Fast Measurement of Dielectric Loss Angle With Time-Domain Quasi-Synchronous Algorithm

Fast Fourier transform (FFT) algorithm inevitably suffers from spectral leakage and picket-fence effect under asynchronous sampling and nonintegral period truncation. So the FFT-based dielectric loss angle (DLA) measurement needs window functions and spectral lines interpolation algorithm, which requires massive sampled data and high computational cost. Therefore, this paper proposes a DLA measurement method on the basis of time-domain quasi-synchronous sampling technique to achieve fast measurement and high accuracy. First, the fundamental frequencies of the original voltage and current sampled signals were estimated accurately with the time-domain Newton interpolation algorithm. Then, the quasi-synchronous sampled sequences (QSSA) of the original asynchronous sampled signals were reconstructed using cubic spline interpolation algorithm. Finally, the DLA was calculated according to the equivalent circuit model and frequency-domain analysis of voltage and current QSSA based on FFT. The proposed method in this paper can perfectly restrain spectral leakage and picket-fence effect without window functions and spectral lines interpolation algorithm. The results of simulation and the implementation on the embedded system have confirmed the effectiveness of the proposed algorithm in this paper with less sampled data and lower computational cost.