CN117147008A - Low-temperature sensor health state self-diagnosis method and system - Google Patents
Low-temperature sensor health state self-diagnosis method and system Download PDFInfo
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- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
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Abstract
The invention relates to a low-temperature sensor health state self-diagnosis method and system, and belongs to the field of low-temperature sensor design and intelligent self-diagnosis algorithms. N test areas are arranged in the liquid cargo tank insulation space, at least one low-temperature sensor is arranged in each test area, temperature data of the N test areas are obtained through the low-temperature sensors, whether the liquid cargo tank leaks or not is judged according to the temperature data in each test area, when the current liquid cargo tank is in a condition of no leakage, temperature data values of two test points corresponding to the low-temperature sensors in each test area are checked mutually, and diagnosis is conducted on the low-temperature sensors through checking errors; when the current cargo tank is in a leakage condition, a leakage temperature distribution cloud chart is constructed by taking a leakage test area as a circle center, and the low-temperature sensor is diagnosed according to the degree of deviation of temperature data of each test area from the temperature distribution cloud chart.
Description
Technical Field
The invention relates to a low-temperature sensor health state self-diagnosis method and system, and belongs to the field of low-temperature sensor design and intelligent self-diagnosis algorithms.
Background
At present, with the continuous expansion of energy demand, natural gas is one of the main energy sources used in various countries. Current vehicles for transporting natural gas include LNG ships (LNG carriers), LNG-dedicated vehicles (transport vehicles using ultra-low temperature medium storage tanks), etc., wherein LNG carriers are dedicated vessels for transporting liquefied gas at low temperatures of-163 degrees celsius, and are known as "marine super-refrigerated vehicles". When LNG cargo tank ship normally sails, through arranging a large amount of temperature monitoring points at cargo tank insulation space and outside cabin piping for the temperature change condition of real-time supervision cargo tank to this judges its storage state, once the system monitors the temperature anomaly, can send the warning immediately, in time discovers and reveal and handle cargo tank as required. The cargo tank of the LNG ship is of a self-supporting type and a film type special structure, the low-temperature sensor for detecting temperature is arranged in an insulation space of the cargo tank, once the cargo tank is arranged, the low-temperature sensor cannot be removed, the cargo tank cannot have the same service life as the ship, accurate monitoring is guaranteed, but after the low-temperature sensor positioned in the insulation space works for a long time, the problems that measured data are inaccurate, temperature data cannot be output and the like occur, and the reliability of the detected data is further affected.
Disclosure of Invention
The invention aims to provide a low-temperature sensor health state self-diagnosis method and system, which are used for solving the problems that the measured data is inaccurate and the reliability of a temperature measurement system is affected due to the failure of a low-temperature sensor.
In order to achieve the above object, the present invention provides a method comprising:
the invention discloses a self-diagnosis method for the health state of a low-temperature sensor, which comprises the following steps:
1) Setting N test areas in the liquid cargo tank insulation space, wherein at least one low-temperature sensor is arranged in each test area, acquiring temperature data of the N test areas through the low-temperature sensors, judging whether the liquid cargo tank leaks according to the temperature data in each test area, and each low-temperature sensor correspondingly comprises at least two test points;
2) When the current cargo tank is in a leakage-free condition, checking temperature data values of two test points corresponding to the low-temperature sensors in each test area, if the checking errors of the two corresponding test points are smaller than or equal to a first set temperature value and all output temperature information, the corresponding low-temperature sensors work normally, otherwise, the checking errors exceed the first set temperature value and/or the low-temperature sensors corresponding to the test areas without uploading the temperature information are in a fault state;
3) When the current cargo tank is in a leakage condition, a leakage temperature distribution cloud chart based on measured temperature data is built by taking a leakage test area as a circle center, whether the temperature data value of each test area deviates from the leakage temperature distribution cloud chart and exceeds a second set temperature value is judged, if so, the low temperature sensor corresponding to the test area is in a fault state, and otherwise, the low temperature sensor is in a normal working state.
The beneficial effects are that: according to the self-diagnosis method for the health state of the low-temperature sensor, when the health state of the low-temperature sensor is diagnosed, in order to avoid inaccurate diagnosis results of the low-temperature sensor caused by leakage of the cargo tank, two conditions are fully considered, different diagnosis schemes are made according to the two conditions, the health state of the low-temperature sensor is further diagnosed on the basis of determining the working condition of the low-temperature sensor, and if the current cargo tank is in the normal condition without leakage, the health state of the low-temperature sensor can be diagnosed by checking between two test points corresponding to the low-temperature sensor, and whether temperature information is output or not. When the current cargo tank is in a leakage working condition, a leakage temperature distribution cloud chart is constructed, and then the deviation degree of the temperature of each test area and the distribution cloud chart is used for judging, so that the health state of the low-temperature sensor is diagnosed. According to the method, a mathematical model is not required to be established in advance, the real-time fault can be estimated, the method is closer to the actual working condition, external signal access is not required, the time required by fault diagnosis is short, and the reliability of the low-temperature sensor is greatly improved.
Further, when the low-temperature sensor is in a fault state, comparing the temperature data of all the test points of each test area, determining the test points and the number of the fault test points in the fault test area according to the comparison result, judging whether the fault test points have temperature data output, and enabling the fault test points outputting the temperature data to enter a correction mode, otherwise, locking the fault test points not outputting the temperature data into an isolation state, and replacing the fault test points with adjacent test points in the same test area.
The beneficial effects are that: the method also comprises the step of further judging the low-temperature sensor with faults, judging whether the temperature data output exists in the test point where the low-temperature sensor with faults exists, if so, indicating that the faults possibly exist as the problems of inaccurate temperature data of the sensor, and the like, and further correcting and removing the faults, if not, indicating that the faults occur in the sensing part of the sensor, isolating the sensing part of the fault test point, and taking over the test work of the test point by the adjacent test points in the same test area. According to the method, a mathematical model is not required to be established, diagnosis of the low-temperature sensor is more detailed, and a fault evaluation result is more accurate.
Further, the correction mode is: when the number of fault test points in the test area is smaller than the number threshold value, the test area is used as a fault group, a temperature difference value is calculated according to the temperature value of the fault test points in the fault group and the temperature average value of other test points in the fault group, the temperature data of the fault test points are corrected by utilizing the temperature difference value, the corrected data are used for verification, if the verification result accords with the temperature measurement precision condition of the cargo tank, the test points are in a normal working state, otherwise, the test points are locked into an isolation state;
when the number of the fault test points in the test area is not smaller than the number threshold value, the test area symmetrical to the fault test area and the fault test area are used as a fault group, a temperature difference value is calculated according to the temperature value of the fault test area and the temperature values of other test points in the corresponding fault group, the temperature difference value is utilized to correct the fault test point, the corrected temperature data is checked, if the checking result accords with the insulation space temperature measurement precision condition, the test point is in a normal working state, and otherwise, the test point is locked into an isolation state.
The beneficial effects are that: the correction of the fault test points is divided into two cases, the number of the fault test points in the test area is determined, when the number of the fault test points is small, the correction can be completed by adopting the temperature data in the same test area, and when the number of the fault test points is large, the fault test points are corrected by depending on the temperature data of the test area with the temperature similar to that of the area where the fault test points are positioned, so that the correction accuracy is improved.
Further, the temperature difference when the number of fault test points in the test area is less than the number threshold is: the average temperature difference value of the fault test point in the current first set period is the average value of the difference values obtained by calculating the temperature value of the fault point and the average value of the temperatures of other test points in the fault group in the first set period;
the temperature difference value when the number of the fault test points in the test area is not smaller than the number threshold value is as follows: and the average temperature difference value of the fault test point in the second set period is the average value of the difference values obtained by calculating the temperature value of the fault point and the average value of the temperatures of other test points in the fault group in the second set period.
Further, the mode of judging whether the cargo tank leaks is as follows: if the temperature of the test points in the test area is lower than the third temperature threshold value and the number of the test points lower than the third temperature threshold value is above a set value, judging that the test area is in a leakage condition, otherwise, judging that the test area is in a non-leakage condition.
The beneficial effects are that: because the low-temperature sensor is positioned in the insulation space of the cargo tank, if the cargo tank leaks, the temperatures of the insulation space leakage points in other spaces have larger difference, so when the health state of the low-temperature sensor is diagnosed, in order to avoid inaccurate diagnosis results of the low-temperature sensor caused by the leakage of the cargo tank, the invention fully considers two conditions, and creates different diagnosis schemes according to the two conditions.
Further, the sensing part of the low-temperature sensor adopts a twin platinum resistor.
The beneficial effects are that: the sensing part of the low-temperature sensor adopts a twin platinum resistor, two test points can be arranged at the same position, and the health state of the low-temperature sensor is further accurately determined through mutual verification between the two test points.
The invention relates to a low-temperature sensor health state self-diagnosis system, which comprises N test areas arranged in an insulation space of a cargo tank of a ship, wherein each test area is provided with at least one low-temperature sensor, and an induction end of the low-temperature sensor is connected with a processing end through a lead wire; the processing end comprises a direct current resistance measurement module, wherein the direct current resistance measurement module is used for converting data acquired by the sensing end into temperature data and uploading the temperature data, and the system further comprises a temperature measurement module which is in communication connection with the processing end of each low-temperature sensor and is used for receiving the temperature data uploaded by each low-temperature sensor and processing the temperature data so as to realize the low-temperature sensor health state self-diagnosis method.
The beneficial effects are that: the low-temperature sensor health state self-diagnosis system is simple in arrangement, comprises N test areas arranged in an insulation space of a cargo tank of a ship, each test area is provided with at least one low-temperature sensor, temperature data of two test points measured by the low-temperature sensor are uploaded to a temperature measurement module of the system, the temperature measurement module receives all the temperature data of each test area, and the low-temperature sensor health state self-diagnosis method is realized according to the temperature data, a mathematical model is not required to be established in advance, the system can evaluate faults occurring in real time, is closer to actual working conditions, external signal access is not required, the time required for fault diagnosis is short, and the reliability of the low-temperature sensor is greatly improved.
Further, the sensing end of the low-temperature sensor adopts a twin platinum resistor.
The beneficial effects are that: the sensing part of the low-temperature sensor adopts a twin platinum resistor, two test points can be arranged at the same position, and the health state of the low-temperature sensor is further accurately determined through mutual verification between the two test points.
Further, the direct current resistance measurement module comprises an excitation constant current power supply, a reference resistor, an impedance amplification circuit and an AD acquisition circuit, wherein the excitation constant current power supply is connected to the impedance amplification circuit through the reference resistor, the impedance amplification circuit is connected with the AD acquisition circuit, the excitation constant current power supply and the reference resistor are used for converting a resistance value acquired by an induction end into a voltage value, the impedance amplification circuit is used for acquiring the converted voltage value and transmitting the acquired voltage value to the AD acquisition circuit, and the AD acquisition circuit is used for converting the acquired voltage value into temperature data and uploading the temperature data to the temperature measurement module.
Further, the lead adopts an insulated five-core shielding wire, the induction end is connected to the processing end through four cores of the shielding wire, and the fifth core of the shielding wire is used for grounding.
The beneficial effects are that: the lead wire adopts insulating five-core shielding wire, satisfies the requirement of tolerating low temperature, and the sensing end passes through four cores of shielding wire are connected to the processing end, have avoided the influence of lead wire to temperature measurement accuracy through this connected mode, and shielding wire's fifth core is used for ground connection, plays the shielding effect and prevents insulation failure to interfering signal.
Drawings
Fig. 1 is a schematic diagram of a measurement point of an insulation space low-temperature sensor of an LNG ship cargo tank according to an embodiment of the present invention;
FIG. 2 is a flowchart of a self-diagnosis workflow of the health status of a low-temperature sensor according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a temperature field under a leakage condition according to an embodiment of the present invention;
FIG. 4 is a flow chart of the online self-compensating self-calibration operation of the low-temperature sensor according to the embodiment of the invention.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings.
Embodiment of the self-diagnosis method for the health state of the low-temperature sensor:
the method for self-diagnosing the health state of the low-temperature sensor shown in fig. 2 comprises the steps of firstly, respectively and simultaneously acquiring temperature data of each test area by the low-temperature sensor arranged in each test area, judging whether a cargo tank leaks according to the temperature data, judging whether the low-temperature sensor fails according to mutual verification between at least two test points corresponding to the low-temperature sensor and whether data output exists under the condition that the cargo tank does not leak, and judging the state of the low-temperature sensor by constructing a leakage temperature distribution cloud picture and utilizing a temperature value and a temperature distribution cloud picture deviation value under the condition that the cargo tank leaks. The specific implementation mode is as follows:
in this embodiment, an insulation space of an LNG ship is taken as an example, and in combination with an actual use condition, each independent cargo tank insulation space of the LNG ship adopts N test areas, each test area includes two low-temperature sensors that are active and standby each other, each test area includes 2 paths of twin platinum resistors, and total 4 test points (i.e., measuring points), so that each cargo tank insulation space includes 4N test points. As shown in fig. 1, the set of temperature test points in the insulation space of the cargo tank of the present embodiment may be represented as t= {1,2, based on this data volume, a self-diagnosis of the health status of the low temperature sensor is achieved. As other embodiments, only one low temperature sensor may be disposed in each test area, and a plurality of low temperature sensors may be disposed in each test area by measuring temperature through two test points. As other embodiments
1) The liquid cargo tank insulation space is internally provided with N test areas, each test area is internally provided with at least one low-temperature sensor, temperature data of the N test areas are obtained through the low-temperature sensors, whether the liquid cargo tank leaks or not is judged according to the temperature data in each test area, each test area at least comprises one low-temperature sensor, and each low-temperature sensor correspondingly comprises two test points.
Specifically, for the low-temperature sensor arranged in the insulation space of the cargo tank, when the cargo tank leaks, the temperature data of the low-temperature sensor at the leakage point is relatively larger than that before leakage, and when the health state of the low-temperature sensor is diagnosed, in order to avoid inaccurate diagnosis results of the low-temperature sensor caused by the leakage of the cargo tank, two working conditions are considered, namely, the normal working condition of the cargo tank without leakage and the low-temperature working condition of the cargo tank when leakage are considered, and the temperature data of the low-temperature sensor is relatively larger when the two working conditions are different, so that the health state of the low-temperature sensor cannot be diagnosed in the same way, and therefore, the determination of which working condition the low-temperature sensor is in is needed before the diagnosis of the low-temperature sensor is needed. In order to accurately diagnose the health state of the low-temperature sensor, the embodiment respectively discusses the health state of the low-temperature sensor under the two conditions of the existence and the non-leakage of the liquid cargo tank.
Firstly, acquiring temperature data of each test area, and judging that the cargo tank is in a leakage condition if the temperature of a test point in each test area is lower than a temperature threshold value and the test point lower than the temperature threshold value exceeds a set value according to the temperature data acquired by each test area, otherwise, judging that the cargo tank is in a non-leakage condition. The collected temperature measuring modules of the temperature measuring system in each low-temperature sensor collect temperature data of 4N measuring points at the same time, if the temperature of the measuring points in the test area is lower than a third temperature threshold (for example, 100 ℃), and the number of the measuring points lower than the temperature threshold in the test area is above a set value (the set value in the embodiment is 2), the situation that the cargo tank of the LNG ship leaks is judged, an alarm signal is sent and a leakage working condition is entered, otherwise, a normal working condition is judged.
The low-temperature sensor in the embodiment comprises an induction end, a processing end, a lead wire and the like. The induction end of the low-temperature sensor is connected with the processing end through a lead. The induction end of the low-temperature sensor of the embodiment adopts a twin platinum resistor. The twin platinum resistor is composed of a double-way high-purity platinum wire, a high-purity corundum tube and a high-temperature-resistant sealing material, the size specification of the element is effectively reduced by adopting a front-back or double-sided printing mode, the alarm of the installation size of the twin platinum resistor is guaranteed to be consistent with that of a real ship, the purpose of adopting the twin platinum resistor in the embodiment is that two test points (namely, the same test point comprises two paths of temperature signals) can be arranged at the same temperature measuring position, the two paths of temperature signals are mutually verified, and 2 times of data volume is provided for the whole measuring system so as to realize data modeling and online calibration. The processing end of the low-temperature sensor comprises a direct-current resistance measuring module, wherein the direct-current resistance measuring module comprises an excitation constant-current power supply, a reference resistor, an impedance amplifying circuit and an AD acquisition circuit. The exciting constant current power supply is connected to the impedance amplifying circuit through the reference resistor, and the impedance amplifying circuit is connected with the AD acquisition circuit. The resistance value acquired by the induction end is converted into a voltage value through exciting the constant-current power supply and the reference resistor, the impedance amplifying circuit acquires the converted voltage value and transmits the acquired voltage value to the AD acquisition circuit, and the AD acquisition circuit converts the acquired voltage value into temperature data and uploads the temperature data to the temperature measuring module.
The length of a lead wire used for connecting the twin platinum resistor and the temperature measuring system is configured according to the actual installation positions of different test points, the lead wire adopts a polytetrafluoroethylene insulated five-core shielding lead wire, the requirement of low temperature resistance is met, and in order to remove the influence of the lead wire on the temperature measuring precision, a single sensing element is led out in a four-wire mode and connected to the temperature measuring system, wherein the fifth core of the shielding wire is used for grounding, so that the shielding effect is achieved, and the insulation failure is prevented.
The impedance amplifying circuit is a high input impedance amplifying circuit, and the AD acquisition circuit adopts a high-precision AD acquisition circuit.
The temperature data is sent to a signal processing module in the temperature measuring module through an A/D converter and an internal bus to carry out voltage signal quantization processing, and CPU internal software obtains accurate temperature data of a temperature control point after a series of algorithms such as filtering and nonlinear compensation are carried out on the quantized temperature measuring signal, and intelligent algorithm design is carried out on the data so as to realize self-diagnosis of the health state of the low-temperature sensor.
2) When the current cargo tank is in a leakage-free condition, the temperature data values of the two test points corresponding to the low-temperature sensors in each test area are mutually checked, if the check errors of the test points in the test area are smaller than or equal to a first set temperature value and all output temperature information, the low-temperature sensors corresponding to the test area work normally, and otherwise, the check errors exceed the first set temperature value and/or the low-temperature sensors corresponding to the test area without uploading the temperature information are in a fault state.
When the cargo tank is in a normal working condition without leakage, the two test points in each twin platinum resistor are mutually checked, and if the check error of the temperature data of the two test points is not larger than a first set temperature value (for example, the value is 0.5 ℃ in the embodiment), and the two test points corresponding to the same low-temperature sensor both output temperature information, the low-temperature sensor is indicated to be in a normal working state. If the verification error of the temperature data corresponding to two test points of the same low-temperature sensor is larger than a first set temperature value (for example, the value is 0.5 ℃ in the embodiment), and at least 1 test point in the two test points corresponding to the low-temperature sensor does not output temperature information, the low-temperature sensor is in a fault state; if the verification error of the temperature data corresponding to two test points of the same low-temperature sensor is larger than the first set temperature value (for example, the value is 0.5 ℃ in the embodiment), or at least 1 test point in the two test points corresponding to the low-temperature sensor does not output temperature information, the low-temperature sensor is in a fault state.
In particular, in the case where the present embodiment determines that the low temperature sensor is normal, the temperature data T recorded for the second set time (e.g., 30 minutes) is continuously stored in the system for self-diagnosis of the health state of the low temperature sensor min30 ＝{T 1 ，T 2 ，...，T i ，...，T n And the test point is ensured to store data in a normal working state for 30 minutes before the fault occurs.
3) When the current cargo tank is in a leakage condition, a leakage temperature distribution cloud chart is built by taking a leakage test area as a circle center, whether the temperature data value of each test area deviates from the leakage temperature distribution cloud chart to exceed a second set temperature value is judged, if yes, the low temperature sensor corresponding to the test area is in a fault state, and if not, the low temperature sensor is in a normal working state.
As shown in fig. 3, when the cargo tank is in a leakage working condition, performing state evaluation on the related temperature test points, taking the leakage test area as a center, and constructing a leakage temperature distribution cloud chart according to measured temperature data of the test area in the cargo tank. Judging whether the temperature data value of each test area deviates from the leakage temperature distribution cloud chart and exceeds a second set temperature value (such as 2 ℃), if so, indicating that the low-temperature sensor corresponding to the test area is in a fault state, otherwise, the low-temperature sensor is in a normal working state. Wherein the leakage temperature distribution cloud (which may also be a temperature distribution table) is constructed based on empirical data of a large number of historical actual measurements.
The present embodiment also includes the step of further analyzing the cryogenic sensor in a fault state (fault mode) in the event that the cargo tank is not leaking. And if the cargo tank is in a leakage state, giving priority to leakage alarm, and not carrying out fault identification and correction on the low-temperature sensor under the leakage condition.
As shown in FIG. 4, when the low temperature sensor is in a fault state, the 4 measuring point data of each test area are compared, and the fault measuring point T is determined by analogy x And the number y (x is more than or equal to 1 and y is more than or equal to 4) of the fault test points, so that the fault test points are temporarily isolated. Judging whether the fault test point outputs temperature data or not, and entering a correction mode by the fault test point outputting the temperature data, otherwise, locking the fault test point which does not output the temperature data into an isolated state, and replacing the fault test point with an adjacent test point in the same test area. Specifically, the adjacent test points are the normal test points closest to the fault test point in straight line. After no temperature data is output at the fault test point, the temperature data still needs to be output at the position to ensure that the temperature of the position is normal, so that the fault test point at the position can be taken over by an adjacent test point of the same low-temperature sensor as the fault test point, and if the adjacent test point of the same low-temperature sensor fails and cannot take electricity, the fault test point can also be taken over by an adjacent test point of the same test area. If the points cannot be taken in the same test area, the central axis is preferentially taken over by the symmetrical measuring points.
After the fault test point outputting the temperature data enters a correction mode, the data of the fault test point is compensated and calibrated on line, the calibrated temperature data is verified, if the temperature data still cannot meet the temperature measurement precision requirement after verification, the fault test point is locked into an isolated state, the test point is taken over by the adjacent normal test point, and if the temperature data meets the temperature measurement precision requirement after verification, the working state of the low-temperature sensor corresponding to the test point is normal.
The specific mode of the correction mode is as follows: firstly, judging the number of fault test points, when the number of fault test points in the same test area is less than the numberWhen the threshold value is measured, calculating a temperature difference value according to the average value of the temperatures of the fault test point in the current test area and other test points in the test area, calculating the average temperature difference value of the fault test point in the first set history period of the test area, correcting the temperature data of the fault test point by using the temperature difference value, namely calculating the temperature difference value according to the temperature value of the fault test area and the temperature values of other test points in the corresponding fault group, correcting the fault test point by using the temperature difference value, and checking the corrected temperature data, wherein if the checking result accords with the temperature measuring precision condition of the cargo tank, the test point is in a normal working state, otherwise, the test point is locked into an isolation state. Specifically, the threshold value in this embodiment is 2, and when the number y of fault test points is less than 2, 4 test points in the same test area are divided into a group, and the fault test point T is calculated x Temperature difference delta t between the temperature measuring point and average value of other measuring points in the same test area, namely
Wherein T is X-1 、T X+1 、T X+2 Are all with the test point T X And temperature data corresponding to other test points in the same test area.
Calculating average temperature difference values in the first set history period (such as 10 periods), namely respectively calculating 10 period temperature difference values deltat of the history according to the above mode, and calculating average value of the 10 period temperature difference values to obtain average temperature difference valueAverage temperature difference->Superimposed to the fault point Tx, the correction of the temperature data of the fault test point is completed, and the average temperature difference value +.>And a second set time (e.g30 minutes) temperature data T min30 Fitting, uploading the fitting result to a temperature measuring module in a low-temperature sensor health state self-diagnosis system, completing verification by using temperature data (namely the fitting result) of other test points in the same test area of the test point, and monitoring that no fault is found in a third period (for example, 30 periods), and putting the test point into a normal working state; if the temperature measurement precision requirement cannot be met after correction, the fault measuring point is locked into an isolated state, and the measuring point is taken over by the adjacent normal measuring point. Temperature data T min30 The data can be regarded as normal data of the area within 30 minutes of normal working state before failure occurs, and the fitting result can be used for judging the validity of the corrected data (the data error is less than 0.5 ℃).
When the number of fault test points in the test area is larger than the number threshold, the test area symmetrical to the fault test area and the fault test area are used as a fault group, a temperature difference is calculated according to the temperature value of the current fault test area and the temperature values of other test points in the corresponding fault group, an average temperature difference of the fault test points in a second set history period of the fault group is calculated, the fault test points are corrected according to the sum of the temperature value of the current fault test points and the average temperature difference of the fault test points in the second set period, the corrected temperature data are checked, if the checking result accords with the temperature measuring precision condition of the cargo tank, the test points are in a normal working state, and otherwise, the test points are locked into an isolation state. Specifically, when the number of fault test points of the test area is greater than or equal to a threshold value (y is greater than or equal to 2), taking the central axis of the cargo tank as a reference, dividing the test area of the fault test area and the test area of the fault test area into a fault group, calculating fault test points T, wherein the total number of the fault groups is 8 x Temperature difference delta t with average value of other measuring points in the same fault group is calculated in the same way, temperature difference in the second set history period (20 periods) is calculated respectively, and average value of the 20 periods is taken to obtain average temperature differenceAverage temperatureDegree difference->Superimposed to the fault point Tx, the correction of the temperature data of the fault test point is completed, and the average temperature difference value +.>And continuously recorded second set time (30 minutes, for example) temperature data T min30 Fitting, uploading a fitting result to a temperature measuring module in a low-temperature sensor health state self-diagnosis system, completing verification by using temperature data of other test points in the same test area of the test point, and monitoring that no fault is repeated in a third period (for example, 30 periods), and putting the test point into a normal working state; if the temperature measurement precision requirement cannot be met after correction, the fault measuring point is locked into an isolated state, and the measuring point is taken over by the adjacent normal measuring point.
Cryogenic sensor health status self-diagnostic system embodiments:
the low-temperature sensor health state self-diagnosis system comprises N test areas arranged in an insulation space of a cargo tank of a ship, wherein at least one low-temperature sensor is arranged in each test area, an induction end of the low-temperature sensor is connected with a processing end through a lead, the induction end comprises two test points, and each test point outputs one path of induction data to the processing end; the processing end comprises a direct current resistance measurement module, the direct current resistance measurement module converts data acquired by the sensing end into temperature data and uploads the temperature data, the system further comprises a temperature measurement module, the temperature measurement module is in communication connection with the processing end of each low-temperature sensor and is used for receiving the temperature data uploaded by each low-temperature sensor and processing the temperature data so as to realize the low-temperature sensor health status self-diagnosis method embodiment, and specific principles and implementation are described in detail in the low-temperature sensor health status self-diagnosis method embodiment and are not repeated here.
The low-temperature sensor in the embodiment comprises an induction end, a processing end, a lead wire and the like. The induction end of the low-temperature sensor is connected with the processing end through a lead. The induction end of the low-temperature sensor of the embodiment adopts a twin platinum resistor. The twin platinum resistor is composed of a double-way high-purity platinum wire, a high-purity corundum tube and a high-temperature-resistant sealing material, the size specification of the element is effectively reduced by adopting a front-back or double-sided printing mode, the alarm of the installation size of the twin platinum resistor is guaranteed to be consistent with that of a real ship, the purpose of adopting the twin platinum resistor in the embodiment is that two test points (namely, the same test point comprises two paths of temperature signals) can be arranged at the same temperature measuring position, the two paths of temperature signals are mutually verified, and 2 times of data volume is provided for the whole measuring system so as to realize data modeling and online calibration. The processing end of the low-temperature sensor comprises a direct-current resistance measuring module, wherein the direct-current resistance measuring module comprises an excitation constant-current power supply, a reference resistor, an impedance amplifying circuit and an AD acquisition circuit. The exciting constant current power supply is connected to the impedance amplifying circuit through the reference resistor, and the impedance amplifying circuit is connected with the AD acquisition circuit. The resistance value acquired by the induction end is converted into a voltage value through exciting the constant-current power supply and the reference resistor, the impedance amplifying circuit acquires the converted voltage value and transmits the acquired voltage value to the AD acquisition circuit, and the AD acquisition circuit converts the acquired voltage value into temperature data and uploads the temperature data to the temperature measuring module.
The length of a lead wire used for connecting the twin platinum resistor and the temperature measuring system is configured according to the actual installation positions of different test points, the lead wire adopts a polytetrafluoroethylene insulated five-core shielding lead wire, the requirement of low temperature resistance is met, and in order to remove the influence of the lead wire on the temperature measuring precision, a single sensing element is led out in a four-wire mode and connected to the temperature measuring system, wherein the fifth core of the shielding wire is used for grounding, so that the shielding effect is achieved, and the insulation failure is prevented.
The impedance amplifying circuit is a high input impedance amplifying circuit, and the AD acquisition circuit adopts a high-precision AD acquisition circuit.
The temperature measuring module comprises a signal processing module, a power module and a control communication module. The signal processing module is connected with the power module, the power module is connected with the control communication module, the power module can provide power for the temperature measuring module, and the temperature measuring module can conduct data interaction with each low-temperature sensor through the control communication module. The signal processing module comprises a CPU processor, and can perform algorithm analysis according to the received temperature data, so that the self-diagnosis of the health state of the low-temperature sensor is realized. The temperature data is sent to a signal processing module in the temperature measuring module through an A/D converter and an internal bus to carry out voltage signal quantization processing, and CPU internal software obtains accurate temperature data of a temperature control point after a series of algorithms such as filtering and nonlinear compensation are carried out on the quantized temperature measuring signal, and intelligent algorithm design is carried out on the data so as to realize self-diagnosis of the health state of the low-temperature sensor.
Claims (10)
1. The self-diagnosis method for the health state of the low-temperature sensor is characterized by comprising the following steps of:
1) Setting N test areas in the liquid cargo tank insulation space, setting at least one low-temperature sensor in each test area, acquiring temperature data of the N test areas through the low-temperature sensors, judging whether the liquid cargo tank leaks according to the temperature data in each test area, and correspondingly including two test points by each low-temperature sensor;
2) When the current cargo tank is in a leakage-free condition, checking temperature data values of at least two test points corresponding to the low-temperature sensors in each test area, if the checking errors of the two corresponding test points are smaller than or equal to a first set temperature value and temperature information is output, the corresponding low-temperature sensors work normally, otherwise, the checking errors exceed the first set temperature value and/or the low-temperature sensors corresponding to the test areas without uploading the temperature information are in a fault state;
3) When the current cargo tank is in a leakage condition, a leakage temperature distribution cloud chart based on measured temperature data is built by taking a leakage test area as a circle center, whether the temperature data value of each test area deviates from the leakage temperature distribution cloud chart and exceeds a second set temperature value is judged, if so, the low temperature sensor corresponding to the test area is in a fault state, and otherwise, the low temperature sensor is in a normal working state.
2. The method for self-diagnosing the health state of a low-temperature sensor according to claim 1, wherein when the low-temperature sensor is in a fault state, temperature data of all test points in each test area are compared respectively, test points within the fault test area and the number of the fault test points are determined according to a comparison result, whether the fault test points have temperature data output is judged, the fault test points outputting the temperature data enter a correction mode, otherwise, the fault test points not outputting the temperature data are locked in an isolated state, and the fault test points are replaced with adjacent test points in the same test area.
3. The method for self-diagnosis of the health state of a low-temperature sensor according to claim 2, wherein the correction pattern is: when the number of fault test points in the test area is smaller than the number threshold value, the test area is used as a fault group, a temperature difference value is calculated according to the temperature value of the fault test points in the fault group and the temperature average value of other test points in the fault group, the temperature data of the fault test points are corrected by utilizing the temperature difference value, the corrected data are used for verification, if the verification result accords with the temperature measurement precision condition of the cargo tank, the test points are in a normal working state, otherwise, the test points are locked into an isolation state;
when the number of the fault test points in the test area is not smaller than the number threshold value, the test area symmetrical to the fault test area and the fault test area are used as a fault group, a temperature difference value is calculated according to the temperature value of the fault test area and the temperature values of other test points in the corresponding fault group, the temperature difference value is utilized to correct the fault test point, the corrected temperature data is checked, if the checking result accords with the insulation space temperature measurement precision condition, the test point is in a normal working state, and otherwise, the test point is locked into an isolation state.
4. The method for self-diagnosis of the health status of a low temperature sensor according to claim 3, wherein the temperature difference when the number of fault test points in the test area is less than the number threshold is: the average temperature difference value of the fault test point in the current first set period is the average value of the difference values obtained by calculating the temperature value of the fault point and the average value of the temperatures of other test points in the fault group in the first set period;
the temperature difference value when the number of the fault test points in the test area is not smaller than the number threshold value is as follows: and the average temperature difference value of the fault test point in the second set period is the average value of the difference values obtained by calculating the temperature value of the fault point and the average value of the temperatures of other test points in the fault group in the second set period.
5. The self-diagnosis method of the state of health of a cryogenic sensor according to claim 2, characterized in that the means for judging whether the cargo tank is leaking is: if the temperature of the test points in the test area is lower than the third temperature threshold value and the number of the test points lower than the third temperature threshold value is above a set value, judging that the test area is in a leakage condition, otherwise, judging that the test area is in a non-leakage condition.
6. The method for self-diagnosis of the health status of a low-temperature sensor according to any one of claims 1 to 4, wherein the sensing part of the low-temperature sensor employs a twin platinum resistor.
7. The self-diagnosis system for the health state of the low-temperature sensor comprises N test areas which are arranged in an insulation space of a cargo tank of a ship, wherein at least one low-temperature sensor is arranged in each test area, and an induction end of the low-temperature sensor is connected with a processing end through a lead wire; the processing end comprises a direct current resistance measurement module, wherein the direct current resistance measurement module is used for converting data acquired by the sensing end into temperature data and uploading the temperature data, the system further comprises a temperature measurement module, the temperature measurement module is in communication connection with the processing end of each low-temperature sensor and is used for receiving the temperature data uploaded by each low-temperature sensor and processing the temperature data so as to realize the low-temperature sensor health state self-diagnosis method according to any one of claims 1-5.
8. The system of claim 7, wherein the sensing end of the low temperature sensor is a twin platinum resistor.
9. The system of claim 8, wherein the direct current resistance measurement module comprises an excitation constant current power supply, a reference resistor, an impedance amplification circuit and an AD acquisition circuit, the excitation constant current power supply is connected to the impedance amplification circuit through the reference resistor, the impedance amplification circuit is connected with the AD acquisition circuit, the excitation constant current power supply and the reference resistor are used for converting a resistance value acquired by the sensing end into a voltage value, the impedance amplification circuit is used for acquiring the converted voltage value and transmitting the acquired voltage value to the AD acquisition circuit, and the AD acquisition circuit is used for converting the acquired voltage value into temperature data and uploading the temperature data to the temperature measurement module.
10. The system of claim 7, wherein the lead wire is an insulated five-core shielded wire, the sensing end is connected to the processing end through four cores of the shielded wire, and a fifth core of the shielded wire is used for grounding.
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