Acoustic emission positioning method of underground gas pipeline leakage point based on Beidou positioning

[0045] The following is a detailed explanation and description of the acoustic emission positioning method of the buried gas pipeline leakage point based on the Beidou positioning of the present invention with reference to the accompanying drawings.

[0046] Such as Figure 1-5 Said, the present invention discloses an acoustic emission location method for buried gas pipeline leakage points based on Beidou positioning. The present invention is based on the Beidou positioning system to obtain the location of the leakage point through time difference positioning, amplitude attenuation positioning and combined with weighted average. It solves the problem that the prior art is difficult to locate the leakage point and cannot detect the leakage of the small flow buried gas pipeline. The acoustic emission positioning method includes the following steps, such as figure 1 , 2 Shown.

[0047] Step 1. The acoustic emission sensor 3 integrated with the Beidou communication module arranged on the buried gas pipeline 5 communicates with the Beidou satellite 4, and the Beidou coordinates of the acoustic emission sensor 3 are obtained through the differential positioning of the reference station 5, so that the acoustic emission sensor 3 can pass The Beidou positioning system performs differential positioning on its own coordinates. Specifically, the differential technology is based on the principle of synchronous co-orbit, based on the Beidou system differential positioning, the reference station 5 calculates the coordinate correction amount of the acoustic emission sensor 3 through the known reference point coordinates; after the acoustic emission sensor 3 obtains the coordinate correction amount, Use the coordinate correction to correct the instantaneous position of the acoustic emission sensor 3 to obtain the Beidou coordinates of the acoustic emission sensor 3. The use of differential technology can greatly improve the positioning accuracy of the acoustic emission sensor, thereby meeting the requirements of leak location; The time of the transmitting sensor 3 is synchronized to realize the synchronization time scale. The current Beidou system has a timing accuracy of 30 nanoseconds, which meets the positioning requirements. In addition, the acoustic emission sensor 3 of the present invention can be arranged on the suspected leaking gas pipe, or when the gas pipe is buried.

[0048] Step 2: Send the Beidou coordinates of the acoustic emission sensor 3 to the host computer 6 through the acoustic emission sensor 3 that is also integrated with a wireless communication module, and the specific communication method is wireless transmission.

[0049] Step 3: Use the acoustic emission sensor 3 to detect the acoustic emission signal of the pipeline in real time, and send the acoustic emission signal of the pipeline to the host computer 6 in a wireless manner;

[0050] Step 4. In this step, before identifying the acoustic emission signal of the pipeline received by the host computer 6, it also includes the step of preprocessing the acoustic emission signal of the pipeline to achieve the purpose of preliminary noise removal, and then pass the screening method based on support vector machine Recognize the acoustic emission signal of the pipeline received by the host computer 6. For the leakage of small flow, the interference caused by the pipeline working condition and environmental noise in the detection process cannot be ignored. Therefore, it is necessary to filter out the effective leakage signal through the pattern recognition algorithm to realize automatic Detect and reduce false alarms, specifically, use a classifier to filter the acoustic emission signals of the pipeline received by the host computer 6. The classifier is obtained by training the support vector machine using noise signal samples and leaked signal samples in advance; this method can identify small, Slow signal leakage, and does not require a large number of training samples. Before measurement, the training noise signal and leakage signal are obtained through experiments. The support vector machine classifies the optimal hyperplane and converts the structure of the optimal hyperplane into a secondary optimization problem. Theoretically, the global optimal solution can be obtained. The classifier is used to filter out the leakage signal sent by the acoustic emission sensor. Judge whether there is a leakage signal in the acoustic emission signal of the pipeline by the above screening method; if yes, go to step 5; if not, go back to step 3;

[0051] Step 5. This step decomposes and reconstructs the leakage signal obtained above. Based on all the acoustic emission sensors 3 that have been time synchronized and the Beidou coordinates are known, the Beidou coordinate set of the leak point 2 is determined by the time difference positioning method and the amplitude attenuation location method; the Beidou coordinate set of this leak point is the initial position of the leak point The collection of results is as follows.

[0052] Such as Figure 4 As shown, the amplitude attenuation positioning method includes the following steps:

[0053] Obtain the sound wave attenuation curve of the gas pipeline 5, the horizontal axis of the sound wave attenuation curve is the distance between the acoustic emission sensor 3 and the leak point 2, and the vertical axis is the amplitude of the leakage signal detected by the acoustic emission sensor 3; search on the sound wave attenuation curve The horizontal axis distance difference is the two points of ΔL, where ΔL is the distance between the two acoustic emission sensors on both sides of the leak point 2; then determine the distance between the leak point 2 and the two acoustic emission sensors, and determine the leak point The coordinate point in the Beidou coordinate set of 2.

[0054] Such as image 3 As shown, the time difference positioning method includes the following steps:

[0055] Assuming that the pipe distance between the two acoustic emission sensors is L, the distance between the leak point 2 and the two acoustic emission sensors is L respectively 1 And L 2 , And L 2 ≥L 1 , L 2 +L 1 =L,L 2 -L 1 =vΔt; then:

[0056] L 1 =(L-vΔt)/2;

[0057] Among them, v represents the speed of sound in the pipeline, and Δt represents the signal delay time obtained after the acoustic emission signals detected by the two acoustic emission sensors are cross-correlated;

[0058] According to L 1 And L 2 Determine the coordinate point in the Beidou coordinate set of leak point 2.

[0059] The present invention innovatively takes into account that the signal received by the acoustic emission sensor has the characteristics of large energy and high signal-to-noise ratio, which is each coordinate point P in the Beidou coordinate set. ij Assign a weight function related to energy, and use the signals from all acoustic emission sensors to calculate the location of the leak point, so as to reduce the error, as follows. The time difference positioning method and the amplitude attenuation positioning method are repeatedly used to determine the coordinate point P in the Beidou coordinate set of the leak point 2. ij; In step 6, the weighted average method includes the following steps:

[0060] Such as Figure 5 As shown, the coordinate point P calculated for every signal detected by the two acoustic emission sensors according to the energy of the signal ij Distribution weight coefficient Of course, the acoustic emission sensor that is close to the point where the leak occurs has more signal energy and more accurate measurement.

[0061]

[0062] Where E i , E j Respectively represent the energy value of the acoustic emission signal detected by the two acoustic emission sensors, E k Represents the energy value of the acoustic emission signal detected by the k-th acoustic emission sensor 3, N represents the number of all effective acoustic emission sensors forming the sensor network, 1≤i i , E j A pair of sensors in a sensor network formed by N effective acoustic emission sensors, which are used to determine a coordinate point in the Beidou coordinate set of the leak point during the time difference positioning or amplitude attenuation positioning process, "effective acoustic emission sensor" It should be understood as: for a target leak point, an acoustic emission sensor capable of detecting the acoustic emission signal of the leak point.

[0063] Then use the following formula to calculate the Beidou coordinate P of leak point 2:

[0064]

[0065] Step 6: Process the Beidou coordinate set by the weighted average method to obtain the Beidou coordinate of the leak point 2. In order to further improve the accuracy of locating the leak point 2, this embodiment further includes step 7.

[0066] Step 7, compare the Beidou coordinates of the leak point 2 with the Beidou coordinate map of the gas pipeline network, and correct the location of the pipeline leak point 2 to determine the more accurate location of the pipeline leak point 2. In this embodiment, the Beidou coordinate map of the gas pipeline network is obtained from the geographic information system (GIS) of the gas pipeline network.

[0067] It should be noted that the determination of the coordinates of the acoustic emission sensor in the present invention can be automated and wireless through the Beidou positioning system. The Beidou satellite navigation system, as a satellite navigation system independently built by my country, currently has the same service performance as the global positioning system in China and surrounding areas. In addition, my country's urban gas pipeline network is gradually adopting the Beidou system for coordinate mapping and establishing a more complete pipeline database network. The adoption of the Beidou positioning system not only supports national independent property rights, but also reduces the dependence on the global positioning system.

[0068] The foregoing descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modification, equivalent replacement, and simple improvement made in the essence of the present invention should be included in the protection scope of the present invention. Inside.