摘要:

An analysis is presented of the problem of designing a distributor from cables of different sizes so as to obtain a design using the minimum volume of conductor, when voltage regulation is the limiting factor. A simple, but exact, procedure is developed for calculating the lengths of the cozstituent cables. The adaptation of the method for branched distributors is also described.

DOI:10.1049/ip-c.1982.0015

出版商:IEE    

年代:1982

数据来源: IET

摘要:

In the original development ofz-transform electromagnetic transient analysis in power systems, transmission-line impulse responses and surge-impedance functions formed initially in the frequency domain were mapped into thez-plane by bilinear transformation, although it is known that this transformation is one that gives rise to a form of distortion error. In now providing means by which this error may be avoided, methods are investigated in the paper by which transmission-line response functions can be synthesised directly in thez-plane. Given the high accuracy in function definition which this can provide, an examination is made of the relationships that are to be satisfied between the step length in the time-domain and transmission-line aerial-and earth-mode transit times. In particular, it is shown that residual errors arising from the frequency dependence of the earth-mode transit time are amenable to analysis and then, based on this, to control by interpolation. Drawing on trial analyses of a 400 kV single-circuit untransposed line, the paper then evaluates the further advances inz-transform electromagnetic transient analysis that these further developments can achieve.

DOI:10.1049/ip-c.1982.0016

出版商:IEE    

年代:1982

数据来源: IET

摘要:

Symmetrical components of voltages and currents of three-phase power systems are used for protection purposes and power-system automatic control. Until now, passive and active analogue filters have been used for determining the symmetrical components from the phase quantities. A disadvantage of analogue filters can be the fact that it is difficult to suppress harmonic components that may be present in the phase quantities. It will be demonstrated that very suitable digital filters can be implemented with a microprocessor which are able to suppress the second- and third-harmonic components as well as the DC components that are present in the measured signals. Tue input of these digital filters consists of three phase quantities and the output consists of three numbers representing the amplitude of the zero-, positive- and negative-sequence quantities.

DOI:10.1049/ip-c.1982.0017

出版商:IEE    

年代:1982

数据来源: IET

摘要:

The problem of measurement error detection and correction in power-system substations or groups of substations is considered. It is shown that, by formulating the problem as a linear program, an efficient automatic solution is obtained which can reject erroneous power measurements and switch indications by taking into account redundant information together with natural circuit laws. The location and degree of inaccuracy of erroneous data are also obtained automatically. Computational examples are given which show that the processor time and storage requirements are very modest. The technique is therefore suitable for application in micro- or minicomputer systems located at substations and may be regarded as a prefiltering and data concentration phase for full-scale topology determination and state estimation at computer control centres.

DOI:10.1049/ip-c.1982.0018

出版商:IEE    

年代:1982

数据来源: IET

摘要:

The paper reviews previous work on aerodynamic and mechanical devices for the control of galloping oscillations. By considering energy input and energy dissipation, a value is set for the damping that mechanical devices need to give. The paper describes two ideas for mechanical dampers. The first is a cross-arm-mounted device driven by the swinging of the suspension insulators. Such dampers give large damping levels to the ‘one-loop’ modes of galloping, and are unaffected by errors in damping rate or by ice accretion on the conductors. The second device is an inspan damper mounted on the conductors. This concept is not new, but an optimised and more effective damper can be produced. Results are presented for dampers optimised in each of two ways. It is shown that dampers having a small fraction of the mass of the conductor span should give significant improvement in galloping behaviour. The paper considers the problems of converting these two ideas into operational hardware.

DOI:10.1049/ip-c.1982.0019

出版商:IEE    

年代:1982

数据来源: IET