Characteristics extraction of acoustic leakage signal for natural gas pipelines

The signals acquired by acoustic leak detection method for natural gas pipelines include useful leakage signal, background noises and interference signals. Therefore, the recognition and characteristics extraction of leakage signal are getting more and more important. The measured signals including leakage signal, knocking signal, compressor shutoff signal, compressor starting signal, regulator closing signal and regulator openning signal were processed by correlation analyses method based on correlation and covariance function. The characteristics of auto-correlation and cross-correlation were extracted. The results show that the correlation analyses can extract the characteristics of leakage signals and other interference signals from the background noises. Then the overall kurtosis can be applied to distinguish the leakage signals from the interference signals. The characteristics extracted by correlation analyses are effective for recognizing leakage signal among the noises and the characteristics of the overall kurtosis can be used to detect leakage signals among all acquired signals if the threshold value of the overall kurtosis is set, which has a strong impetus to the improvement and application of acoustic leak detection technology.