EP1277034A1

EP1277034A1 - Method and installation for detecting and locating a source of noises and vibrations

Info

Publication number: EP1277034A1
Application number: EP01929712A
Authority: EP
Inventors: Pascal Simonie; Marc Chamant
Original assignee: Metravib RDS SA
Current assignee: PII Ltd
Priority date: 2000-04-26
Filing date: 2001-04-26
Publication date: 2003-01-22
Also published as: AU2001256413A1; WO2001081885A1; FR2808315A1; FR2808315B1

Abstract

The invention concerns an installation for locating a source of noises and vibrations comprising: at least two detecting devices (3) each comprising a sensor (4) designed to be mounted on a pipe system (2), a system for receiving (5) a dating signal transmitted by a transmission network (6), means for recording and dating the temporal electric signal delivered by each sensor, a system for communicating (9) with a control centre (10) common to said devices (3) and capable of transmitting at least part of each dated signal occurring during a period of analysis including a triggering time; and a control centre (10) comprising means for analysing dated signals so as to measure the temporal difference of occurrence of a common source of noises and vibrations between at least two detecting devices and means for determining the location of said source.

Description

METHOD AND INSTALLATION FOR DETECTING AND LOCATING A SOURCE OF NOISE AND VIBRATION

The present invention relates to the detection and localization of sources of noise and vibration, such as leaks or shocks appearing in a fluid transport pipe.

Many techniques are known in the prior art suitable for locating a leak in a pipe. It is thus known, for example, a technique consisting in 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 which is propagates by creating a pressure fluctuation in the fluid and / or a vibration of the structure of the pipeline. From the measurement of the difference in the time Δt of propagation of the leakage noise towards the two sensors and as soon as the speed V of propagation of the noise in the pipeline is determined, it is possible to deduce the distance d of the leakage by relation to one of the sensors according to the relation: d = (D - VΔt) / 2.

In general, each sensor is part of a detection device connected to each other by a wired or radio type link. Such a detection system has a major drawback relating to the obligation to limit the spacing between two neighboring detection devices, which does not make it possible to monitor a pipe having a great length.

Furthermore, it is known, from document DE 195 28 287, a method and an installation for detecting a leak on a pipe, consisting in mounting at least two sensors each forming part of a detection device, in two places of the pipeline, separated from each other. Each detection device is equipped with a system for receiving a dating signal transmitted by a transmission network common to the devices and with a communication system with a control center common to the devices. The electrical signals, delivered by the sensors, are sent to the control center by the communication system which is therefore strongly monopolized by the transfer of information. Such a method requires having recourse to a dedicated communication system. The object of the invention therefore aims to remedy the drawbacks stated above by proposing a technique suitable for locating with precision a source of noise and vibration over a long length of a pipeline for transporting a fluid with a number limited detection devices, while allowing the use of conventional communication systems and minimizing their use.

To achieve such an objective, the method according to the invention for detecting and locating a source of noise and vibration following an impact and / or a leak occurring on a pipe for transporting a fluid, consists of:

- to mount at least two acoustic or vibratory magnitude sensors, each part of a detection device, at two places in the pipe separated from each other,

- to equip each detection device:

• a system for receiving a dating signal transmitted by a transmission network common to said devices, • a communication system with a control center common to said devices. According to the invention, the method consists:

- at each detection device, to record and date, using the dating signal, the time electrical signal delivered by each sensor,

- at each detection device, to analyze said dated signals, so as to detect the appearance of a source of noise and vibration at a triggering instant,

- to ensure, for at least the device having detected the appearance of a source of noise and vibration and the neighboring detection device (s), the transmission to the control center, of at least the part of each signal appearing during an analysis period including the trigger time,

- to ensure, by the control center: • the analysis of said dated signals, so as to measure the time difference in the appearance of a common source of noise and vibration between at least two detection devices, • and the location of the noise and vibration source from the propagation speed of the noise and vibration source in the pipeline, the separation distance between said sensors and the measured time difference. Another object of the invention is to propose a technique making it possible to detect a source of noise and vibration, such as a leak and / or a shock occurring on the pipe likely to affect the integrity of the pipe.

To achieve such an objective, the method consists in analyzing said signals by carrying out, in a determined frequency domain, the determination of the energy of each signal in this band and in comparing it with a triggering threshold in order to detect the appearance of a leak.

In order to detect the appearance of a shock, the method according to the invention consists in analyzing said signals by sampling said signals during sampling periods, so that the samples of each period are added and compared with threshold values.

Another object of the invention is to provide an installation for detecting and locating a source of noise and vibration following an impact and / or a leak occurring on a pipe for transporting a fluid. According to the invention, this installation comprises: - at least two detection devices each comprising:

An acoustic or vibratory magnitude sensor intended to be mounted on the pipeline at a location separate from the location where the other sensor is mounted, by a given distance,

A system for receiving a dating signal transmitted by a transmission network common to said devices,

Means for recording and dating using the dating signal, the time electrical signal delivered by each sensor,

• a communication system with a control center common to said devices and capable of ensuring the transmission to the control center, of at least the portion of each dated signal appearing during an analysis period including a triggering instant corresponding to l appearance of a source of noise and vibration, Means for analyzing the signals so as to detect the appearance of a source of noise and vibration at a triggering instant,

- and a control center comprising:

Means for analyzing the dated signals so as to measure the time difference in the appearance of a common source of noise and vibration between at least two detection devices,

• means for determining the location of the source of noise and vibrations from the propagation speed of the source of noise and vibrations in the channeling of the separation distance between the sensors and of the measured time difference.

Fig. 1 is a diagram explaining the implementation of a detection installation according to the invention.

Fig. 2 is a functional block diagram explaining an alternative embodiment of a detection device according to the invention. Fig. 3 is a form of a time signal corresponding to the appearance of a leak.

Fig. 4 is a curve illustrating the energy as a function of time for a time signal received corresponding to the appearance of a leak.

Fig. 5 is a form of a time signal corresponding to the appearance of a shock.

As shown more precisely in Figs. 1 and 2, the subject of the invention relates to a method and an installation 1 ensuring the detection and localization of a source of noise and vibrations S likely to appear on a pipe 2 for transporting 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.

The installation 1 comprises at least two and, in the example illustrated, three detection devices 3 each comprising a vibration or acoustic wave sensor 4 intended to be mounted on the pipe 2. Each sensor 4 is separated from each sensor neighbor, with a distance D which may be of equal or different value for each pair of neighboring sensors thus formed. The sensors 4 can thus be separated from each other by a distance D of the order of a few kilometers or a few tens of kilometers. By way of example, each acoustic or vibratory magnitude sensor 4 is constituted by an accelerometer, a hydrophone, a geophone, a microphone, etc.

Each detection device 3 comprises a system 5 for receiving a dating signal transmitted by a transmission network 6 common to the various detection devices 3. It should be understood that the transmission network 6 is adapted to simultaneously supply all the detection devices 3 installed along line 2, the same dating signal. According to a preferred variant embodiment, the transmission network 6 is a GPS (Global Positioning System) network. According to this exemplary embodiment, each reception system 5 of a detection device 3 comprises a GPS antenna 7 connected to a GPS receiver 8.

Each detection device 3 comprises a communication system 9 with a control center 10 common to the various detection devices 3 installed along the pipe 2. The detection devices 3 communicate with the common control center 10 via a communication network 11 of all types, such as, for example, a GSM network, a satellite or wired telephone network, a radio or fiber optic communication network, etc. For this purpose, each detection device 3 is provided with a modem 12, while the common control center 10 is equipped with a communication interface circuit 13 which is connected to a control and processing unit 14 structured around mainly a computer associated with means of specific programming whose main functions will be described in the following description.

Each detection device 3 comprises means 17 adapted to record and date, using the dating signal supplied by the transmission network 6, the time electrical signal delivered by each sensor 4. As shown more precisely in FIG. . 2, the means 17 of each device 3 are connected at the input to a sensor 4 by means of an amplifier or conditioner 18 of the time signal delivered by the sensor 4. In the embodiment illustrated in FIG. 2, the means 17 comprise means of analysis 20 of the signals delivered by the sensors, so as to detect the appearance of a source of noise and vibrations at a triggering instant tj. These means of analysis which will be described more precisely in the following description, are mounted at the output of amplifier 18.

The output of the analysis means 20 is connected to an analog-digital converter 21 connected, at the output, to a microprocessor 22 of all known types. Conventionally, the microprocessor 22 is connected via a communication bus, to a random access memory 24, to a programmable memory 25, to a clock 26, to output interfaces, such as a screen 27 and a keyboard 28. The microprocessor 22 is connected to the GPS receiver 8 and to the modem 12. In a conventional manner, each detection device 3 comprises a power supply 29 for the various circuits, preferably connected to an energy source of the type mains, rechargeable battery or battery, for example.

The operation of the installation 1 follows directly from the above description.

A series (two or more) of detection devices 3 is installed in various suitable locations along the pipe 2 to be monitored. The sensors 4 are mounted on the pipe 2, being separated two by two from a known measurement D which may be equal to or different from a pair of neighboring sensors. Each detection device 3 receives the time signal s (fig. 3 and 5) delivered by the associated sensor 4 and a common dating signal transmitted by the transmission network 6. Each detection device 3 records the time electrical signal s delivered by the associated sensor 4 and ensures its dating using the signal delivered by the transmission network 6. Each signal delivered by the sensors 4 is analyzed by the analysis means 20. As soon as one of the analysis means 20 detects the appearance of a source of noise and vibration, at a triggering instant ti, the corresponding detection device 3, called the trigger, ensures the transmission to the control center 10, of at least the triggering instant tj and an identifier of said detection device, said trigger. The control center 10 then transmits at least the neighboring detection device (s) of the trigger device 3, the trigger instant ti. As illustrated in the example in fig. 1, the trigger detection device 3 corresponds to the device placed in the middle of the other two, so that the control center 10 transmits at least to these two neighboring detection devices 3 the trigger time ti. Of course, the center of control 10 can transmit the triggering instant ti to the other detection devices 3 more or less close to the device called the trigger.

All the detection devices 3 knowing the triggering instant ti, namely, in the example illustrated, the triggering device and the two neighboring devices, transmit to the control center 10, preferably at the latter's request, to the minus the portion of the dated signal appearing during an analysis period Ta determined in advance, including the trigger time tj. It should be noted that the dated part of the signal originating from the trigger device 3 can be transmitted to the control center 10 when the trigger time tj is sent. The control center 10 analyzes said dated signals so as to measure the time difference in appearance Δt of a common source of noise and vibration between at least two detection devices 3. The control center 10 also provides the location of the source of noise and vibrations S from the propagation speed V of the source of noise and vibrations in the pipe, the distance D of separation between said sensors and the measured time difference Δt by applying the relation d = (D - VΔt) / 2.

The control center 10 thus makes it possible to determine the distance d from the source of noise and vibrations S with respect to one or other of the sensors 4 of a detection device 3. It should be noted that the distance d can be determined precisely, insofar as all the signals delivered by the sensors 4 are dated according to a common reference. Thus, the difference in the time Δt of propagation of the leakage noise towards two sensors can be determined precisely. This time difference Δt can be obtained in different ways, such as for example, by implementing an intercorrelation technique between two signals, taking into account the time difference appearing between the instants of triggering of two signals or, more precisely , by determining the instant of appearance of the triggering phenomena by analysis of the recorded signals. In addition, it should be noted that each detection device 3 sends the information to the control center only after having detected the appearance of a source of noise and vibration using the analysis means 20. It follows that the communication network 11 is not permanently occupied. In the example illustrated, each detection device 3 records the dated signals in a rotating memory, so as to obtain the recording of the signals corresponding at least to the chosen analysis period Ta. This analysis period Ta has a sufficient duration, so that the signals taken into account by the neighboring detection devices 3 comprise the characteristic part of the appearance of a source of noise and vibrations. Each detection device 3 knowing the triggering instant ti (namely triggering devices and neighbors) transmits to the control center 10, the part of the signal appearing during the analysis period Ta and before its erasure by the following values of the signal. To do this, provision may be made to stop recording the dated signal at the end of its analysis period Ta until this part of the signal is transmitted to the control center 10. The signal recording is then for follow-up. Preferably, each detection device 3 knowing the triggering instant ti transmits to the control center 10, at least the portion of the dated signal appearing during the analysis period Ta substantially centered on the triggering instant tj. Such a transmission thus makes it possible to know the shape of the signal before and after the instant ti of the appearance of the source of noise and vibrations S.

According to an advantageous characteristic of embodiment, the analysis means 20 are able to detect at least the appearance of a leak. To this end, the analysis means 20 comprise a band filter 31 connected at the output of the amplifier 18 and making it possible to select a frequency domain specific to the pipeline. The output of this band filter 31 is connected to a circuit 32 for measuring the energy E (fig. 4) in this frequency band of the detected signal. The measurement circuit 32 makes it possible to measure the energy in this band by detection of the effective value (RMS). This energy value E is compared with a triggering threshold Si above which a leak is detected. When the value of the energy E reaches the threshold Si, this corresponds to the appearance of the triggering instant ti. Preferably, the value of the energy E is compared during a determined duration Ti, so that a leak is detected when the value of the energy E of each signal exceeds the triggering threshold Si during a determined duration Ti.

According to another advantageous characteristic of the invention, the analysis means 20 make it possible to detect at least the appearance of a shock. Ways analysis 20 include an anti-kink filter 33 also placed at the output of the amplifier 18. As shown more precisely in FIG. 5, the amplified and filtered analog signal s is sampled during sampling periods t _e . For each sampling period t _e , each of the sampled points is added to the sum of the samples already taken. When the number of programmed analysis points is reached (period t _e elapsed), the value of the sum is compared with positive and negative threshold values, in order to detect the appearance of a shock. In the case where the signal does not present a transitory phenomenon, the sum of the samples tends to remain close to a zero value. If the signal representative of a shock appears (fig. 5) and its half pseudo-period is close to the analysis period, the sum of the samples in the analysis period t _e increases strongly positively or negatively. The comparison of the sum of the samples with a positive threshold and with a negative threshold makes it possible to conclude on the presence of a shock. Even if a shock is a transient phenomenon, the analysis means 20 make it possible to identify its presence, and even to dissociate it from a leak whose noise generally persists over time.

In the above example, in the case where a detection device 3 detects the appearance of a shock, the control center 10 analyzes the corresponding dated signal, as well as the dated signals of the detection devices 3 adjacent to the triggering device .

According to an alternative embodiment, it can be envisaged that the device 3, which detects the appearance of a shock, sends, to the neighboring detection devices 3, the part of the signal appearing during an analysis period including the instant of trigger.

Each neighboring detection device 3 is then configured in a particular detection mode consisting in performing an intercorrelation between its dated signal and the dated signal transmitted by the trigger detection device. The intercorrelated signal is then analyzed as described above, that is to say by sampling it during sampling periods te, so that the samples of each period are added and compared with threshold values, in view detect the appearance of a shock. This variant embodiment, which aims to analyzing the signal resulting from the intercorrelation calculation rather than the signal from the sensor, has the advantage of improving the sensitivity of the detection devices 3 neighboring the triggering detection device.

The installation 1 described above makes it possible to monitor over a long length, a transport pipe 2, with a limited number of detection devices 3, insofar as there are no technical constraints for the choice of the distance between two neighboring detection devices 3. The spacing between the detection devices 3 does not affect the accuracy of the measurements, insofar as the signals delivered by the sensors 4 are dated in a common manner allowing, by cross processing, to locate precisely a source of noise and vibration. In addition, the transfer of information between the detection devices 3 and the control center 10 is not carried out continuously, which makes it possible not to monopolize the communication network 11. Thus, it is possible to not not have recourse to a communication network 11 dedicated to the installation according to the invention or in the case of a dedicated network, to limit its use. It should be noted that the installation 1 makes it possible to locate a leak of the fluid transported by the pipeline and / or a shock likely to occur on the pipeline, following, for example, a hammer blow, a explosion, impact of a projectile, fall of an object, etc. Furthermore, when using a GPS type system, it can be envisaged to detect the movement of the consecutive pipe , especially a ground movement.

The invention is not limited to the examples described and shown, since various modifications can be made thereto without departing from its scope.

Claims

CLAIMS:

1 - Method for detecting and locating a source of noise and vibration (S) following an impact and / or a leak occurring on a transport pipe (2) of a fluid, the method consisting:

- to mount at least two sensors (4) of acoustic or vibratory magnitude each part of a detection device (3), in two places of the pipe separated from each other by a known distance (D),

- to equip each detection device: • with a reception system (5) of a dating signal transmitted by a transmission network (6) common to said devices (3), • with a communication system (9) with a control center (10) common to said devices (3), characterized in that it consists: - at each detection device (3), in recording and dating, using the dating signal, the time electrical signal delivered by each sensor,

- at each detection device (3), to analyze said dated signals, so as to detect the appearance of a source of noise and vibration at a triggering instant (ti),

- to ensure for at least the device (3) having detected the appearance of a source of noise and vibration, and the neighboring detection device (s) (3), transmission to the control center (10 ), at least the part of each signal appearing during an analysis period (Ta) including the trigger time (tj),

- to be provided by the control center (10):

• the analysis of said dated signals, so as to measure the time difference (Δt) of the appearance of a common source of noise and vibration between at least two detection devices (3), • and the location of the source of noise and vibrations from the propagation speed of the noise source and vibrations in the pipe, the distance (D) of separation between said sensors and the measured time difference (Δt).

2 - Method according to claim 1, characterized in that:

- the first device (3), called the trigger, having detected the appearance of a source of noise and vibration ensures the transmission to the control center (10), of the trigger instant (ti),

- the control center (10) transmits at least to the detection device (s) adjacent to the triggering device, the triggering time (ti), - the detection devices (3) for which the trigger instant (ti), transmit to the control center (10), each at least the part of the dated signal appearing during an analysis period including the trigger instant (tj).

3 - Method according to claim 2, characterized in that: - each detection device (3) records the dated signals in a rotating memory,

- And each detection device (3) for which the triggering moment (ti) is known, transmits to the control center (10), the part of the dated signal appearing during the analysis period and before its erasure by the values following signal.

4 - Method according to claim 1, 2 or 3, characterized in that each detection device (3) for which is known the trigger instant (ti), ensures the transmission to the control center (10), at least the part of the dated signal appearing during an analysis period (Ta) substantially centered on the triggering instant (ti).

5 - Method according to claim 1 or 2, characterized in that it consists in analyzing the dated signals by carrying out, in a determined frequency domain, the determination of the energy (E) of each signal in this band and in comparing it to a triggering threshold (si), in order to detect the appearance of a leak. 6 - Method according to claim 5, characterized in that it consists in detecting the appearance of a leak when the value of the energy (E) of each signal exceeds the triggering threshold for a determined duration (Ti). 7 - Method according to claims 1 or 2, characterized in that it consists in analyzing the dated signals by proceeding to a sampling of said signals during sampling periods (t _e ), so that the samples of each period are added and compared with threshold values, in order to detect the appearance of a shock.

8 - Method according to claim 7, characterized in that it consists for each sampling period, to compare the sum of the samples to a negative threshold value and to a positive threshold value beyond which a shock is detected. 9 - Method according to claim 7 or 8, characterized in that it consists:

- ensuring, for each device (3) having detected the appearance of a shock, the transmission to the neighboring detection devices (3), of at least the part of the signal appearing during an analysis period (Ta) including the triggering instant (ti), - ensuring, for each neighboring detection device (3), the correlation between its dated signal and the dated signal transmitted by the device (3) having detected the appearance of a shock,

- And to analyze the intercorrelated signal by sampling it during sampling periods (te), so that the samples from each period are added and compared to threshold values, in order to detect the appearance of a shock. 10 - Installation for detecting and locating a source of noise and vibration (S) following an impact and / or a leak occurring on a transport pipe (2) for a fluid, characterized in that it comprises : - at least two detection devices (3) each comprising:

An acoustic or vibratory magnitude sensor (4) intended to be mounted on the pipe (2) at a location separated from the place where the other sensor is mounted, by a given distance (D),

A reception system (5) for a dating signal transmitted by a transmission network (6) common to said devices,

Means (17) for recording and dating using the dating signal, the time electrical signal delivered by each sensor, • a communication system (9) with a control center (10) common to said devices (3) and capable of ensuring the transmission to the control center, of at least the portion of each dated signal appearing during a period of analysis including a triggering instant corresponding to the appearance of a source of noise and vibration,

Means of analysis (20) of the signals so as to detect the appearance of a source of noise and vibration at a triggering instant (ti), and a control center (10) comprising:

11 - Installation according to claim 10, characterized in that the analysis means (20) comprise: - a selection filter (31) of each signal delivered by a sensor, in a given frequency band,

- means (32) for determining the energy (E) of each signal in the selected frequency band,

- And means for comparing this energy with a triggering threshold, the exceeding of which is characteristic of the appearance of a leak.

12 - Installation according to one of claims 10 or 11, characterized in that the analysis means (20) comprise:

- an anti-kink filter (33) for each signal delivered by a sensor (4), - means for sampling each signal during given sampling periods, - means for summing the samples during each sampling period,

- And means for comparing the value of the sum of the samples with negative and positive threshold values beyond which a shock is detected.

13 - Installation according to claim 10, characterized in that each detection device (3) comprises a rotating memory adapted to cyclically record the part of each dated signal appearing during a period of analysis. 14 - Installation according to claim 10, characterized in that each detection device (3) comprises a reception system (5) of a dating signal transmitted by a network (6) of transmission G.P.S ..