Review of PMU algorithms suitable for real-time operation with digital sampled value data

Phasor Measurement Unit (PMU) instruments are continuously evolving to reflect the needs of electrical grids for enhanced and more accurate monitoring of the AC signal parameters, and to contribute towards optimization of real-time control tasks. In turn, enhanced monitoring can contribute to a more stable and reliable power supply. PMU standards are also being updated to reflect the latest performance requirements PMUs and new technological developments. As described in standard IEC/IEEE 60255-118-1, a PMU may receive streams of timestamped digital samples using the IEC 61850-9-2 Sample Values (SV) protocol, instead of traditional analog signals. This means that the signal conditioning and sampling parts can be located at a different location from the computational unit. This approach requires remote processing, so additional time delay is introduced that affects the reporting latency of the PMU. Therefore, not all the PMU algorithms presented in the literature will be valid candidates to operate with SV data and at the same time comply with reporting latency requirements. To address this issue, the paper presents a literature review of PMU algorithms, to identify algorithms which are suitable for real-time operation with the SV data protocol. Among many proposed PMU algorithms, only a few of them can estimate synchrophasor, frequency, and rate of change of frequency (ROCOF) on a sample per sample basis. Recommendations on selecting PMU algorithms for hardware implementation that complies with SV data has been also provided.