Calculation And Analysis Of Eddy-Current Loss And Active Part Vibration In Large Transformer

After summarizing relevant literatures, using the electromagnetic field theory and finite element calculation method, the eddy-current loss, harmonic loss, vibration and noise in large transformers are studied deeply in the thesis. The additional loss calculation and analysis software is developed, which is based on VB and Fortran hybrid programming. Referential rules are provided to improve abilities for transformer temperature rise calculation.First, in terms of eddy-current loss, using the developed additional loss calculation and analysis software, eddy-current loss in transformer windings, stray loss in transformer structures and problems of temperature rise caused by loss are analyzed and calculated. Taking DFP1-240000kVA/500kV power transformer type as examples and compared with the results of foreign program, has good consistency and meets the engineering requirement.Secondly, in terms of harmonic loss, based on analysis of structure and characteristics of converter transformers, the simplified calculation model of time-harmonic field is established by means of Magnet. The harmonic loss in windings and metal structural components of converter transformers is calculated with finite element method. The numerical values of harmonic loss under higher harmonics current are derived and compared with the measurement results and calculation results of IEC61378-2 method. The results show that: compared with results of IEC61378-2 method, the results of simulation are more close to measured values and able to meet engineering design requirement. On that basis, the harmonic loss values under copper shield structure and non-copper shield structure are compared and discussed.Last, in terms of vibration and noise, using ANSYS finite element software, the axial vibration of active part under short-circuit condition and radiation noise of transformer under load condition are analyzed respectively. The vibrating part: according to a 500kV power transformer, the simulation model of windings and power transformer active part vibration, which composes of core, windings, spacers, tensile plates and clamp frames is established, the natural frequencies and vibration modal in different levels of axial pre-compression and active part vibration caused by axial dynamic short-circuit forces of windings under short-circuit conditions are calculated. The noise part: the sound field finite element model of core, winding and tank are established. Using harmonic field and transient field respectively, the radiation noise of transformer is analyzed. The intensity and distribution of noise which caused by vibrations are calculated quantitatively, and the simulation value of ontology noise is compared with the analytical value. The relative error is smaller, and meets the requirements of the sound level specified value in transformer.