Communications & Networking
Modern power systems are cyber-physical systems — the electrical grid depends on a communication infrastructure for monitoring, control, and protection. These notes cover both the foundational communication theory and the specific protocols and architectures used in grid operations.
Core Topics
Communication Theory Fundamentals
Shannon’s theorem, modulation (AM, FM, QAM, OFDM), channel capacity, noise and error correction.
Network Fundamentals
OSI model, TCP/IP stack, Ethernet, switching, routing, VLANs, network security basics.
Grid Communication Protocols
- DNP3 — SCADA communications between control centers and field devices
- IEC 61850 — substation automation, GOOSE messaging, sampled values
- Modbus — legacy industrial protocol, still widely deployed
- IEC 60870-5 — telecontrol protocols for power systems
- IEEE C37.118 — synchrophasor data standard (PMUs)
SCADA & Energy Management Systems
Architecture of SCADA systems, RTUs, IEDs, historians, HMI. Interfaces to EMS and ADMS.
Communication Media for Grid Applications
Fiber optic, power line carrier (PLC), cellular (4G/5G), licensed radio, satellite. Trade-offs in latency, bandwidth, and reliability.
Time Synchronization
GPS-based timing, IEEE 1588 (PTP), IRIG-B. Why precise time matters for protection and synchrophasors.
OT Network Architecture
IT vs. OT network differences. Purdue model, IEC 62443 zones and conduits. Defense in depth.
Key Questions These Notes Answer
- How does IEC 61850 differ from DNP3 and when is each used?
- How does a SCADA system communicate with a field device?
- What communication latency is required for protection vs. monitoring?
- How is GPS timing used in synchrophasor measurements?
- How do OT networks differ from enterprise IT networks?
Prerequisites
- Engineering Foundations
- Programming Foundations — helps with protocol implementation
Connects To
- Power Systems Engineering — EMS, SCADA
- Distribution Power Systems — ADMS, DA
- Distribution System Operator
- Cybersecurity — OT security