Testing of Phasor Measurement Units as per IEC/IEEE Standards - The Whats and the Hows?

Abstract

Synchrophasors are phasor data that are captured in a synchronized manner with the help of a reference time signal. This task of capturing the synchrophasor data is performed by Phasor Measurement Units (PMUs). PMUs also capture frequency and ROCOF measurements using input voltage and current signals with the help of a reference time signal for time stamping the measured data. Reference time signal is obtained by high accuracy source such as a GPS receiver for example. PMUs are considered highly significant to a power system network since they capture and share time stamped synchrophasor data with multiple devices in real-time. PMUs are used for applications such as Wide-area protection schemes, disturbance analysis, power system health monitoring, etc. In 2018, a new standard was developed for synchrophasor measurement in power systems jointly by IEC and IEEE which is IEC/IEEE 60255-118-1. This standard also includes the accuracy requirements to evaluate the synchrophasor, frequency and ROCOF measurements. Another IEC standard 60255–181 which was published in 2019 sheds light on test methods to validate the frequency protection as well as accuracy requirements for the test results. In this paper, we explore aspects of PMU validation using different tests that need to be performed, different test methods, synchronization methods and accuracy requirements with respect to both the above-mentioned standards. Test results are analyzed and presented in relation to the accuracy requirements.