Applications of 3D Simulation to Solutions of Field Problems and Peformance Upgrades of Large Power Transformers

Using advanced numerical technologies, e.g. 3D simulation, is essential for the verification of some critical aspects of design and performance of large power transformers in service. Using such technologies ensures reliable and predictable operation of the transformer, dielectrically, thermally, and electromechanically. These technologies have also proven to be essential in evaluating the condition and insulation life of transformers already in operation as well as evaluating needed cooling system enhancements for increased transformer loadability and higher operational demands. This paper presents a number of applications, where 3D simulation-based analysis has been used. The applications include verifications of hot-spot temperatures of the core and clamping structure of core form transformers, verification of electric field stresses in tap changers´ lead structure and HV bushings, analysis and solution of an overheated bus-duct of a large GSU, and determining the overloadability of transformers in operation. The paper demonstrates why 3D analysis is an essential tool in a simulation-based transformer service (SBTS) activity