摘要:

Since the Second World War, the scope of electrical engineering has changed completely. Vast new subject areas have been opened up, and the relative importance of power engineering in the field of electrical engineering has declined even though its scope and interest have significantly increased. The proportion of electrical engineering students studying power engineering has also declined, and there is a danger of losing ‘power’ capability in most electrical engineering departments, even though there is evidence that the supply of power graduates is already inadequate for industry's needs. The paper proposes that the education, not only of power engineers, is too specialised and more general training is needed. The paper illustrates the contributions that universities make to engineering through teaching and research.

DOI:10.1049/ip-b.1986.0001

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The paper describes a frequency-convertor AC exciter for use with a synchronous generator to produce a unit which is brushless, self-excited and current compounded. The stator contains a shunt winding fed from the output voltage of the generator and a series winding carrying the output current. These two windings are arranged so that the excitation current supplied to the generator from the rotor winding of the exciter, via a rotating rectifier, increases with both an increasing load current and a decreasing load power factor. The paper presents a detailed consideration of the new exciter, which shows that it possesses all the characteristics found in the familiar static current-compounded arrangement. An optimal design investigation demonstrates a conflict between the requirement for a minimum drift in the generator terminal voltage due to changes in temperature and the need to minimise the VA loading that the exciter imposes on the generator. It is shown, however, that the use of capacitors in series with the shunt winding will go a long way towards eliminating this problem. Consideration is also given in the paper to a suggested development of the frequency-convertor exciter, aimed at the production of a variable-speed but constant-frequency generating unit.

DOI:10.1049/ip-b.1986.0002

出版商:IEE    

年代:1986

数据来源: IET

摘要:

Interface problems related to adapting available 3-phase inverter designs between a photovoltaic array and an AC motor generator without a battery, have been partly solved. However, instability and nonminimal phase responses have been observed on the experimental array. So, the contributing research that will be described in the paper is (i) modelling the photovoltaic system by means of state representation, (ii) studying stability and nonminimal phase responses with the control functions and (iii) describing a method to compute optimal control functions. If the control function is the amplitude stator frequency, the system may be unstable. Replacing the stator frequency control function by a rotor frequency allows the system to remain stable. The phase of the transient response of the speed state variable always is non-minimal when the voltage cell is lower than the optimal voltage cell.

DOI:10.1049/ip-b.1986.0003

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The performance of a static Kramer drive is substantially affected by the DC voltage waveform of the thyristor recovery bridge and the inductance of the DC link smoothing reactor. The paper describes a novel method of analysis of the periodic transient performance of such a drive, in which full account is taken of these practical aspects of the recovery system. The analytical model obtained has been verified by comparison of calculated and measured performance for four different types of recovery bridge. The computed results have allowed a more comprehensive examination of drive performance than is possible from the results of practical tests.

DOI:10.1049/ip-b.1986.0004

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The inrush current associated with energising power transformers can cause interference and damage to other system components. The paper sets out to describe an accurate analytical method which can be used to find the inrush current in any 3-phase transformer in common use. The method is an extension of one previously described to calculate inrush in single-phase transformers. The method is powerful in that the current and its decay can be calculated over many cycles, not just the first peak, as has been possible by other methods. A comparison is made between different transformer connections and illustrated by numerical examples. These show, for example, that resistance in the neutral of a star connected transformer has little effect compared to using the same resistance in series with the energised windings.

DOI:10.1049/ip-b.1986.0006

出版商:IEE    

年代:1986

数据来源: IET

摘要:

A simple general method of allowing for the effect of fringe fields around the airgaps in inductor cores is described. Experimental results for two standard E core shapes are used to demonstrate that the technique is reliable and necessary when calculating inductances. Three alternative methods of allowing for fringe fields are also described and compared.

DOI:10.1049/ip-b.1986.0007

出版商:IEE    

年代:1986

数据来源: IET