Sound quality control method of 110 kV transformer based on distributed variable stiffness dynamic vibration absorber

Area of Science:

• Acoustics and Noise Control
• Electrical Engineering
• Human-Computer Interaction

Background:

• Traditional transformer noise evaluation using A-weighted sound pressure level (L_A) is insufficient for assessing human impact.
• Transformer noise can negatively affect human well-being and perception.
• Advanced methods are needed to objectively and subjectively evaluate transformer noise.

Purpose of the Study:

• To propose an improved transformer noise evaluation method integrating sound quality metrics.
• To develop and validate a sound quality control methodology for transformer noise.
• To assess the effectiveness of a distributed variable stiffness dynamic vibration absorber (DVA) in reducing structural-borne noise and improving sound quality.

Main Methods:

• Field noise measurement of a 110 kV transformer and analysis of objective and subjective parameters.
• Development of a subjective sound quality prediction model using multiple linear regression.
• Application of band-stop filters to attenuate noise at the 100 Hz fundamental frequency and its harmonics.
• Design and laboratory testing of a distributed variable stiffness dynamic vibration absorber (DVA).

Main Results:

• The proposed sound quality control methodology effectively reduced noise at targeted frequencies.
• The DVA demonstrated significant vibration reduction (>30%) and noise level decrease (≥1 dB).
• Field measurements showed a reduction in sound pressure level from 82.2 dB to 76.2 dB and loudness from 24.0 sone to 18.3 sone.
• Subjective scores improved from 4.7 to 6.1, indicating a two-level enhancement in perceived sound quality.

Conclusions:

• The A-weighted sound pressure level alone is an inadequate metric for transformer noise evaluation.
• Integrating sound quality evaluation methods provides a more effective assessment of transformer noise impact on humans.
• The proposed noise control methodology and DVA are effective in reducing transformer noise and improving subjective sound quality.