Modelling and analysis of turbogenerators in single machine and multi- machine subsynchronous resonance studies.
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Date
1987
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Abstract
Subsynchronous Resonance (SSR) is a condition which occurs when
turbogenerators are connected to series capacitively compensated
transmission systems and it can cause large scale damage to the
turbogenerators. The accuracy of predictions of this phenomenon are
limited by the accuracy of the mathematical models used for the various
system elements.
The modal method of modelling a turbogenerator shaft, in which parameters
are associated with each natural torsional mode of the shaft, is
investigated in detail and the sensitivity of SSR predictions (both small signal
and transient) to uncertainties in the mode parameters is evaluated.
The modal model is then used to obtain reduced order shaft models and the
accuracy of these reduced order modal models in SSR predictions is
ascertained.
The determination of mode parameters from generator transient response
waveforms is investigated. A continuing problem in this field is the
separation of damping values obtained from measurements on a synchronized
generator, into their mechanical and electrical components. A method is
proposed in this thesis which uses eigenvalue scanning techniques together
with FFT analysis to achieve this separation.
The SSR stability of, and the torsional interaction between two adjacent
generators at a power station is studied. The analysis covers identical
generators, nominally identical generators with small differences between
their mode parameters and different generators with a coincident torsional
mode. In addition, the torsional interaction between generators at
different power stations which are remote from each other is investigated.
This entire analysis is greatly assisted by modelling the turbogenerator
shafts in modal form.
Finally the damping of SSR oscillations in two non-identical adjacent
turbogenerators with a single controlled shunt reactor, which uses the sum
of the generator speed signals as an input to the controller, is
investigated.
Description
Thesis (Ph.D.)-University of Natal, Durban, 1987.
Keywords
Turbogenerators., Turbogenerators--Mathematical models., Subsynchronous resonance (electrical engineering)., Electric power transmission., Theses--Electrical engineering.