IEC/IEEE 60255-118-1:2018 PDF

Overview

IEC/IEEE 60255-118-1:2018 - Measuring relays and protection equipment, Part 118-1: Synchrophasor for power systems - Measurements - is the international standard that defines how synchronized phasor measurements (synchrophasors), frequency, and rate of change of frequency (ROCOF) are specified, measured, time-tagged, evaluated and reported for power systems. Published jointly by IEC and IEEE in 2018, this standard describes the Phasor Measurement Unit (PMU) as either a stand‑alone physical device or a functional unit within other equipment. It does not prescribe hardware, software designs, or a specific algorithm for computing phasors, frequency or ROCOF.

Key Topics & Requirements

• Measurand definitions: formal definitions for synchrophasor phase angle, synchrophasor magnitude, frequency and ROCOF to ensure consistent interpretation.
• Time synchronization and time tagging: requirements for accurate timestamping of measurements to support system-wide alignment.
• PMU definition and reporting: required input/output quantities, reporting rates, reporting times and message contents for PMUs.
• Measurement evaluation metrics: methods for assessing accuracy including steady-state and dynamic performance (e.g., Total Vector Error (TVE), measurement latency, response time, overshoot/undershoot).
• Performance classes and compliance: classification of PMU performance (referenced in normative and informative annexes) and procedures for compliance verification and testing under static and dynamic conditions.
• Dynamic testing and bandwidth: tests for frequency ramps, step changes in phase/magnitude, measurement bandwidth considerations and ROCOF behavior.
• Documentation and testing guidance: recommended test subsets, reference signal processing models and examples to support evaluation.

Practical Applications

• Ensures consistent synchrophasor measurements across devices and vendors for:
  • Wide-area monitoring, protection and control (WAMPAC)
  • Grid stability and disturbance analysis
  • Real-time state estimation and oscillation detection
  • Event recording and post‑fault analysis
• Useful for utilities, transmission system operators, protection & control engineers, PMU manufacturers, testing laboratories, and researchers implementing or validating synchrophasor systems.

Who Should Use This Standard

• Grid operators seeking reliable time‑synchronized measurements for situational awareness.
• PMU and relay manufacturers designing devices to meet accepted measurement and reporting criteria.
• Test labs and consultants performing compliance testing, performance benchmarking or certification.
• Standards developers and researchers aligning new tools or algorithms with accepted measurement definitions.

Related Standards (if applicable)

• Companion documents and annexes within IEC/IEEE 60255-118-1 provide testing examples, extended accuracy and bandwidth classes, and reference models for PMU evaluation. For implementation of communications and data formats, consult related synchrophasor data transport standards (e.g., IEEE C37.118 family and IEC standards on time synchronization and sampled values).

Keywords: IEC/IEEE 60255-118-1:2018, synchrophasor, PMU, phasor measurement unit, frequency, ROCOF, time synchronization, TVE, PMU testing, measurement compliance.