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Power Systems, IEEE Transactions on

Issue 2 • Date May 1990

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Displaying Results 1 - 25 of 42
  • Developing concurrent processing applications to power system planning and operations

    Page(s): 659 - 664
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    The implementation of existing power system applications in a concurrent programming environment is discussed. The tools comprise a multiprocessor computing system with concurrent processing software facilities and a concurrent processing simulator for helping on problem partition and debugging. Shorter execution times taking into account the solution structure are obtained. Three case studies are used to illustrate the application of the above tools and the development methodology: multiarea reliability, system analysis model, and security-constrained dispatch with postcontingency corrective rescheduling. Results show a very high efficiency in the use of the concurrent processors View full abstract»

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  • An innovative approach to generations scheduling in large-scale hydro-thermal power systems with fuel constrained units

    Page(s): 665 - 673
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    A methodology for short-term unit commitment is proposed. The development of the solution method is based on the Lagrangian relaxation approach. Thermal, fuel-constrained, and hydro units are modeled in the formulation of the problem, and restrictions on fuel and water utilization as well as limits on the storage levels of reservoirs are included. This procedure is especially applicable to systems whose unit commitment solution is sensitive to changes in the Lagrangian multipliers. In this regard, the method incorporates the following special features. First, a set of upper bounds is added to limit the excess in the spinning reserves at different periods during the search for a feasible suboptimal solution. Second, a revised economic dispatch algorithm is introduced in the final stage of the method. This algorithm identifies unnecessarily committed units in the generation schedule of a large power network and provides the solution for the economic allocation of system demand among the committed units View full abstract»

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  • Application of the REI equivalent for operations planning analysis of interchange schedules

    Page(s): 547 - 555
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    A methodology for performing projected interchange studies using an REI equivalent for power systems is presented. Using this REI methodology, based on a general concept previously suggested by T.E. Dy Liacco et al. (1978) but never applied, multiple interchange transactions can be quickly and accurately simulated by the selective, manual adjustment of REI node injections. The REI equivalent was selected since external load and generation are represented on nodes as physically meaningful values. These values can be directly adjusted by the planner to represent potential transactions without intermediate calculations or reequivalencing. It is argued that no other equivalent provides such a straightforward, simple method for transaction simulation given extremely limited information. A description of the method is presented. Basic REI concepts are reviewed and expanded for performing interchange studies. The results of two examples, one using actual real-time values, are provided View full abstract»

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  • Load management at a medium-size utility

    Page(s): 513 - 519
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    Grand Rapids is a medium-size city in northern Minnesota, served by its own municipal utility. The rate structure of its wholesale energy supplier causes wholesale demand charges to be quite high and energy charges to be quite low. A load-management feasibility study showed that major reductions in demand charges could be achieved, and that dual-fuel residential heating could be introduced. Details of water heating and dual-fuel heating analyses, bid evaluation, and promotion techniques are given. The load-management system was installed early in 1988 and is effective in controlling wholesale energy costs for the municipal utility View full abstract»

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  • Fast decoupled state estimators

    Page(s): 556 - 564
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    A framework for fast decoupled state estimators is presented. Decoupling is not seen as neglecting coupling submatrices in the Jacobian, but as a two-step procedure to solve full-Newton equations, without major approximations. In addition to a sound derivation of the standard version of the fast decoupled state estimator, another version is proposed which presents better performance when applied to power systems with critical r/x ratios. Test results and illustrative examples are presented and discussed View full abstract»

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  • Operational experience on the China light and power company's system operation training simulator

    Page(s): 521 - 530
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    The operational experience obtained in the utilization, maintenance, and development of the system operation training simulator (SOTS) is described. Training scenarios, instructor and trainee comments and experiences, evaluation guidelines, database maintenance considerations, and some simulation problems encountered are presented and discussed. Some suggestions are made in regard to the additional requirements for future SOTS specifications. Special attention is devoted to the simulation of system shutdown and restart procedures View full abstract»

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  • An optimized procedure for determining incremental heat rate characteristics

    Page(s): 376 - 383
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    An optimized procedure for producing generator incremental heat rate curves from continually sampled unit performance data is described. A generalized reduced-gradient algorithm is applied to optimally locate break points in incremental heat rate curves. Advantages include the ability to automatically take into consideration slow time-varying effects such as unit aging and temperature variations in combustion air and cooling water. The procedure is tested using actual fuel rate data for four generators View full abstract»

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  • Frequency domain relaxation of power system dynamics

    Page(s): 652 - 658
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    A highly parallel approach for solving nonlinear differential equations in the frequency domain is presented. Solutions of the frequency-domain equations involving polynomial approximations to the nonlinearities involved is handled using a relaxation technique to exploit parallelism. Identities involving frequency-domain matrix polynomials of dimension N and order n are developed to allow evaluation in O(log2 N×log 2 n) time. Results of applying the method to models involving hard limiters and sine nonlinearities are presented. Savings of the number of parallel computations is achieved through the elimination of the hard precedence relationships involved in the classical time-march methods View full abstract»

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  • A new approach for the forward and backward substitutions of parallel solution of sparse linear equations-based on dataflow architecture

    Page(s): 621 - 627
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    A parallel computational method to solve the forward and backward substitutions (F/B) of sparse linear equations for power systems is presented. The architectural model is a multiprocessor hypercube, based on the MIT tagged token dataflow architecture (TTDA). Communication overhead is considered. The differences of the operating time-units among the subtraction, multiplication, and division are modeled. A processor scheduling algorithm is introduced. In the algorithm, a highly sparse operational sequence matrix C is developed. From the C matrix, the minimal completion time, the critical path, and the scheduling of the processors for the proposed parallel F/B can be determined. The implementation of the TTDA architecture in the proposed method is explained in detail. Six power systems are examined and three scenarios are simulated to test the performance of the proposed method. The results are presented and discussed View full abstract»

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  • Hybrid transient stability analysis [power systems]

    Page(s): 384 - 393
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    The hybrid method of power system transient stability analysis, which combines the desirable features of both the time-domain simulation technique and the direct method of transient stability analysis, is presented. The hybrid method first computes the actual system trajectory using time-domain simulation, then evaluates the transient energy function in order to derive a stability index for fast derivation of transient stability limits. Proper criteria are proposed to stop the time-domain simulation of the system trajectory to reduce CPU time, once the status of the system has been identified. The method was successfully applied to three test systems varying in size from four generators to 50 generators. The method is shown to be a potential tool for online calculation of transient stability limits View full abstract»

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  • Modeling and analysis of the induction machine: a computational/experimental approach

    Page(s): 482 - 485
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    A multicomponent approach for communicating an understanding of the behavior of an induction machine to undergraduates is presented. In this approach, students set up and perform laboratory tests to determine equivalent-circuit parameters for the machine, develop software to analyze the circuit model, and compare the simulated results with laboratory observations and theoretical expectations. It is shown how such an approach reinforces the student's understanding of both the physical machine and the purpose of equivalent-circuit modeling and simulation in a more general context as well View full abstract»

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  • Fuel scheduling and accounting

    Page(s): 682 - 688
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    The Houston Lighting and Power (HL&P) Company's new fuel scheduling and accounting (FSA) function is discussed. The fuel scheduling and accounting function allows HL&P to accurately and efficiently schedule, dispatch, and monitor fuel usage throughout the entire HL&P system. In addition to minimizing the total cost of generation using the classical economic dispatch approach, FSA will dispatch generation taking into account various fuel delivery and operational constraints. A network model, fuel flow calculations, dynamic energy balance, fuel accounting, and fuel dispatch are discussed View full abstract»

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  • On voltage collapse in electric power systems

    Page(s): 601 - 611
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    Voltage collapses which have a period of slowly decreasing voltage followed by an accelerating collapse in voltage are analyzed based on a center manifold voltage collapse model. The essence of this model is that the system dynamics after bifurcation are captured by the center manifold trajectory. It is a computable model that allows prediction of voltage collapse. Both physical explanations and computational considerations of this model are presented. The use of static and dynamic models is clarified to explain voltage collapse. Voltage collapse dynamics are demonstrated on a simple power system model View full abstract»

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  • Adaptive procedure for masking effect compensation in contingency selection algorithms

    Page(s): 539 - 546
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    An adaptive procedure developed for the compensation of the masking effect in automatic performance index (PI) contingency ranking algorithms is described. A vector-norm-based PI formulation is introduced. It allows a quantitative description of the masking effect. The advantage of the adaptive procedure is that the security analysis is carried out cyclicly. The verification of the ranking after each exact outage simulation allows updating factors to be estimated, taking into account a sequence of former system states. These factors are assumed to be valid at the time of the next security check in order to update the second-order PI ranking. Thus, the adaptive procedure combines the computational speed of the standard PI2-methods with the accuracy of the masking-free PI20-formation. Extensive tests for realistic European power systems considering actual load and topology changes indicate a substantial reduction of the masking effect and therefore a more reasonable contingency ranking View full abstract»

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  • Interruptible load control for Taiwan Power Company

    Page(s): 460 - 465
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    Three alternative incentive rate designs for an interruptible load program are described, one of which was activated by Taiwan Power Company (Taipower) in 1987 when some preliminary results were obtained. Here, the effect of the interruptible load on the system peak demand reduction and the change of daily load curve for large industrial customers is analyzed. The avoided cost is estimated and a more appropriate incentive rate structure is designed for the interruptible load program. The interruptible load program has reduced the system peak load in the Taipower system by 270 MW or 2.4% of the yearly peak demand View full abstract»

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  • Implementation of the CDA procedure in the EMTP

    Page(s): 394 - 402
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    The application of the critical damping adjustment (CDA) technique to some of the main equipment models in the DCG/EPRI version of EMTP is presented. The CDA procedure eliminates the numerical oscillations that can occur in transients simulations that use the trapezoidal rule of integration. The details of this implementation for linear elements, nonlinear reactors, frequency-dependent transmission lines, and synchronous machines are described. Simulation results involving these components are presented, showing the effectiveness of the procedure View full abstract»

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  • Sparse matrix inverse factors [power systems]

    Page(s): 466 - 473
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    The structural and computation properties of the sparse matrixes encountered in various power system network analysis problems are discussed. Specifically, the inverses of the factors of sparse matrixes produced by factorization or decomposition are discussed. These inverse factors are themselves sparse, at least under suitable ordering and partitioning, and lend themselves to parallel operations in the direct or repeat solution phase of sparse matrix problems. Partitioning reduces the buildup of nonzero elements in the inverse factors, and parallel computation reduces the number of serial steps in the multiplications View full abstract»

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  • Development of power system simulator for research and education

    Page(s): 492 - 498
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    An analog power-system simulator developed for research and education at Waseda University is discussed. It allows system dynamic analyses to be done easily and gives an overall understanding of the events comprising the analyses. Structurally, the simulator consists of a power system block and a digital control block. Programmable controllers are used for the digital control block, making it convenient to design control function blocks and to record events View full abstract»

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  • Usable hydro capacity and electric utility production simulation and reliability calculations

    Page(s): 531 - 538
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    The two most common ways of modeling the energy limits of hydro plants in production simulation programs are compared. The first method dispatches hydro plants against the load duration curve prior to convolving any thermal-unit-outage random variables with the load. This method is often referred to as peakshaving. The second method dispatches hydro plants against the equivalent load duration curve (ELDC) after convolution of some or all thermal-outage random variables. Test results indicate that the peakshaving approach is more appropriate in terms of the implied usability of the hydro capacity View full abstract»

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  • Linear reactive power optimization in a large power network using the decomposition approach

    Page(s): 428 - 438
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    A mathematical framework is presented for the solution of the economic dispatch problem. The application of the Dantzig-Wolfe decomposition method for the solution of this problem is emphasized. The system's optimization problem is decomposed into several subproblems corresponding to specific areas in the power system. The upper bound technique along with the decomposition method are applied to a 16-bus system and a modified IEEE 30-bus system, and numerical results are presented for larger systems. The results indicate that the presented formulation of the reactive power optimization and the application of the decomposition procedure will facilitate the solution of the problem. The algorithm can be applied to a large-scale power network, where its solution represents a significant reduction in the number of iterations and the required computation time View full abstract»

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  • An external network modeling approach for online security analysis

    Page(s): 565 - 573
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    An approach that combines the load flow and state estimation techniques is proposed to improve the numerical stability and provide an external network model for online security analysis. An initial load flow study that provides a preliminary solution for the external network is followed by a state estimation using pseudomeasurements and proper weighting factors. Methods for handling multiple observable islands in the external network modeling process are described, and simulation tests are carried out on a practical system with realistic complexity View full abstract»

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  • On the evaluation of voltage collapse criteria

    Page(s): 612 - 620
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    An approach is proposed to enable a power system operator or planner to evaluate the alternatives in selecting a certain voltage collapse criterion. Specifically, the selection of a criterion must guarantee that the risk of making a wrong decision is minimal for any operating point and disturbance. This is done by recasting the various voltage collapse criteria in terms of a decision framework. Some examples are given to illustrate the effectiveness of the proposed approach View full abstract»

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  • A rule-based approach to decentralized voltage control

    Page(s): 643 - 651
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    A rule-based approach for decentralized voltage control in power systems is presented. A network decomposition technique is used to alleviate a bus voltage limit violation using the most effective voltage control device available. This requires having only the network information local to the bus with a voltage limit violation. A rule-based problem analyzer calculates the network voltage sensitivity with respect to the available voltage control resources and selects the optimal set of control actions for alleviating the voltage limit violation. The approach minimizes the actions taken, making it suitable for real-time application. The results of applying the approach to the AEP 118-bus test system are presented View full abstract»

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  • Predicting air conditioner load curves from energy audit data: a comparison of predicted and actual air conditioning data from the Athens load control experiment

    Page(s): 359 - 366
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    An approach for estimating air conditioning load curves based on household duty cycles is presented. The duty cycles are calculated from heat transfer rates using household audit data, thermostat settings and outdoor temperatures. The fit between the load curves estimated from the duty cycle model and load curves calculated from measured data for households where customers set and forget their air conditioner is presented. The air conditioner and heat pump data were gathered during the load control experiments conducted in the summer of 1987 on the Athens Utilities Board distribution system in Athens, Tennessee. Data collected on days when there was no control were used to evaluate the concept of the duty cycle coefficient which was then used to calculate the duty cycle of heat pumps and air conditioners. The theoretical calculations based on the model are compared to actual measured data and are found to be in close agreement View full abstract»

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  • Demand-side management impact on the transmission and distribution system

    Page(s): 506 - 512
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    A project to assess the impact on the transmission and distribution (TD) system due to the implementation of demand-side management (DSM) programs is described. Traditional TD planning methods are reviewed and procedural changes necessary to fully integrate DSM strategy analysis with the system planning process are discussed. Test procedures and results are discussed for a study conducted at a host utility. Several DSM strategies are analyzed to assess the impacts on a TD system serving a large metropolitan area 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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Editor-in-Chief
Antonio J. Conejo
The Ohio State University