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Setor Elétrico
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Entry · Operation

ONS: National Electric System Operator

Who coordinates and controls the operation of energy generation and transmission?

● checked against the primary source on Oct 9, 2026Source: Presidency of the Republic and ONS

Acronyms: ANEEL, Brazilian Electricity Regulatory Agency.

In one sentence

Private non-profit legal entity, overseen and regulated by ANEEL, that coordinates and controls the operation of electricity generation and transmission in the National Interconnected System (SIN) and, since May 1, 2017, performs load forecasting and operation planning for isolated systems.

Real example

Hourly peak of the SIN load in the day

98,741 MWavg at 19:00Nature of the data: Observed

Sep 28, 2026 · SIN

Source: ONS, Curva de Carga Horária. Reference up to Sep 28, 2026. Captured on Sep 30, 2026.

An operating figure that the ONS measures and publishes: the hour of highest SIN load in the day, read from the hourly load curve.

See in the panel: Load: hourly profile

Observed: Value published directly by the official or primary source.

Why it matters

The law lists among the duties of the ONS the planning and scheduling of operation and the centralized dispatch of generation, as well as proposing transmission operation rules, which ANEEL approves. ONS open datasets are the source of reservoir, load, generation and interchange figures in the observatory.

Not to be confused with

  • CCEE (Electric Energy Trading Chamber)

    The ONS coordinates and controls the operation of SIN generation and transmission; the CCEE has the purpose of enabling the trading of electricity. Operating the system is not trading the energy, and the two entities maintain an operating agreement with each other.

  • ANEEL (Brazilian Electricity Regulatory Agency)

    ANEEL regulates and oversees the power sector; the ONS operates the interconnected system and is overseen and regulated by it. The ONS proposes the transmission operation rules, and ANEEL is the one that approves them.

  • EPE (Energy Research Office)

    The EPE provides studies and research services that support energy sector planning, among them the expansion plans for generation and transmission; the ONS coordinates and controls the operation of the interconnected system and plans that operation. Planning the expansion of the sector and planning the operation of the system are different tasks.

What cannot be concluded

  • The ONS bylaws and the Grid Procedures, which detail how operation is performed, were not read for this entry.
  • The law's list of duties begins with “Sem prejuízo de outras funções que lhe forem atribuídas pelo Poder Concedente” (without prejudice to other functions assigned to it by the granting authority): it does not exhaust what the ONS does.

Related entries

See in the panel

Official source

  • Presidency of the RepublicLaw No. 9.648 of May 27, 1998, art. 13 (consolidated text published by Planalto, read on Oct 9, 2026) 

    In other words: the law says that the coordination and control of the operation of SIN generation and transmission, and load forecasting and operation planning of the Isolated System, are performed by the ONS, a private non-profit legal entity overseen and regulated by ANEEL. Among its duties are scheduling operation and dispatching generation centrally and proposing to ANEEL rules for transmission operation; since May 1, 2017, also load forecasting and operation planning of isolated systems.

    Literal excerpt from the document
    Portuguese only“Art. 13. As atividades de coordenação e controle da operação da geração e da transmissão de energia elétrica integrantes do Sistema Interligado Nacional (SIN) e as atividades de previsão de carga e planejamento da operação do Sistema Isolado (Sisol) serão executadas, mediante autorização do poder concedente, pelo Operador Nacional do Sistema Elétrico (ONS), pessoa jurídica de direito privado, sem fins lucrativos, fiscalizada e regulada pela Aneel [...] Sem prejuízo de outras funções que lhe forem atribuídas pelo Poder Concedente, constituirão atribuições do ONS: [...] a) o planejamento e a programação da operação e o despacho centralizado da geração, com vistas a otimização dos sistemas eletroenergéticos interligados; [...] f) propor regras para a operação das instalações de transmissão da rede básica do SIN, a serem aprovadas pela ANEEL. [...] g) a partir de 1º de maio de 2017, a previsão de carga e o planejamento da operação do Sisol.”

  • ONSONS, institutional page “O que é ONS” (page without publication date, read on Oct 9, 2026) 

    In other words: the ONS itself presents itself as the body that coordinates and controls the operation of SIN generation and transmission facilities and plans the operation of isolated systems, under ANEEL oversight and regulation.

    Literal excerpt from the document
    Portuguese only“O Operador Nacional do Sistema Elétrico (ONS) é o órgão responsável pela coordenação e controle da operação das instalações de geração e transmissão de energia elétrica no Sistema Interligado Nacional (SIN) e pelo planejamento da operação dos sistemas isolados do país, sob a fiscalização e regulação da Agência Nacional de Energia Elétrica (Aneel).”

  • Presidency of the RepublicDecree No. 5.081 of May 14, 2004, art. 3, § 1 (consolidated text published by Planalto, read on Oct 9, 2026) 

    In other words: to perform its duties, the ONS must maintain an operating agreement with the CCEE, to define how the two entities relate technically, and with the EPE, to provide inputs for power sector planning.

    Literal excerpt from the document
    Portuguese only“§ 1º Para a realização das atribuições tratadas no caput, o ONS deverá, entre outros: I - manter acordo operacional com a Câmara de Comercialização de Energia Elétrica - CCEE de que trata o art. 4º da Lei nº 10.848, de 2004, visando ao estabelecimento das condições de relacionamento técnico-operacional entre as duas entidades, para o desenvolvimento das atividades que lhes competirem, naquilo que for cabível; II - manter acordo operacional com a Empresa de Pesquisa Energética - EPE, com a finalidade de prover elementos e subsídios necessários ao desenvolvimento das atividades relativas ao planejamento do setor elétrico, nos termos da Lei nº 10.847, de 15 de março de 2004.”

Documents accessed and text checked on Oct 9, 2026.

Check details

What the check found in the source
  • The ONS page has no publication or update date; it counts as read on Oct 9, 2026. The law and the decree are the consolidated texts from Planalto read on the same date.
  • The versioned capture of each document, with the sha256 of the original and of the text, is in the manifest of the Learn documents folder of Oct 9, 2026.