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Power Systems, IEEE Transactions on

Issue 3 • Date Aug 1992

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Displaying Results 1 - 25 of 54
  • Estimation of marginal system costs and emissions of changes in generating unit characteristics

    Publication Year: 1992 , Page(s): 1251 - 1258
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (652 KB)  

    A method is presented for estimating the marginal system costs and emissions caused by the changes in the fixed costs, variable cost, emissions or capacity of generating units. Changes in dispatch order are accounted for. The method is based on a second-order Taylor series expansion of unit output as calculated by probabilistic production simulation. An approach is developed to compute the first and second derivatives of expected generation with respect to the capacity of a unit, which are essential components of the Taylor series approximation. An illustrative application is presented View full abstract»

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  • Evaluating dispatchability features in competitive bidding [in power systems]

    Publication Year: 1992 , Page(s): 1259 - 1265
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB)  

    Competitive bidding for electric generating capacity is beginning to emphasize dispatchability. The authors examine various aspects of the evaluation problem facing electric utilities. Recent private power contracts are used to illustrate the range and limits upon flexibility that are being offered. Only detailed production simulation models can capture the cost implications of the features being offered. The value of the dispatchability was found to increase with the variable cost of operation. The most important cost found was associated with projects offering only limited curtailment. Procedures for incorporating subtle dispatch effects in a broader evaluation framework are identified View full abstract»

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  • Geomagnetic effects modelling for the PJM interconnection system. I. Earth surface potentials computation

    Publication Year: 1992 , Page(s): 949 - 955
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    The authors describe an ionospheric source current model and the development of an Earth resistivity model used to calculate geomagnetic induced currents (GIC) on the Pennsylvania-New Jersey-Maryland interconnection (PJM). The ionospheric current was modeled as a Gaussian distributed current sheet above the Earth. Geological details are included by dividing the PJM service area into 11 different Earth resistivity regions. The resulting Earth surface potential (ESP) at each power system substation was then calculated View full abstract»

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  • Effect of superconducting magnetic energy storage on automatic generation control considering governor deadband and boiler dynamics

    Publication Year: 1992 , Page(s): 1266 - 1273
    Cited by:  Papers (16)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (580 KB)  

    A comprehensive digital computer model of a two-area interconnected power system including the governor deadband nonlinearity, steam reheat constraints, and the boiler dynamics is developed. The improvement in automatic generation control (AGC) with the addition of a small-capacity superconducting magnetic energy storage (SMES) unit is studied. Time-domain simulations were used to study the performance of the power system and control logic. Optimization of gain parameters and the stability studies were carried out by the second method of Lyapunov. Suitable methods for the control of SMES units are described View full abstract»

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  • A parametrically optimized self-tuning regulator for power system stabilizers

    Publication Year: 1992 , Page(s): 1245 - 1250
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (388 KB)  

    A parametrically optimized self-tuning regulator (POSTR) is proposed for the design of digital power system stabilizers. The proposed POSTR consists of an identification scheme which identifies the nonlinear power system with a predictive model and a control technique based on parameter optimization to derive the control law. The control design consists of choosing a suitable regulator structure then turning the associated parameters. The proposed stabilizer design technique has flexibility in specifying the order and the structure of the regulator which offers advantages in selecting and autotuning well-known effective controller structures. The computational requirements of the regulator are suitable for real-time implementation. Simulation study results are presented which show that the proposed technique outperforms the fixed parameters conventional stabilizer and the adaptive minimum variance self tuner View full abstract»

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  • A least squares solution for optimal power flow sensitivity calculation

    Publication Year: 1992 , Page(s): 1394 - 1401
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    A least-squares-based algorithm is proposed that is suitable for post optimal power flow (OPF) sensitivity calculations. It computes Lagrange multipliers. The algorithm involves the formulation of a Lagrangian which includes the appropriate objective function and all the enforced constraints. By applying the Kuhn-Tucker conditions, the derivatives of the Lagrangian at the solution with respect to free variables provide a set of over-determined equations for the Lagrange multipliers. A least-squares estimation of the Lagrange multipliers with the over-determined set of equations is used. The mathematical formulation of the least-squares problem for the sensitivity calculation is presented. A computationally efficient method of solving the normal equation is derived. Special care has been taken to accurately model all controls and all operating and security constraints. The algorithm has been tested on a reasonably large system. The results indicate the validity of the approach View full abstract»

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  • Short-range load forecasting for distribution system planning-an improved method for extrapolating feeder load growth

    Publication Year: 1992 , Page(s): 1306 - 1312
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    A method of extrapolating feeder peak load histories to produce estimates of future feeder loads is described. The method, an improvement on past multiple regression curve fit methods, uses an assumed geometry based on substation locations and a classification by recent growth rates to group feeders to six classes, each extrapolated in a slightly different manner. The method is simple enough to be applied in situations where computing resources are limited. A series of tests showed that the method outperformed other distribution load extrapolation methods, and that for short range forecasts, it matches the accuracy of simulation forecasting methods, which require considerably more data and computer resources View full abstract»

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  • Determining the value of conservation to Thailand's electric utility

    Publication Year: 1992 , Page(s): 1218 - 1224
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (788 KB)  

    Incorporating demand-side resources into the planning regime of fast-growing electric utilities in developing countries is a particular challenge. A method is developed for valuing the contribution of conservation under these circumstances and illustrated through scenarios of electricity savings in Thailand's large commercial sector. The primary value of these scenarios is in the creation of opportunities to defer or cancel plants planned for future inclusion in the system. The benefits of such deferments are twofold: a direct reduction in capacity needs commensurate with the load impacts of the scenario, plus a reduction in the reserve margin required to maintain system reliability. Comparison of the capital requirements of the conservation scenarios versus the deferrable plant capacity showed that conservation is substantially less capital intensive View full abstract»

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  • Implementation of genetic algorithm for distribution systems loss minimum re-configuration

    Publication Year: 1992 , Page(s): 1044 - 1051
    Cited by:  Papers (172)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB)  

    The loss minimum reconfiguration problem in the open loop radial distribution system is basically one of complex combinatorial optimization, since the normal open sectionalizing switches must be determined appropriately. The genetic algorithm was successfully applied to the loss minimum reconfiguration problem. In the proposed algorithm, strings consist of sectionalizing switch status or radial configurations, and the fitness function consists of the total system losses and penalty value of voltage drop and current capacity violations. The loss minimum reconfiguration problem is formulated as a mixed integer programming problem. The essential components of the genetic algorithm are briefly described. A detailed solution methodology by the use of genetic algorithm is outlined. Numerical examples demonstrate the validity and effectiveness of the proposed methodology View full abstract»

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  • An integrated laboratory for electric machines, power systems, and power electronics

    Publication Year: 1992 , Page(s): 1060 - 1067
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (768 KB)  

    A new-generation laboratory for electric power is described. The design and operation results are discussed. Examples of experiments are presented. The laboratory provides safe, modern, concept-intensive study of power devices and systems. Experience with the facility demonstrated that it is possible to create an integrated approach to the broad area of power devices, systems, and their control, without compromise of the laboratory experience View full abstract»

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  • Analysis of the load flow behaviour near a Jacobian singularity

    Publication Year: 1992 , Page(s): 1362 - 1369
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (604 KB)  

    The authors present theoretical results about the behavior of the load flow solution near a Jacobian singularity. The principal result is the derivation of an analytic closed-form relation between the specified injections and the resulting voltages in the neighborhood of a singularity. This result is a companion to the conventional load flow sensitivity analysis which is valid only if the operating point is not at a Jacobian singularity. The closed-form relation derived is theoretically important since it can predict and explain the main load flow phenomena observed through simulation analysis near a singularity. These are: the nonexistence of solutions of certain injection changes, the bifurcation of the voltages into two nearby solutions, the sudden collapse of voltages for small injection changes, and the nature of the collapse, that is, which buses are more susceptible to the collapse. Numerical simulations supported the validity of the theoretical result by comparing the closed-form analytic relation near a singularity with exact load flow simulations View full abstract»

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  • Using a semi-guided Monte Carlo method for faster simulation of forced outages of generating units

    Publication Year: 1992 , Page(s): 1313 - 1321
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (744 KB)  

    The authors describe a semi-guided Monte Carlo technique to schedule forced outage periods of generating units. The key advantage of this method lies in its ability to create forced-outage schedules that are statistically balanced. When tested against the pure Monte-Carlo method, the semi-guided Monte Carlo technique provided much faster convergence and greatly reduced the number of Monte Carlo iterations required to produce reliable product cost results. The Electricity Supply Board of Ireland has implemented this technique in its chronological dispatch program View full abstract»

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  • Dynamic aspects of voltage/power characteristics [multimachine power systems]

    Publication Year: 1992 , Page(s): 990 - 1000
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (820 KB)  

    The authors investigate the dynamic aspects of operation on a typical voltage/power curve. They discuss multiple stable equilibrium points in the context of small signal stability. A single machine example supplying different types of voltage-dependent loads is examined. A multimachine power system is also studied. Examples include a discussion on multiple stable operating points and the effects of different load characteristics View full abstract»

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  • Optimal scheduling of a multi-branched interconnected energy system

    Publication Year: 1992 , Page(s): 1225 - 1231
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB)  

    The authors present a planning tool designed to foresee the coordinated operation of an interconnected energy system with different sources and markets. The problem is to meet the demand of natural gas and electrical energy with the best possible utilization of the available resources: hydraulic energy, natural gas and sugar cane bagasse. The activity levels of thermal plants (natural gas and bagasse), which links different energy branches, must be adjusted in order to maximise the overall benefit represented by the objective function of the problem. A special algorithm for generalized networks implemented on a microcomputer was used to find solutions for a horizon of one year with monthly steps View full abstract»

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  • Alarm processing and fault diagnosis using knowledge based systems for transmission and distribution network control

    Publication Year: 1992 , Page(s): 1292 - 1298
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (740 KB)  

    The authors present two expert system developments which are each concerned with utilizing, to the best effect, the increasing volume of SCADA (supervisory control and data acquisition) system data available to power system control staff. The systems presented, APEX and RESPONDD, are aimed at the two related fields of alarm processing and fault diagnosis, respectively. The areas of commonality between these systems are discussed, as well as details specific to each separate system, including a case of study illustrating the practical operation of each View full abstract»

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  • Current issues in operational planning [of power systems]

    Publication Year: 1992 , Page(s): 1197 - 1210
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1408 KB)  

    This analysis is one of a series prepared on the behalf of the IEEE System Operations Subcommittee to focus the industry attention on current problems faced by power system operators. The analysis contains 6 short-note reports, describing current and emerging needs of electric utilities in the operational planning area. The authors concentrate on generation-related issues facing utilities in the 90s View full abstract»

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  • An approach for the regularization of a power flow solution around the maximum loading point

    Publication Year: 1992 , Page(s): 1068 - 1077
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (756 KB)  

    A method which is capable of greatly widening the range where the power flow solution is regular is presented. This is achieved by giving some modifications to the conventional power flow solution method and eliminating the singular point or shifting it to region where the voltage is lower than that of the maximum loading point. Then, the continuous execution of V-P curves including the maximum loading point is realized. The efficiency and effectiveness of the method were tested in a practical 598-node system are compared with the conventional method View full abstract»

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  • Efficient methods for finding transfer function zeros of power systems

    Publication Year: 1992 , Page(s): 1350 - 1361
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1136 KB)  

    The authors describe algorithms suited to the efficient calculation of both proper and nonproper transfer function zeros of linearized dynamic models for large interconnected power systems. They also described an improvement to the well-known AESOPS algorithm, formulating it as an exact transfer function zero finding problem which was efficiently solved by a Newton-Raphson iterative scheme. Large power system results are presented View full abstract»

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  • Representing the production cost curve of a power system using the method of moments

    Publication Year: 1992 , Page(s): 1370 - 1377
    Cited by:  Papers (4)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (636 KB)  

    The author presents an analytic formula, based on the equivalent load method, to calculate the production cost curve of a power system. A totally thermal generating system is assumed, although with some exceptions discussed the results extend to systems with limited energy and storage units. Their loading order positions are assumed known and fixed when the curves are calculated, determined beforehand by running a full production cost model. The formula consists of several terms of a Gram-Charlier series using moments which are computed in one iteration of the usual probabilistic production cost algorithm. The author demonstrates how to calculate the total production cost from the marginal cost curve, and shows how to decompose the system cost curve to simplify the repeated production cost calculations needed in generation planning models. Computational experience is discussed. Some mathematical details are presented View full abstract»

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  • Handling discardable measurements in power system state estimation

    Publication Year: 1992 , Page(s): 1333 - 1340
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (672 KB)  

    Observability analysis based exclusively on topological information may lead to systems whose state cannot be estimated by regular state estimation methods. The authors discuss some practical situations in which the presence of the so-called discardable measurements may pass undetected by topological observability analysis. As a consequence, wrong results, or even convergence problems, may occur. A numerically based observability analysis procedure is suggested for handling such cases. The technique is an extension of previously published work on numerical observability analysis. The technique is illustrated by small-scale examples taken from a real-life system where difficulties with discardable measurements have been observed View full abstract»

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  • Screening demand-side management programs with a value-based test

    Publication Year: 1992 , Page(s): 1031 - 1043
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1048 KB)  

    A value-based test is presented for economic screening of electric utility demand-side management (DSM) programs. The widely used least cost test is valid if the programs do not alter the amount or value of energy services provided to customers. But, in general, DSM programs have such effects and, as a result, the value consumers receive is changed. A more general economic efficiency test, the most value test, provides a practical method for considering the effects of DSM on customer value. The version presented allows for multiple load periods and can account for rate impacts on several customer classes. Four typical DSM programs are evaluated as illustrations View full abstract»

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  • Weather sensitive short-term load forecasting using nonfully connected artificial neural network

    Publication Year: 1992 , Page(s): 1098 - 1105
    Cited by:  Papers (74)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    The authors present an artificial neural network (ANN) model for forecasting weather-sensitive loads. The proposed model is capable of forecasting the hourly loads for an entire week. The model is not fully connected; hence, it has a shorter training time than the fully connected ANN. The proposed model can differentiate between the weekday loads and the weekend loads. The results indicate that this model can achieve greater forecasting accuracy than the traditional statistical model. This ANN model has been implemented on real load data. The average percentage peak error for the test cases was 1.12% View full abstract»

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  • Integration of remote measurement calibration with state estimation-a feasibility study

    Publication Year: 1992 , Page(s): 1164 - 1172
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (684 KB)  

    The authors describe the integration of measurement calibration and state estimation methodologies for increasing the confidence level in a real-time database. The objectives are to improve performance of state estimators and to reduce the system engineering effort which goes into its installations and the related measurement calibrations. These objectives are accomplished by remotely minimizing the systematic errors and providing the state estimator with zero-mean and the actual standard deviation for each measurement. The state estimator is then able to suppress the spurious errors and furnish a dependable real-time database for the computer control of power systems. The approach was supported by experimental results carried on a 55 bus portion of an actual power system View full abstract»

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  • An expert system for generator maintenance scheduling using operation index

    Publication Year: 1992 , Page(s): 1141 - 1148
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB)  

    A knowledge-based expert system for generator maintenance scheduling is presented. In the proposed system, generator maintenance scheduling (GMS) is considered as a constrained optimization problem. For different system operation conditions the objective function varies. An operation index is presented to determine an appropriate strategy for a decision-making process. The Taiwan Power Company (TPC) implementation is described. Tests for TPC cases in 1986 and 1987 are presented using the developed prototype GMS expert system. The results can meet TPC GMS requirements, which were still based on manual approaches and other conventional methods. The solution feasibility is discussed View full abstract»

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  • A critical survey of considerations in maintaining process continuity during voltage dips while protecting motors with reclosing and bus-transfer practices

    Publication Year: 1992 , Page(s): 1299 - 1305
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (636 KB)  

    Plantwide shutdowns can be avoided where voltage dips of short duration on the power distribution system are a primary cause. A voltage dip where contactors drop open and reclose can be very serious because of the nature of motors and their driven loads during voltage transients. The general nature of the problem and criteria for safe reclosing or transfer of several motors on the same bus are presented. The mathematical development and modeling techniques for induction and synchronous motors are indicated, and simple easy-to-use expressions are given for determining the currents and torques due to out-of-phase reclosing. Various protective schemes against out-of-phase reclosing and transfer, as well as methods of riding through voltage dips, are discussed 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.

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Meet Our Editors

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