It is required to obtain the excitation forces under operation to achieve
practical noise measures. However, in most cases, it is difficult to
directly measure the excitation force via a sensor because of shapes of the complex structure, especially there is a limit to extract excitation
force of a ultra-high-voltage transformer by experiments. Therefore, this
paper proposes method to extract excitation force of a ultra-high-voltage
transformer by electromagnetic analysis and force identification. Also, this
paper predicts the radiated noise and vibration of a ultra-high-voltage
transformer on load conditions and operating conditions.
Firstly, Lorentz force generated by the three-phase windings on load
conditions is extracted by electromagnetic analysis. At this time, it is
converted the frequency domain because information of the Lorentz force
that is extracted is the time domain. And it is mapped to a finite
element model for structural analysis. Analysis of the structural vibration
and radiated noise under load excitation forces is then conducted using
commercial solvers. Especially the vibration and noise at a frequency of
120Hz, which exerts the greatest effect on load conditions was validated
against experimental results. The radiated noise measured under load
conditions at 120Hz was also compared with the calculated under load
excitation forces. They showed a good agreement.
Secondly, excitation force under operating conditions generated by the
core and three-phase windings are extracted by force identification. this
paper deals with identifying the excitation force by using the acceleration
data measured through experiments and the transfer function estimated
through finite element model. A method to predict structural vibration
and radiated noise on operating conditions was also proposed. Structural
vibration and radiated noise from the surface of the tank was predicted by using the identified excitation force. As a result of the interpretation
of the experimental and computational analysis of structural vibration
from the surface of the tank and radiated noise from the field point, the
interpretation of the computational analysis showed relatively good
accordance with the experiment.
This process could be expected to be applied for the noise reduction of
a ultra-high voltage transformer as well as radiated noise prediction.