A control system and method for a variable frequency pump

Abstract

The embodiment of the present application provides a kind of control system and method of variable frequency pump, the system includes: control module;The control module is used to obtain and according to the current rotational speed rate and current power of the variable frequency pump detected, and the current flow and current lift of the variable frequency pump are calculated according to the performance curve model determined in advance, wherein the performance curve model determined in advance is used to characterize the corresponding relationship between rotational speed rate, power, flow, lift and efficiency;According to the current flow and target flow of the variable frequency pump, the variable frequency pump is adjusted, or, according to the current lift and target lift of the variable frequency pump, the variable frequency pump is adjusted. Through the scheme of the present application, it can be convenient to adjust the variable frequency pump according to the current flow and target flow of the variable frequency pump, or, according to the current lift and target lift of the variable frequency pump, the variable frequency pump is adjusted, to solve the problem of the acquisition and adjustment of the flow of variable frequency pump.

Description

Technical Field

[0001] This application relates to the field of information technology, and in particular to a control system and method for a variable frequency pump. Background Technology

[0002] During the use of variable frequency pumps, by detecting the pump's flow rate (or head), it is easy to adjust the pump according to the target water supply flow rate (or head). For example, if the current flow rate (or head) of the variable frequency pump is less than the target water supply flow rate (or head), the water supply flow rate (or head) can be adjusted by increasing the pump's speed. However, in actual use, some variable frequency pumps often lack flow rate (or head) sensors or have malfunctioning sensors, making it impossible to obtain flow rate or head information and hindering the adjustment of the variable frequency pump. Summary of the Invention

[0003] The purpose of this application is to provide a control system and method for a variable frequency pump, to solve the problem of how to acquire and adjust the flow rate of the variable frequency pump. The specific technical solution is as follows:

[0004] In a first aspect, this application provides a control system for a variable frequency pump, the system comprising: a control module; the control module being used to control and regulate the variable frequency pump;

[0005] The control module is used to acquire and calculate the current flow rate and current head of the variable frequency pump based on the detected current speed and current power of the variable frequency pump, and a pre-determined performance curve model, wherein the pre-determined performance curve model is used to characterize the correspondence between speed, power, flow rate, head and efficiency; and to adjust the variable frequency pump according to the current flow rate and target flow rate, or according to the current head and target head of the variable frequency pump.

[0006] In one possible implementation, the control module is further configured to calculate the current efficiency of the variable frequency pump based on the detected current speed and current power of the variable frequency pump, and a predetermined performance curve model.

[0007] The variable frequency pump is adjusted based on the current efficiency and the target efficiency.

[0008] In one possible implementation, the predetermined performance curve model includes: a first correspondence, a second correspondence, and a third correspondence;

[0009] The first correspondence includes a quadratic polynomial used to characterize the correspondence between head and flow rate;

[0010] The second correspondence includes a cubic polynomial used to characterize the correspondence between power and flow rate;

[0011] The third correspondence includes a cubic polynomial used to characterize the correspondence between efficiency and flow.

[0012] In one possible implementation, the predetermined performance curve model is:

[0013]

[0014] Where H is the current head; Q is the current flow rate; k is the current rotational speed; A0, A1, A2, B0, B1, B2, B3, C0, C1, C2, C3 are predetermined characteristic constants; N is the power; and η is the efficiency.

[0015] In one possible implementation, the control module is specifically used to calculate the current flow rate and current head of the variable frequency pump based on the detected current speed, current power, efficiency range, and speed range of the variable frequency pump, as well as a predetermined performance curve model, wherein the efficiency range is greater than 0 and less than 1, and the speed range is greater than 0.5 and less than 1.

[0016] In one possible implementation, the system further includes: a frequency converter;

[0017] The frequency converter is used to collect the current rotational speed and current power of the frequency converter pump and send them to the control module.

[0018] In one possible implementation, the process of creating the predetermined performance curve model includes:

[0019] Create a fourth correspondence between flow rate and head, a fifth correspondence between flow rate and power, and a sixth correspondence between flow rate and efficiency for the variable frequency pump. The fourth correspondence includes a quadratic polynomial characterizing the correspondence between head and flow rate, the fifth correspondence includes a cubic polynomial characterizing the correspondence between power and flow rate, and the sixth correspondence includes a cubic polynomial characterizing the correspondence between efficiency and flow rate.

[0020] The rotational speed of the variable frequency pump is fitted to the fourth, fifth, and sixth correspondences to obtain the first, second, and third correspondences.

[0021] In one possible implementation, the control module is specifically configured to increase the speed of the variable frequency pump when the current flow rate of the variable frequency pump is less than the target flow rate, or when the current head of the variable frequency pump is less than the target head.

[0022] A second aspect of this application provides a control method for a variable frequency pump, comprising:

[0023] The current flow rate and current head of the variable frequency pump are calculated based on the detected current speed and current power of the variable frequency pump, as well as a predetermined performance curve model. The predetermined performance curve model is used to characterize the correspondence between speed, power, flow rate, head and efficiency.

[0024] The variable frequency pump is adjusted based on its current flow rate and target flow rate, or based on its current head and target head.

[0025] In one possible implementation, the method further includes:

[0026] The current efficiency of the variable frequency pump is calculated based on the detected current speed and power of the variable frequency pump, as well as the predetermined performance curve model.

[0027] The variable frequency pump is adjusted based on the current efficiency and the target efficiency.

[0028] In one possible implementation, the predetermined performance curve model includes: a first correspondence, a second correspondence, and a third correspondence;

[0029] The first correspondence includes a quadratic polynomial used to characterize the correspondence between head and flow rate;

[0030] The second correspondence includes a cubic polynomial used to characterize the correspondence between power and flow rate;

[0031] The third correspondence includes a cubic polynomial used to characterize the correspondence between efficiency and flow.

[0032] In one possible implementation, the predetermined performance curve model is:

[0033]

[0034] Wherein, H is the first head; Q is the simulated flow rate; k is the first rotational speed; A0, A1, A2, B0, B1, B2, B3, C0, C1, C2, C3 are predetermined characteristic constants; N is power; and η is efficiency.

[0035] In one possible implementation, calculating the current flow rate and current head of the variable frequency pump based on the detected current speed and current power of the variable frequency pump, and a predetermined performance curve model, includes:

[0036] Based on the detected values ​​of the variable frequency pump's current speed, current power, efficiency, and speed range, and a predetermined performance curve model, the current flow rate and current head of the variable frequency pump are calculated. The efficiency range is greater than 0 and less than 1, and the speed range is greater than 0.5 and less than 1.

[0037] In one possible implementation, the method further includes:

[0038] The current speed and current power of the variable frequency pump are acquired by the frequency converter.

[0039] In one possible implementation, the process of creating the predetermined performance curve model includes:

[0040] Create a fourth correspondence between flow rate and head, a fifth correspondence between flow rate and power, and a sixth correspondence between flow rate and efficiency for the variable frequency pump. The fourth correspondence includes a quadratic polynomial characterizing the correspondence between head and flow rate, the fifth correspondence includes a cubic polynomial characterizing the correspondence between power and flow rate, and the sixth correspondence includes a cubic polynomial characterizing the correspondence between efficiency and flow rate.

[0041] The rotational speed of the variable frequency pump is fitted to the fourth, fifth, and sixth correspondences to obtain the first, second, and third correspondences.

[0042] In one possible implementation, adjusting the variable frequency pump based on its current flow rate and target flow rate, or adjusting the variable frequency pump based on its current head and target head, includes:

[0043] When the current flow rate of the variable frequency pump is less than the target flow rate, or when the current head of the variable frequency pump is less than the target head, the speed of the variable frequency pump is increased. Another aspect of this application embodiment also provides an electronic device, including:

[0044] Memory, used to store computer programs;

[0045] The processor, when executing the program stored in the memory, implements any of the above-mentioned control methods for the variable frequency pump.

[0046] In another aspect of the embodiments of this application, a computer-readable storage medium is provided, which stores a computer program that, when executed by a processor, implements any of the above-described variable frequency pump control methods.

[0047] In another aspect of the embodiments of this application, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute any of the above-described variable frequency pump control methods.

[0048] Beneficial effects of the embodiments in this application:

[0049] This application provides a control system and method for a variable frequency pump. The system includes a control module for controlling and adjusting the variable frequency pump. The control module is used to acquire and calculate the current flow rate and current head of the variable frequency pump based on the detected current rotational speed and current power, and a predetermined performance curve model. The predetermined performance curve model characterizes the relationship between rotational speed, power, flow rate, head, and efficiency. The control module also adjusts the variable frequency pump based on its current flow rate and target flow rate, or based on its current head and target head. This solution allows for the calculation of the current flow rate of the variable frequency pump using a predetermined performance curve model, based only on the current rotational speed and current power. This facilitates adjustments to the pump based on its current flow rate and target flow rate, or based on its current head and target head, thus solving the problem of acquiring and adjusting the flow rate of the variable frequency pump.

[0050] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.

[0052] Figure 1 A schematic diagram of a control system for a variable frequency pump provided in an embodiment of this application;

[0053] Figure 2 A performance curve of a pump is provided for an embodiment of this application;

[0054] Figure 3 A pump performance data graph is provided for an embodiment of this application;

[0055] Figure 4 A fitting curve diagram of pump head and flow rate provided for embodiments of this application;

[0056] Figure 5A fitting curve diagram of pump efficiency and flow rate provided for an embodiment of this application;

[0057] Figure 6 A fitting curve diagram of pump shaft power and flow rate provided for embodiments of this application;

[0058] Figure 7 A numerical relationship diagram between pump shaft power and flow rate provided for embodiments of this application;

[0059] Figure 8 A schematic flowchart of a variable frequency pump control method provided in an embodiment of this application;

[0060] Figure 9 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0061] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0062] When testing the operating parameters of a water pump, it is often necessary to obtain parameters such as the pump's flow rate. These parameters are then used to calculate other operating parameters, such as power and efficiency. However, in certain special circumstances, it is often impossible to test the pump's flow rate. For example, during pump startup, the pump's outlet valve may be closed, resulting in no flow and making it impossible to obtain other operating parameters such as power and efficiency.

[0063] The first aspect of this application's embodiments provides a control system for a variable frequency pump, see [link to relevant documentation]. Figure 1 The system includes: a control module 101; the control module 101 is used to control and regulate the variable frequency pump;

[0064] The control module 101 is used to acquire and calculate the current flow rate and current head of the variable frequency pump based on the detected current speed and current power of the variable frequency pump and a predetermined performance curve model, wherein the predetermined performance curve model is used to characterize the correspondence between speed, power, flow rate, head and efficiency; and to adjust the variable frequency pump according to the current flow rate and target flow rate, or according to the current head and target head of the variable frequency pump.

[0065] In this embodiment, the rotational speed k is the ratio of the pump's operating speed to its rated speed. In this embodiment, the power and rotational speed of the variable frequency pump can be directly acquired, or calculated from the pump's operating data. For example, the pump's speed can be directly acquired, and the current rotational speed can be obtained by calculating the ratio of the speed to the rated speed; similarly, the pump's operating voltage and current can be directly acquired, and the pump's power can be obtained by calculating their product. Specifically, the variable frequency centrifugal pump in this embodiment can have its speed adjusted by a frequency converter. The current rotational speed and current power of the variable frequency pump can be acquired by the frequency converter, and the control module can receive the current rotational speed and current power of the pump when the frequency converter is adjusting it. In one possible implementation, see [link to relevant documentation]. Figure 1 The system further includes a frequency converter 102; the frequency converter is used to collect the current speed and current power of the variable frequency pump and send them to the control module. The frequency converter can control the speed of the AC motor by changing the frequency of the motor's operating power supply. Therefore, when obtaining the speed, the speed can be directly obtained by acquiring the speed of the frequency converter and then calculating the speed using the rated speed.

[0066] In this embodiment, a pre-determined performance curve model is used to characterize the correspondence between rotational speed, power, flow rate, head, and efficiency. In actual use, the performance curve model can be obtained by collecting historical rotational speed, power, flow rate, head, and efficiency data of the variable frequency pump and fitting the performance curve model. The variable frequency pump is adjusted based on its current flow rate and target flow rate, or based on its current head and target head. In one possible implementation, the control module is specifically used to increase the rotational speed of the variable frequency pump when its current flow rate is less than the target flow rate, or when its current head is less than the target head. Specifically, the calculated current flow rate and target flow rate can be compared; if the current flow rate is less than the target flow rate, the pump's rotational speed can be adjusted to increase the flow rate; or, the calculated current head and target head can be compared; if the current head is less than the target head, the pump's rotational speed can be adjusted to increase the head.

[0067] As can be seen, the system of this application can calculate the current flow rate of the variable frequency pump by means of a predetermined performance curve model, based only on the current rotational speed and current power of the variable frequency pump. This facilitates the adjustment of the variable frequency pump according to its current flow rate and target flow rate, or according to its current head and target head, thus solving the problem of how to obtain and adjust the flow rate of the variable frequency pump.

[0068] In one possible implementation, the control module is further configured to calculate the current efficiency of the variable frequency pump based on the detected current rotational speed and current power of the pump, and a pre-determined performance curve model; and to adjust the variable frequency pump based on the current efficiency and a target efficiency. Specifically, the target efficiency can be a pre-set desired pump efficiency. The current efficiency of the variable frequency pump can be calculated using a pre-determined performance curve model, and then compared with the target efficiency. If the current efficiency is less than the target efficiency, the efficiency can be adjusted by changing the pump's rotational speed, etc., thereby improving the efficiency of the variable frequency pump.

[0069] In one possible implementation, the predetermined performance curve model includes: a first correspondence, a second correspondence, and a third correspondence; the first correspondence includes a quadratic polynomial characterizing the relationship between head and flow rate; the second correspondence includes a cubic polynomial characterizing the relationship between power and flow rate; and the third correspondence includes a cubic polynomial characterizing the relationship between efficiency and flow rate. The first correspondence can be obtained by fitting an HQ curve (head versus flow rate) and can be a quadratic polynomial; the second correspondence can be obtained by fitting an NQ curve (pump shaft power versus flow rate) and can be a cubic polynomial; the third ... The -Q curve is obtained by fitting the curve of pump efficiency versus flow rate, and this third correspondence can be a cubic polynomial.

[0070] In one possible implementation, the predetermined performance curve model is:

[0071]

[0072] Where H is the current head; Q is the current flow rate; k is the current rotational speed; A0, A1, A2, B0, B1, B2, B3, C0, C1, C2, C3 are predetermined characteristic constants; N is the power; and η is the efficiency.

[0073] The following describes the process of obtaining the first, second, and third correspondence relationships in the embodiments of this application. As those skilled in the art will know, a pump performance curve refers to a curve showing the changes in pump head, power, efficiency, and other indicators with flow rate at a certain operating speed. Pump performance curves are generally obtained by pump manufacturers through hydraulic tests and provided to users as pump performance indicators in the form of curves or data. Figure 2 This is a pump performance curve provided as an embodiment of the present application. In the graph, H represents the pump head, in units of... or N represents shaft power, in kW. Pump efficiency is expressed as %; Q is pump flow rate, expressed as %. The HQ curve is a curve showing the change in head as a function of flow rate. The -Q curve represents the pump efficiency as a function of flow rate, and the NQ curve represents the pump shaft power as a function of flow rate. Pump performance curves are inherent characteristic curves of the pump itself; their shape reflects the pump's inherent characteristics and is independent of the pump's operating conditions. Measuring the pump's shaft power is relatively difficult, while the power of its driving motor is easier to obtain. Since motor efficiency is relatively stable, motor power is generally used to represent shaft power. The resulting power and efficiency performance curves represent the pump unit's performance curves.

[0074] Specifically, by fitting the performance curve data of the pump unit, the functional expressions of each performance parameter and flow rate of the pump unit are obtained, which is the mathematical model of the pump unit performance curve. Generally, a polynomial is used as the mathematical model of the pump unit performance curve, and the coefficients of each degree of the polynomial in the mathematical model are obtained by using the least squares method. The mathematical model of the performance curve of the pump when it is running at rated speed can generally be expressed by a quadratic or cubic polynomial to meet the requirements of engineering accuracy, as shown in equations (1), (2), and (3). The coefficients in the equations are... , , , , These are characteristic constants related to the pump unit itself and are independent of the pump's operating conditions. The head H is fitted using a quadratic polynomial, while the power N and efficiency... A cubic polynomial is used for fitting.

[0075]

[0076] If the pump operates with variable frequency speed control, the concept of speed k is introduced here. Speed ​​k is the ratio of the pump's operating speed to its rated speed. When the pump is under load, the speed must not exceed the rated speed, otherwise it will cause motor overload. Therefore, 0≤k≤1, and in practical applications, 0.5≤k≤1. The mathematical model of the performance curve of the variable frequency speed control pump is shown in equations (4), (5) and (6).

[0077]

[0078] In equations (4), (5) and (6), the rotational speed k and power N are real-time parameters inside the frequency converter and can be easily obtained.

[0079] In one possible implementation, the process of creating the predetermined performance curve model includes: creating a fourth correspondence between the flow rate and head of the variable frequency pump, a fifth correspondence between the flow rate and power, and a sixth correspondence between the flow rate and efficiency. The fourth correspondence includes a quadratic polynomial characterizing the correspondence between head and flow rate, the fifth correspondence includes a cubic polynomial characterizing the correspondence between power and flow rate, and the sixth correspondence includes a cubic polynomial characterizing the correspondence between efficiency and flow rate. The variable frequency pump's rotational speed is then fitted to the fourth, fifth, and sixth correspondences to obtain the first, second, and third correspondences. The fourth, fifth, and sixth correspondences can correspond to formulas (1), (2), and (3) respectively, and the first, second, and third correspondences can correspond to formulas (4), (5), and (6) respectively. Further, the identification of the variable frequency pump's operating parameters involves... , , , , When the characteristic constants of the pump unit are known, the pump head H, pump flow rate Q, and pump unit efficiency can be calculated in real time using a mathematical model of the variable frequency pump unit's performance curve. This enables sensorless online identification of hydraulic parameters and operating efficiency parameters of water pump units, providing technical support for the informatization and optimized control of pump stations. In equation (5), , Given N and k, the value of Q can be calculated. However, since this is a cubic equation, it is very difficult and computationally intensive to find the value of Q by solving the equation. Here, a table lookup and linear interpolation method is used, which can better solve the problems of calculation accuracy and computational workload. In equation (5), the power N and the flow rate Q and the rotational speed k are related, and the flow rate Q cannot be directly obtained by the table lookup method. It is necessary to transform them. The normalization method is used to process Q and N to obtain the result. For rated power, For the return flow rate. Let:

[0080]

[0081] Substituting equations (8) and (9) into equation (5) and transforming them, we get:

[0082]

[0083] As can be seen from equation (10), after the transformation Only with Value association. Because... The value is known and follows If the value is monotonically increasing, it can be obtained by looking up a table and using linear interpolation. Then, the flow rate Q value is obtained by equation (8).

[0084] Substituting the rotational speed k and the obtained flow rate Q into equation (4) yields the head H. Similarly, substituting the rotational speed k and the obtained flow rate Q into equation (6) yields the efficiency. This completes the online identification of the operating parameters of the variable frequency water pump.

[0085] In one possible implementation, the control module is specifically used to calculate the current flow rate and current head of the variable frequency pump based on the detected current speed, current power, efficiency range, and speed range of the variable frequency pump, as well as a predetermined performance curve model, wherein the efficiency range is greater than 0 and less than 1, and the speed range is greater than 0.5 and less than 1.

[0086] The solution in this application embodiment can embed the pump unit performance curve model into the frequency converter, enabling a dedicated frequency converter for smart pump units. This allows for monitoring of the pump unit's hydraulic conditions and operating efficiency under conditions without flow and pressure detection, and has high practical value.

[0087] To illustrate the solution of this application, the following description is provided in conjunction with a specific embodiment:

[0088] A certain variable frequency centrifugal water pump has a rated head of 51m and a rated flow rate of 740. The rated efficiency is 88%, and the rated motor power is 160kW. The pump performance curve data provided by the pump manufacturer is as follows: Figure 3 Convert traffic data into Through curve fitting, the quadratic polynomial expressions for the HQ curve and the NQ curve at rated speed were obtained. The cubic polynomial expressions for the -Q curve are shown in equations (11), (12), and (13).

[0089]

[0090] Figure 4 , Figure 5 and Figure 6 These are the fitted curves of equations (10), (11), and (12).

[0091] The mathematical models of the performance curves of the variable frequency speed control pump are shown in equations (13), (14), and (15):

[0092]

[0093] and Numerical relationships such as Figure 7 , For rated power, For return flow. Due to Since this is known, the result can be easily obtained by using a lookup table combined with linear interpolation. The value is obtained by transforming the value, and then the Q value is obtained. Substituting the rotational speed k and the obtained flow rate Q into equation (14) yields the head H. Similarly, substituting the rotational speed k and the obtained flow rate Q into equation (16) yields the efficiency. .

[0094] For example, if the measured power in actual operation is 100kW, the operating frequency is 45.8Hz, and the rated frequency is 50Hz, then the rotational speed is... ,but The result was obtained by looking up the table and using linear interpolation. Flow rate is obtained by transformation Substituting the values ​​of k and Q into equations (14) and (16), we obtain the head H = 46.3 m and the efficiency... =86.06%.

[0095] A second aspect of this application provides a control method for a variable frequency pump, see [link to relevant documentation]. Figure 8 ,include:

[0096] Step S81: Obtain and calculate the current flow rate and current head of the variable frequency pump based on the detected current speed and current power of the variable frequency pump and the predetermined performance curve model, wherein the predetermined performance curve model is used to characterize the correspondence between speed, power, flow rate, head and efficiency.

[0097] Step S82: Adjust the variable frequency pump according to its current flow rate and target flow rate, or adjust the variable frequency pump according to its current head and target head.

[0098] In one possible implementation, the method further includes:

[0099] The current efficiency of the variable frequency pump is calculated based on the detected current speed and power of the variable frequency pump, as well as the predetermined performance curve model.

[0100] The variable frequency pump is adjusted based on the current efficiency and the target efficiency.

[0101] In one possible implementation, the predetermined performance curve model includes: a first correspondence, a second correspondence, and a third correspondence;

[0102] The first correspondence includes a quadratic polynomial used to characterize the correspondence between head and flow rate;

[0103] The second correspondence includes a cubic polynomial used to characterize the correspondence between power and flow rate;

[0104] The third correspondence includes a cubic polynomial used to characterize the correspondence between efficiency and flow.

[0105] In one possible implementation, the predetermined performance curve model is:

[0106]

[0107] Wherein, H is the first head; Q is the simulated flow rate; k is the first rotational speed; A0, A1, A2, B0, B1, B2, B3, C0, C1, C2, C3 are predetermined characteristic constants; N is power; and η is efficiency.

[0108] In one possible implementation, calculating the current flow rate and current head of the variable frequency pump based on the detected current speed and current power of the variable frequency pump, and a predetermined performance curve model, includes:

[0109] Based on the detected values ​​of the variable frequency pump's current speed, current power, efficiency, and speed range, and a predetermined performance curve model, the current flow rate and current head of the variable frequency pump are calculated. The efficiency range is greater than 0 and less than 1, and the speed range is greater than 0.5 and less than 1.

[0110] In one possible implementation, the method further includes:

[0111] The current speed and current power of the variable frequency pump are acquired by the frequency converter.

[0112] In one possible implementation, the process of creating the predetermined performance curve model includes:

[0113] Create a fourth correspondence between flow rate and head, a fifth correspondence between flow rate and power, and a sixth correspondence between flow rate and efficiency for the variable frequency pump. The fourth correspondence includes a quadratic polynomial characterizing the correspondence between head and flow rate, the fifth correspondence includes a cubic polynomial characterizing the correspondence between power and flow rate, and the sixth correspondence includes a cubic polynomial characterizing the correspondence between efficiency and flow rate.

[0114] The rotational speed of the variable frequency pump is fitted to the fourth, fifth, and sixth correspondences to obtain the first, second, and third correspondences.

[0115] In one possible implementation, adjusting the variable frequency pump based on its current flow rate and target flow rate, or adjusting the variable frequency pump based on its current head and target head, includes:

[0116] When the current flow rate of the variable frequency pump is less than the target flow rate, or when the current head of the variable frequency pump is less than the target head, the speed of the variable frequency pump is increased.

[0117] As can be seen, the method of this application allows for the calculation of the current flow rate of the variable frequency pump by using a pre-determined performance curve model, based solely on the current rotational speed and current power of the pump. This facilitates the adjustment of the variable frequency pump based on its current and target flow rates, or its current and target head, thus solving the problem of how to obtain and adjust the flow rate of the variable frequency pump.

[0118] This application also provides an electronic device, such as... Figure 9 As shown, it includes:

[0119] Memory 901 is used to store computer programs;

[0120] When processor 902 executes a program stored in memory 901, it performs the following steps:

[0121] The current flow rate and current head of the variable frequency pump are calculated based on the detected current speed and current power of the variable frequency pump, as well as a predetermined performance curve model. The predetermined performance curve model is used to characterize the correspondence between speed, power, flow rate, head and efficiency.

[0122] The variable frequency pump is adjusted based on its current flow rate and target flow rate, or based on its current head and target head.

[0123] The communication bus mentioned in the above electronic devices can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into address bus, data bus, control bus, etc. For ease of illustration, only one thick line is used to represent it in the diagram, but this does not mean that there is only one bus or one type of bus.

[0124] The communication interface is used for communication between the aforementioned electronic devices and other devices.

[0125] The memory may include random access memory (RAM) or non-volatile memory (NVM), such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0126] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0127] In another embodiment provided in this application, a computer-readable storage medium is also provided, which stores a computer program that, when executed by a processor, implements the steps of any of the above-described variable frequency pump control methods.

[0128] In another embodiment provided in this application, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute any of the variable frequency pump control methods described above.

[0129] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a solid-state drive (SSD), etc.

[0130] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0131] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the method, electronic device, and storage medium embodiments are basically similar to the system embodiments, so the descriptions are relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0132] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. A control system for a variable frequency pump, characterized in that, The system includes: a control module; the control module is used to control and regulate the variable frequency pump; The control module is used to obtain the current rotational speed and current power of the variable frequency pump; Based on the current rotational speed and current power, and a predetermined performance curve model, the current flow rate and current head of the variable frequency pump are calculated, wherein the predetermined performance curve model is used to characterize the correspondence between rotational speed, power, flow rate, head and efficiency. The variable frequency pump is adjusted according to its current flow rate and target flow rate, or according to its current head and target head. The predetermined performance curve model is as follows: Where H is the current head; Q is the current flow rate; k is the current rotational speed; A0, A1, A2, B0, B1, B2, B3, C0, C1, C2, C3 are predetermined characteristic constants; N is the current power; and η is the efficiency. The control module is specifically used for: The normalized power is obtained by processing Q and N using a normalization method. Returned flow ; Will and Substitution After transformation, we get: Transformed Only with Value association, Value through Calculated, and Value follows Monotonically increasing, obtained through table lookup and linear interpolation. Then through Find the current flow Q; Substitute the current rotational speed k and the calculated current flow rate Q into... Find the current head H; The control module is specifically used to calculate the current flow rate and current head of the variable frequency pump based on the detected current speed, current power, efficiency range, and speed range of the variable frequency pump, as well as a pre-determined performance curve model. The efficiency range is greater than 0 and less than 1, and the speed range is greater than 0.5 and less than 1.

2. The system according to claim 1, characterized in that, The control module is also used to calculate the current efficiency of the variable frequency pump based on the detected current speed and current power of the variable frequency pump, as well as a predetermined performance curve model. The variable frequency pump is adjusted based on the current efficiency and the target efficiency.

3. The system according to claim 1, characterized in that, The predetermined performance curve model includes: a first correspondence, a second correspondence, and a third correspondence; The first correspondence includes a quadratic polynomial used to characterize the correspondence between head and flow rate; The second correspondence includes a cubic polynomial used to characterize the correspondence between power and flow rate; The third correspondence includes a cubic polynomial used to characterize the correspondence between efficiency and flow.

4. The system according to claim 1, characterized in that, The system also includes: a frequency converter; The frequency converter is used to collect the current rotational speed and current power of the frequency converter pump and send them to the control module.

5. The system according to claim 3, characterized in that, The process of creating the predetermined performance curve model includes: Create a fourth correspondence between flow rate and head, a fifth correspondence between flow rate and power, and a sixth correspondence between flow rate and efficiency for the variable frequency pump. The fourth correspondence includes a quadratic polynomial characterizing the correspondence between head and flow rate, the fifth correspondence includes a cubic polynomial characterizing the correspondence between power and flow rate, and the sixth correspondence includes a cubic polynomial characterizing the correspondence between efficiency and flow rate. The rotational speed of the variable frequency pump is fitted to the fourth, fifth, and sixth correspondences to obtain the first, second, and third correspondences.

6. The system according to claim 1, characterized in that, The control module is specifically used to increase the speed of the variable frequency pump when the current flow rate of the variable frequency pump is less than the target flow rate, or when the current head of the variable frequency pump is less than the target head.

7. A control method for a variable frequency pump, characterized in that, include: The current flow rate and current head of the variable frequency pump are calculated based on the detected current speed and current power of the variable frequency pump, as well as a predetermined performance curve model. The predetermined performance curve model is used to characterize the correspondence between speed, power, flow rate, head and efficiency. The variable frequency pump is adjusted according to its current flow rate and target flow rate, or according to its current head and target head. The predetermined performance curve model is as follows: Where H is the current head; Q is the current flow rate; k is the current rotational speed; A0, A1, A2, B0, B1, B2, B3, C0, C1, C2, C3 are predetermined characteristic constants; N is the current power; and η is the efficiency. Calculating the current flow rate and current head of the variable frequency pump includes: The normalized power is obtained by processing Q and N using a normalization method. Returned flow ; Will and Substitution After transformation, we get: Transformed Only with Value association, Value through Calculated, and Value follows Monotonically increasing, obtained through table lookup and linear interpolation. Then through Find the current flow Q; Substitute the current rotational speed k and the calculated current flow rate Q into... Find the current head H; The step of calculating the current flow rate and current head of the variable frequency pump based on the detected current speed and power of the pump, and a pre-determined performance curve model, includes: Based on the detected values ​​of the variable frequency pump's current speed, current power, efficiency, and speed range, and a predetermined performance curve model, the current flow rate and current head of the variable frequency pump are calculated. The efficiency range is greater than 0 and less than 1, and the speed range is greater than 0.5 and less than 1.

8. An electronic device, characterized in that, include: Memory, used to store computer programs; A processor, when executing a program stored in memory, implements the method of claim 7.

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