Measurement of Noise Emission Level at Substation Boundary Based on Coherent Power

According to the Chinese standard of GB 12348-2008, to determine the noise emission level at substation boundary, the noise level of substation boundary and the background should be measured separately. Then correct noise level at substation boundary utilizing measured background noise. However, the measured background noise is inaccurate due to the different acoustic environment. Therefore, the noise emission level at substation boundary applying this method often has a certain error. This paper proposes a method for separating transformer noise to calculate the noise emission level of transformers based on coherent power, which avoids the error caused by the inaccurate measurement of background noise.