Simplified transient model of transformer based on geometrical dimensions used in power network analysis and fault detection studies

Various models have been presented for evaluation and study of transformers, but a model including all the following properties has not been given in literature by now: 1- The parameters of the model can be calculated through geometrical dimensions, so investigation of a fault effect on the model is possible and it needs no costly measurements. 2- The accuracy of the model in the medium transient frequency domain is satisfactory. 3- The model is simple, so simulation of this model is easy and fast. 4- It is feasible to use the model as a two-port element in network analysis. Such a model is proposed in this paper as simplified transient model (STM). Accuracy and validity of the model is verified using a 2.5 MVA and 6300/420 V three-phase transformer as a test object. This transformer consists of a disk-type high-voltage winding and a layer-type low-voltage winding. Finally, analysis of some important faults in transformers using this model is discussed.

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