Impact of Wideband Noise on Synchrophasor, Frequency and ROCOF Estimation

Next-generation Phasor Measurement Units (PMU) must exhibit superior performances in order to meet the accuracy requirements of active distribution grids. Till now most researchers have focused their efforts on mitigating the impact of intrinsic amplitude and phase fluctuations as well as harmonic and inter-harmonic disturbances, since they are usually the largest sources of intrinsic uncertainty. The effect of wideband noise, both in amplitude and in phase, is instead often regarded as negligible, provided that the resolution of the data acquisition stage is chosen properly and both sampling jitter and synchronization uncertainty are kept strictly below worst-case limits. This paper extends and complements the results already available in the literature, by providing a general framework to evaluate the effect of wideband noise on synchrophasor, frequency and Rate of Change of Frequency (ROCOF) estimation. The results of this analysis show that, when the influence of the other disturbances is reduced, the impact of noise can become not only significant, but even critical for compliance (especially on frequency and ROCOF estimates) with respect to the limits reported in the IEEE Standards C37.118.1-2011 and C37.118.1a-2014.