Multifunctional SF6 and mixed gas density relay on-line verification device and method

Abstract

The invention, which relates to the technical field of SF6 operation and maintenance, discloses a multifunctional SF6 and mixed gas density relay on-line verification apparatus comprising a measurement module, a PLC chip, a control module, a voltage regulation module, an early warning module, an analysis module, a data storage module, a communication module and a display module. The measuring module is used for measuring data of pressure, temperature and decomposition products of gas by using various sensors; the PLC chip receives the data, calculates and processes the data, and then sends a control signal to the control module and the voltage regulating module; the control module receives the control signal and controls the device; the voltage regulation module carries out voltage regulation operation; the early warning module sends alarm information when abnormity occurs; the analysis module performs deep analysis on related data accumulated for a long time to generate a monitoring report; the data storage module stores data; the communication module carries out communication between the modules; the display module displays related data, alarm information and a monitoring report to operation and maintenance personnel; through mutual cooperation of all the modules, the device achieves the purposes of monitoring and fault early warning of SF6 and mixed gas thereof by operation and maintenance personnel.

Description

Technical Field

[0001] The present invention relates to the field of sulfur hexafluoride operation and maintenance technology, and in particular to a multifunctional SF6 and mixed gas density relay online calibration device, which is used for monitoring SF6 and mixed gas and for fault warning. Background Art

[0002] As an excellent insulating and arc-extinguishing gas, SF6 gas is widely used in the high-voltage field. The amount of SF6 gas in gas-insulated equipment is directly related to the insulation and arc-extinguishing performance. If gas-insulated electrical equipment leaks during operation and the SF6 gas content is lower than the safety threshold, it will have a significant impact on the safe and reliable operation of the electrical equipment. In actual application, gas density relays often suffer from oxidation of control contacts, jamming or damage to the mechanism, and decreased accuracy due to long-term inaction. When the SF6 gas content is lower than the safety threshold, it cannot be effectively monitored, seriously affecting the safe operation of the power grid. Relevant technical standards and specifications require: Regularly calibrate density relays operating on the grid.

[0003] At present, there are two ways to calibrate density relays. One is for electrical equipment that has not been remodeled for free disassembly calibration. To calibrate the density relays on such equipment, it is necessary to first shut down the power supply to the power equipment, then disassemble the density relays and send them to a qualified monitoring agency for calibration. After the calibration is qualified, they are installed and re-operated. This calibration method has the problems of cumbersome inspection, low efficiency, high cost, and power outage, which affects the operation efficiency of the power grid and the production and life of the people. The other is for electrical equipment that has been remodeled for free disassembly calibration. To calibrate the density relays on such equipment, the operation and maintenance personnel need to bring a density calibrator to the site to calibrate the density relays one by one. Compared with the first calibration method, this calibration method has greatly improved efficiency and cost, but the calibration process is greatly affected by the environment, and the calibration accuracy is easily affected. In addition, the greenhouse effect of SF6 gas is 23,500 times that of CO2. It is one of the six greenhouse gases clearly restricted by the United Nations Framework Convention on Climate Change. In the calibration process, SF6 gas will inevitably be discharged into the atmosphere, polluting the environment. At the same time, the free disassembly calibration device can calibrate a single type of gas and a single function. With the continuous advancement of the mixed gas transformation project, it can no longer meet the needs of the mixed gas scenario.

[0004] In the prior art, the Chinese authorized patent announcement number: CN 111443283 B discloses an online calibration device for a gas density relay and an online calibration method thereof. The online calibration device includes a gas density detection sensor, a normally open valve, a normally closed valve, a multi-way joint, a gas source generating unit, an online calibration contact signal sampling unit and an intelligent control unit; the gas pressure is increased or decreased by the normally open valve, the normally closed valve and the gas source generating unit, so that the gas density relay generates a contact signal action, and the contact signal action is transmitted to the intelligent control unit through the online calibration contact signal sampling unit. The intelligent control unit detects the contact signal action value and / or return value of the gas density relay according to the density value when the contact signal is actuated, and the calibration of the gas density relay can be completed without the maintenance personnel going to the site, thereby improving the reliability of the power grid, improving efficiency and reducing costs. At the same time, the gas source required for calibration does not need to be used for the calibration of the electrical equipment during the entire calibration process, but the gas source required for calibration is provided by the gas source generating unit, which is both environmentally friendly and safe and economical. Summary of the invention

[0005] The technical problem to be solved by the present invention is to address the deficiencies in the prior art and disclose a multifunctional SF6 and mixed gas density relay online calibration device and method, which solves the problem of SF6 and mixed gas monitoring and fault warning for operation and maintenance personnel.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: including a measurement module, a PLC chip, a control module, a voltage regulation module, an early warning module, an analysis module, a data storage module, a communication module and a display module;

[0007] The measurement module uses a variety of sensors to measure the pressure, temperature and decomposition product related data of SF6 and its mixed gas;

[0008] The PLC chip is used to receive the relevant data, perform data calculation on the relevant data, and then convert the processed data into control signals and send them to the control module and the voltage regulating module;

[0009] The control module receives the control signal and performs control actions on the density relay device;

[0010] The voltage regulating module receives the control signal to perform voltage regulating operation;

[0011] The early warning module monitors the relevant data and sends an alarm message to the display module and performs an early warning action if the relevant data is abnormal;

[0012] The analysis module conducts in-depth analysis on the relevant monitoring data accumulated over a long period of time, mines the potential rules and trends in the data, and generates a detailed monitoring report;

[0013] The data storage module classifies and stores the collected relevant data, calculation results, analysis data, decomposition product monitoring data, etc. according to time series and equipment identification;

[0014] The communication module uploads the data of the density relay device to the PLC chip and the data storage module through wireless communication;

[0015] The display module displays the relevant data of the density relay, the alarm information and the monitoring report to the operation and maintenance personnel.

[0016] Further:

[0017] The measuring module includes a pressure sensor, a temperature sensor and a decomposition product detection sensor;

[0018] The pressure sensor adopts a pressure sensor with an accuracy level of 0.01;

[0019] The temperature sensor adopts a platinum resistance temperature sensor;

[0020] The decomposition product detection sensor adopts an electrochemical sensor.

[0021] Further:

[0022] The PLC chip includes a pressure control unit and a data processing unit;

[0023] The pressure control unit controls the voltage increase or decrease when checking the contact action value and the switching difference of the density relay according to the mixed gas density relay verification procedure;

[0024] The data processing unit receives the real-time analog signals of the pressure sensor and the temperature sensor, and performs operational amplifier processing, performs AD conversion on the operational amplifier output signal to obtain a digital signal, processes the digital signal into a density value of the SF6 / N2 mixed gas at any temperature, and automatically converts it into a standard density value at 20°C. The standard density value is the final data processing result. At the same time, action instructions are sent to the voltage regulating module and the control module according to the data processing result.

[0025] Further:

[0026] The pressure regulating module includes a micro gas compressor, a micro vacuum pump, and a built-in air bag;

[0027] The micro gas compressor is used to dynamically adjust the air intake of the sealed cylinder when the system is in a pressure-increasing state, and control the micro compressor to continuously work to compress the built-in air bag; the micro vacuum pump is mainly used to dynamically adjust the air intake of the sealed cylinder when the system is in a pressure-increasing state, and control the micro vacuum pump to continuously work to expand the built-in air bag.

[0028] Further:

[0029] The electric control module includes an electric control valve;

[0030] The electric control valve is used for intelligently controlling and cutting off the circuit connection between the contacts of the density relay.

[0031] Further:

[0032] The early warning module includes a characteristic gas early warning unit and an audible and visual alarm unit;

[0033] The characteristic gas warning unit is used for online dynamic detection of the content of characteristic gases such as SO2, H2S, HF, CO, CF4 and C3F8 in the gas chamber, and provides effective data for the analysis module to perform fault trend warning.

[0034] The sound and light alarm unit includes a buzzer alarm and an indicator light. After receiving an alarm signal, the buzzer alarm emits a sound message and the indicator light flashes.

[0035] Further:

[0036] The monitoring report includes the device operation status assessment, fault warning, and maintenance recommendations.

[0037] Further:

[0038] The communication module adopts a mixed star and tree network mode of LoRa wireless communication;

[0039] There is no loop between any two nodes in the LoRa wireless communication network, and each link supports bidirectional transmission.

[0040] Further:

[0041] The LoRa wireless communication network is divided into four levels, namely, the first level is the background data monitoring platform, the second level is the secondary LoRa repeater, the third level is the primary LoRa repeater, and the fourth level is the LoRa wireless communication module;

[0042] The number of the secondary LoRa repeaters is 1 to n (n is a natural number), the number of the primary LoRa repeaters is 1 to m (m is a natural number), and the number of the LoRa wireless communication modules is 1 to j (j is a natural number).

[0043] Further:

[0044] The device performs the following steps:

[0045] Step 1: Data acquisition: using high-precision pressure sensors, temperature sensors and decomposition product detection sensors, real-time acquisition of relevant data on the pressure, temperature and decomposition products of SF6 and its mixed gas; at the same time, the PLC chip obtains the working status and output signal of the density relay;

[0046] Step 2: Signal preprocessing: The PLC chip filters the collected original analog signal to eliminate environmental noise and interference; amplifies and conditions the filtered signal to reach a standard range suitable for subsequent processing;

[0047] Step 3: Data calculation: Based on the collected pressure and temperature data, combined with the characteristic equation of the gas and the principle of thermodynamics, the actual pressure of the gas at 20°C is accurately calculated; considering the compressibility and thermal expansion of the gas, the calculation results are corrected and optimized; Density calculation: Based on the accurate pressure and temperature values, the density of SF6 and its mixed gas is calculated;

[0048] Step 4: Verification analysis: The analysis module performs verification analysis, and the analysis module compares and verifies the calculated density value with the value displayed by the density relay, and analyzes whether the deviation between the two is within the prescribed allowable range. If the deviation exceeds the range of 3%-5%, it is further determined that it is a fault factor of the density relay;

[0049] Step 5: Decomposition product monitoring: using the electrochemical sensor to perform qualitative and quantitative detection of decomposition products in SF6 and its mixed gas, and to monitor the types of decomposition products and changes in their concentrations in real time;

[0050] Step 6: Generate a fault warning report: The analysis module conducts in-depth analysis on the long-term accumulated monitoring data, mines the potential rules and trends in the data, and generates a detailed monitoring report, including equipment operation status evaluation, fault warning, maintenance suggestions, etc.;

[0051] Step 7: Data storage and management: The data storage module classifies and stores the collected raw data, calculation results, verification analysis data, and decomposition product monitoring data according to time series and equipment identification, and establishes a complete data management system;

[0052] Step 8: Fault diagnosis and alarm: When the density relay detects that the pressure value is abnormal, the density deviation is too large, or the concentration of the decomposition product exceeds the standard, the analysis module automatically performs fault diagnosis and analysis, the alarm module immediately sends out an audible and visual alarm signal, and transmits the alarm information to the operation and maintenance personnel in a timely manner through the communication module.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] By combining multi-sensor fusion and edge computing technology, the function of the calibrator is integrated into the density relay, so that the remote SF6 and mixed gas density relays have the function of a calibrator, so that the density relay can calibrate itself regularly during normal operation, and the calibration data is analyzed and diagnosed on the edge of the instrument; at the same time, the pressure and decomposition products of SF6 and its mixed gas are dynamically monitored to provide data for fault trend prediction. It can achieve manual maintenance-free when the equipment is not faulty, and accurately locate the equipment when it is faulty, and upload fault information through the communication network to actively inform the operation and maintenance personnel, making the operation and maintenance work simple and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a schematic diagram of the structure of each module of the present invention;

[0056] Figure 2 is a system block diagram of the device of the present invention;

[0057] Figure 3 This is a schematic diagram of the LoRa wireless communication network described in the present invention;

[0058] Figure 4 The figure is a flow chart of the steps of the method of the present invention.

[0059] Description of reference numerals:

[0060] 1-SF6 and its mixed gas electrical equipment; 2-SF6 and its mixed gas density relay; 3-SF6 and its mixed gas online calibration and pressure, decomposition product monitoring device; 4-signal line contact; 5-electric control valve; 6-pressure regulating module; 7-characteristic gas warning module, pressure sensor, temperature sensor, wireless transmission module integrated unit; 8-PLC chip. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] like Figure 1 As shown, it shows a schematic diagram of the structure of each module of the present invention, including: a measuring module, a PLC chip, a control module, a voltage regulating module, an early warning module, an analysis module, a data storage module, a communication module and a display module; the measuring module uses a variety of sensors to measure the pressure, temperature and decomposition product related data of SF6 and its mixed gas; the PLC chip is used to receive the related data, and perform data calculation and processing on the related data, and then convert the processed data into a control signal and send it to the control module and the voltage regulating module; the control module receives the control signal and controls the density relay device; the voltage regulating module receives the control signal and performs a voltage regulating operation; the early warning module monitors the related data, and if the related data is abnormal, sends an alarm message to the display module and performs an early warning action;

[0063] The sound and light alarm unit includes a buzzer alarm and an indicator light. After receiving an alarm signal, the buzzer alarm emits a sound message and the indicator light flashes.

[0064] The analysis module conducts in-depth analysis on the relevant monitoring data accumulated over a long period of time, explores the potential patterns and trends in the data, and generates a detailed monitoring report; the monitoring report includes the device operation status assessment, fault warning, and maintenance recommendations.

[0065] The data storage module classifies and stores the collected relevant data, calculation results, analysis data, decomposition product monitoring data, etc. according to time series and equipment identification; the communication module uploads the data of the density relay device to the PLC chip and the data storage module through wireless communication; the communication module adopts a mixed star and tree type of LoRa wireless communication networking; no loop is generated between any two nodes in the LoRa wireless communication networking, and each link supports bidirectional transmission.

[0066] The display module displays the relevant data of the density relay, the alarm information and the monitoring report to the operation and maintenance personnel.

[0067] Preferably,

[0068] The measuring module includes a pressure sensor, a temperature sensor and a decomposition product detection sensor;

[0069] The pressure sensor uses a pressure sensor with an accuracy level of 0.01. The pressure sensor is installed in the circuit. When the system is calibrated, the SF6 / N2 gas pressure acts on the surface of the elastic sensitive element in the pressure sensor, causing the elastic sensitive element to deform with the dynamic pressure, driving the resistance strain gauge to deform, and finally converting the strain into a 4-20mA analog signal that can be collected and processed.

[0070] The temperature sensor adopts a platinum resistance temperature sensor. When the system verifies the measured temperature, the platinum resistance temperature sensor and the density relay to be verified are placed at the same ambient temperature. The resistance value of the platinum resistance sensor changes with the temperature of the metal platinum. The changed resistance value can be converted into an electrical signal and transmitted to the data processing unit. The system converts the analog signal measured by the pressure sensor into a standard pressure value at 20°C according to the built-in temperature characteristic curve.

[0071] The decomposition product detection sensor adopts an electrochemical sensor; it performs qualitative and quantitative detection on the decomposition products in SF6 and its mixed gas, and monitors the type and concentration change of the decomposition products in real time.

[0072] Preferably, the PLC chip includes a pressure control unit and a data processing unit;

[0073] The pressure control unit controls the voltage increase or decrease action when checking the contact action value and the switching difference of the density relay according to the mixed gas density relay verification regulations; the pressure control unit selects to control the voltage increase / decrease speed to be no more than 5‰ of the relay range per second when checking the contact action value and the switching difference of the density relay according to the mixed gas density relay verification regulations, so as to avoid overshoot of the measured pressure signal. At the same time, the system is designed with a voltage increase / decrease speed in the non-contact action area to ensure the efficiency of density relay verification. The pressure control unit adopts a dual-speed voltage increase / decrease mode. When the pressure is increased / decreased toward the target voltage increase / decrease, the fast voltage increase / decrease mode is automatically selected, which can significantly improve the verification efficiency. When the pressure is close to the signal setting value, the steady speed voltage increase / decrease mode is selected to control the pressure fluctuation range to be less than 50% of the absolute value of the maximum allowable pressure error.

[0074] The data processing unit receives the real-time analog signals of the pressure sensor and the temperature sensor, performs operational amplification processing, performs AD conversion on the output signal of the operational amplifier to obtain a digital signal, processes the digital signal into a density value of the SF6 / N2 mixed gas at any temperature, and automatically converts it into a standard density value at 20°C. The standard density value is the final data processing result. At the same time, action instructions are sent to the voltage regulating module and the control module according to the data processing result.

[0075] Preferably, the pressure regulating module includes a micro gas compressor, a micro vacuum pump, and a built-in air bag;

[0076] The micro gas compressor is used to dynamically adjust the air intake of the sealed cylinder when the system is in a pressure-increasing state, and control the micro compressor to continuously work to compress the built-in air bag; the micro vacuum pump is mainly used to dynamically adjust the air intake of the sealed cylinder when the system is in a pressure-increasing state, and control the micro vacuum pump to continuously work to expand the built-in air bag;

[0077] Actual boosting process: When the system is in the boosting state, the air intake of the sealed cylinder is dynamically adjusted, and the micro compressor is controlled to continuously work to compress the built-in air bag, so that the calibration system is automatically boosted to the target pressure value;

[0078] The micro gas compressor is selected with a rated pressure of 11 bar according to the calibration range of the density relay. It has the advantages of dry, oil-free, low noise, low power consumption and small size. It does not require the addition of lubricating oil, has zero pollution to the working medium, and does not interfere with the gas analysis of the equipment. It can meet the calibration needs of the mixed gas density relay and significantly improves the calibration efficiency and accuracy compared to the traditional semi-automatic calibration mode.

[0079] Actual depressurization process: The micro vacuum pump is mainly used to dynamically adjust the air intake of the closed cylinder when the system calibration is in a depressurization state, and control the micro vacuum pump to continue working to expand the built-in air bag.

[0080] like Figure 2 As shown, it shows a system block diagram of the device of the present invention, the SF6 and its mixed gas electrical equipment 1 is connected to one end of the electric control valve 5, the other end of the electric control valve 5 is connected to the left end of the voltage regulating module 6, one end of the SF6 and its mixed gas density relay 2 is connected to the upper end of the voltage regulating module 6, the PLC chip 8 is connected to the lower end of the voltage regulating module 6, and the characteristic gas early warning unit, pressure sensor, temperature sensor, wireless transmission module integrated unit 7 are connected to the voltage regulating module;

[0081] The characteristic gas warning unit, pressure sensor, temperature sensor, wireless transmission module integrated unit 7 collect the pressure and temperature of the gas, and then send the collected data information to the PLC chip 8 for data processing and pressure control. The PLC chip 8 sends the processed structure to the electric control valve 5 and the pressure regulating module 6 to perform pressure regulation operation on the device. The electric control valve 5, the pressure regulating module 6, the characteristic gas warning unit, pressure sensor, temperature sensor, wireless transmission module integrated unit 7 and the PLC chip 8 together constitute the SF6 and its mixed gas online calibration and pressure, decomposition product monitoring device 3.

[0082] like Figure 3As shown, it shows the LoRa wireless communication networking of the present invention; the LoRa wireless communication networking is divided into four levels, namely, the first level is the background data monitoring platform, the second level is the secondary LoRa repeater, the third level is the primary LoRa repeater, and the fourth level is the LoRa wireless communication module;

[0083] The number of the secondary LoRa repeaters is 1 to n (n is a natural number), the number of the primary LoRa repeaters is 1 to m (m is a natural number), the number of the LoRa wireless communication modules is 1 to j (j is a natural number), and the LoRa wireless communication networking adopts a mixed star and tree network; the star network of the LoRa wireless communication networking has a simple structure, convenient connection, relatively easy management and maintenance, and strong scalability; it can also ensure that no loop is generated between any two nodes in the network, each link supports two-way transmission, the node expansion in the network is convenient and flexible, and it is convenient to find the link path.

[0084] like Figure 4 As shown, it shows that the specific implementation steps of the present invention are as follows:

[0085] Step 1: Data acquisition: using high-precision pressure sensors, temperature sensors and decomposition product detection sensors, real-time acquisition of relevant data on the pressure, temperature and decomposition products of SF6 and its mixed gas; at the same time, the PLC chip obtains the working status and output signal of the density relay;

[0086] Step 2: Signal preprocessing: The PLC chip filters the collected original analog signal to eliminate environmental noise and interference; amplifies and conditions the filtered signal to reach a standard range suitable for subsequent processing;

[0087] Step 3: Data calculation: Based on the collected pressure and temperature data, combined with the characteristic equation of the gas and the principle of thermodynamics, the actual pressure of the gas at 20°C is accurately calculated; considering the compressibility and thermal expansion of the gas, the calculation results are corrected and optimized; Density calculation: Based on the accurate pressure and temperature values, the density of SF6 and its mixed gas is calculated;

[0088] Step 4: Verification analysis: The analysis module performs verification analysis, and the analysis module compares and verifies the calculated density value with the value displayed by the density relay, and analyzes whether the deviation between the two is within the prescribed allowable range. If the deviation exceeds the range of 3%-5%, it is further determined that it is a fault factor of the density relay;

[0089] Step 5: Decomposition product monitoring: using the electrochemical sensor to perform qualitative and quantitative detection of decomposition products in SF6 and its mixed gas, and to monitor the types of decomposition products and changes in their concentrations in real time;

[0090] Step 6: Generate a fault warning report: The analysis module conducts in-depth analysis on the long-term accumulated monitoring data, mines the potential rules and trends in the data, and generates a detailed monitoring report, including equipment operation status evaluation, fault warning, maintenance suggestions, etc.;

[0091] Step 7: Data storage and management: The data storage module classifies and stores the collected raw data, calculation results, verification analysis data, and decomposition product monitoring data according to time series and equipment identification, and establishes a complete data management system;

[0092] Step 8: Fault diagnosis and alarm: When the density relay detects that the pressure value is abnormal, the density deviation is too large, or the concentration of the decomposition product exceeds the standard, the analysis module automatically performs fault diagnosis and analysis, the alarm module immediately sends out an audible and visual alarm signal, and transmits the alarm information to the operation and maintenance personnel in a timely manner through the communication module.

[0093] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Multifunctional SF6 and mixed gas density relay online calibration device, Features: It includes a measurement module, a PLC chip, a control module, a voltage regulation module, an early warning module, an analysis module, a data storage module, a communication module and a display module; The measuring module is electrically connected to the PLC chip, the control module is electrically connected to the PLC chip, the control module is electrically connected to the voltage regulating module, the early warning module is electrically connected to the PLC chip, the display module is electrically connected to the PLC chip, the data storage module is electrically connected to the PLC chip, the analysis module is electrically connected to the PLC chip, and the communication module is electrically connected to the PLC chip; The measurement module uses a variety of sensors to measure the pressure, temperature and decomposition product related data of SF6 and its mixed gas; The PLC chip is used to receive the relevant data, perform data calculation on the relevant data, and then convert the processed data into control signals and send them to the control module and the voltage regulating module; The control module receives the control signal and performs control actions on the density relay device; The voltage regulating module receives the control signal to perform voltage regulating operation; The early warning module monitors the relevant data and sends an alarm message to the display module and performs an early warning action if the relevant data is abnormal; The analysis module conducts in-depth analysis on the relevant monitoring data accumulated over a long period of time, mines the potential rules and trends in the data, and generates a detailed monitoring report; The data storage module classifies and stores the collected relevant data, calculation results, analysis data, decomposition product monitoring data, etc. according to time series and equipment identification; The communication module uploads the data of the density relay device to the PLC chip and the data storage module through wireless communication; The display module displays the relevant data of the density relay, the alarm information and the monitoring report to the operation and maintenance personnel.

2. The multifunctional SF6 and mixed gas density relay online calibration device according to claim 1, Features: The measuring module includes a pressure sensor, a temperature sensor and a decomposition product detection sensor; The pressure sensor adopts a pressure sensor with an accuracy level of 0.01; The temperature sensor adopts a platinum resistance temperature sensor; The decomposition product detection sensor adopts an electrochemical sensor.

3. The multifunctional SF6 and mixed gas density relay online calibration device according to claim 1, Features: The PLC chip includes a pressure control unit and a data processing unit; The pressure control unit controls the voltage increase or decrease when checking the contact action value and the switching difference of the density relay according to the mixed gas density relay verification procedure; The data processing unit receives the real-time analog signals of the pressure sensor and the temperature sensor, and performs operational amplifier processing, performs AD conversion on the operational amplifier output signal to obtain a digital signal, processes the digital signal into a density value of the SF6 / N2 mixed gas at any temperature, and automatically converts it into a standard density value at 20°C. The standard density value is the final data processing result. At the same time, action instructions are sent to the voltage regulating module and the control module according to the data processing result.

4. The multifunctional SF6 and mixed gas density relay online calibration device according to claim 1, Features: The pressure regulating module includes a micro gas compressor, a micro vacuum pump, and a built-in air bag; The micro gas compressor is used to dynamically adjust the air intake of the sealed cylinder when the system is in a pressure-increasing state, and control the micro compressor to continuously work to compress the built-in air bag; the micro vacuum pump is mainly used to dynamically adjust the air intake of the sealed cylinder when the system is in a pressure-increasing state, and control the micro vacuum pump to continuously work to expand the built-in air bag.

5. The multifunctional SF6 and mixed gas density relay online calibration device according to claim 1, Features: The electric control module includes an electric control valve; The electric control valve is used for intelligently controlling and cutting off the circuit connection between the contacts of the density relay.

6. The multifunctional SF6 and mixed gas density relay online calibration device according to claim 1, Features: The early warning module includes a characteristic gas early warning unit and an audible and visual alarm unit; The characteristic gas warning unit is used for online dynamic detection of the content of characteristic gases such as SO2, H2S, HF, CO, CF4 and C3F8 in the gas chamber, and provides effective data for the analysis module to perform fault trend warning. The sound and light alarm unit includes a buzzer alarm and an indicator light. After receiving an alarm signal, the buzzer alarm emits a sound message and the indicator light flashes.

7. The multifunctional SF6 and mixed gas density relay online calibration device according to claim 1, Features: The monitoring report includes the device operation status assessment, fault warning, and maintenance recommendations.

8. The multifunctional SF6 and mixed gas density relay online calibration device according to claim 1, Features: The communication module adopts a mixed star and tree network mode of LoRa wireless communication; There is no loop between any two nodes in the LoRa wireless communication network, and each link supports bidirectional transmission.

9. The multifunctional SF6 and mixed gas density relay online calibration device according to claim 8, Features: The LoRa wireless communication network is divided into four levels, namely, the first level is the background data monitoring platform, the second level is the secondary LoRa repeater, the third level is the primary LoRa repeater, and the fourth level is the LoRa wireless communication module; The number of the secondary LoRa repeaters is 1 to n (n is a natural number), the number of the primary LoRa repeaters is 1 to m (m is a natural number), and the number of the LoRa wireless communication modules is 1 to j (j is a natural number).

10. Online calibration method for multifunctional SF6 and mixed gas density relays, It is characterized in that The following steps are performed using the device as described in any one of claims 1 to 9: Step 1: Data acquisition: using high-precision pressure sensors, temperature sensors and decomposition product detection sensors, real-time acquisition of relevant data on the pressure, temperature and decomposition products of SF6 and its mixed gas; at the same time, the PLC chip obtains the working status and output signal of the density relay; Step 2: Signal preprocessing: The PLC chip filters the collected original analog signal to eliminate environmental noise and interference; Amplify and condition the filtered signal to bring it within a standard range suitable for subsequent processing; Step 3: Data calculation: Based on the collected pressure and temperature data, combined with the characteristic equation of the gas and the principle of thermodynamics, the actual pressure of the gas at 20°C is accurately calculated; considering the compressibility and thermal expansion of the gas, the calculation results are corrected and optimized; Density calculation: Based on the accurate pressure and temperature values, the density of SF6 and its mixed gas is calculated; Step 4: Verification analysis: The analysis module performs verification analysis, and the analysis module compares and verifies the calculated density value with the value displayed by the density relay, and analyzes whether the deviation between the two is within the prescribed allowable range. If the deviation exceeds the range of 3%-5%, it is further determined that it is a fault factor of the density relay; Step 5: Decomposition product monitoring: using the electrochemical sensor to perform qualitative and quantitative detection of decomposition products in SF6 and its mixed gas, and to monitor the types of decomposition products and changes in their concentrations in real time; Step 6: Generate a fault warning report: The analysis module conducts in-depth analysis on the long-term accumulated monitoring data, mines the potential rules and trends in the data, and generates a detailed monitoring report, including equipment operation status evaluation, fault warning, maintenance suggestions, etc.; Step 7: Data storage and management: The data storage module classifies and stores the collected raw data, calculation results, verification analysis data, and decomposition product monitoring data according to time series and equipment identification, and establishes a complete data management system; Step 8: Fault diagnosis and alarm: When the density relay detects that the pressure value is abnormal, the density deviation is too large, or the concentration of the decomposition product exceeds the standard, the analysis module automatically performs fault diagnosis and analysis, the alarm module immediately sends out an audible and visual alarm signal, and transmits the alarm information to the operation and maintenance personnel in a timely manner through the communication module.

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