Real-time detection of dielectric loss angle can provide a reliable basis for monitoring electrical equipment insulation. When FFT algorithm is applied to measure the dielectric loss angle

the measurement accuracy is influenced by the spectrum leakage effect due to asynchronous sampling. In this paper

the spectrum leakage effect of FFT algorithm caused by asynchronous sampling is analyzed

and a five-point weighted FFT algorithm is proposed to measure the dielectric loss angle. In the algorithm

five points from the Fourier transformed signal series are weighted and calculated to reduce the spectrum leakage error and improve the measurement accuracy of dielectric loss angle.Simulation with the proposed algorithm is conducted to observe the variation of dielectric loss angle in the cases of varying parameters such as signal frequency

third-order harmonics

sampling frequency

sampling point number

direct current component

theoretical value of dielectric loss angle

initial phase angle

and white noise. The simulation results verify the effectiveness of the proposed five-point weighted FFT algorithm.