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Power Systems, IEEE Transactions on

Issue 3 • Date Aug. 1987

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Displaying Results 1 - 25 of 59
  • Table of contents

    Page(s): c1
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    Freely Available from IEEE
  • IEEE Power Engineering Society

    Page(s): c2
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    Freely Available from IEEE
  • A Self Commutated Power Converter for Stabilizing Torsional Interactions

    Page(s): 513 - 521
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    A recently proposed method of counteracting torsional interactions referred to as transmission current feedback involves the measurement of the transmission system currents from which the subsynchronous components that produce torsional interactions are extracted. Once extracted, these are suitably amplified by a power converter and injected into the generator bus of the affected steam turbine so as to cancel the original subsynchronous components which would otherwise produce torsional interactions. In this paper, a power converter capable of supplying the required subsynchronous currents is described. An analytic model relating the converter output currents to its controlling variables is derived and a suitable control strategy is formulated. A detailed hybrid computer simulation of the converter is used to verify the accuracy of the analytic representation of the converter and the effectiveness of the control strategy. View full abstract»

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  • Design of Optimal Modulation Controllers for Multiarea AC/DC Systems Using Eigenvalue Sensitivities

    Page(s): 522 - 528
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    This paper develops a new technique for the design of optimal modulation controllers for multi-area ac/dc systems. The technique is based on optimal pole assignment using eigenvalue sensitivities. The basic feature of the proposed method is that both the diagonal and the off-diagonal elements of the weighting matrices are used for the eigenvalue assignment which results in increased design flexibility. The method is applied to the design of a modulation controller for a strongly interconnected three area ac/dc system. Dynamic simulation results presented in the paper show that the proposed modulation controller results in significant improvement of dynamic performance of the interconnected system. View full abstract»

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  • A Microcomputer Based On-Line Identification Approach to Power System Dynamic Load Modelling

    Page(s): 529 - 536
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    An on-line method for the development of power system load models using system identification techniques is presented. The modelling procedure involves the selection of the load model structure as well as the estimation of the load model parameters. A load model structure selection technique based on the model reference error cost function is used and a square root based least squares estimator is developed. The collection of large volumes of data, for later off-line analysis, is avoided by using an online microcomputer system for the acquisition and analysis of perturbed load data. Load tests were carried out for both agricultural and industrial/commercial loads and typical results obtained are also presented in this paper. View full abstract»

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  • An Efficient Hydrothermal Scheduling Algorithm

    Page(s): 537 - 542
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    In this paper a Hydrothermal Scheduling Algorithm (HSA) for deterministic inflows is presented. A nonlinear network flow model representing the hydrothermal scheduling problem is used. By exploiting the special network structure, a temporally expanded arborescence [1], the HSA code attains important computational savings in processing time and memory requirements allowing the use of microcomputers even for large scale problems. The main feature of the HSA code is a dynamic base choice that enables the decision maker to improve the convergence of the optimization procedure by the use of his practical experience. The performance of the algorithm is tested on the Southeast Brazilian Power System. View full abstract»

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  • Coordinated Synthesis of Multimachine Power System Stabilizer Using an Efficient Decentralized Modal Control (DMC) Algorithm

    Page(s): 543 - 550
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    This paper presents a new method for simultaneously selecting the power system stabilizer (PSS) parameters in multimachine power systems. Design of local output feedback power system stabilizer using local signal of the generator (e.g. speed or power) is formulated as a decentralized modal control (DMC) problem. Exact model reduction based on modal control theory is proposed to make the determination of PSS parameters highly efficient. Results obtained from the coordinated tuning of the parameters of three power system stabilizers equipped on a multimachine power system show that exact assignment of the eigenvalues associated with the poorly damped electromechanical modes can be achieved in a very efficient manner. View full abstract»

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  • Discussion

    Page(s): 550 - 551
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  • Autoregressive Filters for the Identification and Replacement of Bad Data in Power System State Estimation

    Page(s): 552 - 558
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    The quadratic cost function J(x¿) and the normalized residuals rN are used conventionally for identifying the presence and location of bad measurements in power system state estimation. These are "post estimation" tests and therefore require the complete re-estimation of system states whenever bad data is identified. This paper presents a pre-estimation filter for detection and identification of gross measurement errors. The basic function of this filter is to compare the measured value of a system variable with its predicted value obtained using an autoregressive (AR) model. If the difference exceeds a pre-determined threshold, the measured value is discarded in favor of the predicted value. Each measurement is processed by an AR filter before being used in the state estimation. The performance of the AR filter is tested against that of the J(x¿) and rN tests and the results are reported in this paper. The principal advantage of the AR filtering scheme is its speed in bad data identification. Furthermore, it can be used to complement other bad data processing methods. View full abstract»

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  • Discussion

    Page(s): 558 - 560
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  • Controllable Var Compensator: A Potential Solution to Loadability Problem of Low Capacity Power Systems

    Page(s): 561 - 567
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    The stability of the voltage at the receiving end of radial transmission links puts a limit on the amount and character of load that can be connected at that end. The paper demonstrates the potential of having a static var compensator SVC for supporting the voltage at the load end and therefore increasing the loadability of such links. Radial links of different transmission voltages and lengths as well as loads of different characters have been considered in showing the effectiveness of SVC. A general formula defining the sensitivity of receiving end voltage to shunt compensation has been developed. With the aid of this formula the regulator gain of the used SVC control model has been dimensioned and the steady state loadability limits of radial transmission links, at different load character, can be established analytically. View full abstract»

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  • A Method of Representing Isolated Operation of a Group of Induction Motor Loads

    Page(s): 568 - 575
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    A method of representing the isolated operation of a group of induction motor loads using reduced order equations is presented. The method differs from the standard method of neglecting stator transients in that the rate of change of stator flux linkages are neglected in a reference frame whose speed varies as a function of the stator frequency. The accuracy of the resulting reduced order representation is investigated by comparing its response with that established using both the full order and standard reduced order representations. It is shown that in cases where there are no significant rotor transients involved, the reduced order model obtained using the proposed method provides a more accurate indication of the stator terminal voltages during isolated operation than the standard reduced order model derived by neglecting stator transients in the synchronous reference frame. View full abstract»

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  • A Newton Optimal Power Flow Program for Ontario Hydro EMS

    Page(s): 576 - 582
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    A Newton optimal power flow program was developed for the Ontario Hydro Energy Management System. Each iteration minimizes a quadratic approximation of the Lagrangian. All the equations are solved simultaneously for all the unknowns. A new technique based on linear programming is used to identify the binding inequalities. All binding constraints are enforced using Lagrange multipliers. The algorithm combines the fast convergence of the Newton technique with the speed and reliability of Linear programming. Most cases converged in three iterations or less. View full abstract»

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  • Discussion

    Page(s): 582 - 584
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  • Reactive Power Constrained Loadability Limits of Series Capacitor Compensated EHV Transmission Lines

    Page(s): 585 - 591
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    This paper determines the loadability of a 500 kV series-compensated transmission line that are consistent with available var reserves taking into consideration the distributed nature of the line parameters and the effects of load-voltage characteristics and transformer taps at the load end. View full abstract»

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  • Adaptive Weather-Sensitive Short Term Load Forecast

    Page(s): 592 - 598
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    This paper introduces an adaptive, weather sensitive, short term load forecast algorithm that has been developed for two South Carolina Power Systems: CEPCI (Central Electric Power Cooperatives, Inc., Central for short) and Combined System. The model is based on a State Space formulation specially tailored for this application. A detailed correlation study is performed to identify the most relevant weather variables. Different models are used for Summer and Winter, since different weather variables are found to be relevant in both seasons. Adaptivity is attained through careful usage of Kalman filtering and Bayesian techniques. An appropriate methodology is developed to identify and correct anomalous load data and to model nonconforming loads. A new technique is introduced for "filling in" weather forecasts. The model has been sucessfully implemented using state-of-the-art data-base and man-machine techniques. Implementation results are reported. This model benefits from the experience gained using a variety of tools and represents important enhancements over existing methods. View full abstract»

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  • Discussion

    Page(s): 599 - 600
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  • Reliability Evaluation of Systems with after Fault Switching

    Page(s): 601 - 607
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    A new method is presented for reliability evaluation of power systems where components may be switched-out after faults. The method utilizes the concept of boundary conditions for the computation of the probability and frequency of system failure. The truncated state enumeration method applied traditionally to the analysis of such systems is now replaced by a network approach which does not, in principle, require truncation rules and can be applied to the components having arbitrary continuous probability distribution of time to failure or repair time. Examples are described in the text to demonstrate the application of the proposed method and to compare the results with the approximate calculations. View full abstract»

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  • Discussion

    Page(s): 607
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  • A Method for Solving the Fuel Constrained Unit Commitment Problem

    Page(s): 608 - 614
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    The unit commitment problem involves finding the hourly commitment schedule for the thermal units of an electrical system, and their associated generation, over a period of up to a week. For some utilities, contractual or other factors limit the amount of fuel available to certain of the units or plants. This paper describes a new method which solves the unit commitment problem in the presence of fuel constraints. The method uses a Lagrangian decomposition and successive approximation technique for solving the unit commitment problem where the generation, reserve and fuel constraints are adjoined onto the cost function using Lagrange multipliers. All important operating constraints have been incorporated including minimum up and down times, standby operation, ramping limits, time-dependent start-up cost, spinning and supplemental reserve. The method is being applied to a production-grade program suitable for Energy Management Systems applications. View full abstract»

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  • Discussion

    Page(s): 614
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  • Power System Stabilization via Parameter Optimization - Application to the Hellenic Interconnected System

    Page(s): 615 - 622
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    Dynamic stability problems are usually overcome through the application of Power System Stabilizers. This paper presents an alternative approach for power system stabilization based upon the tuning of the existing generator controllers, both governors and A.V.R.'s. The sensitivities of the eigenvalues to the controller parameters are evaluated and an optimization technique is developed to maximize the dynamic stability. Application of the parameter optimization method on a realistic model of the Hellenic Interconnected System has proved an efficient way to stabilize a number of unstable oscillatory modes by relatively small parameter variations. The results are tested with a nonlinear simulation program and the achieved stabilization, as shown by the rotor angle swings, is found to be significant. View full abstract»

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  • Discussion

    Page(s): 623
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  • A Parallel Computation Algorithm for Static State Estimation by Means of Matrix Inversion Lemma

    Page(s): 624 - 631
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    This paper presents an effective parallel computation algorithm for the static state estimation of a power system. The proposed algorithm makes use of the matrix inversion lemma and assumes the use of a MIMD type computer system. The optimal block-partitioning algorithm which tears a power system into several blocks is presented and its clear difference from that for the load flow is clarified. Simulation results on systems of up to 135 nodes have demonstrated the algorithm is very promising to the speed up of the state estimation. View full abstract»

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  • Discussion

    Page(s): 632
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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