摘要:

A simple multimachine test system has been employed to demonstrate a new approach to the co-ordination and selection of power-system stabiliser gain settings to achieve a specified level of overall damping performance on a multimachine power system. For a given operating condition the well established characteristic gain loci (CGL) method is used to determine (i) the range of gain settings for stable operation; and (ii) the gain settings to achieve, when possible, a specified level of damping. The results of (i) are compared with the more conservative results derived using the inverse Nyquist array method and described in an earlier paper. From the results of (ii), for a wide spectrum of operating conditions, a set of fixed gain settings is selected which provide a best compromise of damping performance over the spectrum. Some advantages and shortcomings of this application of the CGL method are highlighted. The paper is an extension of work described in the earlier paper.

DOI:10.1049/ip-c.1982.0008

出版商:IEE    

年代:1982

数据来源: IET

摘要:

The effectiveness of single-pole autoreclosure (SPAR) in maintaining power-system stability is largely determined by the speed with which secondary arc extinction, and hence autoreclosure, can be achieved. Realistic simulation techniques are of obvious importance in relation to the design of systems employing SPAR and, in the paper, digital methods are developed to enable the faulted response of EHV feeders, subjected to secondary arcing phenomena, to be more realistically simulated than has hitherto been possible. The new techniques are also of importance in relation to programmable based protection test equipment. Based upon experimental data, methods of modelling the nonlinear behaviour of the earth-fault arc path, in both conducting and extinction states, are described; together with the techniques developed for incorporating such models into practical EHV system interconnections. The paper concludes by illustrating and discussing the results of a computational study relating to a typical short 500 kV feeder employing SPAR.

DOI:10.1049/ip-c.1982.0009

出版商:IEE    

年代:1982

数据来源: IET

摘要:

In an attempt to arrive at an improved understanding of the disturbing influence of lightning upon power distribution lines, a unique project is described involving the construction of a 10km test distribution line together with an automated lightning and surge recording station. Preliminary data are presented from measurements carried out over two full thunderstorm seasons, in respect of direct strokes to the line and induced overvoltage surge characteristics. The majority of lightning disturbances are caused by induction from nearby discharges to ground, are of positive polarity, rarely exceed 100 kV, and are generally accountable in terms of classic electromagnetic field theories of induction. Several bipolar surge records have also been obtained, however, whose characteristics deviate considerably from theoretical prediction, and it is considered that this might be due to the influence of the leader mechanism. It is also found that the direct stroke incidence to the line is considerably greater than anticipated from traditional theory, as is also the frequency of multiple pole flashovers, and it is concluded that further research is required on the attractive effects of lines and of the final stages of the striking process.

DOI:10.1049/ip-c.1982.0010

出版商:IEE    

年代:1982

数据来源: IET

摘要:

The paper gives computed probability density characteristics for the resultant sequence currents in a three-phase system for several specified load-current probability patterns. Loads are considered to be connected in star, with or without neutral connection, or delta.Results are applicable to both fundamental and harmonic components of load and sequence currents and may be used to assess either the probability of the resultant amplitude of the sequence currents, with many loads on the system, or the probable time duration for any sequence-current magnitude with one load in each phase varying in a prescribed manner over an appropriate period of time. Applications of the characteristics to some typical system problems are examined.

DOI:10.1049/ip-c.1982.0011

出版商:IEE    

年代:1982

数据来源: IET

摘要:

A simple algorithm for fast computation is an important requirement for the efficient application of microprocessors in power-system relaying. Using the rectangular transform technique, a fast and accurate algorithm has been developed for transformer protection. The algorithm generates the Fourier coefficients by addition and subtraction routines only. The method provides good discrimination between the nonzero differential current produced by the transformer energisation and that produced by internal faults. The algorithm provides fast fault detection and yields a large blocking signal, using second or higher harmonic components. The digital simulation and test results on a variety of fault and inrush conditions, including the periodic inrush ones, clearly demonstrate the efficacy of this algorithm for the protection of the power transformer. Furthermore, owing to the relative simplicity and absence of time consuming multiplication and division calculations, the algorithm is quite suitable for microprocessor-based protection of power systems.

DOI:10.1049/ip-c.1982.0012

出版商:IEE    

年代:1982

数据来源: IET

摘要:

A detailed calculation is presented of both axial and radial components of the electromagnetic forces developed in foil-wound transformers. The actual distribution of current along the length of the foil and the presence of iron core are taken into consideration. The axial forces transferred to the end supports and the case of asymmetrical windings are also calculated. Attention is focused upon the effect introduced by the nonuniform distribution of current in the windings. A mathematical model is set up for the general case, where both the transformer windings are of foil and asymmetrically placed relative to the yokes. Transformers having various combinations of foil-wound, wire-wound and sectionised windings are included within the general analysis. The practical scope for the application of the method is illustrated by typical examples.

DOI:10.1049/ip-c.1982.0013

出版商:IEE    

年代:1982

数据来源: IET