FR2845474A1 - METHOD FOR DETECTING AND LOCATING AT LEAST ONE SOURCE OF NOISE IN A FLUID VEHICULATING DRIVE AND INSTALLATION FOR ITS IMPLEMENTATION - Google Patents

Abstract

The object of the invention relates to a method for detecting and locating at least one source of noise (S) in a pipe (2) conveying a fluid. According to the invention, it consists in placing on the pipe (2) a first series of at least three vibration or acoustic wave sensors, in taking the time signals delivered by each sensor and each corresponding to the signal emitted by the source. noise, to be determined from the signals taken if the noise source corresponds to an impact on the pipe or a leak in the pipe, and in the case where the noise source corresponds to a shock: • to determine a mathematical estimator such that • and to minimize the mathematical estimator F to determine the estimated values of the position Xo of the shock and of the velocity of sound C as follows:

Description

F (Xo, C) = E [CAt ,, j- f (XoDk (, j))] z sensors (i, j) (Xo, estimated 9 Cestime)

  The present invention relates to the technical field of the detection and localization of sources of noise and vibrations, such as leaks or shocks appearing in a pipe or the like. a pipe for transporting a gaseous fluid

or liquid.

  It is known in the prior art many techniques adapted to locate for example a leak in a pipe. It is thus known for example a technique of mounting on the pipe to be monitored, at least two acoustic or vibratory magnitude sensors, separated from each other by a known distance D. A leak generates a noise that propagates in creating a fluctuation of pressure in the fluid and / or a vibration of the structure of the pipe. From the measurement of the difference in the propagation time of the leakage noise to the two sensors and as soon as the propagation speed V of the noise propagation in the pipe is determined, it is possible to deduce the distance d from the leaked by

  relative to one of the sensors according to the relation: d = (D - V A t) / 2.

  To determine the difference A t of the propagation time of the leak noise towards the sensors, the cross-correlation functions between the signals coming from the two sensors are calculated. When an intercorrelation function has a maximum for a given delay, it can be asserted that a leak exists at a point in the inspected pipe and this leak can easily be located from the difference in noise propagation time. leakage that corresponds precisely to

delay given.

  It turns out that this classic technique of intercorrelation is unsatisfactory in practice. Indeed, this method has the disadvantage of being particularly sensitive to noise that may come from sources of noise 25 located in the environment of the pipeline to be inspected or shocks intervening

  on the pipeline and are likely to affect the integrity of this pipeline.

  Under these conditions, it turns out that sources of irrelevant noise corresponding to false alarms are detected while sources of noise

  relevant are not found.

  An object of the invention is therefore to overcome the above disadvantages by providing a method for detecting a source of noise in a pipe with a minimum of false alarms and the location of a relatively precise position of this source noise corresponding to a shock

on the pipeline.

  To achieve such an objective, the object of the invention is to provide a method for detecting and locating at least one source of noise in a pipe carrying a fluid consisting of: - arranging on the pipe a first series of at least three vibration or acoustic wave sensors separated from each other by known distances Dk (i,>) - to take the time signals Si (t) delivered by each sensor and each corresponding to the signal emitted by the source of noise reaching said sensor with an arrival time ti, - to be determined from the signals taken if the source of noise corresponds to a shock on the pipe or to a leak of the pipe, - and in the case where the source of noise corresponds to a shock: 15 * to determine a mathematical estimator such that F (XOC) = E [CAtj - f (XoDk (ij)) 2 sensors (i, j) with A té: the difference in arrival times between the sensors i, j 20 f = a function of the dispo geometric positioning of the sensors, c = the sound velocity, * and to minimize the mathematical estimator F to determine the estimated values of the position Xo of the shock and the velocity of the sound C as follows: (XO Estimated 'C estimated) Another object of the invention is to provide a method for detecting a source of noise in a pipe with a minimum of false alarms and locate the position of this source of noise relatively accurately

  corresponding to a leak on the pipe.

  To achieve such an objective, the object of the invention is to propose a method consisting in the case where the source of noise corresponds to a leak: - to determine the reference sensor i having detected the source of noise, - to calculate a first function of intercorrelation Fi -., i between the signals emitted by the reference sensor i and a neighbor sensor said upstream i - 1 and a second intercorrelation function r'i, i + 1 between the signals emitted by the reference sensor i and a neighbor sensor said downstream i + 1, - to seek in the intercorrelation functions ri11, i and Fi, i + 1 the emerging peaks whose number is between 0 and 2, - and to analyze the position of emerging peaks of functions

  cross-correlations rFi-, i and r'i, i + 1 to reject the initial detection of the reference sensor i or on the contrary to locate the leak.

  According to a preferred variant embodiment, the method consists in locating the leak by analyzing the compatibility of the combinations of the peaks, possibly

  present in the cross-correlation functions ri-l, i and ri, i + 1.

  According to another preferred embodiment, the method according to the invention consists of analyzing the compatibility of the emerging peaks of the cross-correlation functions r'i, i and r'i, i + 1 in the following manner: the cross-correlation function Fi - ,, i has no peak and if the cross-correlation function rfi, i + has: At either no peak or a peak corresponding to a position at i + 1, then it is concluded that the absence of a leak, A is a peak corresponding to a position between i and i + 1, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position between i and i + 1, then it is concluded that there is a leak at a position between i and i + 1, 25. either a peak corresponding to a position at i, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position at i, a principal peak corresponding to a position at i and a corresponding secondary peak t at a position between i and i + 1, then it is concluded at the presence of a leak in position i, - if the intercorrelation function Fi-p has a peak corresponding to a position at i and if the function intercorrelation ratio ri, i + 1 has: * either no peak, or a peak corresponding to a position at i, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position at i, or a peak principal corresponding to a position at i and a secondary peak 5 corresponding to a position between i and i + 1, then it is concluded that there is a leak in position i, * is a peak corresponding to a position in i + 1 , then it is concluded that there is a leak but not localized, * either a peak corresponding to a position between i and i + 1, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position between i and i + 1, then it is concluded that there is a leak at a position between ei and i + 1, - if the cross-correlation function Fi -., i has a peak corresponding to a position between i-1 and i and if the cross-correlation function rii + 1 has: 15. either no peak or a peak corresponding to a position at i + 1, ie a peak corresponding to a position at i, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position at i, or a principal peak corresponding to a position at i and a secondary peak 20 corresponding to a position between i and i + 1, then it is concluded that there is a leak at a position between i-1 and i, * a peak corresponding to a position between i and i + 1, ie a principal peak corresponding to a position in i + 1 and a secondary peak corresponding to a position between i and i + 1, then if the position of the peaks between i-1 and i and between i and i i + 1 are equal to an error value, it is concluded that there is a leak at position i, otherwise it is concluded the presence of a leak but not localized, - if the cross-correlation function r - ,,; has a principal peak corresponding to a position at i and a secondary peak corresponding to a position between i-1 and i and if the intercorrelation function rii + 1 has: * either no peak or a peak corresponding to a position in i, ie a principal peak corresponding to a position at i and a secondary peak corresponding to a position between i and i + 1, then it is concluded that there is a leak at position i, * a peak at a position at i + 1, ie a principal peak corresponding to a position at i + 1 and a secondary peak 5 corresponding to a position at i, then it is concluded that there is a leak at a position between i-1 and i, * is a peak corresponding to a position between i and i + 1, then it is concluded that there is a leak at a position between i and i + 1, * a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position between i and i + 1, then it is concluded that there is a leak but no If the intercorrelation function Ir1i, i has a peak corresponding to a position at i-1 and if the intercorrelation function r1ii + 1 has: * either no peak or a peak at a position in i + 1, then it is concluded that there is no leakage, * either a peak corresponding to a position between i and i + 1, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position between i and i + 1, a principal peak corresponding to a position i and a secondary peak 20 corresponding to a position between i and i + 1, it is concluded that there is a leak at a position between i and i + 1, θ is a peak corresponding to a position at i, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position at i, then it is concluded at the presence of a leak but not localized, if the intercorrelation function ri.l ,,; has a principal peak corresponding to a position in i-1 and a secondary peak corresponding to a position in i and if the intercorrelation function r'ii + 1 has: * either no peak or a peak corresponding to a position in i , i.e. a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position at i, then it is concluded that there is a leak at position i, θ is a peak corresponding to a position at i +1, then it is concluded at the presence of a leak but not localized, ò is a peak corresponding to a position between i and i + 1, or a principal peak corresponding to a position at i + 1 and a secondary peak 5 corresponding to a position between i and i + 1, ie a principal peak corresponding to a position at i and a secondary peak corresponding to a position between i and i + 1, then it is concluded that there is a leak at a position between i and i + 1, - if the cross-correlation function ri - ,,; has a principal peak corresponding to a position at i-1 and a secondary peak corresponding to a position between i-1 and i and if the cross-correlation function rijl + has: either no peak or a peak corresponding to a position in i + 1, ie a peak corresponding to a position at i, or a principal peak corresponding to a position at i + 1 and a secondary peak at i, then it is concluded that there is a leak at a position between it and i, * is a peak corresponding to a position between i and i + 1, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position between i and 1 + 1, then if the position of peaks between i-1 and i and between i and i + 1 are equal to an error value of 20, it is concluded that there is a leak at position i while otherwise it is concluded that there is a leak but not localized, * is a principal peak corresponding to a position in i and a corresponding secondary peak at a position between i and i + 1, then it is concluded that there is a leak but not a localized one. Another object of the invention is to provide a method for detecting a source of noise from a leak or shock while a background noise is

  present in the surrounding environment of the pipeline.

  To achieve such an objective, the method according to the invention consists in arranging on the pipe at least a second series of at least two and preferably at least three vibration or acoustic wave sensors, adjacent to them. each other, separated from each other by known distances of k (p, q) - and to analyze the signals measured by these sensors to ensure the reduction

  background noise according to the signal-to-noise ratio.

  According to a preferred variant embodiment, the method consists in extracting the signal and the noise by a limited-conditioning wave sorting method consisting in: - estimating each frequency component of a vector X according to the following relation: X = ( M + M) - 'M + P, with P: vector of the measured pressures on the sensors, M +: conjugated transpose of M, M: matrix of the propagation operators, - and to take into account the spectral component of the vector only if

  the conditioning of M + M is less than a limit value.

  According to a preferred variant embodiment, the method consists in the case where the three sensors each have a shunt with respect to the pipe: - to model each shunt by estimating the frequency transfer function H (f) between the sensor and the input of the derivation, - and to take into account this transfer function in the sorting method

limited-edition waves.

  According to another preferred embodiment, the method consists of taking into account the transfer function H (f) of each derivation by using a method of inverse filter deconvolution of the "Wiener" type such that f H * (f) Y (f) H * (f) H (f) + a C (f) with X (f): input of the derivation Y (O: output of the derivation C (f): constraint operator s: parameter of regularization of Another object of the invention is to provide a method for reducing the volume of data to be transmitted to a processing measurement device when

  the source of noise corresponds to a leak.

  To achieve such an objective, the object of the invention is to propose a method consisting in the case where the source of noise corresponds to a leak: - to possibly provide Shannon filtering of the time signals measured by the sensors, - and to ensure binarization of these signals before calculating the intercorrelation function between each pair of these signals thus obtained in order to reduce the volume of the data to be processed. Another object of the invention is to propose a method for detecting a source of noise in a pipe for determining the temperature of the fluid.

  or the internal pressure of the fluid flowing in the pipe.

  To achieve such an objective, the method according to the invention consists in: measuring resonant frequencies of at least one derivative of the sensors, by a spectral estimation, calculating the speed of sound in the channel, and from a characteristic curve of the fluid circulating inside the

  channelization, to deduce the temperature of the fluid if the pressure of the fluid is known or the fluid pressure if the temperature of the fluid is known.

  Another object of the invention is to propose an installation allowing the setting

  implementation of the location detection method according to the invention.

  Various other characteristics are apparent from the description given below in

  reference to the accompanying drawings which show, by way of non-limiting examples, embodiments of the subject of the invention.

  Fig. 1 is a diagram explaining the implementation of an installation of

  detection and localization according to the invention.

  Fig. 2 is a diagram explaining a part of the installation according to the invention. Figs. 3 to 9 are tables explaining a characteristic phase of the process

to locate a leak.

  As it appears more precisely in FIG. 1, the object of the invention relates to a method and an installation 1 for detecting and locating a source of noise S likely to appear on a pipe or pipe 2 for the transport of a fluid in the general sense . Such a transport pipe 2 can be made in any suitable manner for the transport of a fluid such as a liquid or

  a gas and be placed in the open air, buried or immersed.

  In a first embodiment, the installation 1 comprises a first series of at least three vibration or acoustic wave sensors bearing the references for example i-1, ii + 1. Each sensor is separated from each adjacent sensor, a distance Dk (ij), which may be of equal or different value for each pair of neighboring sensors thus formed. These sensors can be separated from each other by a distance typically of the order of a few kilometers or a few tens of kilometers. By way of example, each acoustic or vibratory magnitude sensor is constituted by an accelerometer, a hydrophone, a geophone, a microphone, etc. The installation according to the invention 1 also comprises a measuring device 10 and processing of the time signals Si (t) delivered by each sensor. According to a preferred embodiment, each sensor is part of a station incorporating a signal conditioning and processing unit, connected by radio or wired to a common control and processing center 5 for detecting and locating a source noise. In a conventional manner, such a processing measuring device comprises means for taking the time signals Si (t) delivered

  by each sensor and each corresponding to the signal emitted by the noise source S, reaching said sensor with an arrival time ti. In a conventional manner, the processing measuring device according to the invention comprises specific means of the programmed type whose main functionalities allow the implementation of the method which will be described in the following description.

  According to an embodiment of the invention, the processing measuring device comprises means for determining from the sampled signals Si (t) whether the source of noise S corresponds to a shock on the pipe or to a leak of the pipe. . In general, a shock is a transient phenomenon while a leak is characterized by noise that is generally persistent over time. The signals measured by the sensors are analyzed so that a stationary signal in a characteristic frequency band can be estimated as corresponding to a leak, while a transient signal in a characteristic frequency band

  can be characterized as a shock.

  According to a first aspect of the subject of the invention, the method according to the invention aims at making it possible to locate shocks intervening on the pipe 2, following for example a hammer blow, an explosion, a an impact of a projectile, the fall of an object, a shock of a public works machine, etc. Thus, in the case where the source of noise S corresponds to a shock, the method according to the invention aims at determining a mathematical estimator and minimizing it in order to locate such a shock.

  with a potential reduction of false alarms.

  As is more particularly apparent from FIG. 2, this method is based on the use of the arrival times of the shock signals on at least the three consecutive stations n 1, n 2 and n 3 each having a sensor i-1, i, i + 1 respectively. The shock is assumed by the time T in X0 between the station n 1 and the station n 3 considering the station n 2 as the intermediate station, with O <X0 <D12 + D23 10 and with D12 and D23 positive. The identification of the shock is for reasons of simplification

  given by its abscissa X0 measured from station 1 and to station 3.

  We thus have t1 - t = X0 C ID, 2 -Xo t2 --t = 0c t - t = D12 + D23 - X0 C

  o ti is the arrival time of the shock measured at the level of the station n i.

  The analytical calculation then provides the estimated values of the shock position X0 as well as the sound velocity: X Xp3 - XPI + C (t t3) with C = t) 2 (t -t2) The minimization method of an estimator mathematical is the one used

in the context of the invention.

  The formula chosen hereinafter then provides estimated values of the position X0 of the shock as well as the sound velocity C. F (Xo, C) = C (t) -X + + t +) + D + D 23 2X0] [(t)] - D-D23 + X0 + D-X]

120]

  and (XO, estimated, Cestimée) = arg [(rin) F (Xo, C)] ktX 0, c) In the example illustrated in FIG. 2, the first series of sensors has three positions but it is clear that the subject of the invention applies to n positions. In this case, the general estimator is such that: F (XoC) = 1 [CAtsj -f (XogDk (ij) t 'sensors (i, j)

  with A tij: the difference of the arrival times between the sensors i, j f a function of the geometrical arrangement of the sensors, c = the speed of sound.

  This mathematical estimator is minimized to determine the estimated values of the Xo position of the shock and the velocity of sound C in the following manner (XO, estimated Cestirée) = arg [min F (X0)] This minimization can be performed by optimization c that is to say, by a grid, gradient, conjugate gradient, numerical analysis, etc. The advantages of this method of locating shocks in at least three positions are as follows: * the analytical method is very simple to implement and provides very good results in most cases and the method based on minimizing the mathematical estimator is also simple to implement and also provides very good results

in most of the cases.

  * This last method makes it possible to reject possible false alarms.

  According to a preferred embodiment, the method according to the invention makes it possible to locate a source of noise corresponding to a leak while reducing the

false alarms.

  According to such a characteristic, the method according to the invention consists in determining the reference sensor i having detected the source of noise. The method then consists in calculating a first cross-correlation function ri-i, i between the signals emitted by the reference sensor i and a neighboring sensor called upstream i-1 and a second cross-correlation function Fri, i + between the signals. emitted by the sensor

  reference i and a neighbor sensor said downstream i + 1.

  The method then consists in searching in the intercorrelation functions

  The peak number may be 0 (no peak detected), 1 or 2 (typically one), and the number of peaks may be 0 to 2. peak generated by the leak and a peak generated by a disturbing noise).

  The method according to the invention consists in analyzing the position of the emerging peaks of the cross-correlation functions Fri-1, i and f i + 1 to reject the detection.

  initial reference sensor i or on the contrary to locate the leak.

  According to an embodiment characteristic, the method consists in locating the leak by analyzing the compatibility of the combinations of the peaks, possibly present

  in the cross correlation functions ril, i and Fri, i + l.

  Figs. 3 to 9 represent in the space of time T the different

  possible combinations of the peaks emerging from the intercorrelation functions and the conclusions that must be drawn for the location of the leak.

  The different possible positions for the emerging peaks of the intercorrelation function ri-J, i are as follows:

  - no peak emerging in the cross-correlation function r] F, i (FIG 3).

  a peak emerging from the intercorrelation function F 1, u corresponding to a position at i (FIG 4), a peak emerging from the cross-correlation function Fr 1, i corresponding to a position at F, that is to say between i-1 and i (Fig. 5), - a principal peak emerging from the cross correlation function rFil ,, corresponding to a position at i and a secondary peak at F (Fig. 6), - an emerging peak of the intercorrelation function FIi, i corresponding to a position in i-1 (FIG 7), a main peak of the cross-correlation function Fri, i corresponding to a position in i-1 and a secondary peak corresponding to a position at i (Fig. 8), and a main peak of the intercorrelation function Fr_, u corresponding to a position at i-1 and and a secondary peak corresponding to a position.

in F (Fig. 9).

  For each of these seven possible cases for the cross-correlation function ri_, i, consider the seven possible cases for the cross-correlation function.

ri, i + l which are symmetrical.

  Fig. 3 illustrates the case where the intercorrelation function ril, i has no peak with the seven possible cases for the intercorrelation function r'i, i + 1 as stated above.

  In case 1, the intercorrelation functions do not show a peak of

  so that there is no secondary peak search on these two functions. The initial detection is considered a false alarm so that the leak is not confirmed.

  In case 2, a spurious noise propagates from i + 1 to i but does not arrive on i-1. The peak positioned in i + 1 is rejected and the search for secondary peaks on ri, i + 1 and

  ri, i is negative. Detection is also considered a false alarm.

  In case 3, the leak is at F 'i.e. between i and i + 1 and its noise does not propagate to i-1. There is therefore no search for a secondary peak on

  intercorrelation functions. A leak is validated in F '.

  In case 4, the leak is F 'and its noise does not propagate in i1. A spurious noise propagates from i + 1 to i but does not arrive on i-1. The principal peak positioned at i + 1 is rejected. The search for a secondary peak on ri, i + l is positive while the search for a secondary peak on ri - i is negative. The localisation

a leak is validated in F '.

  In case 5, the leak is in i and its noise does not propagate in i-1. There is therefore no search for a secondary peak on the two intercorrelation functions. The

leak in i is validated.

  In case # 6, the leak is in i and its noise does not propagate in i-1. A spurious noise propagates from i + 1 to i but does not arrive on i-1. The principal peak positioned at i + 1 is rejected. The search for a secondary peak on Fi, i + 1 is positive, while the search for the secondary peak on ri. is negative. The location of the leak is

validated in i.

  In case # 7, the leak is in i and its noise does not propagate in i-1. An unknown noise causes a peak in F '. There is no search for a secondary peak on

  intercorrelation functions. The leak is validated in i.

  Fig. 4 illustrates the case where the cross-correlation function has a peak corresponding to a position at i with the seven possible cases for the function.

intercorrelation ratio ri, i + 1.

  In case n '8, the leak is in i and its noise does not propagate in i + 1. There is no secondary peak search for intercorrelation functions. The location of the leak is validated in i.

  In case 9, a spurious noise propagates from i + 1 to i and i-1. A leak in i can not, however, be totally excluded. The principal peak positioned at i + 1 is rejected, whereas a secondary peak search on the cross-correlation functions is negative. The detection of a leak is confirmed but its location is impossible. In the case No. 10, the leak is at F 'and its noise propagates on the three sensors. There is no secondary peak search on functions

  cross-correlation. The location of the leak is validated in F '.

  In case No. 11, the leak is at F 'and its noise is eventually propagated on the three sensors. A spurious noise propagates in the direction i + 1 to i and can be up to i-1. The principal peak positioned at i + 1 is rejected. The search for the secondary peak on] F ', i + 1 is positive, while the search for a secondary peak on ri,

  is negative. The location of the leak is validated in F '.

  In case No. 12, the leak is at i and its noise is propagated on the three sensors.

  There is no secondary peak search for cross-correlation functions. The

  location of the leak is validated in i.

  In case # 13, the leak is at i and its noise is propagated on the three sensors.

  A spurious noise propagates in the direction i + 1 to i. The principal peak positioned at 25 i + 1 is rejected. The search for the secondary peak on Fi, i + 1 is positive while the search for the secondary peak on rTi. ,, i is negative. The location of the leak is

validated in i.

  In the n 14, the leak is in i and its noise is spread on the three sensors. A

  unknown noise causes a peak in F '. There is no search for a secondary peak on intercorrelation functions. The location of the leak is validated in i.

  Fig. Figure 5 illustrates the case where the cross-correlation function F1; has a peak corresponding to a position at F i-i between i-1 and i, combined with the seven cases

  possible for the intercorrelation function rii ,,.

  In case 15, the leak is at F and its noise does not propagate at i + 1. There is no search for a secondary peak on the intercorrelation functions. The location of the leak is validated in F. In case No. 16, the leak is at F and a parasitic noise propagates in the direction i + 1 to i without reaching i-1. The peak positioned at i + 1 is rejected. The search for secondary peak on intercorrelation functions is negative. The location of a leak is validated in F. In case No. 17, the leak is close to i. There is no secondary peak search for cross-correlation functions. There appear two different results that can come from propagation rate errors. The ambiguity is raised by comparing the distances from the two peaks. If the position of the peaks between i-1 15 and i and between i and i + 1 are equal to an error value, the location is validated

  in position i. Otherwise, it is concluded that there is a leak but not located.

  In case No. 18, the leak is close to i and a parasitic noise propagates in the direction i + 1 to i. The principal peak positioned at i + 1 is rejected. The search for a secondary peak on rf, i + l is positive while the search for a secondary peak on r11; 20 is negative. The solution goes back to case # 17. The leak location is validated in i, if the position of the peaks between i-1 and i and between i and i + 1 are equal to one value.

  of error. Otherwise, it is concluded that there is a leak but not located.

  In case No. 19, the leak is in F and spreads on the three sensors. This case is symmetrical to the case at No. 10. There is therefore no search for a secondary peak on the intercorrelation functions. The location of the leak is validated in F. In case No. 20, the leak is at F and a parasitic noise propagates in the direction i + 1 to i. The principal peak positioned at i + 1 is rejected. The search for a secondary peak on the cross-correlation function ri, i + 1 is positive while the search

  a secondary peak on r1i-, i is negative. The location of the leak is validated in F. In case No. 21, the leak is at F and its noise is propagated on the three sensors.

  An unknown noise causes a peak in F '. There is no secondary peak search for cross-correlation functions. The location of the leak is validated in F. FIG. 6 illustrates the case where the intercorrelation function Fi - ,, i has a principal peak corresponding to a position at i and a secondary peak corresponding to a position between i-1 and i with the seven possible cases for the function

of intercorrelation FI, i +, 1.

  In case # 22, the leak is in i and its noise does not propagate on i + 1. An unknown noise causes a peak far from i. There is no secondary peak search for cross-correlation functions. The location of the leak is validated eni. In case 23, the leak is at F and a spurious noise propagates on the three sensors from i + 1 to i-1. The peak positioned at i + 1 is rejected. The search for a secondary peak on r'i, i + l is negative, while the search for a secondary peak on ril, i is positive. The location of a leak is validated in F. In case 24, the leak is in F 'and an unknown noise causes a peak in F.

  there is no search for a secondary peak on intercorrelation functions. The location of the leak is validated at F '.

  In case 25, the location is uncertain. The principal peak positioned at i + 1 is rejected. The secondary peak search on intercorrelation functions is

  positive. A leak detection is confirmed but its location is impossible.

  In case 26, the leak is at i and an unknown noise causes a peak at F. There is no search for a secondary peak on the cross-correlation functions. The

  location of the leak is validated in i.

  In case 27, the leak is at F and its noise is propagated on the three sensors.

  A spurious noise propagates in the direction i + 1 to i. The principal peak positioned at i + 1 is rejected. The search for secondary peak on intercorrelation functions is positive. The location of a leak is validated in F. In case No. 28, the leak is in i. There is no secondary peak search

  on intercorrelation functions. The location of the leak is validated in i.

  Fig. 7 illustrates the case where the cross-correlation function Fri ,, i has a peak

  corresponding to a position in i-1, with the seven possible cases for the intercorelation function r'i, i +.

  In case 29, a spurious noise propagates from i-1 to i but does not arrive on i + 1. The peak positioned at i-1 is rejected. The search for secondary peak on intercorrelation functions is negative. It is therefore considered that the detection was

a false alarm.

  Case # 30 is unlikely to the extent that noises spread from i-1

  to i and from i + 1 to i. The peak positioned at i + 1 is rejected. The search for secondary peak on intercorrelation functions is negative. Detection is therefore considered a false alarm.

  In case No. 31, the leak is in F 'and a parasitic noise is propagated in the direction

  from i-1 to i without reaching i + 1. The peak positioned at i-1 is rejected. The search for secondary peak on intercorrelation functions is negative. The location of the leak 10 is validated at F '.

  In case 32, the leak is in F '. This case is unlikely to the extent

  the noises propagate from i-1 to i and from i + 1 to i. The peak positioned at i + 1 is rejected. The search for a secondary peak on the intercorrelation function F1i, i + is positive, while the search for a secondary peak on [ala is negative. The location of a leak is validated at F '.

  In case 33, the detection is a priori due to a noise outside the sector of

  pipeline inspected. A leak in i can not, however, be totally excluded. The peak positioned at i-1 is rejected. The search for secondary peak on intercorrelation functions is negative. The detection of a leak is confirmed but its location is impossible.

  In case No. 34, the detection is a priori due to noise outside the sector of the pipe inspected. A leak in i can not be totally excluded. The peak positioned at i + 1 is rejected. The search for a secondary peak on the cross-correlation function rF, i + 1 is positive, while the search for a secondary peak on the cross-correlation function f ', 1 is negative. The detection of a leak is therefore

  confirmed but its location is impossible.

  In case 35, the leak is F 'and its noise does not propagate on the three sensors. A spurious noise propagates in the direction i-1 to i on the three sensors. The peak positioned at i-1 is rejected. The search for a secondary peak on the cross-correlation function r 1, i is negative, while the search for a secondary peak on

  ri, i + l is positive. The location of a leak is validated in F '.

  Fig. 8 illustrates the case where the intercorrelation function Fi-, has a principal peak in i-1 and a secondary peak corresponding to a position in i, with the seven

  possible cases for the intercorrelation function Fi-, i + 1.

  In case 36, the leak is at i and its noise does not propagate at i + 1. A spurious noise propagates from i-1 to i without arriving at i + 1. The principal peak positioned at i-1 is rejected. The search for a secondary peak on the intercorrelation function Fi _-, i is positive, while the search for a secondary peak on the cross-correlation function rF'i, i + 1 is negative. This case is symmetrical to case # 6.

  location of a leak is validated in i.

  In case No. 37, the detection is a priori due to a noise outside the sector of the pipe inspected. A leak in i can not be totally excluded. The peak positioned at i-1 is rejected. The search for a secondary peak on the intercorrelation function r '1; is positive, while the search for a secondary peak on the cross-correlation function ri, i + 1 is negative. We then find ourselves in a case symmetrical to case # 34 for which the location is uncertain. But the detection

leakage is confirmed.

  In case No. 38, the leak is at F 'and a parasitic noise propagates in the direction i-1 to i. The principal peak positioned at i-1 is rejected. The search for a secondary peak on the cross-correlation function ri-1, i is positive, while the search for a secondary peak of the cross-correlation function ri, i + 1 is negative. This case is

  symmetrical in case n 20. The location of the leak is validated in F '.

  In case No. 39, the leak is in F 'and two parasitic noises are propagated in

  the directions i-1 to i and i + 1 to i. The principal peak positioned at i + 1 is rejected. The search for secondary peak on intercorrelation functions is positive. The location of a leak is therefore validated at F '.

  In case 40, the leak is in i. Its noise spreads on the three sensors.

  A spurious noise propagates in the direction i-1 to i. The principal peak positioned at i-1 is rejected. The search for a secondary peak on the intercorrelation function Fr_ ;; is positive, while the search for a secondary peak on the cross correlation function Fi, i + 1 is negative. The location of the leak is validated in i.

  In case No. 41, it is unlikely that there will be no leakage in i. In

  indeed, a very particularly unfavorable configuration of the background noise would be required.

  A leak was detected in i only. The main peak positioned at i1 is rejected.

  The search for secondary peak on intercorrelation functions is positive. The

  location of the leak is validated in i.

  In case # 42, the leak is at F 'and a spurious noise propagates from i-1 to i5 on the three sensors. The principal peak positioned at i-1 is rejected. The search for secondary peak on intercorrelation functions is positive. This case is symmetrical to

  case n 27. The location is validated in F '.

  Fig. 9 illustrates the case where the intercorrelation function r "-1., I has a peak

  principal corresponding to a position at i-1 and a secondary peak corresponding to a position at F, with the seven possible cases for the cross-correlation function ri, i + 1.

  In case 43, the leak is in F and its noise does not propagate in i + 1. A parasitic noise propagates from i-1 to i without reaching i + 1. The principal peak positioned at i-1 is rejected. The search for a secondary peak on the intercorrelation function Fi1, i is positive while the search for a secondary peak on the cross-correlation function Ii, i + 1 is negative. This case is symmetrical in case 4. The location of the leak is validated in F. In case 44, the leak is in F which is unlikely since the noise propagates from i-1 to i and from i + 1 to i. The principal peak positioned at i-1 is rejected. The search for a secondary peak on the cross-correlation function ri-1, i is positive, while the search for a secondary peak on the cross-correlation function Fri, i + 1 is negative. This case is symmetrical in case n 32. The localization is validated in F. In case n 45, the leak may be close to i. A spurious noise propagates in the direction i-1 to i. The principal peak positioned at i-1 is rejected. The search for a secondary peak on the cross-correlation function rii is positive while the search for a secondary peak on the cross-correlation function Fi, i + 1 is negative. This case is symmetrical in case No. 18. A leak is therefore considered in i if the position of the peaks between i-1 and i and between i and i + 1 are equal to an error value. Otherwise, it is

  concluded with the presence of a leak but not localized.

  In case 46, the leak may be close to i. Two noises propagate in the directions i-1 to i and i + 1 to i. The principal peak positioned at i-1 is rejected. The search for a secondary peak on intercorrelation functions is positive. This case is identical to case No. 17. If the position of the peaks between i-1 and i and between i and i + 1 are equal to an error value, it is concluded that there is

  leak at position i. Otherwise, it is concluded that there is a leak but not located.

  In case No. 47, the leak is at F and a spurious noise propagates in the direction 5 i-1 to i. The principal peak positioned at i-1 is rejected. The search for a secondary peak on the intercorrelation function Fi, 1, is positive, while the search for a secondary peak on the intercorrelation function rT, it is negative. The location of a leak is validated in F. In case No. 48, the peak positioned at i-1 and that positioned at i + 1 are rejected. The search for secondary peak on intercorrelation functions is positive. This case is symmetrical in case No. 39. The location of a leak is validated in F. In case No. 49, the peak positioned at i-1 is rejected. The search for secondary peak on intercorrelation functions is positive. The location is uncertain. This case is symmetrical in Case No. 25. It is therefore concluded that there is

leaked but not localized.

  As can be seen from fig. 3 to 9, the method according to the invention thus makes it possible to locate a leak or to reject the initial detection by analyzing the compatibilities of the different combinations of the peaks possibly present in the intercorrelation functions. This process thus makes it possible to confirm or not the initial detection

  a leak by a sensor, and then locate the leak.

  Another object of the invention is to improve the detection of the signals emitted by

  measuring sensors when background noise is present in the surrounding environment.

  The objective is therefore to extract the relevant signals (leaks or shocks) from the background noise. To achieve such an objective, the method according to the invention aims to have on the

  conduct 2 at least a second series of at least two and preferably at least three vibration sensors 7 or acoustic waves, mounted adjacent to each other. By neighbor, it must be considered that the vibration or acoustic wave sensors 7 are separated by known distances of k (p, q) typically between a few tens of centimeters and a few tens of meters or more.

  The method according to the invention then consists of analyzing the signals measured by these sensors 7 to ensure the reduction of the background noise according to the ratio

signal to noise.

  According to a preferred embodiment, the method consists of extracting the signal and the noise by a limited-conditioning method of wave sorting consisting in: estimating each frequency component of a vector X according to the following relationship: M + M) - 'M + P, with P: vector of the measured pressures on the sensors, 10 M +: conjugated transpose of M, M: matrix of the propagation operators, - and to take into account the spectral component of the vector X only

  if the conditioning of M + M is less than a limit value.

  This method consists in taking into account in the reconstruction of the signals only the frequencies for which there is a high reliability of the inversion result. This method is robust and stable in most cases encountered in practice for which the sensors are placed near a

source of parasitic noise.

  According to an embodiment characteristic, the sensors 7 of the second series are each mounted on a bypass 8 of the pipe 2. In the case where these sensors 7 are mounted on such a branch 8, it is intended to take this derivation into account. 8 in the method of limited wave sorting. According to this characteristic, the method consists in modeling each bypass 8 by estimating the frequency transfer function H (f) between the sensor 7 and the input of the bypass 9 and taking into account this transfer function in the method of limited wave sorting. Preferably, the method consists in taking into account the transfer function H (f) of each derivation 8 by using a method of deconvolution by inverse filtering of the "Wiener" type such that: X (f) = H * (f) Y (f) H * (f) H (f) + s C (f) with X (f): input of the derivation Y (f): output of the derivation C (f) constraint operator

  ú: regularization parameter of the inversion.

  Another feature of the invention is to provide a method for reducing the volume of data to be transmitted in the case where the source of noise corresponds to a leak.

  For this purpose, a one-bit correlation method is implemented

  consider reducing the sampling frequency (decimation factor).

  According to this method, the time signals measured by the two sensors framing the noise source are taken into account. Optionally, a prefiltering of these signals

is done.

  The method then optionally consists in providing Shannon filtering of the signals measured by the sensors via the implementation of a filter

Anti-aliasing spectrum.

  The method then consists of ensuring binarization of these signals by

  thus performing a coding on a bit. This coding consists of characterizing the dynamic variations of this signal around its rest point in terms of positive or negative signs. The method then consists in calculating the intercorrelation function between these signals thus obtained in order to reduce the volume of the data to be processed.

  This decimation is possible without deteriorating the performance in terms of accuracy of location by one-bit intercorrelation method. In addition, Shannon anti-aliasing filtering also makes it possible to obtain good results in terms of the absolute value of the correlation coefficient. Without such filtering, it is observed in most cases a degradation of this value. A decimation by a factor of 5 to 10 and the correlation to a bit may for example

  generate a gain of a factor of 100 on the volume of data to be processed.

  According to another aspect of the invention, the object of the invention is to propose a method making it possible to deduce a measurement of the temperature of the fluid or the internal pressure of the fluid flowing inside the pipe 2. According to such a method, it is intended to measure the resonance frequencies of at least one derivation 8 of the sensors 7 by a spectral estimation. The speed of sound is then calculated in line 2. The process then consists of a characteristic curve of the fluid flowing inside the pipe 2 to deduce the temperature of the fluid if the pressure of the fluid is known, or the fluid pressure if the

fluid temperature is known.

  The invention is not limited to the examples described and shown because various

  changes can be made without departing from its scope.

Claims (7)

  A method for detecting and locating at least one noise source (S) in a pipe (2) conveying a fluid, characterized in that it consists in: - arranging on the pipe (2) a first series of at least three vibration or acoustic wave sensors separated from each other by known distances Dk (i, j), to take the time signals Si (t) delivered by each sensor and each corresponding to the signal emitted by the source of noise reaching said sensor with an arrival time ti, - to be determined from the signals taken if the source of noise corresponds to a shock on the pipe or to a leak of the pipe, - and in the case where the noise source corresponds to an impact: To be determined by a mathematical estimator such that F (Xo, C) = E [CAti, j -f (Xo'Dk (iJ)) l sensors (i, j) with A ti j: the difference of the arrival times between the sensors i, jf = a function of the geometric disposition of the sensors, c = the velocity of the sound, * and to minimize the mathematical estimator F to determine the estimated values of the position Xo of the shock and the velocity of the sound C as follows: (Xo, estimated, Cesmje) = arg [min F ( XO, C)] [(Xo, c) 2 - Method according to claim 1, characterized in that it consists, in the case where the source of noise corresponds to a leak: - to determine the reference sensor i having detected the source of noise, - calculating a first intercorrelation function Fil, i between the signals emitted by the reference sensor i and a neighboring sensor said upstream i-1 and a second intercorrelation function Fi, i + 1 between the signals emitted by the reference sensor i and a neighboring sensor called downstream i + 1, to be sought in the intercorrelation functions ri-1, i and Fi, i +! the emerging peaks whose number is between 0 and 2, and analyzing the position of the emerging peaks of the cross-correlation functions r ', i and r'i, i + 1 to reject the initial detection of the reference sensor i or on the contrary to locate the leak. 3 - Process according to claim 2, characterized in that it consists in locating the leak by analyzing the compatibility of the combinations of the peaks, possibly   present in the intercorrelation functions I'i-, i and ri, i + l.   4. Method according to claim 2 or 3, characterized in that it consists in analyzing the compatibility of the emerging peaks of the cross-correlation functions ri-Si and Fi, i + 1 in the following manner: if the function of There is no peak and the cross-correlation function ri, i + 1 has: * either no peak or a peak corresponding to a position at i + 1, 15 then it is concluded that absence of a leak, * either a peak corresponding to a position between i and i + 1, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position between i and i + 1, then is concluded at the presence of a leak at a position between i and i + 1, 20 * either a peak corresponding to a position at i, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position i, a principal peak corresponding to a position in i and a secondary peak corresponding to a position between i t i + 1, then it is concluded at the presence of a leak in position i, - if the cross-correlation function Fi -., i has a peak corresponding to a position at i and if the intercorrelation function Fi , + 1 present: either no peak, or a peak corresponding to a position at i, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position at i, or a principal peak corresponding to a position at i and a secondary peak corresponding to a position between i and i + 1, then it is concluded that there is a leak at position i, * is a peak corresponding to a position at i + 1, then it is concluded at the presence of a leak but not localized, 5. either a peak corresponding to a position between i and i + 1, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position between i and i i + 1, then it is concluded that there is a leak at a position between i and i + 1, - if the function cross correlation r1i1, has a peak corresponding to a position between i-1 and i and if the intercorrelation function rii +, present: * either no peak, or a peak corresponding to a position i + 1, or a peak corresponding to a position at i, ie a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position at i, ie a principal peak corresponding to a position at i and a secondary peak corresponding to a position between i and i + 1, then it is concluded that there is a leak at a position between i-1 and i, * either a peak corresponding to a position between i and i + 1, or a principal peak corresponding to a position in i + 1 and a secondary peak 20 corresponding to a position between i and i + 1, then if the position of the peaks between i-1 and i and between i and i + 1 are equal to an error value, it is concluded at the presence of a leak at position i, while otherwise it is concluded to the presence of a leak my is non-localized, - if the cross-correlation function r] i1, i has a principal peak 25 corresponding to a position at i and a secondary peak corresponding to a position between i-1 and i and if the intercorrelation function rii + l presents: * either no peak, a peak corresponding to a position at i, or a principal peak corresponding to a position at i and a secondary peak corresponding to a position between i and i + 1, then it is concluded at 30 presence of a leak at position i, * is a peak corresponding to a position at i + 1, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position at i, then it is concluded at presence of a leak at a position between i-1 and i, * is a peak corresponding to a position between i and i + 1, then it is concluded that there is a leak at a position between i and i + 1 , 5. is a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a po between i and i + 1, then it is concluded that there is a leak but not a localized one, - if the cross-correlation function ri, 1 has a peak corresponding to a position in i-1 and if the function of If there is no peak or a peak corresponding to a position at i + 1, then it is concluded that there is no leakage, * a peak corresponding to a position between i and i + 1, ie a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position between i and 1 + 1, ie a principal peak corresponding to a position at i and a secondary peak corresponding to a position. between i and i + 1, then it is concluded that there is a leak at a position between i and i + 1, * either a peak corresponding to a position at i or a principal peak corresponding to a position at i + 1 1 and a secondary peak 20 corresponding to a position at i, then it is concluded to the presence of a leak but not localized, if the fo Cross-correlation function ri, i has a principal peak corresponding to a position at i-1 and a secondary peak corresponding to a position at i and if the intercorrelation function Fi, + 1 has: * either no peak, or a peak corresponding to a position at i, ie a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position at i, then it is concluded that there is a leak at position i, * a peak corresponding to a position at i + 1, then it is concluded at the presence of a leak but not localized, * is a peak corresponding to a position between i and i + 1, or a principal peak corresponding to a position in i +1 and a secondary peak 15 20 25   corresponding to a position between i and i + 1, ie a principal peak corresponding to a position at i and a secondary peak corresponding to a position between i and i + 1, then it is concluded that there is a leak at a position between i and i + 1, - if the cross-correlation function ri - i has a principal peak corresponding to a position at i-1 and a secondary peak corresponding to a position between i-1 and i and if the function d crosscorrelation rii + l present: * either no peak, a peak corresponding to a position at i + 1, or a peak corresponding to a position at i, or a principal peak corresponding to a position at i + 1 and a secondary peak corresponding to a position at i, then it is concluded that there is a leak at a position between i-1 and i, * a peak corresponding to a position between i and i + 1, or a principal peak corresponding to a position in i + 1 and a secondary peak corresponding to a position between i and i + 1, so if the position of s peaks between i-1 and i and between i and i + 1 are equal to an error value, it is concluded that there is a leak at position i while otherwise it is concluded that there is a leak but not localized, * is a principal peak corresponding to a position at i and a secondary peak corresponding to a position between i and i + 1, then it is   concluded with the presence of a leak but not localized.   - Method according to one of claims 1 to 4, characterized in that it consists:   - To have on the pipe (2), at least a second series of at least two and preferably at least three sensors (7) of vibration or acoustic waves, adjacent to each other, separated from each other others by known distances of k (p, q) - and to analyze the signals measured by these sensors to ensure the reduction   background noise according to the signal-to-noise ratio.   6 - Process according to claim 5, characterized in that it consists in extracting the Inal and the noise by a limited-conditioning method of wave sorting consisting in: - estimating each frequency component of a vector X according to the following relation : X = (M + M) - 'M + P, with sig P: vector of the measured pressures on the sensors, M +: conjugated transpose of M, M: matrix of the propagation operators, - and to take into account the spectral component of the vector only if the conditioning of M + M is less than a limit value. 7 - Process according to claim 5 or 6, characterized in that it consists, in the case where the three sensors (7) each have a bypass (8) with respect to the pipe (2): - to model each derivation ( 8) by estimating the frequency transfer function H (f) between the sensor and the input of the tap, and to take into account this transfer function in the sorting method limited-edition waves.   8 - Process according to claim 7, characterized in that it consists in taking into account the transfer function H (f) of each derivation (8) by using a reverse filter deconvolution method of the "Wiener" type such that X (f) H * (f) Y (f) H * (f) H (f) + EC (f) with X (f) input of the derivation Y (f) output of the derivation 20 C (f) operator of constraints: inversion regulation parameter 9 - Method according to claim 3, characterized in that it consists in the case where the source of noise corresponds to a leak: - to possibly provide a Shannon filtering of the time signals 25 measured by the sensors, and to ensure a binarization of these signals before calculating the intercorrelation function between each pair of these signals thus obtained in order to   reduce the volume of data to be processed.   - Method according to claim 7 or 8, characterized in that it consists in: - measuring resonance frequencies of at least one derivative (8) of the sensors, by a spectral estimation, - calculating the speed of sound in the pipe (2), and from a characteristic curve of the fluid flowing inside the pipe, to deduce the temperature of the fluid if the pressure of the fluid is   known or fluid pressure if the temperature of the fluid is known.   11 - Installation for detecting and locating at least one noise source (S) in a pipe (2) conveying a fluid characterized in that it comprises: a first series of at least three vibration sensors or acoustic waves separated from each other by known distances Dk (i, j) q - and a measuring and processing device comprising: * means for taking the time signals Si (t) delivered by each sensor and corresponding each at the signal emitted by the noise source reaching said sensor with an arrival time ti, means for determining from the signals taken if the source of noise corresponds to a shock on the pipe or to a leak of the pipe , * and calculation means allowing in the case where the source of noise corresponding to an impact: * to determine a mathematical estimator such that F (Xoc) = E [CAt jj -f (Xof Dk (ij) sensors (ij) with A t1, j: the difference in arrival times between the sensors i, j * to minimize the mathematical estimator F to determine the estimated values of the position Xo of the shock and the speed of the sound C as follows: (XO, estimated9 Cestimée) = arg [(min) (XC)] 12 - Installation according to claim 1 l, characterized in that the calculation means allow in the case where the noise source corresponds to a leak: * to determine the reference sensor i having detected the source of noise, * to calculate a first intercorrelating function Fi-, i between the signals emitted by the reference sensor i and a neighboring sensor said upstream i-1 and a second intercorrelation function ri, i + 1 between the signals emitted by the reference sensor i and a neighboring sensor said downstream i + 1, * to seek in the intercorrelation functions Fi -., i and rf, i + l the emerging peaks whose number is between 0 and 2, 10. to analyze the position of emerging peaks of intercorrelation functions rFi -., i and rF, i + 1 to reject the initial detection of the reference sensor i or on the contrary to locate the leak. 13 - Installation according to claim 12, characterized in that the calculating means locate the leak by analyzing the compatibility of combinations of peaks, 1 5 possibly present in the intercorrelation functions rFili and ri i + i   14 - Installation according to one of claims 11 to 13 characterized in that it   comprises at least a second series of at least two and preferably at least three vibration sensors (7) or sound waves adjacent to each other on the pipe (2) being separated from one another by means of known distances of k (p, q), and whose signals are picked up by the measuring and processing device which comprises signal analysis means measured by these sensors to ensure the   reduction of background noise according to the signal-to-noise ratio.   - Installation according to claim 14, characterized in that the device   Measurement and processing includes means for extracting the signal and noise by a limited conditioning wave sorting method.   16 - Installation according to claim 14 or 15, characterized in that the three sensors (7) of the second series are each mounted on a bypass (8) relative to the pipe (2) and in that the measuring device and method comprises: 30. means for modeling each branch by estimating the frequency transfer function H (1) between the sensor and the input of the branch (8), e and means for taking into account this transfer function   in the method of limited wave sorting.