Enhancement of digital equivalent voltage flicker measurement via continuous wavelet transform

In this paper, 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 also more easily supervised. 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.