LEAK DETECTION FOR CITY GAS PIPELINES BASED ON INSTANTANEOUS ENERGY DISTRIBUTION CHARACTERISTICS

Because of the smallness of flux and low of pressure it is difficult to judge the characteristic signal when leak occurs. In this paper, a new instantaneous energy (IE) distribution characteristics extraction method based on Hilbert-Huang transformation (HHT) was presented and it was used to recognize different states in pipelines, such as, normal state, valve operating, compressor operating and leak. Firstly, the physical relationship between instantaneous energy and structural state variation of a system was analyzed theoretically. With HHT, the instantaneous energy distribution feature of an unstable pressure signal was obtained, according to the relative contribution method of the instantaneous energy, its noise was eliminated. In order to judge the leak the typical character of the instantaneous energy of pressure in the input and output ends was discussed using correlative analysis. The experimental results showed that this method is effective.