A method and system for detecting bushing discharge faults in transformers

Abstract

The present invention discloses a method and system for detecting bushing discharge faults of a transformer. The method for detecting bushing discharge faults of a transformer according to the present invention includes: S1, determining the number of bushing discharge events occurring in the bushing of the transformer within a specified detection period; S2, judging whether the ratio of the number of bushing discharge events to the total number of detections within the detection period exceeds a set value. If it exceeds the set value, it is determined that the bushing of the transformer has a discharge fault. The present invention has the advantages of not requiring the transformer to be powered off, not requiring contact with live equipment, high detection safety, and convenient testing. Moreover, the method for judging the bushing discharge fault of the transformer according to the present invention can be conveniently combined with the Internet of Things and information technology, and can realize real-time monitoring and early warning of the bushing discharge state of the transformer, which is beneficial to improving the intelligent operation and maintenance level and safe operation level of the transformer.

Description

Technical Field

[0001] The present invention relates to the technology of transformer condition monitoring and fault diagnosis, and particularly to a method and system for detecting bushing discharge faults of transformers. Background Art

[0002] The bushing is an important link for power transmission connecting the transformer winding and the external high-voltage bus. However, accidents such as transformer tripping or burning caused by bushing discharge faults of transformers occur from time to time, resulting in large-scale power outages, bringing huge economic losses, and posing a great threat to the personal safety of staff. Therefore, it is of great significance to carry out bushing discharge monitoring of transformers, eliminate potential faults, and ensure the safe operation of transformers.

[0003] At present, the operation state detection of transformer bushings mostly still adopts planned maintenance mainly based on manpower. Although faults can be largely eliminated and potential hazards can be removed by regularly detecting and maintaining transformer bushings, the transformer needs to be shut down, there are safety risks in the detection process, and the detection period is long and the detection cost is relatively high. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: aiming at the above problems of the prior art, to provide a method and system for detecting bushing discharge faults of transformers that do not require the transformer to be powered off, do not require contact with live equipment, have high detection safety, and are convenient for testing.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for detecting bushing discharge faults of transformers includes:

[0007] S1. Determine the number of bushing discharge events that occur in the specified detection period of the transformer bushing;

[0008] S2. Judge whether the proportion of the number of bushing discharge events to the total number of detections in the detection period exceeds a set value. If it exceeds the set value, it is determined that the transformer bushing has a discharge fault.

[0009] Optionally, step S1 includes:

[0010] S1.1. Collect the sound signal of the bushing of the transformer to be detected and calculate the discharge characteristic parameters;

[0011] S1.2. Judge whether a bushing discharge event occurs based on whether the discharge characteristic parameters exceed the limit;

[0012] S1.3. Judge whether the number of detections that have been completed is equal to the total number of detections in a detection period. If it is equal to the total number of detections in a detection period, jump to step S2; otherwise, jump to step S1.4;

[0013] S1.4. Perform timing. If the timing duration is equal to the set interval time between adjacent detection times, jump to step S1.1; otherwise, continue waiting for timing.

[0014] Optionally, when collecting the bushing sound signal of the transformer to be detected in step S1.1, the microphone used is a microphone with a frequency range covering 20 Hz to 100 kHz and having directivity.

[0015] Optionally, the microphone is installed on the top of the transformer's oil tank.

[0016] Optionally, calculating the discharge characteristic parameter in step S1.1 means calculating the energy proportion of the frequency band above 10 kHz in the sound signal.

[0017] Optionally, step S1.2 includes: judging whether the discharge characteristic parameter exceeds the preset discharge characteristic parameter threshold. If it exceeds the preset discharge characteristic parameter threshold, it is determined that a bushing discharge event has occurred; otherwise, it is determined that no bushing discharge event has occurred.

[0018] Optionally, the determination steps of the preset discharge characteristic parameter threshold include: (1) When no discharge fault occurs in the bushing of the transformer, collect the bushing sound signal of the transformer to be detected and calculate the discharge characteristic parameter to obtain the normal state discharge characteristic parameter set {F n (i)}, where i = 1, 2,..., k, and k is the number of samples of the bushing sound signal of the transformer to be detected collected when no discharge fault occurs in the bushing of the transformer; when a discharge fault occurs in the bushing of the transformer, collect the bushing sound signal of the transformer to be detected and calculate the discharge characteristic parameter to obtain the fault state discharge characteristic parameter set {F a (i)}, where i = 1, 2,..., m, and m is the number of samples of the bushing sound signal of the transformer to be detected collected when a discharge fault occurs in the bushing of the transformer; (2) Judge whether there is an intersection between the normal state discharge characteristic parameter set {F n (i)} and the fault state discharge characteristic parameter set {F a (i)}. If there is no intersection, sort the fault state discharge characteristic parameter set {F a (i)} from small to large, and select the specified number of the top-ranked fault state discharge characteristic parameters and take the average value as the preset discharge characteristic parameter threshold. If there is an intersection, take the average value of the fault state discharge characteristic parameters within the intersection interval of the normal state discharge characteristic parameter set {F n (i)} and the fault state discharge characteristic parameter set {F a (i)} as the preset discharge characteristic parameter threshold.

[0019] Optionally, the total number of detections within one detection cycle in step S1.3 is greater than or equal to 60, and the set interval time between adjacent detection times in step S1.4 is greater than or equal to 30 minutes.

[0020] In addition, the present invention also provides a bushing discharge fault detection system for a transformer, including a microprocessor and a memory connected to each other, and the microprocessor is programmed or configured to execute the steps of the bushing discharge fault detection method for the transformer.

[0021] In addition, the present invention also provides a computer-readable storage medium, in which a computer program is stored, and the computer program is used to be programmed or configured by a microprocessor to execute the steps of the bushing discharge fault detection method for the transformer.

[0022] Compared with the prior art, the present invention mainly has the following advantages:

[0023] 1. By acquiring the sound signal of the bushing of the transformer to be detected, calculating the discharge characteristic parameters according to the sound signal of the bushing of the transformer to be detected, comparing the discharge characteristic parameters with the preset attention threshold of the discharge characteristic parameters, if the discharge characteristic parameters do not exceed the preset attention threshold of the discharge characteristic parameters, it is determined that the bushing of the transformer is in a normal state, otherwise, a bushing discharge event of the transformer is recorded. The sound signals of the bushing of the transformer are continuously detected multiple times and the discharge characteristic parameters are calculated, and the proportion of the bushing discharge events of the transformer is calculated. If the proportion exceeds the preset proportion threshold, it is determined that there is a discharge fault in the bushing of the transformer, otherwise, it is determined that the bushing of the transformer operates normally. It has the advantages of not requiring the transformer to be powered off, not requiring contact with live equipment, high detection safety, and convenient testing.

[0024] 2. The method for judging the bushing discharge fault of the present invention can be conveniently combined with the Internet of Things and information technology, and can realize the real-time monitoring and early warning of the discharge state of the bushing of the transformer, which is beneficial to improving the intelligent operation and maintenance level and the safe operation level of the transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the basic process of the method of the embodiment of the present invention.

[0026] Figure 2 It is a schematic diagram of the process of step S1 in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] As Figure 1 shown, the bushing discharge fault detection method for a transformer in this embodiment includes:

[0028] S1. Determine the number of bushing discharge events that occur in the bushing of the transformer within a specified detection cycle;

[0029] S2. Determine whether the ratio of the number of bushing discharge events to the total number of detections within the detection period exceeds a set value. If it exceeds the set value, it is determined that a discharge fault has occurred in the bushing of the transformer.

[0030] As Figure 2 shown, step S1 of this embodiment includes:

[0031] S1.1. Collect the bushing sound signal of the transformer to be detected and calculate the discharge characteristic parameters;

[0032] S1.2. Determine whether a bushing discharge event has occurred based on whether the discharge characteristic parameters exceed the limit;

[0033] S1.3. Determine whether the number of detections completed is equal to the total number of detections within a detection period. If it is equal to the total number of detections within a detection period, jump to step S2; otherwise, jump to step S1.4;

[0034] S1.4. Start timing. If the timing time is equal to the set interval time between adjacent detection times, jump to step S1.1; otherwise, continue to wait for timing.

[0035] In this embodiment, when collecting the bushing sound signal of the transformer to be detected in step S1.1, the microphone used is a microphone with a frequency range covering 20 Hz to 100 kHz and having directivity. Since there are differences in the frequency band ranges of the sound signals generated in different stages of the transformer bushing discharge fault, but they cover both the audible sound and ultrasonic frequency bands at the same time, therefore, the frequency band range of the microphone is preferably 20 Hz to 100 kHz. Since the sound environment around the transformer is complex, the bushing discharge sound signal is mixed with the sounds of the transformer body and the cooling fan, so the microphone needs to have directivity to be able to detect the sound at the bushing position specifically and reduce the interference of external factors as much as possible. Preferably, the microphone should have rain and wind protection measures to meet the requirements of long-term outdoor monitoring. In this embodiment, the microphone is installed on the top of the transformer oil tank. Since the bushing discharge occurs outside the bushing, installing the microphone on the top of the transformer oil tank can improve the accuracy of collecting the bushing sound signal of the transformer to be detected.

[0036] In this embodiment, calculating the discharge characteristic parameters in step S1.1 means calculating the energy ratio of the frequency band above 10 kHz in the sound signal. The specific calculation includes obtaining the frequency spectrum distribution by performing a Fourier transform on the discharge sound signal, and calculating the energy ratio of the frequency band above 10 kHz in the sound signal according to the following formula:

[0037]

[0038] In the above formula, R represents the energy ratio of the frequency band above 10 kHz in the sound signal, N is the total number of frequency points of the Fourier transform frequency spectrum, pi is the amplitude of the i-th frequency point of the Fourier transform spectrum, and p j is the amplitude of the j-th frequency point of the Fourier transform spectrum, and k is the position of the frequency point corresponding to 10 kHz in the Fourier transform spectrum. It is found through testing that by calculating the energy ratio of the frequency band above 10 kHz as the discharge characteristic parameter, it is possible to accurately determine whether a discharge event occurs in the bushing, and the calculation is relatively simple, which can be achieved through Fourier transform and simple calculations.

[0039] In this embodiment, step S1.2 includes: determining whether the discharge characteristic parameter exceeds the preset discharge characteristic parameter threshold. If it exceeds the preset discharge characteristic parameter threshold, it is determined that a bushing discharge event has occurred; otherwise, it is determined that no bushing discharge event has occurred.

[0040] In this embodiment, the steps for determining the preset discharge characteristic parameter threshold include: (1) When the bushing of the transformer does not have a discharge fault, collect the sound signal of the bushing of the transformer to be detected and calculate the discharge characteristic parameter to obtain the normal state discharge characteristic parameter set {F n (i)}, where i = 1, 2,..., k, and k is the number of samples of the sound signal of the bushing of the transformer to be detected collected when the bushing of the transformer does not have a discharge fault; when the bushing of the transformer has a discharge fault, collect the sound signal of the bushing of the transformer to be detected and calculate the discharge characteristic parameter to obtain the fault state discharge characteristic parameter set {F a (i)}, where i = 1, 2,..., m, and m is the number of samples of the sound signal of the bushing of the transformer to be detected collected when the bushing of the transformer has a discharge fault; (2) Determine whether there is an intersection between the normal state discharge characteristic parameter set {F n (i)} and the fault state discharge characteristic parameter set {F a (i)}. If there is no intersection, sort the fault state discharge characteristic parameter set {F a (i)} from small to large, and select the mean value of the specified number of the leading fault state discharge characteristic parameters as the preset discharge characteristic parameter threshold. If there is an intersection, take the mean value of the fault state discharge characteristic parameters within the intersection interval of the normal state discharge characteristic parameter set {F n (i)} and the fault state discharge characteristic parameter set {F a (i)} as the preset discharge characteristic parameter threshold. Specifically, assume that the numerical distribution of the normal state discharge characteristic parameter set {F n (i)} is between 0.001 and 0.02, and the numerical distribution of the fault state discharge characteristic parameter set {F a (i)} is between 0.03 and 0.4. Therefore, the normal state discharge characteristic parameter set {F n (i)} and the fault state discharge characteristic parameter set {F a(i) If there is an intersection, then for the set of discharge characteristic parameters {F in the fault state a (i), sort them from small to large. Assume that the data range of the first 15% is 0.03 - 0.04, and the average value of the first 15% of the data is 0.036. Then take 0.036 as the preset threshold of the discharge characteristic parameter. Assume the set of discharge characteristic parameters {F in the normal state n (i) has a numerical distribution between 0.001 - 0.03, and the set of discharge characteristic parameters {F in the fault state a (i) has a numerical distribution between 0.02 - 0.4. Then the set of discharge characteristic parameters {F in the normal state n (i) and the set of discharge characteristic parameters {F in the fault state a (i) have an intersection. Assume the data range of the intersection is 0.02 - 0.03, and the average value of the data within the intersection is 0.026. Then take 0.026 as the preset threshold of the discharge characteristic parameter.

[0041] Generally speaking, the total number of detections within one detection cycle in step S1.3 is greater than or equal to 60, and the set interval time between adjacent detection times in step S1.4 is greater than or equal to 30 minutes. As a specific implementation manner, in this embodiment, the total number of detections within one detection cycle in step S1.3 is 72 times, and the set interval time between adjacent detection times in step S1.4 is 1 hour.

[0042] When judging whether the proportion of the number of times of the bushing discharge event in step S2 compared to the total number of detections within the detection cycle exceeds the set value, the set value can be selected as needed. For example, as a specific implementation manner, the set value in this embodiment is taken as 83%, that is, judge whether the proportion of the number of times of the bushing discharge event compared to the total number of detections within the detection cycle exceeds 83%. If it exceeds 83%, it is determined that the bushing of the transformer has a discharge fault; otherwise, it is determined that the bushing of the transformer has not had a discharge fault. For example, in this embodiment, the number of discharge events found within one detection cycle is 60 times, and the discharge event proportion is 83.3%. The event proportion exceeds the preset proportion threshold of 83%. Therefore, it is determined that there is a discharge fault in the transformer bushing.

[0043] When the sleeve discharge fault detection method for a transformer in this embodiment is specifically implemented, it is realized through a computer program. The system for judging the sleeve discharge fault of a transformer realized through a computer program includes: a sound detection unit for detecting the sound signal of the transformer sleeve; a sound characteristic parameter calculation unit for calculating the sound characteristic parameters according to the sleeve sound signal; a discharge fault judgment unit for comparing the discharge characteristic parameters with a preset discharge characteristic parameter attention threshold to judge whether it is a transformer sleeve discharge event. If it is a discharge event, the sound signal of the transformer sleeve is continuously detected multiple times and the discharge characteristic parameters are calculated, and the proportion of the transformer sleeve discharge events is calculated. If the event proportion exceeds the preset proportion threshold, it is judged that there is a discharge fault in the transformer sleeve, otherwise it is judged that the transformer sleeve is operating normally.

[0044] In summary, the method of this embodiment has the following advantages: (1) By obtaining the sound signal of the transformer sleeve to be detected, calculating the discharge characteristic parameters according to the sound signal of the transformer sleeve to be detected, and comparing the discharge characteristic parameters with a preset discharge characteristic parameter attention threshold. If the discharge characteristic parameters do not exceed the preset discharge characteristic parameter attention threshold, it is determined that the transformer sleeve is in a normal state, otherwise a transformer sleeve discharge event is recorded. The sound signal of the transformer sleeve is continuously detected multiple times and the discharge characteristic parameters are calculated, and the proportion of the transformer sleeve discharge events is calculated. If the proportion exceeds the preset proportion threshold, it is judged that there is a discharge fault in the transformer sleeve, otherwise it is judged that the transformer sleeve is operating normally. It has the advantages of not requiring the transformer to be powered off, not requiring contact with live equipment, high detection safety, and convenient testing. (2) The method for judging the sleeve discharge fault of a transformer in this embodiment can be easily combined with the Internet of Things and information technology, and can realize real-time monitoring and early warning of the discharge state of the transformer sleeve, which is beneficial to improving the intelligent operation and maintenance level and safe operation level of the transformer.

[0045] In addition, this embodiment also provides a sleeve discharge fault detection system for a transformer, including a microprocessor and a memory connected to each other. The microprocessor is programmed or configured to execute the steps of the aforementioned sleeve discharge fault detection method for a transformer. The system for judging the sleeve discharge fault of a transformer in the present invention is a system completely corresponding to the method for judging the sleeve discharge fault of a transformer in the present invention. Therefore, it also has the aforementioned advantages of the method for judging the sleeve discharge fault of a transformer in the present invention, which will not be elaborated here.

[0046] In addition, this embodiment also provides a computer-readable storage medium, in which a computer program is stored. The computer program is used to be programmed or configured by a microprocessor to execute the steps of the aforementioned sleeve discharge fault detection method for a transformer.

[0047] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-readable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, as well as the combination of flows and / or blocks in the flowchart and / or block diagram. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in the process Figure 1 one process or multiple processes and / or blocks Figure 1 These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device that implements the functions specified in the process Figure 1 one process or multiple processes and / or blocks Figure 1 These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in the process Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0048] The above are only the preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements should also be regarded as within the protection scope of the present invention.

Claims

1. A method for detecting bushing discharge faults in a transformer, characterized in that, Including: S1. Determine the number of bushing discharge events that occur in the bushing of the transformer within a specified detection period; S2. Judge whether the proportion of the number of bushing discharge events compared to the total number of detections within the detection period exceeds a set value. If it exceeds the set value, it is determined that the bushing of the transformer has a discharge fault; Step S1 includes: S1.

1. Collect the sound signal of the bushing of the transformer to be detected and calculate the discharge characteristic parameters; S1.

2. Determine whether a bushing discharge event has occurred based on whether the discharge characteristic parameters exceed the limit; S1.

3. Judge whether the number of detections completed is equal to the total number of detections within a detection period. If it is equal to the total number of detections within a detection period, jump to step S2; otherwise, jump to step S1.4; S1.

4. Perform timing. If the timing time is equal to the set interval time between adjacent detections, jump to step S1.1; otherwise, continue to wait for timing.

2. The method for detecting bushing discharge faults in a transformer according to claim 1, characterized in that, When collecting the sound signal of the bushing of the transformer to be detected in step S1.1, the microphone used is a microphone with a frequency range covering 20 Hz to 100 kHz and having directivity.

3. The method for detecting bushing discharge faults in a transformer according to claim 2, characterized in that, The microphone is installed on the top of the transformer oil tank.

4. The method for detecting bushing discharge faults in a transformer according to claim 1, characterized in that, Calculating the discharge characteristic parameters in step S1.1 means calculating the energy proportion of the frequency band above 10 kHz in the sound signal.

5. The method for detecting bushing discharge faults in a transformer according to claim 1, characterized in that, Step S1.2 includes: Judge whether the discharge characteristic parameters exceed the preset discharge characteristic parameter threshold. If they exceed the preset discharge characteristic parameter threshold, it is determined that a bushing discharge event has occurred; otherwise, it is determined that no bushing discharge event has occurred.

6. The method for detecting bushing discharge faults in a transformer according to claim 5, characterized in that, The steps for determining the preset discharge characteristic parameter threshold include: (1) When there is no discharge fault in the bushing of the transformer, collect the bushing sound signal of the transformer to be detected and calculate the discharge characteristic parameters to obtain the normal state discharge characteristic parameter set { F n ( i )}, where i = 1, 2, …, k ,, k is the number of samples of the bushing sound signal of the transformer to be detected collected when there is no discharge fault in the bushing of the transformer; When there is a discharge fault in the bushing of the transformer, collect the bushing sound signal of the transformer to be detected and calculate the discharge characteristic parameters to obtain the fault state discharge characteristic parameter set { F a ( i )}, where i = 1, 2, …, m ,, m is the number of samples of the bushing sound signal of the transformer to be detected collected when there is a discharge fault in the bushing of the transformer; (2) Judge whether there is an intersection between the normal state discharge characteristic parameter set { F n ( i )} and the fault state discharge characteristic parameter set { F a ( i )}. If there is no intersection, sort the fault state discharge characteristic parameter set { F a ( i )} from small to large, and select the specified number of the front fault state discharge characteristic parameters to take the average value as the preset discharge characteristic parameter threshold. If there is an intersection, take the average value of the fault state discharge characteristic parameters within the intersection interval of the normal state discharge characteristic parameter set { F n ( i )} and the fault state discharge characteristic parameter set { F a ( i )} as the preset discharge characteristic parameter threshold.

7. The method for detecting bushing discharge faults in a transformer according to claim 1, characterized in that, The total number of detections within a detection period in step S1.3 is greater than or equal to 60, and the set interval time between adjacent detections in step S1.4 is greater than or equal to 30 minutes.

8. A system for detecting bushing discharge faults in a transformer, comprising a microprocessor and a memory connected to each other, characterized in that, The microprocessor is programmed or configured to execute the steps of the method for detecting bushing discharge faults of the transformer according to any one of claims 1 to 7.

9. A computer-readable storage medium, in which a computer program is stored, characterized in that, The computer program is used to be programmed or configured by the microprocessor to execute the steps of the method for detecting bushing discharge faults of the transformer according to any one of claims 1 to 7.

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