A method of processing power signals is provided. The method includes: receiving an analog poly-phase signal associated with power delivered using alternating current (AC); converting the analog poly-phase signal to a digital poly-phase signal sampled at a first sampling rate; detecting a fundamental frequency of the analog poly-phase signal; determining a second sampling rate, wherein the second sampling rate is based on and tracks the fundamental frequency; resampling the digital poly-phase signal at the second sampling rate; for each cycle of the resampled digital poly-phase signal: transforming the resampled digital poly-phase digital signal to a frequency-domain signal; calculating a phase angle of the reference voltage component; adjusting the resampled digital poly-phase signal by compensating the calculated phase angle; and transforming the adjusted resampled digital poly-phase signal to an updated frequency-domain signal using FFT; and calculating one or more measurements based on the updated frequency-domain signal.