The Experimental Study On Human Perception Of Low-frequency Noises Induced From Ultra- High Voltage Transformers

With the rapid development of ultra-high voltage (UHV) grid, the influence of low-frequency noise radiated from UHV transformers has attracted considerable public attention. After fully investigating the researches on characteristics, physiological and psychological effects, evaluation method and standard limit of low-frequency noise at home and abroad, transformer noises were sampled in 500 kV,750 kV and 1000 kV substation, respectively. Subjective evaluation experiments were then conducted under laboratory conditions, and the correlations between subjective annoyance and 31 acoustic parameters of noise samples were analyzed. The dose-effect relationship was established using stepwise regression model and Zwicker's psychoacoustics annoyance model, respectively. And the proper annoyance evaluation index for transformer noise, together with their threshold levels, were suggested according to the experimental results.Results of this study are listed as follows. (1) Transformer noise is a typical low-frequency noise with tonal components because of its dominant low-frequency component and a series of tonal components at 100 Hz and its harmonic frequencies. (2) Compared with linear regression model, logistic regression model could better fit the relationships between subjective annoyance and acoustic parameters of transformer noise. It indicated that among 31 acoustic parameters mentioned in this study, there were 14,13 and 5 parameters well fitted with subjective annoyances of 500 kV,750 kV and 1000 kV transformers, respectively. And equivalent continuous A-weighted sound pressure level and loudness level were the common ones. (3) With the same A-weighted sound pressure level, there was little difference between subjective annoyances caused by transformers of the three voltage levels. Thus, a combination of transformer noises of the three voltage levels could be considered as a whole. Fitting process was conducted on the relationships between their MA or %HA and acoustic parameters, coming to the result that A-weighted sound pressure level, loudness level and loudness performed well. (4) Subjective annoyance caused by transformer noise was similar to that of other low-or mid-frequency noise. Compared with other low- or mid-frequency noise, the tonal components of the transformer noise might slightly add subjective annoyance when the A-weighted sound pressure level was lower than 60 dBA, and the influence weakened when A-weighted sound pressure level became higher. When the A-weighted sound pressure level exceeded 60 dBA, subjective annoyance of transformer noise seemed to be lower although its tonal components were stronger. When compared with high frequency noise with high sharpness, subjective annoyance of transformer noise was generally lower with the same A-weighted sound pressure level. (5) The Zwicker's psychoacoustic annoyance model could well predict the subjective annoyance for transformer noises of 500 kV and 750 kV, but not for that of 1000 kV with strong tonal components. The modified Zwicker's model, in which the effect of tonality on subjective annoyance was taken into consideration, could better predict subjective annoyance of transformer noises with different tonal components. (6) According to different control criterions of subjective annoyance and environmental noise limits of different noise environment functional areas in China, the corresponding limits were given of A-weighted sound pressure level, loudness level, loudness and octave band sound pressure level, as well as the modified psychoacoustic annoyance.Results in present study are of great significance to scientifically understand and evaluate the influence of low-frequency noise induced by UHV substation. Meanwhile, it can also provide technical support for the construction of UHV alternating current substation in China from the perspective of environmental protection.