a set of linear equations of fast decoupled power flow (FDPF) in the contingency screening. Furthermore, the precondition technique is introduced to improve the convergence characteristics of the indirect method. The proposed method has been successfully applied to a 2107 node system View full abstract»

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  • Computer aided power flow software engineering and code generation

    Page(s): 490 - 496
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    In this paper a software engineering concept is described which permits the automatic solution of a nonlinear set of network equations. The power flow equation set can be seen as a defined subset of a network equation set. The automated solution process is the numerical Newton-Raphson solution process of the power flow equations where the key code parts are the numeric mismatch and the numeric Jacobian term computation. It is shown that both the Jacobian and the mismatch term source code can be automatically generated in a conventional language such as Fortran or C. Thereby one starts from a high level, symbolic language with automatic differentiation and code generation facilities. As a result of this software engineering process an efficient, very high duality Newton-Raphson solution code is generated which allows easier implementation of network equation model enhancements and easier code maintenance as compared to hand-coded Fortran or C code View full abstract»

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  • Short-term hydro generation and interchange contract scheduling for Swiss Rail

    Page(s): 274 - 280
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    This paper describes the Short-Term Resource Scheduling (STRS) function that has been developed by Siemens-Empros as part of the new SBB/Direktion Kraftwerk (Swiss Rail) Energy Management System. Optimal scheduling of the single-phase hydro plants, single-phase and three-phase energy accounts, and purchase and sale of three phase energy subject to a multitude of physical and contractual constraints (including spinning and resulting reserve requirements) is the main objective of the STRS function. The operations planning horizon of STRS is one day to one week using an hourly time increment View full abstract»

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  • Identification of ARMAX model for short term load forecasting: an evolutionary programming approach

    Page(s): 403 - 408
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    This paper proposes a new evolutionary programming (EP) approach to identify the autoregressive moving average with exogenous variable (ARMAX) model for one day to one week ahead hourly load demand forecasts. Typically, the surface of forecasting error function possesses multiple local minimum points. Solutions of the traditional gradient search based identification technique therefore may stall at the local optimal points which lead to an inadequate model. By simulating natural evolutionary process, the EP algorithm offers the capability of converging towards the global extremum of a complex error surface. The developed EP based load forecasting algorithm is verified by using different types of data for practical Taiwan power (Taipower) system and substation load as well as temperature values. Numerical results indicate the proposed EP approach provides a method to simultaneously estimate the appropriate order and parameter values of the ARMAX model for diverse types of load data. Comparisons of forecasting errors are made to the traditional identification techniques View full abstract»

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  • Computing dominant poles of power system transfer functions

    Page(s): 162 - 170
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    This paper describes the first algorithm to efficiently compute the dominant poles of any specified high order transfer function. As the method is closely related to Rayleigh iteration (generalized Rayleigh quotient), it retains the numerical properties of global and ultimately cubic convergence. The results presented are limited to the study of low frequency oscillations in electrical power systems, but the algorithm is completely general View full abstract»

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  • Two applications of parallel processing in power system computation

    Page(s): 246 - 253
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    This paper discusses performance improvements achieved in two power system software modules through the use of parallel processing techniques. The first software module, EVARISTE, outputs a voltage stability indicator for various power system situations. This module was designed for extended real-time use and is therefore required to give guaranteed response times. The second module, MEXICO, assesses power system reliability and operating costs by simulating a large number of contingencies for generation and transmission equipment. This module, used for power system planning purposes, uses a Monte-Carlo method to build the various system states, and makes heavy demands on CPU time for running simulations. Like many power system computation packages, both software modules are well-suited to coarse-grain parallel processing. The first module was parallelized on a distributed-memory machine and the second on a shared-memory machine. In this paper, we start by giving a description of the parallelization process used in these two cases, then go on to give details on the performance levels achieved, discussing aspects of programming, parameter selection (number of situations processed, number of processors), and machine characteristics (limitations due to interprocessor communications network, for instance) View full abstract»

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  • Scheduling units with multiple operating modes in unit commitment

    Page(s): 497 - 503
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    The operating flexibility of certain types of generating units can be exploited to reduce the production cost of their system. These units have different operating modes where the operating parameters can differ greatly depending on which mode is operating at the time. Examples of such units are: combined cycle, fuel switching/blending, constant/variable pressure, overfire and dual boiler. A general modeling approach is described which can be used to model units with multiple operating modes. It is shown how Lagrangian relaxation can be used to schedule these units. Examples are given showing the benefit of using these methods to schedule a utility's system View full abstract»

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  • A genetic algorithm solution to the unit commitment problem

    Page(s): 83 - 92
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    This paper presents a genetic algorithm (GA) solution to the unit commitment problem. GAs are general purpose optimization techniques based on principles inspired from the biological evolution using metaphors of mechanisms such as natural selection, genetic recombination and survival of the fittest. A simple GA algorithm implementation using the standard crossover and mutation operators could locate near optimal solutions but in most cases failed to converge to the optimal solution. However, using the varying quality function technique and adding problem specific operators, satisfactory solutions to the unit commitment problem were obtained. Test results for power systems of up to 100 units and comparisons with results obtained using Lagrangian relaxation and dynamic programming are also reported View full abstract»

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  • A heuristic method for reactive power planning

    Page(s): 68 - 74
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    An approach for solving power system reactive power planning problems is presented, which is based on binary search techniques and the use of a special heuristic to obtain a discrete solution. Two versions were developed, one to run on conventional (sequential) computers and the other to run on a distributed memory (hypercube) machine. This latter parallel processing version employs an asynchronous programming model. Once the set of candidate buses has been defined, the program gives the location and size of the reactive sources needed (if any) in keeping with operating and security constraints View full abstract»

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  • Enhanced techniques on sequential unit commitment with interchange transactions

    Page(s): 93 - 100
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    This paper presents two enhanced techniques for improving the solution optimality and computation performance of the sequential unit commitment (SC) method with interchange transactions. The conventional SC method, although often presenting superior performance over other methods, can lead to nonnear-optimal solutions in some circumstances due to the use of a local decision scheme to identify the best unit to be committed at each stage. The proposed technique, instead, uses a global-like decision scheme. It defines a small set of locally advantageous units which are individually examined globally by generating tentative commitment schedules to identify the globally best unit to commit at each stage. Studies have shown that the global-like decision scheme can effectively improve the solution optimality. Meanwhile, while an interchange transaction is incorporated with the unit commitment study, the constant transaction price often causes solution oscillation during iterations. A varying-λ technique is proposed in this paper. This technique properly models the impact of the interchange transactions on the power system hourly energy prices and, hence, successfully overcomes the oscillation problem such that the loading level of a transaction can be optimally determined similarly as for a generating unit View full abstract»

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  • Practical experience with corrective switching algorithm for on-line applications

    Page(s): 415 - 421
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    The objective of the corrective switching algorithm (CSA) is to identify switching candidates to eliminate or reduce power system overloads. This paper describes the implementation of the CSA for online contingency analysis. The developed program searches for the best switching candidates from a user specified list, which normally includes all branches in the study area and most typical switching operations (openings and closings) at main substations. The developed algorithm has the unique ability to process complicated substation busbar switching scenarios, including multiple switching scenarios per any substation. The selection algorithm is based on a linearized DC model, but all selected candidates are verified using AC load flows. The program has been used as part of the security analysis program at Public Service Electric and Gas Company (PSE&G) since Summer 1994 and has proved its reliability and efficiency View full abstract»

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  • An object-oriented approach for implementing power system restoration package

    Page(s): 483 - 489
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    Due to many unforeseen circumstances that could happen in today's bulk power system, there is a possibility of a system wide outage. In order to provide aids to the power system dispatchers following a complete collapse of the power system, a prototype package has been developed. Through an interactive and friendly graphic interface, the package suggests a guideline for the dispatcher to restore the power system. With an aim to increase the ease of maintenance, an object-oriented technique was adopted to implement the package. The development of the software involved three stages: (1) object oriented analysis, (2) object oriented design, and (3) integration and testing. In this paper, the structure and the development procedure of the prototype system are presented View full abstract»

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Aims & Scope

Covers the requirements, planning, analysis, reliability, operation, and economics of electric generating, transmission, and distribution systems for general industrial, commercial, public, and domestic consumption.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Antonio J. Conejo
The Ohio State University