A transformer stacked iron core elasticity matrix determination method, wherein
- the stacked iron core is configured as a plurality of electrical steel sheets and includes at least a first portion and a second portion,
- a constitutive equation represents a relationship between stress and strain in the first portion and the second portion, respectively, and includes elasticity matrices that are different from each other,
- each of the elasticity matrices includes, as elements of the elasticity matrix, transverse elastic moduli in two planes including the stacking direction of the stacked iron core, the transformer stacked iron core elasticity matrix determination method comprising:
- a first step of acquiring a frequency spectrum of excitation noise of the stacked iron core of the transformer;
- a second step of acquiring a frequency spectrum of excitation magnetostriction of the electrical steel sheets;
- a third step of determining, for the stacked iron core of the transformer, a first provisional value of the transverse elastic moduli in two planes including the stacking direction of the first portion and a second provisional value of the transverse elastic moduli in two planes including the stacking direction of the second portion, and calculating a frequency spectrum of a vibration response function of the stacked iron core of the transformer when the first provisional value and the second provisional value are applied to the elasticity matrices;
- a fourth step of calculating a frequency spectrum of excitation vibration of the stacked iron core of the transformer, based on frequency spectrum data of the excitation magnetostriction of the electrical steel sheets acquired in the second step and the frequency spectrum of the vibration response function of the stacked iron core of the transformer calculated in the third step;
- a fifth step of calculating a degree of coincidence between the frequency spectrum of the excitation noise of the stacked iron core of the transformer acquired in the first step and the frequency spectrum of the excitation vibration of the stacked iron core of the transformer calculated in the fourth step;
- a sixth step of calculating the degree of coincidence for each combination of the first provisional value and the second provisional value by changing the first provisional value and the second provisional value respectively and repeating the third step to the fifth step;
- and
- a seventh step of detecting a local maximum value of the degree of coincidence calculated for each combination of the first provisional value and the second provisional value in the sixth step, adopting the first provisional value when the degree of coincidence is a local maximum value as the transverse elastic moduli in two planes including the stacking direction of the stacked iron core of the first portion, and adopting the second provisional value when the degree of coincidence is a local maximum value as the transverse elastic moduli in two planes including the stacking direction of the stacked iron core of the second portion, and
- in the sixth step, when each combination of the first provisional value and the second provisional value corresponding to the degree of coincidence is expressed as a trial point set in a two-dimensional space with the first provisional value as a first axis and the second provisional value as a second axis, a plurality of trial points distributed at a first interval in the two-dimensional space is set as a first trial point group, and a plurality of trial points distributed at a second interval narrower than the first interval in the two-dimensional space is set as a second trial point group,
- the third step comprising:
- a 3-A step of calculating the frequency spectrum of the vibration response function of the stacked iron core of the transformer when the first provisional value and the second provisional value are applied to the elasticity matrix for each of the plurality of trial points set as the first trial point group;
- and
- a 3-B step of calculating the frequency spectrum of the vibration response function of the stacked iron core of the transformer for each of the plurality of trial points set as the second trial point group by a numerical interpolation process using frequency spectrum calculation values for each of the plurality of trial points set as the first trial point group calculated in the 3-A step.