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Power Systems, IEEE Transactions on

Issue 2 • Date May 1998

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Displaying Results 1 - 25 of 61
  • Topology error identification using normalized Lagrange multipliers

    Publication Year: 1998 , Page(s): 347 - 353
    Cited by:  Papers (54)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    This paper introduces a method for topology error identification based on the use of normalized Lagrange multipliers. The proposed methodology models circuit breakers as network switching branches whose statuses are treated as operational constraints in the state estimation problem. The corresponding Lagrange multipliers are then normalized and used as a tool for topology error identification, in the same fashion as measurement normalized residuals are conventionally employed for analog bad data processing. Results of tests performed with the proposed algorithm for different types of topology errors are reported View full abstract»

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  • Neural networks approach for solving economic dispatch problem with transmission capacity constraints

    Publication Year: 1998 , Page(s): 307 - 313
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB)  

    This study presents a new approach using Hopfield neural networks for solving the economic dispatch (ED) problem with transmission capacity constraints. The proposed method is based on an improved Hopfield neural network which was presented by Gee et al. (1994). The authors discussed a new mapping technique for quadratic 0-1 programming problems with linear equality and inequality constraints. The special methodology improved the performance of Hopfield neural networks for solving combinatorial optimization problems. The authors have now modified Gee and Prager's (GP) method in order to solve ED with transmission capacity constraints. Constraints are handled using a combination of the GP model and the model of Abe et al. (1992). The proposed method (PHN) has achieved efficient and accurate solutions for two-area power systems with 3, 4, 40 and 120 units. The PHN results are very close to those obtained using the quadratic programming method View full abstract»

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  • Direct load control-A profit-based load management using linear programming

    Publication Year: 1998 , Page(s): 688 - 694
    Cited by:  Papers (63)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (612 KB)  

    Conventional cost-based load management ignores the rate structure offered to customers. The resulting cost savings may cause revenue loss. In a deregulated power industry where utilities absorb the ultimate consequence of their decision making, reexamination of load management must be conducted. In this paper, profit-based load management is introduced to examine generic direct load control scheduling. Based upon the cost/market price function, the approach aims to increase the profit of utilities. Instead of determining the amount of energy to be deferred or to be paid back, the algorithm controls the number of groups power customer/load type to maximize the profit. In addition to the advantage of better physical feel on how the control devices should operate, the linear programming algorithm provides a relatively inexpensive and powerful approach to the scheduling problem View full abstract»

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  • Fast textured algorithms for optimal power delivery problems in deregulated environments

    Publication Year: 1998 , Page(s): 493 - 500
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (852 KB)  

    For the future deregulated (open access) environments, we need to find the best way to deliver the electric power to buyers after the generation settings are determined by sellers' own economic strategies. In this paper, the authors formulate such a problem as an optimal power delivery (OPD) problem in terms of transmitted line flows and parameters of FACTS (flexible AC transmission systems) devices, such as phase shifters and series compensators. The total transmission losses are taken into account and represented by the transmitted line flows across those lines. Unwanted loop flow can be reduced or eliminated by FACTS devices and can be achieved by minimizing the total transmission loss. The OPD problem is then solved by two fast textured algorithms for modified IEEE 14-bus and 57-bus systems View full abstract»

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  • A mathematical framework for the analysis and management of power transactions under open access

    Publication Year: 1998 , Page(s): 681 - 687
    Cited by:  Papers (39)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (788 KB)  

    Several models are being considered by the power industry for competition under open access transmission. Each alternative offers a radically different solution which must be evaluated, not only in terms of economic benefits, but also in terms of impact on power system security. This paper therefore presents a general mathematical framework for the analysis and management of power transactions under open access subject to system security constraints. The framework introduces the notions of a virtual network of transactions and the transactions matrix, both describing virtual power flows among financial entities. Finally, this paper shows how the transactions selected by the market forces are influenced by the security requirements of the physical network View full abstract»

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  • First and second order methods for voltage collapse assessment and security enhancement

    Publication Year: 1998 , Page(s): 543 - 551
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (964 KB)  

    The paper deals with the applications of steady-state approaches to the assessment of the maximum loadability of the electric system and to the determination of control actions suitable to avoid the voltage collapse. Following current research trends, first order indicators, derived by the linearization of the load flow (LF) equations and by the eigen/singular value analysis are adopted to determine the distance from the voltage collapse. In addition, a new second order performance index, obtained by the maximum singular value of the inverse LF Jacobian and by its sensitivities with respect to the system parameters, is proposed. The same second order information is adopted in a procedure for the security enhancement. It allows preventive rescheduling in alarm states and load shedding in emergency. The performances of the investigated indices are shown with reference to a small test network and to the large EHV Italian system View full abstract»

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  • A security-constrained bid-clearing system for the New Zealand wholesale electricity market

    Publication Year: 1998 , Page(s): 340 - 346
    Cited by:  Papers (71)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (788 KB)  

    This paper reports upon the mathematical models and implementation of the Scheduling, Pricing and Dispatch (SPD) application for the New Zealand Electricity Market (NZEM). SPD analyzes bids for energy offers, reserve offers and energy demands, and recognizes explicitly the effects on bid clearing due to transmission congestion, network losses, reserve requirements, and ramp rate limits. Advanced LP solution methods are utilized to solve the large-scale constrained optimization problem. Results on a 67-bus test system and the NZEM are included View full abstract»

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  • A genetic algorithm modelling framework and solution technique for short term optimal hydrothermal scheduling

    Publication Year: 1998 , Page(s): 501 - 518
    Cited by:  Papers (39)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1432 KB)  

    A genetic algorithm is applied to the problem of determining the optimal hourly schedule of power generation in a hydrothermal power system. A multi-reservoir cascaded hydroelectric system with a nonlinear relationship between water discharge rate, net head and power generation is considered. The water transport delay between connected reservoirs is also taken into account. The main control parameters that affect the genetic algorithm performance are discussed and a summary of the theoretical basis of the genetic algorithm method is presented. It is shown that a multiple step genetic algorithm search sequence can provide the optimal hourly loading of the system generators View full abstract»

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  • An algorithm for solving the dual problem of hydrothermal scheduling

    Publication Year: 1998 , Page(s): 593 - 600
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (712 KB)  

    Lagrangian relaxation has been widely used for the hydrothermal scheduling of power systems. The idea is to use Lagrangian multipliers to relax system-wide demand and reserve requirements, and decompose the problem into unit-wise subproblems that are much easier to solve. The multipliers are then updated at the high level, most commonly by using a subgradient method (SGM). Since the high level dual function is nondifferentiable with many “ridges”, the SGM may zigzag across ridges resulting in slow convergence. This paper presents an algorithm that utilizes a recently developed “reduced complexity bundle method” (RCBM) to update the multipliers at the high level. The RCBM is a kind of “bundle method” that enjoy faster convergence compared to SGM, but has much reduced complexity as compared to a conventional bundle method. Testing results show that RCBM can find better directions, avoid zigzagging behavior and obtain better dual and feasible solutions as compared to the SGM View full abstract»

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  • Transmission congestion management in competitive electricity markets

    Publication Year: 1998 , Page(s): 672 - 680
    Cited by:  Papers (139)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (900 KB)  

    This paper studies the management of costs associated with transmission constraints (i.e., transmission congestion costs) in a competitive electricity market. The paper examines two approaches for dealing with these costs. The first approach is based on a nodal pricing framework and forms the basis of the so-called pool model. The paper also provides an analysis of financial instruments proposed to complement nodal pricing and includes illustrative test results on a large scale system. The second approach is based on cost allocation procedures proposed for the so-called bilateral model. The paper explains the basis for this model including a game-theoretic evaluation of some of its aspects. Both the pool and bilateral models have been at the center of the electric utility restructuring debate in California View full abstract»

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  • On robust control analysis and design for load frequency regulation

    Publication Year: 1998 , Page(s): 449 - 455
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (696 KB)  

    This paper addresses the analysis and design issues in load frequency control (LFC) for a power system entity that participates in interconnection. The basic physical control mechanisms are the same whether the entity is a vertically integrated utility, an independent system operator or a virtual control area in a fully de-regulated market. Goals of this paper are twofold: to examine a rationale for known heuristic design guidelines; and to suggest an orderly methodology for control synthesis. Motivated by the large uncertainty in dynamic models of power system components and their interconnections, this paper proposes a physically motivated passivity objective as a means to achieve effective closed-loop control. Quantitative feedback theory provides convenient graphical tools for suggested design and analysis methods. A simulation model of a two-system interconnection is used as an illustration View full abstract»

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  • Distribution system reliability: default data and model validation

    Publication Year: 1998 , Page(s): 704 - 709
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    Distribution system reliability assessment is able to predict the interruption profile of a distribution system based on system topology and component reliability data. Unfortunately, many utilities do not have enough historical component reliability data to perform such an assessment, and are not confident that other sources of data are representative of their particular system. As a result, these utilities do not incorporate distribution system reliability assessment into their design process and forego its significant advantages. This paper presents a way of gaining confidence in a reliability model by developing a validation method. This method automatically determines appropriate default component reliability data so that predicted reliability indices match historical values. The result is a validated base case from which incremental design improvements can be explored View full abstract»

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  • An investigation on the use of power system stabilizers for damping inter-area oscillations in longitudinal power systems

    Publication Year: 1998 , Page(s): 552 - 559
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (692 KB)  

    This paper presents the progress of an investigation on the use of power system stabilizers (PSSs) to enhance the damping of low-frequency inter-area modes in longitudinal power systems. A dynamic model of the Mexican Interconnected System (MIS) is adopted to evaluate the potential for small signal stability improvement by means of PSSs. Power oscillation flow studies, transfer function residues and controllability and observability characteristics are used to understand the nature of oscillation patterns, mode identification and PSSs siting. It is shown that PSSs can significantly enhance the damping of modal oscillations, especially under high stress conditions View full abstract»

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  • Probabilistic assessment of interconnection assistance between power systems

    Publication Year: 1998 , Page(s): 535 - 542
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (816 KB)  

    The interconnection assistance (IA) between power systems is a function of many variables such as the system installed capacity, generation dispatch, forced and scheduled outages of generating units, load duration characteristics, accuracy of load forecast, load diversity, capability of the interconnections and the operating limits imposed on the transmission network due to thermal, voltage and stability considerations. This paper describes a probabilistic approach for evaluating the IA that a system can provide at any selected location without affecting its level of reliability. The method considers most of the key factors affecting the level of power transfer and differentiates between two types of transfer, namely the economy transfer and the emergency transfer. The method calculates the expected value and the probability distribution of IA of each type. The proposed method is illustrated using the IEEE Reliability Test System View full abstract»

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  • On-line dynamic preventive control: an algorithm for transient security dispatch

    Publication Year: 1998 , Page(s): 601 - 610
    Cited by:  Papers (64)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1080 KB)  

    This paper describes the philosophy and the implementation of a preventive control algorithm for application in power system dynamic security assessment. The methodology consists of an optimization procedure where: the objective function takes into account economic costs; inequality constraints confine the trajectory of the system in a practical domain of the state space; and equality constraints derive from the discretization of the differential-algebraic equations of the power system sparse representation. The algorithm has been implemented to reschedule the power system generation in order to guarantee transient stability. The feasibility of the approach is shown through computer simulation tests on a realistic sized test network View full abstract»

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  • Daily generation scheduling: quest for new models

    Publication Year: 1998 , Page(s): 624 - 629
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (668 KB)  

    This paper presents the need for adding transmission system representation in a conventional power system generation scheduling model. Given the complexity of developing solution algorithms for such models, the present study critically examines whether adding complexities to the simplified models viz., unit commitment and network flow models, is worthwhile, or the simplified models provide good approximation of the optimal generation schedule. Prototype model development and simple case studies for a capacity constrained test system shows there are major deviations in the generation schedules, load-shed requirement and spot prices obtained from the simple models and the complex model. The results indicate that research efforts towards algorithmic development for more accurate scheduling models are needed View full abstract»

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  • Modeling air conditioner load for power system studies

    Publication Year: 1998 , Page(s): 414 - 421
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    The air conditioner load is the most variable component of the system load of the Kansai Electric Power Company. As the air conditioner load changes with temperature and time, the voltage and frequency characteristics of the system load change as well as its magnitude. Single-phase air conditioner characteristics have been determined through measurement, and simple models suitable for power system studies have been developed View full abstract»

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  • Probabilistic evaluation of the effect of maintenance on reliability. An application [to power systems]

    Publication Year: 1998 , Page(s): 576 - 583
    Cited by:  Papers (64)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (708 KB)  

    The purpose of maintenance is to extend equipment lifetime, or at least the mean time to the next failure. While too little maintenance may have very costly consequences, maintenance, too, incurs expenditures and it may not be economical to perform it too frequently. Therefore, the two costs must be balanced. In the past, attempts to approximate this balance have often been based on trial and error. In this paper, a probabilistic model is proposed for the purpose, and a computer program based on this model is described. The model provides a quantitative connection between reliability and maintenance, a link missing in the heuristic approaches. The component ageing process is modelled, and the mean and distribution of the remaining life to failure are predicted for any stage of ageing. The method is applied to a practical example View full abstract»

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  • On influence of load modelling for undervoltage load shedding studies

    Publication Year: 1998 , Page(s): 395 - 400
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    This paper explores the influence of load models on decisions of undervoltage load shedding in power systems. A controlled load rejection can be used as an emergency countermeasure to avoid widespread blackout when system voltages are unstable. In this paper, dynamic simulations of a small power system using both static and dynamic load models are presented. When using a static load model, the system includes an explicit model of a transformer with load tap changer. The aim is to demonstrate how different load models influence the analysis and calculation of the amount of load needed to be shed to stabilise the system voltage View full abstract»

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  • Identification of low-order linear power system models from EMTP simulations using the Steiglitz-McBride algorithm

    Publication Year: 1998 , Page(s): 422 - 427
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (632 KB)  

    This paper presents the implementation of an efficient method for computing low order linear system models of power systems from time domain simulations. The method is the identification algorithm initially introduced by K. Steiglitz and L.E. McBride for calculating the transfer function of a linear system from samples of its input and output. The paper describes the original algorithm, added extensions, and issues addressed for its practical implementation. The applicability of the method is demonstrated by computing a low-order equivalent linear system of a detailed three-phase power system, modeled on an Electromagnetic Transients Program (EMTP). The paper discusses practical implementation issues View full abstract»

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  • Efficient object oriented power systems software for the analysis of large-scale networks containing FACTS-controlled branches

    Publication Year: 1998 , Page(s): 464 - 472
    Cited by:  Papers (38)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (920 KB)  

    This paper presents the methodology used in the development of a new generation of software suitable for the analysis and control of large-scale power networks containing FACTS-controlled branches. A Newton-Raphson load flow is used in this paper to emphasise the benefits and drawbacks introduced by the object-oriented technology when applied to `number-crunching' power engineering solutions. The Newton-Raphson algorithm exhibits quadratic convergence for cases with FACTS-controlled branches. Full details of the prowess of this algorithm are given in a companion paper. C++ has been used to develop compact and easy-to-maintain power systems conventional sparsity software. To aid portability the software has been developed under the UNIXTM environment View full abstract»

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  • Evolutionary-programming-based algorithm for environmentally-constrained economic dispatch

    Publication Year: 1998 , Page(s): 301 - 306
    Cited by:  Papers (71)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    This paper develops an efficient and reliable evolutionary-programming-based algorithm for solving the environmentally constrained economic dispatch (ECED) problem. The algorithm can deal with load demand specifications in multiple intervals of the generation scheduling horizon. In the paper, the principal components of the evolutionary-programming-based ECED algorithm are presented. Solution acceleration techniques in the algorithm which enhance the speed and robustness of the algorithm are developed. The power and usefulness of the algorithm is demonstrated through its application to a test system View full abstract»

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  • A cooperative expert system for transmission expansion planning of electrical power systems

    Publication Year: 1998 , Page(s): 636 - 642
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (768 KB)  

    This paper describes a cooperative expert system for managing the transmission expansion planning process, taking into account the selection of feasible transmission routes, as well as the definition of the expansion plan itself. The use of an expert system is proposed to create a planning environment, which can not only emulate the human expert reasoning, but also represent appropriately all heuristic knowledge related to this problem. The main point of this system is the fact that it is able to define feasible alternatives for the expansion of the electrical transmission system. Afterwards, the expert system executes a network flows program, which determines the minimum cost expansion plan. The developed prototype is tested with a realistic system of 500 busbars View full abstract»

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  • A modular system for decision-making support in generation expansion planning (SUPER)

    Publication Year: 1998 , Page(s): 667 - 671
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    A computer system for generation expansion studies (SUPER) is introduced that in addition to traditional least cost plans produces minimum risk strategies in the presence of several uncertainties, for example, in demand growth. Signals are provided that allow a utility a proper evaluation of cogeneration options and proposals by IPPs (Independent Power Producers). DSM alternatives compete with more traditional supply options in conforming adequate expansion alternatives. Hydro uncertainties are properly modeled. Interconnection lines can be expansion options. Financial and environmental impacts are evaluated and reported. SUPER has a modular structure, a relational database and a graphic user interface (GUI). Extensive experience exists using SUPER in generation expansion studies for all types of power systems View full abstract»

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  • Augmentation of transient stability using a superconducting coil and adaptive nonlinear control

    Publication Year: 1998 , Page(s): 361 - 366
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    The very nonlinear nature of the generator and system behaviour following a severe disturbance precludes the use of classical linear control techniques. In this paper, a nonlinear adaptive excitation and a thyristor-controlled superconducting magnetic energy storage (SMES) unit is proposed to enhance the transient stability of a power system with unknown or varying parameters like equivalent reactances of the transmission lines. The SMES unit is located near the generator bus terminal in a power system. A nonlinear feedback control law is found which linearizes and decouples the power system. An adaptive control law is used to design the controller for the generator excitation and SMES system. Simulation results demonstrate that the proposed controller can ensure transient stability of a single-machine-infinite-bus system under a large sudden fault which may occur near the generator bus terminal 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