Automatic dosing control system and method for reverse osmosis system based on PLC (Programmable Logic Controller)

Abstract

The invention discloses a PLC-based reverse osmosis system automatic dosing control system and method, and relates to the technical field of converter valve water-cooling systems, the system adopts a modular structure, integrates an automatic dosing module, a control protection module and a standby control module, and combines a timing protection logic algorithm to monitor the dosing and dosing process in real time, so that the system is simple and convenient to operate. According to the technical effects, modular design optimizes space utilization and improves durability, gravitational potential energy driving reduces mechanical fault risks, control logic is simplified, system stability is enhanced, remote monitoring achieves parameter adjustment and data tracing through a Modbus protocol, the automation level and operation safety are remarkably improved, and the reliability of the system is improved. According to the invention, automatic dosing control with high reliability, high efficiency and low maintenance cost is realized through innovative design, and a solution is provided for water quality maintenance of extra-high pressure equipment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of converter valve water cooling systems, and more particularly to an automatic dosing control system and method for a reverse osmosis system based on PLC. BACKGROUND

[0002] The existing converter valve water cooling system of an ultra-high voltage converter station needs to be regularly dosed with scale inhibitors and bactericides to maintain water quality stability, prevent equipment from scaling or microbial growth, and ensure efficient operation of the converter valve.

[0003] However, the traditional manual dosing method has significant drawbacks: first, it is inefficient, relying on manual operation to cause long dosing cycles and slow response, making it difficult to meet the needs of continuous operation of the ultra-high voltage system; second, it is not safe, as the operator directly contacts corrosive chemicals, which can easily cause health risks, and human error can cause inaccurate or interrupted dosing; third, it lacks reliability, as the manual process lacks automatic monitoring and protection mechanisms and is easily disturbed by human factors, leading to water quality fluctuations or equipment damage.

[0004] Therefore, an automatic dosing control system and method for a reverse osmosis system based on PLC are proposed to address the above problems. SUMMARY

[0005] To overcome the above-mentioned defects of the prior art, the present application provides an automatic dosing control system and method for a reverse osmosis system based on PLC to solve the problems raised in the background art.

[0006] To achieve the above-mentioned purposes, the present application provides the following technical solutions: an automatic dosing control system for a reverse osmosis system based on PLC, comprising: An automatic dosing module: including a medicine bottle unit, a medicine storage unit, and a water distribution unit, the medicine bottle unit drives the flow of the medicine and water in a fixed volume manner, the medicine bottle unit is connected to the medicine storage unit and the water distribution unit through a pipeline, and the medicine bottle unit, the medicine storage unit, and the water distribution unit are all provided with liquid level switches; A control protection module: including a main control unit, a signal acquisition unit, and an execution unit, the main control unit is configured to perform logical operations and issue instructions, the signal acquisition unit is connected to the liquid level switches to obtain the liquid level state, and the execution unit is configured to control the electromagnetic valves of the automatic dosing module for medicine and water; A backup control module: connected to the main control unit and configured to automatically switch to the backup control module to control the automatic dosing module when the main control unit fails; Wherein, the automatic dosing module drives the flow of the medicine and water through gravitational potential energy, and the control protection module and the backup control module are both connected to a background monitoring unit through Modbus protocol communication.

[0007] Preferably, the automatic dosing module further comprises a dosing barrel unit connected with the medicine bottle unit through pipelines, and the dosing barrel unit is provided with high and low liquid level switches for triggering dosing operation and monitoring liquid level.

[0008] Preferably, the control protection module further comprises a timing protection logic algorithm configured to monitor time of the dispensing process or the dosing process, and trigger a protection action and shut down the execution unit when actual time of the dispensing process or the dosing process exceeds a sum of a preset time and an allowable deviation.

[0009] Preferably, a ratio of the water dispensing unit to the medicine bottle unit is 100:2, and the dispensing process is quantitatively controlled by the liquid level switch, which is a high-precision float switch with an average failure-free operation time of no less than 100,000 hours.

[0010] Preferably, the background monitoring unit realizes remote monitoring and parameter adjustment of the automatic dosing module and the control protection module through a human-computer interaction interface, and supports query and export of historical data.

[0011] Preferably, the automatic dosing module adopts a modular structure, and the medicine bottle unit, the medicine storage unit, the water dispensing unit and the pipelines are integrated in a compact frame, and the medicine bottle unit, the medicine storage unit and the water dispensing unit are made of corrosion-resistant materials including polytetrafluoroethylene or stainless steel 316L.

[0012] An automatic dosing control method for a reverse osmosis system based on PLC, comprising the following steps: S1, dispensing process control: the medicine and water are injected into the fixed-volume medicine bottle unit from the medicine storage unit and the water dispensing unit driven by gravitational potential energy; the main control unit controls opening and closing of the execution unit according to the liquid level switch signal in the medicine bottle unit to realize quantitative dispensing of the medicine and water; S2, dosing process control: when the low liquid level switch of the dosing barrel unit detects that the liquid level is lower than a set value, the main control unit is triggered to control the dosing valve and the water replenishing valve to open, and the medicine liquid is added to the dosing barrel unit until the high liquid level switch acts; S3, abnormal protection: the timing protection logic algorithm is set in the main control unit, and if actual operation time of dispensing or dosing exceeds a sum of a preset time and an allowable deviation value, it is determined as abnormal and a protection action is triggered to shut down the relevant execution unit; S4, state monitoring and communication: the main control unit transmits liquid level state, valve action record and alarm information to the background monitoring unit in real time through Modbus protocol.

[0013] Preferably, in step S4, remote interaction and parameter management are further included, which allows the operator to remotely monitor the system running state, query historical data and export running logs through the man-machine interface of the background monitoring unit, and remotely adjust the dosing ratio or manually start and stop the process.

[0014] Preferably, in step S3, the abnormality determination logic of the timing protection logic algorithm is: triggered when is met, wherein is the actual process time, is the preset standard time, is the allowed time deviation.

[0015] Preferably, in step S4, redundancy control switching is further included, which automatically switches to the standby control module to take over control when the main control unit fails, and the standby control module uses dual power supply to avoid sudden power failure.

[0016] Technical effects and advantages of the present application: Compared with the prior art, the automatic dosing control system and method for reverse osmosis system based on PLC integrates the dosing bottle, the medicine storage barrel, the dosing barrel and the pipeline in a compact frame through modular design, which not only reduces the floor area, but also improves the durability through corrosion-resistant materials; at the same time, the gravity potential energy drive replaces the traditional medicine pump, avoiding mechanical wear and failure, and reducing the system complexity.

[0017] Compared with the prior art, the automatic dosing control system and method for reverse osmosis system based on PLC improves the stability and response speed of the control system through simplifying signal acquisition and redundant architecture, reducing the risk of downtime caused by external interference or single point failure.

[0018] Compared with the prior art, the intelligent monitoring system of the automatic dosing control system and method for reverse osmosis system based on PLC realizes remote data transmission through Modbus protocol, supports remote parameter adjustment and historical record query through human-machine interface, reduces the frequency of manual on-site operation; at the same time, through the integration of remote monitoring and automatic protection, the operation and maintenance convenience is improved, and the safety risk is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0019] Fig. 1 is the system architecture diagram of the present application.

[0020] Fig. 2 is the method flowchart of the present application. DETAILED DESCRIPTION

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0022] As attached Figs. 1-2 The PLC-based automatic dosing control system for a reverse osmosis system shown includes: Automatic dosing module: includes a medicine bottle unit, a medicine storage unit, and a water distribution unit. The medicine bottle unit drives the flow of medicine and water in a fixed volume manner. The medicine bottle unit is connected to the medicine storage unit and the water distribution unit through pipelines. The medicine bottle unit, medicine storage unit, and water distribution unit are all equipped with liquid level switches. Control and protection module: includes main control unit, signal acquisition unit and execution unit. The main control unit is configured to perform logic operations and issue instructions. The signal acquisition unit is connected to the liquid level switch to obtain the liquid level status. The execution unit is configured to control the solenoid valves for the automatic dosing module to enter and exit the reagent and water. Backup control module: Connected to the main control unit, configured to automatically switch to backup control module to control the automatic dosing module when the main control unit fails; The automatic dosing module uses gravitational potential energy to drive the flow of chemicals and water, while the control and protection module and the backup control module are both connected to the background monitoring unit via Modbus protocol.

[0023] Specifically, the automatic dosing device is implemented based on the principle of gravity potential energy and a modular control architecture. The dosing unit of the automatic dosing module adopts a fixed-volume design, connected to the storage unit and water distribution unit via corrosion-resistant pipelines, forming a closed system that relies on gravity to transport the chemicals. Each dosing unit has a chemical inlet valve and a water inlet valve at the top, and a dosing valve at the bottom. Each unit is equipped with a high-precision float-type level switch to detect full and empty levels. The main control unit of the control and protection module uses PLC programming to implement logic operations. When the storage unit's level switch detects the need for replenishment, the PLC sends a command to open the chemical inlet valve, allowing the chemicals to flow into the dosing unit by gravity until a high-level switch signal is triggered, at which point the valve closes. The water distribution unit simultaneously adds water at a 100:2 ratio, achieving precise proportioning through a combination of level switches. The execution unit uses a 24V DC solenoid valve as the actuating element, whose opening and closing states are directly driven by the PLC output module. The backup control module adopts a hot backup redundancy design. When the main control unit fails, it automatically switches to the backup PLC through a hardware watchdog circuit. The dual power supply system achieves uninterrupted power supply through diode isolation. The intelligent monitoring system carries Modbus-RTU protocol through RS485 interface, transmits liquid level state, valve action time sequence and fault code to background monitoring unit in real time, and the background man-machine interface is developed by configuration software, so that the dispensing parameters can be remotely modified or the process can be manually intervened. The entire device integrates each unit through a rigid frame, and the pipeline is connected by stainless steel 316L clamping sleeve to ensure stable transportation by relying on the self-weight of the fluid under the condition of no pump. The timing protection logic is embedded in the PLC program, and the duration of the liquid level switch state is scanned to determine the process abnormality. If the actual operation time exceeds the preset threshold, all electromagnetic valves are immediately closed and an alarm signal is triggered. This implementation simplifies the system structure through physical potential energy conversion and on-off control, and uses a redundant communication architecture to ensure the continuity of the control link.

[0024] As a preferred embodiment, the dosing barrel unit, as a key component of the automatic dosing module, is tightly connected with the medicine bottle unit through corrosion-resistant pipelines to form a closed fluid system based on gravitational potential energy. The design principle is to use the binary signal of the liquid level switch to automatically trigger and accurately monitor the dosing process, thereby avoiding manual intervention and improving system reliability. The dosing barrel unit adopts a cylindrical structure with a volume of 200 liters and is made of stainless steel 316L to resist corrosion of the medicament. The top is provided with a liquid inlet connected to the liquid outlet valve of the medicine bottle unit through a polytetrafluoroethylene hose, and the bottom is provided with a liquid outlet connected to the water cooling system loop of the converter valve. Both the high-level switch and the low-level switch are high-precision float-type sensors fixed at predetermined height positions on the side wall of the dosing barrel. The low-level switch is arranged at the lower part of the barrel corresponding to the lower limit of the liquid level, and the high-level switch is arranged at the upper part corresponding to the upper limit of the liquid level. Both are connected to the switch input module of the PLC through a cable. When the liquid level in the dosing barrel drops to the low-level switch setting value due to consumption of the water cooling system, the float triggers a change in the switch state. The PLC detects this signal and immediately starts the dosing sequence: first, control the dosing electromagnetic valve of the medicine bottle unit to open, rely on gravity to inject the pre-dosed liquid into the dosing barrel, and at the same time, open the water valve to introduce clean water to maintain the concentration balance. When the liquid level rises to the high-level switch setting position, the float action signal is transmitted to the PLC, and the valve is closed to stop dosing. The entire process is controlled in a closed loop through the logic program of the PLC, and the liquid level state is fed back to the background monitoring unit in real time to ensure continuous dosing operation without the risk of overflow. Furthermore, the dosing barrel unit, the medicine bottle unit and the medicine storage unit are integrated in a modular frame, which is compact in structure and has optimized pipeline layout to reduce flow resistance and improve dosing efficiency.

[0025] As a preferred embodiment, the formula of the timing protection logic algorithm is as follows: ; Among them, for actual dispensing or dosing time, for preset standard time, for allowable time deviation, usually 2 seconds. When , the system determines that it is abnormal and triggers the protection action; Timing protection logic algorithm as the core safety mechanism of control protection module, its design principle is based on the time monitoring of dispensing and dosing process, through the preset standard time and allowable deviation value to form a dynamic time window, when the actual operation time exceeds the window, it is immediately determined as an abnormal state and triggers the protection action. The algorithm is realized in PLC program through timer function module, and independent time monitoring channels are set for dispensing process and dosing process respectively. The starting point of dispensing process timing is the time when PLC receives the start dispensing instruction, at this time the medicine inlet valve and water inlet valve of water dispensing unit are opened, and the corresponding timer is started in the program; The ending point of timing is the time when the high liquid level switch of dispensing bottle triggers the signal. The starting point of dosing process timing is the time when the low liquid level switch of dosing barrel triggers the signal, at this time the dosing valve and water valve of medicine bottle unit are opened, and the dosing timer is started; the ending point of timing is the time when the high liquid level switch of dosing barrel triggers the signal. The preset standard time According to the calculation of fluid dynamics, the theoretical time required for the flow of medicament through the pipeline and the valve action delay time are included, and the allowable deviation is set as a fixed value considering the influence factors such as pipeline residue and liquid level switch response fluctuation. When the actual process time continues to exceed and , PLC immediately executes the protection logic: first, close all the electromagnetic valves that are in action, cut off the fluid passage; second, transmit the fault code to the background monitoring unit through Modbus protocol, trigger the sound and light alarm; at the same time, the system automatically enters standby state and waits for manual intervention.

[0026] As a preferred embodiment, the dispensing ratio of water unit and medicine bottle unit is set to 100:2. The design principle is based on the volumetric quantitative control method driven by gravitational potential energy, which realizes the accurate mixing of medicament and water through the cooperation of fixed geometric size container and high precision liquid level switch, avoiding the error caused by relying on external pumping equipment. The dispensing bottle adopts fixed volume design, and its internal capacity is pre-calculated as 400 milliliters corresponding to the medicament injection amount; the water dispensing unit has a volume of 20 liters, which ensures that the mass ratio of water to medicament is strictly maintained at 100:2 through proportional conversion. In the implementation process, the dispensing start is triggered by PLC control logic: when the system detects that the medicine needs to be dispensed, first open the medicine inlet electromagnetic valve connected between the medicine storage unit and the dispensing bottle, the medicament is injected into the dispensing bottle by gravity, until the liquid level in the bottle rises and triggers the high liquid level float switch action, the switch signal is transmitted to PLC to immediately close the medicine inlet valve, and the quantitative injection of medicament is completed; Subsequently, the water inlet valve of the water distribution unit is opened synchronously, and clean water flows into the dispensing bottle along the pipeline. The injection process is monitored by a low liquid level float switch. When the liquid level reaches the set height, the switch signal triggers the valve to close, achieving water quantity control. The liquid level switch uses a high-precision float structure. The float assembly is made of corrosion-resistant polytetrafluoroethylene. Inside, it integrates a magnetic trigger mechanism and a dry reed tube. When the liquid level changes, the displacement of the float drives the change of the magnetic field, causing the dry reed tube to close or open, outputting a stable on-off signal. This design avoids electronic drift through mechanical contact, and the low-friction seal between the float and the valve body ensures response sensitivity and long-term stability, with an average trouble-free operation time of not less than 100,000 hours guaranteed by material selection and structure optimization.

[0027] As a preferred embodiment, the implementation of the background monitoring unit is based on a distributed monitoring architecture and modular human-computer interaction principles. It realizes bidirectional data transmission between the control and protection module and the remote operation interface through the Modbus protocol, forming a full-process visual control of the automatic dosing system. The background monitoring unit uses an industrial computer as the hardware platform. The built-in monitoring software establishes a Modbus-RTU communication link with the PLC master unit through the RS485 interface. The communication frame format includes device address, function code, data field, and check code, ensuring that data such as liquid level switch status, electromagnetic valve action record, and alarm information are uploaded in real time; The human-computer interaction interface uses a 15-inch touch screen as the display terminal. The interface layout is divided into three functional modules: parameter setting area, state display area, and historical data area. The parameter setting area provides online modification functions for parameters such as dosing ratio and timing protection threshold. After logging in with encrypted permissions, the operator can directly input values and issue them to the PLC. The state display area dynamically refreshes the liquid level height, valve opening and closing state, and system operation mode of each unit, using color coding to distinguish between normal and abnormal states. The historical data area stores operation logs in the form of a time axis, supports filtering and querying of dosing frequency, dosing duration, and other key indicators by date, and realizes data export function through built-in memory; The monitoring software uses a multi-thread architecture. The communication thread is responsible for data collection and protocol analysis, the interface thread handles user interaction, and the exception detection thread compares operation time with the preset threshold in real time. When the protection logic is triggered, an alarm dialog box pops up immediately and records the event sequence.

[0028] As a preferred embodiment, the modular structure design principle of the automatic dosing module is based on space optimization and function integration. By compactly integrating the medicine bottle unit, medicine storage unit, water distribution unit, and pipeline system into a unified framework, the number of external connection points is reduced, improving the overall integrity and reliability of the system. The frame is welded from standardized steel structures, the size of which is customized according to the space limitation of the converter station, and the internal space is divided into layers to realize unit modular assembly: the medicine bottle unit is fixed to the upper part of the frame, taking advantage of the gravitational potential energy; the medicine storage unit and the water distribution unit are placed side by side in the middle part and connected with the medicine bottle unit through short-distance pipelines; all pipelines are connected through a sleeve joint to realize quick disassembly and assembly, avoiding the risk of leakage caused by threaded connection. The medicine bottle unit, the medicine storage unit and the water distribution unit are all made of corrosion-resistant materials, among which polytetrafluoroethylene is applied to the inner wall of the medicine bottle unit and the valve sealing element to resist chemical corrosion by taking advantage of its chemical inertness; stainless steel 316L is used for the shell of the medicine storage unit and the water distribution unit and the pipeline system to delay oxidation by forming a passivation film through high chromium nickel composition. The material processing technology includes injection molding of polytetrafluoroethylene components and laser welding of stainless steel structures to ensure seamless integration between units. The internal wiring of the frame adopts shielded cable centralized management, and the liquid level switch and the solenoid valve signal line are connected to the PLC control cabinet through the terminal block to reduce external interference; such modular design not only simplifies the installation and maintenance process, but also prolongs the service life of the equipment through material corrosion resistance.

[0029] A PLC-based automatic dosing control method for a reverse osmosis system, comprising the following steps: S1, process control: the medicine and water are injected into the fixed-volume medicine bottle unit from the medicine storage unit and the water distribution unit by gravitational potential energy; the main control unit controls the opening and closing of the execution unit according to the liquid level switch signal in the medicine bottle unit to realize the quantitative proportioning of the medicine and water; S2, process control: when the low liquid level switch of the dosing barrel unit detects that the liquid level is lower than the set value, the main control unit is triggered to control the dosing valve and the water supplement valve to open, and the liquid medicine is added to the dosing barrel unit until the high liquid level switch acts; S3, abnormal protection: a timing protection logic algorithm is set in the main control unit, if the actual operation time of dosing or dosing exceeds the sum of the preset time and the allowable deviation value, it is determined to be abnormal and the protection action is triggered to close the related execution unit; S4, state monitoring and communication: the main control unit transmits the liquid level state, valve action record and alarm information to the background monitoring unit in real time through the Modbus protocol.

[0030] Specifically, the process control starts when the PLC detects the low liquid level signal, the main control unit opens the medicine outlet valve of the medicine storage unit and the water inlet valve of the water distribution unit in turn, and the medicine and water flow into the fixed-volume dosing bottle by gravity, and the quantitative accuracy is realized through high-precision float switches: When the liquid medicine reaches the high liquid level switch of the dosing bottle, the magnetic float triggers the reed switch signal, and the PLC immediately closes the corresponding valve; The dosing process control is activated by the low liquid level switch of the dosing barrel, and the PLC synchronously opens the dosing bottle outlet valve and the water supplement valve. The mixed liquid is injected into the dosing barrel through the optimized flow resistance pipeline until the high liquid level switch stops the process. The abnormal protection link embeds a timing protection algorithm. The PLC internal timer starts timing from the valve opening signal. If the actual duration exceeds the sum of the preset standard time and the allowed deviation value, all electromagnetic valve power is immediately cut off and an alarm code is triggered. The state monitoring and communication are realized through the Modbus protocol. The RS485 interface of the PLC interacts with the background monitoring unit in master-slave mode, and real-time transmission of liquid level switch state, valve action time sequence and fault code is realized. The background system parses the data packet and refreshes the human-machine interface display.

[0031] As a preferred embodiment, the remote interaction and parameter management function is based on a distributed monitoring architecture and a modular human-machine interaction principle. It realizes the bidirectional transmission of data between the control protection module and the remote operation interface through the Modbus protocol, forming a configurable management of the whole process of the automatic dosing system. The background monitoring unit uses an industrial computer as the hardware platform. The built-in monitoring software establishes a Modbus-RTU master-slave communication link with the PLC master unit through the RS485 interface. The communication frame format is strictly framed according to the structure of device address code, function code, data field and CRC check code, ensuring that the liquid level switch state, electromagnetic valve action time sequence and alarm code data are uploaded to the monitoring system in real time. The human-machine interface uses a 15-inch resistive touch screen as the display and operation terminal. The interface layout adopts a functional partition design. The parameter setting area provides online modification functions of core parameters such as dosing ratio and timing protection threshold. After the operator passes the three-level password permission authentication, he can directly input values on the touch screen digital keyboard. The modified values are transmitted to the PLC's holding register in real time through the Modbus write instruction. The state monitoring area dynamically refreshes the liquid level height, valve opening and closing state and system running mode of each unit. The color coding mechanism uses green to represent normal operation, yellow to represent warning state and red to represent fault state. The historical data area stores the running log in a ring buffer structure, supports time stamp filtering and querying of dosing frequency, dosing time and other key indicators, and exports data in CSV format through the USB interface. The remote control function is realized through virtual buttons. The operator can manually trigger the dosing process start or emergency stop command on the interface. These commands are forwarded to the PLC execution mechanism through Modbus communication. The monitoring software adopts a multi-thread architecture. The communication thread is responsible for data collection and protocol analysis. The interface thread handles user touch events. The data management thread realizes compressed storage and retrieval query of historical records. This layered design ensures that the system can still maintain real-time response in a resource-limited environment.

[0032] As a preferred embodiment, the abnormality determination of the timing protection logic algorithm is based on the time window comparison principle, which monitors the actual duration of the dispensing or dosing process in real time through the PLC built-in timer, and compares it with the preset standard time and the allowed deviation value to form a dynamic threshold for logical judgment. Its technical implementation relies on the cooperative work of the comparison function module and the timer module in the PLC program: when the dispensing process starts, the PLC immediately activates the corresponding timer to start accumulating time, while continuously scanning the liquid level switch state change; the preset standard time According to the fluid dynamics calculation, the theoretical flow time of the medicament flowing through the pipeline and the electromagnetic valve action delay time, the allowed deviation is set as a fixed value considering factors such as pipeline residue and liquid level switch mechanical response fluctuation; The abnormality determination logic is realized through the greater than comparison instruction in the PLC program, when the timer cumulative value continuously exceeds and , the comparison instruction outputs a high-level signal to trigger the protection action sequence. The protection action execution process includes immediately interrupting all electromagnetic valve drive signals related to the current process, cutting off the valve power supply circuit through the PLC output module; at the same time, the fault code is written into a specific register, and the abnormal state word is transmitted to the background monitoring unit in real time through the Modbus communication protocol.

[0033] As a preferred embodiment, the redundant control switching mechanism is based on the master-slave hot backup principle, which realizes disturbance-free switching through the combination of hardware diagnosis circuit and software state monitoring, and can automatically take over the system control right from the standby control module when the main control unit fails; The standby control module uses the same type of PLC hardware platform as the main control unit, and the two realize real-time mirroring of program memory and register data through the optical fiber synchronous interface, while configuring independent switching value input and output modules to form a complete control loop; The dual power supply system inputs through two independent AC220V power sources, converts DC24V working voltage after rectification and filtering, each power source is equipped with overvoltage protection and surge suppression circuit, and the two output ends are electrically isolated through diode isolation module, when the main power supply line is powered off, the standby power supply can realize seamless switching in milliseconds; the fault detection mechanism relies on the hardware watchdog circuit, the main control unit needs to send pulse signals to the watchdog circuit periodically, if the pulse is not received within the timeout, it is determined that the program is running or dead; Simultaneously, the main control unit's operating status is monitored via a heartbeat detection mechanism using Modbus communication messages. A communication failure is identified when no correct response is received for three consecutive communication cycles. The switching logic is executed by the FPGA programmable logic device. Upon receiving a fault signal, the main control unit immediately cuts off the control signal path to the actuator and simultaneously activates the output enable terminal of the backup control module. The switching process can be completed within 10 milliseconds. After taking over, the backup control module first restores the register data from the most recent image and continues executing the control program flow. During this process, the current state of the solenoid valve is maintained to prevent system disturbances.

[0034] The working process of this invention is as follows: The medicine and water are injected into the container via gravitational potential energy. The medicine bottle is connected to the medicine storage tank and the water tank via independent solenoid valves. The opening and closing of the valves are controlled by a PLC based on signals received from a level switch. The medicine preparation process is divided into two stages: the medicine valve in the medicine storage tank opens, and the medicine flows into the medicine bottle until a high level alarm is triggered, at which point it stops. Similarly, the water supply valve opens until the water tank closes at a high level. The water-to-medicine ratio is 100:2. The medicine bottle has a volume of 400ml, and the water tank has a volume of 20L. To ensure mixing accuracy, the system uses a level switch for quantitative control and a timed protection mechanism to monitor the entire operation. If the preparation time exceeds the set range, the system's protection logic is triggered, all valves are closed, and an alarm is issued. This process does not rely on pumping equipment, thus reducing the risk of wear and tear on mechanical parts and malfunctions, and also reducing energy consumption. The dispensing bottles are made of corrosion-resistant PTFE material, ensuring that the containers will not age due to the chemical properties of the medications during long-term operation. The entire dispensing process is highly automated through PLC logic control, guaranteeing the stability and consistency of the dispensing ratio. The dosing process involves accurately adding the prepared chemical solution to the dosing tank to meet the needs of the converter valve's water cooling system. The dosing process is initiated by a low-level switch in the dosing tank. When the liquid level falls below the set value, the PLC executes the dosing operation, sequentially opening the dosing valve of the dosing bottle and the water tank's water inlet valve to add the prepared chemical solution and clean water. The dosing tank has a capacity of 200 liters and a single dosing volume of 20 liters, ensuring the chemical concentration meets the requirements of the water cooling system. To improve the dosing rate, parameters such as valve response time and pipeline resistance have been optimized. Experiments have shown that the average dosing time is approximately 12 seconds, with a standard deviation of ±0.5 seconds for the rise or fall of the liquid level. The dosing process also incorporates protection logic, which, based on timing, determines whether the dosing time is excessively long (exceeding 15 seconds). In this case, it is immediately shut down, the valve is closed, and an alarm is triggered. This is the working principle of this PLC-based automatic dosing control system and method for a reverse osmosis system.

Claims

1. A PLC-based reverse osmosis system automatic dosing control system, characterized in that, The application relates to an automatic dosing module, a control protection module and a backup control module. The automatic dosing module comprises a medicine bottle unit, a medicine storage unit and a water distribution unit, the medicine bottle unit drives the flow of medicine and water in a fixed volume mode, the medicine bottle unit is connected with the medicine storage unit and the water distribution unit through pipelines, and the medicine bottle unit, the medicine storage unit and the water distribution unit are all provided with liquid level switches. The control protection module comprises a main control unit, a signal acquisition unit and an execution unit, the main control unit is configured to perform logical operation and issue instructions, the signal acquisition unit is connected with the liquid level switches to acquire liquid level states, and the execution unit is configured to control electromagnetic valves of the automatic dosing module for medicine and water. The backup control module is connected with the main control unit and is configured to automatically switch to the backup control module to control the automatic dosing module when the main control unit fails. The automatic dosing module drives the flow of medicine and water through gravity potential, and the control protection module and the backup control module are both connected with a background monitoring unit through Modbus protocol communication.

2. The PLC-based automatic dosing control system for reverse osmosis systems of claim 1, wherein: The automatic dosing module further comprises a dosing barrel unit, the dosing barrel unit is connected with the medicine bottle unit through a pipeline, and the dosing barrel unit is provided with high and low liquid level switches to trigger a dosing operation and monitor liquid level states.

3. The PLC-based automatic dosing control system for reverse osmosis systems of claim 1, wherein: The control protection module further comprises a timing protection logic algorithm, the timing protection logic algorithm is configured to monitor the time of a dispensing process or a dosing process, and when the actual time of the dispensing process or the dosing process exceeds the sum of a preset time and an allowable deviation, a protection action is triggered and the execution unit is closed.

4. The PLC-based automatic dosing control system for reverse osmosis systems of claim 1, wherein: The matching ratio of the water distribution unit and the medicine bottle unit is 100:2, the dispensing process is quantitatively controlled through the liquid level switches, the liquid level switches adopt high-precision float switches, and the average failure-free operation time of the liquid level switches is not less than 100,000 hours.

5. The PLC-based automatic dosing control system for reverse osmosis systems of claim 1, wherein: The background monitoring unit realizes remote monitoring and parameter adjustment of the automatic dosing module and the control protection module through a man-machine interface, and supports query and export of historical data.

6. The PLC-based automatic dosing control system for reverse osmosis systems of claim 1, wherein: The automatic dosing module adopts a modular structure, the medicine bottle unit, the medicine storage unit, the water distribution unit and the pipeline are integrated in a compact frame, the medicine bottle unit, the medicine storage unit and the water distribution unit are made of corrosion-resistant materials, and the corrosion-resistant materials include polytetrafluoroethylene or stainless steel 316L.

7. A PLC-based automatic dosing control method for a reverse osmosis system, which is suitable for a PLC-based automatic dosing control system for a reverse osmosis system according to any one of claims 1-6, characterized in that, The application further discloses a method for controlling the automatic dosing module. S1, dispensing process control: the medicine and water are injected into the medicine bottle unit in a fixed volume mode through gravity potential; the main control unit controls the opening and closing of the execution unit according to the liquid level switch signal in the medicine bottle unit, so that the medicine and water are quantitatively matched; S2, dosing process control: when the low liquid level switch of the dosing barrel unit detects that the liquid level is lower than a set value, the main control unit controls the dosing valve and the water supplement valve to be opened, and the medicine liquid is added into the dosing barrel unit until the high liquid level switch acts. S3, Abnormal protection: The timing protection logic algorithm is set in the master control unit. If the actual operation time of dispensing or dosing exceeds the sum of the preset time and the allowed deviation value, it is determined as abnormal and triggers the protection action to close the related execution unit; S4, State monitoring and communication: The master control unit transmits the liquid level state, valve action record and alarm information to the background monitoring unit in real time through the Modbus protocol.

8. The PLC-based automatic dosing control method for a reverse osmosis system according to claim 7, characterized in that: In step S4, remote interaction and parameter management are also included. The remote interaction and parameter management allow the operator to remotely monitor the system running state, query historical data and export running logs through the human-machine interface of the background monitoring unit, and remotely adjust the dispensing ratio or manually start and stop the process.

9. The PLC-based automatic dosing control method for a reverse osmosis system according to claim 7, characterized in that: In step S3, the abnormal determination logic of the timing protection logic algorithm is: The protection is triggered when is met, wherein is the actual process time, is the preset standard time, is the allowed time deviation.

10. The PLC-based automatic dosing control method for a reverse osmosis system according to claim 7, characterized in that: In step S4, redundancy control switching is also included. The redundancy control switching automatically switches to the backup control module to take over the control right when the master control unit fails. The backup control module uses dual power supply to avoid sudden power failure.

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