Ultrasonic propagation-based creeping discharge stage judgment device and method

Abstract

The invention relates to a surface discharge stage judgment device and method based on ultrasonic propagation, and the method comprises the steps: simulating a surface discharge phenomenon with an insulation fault, and generating various characteristic parameter changes of an insulation fault surface discharge electric signal; various characteristic parameter change signals of the sound signals caused by insulation fault surface discharge electric signal changes are obtained in real time, the influence of a sound propagation path on the sound signals is combined, the various characteristic parameter change signals are converted into computable data, and characteristic data are extracted; and the creeping discharge stage judgment module judges the creeping discharge stage of the insulation fault in combination with the detection data obtained by the ultrasonic propagation detection module and the oscilloscope. Compared with the prior art, the method has the advantages that the ultrasonic propagation influence is considered, and accurate and reliable judgment of the creeping discharge stage is realized based on various characteristic parameter changes of the acoustic signal caused by various characteristic parameter changes of the creeping discharge signal.

Description

Technical Field

[0001] The invention relates to the technical field of partial discharge of high-voltage insulating transformers, and in particular to a device and method for judging the stage of surface discharge based on ultrasonic propagation. Background Art

[0002] Whether power equipment can operate safely and reliably in the power system determines the stable operation of the power system. During the manufacturing and operation of power equipment, insulation defects may occur, and local discharge may occur at the defective parts during operation. Long-term local discharge will expand the scope of insulation defects, accelerate insulation aging, and in severe cases, cause insulation breakdown of power equipment. Surface discharge is a type of local discharge, which refers to the discharge phenomenon that occurs at the interface between different media such as solid (or liquid) and gas (or liquid) in the electric field. It is the process in which the surface arc extends to a certain stage and fails to break down. The discharge of insulating oil paper is the most common surface discharge phenomenon in gas. In actual use of power equipment, due to the uneven voltage distribution on the insulating oil paper, the surface flashover voltage is lower than the breakdown voltage when the insulating oil paper exists alone. The flashover voltage is also affected by factors such as the type of insulating oil paper, the electric field distribution and the surface state (such as dirt, moisture). Therefore, by studying the surface discharge of power equipment, corresponding measures (changing the electrode shape, increasing the electrode curvature radius, improving the capacitance distribution between electrodes, etc.) can be taken during the manufacture and installation of high-voltage power equipment to improve the electric field distribution in the insulation, so as to reduce the excessively high electric field strength in some areas of the equipment insulation structure, thereby extending the service life of the power equipment and ensuring the stable operation of the power equipment.

[0003] However, the existing method for studying creeping discharge is mainly based on the fact that when the partial discharge of the power equipment is greater than 300pC or 500pC under the condition of high voltage provided by the test voltage, the power equipment is regarded as a defective product. It is impossible to judge the creeping discharge stage of the insulation fault by the change of various characteristic parameters of the creeping discharge signal.

[0004] After searching, China Invention Patent Publication No. CN116882341B discloses a simulation method and system for electromagnetic signals of partial discharge along surface defects, which includes the following steps: constructing a fluid-chemical simulation model for surface discharge; using the fluid-chemical simulation model to simulate the microscopic process of partial discharge along surface defects, obtain the movement of charged particles during the surface discharge process, and calculate the surface discharge current value; constructing an electromagnetic signal simulation model based on the finite integral method; using the surface discharge current value as an excitation signal, and using the electromagnetic signal simulation model to simulate the electromagnetic signal generated by partial discharge along surface defects. This existing patent has the problem of being unable to determine the stage of surface discharge.

[0005] How to realize the judgment of surface discharge stage based on ultrasonic propagation has become a technical problem that needs to be solved. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a surface discharge stage judgment device and method based on ultrasonic propagation.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] According to one aspect of the present invention, a device for judging the stage of surface discharge based on ultrasonic propagation is provided, the device comprising:

[0009] High voltage generation module, used to simulate high voltage insulation transformer and provide high voltage conditions for creeping discharge caused by insulation failure;

[0010] The surface discharge module simulates the surface discharge phenomenon of insulation fault based on the high voltage condition output by the high voltage generation module, and generates various characteristic parameters of the insulation fault surface discharge electrical signal;

[0011] Oscilloscope, based on the surface discharge phenomenon of the surface discharge module, generates voltage data of each stage of insulation fault surface discharge;

[0012] The ultrasonic propagation detection module sets different sound propagation paths, obtains various characteristic parameter change signals of the acoustic signal caused by various characteristic parameter changes of the insulation fault surface discharge electrical signal from the surface discharge module in real time, and sends them to the characteristic parameter extraction module;

[0013] The characteristic parameter extraction module combines the influence of the sound propagation path on the sound signal, converts various characteristic parameter change signals into calculable data, extracts the characteristic data, and transmits them to the surface discharge stage judgment module;

[0014] The surface discharge stage judgment module combines the detection data obtained by the ultrasonic propagation detection module and the oscilloscope to judge the surface discharge stage of the insulation fault corresponding to the changes in various characteristic parameters of the acoustic signal caused by the changes in various characteristic parameters of the surface discharge electrical signal.

[0015] Preferably, the high voltage generating module comprises a DC power supply and a voltage regulator, the input end of the voltage regulator is connected to the DC power supply, and the output end is connected to the voltage dividing protection module;

[0016] The voltage regulator adjusts the input electric energy to output a voltage simulating the surface discharge caused by insulation failure of the electric power equipment.

[0017] Preferably, the creeping discharge module comprises insulating oil and an insulating oil quantity controller, and the insulating oil quantity controller is used to control the injection and discharge process of the insulating oil so that the oil quantity in the creeping discharge module meets the creeping discharge stage judgment condition;

[0018] The surface discharge module further comprises a needle plate electrode, which is used to simulate the phenomenon of insulation fault surface discharge and generate various characteristic parameters of insulation fault surface discharge electrical signals.

[0019] More preferably, the needle-plate electrode comprises an insulating paperboard, and a needle electrode and a plate electrode respectively connected to the insulating paperboard;

[0020] When the applied voltage reaches the set threshold, the electric field intensity near the needle electrode tip is much higher than the surrounding medium, the insulating paperboard will decompose, and then surface discharge will occur, and various characteristic parameter changes of the electrical signal will appear;

[0021] During the discharge process, the plate electrode acts as a counter electrode to collect the charged particles generated by the ionization of the needle electrode tip to maintain charge balance;

[0022] The plate electrode is connected to a voltage division protection module;

[0023] The surface discharge module includes a pressure controller for controlling the pressure in the surface discharge module. When the pressure is too high, an alarm is issued and a pressure relief valve is controlled to release the pressure so that the pressure meets the judgment condition of the surface discharge stage.

[0024] Preferably, the surface discharge stage judgment module uses the DBSCAN clustering analysis algorithm to perform cluster analysis on the surface discharge characteristic parameters of the entire process of surface discharge development, clusters the data into five categories, and then corresponds the clustering results to the surface discharge stages through the characteristics of different stages to obtain the judgment result of the surface discharge stage;

[0025] The characteristics of the different stages include the amplitude and frequency changes of the signals at different stages;

[0026] The surface discharge stage includes an initial stage, a development stage, a coexistence stage, a near-breakdown stage and a flashover stage.

[0027] Preferably, the device further comprises a voltage-dividing protection module connected to the high-voltage generating module, the oscilloscope and the creeping discharge module respectively, for ensuring that the creeping discharge loop current of the insulation fault is within the safe working range of each component;

[0028] The voltage-dividing protection module is used to eliminate the electromagnetic interference generated by the voltage regulator in the high-voltage generating module, so that the output of the high-voltage generating module meets the high-voltage condition of creeping discharge and is in a stable state.

[0029] More preferably, the voltage division protection module comprises a shunt, and a voltage divider and a coupler respectively connected to the shunt;

[0030] The shunt is used to ensure that the current of the surface discharge circuit of the insulation fault is within the safe working range of each component;

[0031] The voltage divider is connected to the coupler and the oscilloscope respectively, and is used to provide a continuous and stable voltage condition that satisfies the insulation fault surface discharge, and together with the oscilloscope, forms a loop to detect voltage data;

[0032] The other end of the coupler is connected to the creeping discharge module, and the coupler is used to maintain the stability of high-voltage signal transmission.

[0033] According to another aspect of the present invention, a method for determining the stage of surface discharge based on ultrasonic propagation is provided, the method comprising:

[0034] Step S1, treating the insulating paperboard according to the surface discharge condition requirements;

[0035] Step S2, cleaning the inside of the creeping discharge module with oil to make it meet the creeping discharge assessment conditions;

[0036] Step S3, selecting a needle-plate electrode that meets the surface discharge conditions, and installing it at a corresponding position of the surface discharge module;

[0037] Step S4, making the voltage condition output by the high voltage generating module meet the surface discharge voltage condition;

[0038] Step S5, the ultrasonic propagation detection module obtains in real time various characteristic parameter change signals of the acoustic signal caused by various characteristic parameter changes of the surface discharge electrical signal at each stage of the surface discharge of the insulation fault;

[0039] Step S6, the characteristic parameter extraction module receives various characteristic parameter change signals of the acoustic signal caused by various characteristic parameter changes of the electrical signal at each stage of the insulation fault surface discharge from the ultrasonic propagation detection module, converts them into calculable data, extracts characteristic parameters, and transmits them to the surface discharge stage judgment module;

[0040] Step S7, the surface discharge stage judgment module judges the surface discharge stage of the insulation fault corresponding to the changes in various characteristic parameters of the acoustic signal caused by the changes in the surface discharge electrical signal by combining the detection data obtained by the ultrasonic propagation detection module and the oscilloscope.

[0041] Preferably, the surface discharge stage includes an initial stage, a development stage, a coexistence stage, a near-breakdown stage and a flashover stage;

[0042] Each of the stages is specifically characterized by:

[0043] The discharge pulse amplitude in the initial stage is smaller than the first electric pulse amplitude threshold, and the frequency is lower than the first frequency threshold;

[0044] The discharge frequency in the development stage is higher than the set frequency threshold, the acoustic signal amplitude is higher than the first acoustic signal amplitude threshold, and the acoustic signal frequency band is greater than the set acoustic signal frequency band threshold;

[0045] In the coexistence stage, different types of pulse signals appear alternately, and the amplitude variation range of the acoustic signal is higher than the set acoustic signal amplitude variation threshold;

[0046] The acoustic signal amplitude near the breakdown stage is higher than the second acoustic signal amplitude threshold and tends to be stable, and a% of the spectrum energy is concentrated in the low frequency band below 50kHz;

[0047] The acoustic signal amplitude in the flashover stage is higher than the third acoustic signal amplitude threshold;

[0048] The third acoustic signal amplitude threshold is greater than the second acoustic signal amplitude threshold, and the second acoustic signal amplitude threshold is greater than the first acoustic signal amplitude threshold.

[0049] Preferably, the process of step S4 includes the following steps:

[0050] Step S41, using a step-by-step voltage-boosting method to measure the starting voltage of the surface discharge and the electrode breakdown voltage;

[0051] Step S42, according to the judgment condition of the creeping discharge degree, adjusting the voltage value of the high voltage generating module and the high voltage holding time, so that the output voltage condition meets the creeping discharge voltage condition.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] 1) The present invention simulates the surface discharge phenomenon of the insulation fault of the high-voltage insulation transformer and obtains the changes of various characteristic parameters of the surface discharge signal to judge the surface discharge stage of the insulation fault, which is helpful to monitor the local discharge signal in real time, so as to timely discover the early signs of insulation fault and realize early warning; by considering the propagation path of ultrasound, the surface discharge signal is feature extracted, and the characteristic parameters are selected and corrected in combination with the influence of the path on the sound propagation, so as to make a more accurate judgment on the surface discharge stage, thereby more accurately evaluating the severity and development trend of the insulation fault and providing a basis for maintenance decision-making.

[0054] 2) The present invention takes into account the influence of ultrasonic propagation in the ultrasonic detection and characteristic parameter extraction module, and utilizes ultrasonic propagation to eliminate the interference of some media on the propagation path of the surface discharge signal, thereby obtaining direct, accurate and reliable surface discharge data.

[0055] 3) The voltage-dividing protection device of the present invention eliminates the electromagnetic interference generated by the voltage regulator in the high-voltage generating device, ensures that the high-voltage condition output by the high-voltage generating device is in a stable state, and provides more accurate and reliable high-voltage data, making subsequent surface discharge data and stage judgment more accurate, thereby significantly improving the operating reliability and safety of the power equipment and reducing the risk of unexpected power outages. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 Schematic diagram of the structure of a device for judging the stage of surface discharge in an embodiment of the present invention;

[0057] Figure 2 This is a schematic diagram of the connection structure of the high voltage generation module and the voltage division protection module in an embodiment of the present invention;

[0058] Figure 3 This is a schematic structural diagram of the connection part of the surface discharge module in an embodiment of the present invention;

[0059] Figure 4 It is a schematic flow chart of the method for judging the surface discharge stage in the present invention;

[0060] In the attached drawings, 1. high voltage generation module; 2. voltage division protection module; 3. oscilloscope; 4. surface discharge module; 5. ultrasonic propagation detection module; 6. characteristic parameter extraction module; 7. surface discharge stage judgment module; 8. DC power supply; 9. voltage regulator; 10. shunt; 11. voltage divider; 12. coupler; 13 insulating oil; 14. insulating oil quantity controller; 15. needle plate electrode; 16. pressure controller; 17 needle electrode; 18. insulating paperboard; 19. plate electrode. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0062] Example 1

[0063] This embodiment relates to a surface discharge stage judgment device based on ultrasonic propagation, such as Figure 1 The device includes: a high voltage generating module 1, a voltage dividing protection module 2, an oscilloscope 3, a surface discharge module 4, an ultrasonic propagation detection module 5, a characteristic parameter extraction module 6, and a surface discharge stage judgment module 7.

[0064] The high voltage generation module 1 is connected to the voltage division protection module 2 to provide high voltage conditions for creeping discharge when insulation fault occurs;

[0065] like Figure 2 The high-voltage generating module 1 includes a DC power supply 8 and a voltage regulator 9; wherein the DC power supply 8 is connected to the input end of the voltage regulator 9, the DC power supply 8 inputs electric energy through the input end of the voltage regulator 9, and the voltage regulator 9 uses the voltage regulation principle to output a voltage that meets the surface discharge of insulation fault at the output end to meet the voltage requirement of the present invention.

[0066] In this embodiment, the DC power supply 8 is preferably a digitally controlled DC power supply, which provides precise voltage and current regulation, as well as digital display and control, and is suitable for applications that require precise control of power supply conditions.

[0067] The input end of the voltage regulator 9 is connected to the DC power supply 8, and the output end is connected to the voltage divider protection module 2. When performing the surface discharge of the insulation fault of the present invention, the voltage regulator 9 is used to provide the necessary high voltage to simulate the voltage state of the power equipment under actual operating conditions, and to judge the surface discharge stage of the insulation fault by the changes in various characteristic parameters of the acoustic signal caused by the changes in various characteristic parameters of the surface discharge electrical signal.

[0068] In this embodiment, the voltage regulator 9 is preferably a DC regulated power supply voltage regulator, which allows the user to adjust the output voltage as needed, has the advantages of high flexibility and strong adaptability, and can meet the testing and operation requirements of different devices.

[0069] like Figure 2 The voltage-dividing protection module 2 is connected to the high-voltage generating module 1, the oscilloscope 3 and the surface discharge module 4. The voltage-dividing protection module 2 is used to eliminate the electromagnetic interference generated by the voltage regulator 9 in the high-voltage generating module 1, ensure that the high-voltage condition output by the high-voltage generating module 1 that meets the surface discharge is in a stable state, protect the normal operation of each component of the high-voltage generating module 1, extend the service life of the test device, and obtain more accurate and reliable high-voltage data.

[0070] like Figure 2 The voltage divider protection module 2 includes a shunt 10, a voltage divider 11 and a coupler 12; the shunt 10 connects the voltage regulator 9 and the voltage divider 11 to ensure that the current of the surface discharge circuit of the insulation fault is within the range in which each component can work safely.

[0071] In this embodiment, the shunt 10 preferably uses a solid metal nickel-chromium alloy resistor layer, and the joint uses a calibration slot and a "boost" design to improve the temperature coefficient (TCR) performance and improve the accuracy within the operating temperature range.

[0072] The voltage divider 11 is connected to the shunt 10, the coupler 12 and the oscilloscope 3 respectively. In the present embodiment, the voltage divider 11 enables the device to provide a continuous and stable voltage condition that satisfies the creeping discharge of the insulation fault, and at the same time forms a loop with the oscilloscope 3 to detect the current voltage data.

[0073] In this embodiment, the voltage divider 11 is preferably a high voltage divider with very high input impedance and precise voltage division ratio.

[0074] The coupler 12 is respectively connected to the voltage divider 11 and the creeping discharge module 4. In this embodiment, the coupler 12 maintains the stability of the transmission of the high voltage signal, ensuring that the high voltage signal displayed by the oscilloscope 3 is the high voltage signal actually transmitted to the creeping discharge module 4, making the detection result of the present invention more reliable.

[0075] In this embodiment, the coupler 12 is preferably a transformer coupler, which is a device that realizes signal coupling through the principle of magnetic coupling. It is composed of at least two windings (generally an input winding and an output winding). Through the interaction of magnetic fields between the windings, the signal is transmitted from the input winding to the output winding by electromagnetic induction.

[0076] The oscilloscope 3 is respectively connected to the voltage division protection module 2, the surface discharge module 4 and the surface discharge stage judgment module 7 to obtain the surface discharge phenomenon of the insulation fault and generate voltage data of each stage of the surface discharge of the insulation fault;

[0077] In this embodiment, the oscilloscope 3 is preferably a Micsig DP series high-voltage differential probe, whose bandwidth ranges from 100MHz to 500MHz and can withstand differential voltage tests up to 7000Vpk. They are based on optical isolation probe technology, have ultra-low noise floor and excellent amplitude-frequency characteristics, and industry-leading common mode rejection ratio.

[0078] The surface discharge module 4 is connected to the voltage divider protection module 2 and the oscilloscope 3 respectively, and simulates the surface discharge phenomenon of the insulation fault for the detection result, generates various characteristic parameters of the electrical signal of the surface discharge of the insulation fault, and determines the surface discharge stage of the insulation fault by the change of the parameters.

[0079] like Figure 3 The creeping discharge module 4 includes insulating oil 13 , an insulating oil quantity controller 14 , a needle plate electrode 15 and a pressure controller 16 .

[0080] The insulating oil quantity controller 14 is installed on the surface discharge module 4 to complete the injection and discharge process of the insulating oil 13 in the surface discharge module, so that the oil quantity in the surface discharge module 4 meets the surface discharge stage judgment condition, thereby ensuring the reliability of the judgment result;

[0081] The needle plate electrode 15 is connected to the voltage dividing protection module 2. In the embodiment, the needle plate electrode 15 is used to simulate the phenomenon of creeping discharge of insulation fault, generate various characteristic parameters of the electrical signal of creeping discharge of insulation fault, and judge the creeping discharge stage of insulation fault by the change of the parameters;

[0082] The needle plate electrode 15 includes a needle electrode 17, an insulating paperboard 18 and an electrode 19. The needle electrode 17 is connected to the voltage division protection module 2. When the external voltage reaches a certain value, the electric field strength near the needle tip is sufficient to ionize the insulating paperboard, generate surface discharge, and cause various characteristic parameter changes of the electrical signal.

[0083] In this embodiment, the needle electrode 17 is preferably a needle electrode with a top end of φ1 mm×40 mm, a curvature diameter of the top end of 1 mm, and a length of 40 mm.

[0084] like Figure 3 The two ends of the insulating paperboard 18 are connected to the needle electrode 17 and the plate electrode 19 respectively. When the external voltage reaches a certain value, the electric field strength near the needle tip is much higher than the surrounding medium. The insulating paperboard 18 will inevitably decompose, and then surface discharge will occur, and various characteristic parameter changes of the electrical signal will occur.

[0085] In this embodiment, the insulating paperboard 18 is preferably: an insulating paperboard that is vacuum-oiled at 85° C. for 24 hours and then dried at 120° C. for 24 hours.

[0086] The plate electrode 19 is connected to the voltage-dividing protection module 2 . During the discharge process, the plate electrode 19 serves as a counter electrode for collecting charges, and can collect charged particles generated by ionization of the needle electrode 17 to maintain charge balance.

[0087] In this embodiment, the plate electrode 19 is preferably a plate electrode of φ30 mm×24 mm, that is, a diameter of 30 mm and a thickness of 24 mm.

[0088] The pressure controller 16 is installed on the surface discharge module 4 to control the current pressure in the surface discharge module 4. When the pressure is too high, an alarm is issued and the pressure relief valve is controlled to release the pressure, so that the pressure in the surface discharge module 4 meets the judgment conditions of the surface discharge stage, thereby reducing the error of the judgment result.

[0089] The ultrasonic propagation detection module 5 is placed in the detection area of ​​the surface discharge module 4, and different ultrasonic propagation paths are set. When the ultrasonic propagation passes through the oil-paper insulation, various characteristic parameter change signals of the acoustic signal caused by various characteristic parameter changes of the surface discharge electrical signal at each stage of the surface discharge of the insulation fault are obtained in real time. Since there may be insulating oil paper, windings and other media in the transformer oil that affect the propagation path of the surface discharge signal, the interference of these media on the propagation path of the surface discharge signal is eliminated by ultrasonic propagation, thereby obtaining direct, accurate and reliable surface discharge data.

[0090] The characteristic parameter extraction module 6 is connected to the ultrasonic propagation detection module 5, receives the various characteristic parameter changes of the acoustic signal caused by the various characteristic parameter changes of the electrical signal of the creeping discharge at each stage of the creeping discharge of the insulation fault from the ultrasonic propagation detection module 6, converts it into calculable data for extraction, and transmits it to the creeping discharge stage judgment module 7. In the process of extracting parameters, the sound waves of different propagation paths are considered, and then the characteristic parameters are selected.

[0091] The surface discharge stage judgment module 7 is connected to the ultrasonic propagation detection module 6 and the oscilloscope 3 respectively, and judges the surface discharge stage of the insulation fault corresponding to the changes in various characteristic parameters of the acoustic signal caused by the changes in various characteristic parameters of the surface discharge electrical signal by combining the detection data obtained by the ultrasonic propagation detection module 6 and the oscilloscope 3.

[0092] Example 2

[0093] This embodiment also relates to a method for determining the stage of surface discharge based on ultrasonic propagation, such as Figure 4 , the method comprising:

[0094] Step S1, treating the insulating paperboard according to the surface discharge condition requirements;

[0095] Step S2, cleaning the inside of the creeping discharge module with oil to make it meet the creeping discharge assessment conditions;

[0096] Step S3, selecting a needle-plate electrode that meets the surface discharge conditions and installing it at the correct position of the surface discharge module;

[0097] Step S4, making the voltage condition of the high voltage generating module meet the surface discharge voltage condition;

[0098] Step S5, the ultrasonic propagation detection module obtains in real time various characteristic parameter change signals of the acoustic signal caused by various characteristic parameter changes of the surface discharge electrical signal at each stage of the surface discharge of the insulation fault;

[0099] Step S6, the characteristic parameter extraction module receives various characteristic parameter change signals of the acoustic signal caused by various characteristic parameter changes of the electrical signal at each stage of the insulation fault surface discharge from the ultrasonic propagation detection module, converts them into calculable data, extracts characteristic parameters, and transmits them to the surface discharge stage judgment module;

[0100] Step S7, the surface discharge stage judgment module judges the surface discharge stage of the insulation fault corresponding to the changes in various characteristic parameters of the acoustic signal caused by the changes in the surface discharge electrical signal by combining the detection data obtained by the ultrasonic propagation detection module and the oscilloscope.

[0101] The process of step S1 includes the following steps:

[0102] Step S11, manufacturing three sheets of insulating paper according to the surface discharge condition requirements, and treating the surfaces thereof;

[0103] Step S12, placing the two pieces of insulating paperboard processed in step S11 in vacuum oil-immersion at 85° C. for 24 hours, and then drying them at 120° C. for 24 hours;

[0104] Step S13, sandwiching a layer of insulating cardboard processed in step S11 between the two pieces of insulating cardboard processed in step S12, and bonding them together with epoxy resin insulating adhesive.

[0105] The process of step S4 includes the following steps:

[0106] Step S41, using a step-by-step voltage method to measure the starting voltage of the surface discharge (the voltage obtained when the pulse appears for the first time) and the electrode breakdown voltage;

[0107] Step S42, adjusting the voltage value of the high voltage generating module and the high voltage holding time etc. according to the judgment condition of the creeping discharge degree.

[0108] In step S5, detection data of surface discharge is obtained from the ultrasonic propagation detection module and the oscilloscope. The collected characteristic parameters may include signal amplitude, frequency, duration, rise time and peak factor.

[0109] In step S6, the characteristic parameter extraction module analyzes each characteristic parameter collected to determine whether they show signs of creeping discharge. For example, creeping discharge may cause an increase in signal amplitude, a change in frequency, an increase in duration, a shortening of rise time, or an increase in peak factor.

[0110] In step S7, an evaluation algorithm for the entire process of surface discharge development based on DBSCAN cluster analysis is proposed. By clustering the characteristic parameters of surface discharge from the initial discharge to the breakdown stage, the recognition and judgment of each stage of surface discharge are realized, including:

[0111] Step S71, normalizing the surface discharge characteristic data to make the dimension of each surface characteristic parameter consistent;

[0112]

[0113] in,

[0114] y i represents the normalized characteristic parameters of surface discharge;

[0115] x i Indicates the characteristic parameters of surface discharge;

[0116] x min Indicates the minimum value of the statistical surface characteristic parameter;

[0117] x max Indicates the maximum value of the statistical surface characteristic parameters;

[0118] Step S72, define the classification k of each stage of surface discharge. The surface discharge stage can be divided into five stages, namely, the initial stage, the development stage, the coexistence stage, the near breakdown stage, and the flashover stage. Therefore, the number of "class centers" k=5 can be directly determined, that is, the number of "class centers" in each stage is 1.

[0119] Step S73, determine the neighborhood sample set, randomly select one sample data from each of the five positions of the initial stage, the development stage, the coexistence stage, the near breakdown stage, and the flashover stage, and calculate the sub-sample set that does not exceed the threshold according to the following formula;

[0120] Nε(y j )={y i ∈D|diatance(y i ,y j )≤ε}

[0121] Where D represents the normalized surface discharge characteristic parameter sample set, D∈{y 1 ,y 2 ,…,y m}, ε represents the neighborhood distance threshold in the sample set D; m represents the number of subsample sets, Nε(y j ) is the set of subsamples that do not exceed the threshold.

[0122] Step S74, determine the “class center”, for the surface discharge characteristic data sample set D of the entire surface discharge process, if its ε neighborhood corresponds to Nε(y j ) contains at least MinPts samples, that is, if m ≥ MinPts, then y j It is a "class center".

[0123] Among them, MinPts represents the threshold of the number of samples in the neighborhood with a distance of ε in sample D.

[0124] Step S75, update the “class center” according to the density reachability relationship:

[0125] For y i and j , if there exists a sample sequence p 1 ,p 2 ,...,p T , satisfying p 1 =x i ,p T =x j , and p t +1 by p t The density is directly proportional to x j By x i The density is reachable. That is, the density is reachable to satisfy the transitivity. At this time, the transitive sample p in the sequence 1 ,p 2 ,...,p T-1 They are all core objects, because only core objects can make other sample densities directly accessible.

[0126] Step S76: The sample set connected by the maximum density derived from the density reachable relationship is a category or a cluster for our final clustering.

[0127] For x i and x j , if there is a core object sample x k , so that x i and x j All by x k The density can reach, then x i and x j Density connected.

[0128] Step S77, continuously loop the process of steps S73 to S76 until the change of the "class center" is less than the threshold, that is, all "class centers" have categories, then clustering stops, and the "class center" and clustering results are output, which is the judgment result of the surface discharge stage. After clustering the data into five categories, the clustering results are matched with the five stages through the characteristics of different stages. Finally, a stage is judged, that is, the partial discharge is divided into one stage according to the signal data. There may be overlaps between these stages. For example, when two stages that are close in time transition, the data of these two stages may exist at the same time.

[0129] The characteristics of the five stages are as follows:

[0130] In the initial stage, the discharge pulse amplitude is small and the frequency is low;

[0131] In the development stage, the discharge frequency and the amplitude of the acoustic signal increase, and the frequency band of the acoustic signal gradually widens;

[0132] In the coexistence stage, different types of pulse signals appear alternately, the amplitude variation range of the acoustic signal increases, and fluctuation occurs;

[0133] Near the breakdown stage, the acoustic signal amplitude reaches a peak value and tends to be stable, and the spectrum energy is highly concentrated, that is, 90% of the spectrum energy is concentrated in the low frequency band below 50kHz;

[0134] The sound intensity reaches its peak in the flashover stage and far exceeds that in other stages.

[0135] The clustering results can be associated with the discharge stage from the changes in the amplitude and frequency of the local discharge acoustic and electrical signals.

[0136] Step S78: Verify the judgment result of the algorithm, possibly through laboratory testing or field testing. Adjust the threshold and algorithm logic according to the verification result to improve the accuracy of the judgment.

[0137] Example 3

[0138] This embodiment also relates to an application of surface discharge stage judgment based on ultrasonic propagation.

[0139] The three sheets of insulating cardboard were polished clean without sharp corners or burrs. The two sheets of insulating cardboard treated in step S11 of embodiment 2 were vacuum immersed in oil at 85°C for 24 hours, and then dried at 120°C for 24 hours. The inside of the surface discharge module was cleaned with oil to meet the surface discharge evaluation conditions. The needle plate electrode that meets the surface discharge conditions was selected and installed in the correct position of the surface discharge module. The step-up method was adopted to increase the voltage by 0.5kV every 10s to measure the starting voltage of the surface discharge (the voltage obtained when the pulse first appears) and the electrode breakdown voltage. According to the judgment conditions of the surface discharge degree, the voltage value of the high-voltage generation module and the high-voltage holding time were adjusted. The ultrasonic propagation detection module obtains various characteristic parameter change signals of the acoustic signal caused by various characteristic parameter changes of the surface discharge electrical signal at each stage of the insulation fault in real time; the collected characteristic parameters may include the amplitude, frequency, duration, rise time and peak factor of the signal. The characteristic parameter extraction module receives various characteristic parameter change signals of the acoustic signal caused by various characteristic parameter changes of the surface discharge electrical signal at each stage of the insulation fault surface discharge from the ultrasonic propagation detection module, converts it into calculable data for extraction, and transmits it to the surface discharge stage judgment module; the surface discharge stage judgment module judges the surface discharge stage of the insulation fault corresponding to the various characteristic parameter changes of the surface discharge electrical signal by combining the detection data obtained by the ultrasonic propagation detection module and the oscilloscope.

[0140] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0141] In the several embodiments provided in the present application, it should be understood that the disclosed devices and systems can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0142] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0143] Example 4

[0144] The electronic device of the present invention includes a central processing unit (CPU), which can perform various appropriate actions and processes according to computer program instructions stored in a read-only memory (ROM) or loaded from a storage unit into a random access memory (RAM). In the RAM, various programs and data required for device operation can also be stored. The CPU, ROM and RAM are connected to each other via a bus. An input / output (I / O) interface is also connected to the bus.

[0145] Multiple components in the device are connected to the I / O interface, including: input units, such as keyboards, mice, etc.; output units, such as various types of displays, speakers, etc.; storage units, such as disks, optical disks, etc.; and communication units, such as network cards, modems, wireless communication transceivers, etc. The communication unit allows the device to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunication networks.

[0146] The processing unit performs the various methods and processes described above, such as methods S1 to S7. For example, in some embodiments, methods S1 to S7 may be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program may be loaded and / or installed on the device via a ROM and / or a communication unit. When the computer program is loaded into the RAM and executed by the CPU, one or more steps of methods S1 to S7 described above may be performed. Alternatively, in other embodiments, the CPU may be configured to execute methods S1 to S7 in any other appropriate manner (e.g., by means of firmware).

[0147] The functions described above herein may be performed at least in part by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that may be used include: field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), complex programmable logic devices (CPLDs), and the like.

[0148] The program code for implementing the method of the present invention can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer or other programmable data processing device, so that the program code, when executed by the processor or controller, enables the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code can be executed entirely on the machine, partially on the machine, partially on the machine as a stand-alone software package and partially on a remote machine, or entirely on a remote machine or server.

[0149] In the context of the present invention, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0150] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A surface discharge stage judgment device based on ultrasonic propagation, characterized in that: The device includes: A high voltage generating module (1) is used to simulate a high voltage insulation transformer and provide a high voltage condition for creeping discharge when insulation failure occurs; A surface discharge module (4) simulates the surface discharge phenomenon of insulation fault based on the high voltage condition output by the high voltage generation module (1) and generates various characteristic parameter changes of insulation fault surface discharge electrical signals; An oscilloscope (3) generates voltage data of each stage of insulation fault creeping discharge based on the creeping discharge phenomenon of the creeping discharge module (4); The ultrasonic propagation detection module (5) sets different acoustic propagation paths, obtains various characteristic parameter change signals of the acoustic signal caused by various characteristic parameter changes of the insulation fault surface discharge electrical signal from the surface discharge module (4) in real time, and sends them to the characteristic parameter extraction module (6); The characteristic parameter extraction module (6) combines the influence of the sound propagation path on the sound signal, converts various characteristic parameter change signals into calculable data, extracts the characteristic data, and transmits them to the surface discharge stage judgment module (7); The surface discharge stage judgment module (7) combines the detection data obtained by the ultrasonic propagation detection module (6) and the oscilloscope (3) to judge the surface discharge stage of the insulation fault corresponding to the changes in various characteristic parameters of the acoustic signal caused by the changes in various characteristic parameters of the surface discharge electrical signal.

2. The device for judging the stage of surface discharge based on ultrasonic propagation according to claim 1, characterized in that: The high voltage generating module (1) comprises a DC power supply (8) and a voltage regulator (9), wherein the input end of the voltage regulator (9) is connected to the DC power supply (8), and the output end is connected to the voltage dividing protection module (2); The voltage regulator (9) adjusts the input electric energy to output a voltage simulating a creeping discharge caused by an insulation failure in the electric power equipment.

3. The device for judging the stage of surface discharge based on ultrasonic propagation according to claim 1, characterized in that: The creeping discharge module (4) comprises insulating oil (13) and an insulating oil quantity controller (14), wherein the insulating oil quantity controller (14) is used to control the injection and discharge process of the insulating oil (13) so that the oil quantity in the creeping discharge module (4) meets the creeping discharge stage judgment condition; The surface discharge module (4) further comprises a needle plate electrode (15), wherein the needle plate electrode (15) is used to simulate the phenomenon of insulation fault surface discharge and generate various characteristic parameter changes of insulation fault surface discharge electrical signals.

4. The device for judging the stage of surface discharge based on ultrasonic propagation according to claim 3, characterized in that: The needle-plate electrode (15) comprises an insulating paperboard (18), and a needle electrode (17) and a plate electrode (19) respectively connected to the insulating paperboard (18); When the applied voltage reaches a set threshold, the electric field intensity near the needle tip of the needle electrode (17) is much higher than that of the surrounding medium, and the insulating paperboard (18) will decompose, thereby generating surface discharge, and causing changes in various characteristic parameters of the electrical signal; During the discharge process, the plate electrode (19) acts as a counter electrode for collecting charges, collecting charged particles generated by ionization at the tip of the needle electrode (17) to maintain charge balance; The plate electrode (19) is connected to the voltage division protection module (2); The creeping discharge module (4) comprises a pressure controller (16) for controlling the pressure in the creeping discharge module (4). When the pressure is too high, an alarm is given and a pressure relief valve is controlled to release the pressure so that the pressure meets the judgment condition of the creeping discharge stage.

5. The device for judging the stage of surface discharge based on ultrasonic propagation according to claim 1, characterized in that: The surface discharge stage judgment module (7) uses the DBSCAN cluster analysis algorithm to perform cluster analysis on the surface discharge characteristic parameters of the entire process of surface discharge development, clusters the data into five categories, and then matches the clustering results with the surface discharge stages through the characteristics of different stages to obtain the judgment result of the surface discharge stage; The characteristics of the different stages include the amplitude and frequency changes of the signals at different stages; The surface discharge stage includes an initial stage, a development stage, a coexistence stage, a near-breakdown stage and a flashover stage.

6. The device for judging the stage of surface discharge based on ultrasonic propagation according to claim 1, characterized in that: The device also includes a voltage-dividing protection module (2) connected to the high-voltage generation module (1), the oscilloscope (3) and the creeping discharge module (4) respectively, and used to ensure that the creeping discharge loop current of the insulation fault is within the safe working range of each component; The voltage division protection module (2) is used to eliminate the electromagnetic interference generated by the voltage regulator (9) in the high-voltage generation module (1), so that the output of the high-voltage generation module (1) satisfies the high-voltage condition of creeping discharge and is in a stable state.

7. The device for judging the stage of surface discharge based on ultrasonic propagation according to claim 6, characterized in that: The voltage division protection module (2) comprises a current divider (10), and a voltage divider (11) and a coupler (12) respectively connected to the current divider (10); The shunt (10) is used to ensure that the current of the surface discharge circuit due to insulation failure is within the safe working range of each component; The voltage divider (11) is connected to the coupler (12) and the oscilloscope (3) respectively, and is used to provide a continuous and stable voltage condition that satisfies the insulation fault surface discharge, and together with the oscilloscope (3) forms a loop to detect voltage data; The other end of the coupler (12) is connected to the creeping discharge module (4), and the coupler (12) is used to maintain the stability of high-voltage signal transmission.

8. A method for using the surface discharge stage judgment device based on ultrasonic propagation according to any one of claims 1 to 7, characterized in that: The method includes: Step S1, treating the insulating paperboard according to the surface discharge condition requirements; Step S2, cleaning the inside of the creeping discharge module with oil to make it meet the creeping discharge assessment conditions; Step S3, selecting a needle-plate electrode that meets the surface discharge conditions, and installing it at a corresponding position of the surface discharge module; Step S4, making the voltage condition output by the high voltage generating module meet the surface discharge voltage condition; Step S5, the ultrasonic propagation detection module obtains in real time various characteristic parameter change signals of the acoustic signal caused by various characteristic parameter changes of the surface discharge electrical signal at each stage of the surface discharge of the insulation fault; Step S6, the characteristic parameter extraction module receives various characteristic parameter change signals of the acoustic signal caused by various characteristic parameter changes of the electrical signal at each stage of the insulation fault surface discharge from the ultrasonic propagation detection module, converts them into calculable data, extracts characteristic parameters, and transmits them to the surface discharge stage judgment module; Step S7, the surface discharge stage judgment module judges the surface discharge stage of the insulation fault corresponding to the changes in various characteristic parameters of the acoustic signal caused by the changes in the surface discharge electrical signal by combining the detection data obtained by the ultrasonic propagation detection module and the oscilloscope.

9. The method according to claim 8, characterized in that The surface discharge stage includes the initial stage, the development stage, the coexistence stage, the near breakdown stage and the flashover stage; Each of the stages is specifically characterized by: The discharge pulse amplitude in the initial stage is smaller than the first electric pulse amplitude threshold, and the frequency is lower than the first frequency threshold; The discharge frequency in the development stage is higher than the set frequency threshold, the acoustic signal amplitude is higher than the first acoustic signal amplitude threshold, and the acoustic signal frequency band is greater than the set acoustic signal frequency band threshold; In the coexistence stage, different types of pulse signals appear alternately, and the amplitude variation range of the acoustic signal is higher than the set acoustic signal amplitude variation threshold; The acoustic signal amplitude near the breakdown stage is higher than the second acoustic signal amplitude threshold and tends to be stable, and a% of the spectrum energy is concentrated in the low frequency band below 50kHz; The acoustic signal amplitude in the flashover stage is higher than the third acoustic signal amplitude threshold; The third acoustic signal amplitude threshold is greater than the second acoustic signal amplitude threshold, and the second acoustic signal amplitude threshold is greater than the first acoustic signal amplitude threshold.

10. The method according to claim 8, characterized in that The process of step S4 includes the following steps: Step S41, using a step-by-step voltage-boosting method to measure the starting voltage of the surface discharge and the electrode breakdown voltage; Step S42, according to the judgment condition of the creeping discharge degree, adjusting the voltage value of the high voltage generating module and the high voltage holding time, so that the output voltage condition meets the creeping discharge voltage condition.

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