A comprehensive intelligent sensing and protection security system

Abstract

This invention discloses an all-round intelligent sensing and protection safety system, relating to the field of power plant protection technology. It includes a sensor array, a temperature anomaly accumulation calculation module (communicating with the sensor array) for identifying areas in the temperature field data where the temperature value exceeds the background temperature value as temperature anomaly areas, and calculating the cumulative difference between the temperature values ​​at each measuring point within the temperature anomaly area and the background temperature value as the temperature anomaly accumulation; a gas concentration accumulation calculation module (communicating with the sensor array); an acoustic energy integration calculation module (communicating with the sensor array); and a cross-field coupling judgment module. By conducting calibration tests on similar transformers to determine the calibration property ratio range and calibration acoustic energy reference value, the judgment threshold can adapt to the physical characteristics of different types of transformers, avoiding the problem of poor adaptability caused by manually setting fixed thresholds.

Description

Technical Field

[0001] This invention belongs to the field of power plant protection technology, specifically a comprehensive intelligent sensing and protection safety system. Background Technology

[0002] During operation, power plant transformers may experience leaks due to long-term exposure to electric fields, thermal fields, and mechanical stresses. These leaks can lead to issues such as seal aging, weld cracking, or loosening of pipe connections. Transformer oil leaks not only degrade insulation performance and cause equipment failure, but the leaked oil can also release flammable vapors at high temperatures, posing a fire and explosion hazard. Therefore, timely and accurate detection and prevention of transformer oil leaks are crucial technical means to ensure the safe operation of power plant transformers.

[0003] Currently, existing methods for detecting transformer oil leaks mainly rely on single-type sensors. For example, temperature sensors monitor abnormal transformer surface temperatures to determine if oil loss is occurring; combustible gas sensors monitor the concentration of combustible gases in the surrounding environment to infer oil evaporation; or acoustic sensors monitor abnormal noises during transformer operation to identify potential leak points. However, these single-sensor detection methods have the following technical drawbacks: First, temperature sensors are easily affected by changes in transformer load, ambient temperature fluctuations, and nearby heat sources, leading to false alarms. Second, combustible gas sensors are easily affected by other combustible gas sources in the surrounding environment, making it impossible to distinguish between transformer oil evaporation and other combustible gas leaks. Third, acoustic sensors are easily affected by the mechanical and electromagnetic noise commonly found in power plant environments, resulting in insufficient detection sensitivity. More importantly, these detection methods operate independently, lacking effective coupling and correlation analysis methods between various physical quantities. When multiple interfering factors are present simultaneously, the false alarm rate increases significantly, making it difficult to achieve accurate and reliable determination of transformer oil leaks.

[0004] Furthermore, existing technologies, once an oil leak is detected, can typically only provide simple alarm information, lacking quantitative assessment methods for the extent of the leak. This fails to provide maintenance personnel with a basis for leak flow estimation and tiered control, resulting in a lack of targeted follow-up investigation and handling. Summary of the Invention

[0005] Therefore, existing technologies urgently need a transformer oil leakage sensing and protection scheme that can couple and correlate multiple physical field responses, effectively eliminate non-leakage interference, and quantitatively assess the degree of leakage.

[0006] The present invention adopts the following technical solution, specifically proposing an all-round intelligent sensing and protection safety system, including a sensor array arranged around the transformer for collecting acoustic signal data, temperature field data and combustible gas concentration data of the transformer area. The sensor array includes acoustic sensors, temperature sensors and combustible gas sensors installed in groups at the same measuring point.

[0007] The temperature anomaly accumulation calculation module is communicatively connected to the sensor array. It is used to find areas in the temperature field data where the temperature value exceeds the background temperature value as temperature anomaly areas, and to calculate the cumulative value of the difference between the temperature value of each measuring point in the temperature anomaly area and the background temperature value as the temperature anomaly accumulation.

[0008] The gas concentration accumulation calculation module is communicatively connected to the sensor array. It is used to find areas in the combustible gas concentration data where the concentration value exceeds the background concentration value as gas concentration anomaly areas, and to calculate the cumulative value of the difference between the concentration value of each measuring point in the gas concentration anomaly area and the background concentration value as the gas concentration accumulation.

[0009] The acoustic energy integration calculation module is communicatively connected to the sensor array and is used to find periods in the acoustic signal data where the sound pressure value exceeds the background sound pressure value as acoustic abnormal events, and to calculate the time integral of the square of the sound pressure value during the acoustic abnormal event as the acoustic energy integral.

[0010] The cross-field coupling judgment module is communicatively connected to the temperature anomaly accumulation calculation module, the gas concentration accumulation calculation module, and the acoustic energy integration calculation module, respectively. It is used to calculate the ratio of the temperature anomaly accumulation to the gas concentration accumulation as the cross-field accumulation ratio, and to calculate the ratio of the acoustic energy integration to the number of measuring points in the temperature anomaly area as the single-point acoustic energy value. When the cross-field accumulation ratio is within the range of the transformer oil calibration property ratio and the single-point acoustic energy value exceeds the calibration acoustic energy reference value, a transformer oil leakage judgment signal is output.

[0011] Furthermore, the temperature anomaly accumulation calculation module includes:

[0012] The background temperature calculation unit is used to calculate the arithmetic mean of the temperature values ​​of all measuring points in the temperature field data as the background temperature value Tb.

[0013] The temperature anomaly area identification unit is used to identify measuring points whose temperature values ​​exceed the background temperature value Tb as temperature anomaly areas.

[0014] The temperature anomaly cumulative output unit is used to subtract the temperature value Ti of the i-th measuring point in the temperature anomaly area from the background temperature value Tb point by point and then sum them up to output the temperature anomaly cumulative amount ST. The calculation formula is that ST is equal to the sum of the differences between Ti and Tb of all temperature anomaly measuring points.

[0015] Furthermore, the gas concentration accumulation calculation module includes:

[0016] The background concentration calculation unit is used to calculate the arithmetic mean of the concentration values ​​of all measuring points in the combustible gas concentration data as the background concentration value Cb.

[0017] The gas concentration anomaly area identification unit is used to identify measuring points with concentration values ​​exceeding the background concentration value Cb as gas concentration anomaly areas.

[0018] The gas concentration accumulation output unit is used to subtract the concentration value Cj of the j-th measuring point in the gas concentration anomaly area from the background concentration value Cb point by point and then sum them up to output the gas concentration accumulation SC. The calculation formula is that SC is equal to the sum of the differences between Cj and Cb of all gas concentration anomaly measuring points.

[0019] Furthermore, the acoustic energy integration calculation module includes:

[0020] The background sound pressure calculation unit is used to calculate the running average of the sound pressure values ​​at each sampling time in the acoustic signal data as the background sound pressure value Pb.

[0021] An acoustic anomaly event identification unit is used to identify periods when the sound pressure value exceeds the background sound pressure value Pb as acoustic anomalies.

[0022] The acoustic energy integration output unit is used to square the sound pressure value Pn at the nth sampling time during an acoustic anomaly event, multiply it by the sampling time interval dt, sum the products of all sampling times, and output the acoustic energy integral E. The calculation formula is that E is equal to the sum of the products of the squares of Pn at all acoustic anomaly sampling times and dt, where dt is equal to the reciprocal of the acoustic signal data sampling frequency fs.

[0023] Furthermore, the cross-field coupling determination module includes:

[0024] The calibration property ratio range storage unit is used to store the lower limit Rmin and upper limit Rmax of the calibration property ratio range of transformer oil;

[0025] A calibration acoustic energy reference value storage unit is used to store the calibration acoustic energy reference value Eref;

[0026] The cross-field cumulative ratio calculation unit is used to receive the temperature anomaly accumulation ST and the gas concentration accumulation SC, and calculate the cross-field cumulative ratio R, which is equal to the ratio of ST to SC.

[0027] The single-point acoustic energy value calculation unit is used to receive the acoustic energy integral E and the number of measuring points MT in the temperature anomaly area, and calculate the single-point acoustic energy value Esingle, which is equal to the ratio of E to MT.

[0028] The leakage detection output unit is used to compare R with Rmin and Rmax, and to compare Esingle with Eref. When R is greater than or equal to Rmin, R is less than or equal to Rmax, and Esingle is greater than or equal to Eref, a transformer oil leakage detection signal is output.

[0029] Furthermore, the lower limit Rmin and upper limit Rmax in the calibration property ratio interval storage unit are determined through the following steps:

[0030] Conduct transformer oil leakage calibration tests on similar transformers. The number of calibration tests is recorded as N, and N shall be no less than three.

[0031] In the kth calibration test, the known leakage flow rate is denoted as Qk, and Qk is controlled by a flow meter connected in the transformer oil circulation system pipeline;

[0032] Calculate the cumulative temperature anomaly STk for the kth calibration according to the calculation method of the cumulative temperature anomaly calculation module;

[0033] Calculate the cumulative gas concentration SCk for the kth calibration according to the calculation method of the cumulative gas concentration calculation module;

[0034] Calculate the ratio of physical properties Rk for the kth calibration, where Rk is equal to the ratio of STk to SCk;

[0035] The lower limit Rmin is the minimum value of Rk in N calibration tests, and the upper limit Rmax is the maximum value of Rk in N calibration tests.

[0036] Furthermore, the calibration acoustic energy reference value Eref in the calibration acoustic energy reference value storage unit is determined through the following steps:

[0037] In the calibration test, the k-th calibration acoustic energy integral Ek is calculated according to the calculation method of the acoustic energy integral calculation module;

[0038] Count the number of measuring points Mk in the temperature anomaly area during the k-th calibration test;

[0039] Calculate the single-point acoustic energy value Eksingle for the kth calibration, where Eksingle is equal to the ratio of Ek to Mk;

[0040] The calibration acoustic energy reference value Eref is the minimum value among the Eksingle values ​​from N calibration tests.

[0041] Furthermore, in the sensor array:

[0042] Acoustic sensors, temperature sensors, and combustible gas sensors are installed in groups at the same measuring point;

[0043] The spacing d between adjacent measuring points is determined by referring to the transformer fire protection design code based on the rated capacity S of the transformer. d is the required spacing value for the monitoring points corresponding to the rated capacity S in the code.

[0044] Three sensors at the same measuring point receive the second pulse signal generated by the same clock source through a coaxial cable, and time synchronization is performed based on the rising edge of the second pulse signal, with a time synchronization accuracy of not less than 1 millisecond.

[0045] Furthermore, each sensor in the sensor array has a built-in analog-to-digital converter, so that the analog signal is converted into a digital signal locally on the sensor.

[0046] The digital signal is transmitted to the temperature anomaly accumulation calculation module, gas concentration accumulation calculation module and sound energy integration calculation module after being marked with a timestamp. The timestamp is based on the second pulse signal generated by a unified clock source.

[0047] Furthermore, the leakage level determination module is communicatively connected to the cross-field coupling judgment module. After receiving the transformer oil leakage judgment signal, it calculates the average temperature rise deltaT based on the average difference between the temperature value of each measuring point in the temperature abnormal area and the background temperature value output by the temperature abnormality accumulation calculation module. deltaT is equal to the sum of the differences between Ti and Tb of all temperature abnormal measuring points divided by the number of measuring points MT in the temperature abnormal area.

[0048] The volume V of the temperature anomaly region is calculated based on the number of measuring points MT and the distance d between adjacent measuring points. V is equal to the product of MT and the cube of d.

[0049] The leakage heat Q is calculated based on the average temperature rise deltaT, volume V, specific heat capacity c and density rho of transformer oil. Q is equal to the product of c, rho, V and deltaT.

[0050] The leakage heat power P is calculated based on the leakage heat Q and the duration deltat of the temperature anomaly region. P is equal to the ratio of Q to deltat.

[0051] The vaporization equivalent flow rate Qvap is calculated based on the leakage heat power P and the latent heat of vaporization Hvap of the transformer oil. Qvap is equal to the ratio of P to Hvap.

[0052] The leakage rate L is calculated based on the vaporization equivalent flow rate Qvap and the total oil volume Vtotal of the transformer oil circulation system. L is equal to the ratio of Qvap to Vtotal.

[0053] The leakage rate L is compared with the allowable leakage rate Lref, which is obtained from the technical data provided by the transformer manufacturer.

[0054] When L is less than Lref, a low-level leakage signal is output; when L is greater than or equal to Lref, a medium-level leakage signal is output; when L is greater than or equal to Lref and Qvap exceeds the rated flow rate of the supplementary oil pump of the transformer oil circulation system, a high-level leakage signal is output.

[0055] The technical solutions provided by the embodiments of this disclosure have at least the following beneficial effects:

[0056] The cross-field coupling judgment module uses the ratio of the accumulated temperature anomaly to the accumulated gas concentration as the cross-field accumulation ratio, compares this cross-field accumulation ratio with the transformer oil calibration property ratio range, and uses the ratio of the acoustic energy integral to the number of measuring points in the temperature anomaly area as the single-point acoustic energy value, compares this single-point acoustic energy value with the calibration acoustic energy benchmark value, thus realizing the dual threshold joint judgment.

[0057] Compared with the existing technology that uses a single sensor for independent judgment, this application establishes a physical property correlation between the temperature field and the gas concentration field by the ratio of the accumulated temperature anomaly to the accumulated gas concentration. Only when the temperature anomaly and the gas anomaly conform to the inherent thermal properties of transformer oil can it be confirmed that they originate from the same leakage event, thereby effectively eliminating false judgments caused by independent temperature and gas interference sources. At the same time, the homology between acoustic anomalies and temperature anomalies is verified by single-point acoustic energy values, further eliminating external noise interference and significantly reducing the false alarm rate of the system.

[0058] By conducting calibration tests on similar transformers, the calibration property ratio range and calibration acoustic energy reference value are determined, so that the judgment threshold can adapt to the physical characteristics of different types of transformers, avoiding the problem of poor adaptability caused by artificially setting a fixed threshold.

[0059] After determining that transformer oil leakage exists, this application uses a leakage level determination module to calculate the vaporization equivalent flow rate and leakage rate based on physical properties such as the volume of the temperature anomaly area, average temperature rise, specific heat capacity, density, and latent heat of vaporization of the transformer oil. The leakage rate is then compared with the allowable leakage rate to determine the leakage level, thus achieving a quantitative assessment of the leakage degree. This provides maintenance personnel with a tiered control basis from inspection and local isolation to shutdown maintenance, improving the pertinence and efficiency of leakage handling. Attached Figure Description

[0060] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0061] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] like Figure 1 The present invention discloses an all-round intelligent sensing and protection safety system, including a sensor array arranged around a transformer for collecting acoustic signal data, temperature field data and combustible gas concentration data of the transformer area. The sensor array includes acoustic sensors, temperature sensors and combustible gas sensors installed in groups at the same measuring point.

[0063] The temperature anomaly accumulation calculation module is communicatively connected to the sensor array. It is used to find areas in the temperature field data where the temperature value exceeds the background temperature value as temperature anomaly areas, and to calculate the cumulative value of the difference between the temperature value of each measuring point in the temperature anomaly area and the background temperature value as the temperature anomaly accumulation.

[0064] The gas concentration accumulation calculation module is communicatively connected to the sensor array. It is used to find areas in the combustible gas concentration data where the concentration value exceeds the background concentration value as gas concentration anomaly areas, and to calculate the cumulative value of the difference between the concentration value of each measuring point in the gas concentration anomaly area and the background concentration value as the gas concentration accumulation.

[0065] The acoustic energy integration calculation module is communicatively connected to the sensor array and is used to find periods in the acoustic signal data where the sound pressure value exceeds the background sound pressure value as acoustic abnormal events, and to calculate the time integral of the square of the sound pressure value during the acoustic abnormal event as the acoustic energy integral.

[0066] The cross-field coupling judgment module is communicatively connected to the temperature anomaly accumulation calculation module, the gas concentration accumulation calculation module, and the acoustic energy integration calculation module, respectively. It is used to calculate the ratio of the temperature anomaly accumulation to the gas concentration accumulation as the cross-field accumulation ratio, and to calculate the ratio of the acoustic energy integration to the number of measuring points in the temperature anomaly area as the single-point acoustic energy value. When the cross-field accumulation ratio is within the range of the transformer oil calibration property ratio and the single-point acoustic energy value exceeds the calibration acoustic energy reference value, a transformer oil leakage judgment signal is output.

[0067] It should be noted that acoustic signal data, temperature field data, and combustible gas concentration data of the transformer area are collected through a sensor array. The temperature anomaly accumulation calculation module processes the temperature field data and outputs the temperature anomaly accumulation; the gas concentration accumulation calculation module processes the combustible gas concentration data and outputs the gas concentration accumulation; and the acoustic energy integration calculation module processes the acoustic signal data and outputs the acoustic energy integral. The cross-field coupling judgment module receives the outputs of the three calculation modules, calculates the cross-field accumulation ratio and the single-point acoustic energy value, and outputs a transformer oil leakage judgment signal through a dual-threshold joint judgment. The cross-field accumulation ratio reflects the inherent thermophysical characteristics of the transformer oil, and the single-point acoustic energy value reflects the acoustic energy intensity of the leakage event. The joint judgment of these two ratio indicators can avoid misjudgments caused by a single physical quantity anomaly.

[0068] As an optional embodiment, the temperature anomaly accumulation calculation module includes:

[0069] The background temperature calculation unit is used to calculate the arithmetic mean of the temperature values ​​of all measuring points in the temperature field data as the background temperature value Tb.

[0070] The temperature anomaly area identification unit is used to identify measuring points whose temperature values ​​exceed the background temperature value Tb as temperature anomaly areas.

[0071] The temperature anomaly cumulative output unit is used to subtract the temperature value Ti of the i-th measuring point in the temperature anomaly area from the background temperature value Tb point by point and then sum them up to output the temperature anomaly cumulative amount ST. The calculation formula is that ST is equal to the sum of the differences between Ti and Tb of all temperature anomaly measuring points.

[0072] It should be noted that in the background temperature calculation unit, the background temperature value Tb is calculated as follows: Tb equals the sum of the temperature values ​​Tm of all M measuring points divided by M, i.e., Tb is the arithmetic mean of T1 to TM, where M is the total number of temperature sensors in the sensor array. The temperature anomaly region identification unit compares the temperature value Tm of each measuring point with Tb. When Tm is greater than Tb, the measuring point is identified as a temperature anomaly measuring point, and all temperature anomaly measuring points constitute a temperature anomaly region. In the temperature anomaly cumulative output unit, the temperature anomaly cumulative quantity ST is calculated as follows: ST equals the sum of the differences between Ti and Tb of all temperature anomaly measuring points, where i is the number of the temperature anomaly measuring point. The physical meaning of ST is the sum of the deviations of all measuring points within the temperature anomaly region from the background temperature, and it includes information on both the scale and intensity of the anomaly.

[0073] As an optional embodiment, the gas concentration accumulation calculation module includes:

[0074] The background concentration calculation unit is used to calculate the arithmetic mean of the concentration values ​​of all measuring points in the combustible gas concentration data as the background concentration value Cb.

[0075] The gas concentration anomaly area identification unit is used to identify measuring points with concentration values ​​exceeding the background concentration value Cb as gas concentration anomaly areas.

[0076] The gas concentration accumulation output unit is used to subtract the concentration value Cj of the j-th measuring point in the gas concentration anomaly area from the background concentration value Cb point by point and then sum them up to output the gas concentration accumulation SC. The calculation formula is that SC is equal to the sum of the differences between Cj and Cb of all gas concentration anomaly measuring points.

[0077] It should be noted that in the background concentration calculation unit, the background concentration value Cb is calculated as follows: Cb equals the sum of the concentration values ​​Cm of all M measuring points divided by M, i.e., Cb is the arithmetic mean of C1 to CM, and M is the total number of combustible gas sensors in the sensor array. The gas concentration anomaly area identification unit compares the concentration value Cm of each measuring point with Cb. When Cm is greater than Cb, the measuring point is identified as a gas concentration anomaly measuring point, and all gas concentration anomaly measuring points constitute a gas concentration anomaly area. In the gas concentration accumulation output unit, the gas concentration accumulation SC is calculated as follows: SC equals the sum of the differences between Cj and Cb of all gas concentration anomaly measuring points, where j is the number of the gas concentration anomaly measuring point. The physical meaning of SC is the sum of the deviations of all measuring points within the gas concentration anomaly area from the background concentration.

[0078] As an optional embodiment, the acoustic energy integration calculation module includes:

[0079] The background sound pressure calculation unit is used to calculate the running average of the sound pressure values ​​at each sampling time in the acoustic signal data as the background sound pressure value Pb.

[0080] An acoustic anomaly event identification unit is used to identify periods when the sound pressure value exceeds the background sound pressure value Pb as acoustic anomalies.

[0081] The acoustic energy integration output unit is used to square the sound pressure value Pn at the nth sampling time during an acoustic anomaly event, multiply it by the sampling time interval dt, sum the products of all sampling times, and output the acoustic energy integral E. The calculation formula is that E is equal to the sum of the products of the squares of Pn at all acoustic anomaly sampling times and dt, where dt is equal to the reciprocal of the acoustic signal data sampling frequency fs.

[0082] It should be noted that in the background sound pressure calculation unit, the background sound pressure value Pb is calculated using a sliding window average. The window length is determined based on the stabilization period of the transformer's operating conditions. The stabilization period refers to the time required for the transformer's temperature to re-stabilize after transitioning from one load state to another. In the acoustic anomaly event identification unit, the starting sampling time nstart of the acoustic anomaly event is the sampling time when the sound pressure value first exceeds Pb, and the ending sampling time nend is the sampling time when the number of sampling points where the sound pressure value is continuously below Pb after the first time it is below Pb exceeds the preset sampling window length. The preset sampling window length is determined based on the sampling frequency fs and the duration of a typical acoustic pulse generated by transformer oil injection. In the acoustic energy integration output unit, the sampling time interval dt is equal to 1 divided by fs, in seconds. The acoustic energy integral E is calculated using a discrete summation method, with the formula: E is equal to the sum of the squares of Pn at all sampling times from nstart to nend and the product of dt. The physical meaning of the acoustic energy integral E is the time accumulation of sound wave energy during the acoustic anomaly event.

[0083] As an optional embodiment, the cross-field coupling determination module includes:

[0084] The calibration property ratio range storage unit is used to store the lower limit Rmin and upper limit Rmax of the calibration property ratio range of transformer oil;

[0085] A calibration acoustic energy reference value storage unit is used to store the calibration acoustic energy reference value Eref;

[0086] The cross-field cumulative ratio calculation unit is used to receive the temperature anomaly accumulation ST and the gas concentration accumulation SC, and calculate the cross-field cumulative ratio R, which is equal to the ratio of ST to SC.

[0087] The single-point acoustic energy value calculation unit is used to receive the acoustic energy integral E and the number of measuring points MT in the temperature anomaly area, and calculate the single-point acoustic energy value Esingle, which is equal to the ratio of E to MT.

[0088] The leakage detection output unit is used to compare R with Rmin and Rmax, and to compare Esingle with Eref. When R is greater than or equal to Rmin, R is less than or equal to Rmax, and Esingle is greater than or equal to Eref, a transformer oil leakage detection signal is output.

[0089] It should be noted that in the cross-field cumulative ratio calculation unit, the cross-field cumulative ratio R is calculated as R equal to ST divided by SC. R is a dimensionless ratio, eliminating the influence of spatial scale differences between temperature anomaly regions and gas concentration anomaly regions on the absolute cumulative amount. In the single-point acoustic energy value calculation unit, the number of measurement points MT is the number of measurement points in the temperature anomaly region whose temperature value exceeds the background temperature value. The single-point acoustic energy value Esingle is calculated as Esingle equal to E divided by MT. Esingle eliminates the influence of the size of the temperature anomaly region on the acoustic energy integral under different leakage scales. In the leakage judgment output unit, the judgment condition is that R is greater than or equal to Rmin and R is less than or equal to Rmax, and Esingle is greater than or equal to Eref. When both conditions are met, a transformer oil leakage judgment signal is output.

[0090] As an optional embodiment, the lower limit Rmin and upper limit Rmax in the calibration property ratio interval storage unit are determined by the following steps:

[0091] Conduct transformer oil leakage calibration tests on similar transformers. The number of calibration tests is recorded as N, and N shall be no less than three.

[0092] In the kth calibration test, the known leakage flow rate is denoted as Qk, and Qk is controlled by a flow meter connected in the transformer oil circulation system pipeline;

[0093] Calculate the cumulative temperature anomaly STk for the kth calibration according to the calculation method of the cumulative temperature anomaly calculation module;

[0094] Calculate the cumulative gas concentration SCk for the kth calibration according to the calculation method of the cumulative gas concentration calculation module;

[0095] Calculate the ratio of physical properties Rk for the kth calibration, where Rk is equal to the ratio of STk to SCk;

[0096] The lower limit Rmin is the minimum value of Rk in N calibration tests, and the upper limit Rmax is the maximum value of Rk in N calibration tests.

[0097] It should be noted that the calibration tests are conducted on similar transformers to ensure that the transformer being calibrated has the same insulating oil type and structural characteristics as the transformer in the actual application scenario. Each calibration test uses a different known leakage flow rate Qk. Qk is controlled by a flow meter connected to the transformer oil circulation system pipeline, with the flow meter accuracy not less than one percent of its range. The range of leakage flow rate Qk covers the expected range of transformer leakage from slight to severe leakage, with the minimum leakage flow rate being one ten-thousandth of the total oil volume in the transformer oil circulation system per hour, and the maximum leakage flow rate being one percent of the total oil volume per hour. N calibration tests yield N calibration property ratios Rk, where Rmin is the minimum and Rmax is the maximum. The calibration property ratio range storage unit stores Rmin and Rmax as the lower and upper limits of the calibration property ratio range.

[0098] As an optional embodiment, the calibration acoustic energy reference value Eref in the calibration acoustic energy reference value storage unit is determined through the following steps:

[0099] In the calibration test, the k-th calibration acoustic energy integral Ek is calculated according to the calculation method of the acoustic energy integral calculation module;

[0100] Count the number of measuring points Mk in the temperature anomaly area during the k-th calibration test;

[0101] Calculate the single-point acoustic energy value Eksingle for the kth calibration, where Eksingle is equal to the ratio of Ek to Mk;

[0102] The calibration acoustic energy reference value Eref is the minimum value among the Eksingle values ​​from N calibration tests.

[0103] It should be noted that the calibration acoustic energy reference value Eref is the minimum single-point acoustic energy value Eksingle in each calibration test. Using the minimum value, rather than the average value, as the reference ensures that the leakage detection output unit will not miss leakage events within the calibration range during actual detection. The formula for calculating the calibration single-point acoustic energy value Eksingle is Eksingle equal to Ek divided by Mk, where Mk is the number of measurement points whose temperature value exceeds the background temperature value in the k-th calibration test. The calibration acoustic energy reference value storage unit stores Eref as the calibration acoustic energy reference value.

[0104] As an optional embodiment, in the sensor array:

[0105] Acoustic sensors, temperature sensors, and combustible gas sensors are installed in groups at the same measuring point;

[0106] The spacing d between adjacent measuring points is determined by referring to the transformer fire protection design code based on the rated capacity S of the transformer. d is the required spacing value for the monitoring points corresponding to the rated capacity S in the code.

[0107] Three sensors at the same measuring point receive the second pulse signal generated by the same clock source through a coaxial cable, and time synchronization is performed based on the rising edge of the second pulse signal, with a time synchronization accuracy of not less than 1 millisecond.

[0108] It should be noted that the acoustic sensor, temperature sensor, and combustible gas sensor are installed in a group at the same measuring point, ensuring that the three physical quantities are collected in the same spatial location, thus avoiding data spatiotemporal alignment errors caused by differences in the spatial positions of the sensors. The method for determining the spacing d is as follows: refer to the monitoring point layout spacing requirement table in the transformer fire protection design code based on the transformer's rated capacity S, and directly find the corresponding d value. When the transformer is equipped with a forced oil circulation cooling system, additional measuring points are added in the direction of the cooling oil pipeline, with the spacing between the additional measuring points being half of d. A unified clock source generates a second pulse signal, which is distributed to each measuring point through a coaxial cable. Each sensor calibrates its own clock based on the rising edge of the second pulse signal, ensuring the consistency of the timestamps of the data collected by the three sensors.

[0109] As an optional embodiment, each sensor in the sensor array has a built-in analog-to-digital converter, and the analog signal is converted into a digital signal locally at the sensor.

[0110] The digital signal is transmitted to the temperature anomaly accumulation calculation module, gas concentration accumulation calculation module and sound energy integration calculation module after being marked with a timestamp. The timestamp is based on the second pulse signal generated by a unified clock source.

[0111] It should be noted that local analog-to-digital conversion is performed at the sensor terminal, reducing noise interference and signal attenuation introduced by long-distance analog signal transmission. The resolution of the analog-to-digital converter is determined according to the range and accuracy requirements of each sensor. The resolution of the analog-to-digital converter for temperature sensors is no less than 0.1 degrees Celsius, for combustible gas sensors it is no less than one-thousandth of the range, and for acoustic sensors it is no less than 16 bits. The digital signal after analog-to-digital conversion carries a timestamp, which is based on a second pulse signal generated by a unified clock source, with a marking accuracy of 1 millisecond. The digital signal is transmitted to each computing module via a wired communication link.

[0112] As an optional embodiment, the leakage level determination module is communicatively connected to the cross-field coupling judgment module. After receiving the transformer oil leakage judgment signal, it calculates the average temperature rise deltaT based on the average difference between the temperature value of each measuring point in the temperature abnormal area and the background temperature value output by the temperature abnormality accumulation calculation module. deltaT is equal to the sum of the differences between Ti and Tb of all temperature abnormal measuring points divided by the number of measuring points MT in the temperature abnormal area.

[0113] The volume V of the temperature anomaly region is calculated based on the number of measuring points MT and the distance d between adjacent measuring points. V is equal to the product of MT and the cube of d.

[0114] The leakage heat Q is calculated based on the average temperature rise deltaT, volume V, specific heat capacity c and density rho of transformer oil. Q is equal to the product of c, rho, V and deltaT.

[0115] The leakage heat power P is calculated based on the leakage heat Q and the duration deltat of the temperature anomaly region. P is equal to the ratio of Q to deltat.

[0116] The vaporization equivalent flow rate Qvap is calculated based on the leakage heat power P and the latent heat of vaporization Hvap of the transformer oil. Qvap is equal to the ratio of P to Hvap.

[0117] The leakage rate L is calculated based on the vaporization equivalent flow rate Qvap and the total oil volume Vtotal of the transformer oil circulation system. L is equal to the ratio of Qvap to Vtotal.

[0118] The leakage rate L is compared with the allowable leakage rate Lref, which is obtained from the technical data provided by the transformer manufacturer.

[0119] When L is less than Lref, a low-level leakage signal is output; when L is greater than or equal to Lref, a medium-level leakage signal is output; when L is greater than or equal to Lref and Qvap exceeds the rated flow rate of the supplementary oil pump of the transformer oil circulation system, a high-level leakage signal is output.

[0120] It should be noted that the average temperature rise deltaT is calculated as follows: deltaT equals the sum of the differences between Ti and Tb at all temperature anomaly measurement points divided by MT. In other words, deltaT is the arithmetic mean of the differences between the temperature values ​​at each measurement point within the temperature anomaly region and the background temperature value. The volume V of the temperature anomaly region is calculated as V equals MT multiplied by the cube of d, assuming the measurement points are uniformly distributed in three-dimensional space, with each measurement point occupying a cube with side length d. The leakage heat Q is calculated as Q equals c multiplied by rho multiplied by V and then multiplied by deltaT, where the specific heat capacity c and density rho are obtained from the transformer oil product technical specifications. The duration deltat is the time interval between the first time the average temperature within the temperature anomaly region exceeds the background temperature value and the last time it exceeds the background temperature value. The formula for calculating the vaporization equivalent flow rate Qvap is Qvap equal to P divided by Hvap. Hvap is obtained from the transformer oil product technical specifications. The physical meaning of Qvap is the equivalent oil volume flow rate if all the leaked heat is used to drive the phase change vaporization of the transformer oil. This equivalent value is a conservative estimate; the actual leakage flow rate is greater than or equal to Qvap. The total oil volume Vtotal is obtained from the transformer technical files and is the sum of the oil volume in the transformer body, oil pipelines, and oil conservator. The allowable leakage rate Lref is obtained from the technical data provided by the transformer manufacturer. The rated flow rate of the supplementary oil pump is obtained from the oil pump product nameplate.

[0121] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A comprehensive intelligent perception protection safety system, characterized in that, The system includes a sensor array arranged around the transformer to collect acoustic signal data, temperature field data, and combustible gas concentration data in the transformer area. The sensor array includes acoustic sensors, temperature sensors, and combustible gas sensors installed in groups at the same measuring point. The temperature anomaly accumulation calculation module is communicatively connected to the sensor array. It is used to find areas in the temperature field data where the temperature value exceeds the background temperature value as temperature anomaly areas, and to calculate the cumulative value of the difference between the temperature value of each measuring point in the temperature anomaly area and the background temperature value as the temperature anomaly accumulation. The gas concentration accumulation calculation module is communicatively connected to the sensor array. It is used to find areas in the combustible gas concentration data where the concentration value exceeds the background concentration value as gas concentration anomaly areas, and to calculate the cumulative value of the difference between the concentration value of each measuring point in the gas concentration anomaly area and the background concentration value as the gas concentration accumulation. The acoustic energy integration calculation module is communicatively connected to the sensor array and is used to find periods in the acoustic signal data where the sound pressure value exceeds the background sound pressure value as acoustic abnormal events, and to calculate the time integral of the square of the sound pressure value during the acoustic abnormal event as the acoustic energy integral. The cross-field coupling judgment module is communicatively connected to the temperature anomaly accumulation calculation module, the gas concentration accumulation calculation module, and the acoustic energy integration calculation module, respectively. It is used to calculate the ratio of the temperature anomaly accumulation to the gas concentration accumulation as the cross-field accumulation ratio, and to calculate the ratio of the acoustic energy integration to the number of measuring points in the temperature anomaly area as the single-point acoustic energy value. When the cross-field accumulation ratio is within the range of the transformer oil calibration property ratio and the single-point acoustic energy value exceeds the calibration acoustic energy reference value, a transformer oil leakage judgment signal is output.

2. The all-around intelligent sensing and protection security system according to claim 1, characterized in that, The temperature anomaly accumulation calculation module includes: The background temperature calculation unit is used to calculate the arithmetic mean of the temperature values ​​of all measuring points in the temperature field data as the background temperature value Tb. The temperature anomaly area identification unit is used to identify measuring points whose temperature values ​​exceed the background temperature value Tb as temperature anomaly areas. The temperature anomaly cumulative output unit is used to subtract the temperature value Ti of the i-th measuring point in the temperature anomaly area from the background temperature value Tb point by point and then sum them up to output the temperature anomaly cumulative amount ST. The calculation formula is that ST is equal to the sum of the differences between Ti and Tb of all temperature anomaly measuring points.

3. The all-around intelligent sensing and protection security system according to claim 2, characterized in that, The gas concentration accumulation calculation module includes: The background concentration calculation unit is used to calculate the arithmetic mean of the concentration values ​​of all measuring points in the combustible gas concentration data as the background concentration value Cb. The gas concentration anomaly area identification unit is used to identify measuring points with concentration values ​​exceeding the background concentration value Cb as gas concentration anomaly areas. The gas concentration accumulation output unit is used to subtract the concentration value Cj of the j-th measuring point in the gas concentration anomaly area from the background concentration value Cb point by point and then sum them up to output the gas concentration accumulation SC. The calculation formula is that SC is equal to the sum of the differences between Cj and Cb of all gas concentration anomaly measuring points.

4. The all-around intelligent sensing and protection security system according to claim 3, characterized in that, The acoustic energy integration calculation module includes: The background sound pressure calculation unit is used to calculate the running average of the sound pressure values ​​at each sampling time in the acoustic signal data as the background sound pressure value Pb. An acoustic anomaly event identification unit is used to identify periods when the sound pressure value exceeds the background sound pressure value Pb as acoustic anomalies. The acoustic energy integration output unit is used to square the sound pressure value Pn at the nth sampling time during an acoustic anomaly event, multiply it by the sampling time interval dt, sum the products of all sampling times, and output the acoustic energy integral E. The calculation formula is that E is equal to the sum of the products of the squares of Pn at all acoustic anomaly sampling times and dt, where dt is equal to the reciprocal of the acoustic signal data sampling frequency fs.

5. The all-around intelligent sensing and protection security system according to claim 4, characterized in that, The cross-field coupling determination module includes: The calibration property ratio range storage unit is used to store the lower limit Rmin and upper limit Rmax of the calibration property ratio range of transformer oil; A calibration acoustic energy reference value storage unit is used to store the calibration acoustic energy reference value Eref; The cross-field cumulative ratio calculation unit is used to receive the temperature anomaly accumulation ST and the gas concentration accumulation SC, and calculate the cross-field cumulative ratio R, which is equal to the ratio of ST to SC. The single-point acoustic energy value calculation unit is used to receive the acoustic energy integral E and the number of measuring points MT in the temperature anomaly area, and calculate the single-point acoustic energy value Esingle, which is equal to the ratio of E to MT. The leakage detection output unit is used to compare R with Rmin and Rmax, and to compare Esingle with Eref. When R is greater than or equal to Rmin, R is less than or equal to Rmax, and Esingle is greater than or equal to Eref, a transformer oil leakage detection signal is output.

6. The all-around intelligent sensing and protection security system according to claim 5, characterized in that, The lower limit Rmin and upper limit Rmax in the calibrated property ratio interval storage unit are determined through the following steps: Conduct transformer oil leakage calibration tests on similar transformers. The number of calibration tests is recorded as N, and N shall be no less than three. In the kth calibration test, the known leakage flow rate is denoted as Qk, and Qk is controlled by a flow meter connected in the transformer oil circulation system pipeline; Calculate the cumulative temperature anomaly STk for the kth calibration according to the calculation method of the cumulative temperature anomaly calculation module; Calculate the cumulative gas concentration SCk for the kth calibration according to the calculation method of the cumulative gas concentration calculation module; Calculate the ratio of physical properties Rk for the kth calibration, where Rk is equal to the ratio of STk to SCk; The lower limit Rmin is the minimum value of Rk in N calibration tests, and the upper limit Rmax is the maximum value of Rk in N calibration tests.

7. The all-around intelligent sensing and protection security system according to claim 5, characterized in that, The calibration acoustic energy reference value Eref in the calibration acoustic energy reference value storage unit is determined through the following steps: In the calibration test, the k-th calibration acoustic energy integral Ek is calculated according to the calculation method of the acoustic energy integral calculation module; Count the number of measuring points Mk in the temperature anomaly area during the k-th calibration test; Calculate the single-point acoustic energy value Eksingle for the kth calibration, where Eksingle is equal to the ratio of Ek to Mk; The calibration acoustic energy reference value Eref is the minimum value among the Eksingle values ​​from N calibration tests.

8. The all-around intelligent sensing and protection security system according to claim 1, characterized in that, In the sensor array: Acoustic sensors, temperature sensors, and combustible gas sensors are installed in groups at the same measuring point; The spacing d between adjacent measuring points is determined by referring to the transformer fire protection design code based on the rated capacity S of the transformer. d is the required spacing value for the monitoring points corresponding to the rated capacity S in the code. Three sensors at the same measuring point receive the second pulse signal generated by the same clock source through a coaxial cable, and time synchronization is performed based on the rising edge of the second pulse signal, with a time synchronization accuracy of not less than 1 millisecond.

9. The all-around intelligent sensing and protection security system according to claim 8, characterized in that, Each sensor in the sensor array has a built-in analog-to-digital converter, and the analog signal is converted into a digital signal locally on the sensor. The digital signal is transmitted to the temperature anomaly accumulation calculation module, gas concentration accumulation calculation module and sound energy integration calculation module after being marked with a timestamp. The timestamp is based on the second pulse signal generated by a unified clock source.

10. The all-around intelligent sensing and protection security system according to claim 1, characterized in that, Also includes: The leakage level determination module is communicatively connected to the cross-field coupling judgment module. After receiving the transformer oil leakage judgment signal, it calculates the average temperature rise deltaT based on the average difference between the temperature value of each measuring point in the temperature abnormal area and the background temperature value output by the temperature abnormality accumulation calculation module. deltaT is equal to the sum of the differences between Ti and Tb of all temperature abnormal measuring points divided by the number of measuring points MT in the temperature abnormal area. The volume V of the temperature anomaly region is calculated based on the number of measuring points MT and the distance d between adjacent measuring points. V is equal to the product of MT and the cube of d. The leakage heat Q is calculated based on the average temperature rise deltaT, volume V, specific heat capacity c and density rho of transformer oil. Q is equal to the product of c, rho, V and deltaT. The leakage heat power P is calculated based on the leakage heat Q and the duration deltat of the temperature anomaly region. P is equal to the ratio of Q to deltat. The vaporization equivalent flow rate Qvap is calculated based on the leakage heat power P and the latent heat of vaporization Hvap of the transformer oil. Qvap is equal to the ratio of P to Hvap. The leakage rate L is calculated based on the vaporization equivalent flow rate Qvap and the total oil volume Vtotal of the transformer oil circulation system. L is equal to the ratio of Qvap to Vtotal. The leakage rate L is compared with the allowable leakage rate Lref, which is obtained from the technical data provided by the transformer manufacturer. When L is less than Lref, a low-level leakage signal is output; when L is greater than or equal to Lref, a medium-level leakage signal is output; when L is greater than or equal to Lref and Qvap exceeds the rated flow rate of the supplementary oil pump of the transformer oil circulation system, a high-level leakage signal is output.

Images