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Power Systems, IEEE Transactions on

Issue 2 • Date May 1989

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Displaying Results 1 - 25 of 52
  • Suppression of numerical oscillations in the EMTP power systems

    Publication Year: 1989 , Page(s): 739 - 747
    Cited by:  Papers (45)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (604 KB)  

    The integration scheme in the electromagnetic transients program EMTP has been modified to solve the problem of sustained numerical oscillations that occur when the trapezoidal rule has to act as a differentiator. These oscillations appear, for instance, on the voltage across an inductance after current interruption. The technique presented prevents these oscillations by providing critical damping of the discontinuity within one Δt of the simulation. The critical damping adjustment (CDA) is achieved by means of two Δt/2 integration steps using the backward Euler rule. With the CDA scheme the trapezoidal rule can still be used throughout the entire simulation without the problem at discontinuities. The effectiveness of the scheme is illustrated with simulation results View full abstract»

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  • Joint development and consistent bulk transmission outage reporting and analysis procedures by two NERC regions

    Publication Year: 1989 , Page(s): 517 - 523
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    Two North American Electric Reliability Council (NERC) regions, the Mid-Continent Area Power Pool and the Mid-America Interconnected Network, have individually collected bulk transmission outage data for a number of years. Based on recent research work, the members of the two regions realized that related multiple outages significantly affect bulk transmission system reliability. However, no existing data collection methods provided sufficient data to report and analyze adequately relationships between multiple outages. The experiences of these NERC regions working together to derive a consistent bulk transmission performance analysis package are discussed. The resultant data collection philosophy and format and the expected analysis capability are reviewed. Potential benefits of standardizing data formats and definitions are presented View full abstract»

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  • The inclusion of dynamic factors in statistical power system cost models. II. Part loading and reserve costs

    Publication Year: 1989 , Page(s): 524 - 529
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    For pt.I see ibid., vol.4, no.2, p.419-25 (1989). Techniques are developed for analyzing the costs of maintaining adequate operating reserver on power systems, within probabilistic production costing models and other based on load distribution functions. The aim is to show that such models can be developed to approximate the full range of dynamic penalties associated with practical power system operation. Algorithms for costing predetermined part loading are presented, taking into account the need for bringing plant online out of strict merit order. The author describes how a prediction error function can be used to estimate the probability that the specified spinning reserve is insufficient and hence approximate for the cost of gas turbine or storage utilization for dynamic control. This allows estimation of optimal reserve levels. The author discusses the analysis of longer term reserve from banked thermal units. Some results of the model are compared to those reported from hourly simulation studies View full abstract»

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  • Variance of power generating system production costs

    Publication Year: 1989 , Page(s): 662 - 667
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    Using the framework for production costs of H. Baleriaux (1967), this study provides formulae for computing the variance of the unit energy produced and the variance of the system production costs. Numerical results show that the coefficient of variation of these quantities can be quite large, highlighting the need for considering variances in addition to the expected values in production-costing models. Numerical examples show that the ratio of the standard deviation of unit energy produced to its mean value can be quite high. A similar observation applies for the system production costs. This suggests that basing utility decisions on the mean values only could be misleading and that the currently used production-costing models should be enlarged to include information on variance as well View full abstract»

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  • Effect of load models on AC/DC system stability and modulation control design

    Publication Year: 1989 , Page(s): 411 - 418
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    An investigation is conducted of the effect of load models on the modulated AC/DC system. Static load is modeled as a nonlinear function of load bus voltage, and dynamic load is modeled by an equivalent induction motor. DC power and relative power modulations are considered for the modulation controllers. A method for eigenvalue sensitivity calculation is developed to predict the effect of load characteristics on the system stability. Eigenvalue sensitivity and simulation results show that static and dynamic load characteristics can have a considerable effect on the system stability. The impact of static and dynamic load modules on the modulation controller gains obtained via optimal control theory is examined and it is shown that load models can have a marked influence on the controller gains. It is also shown that there are specific situations where the choice of load model can make a difference in system stability prediction View full abstract»

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  • Hydrothermal optimal power flow based on a combined linear and nonlinear programming methodology

    Publication Year: 1989 , Page(s): 530 - 537
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB)  

    The author's consider a new formulation of optimal power flow (OPF) that makes it eminently suitable for accurate incremental modeling. G. Zoutendijk's method of feasible directions (1960) for solving the nonlinear programming problems is adapted for the solution of the OPF. Hydraulic modeling of systems with a considerable share of hydraulic generation is considered. The method is very efficient as it is designed to exploit the special structure of the problem View full abstract»

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  • The inclusion of dynamic factors in statistical power system cost models. I. Assessment of startup and banking costs

    Publication Year: 1989 , Page(s): 419 - 425
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (552 KB)  

    Methods are developed for approximating dynamic aspects of power system costs within the load duration and probabilistic framework. The approach uses a transition-frequency function, as applied in frequency and duration methods of system reliability assessment, together with a function expressing the RMS prediction error in load forecasting. The author shows how the transition-frequency function can be used to estimate plant startup and banking costs under various conditions. He demonstrates how the calculations can be performed in terms of cumulants of the functions involved, making possible a very efficient formulation View full abstract»

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  • An enhanced LQ adaptive VAr unit controller for power system damping

    Publication Year: 1989 , Page(s): 443 - 451
    Cited by:  Papers (20)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    An adaptive linear quadratic Gaussian control strategy is presented for static VAr compensators to enhance power system damping and stability. The control strategy utilizes only local information to dampen oscillatory modes present in the network. The controller calculates an appropriate value of static VAr compensator susceptance to present to the network at each sampling interval based on a reduced-order model of the power system. The reduced-order model is obtained online by a least-squares identifier. Simulation results for a nine-bus network are presented View full abstract»

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  • Coal to natural gas seasonal fuel switching: an option for acid rain control

    Publication Year: 1989 , Page(s): 457 - 462
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    An investigation is conducted of seasonal fuel-switching as a means to control SO2 emissions. There is evidence that strategic control of emissions results in environmental improvements at a lower overall cost. The Electric Generation Expansion Analysis System (EGEAS) was used as the primary analytical tool for the study. The economics of gas substitution versus flue gas desulfurization technology was studied under a variety of economic conditions, taking into account initial capital investment, variable operating and maintenance costs, retrofit costs, pipelining costs, and a number of other factors. Natural gas substitution was found to be an economical means of efficient energy production combining low cost and significant emission reduction under a variety of conditions View full abstract»

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  • Cost of electrical power system losses for use in economic evaluations

    Publication Year: 1989 , Page(s): 586 - 593
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (660 KB)  

    A methodology is presented for calculating the cost of losses that incorporates both established and novel concepts. Its enhancement can accommodate a loss decrease during a planned period, with additional generation not being required for many years. The effects of peak load diversity and the compounding of losses on `upstream' categories are combined into multiplying factors. The method also utilizes the incremental approach for percent demand losses. For each system category, the costs of variable and fixed losses can be calculated, including the costs associated with the burden imposed on all `upstream' categories. Examples are included View full abstract»

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  • Unit connected operator with diode valve rectifier scheme

    Publication Year: 1989 , Page(s): 538 - 543
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    The application of a diode bridge rectifier unit connected to a generator feeding a sending-end HVDC station shows a substantial reduction in the station cost. One of the major problems of this configuration is its slow recovery from a DC line fault. The authors propose and analyze a few types of control and protection schemes for the generator. The minimum time required to restore full power subsequent to a DC line fault is studied for each scheme. The results of a digital computer study are presented, as are some results obtained from a real-time physical component HVDC simulator View full abstract»

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  • A general-purpose version of the fast decoupled load flow

    Publication Year: 1989 , Page(s): 760 - 770
    Cited by:  Papers (48)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (948 KB)  

    A new version of the fast decoupled load flow, in which a more broad range of power systems can be solved, is presented. The key lies in the different way in which the resistances are ignored and in a different iteration scheme. In the standard algorithm the resistances are ignored while building the B' load flow matrix: it is shown that it is preferable that the resistances are ignored in the B" matrix instead of the B' matrix. For normal test systems there is hardly any difference in the number of iterations. However, the new algorithm iterates faster if one or more problematic R/X ratios are present. An iteration scheme with strict successive P and Q iterations prevents cycling convergence behavior which can be found in some low voltage systems. The advantages of the new version are demonstrated with runs on IEEE test systems, with both uniformly and nonuniformly scaled reactances. R -scaling up to 3 is always possible, and sometimes values up to 5 can be used. X-scaling of at least 0.1 is possible without losing convergence and with iteration counts which are significantly lower than with the standard scheme View full abstract»

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  • The Kansas Electric Utilities Research Program: a model of utility/university cooperation

    Publication Year: 1989 , Page(s): 812 - 816
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    The Kansas Electric Utilities Research Program (KEURP) is a joint venture by six electric utilities in the state of Kansas to undertake and encourage applied research and development projects which may enhance reliability and minimize the cost of electric service in Kansas. The authors give a brief history of KEURP and describe its structure and operation. Several of the research projects sponsored by KEURP are described. A discussion is presented of the perceived benefits and difficulties with KEURP from a number of viewpoints View full abstract»

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  • VAr planning for power system security

    Publication Year: 1989 , Page(s): 677 - 686
    Cited by:  Papers (21)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    A method is presented for identifying a dispersed reactive power (VAr) supply that can enhance power systems' pre- and post-contingency voltage security, subject to technical and economic constraints. The problem is formulated in two stages. The first stage involves a nonlinear optimization problem which minimizes the amount of reactive supply. The second stage uses a mixed-integer linear program which optimizes the number of candidates buses for VAr support. Results of application of the method to an example system are presented View full abstract»

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  • Utility planning perspectives: a review

    Publication Year: 1989 , Page(s): 452 - 456
    Cited by:  Papers (1)
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    Today's mixed market (simultaneously regulated and competitive) for electric services has resulted in a proliferation of planning paradigms and optimization criteria, all of which attempt to provide the best planning approach. The author describes these planning approaches, the market environments to which they best apply, and the degree to which they apply to the current electric utility marketplace. He concludes that the newer approaches more directly address the real issues of today's electric marketplace, but still need to develop a commensurate level of accuracy and acceptance in the methods and data upon which they rely. Nevertheless, the key to utility planning lies in solving the right problem (the appropriate business environment), not in applying ready solutions to any problem that comes along View full abstract»

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  • Utility experience with real time rates

    Publication Year: 1989 , Page(s): 463 - 471
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (876 KB)  

    The structure of electric utilities is undergoing far-reaching changes as new and expanded service options are added. The concepts of unbundling or of priority service are expanding the options open to customers. Spot pricing, or real-time pricing of electricity, provides the economic structure for many of these new service options. It is frequently stated that customers cannot adapt to real-time prices. The authors identify the elements of real-time rates and existing rate structures in the United States and other OECD countries which incorporate these dimensions View full abstract»

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  • Three-phase modeling for transient stability of large scale unbalanced distribution systems

    Publication Year: 1989 , Page(s): 487 - 493
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    The authors propose a generalized method to analyze the transient stability by using the three-phase bus admittance matrix algorithm for any network configuration. The method takes into account the unbalance created by large single-phase loads, untransposed feeders, conductor bundles, and cables. Consequently, the effects of unsymmetrical shunt and/or series faults, as well as the addition or removal of single-phase feeders, can be simulated anywhere in the network. Also presented is a novel, general systematic technique of studying transient stability of unbalanced distribution systems View full abstract»

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  • Large-scale optimal power flow: effects of initialization, decoupling and discretization

    Publication Year: 1989 , Page(s): 748 - 759
    Cited by:  Papers (37)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1220 KB)  

    Extensive numerical testing of a second-order OPF (optimal power flow) solution method was conducted using a 1500 bus network under various loading conditions. The results show that properly implemented second-order OPF solution methods are robust with respect to different starting points, the decoupled OPF solution is expected to be close to the full OPF solution, and the effects of discretization of load tap changing (LTC) transformer taps are very small and usually negligible. The test procedure required two optimizations. During the first optimization, the transformer taps were treated as continuous variables. Using the continuous solution, the LTC taps were moved to their closest allowable discrete values. During the second optimization the LTC transformer taps were held fixed at their discretized values. The second solution was compared to the first. A small difference between these two solutions indicates that the effects of the transformer tap discretization were minimal View full abstract»

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  • Trajectory approximations for direct energy methods that use sustained faults with detailed power system models

    Publication Year: 1989 , Page(s): 499 - 506
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    The authors address the effects of fast dynamics on direct energy methods that use a sustained fault trajectory to approximate critically cleared trajectories and the corresponding critical energies. Integral manifold concepts are used to explain why fast dynamics can destroy such an approximation. Methods to remedy this problem are given and illustrated with a ten-machine example View full abstract»

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  • Digital control of HVDC converters

    Publication Year: 1989 , Page(s): 704 - 711
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (524 KB)  

    A description is provided of a completely digital HVDC converter controller based on a 16 bit microcomputer. The design comprises software programmed functions such as a proportional-integral-derivative current control amplifier, voltage-dependent current-order limiters and an alpha-minimum symmetrization unit, among others. HVDC control principles are briefly reviewed, and a detailed description of both the hardware and software structure of the controller is presented. The digital controller was implemented in an HVDC simulator, and several dynamic performance tests demonstrated the efficiency of the approach View full abstract»

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  • Apparent impedance measuring systems (AIMS)

    Publication Year: 1989 , Page(s): 575 - 585
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1012 KB)  

    For the analysis of subsynchronous resonance, computer models of an electric system have generally been based on a modified 60 Hz model with short-circuit equivalents for power sources and with loads neglected. Due to the importance of validating the electric systems model, AIMS has been developed to measure the apparent impedance as a function of frequency seen at the terminals of the study generator. AIMS has been successfully applied to an extensive power system. A description is given of AIMS and the significant modeling improvement realized by it application View full abstract»

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  • An expert system prototype for event diagnosis and real-time operation planning in power system control

    Publication Year: 1989 , Page(s): 544 - 550
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (564 KB)  

    A prototype system called EKA, which is an attempt to apply sophisticated knowledge-engineering methods to power systems, is described. EKA is based on an object-oriented model and model-based reasoning, including multiple ways to represent knowledge: rules, facts, methods, daemons, procedures, logic programs, etc. The EKA system consists of three separate but structurally similar systems: an operation planning system, an event analysis system, and a training simulator. As a development environment, hybrid software and a Lisp computer have been used. The tasks and methods involved are described with and without an expert system. The application environment and prototype implementation are outlined View full abstract»

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  • Complete bounding method for AC contingency screening

    Publication Year: 1989 , Page(s): 724 - 729
    Cited by:  Papers (51)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    An efficient contingency screening method for detecting both branch MW flow violations and bus-voltage-limit violations is presented. The efficiency of the method stems from a bounding criterion which reduces the number of branch-flow computations and limits checking, and a bounding criterion which reduces the number of buses for which the Q-mismatch has to be calculated. The method requires no offline setup and can handle contingencies with network topology changes of any type. The method is based on the incremental angle criterion and the fast decoupled power flow. Consequently, it includes reactive power considerations View full abstract»

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  • An equivalent of multi-machine power systems and its identification for on-line application to decentralized stabilizers

    Publication Year: 1989 , Page(s): 687 - 693
    Cited by:  Papers (4)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (524 KB)  

    An analysis of modal oscillations in multimachine power systems is presented. On the basis of the analysis, a power system equivalent representing a coherence mode of oscillations appearing in such a multimachine system is proposed for designing a decentralized control system. The equivalent is represented by an equivalent voltage and an equivalent reactance, which are identified by using measurements on a generator in the multimachine system under a transient condition. The identification is implemented by a sequential estimator based on the Kalman filter algorithm. Performance of the estimator is verified by using actual data on some example power systems View full abstract»

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  • A real-time calculation method for optimal reactive power compensator

    Publication Year: 1989 , Page(s): 643 - 652
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (668 KB)  

    A real-time calculation method is presented to determine the optimal reactive power compensator for power systems. The reactive power compensators are expressed as both the continuous control scheme and the discrete control scheme. The optimization problem is written in terms of the minimization of power line loss by minimizing the line currents. Three-phase current balancing is also considered in this problem. By an integerization method, suboptimal solutions are approached for utilizing the discrete-tap compensators. Theoretical derivations and computation procedures are formulated by including digital techniques for real-time data acquisition. Applications to radial-type systems are described and discussed. Examples of real-time simulations and experiments are discussed to show the performance of the method and to support the application capability 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