Study of noise reduction of natural gas pipeline leakage acoustic series by local projection

Key words:  acoustic series  chaos characteristics  local projection  natural gas pipeline  leakage

Abstract:

The acoustic series collected from natural gas pipeline leakage detection includes much noise, and thus, the noise must be reduced before extracting leakage characteristic index. The noise reduction method of local projection for leakage acoustic series was introduced by analyzing frequency distribution and chaos characteristics. The subspace formed by noise was given in the phase space reconstruction process in this method, and through inhibiting noise projection in that space, the noise was reduced. Simulation signal test and field experiment results indicate that the local projection method is suitable for leakage acoustic series noise reduction and can solve the problems brought by frequency alias and chaos in noise reduction processing. The results show that compared with other methods, the local projection method can get obvious improvement in time domain statistical indexes, in analyzing frequency domain, power spectrum and autocorrelation function, as well as in raising signal to noise ratio, which can largely increase the accuracy when extracting leakage characteristic index.