CN103823168A - Circuit and device for detecting local discharge of gas insulated enclosed composite apparatus - Google Patents
Circuit and device for detecting local discharge of gas insulated enclosed composite apparatus Download PDFInfo
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- CN103823168A CN103823168A CN201410085333.9A CN201410085333A CN103823168A CN 103823168 A CN103823168 A CN 103823168A CN 201410085333 A CN201410085333 A CN 201410085333A CN 103823168 A CN103823168 A CN 103823168A
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Abstract
The invention discloses a circuit for detecting local discharge of a gas insulated enclosed composite apparatus, wherein an ultrasonic acoustoelectric sensor is accessed between a reverse input end and a non-inverting input end of a first charge amplifier; an overlapped output signal of a bypass pulse signal and an ultrasonic acoustoelectric signal is generated; a fixed capacitor is accessed between the reverse input end and the non-inverting input end of a second charge amplifier to form a pure bypass pulse current signal; the reverse input end and the non-inverting input end of a differential amplifier are respectively connected with the output ends of the first charge amplifier and the second charge amplifier and used for inhibiting the bypass pulse current signal and outputting a pure ultrasonic acoustoelectric signal which is directly proportional to the difference between the non-inverting input pure bypass pulse current signal and the reversely input overlapped signal of the bypass pulse current signal and ultrasonic acoustoelectric signal. A device for detecting the local discharge of the gas insulated enclosed composite apparatus is also proposed by the invention.
Description
Technical field
The invention belongs to transmission facility detection technique field, be specifically related to a kind of gas-insulated gas insulated metal enclosed swit chgear detection circuit for partial discharge and device based on pulse current and Ultrasonic Detection.
Background technology
GIS equipment (Gas Insulated Switchgear) is gas-insulated gas insulated metal enclosed swit chgear, a kind of Novel power transmission equipment occurring the sixties in 20th century, it is combined in the function device of other except transformer in transformer station in metal shell one by one, and fill the gas with SF6, thereby improve the safety and reliability of these transmission of electricity switchgears.The domestic GIS equipment of introducing since the eighties in 20th century, at present still in the middle of continuation expands application.Although the design of GIS equipment is exactly that its inner partial discharge phenomenon also can cause fault even to lead to a disaster in order to realize safety and reliability.Once and break down, only have and change there is the associated components at shelf depreciation position, extremely waste time and energy, the normal operation of electric system is made a big impact.For electric system is recovered as early as possible from fault, first to position the occurrence positions of shelf depreciation, then just likely carry out rapidly and effectively safeguard.As can be seen here, the detection and localization of GIS shelf depreciation has important practical significance to electric power operation department.
In addition, as manufacturer or the construction business of GIS equipment, need to, by can find defect, the mistake in GIS insulation manufacturing process and installation process to the detection of shelf depreciation, improve " cleanliness " manufacturing and install, and determine the position of these defects.Therefore, GIS Partial Discharge Detection positioning equipment is the powerful measure of quality assurance in GIS manufacture process.
Along with the raising of the importance of GIS in electric system, for guaranteeing that GIS moves reliably and with long-term, its insulation diagnosis is also more and more paid attention to.As the effective means that judges GIS insulation status, in GIS, the detection technique of shelf depreciation also develops rapidly.The method of measurement of partial discharge is a lot, is simply described below:
(1) pulse current method
Be called again coupling capacitance method, it utilizes the capacitance electrode coupling being attached on GIS shell to survey the change in voltage that shelf depreciation causes in conductor cores.The method is simple in structure, is convenient to realize.But while test at the scene, the local discharge signal that None-identified and multiple noise are mixed in together, therefore the use of this method is promoted and is greatly limited.
(2) superfrequency electromagnetic wave (UHF) detection method
The UHF method that Strathclyde university of Britain proposes has been applied to GIS production and in service at present, and it is a kind of method of utilizing ultrahigh frequency frequency signal to carry out partial discharge monitoring.Once GIS partial discharge phenomenon, will produce pulse current, current impulse rise time and duration are only nanosecond (nS) level.This current impulse will inspire frequency electromagnetic waves, its main frequency range is 0.3-3GHz, this electromagnetic wave can leak from the disk insulator on GIS, adopt uhf sensor (frequency range is 0.3-3GHz) to measure the electromagnetic wave at insulation gap place, then analyze the order of severity of shelf depreciation according to the signal intensity receiving.
The method can live line measurement, and measuring method does not change the method for operation of equipment, and can realize on-line continuous monitoring.Can effectively suppress ground unrest by methods such as filtering, thereby there is stronger antijamming capability.But the method only can be confirmed the generation of fault mostly, can not locate accurately the point breaking down.
(3) supercritical ultrasonics technology
GIS shelf depreciation can produce sound wave, and its type comprises compressional wave, shear wave and surface wave.Compressional wave passes to shell by gas, and shear wave needs to pass to shell by solid dielectric (such as insulator etc.).Receive these acoustic signals by the piezoelectric type acoustoelectric sensor that is attached to GIS case surface, the object of putting to reach monitoring GIS office.Therefore can be used in the ultrasonic sensor of installing on chamber outer wall and measure shelf depreciation.
The sensor of the method also contacts without any with the electric loop of GIS equipment, is not subject to the interference of electric aspect.Equipment is easy to use, and technology is relatively ripe, and rig-site utilization experience is abundanter, the method of operation that can not change equipment is carried out live line measurement, ultrasonic signal due to what measure, therefore more intense to the antijamming capability of electromagnetic interference (EMI), can position defect.But the method also has that ultrasonic signal and discharge pulse current signal cannot be distinguished, noise need be pasted on GIS equipment compared with low, sensor compared with large, sensitivity and the cheap shortcoming such as use not.
(4) optical monitoring method
Photomultiplier cell can monitor the even transmitting of a photon, but because ray is absorbed consumingly by SF6 gas and glass, therefore have " dead angle " to occur, the method is more effective for the monitoring rate of known discharge source position, but does not possess the station-keeping ability to fault.And the impact that the reflection causing due to GIS inner wall smooth brings, causes sensitivity not high.
The feature of summing up said method, we can draw to draw a conclusion.UHF method antijamming capability is strong, highly sensitive, but testing circuit is high-frequency circuit, and technical difficulty is larger.In addition,, though the method also can realize localization of fault in principle, the algorithm of localization of fault is very complicated, is unfavorable for equally controlling the cost of checkout equipment.Although ultrasonic Detection Method can realize location, lower because of its sensitivity, be unfavorable for the detection of the faint electric discharge in GIS, be therefore just unfavorable for the early diagnosis of GIS fault.
Analyze theoretically, any ultrasonic acoustoelectric sensor all can be considered as an electric capacity, and therefore its effect is completely the same with the effect of the coupling capacitance in above-mentioned " pulse current method method ", and the pulse current that shelf depreciation directly can be produced is coupled into.But as the acoustoelectric sensor of ultrasonic method, what we will detect is the electric signal that ultrasound wave obtains by acoustoelectric effect conversion on sensor, above-mentioned coupling and the pulse current that obtains has just become noise.
Summary of the invention
(1) technical matters that will solve:
The noise that the pulse current obtaining in order to solve prior art coupling causes, the object of the invention is to attempt to separate ultrasonic acoustoelectric signal and pulsed current signal, and they are fully utilized, improve sensitivity to GIS Partial Discharge Detection and the precision of location, propose a kind of GIS detection circuit for partial discharge and device based on pulse current and Ultrasonic Detection for improving the signal to noise ratio (S/N ratio) of the ultrasonic acoustoelectric signal in ultrasonic acoustoelectric sensor.
(2) technical scheme:
A first aspect of the present invention, a kind of testing circuit to gas-insulated gas insulated metal enclosed swit chgear shelf depreciation is proposed, this testing circuit is made up of the first charge amplifier, the second charge amplifier, differential amplifier, ultrasonic acoustoelectric sensor and a fixed capacity, wherein:
Between the reverse input end of the first charge amplifier and in-phase input end, access ultrasonic acoustoelectric sensor, ultrasonic acoustoelectric sensor receives bypass pulse current signal and ultrasonic acoustoelectric signal simultaneously, be coupled into the first charge amplifier through ultrasonic acoustoelectric sensor, the first charge amplifier produces the superposed signal of bypass pulse current signal and ultrasonic acoustoelectric signal;
Between the reverse input end of the second charge amplifier and in-phase input end, access a fixed capacity, fixed capacity receives bypass pulse current signal, be coupled into the second charge amplifier by this fixed capacity, the second charge amplifier forms pure bypass pulse current signal;
Differential amplifier has the configuration of in-phase input end and reverse input end symmetry, and the reverse input end of differential amplifier is connected with the output terminal of first charge amplifier, receives the superposed signal of bypass pulse current signal and ultrasonic acoustoelectric signal; The positive input of differential amplifier is connected with the output terminal of the second charge amplifier, receives pure bypass pulse current signal; The pure ultrasonic acoustoelectric signal that differential amplifier is directly proportional to the difference of the superposed signal of ultrasonic acoustoelectric signal to the pure bypass pulse current signal of homophase input and the bypass pulse current signal of oppositely input for suppressing bypass pulse current signal output.
A second aspect of the present invention, propose a kind of based on the pick-up unit to gas-insulated gas insulated metal enclosed swit chgear shelf depreciation by pulse current and ultrasound wave, this pick-up unit is made up of ultrasonic acoustoelectric sensor, fixed capacity, the first charge amplifier, the second charge amplifier, differential amplifier, AD converter, digital signal processor, interactive button, pilot lamp and liquid crystal micro graphic alphanumeric display, wherein:
Between the reverse input end of the first charge amplifier and in-phase input end, access ultrasonic acoustoelectric sensor, ultrasonic acoustoelectric sensor receives bypass pulse current signal and ultrasonic acoustoelectric signal simultaneously, be coupled into the first charge amplifier through ultrasonic acoustoelectric sensor, the first charge amplifier produces the superposed signal of bypass pulse current signal and ultrasonic acoustoelectric signal;
Between the reverse input end of the second charge amplifier and in-phase input end, access a fixed capacity, fixed capacity receives bypass pulse current signal, be coupled into the second charge amplifier by this fixed capacity, the second charge amplifier forms pure bypass pulse current signal;
Differential amplifier has the configuration of in-phase input end and reverse input end symmetry, and the reverse input end of differential amplifier is connected with the output terminal of first charge amplifier, receives the superposed signal of bypass pulse current signal and ultrasonic acoustoelectric signal; The positive input of differential amplifier is connected with the output terminal of the second charge amplifier, receives pure bypass pulse current signal; The pure ultrasonic acoustoelectric signal that differential amplifier is directly proportional to the difference of the superposed signal of ultrasonic acoustoelectric signal to the pure bypass pulse current signal of homophase input and the bypass pulse current signal of oppositely input for suppressing bypass pulse current signal output;
The input end of AD converter is connected with the second charge amplifier, differential amplifier output terminal respectively, and digital signal processor is connected with the output terminal of AD converter, the input end of interactive button, the input end of pilot lamp;
Described AD converter, carries out digitizing by the pure bypass pulse current signal of the pure ultrasonic acoustoelectric signal of differential amplifier output and the output of the second charge amplifier;
Described digital signal processor, the pure ultrasonic acoustoelectric signal of digitizing and pure bypass pulse current signal are calculated, obtain and show waveform, product spectrum, amplitude peak and the maximum power frequency of pure ultrasonic acoustoelectric signal and pure bypass pulse current signal, utilize mistiming of the due in of pure ultrasonic acoustoelectric signal and pure bypass pulse current signal to be multiplied by the velocity of sound and obtain the distance between partial discharge position and ultrasonic acoustoelectric sensor placement location, realize the location to gas-insulated gas insulated metal enclosed swit chgear partial discharge position, and show this distance value;
What described interactive button received that user sends changes screen instruction and reset instruction, and pilot lamp is lighted and shown that device works;
Described liquid crystal micro graphic alphanumeric display input end is connected with digital signal processor output terminal, shows the distance between waveform, frequency spectrum, amplitude peak, maximum power frequency and shelf depreciation and the ultrasonic acoustoelectric sensor of pure ultrasonic acoustoelectric signal and pure bypass pulse current signal under DSP CONTROL.
(3) useful technique effect:
The present invention proposes a kind of GIS local discharge detection device based in conjunction with pulse current and ultrasound examination, by separating ultrasonic acoustoelectric signal and the pulsed current signal from ultrasonic acoustoelectric sensor, has improved the signal to noise ratio (S/N ratio) of ultrasonic acoustoelectric signal.Fully utilize the pure bypass pulse current signal and the ultrasonic acoustoelectric signal that obtain, proposed the method for the location of the poor GIS of the realization shelf depreciation of due in of utilizing pure bypass pulse current signal and ultrasonic acoustoelectric signal.Compared with the existing technology that only adopts bypass pulse electric current testing, device of the present invention has increased GIS shelf depreciation positioning function newly; Compared with the existing technology that only adopts supersonic testing method, device of the present invention has improved the signal to noise ratio (S/N ratio) of ultrasonic acoustoelectric signal, can make to only depend on the localization method that ultrasonic signal positions to obtain higher precision; Only use compared with the ultrasonic method positioning with existing, existing method need to access plural ultrasonic acoustoelectric sensor simultaneously, and need complicated computing, the localization method that the present invention proposes only need to access a ultrasonic acoustoelectric sensor, computing is also relatively simple, thereby more simple and practical.
GIS detection circuit for partial discharge is different to the response of bypass pulse current signal and ultrasonic signal, has realized separating from the bypass pulse signal in same ultrasonic acoustoelectric sensor and ultrasonic acoustoelectric signal from hardware.Pure ultrasonic acoustoelectric signal and pure bypass pulse current signal have been obtained simultaneously.
With search absolute value peaked method find out described two corresponding moment of purified signal maximal value, calculate the mistiming of described two purified signals generation by both differences, be multiplied by the velocity of sound with this mistiming and obtain the distance between partial discharge position and ultrasonic acoustoelectric sensor placement location, thereby a kind of simple and effective method that realizes partial discharge position location is provided.
Take above-mentioned testing circuit as basis, with digital signal processor subsequent treatment center, and the miniature graphic alphanumeric display of collocating LCD, interactive button and pilot lamp, form GIS Partial Discharge Detection equipment.The demonstration of the distance between waveform, frequency spectrum, amplitude peak and maximum power frequency and discharge position and the ultrasonic acoustoelectric sensor placement location of this device to above-mentioned two-way purified signal.
Accompanying drawing explanation
Fig. 1 is conventional charge amplifier circuit schematic diagram;
Fig. 2 is that the combination pulse current that proposes of the present invention detects and the testing circuit of the GIS shelf depreciation of ultrasound examination;
Fig. 3 is the pick-up unit theory diagram of the GIS shelf depreciation that proposes of the present invention;
Fig. 4 is the GIS local discharge detection device software flow example of proposition of the present invention
The equivalent capacity of the ultrasonic acoustoelectric sensor of Cs,
A Integrated-Circuit charge amplifier,
A1 Integrated-Circuit charge amplifier reversed-phase output,
A2 Integrated-Circuit charge amplifier inverting input,
A3 Integrated-Circuit charge amplifier homophase phase input end,
Rf charge discharging resisting resistance, Cf integrating capacitor,
1 first charge amplifier, 2 second charge amplifiers, 3 differential amplifiers,
4 ultrasonic acoustoelectric sensors, 5 fixed capacities, 6 high-speed A/D converters,
7 digital signal processors, 8 interactive buttons, 9 pilot lamp,
10 liquid crystal micro graphic alphanumeric displays,
O
1the superposed signal of the-the first charge amplifier output,
O
2the-the second charge amplifier is exported pure bypass pulse current signal,
O
3the pure ultrasonic acoustoelectric signal of-differential amplifier output output,
I
1-from the ultrasonic acoustoelectric signal of ultrasonic acoustoelectric sensor,
I
2-from ultrasonic acoustoelectric sensor earth terminal bypass pulse current signal.
Embodiment
For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in more detail.
First need existing ultrasonic acousto-electric detection circuit to analyze fully, find out the reason that produces noise in available circuit or fail to suppress noise.
Existing ultrasonic acousto-electric detection circuit generally adopts charge amplifier as prime amplifier, the traditional circuit of charge amplifier as shown in Figure 1, Cs is ultrasonic acoustoelectric sensor equivalent capacity, A is Integrated-Circuit charge amplifier, A1 is Integrated-Circuit charge amplifier reversed-phase output, and A2 is Integrated-Circuit charge amplifier inverting input, and A3 is Integrated-Circuit charge amplifier homophase phase input end, Rf is charge discharging resisting resistance, and Cf is integrating capacitor.Wherein, there is special singularity as the capacitor C s of ultrasonic acoustoelectric sensor.On the one hand, in the time that the ultrasound wave of the shelf depreciation generation in GIS is broadcast on this sensor, on Cs the two poles of the earth, produce positive and negative contrary electric charge, this electric charge amplifies by the charge amplifier being made up of integrated amplifier A, integrating capacitor Cf and bleeder resistance Rf, thereby ultrasound wave detected.On the other hand, shelf depreciation in GIS is producing hyperacoustic while, electric discharge itself just means the pulse current existing at the electric discharge position of GIS by the motion generation of ionized gas ion and free electron, this pulse current is released by the loop of GIS formation itself on the one hand, on the other hand by the ground connection position of the GIS outer conductor the earth of releasing.And ultrasonic acoustoelectric sensor for detect ultrasonic must with GIS shell close contact, like this, ultrasonic acoustoelectric sensor receive ultrasonic in, shelf depreciation produce pulse current also near ultrasonic acoustoelectric sensor " bypass " pass through.The electric current that this " bypass " passed through, can be coupled in the amplifying circuit shown in Fig. 1 by the equivalent capacity Cs of ultrasonic acoustoelectric sensor, becomes the noise of the ultrasonic acoustoelectric signal of ultrasound wave generation.In general, bypass pulse current signal is direct electric signal, and it arrives above-mentioned amplifying circuit with light velocity propagation.And ultrasonic acoustoelectric signal was to propagate in the various piece at GIS with the velocity of sound before being converted into electric signal by ultrasonic acoustoelectric sensor, and the velocity of sound is far smaller than the light velocity certainly.Therefore,, as long as have certain distance between the placement location of sensor and partial discharge position, will more first arrive than the forward position of ultrasonic acoustoelectric signal in the forward position of bypass pulse signal.But as long as the duration of shelf depreciation is longer, two kinds of signals are just together overlapped, each signal all becomes the noise of another one signal.Therefore, existing ultrasonic acousto-electric detection circuit is only effective in the situation that disturbing without bypass pulse signal.And under this concrete applied environment of GIS Partial Discharge Detection, GIS shelf depreciation not only produces ultrasound wave, also produce the signals such as pulse by-pass current and ultrahigh frequency electromagnetic wave signal simultaneously, they have all formed severe jamming.At present, the method for rejecting other undesired signals from ultrasonic acoustoelectric signal is mainly the method for multistage active power filtering.But the method for filtering is only effective under the nonoverlapping condition of frequency spectrum of ultrasonic acoustoelectric signal and other undesired signals.But under this concrete applied environment of GIS Partial Discharge Detection, ultrasonic acoustoelectric signal and bypass pulse current signal have more overlapping, and the power of bypass pulse current signal is often also large than the power of ultrasonic acoustoelectric signal, even " flood " ultrasonic acoustoelectric signal.In this situation, filtering method can not thoroughly address the above problem
For solving the problem of prior art, the present invention has provided Fig. 2 and has illustrated that the present invention detects in conjunction with pulse current and the GIS detection circuit for partial discharge of ultrasound examination, this circuit is by the first charge amplifier 1, the second charge amplifier 2, a differential amplifier 3, ultrasonic acoustoelectric sensor 4, fixed capacity 5 forms, wherein: between the reverse input end of the first charge amplifier 1 and in-phase input end, access ultrasonic acoustoelectric sensor 4, ultrasonic acoustoelectric sensor 4 receives bypass pulse current signal and ultrasonic acoustoelectric signal simultaneously, be coupled and enter the first charge amplifier 1 through ultrasonic acoustoelectric sensor 4, the first charge amplifier 1 produces and exports the superposed signal O of bypass pulse current signal and ultrasonic acoustoelectric signal
1, between the reverse input end of the second charge amplifier 2 and in-phase input end, access a fixed capacity 5, fixed capacity receives bypass pulse current signal, be coupled into the second charge amplifier 2, the second charge amplifiers 2 by this fixed capacity and form pure bypass pulse current signal O
2, differential amplifier 3 has the configuration of in-phase input end and reverse input end symmetry, and differential amplifier 3 reverse input ends are connected with the output terminal of first charge amplifier 1, receives the superposed signal O of bypass pulse current signal and ultrasonic acoustoelectric signal
1, the positive input of differential amplifier 3 is connected with the output terminal of the second charge amplifier 2, receives pure bypass pulse current signal O
2, the pure bypass pulse current signal O that differential amplifier 3 is inputted for suppressing bypass pulse current signal output and homophase
2with the bypass pulse current signal of reverse input and the superposed signal O of ultrasonic acoustoelectric signal
1the pure ultrasonic acoustoelectric signal O that is directly proportional of difference
3.
Described the first charge amplifier 1 is by an Integrated-Circuit charge amplifier A, charge discharging resisting resistance R _ f and integrating capacitor Cf composition;
Described the second charge amplifier 2 is by an Integrated-Circuit charge amplifier B, charge discharging resisting resistance R F and integrating capacitor Cf' composition;
Described differential amplifier 3 is made up of an integrated operational amplifier C and resistance R 1, R2, R3 and R4.
Between the reverse input end of first charge amplifier 1 and in-phase input end, access ultrasonic acoustoelectric sensor 4, the static equivalent capacity of this ultrasonic acoustoelectric sensor 4 is Cs; Between the reverse input end of the second charge amplifier 2 and in-phase input end, access a fixed capacity 5, the capacitance Cs' that chooses fixed capacity 5 equates with static equivalent capacity Cs as far as possible.The in-phase input end of described the first charge amplifier 1 and the second charge amplifier 2 altogether.The bypass pulse current signal that described the first charge amplifier 1 is exported and the superposed signal O of ultrasonic acoustoelectric signal
1be fed to the reverse input end of described differential amplifier 3, the pure bypass pulse current signal O of the output of the second charge amplifier 2
2be fed to the in-phase input end of described differential amplifier 3.Described differential amplifier 3 is designed to the subtracter of described in-phase end and backward end symmetry, select resistance R 2/R1=R4/R3, therefore the output signal of described differential amplifier 3 and the bypass pulse current signal of exporting from the first charge amplifier 1 and the superposed signal O of ultrasonic acoustoelectric signal
1the pure bypass pulse current signal O exporting with the second charge amplifier 2
2the pure ultrasonic acoustoelectric signal O that is directly proportional of difference
3,
O
3=A
3d(O
2-O
1) (1)
A in above formula
3dfor the differential mode closed-loop gain of differential amplifier 3, O
3it is the pure ultrasonic acoustoelectric signal that differential amplifier 3 is exported.
Between the reverse input end of first charge amplifier 1 and in-phase input end, be connected to ultrasonic acoustoelectric sensor 4, ultrasonic acoustoelectric sensor 4 can respond the shelf depreciation of GIS and produce ultrasonic acoustoelectric signal I
1.In addition, the shelf depreciation of GIS also can produce bypass pulse current signal I
2, I
2also the earth terminal 12 of the static equivalent capacity Cs by ultrasonic acoustoelectric sensor 4 is coupled in the first charge amplifier 1.According to known circuit theory, the output bypass pulse current signal of the first charge amplifier 1 and the superposed signal of ultrasonic acoustoelectric signal meet following formula:
O
1=A
1dI
1+A
1cI
2 (2)
Wherein, A
1dand A
1crespectively differential mode closed-loop gain and the common mode closed-loop gain of the first charge amplifier 1.From above formula, the bypass pulse current signal of the first charge amplifier output and the superposed signal O of ultrasonic acoustoelectric signal
1ultrasonic acoustoelectric signal I
1with bypass pulse current signal I
2linear superposition.That is to say, the output signal of the first charge amplifier I is ultrasonic acoustoelectric signal I
1with bypass pulse current signal I
2the mixed signal of stack mutually, but not purified signal.
What between the reverse input end of the second charge amplifier 2 and in-phase input end, access is a fixed capacity 5, and therefore the second charge amplifier 2 can be to not resulting from the ultrasonic acoustoelectric signal I of shelf depreciation of GIS
1respond.But, due to the in-phase input end of the first charge amplifier 1 and the second charge amplifier 2 altogether, the therefore bypass pulse current signal I from holding altogether GND bypass to pass through
2also can be coupled in the second charge amplifier 2, and be amplified by the second charge amplifier 2.According to known circuit theory, the pure bypass pulse current signal of the output of the second charge amplifier 2 O
2meet following formula:
O
2=A
2cI
2 (3)
Wherein A
2cit is the common mode closed-loop gain of the second charge amplifier 2.Above formula shows the output signal O of the second charge amplifier 2
2with bypass pulse current signal I
2be directly proportional, but with the ultrasonic acoustoelectric signal I of shelf depreciation that results from GIS
1irrelevant.That is to say, this signal is pure bypass pulse current signal.
Described the first charge amplifier 1 and the second charge amplifier 2 separately Integrated-Circuit charge amplifier chip can be selected any product with similar parameter of TLC2272 chip or TLC2274 chip or other, measure their open loop enlargement factor and input impedance, select the chip with identical open loop enlargement factor and identical input impedance for use.The charge discharging resisting resistance R F ' and the integrating capacitor element Cf' that select described the first charge amplifier 1 and the second charge amplifier 2, make their resistance consistent as far as possible with capacitance, selects charge discharging resisting resistance R F '=Rf, integrating capacitor CF '=Cf.With this understanding, learn the common mode closed-loop gain A of the first charge amplifier 1 according to knowledge
1ccommon mode closed-loop gain A with the second charge amplifier 2
2cequate, that is:
A
1c=A
2c (4)
By formula (2) and formula (3) substitution formula 1, and utilize formula (4), can push over and draw following formula:
O
3=A
3dA
1dI
1 (5)
Above formula shows, the ultrasonic acoustoelectric signal I of the shelf depreciation of the output signal of differential amplifier 3 and generation and GIS
1be directly proportional, and with bypass pulse current signal I
2irrelevant.That is to say, by foregoing circuit, finally obtained pure ultrasonic acoustoelectric signal O at the output terminal of differential amplifier 3
3.
Described ultrasonic acoustoelectric sensor 4 can select based on piezoelectric ceramics and based on two kinds of flexible piezoelectric film.Wherein the piezoelectric modulus of piezoelectric ceramics is large, made ultrasonic acoustoelectric sensor 4 highly sensitive.But there is a natural resonance frequency determining for its geomery in piezoelectric ceramics, means that the response of this sensor is only sensitive near this frequency, has very narrow response passband.The less restriction that is subject to its shape and size of frequency response of flexible piezoelectric film, therefore its frequency response passband is very wide, all has roughly the same response between 50Hz-300kHz.But the piezoelectric modulus of piezoelectric film material is than the little order of magnitude of piezoceramic material, the sensitivity of made ultrasonic acoustoelectric sensor is also lower.And the ultrasonic frequency of GIS shelf depreciation, because of its electric discharge diversity of reason and the complicacy of discharge mechanism, has very wide bandwidth, the highlyest may reach 100kHz.As an embodiment, originally select the ultrasonic acoustoelectric sensor based on piezoelectric membrane.
As an embodiment, can in existing GIS Partial Discharge Detection equipment based on ultrasonic method or device, adopt and be realized GIS detection circuit for partial discharge by step 1-step 6, thereby improve the signal ratio of the ultrasonic acoustoelectric signal obtaining, thereby the technical merit of upgrading existing equipment, improves the positioning precision of these equipment.
The present invention further proposes a kind of GIS local discharge detection device based on above-mentioned testing circuit, and Fig. 3 shows the GIS local discharge detection device theory diagram that the present invention proposes; This pick-up unit is made up of testing circuit, AD converter 6, digital signal processor 7, interactive button 8, pilot lamp 9 and liquid crystal micro graphic alphanumeric display 10, wherein testing circuit is that Fig. 2 illustrates the power detection circuit that gas-insulated gas insulated metal enclosed swit chgear part is put, and this testing circuit comprises the first charge amplifier 1, the second charge amplifier 2, differential amplifier 3, ultrasonic acoustoelectric sensor 4, fixed capacity 5; AD converter 6 adopts high-speed A/D converter, between the reverse input end of the first charge amplifier 1 and in-phase input end, access ultrasonic acoustoelectric sensor 4, ultrasonic acoustoelectric sensor 4 receives bypass pulse current signal and ultrasonic acoustoelectric signal simultaneously, be coupled into the first charge amplifier 1, the first charge amplifier 1 and produce the superposed signal O of bypass pulse current signal and ultrasonic acoustoelectric signal through ultrasonic acoustoelectric sensor 4
1; Between the reverse input end of the second charge amplifier 2 and in-phase input end, access a fixed capacity 5, fixed capacity 5 receives bypass pulse current signal, be coupled into the second charge amplifier 2, the second charge amplifiers 2 by this fixed capacity 5 and form pure bypass pulse current signal O
2; Differential amplifier 3 has the configuration of in-phase input end and reverse input end symmetry, and the reverse input end of differential amplifier 3 is connected with the output terminal of first charge amplifier 1, receives the superposed signal O of bypass pulse current signal and ultrasonic acoustoelectric signal
1; The positive input of differential amplifier 4 is connected with the output terminal of the second charge amplifier 2, receives pure bypass pulse current signal O
2; The pure bypass pulse current signal O that differential amplifier 3 is inputted for suppressing bypass pulse current signal output and homophase
2with the bypass pulse current signal of reverse input and the superposed signal O of ultrasonic acoustoelectric signal
1the pure ultrasonic acoustoelectric signal that is directly proportional of difference; The input end of AD converter 6 is connected with the second charge amplifier 2, differential amplifier 3 output terminals respectively, and 7 of digital signal processors are connected with the output terminal of AD converter 6, the input end of interactive button 8, the input end of pilot lamp 9; Described AD converter 6, the pure ultrasonic acoustoelectric signal O that differential amplifier 3 is exported
3pure bypass pulse current signal O with the second charge amplifier output
2carry out digitizing; Described digital signal processor 7, the pure ultrasonic acoustoelectric signal of digitizing and pure bypass pulse current signal are calculated, obtain and show waveform, product spectrum, amplitude peak and the maximum power frequency of pure ultrasonic acoustoelectric signal and pure bypass pulse current signal, utilize mistiming of the due in of pure ultrasonic acoustoelectric signal and pure bypass pulse current signal to be multiplied by the velocity of sound and obtain the distance between partial discharge position and ultrasonic acoustoelectric sensor placement location, realize the location to gas-insulated gas insulated metal enclosed swit chgear partial discharge position, and show this distance value; What described interactive button 8 received that user sends changes screen instruction and reset instruction, and pilot lamp 9 is lighted and shown that device works; Described liquid crystal micro graphic alphanumeric display 10 input ends are connected with digital signal processor 7 output terminals, under digital signal processor 7 is controlled, show pure ultrasonic acoustoelectric signal O
3with pure bypass pulse current signal O
2waveform, frequency spectrum, amplitude peak, maximum power frequency and shelf depreciation and ultrasonic acoustoelectric sensor 4 between distance.
The capacitance of described fixed capacity 5 equates with the static equivalent capacity of ultrasonic acoustoelectric sensor 4.Form Integrated-Circuit charge amplifier A by described the first charge amplifier 1 and the second charge amplifier 2, the first charge amplifier 1 is identical with open loop enlargement factor, the input impedance of the second charge amplifier 2; Described the first charge amplifier 1 and the second charge amplifier 2 form charge discharging resisting resistance R _ f and integrating capacitor Cf, the charge discharging resisting resistance Rf of described the first charge amplifier 1 and the second charge amplifier 2 is identical, the capacitance Cf of the integrating capacitor of described the first charge amplifier 1 and the second charge amplifier 2 is identical.Digital signal processor 7 utilizes the pure ultrasonic acoustoelectric signal O of peaked method search of search absolute value
3with pure bypass pulse current signal O
2the maximal value of absolute value, finds out pure ultrasonic acoustoelectric signal O
3with pure bypass pulse current signal O
2the corresponding moment of maximal value, with pure ultrasonic acoustoelectric signal O
3with pure bypass pulse current signal O
2difference calculate pure ultrasonic acoustoelectric signal and pure bypass pulse current signal O
1the mistiming occurring.
The theory diagram of this GIS local discharge detection device.This device with testing circuit as shown in Figure 2 proposed by the invention so that pure ultrasonic acoustoelectric signal O to be provided
3with pure bypass pulse current signal O
2, they are fed to any a digital signal processor with high-speed A/D converter in sheet and carry out AD conversion by high-speed A/D converter in its sheet.As an embodiment, digital signal processor of the present invention adopts the interior high-speed A/D converter of the sheet of TMS320F28335 to realize this function.Adopt independently high-speed A/D converter chip to realize this function and also belong to content of the present invention.
The function of obtained data being calculated, being analyzed and judge as an embodiment also adopts TMS320F28335 to realize.
The central processing unit maximum clock frequency of TMS320F28335 chip can reach 150MHz, and minimum clock cycle is 6.67ns; Have high-speed A/D converter in 16 tunnel 12 bit slices, can carry out high-speed sampling to the voltage signal between 0V-3V, be 80ns the switching time of described high-speed A/D converter; Have ram in slice 34k, flash memory (FLASH) 256k in sheet; Operating voltage is 3.3V, and core operational voltage is 1.8V.This is a digital signal processor take low-power consumption as target design, has guaranteed that the GIS local discharge detection device of developing can work under powered battery condition.In addition, to have nearly 64 terminal pins can be general purpose I/O port by software definition to this digital signal processor." interactive button and the pilot lamp " of the present invention using some terminal pins in this digital signal processor as Fig. 3 F input or output lead-in wire, the data output of the miniature graphic alphanumeric display 10 of liquid crystal (LCD) using other terminal pins in Fig. 3 or show control line.In general, each interactive button 8 needs an input port, and each pilot lamp 9 needs a delivery outlet, and the display of serial input needs 4-6 delivery outlet, and the display of parallel input needs 8-12 delivery outlet.As an embodiment, the present invention introduces 2 interactive buttons 8, respectively called after " reboot button " and " changing screen button ".Also introduce in addition the display of 9, one serial inputs of two pilot lamp, required general purpose I/O port number is 8, uses so 64 general purpose I/O port resources of digital signal processor 7 are enough to meet.
The miniature graphic alphanumeric display 10 of LCD in Fig. 3 can be the miniscope product of market any style that can provide.Because the terminal pin resource that may be defined as general purpose I/O port of digital signal processor 7 is enough, and can more easily redefine with software, therefore the present embodiment can adapt to all miniature LCD display styles on market.
Interactive button 8 in Fig. 3 can be selected the touch-switch of any style that market can provide, as long as its reliable in quality, good looking appearance, size meet installation requirement, there is no special requirement.
The testing circuit as shown in Figure 2 that has adopted the present invention to propose adopts the digital signal processor 7 of other styles or adopts the scheme of FPGA in conjunction with independent high-speed A/D converter 6, as long as just should be considered as content of the present invention.
Take theory diagram shown in Fig. 3 as detection and location that basic GIS local discharge detection device can be realized GIS shelf depreciation.With search absolute value peaked method find out the pulse current purified signal O that shown in Fig. 2, circuit provides
2with ultrasonic acoustic-electric purified signal O
3the corresponding moment of maximal value, calculate the mistiming of described two purified signals generation by both differences, be multiplied by the velocity of sound with this mistiming and obtain the distance between partial discharge position and ultrasonic acoustoelectric sensor 4 placement locations, thus the location of realizing partial discharge position.Computing formula is as follows:
D=V△T
Wherein D is that partial discharge position arrives the distance between ultrasonic acoustoelectric sensor 4 installation sites, and V is ultrasonic velocity, and △ T is the above-mentioned mistiming.The transmission speed of ultrasound wave in the SF6 of GIS inside gas is only 150m/s, and velocity of propagation in GIS shell (material is generally aluminium) is 4000m/s.Therefore, the result of above-mentioned location only has relative meaning.In the present invention, calculate respectively two distances with above-mentioned two kinds of velocities of sound respectively, all export to display and show, offer user with reference to use.
Obviously, above-mentioned localization method is an embodiment, to any improvement of this method, as long as having used the mistiming of pulsed current signal and ultrasonic acoustoelectric signal, just belongs to scope of the present invention.
The GIS Partial discharge detector realizing on Fig. 3 theory diagram basis also need to work under the support at software.As an embodiment, Fig. 4 has illustrated out GIS local discharge detection device software flow pattern of the present invention.Illustrate that in conjunction with Fig. 4 running software step is as follows now:
Step S1: system initialization, comprise the interior high-speed A/D converter initialization of definition, timer and sheet of general purpose I/O port, start timer and interrupt, arrange by timer IE AD converter.Read pure bypass pulse current signal O
2with pure ultrasonic acoustoelectric signal O
3sampled data, deposits pure bypass pulse current signal sampled data variable O in
2old and pure ultrasonic acoustoelectric signal sampled data variable O
3old.Represent not yet to grab GIS local discharge signal with Boolean variable Grasped=0, be set to 0, enter following major cycle.
Step S2: enter after major cycle, first detect whether Boolean variable Grasped (illustrated, belong to a variable in the software in the present invention, its type is Boolean variable) is zero in to the narration of step S1.If zero, enter step S3, Boolean variable Grasped is non-vanishing, enters step S6.
Step S3: check whether " reboot button " is pressed, if " reboot button " is pressed, reruns step S1, if " reboot button " is not pressed, enters step S4.
Step S4: read pure bypass pulse current signal O
2with pure ultrasonic acoustoelectric signal O
3sampled data, deposits the new sampled data O of pure bypass pulse current signal in
2new and the new sampled data O of pure ultrasonic acoustoelectric signal
3new.Check criterion | O
2new-O
2whether old| is less than 100, if | O
2new-O
2old| is less than 100 operating procedure S2, if | O
2new-O
2old| is more than or equal to 100, enters step S5.
Step S5: Boolean variable Grasped is set to 1, represents to have grabbed GIS local discharge signal.It is the number that after this needs the sampled data of preserving that maximum hits Nmax is set, such as being set to 128, and hits q=1, execution step S2.Obviously, the concrete numerical value of Nmax is not restriction of the present invention.
Step S6: read pure bypass pulse current signal O
2with pure ultrasonic acoustoelectric signal O
3sampled data, deposits sampled data in array O
2array and O
3array.The maximum hits Nmax of the hits q having completed and setting is compared simultaneously, be less than setting maximum hits Nmax, repeating step S6 if completed hits q.Be more than or equal to the maximum hits Nmax of setting if completed hits q, enter step S7.
Step S7: establish i=1, large-size screen monitors are counted imax=constant, show pure bypass pulse current signal O
2waveform, i=i+1.Imax is the large-size screen monitors number that wish shows, represents with constant.
Step S8: whether detect " changing screen button " and be pressed, if " changing screen button " is pressed, operating procedure S9, if " changing screen button " is not pressed, reruns step S8.
Step S9: calculate and show next screen content.Such as, and then pure bypass pulse current signal O
2the demonstration of waveform, can calculate and show pure bypass pulse current signal O
2frequency spectrum, then next screen content can be pure bypass pulse current signal O
2amplitude and frequency.Can be by ultrasonic acoustoelectric signal O
3waveform, ultrasonic acoustoelectric signal O
3frequency spectrum and ultrasonic acoustoelectric signal O
3amplitude and allocation be after this 4th, 5 and 6 screen displaying contents, can also using the distance B of the GIS partial discharge position being calculated by above-mentioned Concrete facts step S9 and sensor as the 7th shield displaying contents.Iff showing this 7 screen, large-size screen monitors are counted imax and are equaled 7.Obviously, concrete display screen number is not restriction of the present invention.The screen that shown of judgement is counted i and whether is less than set large-size screen monitors and counts imax.If the screen having shown is counted i and is less than set large-size screen monitors and counts imax, return to step S8, be greater than set large-size screen monitors and count imax, operating procedure S10 if the screen having shown is counted i.
Step S10: Boolean variable Grasped is set to 0, rotates back into step S2 and reruns, to detect GIS shelf depreciation next time.
According to the system principle diagram of GIS local discharge detection device shown in the detection circuit for partial discharge of GIS shown in Fig. 2 and Fig. 3, utilize the corresponding printed circuit board (PCB) of known technology manufacture, utilize known technology DSP chip etc. to be welded to the relevant position of described printed circuit board (PCB), realize the manufacture of the corresponding hardware circuit of GIS local discharge detection device.
According to software flow shown in principle described in step S9 and Fig. 4, write corresponding software with known technology, and move and be verified on the circuit board producing in above-mentioned steps, subsequently by program code burning in the sheet of digital signal processor 6 in flash memory.
The above-mentioned circuit board with software is installed in appropriate device cabinet, and on cabinet panel the interactive button 8 shown in appropriate location installation diagram 3 and the miniature graphic alphanumeric display 10 of liquid crystal, obtain GIS local discharge detection device finished product to this.
The above; be only the embodiment in the present invention, but protection scope of the present invention is not limited to this, any people who is familiar with this technology is in the disclosed technical scope of the present invention; conversion or the replacement that can understand and expect, all should be encompassed in of the present invention comprise scope within.
Claims (8)
1. the testing circuit to gas-insulated gas insulated metal enclosed swit chgear shelf depreciation, it is characterized in that, this gas-insulated gas insulated metal enclosed swit chgear detection circuit for partial discharge is made up of the first charge amplifier, the second charge amplifier, differential amplifier, ultrasonic acoustoelectric sensor and a fixed capacity, wherein:
Between the reverse input end of the first charge amplifier and in-phase input end, access ultrasonic acoustoelectric sensor, ultrasonic acoustoelectric sensor receives bypass pulse current signal and ultrasonic acoustoelectric signal simultaneously, be coupled into the first charge amplifier through ultrasonic acoustoelectric sensor, the first charge amplifier produces the superposed signal of bypass pulse current signal and ultrasonic acoustoelectric signal;
Between the reverse input end of the second charge amplifier and in-phase input end, access a fixed capacity, fixed capacity receives bypass pulse current signal, be coupled into the second charge amplifier by this fixed capacity, the second charge amplifier forms pure bypass pulse current signal;
Differential amplifier has the configuration of in-phase input end and reverse input end symmetry, and the reverse input end of differential amplifier is connected with the output terminal of first charge amplifier, receives the superposed signal of bypass pulse current signal and ultrasonic acoustoelectric signal; The positive input of differential amplifier is connected with the output terminal of the second charge amplifier, receives pure bypass pulse current signal; The pure ultrasonic acoustoelectric signal that differential amplifier is directly proportional to the difference of the superposed signal of ultrasonic acoustoelectric signal to the pure bypass pulse current signal of homophase input and the bypass pulse current signal of oppositely input for suppressing bypass pulse current signal output.
2. the testing circuit to gas-insulated gas insulated metal enclosed swit chgear shelf depreciation as claimed in claim 1, is characterized in that, the capacitance of described fixed capacity equates with the static equivalent capacity of ultrasonic acoustoelectric sensor.
3. the testing circuit to gas-insulated gas insulated metal enclosed swit chgear shelf depreciation as claimed in claim 1, it is characterized in that, form Integrated-Circuit charge amplifier by described the first charge amplifier and the second charge amplifier, open loop enlargement factor, the input impedance of the first charge amplifier and the second charge amplifier are identical; Described the first charge amplifier and the second charge amplifier composition charge discharging resisting resistance and integrating capacitor, the charge discharging resisting resistance of described the first charge amplifier and the second charge amplifier is identical, and described the first charge amplifier is identical with the capacitance of the integrating capacitor of the second charge amplifier.
4. the pick-up unit to gas-insulated gas insulated metal enclosed swit chgear shelf depreciation as claimed in claim 1, it is characterized in that, the peaked method pure ultrasonic acoustoelectric signal of search of digital signal processor by using search absolute value and the maximal value of pure bypass pulse current signal absolute value, find out pure ultrasonic acoustoelectric signal and corresponding moment of pure bypass pulse current signal maximal value, calculate the mistiming of pure ultrasonic acoustoelectric signal and the generation of pure bypass pulse current signal by the difference of pure ultrasonic acoustoelectric signal and pure bypass pulse current signal.
5. the pick-up unit to gas-insulated gas insulated metal enclosed swit chgear shelf depreciation, it is characterized in that, this pick-up unit is made up of ultrasonic acoustoelectric sensor, fixed capacity, the first charge amplifier, the second charge amplifier, differential amplifier, AD converter, digital signal processor, interactive button, pilot lamp and liquid crystal micro graphic alphanumeric display, wherein:
Between the reverse input end of the first charge amplifier and in-phase input end, access ultrasonic acoustoelectric sensor, ultrasonic acoustoelectric sensor receives bypass pulse current signal and ultrasonic acoustoelectric signal simultaneously, be coupled into the first charge amplifier through ultrasonic acoustoelectric sensor, the first charge amplifier produces the superposed signal of bypass pulse current signal and ultrasonic acoustoelectric signal;
Between the reverse input end of the second charge amplifier and in-phase input end, access a fixed capacity, fixed capacity receives bypass pulse current signal, be coupled into the second charge amplifier by this fixed capacity, the second charge amplifier forms pure bypass pulse current signal;
Differential amplifier has the configuration of in-phase input end and reverse input end symmetry, and the reverse input end of differential amplifier is connected with the output terminal of first charge amplifier, receives the superposed signal of bypass pulse current signal and ultrasonic acoustoelectric signal; The positive input of differential amplifier is connected with the output terminal of the second charge amplifier, receives pure bypass pulse current signal; The pure ultrasonic acoustoelectric signal that differential amplifier is directly proportional to the difference of the superposed signal of ultrasonic acoustoelectric signal to the pure bypass pulse current signal of homophase input and the bypass pulse current signal of oppositely input for suppressing bypass pulse current signal output;
The input end of AD converter is connected with the second charge amplifier, differential amplifier output terminal respectively, and digital signal processor is connected with the output terminal of AD converter, the input end of interactive button, the input end of pilot lamp;
Described AD converter, carries out digitizing by the pure bypass pulse current signal of the pure ultrasonic acoustoelectric signal of differential amplifier output and the output of the second charge amplifier;
Described digital signal processor, the pure ultrasonic acoustoelectric signal of digitizing and pure bypass pulse current signal are calculated, obtain and show waveform, product spectrum, amplitude peak and the maximum power frequency of pure ultrasonic acoustoelectric signal and pure bypass pulse current signal, utilize mistiming of the due in of pure ultrasonic acoustoelectric signal and pure bypass pulse current signal to be multiplied by the velocity of sound and obtain the distance between partial discharge position and ultrasonic acoustoelectric sensor placement location, realize the location to gas-insulated gas insulated metal enclosed swit chgear partial discharge position, and show this distance value;
What described interactive button received that user sends changes screen instruction and reset instruction, and pilot lamp is lighted and shown that device works;
Described liquid crystal micro graphic alphanumeric display input end is connected with digital signal processor output terminal, shows the distance between waveform, frequency spectrum, amplitude peak, maximum power frequency and shelf depreciation and the ultrasonic acoustoelectric sensor of pure ultrasonic acoustoelectric signal and pure bypass pulse current signal under DSP CONTROL.
6. the pick-up unit to gas-insulated gas insulated metal enclosed swit chgear shelf depreciation as claimed in claim 5, it is characterized in that, the peaked method pure ultrasonic acoustoelectric signal of search of digital signal processor by using search absolute value and the maximal value of pure bypass pulse current signal absolute value, find out pure ultrasonic acoustoelectric signal and corresponding moment of pure bypass pulse current signal maximal value, calculate by the difference of pure ultrasonic acoustoelectric signal and pure bypass pulse current signal that pure ultrasonic acoustoelectric signal and pure bypass pulse current signal occur mistiming.
7. the pick-up unit to gas-insulated gas insulated metal enclosed swit chgear shelf depreciation as claimed in claim 5, is characterized in that, the capacitance of described fixed capacity equates with the static equivalent capacity of ultrasonic acoustoelectric sensor.
8. the pick-up unit to gas-insulated gas insulated metal enclosed swit chgear shelf depreciation as claimed in claim 5, it is characterized in that, form Integrated-Circuit charge amplifier by described the first charge amplifier and the second charge amplifier, open loop enlargement factor, the input impedance of the first charge amplifier and the second charge amplifier are identical, form charge discharging resisting resistance and integrating capacitor by described the first charge amplifier and the second charge amplifier, described the first charge amplifier is identical with the resistance of the second charge amplifier, and described the first charge amplifier is identical with the second charge amplifier capacitance.
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