摘要:

The development and implementation of a Prolog expert system using computer graphics is reported for the on-line monitoring and control of the 50 Hz single-phase overhead current collection catenary system currently in operation in Hong Kong. Running as an on-line consultant on a personal computer, this expert system allows operating personnel to perform intelligent network switching on a graphic picture representing the whole of the catenary line system. Users are able to find out effects of their own choice of switching sequence by examining graphic displays. Valid switching brings about changes in display configurations and colours to record changes in the on/off status of circuit-breakers or isolators, or the relocation of supply points. The expert system also checks against any invalid switching which causes a violation of interlocking rules, an isolation of overhead-line sections from the supply, or a phase-to-phase short-circuit of the utility system. Work to develop a methodology of evaluating voltage across voltages across crossovers which run between parallel overhead lines is also reported. A crossover with excessive voltages across it should not be used to divert a train owing to the risk of damaging insulators across the crossover. An accurate evaluation of crossover voltages usually involves the solution of a large set of simultaneous differential equations governing train timetables, controls, movements and power consumptions. It is shown how train consumptions may be referred to their nearest static busbars and the resultant admittance matrix does not include any moving busbars (trains). This ‘reduced’ matrix occupies only a very manageable memory for either a full power flow solution or any other approximate method of voltage evaluation

DOI:10.1049/ip-b.1992.0001

出版商:IEE    

年代:1992

数据来源: IET

摘要:

It has already been shown that the shape of the circulating current of parallel convertor configurations can be controlled by the use of thyristor controlled taps, and that such action can be used to increase the number of pulses. This technique, referred to as DC ripple re-injection, is generalised and it is shown, theoretically and experimentally, that it is possible to increase the number of pulses by any specified multiple of the basic pulse configuration.

DOI:10.1049/ip-b.1992.0002

出版商:IEE    

年代:1992

数据来源: IET

摘要:

A new modelling method for computing the AC resistance of litz wire in windings is presented. The method, being analytically based, is not subject to mesh limitations encountered with numerical methods and can handle multiturn windings with an unlimited number of strands. A feature of this approach is that, as analytical equations are used, it requires less computing power and can be implemented on smaller desktop computers. Experimental measurements are presented which support the validity of this method.

DOI:10.1049/ip-b.1992.0003

出版商:IEE    

年代:1992

数据来源: IET

摘要:

The paper presents an exploration of alternative control strategies for a high-torque brushless drive involving a permanent magnet rotor making use of NdFeB magnets. The efficiency of control over a speed range is explored, together with the response of the system to changes in speed demand and load. Two position control schemes are described and their performance is compared for different load conditions.

DOI:10.1049/ip-b.1992.0004

出版商:IEE    

年代:1992

数据来源: IET

摘要:

A method for calculating the developed force of the hybrid linear stepping motor (LPM) is presented. The force equation is derived by use of design parameters, such as the magnetic flux or magnetic flux density produced by the permanent magnet. The relation between the force and the speed EMF induced in the coil when the forcer is moved externally at a constant velocity is obtained. It is found that disagreement between the theoretical and experimental force-displacement curves increases at large currents. Effects of the eddy currents in the stator core and magnetic saturation on the developed force are investigated. The acceleration characteristics of LPM are compared with those of a rotating type hybrid stepping motor.

DOI:10.1049/ip-b.1992.0005

出版商:IEE    

年代:1992

数据来源: IET

摘要:

The continuous improvement of microprocessors performances make their use very attractive in the field of electrical drives control. They can greatly reduce the necessary control hardware and allow the set-up of user oriented control strategies, simply by changing the software. However, to obtain optimal solutions a proper approach to digital control is required. That means considering and solving all problems arising from digital control of electrical machines. The paper deals with digital control of asynchronous motors. Some different feeding strategies are presented and the corresponding motor performances compared. Evidence is given to the motor output deviations owing to the discrete time operation introduced by microprocessor control.

DOI:10.1049/ip-b.1992.0006

出版商:IEE    

年代:1992

数据来源: IET