Resumo:
Over the past decade, electric power systems have been restructured based on different models
to introduce competition among market participants. Transmission open access for suppliers
and customers is one of the most prevailing unbundling services. Usually, a connection
tariff is established based on different market factors including the actual usage of the transmission
network.
In Brazil, most of vertically integrated companies owned by the federal and state governments
were unbundled, and new transmission companies are being created. These companies make
their assets available to the independent system operator, designated as Operador Nacional do
Sistema Elétrico (ONS). One of the main objectives of ONS is to manage transmission services,
over a certain voltage level, to ensure nondiscriminatory access to the grid. All transmission
users, including regional distribution companies, pay wheeling transmission charges
at each delivery or connection point with the major Brazilian network administrated by ONS.
This work presents a methodology for determining the optimal amount of transmission system
usage that must be contracted by a regional distribution company, at each connection point. In
the proposed approach, the maximum flow at each connection is represented as a random
variable, in order to obtain the distribution probability of the transmission charges as a function
of the contracted amount. Besides providing the optimal amounts to be contracted, the
proposed probabilistic methodology allows quantifying the risks of violation of each contract
and estimating possible penalties. All methodology development steps are described and illustrated
through numerical examples. An application to a typical Brazilian regional distribution
company, called Ampla, is also discussed.
