Research on the Response Current Harmonic Characteristics of Transformer Damping Oil Paper Insulation

Dielectric response technology is an important means of nondestructive evaluation of moisture state of transformer oil paper insulation. However, oil paper insulation will show nonlinearity under certain conditions, so it is necessary to study the nonlinear characteristics of oil paper insulation. In this paper, the current harmonic characteristics of oil impregnated paper insulation under different voltage frequencies and amplitudes are experimentally studied. It is found that the nonlinearity of dielectric response will lead to the generation of harmonic current. The lower the excitation voltage frequency is, the greater the amplitude is, and the more prone the current response to harmonic distortion is. The higher the moisture content of oil paper insulation, the more serious the harmonic distortion of current response, and the greater the proportion of the third harmonic current, which can reflect the moisture content of transformer insulation paperboard to a certain extent.