A water quality evaluation method for multi-source water pipe network based on node water age

Abstract

The present invention discloses a method for evaluating the water quality of a multi-water source network based on node water age, comprising the following steps: screening out non-zero data on water output; dividing the single water supply area of ​​each water source into the mixed water supply area of ​​multiple water sources; obtaining the weight value of the number of nodes to obtain the comprehensive weighted water age of the network; performing water age simulation analysis on a given network to obtain the node water age values ​​of all water-using nodes, and calculating the flow-weighted average water age by region; repeating the above steps to draw a comprehensive water age chart of the network area under different schemes to evaluate the overall water quality of the network. The method performs source tracing analysis on the multi-water source water supply network under different working conditions, divides the single and multi-water source mixed water supply ranges, and then calculates the comprehensive weighted water age values ​​under the corresponding working conditions, and finally compares the effects of different working conditions, which can provide a reference evaluation basis for the regional water age changes that may be caused by the water pressure regulation of water service personnel, thereby ensuring the safety of drinking water in the mixed water supply range.

Description

Technical Field

[0001] The invention relates to a water quality evaluation method for a multi-water source water supply network, and in particular to a method for comparatively evaluating water quality conditions corresponding to different water pressure regulation schemes of a multi-water source water supply system based on node water age. Background Art

[0002] In the process of urban-rural integration, the transition from independent water supply mode to multi-source water supply mode is an important trend in the development of urban infrastructure. Compared with independent water supply network, multi-source water supply system has the characteristics of long pipelines, multiple water sources and more complicated operation. The biggest difference is that there must be one or more mixed water supply areas in the multi-source water supply network system.

[0003] Using the built-in functions of EPANET software, the water supply network model can be traced and analyzed for water age. The mixed area and the terminal position of the network are relatively far away from the water source, and there are problems such as too long water age and low residual chlorine. For the method of using water age to characterize the water quality in the water supply network, there are methods that select the absolute value of node water age and the weighted average of node water age relative to node flow as indicators to evaluate the water quality in the network, and there are also methods that use comprehensive water age index for multi-objective optimization scheduling under different zoning methods. Considering the special water supply distribution zoning of multi-source networks, and the importance of different water nodes and pipe sections in urban water supply network modeling, proposing a suitable water quality evaluation method will also help to carry out hydraulic scheduling and improve the comprehensive water quality of multi-source networks. Summary of the invention

[0004] The purpose of the present invention is to evaluate the comprehensive water quality of a multi-source water supply network under changes in mixed areas, and to provide a multi-source water supply network water quality evaluation method based on node water age, which can help water workers more effectively regulate the factory pressures of multiple water plants and adjust the geographical locations of mixed areas in the multi-source water supply network, thereby improving the comprehensive water quality of the multi-source water supply network.

[0005] To achieve the above-mentioned purpose, the present invention provides a method for evaluating water quality of a multi-source pipe network based on node water age, comprising the following steps:

[0006] (1) Conduct water source node tracing analysis on a given pipe network to obtain the water volume proportion data of each water consumption node from different water sources, and filter out non-zero water volume data;

[0007] (2) Determine the water supply range of each water source based on the non-zero water volume percentage data screened out, and divide the water supply area of ​​each water source into a single water supply area and a multi-source mixed water supply area;

[0008] (3) Perform water age simulation analysis on a given pipe network to obtain the node water age values ​​of all water-using nodes, and calculate the flow-weighted average water age by region;

[0009] (4) According to the zoning, the number of water use nodes in each area and the number of water use nodes in the entire pipe network are determined, and the weight value of the number of nodes is obtained. The comprehensive weighted water age of the pipe network area is obtained by combining the flow-weighted average water age;

[0010] (5) Repeat the above steps with different pressure differences to analyze the flow-weighted average water age in the mixed water supply area, and draw a comprehensive water age chart for the pipe network area under different schemes to evaluate the overall water quality of the pipe network.

[0011] In the above steps, the method conducts source tracing analysis and water age simulation analysis on the water supply network under the control of different water source total head combination schemes, divides the water supply area, and obtains the regional comprehensive weighted water age by calculating the water volume weighted water age and the node quantity weight value of each water supply area, and then evaluates the comprehensive water quality of the water supply network. The method finally judges the water source total head combination scheme with the optimal comprehensive water quality based on the regional comprehensive weighted water age value.

[0012] Step (1) includes the following steps:

[0013] 1.1) Import the given pipe network model into EPANET software and set the total water head value of each water source node;

[0014] 1.2) Set the type of water quality simulation to source analysis, and set the total duration of water quality simulation to t hours;

[0015] 1.3) Set each water source node as the target node for tracking in turn, and obtain the water volume share data of each water-using node at time t;

[0016] 1.4) The water consumption nodes with water consumption of "0" in the data are screened out, and the non-zero water consumption data are retained.

[0017] The total duration of water quality simulation t hours set in step (1) has different values ​​for water supply networks of different complexity. The value should be selected so that the simulation results can show stable periodic changes, and is generally not less than the set total duration of the time series. The value of t can be set in steps of 24 hours and is greater than or equal to 168 hours (7 days).

[0018] In step (2), the water volume ratio threshold is set to w% according to the actual situation. If the water volume ratio of the water-using node is higher than w%, it is classified as the water supply area of ​​the corresponding water source node; otherwise, it is classified as a multi-source mixed water supply area.

[0019] In step (3), the given pipe network model and parameters in step (1) are kept unchanged, the type of water quality simulation is changed to water age analysis, and the total duration of water quality simulation is set to t hours, and the node water age of each water-using node at time t is obtained.

[0020] In step (3), water age simulation analysis is performed on a given pipe network. The initial data obtained by water age simulation using EPANET software is the node water age. The node water age T i The formula is:

[0021]

[0022] Where: is the amount of water from the water source to node i through the nth water supply path; is the time it takes for water to be transported from the water source along the nth water supply path to node i; U i is the set of all water source supply paths that flow to node i.

[0023] In step (3), the water-weighted water age T of different regions is calculated by using the regional division in step (2) and the water age of nodes in the corresponding range. m , the formula is:

[0024]

[0025] Where: q i is the water volume of water-using node i in the mth region; T i is the node water age of each water-using node in the mth area.

[0026] In step (4), the number of water-using nodes in each area and the number of water-using nodes in the entire network are determined, and the node number weight value η m The formula is:

[0027]

[0028] Where: n m is the number of water-using nodes in the mth area; N is the total number of water-using nodes in all areas of the pipe network.

[0029] In step (4), the regional comprehensive weighted water age assessment (T z ) is:

[0030] T z =∑η m T m

[0031] In step (5), the above steps are repeated using different water source total head value combination schemes to obtain the flow-weighted average water age T in each area of ​​the pipe network under different schemes. m and regional comprehensive water age T z . T z The smaller it is, the better the overall water quality of the multi-source pipe network is. Among the different schemes, the first choice is the mixed water supply area T m Minimum, secondary regional comprehensive water age T zThe smallest corresponding solution is the best, which can ensure the water quality of the mixed water supply area while preventing the water quality of the overall pipe network from deteriorating.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention takes into account the importance of different water use nodes and the distribution density of drinking water users in different areas of the city during modeling. The present invention proposes a water quality evaluation method for a multi-source pipe network based on node water age, which obtains the optimal water pressure regulation scheme by taking the flow-weighted average water age and the node quantity weights in different areas as the target, and taking the flow-weighted average water age and the comprehensive weighted water age of the mixed water supply area as the target.

[0034] The method of the present invention conducts source tracing analysis on multi-source water supply networks under different working conditions, divides the scope of single and multi-source mixed water supply, then calculates the comprehensive weighted water age value under the corresponding working conditions, and finally compares the effects of different working conditions. It can provide a reference evaluation basis for water workers to adjust the regional water age changes that may be caused by water pressure, thereby ensuring the safety of drinking water in the mixed water supply range. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a flow chart of the method of the present invention;

[0036] Figure 2 A schematic diagram of a pipe network in an embodiment;

[0037] Figure 3 It is the regional comprehensive weighted water age histogram of different water source total head combination schemes;

[0038] Figure 4 Schematic diagram of water supply zoning for different optimal water pressure difference schemes. DETAILED DESCRIPTION

[0039] The drawings are for illustrative purposes only and should not be construed as limiting the present patent;

[0040] The present invention will be described in detail below with reference to the various embodiments shown in the accompanying drawings.

[0041] like Figure 1 As shown, a water quality evaluation method for a multi-water source network based on node water age of the present invention comprises the following steps:

[0042] (1) Conduct water source node tracing analysis on a given pipe network to obtain the water volume proportion data of each water consumption node from different water sources, and filter out non-zero water volume data;

[0043] (2) Determine the water supply range of each water source based on the non-zero water volume percentage data screened out, and divide the water supply area of ​​each water source into a single water supply area and a multi-source mixed water supply area;

[0044] (3) Perform water age simulation analysis on a given pipe network to obtain the node water age values ​​of all water-using nodes, and calculate the flow-weighted average water age by region;

[0045] (4) According to the zoning, the number of water use nodes in each area and the number of water use nodes in the entire pipe network are determined, and the weight value of the number of nodes is obtained. The comprehensive weighted water age of the pipe network area is obtained by combining the flow-weighted average water age;

[0046] (5) Repeat the above steps with different pressure differences to analyze the flow-weighted average water age in the mixed water supply area, and draw a comprehensive water age chart for the pipe network area under different schemes to evaluate the overall water quality of the pipe network.

[0047] The step (1) comprises the following steps:

[0048] 1) Import the given pipe network model into EPANET software and set the total water head value of each water source node;

[0049] 2) Set the type of water quality simulation to source tracing analysis, and set the total duration of water quality simulation to t hours;

[0050] 3) Set each water source node as the target node for tracking in turn, and obtain the water volume share data of each water-using node at time t.

[0051] 4) The water consumption nodes with water consumption of "0" in the data are screened out, and the non-zero water consumption data are retained.

[0052] The total duration of water quality simulation t hours set in step (1) has different values ​​for water supply networks of different complexity. The value should be selected so that the simulation results can show stable periodic changes, and is generally not less than the set total duration of the time series. The value of t can be set in steps of 24 hours and is greater than or equal to 168 hours (7 days).

[0053] In step (2), the water volume ratio threshold is set to w% according to the actual situation. If the water volume ratio of the water-using node is higher than w%, it is classified as the water supply area of ​​the corresponding water source node; otherwise, it is classified as a multi-source mixed water supply area.

[0054] In step (3), the given pipe network model and parameters in step (1) are kept unchanged, the type of water quality simulation is changed to water age analysis, and the total duration of water quality simulation is set to t hours, and the node water age of each water-using node at time t is obtained.

[0055] In step (3), water age simulation analysis is performed on a given pipe network. The initial data obtained by water age simulation using EPANET software is the node water age. The node water age T i The formula is:

[0056]

[0057] Where: is the amount of water from the water source to node i through the nth water supply path; is the time it takes for water to be transported from the water source along the nth water supply path to node i; U i is the set of all water source supply paths that flow to node i.

[0058] In step (3), the water-weighted water age T in different regions is calculated by using the regional division in step (2) and the water age of the nodes in the corresponding range. m , the formula is:

[0059]

[0060] Where: q i is the water volume of water-using node i in the mth region; T i is the node water age of each water-using node in the mth area.

[0061] In step (4), the number of water-using nodes in each area and the number of water-using nodes in the entire network are determined, and the node number weight value η m The formula is:

[0062]

[0063] Where: n m is the number of water-using nodes in the mth area; N is the total number of water-using nodes in all areas of the pipe network.

[0064] In step (4), the regional comprehensive weighted water age assessment (T z ) is:

[0065] T z =∑η m T m

[0066] In step (5), the steps described in claims 2 to 7 are repeated using different water source total head value combination schemes to obtain the flow-weighted average water age T in each area of ​​the pipe network under different schemes. m and regional comprehensive water age T z . T z The smaller it is, the better the overall water quality of the multi-source pipe network is. Among the different schemes, the first choice is the mixed water supply area T m Minimum, secondary regional comprehensive water age T z The smallest corresponding solution is the best, which can ensure the water quality of the mixed water supply area while preventing the water quality of the overall pipe network from deteriorating.

[0067] like Figure 2As shown, the specific implementation effect of the present invention is illustrated by taking the water supply network of Huzhou City as an example. The network model has 15,891 water nodes, 16,579 pipe sections, and 2 water sources. The comprehensive water quality of the network under different pressure difference schemes includes the following steps:

[0068] Step 1: First, import the pipe network model into the EPANET software, set the total head value of the water source node numbered R-1 to 33, and the total head value of the water source node numbered R-3 to 37. Secondly, set the total duration of the water quality simulation to 168 hours, the hydraulic step length to 1 hour, and the water quality simulation step length to 15 minutes. Then, set the water quality simulation type to trace analysis (trace), and set the water source node numbered R-3 as the target node for tracing, and obtain the percentage of water consumption of each water-using node in the pipe network that comes from the water source node R-3 when the water quality simulation is stable at 168 hours; set the water source node numbered R-1 as the target node for tracing again, and also obtain the percentage of water consumption of each water-using node in the pipe network that comes from the water source node R-1 at 168 hours. Finally, the total head combination of the water source is 33-37, that is, the water volume proportion data of each water-using node in the pipe network at 168 hours under the scheme with a pressure difference of 4. Because the model is relatively simple, we can only trace back one of the water source nodes to obtain the water volume share data of the water use nodes in the entire network. It is proposed that the water use nodes with water consumption ≥ 0.005 LPS are valid nodes, and finally 15,535 valid water use nodes are screened.

[0069] Step 2: First, the threshold of water supply range zoning is set to 80%, and it is artificially stipulated that when no less than 80% of the water consumption of a node comes from a certain water source, the node is considered to belong to the single water supply area of ​​this water source; secondly, the water nodes that do not belong to the single water supply area of ​​a certain water source are grouped into a mixed water supply area. So far, the pipe network is divided into three areas, namely the single water supply area of ​​water source node R-1, the single water supply area of ​​water source node R-3, and the mixed water supply area, which are respectively called "Area 1", "Area 2" and "Area 3".

[0070] Step 3: Determine the number of water nodes n1, n2, n3 in "Zone 1", "Zone 2" and "Zone 3" and the number of water nodes N in the entire network, and obtain the node quantity weights η1, η2, η3. Then, according to the water volume obtained in step 3, the weighted water age T1, T2, T3 is used to obtain the regional comprehensive weighted water age T z ;

[0071] Step 4: Change the water quality simulation type to water age analysis (age). The total duration of the water quality simulation is 168 hours. Perform water quality analysis on the water supply network to obtain the water age T of each water consumption node at 168 hours. iThen, according to the water age data of water use nodes divided into three areas in the second step, the water-weighted water ages T1, T2, and T3 of water use nodes in the "1st area", "2nd area", and "3rd area" are calculated.

[0072] Step 5: Repeat steps 1 to 4 using different total head difference combinations. In this example, there are 5 pressure difference combinations, the total head value combination of water source nodes R-1 and R-3, and the corresponding node quantity weight value η m and flow-weighted average water age T m The calculation results are shown in Table 1. Draw the comprehensive weighted water age diagram of different scheme areas as shown in Figure 3 According to the T1 result analysis, it is preliminarily determined that the ΔH=2 scheme is better, T1=29.54h; the regional comprehensive water age corresponding to this scheme is 12.23h, and it is finally determined that ΔH=2 under the optimal scheme.

[0073] Table 1 Water age evaluation results of different pipe network areas under different schemes

[0074]

Claims

1. A water quality evaluation method for a multi-source water network based on node water age, characterized in that: The following steps are involved: (1) Conduct water source node tracing analysis on a given pipe network to obtain the water volume proportion of each water consumption node from different water sources and filter out non-zero water volume data; (2) Determine the water supply range of each water source based on the non-zero water volume percentage data screened out, and divide the water supply area of ​​each water source into a single water supply area and a multi-source mixed water supply area; (3) Perform water age simulation analysis on a given pipe network to obtain the node water age values ​​of all water-using nodes, and calculate the flow-weighted average water age by region; Node water age T i The formula is: Where: is the amount of water from the water source to node i through the nth water supply path; is the time it takes for water to be transported from the water source along the nth water supply path to node i; U i is the set of all water supply paths that flow to node i; (4) According to the zoning, the number of water use nodes in each area and the number of water use nodes in the entire pipe network are determined, and the weight value of the number of nodes is obtained. The comprehensive weighted water age of the pipe network area is obtained by combining the flow-weighted average water age; (5) Repeat the above steps with different pressure differences to analyze the flow-weighted average water age in the mixed water supply area, and draw a comprehensive water age chart for the pipe network area under different schemes to evaluate the overall water quality of the pipe network.

2. The water quality evaluation method for a multi-source pipe network based on node water age according to claim 1 is characterized in that: Step (1) specifically includes: (1.1) Import the given pipe network model into EPANET software and set the total water head value of each water source node; (1.2) Set the type of water quality simulation to source analysis and set the total duration of water quality simulation to t hours; (1.3) Set each water source node as the target node for tracking in turn, and obtain the water volume share data of each water-using node at time t; (1.4) The water consumption nodes with water consumption of "0" in the data are screened out, and the non-zero water consumption data are retained.

3. The water quality evaluation method for a multi-source pipe network based on node water age according to claim 1 is characterized in that: In step (2), the water supply range of each water source is determined based on the non-zero water volume percentage data screened out, and the water supply area of ​​each water source is divided into a single water supply area and a multi-source mixed water supply area, specifically including: According to the actual situation, the water volume ratio threshold is set to w%. If the water volume ratio of the water-using node is higher than w%, it is classified into the water supply area of ​​the corresponding water source node; otherwise, it is classified into the multi-source mixed water supply area.

4. The water quality evaluation method for a multi-source pipe network based on node water age according to claim 1 is characterized in that: In step (3), water age simulation analysis is performed on a given pipe network to obtain node water age values ​​of all water-using nodes, specifically including: Keep the given pipe network model with the total water head value of each water source node unchanged, set the type of water quality simulation to water age analysis, and set the total duration of water quality simulation to t hours, and obtain the node water age of each water-using node at time t.

5. The water quality evaluation method for a multi-source pipe network based on node water age according to claim 1 is characterized in that: In step (3), the flow-weighted average water age T m The formula is: Where: q i is the water volume of water-using node i in the mth region; T i is the node water age of each water-using node in the mth area.

6. The water quality evaluation method for a multi-source pipe network based on node water age according to claim 1 is characterized in that: In step (4), the node quantity weight η m The formula is: Where: n m is the number of water-using nodes in the mth area; N is the total number of water-using nodes in all areas of the pipe network.

7. The water quality evaluation method for a multi-source pipe network based on node water age according to claim 1 is characterized in that: In step (4), the comprehensive weighted water age of the pipe network area T z The formula is: T z =∑η m T m Among them, T m is the flow-weighted average water age.

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