Resumo:
Subsynchronous resonance is a phenomenon inherent in electrical power systems
which presents thermal power plants connected to series compensated transmission
networks. This phenomenon is characterized by energy exchange between turbine generator shafts and the transmission system at frequencies below the synchronous
one, i.e., at subsynchronous frequencies. Therefore, to capture this phenomenon it is
necessary to model generators, turbine-generator mechanical shafts and electrical
network, so that the network frequencies can be reflected on mechanical shafts
through the electromagnetic torques induced in the generators and vice-versa. This
effect becomes critical when one of the network natural frequencies is close, or
equal, to one of the torsional modes of the shafts. Under these conditions, the system
may come to be self-excited or even unstable.
This document intends to present, in a comprehensive way, alternative forms to
interpret the subsynchronous resonance and its build-up mechanisms. It also
exposes models for the basic components of the electrical power systems for
subsynchronous resonance studies, among them synchronous generators, electrical
network and mechanical shafts. The eigenanalysis are employed as the main tool for
the stability analysis in this document, which are based in the linearised state space
matrix of the whole system.
An index designed to identify Hopf bifurcations in electrical power systems is also
presented, aiming a quick visualization of the system critical points, when a specific
control parameter is varied.
In the end of the dissertation, some numerical examples are presented, providing one
to reproduce them totally.
