A case study of noise pollution and its control in an Eco-friendly 500 kV substation

The current accelerated urbanization process in China has been accompanied by a number of environmental problems, such as waste, wastewater, and environmental noise. Due to the increasing number of substations located around the city, noise pollution has become a prominent problem now. It is well known that chronic exposure to high intensity noise may cause health damage. It will inevitably affect the station staff, nearby residents, and the local environment. Yet, little or no attention has been given to low-frequency noise originating from power substation. In order to protect the environment and the public health, avoid the hearing impairment, the power company needs to control noise pollution from substations.This research aims to discuss the environmental impact and human health of low-frequency noise. Exposure to low-frequency noise has significant impacts on human health. This impact is absorbed by the auditory sensation, which is a function of the perception that encompasses aspects of physiological, pathological and sociological order. We presented data from a case study in a 500kV substation of South China. A typical Eco-friendly 500 kV substations was analyzed by the noise source identification technology. Experimental results demonstrated that the noise level of substation depended directly on the transformer. Furthermore, we measured and analyzed the noise characteristic and the frequency spectrum of a single phase 500 kV transformers. The noise levels of the field measurements were compared with the criteria curve in this substation. By the analysis, the position and reasons for the noise were found out. The main noise sources of 500kV transformer were the magnetostriction size of silicon steel sheet and its subsidiaries cooling equipment. Spectral characteristic of the noise was low-frequency noise prominent band noise. The results revealed that the levels of transformer noise were 69.9 dB to 80.5 dB. The spectrum peak value is mostly concentrated in the frequency range from 100 Hz to 200 Hz, which were in low-frequency. The spectrum peak value of cooling fan noise was concentrated on the frequency range of 1k Hz to 2k Hz, which was in medium frequency. The sound field model of the substation was established. The noise attenuation was 19 dB from A phase 1 # transformer to the boundary of the substation, and slowly decreases in low-frequency (11.2 dB to 13.5 dB). However, the measured value of measurement points in southern boundary wall was exceeded the criterion reference value, especially between the 50 Hz and 100 Hz frequency bands.Due to low frequencies of components are considered more annoying for humans. The major measures for Eco-friendly substation were proposed. Thus, three main substation acoustic environment protection measures were considered to reduce noise: noise source control technique, sound insulation technique, and active transformer noise cancellation technique. On the one hand, Noise source control technique can be achieved through the improvement of the production engineering. On the other hand, reasonable treatment schemes focusing on excessive noise problem can be put forward. Finally, considering both the economic benefit and the demand of substation, the best noise control method can be reforming cooling fan noise. The major measures lower the noise level of 2.5$\sim$6.4 dB. This deduction can be confirmed with the results obtained after shutdown equipment, where the criterion curve was exceeded. The excess noise can be efficiently reduced by taking the corresponding noise reduction methods.