摘要:

The design of elliptic digital filters through the bilinear transformation is considered. Sets of formulas are derived which can be used to design filters satisfying prescribed specifications. A simple design procedure based on these formulas is then described. The procedure is illustrated by designing an 8th-order bandpass filter and a 10th-order bandstop filter.

DOI:10.1049/piee.1977.0062

出版商:IEE    

年代:1977

数据来源: IET

摘要:

In the paper, single and multiple-fault locating test sets for Reed-Muller canonic networks are derived. The fault model assumes stuck-at faults at theI/Oleads of AND gates, and that an EOR gate under a fault can produce any other function of two inputs other than equivalence. The results in the paper give an insight into the complexity of testing of a class of logic networks.

DOI:10.1049/piee.1977.0063

出版商:IEE    

年代:1977

数据来源: IET

摘要:

Distance-type protective equipment often has, for a variety of practical reasons, rather limited tolerance to high-resistance earth-fault conditions. In this paper, a new distance relay, which has increased resistive coverage, is described, and it is shown to possess a characteristic which varies so as to accommodate more closely the impedance measured for various prefault loading conditions. Complicated setting procedures are avoided, and the results of dynamic tests show that the accuracy of the measurement can be maintained. A high degree of immunity to balanced phenomena such as power swings and operation during faults not involving a particular phase is inherent to the new relays. The paper concludes with a presentation of results relating to an application involving a 220 kV line of unearthed construction.

DOI:10.1049/piee.1977.0064

出版商:IEE    

年代:1977

数据来源: IET

摘要:

A method has been developed for computing electromagnetic fields and eddy-current heating in and around the core ends of large generators. The effect of tooth geometry. Pistoye slots, cooling ducts, anisotropy saturation, distributed eddy currents and variable stacking factor are included. The calculation is formulated as a 2-potential 3-dimensional nonlinear boundary-value problem, and solved by an iterative finite-difference scheme with crosscoupled harmonics. The predicted axial fields have been compared with measurements on a 500 MW machine.

DOI:10.1049/piee.1977.0065

出版商:IEE    

年代:1977

数据来源: IET

摘要:

A linear synchronous motor has been designed to propel a 480 km/h magnetically levitated passenger vehicle. The paper describes the motor and presents the results of tests which have been performed on essentially full-scale components of the motor using a 7.6 m-diameter test-wheel facility. Controlled starting, acceleration, cruising, deceleration and transient operation have been demonstrated. A 6-component force balance has been used to measure the three forces and three moments acting on a single stationary superconducting magnet due to its interaction with the split 3-phase windings mounted on the rim of the test wheel and energised by a variabl-efrequency current-controlled inverter power supply. Measured forces and terminal characteristics over complete cycles of force angle are in excellent agreement with analysis based on a coupled circuit model of the machine and mutual inductance computations. Moments were measured to be small underall operating conditions. Two modes of control have been demonstrated. The α-scheme, proposed for a full-scale system, maintains the angle between induced voltage and phase current at a value which optimises the motor characteristics, i.e. inverter MVA rating, etc. β-control, which may be required for starting, uses vehicle position detectors to fire the inverter thyristors at appropriate times.

DOI:10.1049/piee.1977.0066

出版商:IEE    

年代:1977

数据来源: IET

摘要:

The braking forces acting on a thick conducting disc rotating in the field of rectangular electromagnets are examined. The analysis is based on the solution of quasi-one-dimensional vector potential in the plate and airgap regions of the device. Finite thickness of the plate is taken into account explicitly in deriving the general expression for the braking force. This expression is shown to reduce to the conventional induction motor characteristic in the thin plate limit and a simple original expression is presented for the calculation of braking forces in the skin-effect region.

DOI:10.1049/piee.1977.0067

出版商:IEE    

年代:1977

数据来源: IET

摘要:

A machine test system is described which provides convenient analytical facilities applicable to any transient test involving measured waveforms consisting of mixtures of exponentially time-varying a.c. and d.c. components. The analysis of a sudden 3-phase short circuit of a synchronous machine is used to illustrate the analysis procedure and the results are shown to be more accurate and consistent than those derived using traditional techniques. The accuracy of analysis is examined using synthesised test data.

DOI:10.1049/piee.1977.0068

出版商:IEE    

年代:1977

数据来源: IET

摘要:

The authors' previous work on the stability of repetitive processes exhibiting strong interaction between successive passes (transverse interaction) is extended to cover cases of longitudinal interaction occurring along each pass. It is shown that such interaction can be represented by transfer functions whose associated impulse responses are delayed even functions and therefore not encountered in normal process modelling. The beneficial effects of such transfer functions on system stability are demonstrated, but other types of longitudinal interaction, arising from geometrical offset, are shown to affect stability adversely. Consideration is also given to multipass processes having more than one control loop and it is shown that, where the sensor for one loop can be sited in advance of that for another, easily implemented feedforward techniques can be applied to stabilise a multipass process which would otherwise be inherently unstable.

DOI:10.1049/piee.1977.0072

出版商:IEE    

年代:1977

数据来源: IET

摘要:

The paper presents a new design procedure of an autonomous area regulator for automatic generation control (a.g.c.) of interconnected power systems. The regulator is of proportional-plus-integral type. It applies the basic concept of optimal linear regulators, using a reduced number of measurements from its own power area, as in the conventional control schemes. It is found that both the regulator structure and the steady-state system performance are the same as in the case of conventional control, with significant improvement of system transients. These features are advantageous from the implementation point of view, compared to the previously suggested linear regulator schemes that required the transmission of some measurements from neighbouring areas. The paper gives an analytical derivation of the autonomous a.g.c. system design and some digital simulation studies performed on a linearised state-space model of a 2-area interconnected powersystem.

DOI:10.1049/piee.1977.0073

出版商:IEE    

年代:1977

数据来源: IET

摘要:

Methods for estimating the parameters of the lumped difference equation models postulated for distributed parameter systems are presented. These methods utilise pseudorandom binary sequences to yield spatial and temporal pulse responses which may then be processed using instrumental variable techniques to give parameter estimates. Alternatively, regression methods are described which process either the system output at various points in space or the corresponding pulse response to give similar estimates. Computer simulation results are used to confirm the theoretical concepts.

DOI:10.1049/piee.1977.0074

出版商:IEE    

年代:1977

数据来源: IET