1. A method for obtaining a power system phasor comprising: sampling a power system signal at instants determined by a nominal power system frequency to provide a plurality of data samples; using the plurality of data samples to estimate a phasor having an elliptical trajectory; generating a deviation formula representing a frequency deviation between an actual power system frequency and the nominal power system frequency; and using the deviation formula to perform a coordinate transform of the estimated phasor to provide a scaled phasor having a substantially circular trajectory.