A fuzzy PID based control device for dosing and phosphorus removal in a containerized sewage treatment system

Abstract

The present invention relates to a container-type sewage treatment system dosing and phosphorus removal control device based on fuzzy PID, belonging to the technical field of sewage treatment. The device includes a human-computer interaction unit, a fuzzy PID control unit, a PLC control circuit unit and a dosing unit; the human-computer interaction unit sets the average hourly flow rate and the total phosphorus concentration of the effluent of the container-type sewage treatment system through a parameter setting module; the fuzzy PID control unit iteratively calculates the PID parameters under the fuzzy control rules to obtain the controller correction parameters; the PLC control circuit unit writes the frequency output program of the frequency converter, and controls the frequency output of the frequency converter according to the parameters set by the PLC display screen and the PID parameters received from the fuzzy PID control unit; the dosing unit controls the metering pump through the frequency converter to extract a solution containing a certain concentration from the phosphorus removal agent barrel into the reaction tank. The problem of the total phosphorus concentration of the sewage treatment effluent not meeting the standard and the excessive addition of the phosphorus removal agent is solved, and the control accuracy of the dosing device is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a fuzzy PID-based containerized sewage treatment system dosing and phosphorus removal control device. Background Art

[0002] With the continuous development of the economy, the rapid advancement of industrialization and urbanization, the discharge of industrial wastewater and domestic sewage continues to rise, and the pollution pressure on water bodies is increasing. In the face of increasingly severe water pollution, sewage treatment is the most important solution.

[0003] Excessive phosphorus in sewage will induce eutrophication in the water, leading to the proliferation of aquatic organisms, especially algae, which will destroy the ecological balance of the water. At the same time, the algae toxins produced by algae will affect the water sources of drinking water and industrial and agricultural water. Therefore, in order to alleviate the eutrophication of water bodies, it is necessary to control the discharge of total phosphorus (TP) in the sewage during the sewage treatment process.

[0004] With the continuous improvement of urban sewage treatment discharge standards, the control value of total phosphorus in the effluent of sewage treatment plants is getting lower and lower. In order to ensure that the total phosphorus in the effluent of sewage treatment plants can meet the standards stably around the clock, a large amount of chemical phosphorus removal agents need to be added. In the actual project operation process, the method of artificial constant addition is usually adopted to cope with the ever-changing total phosphorus concentration of the influent, which often results in excessive addition of phosphorus removal agents, resulting in a significant increase in the direct costs of sewage treatment plant operators.

[0005] Although the traditional manual dosing method is easy to operate and has obvious effects, it also has some problems and challenges. The manual dosing method can only rely on the experience of the staff, and it is difficult to accurately control the dosage and time of the agent. The control accuracy is low, which may lead to unstable treatment effects. Manual dosing also requires operators to have a certain level of technical skills and experience to ensure correct and safe operation, and has high requirements for operators. The automatic dosing control strategy of constant proportion dosing according to the inlet flow rate may also cause waste of agents or substandard total phosphorus emissions in the effluent due to fluctuations in the inlet water quality.

[0006] Since the phosphide content in sewage is related to the season and weather, the phosphorus removal process has the characteristics of nonlinearity and hysteresis, and it is impossible to establish an accurate and appropriate mathematical model. Traditional controllers have limitations in sewage phosphorus removal. The total phosphorus value is detected by the end effluent, and the PLC controller and fuzzy control technology are combined to control the addition of chemical phosphorus removal agents. Fuzzy control technology is insensitive to parameter changes and relies on expert experience, which often leads to deviations in sewage treatment. The PID control method of dynamic dosing based on the total phosphorus concentration feedback at the end of the effluent is adopted. Although this method takes into account the dosing situation and combines it with the PID controller, the PID controller has a simple structure and is sensitive to parameter changes. For complex systems with nonlinear, time-varying, and hysteresis characteristics, it is often difficult to achieve satisfactory results.

[0007] Since the containerized sewage treatment system uses membrane bioreactor (MBR) membrane components, it is easy to form membrane pollution. The suspended pollutants in the mixed liquor, the soluble organic matter, the deposition of microorganisms on the membrane surface, and the folding and entanglement of fibers and debris in the activated sludge will reduce the permeability of the membrane to varying degrees. During the entire life cycle of the membrane, the delay time between the dosing point and the total phosphorus concentration detection point will increase as the membrane permeability decreases. In addition, for containerized sewage treatment systems of different sizes and average hourly flow rates, it is necessary to control the dosing pump to add different amounts of drugs. Summary of the invention

[0008] In order to solve the above problems existing in the prior art, the present invention provides a container-type sewage treatment system dosing and phosphorus removal control device based on fuzzy PID. The purpose of the present invention can be achieved through the following technical solutions:

[0009] A container-type sewage treatment system dosing and phosphorus removal control device based on fuzzy PID, comprising: a human-computer interaction unit, a fuzzy PID control unit, a PLC control circuit unit and a dosing unit;

[0010] The human-computer interaction unit includes a parameter setting module, a first communication module, and a program reset module;

[0011] The fuzzy PID control unit includes a fuzzy PID controller, a PID controller parameter adjustment module, and a second communication module;

[0012] The PLC control circuit unit includes a power module, a CPU module, an input module, an output module, and a third communication module;

[0013] The dosing unit includes a dephosphorization agent barrel, an online total phosphorus detector at the water outlet, and a metering pump;

[0014] The human-computer interaction unit sets the average hourly flow rate and the effluent total phosphorus concentration of the containerized sewage treatment system through the parameter setting module, transmits the average hourly flow rate to the fuzzy PID control unit and the PLC control circuit unit through the first communication module, and transmits the effluent total phosphorus concentration to the human-computer interaction interface display of the human-computer interaction unit through the first communication module;

[0015] The second communication module in the fuzzy PID control unit transmits the PID parameters of the fuzzy PID controller to the PLC control circuit unit;

[0016] The PLC control circuit unit receives the PID parameters of the fuzzy PID controller and the average time flow rate set by the parameter setting module through the third communication module, and sends the real-time detection result of the outlet total phosphorus concentration to the human-computer interaction unit and the fuzzy PID control unit through the PLC host computer software;

[0017] The dosing unit sends the real-time detection result of the total phosphorus concentration of the outlet water to the PLC control circuit unit through the total phosphorus online detector at the outlet end.

[0018] Specifically, the program resetting module is used to reset the program after the membrane bioreactor of the containerized sewage treatment system is cleaned, and the parameters are reset through the parameter setting module.

[0019] Specifically, the fuzzy PID controller compares the real-time total phosphorus concentration of the outlet water detected by the total phosphorus online detector at the outlet end with the preset expected value to obtain the deviation and the deviation rate, takes the deviation and the deviation rate as the input of the controller, takes the correction amount of the PID controller coefficient as the output of the controller, and iterates the PID controller coefficient through the fuzzy control rule to obtain the controller correction parameter.

[0020] Specifically, the PID controller parameter adjustment module obtains the PID controller parameters after adjusting the system delay time through the system transfer function.

[0021] Specifically, the system transfer function is a frequency simulation analysis of the frequency converter that controls the amount of phosphorus removal agent, and the calculation formula is:

[0022] ,

[0023] in, G ( s ) is the transfer function of the differential equation solved by the linear Lassen transformation method, K is the magnification factor of the inertial link, s is the Laplace transform variable, e is a natural constant, τis the delay time, T is the sampling time constant, θ is the delay order;

[0024] Specifically, the delay time is the delay time from the phosphorus removal dosing point to the water outlet during the replacement cycle of the membrane bioreactor of the containerized sewage treatment system, and the calculation formula is:

[0025] ,

[0026] in, V It is the volume of sewage flowing through the sewage treatment facility from the phosphorus removal dosing point to the outlet, in liters. J is the membrane flux, in liters / (square meters·hour), A is the effective area of ​​the membrane, in square meters.

[0027] Specifically, the power supply module is used to transform and rectify the external input current into a DC voltage signal below 24V, which is applied to the logic control and drive interface inside the PLC; the CPU module is used to perform data processing and control output; the input module is used to receive the real-time detection results of the total phosphorus online detector at the outlet and convert the real-time detection results into digital signals; after the output module transmits the controller correction parameters to the PLC control circuit unit, it controls the frequency of the output inverter according to the calculation results of the CPU module. The inverter is used to control the metering pump, and the phosphorus removal agent is controlled by controlling the frequency of the inverter; the third communication module receives the controller correction parameters calculated by the fuzzy PID control unit, and the average hourly flow rate of the sewage treatment system set by the human-computer interaction unit, and sends the real-time detection results of the total phosphorus concentration of the outlet water to the human-computer interaction unit and the fuzzy PID control unit through the PLC host computer software.

[0028] Specifically, the phosphorus removal agent barrel is a container for storing and using chemical agents to remove phosphorus from wastewater, and the chemical agents include aluminum salts, iron salts, calcium salts and phosphorus removal agents; the total phosphorus online detector at the outlet end is a device for monitoring the total phosphorus content during sewage treatment; the metering pump is driven by a frequency converter to extract the agent solution from the phosphorus removal agent barrel and put it into the reaction tank.

[0029] The beneficial effects of the present invention are:

[0030] By automatically adjusting the PID control parameters according to the actual working conditions, the total phosphorus concentration of the sewage treatment effluent is effectively avoided to be substandard and the phenomenon of excessive addition of phosphorus removal agent is avoided, and the control accuracy of the dosing device is improved. The constructed fuzzy PID controller module has good response speed, accuracy and stability. Different effluent total phosphorus control values ​​can be set according to different sewage treatment discharge standards. Fuzzy PID control can adapt to various complex nonlinear systems, and is well adapted to the nonlinear and variable characteristics of the sewage treatment process, making the addition of phosphorus removal agents simple to control. For the problems of membrane permeability changing over time and different sizes in containerized sewage treatment systems, the dosage can be accurately controlled by adjusting the PID control parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0032] Figure 1 It is a structural block diagram of the container-type sewage treatment system dosing and phosphorus removal control device based on fuzzy PID in the present invention;

[0033] Figure 2 It is the overall application flow chart of the device;

[0034] Figure 3 It is a schematic diagram of a fuzzy PID control unit;

[0035] Figure 4 It is the membrane flux variation curve;

[0036] Figure 5 It is the fuzzy PID control model diagram;

[0037] Figure 6 It is the fuzzy control rule table. DETAILED DESCRIPTION

[0038] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0039] See also Figure 1 , a container-type sewage treatment system dosing and phosphorus removal control device based on fuzzy PID, comprising: a human-computer interaction unit, a fuzzy PID control unit, a PLC control circuit unit and a dosing unit;

[0040] The human-computer interaction unit includes a parameter setting module, a first communication module, and a program reset module;

[0041] The fuzzy PID control unit includes a fuzzy PID controller, a PID controller parameter adjustment module, and a second communication module;

[0042] The PLC control circuit unit includes a power module, a CPU module, an input module, an output module, and a third communication module;

[0043] The dosing unit includes a dephosphorization agent barrel, an online total phosphorus detector at the water outlet, and a metering pump;

[0044] The human-computer interaction unit sets the average hourly flow rate and the effluent total phosphorus concentration of the containerized sewage treatment system through the parameter setting module, transmits the average hourly flow rate to the fuzzy PID control unit and the PLC control circuit unit through the first communication module, and transmits the effluent total phosphorus concentration to the human-computer interaction interface display of the human-computer interaction unit through the first communication module;

[0045] The second communication module in the fuzzy PID control unit transmits the PID parameters of the fuzzy PID controller to the PLC control circuit unit;

[0046] The PLC control circuit unit receives the PID parameters of the fuzzy PID controller and the average time flow rate set by the parameter setting module through the third communication module, and sends the real-time detection result of the outlet total phosphorus concentration to the human-computer interaction unit and the fuzzy PID control unit through the PLC host computer software;

[0047] The dosing unit sends the real-time detection result of the total phosphorus concentration of the outlet water to the PLC control circuit unit through the total phosphorus online detector at the outlet end.

[0048] In this embodiment, the application process of the device is as follows Figure 2 As shown:

[0049] Step 1: Use the PLC display screen as the human-machine interface of the human-machine interaction unit to set parameters, mainly to set the average hourly flow rate of the containerized sewage treatment system and the required total phosphorus concentration of the effluent. The required phosphorus removal agent dosage per hour of the sewage treatment system is proportional to the average hourly flow rate. When the sewage treatment system needs to clean or replace the MBR membrane, the program reset module of the human-machine interaction unit is operated through the PLC display screen to restore the sewage treatment system to the initial state and reset the parameters.

[0050] Step 2: The total phosphorus online detector at the water outlet monitors the total phosphorus content at the water outlet and sends the detection result to the PLC control circuit unit, and then sends it to the human-computer interaction unit and the fuzzy PID control unit through the PLC host computer software, and the controller correction parameters are obtained through the fuzzy PID control unit.

[0051] Step 3: Use PLC to write the inverter frequency output program, and control the inverter frequency according to the parameters set on the PLC display and the controller correction parameters received from the fuzzy PID control unit.

[0052] Step 4: The metering pump of the dosing unit is controlled by the frequency converter to extract a solution of a certain concentration from the dephosphorization agent barrel into the reaction tank. After the sewage and solution in the reaction tank react, the phosphate in the water is precipitated into solid particles, which is convenient for subsequent removal or treatment.

[0053] In this embodiment, the containerized sewage treatment system dosing and phosphorus removal control device based on fuzzy PID is mainly composed of a PLC display screen, a PLC control circuit unit, a fuzzy PID controller, a frequency converter, a metering pump, a reagent barrel, and an online detector for total phosphorus at the outlet end. Before the sewage treatment system is started, the PLC display screen is used as a human-computer interaction interface to set the parameters of the average water flow rate of the containerized sewage treatment system and the required total phosphorus concentration of the outlet water. Taking the containerized sewage treatment system with a sewage treatment scale of 50m3 / d as an example, the average hourly flow rate of the treated water volume is Q=2.1m3 / h when it runs 24 hours a day. The inlet of the containerized sewage treatment system is designed according to the water quality of general urban domestic sewage, and the effluent water quality is required to meet the Class A standard of the Pollutant Discharge Standard for Urban Sewage Treatment Plants (GB18918-2002), and the total phosphorus concentration of the effluent water quality is set to 0.5mg / L. When the MBR membrane needs to be cleaned or replaced, the parameters are reset after the sewage treatment system is restored to its initial state through the PLC display screen operation program reset. The effluent total phosphorus online detector detects the effluent total phosphorus concentration in real time, converts it into a voltage signal and connects it to the PLC control circuit unit. The PLC control circuit unit is connected to the PLC display screen, so that the effluent total phosphorus concentration is displayed on the PLC display screen. At the same time, the PLC host computer software transmits the effluent total phosphorus concentration to the MATLAB fuzzy PID control unit through network communication. Based on field experience and system parameter identification through the MATLAB system toolbox, the transfer function between the frequency of the PLC control output inverter and the amount of phosphorus removal agent is obtained. During the entire service life of the MBR membrane (90 days), data is collected every day, and the three straight line segments of the membrane flux are calibrated and fitted, such as Figure 4As shown, the delay time from the phosphorus removal dosing point to the water outlet is calculated. When the system transfer function delay time changes, the fuzzy PID control unit obtains new PID controller parameters that meet the control requirements through the PID controller parameter adjustment module. The fuzzy controller takes the deviation between the real-time effluent total phosphorus concentration and the expected value, as well as the deviation change rate as input, and iterates the PID controller parameters according to the fuzzy control rules, so that the PID controller parameters are adjusted as the controlled quantity changes to achieve the desired control effect. MATLAB communicates with PLC through OPC, and transmits the fuzzy PID control unit parameters to the PLC control circuit unit. The fuzzy PID control unit model is shown in Figure 5 As shown, step is the step signal source, sub1 is the subtraction module, Derivative is the differential link, ke1 and kec1 are the gain links of the amplification factor, Scope is the oscilloscope output, Saturation Dynamic is the dynamic saturation output, Mux is to convert a single output into a composite output, DeMux is to convert a composite output into multiple single outputs, Fuzzy Logic Controller is the fuzzy logic controller, Gain is the proportional operation, add1 and add2 are the accumulation operations, Integrator is the integration link, Fcn is the transfer function, dynamic Delay is the matlab function, and Product is the multiplication operation. The staff used PLC to write the frequency output program of the industrial inverter in advance, and controlled the frequency of the PLC circuit inverter according to the parameters set on the PLC display and the PID parameters received from the fuzzy PID control unit, and controlled the metering pump to extract the prepared solution from the dephosphorization agent barrel into the reaction tank. The sewage in the reaction tank reacts with the solution to make the total phosphorus concentration of the effluent meet the standard.

[0054] Specifically, the program resetting module is used to reset the program after the membrane bioreactor of the containerized sewage treatment system is cleaned, and the parameters are reset through the parameter setting module.

[0055] In this embodiment, the containerized sewage treatment system uses an MBR membrane assembly. In order to maintain the good performance of the membrane, the membrane needs to be cleaned. After the MBR membrane is cleaned, the program is reset to restore the system to its initial state, and then the parameters are reset; when the MBR membrane is not replaced or cleaned, the delay time between the dosing point and the total phosphorus concentration detection point increases as the membrane permeability decreases, and the system delay time changes with time. The PID controller parameters that meet the control requirements are obtained from the new system transfer function.

[0056] Specifically, the fuzzy PID controller compares the real-time total phosphorus concentration of the outlet water detected by the total phosphorus online detector at the outlet end with the preset expected value to obtain the deviation and the deviation rate, takes the deviation and the deviation rate as the input of the controller, takes the correction amount of the PID controller coefficient as the output of the controller, and iterates the PID controller coefficient through the fuzzy control rule to obtain the controller correction parameter.

[0057] In this embodiment, when the system transfer function is known, a new PID controller parameter that meets the control requirements is obtained through a PID controller parameter adjustment module. The structure of the fuzzy PID control unit can be found in Figure 3 , Figure 3 The correspondence between fuzzy controller and PID controller Figure 1 The fuzzy PID controller in the fuzzy PID control unit, Figure 3 The parameter adjustment module corresponds to Figure 1 The PID controller parameter adjustment module in the fuzzy PID control unit, Figure 3 PLC circuit in Figure 1 PLC control circuit unit, Figure 3 The metering pump, phosphorus removal agent barrel, and effluent total phosphorus online detector correspond to Figure 1 The dosing unit includes a metering pump, a phosphorus removal agent barrel, and an online detector for total phosphorus at the outlet; based on the actual data provided by the sewage treatment plant and the experience analysis of the on-site staff, the fuzzy control of phosphorus removal agent placement has two input quantities, namely the total phosphorus real-time value deviation and the rate of change of the total phosphorus real-time value deviation; the three output quantities are the correction values ​​of the PID controller parameters Kp, Ki, and Kd, Kp is the error, Ki is the integral, which is the accumulation of the error, and Kd is the differential, which is the difference between the current error and the previous error. The total phosphorus value input deviation and the rate of change of the total phosphorus value input deviation are described by the fuzzy subsets negative large (NB), negative medium (NM), negative small (NS), moderate (ZE), positive small (PS), positive medium (PM), and positive large (PB), and the corresponding discrete domain after quantization is {-3, -2, -1, 0, 1, 2, 3}. The membership function of each fuzzy subset selects a triangular function, and the fuzzy rules of the parameters are established based on the experience of sewage treatment work, as shown below. Figure 6 As shown in the figure, the membership function rules and parameter fuzzy control rules of each fuzzy subset are written using the FIS editor in MATLAB, where ΔKp, ΔKi, and ΔKd are the increments of error, integral, and differential, respectively. The PID controller parameters Kp, Ki, and Kd are used as the input of fuzzy control, the input is fuzzified, and ΔKp, ΔKi, and ΔKd are used as output. Figure 6The fuzzy control rule table is fuzzy deduced to calculate the output membership under different input conditions. The output quantities ΔKp, ΔKi, and ΔKd are clarified through the output membership. The calculated ΔKp, ΔKi, and ΔKd are summed with the previous Kp, Ki, and Kd coefficients and brought into the PID controller parameter adjustment module to achieve adaptive adjustment of the PID controller parameters under different errors or error changes.

[0058] Specifically, the PID controller parameter adjustment module obtains the PID controller parameters after adjusting the system delay time through the system transfer function.

[0059] Specifically, the system transfer function is a frequency simulation analysis of the frequency converter that controls the amount of phosphorus removal agent, and the calculation formula is:

[0060] ,

[0061] in, G ( s ) is the transfer function of the differential equation solved by the linear Lassen transformation method, K is the magnification factor of the inertial link, s is the Laplace transform variable, e is a natural constant, τ is the delay time, T is the sampling time constant, θ is the delay order;

[0062] Specifically, the delay time is the delay time from the phosphorus removal dosing point to the water outlet during the replacement cycle of the membrane bioreactor of the containerized sewage treatment system, and the calculation formula is:

[0063] ,

[0064] in, V It is the volume of sewage flowing through the sewage treatment facility from the phosphorus removal dosing point to the outlet, in liters. J is the membrane flux, in liters / (square meters·hour), A is the effective area of ​​the membrane, in square meters.

[0065] In this embodiment, the system transfer function is obtained by frequency simulation analysis of the frequency converter that controls the amount of dephosphorization agent, based on field experience and system parameter identification through the MATLAB system toolbox. The membrane flux is the amount of fluid passing through a unit membrane area per unit time. The size directly affects the flow rate of sewage through the membrane. It can be used to calculate the delay time between the dosing point and the effluent total phosphorus concentration detection point, usually expressed in liters per square meter per hour (L / (m²·h)). In MATLAB, the pidtune function in the Control System Toolbox is used to design a PID controller. When using the pidtune function, the delay link of the system is represented as a first-order inertia link to approximate it. The output of the MATLAB program will be used as the input of the Simulink model. When the MATLAB program outputs the PID controller parameters, the Simulink model will be able to read these data in real time and apply them to the control logic or simulation in the model, as a PID controller parameter adjustment module to adjust the PID controller parameters as the system delay time changes.

[0066] Specifically, the power supply module is used to transform and rectify the external input current into a DC voltage signal below 24V, which is applied to the logic control and drive interface inside the PLC; the CPU module is used to perform data processing and control output; the input module is used to receive the real-time detection results of the total phosphorus online detector at the outlet and convert the real-time detection results into digital signals; after the output module transmits the controller correction parameters to the PLC control circuit unit, it controls the frequency of the output inverter according to the calculation results of the CPU module. The inverter is used to control the metering pump, and the phosphorus removal agent is controlled by controlling the frequency of the inverter; the third communication module receives the controller correction parameters calculated by the fuzzy PID control unit, and the average hourly flow rate of the sewage treatment system set by the human-computer interaction unit, and sends the real-time detection results of the total phosphorus concentration of the outlet water to the human-computer interaction unit and the fuzzy PID control unit through the PLC host computer software.

[0067] In this embodiment, the power module is responsible for converting the external input AC 220V power supply or DC power supply into a DC voltage signal of 24V or less through the processes of transformation and rectification, which is applied to the logic control and drive interface inside the PLC to provide power for the normal operation of the PLC. The CPU module is responsible for executing user programs, performing data processing, and controlling output and other operations. For the S7-1200 series PLC, its CPU module integrates a microprocessor and a power supply function, and can provide outputs of multiple different voltage levels to meet the needs of different modules. The input module is used to receive the real-time detection results of the total phosphorus online detector at the water outlet and convert it into a digital signal so that the PLC can perform logical operations and control. After the output module transmits the PID parameters of the new fuzzy PID controller to the PLC control circuit unit, according to the results calculated by the CPU, the frequency of the output inverter is controlled, and the inverter controls the metering pump. By controlling the inverter frequency, the delivery control of the dephosphorization agent is realized, and the delivery amount of the dephosphorization agent is changed. The communication module realizes the communication between PLC and the human-computer interaction interface and the fuzzy PID control unit, receives the three parameters of the PID controller calculated by the fuzzy PID control unit and the average flow rate of the sewage treatment system set from the human-computer interaction interface, and sends the real-time detection results of the total phosphorus concentration of the effluent to the human-computer interaction interface display and the fuzzy PID control unit through the PLC host computer software.

[0068] Specifically, the phosphorus removal agent barrel is a container for storing and using chemical agents to remove phosphorus from wastewater, and the chemical agents include aluminum salts, iron salts, calcium salts and phosphorus removal agents; the total phosphorus online detector at the outlet end is a device for monitoring the total phosphorus content during sewage treatment; the metering pump is driven by a frequency converter to extract the agent solution from the phosphorus removal agent barrel and put it into the reaction tank.

[0069] The computer storage medium of the embodiment of the present invention may adopt any combination of one or more computer-readable media. The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples (non-exhaustive list) of computer-readable storage media include: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this document, a computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in combination with an instruction execution system, device or device.

[0070] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, which carry computer-readable program code. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. Computer-readable signal media may also be any computer-readable medium other than a computer-readable storage medium, which may send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, apparatus, or device.

[0071] The program code included on the computer readable medium can be transmitted with any appropriate medium, including but not limited to wireless, electric wire, optical cable, RF, etc., or any suitable combination of the above. The computer program code for performing the operation of the present invention can be written in one or more programming languages ​​or their combinations, and the programming language includes object-oriented programming languages-such as Java, Smalltalk, C++, and also includes conventional procedural programming languages-such as "C" language or similar programming languages. The program code can be executed completely on the user's computer, partially on the user's computer, as an independent software package, partially on the user's computer and partially on the remote computer, or completely on the remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (for example, using an Internet service provider to connect through the Internet).

[0072] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A containerized sewage treatment system dosing and phosphorus removal control device based on fuzzy PID, characterized in that: include: Human-machine interaction unit, fuzzy PID control unit, PLC control circuit unit and dosing unit; The human-computer interaction unit includes a parameter setting module, a first communication module, and a program reset module; The fuzzy PID control unit includes a fuzzy PID controller, a PID controller parameter adjustment module, and a second communication module; The PLC control circuit unit includes a power module, a CPU module, an input module, an output module, and a third communication module; The dosing unit includes a dephosphorization agent barrel, an online total phosphorus detector at the water outlet, and a metering pump; The human-computer interaction unit sets the average hourly flow rate and the required effluent total phosphorus concentration of the containerized sewage treatment system through the parameter setting module, transmits the average hourly flow rate to the fuzzy PID control unit and the PLC control circuit unit through the first communication module, and transmits the required effluent total phosphorus concentration to the human-computer interaction interface display of the human-computer interaction unit through the first communication module; The second communication module in the fuzzy PID control unit transmits the PID parameters of the fuzzy PID controller to the PLC control circuit unit; The fuzzy PID controller compares the real-time total phosphorus concentration of the outlet water detected by the total phosphorus online detector at the outlet end with the preset expected value to obtain a deviation and a deviation rate, uses the deviation and the deviation rate as the input of the controller, uses the correction amount of the PID controller coefficient as the output of the controller, and iterates the PID controller coefficient through the fuzzy control rule to obtain the controller correction parameter; The PLC control circuit unit receives the PID parameters of the fuzzy PID controller and the average time flow rate set by the parameter setting module through the third communication module, and sends the real-time detection result of the outlet total phosphorus concentration to the human-computer interaction unit and the fuzzy PID control unit through the PLC host computer software; The dosing unit sends the real-time detection result of the total phosphorus concentration of the outlet water to the PLC control circuit unit through the total phosphorus online detector at the outlet end; The PID controller parameter adjustment module obtains the PID controller parameters after adjusting the system delay time through the system transfer function. The system transfer function is a frequency simulation analysis of the frequency converter that controls the amount of phosphorus removal agent, and the calculation formula is: ， Where G(s) is the transfer function of the differential equation solved by the linear Laplace transformation method, K is the amplification factor of the inertial link, s is the Laplace transformation variable, e is a natural constant, τ is the delay time, T is the sampling time constant, and θ is the delay order; The containerized sewage treatment system uses MBR membrane modules. The delay time is the delay time from the phosphorus removal dosing point to the water outlet during the replacement cycle of the membrane bioreactor of the containerized sewage treatment system. The calculation formula is: ， Among them, V is the volume of sewage flowing through the sewage treatment facility from the phosphorus removal dosing point to the outlet, in liters, J is the membrane flux, in liters / (square meters·hour), and A is the effective area of ​​the membrane, in square meters.

2. The device according to claim 1, characterized in that The program reset module is used to reset the program after the membrane bioreactor of the containerized sewage treatment system is cleaned, and the parameters are reset through the parameter setting module.

3. The device according to claim 1, characterized in that The power supply module is used to transform and rectify the external input current into a DC voltage signal below 24V, which is applied to the logic control and drive interface inside the PLC; the CPU module is used to perform data processing and control output; the input module is used to receive the real-time detection results of the total phosphorus online detector at the outlet end and convert the real-time detection results into digital signals; after the output module transmits the controller correction parameters to the PLC control circuit, it controls the frequency of the output inverter according to the calculation results of the CPU module. The inverter is used to control the metering pump, and the phosphorus removal agent is controlled by controlling the frequency of the inverter; the third communication module receives the controller correction parameters calculated by the fuzzy PID control unit, and the average hourly flow rate of the sewage treatment system set by the human-computer interaction unit, and sends the real-time detection results of the total phosphorus concentration of the outlet water to the human-computer interaction unit and the fuzzy PID control unit through the PLC host computer software.

4. The device according to claim 1, characterized in that The dephosphorization agent barrel is a container for storing and using chemical agents to remove phosphorus from wastewater, and the chemical agents include aluminum salts, iron salts, calcium salts and dephosphorization agents; the outlet end total phosphorus online detector is a device for monitoring the total phosphorus content in the sewage treatment process; The metering pump is driven by a frequency converter to extract the agent solution from the dephosphorization agent barrel and put it into the reaction tank.

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