Probabilistic assessment of PMU integrity for planning of periodic maintenance and testing

The standard C37.118.1a-2014 has specified the permissible limits for PMU measurement errors under various static and dynamic test conditions. This paper proposes a statistical measure to evaluate the probability of PMU performance degradation with regards to certain standard requirements. The proposed approach is implemented using a field calibrator system for phasor measurement units (PMUs). Assessment of the test results provides an additional insight about: (a) whether the expected functionality and integrity of the PMUs is maintained over time; (b) which synchrophasor standard requirements are most vulnerable for a given device over time; (c) when the maintenance schedule needs to be expedited on certain PMUs based on observed performance degradation probabilities; and (d) the risks of loss of trustworthiness of various end-use synchrophasor-based applications. The applicability of the suggested technique is verified through implementation on several PMUs in a calibration and testing set-up.