CN102721904B - Device for detecting external insulation of transmission lines and control method thereof - Google Patents
Device for detecting external insulation of transmission lines and control method thereof Download PDFInfo
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Abstract
The invention relates to a device for detecting external insulation of transmission lines and a control method thereof. The device comprises an inclined insulated support frame which supports a sample. Upper part and lower part of the sample are equipped with a high-voltage end electrode and a ground electrode respectively, wherein the high-voltage end electrode is connected with one output end of a transformer through a resistor R. A primary coil of the transformer is connected with ac power supply through a voltage regulator. A water-dripping device is arranged above the sample and an antenna is arranged in front of a sample surface, wherein the antenna is connected with a filter amplifier circuit. The filter amplifier circuit is connected to a computer through a data acquisition card. The method comprises: putting the sample on the insulated support frame and connecting the sample to the high-voltage end electrode and the ground electrode, electrifying the sample, dripping water upon the sample surface, receiving electromagnetic wave signals, drawing a three-dimension spectrum of the electromagnetic wave signals, calculating a vacancy rate lambda with a formula lambda=(E(m<2>)-[E(m)]<2>)/[E(m)]<2>, drawing a two-dimension spectrum, drawing a discharging recurrence plot and calculating a recurrence rate, and determining a hydrophobicity level of the sample. The device and the method can decrease external interference and provide high accuracy, and can visually, clearly and accurately reflect changing conditions of hydrophobicity of the insulator surface.
Description
Technical field
The present invention relates to a kind of device detecting transmission line of electricity external insulation.Particularly relate to a kind of electromagnetic wave signal utilizing the dynamically method of dripping to obtain the electric discharge corresponding to different hydrophobic nature to launch, and the control method of device by the detection transmission line of electricity external insulation of analytic signal character recognition insulator hydrophobicity power.
Background technology
Composite insulator uses the history having had nearly 40 years as external insulation, all use composite insulator, and the quantity of its hanging net operation is still progressively increasing in the electrical network of a lot of countries and regions.Composite insulator owing to having pollution flashover, the advantage such as wet lightning pressure is high, lightweight, be widely used in China's electrical network.Along with the progressively raising of China's line voltage grade, also more and more higher to the requirement of transmission line of electricity external insulation, the effect of composite insulator in electrical network also seems more and more important.
At present, in composite high voltage insulator Application comparison widely umbrella sheath material be high-temperature silicon disulfide rubber, there is the advantages such as electric insulating quality, weatherability, high-low temperature resistant characteristic, physiological inertia, low surface tension and low-surface-energy.There is a large amount of uncrosslinked low-molecular-weight siloxane segment in various degree in silicon rubber, the migration of these low-molecular-weight siloxane segments is main causes that silastic material has hydrophobic nature migrate attribute, is also the main cause of its hydrophobicity recovery.
Silastic material is organic material, different with the inorganic material such as glass insulator from pottery, in organic material molecule, element is by being covalently bonded on together, key between element and force rate lower, thus the large molecule of organic material easily ruptures, especially, under the effect of the environment such as ultraviolet radiation, corona discharge, humidity, temperature variation and chemical factor, molecular link easily ruptures, and causes organic material aging.When composite insulator umbrella skirt occurs aging, its surface hydrophobicity declines, and electric property and mechanical property all can decline thereupon, and after declining, this performance is expendable.If the decline of certain performance of material is recoverable, we are referred to as fatigue; If the decline of certain performance of material is expendable, be then called aging.Major part material (especially organic material) ubiquity problem of aging, but its aging speed because of the different difference of material very large.Being not only organic material, equally also there is problem of aging in inorganic material, as the porcelain insulator in transmission line of electricity and glass insulator also can occur aging, but due to its aging speed very slow, can be not considered in operational process.As the composite insulator be made up of a kind of organic material, because its surface is easily by the impact of the factors such as insulator surface shelf depreciation, UV radiation, corona discharge, acid rain, ubiquity catabiosis in hanging net operation process, in UHV transmission line, the impact of corona discharge is particularly outstanding.The aging forfeiture gradually just meaning hydrophobic nature of composite insulator, and then affect the stability of circuit, therefore should give enough attention to the problem of aging of composite insulator in transmission line of electricity.
Composite insulator is due to the impact of the factors such as filth, humidity, electric discharge, and its hydrophobic nature can decline gradually and even lose.The degradation of hydrophobic nature will cause the remarkable decline of composite insulator pollution flashover voltage, thus threaten the safe and stable operation of electric system.Find by carrying out detection to the insulator that flashover occurs, its hydrophobic nature state changes.Therefore very important meaning is had to the detection of surface hydrophobicity of composite insulator.
In the relevant criterion of IEC, hydrophobic nature is measured and is measured also referred to as wettability.IEC/TS 62073-2003 recommendation 3 kinds of hydrophobic nature method of testings, i.e. contact angle method, surface tension method and water spray stage method.After this, along with the application & development of leakage current method on online insulator surface monitoring running state, be also applied to the detection of surface hydrophobic sexual state successively.Therefore the hydrophobic nature criterion of silicon rubber insulator is divided into: 1, Static Contact horn cupping (CA method); 2, surface tension method; 3, water spray stage method (HC method); 4, leakage current measurement method; 5, dynamic water droplet method (DDT method).Wherein,
1. Static Contact horn cupping
Static Contact horn cupping refers to that water droplet volume being about about 4ul ~ 7ul by micro-syringe drops in material surface, and the size then measuring the contact angle of the material surface globule reflects the method for material hydrophobic nature state.The main process of the method is: high-speed camera shooting water droplet, in the state of material surface, then applies the contact angle of corresponding software measurement water droplet and material surface.This method is measured simple, convenient, is thus widely used in the assessment of surface hydrophobicity of composite insulator.But when surface of composite insulator has contamination, contact angle has obvious hysteresis phenomenon, at this moment generally first allow water droplet at static about the 20s of material surface, then measure it.
2. surface tension method
Surface tension method is a kind of method using one group of liquid assessment Hydrophobicity of Composite Insulator with different surfaces tension force.The process employs the liquid mixture in low scope, medium range, high scope 3 tension ranges.Spiece is sprayed at specimen surface gently, and record successive layers is split into time required for little water droplet, and successive layers is defined as the surface tension of product to be tested in the specimen surface retention time closest to the surface tension that the potpourri of 2s has.
3. to spray water stage method
Water spray stage method, i.e. HC method (Hydrophobicity Classification Guide) are the methods of the sign Hydrophobicity of Composite Insulator state proposed by power transmission and distribution research institute of Sweden.Hydrophobic nature is divided into 7 grades: HC1-HC3 level to be hydrophobic nature state by the method, and HC4 level is intermediate state, and HC5-HC7 level is hydrophilic state.The Main Basis divided between at different levels be measured surface gather state, and have the classification figure reference of standard.HC method can conveniently for the site assessment of the sub-hydrophobic nature of actual insulation, and shortcoming is large by subjective impact.
4. leakage current method
The leakage current of surface of composite insulator refers to the electric current flowing through surface of composite insulator before pollution flashover occurs, its concentrated expression key elements such as voltage, weather and filth.In the last few years, some scholars find that the evolution relation of the leakage current of insulator surface and pollution flashover electric discharge is very close in the research of Mechanism of Contamination Flashover, contain bulk information in the leakage current that surface of composite insulator produces, it can be used for the damp degree of concentrated expression composite insulator, pollution level, insulator and bear the factor such as voltage and insulator shape.The change procedure of insulator surface leakage current also reflects the cumulative change process of composite insulator filth simultaneously, so the monitoring of Insulators surface filth layer leakage current is for judging that the running status of transmission line of electricity external insulation has very important significance.Therefore, generally adopt the method for monitoring insulator surface leakage current to assess the filthy state of insulation, the more important thing is that leakage current can realize continuous on-line monitoring.
5. dynamic water droplet method (DDT method)
In the last few years, dynamic water droplet method (Dynamic Drop Test, DDT) gradually accept by some scholars, and be used for studying change and the Correlative Influence Factors of insulator surface hydrophobic nature.The people such as Otsubo adopt dynamic water droplet method to have studied the dynamic perfromance of drop in surface of composite insulator of different gradation for surface pollution and the impact on insulator hydrophobicity thereof, have studied insulator surface roughness and ATH content to the impact of its hydrophobic nature simultaneously.The people such as Kurimoto rely on dynamic water droplet method establish insulator surface partial discharge pulse number and hydrophobic nature change between corresponding relation, promoted the application of dynamic water droplet method in the assessment of insulator surface hydrophobic nature.The people such as Tokoro have studied the factors such as temperature, material surface roughness and ATH content to the impact of silastic material surface hydrophobicity by measuring drop in dynamic water droplet method in some morphological parameters on silastic material surface, and establish silastic material degree of aging appraisal procedure.Dynamic water droplet method is a kind of Hydrophobicity of Composite Insulator appraisal procedure just proposed in recent years, therefore according to the method come qualitative assessment insulator surface hydrophobic nature state need further study.
There is shortcomings in existing surface hydrophobicity of composite insulator appraisal procedure: although 1. Static Contact horn cupping has very high measuring accuracy, but need strict test environment, insulator hydrophobicity assessment under being mainly used in laboratory condition and under off-line state, the surface hydrophobicity not being suitable for online insulator detects.2. some liquid used in surface tension method has certain harmfulness to human body, and therefore the method is not also used widely at present.Although stage method of 3. spraying water operation fast, simply, the method mainly relies on artificial contrast and classification, and the subjective factor by people affects greatly, and can not qualitative assessment insulator surface hydrophobic nature.4. the current research to leakage current mostly rests on theory stage, and major part is conceived to condition monitoring, so not yet there are the effective ways of the qualitative assessment Hydrophobicity of Composite Insulator based on leakage current up to now.5. dynamically water droplet method is a kind of Hydrophobicity of Composite Insulator appraisal procedure just proposed in recent years, and therefore carrying out qualitative assessment insulator surface hydrophobic nature according to the method needs further theoretical research and experiment to support.
Summary of the invention
Technical matters to be solved by this invention is, there is provided a kind of based on dynamic water droplet experimental method, by analyzing the electromagnetic signals change of insulator surface electric discharge institute, thus the control method of the device of the detection transmission line of electricity external insulation of assessment insulator hydrophobicity power.
The technical solution adopted in the present invention is: a kind of control method detecting the device of transmission line of electricity external insulation, detect the device of transmission line of electricity external insulation, comprise: for supporting the inclination insulating support of sample, the upper and lower of described sample respectively correspondence is provided with high-pressure side electrode and ground electrode, described high-pressure side electrode is by resistance R connection transformer one output terminal, described ground electrode ground connection, the primary coil of described transformer connects AC power by pressure regulator, the top of described sample is provided with the dripping device for dripping to the surface being positioned at high-pressure side electrode bottom of sample, the front of described specimen surface is provided with the antenna for receiving the electromagnetic wave signal that water droplet produces when specimen surface causes electric discharge, described antenna connects filter amplification circuit, described filter amplification circuit connects computing machine by data collecting card.
The output terminal of described transformer is parallel with voltage table.
Described high-pressure side electrode and ground electrode are plate type electrode, and the spacing on the surface of sample between two electrodes is 40 ~ 60mm.
Described antenna is arranged on apart from specimen surface 9 ~ 11cm place.
The angle of inclination of described insulating support is 50 ° ~ 60 °, thus the angle of inclination of described sample is 50 ° ~ 60 °.
The NaCl solution of described water droplet to be conductance be 3 ± 0.2mS/cm.
For detecting the control method of the device of transmission line of electricity external insulation, comprise the steps:
1) sample being placed on inclination angle is on the insulating support of 50 ° ~ 60 °, and the high-pressure side electrode be connected with transformer output terminal and the ground electrode be connected to ground are placed on the surface of sample respectively;
2) connect circuit, by transformer, the power frequency ac voltage that frequency is 50Hz is risen to the voltage that effective value is 5kV, be connected to upper high-pressure side electrode by resistance, the direct ground connection of ground electrode;
3) drip to specimen surface with dripping device, water droplet is flowed down along specimen surface from upper end high-pressure side electrode, through specimen surface, flow to ground electrode place, lower end, be collected, do not executing in alive situation, dripping continuously 5 minutes;
4) filter amplification circuit receives the electromagnetic wave signal of water droplet generation when specimen surface causes electric discharge by antenna, and will deposit in computing machine by data collecting card after this electromagnetic wave signal filter and amplification;
5) computing machine extracts the electromagnetic wave signal of multiple every 1 minutes length;
6) electromagnetic wave signal of extraction is carried out small echo signal transacting, obtain the duration of signal, frequency component and amplitude, draw the three-dimensional spectrum of electromagnetic signal waveform;
7) formula is utilized to three-dimensional spectrum:
calculate vacancy rate Λ
Wherein, m is containing the quantity that fractal area is put in cube, or is called cubical " quality ", and E (m) is cubical expectation " quality ";
8) getting amplitude and specific in three-dimensional spectrum is object, draws two-dimentional spectrogram;
9) two-dimentional spectrogram is utilized to calculate corresponding fractal dimension, i.e. Hausdorff dimension;
10) recursive algorithm is utilized to draw electric discharge recurrence plot and calculate recurrence rate to discharge signal;
11) by the characterizing magnitudes that calculates and feature spectrogram, and test set up experience database characterizing magnitudes and feature spectrogram compares in the past, determine the hydrophobicity rank of sample.
The NaCl solution of described water droplet to be conductance be 3 ± 0.2mS/cm.
Described high-pressure side electrode and ground electrode are plate type electrode, and the spacing on the surface of sample between two electrodes is 40 ~ 60mm.
Step 2) described in the frequency of dripping be 12 ± 1 per minute.
The control method of the device of detection transmission line of electricity external insulation of the present invention, beneficial effect is:
1, the present invention is for the assessment of insulator hydrophobicity intensity, there is breakthrough innovation, on the basis of dynamic water droplet detection method, by measuring the electromagnetic wave signal launched and the insulator surface analyzing different digestion time discharges, obtain corresponding variation tendency spectrogram so that situation of change that is more directly perceived, clearly and accurately reflection insulator surface hydrophobic nature;
2, method safety of the present invention is reliable, non-contacting measuring method, makes survey crew and high voltage, big current isolated, does not damage testing staff, less demanding to experimental enviroment;
3, the present invention has good filter design, and reduce external interference, accuracy is high;
4, equipment of the present invention is simple, easy to operate, is beneficial to popularization.
Accompanying drawing explanation
Fig. 1 is corona aging experimental provision schematic diagram;
Fig. 2 is the sample hydrophobic nature change under the different corona aging time;
Fig. 3 is the structural representation of the device of detection transmission line of electricity external insulation of the present invention;
Fig. 4 is different aging sample corresponding surface-discharge emitting electromagnetic wave waveform;
Fig. 5 is the electric discharge three-dimensional spectrum on different aging sample surface
Wherein (a) is aging 2h sample spectrogram, b () is aging 4h sample spectrogram, c () is aging 6h sample spectrogram, d () is aging 8h sample spectrogram, e () is aging 10h sample spectrogram, (f) is aging 12h sample spectrogram;
Fig. 6 is the ratio of defects feature of 3 D video spectrogram;
Fig. 7 is two-dimentional level line spectrogram
Wherein (a) is aging 2h sample spectrogram, b () is aging 4h sample spectrogram, c () is aging 6h sample spectrogram, d () is aging 8h sample spectrogram, e () is aging 10h sample spectrogram, (f) is aging 12h sample spectrogram;
Fig. 8 is the fractal dimension of two-dimentional level line spectrogram;
Fig. 9 is the sample electric discharge recurrence plot under the different corona aging time
Wherein (a) is aging 4h sample recurrence plot, and (b) is aging 6h sample recurrence plot, and (c) is aging 8h sample recurrence plot, and (d) is aging 10h sample recurrence plot;
Figure 10 is the graph of a relation of recurrence rate and corona aging time;
Figure 11 is the fractal dimension of electromagnetic wave signal, recurrence rate and ratio of defects spectrogram method compare with Static Contact horn cupping
Wherein (a) is relative variation value, and (b) is the similarity of fractal, recurrence rate and ratio of defects and contact angle method.
In figure
1: insulating support 2: sample
3: high-pressure side electrode 4: ground electrode
5: water droplet 6: dripping device
7: antenna 8: filter amplification circuit
9: data collecting card 10: computing machine
11: pin electrode 12: sample
13: pole electroplax
Embodiment
Below in conjunction with embodiment and accompanying drawing, the control method to the device of detection transmission line of electricity external insulation of the present invention is described in detail.
The insulator surface obtaining different digestion time based on dynamic water droplet method discharges the electromagnetic wave signal launched, utilize theory of wavelet transformation, fractal theory and recursion theory, by the analysis to signal waveform, obtain correspond to different digestion time insulator surface electric discharge electromagnetic signals multiple change spectrogram, this spectrogram can accurate, clear, intuitively for the assessment of insulator hydrophobicity.
The on-the-spot composite insulator run is due to the impact of corona discharge, and its surface hydrophobicity can decline gradually, the transmission line of electricity that electric pressure is higher, and corona phenomenon is more serious.First the present invention carries out aging by the corona discharge phenomenon in multi-needle-to-plate electrode simulation non-uniform electric field to six pieces of experimental samples in corona aging experiment.Six pieces of sample digestion times are different, then the degree of its hydrophobicity loss is just different.Then in dynamic water droplet sample, the capable state of its hydrophobic is assessed.Fig. 1 is corona aging experimental provision schematic diagram.Fig. 2 is the hydrophobic nature change of six pieces of samples after corona aging.The reason that contact angle constantly reduces is mainly: the fracture of silastic surface molecular chemistry key is caused on impact ionization when there is corona discharge in corona field and electron avalanche impact specimen surface.Why silicon rubber has hydrophobic nature, it is the strong polarity effect due to silicon oxygen bond main chain, shield by the nonpolar methyl group that is closely centered around around main chain, and corona discharge causes chemical bond rupture to destroy the effect of methyl group, finally causes the forfeiture of silastic material surface hydrophobicity.
The device of detection transmission line of electricity external insulation of the present invention, comprising: for supporting the inclination insulating support 1 of sample 2, and the angle of inclination of described insulating support 1 is 50 ° ~ 60 °, thus the angle of inclination of described sample 2 is 50 ° ~ 60 °.The upper and lower of described sample 2 respectively correspondence is provided with high-pressure side electrode 3 and ground electrode 4, and described high-pressure side electrode 3 and ground electrode 4 are plate type electrode, and the spacing on the surface of sample 2 between two electrodes is 40 ~ 60mm.Described high-pressure side electrode 3 is by resistance R connection transformer T1 mono-output terminal, and described ground electrode 4 ground connection, the primary coil of described transformer T1 connects AC power by pressure regulator T2, and the output terminal of described transformer T1 is parallel with voltage table kV.The top of described sample 2 be provided with for drip to the surface being positioned at high-pressure side electrode 3 bottom of sample 25 dripping device 6, the NaCl solution of described water droplet 5 to be conductances be 3 ± 0.2mS/cm.The front on described sample 2 surface is provided with the antenna 7 for receiving the electromagnetic wave signal that water droplet produces when electric discharge is caused on sample 2 surface, and described antenna 7 is arranged on apart from 9 ~ 11cm place, sample 2 surface.Described antenna 7 connects filter amplification circuit 8, and described filter amplification circuit 8 connects computing machine 10 by data collecting card 9.
Power frequency ac voltage is produced by the transformer of 1:40 no-load voltage ratio, and output voltage is 5kV.The sample of the embodiment of the present invention adopts the silicone rubber plate through different digestion time in the test of above-mentioned corona aging, it is on the insulcrete of 60 ° that sample is placed in inclination angle, insulcrete top electrode model is plate-template electrode, and upper/lower electrode is stainless steel substrates, and upper/lower electrode spacing is 50mm.The NaCl solution of water droplet to be conductance be 3 ± 0.2mS/cm, NaCl solution flows down from upper end high-pressure side electrode along specimen surface, through specimen surface, flows to lower end ground electrode, flows in the container of preprepared bottom electrode side and collects.Do not executing in alive situation, drip frequency be about 12 ± 1 per minute, drip continuously 5 minutes.Connect circuit, then start pressurization.By transformer, the power frequency ac voltage that frequency is 50Hz is risen to the voltage that effective value is 5kV, it is connected to upper high-pressure side electrode by the cement protective resistance of a 15k Ω, the direct ground connection of ground electrode.By wideband antenna, and to discharge the electromagnetic wave signal launched through signal processing system and data acquisition system (DAS) receiving record specimen surface.
The control method of the device for detecting transmission line of electricity external insulation of the present invention, comprises the steps:
1) sample being placed on inclination angle is on the insulating support of 50 ° ~ 60 °, and the high-pressure side electrode be connected with transformer output terminal and the ground electrode be connected to ground are placed on respectively the surface of sample, described high-pressure side electrode and ground electrode are plate type electrode, and the spacing on the surface of sample between two electrodes is 40 ~ 60mm;
2) connect circuit, by transformer, the power frequency ac voltage that frequency is 50Hz is risen to the voltage that effective value is 5kV, be connected to upper high-pressure side electrode by the cement protective resistance of a 15k Ω, the direct ground connection of ground electrode;
3) drip to specimen surface with dripping device, water droplet is flowed down from upper end high-pressure side electrode along specimen surface, through specimen surface, flow to ground electrode place, lower end, be collected, do not executing in alive situation, dripping continuously 5 minutes, the NaCl solution of described water droplet to be conductance be 3 ± 0.2mS/cm, the described frequency of dripping is 12 ± 1 per minute;
4) filter amplification circuit receives the electromagnetic wave signal of water droplet generation when specimen surface causes electric discharge by antenna, and will deposit in computing machine by data collecting card after this electromagnetic wave signal filter and amplification;
5) computing machine extracts the electromagnetic wave signal of multiple every 1 minutes length;
6) electromagnetic wave signal of extraction is carried out small echo signal transacting, obtain the duration of signal, frequency component and amplitude, draw the three-dimensional spectrum of electromagnetic signal waveform;
7) formula is utilized to three-dimensional spectrum:
calculate vacancy rate Λ
Wherein, m is containing the quantity that fractal area is put in cube, or is called cubical " quality ", and E (m) is cubical expectation " quality ";
8) getting amplitude and specific in three-dimensional spectrum is object, draws two-dimentional spectrogram;
9) two-dimentional spectrogram is utilized to calculate corresponding fractal dimension, i.e. Hausdorff dimension;
10) recursive algorithm is utilized to draw electric discharge recurrence plot and calculate recurrence rate to discharge signal;
11) by the characterizing magnitudes that calculates and feature spectrogram, and test set up experience database characterizing magnitudes and feature spectrogram compares in the past, determine the hydrophobicity rank of sample.
With MATLAB software, different aging samples corresponding surface-discharge emitting electromagnetic wave waveform is as shown in Figure 4 processed, obtain the electric discharge three-dimensional spectrum on different aging sample surfaces as shown in Figure 5, the ratio of defects feature of 3 D video spectrogram as shown in Figure 6, Figure 7 shows that two-dimentional level line spectrogram, Figure 8 shows that the fractal dimension of two-dimentional level line spectrogram, Figure 9 shows that the sample electric discharge recurrence plot under the different corona aging time, Figure 10 shows that the graph of a relation of recurrence rate and corona aging time and the fractal dimension of Figure 11 electromagnetic wave signal, recurrence rate and ratio of defects spectrogram method compare with Static Contact horn cupping.Fractal theory is used to calculate fractal dimension and the similarity of each discharge spectrum, thus the hydrophobic nature of sample under assessing the different corona discharge time more intuitively.
2 hours, 4 hours, 6 hours, 8 hours, 10 hours respectively shown in Fig. 4, the single discharge waveform of 12 hours aging samples.As seen from the figure along with the corona aging time lengthens, sample discharge frequency and amplitude increase gradually, the increase of counting of violent electric discharge, and electric discharge severe degree also increases progressively.It can thus be appreciated that the electric discharge electromagnetic wave signal on the sample of different digestion time there are differences, and can process electromagnetic wave signal, extract characteristic quantity wherein for follow-up research.
Figure 5 shows that the electric discharge three-dimensional spectrum under different digestion time.This three-dimensional time-frequency spectrum can reflect the situation that the amplitude of the discharge waveform under the different corona aging time, frequency and this three parameters of time are corresponding intuitively, and its mountain peak, surface, hills irregular, in every width figure, parameters change is different.According to its changing features, can analyze the increase along with the corona aging time, the hydrophobic nature of sample reduces gradually initial characterization, thus aggravates in the surface-discharge of DDT experiment.
Figure 6 shows that the ratio of defects feature of three-dimensional time-frequency spectrum, along with the increase of sample corona aging time in figure, ratio of defects and fractal dimension are all in increasing trend.Indicate rule and net result that sample discharge characteristic increases progressively along with digestion time, and just can identify these six kinds of samples intuitively.Also illustrate that to the sample hydrophobic nature under the different corona aging time, to there is rational separating capacity by the ratio of defects extracted in three-dimensional feature spectrogram and these two characteristic quantities of fractal dimension simultaneously, can as one of analysis means of Hydrophobicity of Composite Insulator assessment.
Figure 7 shows that two-dimentional level line spectrogram.This six width figure depicts frequency, relation between time and amplitude.The amplitude of electric discharge is expressed by level line spectrogram, illustrates the energy of electric discharge.Spectrogram dense degree high heel when isocontour dense degree can find out that the corona aging spectrogram of 12 hours is obviously little than 2 from figure is many, and all shows a rising trend along with the discharge energy of each spectrogram of increase of discharge time and complexity.
Figure 8 shows that the fractal dimension of two-dimentional level line spectrogram.Based on two-dimentional level line spectrogram, we analyze 6 kinds of relations between discharge spectrum and insulator hydrophobicity rank quantitatively by calculating the fractal dimension of spectrogram.For the fractal dimension statistics bar chart of the sample under the individual digestion time that two-dimentional level line spectrogram is corresponding, the relation between sample hydrophobic nature under different digestion time can be found out more intuitively from figure.Values of fractal dimension is from 1.4 to 1.6 incremental variations, show the trend along with the sustainable growth of insulator hydrophobicity reduction values of fractal dimension, this Trend Forecasting specimen surface electric discharge and is become and more and more do not have rule to become increasingly complex, and in the degree of aging of this and specimen surface and wavelet transformed domain, the energy variation of electric discharge is consistent.The electric discharge two dimension level line fractal dimension difference respectively organizing sample for 2 ~ 12 hours is comparatively average, and gradient is basically identical.
Figure 9 shows that the sample electric discharge recurrence plot under the different corona aging time.4 width figure in Fig. 9 give the relation of recurrence rate respectively and between the electric discharge of corona aging 4,6,8,10 hours samples.All there is the diagonal line of a lower-left to upper right in this four width recurrence plot, this and variable X (i) are from relevant as 0.All circulation points are the equal regularity of distribution in recurrence plot, and this recursive structure is by the inherent law imagery of discharge signal, visual.When ac high-voltage is applied on insulator sample, Leakage Current flows through insulating surface and causes the evaporation of electrolysis drop just to define dry zone, thus defines dry zone electric discharge.Along with the increase of composite insulator sample corona aging time, dry zone electric discharge aggravation.Recurrence plot under this different corona aging time also provides the trend describing discharge signal change.
Figure 10 shows that the graph of a relation of recurrence rate and corona aging time.Relation between the quantitative surface-discharge feature recurrence rate giving 6 kinds of corona aging times and sample.Therefrom draw to also exist between the recursive feature that corona aging time and specimen surface discharge and contact closely, namely along with the increase of corona aging time, recurrence rate also significantly improves, great difference is had between the recurrence rate of especially 2,4 hours and the recurrence rate of 12 hours, that is along with the reduction of Hydrophobicity of Composite Insulator, recurrence rate increases gradually.The contrast effect of especially 2,4 and 6 hours is the most obvious, and sample insulator hydrophobicity gradient is maximum.Can show that recurrence quantification analysis contributes to disclosing the variations in detail of surface-discharge feature thus, be a kind of aid of effective assessment insulator.
Figure 11 shows that comparing of the fractal dimension of electromagnetic wave signal, recurrence rate and ratio of defects spectrogram method and Static Contact horn cupping.Representated by each line segment of Figure 11 (a) is the relative variation tendency of the fractal dimension of above-mentioned three kinds of relation spectrums and the comparison diagram of the relative variation tendency of static contact angle.In order to ensure accuracy, each standard value chosen is the maximal value in the method, and for the calculating of relative variation, therefore relative changing value is the slip of actual value, and its variation tendency and former fractal dimension and static contact angle are consistent.As seen from the figure, the changing value of ratio of defects is maximum, and the changing value of fractal dimension is minimum, and recurrence rate mediates, and the changing value of static contact angle is relatively large.Therefore, can find out that the degree of approach of the change amplitude of ratio of defects and static contact angle is maximum.Figure 11 (b) is fractal dimension, recurrence rate and ratio of defects and traditional Static Contact horn cupping compare the Similarity value obtained, can visually see the Similarity value of three kinds of methods and contact angle method all higher than 0.9 from figure, illustrate three kinds of methods to Hydrophobicity of Composite Insulator can assessment result and the result assessed of contact angle method closely, accuracy is very high.Illustrate and analyze creeping discharge characteristic relation by recurrence rate to assess the method accuracy of Hydrophobicity of Composite Insulator very high, adopt the method to carry out analysis and assessment to silicon rubber compound insulator hydrophobic nature and there is higher accuracy, reliability.
Claims (4)
1. one kind is detected the control method of the device of transmission line of electricity external insulation, the device of described detection transmission line of electricity external insulation comprises: for supporting the inclination insulating support (1) of sample (2), the upper and lower of described sample (2) respectively correspondence is provided with high-pressure side electrode (3) and ground electrode (4), described high-pressure side electrode (3) is by resistance R connection transformer (T1) output terminal, described ground electrode (4) ground connection, the primary coil of described transformer (T1) connects AC power by pressure regulator (T2), the top of described sample (2) is provided with the dripping device (6) for drip to the surface being positioned at high-pressure side electrode (3) bottom of sample (2) (5), the front on described sample (2) surface is provided with the antenna (7) for receiving the electromagnetic wave signal that water droplet produces when electric discharge is caused on sample (2) surface, described antenna (7) connects filter amplification circuit (8), described filter amplification circuit (8) connects computing machine (10) by data collecting card (9), it is characterized in that, comprise the steps:
1) sample being placed on inclination angle is on the insulating support of 50 ° ~ 60 °, and the high-pressure side electrode be connected with transformer output terminal and the ground electrode be connected to ground are placed on the surface of sample respectively;
2) connect circuit, by transformer, the power frequency ac voltage that frequency is 50Hz is risen to the voltage that effective value is 5kV, be connected to upper high-pressure side electrode by resistance, the direct ground connection of ground electrode;
3) drip to specimen surface with dripping device, water droplet is flowed down along specimen surface from upper end high-pressure side electrode, through specimen surface, flow to ground electrode place, lower end, be collected, do not executing in alive situation, dripping continuously 5 minutes;
4) filter amplification circuit receives the electromagnetic wave signal of water droplet generation when specimen surface causes electric discharge by antenna, and will deposit in computing machine by data collecting card after this electromagnetic wave signal filter and amplification;
5) computing machine extracts the electromagnetic wave signal of multiple every 1 minutes length;
6) electromagnetic wave signal of extraction is carried out small echo signal transacting, obtain the duration of signal, frequency component and amplitude, draw the three-dimensional spectrum of electromagnetic signal waveform;
7) formula is utilized to three-dimensional spectrum:
calculate vacancy rate Λ
Wherein, m is containing the quantity that fractal area is put in cube, or is called cubical " quality ", and E (m) is cubical expectation " quality ";
8) getting amplitude and specific in three-dimensional spectrum is object, draws two-dimentional spectrogram;
9) two-dimentional spectrogram is utilized to calculate corresponding fractal dimension, i.e. Hausdorff dimension;
10) recursive algorithm is utilized to draw electric discharge recurrence plot and calculate recurrence rate to discharge signal;
11) by the characterizing magnitudes that calculates and feature spectrogram, and test set up experience database characterizing magnitudes and feature spectrogram compares in the past, determine the hydrophobicity rank of sample.
2. the control method of the device of detection transmission line of electricity external insulation according to claim 1, is characterized in that, the NaCl solution of described water droplet to be conductance be 3 ± 0.2mS/cm.
3. the control method of the device of detection transmission line of electricity external insulation according to claim 1, is characterized in that, described high-pressure side electrode and ground electrode are plate type electrode, and the spacing on the surface of sample between two electrodes is 40 ~ 60mm.
4. the control method of the device of detection transmission line of electricity external insulation according to claim 1, is characterized in that, step 2) described in the frequency of dripping be 12 ± 1 per minute.
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| US5963410A (en) * | 1995-08-02 | 1999-10-05 | Matsushita Electric Industrial Co., Ltd. | Insulation testing method and apparatus therefor |
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| 基于放电特征检测的复合绝缘子憎水性评估方法研究;杨本星;《万方学位论文》;20110803;正文第14-15页，图2-4 * |
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