Executive Summary
The electric grid is evolving into a highly digital, interconnected system. Operational Technology (OT) protocols are at the heart of this transformation, enabling real-time monitoring, automation, and integration with IT systems. This page highlights trending protocols in Grid OT and provides best practices for secure and efficient deployment.
1. Trending Protocols in Grid OT
IEC 61850 – Digital Substation Backbone
IEC 61850 is an international standard for communication in electrical substations, designed to enable interoperability among Intelligent Electronic Devices (IEDs). It uses object-oriented data models and services for protection, control, and monitoring. Key components include GOOSE for high-speed event messaging, Sampled Values for precise measurement exchange, and MMS for SCADA integration. Recent advancements like IEC 61850-8-3 introduce JSON over WebSockets, bridging OT with IT systems for cloud analytics and DER integration. Its benefits include reduced wiring, faster fault response, and standardized engineering, making it the backbone of modern digital substations.
DNP3 – SCADA Workhorse
DNP3 (Distributed Network Protocol) is a widely used communication standard in electric power systems for Supervisory Control and Data Acquisition (SCADA). It was designed for reliable, event-driven communication over long distances and low-bandwidth networks, making it ideal for remote substations and field devices. DNP3 supports time-stamped data, unsolicited reporting, and efficient bandwidth usage. Modern implementations include Secure Authentication (SA) and TLS encryption to protect against cyber threats. Its robustness and interoperability with legacy systems make DNP3 a critical protocol for grid monitoring, control, and automation, especially in transmission and distribution networks.
IEC 60870-5-104 – European SCADA Standard
IEC 60870-5-104 is a widely adopted protocol for Supervisory Control and Data Acquisition (SCADA) in European power systems. It extends the IEC 60870-5 series by using TCP/IP for wide-area communication, enabling efficient and reliable data exchange between control centers and substations. IEC 104 supports remote monitoring, control commands, and event reporting over IP networks. Recent enhancements through IEC TS 60870-5-7 and IEC 62351 introduce TLS encryption, authentication, and role-based access control to strengthen cybersecurity. Its simplicity, interoperability, and ability to operate over standard Ethernet make IEC 104 a key protocol for modern grid automation.
IEEE C37.118 – Synchrophasor Data
IEEE C37.118 is the standard for measuring and transmitting synchrophasor data from Phasor Measurement Units (PMUs) in power systems. It defines two main parts: C37.118.1 for measurement accuracy and C37.118.2 for data communication. Synchrophasors provide real-time voltage and current phase angle information, enabling wide-area monitoring, grid stability analysis, and dynamic control. The protocol supports high-speed streaming with precise time synchronization using GPS or IEEE 1588. Security is not inherent, so utilities typically implement VPNs, TLS encryption, and access controls to protect data integrity and confidentiality. This standard is critical for modern grid reliability and situational awareness.
MQTT & OPC UA – IT/OT Convergence
MQTT (Message Queuing Telemetry Transport) and OPC UA (Open Platform Communications Unified Architecture) are key protocols bridging IT and OT in modern grid systems. MQTT is a lightweight publish/subscribe protocol ideal for transmitting telemetry from distributed energy resources (DERs) and edge devices to cloud platforms. It supports efficient, low-bandwidth communication and scales easily for IoT applications. OPC UA, on the other hand, provides rich semantic data modeling, secure communication, and interoperability between industrial systems and enterprise applications. Together, they enable real-time data exchange, analytics, and integration with IT systems, forming the backbone of digital grid transformation.
Private 5G – Future of Grid Connectivity
Private 5G is emerging as a transformative technology for electric grid operations, offering ultra-reliable, low-latency wireless communication tailored for critical infrastructure. Unlike public networks, private 5G provides dedicated spectrum, secure SIM-based authentication, and network slicing to prioritize grid traffic. It enables high-speed connectivity for substation automation, real-time DER control, and mobile workforce applications such as AR-assisted maintenance and drone inspections. With latency under 10 ms and near-zero jitter, private 5G supports mission-critical functions like fault isolation and protection signaling. Its scalability and security make it a cornerstone for modernizing grid OT networks and enabling Industry 4.0 in utilities.
2. Best Practices for Protocol Deployment
A layered approach ensures that protocols are used where they fit best:
Field Layer: IEC 61850 GOOSE/SV for protection
This layer is closest to physical assets like transformers and circuit breakers. IEC 61850 GOOSE messages provide ultra-fast peer-to-peer communication for protection and control, while Sampled Values transmit precise measurement data. Keeping these at the field layer ensures deterministic performance and safety.Control Layer: MMS, DNP3, IEC 104 for SCADA
This layer handles supervisory control and monitoring. MMS (part of IEC 61850) is used for device management, while DNP3 and IEC 104 are reliable for wide-area SCADA communication. They aggregate data from field devices and send commands from control centers.Enterprise Layer: OPC UA and MQTT for analytics and IT integration
At the enterprise level, data is contextualized and integrated with IT systems. OPC UA provides rich semantic modeling and secure communication, while MQTT enables lightweight, scalable telemetry for cloud and analytics platforms.
Conclusion
The modernization of grid OT relies on adopting advanced, secure, interoperable protocols protocols like IEC 61850, DNP3, IEC 104, IEEE C37.118, MQTT, OPC UA, and private 5G. These technologies enable real-time monitoring, automation, and IT/OT integration while ensuring interoperability and security. Implementing layered architecture, robust cybersecurity frameworks, and data governance practices is essential for resilience, compliance, and operational efficiency, paving the way for a smarter, more reliable, and future-ready electric grid.