Reactive power measurement using the wavelet transform

This paper provides the theoretical basis for the measurement of reactive and distortion powers from the wavelet transforms. The measurement of reactive power relies on the use of broad-band phase-shift networks to create concurrent in-phase currents and quadrature voltages. The wavelet real power computation resulting from these 90 degree phase-shift networks yields the reactive power associated with each wavelet frequency level or sub-band. The distortion power at each wavelet sub-band is then derived from the real, reactive and apparent powers of the sub-band, where the apparent power is the product of the ν,i element pair´s sub-band rms voltage and current. The advantage of viewing the real and reactive powers in the wavelet domain is that the domain preserves both the frequency and time relationship of these powers. In addition, the reactive power associated with each wavelet sub-band is a signed quantity and thus has a direction associated with it. This permits tracking the reactive power flow in each sub-band through the power system