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Electrical Engineers, Proceedings of the Institution of

Issue 7 • Date July 1977

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Displaying Results 1 - 19 of 19
  • Bridge method for the accurate measurement of waveguide wall loss

    Publication Year: 1977 , Page(s): 589 - 592
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    The effect of slight discontinuities within the measuring arm of a wall-loss bridge is investigated, and it is shown that erroneous values of attenuation coefficient may arise, owing to the presence of such discontinuities. A method is proposed by means of which such errors may be eliminated. Experimental results are presented, demonstrating that significant errors do arise owing to imperfections in the apparatus and that these errors may be removed using the technique described. View full abstract»

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  • High accuracy analogue multiplier

    Publication Year: 1977 , Page(s): 593 - 596
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (678 KB)  

    This paper describes the circuitry, construction and performance of an analogue multiplier which achieves an accuracy within 0.03%. The technique employed involves splitting one analogue input signal into two parts, one in digital form and the other in analogue form. The two parts are separately multiplied by the other input signal, the results summed together to obtain the required product. Here, particular emphasis is laid on the circuitry and construction necessary to achieve high accuracy while minimising the effects of the inevitable switching involved with this method. View full abstract»

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  • IEE North Eastern Electronics & Control Section: Chairman's address. Adaptive and self tuning controllers

    Publication Year: 1977
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (157 KB)  

    First Page of the Article
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  • Estimation of power-system stability domains using quadratic Lyapunov functions

    Publication Year: 1977 , Page(s): 597 - 601
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (533 KB)  

    Systematical construction of Lyapunov functions for studying power-system transient-stability problems are investigated. Lyapunov functions that are quadratic in the state variables, are constructed by a direct-search technique involving the maximisation of the volume of the region of asymptotic stability. Single, as well as multimachine, problems have been studied. View full abstract»

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  • Real-time monitoring of power systems using fast-decoupled load flow

    Publication Year: 1977 , Page(s): 602 - 606
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    The paper presents the implementation of the fast-decoupled load-flow technique for real-time monitoring of power systems in the presence of metering inaccuracies and data-acquisition failures. The real-time load-flow solution with mode injections and redundant line flows, using the fast-decoupled load flow, is much faster and requires less computer storage than that using conventional Newton-Raphson method, but still provides the same accuracy. Results of this analysis for a.e.p. 30-busbar test system are included for illustration. View full abstract»

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  • Self-excitation of dual-excited synchronous machines

    Publication Year: 1977 , Page(s): 607 - 612
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (728 KB)  

    The paper deals with the study of self-excitation phenomenon of dual-excited synchronous machines connected to highly series-compensated transmission lines having low resistance, particularly in the case of e.h.v. long transmission lines using bundled conductors. Analysis for self-excitation for a typical system is carried out through the Routh-Hurwitz and a simpler approach for the unregulated case, whereas the parameter-plane approach is effectively used for the regulated case. The effect of the transformer (p¿) terms in the mathematical model on self-excitation has been highlighted. A comparison between the performance of dual-excited and equivalent conventional machines has been brought out. Dual-excited turbogenerators exhibit instability due to fast self-excitation only, whereas dual-excited hydroelectric generators exhibit instability due to both slow and fast self excitation. While the performances of both dual-excited and equivalent conventional turbogenerators are found to be nearly therome, the performance of a dual-excited hydroelectric generator is found to be decidedly better than that of an equivalent conventional one. In general, slow self excitation can be completely suppressed, but not fast self excitation, even with dual excitation. Complete elimination of self excitation seems to be feasible with a suitable resistance Rc in parallel with the capacitor. Another interesting conclusion is that the omission of the p¿ terms for the regulated case leads to highly optimistic results. View full abstract»

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  • Effect of load characteristics and voltage-regulator speed-stabilising signal on power-system dynamic stability

    Publication Year: 1977 , Page(s): 613 - 618
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (751 KB)  

    It has been recognised that the dynamic-stability margin of synchronous generators can be improved by the damping effect of the speed-stabilising signal in the excitation control system. The dynamic-stability analysis is extended to account for the effect of loads modelled as a nonlinear function of voltage. In order to make the analysis realistic, a conventional load-frequency control system is also considered to be regulating the power-system frequency and tie-line power. The load voltage is considered to be undergoing changes in the dynamic period in response to speed signal in the excitation system which establishes a coupling between QV and p.f. control loops. The damping effect on frequency and tie-line power oscillations is studied by varying the load characteristics and excitation stabiliser parameters. View full abstract»

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  • IEE North Midland Centre Power Section: Chairman's address. Power systems ߝ today and tomorrow

    Publication Year: 1977
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (150 KB)  

    First Page of the Article
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  • Arc instability and current chopping in an air-blast interrupter

    Publication Year: 1977 , Page(s): 619 - 627
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1382 KB)  

    The performance of a single gas-blast interrupter, when switching low amplitude inductive currents, has been examined in detail. The effect of local circuit-component variation has been studied, and the factors which dominate the arc-instability condition established. It has been shown that circuit voltage and rate of change of current are of less significance than instantaneous current in determining the point of arc instability, though they can influence arc-restriking performance during the current chopping period. Where the dominant capacitance is separated from the interrupter by some inductance, both instability and chopped-current levels are increased. The nature of the arc-instability oscillation has been studied and related to earlier work. A new technique for predicting instability and hence estimating chopped current level for different circuit arrangements based on a single series of tests is proposed. This, when coupled with a frequency impedance characteristic for the connected circuit, would enable more precise prediction of current chopping levels in a given system application. View full abstract»

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  • Discussion on ¿Frequency content of switching overvoltages¿

    Publication Year: 1977 , Page(s): 628 - 630
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  • Sensitivity method for online optimisation of a synchronous-generator excitation controller

    Publication Year: 1977 , Page(s): 631 - 638
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (913 KB)  

    The paper describes a technique for the optimisation of the parameter settings of the excitation controller of a synchronous machine which is suitable for on-site use. The optimisation method is based on an integral squarederror criterion, and involves the use of parameter sensitivity functions to estimate the parameter changes needed to alter system responses to approach some predetermined or desirable form. The computation of the parameter sensitivity functions is achieved by a direct method, which does not demand explicit identification of the controlled system and which yields the sensitivity functions of all output variables to all adjustable parameters from the results of a single-step test. The technique may be implemented using a small digital computer. The paper includes the results of simulation studies on unsynchronised and on loaded generators, together with results of micromachine experiments. View full abstract»

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  • Performance of high-speed distance relays with particular reference to travelling-wave effects

    Publication Year: 1977 , Page(s): 639 - 646
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1243 KB)  

    Travelling waves on e.h.v. transmission lines often cause considerable distortion of relaying measurands, and, in this paper, modern methods of digital simulation are used to examine the performance of crosspolarised mho relays under more realistic conditions than have hitherto been possible using conventional conjunctive test methods. It is shown that travelling-wave effects can cause a significant delay in the fault-detection process and that, in this respect, the bandwidth of the voltage transformers (v.t.s) is an important influencing factor. The extensively used block-average comparator arrangement is examined in detail, and it is shown that a recently developed processing technique can provide faster fault-clearance times when coupled with a small degree of overreach. The paper concludes with a brief consideration of the performance of the block-average comparator mho relay in a long-line application. View full abstract»

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  • Induction-motor torques with pulse-width-modulated inverter drive

    Publication Year: 1977 , Page(s): 646 - 647
    Save to Project icon | PDF file iconPDF (260 KB)  
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  • Modal decomposition for power transmission lines with imperfect earth return

    Publication Year: 1977 , Page(s): 647 - 648
    Cited by:  Papers (5)
    Save to Project icon | PDF file iconPDF (219 KB)  
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  • Functional iteration for solving nonlinear system equations

    Publication Year: 1977 , Page(s): 649 - 650
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    Functional iteration has been very widely used for the solution of nonlinear system equations. Although sufficient conditions have been given for the iteration sequence to converge, a method to determine the precise number of iterations that are required is not to be found in the literature. The availability of such information would enhance, considerably, the utility of the method. Using the concept of `stop-growing terms¿, an algorithm is now proposed which enables one to determine precisely the number of iterations that are required for the solution to converge to a predetermined degree of approximation. View full abstract»

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  • Dynamic performance of permanent-magnet stepping motors

    Publication Year: 1977 , Page(s): 651 - 655
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (660 KB)  

    The paper deals with the dynamic performance of permanent-magnet stepping motors as affected by various kinds of practical load torques. The constant component of load torque, including coulomb friction, results in stable and unstable equilibrium regions, while the viscous torque component is analogous to the damping-factor increase. The technique of generating phase trajectories for a 2-phase permanent-magnet motor, using a digital-computer program, can take into account the actual static torque/angle characteristic of the motor. Pull-in and pull-out stepping rates, obtained from the phase planes, change significantly on account of the variation in motor damping. The technique can also be applied to other types of stepping motors. View full abstract»

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  • Multiplex electronic commutation

    Publication Year: 1977 , Page(s): 656 - 658
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    An electronic switching scheme is outlined that can scan No outputs in step across Niinputs (Ni¿Nomuch more economically than the conventional Ni.No switch matrix. It thus reduces the relative advantage of a mechanical solution reported previously. Applications include instrumentation, scanning beam-formers, and possible spatiallymultiplexed slip rings. View full abstract»

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  • Theory of flux penetration into laminated iron and associated losses

    Publication Year: 1977 , Page(s): 659 - 664
    Cited by:  Papers (6)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (884 KB)  

    The penetration of leakage flux into a laminated machine or transformer core is governed by the currents induced in the steel, and poses an anisotropic and 3-dimensional field problem which is also severely nonlinear. It is shown that the differential equations can be formulated in terms of an electric vector potential T, and magnetic scalar potential ¿, and that the solution can be expressed in the form of three different characteristic modes, two associated with the core surfaces and the third describing the flux penetration into the interior. This form of solution provides both a qualitative and quantitative picture of the 3-dimensional flux paths, and eddy current loss distribution, and also a practicable means of allowing for saturation. The result can be expressed in the form of a simple network model that is well suited to numerical solution by computer. View full abstract»

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  • Potential from a ring of charge

    Publication Year: 1977
    Save to Project icon | PDF file iconPDF (106 KB)  
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Aims & Scope

The Proceedings of the Institution of Electrical Engineers was published by the IET between 1963 and 1979.

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