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1887

Proceedings of the Institution of Electrical Engineers

Volume 126, Issue 10, October 1979

Volumes & issues:

Volume 126, Issue 10

October 1979

Inverse scattering theory and profile reconstruction
  • Author(s): A.K. Jordan  and  S. Ahn
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 10, p. 945 –950
  • DOI:  10.1049/piee.1979.0175
  • Type: Article
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  • p. 945 –950 (6)
    An analytic method for the reconstruction of the profiles of refractive indexes of inhomogeneous, stratified regions is presented. The reflection coefficient r(k) for time-harmonic electromagnetic waves is represented as a rational function of k, the wave number. 1-dimensional inverse scattering theory has been applied to obtain analytic, closed-form expressions for the profile functions q(x) from r(k). The profile reconstruction method is demonstrated with a 3-pole r(k), that results in a q(x) which resembles an ionospheric electron-density profile previously analysed by direct scattering methods. The present communication generalises previous results to oblique incidence and compares several.q(x) obtained from different rational approximations to r(k).
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Ice-crystal depolarisation on satellite—earth microwave radio paths
Simplified algorithm for correcting both errors and erasures of Reed-Solomon codes
Synthetic test methods of high-direct-current circuit breaker
The truth about airgap leakage reactance in polyphase squirrel-cage induction motors
  • Author(s): G.H. Cheong
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 10, p. 971 –978
  • DOI:  10.1049/piee.1979.0179
  • Type: Article
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  • p. 971 –978 (8)
    The paper examines the validity of the theory arrived at by some authors, notably Alger, that the airgap leakage reactance of a polyphase squirrel-cage induction motor consists of two separate entities, namely, the ‘zig-zag’ reactance and ‘belt’ leakage reactance. The paper shows that not only the lower-order primary airgap m.m.f. harmonics have equal and opposing m.m.f.s induced in the secondary, but also the stator harmonics of pole-pair pitch smaller than the rotor slot pitch, which Alger calls ‘zig-zag’ leakage harmonics. This fact thus disproves that the ‘zig-zag’ leakage is a separate entity from the so-called ‘belt leakage reactance’, which Alger suggests should be disregarded for squirrel-cage motors. Further analysis reveals that the alternative theory of ‘differential leakage reactance’, as also derived by Alger, but on the assumption of vanishingly narrow slot-openings, is also valid for slot-opening which are not so. This, provided that the magnetising reactance, (with which the differential leakage coefficient must be multiplied to obtain the differential leakage reactance) incorporates the Carter airgap coefficient, as in fact it does in practice. The effect of slot-openings which are not infinitesimally narrow on the mean permeance and the permeance harmonics produced are also dealt with. The theory set forth in this paper is supported by locked-rotor tests on a number of machines.machines.
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Transient performance of linear induction machines following reconnection of supply
  • Author(s): R. Sankaran ; K.P.P. Pillai ; K.A. Muraleedharan
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 10, p. 979 –983
  • DOI:  10.1049/piee.1979.0180
  • Type: Article
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  • p. 979 –983 (5)
    A frequency-domain approach for the transient modelling of a voltage-fed, double-sided sheet-secondary-type linear induction motor (l.i.m.) is discussed. The problem of sudden reconnection of the l.i.m. in the motoring and braking modes at different operating speeds is analysed using discrete Fourier transforms. Attention is focused on the transient currents and thrust pulsations immediately following the switching action. The computational considerations for efficient calculation of the time response of the machine are discussed. Experimental results pertaining to the switching-in of a 2.5 kW l.i.m. from a 3-phase supply are presented, and compared with the predicted theoretical results.
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Nonlinear stabiliser design applied to microalternator system
  • Author(s): W.J. Wilson ; E.H. Okongwu ; J.H. Anderson
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 10, p. 984 –990
  • DOI:  10.1049/piee.1979.0181
  • Type: Article
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  • p. 984 –990 (7)
    A method for designing stabilisers for high-speed static exciters which includes the systems nonlinearities and allows for nonlinearities in the stabilisers is presented. The method combines the use of nonlinear-optimal-control techniques and system-identification techniques to design flexibly structured stabilisers based on readily available outputs of the system. The method also allows the combination of information from many operating conditions in the design process. The performance of the method is first examined on a computer simulation of a single- machine/infinite-bus system. Then the method is tested on a microalternator system to verify the computer results and to demonstrate the practical feasibility of the design method. The results show that the stabiliser performs very well both for small changes in the reference inputs and large disturbance faults applied to the system.
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New type of test for connectors to be used on aluminium conductors
  • Author(s): R.D. Naybour  and  J.R. Brailsford
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 10, p. 991 –994
  • DOI:  10.1049/piee.1979.0182
  • Type: Article
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  • p. 991 –994 (4)
    The basis and details are given of an accelerated lifetime-test procedure for assessing connectors on aluminium conductors. This test is designed to reproduce the degradation over the service lifetime, and the failure criterion is based upon the resistance values which would lead to failure in service. A large number of connectors can be tested, and this is shown to be essential if a reasonable degree of statistical significance is required in any test result. Results obtained from the new test are compared with those from a series of long-term current-cycling experiments chosen to reproduce a very arduous thermal history.
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Generalised polyphase fault-analysis program: calculation of cross-country fault
  • Author(s): L. Roy
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 10, p. 995 –1001
  • DOI:  10.1049/piee.1979.0183
  • Type: Article
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  • p. 995 –1001 (7)
    A general computer program using the phase co-ordinate technique has been developed for analysing series, shunt and simultaneous faults on balanced and unbalanced polyphase electrical networks. The program eliminates the need for maintaining numerous fault analysing subroutines, one for each kind of fault, and makes the solution of many difficult and previously unsolvable problems possible. It is employed to analyse the cross-country fault involving different phases. The solution method, program outlines and postfault results of voltages, currents and apparent power of an actual power system are given.
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Continuous alternating-voltage resulation using a thyristor bridge
Optimal output feedback by gradient methods with optimal stepsize adjustment
Electromagnetic control of flexible transmission shaft vibrations
Diagonal dominance and the method of pseudodiagonalisation
  • Author(s): M.A. Johnson
  • Source: Proceedings of the Institution of Electrical Engineers, Volume 126, Issue 10, p. 1011 –1017
  • DOI:  10.1049/piee.1979.0187
  • Type: Article
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  • p. 1011 –1017 (7)
    Very little practical guidance has been forthcoming on achieving a diagonally-dominant system prior to controller design, using either the Nyquist or inverse-Nyquist multivariable design techniques. In this reappraisal of pseudodiagonalisation and diagonal dominance, a linear space setting is used as a framework for the existing technique of Rosenbrock and several new related optimisations. The relationship between pseudodiagonalisation and dominance at one given frequency is discussed. In particular, sufficient conditions, for successive iterates of a pseudodiagonalisation procedure, to create dominance at that frequency are given. The extension of pseudodiagonalisation to try and create diagonal dominance per se is examined in some detail. The new technique for pseudodiagonalisation is utilised in a least-squares approach to diagonal dominance, and the new algorithm demonstrated on the example of Hawkins.
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Identification of factorable Volterra systems

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