T.S. Legotkina – Ph.D. (Eng.), Associate Professor, Department of Automation and Telemechanics, Perm National Research Polytechnic University. E-mail: firstname.lastname@example.org
Yu.N. Khizhnyakov – Ph.D. (Eng.), Professor, Department of Automation and Telemechanics, Perm National Research Polytechnic University. E-mail: email@example.com
V.S. Nikulin – Student, Department of Automation and Telemechanics, Perm National Research Polytechnic University. E-mail: firstname.lastname@example.org
One of the methods for detecting leaks in the oil pipeline is the method based on the analysis of hydraulic gradient conduct. The hydraulic gradient is a value that characterizes the loss of pressure on the unit of pipeline length. Control sections equipped with measuring and managing devices are installed along the length of the pipeline.
The well known method consists in the following. The data from every pressure sensor is converted in the hydraulic gradient value at a certain point. When the pipeline works normally (no leak) the hydraulic gradient values line along one straight line. When a leak takes place the straightness is disrupted. According to the method the place of the line disruption is detected (using the previously determined deviations from the straight line during the normal work of the pipeline). The results of the measured pressures before and after the place of the leak are used to construct straight lines according to the minimal squares method (MSQ). The point where these straight lines cross is the point of the leak.
To verify this method for detecting leaks a program modeling the work of the system has been designed. During the modeling the parameters of the real oil pipeline Severokamsk-Perm measuring almost 67 km were used. However the calcu-lations have shown that during the leak some deviations of hydraulic gradients may exceed maximum value. As a result it be-comes impossible to determine the number of the section where the leak took place and therefore one cannot say exactly in which interval the leak is located.
That is why to determine the number of the section with the leak the method of fussy approximation is proposed. The method consists in drawing two charts of pressure measurement: one during the normal work of the pipeline and another when the leak occurs. An abrupt change in pressure indicates a leak at a certain section.
Thus the method of fuzzy approximation allows to determine the number of the section where a leak took place. Af-terwards it is necessary using the MSQ to draw two straight lines according to the results of pressure measurements and detect the exact place of the leak.