Research On Accurate Leak Locating For Long GAS Pipeline

At present, there is variety of methods of pipeline leak detection technology, including acoustic leak detection technology which has its own advantages, applied widely in practice. However, because of the complexity of the actual working condition, acoustic signal contains lots of interference so that leak detection alarms still contain failed alarm and false alarm.In order to improve acoustic leak detection system’s diagnostic reliability and locating accuracy effectively, to reduce the failed alarm and false alarm, this paper proposes an acoustic signal processing method of delay-difference, considering acoustic signal’s characteristics of susceptible to interference caused by the strong low-frequency signal, analyzes the effect to feature extraction caused by the different step-length so that gains the selection criteria for step-length.The impact on the cross-correlation coefficient curve’s peak position is analyzed theoretically in detail, this paper proposes the method of matching positioning which can separate the interference signals from the leakage signals effectively and improve the positioning accuracy in single section pipeline. For multi-sections of long-distance gas pipeline, the paper proposes a locating method by the combination of abnormal signal tracing and delay-alarm method by analyzing the transmission relationship of abnormal signals among adjacent sections, simulating situations contain the abnormal signals which can cause repeat alarm and false alarm easily.Test results with measured acoustic signals show that the abnormal signal diagnosis and matching locating method based on delay-differential signal can improve the leakage detection system’s reliability and locating accuracy effectively. Coupled with method of abnormal signal tracing and delayed-alarm, failed alarm and false alarm can be reduced effectively for long distance gas pipeline.