Study On The Methodology Of Detection For Transformer Winding Insulation Defects Based On Lightning Impulse Test

As the terminal equipment in power system, power transformer is directly related to the safety and stability of power grid. The faults of transformer may bring great harms to the entire power grid and result in huge loss. A methodology of diagnosing the winding insulation defect according to data of transient voltage and current from the impulse voltage test is put forward in this paper. Lightning impulse test for transformer is divided into half-wave and full-wave at the moment. According to the full voltage and reduced voltage under two pressure processes. The part of data of transient voltage and current from the impulse voltage test can be divided into Series of harmonic. The insulation defect is diagnosed by dividing impulse voltage and current into series of harmonic and structuring discriminant function according to the longitudinal ratio method and cross ratio method for the corresponding period of harmonic voltage and current. The methodology is also applicable to diagnose whether there are insulation damage in the windings those have passed the lightning impulse test. The valuable information about lightning impulse test for transformer can be made full use by the detection methodology put forward in the paper. Insulation defects can be detected rapidly and realize the reliability of the test. Based on a large number of good results in the test of insulation defects with various locations, the methodology is proved that insulation defects can be detected rapidly and reliably.