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Generation, Transmission and Distribution, IEE Proceedings C

Issue 4 • Date Jul 1988

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Displaying Results 1 - 11 of 11
  • Modelling, analysis and control of a wind-turbine driven self-excited induction generator

    Page(s): 268 - 275
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (656 KB)  

    A wind-turbine driven self-excited induction generator is considered as a variable speed, constant voltage, constant frequency supply for isolated resistive loads. First, a general nonlinear model of the system is developed in a synchronously rotating reference frame. Next, using a modified approach of the singular perturbation theory, an order reduction is carried out by neglecting the fast transients existing in the system and a simplified model is obtained. Then, based on the reduced order model, the steady-state operating characteristics and the stability performance of the system are derived. Finally, the simplified model is used to develop a control strategy which aims to maintain the generator terminal voltage and frequency constant in case of variations in the load and/or windspeed View full abstract»

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  • Co-ordinated design of multimachine power system stabilisers based on damping torque concepts

    Page(s): 276 - 284
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (660 KB)  

    The author employs damping torque concepts associated with frequency response analysis, to consider the co-ordinated design of power system stabilisers (PSSs) in multimachine power systems. The aim of the proposed approach is to provide, through the action of the stabiliser, an electrical damping torque proportional to speed perturbations, i.e. ΔPei(s)=Di Δωi(s). The stabiliser network is designed to compensate for the phase lag and gain in the machine/system transfer function ΔPei(s)/Δvri (s). The stabiliser gain Di is co-ordinated, in the first instance, so that the damping effect is distributed among those machines fitted with stabilisers in proportion to their ratings. The damping performance of a sample power system with PSSs installed is shown to be comparable to that for a multimachine system without PSSs in which a pure damping torque is introduced artificially in the transfer function block representing shaft dynamics View full abstract»

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  • Specified current in emergency load switches

    Page(s): 330 - 333
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (312 KB)  

    The authors deal with the problems which arise in the contacts of power switches at LV distribution systems, especially in cases where emergency loads cannot allow programmed power interrupts through the central distribution panels to perform maintenance. Dust and other local impurities accumulated on the metal surfaces deteriorate the contacts with the time and the switch's ability to supply its specified current. An explanation of the contact deterioration mechanism is attempted, and a solution of the maintenance problem is suggested: a design of a bypass supply system, including isolators and automatic switches. The proposed system was tested in actual industrial conditions, namely in hospitals, where maintenance is an awkward procedure, and proved to perform adequately View full abstract»

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  • Generation expansion planning: an expert system approach

    Page(s): 261 - 267
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (672 KB)  

    An expert system approach to solve the problem of generation expansion planning is presented. The approach is based on the decision tree technique which is used instead of the techniques of mathematical programming. The expert system approach is capable of emulating human expertise in the field of generation planning. New concepts based on the natural properties of the problem are developed to minimise the computation burden by making in the minimum size. The solution technique satisfies the objectives of strategic planning and is capable of modelling the various uncertainties inherent in the problem of generation expansion planning View full abstract»

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  • MCHSE: a versatile framework for the design of two-level power system state estimators

    Page(s): 291 - 298
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (660 KB)  

    A new method for the design of static WLS state-estimators on large-scale power systems is described. The approach is based on a simple partitioning, termed `α-decomposition' of the measurement model, and the estimator is implemented on two levels within a multiple-processor environment. The lower level computation, executed within subsystem processors operating in parallel, is noniterative and of reduced order; the upper level algorithm, also noniterative and of low order, is executed in a single processor. The solution is obtained from alternate entries to the lower and upper levels, continued to a convergence. Necessary and sufficient conditions for convergence are derived, and lead to new definitions for observability on decomposed power systems. Tests for `α-observability' may be distributed amongst the processors on two levels. The method is optimal and structurally efficient, and convergence is fast (theoretically quadratic). The structure of the estimator is simple and well-defined, and possibilities for suboptimal variants are suggested View full abstract»

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  • Alternative solution for the Chowdhuri-Gross model of lightning-induced voltages on power lines

    Page(s): 324 - 329
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    According to a previous study, the induced voltage due to any current shape in the lightning channel can be obtained through the application of the Duhamel integral to the induced voltage due to a step current in the lightning channel. The authors present an alternative expression for the Chowdhuri-Gross model, using a method different from that previously employed. This expression gives the induced voltage directly in terms of the inducing voltage due to a step current. The simplicity of the expression is particularly evident when calculating the induced voltage due to a ramp current. The expression for this induced voltage is used to obtain induced voltage pulse shapes due to a current with a linearly-rising front. Good agreement is obtained with a previously published plot View full abstract»

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  • Two-level state estimation for large power system. II. Computational experience

    Page(s): 309 - 318
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (736 KB)  

    For pt.I see ibid., vol.135, pt.C, no.4, p.299 (1988). In this part the authors establish an algorithm which has a consistent convergence property and is also able to handle bad data in the subsystem, as well as in the interconnection area. They deal mainly with the computational experience of the integrated state estimation (ISE) and six algorithms of the TLE which were formulated in part 1 of the series View full abstract»

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  • Co-operative research into the engineering and design of a new digital directional comparison scheme

    Page(s): 334 - 368
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (3124 KB)  

    The authors review the salient features of a major co-operative research, development and site trial validation programme which was initiated in 1980 with the primary objective of accomplishing a major advance in power transmission system protection. Details of the project are given, together with the research/development methodology found necessary to transform a new approach to directional comparison protection into a next-generation product to meet stringent operational design objectives. The basic principles of the new scheme are outlined, together with details of the early computer-aided design studies which formed the basis of first prototype digital measuring equipments. Details are also given of the site-trial tests which were performed on the British 400 kV supergrid system, together with the results of investigations into the performance in long-distance power transmission applications. They conclude with brief details of preproduction prototype equipment and its performance View full abstract»

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  • Parallel processor algorithm for power system simulation

    Page(s): 285 - 290
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    The authors consider real-time simulation over the operational timescales in an electrical power system and present a mathematical technique for the decomposition of a set of nonlinear algebraic and differential equations, which result from the corresponding dynamic model. It is shown that the resulting algorithm is suitable for implementation on parallel processors with a 32 bit word capability. The results illustrate that the proposed decomposition technique results in a significant saving in simulation elapsed time, and can consequently be applied to the real-time simulation of large power systems, using relatively inexpensive microprocessor-based hardware View full abstract»

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  • Two-level state estimation for large power system. I. Algorithms

    Page(s): 299 - 308
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (844 KB)  

    The authors test the performance of several techniques for two-level state estimation. The main purpose is to develop an efficient and fast algorithm for a large power system. In part one the authors give the analytical formulation of six algorithms of the two-level state estimator View full abstract»

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  • New method for transmission planning using mixed-integer programming

    Page(s): 319 - 323
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    The authors present a new approach for planning high voltage transmission networks. The simulation model developed takes into account the capital investment cost in its discrete form as well as the cost of transmission losses. The constraint equations include the DC load flow equations and line loading constraints. The voltage loop equations are written in a modified form, such that a close-loop equation will be ineffective if any line of this loop is deleted. The simulation model utilises the mixed-integer linear programming technique to obtain the least-cost network satisfying line loading constraints. Verification of the method is made through a test example View full abstract»

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