Resumo:
Traditionally, Power Systems capacity has been determined by angular stability or
thermal capacity of their elements. But factors like intense load growth, system
expansion, and systems interconnections, through long transmission lines, have caused
problems related to voltage instability and many voltage collapse events have been
verified all over the world.
As the majority of voltage collapse events are related to equipments that have a slow
dynamic behavior, studies of long term voltage control are significantly affected due to
the difficulty of representing these equipments in the process of load and generation
variation in the system.
The automatic and discrete switching of these equipments generate significant impacts
on system voltage control and need to be represented accurately to perform more
precise, and less conservative, load margin calculus than the ones that are traditionally
performed with the majority of static analysis tools available.
The present study used a simulation tool capable of implementing a control logic of
these slow dynamic behavior equipments based on the bus to be controlled and on
suitable voltage control ranges that were established from the experience of operating
the studied system, trying to identify, through comparative studies, the impacts of these
equipments on voltage security analysis. The studies were made under a wide range of
generation dispatches that were applied in some specific areas of the system. It was
verified that representing these slow dynamic behavior equipments using voltage
control range brought significant benefits on load margins of the analyzed system.