Enhancement of Digital Equivalent Voltage Flicker Measurement via Continuous Wavelet Transform

A continuous wavelet transform-based approach is proposed to assist the measurement of voltage flicker. With the time-frequency localization characteristics embedded in wavelets, the time and frequency information of a waveform is seen integrally presented, thereby enhancing the monitoring capability of voltage flicker signals at different time intervals. By embodying the Gaussian wavelet function, this proposed wavelet-direct demodulation method was also compared with the frequency-domain direct demodulation and indirect demodulation approaches based on the evaluation of flicker-frequency response and the amount of system frequency deviation. Comparison results indicated that the proposed method owns the higher reliability and better visualization. Signal components at any frequency of interest can be supervised more easily. The approach has been applied to investigate various simulated voltage flicker-generated signals and inspect the data recorded from the actual arc furnace operation. Test results support the proposed method in good agreement.