Method and apparatus for detecting leakage points in supply network

Abstract

The invention relates to a method and a suitable device for detecting leakage points in a supply network having a line system through which a fluid is conducted, at different locations (x1, x2,... xN) of the line system, the pressure (p (t)) of the fluid and the volumetric flow rate (V (t)) of the fluid being captured in each case in a time-dependent manner using a measurement technique. The invention is characterized in that the pressure in the line system is regulated at a first location (x1) for a defined first duration (T1) by means of a predeterminable first reference signal (M1), and a curve of the regulated pressure signal and the volume flow signal is determined preferably at the first location (x1), when a time difference ([delta] t1) between the defined signal component of the pressure signal and the defined signal component of the volume flow signal is detected, a first distance from the leakage point to the first location (x1) is determined from the time difference ([delta] t1). The method according to the invention and the correspondingly designed device can be used in particular for detecting existing leakage points in supply networks.

Description

Technical Field

[0001] This invention relates to a method for detecting leaks in a supply network with a piping system, wherein fluid is guided through the piping system, and the pressure and volumetric flow rate of the fluid are captured at different locations within the piping system, depending on time, using measurement techniques. The invention also relates to apparatus suitable for this method. Background Technology

[0002] Drinking water loss caused by dilapidated pipeline systems is a significant problem in many countries around the world. Vast quantities of drinking water are lost at unknown leak points. There is a global need for treatment as climate change, a growing global population, and increasing industrialization are making water increasingly scarce and leading to expensive food.

[0003] Various methods for detecting leaks in water distribution networks are known in existing technologies. In principle, leak detection techniques can be categorized into two types: external and internal. External methods identify leaks by searching for signs of leakage outside the piping system. An example of this is visual inspection. Another method is to listen for flow noise in the pipes at various locations, thereby determining the location of the leak. Internal methods, such as internal inspections, attempt to locate leaks using sensors that measure, for example, the state parameters within the pipes. This category includes various mathematical calculations and signal processing methods.

[0004] In the literature "Pressure wave behavior and leak detection in pipelines" (Journal of Agricultural and Food Research, 1996, by Silva et al., Proceedings of the 6th European Symposium on Computer and Chemical Engineering (Rhode Island), 20, pp. 491-6), an online computational technique is known in which a computer detects transient data caused by a leak, displays a pressure transient curve, and can identify the location of the leak. This method is based on the fact that the pressure wave generated by a leak is accompanied by a sudden pressure drop. Leak point identification devices for various water distribution pipes are known from the literature GB2444955A, in which pressure waves are transmitted from fire hydrants to underground pipelines. Sensors detect pressure fluctuations in the liquid in the pipe caused by the pressure wave, which are reflected by discontinuities in the system (e.g., leaks). The control device records, analyzes, and calculates the distance between the pressure sensor and the identified interruption. A drawback of the method for leak point identification described in GB2444955A is that it requires significant pressure fluctuations to generate reflections at the fault location of the leak, which introduces pressure into the pipeline system. Furthermore, the measurement structures involve temporary setups requiring personnel and cannot be permanently integrated into the existing infrastructure. The measurement structures only function at larger leak points, and other fault locations (such as branch or cross-sectional changes) result in false checks. Additionally, the detection range is very limited.

[0005] WO2019 / 160433A1 describes a method for processing transient events in a distributed network with a defined network topology based on wavefront characterization, which is derived at high speeds from multiple sensors at defined measurement locations within the distributed network. In this method, the arrival time of the wavefront caused by the determined transient event is detected at at least a subset of measurement locations by corresponding sensors of N sensors. Then, the location of the determined transient event in the distributed network is determined based on the detected arrival time of the wavefront detected by sensors at a subset of measurement locations. Subsequently, the event type of the transient event in the distributed network is classified under the conditions of the determined location of the transient event in the distributed network, the conditions of the detected arrival time of the wavefront, and the conditions of the defined network topology of the distributed network. The method described in WO2019 / 160433A1 also has drawbacks, namely, very large pressure gradients (e.g., caused by pipe rupture) can put pressure on the pipeline system. Furthermore, multiple densely interwoven measurement locations are required, meaning that powering the measurement locations is often difficult. All measurement locations require very precise clock timing or must be precisely synchronized. Summary of the Invention

[0006] In particular, the methods described in these two descriptions are not applicable to continuous monitoring of existing leaks integrated within a water supply network. Therefore, the object of the present invention is to overcome the shortcomings of the prior art and to provide methods and apparatus for identifying leaks in supply networks, particularly water supply networks, especially existing leaks.

[0007] This objective is achieved by a method having the features of claim 1. Furthermore, the method is achieved by the apparatus according to claim 15 and the computer-aided processing unit according to claim 16. Advantageous improvements are derived from the dependent claims.

[0008] The proposed method is known in principle from the identification of systems analysis or dynamic systems, and is particularly suitable for stimulating dynamic systems. According to the invention, during a measurement activity at a location within the supply system, the system is intentionally stimulated using a pressure signal, and in response, the flow rate at the applied pressure location is measured (and the pressure is also measured for comparison). The distance to the leak location can be calculated from the time offset between the pressure change and the flow rate change. Through multiple measurement activities at various locations, the precise location of the leak can be measured. Specifically, the feed point in the piping system into the supply network can be used as the measurement location. However, any location within the supply network is equally suitable as a measurement location.

[0009] Therefore, the present invention relates to a method for detecting one or more leak points in a supply network having a piping system through which fluid is guided, wherein the pressure and volumetric flow rate of the fluid in the piping system are captured, respectively, at different locations in the piping system over time, using measurement techniques. The invention is characterized in that, at a first location, the pressure in the piping system is adjusted using a predetermined first reference signal for a defined first duration, and preferably, curves of the adjusted pressure signal and volumetric flow rate signal are recorded at the first location, and, in the case of detecting the time difference between a defined signal component of the pressure signal and a defined signal component of the volumetric flow rate signal, a first distance between the leak point and the first location is derived from this time difference.

[0010] Advantageously, the method for leak detection according to the invention has multiple applications. In particular, it can be used to detect existing leaks in a supply network. It can also detect small leaks that grow larger over time. Normal operation of the supply network is unaffected during measurement activities, thus allowing the method to be easily integrated into the existing operation of the supply network. The method is implemented in a way that allows for the distinction between normal operation and leaks in, for example, a drinking water network. This is because, in principle, it is impossible to distinguish whether a leak or normal operation is involved at the point of consumption (i.e., the location from which fluid is obtained from the network). Accordingly, for example, a pressure reducer is provided at the consumption point (i.e., the household port) in the drinking water network, which decouples events in the network from operation within the house. All outlet locations after the pressure reducer do not experience pressure changes in the network. Furthermore, it is noted that most water consumption characteristics in a piping network are statistically distributed. That is, the location, time, and amount of water consumption vary at each point in time. In contrast, leaks are at fixed locations, persist at every time, and the volumetric flow rate at the leak depends on the pressure. Therefore, by taking multiple measurements at different times over several days (especially at night), it is possible to distinguish the identified leak points from the remaining consumption characteristics using the method according to the invention.

[0011] While the measurement process can only determine the distance to the leak point, the first advantageous embodiment of the invention can also determine the precise location of the leak point in the pipeline system. For this purpose, the method according to the invention is repeated at different times at other locations in the pipeline system. At the second location in the pipeline system, the pressure in the pipeline system is adjusted using a second, predetermined reference signal that is identical to the first reference signal for a defined second duration equal to the first duration. Preferably, the adjusted pressure signal and volumetric flow rate signal are now acquired at this location, and a second distance between the leak point and the second location is derived from the time difference between the defined signal components of the pressure signal and the defined signal components of the volumetric flow rate signal. This method is repeated at other locations, and the location of the leak point in the pipeline system is determined from multiple such distances. The more locations where adjustment and measurement are performed, the more accurate the leak point location becomes. By applying different reference signals for pressure adjustment, individual measurements can be better distinguished.

[0012] In a particularly advantageous implementation variant, the distance from the leak point to the measurement location is determined at different measurement time points. This allows for high flexibility in determining the leak point. Thus, for example, it is possible to measure the first distance from the leak point to a first measurement location on one day, and the second distance from the leak point to a second measurement location on another day, or for example, at night. Furthermore, the various measurement time points allow for better separation of the individual measurements. This implementation is particularly advantageous in the case of long-term leak points.

[0013] In most cases, the location where regulation is introduced into the piping system is the same as the location where pressure and volumetric flow rate are measured. However, it is also advantageous, for example, due to the actual conditions of the supply network, that regulation is introduced into the piping system at only one or a few locations, and measured at different locations. In this advantageous embodiment, the location where pressure is regulated in the piping system is at least partially different from the location where pressure and volumetric flow rate of the fluid are measured. This also applies to the technical means of capturing pressure and volumetric flow rate measurements of the fluid at different locations within the same piping section. The structural realities within the piping system or its sections may necessitate spatial separation of pressure and volumetric flow rate detection.

[0014] In another advantageous variant of the invention, the duration of pressure regulation in the piping system is at least partially consistent with the duration of measurement of the pressure and volumetric flow rate of the fluid. In principle, the duration of regulation and measurement needs to be consistent for deriving the time difference between the pressure signal and the volumetric flow rate signal. However, it is advantageous in various cases, for example, to adjust the regulation signal before the actual measurement with a time offset begins, so as to adapt it to the system.

[0015] The regulating signal can be arbitrarily selected. It can be short-duration pressure fluctuations, pressure steps, or applied pressure in sinusoidal form at various frequencies. Downward pressure steps (e.g., 2 bar below the operating pressure) can also be considered. In a particularly advantageous implementation variant, a periodic signal with a predetermined amplitude, frequency, and phase is selected as the pressure regulating signal, and correspondingly, the time difference between the pressure signal and the volumetric flow rate signal obtained at the location is a phase difference, which can be obtained with particular precision using measurement techniques.

[0016] In the case of periodically adjusted signals, the phase between the pressure signal and the volumetric flow rate signal can be affected by changing the frequency of the pressure signal. This frequency adjustability is particularly advantageous for improving the accuracy of time difference measurements.

[0017] In another advantageous embodiment, the measured pressure signal is correlated with the measured volumetric flow rate signal. The correlation strengthens a specific signal component. This can be particularly advantageously utilized by maximizing the duration for measuring the pressure and volumetric flow rate of the fluid. Here, "maximum" is understood to be on the order of several hours.

[0018] Of particular advantage, the amplitude and frequency of the regulating signal can be selected according to the characteristics of the piping system. Depending on the expansion of the piping system and the dynamics of the system, the frequency of the regulating signal can be in the range of approximately 0.05 Hz to 0.5 Hz.

[0019] The efficiency of this method can be significantly improved by incorporating fluid pressure and volumetric flow rate measurement techniques and / or pressure regulation into the control system.

[0020] Another advantageous design of the invention is that the supply network is a water distribution network, and the locations are feed points for water to enter the piping system. The invention can be used in all infrastructure networks in which fluids are transported and / or consumed. Examples of such infrastructure networks include gas supply and district heating networks, but hydrogen distribution networks can also be included. Attached Figure Description

[0021] The present invention and its design scheme will now be described and illustrated in detail with reference to the accompanying drawings showing embodiments of the present invention.

[0022] The attached diagram shows: Figure 1 An outline of a first embodiment of the device according to the present invention is shown; Figure 2 A graph showing the time curves of the pressure signal and volumetric flow rate signal with adjustment is displayed. Detailed Implementation

[0023] Figure 1 An embodiment of a device 1 according to the invention for determining a leak point in a piping system through which fluid is guided is shown. Device 1 is arranged at location x1 of a pipe section R in the piping system. In this embodiment, device 1 includes a device 2 for regulating fluid pressure, a computer-aided control unit 3 for controlling the device 2 for regulating fluid pressure, a pressure sensor 4A having a pressure p(t) for measuring fluid pressure using a measurement technique, and a volumetric flow rate for measuring fluid volume using a measurement technique. The volumetric flow sensor 4B of (t) includes a capture system 4 and a processing unit 5 that is communicatively connected to at least the control unit of the device 2 for regulation and the capture system 4.

[0024] The pressure regulating device 2 can be configured to change the pump speed, for example. This change can be achieved by means of a pressure-boosting pump or other mechanical device, such as a pump with a bypass feedback circuit having a throttle valve. Figure 2The pump is connected to a computer-aided control unit 3, which, for example, changes the pump's rotational speed. A control signal corresponds to a reference signal, which is used to regulate the pressure of the fluid in the pipeline. For example, a Siemens SITRANS P family measurement transducer can be used as a pressure sensor 4A. For example, a Siemens SITRANS F family measurement transducer can be used as a volumetric flow sensor 4B. Preferably, the pressure sensor and the volumetric flow sensor are positioned close to each other. It is particularly advantageous that the two sensors are arranged in the same pipe section of the piping system. In particular, drinking water feed points are provided in the water supply network, as pressure and flow sensors are typically already present at these locations. The measurement transducer is often connected to a data processing unit 5 via fieldbus communication, which in turn can be connected to a higher-level data processing system 6 (e.g., a control system), where the acquired process and diagnostic data are further processed.

[0025] According to the present invention, in order to determine the leak point, the pressure in the pipeline system is adjusted at location x1 for a predetermined first duration T1 using a first reference signal that can be predetermined, and preferably the adjusted pressure signal and volumetric flow rate signal are acquired at location x1.

[0026] In order to illustrate the present invention, Figure 2 A graph showing the time curves of the regulated pressure signal and volumetric flow rate signal is presented. In this embodiment, the pressure p(t) is regulated using a periodic reference signal and has a sinusoidal curve.

[0027] In a pipeline network, a targeted pressure variation is introduced to allow fluid to propagate at a limited velocity (approximately 1000 m / s) and reach the leak point with a corresponding time delay. The pressure change at the leak point causes a change in the volumetric flow rate at that point. If the pressure in the pipeline increases or decreases, the volumetric flow rate also increases or decreases accordingly. This change can be determined by a flow measurement device. If the flow measurement device is also placed at location x1, it again determines the increased volumetric flow rate with a time delay. (t). In Figure 2 The volumetric flow rate signal with a time delay relative to the pressure signal p(t) can be observed. The curve is in sinusoidal form (t). Therefore, approximately two transport times occur in the pipeline path until the corresponding increase in volumetric flow rate can be measured at the point x1 where the pressure rise occurs. Therefore, the time difference Δt between the defined signal component of the pressure signal and the defined signal component of the volumetric flow rate signal (and...) Figure 2 In the case of Δt), the distance E1 between the leak point and the location x1 can be obtained from the time difference Δt. Figure 1 compared to).

[0028] If the measurement method is repeated at multiple measurement locations in a branch pipeline network, the location of the leak point can be determined by correlation.

[0029] Because the measured signal may be mixed with noise and superimposed with various interference signals, it is reasonable to apply a combined correlation method here. A lock-in amplifier is provided here, which makes the signal p(t) (=reference signal) and... (t) (= measurement signal) is multiplied. This eliminates random interference signals and amplifies the signal component associated with the reference signal. By adjusting the phase offset of the reference signal at the lock-in input, the output signal of the lock-in amplifier is maximized as long as the reference signal and the measurement signal are in phase. The phase offset is a measure of the distance between the leak point and the measurement location.

[0030] Alternatively, a method based on the identifiers of the dynamic system can be used, which can accurately estimate the dead time. This dead time corresponds exactly to the phase shift or delay described above.

Claims

1. A method for detecting leaks in a supply network having a piping system, wherein fluid is directed through the piping system, wherein, At N different locations (x1, x2, ... xN) in the pipeline system, the pressure (p(t)) and volumetric flow rate (t) of the fluid in the pipeline system are captured by measurement techniques at different times. (t)), The invention is characterized in that, at a first location (x1), the pressure in the pipeline system is adjusted using a predetermined first reference signal (M1) for a defined first duration (T1), and preferably, curves of the adjusted pressure signal and volumetric flow rate signal are acquired at the first location (x1), and, in the case of detecting the time difference (Δt1) between a defined signal component of the pressure signal and a defined signal component of the volumetric flow rate signal, a first distance (E1) between the leak point and the first location (x1) is derived from the time difference (Δt1).

2. The method according to claim 1, characterized in that, At a second location (x2), the pressure in the pipeline system is adjusted using a predetermined second reference signal (M2) that is the same as the first reference signal (M1) for a defined second duration (T2) that is equal to the first duration (T1). Preferably, the curves of the adjusted pressure signal and the volumetric flow rate signal are acquired at the second location (x2), and a second distance (E2) between the leak point and the second location (x2) is obtained from the time difference (Δt2) between the defined signal component of the pressure signal and the defined signal component of the volumetric flow rate signal. The method is repeated at other locations (x3, x4, ...), and the location of the leak point in the pipeline system is obtained from the multiple distances (E3, E4, ...) obtained by the method.

3. The method according to claim 1 or 2, characterized in that, The distance between the leak point and the location (x1, x2, ... xN) is obtained at different measurement time points (t1, t2, ... tM).

4. The method according to claim 2 or 3, characterized in that, At least some of the locations used to regulate the pressure in the piping system are different from the locations used to measure the pressure and volumetric flow rate of the fluid.

5. The method according to any one of claims 1 to 4, characterized in that, The pressure and volumetric flow rate of the fluid are captured by measurement techniques at different locations within the same pipe section.

6. The method according to any one of the preceding claims, characterized in that, The duration (Ti) for regulating the pressure in the piping system is at least partially consistent with the duration for measuring the pressure and volumetric flow rate of the fluid.

7. The method according to any one of the preceding claims, characterized in that, The signal used for pressure regulation can be a periodic signal with a predetermined amplitude, frequency, and phase, and the time difference between the pressure signal and the volumetric flow rate signal obtained at the corresponding location is the phase difference.

8. The method according to claim 7, characterized in that, In the case of a periodic adjustment signal, the phase between the pressure signal and the volumetric flow rate signal is affected by changing the frequency of the pressure signal.

9. The method according to any one of the preceding claims, characterized in that, The measured pressure signal is correlated with the measured volumetric flow rate signal.

10. The method according to any one of the preceding claims, characterized in that, To improve the signal-to-noise ratio, the duration for measuring the pressure and volumetric flow rate of the fluid should be selected as large as possible.

11. The method according to any one of the preceding claims, characterized in that, The amplitude and frequency of the adjustment signal are selected based on the characteristics of the pipeline system.

12. The method according to any one of the preceding claims, characterized in that, The measurement techniques for the pressure and volumetric flow rate of the fluid are captured and / or pressure regulation is controlled.

13. The method according to any one of claims 1 to 12, characterized in that, The supply network is a water distribution network, and the locations are feed points for allowing water to enter the pipeline system.

14. The method according to any one of claims 1 to 12, characterized in that, The supply network is a hydrogen distribution network, and the locations are feed points for introducing hydrogen into the pipeline system.

15. An apparatus (1) for detecting leaks in a supply network having a piping system, wherein fluid is directed through the piping system, the apparatus comprising: - A regulating device (2), the regulating device being configured to regulate the pressure of the fluid using a predetermined reference signal, - A computer-aided control unit (3) for controlling the device (2) used for regulation. - Capture system (4), which is capable of being connected to the piping system at a location (x1), and the capture system has a pressure sensor (4A) for capturing the pressure of the fluid by measurement technology and a volumetric flow sensor (4B) for capturing the volumetric flow rate of the fluid by measurement technology. - A processing unit (5), which is communicatively connected to at least the control unit (3) of the regulating device (2) and the capture system (4), and the processing unit is configured to determine the distance (E1) from the leak point, characterized in that, The curves of the regulated pressure signal and the volumetric flow rate signal acquired by means of the capture system (4) are compared, and the distance between the leak point and the location (x1) is derived from the time difference (Δt1) between the defined signal component of the pressure signal and the defined signal component of the volumetric flow rate signal.

16. A computer-aided processing unit (6) connected to at least one device (1) according to claim 15, and the processing unit is configured to implement the method according to any one of claims 1 to 14.

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