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Generation, Transmission and Distribution, IEE Proceedings C

Issue 5 • Date Sep 1992

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Displaying Results 1 - 11 of 11
  • Calculation of the transient performance of protective current transformers including core hysteresis

    Page(s): 455 - 460
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (236 KB)  

    Core saturation of protective current transformers, due to the DC component of fault current and the qualitative effect of core hysteresis resulting in residual flux are both well known phenomena that can produce distorted output currents. A digital simulation technique, previously described, which represents both hysteresis and eddy-current action in the core steel is used to compute current waveshapes and flux excursions for a wide range of fault current parameters. The production of residual core flux and its influence on secondary current output is also examined View full abstract»

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  • Load flow analysis by G-S reduction and restoration method

    Page(s): 383 - 386
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    A simple, fast and reliable method is proposed in this paper for load flow analysis. The method depends on the technique of reduction and restoration applied to the conventional Gauss-Seidel (G-S) method. Three IEEE well-conditioned systems, namely 14, 30, and 57 bus systems, and some ill-conditioned systems were studied, and the results obtained by the algorithm, using an ICL 2966 mainframe computer, are presented. The method can handle bus violations with ease and has the desirable features required for online applications View full abstract»

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  • New bad-data detection and identification technique based on rotation of measurement order for sequential state estimation [for power systems]

    Page(s): 387 - 401
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (996 KB)  

    The authors describe the development of a new bad-data detection and identification technique for sequential power system state estimations using Givens orthogonal transformation. The proposed bad-data detection and identification method does not rely on the analysis of measurement residuals. The new bad-data processing technique is tested on an industrial steam turbine system for which a robust and efficient state estimator has been developed. Numerical results for bad-data detection and identification tests are reported View full abstract»

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  • Neural net based determination of generator-shedding requirements in electric power systems

    Page(s): 427 - 436
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    The authors present an application of artificial neural networks (ANN) in support of a decision making process by power system operators directed towards the fast stabilisation of multimachine power systems. The proposed approach considers generator shedding as the most effective discrete supplementary control for improving the dynamic performance of faulted power systems and preventing instabilities. The sensitivity of the transient energy function (TEF) with respect to changes in the amount of dropped generation is used during the training phase of ANNs to assess the critical amount of generator shedding required to prevent the loss of synchronism. The learning capabilities of neural nets are used to establish complex mappings between fault information and the amount of generation to be shed, suggesting it as the control signal to the power system operator View full abstract»

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  • An efficient methodology for coherency-based dynamic equivalents [power system analysis]

    Page(s): 371 - 382
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (808 KB)  

    The authors present a new methodology for dynamic equivalents. Two alternative linear simulation methods are proposed for the identification of coherent generators. The measure of coherency for both methods is the angular speed average deviation of generators. The coherent generators are grouped using a clustering algorithm that assures the uniqueness of the composed coherent groups. The REI approach is applied to transfer the generators of each group to a common busbar. The Levenberg-Marquardt method is used for the coherent generator dynamic aggregation. The dynamic equivalents are evaluated in the New England system and in a configuration of the Brazilian South-Southeastern system with 421 busbars, 717 transmission lines/transformers and 40 generators View full abstract»

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  • Steady-state temperature rises of ONAN/ONAF/OFAF transformers

    Page(s): 448 - 454
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    In the piping between the tank of a 40 MVA transformer, originally designed for ONAN/ONAF cooling combination, and its bank of radiators, a propeller oil pump was installed. Characteristic temperature rises were measured before and after installation of the pump. The results were applied to the development of a new algorithm for calculation of windings and oil steady-state temperature rises of ONAN/ONAF/OFAF transformers. The mathematical model is briefly described by the authors, and the basic thermal characteristics of transformers with this combination of cooling types are described. Installation of the oil pump can make transformer cooling more efficient provided that certain conditions are satisfied View full abstract»

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  • Development of a practical expert system for alarm processing [power systems]

    Page(s): 437 - 447
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (636 KB)  

    The authors describe the procedure and approach taken in constructing an expert system for practical application in power system alarm processing. Practical considerations include the need for rapid speed of analysis, a good user interface, easy maintainability of the knowledge base, and ability to cope with missing or uncertain input alarm data. The strategies adopted in tackling these problems are described in detail View full abstract»

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  • Novel adaptive control scheme for improving power system stability

    Page(s): 423 - 426
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (208 KB)  

    The author presents a new adaptive control approach for power systems. The proposed adaptive control structure is based on hyperstability theory. The control is constructed so that the closed-loop system is hyperstable, guaranteeing the dynamic stability improvement of power systems. The changeable gains generated by a nonlinear function act as the adaptive mechanism. Compared with MRAC or STAC, the proposed control structure avoids the difficulty of choosing an appropriate reference model and the burden of implementing an online parameter estimator. Simulation results of a numerical example are presented, which show that the controller works well under system parameter changes, variation in operating conditions and with different disturbances View full abstract»

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  • Efficient identification of binding inequality constraints in optimal power flow Newton approach

    Page(s): 365 - 370
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (388 KB)  

    The authors present a new technique for identifying the binding inequality constraints for the optimal power flow Newton approach. The technique is free of the need for user intervention, and reduces significantly the computational effort required by other methods. The algorithm is based on an efficient criteria for selecting and enforcing, at each iteration, a minimum number of active inequality constraints, and on obtaining a solution quickly and with less oscillations. The effectiveness of the proposed method is demonstrated by means of two sample systems View full abstract»

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  • Analysis of partial discharge pulse distribution along transformer windings using digital filtering techniques

    Page(s): 402 - 410
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    The capacitive network often used for the calculation of initial voltage distribution along a transformer winding can be in error for steep impulses. As such pulses are produced by partial discharges (PDs) the application of the concept could contribute to inaccuracies in methods developed for the location of PDs in windings. Results are presented for tests on 66 kV and 132 kV interleaved windings and a conventional 66 kV winding. It is concluded that the studies described will assist in the long-term development of more accurate electrical PD location systems View full abstract»

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  • Analysis of magnetic fields in the slotted structure of a superconducting AC generator

    Page(s): 411 - 422
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    An analytical model has been developed to help determine the distribution of the magnetic flux density inside the superconducting AC generator. The model takes into account the number, and the geometric structure, of the winding slots and allows the rotor of the superconducting machine to be designed with optimum magnetic field distribution. The results obtained by the model are verified by comparison with results obtained by former models. The new model is also used to study the influence of the field winding geometry on the magnetic flux density distribution. The authors also review two-dimensional modelling methods for calculating the magnetic field inside a superconducting AC generator, and highlight some of the problems and opportunities for the application of these methods to magnetic field analysis of superconducting field winding View full abstract»

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