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.