Моделирование ЭДС магнитных трансформаторов тока для токовой защиты трехфазного силового трансформатора

Abstract

One of the most common damage to the windings of three-phase transformers are loop closures. Traditional current protections have low sensitivity to them, and gas protections are not able to protect «dry» transformers. Unconventional protections on magnetic current transformers are devoid of these disadvantages. However, the implementation of such protections is impossible without calculating the MTT EMF in an arbitrary transformer operation mode, the magnitude of which is determined by the magnitude of the axial component of the magnetic field scattering of the transformer coils. Their mathematical modeling is a difficult task and does not allow taking into account the nonlinearity of this transformer. This can be avoided if the ELCUT software package is used to simulate this axial component of the magnetic scattering field of the transformer windings. Based on its use, a method is proposed for modeling the effective value of the EMF induced in the MTT windings located in the places proposed in the considered protection device of a linear three-phase transformer using the ELCUT software package. The adequacy of the results of modeling the magnetic fields of scattering of transformer windings is assessed by comparing the measured and calculated MTT EMF. Recommendations for taking into account the nonlinearity of this transformer are given.