Basova A. Improved methods of electromagnetic and thermal calculations of the constructional elements in power transformers and reactors on the basis of numeral and analytical models.

The object of research: electromagnetic and thermal processes in the oil-immersed power transformers and reactors. The purpose of research: improving of methods, mathematical models, development of scientific approaches for electromagnetic and thermal calculations in the structural elements of the oil-immersed power transformers and reactors to ensure improvement of their design quality. Methods of research: methods of finite-element analysis at the decision of Maxwell and Navie-Stocks system of equations, for the decision of boundary tasks of heat-conducting with the mixed boundary conditions are analytical methods with expansion of desired function; for verification of results - comparing with the results of numerical design, measuring and heat researches on physical models and model equipment. Theoretical and practical results and innovations: the models of the three-dimensional field calculation of losses are improved in executed from magnetic and non-magnetic steel yoke beams and tank owing to the account of distribution volumetric loss densities to eddy currents and to hysteresis; the method of step-by-step calculation of magnetic field, eddy currents, losses and temperatures of construction elements, which in the three-dimensional models of equipment can be examined as flat, is developed for the first time for the systems of finite-element analysis; the method of thermal calculations of contact conductive plates of the core and anisotropic anisotropic extreme stacks made of electric steel by the use of numerical and analytical models with the specified three-dimensional boundary tasks of heat-conducting with the mixed boundary conditions; the scientific approach to connected electromagnetic, thermal and hydrodynamic calculation of designed elements and windings in stationary conditions of heat and mass transfer in transformer oil was developed for thr first time; calculation methodology of inductance and volt-ampere characteristic of shunt reactors are worked out. A subject degree of introduction: used for the industrial designing as a programmatic-methodical software, and also as normative methodologies of numerical electromagnetic and thermal modelling in PrJSC "Zaporozhtransformator". Effectiveness of implantation: provided the increase of competitiveness of products owing to the optimal choice of structural elements parameters and allowed to provide reliability of construction owing to diminishing of local losses and overheats. Sphere of use: designing and calculations of transformer equipment on machine-building enterprises and at project institutes.