FEM Evaluation of Zero-phase-sequence Characteristics of 3-ph 3-limb Core-type Transformers

摘要

The paper deals with the zero-phase sequence behavior of 3-phase-3-limb-core-type two-winding power transformers. The zero-sequence-impedance of power transformers depends on both the type of iron core and the presence of the tank, particularly in the case of three-limb core-type two-winding units without a delta-connected winding. A theoretical analysis proposes an equivalent network which allows the simulation of both the open-circuit and the short-circuit zero-sequence behavior of 3-limb core-type units. A finite element simulation procedure allows the computation of the linear and nonlinear parameters of the equivalent network. Experimental verifications have validated the computational procedure and the proposed theoretical approach.