SEL Synchrophasors and PMU
Key Takeaway
What synchrophasors and PMUs are, how SEL relays with PMU capability work, IEEE C37.118 data streaming, and wide-area monitoring applications.
Quick Answer
A synchrophasor is a GPS-time-stamped measurement of voltage or current magnitude and phase angle. SEL relays with PMU capability (SEL-421, SEL-451, SEL-300G) stream phasor data via IEEE C37.118 to Phasor Data Concentrators for wide-area grid monitoring and situational awareness.
What Is a PMU?
A Phasor Measurement Unit measures voltage and current phasors synchronized to GPS time (1 microsecond accuracy). Because all PMUs share the same time reference, measurements from different substations can be directly compared in real time.
C37.118
IEEE C37.118 defines the data format and streaming protocol for synchrophasor data — phasor magnitude and angle, frequency, ROCOF, at 10-120 frames per second over TCP or UDP.
Applications
- Oscillation detection and inter-area mode observation
- Post-disturbance replay and analysis
- State estimation improvement
- Wide-area situational awareness for grid operators
Frequently Asked Questions
A GPS-time-stamped phasor measurement (magnitude + angle) enabling real-time comparison of grid conditions across wide areas — impossible with conventional SCADA.
The standard defining data format and streaming protocol for synchrophasor data from PMUs to data concentrators.