The connection of new battery energy storage systems to the Brazilian electricity grid relies on a revised version of the remaining capacity quantities of the SIN (National Interconnected System).
Released this week, the update corrects information related to the Milagres substation and is part of the preparation for the 2026 LRCAPs (Capacity Reserve Auctions) focused on storage, scheduled for December 2nd and 4th.
The revision of Technical Note NT-ONS DPL 0095/2026 incorporates a correction made by the responsible transmission company regarding the physical availability for new connections on the 69 kV busbar of the Milagres substation.
It also corrects the information regarding the short-circuit breaking capacity of one of the circuit breakers in the same substation, at the 230 kV voltage level.
Despite the changes, the document preserves the values of the margins of the dams that are candidates for connection of new projects. According to the ONS (National System Operator), the new version also includes general textual adjustments, without changes to these quantities.
Remaining capacity
This technical note compiles information on the remaining capacity available in the SIN (National Interconnected System) for connecting new storage systems in different types of electrical installations.
The survey covers the Basic Network, Other Transmission Facilities (DIT), and Facilities of Exclusive Interest to Generation Plants for Shared Connection (ICG).
The scope also includes indirect connections made through distribution systems. The document therefore contemplates different alternatives for accessing electrical infrastructure for projects intending to participate in the energy storage auctions scheduled for 2026.
The publication is linked to the rules established in Ordinances No. 444/GM/MME/2016 and No. 136/GM/MME/2026. The publication of the revision also complies with the procedure foreseen in paragraph 5 of article 3 of Ordinance No. 444.
Technical requirements have also been updated.
Prior to the revision of capacity quantities, EPE and ONS had released, on October 22, an update to the technical note that establishes the minimum technical requirements for the connection of battery storage systems.
The document is identified as NT-ONS DPL 0111/2025 / EPE-DEE-NT-095/2025 and is related to the guidelines of MME Normative Ordinance No. 136/2026. The revision clarifies points from the previous version and improves the wording of requirements applicable to projects.
Among the changes is the possibility for applicants to submit mathematical models of electromechanical transients in the formats of the ORGANON or ANATEM programs, according to the option chosen by the applicant. The note addresses requirements that must be observed in the solutions submitted for the LRCAPs 2026.
The content covers aspects necessary for connecting projects to transmission facilities, including supervision, control, protection, and telecommunications.
Converters and system operation
The technical document also establishes parameters for the electronic converters associated with the batteries. Among the functionalities covered are voltage and frequency control capabilities and operation according to the grid forming strategy.
This strategy relates to the ability of a piece of equipment to contribute to the formation and maintenance of voltage and frequency references in the grid. In the context of this note, grid forming operation appears among the technical functionalities considered in the requirements applicable to storage systems.
Updating the minimum requirements and revising the remaining capacity quantities therefore address distinct aspects of auction preparation. While the former establishes technical parameters for the solutions proposed by the participants, the latter gathers information on the possibilities of connecting the new systems to the electrical infrastructure.
- The NT (Technical Note) regarding the revision of quantities is available here. link
- The technical note (NT) regarding the minimum requirements is available by clicking [here]. here.
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