CN113435040B - Inversion method of burst diameter based on transient flow - Google Patents

Abstract

The invention relates to a method for realizing the inversion of the diameter of a burst pipe, in order to realize the location of the burst pipe in a pipe network, a high-frequency SCADA system is applied to monitor a pressure abnormal signal in the pipe network, and on the basis of the location of the burst pipe, a total monitoring signal is decomposed into branch monitoring signals from each propagation path according to the propagation characteristics of transient flow; inverting the propagation path and characteristics of the transient flow, namely inverting the local loss and the friction loss in the original propagation process to obtain the reciprocal of the local loss and the friction loss, converting the reciprocal of the local loss and the friction loss into gain, inverting the excitation signals from each path, and superposing the excitation signals to form a total inversion excitation signal; and according to the relation between the detonation excitation signal and the detonation diameter, the excitation signal takes the maximum amplitude, the detonation diameter takes the maximum value, and the detonation diameter is calculated. The comparison of the diameter of the detonation calculated by the method with the actual diameter of the detonation and the instantaneous flow attenuation method proves that the positioning precision of the method is higher, and the method can effectively solve the problem of the diameter inversion of the detonation.

Description

Inversion method of burst diameter based on transient flow

technical field

The invention relates to a method for inversion of the diameter of a burst pipe, belonging to the field of engineering, in particular to a method for inversion of the diameter of a burst pipe based on a transient flow.

Background technique

The water supply network is an important part of the urban infrastructure and is called the lifeline of the city. When a pipe burst occurs, it is necessary to provide decision-making for burst pipe repair based on the burst pipe information. In recent years, SCADA systems have been widely introduced into the water supply network to monitor flow and pressure in real time. There are many methods for locating burst pipes using monitoring data. However, the area of burst pipes cannot be inferred, which brings certain difficulties to the decision-making of burst pipe repairs. . Therefore, it is of great significance to realize the inversion of the burst diameter.

In recent years, high-frequency pressure monitoring in the SCADA system has been introduced into the water supply pipe network. The transient flow monitored by the system can be used to accurately locate the complex pipe network, but it is difficult to infer the burst diameter information. Therefore, it is necessary to study an inversion method for the diameter of the burst pipe to provide the decision of the burst pipe repair.

The transient flow monitored by the SCADA system is the transient flow excited by the burst pipe that propagates through multiple paths to the monitoring point and is superimposed. There are local losses and friction losses during the propagation. Based on the location of the burst pipe, the invention reverses the propagation path, and replaces the two losses with two gains. The transient current propagates from the monitoring point to the burst pipe point through multiple paths to form an excitation signal after superposition. The corresponding relationship of the pipe diameter is used to calculate the burst pipe diameter.

SUMMARY OF THE INVENTION

Aiming at the problem that the diameter of the burst pipe in the water supply pipe network is difficult to invert, the invention proposes a burst pipe diameter inversion method based on transient flow on the basis of the location of the burst pipe, which effectively realizes the inversion of the burst pipe diameter in the water supply pipe network. For this reason, the technical scheme of the present invention is as follows:

A method for inversion of burst diameter based on transient flow, the steps are as follows:

S1. According to the propagation characteristics of the transient flow, the total monitoring signal is decomposed into branch monitoring signals from each propagation path;

S2. Reverse the propagation path and characteristics of the transient flow to invert the excitation signal;

S3. Calculate the diameter of the burst tube according to the relationship between the burst tube excitation signal and the burst tube diameter.

Further, in step S1, the specific method for decomposing the total monitoring signal is:

According to the propagation theory of transient current, the propagation transient current signal in each propagation path from the pipe burst point to the monitoring point is calculated, which is called the branch analog signal, and it is superimposed to form a total analog signal, which is called the total analog signal, The monitoring signal amplitude from each propagation path can be expressed as:

In formula (1), k is the propagation path number of the transient flow, E _k (t) is the amplitude of the branch analog signal at time t, M(t) is the amplitude of the total monitoring signal at time t, ε _k ( t) is the proportion of monitoring signals in the k-th path at time t.

Further, in step S2, the specific method of inverting the excitation signal is:

The signal in each path is propagated from the monitoring point to the burst point in the reverse direction of the original path, and the reciprocal of the local loss and frictional loss in the original propagation process is taken as the gain, and the excitation signal amplitude from each path is expressed as The formula is:

In formula (2), T _k is the propagation time of the transient flow on the k-th path, A _ki is the transmission or reflection coefficient of the i-th node, R _kj is the friction factor per unit length of the j-th pipe section, and e ^{-Rkj is} the The friction loss per unit length of the j-section pipe, L _kj is the length of the j-th pipe section.

The excitation signals from each path are superimposed, and the superimposed signal is the total excitation signal, and its amplitude expression is:

Further, in step S3, the concrete method that calculates the diameter of burst pipe is:

Considering the surface of the squib as a circle, according to the relationship between the excitation signal and the diameter of the squib, the excitation signal takes the maximum amplitude, and the squib diameter takes the maximum value, then the expression is:

In formula (4), _Imax is the maximum amplitude of the excitation signal, μ is the squib coefficient, and D is the squib diameter.

The burst diameter can be calculated by formula (4).

Description of drawings

Figure 1 is a schematic diagram of the experimental pipe network;

Fig. 2 is the overall monitoring signal curve diagram;

Fig. 3 is the total excitation signal curve diagram of inversion;

Figure 4 is a flow chart of the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the following embodiments by no means limit the present invention.

In the following, the diameter inversion of the burst pipe is realized in the experimental pipe network, and the specific operation steps are as follows:

S1, monitoring signal decomposition

The experimental equipment mainly includes: water pump, water tank, high-frequency pressure sensor (3), DN100, DN50, DN25 steel pipe, DN50 PVC pipe, water valve. Each pipe section is combined into a pipe network with two rings. 10000Hz. Number each node in the pipe network with a letter "B" and a number, for example: B1, B5, B10. The number of each pipe segment is numbered with a letter "T" and the number number of the nodes at both ends of the pipe segment, for example: T2-3, T10-13 (Figure 1). In the experimental pipe network, by quickly opening the water valve, a pipe burst event was created, the pressure signals before and after the event were monitored (Fig. 2), and the burst pipe location method based on transient flow was used to locate the pipe burst point on the T9-10 pipe section and 2.3m away from the B9 node.

According to the propagation theory of transient current, the propagation transient current signal in each propagation path from the pipe burst point to the monitoring point is calculated, which is called the branch analog signal, and it is superimposed to form the total analog signal, which is called the total analog signal, The monitoring signal amplitude from each propagation path can be expressed as:

In formula (1), k is the propagation path number of the transient flow, E _k (t) is the amplitude of the branch analog signal at time t, M(t) is the amplitude of the total monitoring signal at time t, ε _k ( t) is the proportion of monitoring signals in the k-th path at time t.

S2, excitation signal inversion

The signal in each path is propagated from the monitoring point to the pipe burst point in the reverse direction of the original path, and the reciprocal of the local loss and frictional loss in the original propagation process is taken as the gain, and the excitation signal amplitude from each path is expressed as The formula is:

In formula (2), T _k is the propagation time of the transient flow on the k-th path, A _ki is the transmission or reflection coefficient of the i-th node, R _kj is the friction factor per unit length of the j-th pipe section, and e ^{-Rkj is} the The friction loss per unit length of the j-section pipe, L _kj is the length of the j-th pipe section.

The excitation signals from each path are superimposed, and the superimposed signal is the total excitation signal, and its amplitude expression is:

After back-propagating the monitoring signal from each propagation path obtained in step S1, use formula (2) to obtain the excitation signal from each path, and then use formula (3) to obtain the total excitation signal (Fig. 3).

S3. Calculate the diameter of the burst pipe

Considering the surface of the squib as a circle, according to the relationship between the excitation signal and the diameter of the squib, the excitation signal takes the maximum amplitude, and the squib diameter takes the maximum value, then the expression is:

In formula (4), _Imax is the maximum amplitude of the excitation signal, μ is the squib coefficient, and D is the squib diameter.

Taking the maximum amplitude (1.617Mpa) in Figure 3, the diameter of the squib can be calculated to be 32.92mm by formula (4).

Table 1: Comparison table of inversion results of the present invention and transient flow attenuation method burst diameter

As can be seen from Table 1, there is an absolute error of 0.92 mm and a relative error of 2.88% in the inversion of the squib diameter of the present invention; The relative value is increased by 14.12%; in conclusion, the absolute error and relative error of the inversion of the diameter of the burst pipe in the present invention are small, and the problem that the diameter of the burst pipe in the pipe network is difficult to invert is solved.

Claims (1)

1. based on the inversion method of burst diameter of transient flow, it is characterized in that, step is as follows: S1. According to the propagation characteristics of the transient flow, decompose the total monitoring signal into branch monitoring signals from each propagation path. The specific method is as follows: According to the propagation theory of transient current, the propagation transient current signal in each propagation path from the pipe burst point to the monitoring point is calculated, which is called the branch analog signal, and it is superimposed to form a total analog signal, which is called the total analog signal, Then the monitoring signal amplitude from each propagation path can be expressed as:

In formula (1), k is the propagation path number of the transient flow, E _k (t) is the amplitude of the branch analog signal at time t, M(t) is the amplitude of the total monitoring signal at time t, ε _k ( t) is the proportion of the monitoring signal in the k-th path at time t; S2. Reverse the propagation path and propagation characteristics of the transient flow to invert the excitation signal. The specific method is as follows: The signal in each path is propagated from the monitoring point to the pipe burst point in the reverse direction of the original path, and the reciprocal of the local loss and frictional loss in the original propagation process is taken as the gain, and the excitation signal amplitude from each path is expressed as The formula is:

In formula (2), T _k is the propagation time of the transient flow on the k-th path, A _ki is the transmission or reflection coefficient of the i-th node, R _kj is the friction factor per unit length of the j-th pipe section, e ^{− Rkj} is the friction loss per unit length of the jth pipe section, _Lkj is the length of the jth pipe section, The excitation signals from each path are superimposed, and the superimposed signal is the total excitation signal, and its amplitude expression is:

S3. Calculate the diameter of the burst tube according to the relationship between the excitation signal of the burst tube and the diameter of the burst tube. The specific method is: Considering the surface of the squib as a circle, according to the relationship between the excitation signal and the diameter of the squib, the excitation signal takes the maximum amplitude, and the squib diameter takes the maximum value, then the expression is:

In formula (4), _Imax is the maximum amplitude of the excitation signal, μ is the squib coefficient, and D is the squib diameter.

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