Calculation On The Winding Short-Circuit Electrodynamics Force And Stability Analysis Of Transformer

The transformer which is one of the indispensable electric equipment of electrical substation and power plants, occupies a pivotal position in power system,and it plays an important role on power transmission and the transformation of voltage degree. In recent years, the transformer which has larger capacity and voltage degree is more and more highly required. In this case, the research on the stability of transformer under winding short-circuit condition has become one of the important projects to break through the electric power industry.In this paper, based on the "field-circuit coupling" principle, the threedimensional finite element model which regards a SFP10-370000/220 without excitation regulating power transformer as an example is established under different tap ampere-turns unbalanced situations by using the MAGNET finite element software and the availability of the model is checked based on short-circuit impedance for validation. On the basis of considering the core material nonliterary,this paper uses nonlinear transient solver to solve the magnetic flux leakage distribution and short-circuit electrodynamics force about transformer high and low voltage winding. Then the Calculation formula of the winding’s average temperature is derived under sudden short-circuit. In addition, this dissertation calculates the average temperature of examples by using the formula and compares the average temperature calculated by the formula derived to the result calculated by the formula on the GB1094.5-2008 under winding short-circuit. Based on the result of the comparison, the paper judges the correctness of the formula, at the same time also analyzes the dynamic and thermal stability of transformer under short-circuit conditions.High and low voltage winding of transformer under the action of radial shortcircuit electrodynamics force will respectively appear to the phenomenon of internalcompression and stretching outwards, so it’s necessity to analyze winding’s radial stability. For the high voltage winding three-dimensional drum mechanical model is established by using the ANSYS finite element software, use transient analysis method to calculate the displacement deformation under cyclic load, and check the winding radial stability. Considering the dynamic characteristics of short-circuit electrodynamics force, the influence of winding structure, and the uneven force, etc.,the linear buckling analysis was carried out on the low voltage winding to assess stability and determine the critical load of low voltage winding how it can bear. It also need to obtain the low voltage winding safety margin under the maximum radial short-circuit electrodynamics force, and the nonlinear buckling analysis was applied to low voltage winding deformation is calculation under a variety of initial defects.Because of the small space between adjacent stay, the dissertation evaluates the stability of transformer’s snap-through by using slightly round flat arch model combined with in-plane buckling theory, and concludes the relationship between the deflection of winding, span of transformer, winding’s loads and snap-through.This paper proves that the transformer simulated has good dynamic and thermal stability under short-circuit conditions, and also proposes the method of researching transformer radial stability and snap-through stability, which provides the beneficial reference in the process of transformer design and stability evaluation for transformer researcher.