Resumo:
There are three forms of a hidroelectric system to self-protect by hydrological and
load risks: the first one is the water storage; the second is the complementarities
thermal; the third is the increase of the elasticity of the demand, with strong signal of
generation price. Historically, the use of reservoirs was the way of protecting of the
uncertainties. In this phase the concepts of firm energy and critical period had
appeared, and the economic criterion had minor value than the technical criteria. With
the entrance of some thermal generation, it was transferred to operate the reservoir,
according to criterion of the rule curve. The great advantage of the rule curve is the
transparency. Moreover, it has a certain isonomy between the reservoirs, not allowing
that one if finds emptied total, while the other meets full or almost full. All the reservoirs
have that to be in the same band.
With the evolution of the computational models, Brazil abandoned the previously
criterion, evolving for one with strong economic bias, that if based on the costs of the
thermal generation and the deficit, beyond the expansion of the generating park. The
sophistication of the models demanded a simplification of the physical reality. Thus,
this second phase of the electro-energy operation in the country if did not worry about
the aspects to maximize the hydroelectric generation (that it is the same that to
minimize the thermal generation).
The 2001 crisis presented the fragility of the sector, imposing the creation of the
aversion risk curve, that is a rule curve; when the storage in the reservoirs is less than
established level, determines the forwarding of all the thermal capacity. Today, the
sector indicates the necessity of other curves of aversion that determines the
forwarding of parts of thermal the generating grid, before if transgressing to the current
aversion curve. This nothing more is that the rescue of the rule curve, only that still
applied to the reservoir equivalent.
The objective of this paper is to develop a strength and plain method for the
hydroelectric plants reservoirs operation. It is understood that strength way is the
capacity for the operation without major economic losses under unexpected conditions.
The plain way means the capacity of for reproducing or projecting the operation results
with no major differences, is that to say, forecasting and repeatability.