A method includes performing by a processor: receiving a plurality of synchrophasor measurements of a power system signal associated with a time interval from a phasor measurement unit (PMU), each of the plurality of synchrophasor measurements including a phase angle, frequency value, and a timestamp associated with the synchrophasor measurement, determining a plurality of relative phase angles based on the plurality of phase angles, determining a correlation coefficient between the plurality of relative phase angles and a plurality of corresponding frequency values of the power system signal, and detecting an error in the plurality of timestamps based on the correlation coefficient; estimating the error in the plurality of timestamps based on the plurality of relative phase angles and the plurality of corresponding frequency values.