Resumo:
According to the new energy market regulation, the electric system companies have been
leading to become more and more competitive. However, the consumption of electric
energy has increased along the years, and the investments in the electric system have not
increased in the same proportion. It makes the electrical grid operation close to its
maximum capacity.
Energy production through renewable sources such as wind and solar contributes to
sustainable development and minimizes energy deficit issues. However, intermittent
sources, due to low synchronous inertia, make a small contribution to the electrical system
in the event of major disturbances.
In this scenario, hydrogenerators are still the most reliable sources and play a fundamental
role in the electrical system stability. Additionally, hydrogenerators with variable speed can
significantly contribute to system operation, reservoir optimization and minimization of
environmental impacts. Furthermore, through technological development, the reduction
costs of inverters and the expansion of HVDC grids, the application of variable speed
hydrogenerators is completely viable.
The objective of this work is to propose a study of the efficiency of a large hydrogenator
with variable speed operation. The aim is to map the efficiency of the machine for different
load and rotational speed conditions, analyzing the behavior of the machine regarding to
distinct types of losses. The operational limits of the salient pole synchronous machine for
different rotational speed condition will also be analyzed.
The analyzes and simulations will be applied to a large hydrogenator and as a contribution
a three-dimensional capability chart will be proposed with speed variation in the third axis
and the respective analyzes of the influence of reactance, voltage, armature current and
losses in the operational limits of the machine.
