A FEM-based simulation of electromagnetic forces on transformer windings under short-circuit

Abstract

As the key equipment of power plants and substations, transformers carry heavy responsibility of power transmission, distribution and transformation of voltage levels. Recent years, with the construction of UHV projects, the voltage level in China has increased to more than 1000kV and has formed several UHV networks, enhancing the reliability and efficiency of power supply. Howe ver, this also put more stringent requirements on the operation and maintenance of transformers. When a short-circuit fault occurs, the current flowing through transformer windings will be bigger than before, exerting larger electromagnetic forces on transformer windings, resulting in the collapse of the transformer structure. In that case, it is of great meaning and imperative to calculate short-circuit forces precisely.The finite element method can accurately obtain the magnetic field distribution in all parts of the windings, and plays an important role in the transformer design process. In order to calculate precise electromagnetic forces, this paper reviews the analytical method of electromagnetic force calculation firstly. And then, the three-dimensional and two-dimensional simulation are carried out by FEM. The short-circuit impedance of two-dimensional model and three-dimensional model are compared with measured one to verify the accuracy of these simulation models. Finally, the transient analysis of the two-dimensional model is carried out to obtain the variation laws of short-circuit electromagnetic forces applied to the windings with time. The short-circuit electromagnetic forces obtained through the above method is accurate and quickly. And it can provi de the necessary reference for the transformer design.