Purpose/Aim
Three-phase three-limbs transformers are widely used in offshore wind power systems,which play an important role in electric energy transmission. The simulation speed of transformer finite element model is affected by many factors. The electromagnetic transient transformer model needs to be established to meet the needs of rapid simulation.
Experimental/Modeling methods
The parameter extraction test and inrush experiment are carried out on the finite element model of 12.5MVA engineering simulation transformer in offshore wind power station. Based on the principle of BCTRAN model, the improved BCTRAN model for this engineering simulation transformers is proposed considering deep saturation of iron core. .
Results/discussion
Inrush current experiments on a this 12.5MVA engineering simulation transformer in offshore wind power station show that the first peak error of inrush current of the improved BCTRAN model is reduced from 24.9% to -1.7% comparing with the traditional model.
Conclusions
The results show that the improved BCTRAN model of three-phase three-limbs transformers in offshore wind power station can accurately represent the saturation characteristics,which can provide a basic electromagnetic transient transformer model for the study of  three-phase three-limbs transformers in offshore wind power station.

three-phase three-limb transformers,offshore wind power systems,improved BCTRAN model,deep saturation characteristics,inrush current