Calculation Method and Error Analysis of Dielectric Loss Factor Considering the Influence of Harmonics

Harmonics, which exist in power grid, introduce a large error in the measurement of dielectric loss factor, which cannot accurately reflect the insulation level. In this paper, a calculation method of dielectric loss factor considering the influence of harmonics is proposed. The influence of different harmonic content on dielectric loss factor is analyzed by calculating the dielectric loss factor under fundamental and harmonic conditions. The results show that the dielectric loss factor is related to the harmonic content and frequency. The higher the harmonic content is, the greater the dielectric loss factor will be. Particularly when the harmonic content reaches 10%, the difference in dielectric loss factor corresponding to harmonics of different frequencies will increase rapidly. The dielectric loss factor corresponding to the higher harmonics shows an exponential increase with the growing harmonic content. When the frequency reaches a certain value, it will have a great influence on the magnitude of dielectric loss factor, which introduces a large error compared with the dielectric loss factor under fundamental wave.