CN101694481B - Ultrasonic detecting system and detecting method of surface state of inner electrode made of solid insulating material - Google Patents

Abstract

The invention discloses an ultrasonic detecting system and a detecting method of a surface state of an inner electrode made of solid insulating material. The system comprises an ultrasonic probe, an ultrasonic receiving and transmitting device, a data acquiring card, a computer, a mechanical positioning device and a carrying pool, wherein the computer is connected with the ultrasonic receiving and transmitting device through the data acquiring card; the ultrasonic probe is connected to the ultrasonic receiving and transmitting device; the ultrasonic probe is fixed on the mechanical positioning device; the carrying pool is arranged below the mechanical positioning device, filled with coupling agents and provided with the solid insulating material inner electrode at the bottom; and the mechanical positioning device is used for moving the ultrasonic probe in the vertical direction and the horizontal direction. The detecting method can be used for detecting the surface state of a capacitive type inner electrode with an insulated structure and can be also used for detecting the main insulation aging of an engine.

Description

The ultrasonic testing system of surface state of inner electrode made of solid insulating material and detection method thereof

Affiliated technical field

The invention belongs to power equipment manufacturing and detection technique field, use ultrasonic method to detect surface state of inner electrode made of solid insulating material.

Background technology

Condenser type insulation system power equipment is meant and uses the capacitance type structure mode to constitute its insulation in the power equipment, to reach effects such as dividing potential drop, division electric field.

Common have condenser type current transformer, bushing, coupling condenser, capacitance type potential transformer, a power capacitor etc.With the capacitance type potential transformer is example, and capacitance type potential transformer is actually by a capacitive divider and calutron partly to be formed.Its crucial dividing potential drop part is by several capacitors in series, a termination high-tension line, other end ground connection.To need measured voltage to extract through a small capacitor according to the capacitance partial pressure principle.Capacitance type potential transformer has obtained using widely in the 110 ~ 500kV of China power network.

Common power capacitor fuse is overrided to form by several elements and insulating part in the electric system in addition, and element is compound with kraft capacitor paper or film paper, or makes medium and aluminium platinum with pure film and roll as pole plate and form.Its structural drawing such as Fig. 2-1, and wherein dash area A, B are metal polar plate (being generally aluminium foil).

Condenser-type terminal in the electric system is that high-pressure system is the most often used for another example; Condenser-type terminal adds a capacitor core as interior insulation between guide rod and flange; The multiple layer metal pole plate is arranged, to force the homogenising of its internal electric field of control and surface field in the capacitor core.Its performance depends primarily on capacitor core.With common dry sleeve is example, its core structures figure such as Fig. 1-2.Fuse is to surround on the guide rod with cable paper, when holding certain diameter, wraps the aluminium foil pole plate, and the pole plate size need be passed through detailed calculated, and strict control.With the synthetic resin dipping, form through being heating and curing again then.

Though have many similar condenser type insulation system power equipments in the electric system, its basic structure all is the capacitor-type structure, i.e. fill insulant between the electrode that certain material is processed.

About of the influence of metal polar plate form for internal electric field, study lessly, but its influence to the condenser type insulating reliability is still very big.Lot of materials is pointed out; In a lot of condenser type insulation systems; There is large number quipments all to select for use metal formings such as aluminium foil as electrode; And all quite strict to its shape and status requirement, like each layer electrode in the preceding sleeve pipe of mentioning, generally distance between them and length all claimed accuracy all less than 0.01mm.

Because the size of elements such as power capacitor, sleeve pipe, fuse is bigger, must use the major axis bushing machine in recent years.But because bushing machine the axle depth of parallelism is poor, pulling force is inconsistent, when rotating in big, the aluminium foil possibility changing of the relative positions of vibrations even the paper factors such as variation of institute's water content all possibly cause aluminium foil wrinkling.And aluminium foil is in a single day wrinkling, then can cause the internal electric field skewness, and breakdown field strength is reduced, and firing potential reduces.

For the condenser type insulation system, at the inner a certain ad-hoc location of insulating medium, insulating material is normally opaque, can't directly detect usually in the position of metal electrode.Because method of optics can only be observed fold, but can't the degree of fold be quantized simultaneously, therefore can not use simple measuring method to realize.Along with the appearance of science and technology development and new material, the scope of acoustic applications is more and more wider, and in the existing considerable application of electric system kind, technology is comparative maturity, therefore selects for use ultrasonic method to carry out the detection of electrode shape in the epoxy composite material.

In the long-term operational process of generator, major insulation is subjected to the synergy of electric field, thermal field, mechanical stress, thermal stress and environmental stress, and its insulating property descend gradually, finally causes failure of insulation.Because the high-rating generator expense has high input, the output economic benefit is high, in case occur that the loss that non-programmed halt causes is big, to involve scope wide, its operational reliability is very important.Along with the reform of electric power system deepens continuously, the new frame of separating the factory and network, surfing the Net at a competitive price is about to form, and the generator insulating state directly becomes one of important evidence of electricity power enterprise's business decision.

The insulation of high-rating generator detects and is developed to the repair based on condition of component direction by prophylactic repair and periodic maintenance.Repair based on condition of component reduces the maintenance number of times on the basis that guarantees the generator operation reliability, prevent in unnecessary maintenance process, to cause direct to equipment and damage indirectly, reduces greatly and overhauls and maintenance cost.According to the statistics of Japanese Shikoku Denliyoku Co., Ltd., under the condition of not exclusively carrying out repair based on condition of component, can practice thrift 20 ~ 30% of recondition expense.Big motor stator insulated state of insulation diagnosis and residual life evaluation are significant.

Around this problem, insulation ag(e)ing characteristic parameter, aging rule and residual life evaluation have become the research content in domestic and international insulation field.The external predicting residual useful life that will move generator more than 15 years is classified emphasis research topic as.China's the seventies and the 100MW that puts into operation in the past and more jumbo generator have 110, have moved more than 20 years.If can carry out efficient diagnosis to state of insulation through the detection of insulation ag(e)ing characteristic quantity, the insulation residual life is effectively assessed, rationally arrange the maintenance and repair of generator, prolong its serviceable life, with obtaining huge economic benefit.

Ultrasonic method is through the measurement of material acoustics parameter being confirmed the ageing state of material, and supersonic detection method is because its plurality of advantages becomes the focus of studying this year.

Summary of the invention

The present invention proposes detection system and detection method thereof with the configuration of surface of electrode in the invisible solid material of focus ultrasonic probe measurement, technical scheme of the present invention is following.

A kind of ultrasonic testing system of surface state of inner electrode made of solid insulating material, this system is made up of ultrasonic probe, ultrasonic R-T unit, data collecting card, computing machine, mechanical positioner and loading pond; Said computing machine is connected with ultrasonic R-T unit through data collecting card; Be connected with ultrasonic probe on the ultrasonic R-T unit; Ultrasonic probe is fixed on the mechanical positioner; The mechanical positioner below is provided with the loading pond, and loading is full of couplant in the pond, places electrode in the insulating material in bottom, loading pond; Said mechanical positioner is used to make ultrasonic probe to move at vertical and horizontal both direction.

Said ultrasonic R-T unit is the pulse reflection reflectoscope; Said ultrasonic probe is the immersion type focusing probe.

Said mechanical positioner comprises objective table and mechanical arm, and ultrasonic probe is fixed on the mechanical arm and can on two dimensional surface, accurately moves arbitrarily.

A kind of supersonic detection method of surface state of inner electrode made of solid insulating material:

(1) electrode in the insulating material is placed bottom, loading pond;

(2) regulate ultrasonic R-T unit parameter, adjust the parameter of ultrasonic R-T unit, make the waveform that receives steady and audible, guarantee that whole detection system normally moves;

(3) through the position of mechanical positioner adjustment ultrasonic probe in the loading pond, make ultrasonic probe aim at electrode in the insulating material, and guarantee that electrode separation is near the ultrasonic probe focal length in ultrasonic probe and the insulating material;

(4) go out distance between electrodes in ultrasonic probe and the insulating material through COMPUTER CALCULATION, and the distance that will calculate is stored as primary data;

(5) arrive next position, repeating step (4) then through mechanical positioner vertical moving ultrasonic probe; When in the ultrasonic probe traversal insulating material during electrode, execution in step (6);

The data acquisition that (6) will be stored in the computing machine is depicted as three-dimensional picture demonstration or output.

The effect of invention:

According to the characteristics of typical capacitance formula insulation system, a little copper sheet ring is close to aluminium foil surface and is enclosed in the epoxy in the sample, and small circle ring thickness is 0.5mm, and ring width is 0.5mm, and mean diameter is 2.8mm.To check the detection that the outline line that contains curve is risen and fallen and to detect the influence of step-length to accuracy of detection.

Adopt 0.1mm as detecting its testing result of step-length.

Wherein its width range of sample b is 0.5mm ± 0.2mm, and thickness range is 0.5 ± 0.02mm, and diameter is 2.8mm ± 0.2mm, is 0.2mm with the sample b situation maximum error that also conforms to.Border and surface profile are more clear.

Through above method, can detect the metal polar plate form in the condenser type insulation system.

For the condenser type insulation system; Usually at the inner a certain ad-hoc location of insulating medium, as stated, the insulating paper that 8 layer thicknesses is about 0.2mm is range upon range of in the position of aluminium foil electrode; In the middle of the insulating paper layer the (promptly the 4th; 5 layers of centre) place an aluminium foil layer, the aluminium foil average thickness is about 0.01mm, carries out epoxy vacuum pouring and curing then.The folding line of aluminium foil then is to be produced by the tangential oblique stress, the fold that causes with simulation bushing machine pulling force uneven or individual axle depth of parallelism difference.After the zone of selecting carried out ultrasonic scanning,, carry out three-dimensional with matlab and reduce its raw data input computing machine.

Select suitable detection step-length and the probe that has appropriate frequency and Jiao Qu then can realize high Precision Detection.When adopting the 10MHz focusing probe, when the mechanical arm precision was 0.1mm, interfacial configuration detects transverse precision can reach 0.14mm; Detect vertical precision and can reach 0.02mm.

This detection method can be used for detecting the detection of condenser type insulation system surface state of inner electrode made, also can be used for the aging detection of generator stator insulation simultaneously.

Advantage of the present invention:

1, proposed the supersonic detection method of surface state of inner electrode made of solid insulating material first, and designed detection system, for the analyzing electrode form provides important evidence to electric field effects.

2, propose to use the immersion type focusing probe to be used for the detection of insulating material, compare with the normal probe detection mode of broad research in the past, stronger to the resolution characteristic of the small fluctuating of electrode surface;

3, probe can move arbitrarily on two dimensional surface, and the location accurately.

Description of drawings:

Fig. 1 is that test macro of the present invention is formed synoptic diagram;

Wherein: 1, ultrasonic probe; 2, tank; 3, mechanical positioner; 4, ultrasonic R-T unit; 5, number is adopted card; 6, PC.

Fig. 2 is mechanical positioner of the present invention and loading pool structure vertical view;

Embodiment:

Below in conjunction with accompanying drawing the present invention is done and to describe in further detail:

A kind of ultrasonic testing system of surface state of inner electrode made of solid insulating material, this system is made up of ultrasonic probe, ultrasonic R-T unit, data collecting card, computing machine, mechanical positioner and loading pond; Said computing machine is connected with ultrasonic R-T unit through data collecting card; Be connected with ultrasonic probe on the ultrasonic R-T unit; Ultrasonic probe is fixed on the mechanical positioner; The mechanical positioner below is provided with the loading pond, and loading is full of couplant in the pond, places electrode in the insulating material in bottom, loading pond; Said mechanical positioner is used to make ultrasonic probe to move at vertical and horizontal both direction.

Said ultrasonic R-T unit is the pulse reflection reflectoscope; Said ultrasonic probe is the immersion type focusing probe.

Said mechanical positioner comprises objective table and mechanical arm, and ultrasonic probe is fixed on the mechanical arm and can on two dimensional surface, accurately moves arbitrarily.

A kind of supersonic detection method of surface state of inner electrode made of solid insulating material:

(1) electrode in the insulating material is placed bottom, loading pond;

(2) regulate ultrasonic R-T unit parameter, adjust the parameter of ultrasonic R-T unit, make the waveform that receives steady and audible, guarantee that whole detection system normally moves;

(3) through the position of mechanical positioner adjustment ultrasonic probe in the loading pond, make ultrasonic probe aim at electrode in the insulating material, and guarantee that electrode separation is near the ultrasonic probe focal length in ultrasonic probe and the insulating material;

(4) go out distance between electrodes in ultrasonic probe and the insulating material through COMPUTER CALCULATION, and the distance that will calculate is stored as primary data;

(5) arrive next position, repeating step (4) then through mechanical positioner vertical moving ultrasonic probe; When in the ultrasonic probe traversal insulating material during electrode, execution in step (6);

The data acquisition that (6) will be stored in the computing machine is depicted as three-dimensional picture demonstration or output.

Selected appropriate probe type.

1, the selection of probe type:

Ultrasound detection probe commonly used has normal probe, angle probe, focusing probe etc.In order to select suitable probe, the special standard sample that is equipped with, sample is that the epoxy that uses in the dry sleeve soaks isolit, thickness 4.8mm.

In numerous probes, using maximum normal probes is the probe that makes ultrasound wave vertical incidence subject, mainly is used for launching and accepting compressional wave, so be also referred to as longitudinal wave probe.And focusing probe is can ultrasound wave be converged to pencil shape or probe traditional thread binding, point-like.The characteristics of focusing probe are can the Jiao Qu of concentration of energy can be improved the flaw detection resolving power.Focusing probe uses in the immersion method of being everlasting.It is worthy of note that focusing probe is with in sound field focusing to the very little zone, measure focusing acoustic field through burnt district's diameter phi commonly used and burnt section length L.Frequency like focusing probe is h, and the velocity of sound in medium is v, and focal length is F, and wafer diameter is D, then

$\mathrm{\φ}=\frac{v}{h}\frac{F}{D}---(3-1)$

$L=4\frac{v}{h}{\left(\frac{F}{D}\right)}^2---(3-2)$

Immersion probe is can be immersed in the liquid to detect a flaw, do not contact with material, and the film that do not need protection, its structure is similar with normal probe.

And for the condenser type insulation system, the position of electrode perhaps is clipped in a certain ad-hoc location in the insulating medium usually on the surface.This just is very suitable for that focusing probe concentrates on sound field on the focus point is to carry out ultrasound detection on the face of electrode place.And to above-mentioned a lot of composite insulating materials,, therefore use focusing probe that sound field is concentrated because factor such as material molecule is big, and viscoelasticity is strong, and material is inhomogeneous makes SATT big, improve resolving power and penetration power.

As can be seen from the figure, when the focusing probe focal length being placed on surface when lasting, the surface, Bottom echo is clear, and that clutter amplitude echo is compared is much smaller, and this just efficiently solves the interference of other contact bed for the detection contact bed.Therefore, focusing probe is to be fit to very much detect condenser type insulation system electrode surface form.

2, frequency probe is to the influence of ultrasonic echo:

Because when sound wave is propagated in different medium, inevitably scattering can take place, frequency is high more; Wavelength is short more; Ultrasound wave is scattered easily, and it is big more to decay, and therefore must select the probe of appropriate frequency for checked object; Can not blindly select big frequency probe, in order to avoid make echoed signal too little so that distinguish for difficult time.But frequency probe is also too small.In order to guarantee enough resolving powers, frequency probe again must be enough high.

According to ultrasonic theory, ultrasound wave finds that the theoretical resolution of defective is: $\frac{1}{2}\mathrm{\λ}=\frac{1}{2}\×\frac{v}{h},$ If select the probe of different frequency for use, its theoretical resolution is like table 3-1.Significantly detect, select high more frequency good more certainly for condenser type insulation system electrode surface form.Its theoretical resolution of focusing probe with 10MHz can reach below the 0.1mm, shown in the detection of echoes signal such as Fig. 3-1 of standard sample, proves the resolving power that not only can obtain 0.1mm with the focusing probe of 10MHz, can also obtain enough big echo.Therefore can use the focusing probe of 10MHz to come the electrode surface form is detected.

Table 3-1 different frequency probe theoretical precision

3, detection system is formed:

After having confirmed the various parameters of ultrasound detection, made up corresponding ultrasonic testing system, this system comprises: mechanical positioner, probe, ultrasonic R-T unit, number are adopted card and computer system.

The principle of work of system is: ultrasonic generator is launched synchronous electric pulse, excites the piezoelectric chip vibration in the probe to produce ultrasound wave, simultaneously synchronously electric pulse after trigger delay as the scanning trigger pip of data collecting card.The ultrasound wave that sonac produces is propagated in sample; Running into the interface launches on the interface; The reflection wave backpropagation, and by launching hyperacoustic ultrasonic probe reception and converting electric impulse signal to, behind signal conditions such as ultrasonic probe, ultrasonic receiver coupling, decay, amplification and filtering; By the data collecting card digitizing; Special software in the input computing machine is realized collection, the demonstration of ultrasound detection signal, through data being handled measurement and the demonstration that can carry out epoxy organic composite material surface state of inner electrode made.

Mechanical positioner and tank: quantitatively adjustable in order to realize probe at two-dimensional directional, designed mechanical positioner.As shown in the figure.Adopt two optical rail that move each other to build the mechanical arm of two-dimensional adjustable, ultrasonic probe is fixed on the mechanical arm and can on two dimensional surface, moves arbitrarily, and the moving range of both direction is 150mm, and minimum moving step length is 0.1mm.The probe fixing device of design is fixed on the objective table by a fastening bolt voluntarily, and the probe adjustable height.Because the couplant of focusing probe is a water, therefore according to the size design of sample the loading pond, the bottom surface is that a length of side is the square of 150mm.

2, ultrasonic probe

Use the immersion type focusing probe, frequency is 10MHz, wafer size 14mm, focal length 20mm

3, ultrasonic R-T unit

Adopt Shantou CTS-26 of ultrasonic electronic company limited pulse reflection reflectoscope, this defectoscope frequency of operation covers 0.5M-20MHz, and overall attenuation is 90dB, and various types of probes basically all can use supporting with it.

4, number is adopted card

Selected the USB-5133 data collecting card of America NI (National Instruments) company for use, its performance index are shown in table 3-1.

The main performance index of table 3-1 data collecting card

Effect of the present invention:

1, proposes the supersonic detection method of surface state of inner electrode made of solid insulating material, and designed detection system;

2, study the performance of normal probe and focusing probe, confirmed to detect type and the frequency of using probe;

3, the precision that the electrode surface form is detected of a whole set of detection system can reach 0.1mm;

Designed mechanical positioner, probe can the step-length with 0.1mm accurately be moved on two dimensional surface.

System software:

Native system adopts LabVIEW pattern development language to design system software based on the hardware platform of computing machine and data collecting card formation.System software is realized collection, the demonstration of ultrasound detection signal, through data being handled measurement and the demonstration that can carry out epoxy organic composite material surface state of inner electrode made through the control to digital capture card.

The data acquisition function module is mainly accomplished the collection of data and the real-time Presentation Function of waveform;

The function of data processing module is to calculate testee to the distance between the probe according to the Wave data of one-shot measurement;

The three-dimensional picture display module is that the data that data processing module obtains are shown, so that observe the configuration of surface of testee intuitively.

Filtration module has adopted wavelet filtering and Butterworth filtering; At first carry out the signal wavelet filtering to remove the white noise that various approach produce; Carry out Butterworth filtering again, remove the high and low frequency signal, Wave data is carried out filtering can make the calculating of data processing module more accurate.

Claims (1)

1. detection method based on the ultrasonic testing system of surface state of inner electrode made of solid insulating material,

This system is made up of ultrasonic probe, ultrasonic R-T unit, data collecting card, computing machine, mechanical positioner and loading pond; Said computing machine is connected with ultrasonic R-T unit through data collecting card; Be connected with ultrasonic probe on the ultrasonic R-T unit; Ultrasonic probe is fixed on the mechanical positioner; The mechanical positioner below is provided with the loading pond, and loading is full of couplant in the pond, places electrode in the insulating material in bottom, loading pond; Said mechanical positioner is used to make ultrasonic probe to move at vertical and horizontal both direction;

Said ultrasonic R-T unit is the pulse reflection reflectoscope; Said ultrasonic probe is a focusing probe; Said couplant is a water;

Said mechanical positioner comprises objective table and mechanical arm, and ultrasonic probe is fixed on the mechanical arm and can on two dimensional surface, accurately moves arbitrarily;

It is characterized in that:

(1) electrode in the insulating material is placed bottom, loading pond;

(2) parameter of the ultrasonic R-T unit of adjustment makes the waveform that receives steady and audible, guarantees that whole detection system normally moves;

(3) through the position of mechanical positioner adjustment ultrasonic probe in the loading pond, make ultrasonic probe aim at electrode in the insulating material, and guarantee that electrode separation is near the ultrasonic probe focal length in ultrasonic probe and the insulating material;

(4) go out distance between electrodes in ultrasonic probe and the insulating material through COMPUTER CALCULATION, and the distance that will calculate is stored as primary data;

(5) arrive next position, repeating step (4) then through mechanical positioner vertical moving ultrasonic probe; When in the ultrasonic probe traversal insulating material during electrode, execution in step (6);

The data acquisition that (6) will be stored in the computing machine is depicted as three-dimensional picture demonstration or output.

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