A Fast Frequency Domain Dielectric Spectroscopy Method under Multisine Voltage Excitation and Waveform Parameters Optimization

Dielectric response measurement technology is widely used in dielectric materials for dielectric property measurement and condition assessment as a non-destructive testing method. Pure sinusoidal waveform was adopted as excitation voltage in traditional frequency domain spectroscopy (FDS) measurement. The measurement results at different frequency are obtained by sweep frequency method from high-frequency to low-frequency. A major shortcoming of this method is time-consuming in low-frequency, which limits its application in the field. This paper used multisine waveform instead of natural sinusoid as excitation and studied the optimization methods of multisine waveform parameters. The harmonic components of multisine excitation and response current were extracted using Fast Fourier Transform, complex capacitance and dielectric dissipation factor were calculated simultaneously for each of these harmonic components. The purpose of accelerating FDS measurement was realized base on assurance of measurement accuracy. Three different oil-immersed pressboards and a high voltage testing transformer were measured in 0.1 mHz~1 kHz using self-made measurement hardware and analysis system. The results were compared with commercial instrument IDAX-300. According to the experimental results, the results of the two methods are in good agreement and the relative error is not more than 1%. The measurement time under optimized multisine excitation is only 2.9 h. Compared with conventional single frequency sweep, the proposed method saves 8 h. © 2018, Electrical Technology Press Co. Ltd. All right reserved.