Static and Dynamic Characteristics Analysis of Converter Transformer Winding and Bushing Based on Digital Twin Modal Analysis

The axial natural frequency of the large capacity transformer winding is often between <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$50 \sim 100 \text{Hz}$</tex>, and its dynamic characteristics must be analyzed. The paper shows 3D model of the valve side winding established based on the original drawings provided by the manufacturer. Two segments were selected to fit the experimental data separately. In order to analyze influence of different preload forces on axial natural frequency of winding, paper selected six cases: with preload forces of 1000 kN, 1200 kN, 1400 kN, 1600 kN, and 1800 kN, respectively. In the range of 50% to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$100 \% U_{\mathrm{r}}$</tex>, difference between calculated and measured values obtained by method is very small, and compared with traditional methods, the accuracy can be improved by up to 9.8%. After 30th generation, most particles begin to stabilize, and they begin to conduct local refined searches. The relative error between the root mean square value of voltage meter reading and the average value meter reading is much greater than 3%.