An Improved BCTRAN Model of Three-phase Three-limbs Transformer in Offshore Wind Power Systems

Abstract

With the rapid development of clean energy,three-phase three-limb transformer is widely used in offshore wind power systems. However, the classical BCTRAN model can not accurately simulate the deep saturation phenomenon at each terminal. In this paper the improved BCTRAN model of three-phase three-limbs transformer has been built. The improved BCTRAN matrix of three-phase three-limbs transformer can accurately describe the coupling relationship between different windings. Deep saturation inductances are measured and determined using the hybrid source method to create the magnetizing branch, including the deep saturation region. Inrush current experiments on a 12.5MVA three-phase three-limb transformer in offshore wind power systems show that the first peak error of inrush current of the improved BCTRAN model is reduced from 24.9% to -1.7 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">%</sup> , comparing with the traditional model, whichcan accurately represent the saturation characteristics and provide a basic model for hree-phase three-limb transformers in offshore wind power systems