Method and system for determining stable operation threshold interval of water pump based on multi-parameter constraint

Abstract

The invention provides a water pump stable operation threshold interval determination method and system based on multi-parameter constraint, and relates to the technical field of water pumps, the method comprises the steps of determining a basic performance framework, obtaining a flow-lift curve and a static limit boundary, dynamically calculating a water level related boundary based on the flow-lift curve, and obtaining a dynamic boundary; and calculating a stability boundary based on a flow-lift curve, and integrating the static boundary, the dynamic boundary and the stability boundary to form a stable operation threshold interval of the water pump. According to the method, the threshold interval of safe operation of the water pump is constructed by integrating the six parameters including the efficient area, the cavitation limiting area, the hump safety margin, the pressure pulsation limiting area, the lift limiting area and the rotating speed limiting area, the problem of dynamic definition of the safe operation interval under the complex working condition of the variable-frequency speed regulation pump station is solved, and the design accuracy and the operation reliability of the pump station are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of water pump technology, and in particular to a method and system for determining the stable operation threshold range of a water pump based on multi-parameter constraints. Background Technology

[0002] Large-scale water transfer pumping stations (especially variable frequency speed control pumping stations) are prone to drastic changes in hydraulic conditions due to fluctuations in user water demand and frequent adjustments to operating conditions, threatening operational safety. Existing technologies mostly focus on research on single parameters (such as the high-efficiency zone or cavitation margin), lacking a method for defining dynamic threshold intervals based on multi-parameter coordination. Although scholars have conducted extensive research on pressure pulsation and hump characteristics (e.g., Xiao Yang, Zhang Fei), a systematic integrated judgment system for safe operating intervals has not been formed, leading to pumping station design relying on experience and unclear safety margins for operating conditions. Therefore, it is essential to design a method and system for determining the stable operating threshold interval of water pumps based on multi-parameter constraints. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the purpose of this invention is to provide a method and system for determining the stable operation threshold range of a water pump based on multi-parameter constraints.

[0004] To achieve the above objectives, the present invention provides the following solution: This invention provides a method for determining the stable operation threshold range of a water pump based on multi-parameter constraints, comprising: Step 1: Determine the basic performance framework and obtain the flow-head curve and static limit boundaries; Step 2: Dynamically calculate the water level-related boundaries based on the flow-head curve to obtain the dynamic boundaries; Step 3: Calculate the stability boundary based on the flow-head curve; Step 4: Integrate the static boundary, dynamic boundary, and stability boundary to form the stable operation threshold range of the water pump.

[0005] Preferably, in step 1, the basic performance framework is determined, and the flow-head curve and static limit boundaries are obtained, specifically as follows: Based on the pump test data, a flow-head curve was fitted, and the high-efficiency zone was defined; Preset static limit boundaries, including setting the maximum and minimum required head limit lines according to engineering requirements, and setting the maximum and minimum speed limit lines according to pump performance.

[0006] Preferably, the high-efficiency region is the envelope region where the highest efficiency decreases by ≤7%.

[0007] Preferably, in step 2, the dynamic boundary is obtained by dynamically calculating the water level-related boundary based on the flow-head curve, specifically as follows: Based on the flow-head curve and combined with the cavitation margin of the real-time inlet pool water level calculation device, a safety factor is introduced through the critical relationship between the device cavitation margin and the required cavitation margin to solve the dynamic cavitation boundary point, and the cavitation boundary points at different speeds are correlated to form the left and right cavitation limit lines.

[0008] Preferably, in step 3, the stability boundary is calculated based on the flow-head curve, specifically as follows: Generate hump limit lines based on flow-head curves; The left and right pressure pulsation limit lines are generated based on the flow-head curve.

[0009] Preferably, the hump limit line is generated based on the flow-head curve, specifically as follows: Based on the flow-head curve, the hump limit point at rated speed is calculated using the hump margin formula. By extending the similarity law to various rotational speeds, a hump limit line is generated.

[0010] Preferably, left and right pressure pulsation limit lines are generated based on the flow-head curve, specifically as follows: Obtain the model pressure pulsation data and convert it to the prototype according to the similarity law; Based on the flow-head curve, with pressure pulsation amplitude ≤7% as a constraint, the left and right boundary points at each speed are determined; Connect the left and right boundary points at each determined speed to form the left and right pressure pulsation limit lines.

[0011] Preferably, in step 4, the static boundary, dynamic boundary, and stability boundary are integrated to form the stable operation threshold range of the water pump, specifically: Obtain the maximum required head limit line, minimum required head limit line, maximum speed limit line, minimum speed limit line, left cavitation limit line, right cavitation limit line, hump limit line, left pressure pulsation limit line, and right pressure pulsation limit line. Take the common overlapping area of ​​all boundary lines to form the stable operation threshold range of the water pump.

[0012] The present invention also includes a system for determining the stable operation threshold range of a water pump based on multi-parameter constraints, applied to the above-mentioned method for determining the stable operation threshold range of a water pump based on multi-parameter constraints, comprising: The data acquisition and processing unit is used to acquire water pump performance test data, real-time inlet pool water level data, and pressure pulsation data. The basic performance framework determination unit is connected to the data acquisition and processing unit. It is used to generate a flow-head curve based on the water pump performance test data, delineate the high-efficiency zone based on the flow-head curve, and preset the head limit line and speed limit line. The dynamic boundary calculation unit, connected to the data acquisition and processing unit and the basic performance framework determination unit, is used to calculate the cavitation margin of the device based on the flow-head curve and the real-time water level of the inlet pool. It also introduces a safety factor through the critical relationship between the dynamic boundary calculation unit and the required cavitation margin, solves the dynamic cavitation boundary point, and generates the dynamic cavitation limit line. The stability boundary calculation unit, connected to the basic performance framework determination unit, is used to calculate and generate the hump limit line and pressure pulsation limit line based on the flow-head curve. The integrated output unit is connected to the basic performance framework determination unit, the dynamic boundary calculation unit, and the stability boundary calculation unit, respectively. It is used to integrate the static limit boundary, the dynamic cavitation limit line, the hump limit line, and the pressure pulsation limit line, take the common overlapping area of ​​all boundaries, and construct and output the stable operation threshold range of the water pump.

[0013] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: This invention provides a method and system for determining the stable operation threshold range of a water pump based on multi-parameter constraints. The method includes determining a basic performance framework, obtaining the flow-head curve and static constraint boundaries, dynamically calculating water level-related boundaries based on the flow-head curve to obtain dynamic boundaries, calculating stability boundaries based on the flow-head curve, and integrating the static, dynamic, and stability boundaries to construct the stable operation threshold range of the water pump. The system includes a data acquisition and processing unit, a basic performance framework determination unit, a dynamic boundary calculation unit, a stability boundary calculation unit, and an integrated output unit. This invention constructs the safe operation threshold range of the water pump by comprehensively considering six parameters: high-efficiency zone, cavitation constraint zone, hump safety margin, pressure pulsation constraint zone, head constraint zone, and speed constraint zone. This solves the problem of dynamically defining the safe operation range under complex operating conditions of variable frequency speed control pump stations, significantly improving the design accuracy and operational reliability of pump stations, and has the following advantages: 1. Dynamic adaptability: By adjusting the cavitation limitation boundary in real time according to the water level of the inlet pool, the problem of interval failure caused by water level fluctuation in traditional methods is solved; 2. Multi-parameter coordination: For the first time, it integrates six-dimensional constraints, including high efficiency, cavitation, hump, pulsation, head, and speed, to form a complete safety criterion; 3. Engineering applicability: The method is applicable to variable frequency speed control pump stations, providing a theoretical basis for design and reducing the risks of instability and cavitation damage in the hump area; 4. Quantitative accuracy: Through mathematical modeling (polynomial fitting + similarity law) and standardized thresholds (such as η decrease ≤ 7%, pulsation ≤ 7%, hump margin ≥ 3%), empirical design errors are eliminated. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 A schematic diagram illustrating the determination of the high-efficiency zone of a water pump; Figure 2 A schematic diagram of the high-efficiency zone of a pumping station; Figure 3 A simplified diagram of a water pump unit; Figure 4 for , A schematic diagram of the relationship between flow rate and output; Figure 5 A schematic diagram of the cavitation limitation range at a certain rotational speed; Figure 6 A schematic diagram of the safe operating zone where the water pump does not experience initial cavitation when the water level in a certain inlet pool is [missing information]. Figure 7 Schematic diagram defining the safety margin for the hump region; Figure 8 This is a schematic diagram of the hump limit line for a certain pumping station. Figure 9 This is a schematic diagram showing the pressure pulsation curve and pressure pulsation limit of a water pump at its rated speed in a certain pumping station. Figure 10 For the pressure pulsation of a certain pump station's water pump ( DH / H Schematic diagram of the limit range (≤7%); Figure 11 A schematic diagram of the threshold region for stable operation of water pumps in a certain pumping station; Figure 12 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] The purpose of this invention is to provide a method and system for determining the stable operation threshold range of a water pump based on multi-parameter constraints. By integrating six parameters—high-efficiency zone, cavitation restriction zone, hump safety margin, pressure pulsation restriction zone, head restriction zone, and speed restriction zone—a common threshold range for safe operation of the water pump is constructed. This solves the problem of dynamically defining the safe operation range under complex operating conditions of variable frequency speed control pump stations, and significantly improves the design accuracy and operational reliability of pump stations.

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] like Figure 12 As shown, the present invention provides a method for determining the stable operation threshold range of a water pump based on multi-parameter constraints, including: Step 1: Determine the basic performance framework and obtain the flow-head curve and static limit boundaries; Step 2: Dynamically calculate the water level-related boundaries based on the flow-head curve to obtain the dynamic boundaries; Step 3: Calculate the stability boundary based on the flow-head curve; Step 4: Integrate the static boundary, dynamic boundary, and stability boundary to form the stable operation threshold range of the water pump.

[0020] In step 1, the basic performance framework is determined, and the flow-head curve and static limit boundaries are obtained, specifically: Based on the pump test data, a flow-head curve was fitted, and the high-efficiency zone was defined; A preset static limit boundary is defined, wherein the maximum required head limit line and the minimum required head limit line (horizontal boundary) are set according to engineering requirements, and the maximum speed limit line and the minimum speed limit line (gradient curve boundary) are set according to pump performance. The high efficiency zone is the envelope region where the highest efficiency decreases by ≤7%. To explain in detail, such as Figure 1 As shown, the horizontal axis represents the flow rate of the water pump. The vertical axis represents the pump head. or pump efficiency ; If the data points measured in the water pump performance test , The flow rate of the water pump ~lift The performance curve can be seen below. Fitting the polynomial of degree n, i.e.: (1) In the formula, Number the test and measured operating points; , The first Pump flow rate and head at each operating point; This represents the maximum number of operating points. ( () represents the coefficients of the polynomial; The high-efficiency range of a water pump typically refers to a drop in efficiency no greater than 7% from its peak efficiency (design point efficiency). The isoefficiency line and speed range of ≤7% The shaded area enclosed by the curve, Figure 1 Curve 1 represents the maximum speed of the pump during variable speed operation. Curve 2 shows the points A and B on the curve, which are the boundary points of the high-efficiency zone. Curve 3 represents the minimum speed of the pump during variable-speed operation. Curves 3 and 4 are iso-efficiency lines passing through points A and B, respectively. The flow rate, head, and hydraulic efficiency of a pump at a certain pumping station under varying pump speeds are converted using the following formula: (2) In the formula, , , , These refer to the pump's flow rate, head, volumetric efficiency, and hydraulic efficiency, respectively. The subscript 0 represents the rated speed. The corresponding parameters are below; subscript 1 represents any other rotational speed. The corresponding parameters below; The values ​​given in different literature differ, as determined by experiments. =0.16~0.5, taken according to IEC60193. =0.16; It is generally believed that the mechanical efficiency of a water pump changes when its speed changes. and volumetric efficiency Unchanged, that is, having ; If the highest hydraulic efficiency of a pump at a certain pumping station is 93%, then the high-efficiency zone (hydraulic efficiency) of the pump at that pumping station can be obtained. ≥86% Figure 2 As shown.

[0021] In step 2, the water level-related boundaries are dynamically calculated based on the flow-head curve to obtain the dynamic boundaries, specifically: Based on the flow-head curve and combined with the cavitation margin (NPSHa) of the real-time inlet pool water level calculation device, a safety factor is introduced through the critical relationship between the device cavitation margin and the required cavitation margin (NPSHr), the dynamic cavitation boundary points are solved, and the cavitation boundary points at different speeds are correlated to form the left and right cavitation limit lines (the positions of which change with the water level in real time). It is described in detail, among which the cavitation margin of the water pump is also known as the required cavitation margin of the water pump. , is a parameter that only represents the cavitation performance of the water pump itself and is unrelated to the suction conditions of the water pump device. It refers to the cavitation margin when the pressure at the lowest pressure point inside the impeller is exactly equal to the vaporization pressure of the water being pumped (bubbles were observed in the three blades in the model experiment). In essence, it is the head loss when the water at the pump inlet flows to the lowest pressure point inside the impeller and the pressure drops to the vaporization pressure. Its theoretical expression is: (3) Equation (3) is also known as the basic equation for cavitation of a pump. This is the pressure drop coefficient caused by the change in absolute flow velocity at the blade inlet and the hydraulic losses from the pump inlet to the blade inlet. This is the pressure drop coefficient caused by the change in relative velocity at the blade inlet and the liquid flowing around the blade tip. Currently, the pressure drop coefficient... and Since it cannot be obtained through theoretical calculations, the required cavitation margin cannot be determined by calculation. It needs to be determined through pump cavitation performance testing; If the rated speed The water pump flow rate ~Primitive cavitation The performance curve can be represented by a general polynomial as follows: (4) In the formula, , This indicates the measured flow rate of the water pump at rated speed, representing the first-order cavitation performance. Data points, ,common One measured point, The coefficients of the polynomial, If is the highest power of the polynomial, then any rotational speed within the applicable range of the similarity law... Below, the water pump flow rate ~Primitive cavitation The performance curve can be represented as: (5) In the formula, , ; The cavitation margin of a pumping station is also known as the effective cavitation margin or the device cavitation margin. (The subscript "pl" stands for "plant") refers to the energy remaining after subtracting the vaporization head from the unit energy supplied to the pump inlet section by the water pump suction device, which is the cavitation margin provided by the suction device. like Figure 3As shown, the energy equations for the inlet pool surface and the pump reference plane are as follows: (6) From the definition of cavitation margin of the device: (7) Therefore, the cavitation margin provided by the device, i.e., the cavitation margin of the pump station, is: (8) In the formula, This refers to the installation height of the water pump. The elevation of the plane where the pressure is lowest. This refers to the water level in the inlet pool. This refers to the surface pressure of the inlet pool. This refers to the vaporization pressure. Water pump inlet side losses; The gravitational acceleration at the test site; Density; To the right of the point of highest efficiency The change in flow rate is an upward curve, such as... Figure 4 As shown, Figure 4 medium curve Q~ This is a curve showing the relationship between effective cavitation margin and flow rate, assuming constant water temperature, pressure on the suction surface, and pump installation height. It is a parabola that decreases as the flow rate increases. and Flow rate at the intersection of curves The critical flow rate is the dividing point at which cavitation occurs in a water pump. hour, < The water pump will experience cavitation, so the water pump cannot be used in this situation. Operating in the unsafe zone, the situation is similar to that to the left of the highest efficiency point, when... hour, < The water pump will experience cavitation, so the water pump cannot be used in this situation. The pump operates in an unsafe zone; therefore, the safe operating zone where cavitation does not occur is... ; This section introduces the determination of cavitation restriction zones, specifying that water pumps must not generate primary cavitation. ,when The critical state is reached when bubbles are observed on all three blades in the experiment. Considering the significant difference between the actual operating environment of the pump and the laboratory environment, to ensure that no cavitation bubbles appear around the blades, it can be set as follows: = (1.03~1.05) Solving this equation yields the flow rates for both the left and right sides. , Substituting these two flow rates into equation (1), the corresponding head can be obtained. , When the water pump operating point is between and Primary cavitation does not occur between these periods; Given a rotational speed, we can obtain two flow rates and corresponding heads on the left and right. Given another rotational speed, we can obtain two more flow rates and corresponding heads on the left and right. Connect all the points on the left side to form a curve, and connect all the points on the right side to form a curve as well. The part between the left and right curves is the safe operating area where cavitation does not occur. Once the pump system is installed, under standard conditions, the size of the area where cavitation does not occur is related to the inlet water level and the suction side resistance coefficient (the change in roughness has little impact on the hydraulic loss on the suction side, so the effect of the resistance coefficient change can be ignored), i.e., it is related to the submersion depth (or installation height). The greater the submersion depth, the wider the safe zone without cavitation; conversely, the smaller the submersion depth, the narrower the safe zone without cavitation. The safe operating area where the pump does not experience initial cavitation at the maximum inlet water level of a certain pumping station is as follows: Figure 6 As shown.

[0022] In step 3, the stability boundary is calculated based on the flow-head curve, specifically as follows: Generate hump limit lines based on flow-head curves; The left and right pressure pulsation limit lines are generated based on the flow-head curve.

[0023] The hump limit line is generated based on the flow-head curve, specifically as follows: Based on the curve of the high-efficiency zone of the flow-head curve, the hump limit point at rated speed is calculated using the hump margin formula. By extending the similarity law to various rotational speeds, a hump limit line is generated. It is described in detail below: like Figure 7 As shown, the hump margin is given by the following formula: (9) In the formula, For hump margin, , It is the head at the bottom of the hump when the system frequency is at its minimum (49.8Hz). This corresponds to the pump head at the maximum static head of the device when the system frequency is at its minimum. The "Design Code for Pumped Storage Power Stations" (NB / T 10072—2018) stipulates that within the normal frequency variation range of the power grid (49.5~50.5Hz), the margin between the maximum head of the pump under operating conditions and the starting point of the valley in the secondary return hump should not be less than 2%. It is generally considered that the safety margin in the hump area during stable pump operation should be ≥3%. The flow rate-head curve of a pump at a certain pumping station is as follows: Figure 7 As shown, the flow rate corresponding to the hump and trough at rated speed. =7.28m 3 / s, head =43.20m, in equation (9) let =3%, from which we can obtain ≈41.94m, then based on the water pump The curve expression (1) can be obtained. Corresponding traffic =8.66m 3 / s, point A This is the hump limit point of the water pump at its rated speed. The area to the left of this point is the unstable operating region, and the area to the right is the stable operating region. The flow rate at the hump limit point at other speeds is... He Yangcheng Given by similarity relations, i.e. = , = In the formula The symbols have the same meaning as in equation (5). Connecting the hump limit points at each speed, the resulting hump limit line is as follows: Figure 8 As shown, the area to the left of the limit line is the unstable operating region, and the area to the right is the stable operating region.

[0024] The left and right pressure pulsation limit lines are generated based on the flow-head curve, specifically: Obtain the model pressure pulsation data and convert it to the prototype according to the similarity law; Based on the flow-head curve, with pressure pulsation amplitude ≤7% as a constraint, the left and right boundary points at each speed are determined; Connect the left and right boundary points at each speed to form the left and right pressure pulsation limit lines; It is described in detail: Under favorable conditions for model testing and without significant interference to external systems, the pressure pulsation amplitude can be reasonably converted from the model to the prototype. Under good test conditions, the uncertainty of the prototype prediction can be expected to reach: a) amplitude: ±30%; b) dominant frequency: 3-5% of the prototype switching frequency; c) phase difference: ±30°; According to the basic similarity law, relevant data on the prototype can be obtained from the model test values ​​through conversion. It is generally customary to use dimensionless quantities to represent the conversion relationship between the model and the prototype. Relative pressure pulsation (pressure pulsation factor): or (10) The pulsation frequency coefficient is: (11) In the formula, Energy per unit mass For density, For Yang Cheng, This refers to relative pressure pulsation. The pulsation frequency, The impeller frequency; The pressure pulsation value between the impeller outlet and the guide vane inlet of a certain pumping station is calculated from the model to the prototype result as follows: Figure 9 As shown, the pressure pulsation limit within the stable operating range is assumed to be... The flow rates on the left and right sides can be determined from the pressure pulsation amplitude curve at rated speed. =6.81m 3 / s, =14.02m 3 / s, then according to the water pump The curve expression (1) can be obtained. Corresponding head =43.73m 3 / s, point This is the left-side limiting point of the pressure pulsation of the water pump at rated speed. To the left of this point is the high-pressure pulsation region, and to the right is the low-pressure pulsation region. Similarly, we can obtain... Corresponding head =23.44m 3 / s, point This is the right-hand limit point for pressure pulsation of the water pump at rated speed. To the left of this point is the low-pressure pulsation zone, and to the right is the high-pressure pulsation zone. The flow rate at the pressure pulsation limit point at other speeds... He Yangcheng The similarity relation is given by, i.e. = , = In the formula The symbols have the same meaning as in equation (5). Connecting the left and right pressure pulsation limiting points at all speeds, we can obtain the pressure pulsation limiting lines as shown in equation (5). Figure 10 As shown, the area between the left and right limit lines is a low-pressure pulsation zone.

[0025] In step 4, the static boundary, dynamic boundary, and stability boundary are integrated to form the stable operating threshold range of the water pump, specifically: Obtain the maximum required head limit line, minimum required head limit line, maximum speed limit line, minimum speed limit line, right cavitation limit line, hump limit line and left pressure pulsation limit line, and take the common overlapping area of ​​all boundary lines to form the stable operation threshold range of the water pump; A detailed introduction to it: The threshold range for stable operation of a water pump is determined by the following factors: (1) the high-efficiency zone of the water pump; (2) the zone without initial cavitation; (3) the hump margin limit; (4) the relative amplitude (relative peak-to-peak value) limit of pressure pulsation; (5) the maximum and minimum required head limits; and (6) the maximum and minimum speed limits.

[0026] The threshold range for stable operation of water pumps in a certain pumping station is as follows: Figure 11 As shown, the area is defined by the hump limit line, the maximum required head line, the minimum required head line, the cavitation limit line on the right, and the maximum speed limit line. Different pumping stations use different pumps with different performance characteristics, so the limit lines will also be different and need to be determined according to the specific situation.

[0027] This invention also provides a system for determining the stable operation threshold range of a water pump based on multi-parameter constraints, applied to the aforementioned method for determining the stable operation threshold range of a water pump based on multi-parameter constraints, comprising: The data acquisition and processing unit is used to acquire water pump performance test data, real-time inlet pool water level data, and pressure pulsation data. The basic performance framework determination unit is connected to the data acquisition and processing unit. It is used to generate a flow-head curve based on the water pump performance test data, delineate the high-efficiency zone based on the flow-head curve, and preset the head limit line and speed limit line. The dynamic boundary calculation unit, connected to the data acquisition and processing unit and the basic performance framework determination unit, is used to calculate the cavitation margin of the device based on the flow-head curve and the real-time water level of the inlet pool. It also introduces a safety factor through the critical relationship between the dynamic boundary calculation unit and the required cavitation margin, solves the dynamic cavitation boundary point, and generates the dynamic cavitation limit line. The stability boundary calculation unit, connected to the basic performance framework determination unit, is used to calculate and generate the hump limit line and pressure pulsation limit line based on the flow-head curve. The integrated output unit is connected to the basic performance framework determination unit, the dynamic boundary calculation unit, and the stability boundary calculation unit, respectively. It is used to integrate the static limit boundary, the dynamic cavitation limit line, the hump limit line, and the pressure pulsation limit line, take the common overlapping area of ​​all boundaries, and construct and output the stable operation threshold range of the water pump.

[0028] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0029] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for determining the stable operation threshold range of a water pump based on multi-parameter constraints, characterized in that, include: Step 1: Determine the basic performance framework and obtain the flow-head curve and static limit boundaries; Step 2: Dynamically calculate the water level-related boundaries based on the flow-head curve to obtain the dynamic boundaries; Step 3: Calculate the stability boundary based on the flow-head curve; Step 4: Integrate the static boundary, dynamic boundary, and stability boundary to form the stable operation threshold range of the water pump.

2. The method according to claim 1, characterized in that, In step 1, the basic performance framework is determined, and the flow-head curve and static limit boundaries are obtained, specifically: Based on the pump test data, a flow-head curve was fitted, and the high-efficiency zone was defined; Preset static limit boundaries, including setting the maximum and minimum required head limit lines according to engineering requirements, and setting the maximum and minimum speed limit lines according to pump performance.

3. The method according to claim 2, characterized in that, The high-efficiency zone is the envelope region where the highest efficiency decreases by ≤7%.

4. The method according to claim 1, characterized in that, In step 2, the water level-related boundaries are dynamically calculated based on the flow-head curve to obtain the dynamic boundaries, specifically: Based on the flow-head curve and combined with the cavitation margin of the real-time inlet pool water level calculation device, a safety factor is introduced through the critical relationship between the device cavitation margin and the required cavitation margin to solve the dynamic cavitation boundary point, and the cavitation boundary points at different speeds are correlated to form the left and right cavitation limit lines.

5. The method according to claim 1, characterized in that, In step 3, the stability boundary is calculated based on the flow-head curve, specifically as follows: Generate hump limit lines based on flow-head curves; The left and right pressure pulsation limit lines are generated based on the flow-head curve.

6. The method according to claim 5, characterized in that, The hump limit line is generated based on the flow-head curve, specifically as follows: Based on the flow-head curve, the hump limit point at rated speed is calculated using the hump margin formula. By extending the similarity law to various rotational speeds, a hump limit line is generated.

7. The method according to claim 5, characterized in that, The left and right pressure pulsation limit lines are generated based on the flow-head curve, specifically: Obtain the model pressure pulsation data and convert it to the prototype according to the similarity law; Based on the flow-head curve, with pressure pulsation amplitude ≤7% as a constraint, the left and right boundary points at each speed are determined; Connect the left and right boundary points at each determined speed to form the left and right pressure pulsation limit lines.

8. The method according to claim 7, characterized in that, In step 4, the static boundary, dynamic boundary, and stability boundary are integrated to form the stable operating threshold range of the water pump, specifically: Obtain the maximum required head limit line, minimum required head limit line, maximum speed limit line, minimum speed limit line, left cavitation limit line, right cavitation limit line, hump limit line, left pressure pulsation limit line, and right pressure pulsation limit line. Take the common overlapping area of ​​all boundary lines to form the stable operating threshold range of the water pump.

9. A system for determining the stable operation threshold range of a water pump based on multi-parameter constraints, applied to the method for determining the stable operation threshold range of a water pump based on multi-parameter constraints as described in any one of claims 1-8, characterized in that, include: The data acquisition and processing unit is used to acquire water pump performance test data, real-time inlet pool water level data, and pressure pulsation data. The basic performance framework determination unit is connected to the data acquisition and processing unit. It is used to generate a flow-head curve based on the water pump performance test data, delineate the high-efficiency zone based on the flow-head curve, and preset the head limit line and speed limit line. The dynamic boundary calculation unit, connected to the data acquisition and processing unit and the basic performance framework determination unit, is used to calculate the cavitation margin of the device based on the flow-head curve and the real-time water level of the inlet pool. It also introduces a safety factor through the critical relationship between the dynamic boundary calculation unit and the required cavitation margin, solves the dynamic cavitation boundary point, and generates the dynamic cavitation limit line. The stability boundary calculation unit, connected to the basic performance framework determination unit, is used to calculate and generate the hump limit line and pressure pulsation limit line based on the flow-head curve. The integrated output unit is connected to the basic performance framework determination unit, the dynamic boundary calculation unit, and the stability boundary calculation unit, respectively. It is used to integrate the static limit boundary, the dynamic cavitation limit line, the hump limit line, and the pressure pulsation limit line, take the common overlapping area of ​​all boundaries, and construct and output the stable operation threshold range of the water pump.

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