摘要:

The paper analyses the influence of various types of field regulators on the dynamic performance of synchronous generators. Both conventional and dual-excitation generators are considered, with basic controls provided by voltage and angle regulators, which may have proportionate and derivative feedback. In the case of dual-excitation machines, both bus-rotor-angle and terminal-rotor-angle signals are employed in the quadrature-axis regulator.Stability is initially defined by computed regulation curves, and additional information is then obtained by calculating the variations of the synchronising- and damping-torque coefficients (TsandTD) with regulator gain. These graphs are superimposed on the regulation curves, to show howTsandTDdetermine the dynamic stability of the machine, and to illustrate the underlying reasons for stability.

DOI:10.1049/piee.1974.0316

出版商:IEE    

年代:1974

数据来源: IET

摘要:

A brushless a.c. generator is described which has a mode of operation similar to two wound-rotor induction machines connected in cascade. This cascade machine, which has previously been considered for application as a motor, has single stator and rotor windings in a conventional induction-machine frame. The machine is one of inherently high pole number. As an alternator, therefore, it is suitable for the generation of medium- to high-frequency supplies. The direct excitation current and the alternating output current flow in its one stator winding. Its cylindrical rotor iswound with an extremely simple short-circuited polyphase winding. Since no brushes, slip rings or rotating diodes are needed, the machine may be driven reliably at high speeds.A theoretical treatment is developed which takes account of magnetic saturation both in the steady state and in the transient state. Design and performance details of a prototype 400 Hz, 3000 rev/min., 3-phase machine are also included.

DOI:10.1049/piee.1974.0317

出版商:IEE    

年代:1974

数据来源: IET

摘要:

The distribution of axial flux in stator cores has been examined by numerical and experimental techniques. It has been found possible to consider separately the tooth region and the core back. In the tooth region, the axial flux is caused by the airgap fringing flux. In the core back, it is caused by the main core flux and the magnetomotive force of the winding overhang. The effect of slits in the teeth has been studied and also the effect of radial cooling ducts. The effect of butted joints between the core segments has also been considered. It has been found that axial flux is a very local phenomenon which cannot be eliminated, but which can be reduced by careful design of those regions where it is likely to be troublesome.

DOI:10.1049/piee.1974.0318

出版商:IEE    

年代:1974

数据来源: IET

摘要:

Dynamic-response evaluations of high-speed primary-protection systems are assuming an increasing importance as protection measuring times are progressively reduced, and these require very considerable detail of representation, not only for protection systems, but for the primary transducers from which they operate, and for the section of the primary system protected. Within this composite simulation, it is the latter area, that of the primary system for which the protection system under investigation provides coverage, to which the paper is devoted. In particular, the paper develops a phase-variable analysis scheme for synchronous generation in a form that allows it to be used directly in conjunction with electromagnetic transient analysis for the network system interconnecting generation. This provides a rational and unified scheme of analysis which combines fast-solution properties with considerable flexibility in application.

DOI:10.1049/piee.1974.0319

出版商:IEE    

年代:1974

数据来源: IET

摘要:

The paper describes and examines a technique which permits the power-flow problem in a power system to be analysed probabilistically instead of using normal deterministic methods. All the nodal loads and generation are defined as random variables and the power flow in each line is computed in terms of a probability density function. The expected values and standard deviation of each power flow are also calculated, and, in addition, the overall balance of power in the system is determined in terms of a density function. The purpose of this analysis is to account for the errors and statistical variations known to exist in the operation and planning of systems within one solution. This enables the power-flow problem to be treated objectively and allows quantitative assessment of reliability and security. The paper compares the results obtained probabilistically with those that would be obtained deterministically, and shows the much wider range of information gained in this type of analysis.

DOI:10.1049/piee.1974.0320

出版商:IEE    

年代:1974

数据来源: IET

摘要:

A 3-phase capacitor-voltage-transformer simulation is described which, when used in conjunction with a conventional artificial transmission line, allows complete relaying schemes to be tested. The accuracy of the simulation is confirmed by comparison of its response with that of a full-scale capacitor voltage transformer. Conjunctive distance-relay/capacitor-voltage-transformer tests are reported showing that transient errors degrade relay performance in speed and stability. Various methods for providing a more faithful voltage signal to supply the relay circuits are discussed.

DOI:10.1049/piee.1974.0321

出版商:IEE    

年代:1974

数据来源: IET

摘要:

As an alternative to present analogue-based control schemes, the basic design characteristics and dynamic performance of a newly proposed direct digital control are described. Tests are carried out in a specially designed scaled-down model provided with the necessary monitoring facilities for direct digital control. Special emphasis is given to the performance of relatively weak a.c. systems, and therefore the model includes suitable representation of the system parameters and of the filters normally used. It is shown that the implementation of equidistant-firing control by means of digital feedback loops provides fast recoveries from convertor and line disturbances.

DOI:10.1049/piee.1974.0322

出版商:IEE    

年代:1974

数据来源: IET

摘要:

A numerical technique for computing switching transients in multiphase nonlinear systems is presented. The nonlinear terminal characteristics of the lumped parameters have been considered in totality without approximating them as piecewise linear characteristics It has been shown that a fast, stable and accurate algorithm results from using Bergeron's method of characteristics for distributed parameter lines and a semi-implicit Runge—Kutta method for solution of the differential equations which describe the dynamics of linear/nonlinear lumped parameters.

DOI:10.1049/piee.1974.0323

出版商:IEE    

年代:1974

数据来源: IET

摘要:

The results of a survey into the effects and costs of electricity-supply interruptìons to 23 large industrial consumers are described. Detailed costs have been obtained for 12 companies and it is shown that they can be expressed in terms of a fixed cost, varying with the frequency of interruption, and a variable cost, varying with the duration of interruption.

DOI:10.1049/piee.1974.0324

出版商:IEE    

年代:1974

数据来源: IET

摘要:

Digital computer models of a selection of 2-input phaseand amplitude-comparator distance relays, generating mho and offset-mho characteristics in the steady state, are described and evaluated under transient conditions, necessitating interpretation of the criteria of operation in instantaneous terms. The primary system is simply represented by sinusoidal-voltage source and lumped impedances, comparator representation includes consideration of finite sensitivity and the provision of self polarisation. Dynamic performance is presented in the form of contoured distance-to-fault/system-impedance-ratio curves.

DOI:10.1049/piee.1974.0325

出版商:IEE    

年代:1974

数据来源: IET