Liquid level detection system and method of millimeter wave radar liquid level meter

Abstract

The invention discloses a liquid level detection system and method of a millimeter wave radar liquid level meter, and relates to the technical field of liquid level detection.The environment information and liquid information of a target detection scene are collected, and then a blind area alarm threshold value of the target detection scene at a detection time point is analyzed; according to the method, the detection scene is dynamically matched through the alarm threshold value, the detection reliability is ensured to the greatest extent, then the acquisition mode of the system is analyzed, and the detection data is obtained through analysis according to the output mode and the acquisition mode of the system; the problem that a single sensor is short in performance in a full-liquid-level detection interval is solved, meanwhile, the running state of the sensor is monitored, then fault recognition is conducted, a fault tolerance scheme is analyzed, and finally power supply classification is determined according to the output mode, the collection mode and the fault state of the system. Therefore, continuity and accuracy of detection data and fault tolerance of the system are guaranteed.

Description

Technical Field

[0001] This application relates to the field of liquid level detection technology, specifically to a liquid level detection system and method using a millimeter-wave radar liquid level gauge. Background Technology

[0002] Existing level gauges generally employ a single sensor solution. However, radar or ultrasonic sensors are susceptible to interference at close range or in high-echo environments, and submersible sensors suffer from blind spots or low signal-to-noise ratios at low levels. Therefore, a single solution cannot simultaneously achieve high accuracy and high reliability across the entire measurement range. Furthermore, in battery-powered scenarios, continuous sensor power consumption leads to high power consumption, making it difficult to meet the requirements of long-life applications. While dual-sensor redundancy solutions can improve reliability, without a sound switching logic and power management strategy, it remains difficult to achieve the comprehensive performance of "no blind spots, low power consumption, and strong robustness." Therefore, this application proposes a level detection system and method using millimeter-wave radar level gauges.

[0003] Existing technology, such as the invention application patent with announcement number CN118129864B, discloses a liquid level measurement method and system based on millimeter-wave radar, which relates to the field of liquid level measurement technology. It mainly solves the problems of low efficiency and inaccurate positioning in liquid level measurement. The liquid level measurement method based on millimeter-wave radar includes: setting the operating parameters and control strategy of the measurement system; the millimeter-wave radar emitting continuous electromagnetic wave signals; the millimeter-wave radar receiving and analyzing the reflected signals; calculating the liquid level height based on the electromagnetic wave propagation distance; outputting liquid level data and monitoring liquid level changes in real time; maintaining and optimizing the detection system; processing the radar signal through a signal matching algorithm to reduce interference from multipath effects; analyzing the processed data through a dynamic evaluation algorithm to improve measurement accuracy and resolution; and alerting the user to abnormal changes in liquid level through LED lights and an audible alarm, thus improving the liquid level measurement capability.

[0004] Existing technology, such as the invention patent application with publication number CN115540972A, discloses a novel low-power level gauge and low-power operation method for detecting liquid levels using millimeter-wave radar. This method employs a programmable low-power ARM processor as the signal processing chip. Leveraging the abundant wiring resources, reprogrammability, and high integration of ARM processors, and through the rational arrangement of the level gauges, the accuracy of distance detection can be significantly improved. The level gauge can operate intermittently, and the programmable nature of the ARM processor allows for power control of the processing and control module, enabling it to enter sleep and power-saving modes, thus significantly reducing the level gauge's power consumption. The power-saving and sleep mode control via the ARM processor achieves the beneficial effect of reduced power consumption, and the rational arrangement of the level gauges further improves the accuracy of distance detection.

[0005] The above-mentioned solutions have the following technical problems: 1. Current technology mainly monitors and analyzes the electromagnetic wave signals emitted by radar to monitor changes in liquid level. However, it does not take into account the large interference that radar sensors are subject to at close range or in high echo environments, which will lead to large errors in the monitored liquid level data. The current technology's neglect of this aspect results in the lack of accuracy and reliability of the liquid level data monitored by radar.

[0006] 2. Current technology does not take into account the problem of sensor failure during liquid level detection. When the radar sensor fails, there is no immediate response strategy, which will cause the liquid level data to be distorted and is not conducive to the long-term use of various detection devices. At the same time, the current technology uses the intermittent operation of the liquid level gauge and the programmable feature of the ARM processor to control the power supply to enter sleep and power saving mode, without taking into account that the intermittent operation of the liquid level gauge will reduce the accuracy of the liquid level data. Summary of the Invention

[0007] The purpose of this application is to provide a liquid level detection system and method for a millimeter-wave radar level gauge, which solves the problems existing in the background art.

[0008] To solve the above-mentioned technical problems, this application adopts the following technical solution: In the first aspect, this application provides a liquid level detection system and method for a millimeter-wave radar liquid level gauge, including: a data acquisition module: used to collect environmental information and liquid information of the target detection scene.

[0009] Acquisition Mode Analysis Module: This module analyzes the blind zone alarm threshold of the target detection scenario at the detection time point, and then analyzes the switching of the system output mode based on the blind zone alarm threshold. At the same time, it analyzes the system's acquisition mode, and thus obtains the detection data based on the system's output mode and acquisition mode.

[0010] Fault and power analysis module: Used to monitor the operating status of sensors, identify faults, analyze fault tolerance schemes, and determine power supply levels based on the system's output mode, acquisition mode, and fault status.

[0011] In a second aspect, this application provides a liquid level detection system and method for a millimeter-wave radar level gauge, comprising: Step 1, collecting environmental information and liquid information of the target detection scene.

[0012] Step 2: Analyze the blind zone alarm threshold of the target detection scenario at the detection time point, and then analyze the switching of the system output mode based on the blind zone alarm threshold. At the same time, analyze the system's acquisition mode, and then obtain the detection data based on the system's output mode and acquisition mode.

[0013] Step 3: Monitor the operating status of the sensors, identify faults, analyze fault tolerance schemes, and determine power supply levels based on the system's output mode, acquisition mode, and fault status.

[0014] The beneficial effects of this application are as follows: 1. The liquid level detection system and method of the millimeter-wave radar liquid level gauge provided by this application collects environmental information and liquid information of the target detection scene, and then analyzes the blind zone alarm threshold of the target detection scene at the detection time point. Then, based on the blind zone alarm threshold, the switching of the system output mode is analyzed. This application dynamically matches the detection scene with the alarm threshold, which maximizes the reliability of the detection. Then, the system's acquisition mode is analyzed, and the detection data is obtained based on the system's output mode and acquisition mode. This solves the performance shortcomings of a single sensor in the full liquid level detection range. At the same time, the operating status of the sensor is monitored, and fault identification and fault tolerance schemes are performed. Finally, the power supply level is determined according to the system's output mode, acquisition mode and fault status, thereby ensuring the continuity, accuracy and fault tolerance of the detection data.

[0015] 2. This application analyzes the blind zone alarm threshold of the target detection scene based on environmental and liquid information. Compared with the traditional threshold setting method, the blind zone alarm threshold output by the model can dynamically match the current detection scene, so that the threshold changes from a general estimated value to a scene-specific accurate value. The false alarm rate can be reduced to below 5%, which greatly ensures the reliability of the detection data.

[0016] 3. This application solves the performance limitations of a single sensor in the full liquid level detection range by matching different liquid level modes with thresholds and then selecting different sensors for liquid level detection. In the high liquid level mode, the stability advantage of the submersible sensor is brought into play, and in the low liquid level mode, the blind zone avoidance capability of the radar sensor is brought into play. Liquid level detection is achieved through dual sensors, thereby improving the accuracy of liquid level detection data.

[0017] 4. This application uses dual sensors to achieve liquid level detection. When one sensor suddenly fails, the system can automatically rely on the other sensor, avoiding system paralysis caused by the failure of a single sensor, ensuring the continuity of detection data, and improving the fault tolerance of the system. At the same time, by accurately matching the power supply requirements with the sensor failure mode and failure condition, energy consumption optimization is achieved. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the system structure connection of this application.

[0020] Figure 2 This is a schematic diagram of the radar sensor installation in this application.

[0021] Figure 3 This is a flowchart illustrating the steps involved in implementing the method described in this application. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Reference Figure 1 As shown, this application provides a liquid level detection system for a millimeter-wave radar level gauge in a first aspect, including the following modules: a data acquisition module: used to collect environmental information and liquid information of the target detection scene.

[0024] In a specific example, the process of collecting environmental and scene information of the target detection scene is as follows: the environmental information includes ambient temperature, ambient pressure, and concentration of air obstructions; the liquid information includes the dielectric constant of the liquid surface in the target detection scene and the amplitude of liquid surface fluctuation.

[0025] The ambient temperature, ambient pressure, and concentration of airborne obstructions in the target detection scene were collected by using a platinum resistance sensor, a pressure sensor, and an electrostatic dust sensor, respectively; the dielectric constant of the liquid in the target detection scene and the amplitude of liquid level fluctuation were collected by using a capacitive sensor and a pressure sensor array method, respectively.

[0026] It should be noted that air obstructions include dust, vapor, and mist in the air.

[0027] It should be noted that the pressure sensor array method is existing technology, so it will not be described in detail here.

[0028] Acquisition Mode Analysis Module: This module analyzes the blind zone alarm threshold of the target detection scenario at the detection time point, and then analyzes the switching of the system output mode based on the blind zone alarm threshold. At the same time, it analyzes the system's acquisition mode, and thus obtains the detection data based on the system's output mode and acquisition mode.

[0029] It should be noted that the liquid level detection system in this application is a liquid level detection system that can switch between radar liquid level gauges and submersible liquid level gauges.

[0030] It should be noted that the output modes include main output and standby output; the detection modes include air level detection and liquid level detection.

[0031] In a specific example, the blind zone alarm threshold of the target detection scenario at the analysis detection time point is analyzed as follows: First, the standard liquid level range of the submersible sensor is obtained. Several known liquid level points are set within the standard liquid level range, and environmental and liquid information are randomly configured for each known liquid level point to obtain each test scenario. The submersible sensor is used to detect the liquid level in each test scenario to obtain the liquid level detection data of each test scenario. After preprocessing the environmental information, scenario information, actual liquid level, and detected liquid level of each test scenario, the data is substituted into the gradient boosting tree model. The model is trained and verified with the constraint that the coverage rate of the predicted blind zone over the actual blind zone is greater than 96%, and the decision model of the blind zone alarm threshold of the submersible sensor is obtained.

[0032] It should be noted that when the submersible sensor has multiple standard liquid level ranges, each standard liquid level range is tested.

[0033] It should be noted that each test scenario should be repeated at least 3 times to avoid errors in the test results.

[0034] It should be noted that the preprocessing includes continuous feature normalization, discrete feature encoding, and dataset partitioning. Among these, continuous feature normalization, discrete feature encoding, and dataset partitioning are existing technologies, so they will not be described in detail.

[0035] In a specific example, the switching of the output mode of the blind zone alarm threshold analysis system is carried out as follows: First, the environmental information and liquid information of the target detection scene at the detection time point are collected. The environmental information and liquid information of the target detection scene at the detection time point are input into the blind zone alarm threshold decision model to obtain the blind zone alarm threshold at the detection time point.

[0036] Then, the submersible liquid level value of the target detection scene is collected by the submersible sensor at the detection time point. The submersible liquid level value is compared with the blind zone alarm threshold. If the submersible liquid level value is greater than the blind zone alarm threshold, it is determined to be a high liquid level mode; otherwise, if the submersible liquid level value is less than or equal to the blind zone alarm threshold, it is determined to be a low liquid level mode.

[0037] For the high liquid level mode, the liquid level value collected by the submersible sensor is used as the main output; for the low liquid level mode, the radar liquid level value collected by the radar sensor is used as the main output.

[0038] It should be noted that during the detection process, if a sensor fails, the system will automatically switch to another sensor for liquid level detection.

[0039] In a specific example, the acquisition mode of the analysis system and the specific analysis process are as follows: First, the preset zero point and reference depth of the target detection scene are determined. When the preset zero point is the liquid surface of the target detection scene and the reference depth is 0, the system is adjusted to the air height acquisition mode, and the main output is the distance from the sensor to the liquid surface, which is recorded as the air height value.

[0040] When the preset zero point is the bottom of the container in the target detection scene and the reference depth is greater than 0, the system is adjusted to the liquid level acquisition mode. The main output is the liquid level height of the target detection scene, which is recorded as the liquid level value. The liquid level value needs to be calculated in combination with the reference depth and the sensor installation distance, and is compensated by the installation distance of the external sensor.

[0041] It should be noted that the reference depth is the distance from the liquid surface to the preset zero point.

[0042] It should be noted that data compensation using external sensors includes compensation for near-field blind zones and compensation for long-term error drift of the detection equipment. For example, radar sensors have near-field blind zones. When the liquid surface approaches the sensor, the radar sensor cannot accurately measure the air height. In this case, an external capacitive proximity sensor is needed. When the liquid surface enters the blind zone, its data is used to correct the blind zone error of the radar sensor. For example, if the radar sensor measures an air height of 0.15m, and the external capacitive sensor confirms the liquid level as 4.85m, combined with a reference depth of 5m, the radar sensor's air height is corrected to 0.15m. Another example is that after long-term use, the radar chip of the radar sensor may experience parameter drift, causing the measured value to gradually deviate from the true value. In this case, an external high-precision calibration sensor is needed. The external calibration data is used as a reference value to correct the drift error of the main sensor. For example, if the calibrated liquid level is 3.0m, and the main sensor displays 2.98m, then an error of 0.02m is automatically compensated. The above examples are only illustrative examples, and the specific data compensation is determined according to the actual detection situation of the target detection scenario.

[0043] Reference Figure 2As shown, in a specific example, the detection data is analyzed based on the system's output mode and acquisition mode. The specific analysis process is as follows: In the air-height acquisition mode, the main output of the high liquid level mode is: Eh = EXT_SENSOR_DISTANCE + distance - level_2v5_val; the main output of the low liquid level mode is: Eh = radar_val + distance; in the liquid level acquisition mode, the main output of the high liquid level mode is: H = well_depth - distance - EXT_SENSOR_DISTANCE + level_2v5_val; the main output of the low liquid level mode is: H = well_depth - distance - radar_val; where Eh is the air-height, H is the liquid level, EXT_SENSOR_DISTANCE is the distance between the two probes of the radar sensor, where the distance between the two probes of the radar sensor is 1 meter, distance is the installation distance between the radar sensor and the ground, level_2v5_val is the liquid level value of the submersible, well_depth is the well depth, and radar_val is the liquid level value of the radar sensor.

[0044] It should be noted that, for example, when well_depth=0mm, distance=1000mm, and the blind zone alarm threshold is 300mm, the system is in air-height acquisition mode, and the main output uses the radar sensor level value to ensure low level resolution; when well_depth=8000mm, distance=500mm, and the blind zone alarm threshold is 500mm, the system is in level acquisition mode, and the main output uses the radar sensor level value at low levels and the submersible sensor level value at high levels.

[0045] Fault and power analysis module: Used to monitor the operating status of sensors, identify faults, analyze fault tolerance schemes, and determine power supply levels based on the system's output mode, acquisition mode, and fault status.

[0046] In a specific example, the monitoring of the sensor's operating status and subsequent fault identification process is as follows: For an immersion sensor, the AD value, signal line voltage, and signal line current of the immersion sensor are monitored. The AD value is compared with a set standard range for AD values ​​to obtain the duration of abnormal AD values. The duration of abnormal AD values ​​is compared with a set anti-shake threshold to determine if the immersion sensor has an AD fault. Simultaneously, the signal line voltage and signal line current of the immersion sensor are compared with the corresponding voltage and current fluctuation ranges to determine if the immersion sensor has a cable fault. When an immersion sensor fault is detected, the system marks it as a ret1 fault.

[0047] It should be noted that the standard range of AD values, the anti-shake threshold, and the voltage and current fluctuation ranges were all obtained by consulting the user manual of the submersible sensor.

[0048] For radar sensors, the system monitors the data response time of the radar sensor to the host and compares it with the set data response time threshold to determine the communication failure of the radar sensor. At the same time, the system monitors the number of data requests from the host to the radar sensor and compares the number of requests with the set number of requests threshold to determine the data response failure of the radar sensor. When a radar sensor failure is detected, the system marks it as a ret2 failure.

[0049] It should be noted that when the host sends a data request to the radar sensor but the radar sensor does not respond, the host will send a data request to the radar sensor again. When the number of data requests exceeds the set request number threshold, it indicates that the radar sensor is faulty.

[0050] It should be noted that the data response time threshold and the request count threshold were obtained by consulting the radar sensor's user manual.

[0051] In a specific example, the fault tolerance scheme is analyzed as follows: When the system is marked as ret1 abnormal, the level_2v5_val in the high liquid level main output formula is updated to e_level_2v5_val in both the air-to-high liquid level acquisition mode and the liquid level acquisition mode. Here, e_level_2v5_val is the average level_2v5_val of the 20 minutes before the fault time point. The low liquid level main output directly disables the data from the submersible sensor.

[0052] When the system is flagged as ret2 abnormal, the radar sensor is disabled, and an immersion sensor is used to measure the liquid level in the target detection scenario.

[0053] When the system is marked as ret1 and ret2 faults, the system locks the last detected data before the fault occurred as the current output value and immediately issues an alarm.

[0054] In a specific example, the process of determining the power supply level based on the system's output mode, acquisition mode, and fault status is as follows: when the system is in a high liquid level mode, the first-level power supply mode is triggered; when the system is in a low liquid level mode, the second-level power supply mode is triggered; when the system is marked as ret1 or ret2 fault, the third-level power supply mode is triggered.

[0055] It should be noted that the total power consumption of the first-level power supply mode is 15-20W, the total power consumption of the second-level power supply mode is 8-12W, and the total power consumption of the third-level power supply mode is less than 3W.

[0056] It should be noted that immersion sensors require a 150ms warm-up before use, while radar sensors require a 500ms warm-up before use.

[0057] It should be noted that the liquid level detection system mentioned in this application includes hardware and software components. The hardware component includes an MCU, power supply, ADC, and sensors, while the software component includes an application layer, sensor processing layer, HAL, and driver layer.

[0058] It should be noted that the target detection scenarios include wells, reservoirs, and tanks. For example, when detecting the liquid level in a reservoir, the environment is complex due to the wide range of liquid level changes. A practical dual-sensor design can effectively improve the reliability of the system.

[0059] It should also be noted that when installing sensors, radar sensors need to be installed vertically to avoid tilting, and there should be no obstructions within 1m of the radar sensor antenna. At the same time, IP67 protection should be used to adapt to harsh environments. When installing submersible sensors, it is necessary to ensure that there is still sufficient immersion depth at the lowest liquid level, and a special bracket should be used to prevent swaying.

[0060] Reference Figure 3 As shown, this application provides a liquid level detection method for a millimeter-wave radar level gauge in a second aspect, including the following steps: Step 1, collecting environmental information and liquid information of the target detection scene.

[0061] Step 2: Analyze the blind zone alarm threshold of the target detection scenario at the detection time point, and then analyze the switching of the system output mode based on the blind zone alarm threshold. At the same time, analyze the system's acquisition mode, and then obtain the detection data based on the system's output mode and acquisition mode.

[0062] Step 3: Monitor the operating status of the sensors, identify faults, analyze fault tolerance schemes, and determine power supply levels based on the system's output mode, acquisition mode, and fault status.

[0063] This application provides a liquid level detection system and method for a millimeter-wave radar level gauge. By collecting environmental and liquid information from the target detection scene, it analyzes the blind zone alarm threshold of the target detection scene at the detection time point. Based on the blind zone alarm threshold, it analyzes the switching of the system's output mode. This application dynamically matches the detection scene with the alarm threshold, maximizing the reliability of the detection. It then analyzes the system's acquisition mode, obtaining detection data based on the system's output and acquisition modes. This solves the performance limitations of a single sensor across the entire liquid level detection range. Simultaneously, it monitors the sensor's operating status, enabling fault identification and analysis of fault tolerance schemes. Finally, it determines the power supply level based on the system's output mode, acquisition mode, and fault status, thereby ensuring the continuity, accuracy, and fault tolerance of the detection data.

[0064] The above content is merely an example and illustration of the concept of this application. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined in this application, they should all fall within the protection scope of this application.

Claims

1. A liquid level detection system of a millimeter wave radar liquid level meter, characterized by, Comprise: Data acquisition module: for collecting the environmental information and liquid information of the target detection scene; Collecting mode analysis module: for analyzing the blind area alarm threshold of the target detection scene at the detection time point, and then analyzing the switching of the system output mode according to the blind area alarm threshold, and analyzing the collection mode of the system, so as to analyze the detection data according to the output mode and collection mode of the system; Fault and power analysis module: for monitoring the running state of the sensor, and then identifying the fault, analyzing the fault tolerance scheme, and determining the power supply classification according to the output mode, collection mode and fault state of the system.

2. The liquid level detection system of a millimeter wave radar liquid level meter according to claim 1, characterized by, The environmental information and scene information of the target detection scene are collected, and the specific process is as follows: The environmental information includes environmental temperature, environmental pressure and air shielding concentration; the liquid information includes the medium dielectric constant and liquid surface fluctuation amplitude of the target detection scene liquid surface; The environmental temperature, environmental pressure and air shielding concentration of the target detection scene are collected by using platinum resistance sensor, pressure group pressure sensor and electrostatic induction dust sensor respectively; the medium dielectric constant and liquid surface fluctuation amplitude of the target detection scene liquid are collected by using capacitive sensor and pressure sensor array method respectively.

3. The liquid level detection system of a millimeter wave radar liquid level meter according to claim 2, characterized by, The blind area alarm threshold of the target detection scene at the detection time point is analyzed, and the specific analysis process is as follows: First, the standard liquid level range interval of the input sensor is obtained, a plurality of known liquid level points are set in the standard liquid level range interval, and the environmental information and liquid information of each known liquid level point are randomly configured to obtain each test scene, the input sensor is used to detect the liquid level of each test scene to obtain the liquid level detection data of each test scene, and after the environmental information, scene information, actual liquid level and detection liquid level of each test scene are pretreated, they are substituted into the gradient boosting tree model to predict that the coverage rate of the blind area to the actual blind area is greater than 96%, the model is trained and verified, and the blind area alarm threshold decision model of the input sensor is obtained.

4. The liquid level detection system of a millimeter wave radar liquid level meter according to claim 3, characterized by, The switching of the system output mode according to the blind area alarm threshold is analyzed, and the specific process is as follows: First, the environmental information and liquid information of the target detection scene at the detection time point are collected, and the environmental information and liquid information of the target detection scene at the detection time point are input into the blind area alarm threshold decision model to obtain the blind area alarm threshold at the detection time point; Then, the input liquid level value of the target detection scene at the detection time point is collected by the input sensor, and the input liquid level value is compared with the blind area alarm threshold. If the input liquid level value is greater than the blind area alarm threshold, it is determined as high liquid level mode; otherwise, if the input liquid level value is less than or equal to the blind area alarm threshold, it is determined as low liquid level mode; For high liquid level mode, the input liquid level value collected by the input sensor is used as the main output; for low liquid level mode, the radar liquid level value collected by the radar sensor is used as the main output.

5. The liquid level detection system of a millimeter wave radar liquid level meter according to claim 4, characterized by, The collection mode of the system is analyzed, and the specific analysis process is as follows: First, the preset zero point and reference depth of the target detection scene are determined. When the preset zero point is the liquid surface of the target detection scene and the reference depth is 0, the system is adjusted to the empty high collection mode, and the main output is the distance from the sensor to the liquid surface, which is recorded as the empty high value; When the preset zero point is the bottom of the container of the target detection scene, and the reference depth is greater than 0, the system is adjusted to the liquid level collection mode, and the main output is the liquid level height of the target detection scene, which is recorded as a liquid level value, wherein the liquid level value needs to be calculated in combination with the reference depth and the sensor installation distance, and is compensated through the external sensor installation distance.

6. The liquid level detection system of a millimeter wave radar liquid level meter according to claim 5, wherein The detection data is analyzed according to the output mode and the collection mode of the system, and the specific analysis process is as follows: In the empty height collection mode, the main output of the high liquid level mode is Eh=EXT_SENSOR_DISTANCE+distance-level_2v5_val, and the main output of the low liquid level mode is Eh=radar_val+distance; in the liquid level collection mode, the main output of the high liquid level mode is H=well_depth-distance-EXT_SENSOR_DISTANCE+level_2v5_val, and the main output of the low liquid level is H=well_depth-distance-radar_val; wherein Eh is the empty height, H is the liquid level, EXT_SENSOR_DISTANCE is the distance between the two probes of the radar sensor, wherein the distance between the two probes of the radar sensor is 1 meter, distance is the installation distance of the radar sensor from the ground, level_2v5_val is the inserted liquid level value, well_depth is the well depth, and radar_val is the radar sensor liquid level value.

7. The liquid level detection system of a millimeter wave radar liquid level meter according to claim 6, characterized by, The running state of the monitoring sensor is monitored, and then fault identification is performed, and the specific process is as follows: For the inserted sensor, the AD value, the signal line voltage and the signal line current of the inserted sensor are monitored, the AD value is compared with the set AD value standard interval, and then the duration of the abnormal AD value is obtained, the duration of the abnormal AD value is compared with the set anti-shake threshold, so as to judge the AD fault of the inserted sensor; at the same time, the signal line voltage and the signal line current of the inserted sensor are compared with the corresponding voltage and current fluctuation interval, so as to judge the cable fault of the inserted sensor; when the inserted sensor fault is monitored, the system is marked as ret1 fault; For the radar sensor, the data response time of the radar sensor to the host is monitored, the data response time is compared with the set data response time threshold, so as to judge the communication fault of the radar sensor; at the same time, the data request times of the host to the radar sensor are monitored, the request times are compared with the set request times threshold, so as to judge the data response fault of the radar sensor; when the radar sensor fault is monitored, the system is marked as ret2 fault.

8. The liquid level detection system of a millimeter wave radar liquid level meter according to claim 7, characterized by, The fault tolerance scheme is analyzed, and the specific analysis process is as follows: When the system is marked as ret1 abnormal, the level_2v5_val in the high liquid level main output formula in the empty high collection mode and the liquid level collection mode is updated to e_level_2v5_val, wherein e_level_2v5_val is the average value of level_2v5_val in the last 20 minutes before the fault time point, and the low liquid level main output directly stops using the input sensor data; When the system is marked as ret2 abnormal, the radar sensor is stopped, and the input sensor is used for liquid level measurement in the target detection scene; When the system is marked as ret1 and ret2 faults, the system locks the last detected data before the fault as the current output value, and immediately prompts an alarm.

9. The liquid level detection system of a millimeter wave radar liquid level meter according to claim 8, characterized by, The power supply classification is determined according to the output mode, collection mode and fault state of the system, and the specific process is as follows: When the system is in a high liquid level mode, a first power supply mode is triggered; when the system is in a low liquid level mode, a second power supply mode is triggered; when the system is marked as ret1 or ret2 fault, a third power supply mode is triggered.

10. A method of liquid level detection by a millimeter wave radar liquid level gauge, performed by a liquid level detection system using the millimeter wave radar liquid level gauge according to any one of claims 1 to 9, characterized by, It includes: Step one, collecting the environmental information and liquid information of the target detection scene; Step two, analyzing the blind area alarm threshold of the target detection scene at the detection time point, and then analyzing the switching of the system output mode according to the blind area alarm threshold, and analyzing the collection mode of the system, so as to obtain the detection data according to the output mode and the collection mode of the system; Step three, monitoring the running state of the sensor, and then identifying the fault, analyzing the fault tolerance scheme, and determining the power supply classification according to the output mode, collection mode and fault state of the system.

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