CN103389446B - Electrical positioning method for partial discharge of power transformer - Google Patents

Abstract

The invention relates to an electrical positioning method for partial discharge of a power transformer. A sensor is used for acquiring impulse currents generated by partial discharge of a transformer winding and treating the acquired impulse currents generated by the partial discharge of the transformer winding, so that related information of the impulse currents is obtained, and the position of a discharge source of the transformer winding is located. Five steps including a signal sampling step, a filter amplification step, an analog-digital conversion step, a digital filtering step and a signal identification and digital data processing step are adopted. Data processing is performed on a pulse signal of the partial discharge inside the transformer which is subjected to digital filtering and interference signal rejecting; and mathematical derivation and arithmetical operation are performed through a computer with a mathematical formula. The electrical positioning method has the advantages that the conception is novel, the method is reasonable and convenient to implement, the position of the discharge source in the transformer is found accurately, and practical problems can be solved.

Description

Partial Discharge in Power Transformer electrical Location method

Technical field

The invention belongs to impulse current measurement method, particularly relate to Partial Discharge in Power Transformer electrical Location method.

Background technology

One of criterion of electric power transformer insulated state is its partial discharge quantity.If discharge capacity exceedes state specified standards, will search electric discharge position, and determine position, fix a breakdown a little.

The insulation system of power transformer is complicated, its self rely on the papery insulation system of the various shapes be immersed in power transformer tank and cross-over block to ensure the safe operation of power transformer self, and some small air-gap in these insulation systems, impurity are under the voltage effect of long-time running, all may produce shelf depreciation.This shelf depreciation can cause a hidden trouble to the safe operation of power transformer, but due to its discharge position hidden, therefore search more difficult.According to the knowledge of the applicant, superfrequency method comparatively popular at present, supercritical ultrasonics technology is all difficult to the position accurately finding point of discharge.

(application number: 201110055118.6) comprising: gather the partial discharge pulse's signal in the single power frequency period of transformer, extracts pulse number to Chinese patent literature CN102207532A disclosed " paper oil insulation early discharge defect diagnostic method "; The PHASE DISTRIBUTION of transformer discharge pulse is added up, obtains the PHASE DISTRIBUTION scope of pulse; Detect acetylene content in transformer oil; Utilize the paper oil insulation early discharge defect criteria for classifying, judge whether the paper oil insulation electric discharge in transformer is in commitment.This invention achieves by characteristic parameters such as the frequency of discharge pulse, phase place and oil dissolved gas content, identifies the early stage shelf depreciation defect of inside transformer, for Transformer State Assessment and maintenance provide support.But applicant finds under study for action, though this PHASE DISTRIBUTION to transformer discharge pulse carries out statistical have certain help to searching out spark location, there is certain limitation.Applicant thinks: disclosed " paper oil insulation early discharge the defect diagnostic method " (number of patent application: 201110055118.6) have following weak point: one of Chinese patent literature CN102207532A, as everyone knows, partial discharge of transformer pulse is extremely similar to other discharge-type interference waveforms, and " paper oil insulation early discharge defect diagnostic method " does not have explanation how transformer partial discharge signal and undesired signal to be made a distinction, therefore this invention is in order to " to achieve the frequency by discharge pulse, the characteristic parameters such as phase place and oil dissolved gas content, identify the early stage shelf depreciation defect of inside transformer " method be not accurate enough, because " frequency of discharge pulse " can only add up all pulse signals, can not ensure that these pulses are that inside transformer produces entirely, it also contains various electric discharge undesired signal, thus, erroneous judgement may be caused.Its two, " paper oil insulation early discharge defect diagnostic method " (number of patent application: 201110055118.6) it can only determine that inside transformer has had electric discharge to occur, but accurately cannot make the discharge source position of transformer.

Summary of the invention

The object of the invention is, for the deficiency that above-mentioned prior art exists, improve, propose and study a kind of Partial Discharge in Power Transformer electrical Location method.The present invention can distinguish partial discharge pulse's signal and the undesired signal of inside transformer exactly from sampled signal, directly and accurately can make the shelf depreciation source position of power transformer after rejecting undesired signal.It both when power transformer test, also can carry out partial discharge position and determine in power transformer runs.The current impulse that the present invention produces when being and using Transformer Winding generation shelf depreciation, utilizes the propagation law of this current impulse in winding to determine the position of discharge source.

Technical solution of the present invention is, sensor is adopted to obtain the pulse current of Transformer Winding shelf depreciation generation, the pulse current that the Transformer Winding shelf depreciation obtained produces is processed, obtain the relevant information of pulse current, determine the position of the discharge source of Transformer Winding, it is characterized in that, the position of the relevant information obtaining pulse current and the discharge source determining Transformer Winding have employed and includes signal sampling step, filter and amplification step, analog to digital conversion step, digital filtering step, the five steps of signal discriminating and Digital data processing step, wherein:

One, signal sampling step: adopt High Frequency Current Sensor, the pulse current of the head end of each winding of measuring transformer and the shelf depreciation generation of end respectively;

Two, filter and amplification step: the pulse current of the head end and the generation of end shelf depreciation of signal sampling step being measured to each winding of transformer obtained carries out filtering, amplification;

Three, analog to digital conversion step: analog to digital conversion is carried out to the pulse current that the head end of each winding of transformer after filtering, amplification and the shelf depreciation of end produce, obtains head end current digital amount and the end current digital quantity of each winding of transformer;

Four, digital filtering step: digital filtering is carried out to the head end current digital amount of each winding of described transformer and end current digital quantity;

Five, signal is differentiated and data processing step: carry out signal discriminating to the head end current digital amount of each winding of described transformer through digital filtering and end current digital quantity, distinguish partial discharge pulse's signal and the undesired signal of inside transformer, after rejecting undesired signal, again data processing is carried out to partial discharge pulse's signal of the inside transformer distinguished, by flow chart of data processing, find the accurate location of the Partial Discharge Sources of transformer.

It is characterized in that, signal is differentiated and in data processing step, carry out data processing and used mathematical formulae, the mode of being carried out mathematical derivation and mathematical operation by computing machine carries out data processing.

It is characterized in that, signal is differentiated and in data processing step, the mathematical formulae carrying out data processing utilization comprises the formula of following derivation:

$\frac{I_L}{I_N}=\frac{(e^{\mathrm{\αx}}+e^{-\mathrm{\αx}})P/2+(e^{\mathrm{\αx}}+e^{-\mathrm{\αx}})/2}{[e^{\mathrm{\α}(1-x)}+e^{-\mathrm{\α}(1-x)}]Q/2+[e^{\mathrm{\α}(1-x)}-e^{-\mathrm{\α}(1-x)}]/2}\·\·\·\left(1\right)$

$\mathrm{\α}=\sqrt{\frac{C}{k}}\·\·\·\left(2\right)$

$P=\frac{I_{L1}{I}_{L0}\mathrm{sh\αch\α}+I_{N1}{I}_{N0}\mathrm{sh\α}}{I_{L1}{I}_{N0}-I_{N1}{I}_{N0}{\mathrm{ch}}^2\mathrm{\α}}\·\·\·\left(3\right)$

$Q=\frac{I_{L0}{I}_{N1}\mathrm{sh\αch\α}+I_{N1}{I}_{N0}\mathrm{sh\α}}{I_{L1}{I}_{N0}-I_{L0}{I}_{N1}{\mathrm{ch}}^2\mathrm{\α}}\·\·\·\left(4\right)$

In formula: X is the electrical distance of discharge source distance neutral point;

I _lthe signal that-transformer head end sensor obtains;

I _nthe signal that-transformer tip sensor obtains;

α, I _l1, I _n1, I _l0, I _n0parameter is tried to achieve by experiment, and

$\mathrm{\α}=\mathrm{ar}\cosh \left(\frac{V_1}{V_2}\right)$

I _l1-when the calibration pulse local discharge signal that transformer head end sensor obtains when winding head end injects;

I _n1-when the calibration pulse local discharge signal that transformer tip sensor obtains when winding head injects;

I _l0the local discharge signal of-transformer head end sensor the acquisition when property point injects in the windings in calibration pulse;

I _n0the local discharge signal of-transformer tip sensor the acquisition when property point injects in the windings in calibration pulse.

It is characterized in that, α, I _l1, I _n1, I _l0, I _n0the method that parameter is tried to achieve by experiment is: produce with signal generator the high-pressure side that high-frequency signal adds to transformer, record the voltage V1 of high-pressure side, the voltage V2 of neutral point, by formula with oscillograph

$\mathrm{\α}=\mathrm{ar}\cosh \left(\frac{V_1}{V_2}\right)$

By calculating, obtain α value;

I is obtained by parameter calibrating method _l1, I _n1, I _l0, I _n0parameter, adopt calibrating device, make transformer neutral point ground connection, at transformer head end and end access sensor, the calibrating signal provided by calibrating device is injected through the head end of standard capacitance at transformer, the signal obtained through sensor, through the shelf depreciation positioning system process of amplifilter and transformer, obtains the head end of transformer and the local discharge signal of end and parameter I _l1, I _n1; The sensor of the calibrating signal that calibrating device is provided directly through being connected on transformer neutral point and transformer end enters ground, obtains parameter I _l0, I _n0.

It is characterized in that, signal is differentiated and in data processing step, carries out signal differentiate to have employed partial discharge of transformer " pulse effectively to " criterion to the head end current digital amount of each winding of described transformer through digital filtering and end current digital quantity.

It is characterized in that, partial discharge of transformer " pulse effectively to " criterion is: digital filtering inside transformer partial discharge pulse signal out must be that both have identical pulse number at high-pressure side and neutral point, waveform similarity, their first peak values occur in same time or within the μ S of time difference ± 0.8.

It is characterized in that, the mathematical formulae of utilization adopts special software for calculation to provide.

It is characterized in that, special software for calculation be the special parameter of the relation of the pulse current that the head end finding out spark location and Transformer Winding, the end that obtain in test are passed through and application regularity thereof be compiled into for computer recognizing and application software system, application regularity comprises rule and formula.

Principle of work of the present invention is: according to the characteristic of transformer under the effect of different frequency voltage, considers the actual influence of transformer.Because the equivalent circuit of transformer under power-frequency voltage effect, the inductance of usual available coil and resistance replace, and can disregard electric capacity.And when high frequency or Impulse Voltage, then must consider the impact of electric capacity in transformer between winding and winding-to-earth capacity.Along with the frequency of operation of transformer improves further, then iron core, iron-clad can produce iron magnetic action (as Ji Skin effect, eddy current) inductance that produces and resistance, also need to take into account.For the equivalent circuit of general transformer, the inductance of transformer inner high voltage winding and electric capacity and turn-to-turn capacitance, layer capacitance and ground capacitance need only be considered, ignore the impact of the mutual inductance effect of low pressure winding in transformer, iron magnetic action and winding resistance.

Applicant is found by research: can find a frequency band by experiment, within the scope of this frequency band, the impedance of the impedance ratio capacitive branch of inductive branch is much bigger, and thus the impact of inductive branch can not be considered.And the frequency of this frequency range found by experiment is not again special height, and the inductance caused by the iron magnetic action of iron core, iron-clad and resistance also do not occur, now the equivalent circuit of Transformer Winding can regard pure capacitive recurrent circuit approx as.This pure capacitive recurrent circuit, belongs to linear circuit, and when pulse current passes through, waveform can not change, and also can not produce vibration, that is (in other words) is the same at the waveform that any position detects, just amplitude is different.That is the pulse waveform that (in other words) arrives in the head end of Transformer Winding, end point detection, the time that their first peak value occurs is identical.

But it should be noted that the mathematic(al) representation describing pure capacitive recurrent circuit is complicated hyperbolic function.For this reason, applicant is on the basis conducted in-depth research, the signal at the position finding discharge source to occur and Transformer Winding two ends has the test figure of correlativity to carry out analyzing and inquiring into, think can find out the head end of point of discharge (namely above-mentioned discharge source occurs) position and Transformer Winding by the regularity using relevant mathematical formulae to carry out mathematical derivation to find out wherein, the relation of pulse current that end passes through.In addition, applicant considers from the prerequisite facilitating the present invention to apply, find out the head end of spark location and Transformer Winding by obtaining in test, the special parameter of the relation of pulse current that end passes through and application regularity thereof be compiled into for computer recognizing and application software system, application regularity comprises rule and formula.As long as carried out following calibration test carry out the position location test of discharge source at transformer before, to obtain in software required special parameter and by computer input in software systems, just can use the mathematical formulae that software systems provide, calculated by mathematical formulae, determine the position of the discharge source in transformer.Applicant establishment for computer recognizing and software systems can as special software systems.When transformer positions test, as long as get the head end signal (I of transformer at transformer first, last two ends _l) and the distal tip signal (I of transformer _n), use computing machine, the special software systems of request for utilization people establishment, just can easily according to the mathematical formulae provided by special software systems, carry out mathematical derivation and mathematical computations, by this calculation process, just can determine the position of the discharge source in transformer.

Innovative point of the present invention is: 1, for determining the position of the discharge source in transformer, the pulse current produced by Transformer Winding shelf depreciation finds out spark location, have employed the mode of calibration test, the relation of the pulse current that the head end of acquisition spark location and Transformer Winding, end pass through; The mode of the calibration test adopted is and existing popular superfrequency method, supercritical ultrasonics technology difference method; 2, signal discriminating is carried out to the head end current digital amount of each winding of described transformer through digital filtering and end current digital quantity, distinguish partial discharge pulse's signal and the undesired signal of inside transformer, and reject undesired signal, define this inside transformer partial discharge pulse signal for " partial discharge of transformer pulse effectively to ".Adopt signal differentiate partial discharge pulse's signal of differentiating transformer inside and undesired signal and reject undesired signal, method rationally, successful; 3, to namely coming from transformer each winding head end current digital amount through the inside transformer partial discharge pulse signal distinguished and end current digital quantity carries out data processing, being to use mathematical formulae, being undertaken by computing machine that mathematical derivation and mathematical operation carry out.Carrying out data processing uses mathematical formulae to realize having practicality and reliability by computing machine; 4, according to obtaining the head end of spark location and Transformer Winding, the special parameter of pulse current that end passes through, utilization mathematical formulae, carries out mathematical derivation and mathematical operation by computing machine, determines the position of the discharge source in transformer.5, find out the head end of spark location and Transformer Winding by obtaining in test, the special parameter of the relation of pulse current that end passes through and application regularity (rule and formula) thereof be compiled into for computer recognizing and application software system, use very convenient.

Advantage of the present invention is, novel, method is reasonable, easy to use, be convenient to implement, the position that application the present invention searches the discharge source in transformer is accurate, can solving practical problems.

Accompanying drawing explanation

Fig. 1, application the present invention are to breakdown location test connection figure in local during transformer neutral point ground connection.

Fig. 2, application the present invention carry out the transformer connection figure that α value is measured.

Fig. 3, apply transformer neutral point ground connection of the present invention, head end injects the schematic diagram of calibrating signal.

The workflow of the shelf depreciation positioning system that Fig. 4, the present invention adopt.

Embodiment

Below, with reference to the accompanying drawings, specific embodiments of the invention are described in detail.

As shown in Figure 1, Figure 2, Figure 3 shows, the present invention adopts High Frequency Current Sensor to obtain the pulse current of Transformer Winding shelf depreciation generation, the pulse current that the Transformer Winding shelf depreciation obtained produces is processed, make the position of discharge source, the concrete steps adopted include signal sampling step, filter and amplification step, analog to digital conversion step, digital filtering step, signal are differentiated and the five steps of Digital data processing step, wherein:

One, signal sampling step: adopt High Frequency Current Sensor, the pulse current of the head end of each winding of measuring transformer and the shelf depreciation generation of end respectively;

Two, filter and amplification step: filtering, amplification are carried out to the pulse current that head end and the end shelf depreciation of each winding of obtained transformer produce;

Three, analog to digital conversion step: analog to digital conversion is carried out to the pulse current that head end and the end shelf depreciation of each winding of transformer after filtering, amplification produce, obtains head end current digital amount and the end current digital quantity of each winding of transformer;

Four, digital filtering step: digital filtering is carried out to the head end current digital amount of each winding of described transformer and end current digital quantity;

Five, signal authentication data treatment step: signal discriminating is carried out to the head end current digital amount of each winding of described transformer through digital filtering and end current digital quantity, distinguish partial discharge pulse's signal and the undesired signal of inside transformer, after rejecting undesired signal, again data processing is carried out to partial discharge pulse's signal of the inside transformer distinguished, by flow chart of data processing, find the accurate location of the Partial Discharge Sources of transformer.

In signal authentication data treatment step, the mathematical formulae of utilization comprises the formula of following derivation:

$\frac{I_L}{I_N}=\frac{(e^{\mathrm{\αx}}+e^{-\mathrm{\αx}})P/2+(e^{\mathrm{\αx}}+e^{-\mathrm{\αx}})/2}{[e^{\mathrm{\α}(1-x)}+e^{-\mathrm{\α}(1-x)}]Q/2+[e^{\mathrm{\α}(1-x)}-e^{-\mathrm{\α}(1-x)}]/2}\·\·\·\left(1\right)$

$\mathrm{\α}=\sqrt{\frac{C}{k}}\·\·\·\left(2\right)$

$P=\frac{I_{L1}{I}_{L0}\mathrm{sh\αch\α}+I_{N1}{I}_{N0}\mathrm{sh\α}}{I_{L1}{I}_{N0}-I_{N1}{I}_{N0}{\mathrm{ch}}^2\mathrm{\α}}\·\·\·\left(3\right)$

$Q=\frac{I_{L0}{I}_{N1}\mathrm{sh\αch\α}+I_{N1}{I}_{N0}\mathrm{sh\α}}{I_{L1}{I}_{N0}-I_{L0}{I}_{N1}{\mathrm{ch}}^2\mathrm{\α}}\·\·\·\left(4\right)$

In formula: X is the electrical distance of discharge source distance neutral point.

I _lthe signal that-transformer head end sensor obtains.

I _nthe signal that-transformer tip sensor obtains.

α, I _l1, I _n1, I _l0, I _n0to try to achieve by experiment etc. parameter.

$\mathrm{\α}=\mathrm{ar}\cosh \left(\frac{V_1}{V_2}\right)$

I _l1-when the calibration pulse local discharge signal that transformer head end sensor obtains when winding head end injects.

I _n1-when the calibration pulse local discharge signal that transformer tip sensor obtains when winding head injects.

I _l0the local discharge signal of-transformer head end sensor the acquisition when property point injects in the windings in calibration pulse.

I _n0the local discharge signal of-transformer tip sensor the acquisition when property point injects in the windings in calibration pulse.

In signal authentication data treatment step, carrying out data processing is use mathematical formulae, and the mode of carrying out mathematical derivation and mathematical operation by computing machine carries out data processing.The mathematical formulae used is provided by special software for calculation.Described special software for calculation be find out the head end of spark location and Transformer Winding by obtaining in test, the special parameter of the relation of pulse current that end passes through and application regularity thereof be compiled into for computer recognizing and application software system, use very convenient like this, be conducive to of the present invention applying.Application regularity comprises rule and formula.

α, I _l1, I _n1, I _l0, I _n0the method that parameter is tried to achieve by experiment is: produce with signal generator the high-pressure side that high-frequency signal adds to transformer, record the voltage V1 of high-pressure side, the voltage V2 of neutral point, by formula with oscillograph

$\mathrm{\α}=\mathrm{ar}\cosh \left(\frac{V_1}{V_2}\right)$

By calculating, obtain α value;

I is obtained by parameter calibrating method _l1, I _n1, I _l0, I _n0parameter, adopt calibrating device, make transformer neutral point ground connection, at transformer head end and end access sensor, the calibrating signal provided by calibrating device is injected through the head end of standard capacitance at transformer, the signal obtained through sensor, through the shelf depreciation positioning system process of amplifilter and transformer, obtains the head end of transformer and the local discharge signal parameter I of end _l1, IN1; The sensor of the calibrating signal that calibrating device is provided directly through being connected on transformer neutral point and transformer end enters ground, obtains parameter I _l0, I _n0.

The present invention needs the operation adopting relevant instrument and carry out being correlated with in concrete enforcement:

One, the instrument adopted: comprise sensor, amplifilter, calibrating device, A/D analog to digital converter, partial discharge of transformer positioning system.

Two, relevant operation: comprise wiring, calibration test, data processing.

The sensor adopted is made up of coil, soft magnetic bodies iron core, and coil is around on iron core, and coil turn 20-100 circle, is positioned in stainless steel casing;

The amplifilter frequency band adopted is 5kHz-2.0MHz.Enlargement factor 40-50.

Calibrating device adopts square wave to export, and amplitude is 10V, and wavefront rising steepness is less than 0.1 μ S, and the cycle is 50Hz.

The sampling rate of A/D analog to digital converter: 20MHz/S, 12bit.

When transformer neutral point ground connection, shelf depreciation location test wiring as shown in Figure 1.The first, last two ends sensor installation 1,2 of transformer (winding).Sensor 1 installation site is through the ground wire of transformer high-voltage bushing 3 end shield to earth point.Sensor 2 installation site is through transformer neutral point 4(and O point) to the ground wire of earth point.The signal that sensor 1 and sensor 2 obtain enters partial discharge of transformer positioning system 6 by concentric cable through amplifilter 5.Sensor 1 adopts 1# sensor, and sensor 2 adopts 2# sensor.

Use the present invention to carry out α value to measure:

According to Fig. 2 wiring, produce 5kHz-2.0MHz by high frequency signal generator 7, amplitude 2V-8V high-frequency signal adds to the high-pressure side of the winding A of transformer, records high-pressure side V1, the neutral end V2 voltage of winding A, by formula with dual beam oscilloscope 8

$\mathrm{\α}=\mathrm{ar}\cosh \left(\frac{V_1}{V_2}\right)$

By calculating, α value can be obtained.

During transformer neutral point ground connection, I _l1, I _n1, I _l0, I _n0parameter calibrating method: calibration test wiring as shown in Figure 3.

The calibrating signal that calibrating device 12 provides is injected through the head end of standard capacitance 11 at Transformer Winding A, through the signal that sensor 9, sensor 10 obtain, then obtains signal through amplifilter 13 and partial discharge of transformer positioning system 14 process.Sensor 9 adopts 1# sensor, and sensor 10 adopts 2# sensor.

I _l1-when calibration pulse sensor 9(and 1# sensor when winding high voltage end injects) signal that obtains.

I _n1-when calibration pulse sensor 10(and 2# sensor when winding high voltage end injects) signal that obtains.

Partial discharge of transformer location test step:

1, calibration parameter α and I of tested transformer is determined _l1, I _n1, I _l0, I _n0.

2, the signal obtained from tested transformer is I _l, I _n.

3, signal mode number conversion.

4, digital filtering and signal are differentiated.

5, discharge source position is determined.

It is to be noted that before data processing, inside transformer partial discharge pulse signal and undesired signal be distinguished, and reject undesired signal, thus obtain the partial discharge pulse pair of transformer first and end.In step 5 (signal authentication data treatment step), differentiate to have employed partial discharge of transformer " pulse effectively to " criterion to carrying out signal through described transformer each winding head end current digital amount of digital filtering and end current digital quantity.Pulse to the criterion that identification module rejects undesired signal is effectively: partial discharge pulse's signal of digital filtering inside transformer out must be that both have identical pulse number at high-pressure side and neutral point, waveform similarity, their first peak value occurs in mutually in the same time or within the μ S of time difference ± 0.8.All discharge pulse signals meeting above-mentioned requirements are called " pulse effectively to ", and what do not meet above-mentioned requirements will be considered as interference, all reject.

As shown in Figure 4, the shelf depreciation positioning system that adopts in force of the present invention.The workflow of shelf depreciation positioning system is, the signal that sensor 15-1,15-2 obtain enters amplifilter 16-1,16-2 respectively, through A/D converter 17-1,17-2 of being entered shelf depreciation positioning system by the signal of amplifilter 16-1,16-2 output again of amplification filtering, carry out the signal after analog to digital conversion by A/D converter 17-1,17-2 and send into digital filter block 18-1,18-2, pass through filtering, and then send into pulse effectively to identification module 19, carry out discharge pulse to discriminating, reject interference; Only have passed discharge pulse and just can enter data processing module 21 to the pulse signal (i.e. pulse effectively to) differentiated, respectively with α Value Data storehouse 20 and the I of data processing module 21 accessory _l1, I _n1, I _l0, I _n0parameter database 22 will participate in the data processing of data processing module 21.The output signal of data processing module 21 is admitted to shelf depreciation locating module 23, provides positioning result by shelf depreciation locating module 23.

Above-described embodiment is only for illustrating technical conceive of the present invention and realizing bare bones of the present invention; the technology contents that its object is to allow the those skilled in the art understanding the technology of the present invention solution can know the present invention to contain; and implement according to this, the protection domain that the technical solution that can not limit the present invention's proposition with this contains.The equivalent transformation that all Substantial technical contents proposed according to the present invention are done, all should be encompassed within protection scope of the present invention.

Claims (3)

1. Partial Discharge in Power Transformer electrical Location method, sensor is adopted to obtain the pulse current of Transformer Winding shelf depreciation generation, the pulse current that the Transformer Winding shelf depreciation obtained produces is processed, obtain the relevant information of pulse current, determine the position of the discharge source of Transformer Winding, it is characterized in that, obtain the relevant information of pulse current, determine that the position of the discharge source of Transformer Winding have employed and include signal sampling step, filter and amplification step, analog to digital conversion step, digital filtering step, the five steps of signal discriminating and Digital data processing step, wherein:

One, signal sampling step: adopt High Frequency Current Sensor, the pulse current of the head end of each winding of measuring transformer and the shelf depreciation generation of end respectively;

Two, filter and amplification step: the pulse current of the head end and the generation of end shelf depreciation of signal sampling step being measured to each winding of transformer obtained carries out filtering, amplification;

Three, analog to digital conversion step: analog to digital conversion is carried out to the pulse current that the head end of each winding of transformer after filtering, amplification and the shelf depreciation of end produce, obtains head end current digital amount and the end current digital quantity of each winding of transformer;

Four, digital filtering step: digital filtering is carried out to the head end current digital amount of each winding of described transformer and end current digital quantity;

Five, signal is differentiated and data processing step: carry out signal discriminating to the head end current digital amount of each winding of described transformer through digital filtering and end current digital quantity, distinguish partial discharge pulse's signal and the undesired signal of inside transformer, after rejecting undesired signal, again data processing is carried out to partial discharge pulse's signal of the inside transformer distinguished, by flow chart of data processing, find the accurate location of the Partial Discharge Sources of transformer;

Signal is differentiated and in data processing step, carry out data processing and used mathematical formulae, the mode of being carried out mathematical derivation and mathematical operation by computing machine carries out data processing;

Signal is differentiated and in data processing step, the mathematical formulae carrying out data processing utilization comprises the formula of following derivation:

In formula: X is the electrical distance of discharge source distance neutral point;

I _lthe signal that-transformer head end sensor obtains;

I _nthe signal that-transformer tip sensor obtains;

α, I _l1, I _n1, I _l0, I _n0parameter will be tried to achieve by experiment,

I _l1-when the calibration pulse local discharge signal that transformer head end sensor obtains when winding head end injects;

I _n1-when the calibration pulse local discharge signal that transformer tip sensor obtains when winding head end injects;

I _l0the shelf depreciation letter of-transformer head end sensor acquisition when property point injects in the windings in calibration pulse;

I _n0the local discharge signal of-transformer tip sensor the acquisition when property point injects in the windings in calibration pulse.

2. Partial Discharge in Power Transformer electrical Location method according to claim 1, is characterized in that, α, I _l1, I _n1, I _l0, I _n0the method that parameter is tried to achieve by experiment is: produce with signal generator the high-pressure side that high-frequency signal adds to transformer, record the voltage V1 of high-pressure side, the voltage V2 of neutral point, by formula with oscillograph

By calculating, obtain α value;

I is obtained by parameter calibrating method _l1, I _n1, I _l0, I _n0parameter, adopts calibrating device, makes transformer neutral point ground connection,

At transformer head end and end access sensor, the calibrating signal provided by calibrating device is injected through the head end of standard capacitance at transformer, the signal obtained through sensor, through the shelf depreciation positioning system process of amplifilter and transformer, obtains the first peak value of pulse and the parameter I of the head end of transformer and the local discharge signal of end _l1, I _n1; The sensor of the calibrating signal that calibrating device is provided directly through being connected on transformer neutral point and transformer end enters ground, obtains parameter I _l0, I _n0.

3. Partial Discharge in Power Transformer electrical Location method according to claim 1, it is characterized in that, signal is differentiated and in data processing step, carries out signal differentiate to have employed partial discharge of transformer " pulse effectively to " criterion to the head end current digital amount of each winding of described transformer through digital filtering and end current digital quantity; Partial discharge of transformer " pulse effectively to " criterion is: digital filtering inside transformer partial discharge pulse signal out must be that both have identical pulse number at high-pressure side and neutral point, waveform similarity, their first peak values occur in same time or within the μ S of time difference ± 0.8.