New equivalent circuit of three-phase three-limb transformer based on magnetic circuit characteristics

Due to the characteristics of three-phase three-limb transformer core topology, its magnetic flux can be represented by leakage inductances, column leakage inductances and mutual inductances. Based on this representation, a new equivalent circuit model of three-phase three-limb transformer is proposed in this paper. The distinguishing feature of the new model is that the operating mechanism of three-phase three-limb transformer can be expressed straightforwardly. With a simpler structure and fewer elements than the existing models, the proposed model is more convenient to be applied in qualitative analysis and calculations. The new model is validated through the comparison with the conventional nonlinear transformer model based on inductance matrix. As an example of application, the simplified fault current calculation model of three-phase three-limb transformer is introduced in this paper.