Transformer oil level monitoring device and system based on dual-mode ultrasonic sensor

Abstract

The application relates to the technical field of oil level monitoring, in particular to a transformer oil level monitoring device and system based on a dual-mode ultrasonic wave sensor. The system comprises the following steps: collecting transformer oil level and vibration acceleration; obtaining threshold difference through oil level comparison and dividing the oil level; obtaining an oil level anomaly comprehensive index based on different types of oil level fluctuation, quantity and interval; determining an oil level anomaly factor after screening an out-of-limit oil level, and obtaining an oil level anomaly value in combination with the oil level anomaly comprehensive index; determining a change time and a reaction time range based on the vibration acceleration; determining an acceleration oil level influence factor by analyzing correlation, and obtaining a fault characteristic value in combination with an interference factor; and monitoring the oil level through the fault characteristic value. The application improves the reliability of the whole monitoring system.

Description

Technical Field

[0001] This application relates to the field of oil level monitoring technology, specifically to a transformer oil level monitoring device and system based on dual-mode ultrasonic sensing. Background Technology

[0002] With the deepening of the construction of new power systems and the continuous improvement of power supply quality requirements, there is also a greater demand for the daily analysis and management of transformer oil levels in substations. Intelligent and digital operation and maintenance of power equipment has become a core requirement for ensuring the safe operation of the power grid. As the core equipment of the power system, transformers operate under complex conditions and in a variable environment. Their oil level status is directly related to insulation performance, heat dissipation efficiency, and equipment life. Real-time monitoring of transformer oil levels is particularly important and is a core link in ensuring the safe and stable operation of transformers. It helps to provide real-time early warning of fault risks and ensure the continuity of power supply.

[0003] When using ultrasonic sensors to monitor transformer oil levels, the transformer's own operating conditions, such as oil level fluctuations caused by vibration, can also lead to changes in oil level. If these factors are not taken into account, it can easily lead to errors in judging abnormal oil level data, thus failing to obtain a more accurate understanding of the transformer's operating status based on the oil level data, and affecting the reliability and effectiveness of transformer oil level monitoring. Summary of the Invention

[0004] To address the technical problem of inaccurate oil level monitoring, this application provides a transformer oil level monitoring device and system based on dual-mode ultrasonic sensing. The specific technical solution adopted is as follows:

[0005] In the first aspect, this application proposes a transformer oil level monitoring system based on dual-mode ultrasonic sensing, which includes the following modules:

[0006] The data acquisition module is used to collect transformer oil level and vibration acceleration.

[0007] The anomaly analysis module is used to compare the oil level with the preset oil level safety threshold to obtain the threshold difference; classify the oil level into different categories based on the threshold difference; obtain the comprehensive index of oil level anomaly based on the oil level fluctuation, quantity and interval of different categories; screen out oil levels that exceed the limit, determine the oil level anomaly factors, and combine the comprehensive index of oil level anomaly as the oil level anomaly value.

[0008] The fault analysis module is used to determine the moment of change and its reaction time range based on vibration acceleration; within the range, it determines the acceleration oil level influence factor by combining the correlation between threshold differences and vibration acceleration; it obtains the interference factor by combining the proportion of normal fluctuation oil level and threshold differences; and it obtains fault characteristic values ​​by combining abnormal oil level values.

[0009] The oil level detection module is used to identify faults by analyzing fault characteristic values ​​and to monitor the oil level.

[0010] In the above-mentioned scheme, this application uses a dual-mode ultrasonic sensor to monitor the transformer oil level. Based on the historical oil level data sequence, it determines the comprehensive index of oil level anomalies. Then, by combining the relationship between transformer vibration data and oil level over a historical period, it eliminates the interference of oil level changes caused by normal transformer operation on transformer fault judgment. Finally, it determines the possible fault characteristic values ​​of the transformer reflected by the oil level data over a historical period. Based on the fault characteristic values, it determines the transformer operating status and takes corresponding measures. This method can measure the transformer oil level more accurately, effectively improve measurement accuracy, reduce measurement errors, and analyze the measured historical oil level data to eliminate the interference of oil level anomalies caused by normal transformer operation vibration on faults, improve the accuracy of fault characteristic values, improve the reliability of the entire monitoring system, effectively reduce the workload of maintenance personnel, and improve work efficiency.

[0011] In one embodiment, the method for obtaining the threshold difference by comparing the oil level with a preset oil level safety threshold is as follows:

[0012] The oil level safety threshold includes an upper limit threshold and a lower limit threshold; the average of the upper limit threshold and the lower limit threshold is recorded as the median value.

[0013] The oil levels from the previous day are sorted to form an oil level sequence. When an oil level in the sequence is greater than the median value, the difference between the upper limit threshold and the median value is used as the threshold difference. When an oil level in the sequence is less than the median value, the difference between the median value and the lower limit threshold is used as the threshold difference.

[0014] In one embodiment, the method for classifying oil levels by the threshold difference is as follows:

[0015] When the threshold difference is less than or equal to the preset oil level threshold, the oil level is recorded as the warning oil level;

[0016] When the difference between the threshold and the preset oil level threshold is greater than the oil level threshold, the oil level is recorded as the normal oil level.

[0017] In one embodiment, the abnormal oil level comprehensive index is positively correlated with the fluctuation degree of the normal oil level and the proportion of the warning oil level in all oil levels; and negatively correlated with the maximum interval between the warning oil levels.

[0018] In one embodiment, the oil level anomaly factor is positively correlated with the proportion of out-of-limit oil levels in the indicated oil levels, the absolute value of the minimum threshold difference, and the out-of-limit difference of the out-of-limit oil levels; the out-of-limit difference is the difference between each out-of-limit oil level and the normal oil level most recent in the previous collection time; the out-of-limit oil level is the oil level with a negative threshold difference; and the minimum threshold difference is the minimum value of the threshold differences of all out-of-limit oil levels.

[0019] In one embodiment, the method for determining the moment of change and its reaction time range based on vibration acceleration is as follows:

[0020] The difference in vibration acceleration between each moment and the previous moment is used to represent the instantaneous rate of change at each moment; when the instantaneous rate of change is greater than a preset rate of change threshold, each moment is recorded as the moment of change; the preset moment before the moment of change is used as the reaction time range.

[0021] In one embodiment, the acceleration oil level influence factor is positively correlated with the number of change times and the correlation between threshold differences and vibration acceleration; the correlation is the correlation of the sequences formed by all threshold differences and vibration accelerations within the reaction time range.

[0022] In one embodiment, the interference factor is positively correlated with the proportion of normal fluctuation oil levels in the indicated oil levels, the threshold difference of normal fluctuation oil levels, and the acceleration oil level influence factor of normal fluctuation oil levels; the normal fluctuation oil level is the indicated oil level within the reaction time range when the acceleration oil level influence factor is greater than or equal to the influence threshold.

[0023] In one embodiment, the fault characteristic value is positively correlated with the abnormal oil level value and negatively correlated with the interference factor.

[0024] On the other hand, this application also provides a transformer oil level monitoring device based on dual-mode ultrasonic sensing, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements a module of the transformer oil level monitoring system based on dual-mode ultrasonic sensing described above.

[0025] The beneficial effects of this application are as follows:

[0026] This application uses a dual-mode ultrasonic sensor to monitor transformer oil levels. Based on historical oil level data sequences, it determines a comprehensive index of oil level anomalies. Then, by combining the relationship between transformer vibration data and oil levels over a historical period, it eliminates interference from oil level changes caused by normal transformer operation in fault diagnosis. Finally, it determines the potential fault characteristic values ​​of the transformer reflected by the historical oil level data. Based on these fault characteristic values, it determines the transformer's operating status and takes corresponding measures. This method can more accurately measure transformer oil levels, effectively improving measurement accuracy, reducing measurement errors, and analyzing the historical oil level data to eliminate interference from oil level anomalies caused by normal transformer operation vibrations, improving the accuracy of fault characteristic values, enhancing the reliability of the entire monitoring system, effectively reducing the workload of maintenance personnel, and improving work efficiency. Attached Figure Description

[0027] To more clearly illustrate the technical solutions and advantages in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a flowchart of a transformer oil level monitoring system based on dual-mode ultrasonic sensing, provided as an embodiment of this application. Detailed Implementation

[0029] To further illustrate the technical means and effects adopted by this application to achieve the intended purpose of the invention, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of the transformer oil level monitoring device and system based on dual-mode ultrasonic sensing proposed in this application. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0031] Example of a transformer oil level monitoring device and system based on dual-mode ultrasonic sensing:

[0032] The specific scheme of the transformer oil level monitoring system based on dual-mode ultrasonic sensing provided in this application is described in detail below with reference to the accompanying drawings.

[0033] Please see Figure 1 The diagram illustrates a flowchart of a transformer oil level monitoring system based on dual-mode ultrasonic sensing according to an embodiment of this application. The system includes the following modules:

[0034] The data acquisition module is used for transformer oil level monitoring based on dual-mode ultrasonic sensors. It needs to collect historical oil level data of the transformer, environmental parameters of the transformer, transformer operating parameters, and working status parameters of the ultrasonic sensors.

[0035] The ultrasonic measuring device is installed at a suitable location on top of the transformer oil conservator or tank, ensuring its transmitting surface is perpendicular to the oil surface. The ultrasonic measuring device generates ultrasonic pulse signals, which are amplified to drive the transmitting sensor. Simultaneously, the receiving sensor is activated to receive the echo signal. After signal processing including amplification, filtering, and shaping, the microcontroller measures the time difference between the transmitted and received signals, and then calculates the oil level based on temperature correction. In this embodiment, the oil level is acquired once per second.

[0036] The vibration acceleration sensor is installed at a critical location on the transformer casing; in this embodiment, it is installed in the middle of the tank wall. This allows for a better reflection of the overall vibration of the transformer; the data acquisition frequency is also once per second. The amplitude of the vibration acceleration data directly reflects the severity of the vibration; generally, a sensor with a range that can cover the maximum acceleration range that the transformer may generate and high sensitivity is selected.

[0037] The oil level and vibration acceleration were collected through the above steps and then normalized. In this embodiment, the maximum and minimum value normalization method was used.

[0038] At this point, the normalized oil level and vibration acceleration were obtained.

[0039] The anomaly analysis module is crucial because oil level fluctuations during transformer operation are closely related to the transformer's operating status. Fluctuations in oil level may indicate internal transformer faults. For example, when faults such as partial discharge or multi-point grounding of the core occur inside the transformer, a large amount of heat is generated, causing the oil temperature to rise rapidly and the oil level to rise sharply. Similarly, when a short circuit occurs in the transformer windings, the heat generated by the short-circuit current will also cause the oil temperature to rise instantaneously, the oil volume to expand rapidly, and the oil level to fluctuate significantly. In addition, faults in some transformer components can also lead to oil level fluctuations. For instance, aging or damage to seals can cause leakage, leading to a gradual decrease in oil level, while cooling system malfunctions can cause an increase in oil temperature and a rise in oil level. Therefore, by analyzing the fluctuations in historical oil level data, the operating status of equipment components can be inferred in a timely manner.

[0040] First, determine the safe oil level thresholds, including an upper and lower limit. When the oil level reaches or exceeds the upper limit, it indicates that the transformer oil level may be too high, possibly caused by problems such as cooling system failure, sudden load changes, or oil tank failure. When the oil level drops or falls below the lower limit, it means that the transformer oil is insufficient, possibly due to oil leakage or overcooling. Both excessively high and low oil levels will significantly affect transformer performance and threaten the safe and stable operation of the transformer. In this embodiment, the upper limit is 3 / 4 and the lower limit is 1 / 4. The values ​​for the upper and lower limits are within the conventional range for small and medium-sized oil-immersed power transformers.

[0041] For the current moment, sort all the oil levels from the previous day in chronological order to obtain the current oil level sequence; use the average of the upper and lower oil level thresholds as the median. For the obtained oil level sequence, determine its difference from the upper and lower oil level thresholds.

[0042] If the oil level in the oil level sequence is greater than the median value, the difference between the upper limit threshold and this value is used as the threshold difference. If the threshold difference is negative, it means that the upper limit threshold is less than the oil level in the oil level sequence, indicating that the oil level is higher than the upper limit threshold. When the oil level in the oil level sequence is less than the median value, the difference between this value and the lower limit threshold is used as the threshold difference. If the threshold difference is negative, it means that the lower limit threshold is greater than the oil level in the oil level sequence, indicating that the oil level is lower than the lower limit threshold.

[0043] This yields the threshold difference at each time point. All threshold differences are then arranged in time sequence to form a threshold difference sequence. The smaller the threshold difference, the closer the oil level is to, or even further away from, the upper or lower limit threshold at that time.

[0044] When the threshold difference is less than or equal to the preset oil level threshold, the oil level at that moment is considered to be close to the upper or lower limit threshold and is recorded as a warning oil level; when the threshold difference is greater than the preset oil level threshold, it is considered to be a normal oil level. This allows us to obtain the number of warning oil levels and normal oil levels; simultaneously, we can obtain the sequence number of the warning oil levels, and use the difference in sequence number between two adjacent warning oil levels as the interval between warning oil levels.

[0045] In the oil level sequence, an abnormal oil level comprehensive index is obtained based on the proportion of the indicated oil level in all oil levels, the maximum interval between indicated oil levels, and the degree of fluctuation of the normal oil level.

[0046] The abnormal oil level comprehensive index is positively correlated with the fluctuation degree of normal oil level and the proportion of warning oil levels in all oil levels; and negatively correlated with the maximum interval between warning oil levels.

[0047] It should be noted that positive correlation means that when one variable increases, the other variable also increases, and the two variables change in the same direction. When one variable changes from large to small or from small to large, the other variable also changes from large to small or from small to large. The specific relationship is determined by the actual application, and this application does not impose any special restrictions.

[0048] It should be noted that negative correlation means that when one variable increases, the other variable decreases accordingly, and the two variables change in opposite directions. When one variable changes from large to small or from small to large, the other variable also changes from small to large or from large to small. The specific relationship is determined by practical application, and this application does not impose any special restrictions.

[0049] Preferably, in this application, the expression for the comprehensive index of abnormal oil level is:

[0050] , This indicates the degree of fluctuation in the normal oil level within the oil level sequence. This indicates the number of oil levels indicated in the oil level sequence, c represents the total number of oil levels in the oil level sequence, and d represents the maximum interval between all indicated oil levels in the oil level sequence. This indicates a comprehensive index of abnormal oil levels.

[0051] It is worth noting that the smaller the fluctuation of the normal oil level, the more stable the normal oil level is; the smaller the maximum value of the interval between all the indicated oil levels in the oil level sequence, the closer and more continuous the intervals between all the oil levels close to the threshold are; the second half of the formula represents the distribution characteristics of the indicated oil levels; the larger the variance of the normal oil level, the larger the proportion of indicated oil levels, and the smaller the distribution interval, the more obvious the oil level anomaly is, and the larger the corresponding comprehensive index of oil level anomaly is, reflecting that the transformer oil level anomaly is more obvious, and it may be in an unstable and abnormal state.

[0052] Among all the moments that trigger the threshold mentioned above, there are moments that are close to the threshold and moments that exceed the threshold, that is, moments that are greater than the upper limit threshold or less than the lower limit threshold. These moments are also key to reflecting abnormal oil level data, so it is necessary to adjust the comprehensive index of abnormal oil level obtained above based on the distribution of these negative values.

[0053] In the above oil level sequence, the oil levels with negative threshold differences are recorded as over-limit oil levels. The number of all over-limit oil levels is determined, and the over-limit oil level corresponding to the minimum threshold difference is determined. The threshold difference of the over-limit oil level is recorded as the minimum threshold difference.

[0054] The difference between each out-of-limit oil level and its nearest normal oil level is determined and denoted as the out-of-limit difference, which is the absolute value of the oil level difference. The larger the value of the out-of-limit difference, the more rapidly the oil level changes from the normal state to the out-of-threshold state. This drastic change may indicate a sudden deterioration in the transformer's operating condition and may indicate a potential serious internal fault in the transformer. The smaller the value of the out-of-limit difference, the more gradually the oil level changes from the normal state to the out-of-threshold state, and the fault may be relatively minor.

[0055] Therefore, the oil level anomaly factor is determined based on the proportion of oil levels exceeding the limit in the indicated oil levels, the minimum threshold difference, and the difference in the limits of the oil levels exceeding the limit.

[0056] The oil level anomaly factor is positively correlated with the proportion of oil levels exceeding the limit in the indicated oil levels, the absolute value of the minimum threshold difference, and the difference in the limit of the oil levels exceeding the limit.

[0057] Preferably, the expression for the oil level anomaly factor is:

[0058] , This indicates the number of oil levels indicated in the oil level sequence. This indicates the number of oil levels exceeding the limit in the oil level sequence. This represents the minimum threshold difference in the oil level sequence; its absolute value indicates the maximum extent to which the oil level exceeds the threshold. This represents the mean difference in oil level exceedances within the oil level sequence. This indicates an abnormal oil level factor.

[0059] in, This indicates the maximum extent to which an oil level exceeds the threshold among all oil levels exceeding the limit. The larger the proportion of oil levels exceeding the limit in the alert oil levels, the greater the extent of the exceeding limit, and the faster the change to the exceeding limit, the more serious the oil level anomaly is, and the larger the corresponding oil level anomaly factor is.

[0060] The oil level anomaly value is obtained by adjusting the comprehensive index of oil level anomaly based on the oil level anomaly factor.

[0061] Preferably, in this embodiment, the oil level anomaly value is the product of the oil level anomaly factor and the oil level anomaly comprehensive index. A larger oil level anomaly value indicates a greater degree of oil level anomaly over a historical period, suggesting that the transformer may be in a severely abnormal state, with multiple complex faults potentially occurring simultaneously, requiring prompt repair. Conversely, a smaller oil level anomaly value indicates a lower degree of oil level anomaly, suggesting a relatively stable transformer operating condition.

[0062] At this point, the abnormal oil level value was obtained.

[0063] The fault analysis module obtains abnormal oil level values ​​from historical data through the above steps. The larger the value, the more likely the transformer is in an abnormal state.

[0064] However, during the monitoring and acquisition of oil level data, the transformer will vibrate during operation. This vibration may be transmitted to the oil, causing fluctuations in the oil level. These fluctuations can lead to uneven ultrasonic reflection interfaces when using ultrasonic sensors to monitor the oil level, resulting in unstable reflected signals received by the sensors. Consequently, the measured oil level data will also fluctuate. For example, when the transformer is operating under high load, the vibration will intensify, and the fluctuation amplitude of the oil level will increase, making it difficult to accurately reflect the actual oil level status. This affects the analysis of oil level data characteristics and makes the obtained abnormal oil level values ​​inaccurate.

[0065] For the current moment, obtain the acceleration sequence by sorting all the vibration accelerations of the previous day in chronological order.

[0066] In calculating the instantaneous rate of change of an acceleration sequence, which is the ratio of the difference between the vibration acceleration at the current moment and the previous moment to the time interval between the two moments, the difference between the current moment and the previous moment is used to represent the instantaneous rate of change at the current moment because the sampling frequency is fixed and the time interval between two adjacent data points is also consistent.

[0067] The preset rate of change threshold is C0. When the instantaneous rate of change at a certain moment is greater than the rate of change threshold, it is considered that the vibration acceleration at that moment has increased significantly compared with the previous moment, and it is recorded as a moment of change. If the instantaneous rate of change at a certain moment is less than the rate of change threshold, it is considered that the vibration rate of change has not changed much, and it is recorded as a steady moment.

[0068] A significant increase in vibration acceleration may cause oil level fluctuations, which in turn affect the oil level data. Therefore, for each moment of change, a preset number of moments prior to it is used as its reaction time range; in this embodiment, the reaction time range is 5 moments.

[0069] Within the reaction time range of each change moment, determine whether there is an abnormal oil level, i.e., an alert oil level. If there is one or more alert oil levels within the reaction time, it indicates that these abnormal oil levels may be caused by a significant increase in vibration acceleration.

[0070] Within the reaction time range of each change moment, the acceleration sequence and threshold difference sequence are acquired, and their correlation is calculated. In this embodiment, the correlation is calculated using the Pearson correlation coefficient. The larger the correlation, the greater the deviation of the oil level from the threshold caused by the change in vibration acceleration within that time period, and the more likely the indicated oil level within that time period is caused by the change in vibration acceleration.

[0071] The acceleration oil level influence factor is obtained based on the number and correlation of changes in the reaction time range.

[0072] The acceleration oil level influence factor is positively correlated with the number of time points of change and the correlation.

[0073] Preferably, the expression for the acceleration oil level influence factor is:

[0074] , This indicates the number of moments of change within the reaction time range. Indicates the correlation of reaction time range. This represents the acceleration-oil level influence factor over the reaction time range. Among them, The larger the value of and the stronger the correlation between the two, the larger the corresponding value of D, indicating that the oil level warning during this period is mainly caused by a significant increase in vibration acceleration.

[0075] The acceleration-induced oil level influence factor is determined at each moment of change and normalized. If the acceleration-induced oil level influence factor is greater than or equal to a preset influence threshold, the indicated oil level within the reaction time range at that moment is considered to be mainly caused by changes in vibration acceleration, which is a normal change during operation. The indicated oil level appearing within the reaction time range at that moment is recorded as a vibration-related normal fluctuation oil level. Conversely, if the acceleration-induced oil level influence factor is less than the preset influence threshold, it indicates that the mutual influence between vibration acceleration and oil level changes is low. In this embodiment, the preset influence threshold is set to 0.7.

[0076] The acceleration oil level influence factor within the reaction time range at the change moment is used as the acceleration oil level influence factor for each normal fluctuation oil level within the reaction time range.

[0077] Based on the above steps, all vibration-related normal fluctuation oil levels are screened from all indicated oil levels. These oil levels are mainly caused by vibration changes during normal transformer operation and cannot well reflect oil level anomalies caused by other possible faults, such as oil leakage, oil tank failure, cooling system failure, etc. Therefore, it is necessary to eliminate the interference of oil level changes caused by normal vibration on transformer fault judgment based on the distribution characteristics of these normal fluctuation oil levels and the oil level anomaly values ​​obtained above, and finally determine the probability of transformer faults reflected by oil level data in historical time period.

[0078] The number of all normally fluctuating oil levels is counted. Based on the proportion of normally fluctuating oil levels in the alert oil levels, the threshold difference of normally fluctuating oil levels, and the acceleration oil level influence factor of normally fluctuating oil levels, the interference factor is determined.

[0079] The interference factors are positively correlated with the proportion of normal fluctuation oil level in the indicated oil level, the threshold difference of normal fluctuation oil level, and the acceleration oil level influence factor of normal fluctuation oil level.

[0080] Preferably, the expression for the interference factor is:

[0081] , This indicates the number of normally fluctuating oil levels in the oil level sequence. This indicates the number of oil levels indicated in the oil level sequence. This represents the mean threshold difference among all normally fluctuating oil levels in the oil level sequence. This represents the mean of the acceleration factor affecting all normally fluctuating oil levels in the oil level series. This represents the interference factor in the oil level sequence.

[0082] Among them, the larger the proportion of normal fluctuation oil level, the greater the difference between it and the threshold, and the stronger the interaction with vibration acceleration, the greater the corresponding interference factor, which means the greater the interference on the judgment of oil level fault.

[0083] The fault characteristic values ​​of the transformer are determined based on the abnormal oil level and interference factors.

[0084] The fault characteristic values ​​are positively correlated with abnormal oil levels and negatively correlated with interference factors.

[0085] Preferably, the expression for the fault characteristic value is:

[0086] , This represents the outlier values ​​in the oil level sequence. Indicates the interference factor of the oil level sequence. Represents the normalization function. This represents the fault characteristic value of the transformer.

[0087] The larger the interference factor, the less accurate the judgment of oil level anomalies, and the smaller the fault characteristic value obtained for oil levels with normal fluctuations. The larger the oil level anomaly value, the more likely there is an oil level anomaly, the more likely the transformer is to fail, and the larger the fault characteristic value.

[0088] Thus, the fault characteristic values ​​of the transformer were obtained.

[0089] The oil level detection module obtains the transformer's fault characteristic value through the above steps. The larger the fault characteristic value, the greater the possibility of a transformer failure and the more severe the failure. The smaller the fault characteristic value, the less likely the transformer is to fail, and the failure may be minor or nonexistent.

[0090] The fault characteristic value is normalized to the range of 0-1. When the normalized fault characteristic value is greater than or equal to the fault threshold, it is considered that the transformer is likely to be faulty. At this time, professional technicians need to conduct inspections to promptly identify potential faults and take corrective measures. When the fault characteristic value is less than the fault threshold, routine monitoring can continue, and regular maintenance can be carried out to prevent faults from occurring. In this embodiment, the fault threshold is 0.6.

[0091] Based on the same inventive concept as the above method, this embodiment of the invention also provides a transformer oil level monitoring device based on dual-mode ultrasonic sensing, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements any of the modules of the above-described transformer oil level monitoring system based on dual-mode ultrasonic sensing.

[0092] It should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

[0093] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A transformer oil level monitoring system based on dual-mode ultrasonic sensing, characterized in that, The system comprises the following modules: A data acquisition module for acquiring transformer oil level and vibration acceleration; An abnormality analysis module for comparing the oil level with a preset oil level safety threshold to obtain a threshold difference; dividing the oil level into different categories through the threshold difference; obtaining an oil level abnormality comprehensive index based on the different categories of oil level fluctuations, quantity and interval; screening an over-limit oil level, determining an oil level abnormality factor, and combining the oil level abnormality comprehensive index as an oil level abnormal value; when the threshold difference is less than or equal to the preset oil level threshold, the oil level is recorded as a prompt oil level; when the threshold difference is greater than the preset oil level threshold, the oil level is recorded as a normal oil level; the over-limit oil level is an oil level with a negative threshold difference; A fault analysis module for determining a change time and its reaction time range according to the vibration acceleration; determining an acceleration oil level influence factor in the range in combination with the correlation of the threshold difference and the vibration acceleration; obtaining an interference factor in combination with the number ratio of the normal fluctuation oil level in the prompt oil level and the threshold difference of the normal fluctuation oil level; obtaining a fault characteristic value in combination with the oil level abnormal value; An oil level detection module for judging faults through the fault characteristic value and monitoring the oil level; The method for determining the change time and its reaction time range according to the vibration acceleration is: The difference between the vibration acceleration of each time and the previous time is used to represent the instantaneous change rate of each time; when the instantaneous change rate is greater than a preset change rate threshold, each time is recorded as a change time; a preset time before the change time is taken as the reaction time range.

2. The dual-mode ultrasonic sensor based transformer oil level monitoring system as claimed in claim 1, wherein, The method for obtaining the threshold difference by comparing the oil level with a preset oil level safety threshold is: The oil level safety threshold includes an upper limit threshold of the oil level and a lower limit threshold of the oil level; the average of the upper limit threshold of the oil level and the lower limit threshold of the oil level is recorded as an intermediate value; The oil levels of the previous day before the current time are sorted to form an oil level sequence; when the oil level in the oil level sequence is greater than the intermediate value, the difference between the upper limit threshold and the value is taken as the threshold difference; when the oil level in the oil level sequence is less than the intermediate value, the difference between the value and the lower limit threshold of the oil level is taken as the threshold difference.

3. The dual-mode ultrasonic sensor based transformer oil level monitoring system as claimed in claim 1, wherein, The oil level abnormality comprehensive index is positively correlated with the fluctuation degree of the normal oil level and the number ratio of the prompt oil level in all oil levels; and is negatively correlated with the maximum interval between the prompt oil levels.

4. The dual-mode ultrasonic sensor based transformer oil level monitoring system as claimed in claim 1, wherein, The oil level abnormality factor is positively correlated with the number ratio of the over-limit oil level in the prompt oil level, the absolute value of the minimum threshold difference, and the over-limit difference of the over-limit oil level; the over-limit difference is the difference between each over-limit oil level and the nearest normal oil level at its previous acquisition time; the minimum threshold difference is the minimum value of the threshold differences of all over-limit oil levels.

5. The dual-mode ultrasonic sensor based transformer oil level monitoring system as claimed in claim 1, wherein, The acceleration oil level influence factor is positively correlated with the number of change times and the correlation of the threshold difference and the vibration acceleration; the correlation is the correlation of the sequences respectively formed by all threshold differences and vibration accelerations within the reaction time range.

6. The dual-mode ultrasonic sensor-based transformer oil level monitoring system as claimed in claim 1, wherein, The interference factor is positively correlated with the number ratio of the normal fluctuation oil level in the prompt oil level, the threshold difference of the normal fluctuation oil level, and the acceleration oil level influence factor of the normal fluctuation oil level; The normal fluctuation oil level is a prompt oil level within the reaction time range when the acceleration oil level influence factor is greater than or equal to an influence threshold.

7. The dual-mode ultrasonic sensor based transformer oil level monitoring system as claimed in claim 1, wherein, The fault characteristic value is positively correlated with the oil level abnormal value and negatively correlated with the interference factor.

8. A transformer oil level monitoring device based on dual-mode ultrasonic sensing, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, The processor implements the modules of the transformer oil level monitoring system based on the dual-mode ultrasonic sensor according to any one of claims 1-7 when executing the computer program.

Images