Brazil's electricity transmission grid is expanding and evolving, becoming increasingly digital over time as a result of improved operational practices and enhanced grid performance. The sector is governed by the national electricity agency, Agência Nacional de Energia Elétrica (ANEEL), and operated by the national system operator, Operador Nacional do Sistema (ONS). The ONS establishes network proceedings that define the rules all assets belonging to the operational network must follow — specifically those with voltages equal to or above 230 kV, referred to as the “basic grid.” ANEEL provides regulations and oversees the auction process for expanding the transmission grid after the energy research office, Empresa de Pesquisa Energética (EPE), conducts studies to identify where expansion is needed.
The winning bidder is determined by the lowest proposed annual allowed revenue, or receita annual permitida (RAP). The concession period for a section of the transmission grid is 30 years, exceeding the expected lifespan of electronic equipment. Consequently, the successful contractor must replace electronic components at least once during the concession period.
Every new transmission line must include an optical ground wire cable (OPGW) as its grounding cable. Introduced in the late 1980s, OPGW cables are widely used in Brazil because of their superior reliability compared to other types of fiber cables, including buried ones. They form the backbone of the country’s electric grid's telecommunications media.
If the contractor opts to operate assets remotely through a remote control center, it must comply with the telecommunications requirements outlined in the network proceedings. Tele-assistance encompasses remote supervision and control, voice communication and operational video surveillance, enabling substations to be operated remotely. Substations must have two data and voice channels on different routes, with a combined annual availability of 99.98% — classified as class A channels. The overall system, including channels, supervision and controls, must achieve an annual availability of 99.95%. Operational cameras must verify the disconnector switch status (opened, closed or intermediate) after a maneuver to prevent reporting errors, manual confirmation by crews, asset damage and accidents.
Transmission Utilities
All transmission lines in the basic grid must have two dedicated tele-protection channels using different communication media and total redundancy, including end-to-end electronic systems. For example, one channel may use an OPGW cable, while another might use carrier waves on high-voltage lines. However, carrier waves cannot support differential tele-protection when required, creating challenges for contractors needing a second fiber path.
In cases where high-voltage lines are sectioned, contractors may need to share or exchange infrastructure with others, adhering to the network proceedings and criteria established by the line owner. These negotiations can be complex, especially when mutual interests in channel exchanges are lacking or when renting unused fibers or communication channels is necessary. In such cases, the utility owning the desired channel must hold a multimedia license from the national telecommunications agency, Agência Nacional de Telecomunicações (Anatel).
Oscillography is another mandatory service. These devices operate independently of protection relays, monitoring voltage and current signals to analyze faults and locate their origins. The recordings are transmitted via specific channels to the remote control center for fault investigation by the protection team. Transmission utilities also use traveling-wave technology to improve fault location precision, which requires telecommunications channels to exchange information between the line's terminals.
Utilities' remote control centers must share operational equipment status and alarms with the ONS via two redundant links in different regions of the country (for example, Florianópolis and Rio de Janeiro). For enhanced frequency synchronization and disturbance diagnostics, assets operating at 500 kV or higher must include phasor measurement units (PMUs) on the line terminals and send the data to two ONS sites in Brasília and Rio de Janeiro with a maximum delay of 500 msec.
In addition to complying with these regulatory requirements, utilities deploy corporate services to improve operational quality and security. It is strongly recommended to separate operational and corporate networks by using distinct IP network addresses. Corporate services include voice communication, email, internet access, and enterprise resource planning (ERP) systems, typically delivered through LAN cables or Wi-Fi networks. Maintenance teams favor Wi-Fi for its reliable communication coverage across substation perimeters for both voice and data. However, Wi-Fi signals can extend to unintended areas, creating vulnerabilities intruders could exploit. Voice communications with frontline workers must be recorded for compliance purposes.
Cybersecurity is a critical concern in Brazil's utility sector. It has become a mandatory component of network proceedings for remote control centers and remote substations. Regulations now require firewalls, intrusion detection systems (IDS), security operations centers (SOC), endpoint defense solutions (EDR), access control mechanisms and identity management protocols.
Auxiliary services are designed to power these electronics, and contractors must meet specific requirements at transmission substations. These include having two independent power sources via the tertiary winding of transformers, feeding two independent rectifiers, each with a battery capacity of at least 10 hours as well as a 30% surplus for future expansion. Rectifiers must also be monitored by the control center to detect critical alarms or battery discharges. Additionally, an external generator must serve as a third power source in case of disasters.
Failure to comply with ONS rules can result in penalties ranging from improvement recommendations and fines to mandatory local substation operations, significantly increasing operational costs. Labor laws also mandate all workers, including linemen, have access to communication channels while working on the grid. Utilities often use satellite phones and very high-frequency (VHF) systems for this purpose, with all communications recorded for investigation purposes.
Distribution Utilities
Distribution utilities face similar challenges, particularly in automation, smart metering, and loss management. These challenges also include remote substation operations and tele-protection channels, although the requirements are less stringent than those for transmission utilities. In addition to the telecommunication systems previously mentioned, these utilities also implement, operate and maintain mesh, LTE/4G, 5G and private radio networks with dedicated frequencies exclusively for utility use. Unlike transmission expansion, which occurs through auctions, distribution expansion is driven by strategic investments recognized during each tariff review by ANEEL.
Recent expansions in smart metering projects have reduced the need for manual readings, improved fault detection and enhanced energy quality monitoring.
Recloser automation is another critical issue for distribution utilities. It enables remote control to restore electricity, reducing the distances teams must travel to inspect a line. It also monitors the frequency of reclosures, which often indicate vegetation interference, and remotely manages load disconnection when the network is overloaded, especially during summertime.
Loss management involves comparing energy measured by residential meters with energy delivered by a distribution transformer to identify energy theft in specific areas. ANEEL sets goals for distribution utilities to detect and address such situations.
Smart metering, recloser automation and loss management are entirely dependent on telecommunication services deployed across the grid and managed by utility professionals. Managing these services requires expertise in various protocols, equipment, network architecture, spare parts and employee training.
However, utilities face significant challenges due to the rapid depreciation of equipment and fast-paced evolution of technology. Manufacturers frequently update their product lines, creating issues with equipment reaching end of life and reducing the availability of spare parts. The depreciation rate is regulated by ANEEL's manual on the electricity sector, which requires constant revisions to align with the fast pace of technological advancements. Operation and maintenance of a diverse range of manufacturers and products is another major hurdle. Telecommunications control centers typically feature numerous screens from different manufacturers, reflecting the field's diversity. This situation necessitates more training programs and skilled employees.
Commonly used in remote areas, radio link networks and their repeaters also face challenges. These include increased costs due to vandalism, the need for environmental licensing renewals and team displacement over long distances.
Though robust, OPGW cables are vulnerable to damage from electrical discharges, weather conditions and mechanical stress, which can degrade their optical transmission capacity. Some years ago, Brazilian OPGW cables experienced fiber ruptures caused by insufficient fiber length to accommodate contraction and expansion due to temperature fluctuations. Nonetheless, OPGW cables remain the most reliable telecommunications medium for transmitting digital services and are widely used as the grid backbone.
With a technical lifespan of 40 years, OPGW cables are preferred not only by utilities but also by telecommunications companies because of their superior availability compared to fiber cables attached to poles or buried underground. This preference was addressed in the joint Telecommunications and Energy Agencies Resolution No. 01/1999 and ANEEL Resolution 1,044/2022, which regulate infrastructure sharing between the two sectors, leveraging the unused capacity of utilities to enhance communication services for the public.
Whenever contractors upgrade electronic equipment or replace critical assets like circuit breakers, capacitors or reactor banks, or power transformers, they must adhere to the latest network proceedings, including the electronics involved.
Satellite links play a vital role in expanding the electricity grid, particularly in delivering communications to remote substations. In cases where the primary medium is OPGW cable and a secondary fiber medium is unavailable, satellite links are used to meet tele-assistance requirements. However, without a second fiber medium, teleprotection services are limited by distance zones when high-voltage carrier lines serve as the secondary medium.
Keeping up with Requirements
Despite these challenges, Brazilian transmission and distribution utilities have consistently implemented the required telecommunications solutions. To date, no project has been canceled due to noncompliance with telecommunications requirements in Brazil, although unexpected cost increases are common for contractors that lack construction experience.
Managing assurance contracts, maintenance orders as well as statistics, analyzing failure indicators, handling electronic equipment logistics, monitoring link and service availability, evaluating equipment lifespans, and coordinating replacement and expansion projects are ongoing challenges for telecommunication teams and control centers. Telecommunication equipment is fully depreciated after 15 years under regulatory norms but often lasts up to 20 years. In contrast, advanced technological solutions, such as computer servers and IT hardware and software, typically require upgrades every five years on average.
Large data transmission capacity is crucial for grid digitalization, requiring an evaluation of the most effective media to ensure desired bandwidth, guaranteed availability and long lifespan.
Despite regulatory challenges, the framework is widely regarded as a fair and equitable way to ensure consistency among industry players, whether competing in auctions or upgrading systems.
As grid digitalization accelerates — with more advanced protection and control systems, increased data demands from corporate tools, heightened cybersecurity requirements, real-time asset monitoring, operational video surveillance, substation-to-control center voice communications and mobile communications — greater bandwidth availability will become essential. Consequently, the challenges for telecommunication professionals, manufacturers and regulatory agencies in the electricity sector are expected to increase significantly in the coming years. Proactive measures and close collaboration will be crucial to successfully navigating these challenges, ensuring a reliable, secure and efficient grid for the future.
