IEEE Power & Energy Magazine - November/December 2016 - 42

table 1. States that compose each
geoelectrical region in Brazil.
Region

States

South

Rio Grande do Sul, Santa Catarina, and
Paraná

Southeast

Espírito Santo, Rio de Janeiro, Minas Gerais,
and São Paulo

Midwest

Goiás, Distrito Federal, Mato Grosso, Mato
Grosso do Sul, Acre, and Rondônia

North

Pará, Tocantins, Amapá, Amazonas, and
Roraima

Northeast

Maranhão, Piauí, Ceará, Rio Grande do
Norte, Paraíba, Pernambuco, Alagoas,
Sergipe, and Bahia

generation, with a consequent increase in greenhouse gas
emissions. However, Brazil remains an international environmental leader, with the majority of its electricity needs
supplied by renewable generation and a low level of emissions from its thermal generation.
Currently, the Brazilian transmission grid includes
several voltage levels: 138, 230, 345, 440, 500, and
765 kV (ac) and also !600 kV (dc). Table 3 shows the
total length of transmission lines installed at 230-kV level
and above. The 500-kV voltage level is widely used to
interconnect the regional subsystems, such as north to

northeast, south to southeast, north to southeast, and
southeast to northeast.
This combination of large remote generation sources, large
seasonal impacts on transfers, and long transmission lines has
resulted in some experience with blackouts. The consequences
of blackouts in economical, social, and political terms are
intrinsically linked to their frequency of occurrence and duration. The frequency of blackouts is addressed by reliability
improvements while duration is, of course, related to the total
time for the load restoration. To obtain concrete results on the
minimization of restoration times, several actions involving
distinct time frames have been undertaken in the Brazilian
Interconnected Power System (BIPS) to improve the system
restoration process.
In recent years there were two major incidents in the
BIPS. A brief description of the causes and consequences
of each of these two disturbances and the challenges faced
by the Brazilian independent system operator (ISO), the
Operador Nacional do Sistema Elétrico (ONS), follows.

Blackout of 10 November 2009

The initiating disturbance occurred on the transmission
system that carries power from the large Itaipu hydroelectric station in southwestern Brazil to the load centers of
São Paulo and Rio de Janeiro. The Itaipu hydroelectric station is the second largest power station in the world with
20 700-MW units, for a total generation of 14,000 MW.
By international agreement, the Itaipu power station was
constructed using both 50- and
60-Hz units. Ten generating units
operate at 60 Hz and connect to
the Brazilian 765-kV network.
Roraima
Amapá
The other ten generating units
operate at 50 Hz and connect to
the Itaipu HVdc lines that carry
Amazonas
Ceará
the power to the load centers in
Pará
Maranhão
Rio Grande do Norte
the southeast of Brazil. These
Paraíba
units may also supply power to
Piauí
Pernambuco
Acre
the 50-Hz Paraguay system.
Alagoas
Tocantins
Rondônia
The disturbance started with
Sergipe
Mato Grosso
Bahia
a phase-to-ground fault (phase B)
DF
on circuit 1 (C1) of the 765-kV
Goiás
Minas
Ivaiporã-Itaberá transmission
Gerais
Mato Grosso
line, close to the Itaberá substaEspírito Santo
do Sul
Legend:
tion (Figure 4). The faulted circuit
São Paulo
Rio de Janeiro
North Region
was tripped in 48 ms by operaNortheast Region
Paraná
tion of the distance protection.
Midwest Region
At 13.5 ms after the first event,
Santa Catarina
Southeast Region
Rio
a second short circuit (phase A)
Grande
South Region
do Sul
occurred on circuit 2 (C2) of the
same line, also close to the Itaberá
substation. This second short circuit was cleared by trip of circuit
figure 1. The geoelectrical regions in Brazil. DF: Distrito Federal. (Source: 2015
2
in 48.8 ms by operation of the
Statistical Yearbook of Electricity; the 2014 baseline year is available at http://
directional
overcurrent protection.
www.epe.gov.br.)
42

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november/december 2016

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