Optimized scheduling method and system based on water pump parallel operation characteristic curve

Abstract

The invention discloses an optimal scheduling method and system based on a water pump parallel operation characteristic curve, relates to the technical field of urban water supply and drainage, and solves the problems that an existing scheduling model is difficult to solve and insufficient in model interpretability. An efficient area of a single pump is calculated based on the single-pump characteristic curve, a multi-pump parallel operation characteristic curve is constructed based on the single-pump characteristic curve and the pipeline water head energy loss, and an efficient area of multi-pump parallel operation is calculated based on the multi-pump parallel operation characteristic curve; constructing an urban water supply scheduling planning model by taking the minimum number of switching times of the pump set modes as an objective function and taking a constraint function that only one pump set mode can be selected at any moment and the selected pump set mode runs in a high-efficiency area, and solving to obtain pump set matching; working conditions of all pumps in pump set matching are calculated according to the required water supply pressure and the required total water supply amount; a step-by-step solving strategy is adopted, a water pump parallel efficient area is established firstly, the solving range is narrowed, and the problem is solved.

Description

Technical Field

[0001] The invention relates to the technical field of urban water supply and drainage, and more specifically, to an optimization scheduling method and system based on a water pump parallel operation characteristic curve. Background Art

[0002] The water supply pump station is the last checkpoint for supplying water to end users, and it needs to meet the process and head required for its service scope. The traditional operation method is for the dispatcher to adjust the water pump unit based on experience after receiving the dispatch instruction for the current period. This method is suitable for the scenario where the water supply unit has a simple structure and stable water demand. However, with the increase in urban water demand and the diversification of water demand units, the current water supply pump unit is often composed of multiple pumps of different types and powers, and the water demand also shows obvious time-varying, seasonal, and other sudden events or environmental factors. In order to optimize the dispatch of water supply pump stations more scientifically and reduce the comprehensive energy consumption of water supply pump units, it is necessary to establish a mathematical model to optimize the dispatch of water supply pump stations.

[0003] The essence of water supply pump station scheduling optimization is to solve the mixed integer nonlinear programming (MINLP) problem formed by considering discrete variables (pump start and stop), continuous variables (pump frequency conversion) and various constraints faced in actual operation. The difficulty in solving MINLP lies in dealing with the non-convexity that may be caused by nonlinear models on the one hand, and the combinatorial explosion problem caused by integer variables on the other hand. Some studies use rounding algorithms based on integer programming to solve the pump station switching cost optimization problem, but ignore the inherent complex hydraulic characteristics of the model; some studies use simulation-based optimization methods to process the mixed integer and nonlinear parts of the model in stages, and use EPANET simulation software to verify the feasibility of the results, but these methods rely on mature software and cannot be adjusted according to actual conditions; other researchers use genetic algorithms to solve the established scheduling model, but this type of method has low solution efficiency and the model interpretability still needs to be improved.

[0004] Therefore, the present application provides an optimization scheduling method and system based on the parallel operation characteristic curve of water pumps to solve the above problems. Summary of the invention

[0005] The purpose of this application is to provide an optimization scheduling method and system based on the parallel operation characteristic curve of water pumps, so as to solve the problems of difficulty in solving the existing scheduling model and insufficient model interpretability; this application adopts a step-by-step solution strategy, first establishing a water pump parallel high-efficiency zone to narrow the solution scope, and then establishing an urban water supply scheduling planning model to find the optimal operating condition to overcome the above problems.

[0006] The present application first provides an optimization scheduling method based on the water pump parallel operation characteristic curve, including: fitting the characteristic curve of a single pump to obtain the single pump characteristic curve, the single pump includes: a fixed speed pump and a variable frequency pump; calculating the high efficiency zone of the single pump based on the single pump characteristic curve, constructing a multi-pump parallel operation characteristic curve based on the single pump characteristic curve and the pipeline head energy loss, and calculating the high efficiency zone of the multi-pump parallel operation based on the multi-pump parallel operation characteristic curve; taking the minimum number of pump group mode switching as the objective function, and taking only one pump group mode can be selected at any time and the selected pump group mode operates in the high efficiency zone as the constraint function, constructing an urban water supply scheduling planning model, and solving the pump group matching; calculating the working conditions of each pump in the pump group matching according to the required water supply pressure and the total water supply, and the working conditions include: flow, pressure and speed ratio.

[0007] In a possible implementation, a single pump characteristic curve is obtained by performing characteristic curve fitting on a single pump, and the single pump includes: a constant speed pump and a variable frequency pump; including: selecting a standard operating condition characteristic curve expression of the water pump when running at a constant speed as a fitting model for the constant speed pump, taking points on the pump factory characteristic curve diagram, and using the least squares method to calculate the parameters of the constant speed pump fitting model to obtain a fitting formula for the constant speed pump characteristic curve; according to the water pump similarity law, the constant speed pump fitting model is converted into a variable frequency pump fitting model, taking points from the variable frequency pump operation history data, and using the least squares method to calculate the parameters of the variable frequency pump fitting model to obtain a fitting formula for the variable frequency pump characteristic curve.

[0008] In one possible implementation, the high efficiency zone of a single pump is calculated based on a single pump characteristic curve, a multi-pump parallel operation characteristic curve is constructed based on the single pump characteristic curve and the pipeline head energy loss, and the high efficiency zone of multi-pump parallel operation is calculated based on the multi-pump parallel operation characteristic curve; including: defining a flow segment where the pump efficiency is not lower than a threshold as a high efficiency zone, extracting a curve segment where the pump efficiency is greater than the threshold as the high efficiency zone of the constant speed pump based on the constant speed pump characteristic curve, and extracting an area where the pump efficiency is greater than the threshold as the high efficiency zone of the variable frequency pump based on the variable frequency pump characteristic curve; constructing a pump parallel operation characteristic curve based on the single pump characteristic curves of each pump during parallel operation by superimposing the flow rates under the same head and considering the pipeline head energy loss, and extracting the high efficiency zone of the pump parallel operation based on the pump parallel operation characteristic curve.

[0009] In one possible implementation, the objective function is to minimize the number of pump group mode switching times, and the constraint function is that only one pump group mode can be selected at any time and the selected pump group mode operates in the high-efficiency zone, to construct an urban water supply scheduling planning model and solve it to obtain the pump group matching; including: ignoring the differences between pumps of the same model, solving the urban water supply scheduling planning model, and obtaining the pump group mode; based on the determined pump group mode, considering the differences in maintenance and intermittent work requirements of pumps of the same model, selecting pumps of the same model to obtain the pump group matching.

[0010] In one possible implementation, the operating conditions of each pump in the pump group are calculated according to the required water supply pressure and the total water supply, and the operating conditions include: flow, pressure and speed ratio; including: calculating the fixed speed pump flow according to the water supply pressure; calculating the variable frequency pump flow according to the total water supply and the fixed speed pump flow; calculating the variable frequency pump speed ratio according to the water supply pressure and the variable frequency pump flow; obtaining the pressure and flow of each fixed speed pump in the pump group and the pressure, flow and speed ratio of each variable frequency pump.

[0011] The present application also provides an optimization scheduling system based on the water pump parallel operation characteristic curve, including: a single pump characteristic curve fitting unit, used to fit the characteristic curve of a single pump to obtain a single pump characteristic curve, the single pump includes: a fixed speed pump and a variable frequency pump; a high-efficiency zone calculation unit, used to calculate the high-efficiency zone of the single pump based on the single pump characteristic curve, to construct a multi-pump parallel operation characteristic curve based on the single pump characteristic curve and the pipeline head energy loss, and to calculate the high-efficiency zone of the multi-pump parallel operation based on the multi-pump parallel operation characteristic curve; a pump combination optimization scheduling unit, used to construct an urban water supply scheduling planning model with the minimum number of pump group mode switching as the objective function and only one pump group mode can be selected at any time and the selected pump group mode operates in the high-efficiency zone as the constraint function, and solve to obtain the pump group matching; a scheduling condition calculation unit, used to calculate the working condition of each pump in the pump group matching according to the required water supply pressure and total water supply, the working conditions include: flow, pressure and speed ratio.

[0012] In one possible implementation, a single pump characteristic curve fitting unit includes: a constant speed pump fitting unit, which is used to select a standard operating condition characteristic curve expression of a water pump during constant speed operation as a constant speed pump fitting model, take points on a pump factory characteristic curve diagram, and use the least squares method to calculate the parameters of the constant speed pump fitting model to obtain a fitting formula for the constant speed pump characteristic curve; a variable frequency pump fitting unit, which is used to convert the constant speed pump fitting model into a variable frequency pump fitting model according to a water pump similarity law, take points from the variable frequency pump operation history data, and use the least squares method to calculate the parameters of the variable frequency pump fitting model to obtain a fitting formula for the variable frequency pump characteristic curve.

[0013] In one possible implementation, the high-efficiency zone calculation unit includes: a single-pump high-efficiency zone calculation unit, which is used to define a flow segment in which the water pump efficiency is not lower than a threshold as a high-efficiency zone, extract a curve segment in which the water pump efficiency is greater than the threshold as the high-efficiency zone of the constant-speed pump according to the constant-speed pump characteristic curve, and extract an area in which the water pump efficiency is greater than the threshold as the high-efficiency zone of the variable-frequency pump according to the variable-frequency pump characteristic curve; a parallel pump high-efficiency zone calculation unit, which is used to construct a water pump parallel operation characteristic curve by superimposing the flow rate under the same head based on the single pump characteristic curves of each water pump during parallel operation and considering the pipeline head energy loss, and extracting the high-efficiency zone of the water pump parallel operation according to the water pump parallel operation characteristic curve.

[0014] In one possible implementation, the pump combination optimization scheduling unit includes: a pump group mode calculation unit, which is used to ignore the differences between pumps of the same model, solve the urban water supply scheduling planning model, and obtain the pump group mode; a pump group matching calculation unit, which is used to select pumps of the same model based on the determined pump group mode, taking into account the differences in maintenance and intermittent work requirements of pumps of the same model, and obtain the pump group matching.

[0015] In one possible implementation, the scheduling operating condition calculation unit is specifically used to: calculate the constant speed pump flow rate according to the water supply pressure, calculate the variable frequency pump flow rate according to the total water supply and the constant speed pump flow rate, calculate the variable frequency pump speed ratio according to the water supply pressure and the variable frequency pump flow rate, and obtain the pressure, flow rate of each constant speed pump in the pump group and the pressure, flow rate and speed ratio of each variable frequency pump.

[0016] Compared with the prior art, the present application has the following beneficial effects: through a step-by-step solution strategy, the high-efficiency area of ​​multiple pumps operating in parallel is first calculated to narrow the solution scope, and then the minimum number of pump group mode switching is used as the objective function to construct an urban water supply scheduling planning model to find the optimal operating condition; the difficulty of model solution is reduced without affecting the interpretability of the model, and it can be directly applied to the existing real-time scheduling control system of water plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0018] Figure 1 It is a flow chart of the optimization scheduling method based on the parallel operation characteristic curve of water pumps;

[0019] Figure 2 This is a schematic diagram of the high efficiency area when the water pump is frequency-converted;

[0020] Figure 3 Schematic diagram of high efficiency area for different pump combinations.

[0021] Figure 4 This is the structural diagram of the optimal scheduling system based on the parallel operation characteristic curve of water pumps. DETAILED DESCRIPTION

[0022] Hereinafter, the term "include" or "may include" used in various embodiments of the present application indicates the presence of the function, operation or element applied for, and does not limit the increase of one or more functions, operations or elements. In addition, as used in various embodiments of the present application, the terms "include", "have" and their cognates are intended only to indicate specific features, numbers, steps, operations, elements, components or a combination of the foregoing items, and should not be understood as first excluding the presence of one or more other features, numbers, steps, operations, elements, components or a combination of the foregoing items or the possibility of increasing one or more features, numbers, steps, operations, elements, components or a combination of the foregoing items.

[0023] The terms used in the various embodiments of the application are only used to describe the purpose of specific embodiments and are not intended to limit the various embodiments of the application. As used herein, the singular form is intended to also include the plural form, unless the context clearly indicates otherwise. Unless otherwise limited, all terms used here (including technical terms and scientific terms) have the same meaning as the meanings commonly understood by ordinary technicians in the field of the various embodiments of the application. Terms (such as terms defined in generally used dictionaries) will be interpreted as having the same meaning as the contextual meaning in the relevant technical field and will not be interpreted as having idealized meanings or too formal meanings, unless clearly defined in the various embodiments of the application.

[0024] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with examples and drawings. The illustrative implementation scheme of the present application and its description are only used to explain the present application and are not intended to limit the present application.

[0025] Example 1 of the present application provides an optimization scheduling method based on the parallel operation characteristic curve of water pumps. Figure 1 As shown, Figure 1 The flowchart of the optimization scheduling method based on the characteristic curve of parallel operation of water pumps. The method includes: S1, fitting the characteristic curve of a single pump to obtain the characteristic curve of a single pump, and the single pump includes: a fixed speed pump and a variable frequency pump; S2, calculating the high efficiency zone of a single pump based on the characteristic curve of a single pump, constructing the characteristic curve of parallel operation of multiple pumps based on the characteristic curve of a single pump and the energy loss of the pipeline head, and calculating the high efficiency zone of parallel operation of multiple pumps based on the characteristic curve of parallel operation of multiple pumps; S3, taking the minimum number of pump group mode switching as the objective function, and taking only one pump group mode can be selected at any time and the selected pump group mode operates in the high efficiency zone as the constraint function, constructing the urban water supply scheduling planning model, and solving to obtain the pump group matching; S4, calculating the working conditions of each pump in the pump group matching according to the required water supply pressure and total water supply, and the working conditions include: flow, pressure and speed ratio.

[0026] The improvement of this application lies in that, through a step-by-step solution strategy, the high-efficiency area of ​​multiple pumps operating in parallel is first calculated to narrow the solution scope, and then the urban water supply scheduling planning model is constructed with the minimum number of pump group mode switching as the objective function to find the optimal operating condition; the difficulty of model solution is reduced without affecting the interpretability of the model, and it can be directly applied to the real-time scheduling control system of existing water plants.

[0027] In a possible implementation, S1, performing characteristic curve fitting on a single pump to obtain a single pump characteristic curve, the single pump comprising: a constant speed pump and a variable frequency pump; comprising: S11, selecting the standard operating characteristic curve expression of the water pump during constant speed operation as the constant speed pump fitting model, taking points on the pump factory characteristic curve diagram, and using the least squares method to calculate the parameters of the constant speed pump fitting model to obtain a fitting formula for the constant speed pump characteristic curve; S12, according to the water pump similarity law, converting the constant speed pump fitting model into a variable frequency pump fitting model, taking points from the variable frequency pump operation historical data, and using the least squares method to calculate the parameters of the variable frequency pump fitting model to obtain a fitting formula for the variable frequency pump characteristic curve.

[0028] Specifically, step S11: constant speed pump characteristic curve fitting. Each water pump has its own characteristic curve when running at a fixed speed. The least squares principle can be used to fit the constant speed pump characteristic curve in combination with the expression of the standard operating condition characteristic curve of the water pump when running at a fixed speed. The expression of the standard operating condition characteristic curve of the water pump when running at a fixed speed is:

[0029]

[0030] In the formula, H e is the head under standard working condition; Q e is the flow rate under standard working conditions; N e is the pump shaft power under standard working conditions; η e is the pump efficiency under standard working conditions; H x , S x , a0, a1, a2, b0, b1, b2 are the unknown coefficients of the characteristic curve equation. By taking points on the pump factory characteristic curve and using the least squares principle, the fitting formula of the constant speed pump characteristic curve under standard working conditions can be calculated.

[0031] Step S12: frequency conversion pump characteristic curve fitting. A frequency conversion pump is a pump that can change the operating conditions of the pump by changing the speed under the drive of a variable frequency motor. Since the frequency conversion operation does not change the physical characteristics of the pump, according to the water pump similarity law, when the speed changes, the flow ratio before and after the water pump frequency conversion is equal to the speed ratio, the head ratio is equal to the square of the speed ratio, and the shaft power ratio is equal to the cube of the speed ratio:

[0032]

[0033] In the formula, Q, H, and N are the flow rate, head, and shaft power of the pump after frequency conversion, respectively. n and n e are the speeds after frequency conversion and under standard conditions respectively. Assume that the speed ratio k = n / n e , combining the above formulas, we can get the following variable frequency pump fitting model:

[0034]

[0035] By using the least squares method to process the historical operating data of the variable frequency pump, the fitting formula of the variable frequency pump characteristic curve under different working conditions can be calculated.

[0036] In one possible implementation, S2, calculates the high-efficiency zone of a single pump based on a single pump characteristic curve, constructs a multi-pump parallel operation characteristic curve based on the single pump characteristic curve and the pipeline head energy loss, and calculates the high-efficiency zone of multi-pump parallel operation based on the multi-pump parallel operation characteristic curve; including: S21, defining a flow segment where the pump efficiency is not lower than a threshold as a high-efficiency zone, extracting a curve segment where the pump efficiency is greater than the threshold as the high-efficiency zone of the constant-speed pump according to the constant-speed pump characteristic curve, and extracting an area where the pump efficiency is greater than the threshold as the high-efficiency zone of the variable-frequency pump according to the variable-frequency pump characteristic curve; S22, based on the single pump characteristic curves of each pump during parallel operation, superimposes the flow rate under the same head and considers the pipeline head energy loss to construct a pump parallel operation characteristic curve, and extracts the high-efficiency zone of the pump parallel operation according to the pump parallel operation characteristic curve.

[0037] Specifically, step S21: single pump high efficiency zone calculation. For pumps that are not clearly specified, the flow segment [Q A ,Q B ] is defined as the high efficiency zone. For a water pump running at a constant speed (speed is n0), its high efficiency zone can be expressed as a curve segment:

[0038] H=H x -S x Q 2 ,Q∈[Q A ,Q B ]

[0039] When the water pump is running at variable frequency, due to the water pump's own efficiency, cavitation and other requirements, its speed range is [n min ,n0]. Define the speed as n min When the centrifugal pump has high efficiency, the flow range is [Q C ,Q D ], the high efficiency area of ​​the water pump when the frequency is changed Figure 2 The shaded area in Figure 2 This is a schematic diagram of the high efficiency area when the water pump is frequency-converted. Figure 2 In the equation, l1 and l2 are parabolas of similar working conditions, and their analytical expressions are:

[0040]

[0041] Assume that the coordinates of the endpoints of the shadow area are A(Q A ,H A ), B(Q B ,H B ), According to the similarity law, we can get C(Q A ·k min ,H A ·k min 2 ), D(Q B ·k min ,H B ·k min 2 ). Further, the analytical expression of the shaded area is:

[0042] H≤H x +S x Q 2

[0043] H≥H x ·k min 2 +S x Q 2

[0044]

[0045] Step S22: Calculation of parallel operation characteristic curve and high efficiency area. When multiple pumps work in parallel, add the flow rates of each pump at the same head to get the characteristic curve after parallel operation. This method can also be used to solve the operation area. Add the operation areas of each single pump at a certain head to get the operation area under parallel operation. Since multiple pumps are connected in parallel, there is energy loss in the pipeline head, so the energy loss in the pipeline head also needs to be considered. The calculation formula for the QH characteristic curve of multi-pump parallel operation is as follows:

[0046]

[0047] In the above formula, H factory is the factory water head, ΔH i is the pipeline head energy loss of the i-th pump, H i is the pressure after the i-th pump, k i is the speed ratio of the i-th pump, and Qfactory is the total flow rate of factory water.

[0048] In one possible implementation, S3, taking the minimum number of pump group mode switching times as the objective function, and taking only one pump group mode can be selected at any time and the selected pump group mode operates in the high-efficiency zone as the constraint function, constructing an urban water supply scheduling planning model, and solving to obtain the pump group matching; including: S31, ignoring the differences between pumps of the same model, solving the urban water supply scheduling planning model, and obtaining the pump group mode; S32, based on the determined pump group mode, considering the differences in maintenance and intermittent work requirements of pumps of the same model, selecting pumps of the same model to obtain the pump group matching.

[0049] Specifically, step S31: determine the pump group mode according to the water demand. Urban water supply pumping stations are generally composed of multiple pumps, including both variable frequency pumps and fixed speed pumps. These water pumps may also have the same model of pumps as backup for each other, resulting in multiple configuration schemes to meet the same water demand. In order to simplify the scheduling work, the differences between pumps of the same model are ignored in this step, and the optimal pump station configuration mode in different water supply intervals is determined according to the actual water supply characteristics of the pump station. Establish an urban water supply scheduling planning model, including the objective function: minimize the number of pump group mode switching; including the following constraints: 1. Only one pump group mode can be selected at any time; 2. The efficiency of the selected pump group mode is in the high efficiency zone, that is, it cannot be lower than the set threshold, such as 0.8.

[0050]

[0051] pe t,i =QH i (Q t ,H t )

[0052]

[0053] b t,i ∈(0,1)

[0054] In the above formula, sw t is the pump group mode switching change at time t, b t,i is the selection state of the i-th pump group mode at time t, which is a binary variable. At any time, only one mode is selected to be turned on. When selected, it is equal to 1, and when not selected, it is equal to 0. When the pump group mode is switched at time t, sw t is equal to 1; otherwise, it is 0. t is the efficiency of the pump group mode at time t, and its value is determined by the selected i-th pump group mode; pe t,i is the factory flow Q at time t t And lift H t Under , the overall pump efficiency of the i-th pump station mode.

[0055] Step S32: Determine the pump group matching according to the actual situation. In the previous step, the substitutability of pumps of the same model is not considered. In the selected mode, the pumps of the same model are selected considering the requirements of actual pump maintenance, intermittent operation, etc.

[0056] In a possible implementation, S4, the operating conditions of each pump in the pump group are calculated according to the required water supply pressure and the total water supply, and the operating conditions include: flow, pressure and speed ratio; including: calculating the fixed speed pump flow according to the water supply pressure; calculating the variable frequency pump flow according to the total water supply and the fixed speed pump flow; calculating the variable frequency pump speed ratio according to the water supply pressure and the variable frequency pump flow; obtaining the pressure, flow of each fixed speed pump in the pump group and the pressure, flow and speed ratio of each variable frequency pump.

[0057] Specifically, the flow rate of the fixed speed pump is calculated according to the water supply pressure. The relevant calculation formula is as follows:

[0058]

[0059] Calculate the variable frequency pump flow rate based on the total water supply and the fixed speed pump flow rate (only one variable frequency pump is used at the same time). The relevant calculation formula is as follows:

[0060] Q 变 =Q 出厂 -ΣQ 定

[0061] In the above formula, Q 变 is the variable frequency pump flow, Q 出厂 It is the total water supply flow of the pumping station.

[0062] Calculate the speed ratio of the variable frequency pump based on the water supply pressure and the variable frequency pump flow rate. The relevant calculation formula is as follows:

[0063]

[0064] Finally, the operating conditions of the fixed speed pump and variable frequency pump obtained by the optimization scheduling method of this application are output, including flow, pressure and speed ratio (variable frequency pump).

[0065] It can be understood that the present application first calculates the high-efficiency zone of multiple pumps running in parallel and uses this as the model constraint condition, while considering the number of pump group mode switching and using this as the model objective function, to achieve a pump group combination that works in the high-efficiency zone with the least number of switching times, and effectively reduce the difficulty of solving the model.

[0066] Example 2 of the present application provides an application example of the above-mentioned optimization scheduling method. Taking a water supply pump station of a water plant in a certain city as an example, the above-mentioned method is introduced in detail. The water plant has 10 pumps, including 6 large pumps (2 variable frequency pumps) and 4 small pumps. The relevant pump models and usage methods are as follows:

[0067] Table 1 Basic information list of water supply pump stations in a certain city water plant

[0068]

[0069]

[0070] In step S1, the standard operating characteristic curve is used to perform curve fitting for the 1-6# large pumps and 7-10# small pumps. The sample point data are as follows:

[0071] Table 2.1 Sample point data of standard operating characteristic curve of 1#, 3# and 5# pumps

[0072] Flow rate (m3 / h) Lift(m) Power(kw) Work efficiency 3500 51.5 578 0.85 4000 50.7 585 0.88 4475 48.4 603 0.90 5000 45.0 674 0.91 5123 44.9 678 0.92 5600 40.5 694 0.89 5625 38.7 700 0.84 6480 32.3 710 0.82

[0073] Table 2.2 Sample point data of standard operating characteristic curve of 2#, 4# and 6# pumps

[0074] Flow rate (m3 / h) Lift(m) Power(kw) Work efficiency 3544 57.4 696 0.78 4051 55.1 714 0.82 4555 50.8 730 0.86 5006 48.5 735 0.90 5104 48.1 739 0.90 5302 46.2 740 0.90 5615 44.2 751 0.90 6124 40.8 767 0.89

[0075] Table 2.3 Sample point data of 7-10# pump standard operating characteristic curve

[0076]

[0077]

[0078] The results of fitting parameters of single pump characteristic curve are as follows:

[0079] Table 3 Fitting parameters of the characteristic curves of standard working conditions of each pump

[0080] parameter 1, 3, 5# pumps 2, 4, 6# pumps 7-10# pump Hx 61.7 65.4 54.2 Sx -6.95E-07 -6.75E-07 -7.40E-06 a0 366.6 570.3 91.6 a1 6.30E-02 3.78E-02 6.21E-02 a2 -6.24E-07 -9.34E-07 -3.55E-07 b0 1.55E-02 -3.48E-03 8.04E-03 b1 3.98E-04 3.22E-04 1.46E-03 b2 -4.37E-08 -2.87E-08 -5.94E-07

[0081] In step S2, based on the high-efficiency intervals of the fixed-speed pump and the variable-frequency pump, high-efficiency zones for different pump combinations running in parallel can be drawn. Assuming that the minimum pump efficiency allowed in the high-efficiency zone is 0.8, and at most one variable-frequency pump can run at the same time, there are a total of 8 pump combination modes when the high-efficiency zones do not overlap as much as possible. Figure 3 As shown, Figure 3 This is a schematic diagram of the high-efficiency area of ​​different pump combinations. When the factory flow and pressure requirements change, in order to ensure operating efficiency, it is necessary to switch to the corresponding high-efficiency pump combination mode.

[0082] Table 4 High efficiency range of different pump combination modes

[0083]

[0084]

[0085] In step S3, based on the prediction of the water supply pressure and the total water supply in the future, the pump parallel operation combination mode (pump group mode) can be optimized, as shown below based on the optimization result:

[0086] Table 5 Optimization calculation results

[0087] time Lift(m) Water supply (m3 / h) Optimize the combination Pump package details 0 41.4 14855.8 mode6 [2,1,3,7,8] 1 38.3 11894.9 mode3 [2,1] 2 36.0 9939.3 mode3 [2,1] 3 35.1 8892.2 mode2 [2,7,8] 4 35.1 8554.9 mode2 [2,7,8] 5 35.9 8947.0 mode2 [2,7,8] 6 38.0 9841.8 mode3 [2,1] 7 41.3 12070.3 mode3 [2,1] 8 44.8 15272.0 mode6 [2,1,3,7,8] 9 46.4 17080.8 mode6 [2,1,3,7,8] 10 47.2 18271.2 mode7 [2,1,3,5] 11 46.6 17742.8 mode7 [2,1,3,5] 12 45.3 17173.5 mode7 [2,1,3,5] 13 43.8 16202.4 mode6 [2,1,3,7,8] 14 42.5 15030.2 mode6 [2,1,3,7,8] 15 42.0 14515.2 mode6 [2,1,3,7,8] 16 42.2 14344.2 mode6 [2,1,3,7,8] 17 43.5 15371.5 mode6 [2,1,3,7,8] 18 45.1 16270.9 mode6 [2,1,3,7,8] 19 46.3 17049.7 mode6 [2,1,3,7,8] 20 46.7 17361.0 mode6 [2,1,3,7,8] 21 46.7 17793.0 mode6 [2,1,3,7,8] 22 46.4 17979.3 mode6 [2,1,3,7,8] 23 44.7 17075.5 mode6 [2,1,3,7,8]

[0088] In step S4, the variable frequency pump flow and speed ratio are calculated according to the optimized pump group mode. The calculation results are as follows:

[0089] Table 6 Output working conditions of variable frequency pump

[0090]

[0091] Example 3 of the present application provides an optimization scheduling system based on the water pump parallel operation characteristic curve. Figure 4 As shown, Figure 4 This is a structural diagram of an optimization scheduling system based on the characteristic curve of water pump parallel operation. The system includes: a single pump characteristic curve fitting unit, which is used to fit the characteristic curve of a single pump to obtain a single pump characteristic curve. The single pump includes: a fixed speed pump and a variable frequency pump; an efficient zone calculation unit, which is used to calculate the efficient zone of a single pump based on the single pump characteristic curve, to construct a multi-pump parallel operation characteristic curve based on the single pump characteristic curve and the pipeline head energy loss, and to calculate the efficient zone of multi-pump parallel operation based on the multi-pump parallel operation characteristic curve; a pump combination optimization scheduling unit, which is used to construct an urban water supply scheduling planning model with the minimum number of pump group mode switching as the objective function and the constraint function that only one pump group mode can be selected at any time and the selected pump group mode operates in the efficient zone, and solve the pump group matching; a scheduling condition calculation unit, which is used to calculate the working conditions of each pump in the pump group matching according to the required water supply pressure and total water supply. The working conditions include: flow, pressure and speed ratio.

[0092] In one possible implementation, a single pump characteristic curve fitting unit includes: a constant speed pump fitting unit, which is used to select a standard operating condition characteristic curve expression of a water pump during constant speed operation as a constant speed pump fitting model, take points on a pump factory characteristic curve diagram, and use the least squares method to calculate the parameters of the constant speed pump fitting model to obtain a fitting formula for the constant speed pump characteristic curve; a variable frequency pump fitting unit, which is used to convert the constant speed pump fitting model into a variable frequency pump fitting model according to a water pump similarity law, take points from the variable frequency pump operation history data, and use the least squares method to calculate the parameters of the variable frequency pump fitting model to obtain a fitting formula for the variable frequency pump characteristic curve.

[0093] In one possible implementation, the high-efficiency zone calculation unit includes: a single-pump high-efficiency zone calculation unit, which is used to define a flow segment in which the water pump efficiency is not lower than a threshold as a high-efficiency zone, extract a curve segment in which the water pump efficiency is greater than the threshold as the high-efficiency zone of the constant-speed pump according to the constant-speed pump characteristic curve, and extract an area in which the water pump efficiency is greater than the threshold as the high-efficiency zone of the variable-frequency pump according to the variable-frequency pump characteristic curve; a parallel pump high-efficiency zone calculation unit, which is used to construct a water pump parallel operation characteristic curve by superimposing the flow rate under the same head based on the single pump characteristic curves of each water pump during parallel operation and considering the pipeline head energy loss, and extracting the high-efficiency zone of the water pump parallel operation according to the water pump parallel operation characteristic curve.

[0094] In one possible implementation, the pump combination optimization scheduling unit includes: a pump group mode calculation unit, which is used to ignore the differences between pumps of the same model, solve the urban water supply scheduling planning model, and obtain the pump group mode; a pump group matching calculation unit, which is used to select pumps of the same model based on the determined pump group mode, taking into account the differences in maintenance and intermittent work requirements of pumps of the same model, and obtain the pump group matching.

[0095] In one possible implementation, the scheduling operating condition calculation unit is specifically used to: calculate the constant speed pump flow rate according to the water supply pressure, calculate the variable frequency pump flow rate according to the total water supply and the constant speed pump flow rate, calculate the variable frequency pump speed ratio according to the water supply pressure and the variable frequency pump flow rate, and obtain the pressure, flow rate of each constant speed pump in the pump group and the pressure, flow rate and speed ratio of each variable frequency pump.

[0096] It should be noted that the optimization scheduling system based on the parallel operation characteristic curve of the water pumps in the present application is used to implement the above-mentioned optimization scheduling method based on the parallel operation characteristic curve of the water pumps, corresponds one-to-one to the above-mentioned method, and has corresponding technical effects, so it will not be elaborated on here.

[0097] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An optimization scheduling method based on the parallel operation characteristic curve of water pumps, characterized in that: include: Performing characteristic curve fitting on a single pump to obtain a single pump characteristic curve, wherein the single pump includes: a fixed speed pump and a variable frequency pump; Calculate the high efficiency zone of a single pump based on the single pump characteristic curve, construct the multi-pump parallel operation characteristic curve based on the single pump characteristic curve and pipeline head energy loss, and calculate the high efficiency zone of multi-pump parallel operation based on the multi-pump parallel operation characteristic curve; Taking the minimum number of pump group mode switching as the objective function and only one pump group mode can be selected at any time and the selected pump group mode must operate in the high-efficiency area as the constraint function, an urban water supply scheduling planning model is constructed to solve the pump group matching. The working conditions of each pump in the pump group are calculated according to the required water supply pressure and the total water supply, and the working conditions include: flow rate, pressure and speed ratio.

2. The optimization scheduling method based on the water pump parallel operation characteristic curve according to claim 1 is characterized in that: The characteristic curve of a single pump is fitted to obtain a characteristic curve of the single pump, wherein the single pump includes: a fixed speed pump and a variable frequency pump; including: The standard operating characteristic curve expression of the water pump during constant speed operation is selected as the constant speed pump fitting model, points are taken on the pump factory characteristic curve, and the parameters of the constant speed pump fitting model are calculated using the least squares method to obtain the fitting formula of the constant speed pump characteristic curve; According to the water pump similarity law, the fixed speed pump fitting model is transformed into the variable frequency pump fitting model. The historical data of the variable frequency pump operation are taken, and the parameters of the variable frequency pump fitting model are calculated using the least squares method to obtain the fitting formula of the variable frequency pump characteristic curve.

3. The optimization scheduling method based on the water pump parallel operation characteristic curve according to claim 1 is characterized in that: Calculate the high efficiency area of ​​a single pump based on the single pump characteristic curve, construct the multi-pump parallel operation characteristic curve based on the single pump characteristic curve and pipeline head energy loss, and calculate the high efficiency area of ​​multi-pump parallel operation based on the multi-pump parallel operation characteristic curve; including: The flow section where the pump efficiency is not less than the threshold is defined as the high-efficiency zone. According to the characteristic curve of the fixed-speed pump, the curve section where the pump efficiency is greater than the threshold is extracted as the high-efficiency zone of the fixed-speed pump. According to the characteristic curve of the variable-frequency pump, the area where the pump efficiency is greater than the threshold is extracted as the high-efficiency zone of the variable-frequency pump. Based on the single pump characteristic curves of each pump during parallel operation, the flow rates under the same head are superimposed and the pipeline head energy loss is considered to construct the parallel operation characteristic curve of the pumps. The high-efficiency area of ​​the parallel operation of the pumps is extracted according to the parallel operation characteristic curve of the pumps.

4. The optimization scheduling method based on the water pump parallel operation characteristic curve according to claim 1 is characterized in that: Taking the minimum number of pump group mode switching as the objective function and only one pump group mode can be selected at any time and the selected pump group mode operates in the high-efficiency zone as the constraint function, an urban water supply scheduling planning model is constructed to solve the pump group matching; including: Ignoring the differences between pumps of the same model, solve the urban water supply scheduling planning model and obtain the pump group mode; Based on the determined pump group mode, considering the differences in maintenance and intermittent work requirements of pumps of the same model, pumps of the same model are selected to obtain the pump group combination.

5. The optimization scheduling method based on the water pump parallel operation characteristic curve according to claim 1 is characterized in that: Calculate the working conditions of each pump in the pump group according to the required water supply pressure and total water supply, including: flow rate, pressure and speed ratio; including: The fixed speed pump flow is calculated according to the water supply pressure, the variable frequency pump flow is calculated according to the total water supply and the fixed speed pump flow, and the variable frequency pump speed ratio is calculated according to the water supply pressure and the variable frequency pump flow, so as to obtain the pressure and flow of each fixed speed pump in the pump group and the pressure, flow and speed ratio of each variable frequency pump.

6. An optimization scheduling system based on the parallel operation characteristic curve of water pumps, characterized in that: include: A single pump characteristic curve fitting unit is used to fit the characteristic curve of a single pump to obtain a single pump characteristic curve, wherein the single pump includes: a fixed speed pump and a variable frequency pump; A high-efficiency zone calculation unit, used for calculating the high-efficiency zone of a single pump based on a single pump characteristic curve, constructing a multi-pump parallel operation characteristic curve based on the single pump characteristic curve and pipeline head energy loss, and calculating the high-efficiency zone of multi-pump parallel operation based on the multi-pump parallel operation characteristic curve; The pump combination optimization scheduling unit is used to build an urban water supply scheduling planning model with the minimum number of pump group mode switching as the objective function and only one pump group mode can be selected at any time and the selected pump group mode must operate in the high-efficiency area as the constraint function to solve the pump group matching; The dispatching working condition calculation unit is used to calculate the working condition of each pump in the pump group according to the required water supply pressure and total water supply, and the working condition includes: flow rate, pressure and speed ratio.

7. The optimization scheduling system based on the water pump parallel operation characteristic curve according to claim 6 is characterized in that: The single pump characteristic curve fitting unit comprises: The constant speed pump fitting unit is used to select the standard working condition characteristic curve expression of the water pump during constant speed operation as the constant speed pump fitting model, take points on the pump factory characteristic curve diagram, calculate the parameters of the constant speed pump fitting model using the least squares method, and obtain the fitting formula of the constant speed pump characteristic curve; The variable frequency pump fitting unit is used to convert the fixed speed pump fitting model into the variable frequency pump fitting model according to the water pump similarity law, take points of the variable frequency pump operation historical data, calculate the parameters of the variable frequency pump fitting model by using the least squares method, and obtain the fitting formula of the variable frequency pump characteristic curve.

8. The optimization scheduling system based on the water pump parallel operation characteristic curve according to claim 6 is characterized in that: The high-efficiency area calculation unit comprises: A single pump high-efficiency zone calculation unit is used to define a flow section where the pump efficiency is not less than a threshold as a high-efficiency zone, extract a curve section where the pump efficiency is greater than the threshold as the high-efficiency zone of the fixed-speed pump according to the characteristic curve of the fixed-speed pump, and extract an area where the pump efficiency is greater than the threshold as the high-efficiency zone of the variable-frequency pump according to the characteristic curve of the variable-frequency pump; The parallel pump high-efficiency zone calculation unit is used to superimpose the flow rates under the same head based on the single pump characteristic curves of each pump during parallel operation and consider the pipeline head energy loss to construct the parallel operation characteristic curve of the pumps, and extract the high-efficiency zone of the parallel operation of the pumps according to the parallel operation characteristic curve of the pumps.

9. The optimization scheduling system based on the water pump parallel operation characteristic curve according to claim 6 is characterized in that: The pump combination optimization scheduling unit comprises: The pump group mode calculation unit is used to ignore the differences between pumps of the same model, solve the urban water supply scheduling planning model, and obtain the pump group mode; The pump group matching calculation unit is used to select pumps of the same model based on the determined pump group mode and take into account the differences in maintenance and intermittent work requirements of pumps of the same model to obtain the pump group matching.

10. The optimization scheduling system based on the water pump parallel operation characteristic curve according to claim 6, characterized in that: The dispatching condition calculation unit is specifically used for: The fixed speed pump flow is calculated according to the water supply pressure, the variable frequency pump flow is calculated according to the total water supply and the fixed speed pump flow, and the variable frequency pump speed ratio is calculated according to the water supply pressure and the variable frequency pump flow, so as to obtain the pressure and flow of each fixed speed pump in the pump group and the pressure, flow and speed ratio of each variable frequency pump.

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