A Variable Frequency Constant Pressure Water Supply Control Method and System

Abstract

The present invention discloses a variable-frequency constant-pressure water supply control method and system, belonging to the technical field of water supply. Among them, a variable-frequency constant-pressure water supply control method includes obtaining a water pressure set value Ps in the pipeline; obtaining a control output value Psc according to the water pressure set value Ps in the pipeline; obtaining a water pressure deviation value Pe in the pipeline according to the control output value Psc; obtaining a water pump speed command v according to the water pressure deviation value Pe in the pipeline; and obtaining the water pump speed command v to complete the variable-frequency constant-pressure water supply control. The present invention introduces a set value change process control module and simultaneously uses an expert proportional-integral control algorithm, liberating the adjustable space of the proportional-integral coefficient. Under the condition of a relatively small water pressure deviation, a relatively large proportional-integral coefficient can be set to improve the water pressure adjustment speed and will not cause overshoot.

Description

Technical Field

[0001] The present invention belongs to the technical field of water supply, and in particular to a variable frequency constant pressure water supply control method and system. Background Art

[0002] The variable frequency constant pressure water supply system occupies less land, is energy-saving, and has a high degree of intelligence. It is widely used in residential water supply, chemical industry, and power fields. When the existing algorithms used in the variable frequency constant pressure water supply control system are applied, the water pressure in the pipeline may quickly rush to the set value, and then exceed the set value and continue to change, that is, the "overshoot" phenomenon occurs. By modifying the integral coefficient in the control algorithm, the overshoot phenomenon can be improved, but another problem will occur: the water pressure regulation process in the pipeline is too slow. Once a valve in the pipeline is opened or closed, it will cause the water pressure in the pipeline to deviate from the set value, and then it takes a long time to recover. In short: in the existing water supply system, there is an irreconcilable contradiction between the water pressure overshoot phenomenon and the regulation speed. It is necessary to improve the working performance of the variable frequency constant pressure water supply system and improve the deficiencies of the existing system solutions. Summary of the Invention

[0003] Object of the Invention: To provide a variable frequency constant pressure water supply control method and system to solve the above problems existing in the prior art.

[0004] Technical Solution: A variable frequency constant pressure water supply control method includes:

[0005] Obtain the water pressure set value Ps in the pipeline;

[0006] Obtain the control output value Psc according to the water pressure set value Ps in the pipeline;

[0007] Obtain the water pressure deviation value Pe in the pipeline according to the control output value Psc;

[0008] Obtain the water pump speed command v according to the water pressure deviation value Pe in the pipeline;

[0009] Obtain the water pump speed command v to complete the variable frequency constant pressure water supply control.

[0010] Further, the calculation formula for obtaining the control output value Psc according to the water pressure set value Ps in the pipeline is as follows:

[0011]

[0012] Wherein, Psc is the output value of the control module, Ps is the water pressure set value in the pipeline, Pso is the initial water pressure value in the pipeline, T is an adjustable parameter and is inversely proportional to the water pressure change speed in the pipeline, t is the running time after the water pressure command Ps is modified, and e is the natural constant.

[0013] Further, the calculation formula for obtaining the water pressure deviation value Pe in the pipeline based on the control output value Psc is as follows:

[0014] Pe = Psc - Pc

[0015] Wherein, Pe is the water pressure deviation value in the pipeline, Psc is the output value of the control module, and Pc is the pressure detection value Pc in the pipeline.

[0016] Further, obtaining the water pump speed command v based on the water pressure deviation value Pe in the pipeline includes:

[0017] Obtaining the integral coefficient Ki based on the water pressure deviation value Pe in the pipeline;

[0018] Obtaining the water pump speed command v by combining the integral coefficient Ki with the proportional coefficient Kp.

[0019] Further, obtaining the integral coefficient Ki based on the water pressure deviation value Pe in the pipeline includes:

[0020] Obtaining the water pressure deviation coefficient i in the pipeline based on the water pressure deviation value Pe in the pipeline;

[0021] Judging whether the water pressure deviation coefficient i in the pipeline is less than 0.25. If so, the integral coefficient Ki is Kib; otherwise, the integral coefficient Ki is Kis;

[0022] Wherein, Pe is the water pressure deviation value in the pipeline, Ps is the set water pressure value in the pipeline, and Kib and Kis are two parameter values of the integral coefficient Ki and Kib > Kis.

[0023] Further, obtaining the water pump speed command v by combining the integral coefficient Ki with the proportional coefficient Kp includes:

[0024] Obtaining the water pressure deviation integral term Ysm based on the integral coefficient Ki;

[0025] Obtaining the water pump speed command v by combining the water pressure deviation integral term Ysm with the proportional coefficient Kp.

[0026] Further, the calculation formula for obtaining the water pressure deviation integral term Ysm based on the integral coefficient Ki is as follows:

[0027] Ysm = Pe * Ki + Ysm'

[0028] Wherein, Ysm is the water pressure deviation integral term, Pe is the water pressure deviation value in the pipeline, Ki is the integral coefficient, and Ysm' is the water pressure deviation integral term at the previous moment.

[0029] Further, the calculation formula for obtaining the water pump speed command v based on the water pressure deviation integral term Ysm and the proportional coefficient Kp is as follows:

[0030] v = Pe * Kp + Ysm

[0031] Wherein, v is the water pump speed command, Pe is the water pressure deviation value in the pipeline, Kp is the controller proportional parameter, and Ysm is the water pressure deviation integral term.

[0032] A variable frequency constant pressure water supply control system includes: a controller and an actuator. The controller and the actuator are electrically connected. The controller includes a set value change process control module, a pressure comparison unit, and an automatic control unit;

[0033] The set value change process control module is used to obtain the water pressure set value Ps in the pipeline and obtain the control output value Psc according to the water pressure set value Ps in the pipeline, and transmit it to the pressure comparison unit;

[0034] The pressure comparison unit is used to obtain the control output value Psc, and obtain the water pressure deviation value Pe in the pipeline according to the pipeline pressure detection value Pc, and transmit it to the automatic control unit;

[0035] The automatic control unit is used to obtain the water pressure deviation value Pe in the pipeline, and obtain the water pump speed command v according to the water pressure deviation value Pe in the pipeline, and transmit it to the actuator;

[0036] The actuator is used to obtain the water pump speed command v, and control the water pump speed according to the water pump speed command v to achieve constant pressure control of the water supply system.

[0037] Beneficial effects: By adding a set value change process control module, the water pressure set value Psc in the pipeline will not have a large mutation after the set value is modified or when starting the machine, effectively controlling the stable change of the water pressure. The present invention introduces a set value change process control module and simultaneously uses an expert proportional integral control algorithm, liberating the adjustable space of the proportional integral coefficient. In the working condition where the water pressure deviation is relatively small, a relatively large proportional integral coefficient can be set to improve the water pressure adjustment speed and will not cause overshoot. Description of the Drawings

[0038] Figure 1 is the flowchart of a variable frequency constant pressure water supply control method provided by the present invention;

[0039] Figure 2 is the control block diagram of a variable frequency constant pressure water supply control method provided by the present invention;

[0040] Figure 3 is the flow block diagram of the specific implementation process of a variable frequency constant pressure water supply control method provided by the present invention;

[0041] Figure 4 It is a structural block diagram of a variable-frequency constant-pressure water supply control system provided by the present invention. Specific implementation mode

[0042] In the following description, a large number of specific details are given to provide a more thorough understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0043] Embodiment 1:

[0044] As Figures 1 to 3 shown, a variable-frequency constant-pressure water supply control method includes:

[0045] S1. Obtain the water pressure set value Ps in the pipeline;

[0046] S2. Obtain the control output value Psc according to the water pressure set value Ps in the pipeline;

[0047] S3. Obtain the water pressure deviation value Pe in the pipeline according to the control output value Psc;

[0048] S4. Obtain the water pump speed command v according to the water pressure deviation value Pe in the pipeline;

[0049] S5. Obtain the water pump speed command v to complete the variable-frequency constant-pressure water supply control.

[0050] The calculation formula for obtaining the control output value Psc according to the water pressure set value Ps in the pipeline is as follows:

[0051]

[0052] Wherein, Psc is the output value of the control module, Ps is the water pressure set value in the pipeline, Pso is the initial water pressure value in the pipeline, T is an adjustable parameter and is inversely proportional to the water pressure change speed in the pipeline, t is the running time after the water pressure command Ps is modified, and e is the natural constant.

[0053] In this embodiment, Pso represents the Ps value before the modification of the pipeline pressure set value - the old Ps value, which is the initial water pressure value in the pipeline. At the moment when the controller runs for the first time at time 0, it is also regarded as a process of Ps change. Pso should be initialized to Pc(0). T is an adjustable parameter used to control the change speed of the water pressure in the pipeline. The larger T is, the gentler the change of the water pressure set value Ps in the pipeline will be after the change. On the contrary, the water pressure in the pipeline will quickly reach the set water pressure. The introduction of the set value process control module can greatly improve the overshoot phenomenon. During the specific implementation, first test the process of the water pump starting at full speed (power frequency starting). Assume that after n seconds, the water pressure in the pipeline can rise from 0 to Ps. During the specific implementation, as long as T>0, the operation effect of the control strategy described in this patent will be higher than that of the prior art. However, when the value of T is too large, although the water pressure rising process is stable, it is too slow. Considering comprehensively, the performance is relatively ideal when T = n.

[0054] The calculation formula for obtaining the water pressure deviation value Pe in the pipeline according to the control output value Psc is as follows:

[0055] Pe = Psc - Pc

[0056] Where, Pe is the water pressure deviation value in the pipeline, Psc is the output value of the control module, and Pc is the pressure detection value Pc in the pipeline.

[0057] Step S4 specifically includes:

[0058] S4-1. Obtain the integral coefficient Ki according to the water pressure deviation value Pe in the pipeline;

[0059] S4-2. Obtain the water pump speed command v according to the integral coefficient Ki in combination with the proportional coefficient Kp.

[0060] Step S4-1 specifically includes:

[0061] S4-1-1. Obtain the water pressure deviation coefficient i in the pipeline according to the water pressure deviation value Pe in the pipeline;

[0062] S4-1-2. Judge whether the water pressure deviation coefficient i in the pipeline is less than 0.25. If so, the integral coefficient Ki is Kib; otherwise, the integral coefficient Ki is Kis;

[0063] Where, Pe is the water pressure deviation value in the pipeline, Ps is the water pressure set value in the pipeline, and Kib and Kis are two parameter values of the integral coefficient Ki and Kib>Kis.

[0064] In this embodiment, the automatic control algorithm in the improved controller is changed from the ordinary proportional-integral control algorithm to the expert proportional-integral control algorithm. Since the control parameters of the ordinary proportional-integral control algorithm are fixed and cannot take into account the requirements of control parameters under different working conditions, the expert proportional-integral control algorithm can change the proportional-integral coefficient according to the working conditions, thus solving the contradiction between the water pressure regulation speed and the water pressure overshoot. The flowchart of the automatic control algorithm of this patent is as shown in Figure 3 , the ordinary proportional-integral control program uses an integral coefficient Ki, and the expert proportional-integral control program uses two integral coefficients Kis and Kib. Kis is relatively small and Kib is relatively large. When the water pressure deviation in the pipeline is relatively small, Kib is used, and the water pressure in the pipeline can be quickly adjusted to the set value; when the water pressure deviation in the pipeline is relatively large, Kis is used, which can reduce the integral saturation phenomenon. The water pressure deviation integral term Ysm is shared under the two working conditions, and the integral coefficient is automatically switched according to the working conditions. In specific implementation, 0.1Kib = Kis, and 0.1 has nothing to do with the environmental variable, but whether to use Kib or Kis is directly related to the environmental variable Pe. Kib and Kis are two values of Ki. When Pe is relatively large, Ki uses Kis. As Pe becomes smaller, Ki changes from Kis to Kib. In specific implementation, Ki is a parameter variable of the controller and has two values: Kib and Kis. For example: Kib = 0.2, Kis = 0.02; if Pe / Ps < 0.25, then let Ki = Kis, otherwise Ki = Kib. In the prior art, Ki has only one value and is fixed. This patent assigns two values to it, and Ki can be switched to different values according to different water pressures.

[0065] Step S3-2 specifically includes:

[0066] S3-2-1. Obtain the water pressure deviation integral term Ysm according to the integral coefficient Ki;

[0067] S3-2-2. Obtain the water pump speed command v according to the water pressure deviation integral term Ysm and the proportional coefficient Kp.

[0068] The calculation formula for obtaining the water pressure deviation integral term Ysm according to the integral coefficient Ki is as follows:

[0069] Ysm = Pe * Ki + Ysm'

[0070] where Ysm is the water pressure deviation integral term, Pe is the water pressure deviation value in the pipeline, Ki is the integral coefficient, and Ysm' is the water pressure deviation integral term at the previous moment.

[0071] The calculation formula for obtaining the water pump speed command v according to the water pressure deviation integral term Ysm and the proportional coefficient Kp is as follows:

[0072] v = Pe * Kp + Ysm

[0073] Among them, v is the water pump speed command, Pe is the water pressure deviation value in the pipeline, Kp is the controller proportional parameter, and Ysm is the integral term of water pressure deviation.

[0074] Embodiment 2:

[0075] As Figure 4 shown, a variable frequency constant pressure water supply system includes: a controller and an actuator, the controller and the actuator are electrically connected, and the controller includes a set value change process control module, a pressure comparison unit, and an automatic control unit;

[0076] The set value change process control module is used to obtain the water pressure set value Ps in the pipeline and obtain a control output value Psc according to the water pressure set value Ps in the pipeline and transmit it to the pressure comparison unit;

[0077] The pressure comparison unit is used to obtain the control output value Psc and obtain the water pressure deviation value Pe in the pipeline according to the pipeline pressure detection value Pc and transmit it to the automatic control unit;

[0078] The automatic control unit is used to obtain the water pressure deviation value Pe in the pipeline and obtain the water pump speed command v according to the water pressure deviation value Pe in the pipeline and transmit it to the actuator;

[0079] The actuator is used to obtain the water pump speed command v and control the water pump speed according to the water pump speed command v to achieve constant pressure control of the water supply system.

[0080] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0081] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of the processes and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate for implementing in the process Figure 1 each process or multiple processes and / or blocksFigure 1 means for the functions specified in one or more boxes.

[0082] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to work in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction means that implements the functions specified in one Figure 1 process or a plurality of processes and / or boxes Figure 1 or more boxes.

[0083] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus, such that a series of operational steps are performed on the computer or other programmable apparatus to produce a computer-implemented process, so that the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one Figure 1 process or a plurality of processes and / or boxes Figure 1 or more boxes.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent substitutions can still be made to the specific embodiments of the present invention, and any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A variable-frequency constant-pressure water supply control method, characterized in that, it includes: Obtain the water pressure set value Ps in the pipeline; Obtain the control output value Psc according to the water pressure set value Ps in the pipeline; Obtain the water pressure deviation value Pe in the pipeline according to the control output value Psc; Obtain the water pump speed command v according to the water pressure deviation value Pe in the pipeline, including: obtain the integral coefficient Ki according to the water pressure deviation value Pe in the pipeline; obtain the water pump speed command v by combining the integral coefficient Ki and the proportional coefficient Kp; The obtaining the integral coefficient Ki according to the water pressure deviation value Pe in the pipeline includes: Obtain the water pressure deviation coefficient i in the pipeline according to the water pressure deviation value Pe in the pipeline; Judge whether the water pressure deviation coefficient i in the pipeline is less than 0.

25. If so, the integral coefficient Ki is Kib, otherwise, the integral coefficient Ki is Kis; Among them, Pe is the water pressure deviation value in the pipeline, Ps is the set water pressure value in the pipeline, and Kib and Kis are two parameter values of the integral coefficient Ki and Kib > Kis; Obtain the water pump speed command v to complete the variable-frequency constant-pressure water supply control; The obtaining the water pump speed command v by combining the integral coefficient Ki and the proportional coefficient Kp further includes: obtain the water pressure deviation integral term Ysm according to the integral coefficient Ki; obtain the water pump speed command v by combining the water pressure deviation integral term Ysm and the proportional coefficient Kp; The calculation formula for obtaining the control output value Psc according to the water pressure set value Ps in the pipeline is as follows: Where Psc is the output value of the control module, Ps is the water pressure set value in the pipeline, Pso is the initial water pressure value in the pipeline, T is an adjustable parameter inversely proportional to the water pressure change speed in the pipeline, t is the running time after the water pressure command Ps is modified, and e is the natural constant.

2. A variable-frequency constant-pressure water supply control method according to claim 1, characterized in that, The calculation formula for obtaining the water pressure deviation value Pe in the pipeline according to the control output value Psc is as follows: Pe = Psc - Pc Where Pe is the water pressure deviation value in the pipeline, Psc is the output value of the control module, and Pc is the pressure detection value Pc in the pipeline.

3. A variable-frequency constant-pressure water supply control method according to claim 1, characterized in that The calculation formula for obtaining the water pressure deviation integral term Ysm according to the integral coefficient Ki is as follows: Ysm = Pe * Ki + Ysm' Where Ysm is the water pressure deviation integral term, Pe is the water pressure deviation value in the pipeline, Ki is the integral coefficient, and Ysm' is the water pressure deviation integral term at the previous moment.

4. A variable-frequency constant-pressure water supply control method according to claim 1, characterized in that, The calculation formula for obtaining the water pump speed command v by combining the water pressure deviation integral term Ysm and the proportional coefficient Kp is as follows: v = Pe * Kp + Ysm Where v is the water pump speed command, Pe is the water pressure deviation value in the pipeline, Kp is the controller proportional parameter, and Ysm is the water pressure deviation integral term.

5. A system based on the variable-frequency constant-pressure water supply control method according to any one of claims 1 to 4, characterized in that, it includes: A controller and an actuator, the controller and the actuator are electrically connected, and the controller includes a set value change process control module, a pressure comparison unit and an automatic control unit; The set value change process control module is used to obtain the water pressure set value Ps in the pipeline, and obtain the control output value Psc according to the water pressure set value Ps in the pipeline and transmit it to the pressure comparison unit; The pressure comparison unit is used to obtain the control output value Psc, and obtain the water pressure deviation value Pe in the pipeline according to the pipeline pressure detection value Pc and transmit it to the automatic control unit; The automatic control unit is used to obtain the water pressure deviation value Pe in the pipeline, and obtain the water pump speed command v according to the water pressure deviation value Pe in the pipeline and transmit it to the actuator; The actuator is used to obtain the water pump speed command v, and control the water pump speed according to the water pump speed command v to achieve constant pressure control of the water supply system.

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