Measurement of voltage distortion in the frequency range 2 – 9 kHz

This paper presents some of the results obtained in the measurement of voltage distortion in the frequency range 2 to 9 kHz in a low-voltage distribution network. The Discrete Fourier Transform is used for the analysis of the voltage waveform using a 200-millisecond window width and grouping in 200-Hz bands. The paper presents the time-frequency analysis of the results obtained during several days monitoring of voltage distortion, and proposes a new performance index for assessment of the distortion in this frequency range. Finally a new method, based on the use of wavelet analysis, is proposed for the assessment of the distortion in this frequency range.