Assessment of time synchronization quality in a distributed PMU

Distributed Phasor Measurement Unit (PMU) is a performing solution to measure synchrophasors in an IEC 61850 compliant scenario. The standard IEEE C37.118.2-2011, about data transfer of synchrophasor measurements, requires to give time quality information along with time stamped measurement data. In a distributed PMU, the time quality of the system depends on the capabilities of the Merging Unit (MU) to recover the time. In this paper a solution to make the distributed PMU aware of synchronization conditions, also in multi-channel operative mode, is presented. The solution is based on a distributed algorithm that is able to estimate the quality of each MU and to obtain an estimation of time quality of the overall system using this information. The results demonstrate as the proposed approach is able to correctly estimate the time quality of the system, also in case of failures which degrade the time synchronization of the MUs.