An intelligent cut-off control system for ventilation engineering concentration

Abstract

The present invention provides a ventilation engineering concentration intelligent cut-off control system, which relates to the field of intelligent control technology, and includes: a power supply module; a gas concentration probe, electrically connected to the power supply module, for real-time detection of gas concentration; a control module, connected to the power supply module and the gas concentration probe, for receiving a gas concentration signal, and analyzing the gas concentration signal to generate a control signal; a remote transmission module, connected to the power supply module and the control module, for remote transmission of control signals; a cut-off valve, electrically connected to the power supply module, for receiving a control signal emitted by the remote transmission module, and opening or closing the gas pipeline according to the control signal. The control module of the present invention can determine and prompt a pre-set replacement qualification standard, avoiding the safety risks brought by operating personnel approaching the vent to detect changes in gas concentration.

Description

Technical Field

[0001] The invention relates to the field of intelligent control technology, and in particular to an intelligent cut-off control system for ventilation engineering concentration. Background Art

[0002] Before ventilating, city gas users need to start the pressure regulating box to replace the air at each downstream terminal inlet. For medium and low pressure, the direct replacement method is often used, that is, the gas is input from the connected old gas pipeline to the newly built pipeline system, and the air is directly replaced by the gas. This method is relatively simple and economical, but it has certain risks, because during the replacement process, a mixture of gas and air must be produced in the pipeline. The mixing ratio of this mixed gas is uncontrollable and is eventually discharged directly through the terminal vent; at the same time, it is necessary to manually detect the concentration of the vented gas, that is, the gas operator uses a gas concentration detector to detect the terminal vented gas, and the replacement is completed if the test is qualified. The qualified replacement standard is based on the relevant provisions of CJJ51-2016 "Safety Technical Regulations for Operation, Maintenance and Emergency Repair of Urban Gas Facilities": that is, the concentration of the gas should be measured three times in a row, each interval should not be less than 5 minutes, and the gas concentration measurement value should be greater than 90%.

[0003] At present, the terminal concentration detection process of user ventilation replacement includes: first, remove the inlet plug, install the replacement valve with short section and replacement hose; second, slowly open the front and end valves to start replacement; third, use the gas concentration detector to detect the outlet of the replacement hose, and complete the replacement process after passing the test.

[0004] Therefore, the prior art may have the following disadvantages:

[0005] 1. Currently, operators hold a handheld gas concentration detection device close to the discharge port of the replacement hose to measure the gas concentration. However, when the mixed gas in the discharge port pipe is discharged, there is a certain flow rate and a local negative pressure is formed instantly. The air flows to the mixed gas column to a certain extent. At this time, there must be a certain error in the measured gas concentration, which affects the replacement effect and efficiency.

[0006] 2. Currently, most of the gas emissions during the replacement process rely on theoretical calculation formulas, which have not been verified by actual measurements. At the same time, a gas mixing process will occur during the pipeline replacement process. The pressure, gas flow rate, and pipe diameter in the pipe will affect the length of the mixing section. Therefore, the gas concentration distribution during the replacement process is relatively complex, and the mixture of air and gas in the pipe changes nonlinearly. The error in estimating gas emissions through theoretical calculations is relatively large. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a ventilation engineering concentration intelligent cut-off control system, which avoids the safety risks brought by operating personnel approaching the vent to detect changes in gas concentration; at the same time, the gas emissions are estimated based on concentration detection and flow meter, which is convenient for the company's methane emissions accounting.

[0008] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0009] A ventilation engineering concentration intelligent cut-off control system, comprising:

[0010] Power supply module;

[0011] A gas concentration probe, electrically connected to the power supply module, for real-time detection of gas concentration;

[0012] A flow meter, electrically connected to the power supply module, for detecting the mixed gas flow of fuel gas and air in real time;

[0013] A control module, connected to the power supply module and the gas concentration probe, for receiving a gas concentration signal and analyzing the gas concentration signal to generate a control signal;

[0014] A remote transmission module, connected to the power supply module and the control module, for remotely transmitting control signals;

[0015] The shut-off valve is electrically connected to the power supply module, and is used to receive the control signal transmitted by the remote transmission module, and to open or close the gas pipeline according to the control signal.

[0016] Furthermore, the gas pipeline is connected with the user introduction port and the terminal release port to control the introduction and release of the gas.

[0017] Furthermore, a flow meter is provided on the gas pipeline, and the flow meter is connected to the control module.

[0018] Furthermore, the gas concentration signal is analyzed to generate a control signal, including:

[0019] Obtain the original gas concentration signal through the gas concentration probe;

[0020] Smooth the original gas concentration signal and extract key features;

[0021] According to the key features, the changing trend of the gas concentration signal is analyzed to obtain the gas emission during the displacement process;

[0022] The changing trend of the gas concentration signal is subjected to fuzzy reasoning to obtain a fuzzy value, which is then defuzzified and converted into a control instruction.

[0023] Furthermore, the changing trend of the gas concentration signal is subjected to fuzzy reasoning to obtain a fuzzy value, which is then defuzzified and converted into a control instruction, including:

[0024] The real-time monitored gas concentration and concentration change trend are converted into a fuzzy set of gas concentration and a fuzzy set of concentration change trend respectively;

[0025] Determine the fuzzy control rules in the rule base according to the gas concentration and the gas concentration change trend;

[0026] According to the fuzzy set of gas concentration, the fuzzy set of concentration change trend and fuzzy control rules, fuzzy reasoning is performed to determine the fuzzy value of the control signal of the cut-off valve;

[0027] Convert the fuzzy value of the control signal into specific control instructions.

[0028] Furthermore, according to the key features, the changing trend of the gas concentration signal is analyzed to obtain the gas emission during the displacement process, including:

[0029] According to the key characteristics, a data acquisition system is set up to monitor and record the gas concentration v and flow rate q every 20 seconds;

[0030] Continuously monitor and record data until the replacement process is completed. After the replacement is completed, collect and record the final gas concentration v at the time of closing the shut-off valve. n and flow rate q n ;

[0031] Arrange the collected data to form a concentration sequence v1 to v n , flow sequence q1 to q n ;

[0032] Through V = v1 × q1 × 20 / 3600 + ... + v n ×q n ×20 / 3600 to calculate the gas release volume V during the entire replacement process, where v i Represents the gas concentration collected each time, q i represents the corresponding flow rate, 20 is the sampling time interval in seconds, and 3600 is a constant used to convert seconds to hours;

[0033] By analyzing the changing trend of the calculated gas emission volume V, the mixing condition of the gas during the replacement process can be predicted.

[0034] Furthermore, fuzzy reasoning is performed based on the fuzzy set of gas concentration, the fuzzy set of concentration change trend and the fuzzy control rule to determine the fuzzy value of the control signal of the cut-off valve, including:

[0035] The measured values ​​of gas concentration and concentration change trend monitored in real time are converted into corresponding fuzzy set membership degrees through the set domain and membership function;

[0036] According to the fuzzy set membership degree of the gas concentration and concentration change trend obtained by conversion, matching is performed in the preset fuzzy control rule library to find the corresponding fuzzy control rule;

[0037] The matched fuzzy control rules are used for fuzzy reasoning, and the fuzzy value of the control signal of the shut-off valve is determined according to the fuzzy set of gas concentration and concentration change trend.

[0038] Furthermore, the real-time monitored gas concentration and concentration change trend are converted into a fuzzy set of gas concentration and a fuzzy set of concentration change trend, respectively, including:

[0039] Determine the domain and membership functions of fuzzy sets;

[0040] The gas concentration data is obtained in real time through the sensor, and the concentration change trend is calculated based on the gas concentration data;

[0041] The real-time acquired gas concentration data is converted into a fuzzy set of gas concentration through a membership function; the concentration change trend is divided into several intervals;

[0042] For each interval, a membership function is defined to determine the extent to which a specific concentration trend value belongs to each interval;

[0043] When there is a specific concentration change trend value, the membership function is used to calculate the membership degree of the concentration change trend value belonging to each interval;

[0044] The membership degrees of each interval are combined into a fuzzy set.

[0045] Furthermore, the concentration change trend is calculated based on the gas concentration data, including:

[0046] Set the size of a sliding window, and at each sampling moment, combine the current sample value with the previous sample values ​​to form a data set;

[0047] The data set is averaged to obtain the sliding average at the current moment. As time goes by, the sliding window moves forward. Each new sample value enters the window, and the first sample value moves out of the window. At each new sampling moment, the sliding average is recalculated.

[0048] By comparing the difference between two adjacent sliding averages, the concentration change trend can be calculated. The concentration change trend includes: if the difference is positive, it means that the concentration is rising; if the difference is negative, it means that the concentration is falling; if the difference is close to zero, it means that the concentration remains basically stable.

[0049] Furthermore, the fuzzy value of the control signal is converted into a specific control instruction, including:

[0050] According to fuzzy control rules and fuzzy sets, the membership degree of elements in each fuzzy set is calculated;

[0051] After calculating the membership of each fuzzy set, determine the element with the largest membership;

[0052] According to the element with the largest membership degree, the corresponding fuzzy value of the control signal is determined;

[0053] Convert the fuzzy value of the control signal into specific control instructions.

[0054] The above solution of the present invention includes at least the following beneficial effects:

[0055] The above scheme of the present invention avoids the safety risks brought by the operating personnel approaching the discharge port to detect the change of gas concentration; through the built-in gas concentration probe, it overcomes the numerical error caused by concentration detection at the discharge end outlet, and improves the refinement of the gas replacement process.

[0056] By integrating the gas concentration detection probe, power supply module, cut-off device, remote transmission and control module, the digitalization of the replacement end detection process is realized, and the replacement process is standardized by replacing manual operation with intelligent control. By real-time monitoring of gas concentration and flow, the gas emission can be estimated more accurately, effectively reducing the error caused by theoretical calculation.

[0057] By integrating the gas concentration detection probe, power supply module, cut-off device, remote transmission and control module, the digitalization of the replacement terminal detection process is realized. By replacing manual operation with intelligent control, the replacement process is further standardized, the degree of refinement is improved, and the safety of operators is guaranteed. The built-in gas concentration detection probe improves the accuracy of concentration detection; remote data transmission ensures that operators can grasp the changes in gas concentration through handheld terminals; the control module can judge and prompt the pre-set replacement qualification standards; the automatic cut-off device realizes timely and effective cut-off after the replacement is qualified, avoiding excessive emission and causing greenhouse effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 It is a schematic diagram of a ventilation engineering concentration intelligent cut-off control system provided by an embodiment of the present invention.

[0059] Figure 2 The embodiment of the present invention provides a flow chart of analyzing a gas concentration signal to generate a control signal.

[0060] Numbers in the figure: 1. User inlet; 2. Gas concentration probe; 3. Flow meter; 4. Control module; 5. Remote transmission module; 6. Cut-off valve; 7. Terminal discharge port; 8. Power supply module; DETAILED DESCRIPTION

[0061] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0062] like Figure 1 As shown, an embodiment of the present invention provides a ventilation engineering concentration intelligent cut-off control system, comprising:

[0063] Power supply module 8;

[0064] A gas concentration probe 2, electrically connected to the power supply module 8, for real-time detection of gas concentration;

[0065] A flow meter 3 is electrically connected to the power supply module and is used to detect the mixed gas flow of gas and air in real time; a control module 4 is connected to the power supply module 8 and the gas concentration probe 2 and is used to receive a gas concentration signal and analyze the gas concentration signal to generate a control signal;

[0066] A remote transmission module 5, connected to the power supply module 8 and the control module 4, for remotely transmitting control signals;

[0067] The shut-off valve 6 is electrically connected to the power supply module 8 and is used to receive the control signal transmitted by the remote transmission module 5 and open or close the gas pipeline according to the control signal.

[0068] In the embodiment of the present invention, the power supply module 8 supplies power to ensure the stability of the power supply of the entire system. The gas concentration probe 2 and the cut-off valve 6 are used to automatically cut off the gas supply when the preset conditions are met. The control module 4 is used to receive and process the detection signal of the gas concentration probe, and has the functions of data collection, replacement qualification judgment and gas mixing situation estimation. The remote transmission module 5 is connected to the control module and is used to remotely transmit the data collected by the control module, the equipment status information and the gas mixing situation estimation, and is used to detect the gas concentration in real time to enter the working state. The gas concentration probe 2 detects the gas concentration in the environment in real time, and the probe 2 converts the detected gas concentration signal into a telecommunication signal. The control module 4 receives the gas concentration signal and analyzes and processes the signal. The control module 4 remotely transmits the generated control signal to the cut-off valve 6 through the remote transmission module 5. After the cut-off valve 6 receives the control signal sent by the remote transmission module 5, it performs corresponding actions according to the instructions of the signal. When the device is used, first connect the device to the building inlet of the pipe section to be replaced, slowly open the inlet valve, and open the cut-off valve through remote control to start replacement; secondly, set the concentration trend and the end of replacement prompts in the control module, and upload the relevant prompts to the operator's handheld terminal through remote transmission. The program setting is:

[0069] The gas concentration reminder can be set to 30%, 60%, 80%, and 90%. When the gas concentration reaches the above values, a reminder message will be sent to the operator's handheld terminal.

[0070] When the gas concentration reaches 90%, the control module collects the gas concentration value every 5 minutes. When the gas concentration value collected for 3 consecutive times is greater than 90%, a shut-off valve closing instruction is sent. At this time, the shut-off valve is closed and the replacement is completed, and the replacement qualified information is sent to the operator's handheld terminal;

[0071] Finally, the user ventilation replacement project is completed. The operator closes the inlet valve in front of the building, remotely controls the opening of the cut-off valve to vent the mixed gas in the device, and dismantles the device, which includes a gas concentration probe, a cut-off valve, a power supply module, a control module, and a remote transmission module. It has explosion-proof performance and can realize the functions of gas concentration detection and automatic valve cut-off. At the same time, the control module has functions such as data collection and replacement qualification judgment, and can complete the remote transmission of relevant parameters and equipment status with the remote transmission module.

[0072] In a preferred embodiment of the present invention, the gas pipeline is connected to the user introduction port 1 and the terminal release port 7 to control the introduction of gas and the release of gas.

[0073] In the embodiment of the present invention, the introduction of gas is strictly controlled through the user introduction port 1, which can ensure that only authorized users can access the gas, reducing the risk of illegal access and abuse. The design of the terminal release port 7 can quickly release the pressure in the pipeline in an emergency, reducing the risk of safety accidents caused by excessive pressure. The user introduction port 1 can flexibly adjust the gas supply according to user needs to meet the actual usage needs of different users. The existence of the terminal release port 7 makes it easy to drain the gas in the pipeline during maintenance, inspection or other special circumstances, ensuring the safety of the operator.

[0074] In a preferred embodiment of the present invention, a flow meter 3 is provided on the gas pipeline, and the flow meter 3 is connected to the control module.

[0075] In the embodiment of the present invention, the flow meter can accurately measure the flow of gas. By connecting with the control module, the data provided by the flow meter can be monitored in real time, so that the operator can understand the gas usage at any time and discover abnormalities in time. If the flow meter detects abnormal flow, such as a sudden increase or decrease in flow, the control module can trigger the alarm system and notify the operator in time to ensure the safe operation of the system.

[0076] In a preferred embodiment of the present invention, the gas concentration signal is analyzed to generate a control signal, including:

[0077] Step 11, obtaining an original gas concentration signal through a gas concentration probe;

[0078] Step 12, smoothing the original gas concentration signal and extracting key features;

[0079] Step 13, analyzing the change trend of the gas concentration signal according to the key features to obtain the gas emission during the replacement process;

[0080] Step 14, fuzzy reasoning is performed on the variation trend of the gas concentration signal to obtain a fuzzy value, the fuzzy value is defuzzified, and converted into a control instruction.

[0081] In the embodiment of the present invention, the change of gas concentration can be monitored in real time through the gas concentration probe, and the extraction of key features can help us understand the change pattern of gas concentration more accurately. By analyzing the extracted key features, the changing trend of gas concentration can be predicted, and the mixing condition of gas during the replacement process can be understood. Fuzzy reasoning can handle uncertainty and ambiguity, and defuzzification converts the result of fuzzy reasoning into clear control instructions. Real-time monitoring and precise analysis of gas concentration signals can timely discover and deal with potential safety risks and prevent accidents such as gas leakage. At the same time, by extracting key features and fuzzy reasoning, more precise control instructions can be generated, thereby achieving fine control of the gas system. Automated control instruction generation and response can reduce the need for manual intervention and improve the operating efficiency of the system. Accurate gas concentration monitoring and control help optimize gas use, reduce waste, and improve energy efficiency.

[0082] In a preferred embodiment of the present invention, fuzzy reasoning is performed on the variation trend of the gas concentration signal to obtain a fuzzy value, and the fuzzy value is defuzzified and converted into a control instruction, including:

[0083] The real-time monitored gas concentration and concentration change trend are converted into a fuzzy set of gas concentration and a fuzzy set of concentration change trend respectively;

[0084] Determine the fuzzy control rules in the rule base according to the gas concentration and the gas concentration change trend;

[0085] According to the fuzzy set of gas concentration, the fuzzy set of concentration change trend and fuzzy control rules, fuzzy reasoning is performed to determine the fuzzy value of the control signal of the cut-off valve;

[0086] Convert the fuzzy value of the control signal into specific control instructions.

[0087] In the embodiments of the present invention, the present invention is capable of handling uncertainty and noise, so that the system can remain stable and reliable when faced with inaccurate or noisy data; the fuzzy control rules are flexibly adjusted according to actual conditions; the control signal generated by fuzzy reasoning is a continuous fuzzy value, which can achieve a smooth transition of the control signal when converted into a specific control instruction through the maximum membership method; unnecessary gas leakage and waste can be avoided by accurately controlling the opening and closing of the shut-off valve; real-time monitoring of the gas concentration and concentration change trend, and timely adjustment of the state of the shut-off valve through fuzzy control can effectively prevent safety hazards such as gas leakage and improve the safety performance of the system.

[0088] In a preferred embodiment of the present invention, the change trend of the gas concentration signal is analyzed according to the key features to obtain the gas emission during the displacement process, including:

[0089] According to the key characteristics, a data acquisition system is set up to monitor and record the gas concentration v and flow rate q every 20 seconds;

[0090] Continuously monitor and record data until the replacement process is completed. After the replacement is completed, collect and record the final gas concentration v at the time of closing the shut-off valve. n and flow rate q n ;

[0091] Arrange the collected data to form a concentration sequence v1 to v n , flow sequence q1 to q n ;

[0092] Through V = v1 × q1 × 20 / 3600 + ... + v n ×q n ×20 / 3600 to calculate the gas release volume V during the entire replacement process, where v i Represents the gas concentration collected each time, q i represents the corresponding flow rate, 20 is the sampling time interval in seconds, and 3600 is a constant used to convert seconds to hours.

[0093] In the embodiment of the present invention, the gas concentration and flow rate are monitored every 20 seconds, so that the real-time monitoring of the gas system can be realized. The formula V = v1 × q1 × 20 / 3600 + ... + v n ×q n ×20 / 3600 can accurately calculate the amount of gas released during the replacement process, which helps to evaluate the gas usage efficiency and mixing conditions. By analyzing the release amount, the mixing conditions of the gas during the replacement process can be understood. At the same time, monitoring the gas concentration and flow rate can help to promptly discover potential safety risks.

[0094] In a preferred embodiment of the present invention, the measured values ​​of the gas concentration and concentration change trend monitored in real time are converted into corresponding fuzzy set membership degrees through the set domain and membership function;

[0095] According to the fuzzy set membership degree of the gas concentration and concentration change trend obtained by conversion, matching is performed in the preset fuzzy control rule library to find the corresponding fuzzy control rule;

[0096] The matched fuzzy control rules are used for fuzzy reasoning, and the fuzzy value of the control signal of the shut-off valve is determined according to the fuzzy set of gas concentration and concentration change trend.

[0097] In the embodiment of the present invention, the control rules are divided into four categories:

[0098] Category 1: When the gas concentration is ≤60%, the concentration is judged as "low" and the following rules are implemented: ① Monitor for 20 seconds. If the methane concentration is stable or shows an upward trend, send the shut-off valve "open" command; ② Monitor for 20 seconds. If the methane concentration shows a downward trend, manually close the front-end gas inlet, send the shut-off valve "close" command, and check the cause of the fault.

[0099] Category 2: When the gas concentration is in the range of (60%, 80%), the concentration is judged to be "medium" and the following rules are implemented: ① Monitor for 20 seconds. If the methane concentration is stable or shows an upward trend, send the "open" command to the shut-off valve and predict the time T seconds when the concentration will reach 90% for the first time. T = 20 × (90% - V2) / (V2 - V1), V2 is the current concentration, and V1 is the concentration 20 seconds ago; ② Monitor for 20 seconds. If the methane concentration shows a downward trend, close the front-end gas inlet and shut-off valve, and check the cause of the fault.

[0100] Category 3: When the gas concentration is in the range of [80%, 90%), the concentration is judged to be "high" and the following rules are implemented: ① Monitor for 20 seconds. If the methane concentration is stable or shows an upward trend, send the shut-off valve "prepare to close" command and predict the time when the concentration reaches 90% for the first time, T seconds, T = 20 × (90% - V2) / (V2 - V1), V2 is the current concentration, and V1 is the concentration 20 seconds ago; ② Monitor for 20 seconds. If the methane concentration shows a downward trend, close the front-end gas inlet and shut-off valve, and check the cause of the fault.

[0101] Category 4: When the gas concentration is ≥90%, the concentration is judged as "qualified" and the following rules are implemented: first record the time t1 when the concentration is 90%, and collect the concentration v1 at t1+5min: ① If v1≥90%, continue to collect the concentration v2 at t1+10min. If v2≥90%, send the shut-off valve "close" command at this time; if v2<90%, repeat step ①; ② If v1<90%, repeat step ①. The fuzzy control rules enable the system to make decisions quickly based on the current gas concentration and concentration change trend, and the fuzzy control rules can be adjusted and optimized according to the actual situation, which enables the system to better adapt to specific application environments and needs.

[0102] In a preferred embodiment of the present invention, the real-time monitored gas concentration and concentration change trend are converted into a fuzzy set of gas concentration and a fuzzy set of concentration change trend, respectively, including:

[0103] Determine the domain and membership functions of fuzzy sets;

[0104] The gas concentration data is obtained in real time through the sensor, and the concentration change trend is calculated based on the gas concentration data;

[0105] The real-time acquired gas concentration data is converted into a fuzzy set of gas concentration through a membership function; the concentration change trend is divided into several intervals;

[0106] For each interval, a membership function is defined to determine the extent to which a specific concentration trend value belongs to each interval;

[0107] When there is a specific concentration change trend value, the membership function is used to calculate the membership degree of the concentration change trend value belonging to each interval;

[0108] The membership degrees of each interval are combined into a fuzzy set.

[0109] In the embodiment of the present invention, by defining the domain and membership function, the data of gas concentration and its changing trend can be processed more flexibly. The use of membership function enables the system to process fuzzy and uncertain data. At the same time, by dividing the intervals of concentration change trend and defining membership function for each interval, the system can more accurately judge the changing trend of the current gas concentration, improve the accuracy of decision-making, and the system has better fault tolerance for small fluctuations or abnormal values ​​of sensor data.

[0110] In a preferred embodiment of the present invention, the concentration change trend is calculated based on the gas concentration data, including:

[0111] Set the size of a sliding window, and at each sampling moment, combine the current sample value with the previous sample values ​​to form a data set;

[0112] The data set is averaged to obtain the sliding average at the current moment. As time goes by, the sliding window moves forward. Each new sample value enters the window, and the first sample value moves out of the window. At each new sampling moment, the sliding average is recalculated.

[0113] By comparing the difference between two adjacent sliding averages, the concentration change trend can be calculated. The concentration change trend includes: if the difference is positive, it means that the concentration is rising; if the difference is negative, it means that the concentration is falling; if the difference is close to zero, it means that the concentration remains basically stable.

[0114] In an embodiment of the present invention, by calculating the average value within the sliding window, instantaneous fluctuations and noise in the data can be effectively smoothed out, thereby more clearly revealing the long-term trend of the gas concentration. The sliding window moves over time and can provide real-time concentration change trend information. The calculation of the sliding average value is relatively simple and efficient. By analyzing the changes in the sliding average value, the future trend of the gas concentration can be predicted. The method of using a sliding window to calculate the sliding average value and determine the concentration change trend can provide real-time and smooth concentration data, which is helpful to accurately predict and promptly respond to changes in gas concentration, while reducing false alarms and improving system reliability.

[0115] In a preferred embodiment of the present invention, converting the control signal fuzzy value into a specific control instruction includes:

[0116] According to fuzzy control rules and fuzzy sets, the membership degree of elements in each fuzzy set is calculated;

[0117] After calculating the membership of each fuzzy set, determine the element with the largest membership;

[0118] According to the element with the largest membership degree, the corresponding fuzzy value of the control signal is determined;

[0119] Convert the fuzzy value of the control signal into specific control instructions.

[0120] In the embodiment of the present invention, fuzzy control can handle this uncertainty well, and the degree to which an element belongs to each fuzzy set is determined by calculating the membership degree, so as to more accurately reflect the actual situation. Since fuzzy control does not rely on an accurate mathematical model, it has strong robustness to changes in system parameters and external interference. Even if there is a certain uncertainty or noise in the system, fuzzy control can maintain stable control performance through the reasonable design of membership degree and fuzzy rules. Fuzzy control rules can be flexibly adjusted according to actual needs, so that the control system can adapt to different working environments and task requirements. By modifying the membership function or adjusting the fuzzy rules, the system performance can be easily optimized without making large-scale changes to the entire control system. Compared with traditional precise control methods, fuzzy control does not require the establishment of an accurate mathematical model, thereby simplifying the complexity of control design. Designers can more intuitively formulate fuzzy rules and membership functions based on experience and professional knowledge.

[0121] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A ventilation engineering concentration intelligent cut-off control system, characterized in that: include: Power supply module (8); A gas concentration probe (2) is electrically connected to the power supply module (8) and is used to detect the gas concentration in real time; A control module (4) connected to the power supply module (8) and the gas concentration probe (2), and used for receiving a gas concentration signal and analyzing the gas concentration signal to generate a control signal; A remote transmission module (5), connected to the power supply module (8) and the control module (4), and used for remotely transmitting control signals; The cut-off valve (6) is electrically connected to the power supply module (8) and is used to receive the control signal transmitted by the remote transmission module (5) and open or close the gas pipeline according to the control signal; the gas pipeline is connected to the user introduction port (1) and the terminal discharge port (7); a flow meter (3) is provided on the gas pipeline, and the flow meter (3) is connected to the control module; the gas concentration signal is analyzed to generate a control signal, including: Obtain the original gas concentration signal through the gas concentration probe; Smooth the original gas concentration signal and extract key features; According to the key features, the changing trend of the gas concentration signal is analyzed to obtain the gas emission during the displacement process; Performing fuzzy reasoning on the changing trend of the gas concentration signal to obtain a fuzzy value, defuzzifying the fuzzy value, and converting it into a control instruction; Performing fuzzy reasoning on the changing trend of the gas concentration signal to obtain a fuzzy value, defuzzifying the fuzzy value, and converting it into a control instruction, including: The real-time monitored gas concentration and concentration change trend are converted into a fuzzy set of gas concentration and a fuzzy set of concentration change trend respectively; Determine the fuzzy control rules in the rule base according to the gas concentration and the gas concentration change trend; According to the fuzzy set of gas concentration, the fuzzy set of concentration change trend and fuzzy control rules, fuzzy reasoning is performed to determine the fuzzy value of the control signal of the cut-off valve; Convert the fuzzy value of the control signal into a specific control instruction; analyze the change trend of the gas concentration signal according to the key characteristics to obtain the gas emission during the displacement process, including: According to the key characteristics, a data acquisition system is set up to monitor and record the gas concentration v and flow rate q every 20 seconds; Continuously monitor and record data until the replacement process is completed. After the replacement is completed, collect and record the final gas concentration v at the time of closing the shut-off valve. n and flow rate q n ; Arrange the collected data to form a concentration sequence v1 to v n , flow sequence q1 to q n ; Through V = v1 × q1 × 20 / 3600 + ... + v n ×q n ×20 / 3600 to calculate the gas release volume V during the entire replacement process, where v i Represents the gas concentration collected each time, q i represents the corresponding flow rate, 20 is the sampling time interval in seconds, and 3600 is a constant used to convert seconds into hours; according to the fuzzy set of gas concentration, the fuzzy set of concentration change trend and the fuzzy control rules, fuzzy reasoning is performed to determine the fuzzy value of the control signal of the cut-off valve, including: The measured values ​​of gas concentration and concentration change trend monitored in real time are converted into corresponding fuzzy set membership degrees through the set domain and membership function; According to the fuzzy set membership degree of the gas concentration and concentration change trend obtained by conversion, matching is performed in the preset fuzzy control rule library to find the corresponding fuzzy control rule; The matched fuzzy control rules are used for fuzzy reasoning, and the fuzzy value of the control signal of the cut-off valve is determined according to the fuzzy set of the gas concentration and the concentration change trend; the real-time monitored gas concentration and the concentration change trend are converted into the fuzzy set of the gas concentration and the fuzzy set of the concentration change trend, respectively, including: Determine the domain and membership functions of fuzzy sets; The gas concentration data is obtained in real time through the sensor, and the concentration change trend is calculated based on the gas concentration data; The real-time acquired gas concentration data is converted into a fuzzy set of gas concentration through a membership function; the concentration change trend is divided into several intervals; For each interval, a membership function is defined to determine the extent to which a specific concentration trend value belongs to each interval; When there is a specific concentration change trend value, the membership function is used to calculate the membership degree of the concentration change trend value belonging to each interval; The membership of each interval is combined into a fuzzy set; the concentration change trend is calculated based on the gas concentration data, including: Set the size of a sliding window, and at each sampling moment, combine the current sample value with the previous sample values ​​to form a data set; The data set is averaged to obtain the sliding average at the current moment. As time goes by, the sliding window moves forward. Each new sample value enters the window, and the first sample value moves out of the window. At each new sampling moment, the sliding average is recalculated. By comparing the difference between two adjacent sliding average values, the concentration change trend is calculated. The concentration change trend includes: if the difference is positive, it means that the concentration is rising; if the difference is negative, it means that the concentration is falling; if the difference is close to zero, it means that the concentration remains basically stable; the control signal fuzzy value is converted into a specific control instruction, including: According to fuzzy control rules and fuzzy sets, the membership degree of elements in each fuzzy set is calculated; After calculating the membership of each fuzzy set, determine the element with the largest membership; According to the element with the largest membership degree, the corresponding fuzzy value of the control signal is determined; Convert the fuzzy value of the control signal into specific control instructions.

Images