A sewage plant precise aeration system based on internet of things wireless communication and a control method thereof

Abstract

The application discloses a sewage plant precise aeration system and control method based on wireless communication of the Internet of Things, which is composed of field sensing, central control processing and remote execution units, adopts bidirectional wireless communication of the Internet of Things and is suitable for complex terrain wiring scenes. The control method takes dissolved oxygen as a reference, adopts 5% gradient step adjustment instead of continuous PID fine adjustment, and is provided with 30Hz fan low-frequency locking. The method realizes independent aeration of multiple biochemical pools in different zones, and signal isolation and anti-interference of the whole link. At the same time, the method distinguishes between conventional parameter early warning and frequency converter hard fault protection, matches fan flexible maintenance reminders, and takes into account continuous production and equipment safety. The application effectively solves the problem of frequent fan adjustment caused by sensor jump, reduces aeration energy consumption, improves system operation stability and operation and maintenance flexibility, and is suitable for precise aeration energy-saving control of biochemical pools of municipal sewage plants.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for wastewater treatment, and is particularly applicable to the precision aeration and energy-saving control system for biochemical tanks in municipal wastewater treatment plants with complex terrain where wired communication cables cannot be laid on site. Background Technology

[0002] In wastewater biological treatment processes, the energy consumption of the aeration system accounts for a relatively high proportion of the total energy consumption of the wastewater treatment plant. Traditional aeration methods mostly adopt fixed-duration timed aeration, which cannot dynamically adjust the air volume according to the real-time water quality in the biological treatment tank. This easily leads to problems such as excessive aeration resulting in wasted energy or insufficient aeration leading to substandard effluent quality.

[0003] Most commonly used aeration control solutions on the market currently employ continuous PID regulation, which is highly dependent on the stability of dissolved oxygen sensor measurements. Under actual operating conditions, dissolved oxygen probe readings are easily affected by bubbles and sludge disturbances, causing fluctuations in values. This directly leads to frequent frequency adjustments by the blower inverter, resulting in increased wear and tear on the blower equipment and severe fluctuations in pipeline air pressure.

[0004] Meanwhile, in many wastewater treatment plants, biological treatment tanks and fan rooms are scattered, obstructed by ditches, and the terrain is complex, making it difficult to lay network cables and signal cables; the operation of high-power fan frequency converters generates strong electromagnetic interference, and outdoor instruments are at risk of induced lightning strikes. Existing systems generally lack a full-link signal isolation and protection solution.

[0005] In addition, most existing wind turbine operation and maintenance systems will directly force shutdown when the operating time reaches the threshold or the equipment parameters exceed the limit. Under the continuous production conditions of sewage treatment plants, shutdown can easily cause the effluent to exceed the standard, resulting in insufficient operation and maintenance flexibility.

[0006] In response to the shortcomings of existing technologies, the applicant, based on on-site engineering practice, developed a zoned precision aeration control system that features anti-interference capabilities, stepped adjustment, wireless long-distance transmission, and graded safety interlocking and flexible early warning functions. Summary of the Invention

[0007] Purpose of the invention To overcome the shortcomings of existing technologies, this paper provides a precision aeration control system and method for wastewater treatment plants based on Internet of Things (IoT) wireless communication. It suppresses frequent blower adjustments caused by sensor jumps, enabling independent aeration control for multiple biological treatment tanks. It provides full-link electrical isolation to resist electromagnetic interference and surge impacts. It distinguishes between general equipment over-limit warnings and inverter hard fault protection, while taking into account unattended safety interlocks and flexible early warning reminders, thereby reducing aeration energy consumption and improving the long-term operational stability of the system. Technical solution A precision aeration control system for wastewater treatment plants based on Internet of Things (IoT) wireless communication is divided into three main parts: a field sensing unit, a central control processing unit, and a remote execution unit. The on-site sensing unit includes a dissolved oxygen sensor 1, a dissolved oxygen signal acquisition and isolation module 2, and a dissolved oxygen signal acquisition and transceiver IoT wireless communication module 3. The dissolved oxygen sensor outputs a 4~20mA analog water quality signal. The signal is first connected to the acquisition and isolation module to complete anti-interference isolation, and the isolated signal is sent to the acquisition IoT wireless communication module. The acquisition IoT wireless communication module is equipped with an independent UPS uninterruptible power supply for short-term continuous data acquisition and wireless transmission during power outages. The central control processing unit includes a dissolved oxygen signal receiving IoT wireless communication module 4, a PLC module 5, a WinCC central control computer data logic processing platform 6, and an aeration blower instruction and status return PLC-end IoT wireless communication transceiver module 7.

[0008] The dissolved oxygen signal receiving terminal IoT wireless communication module receives the on-site water quality signal and transmits it to the PLC module; the PLC module communicates with the WinCC platform via RS485 bus, and the WinCC platform is responsible for data filtering, logic operation, parameter storage, and human-machine interaction; the WinCC platform has a separate reserved external network port for remote operation and maintenance, and the external network link is physically isolated from the PLC industrial control communication link; the PLC module outputs control commands and connects to the PLC terminal IoT wireless communication transceiver module to send commands wirelessly, while continuously receiving operating condition feedback signals such as temperature, current, wind pressure, and faults from the remote fan.

[0009] Remote Execution Unit The remote execution unit includes an inverter-side IoT wireless communication transceiver module 8, an inverter command and status return signal isolation module 9, an inverter 10, and an aeration blower 11. The inverter-side IoT wireless communication transceiver module receives adjustment commands from the central control unit. The analog commands are processed by the isolation module to prevent interference before being connected to the inverter, which drives the aeration blower to adjust the airflow. Signals such as blower operating temperature, current, air pressure, and hardware faults are isolated and then wirelessly transmitted back to the central control unit via the inverter-side IoT wireless communication transceiver module. Multiple aeration blowers are grouped, with each group of blowers independently corresponding to a biological treatment tank, enabling independent aeration control by zone. Isolation devices are deployed throughout the entire analog signal path, forming a three-level isolation protection system: the acquisition end, the central control output end, and the execution end.

[0010] Control methods A precise aeration control method for wastewater treatment plants based on Internet of Things (IoT) wireless communication, executed using the aforementioned hardware system, includes the following steps: S1. Data Acquisition and Preprocessing: The field sensing unit acquires 4~20mA analog signals of dissolved oxygen from the biochemical tank, which are then transmitted to the central control WinCC platform via isolation and IoT wireless communication. The WinCC platform sets upper and lower limit thresholds for dissolved oxygen, eliminates abnormal values ​​caused by instantaneous changes in the sensor, and completes data smoothing and filtering. Simultaneously, it collects data on operating conditions such as fan motor temperature, operating current, pipeline air pressure, air volume, and inverter hardware faults.

[0011] S2. Stepped frequency conversion adjustment: Based on the measured dissolved oxygen value, a 5% frequency gradient adjustment method is used to replace continuous PID fine-tuning, and the interval between single adjustment is greater than or equal to 10 seconds; the fan operating frequency is set to a lower limit of 30Hz and locked, prohibiting the fan from operating at a low frequency below this lower limit; the frequency is slowly adjusted step by step according to the state of high or low dissolved oxygen.

[0012] S3. Zoned Collaborative Control: Multiple blowers are grouped to correspond to different biological tanks. Each group of blowers receives adjustment commands independently and controls the air volume separately, realizing precise aeration of multiple biological tanks in zones as needed.

[0013] S4. Graded safety early warning and interlocking protection ①Routine parameter warning: When the temperature of the fan motor, the operating current, the wind pressure, and the air volume exceed the preset threshold, the upper computer pop-up window flashes and the on-site audible and visual alarm is triggered. Only a warning reminder is output, and the fan continues to run at the current speed without performing a shutdown operation. ② Hardware fault protection: When the frequency converter reports its own hardware fault signal, the central control immediately blocks all adjustment commands sent to the frequency converter and locks the fan operating frequency to prevent the fault from escalating.

[0014] S5. Flexible maintenance and early warning for wind turbines: The system independently accumulates the effective running time of each wind turbine, and the maintenance time threshold is preset manually; when the time reaches the threshold, only maintenance reminder is output, and the wind turbine is operated normally under control without forced shutdown; the time can be manually reset after maintenance is completed.

[0015] S6. Remote Closed-Loop Control: The central control unit generates adjustment commands and sends them to the remote control cabinet via the Internet of Things wireless communication network. The fan operating data is continuously transmitted back to the central control unit to correct the adjustment parameters in real time, forming a full-process remote closed-loop control. The host computer reserves a historical data storage interface, which can be expanded to include operation reports and data analysis functions in the future.

[0016] Beneficial effects 1. It adopts a 5% gradient step adjustment, abandoning the frequent fine-tuning of continuous PID, effectively solving the problem of frequent fan oscillation caused by dissolved oxygen probe jumps, and extending the service life of the fan and frequency converter; it sets a minimum operating frequency of 30Hz to protect the fan from low-frequency resonance damage.

[0017] 2. The entire system is equipped with three levels of signal isolation devices, which are respectively deployed at the acquisition end, the central control end, and the fan execution end to block ground potential difference and frequency conversion electromagnetic interference, resist induced lightning surges, and protect field instruments and automatic control hardware.

[0018] 3. Adopting two-way wireless transparent transmission for industrial IoT, it is suitable for complex factory terrain and scenarios where wiring is not possible; the industrial control RS485 communication and the external network remote access port are physically separated, improving the network security level of industrial control.

[0019] 4. Implement a two-tiered differentiated protection strategy: alarms are triggered only when normal operating parameters exceed limits, without shutting down the system; only inverter malfunctions trigger command blocking. This balances equipment safety with the wastewater treatment plant's continuous production requirements, avoiding the risk of excessive effluent discharge due to abrupt shutdowns; coupled with flexible maintenance reminders based on operating time, it offers greater operational flexibility.

[0020] 5. Multiple biological treatment tanks and multiple blowers are grouped and zoned for control, allowing for on-demand aeration and effectively reducing aeration energy consumption; the system has reserved data expansion interfaces, ensuring strong compatibility and facilitating future functional upgrades and expansions. Detailed Implementation

[0022] 1. A dissolved oxygen sensor is installed at the biochemical pool location. The sensor outputs a 4~20mA analog signal, which is connected to the nearest signal isolation module. After isolating and eliminating on-site interference, the signal is sent to the on-site IoT wireless communication acquisition module. The IoT wireless communication acquisition module is powered by an independent UPS uninterruptible power supply, and the acquired data is sent uplink via a wireless network.

[0023] 2. The central control room IoT wireless communication receiving module receives water quality data and sends it to the PLC module; the PLC establishes communication with the WinCC host computer via RS485 bus; the host computer is connected to the Internet via an independent network cable and carries remote operation and maintenance software, and the external network link does not occupy the PLC's industrial control communication link.

[0024] 3. The WinCC host computer completes signal filtering and step adjustment logic operations, generates a fan frequency adjustment command and sends it to the PLC; the PLC output signal is isolated and then connected to the central control side IoT wireless communication transmission module for wireless transmission to the fan room.

[0025] 4. The remote IoT wireless communication module in the fan room receives control commands: analog frequency commands are connected to the frequency converter through the end isolator; multiple fans are grouped to correspond to different biological tanks for independent aeration; fan temperature, current, air pressure, air volume, and fault status signals are isolated and transmitted back to the central control, forming a two-way closed-loop link.

[0026] 1. The WinCC host computer continuously receives water quality signals, sets upper and lower limits for dissolved oxygen data, and eliminates instantaneous abnormal jumps in values ​​to avoid erroneous adjustments; at the same time, it continuously collects real-time data on fan motor temperature, operating current, air pressure, and air volume.

[0027] 2. Implement a step-by-step adjustment strategy based on the measured dissolved oxygen value, with adjustment steps divided into 5% increments and adjustment intervals of no less than 10 seconds; lock the fan frequency at a minimum of 30Hz and prohibit continuous low-frequency operation.

[0028] 3. The host computer scans the fan operating parameters and inverter fault signals in real time. ①If the temperature, current, wind pressure, or air volume exceeds the preset limits, the screen will flash and an audible and visual alarm will sound, and the fan will continue to run without performing a shutdown operation. ② Once a hardware fault signal of the frequency converter is identified, immediately stop sending any adjustment commands to the faulty fan frequency converter and lock the frequency.

[0029] 4. Independently calculate the effective operating time of each wind turbine; maintenance personnel can preset the maintenance time. When the time reaches the threshold, a maintenance reminder will pop up on the interface. The system will maintain normal control of the wind turbine. After the maintenance is completed, the timer will be manually reset.

[0030] 5. The host computer reserves a historical storage channel for the fan operating parameters, and historical data reports can be directly configured in the future without changing the underlying control architecture. Attached Figure Description

[0031] Figure 1 shows the overall architecture of this system. Attached Figure

[0032] 1. Dissolved oxygen sensor; 2. Dissolved oxygen signal acquisition and isolation module; 3. Dissolved oxygen signal acquisition terminal transceiver IoT wireless communication module; 4. Dissolved oxygen signal receiving and transmitting IoT wireless communication module; 5. PLC module; 6. Central Control Computer WinCC Data Logic Processing Platform; 7. Aeration blower command and status return signal IoT wireless communication PLC transceiver module; 8. Aeration blower command and status return signal IoT wireless communication inverter transceiver module; 9. Inverter command and status return signal isolation module; 10. Frequency converter; 11. Aeration blower.

Claims

1. A precision aeration system and control method for wastewater treatment plants based on Internet of Things (IoT) wireless communication, characterized in that, Includes the following steps: S1. Data Acquisition and Preprocessing: The dissolved oxygen sensor acquires the analog signal of dissolved oxygen in the biological treatment tank, which is then transmitted to the central control WinCC platform via isolation and IoT wireless communication. WinCC sets upper and lower limits to remove instantaneous abnormal values ​​and completes data smoothing filtering. Simultaneously, it acquires the motor temperature, operating current, pipeline air pressure, air volume, and inverter hardware fault condition signals of the aeration blower. S2, stepped frequency conversion adjustment: Based on the dissolved oxygen detection value, the fan operating frequency is adjusted using a 5% frequency gradient adjustment method. The interval between single adjustment is ≥10s. The minimum operating frequency of the fan is set to 30Hz and a lock-up limit is set to prevent the fan from running continuously at low frequency. S3, Zoned Collaborative Aeration: Multiple aeration blowers are grouped to correspond to different biological tanks. Each group of blowers receives control commands independently and adjusts the air volume separately to achieve precise zoned aeration. S4. Graded safety interlock protection: S4-1 When the fan temperature, current, air pressure, and air volume exceed the preset warning threshold, only the upper computer pop-up window and audible and visual alarm will be triggered. The fan will continue to run at the current speed and will not perform a shutdown operation. S4-2. When a hardware fault signal is detected in the frequency converter, immediately block all adjustment commands sent to the frequency converter and lock the current operating frequency of the fan. S5. Flexible maintenance early warning: The system accumulates the effective running time of a single wind turbine. Once the time reaches the preset maintenance threshold, only a maintenance reminder is output, and the wind turbine continues to operate under normal control. The timer can be manually reset after maintenance is completed. S6. Remote closed-loop control: The central control unit generates adjustment commands and sends them to the remote wind turbine control cabinet via the Internet of Things wireless communication network. The wind turbine operating condition signal is transmitted back to the central control unit in reverse, and the adjustment parameters are corrected in real time, enabling remote closed-loop control throughout the entire process.

2. The method for precise aeration control of wastewater treatment plants based on Internet of Things wireless communication according to claim 1, characterized in that: In step S1, analog signal isolation devices are added to the water quality acquisition link, in step S4, the working condition feedback link, and in step S6, the command issuance link, to achieve full-link anti-interference protection.

3. The method for precise aeration control of wastewater treatment plants based on Internet of Things wireless communication according to claim 1, characterized in that: The PLC module communicates with the WinCC central control platform via RS485, and the WinCC external network remote operation and maintenance port is physically isolated from the PLC industrial control communication link.

4. The method for precise aeration control of wastewater treatment plants based on Internet of Things wireless communication according to claim 1, characterized in that: The WinCC central control platform reserves an expansion interface for historical data storage, which can be configured later to generate historical reports of wind turbine operation.

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