Measurement of apparent power components in the frequency domain

An algorithm and a digital signal-processing technique are proposed for the measurement of the apparent power components in the frequency-domain approach. The discrete Fourier transform (DFT) is applied to simultaneous samples of voltage and current waveforms to compare their respective spectra. The RMS values of the harmonic currents flowing between the source and the load (resistive, reactive, and generated by the load nonlinearity) are calculated. The algorithm evaluates V_RMS, I_RMS and the active power in both the time and frequency domains, and the resistive, reactive, and complementary power components in the frequency domain