Resumo:
This thesis discusses the problem of stability in power systems. Some
aspects related to power systems dynamics are brie y described, including
appendices associated with electric machines theory and numerical methods.
The bifurcation theory is also mentioned, since it plays an important role
on the operating critical points identi cation. The model employed enables
one to identify saddle-node and Hopf bifurcations.
A computational program aiming the transient and long term stability
is developed. The presented methodology captures the transient trajectory,
migrating to long term period when the transient is over.
The methodology developed allows one to take control actions to avoid
voltage collapse, such that tap blocking, AVR set points adjustments and
load shedding. For each control action, a particular strategy is proposed,
and the results obtained are promising.
Finally, theoretical aspects are also discussed. The combination of the
transient and long term methodologies into a uni ed approach is very im-
portant. Studies devoted to sensitivity of the dynamic variables and to the
critical eigenvalues identi cation are also addressed.
