Patent ID: 8160195

Claim:
A method for processing a signal of interest in an electrical power system, wherein the signal of interest is subject to phase drift, the method comprising: (a) obtaining a representative window of data points from the signal of interest; (b) obtaining a window of interest containing data points from the signal of interest; (c) determining a phase drift present in the window of interest relative to the representative window, wherein the phase drift is determined by comparing at least one phase angle associated with the window of interest to at least one phase angle associated with the representative window, wherein the phase drift for a frequency f Δθ(f) can be represented in the form: −Δθ(f)=2πs f +ε f F/f, where: s f represents the number of samples by which the signal of interest needs to be shifted to compensate for the phase drift; ε f is an additional fractional compensation for the phase drift that is to be achieved for the frequency f; with a constraint |ε f |<φ f , where φ f =2πf/F; φ f is the expected phase difference observed in the frequency f between two successive samples obtained from the window of interest; and F is a sampling rate of the samples, and compensating for the phase drift to calculate a phase drift compensated window; and (d) comparing the phase drift compensated window to the representative window.