Resumo:
This work presents a methodology for prioritization, from a voltage stability point of
view, of future reinforcements detected in the system planning, whether transmission,
transformation and/or reactive compensation projects. The methodology is based on the
evaluation of the behavior of PV and QV curves of the buses of the electric system under
study.
The performance of the power system of interest is analyzed for a base case loading
(1 pu), as well as a loading corresponding to an operating point close to the bifurcation or
instabilibility of the system, evaluating the impact of the reinforcement projects by the
variation they produce in the system voltage stability margins.
The critical region or buses of the system were identified by the higher norm of the
components of the tangent (TV).
Three power systems were used to performe the simulations. Two cases correspond to
academic system (IEEE 14 and 30 bus systems respectively), and a third one
corresponding to a real case (Paraguayan power system, ANDE Subsystem I, comprised
of approximately 225 buses and four voltage levels).
For each system selected, the active power margin is determined from the system PV
curve (AM), as well as the reactive margin of the system buses based on QV curves
(RM).
A computer program has been develop in order to obtain information related to the PV
and QV curves (AM, RM, indices, plots, charts, etc.). It allows to draw the curves for a
specific bus, or for all the buses of the electrical system.
Some interesting features were observed, both in the simulations of the academic
systems, and in the simulations of the real system selected.
Two analyzes were made regarding the behavior of the QV curves:
1. Performance of the QV curves in all buses of the system for various points of the
PV curve, considering the base case that includes all the planned reinforcements
that must be prioritized.
2. Performance of the QV curves in all buses of the system for the same points of the
PV curve, above described, but with the contingency of a selected reinforcement at
a time.
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In this way, the priorization of the reinforcement projects is defined based on comparison
of these two situations.
For the academic cases, the simulations have been processed for all the system buses,
while for the real system case; the simulations were processed by voltage level classes.
The conclusions obtained are presented and discussed within the work.
