CN110848578B

CN110848578B - PDD model-based existing leakage positioning method for urban water supply pipe network

Info

Publication number: CN110848578B
Application number: CN201810951519.6A
Authority: CN
Inventors: 余健; 黄帆; 刘倍良
Original assignee: Hunan University
Current assignee: Hunan University
Priority date: 2018-08-21
Filing date: 2018-08-21
Publication date: 2021-07-30
Anticipated expiration: 2038-08-21
Also published as: CN110848578A

Abstract

An existing leakage positioning method for an urban water supply pipe network based on a PDD model. According to the method, firstly, the production and marketing difference of the pipe network needs to be analyzed, the actual production and marketing difference of the pipe network is compared with the expected production and marketing difference, and if the actual production and marketing difference exceeds the expected production and marketing difference, the existing leakage positioning is carried out on the pipe network. When the existing leakage positioning is carried out, the pipe network is subjected to hydraulic calculation according to the expected production and sales difference to obtain the pipe network condition under the expected production and sales difference. And taking the difference between the actual water supply quantity of the pipe network and the expected yield-sales difference water supply quantity as the superposed water quantity, superposing the superposed water quantity to the nodes of the expected yield-sales difference pipe network, and performing hydraulic calculation again to obtain the pressure value of each node. And finally, solving the minimum value of the target function by taking the square sum of the difference between the pressure value of the pressure monitoring point calculated by the superposed water amount and the pressure value of the actual monitoring point as an evaluation standard to obtain the existing leakage point. The invention can realize the quick positioning of the existing leakage, reduce the leakage detection time and solve the problem of the leakage storage of the pipe network.

Description

PDD model-based existing leakage positioning method for urban water supply pipe network

Technical Field

The invention belongs to the field of urban water supply pipe networks, relates to existing leakage positioning of a water supply pipe network, and particularly relates to an existing leakage positioning method of an urban water supply pipe network based on a pressure-driven hydraulic model (PDD model).

Background

The yield and sales difference is an important index for measuring the economic benefit of water supply enterprises, and is also the comprehensive reflection of the management service level of the water supply enterprises. The poor yield and sales are caused by various factors, and from the view of a water balance system of the international water coordination, the poor yield and sales can be divided into physical leakage of a pipe network, free water, recording errors, metering errors, water stealing and the like, wherein the leakage water is a main component of the poor yield and sales, and the reduction of the leakage water is a key for controlling the poor yield and sales. Leakage detection and repair are the most important mode for controlling the leakage of a pipe network, the first step is to adopt effective leakage detection measures to find out the specific position where the leakage occurs, and the leakage can be repaired and stopped in the next step. The research and development of leak detection technology, and the improvement of leak detection efficiency are one of the important directions in the field of leak control research, and the current common leak detection methods include a passive leak detection method and an active leak detection method. Passive leakage detection can only find a few leakage points seeping out of the ground, and the control effect on the total leakage water quantity of the pipe network is not high. The active leak detection method is to adopt various equipment instruments to analyze and detect the leakage condition of the underground pipe section, and compared with passive leak detection, the leakage condition which can not be detected by naked eyes can be detected, but the investment of the equipment is relatively high. In recent years, with the installation and improvement of a supervisory control and data acquisition (SCADA) system on a water supply network, many scholars at home and abroad are engaged in research and development of leakage detection and positioning of the water supply network mainly based on software. The method is characterized in that whether leakage occurs in a pipe network is judged and the position and the amount of leakage occurring are determined according to the change of pressure or flow values acquired by an SCADA system. The technology can improve the sensitivity and effectiveness of the leakage detection, can enable a water supply company to quickly respond after a leakage accident occurs, and has good application prospect.

Disclosure of Invention

In view of the above, the invention provides a PDD model-based existing leakage positioning method for an urban water supply network, aiming at the requirement of the water supply network on existing leakage positioning.

In order to achieve the purpose, the invention adopts the following steps:

step 1, carrying out production and marketing differential analysis to judge whether existing leakage positioning is needed

Calculating the actual production and sales rate of the existing pipe network according to the water supply and sales data of a water supply network in a partition metering area (DMA), comparing the actual production and sales rate with the expected production and sales rate, and if the actual production and sales rate exceeds the expected production and sales rate, performing existing leakage positioning; if not, positioning is not needed;

step 2, reducing the pipe network under the expected yield-sales difference rate

First, the water supply for the DMA zoned water supply network at the desired production and sales differential rate is calculated:

Q_q(1+ expected yield-to-sales ratio) × S

In the formula, Q_qThe water supply amount of the DMA subarea under the expected yield and sales rate is S, and the actual water sale amount of the DMA subarea is S;

secondly, with Q_qAs total water inflow flow of the subarea pipe network, distributing flow along the line according to actual water consumption condition of the pipe network, and calculating the flow at Q by controlling the most unfavorable water pressure_qObtaining the reduced water quantity and water pressure condition of the pipe network for the node flow and the water pressure of each node of the pipe network when the total water inflow flow is achieved;

step 3, calculating and positioning the superposed water volume

Subtracting the actual water supply amount of the DMA partition pipe networkDMA zoned water supply Q at expected differential production and sales rates_qAs the superposed water quantity Q_LNamely:

Q_Lactual pipe network water supply-Q_q

Step 4, positioning is carried out

Taking the flow and pressure of each node of the reduction pipe network as initial values of the existing leakage positioning calculation, and adding the water quantity Q_LSuperpose the node of reducing pipe network and carry out hydraulic calculation again, in order to make each node flow of pipe network after the stack and pressure can actually reflect current pipe network condition, reduce model calculation error, when carrying out the calculation of the water yield that adds, adopt the pressure drive hydraulic model that more laminates reality to calculate, promptly:

q_i-leak＝c_iQ_i ^reqH_i ^1.18

in the formula:

q_i-leak-background leakage amount (L/s) for node i;

Q_i ^req-node nominal flow (L/s) of node i;

c_i-loss factor.

In the formula:

Q_i ^use-water consumption (L/s) by the user of node i;

Q_L-the burst volume (L/s) of the burst node;

H_i-the actual water pressure (m) of the node i;

H_max-nominal water pressure (m) of node i;

H_min-critical water pressure (m) of node i;

when the node has no additional pipe explosion, Q_LIs 0; calculate Q_LThe pressure values of all the nodes are superposed at different nodes;

finally, the pressure value H of the pressure monitoring point calculated by the objective function according to the superposed water quantity_qiPressure with actual monitoring pointValue H_iThe sum of the squares of the differences was used as an evaluation criterion, namely:

wherein n is the total number of the pressure monitoring points;

the invention has the beneficial effects that: the invention can realize the positioning of the existing leakage points exceeding the expected yield and sales rate, reduce the leakage detection time, reduce the leakage stock of the pipe network, and reduce the waste of water resources and the loss of water supply enterprises.

Drawings

FIG. 1 is a small DMA pipe network in G

FIG. 2 is a diagram of the positioning result of the existing leakage

FIG. 3 is a flow chart of an existing leakage location embodiment

Detailed Description

In order that the technology of the present invention may be readily understood, a more particular description of embodiments of the present invention will be rendered by reference to the appended drawings, which are illustrated in the appended drawings.

In the example, a small DMA pipe network in G city is taken as a research object, and as shown in FIG. 1, the pipe network comprises 16 common water consumption nodes, 18 pipelines, 1 pressure monitoring point, 1 water inlet, and measurement data of pressure and flow; the DMA pipe network is known to sell water in 8408m in month 4³The water supply amount is 27254m³Total head of water inlet is 32.34mH₂O, loss coefficient of 0.0272;

Calculating the actual yield and sales rate of the existing pipe network to be 69% according to the water supply and sales data of the small water supply pipe network, and if the expected yield and sales rate is 20%, the yield and sales rate of the small DMA pipe network far exceeds the expected yield and sales rate, and the existing leakage needs to be positioned;

step 2, reducing the pipe network under the expected production and marketing difference

The small DMA pipe network is subjected to leakage positioning according to the step 1 after judgment, and the yield and the sales difference rate expected in the step 1 are20%, the water supply amount under the expected yield and sales rate is 3.65L/s according to the water sales of 4 months, and the water inlet pressure of the pipe network under the expected yield and sales rate is calculated to be 33.82mH by flow distribution and using the worst point water pressure as a constraint condition₂O, the flow pressure of each node of the pipe network before and after reduction is shown in a graph 1:

TABLE 1

Step 3, calculating and positioning the superposed water volume

The actual water supply of the small DMA pipe network is 10.51L/s, when the expected yield and sales difference rate is 20 percent, the water supply Qq of the pipe network is 3.65L/s, and the positioning superposed water quantity Q_L6.86L/s, the positioning known data are shown in Table 2;

TABLE 2

Quantity of water sold per month (L/s)	3.04
		Expected rate of differential production and sales	20％
Expected yield and sales difference rate water supply (L/s)	3.65
		Reducing pipe network inlet pressure (mH2O)	33.82
Positioning superimposed water volume (L/s)	6.86
		Loss coefficient of leakage	0.0272
Monitoring point pressure (mH2O)	26.087

Step 4, positioning is carried out

Taking the node flow in the reduction pipe network in the step 2 as an initial population, introducing the node flow into a traditional hydraulic model, solving through EPANET to obtain the pressure value of each node, and calculating the actual water consumption of each node by using a pressure driving model;

the superposed water quantity Q_LThe calculated values and the actual values are close to each other and have high positioning accuracy, the result is shown as figure 2, and the actual leakage points are confirmed to be close to the nodes with the node ID of 365 through leakage detection.

TABLE 3

Claims

1. A PDD model-based existing leakage positioning method for an urban water supply pipe network is characterized by comprising the following steps:

Calculating the actual production and sales rate of the existing pipe network according to the water supply and sales data of the DMA subarea water supply pipe network, comparing the actual production and sales rate with the expected production and sales rate, and if the actual production and sales rate exceeds the expected production and sales rate, performing existing leakage positioning; if not, positioning is not needed;

Q_q(1+ expected yield-to-sales ratio) × S

step 3, calculating and positioning the superposed water volume

Subtracting the water supply Q of the DMA subarea under the expected yield and sales difference rate from the actual water supply of the DMA subarea pipe network_qAs the superposed water quantity Q_LNamely:

Q_Lactual pipe network water supply-Q_q

Step 4, positioning is carried out

q_i-leak＝c_iQ_i ^reqH_i ^1.18

in the formula:

q_i-leak-background leakage amount (L/s) for node i;

Q_i ^req-node nominal flow (L/s) of node i;

c_i-a loss factor;

in the formula:

Q_i ^use-water consumption (L/s) by the user of node i;

Q_L-the burst volume (L/s) of the burst node;

H_i-the actual water pressure (m) of the node i;

H_max-nominal water pressure (m) of node i;

H_min-critical water pressure (m) of node i;

finally, the pressure value H of the pressure monitoring point calculated by the objective function according to the superposed water quantity_qiAnd the pressure value H of the actual monitoring point_iThe sum of the squares of the differences was used as an evaluation criterion, namely:

wherein n is the total number of the pressure monitoring points.