摘要:

A detailed design procedure is presented for an eccentrically insulated travelling-wave antenna suitable for subsurface radio communication. Simple formulas for the input impedance, current distribution and field pattern of this directional antenna are derived.

DOI:10.1049/piee.1979.0252

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The analysis of a step discontinuity of single-mode slab waveguide excited in the dominant mode is presented for both TE- and TM-modes. The problem is formulated by using the mode-matching procedure parallel to that of Marcuse. The solutions for the reflection coefficient, transmitted power and radiated power are then obtained by the application of the residue-calculus technique, which leads to more general expressions than those so far obtained by others who used more complicated methods. Numerical results are given which are in good agreement with previous results for specific cases. For the general case, the results also agree very well with those obtained by the reciprocity theorem.

DOI:10.1049/piee.1979.0253

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The unequal impedance angles of the positive and zero sequence underground-cable impedances, which are in variance with overhead lines, requires a study to evaluate the appropriate relay residual compnesation factor, which is of paramount importance for earth faults. The problem, in many cases, is provoked when the protected zone consists of a mix of underground cables and overhead lines. This paper shows the importance of having an accurate residual vectorial compensation together with a proper selected comparator characteristic.

DOI:10.1049/piee.1979.0254

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The paper deals with the operation of self-controlled wound-field generators for small-scale wind-power application in which the output is connected to a constant-resistance load and the field is connected in plain shunt or series. It is shown that, with this configuration, a fairly good natural match can be obtained between the power/speed characteristics of the generator and the windmill, particularly when the magnetic circuit of the generator goes fairly hard into saturation at higher speeds and field currents. Test results are included and indicate that an external d.c. source would often be necessary to initiate ‘build-up’ in a practical system.

DOI:10.1049/piee.1979.0255

出版商:IEE    

年代:1979

数据来源: IET

摘要:

A new speed-control system suitable for a wound-rotor induction motor is introduced. This system is a combination of two schemes: primary voltage control by means of bias voltage control and Scherbius control. The performance characteristics of the system are obtained and compared for the two types of speed control (new speed control system against hybrid system and Scherbius system). The investigations are verified by the concurring data of theoretical and experimental results. The possibility exists for these systems to operate independently of each speed control over a wide range for the 3-phase wound-rotor induction motor, such as is sometimes used in pump driving systems. Both schemes have some inherent advantages and disadvantages. On balance, it appears that combined usage of the two systems is practical and convenient

DOI:10.1049/piee.1979.0256

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The effect, hitherto neglected, of core loss of nonlinear inductors has been considered in the analysis of a parallel ferroresonant circuit. Some generalised conclusions based on mathematical proofs are made to give deeper physical insight into the effects of core loss on: (a) the critical values of linear system parameters for the onset of ferroresonance; (b) jump-from points; (c) percentage unstable zone; (d) susceptibility to ferroresonance; and (e) jump-to points and jump severity. A comparative study of the theoretically computed response curves with and without loss and the one observed experimentally for a parallel ferroresonant circuit shows that agreement between the experimental observations and the computed results is closer when core loss is included. Further, the experimentally observed critical values of resistance and inductance are closer to the theoretical values obtained when core loss is included.

DOI:10.1049/piee.1979.0257

出版商:IEE    

年代:1979

数据来源: IET

摘要:

By passing of a thyristor bridge is being used in large convertor systems such as in h.v.d.c. transmission lines for fault conditions. In normal voltage-control operation, an increase in the total power factor of the whole convertor system can be achieved by relieving a few bridges from current by using external bypass valves. However, a fully rated external bypass valve is relatively expensive because it has to carry continuously the full direct current. A novel way of continuous operation of the bridge thyristors in a cyclic firing method is described in the paper. This method allows the designer to eliminate the external bypass valve and still get the bypass mode of operation.

DOI:10.1049/piee.1979.0258

出版商:IEE    

年代:1979

数据来源: IET

摘要:

A partitioning algorithm based on Benders's method1is described. This algorithm makes possible the solution of a large problem in a limited computer memory. The special properties of the partial problems of the partitioned problem are exploited to reduce further memory requirements and computation time. This method has been implemented on the SEL 32/55 computer of the UNERG at Charleroi in Belgium.

DOI:10.1049/piee.1979.0259

出版商:IEE    

年代:1979

数据来源: IET

摘要:

The design of large stochastic optimal regulating systems is considered. The system model represents a typical industrial-control situation, with coloured noise and disturbance inputs to the plant. The resulting system involves a large number of state variables, and it is inefficient to solve the control and filtering Riccati differential equations for this system. It is shown that the redundancy in the system equations can be used to reduce the order of the Riccati equations which must be solved. It is also shown that a steady-state (or constant-gains) solution to the problem exists, and is unique. This system is also shown to be asymptotically stable.In the design of industrial controllers, it is often necessary to include integral action to offset constant disturbances. This is also desirable in the above situation, even when most of the disturbances are modelled accurately, if the regulating error is to be reduced to zero in the steady state. The integral control is introduced by including an additional term, which involves an integral operator, in the usual cost function. The performance criterion is also specified, so that the system regulates about given set-point values. The system is described in general terms, but the problem is based upon the dynamic ship-positioning control problem. The paper thus provides a formal solution to this problem, based upon l.q.g. stochastic optimal-control theory.

DOI:10.1049/piee.1979.0261

出版商:IEE    

年代:1979

数据来源: IET

摘要:

A new coaxial r.f. power meter, developed for use as a primary standard for the frequency range 0–8 GHz, has an uncertainty of ≤0.2%, excluding d.c. standards and mismatch errors. The reading time is 3 min, and the effective efficiency, which can be determined without dismantling the instrument, varies smoothly from 99.89% at 1 GHz to 99.43% at 8 GHz. A novel feedback technique is used. The instrument is portable, and the r.f. head is small enough to be accommodated without difficulty in most calibration test benches.

DOI:10.1049/piee.1979.0262

出版商:IEE    

年代:1979

数据来源: IET