الفهرس 
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Abstract
Investigations reported in the recent past confirm the vastly improved dynamic and transient stability characteristics of dual¬excited synchronous machines. In order to utilize more fully the capabilities of these machines, it is of prime importance to understand how they behave under different conditions and to assess their advantages and disadvantages in comparison with conventional synchronous machines.
It is the main objective of this thesis to examine various aspects
of the dynamic behaviour of dual-excited synchronous machines. The mathematical treatment involves a series of digital, analytical and
analog simulations;both rigorous and simplified. A good deal of this
work is devoted to dynamic stability investigations with particular emphasis on the choice of the parameters of the excitation systems for maximum possible capacitive loading. In addition, the limitations imposed on the excitation control of dual-excited synchronous condensers are determined. This involvesan analytical evaluation of the relative effectiveness of the different feed-back control signals. Information regarding the phenomenon of self-excitation and electromechanical oscilla¬tions of dual-excited synchronous machines, particularly when they are connected through series compensated transmission lines, are also presented. These dynamic stability investigations are followed by a study of the transient stability characteristics of these machines. The main objective of this study is to explore the effect of the different modes of operation, the loading conditions, the possible schemes of excitation control and the parameters of the control loops on their transient stability limits. Another important aspect is the development of generalized equivalent circuits for these machines, which provide a convenient method for determining their steady-state and transient behaviour. In this respect, expressions for the machine reactances and time constants as well as formulae for the 3-phase short-circuit currents are derived. The equivalent circuits are also utilized in devising a new approach to analog computer simulation of such machines.