Study on high accurate dielectric loss angle measurement method considering noise

FFT-based dielectric loss angle measurement methods can be realized easily, however its accuracy is influenced greatly by spectral leakage and noise. This paper presents a high-accuracy dielectric loss angle measurement method based on the Blackman self-convolution window (BSCW), and establishes the dielectric loss measurement result statistical model considering noise. Firstly, the distorted voltage and current signals are weighted using the BSCW. Then, the fundamental phases of the voltage and current signals are calculated with the discrete spectral symmetric interpolation algorithm, and the dielectric loss angle is obtained according to the phase difference between the voltage and current fundamental phases. Finally, the statistical model of the effect of noise on dielectric loss angle measurement accuracy is deduced according to the uncertainty propagation theory. Simulation and laboratory measurement were carried out, and the results verify the effectiveness and practicability of the proposed method and the statistical model.