A Methodology to Evaluate the Radial Bending Stress of Transformer Inner Windings Based on the Turn-to-Turn Model

The considerable size and intricacy of high-power transformers frequently lead to inefficiency in finite element simulation analysis. To promptly and accurately estimate the stress state of the winding, this paper presents a theoretical approach to analyze the bending stress for each conductor in the inner winding of the transformer. Firstly, this approach takes into account the influences of conductor leakage flux and radial force as they vary with the radial position of the conductor. Subsequently, a 40000 kVA/110 kV transformer is adopted as a prototype, and the turn-to-turn winding model is constructed. The proposed analytical model is verified using 3D finite element method (FEM) simulations. Finally, a leakage flux test was conducted on the prototype, and the simulation and experimental results confirmed the validity of the proposed method.