CN103389446A - 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 the 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 surpasses state specified standards, will search the discharge position, determine position, fix a breakdown a little.

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

Chinese patent literature CN102207532A disclosed " paper oil insulation early discharge defect diagnostic method " (application number: 201110055118.6) comprising: gather the partial discharge pulse's signal in the single power frequency period of transformer, extract pulse number; PHASE DISTRIBUTION to the transformer discharge pulse is added up, and 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 discharge in transformer is in commitment.This invention has realized in frequency, phase place and oil by discharge pulse the characteristic parameters such as gas content, and the early stage shelf depreciation defect of identification transformer inside, for Transformer State Assessment and maintenance provide support.But the applicant finds to searching out spark location, certain help is arranged though this PHASE DISTRIBUTION to the transformer discharge pulse is carried out statistical under study for action, has certain limitation.the applicant thinks: Chinese patent literature CN102207532A disclosed " paper oil insulation early discharge defect diagnostic method " (number of patent application: 201110055118.6) following weak point is arranged: one, as everyone knows, the partial discharge of transformer pulse is extremely similar to other discharge-type interference waveforms, and " paper oil insulation early discharge defect diagnostic method " do not illustrate it is how transformer partial discharge signal and undesired signal to be made a distinction, therefore this invention is in order to " to have realized the frequency by discharge pulse, the characteristic parameter such as gas content in phase place and oil, the early stage shelf depreciation defect of identification transformer inside " method be not accurate enough, because " frequency of discharge pulse " can only add up all pulse signals, can not guarantee that these pulses are that transformer is inner entirely and produce, it has also comprised various discharge undesired signals, thus, may cause erroneous judgement.Its two, " paper oil insulation early discharge defect diagnostic method " (number of patent application: 201110055118.6) it can only determine that transformer inside has had discharge to occur, but the discharge source position that can't accurately make transformer.

Summary of the invention

The objective 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 transformer inside exactly from sampled signal, can be directly after rejecting undesired signal and the shelf depreciation source position of making accurately power transformer.It both can when power transformer is tested, also can be determined at the power transformer partial discharge position that carries out in service.The present invention is the current impulse that produces while 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, adopt sensor to obtain the pulse current that the Transformer Winding shelf depreciation produces, the pulse current that the Transformer Winding shelf depreciation of obtaining 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 relevant information that obtains pulse current has adopted and has included the signal sampling step with the position of determining the discharge source of Transformer Winding, the filter and amplification step, the analog to digital conversion step, the digital filtering step, the five steps of signal discriminating and Digital data processing step, wherein:

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

Two, filter and amplification step: the head end of resulting each winding of transformer of signal sampling step measurement and the pulse current of end shelf depreciation generation are carried out filtering, amplification;

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

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

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

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

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

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

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

$P=\frac{I_{L1}{\mathrm{<figure-callout\; id="0"\; label="I\; L"\; filenames="130726154817.png,130726154825.png"\; state="\{\{state\}\}">I</figure-callout>}}_L\mathrm{sh\&alpha;ch\&alpha;}+I_{N1}{\mathrm{<figure-callout\; id="0"\; label="I\; N"\; filenames="130726154817.png,130726154825.png"\; state="\{\{state\}\}">I</figure-callout>}}_N\mathrm{sh\&alpha;}}{I_{L1}{I}_{N0}-I_{N1}{\mathrm{<figure-callout\; id="0"\; label="I\; N"\; filenames="130726154817.png,130726154825.png"\; state="\{\{state\}\}">I</figure-callout>}}_N{\mathrm{ch}}^2\mathrm{\&alpha;}}\&CenterDot;\&CenterDot;\&CenterDot;\left(3\right)$

$Q=\frac{I_{L0}{\mathrm{<figure-callout\; id="1"\; label="I\; N"\; filenames="130726154829.png"\; state="\{\{state\}\}">I</figure-callout>}}_N\mathrm{sh\&alpha;ch\&alpha;}+I_{N1}{\mathrm{<figure-callout\; id="0"\; label="I\; N"\; filenames="130726154817.png,130726154825.png"\; state="\{\{state\}\}">I</figure-callout>}}_N\mathrm{sh\&alpha;}}{I_{L1}{I}_{N0}-I_{L0}{\mathrm{<figure-callout\; id="1"\; label="I\; N"\; filenames="130726154829.png"\; state="\{\{state\}\}">I</figure-callout>}}_N{\mathrm{ch}}^2\mathrm{\&alpha;}}\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right)$

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

I _LThe signal that-transformer head end sensor obtains;

I _NThe signal that-transformer tip sensor is obtained;

α, I _L1, I _N1, I _L0, I _N0Parameter is tried to achieve by experiment, and

$\mathrm{\&alpha;}=\mathrm{ar}\cosh \left(\frac{V_1}{V_2}\right)$

I _L1-when the calibration pulse local discharge signal that transformer head end sensor obtains when the winding head end injects;

I _N1-when the calibration pulse local discharge signal that the transformer tip sensor is obtained when winding head injects;

I _L0-when the calibration pulse local discharge signal that transformer head end sensor obtains when the winding neutral point injects;

I _N0-when the calibration pulse local discharge signal that the transformer tip sensor is obtained when the winding neutral point injects.

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 high-frequency signal with signal generator and add to the high-pressure side of transformer, record the voltage V1 of high-pressure side, the voltage V2 of neutral point with oscillograph, by formula

$\mathrm{\&alpha;}=\mathrm{ar}\cosh \left(\frac{V_1}{V_2}\right)$

, by calculating, obtain the α value;

Obtain I 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, injected through the head end of standard capacitance at transformer by the calibrating signal that calibrating device provides, process through the shelf depreciation positioning system of amplifilter and transformer through the signal that sensor obtains, obtaining the head end of transformer and the local discharge signal of end is parameter I _L1, I _N1Making calibrating signal that calibrating device provides is directly that the sensor of transformer end enters ground through being connected on transformer neutral point, obtains parameter I _L0, I _N0.

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

It is characterized in that, partial discharge of transformer " pulse effectively to " criterion is: the inner partial discharge pulse of digital filtering transformer out signal 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 time difference ± 0.8 μ S.

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

It is characterized in that, the special parameter of the relation of the pulse current that special-purpose software for calculation is the head end of finding out spark location and Transformer Winding that obtains in will test, end passes through and application regularity thereof be compiled into for computing machine identify 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, consider the actual influence of transformer.Because, the equivalent circuit of transformer under the power-frequency voltage effect, the inductance of common available coil and resistance replace, and can disregard electric capacity.And when high frequency or Impulse Voltage, the electric capacity between winding and the impact of winding-to-earth capacity in necessary consideration transformer.Along with the frequency of operation of transformer further improves, iron core, iron-clad can produce iron magnetic action (such as Ji Skin effect, eddy current) inductance and the resistance that produce, also need to take into account.For the equivalent circuit of general transformer, need only consider that the inductance of transformer inner high voltage winding and electric capacity are turn-to-turn capacitance, layer capacitance and ground capacitance, ignore the impact of mutual inductance effect, iron magnetic action and the winding resistance of low pressure winding in transformer.

The applicant finds by research: can find by experiment a frequency band, in this frequency band scope, the impedance of the impedance ratio capacitive branch of inductive branch is much bigger, thereby the impact of inductive branch can not considered.And the frequency of this frequency range that finds by experiment is not again special height, and the caused inductance of the iron magnetic action of iron core, iron-clad and resistance is not appearance also, and this moment, the equivalent circuit of Transformer Winding can be regarded pure capacitive recurrent circuit approx as.This pure capacitive recurrent circuit, belong to linear circuit, when pulse current by the time, waveform can not change, and can not produce vibration yet, that is (in other words) any position probing to waveform be the same, be the amplitude difference.That is (in other words) in the head end of Transformer Winding, the pulse waveform that end point detection arrives, and the time that their first peak value occurs is identical.

But should be noted that the mathematic(al) representation of describing pure capacitive recurrent circuit is complicated hyperbolic function.For this reason, the applicant is on the basis that conducts in-depth research, find the position of discharge source generation and the signal at Transformer Winding two ends to have the test figure of correlativity to analyze and inquire into, think and can find out wherein regularity by using relevant mathematical formulae to carry out mathematical derivation, find out the head end of point of discharge (namely above-mentioned discharge source occurs) position and Transformer Winding, the relation of pulse current that end passes through.In addition, the applicant considers under the prerequisite that facilitates the present invention to apply, with obtain to find out in test the special parameter of relation of the head end of spark location and Transformer Winding, pulse current that end passes through and application regularity thereof be compiled into for computing machine identify and application software system, application regularity comprises rule and formula.As long as carried out following calibration test before transformer carries out the position location test of discharge source, obtain in software needed special parameter and by computer input in software systems, the mathematical formulae that just can use software systems to provide, calculate by mathematical formulae, determine the position of the discharge source in transformer.Applicant establishment for computing machine identification and software systems can be used as the software systems of special use.When transformer positions test, as long as get the head end signal (I of transformer at transformer first, last two ends _L) and the end signal (I of transformer _N), use computing machine, the software systems of the special use of request for utilization people establishment, the mathematical formulae that just can provide according to the software systems by special use easily, 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, find out spark location by the pulse current that the Transformer Winding shelf depreciation produces, adopt the mode of calibration test, obtained the head end of spark location and Transformer Winding, the relation of pulse current that end passes through; The mode of the calibration test of adopting is and existing popular superfrequency method, supercritical ultrasonics technology difference method; 2, the signal discriminating is carried out in head end current digital amount and the end current digital quantity of described each winding of transformer through digital filtering, distinguish partial discharge pulse's signal and the undesired signal of transformer inside, and the rejecting undesired signal, define the inner partial discharge pulse of this transformer signal and be " partial discharge of transformer pulse effectively to ".Adopt signal differentiate partial discharge pulse's signal and the undesired signal of differentiating transformer inside and reject undesired signal, method is reasonable, successful; 3, carrying out data and process namely come from each winding head end current digital amount of transformer and end current digital quantity through the inner partial discharge pulse of the transformer distinguished signal, is to use mathematical formulae, is undertaken by computing machine that mathematical derivation and mathematical operation carry out.Carrying out the data processing uses mathematical formulae to realize having practicality and reliability by computing machine; 4,, according to the special parameter of the head end that obtains spark location and Transformer Winding, pulse current that end passes through, use mathematical formulae, by computing machine, carry out mathematical derivation and mathematical operation, determine the position of the interior discharge source of transformer.5, obtain to find out in testing the special parameter of relation of the head end of spark location and Transformer Winding, pulse current that end passes through and application regularity (rule and formula) thereof be compiled into for computing machine identify and application software system, use very convenient.

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

Description of drawings

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

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

Fig. 3, application 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, describe specific embodiments of the invention 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 that the Transformer Winding shelf depreciation produces, the pulse current that the Transformer Winding shelf depreciation of obtaining produces is processed, make the position of discharge source, the concrete steps that adopt include signal sampling step, filter and amplification step, analog to digital conversion step, digital filtering step, signal is differentiated and the five steps of Digital data processing step, wherein:

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

Two, filter and amplification step: the head end of resulting each winding of transformer and the pulse current of end shelf depreciation generation are carried out filtering, amplification;

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

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

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

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

$\frac{I_L}{I_N}=\frac{(e^{\mathrm{\&alpha;x}}+e^{-\mathrm{\&alpha;x}})P/2+(e^{\mathrm{\&alpha;x}}+e^{-\mathrm{\&alpha;x}})/2}{[e^{\mathrm{\&alpha;}(1-x)}+e^{-\mathrm{\&alpha;}(1-x)}]Q/2+[e^{\mathrm{\&alpha;}(1-x)}-e^{-\mathrm{\&alpha;}(1-x)}]/2}\&CenterDot;\&CenterDot;\&CenterDot;\left(1\right)$

$\mathrm{\&alpha;}=\sqrt{\frac{C}{k}}\&CenterDot;\&CenterDot;\&CenterDot;\left(2\right)$

$P=\frac{I_{L1}{\mathrm{<figure-callout\; id="0"\; label="I\; L"\; filenames="130726154817.png,130726154825.png"\; state="\{\{state\}\}">I</figure-callout>}}_L\mathrm{sh\&alpha;ch\&alpha;}+I_{N1}{\mathrm{<figure-callout\; id="0"\; label="I\; N"\; filenames="130726154817.png,130726154825.png"\; state="\{\{state\}\}">I</figure-callout>}}_N\mathrm{sh\&alpha;}}{I_{L1}{I}_{N0}-I_{N1}{\mathrm{<figure-callout\; id="0"\; label="I\; N"\; filenames="130726154817.png,130726154825.png"\; state="\{\{state\}\}">I</figure-callout>}}_N{\mathrm{ch}}^2\mathrm{\&alpha;}}\&CenterDot;\&CenterDot;\&CenterDot;\left(3\right)$

$Q=\frac{I_{L0}{\mathrm{<figure-callout\; id="1"\; label="I\; N"\; filenames="130726154829.png"\; state="\{\{state\}\}">I</figure-callout>}}_N\mathrm{sh\&alpha;ch\&alpha;}+I_{N1}{\mathrm{<figure-callout\; id="0"\; label="I\; N"\; filenames="130726154817.png,130726154825.png"\; state="\{\{state\}\}">I</figure-callout>}}_N\mathrm{sh\&alpha;}}{I_{L1}{I}_{N0}-I_{L0}{\mathrm{<figure-callout\; id="1"\; label="I\; N"\; filenames="130726154829.png"\; state="\{\{state\}\}">I</figure-callout>}}_N{\mathrm{ch}}^2\mathrm{\&alpha;}}\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right)$

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

I _LThe signal that-transformer head end sensor obtains.

I _NThe signal that-transformer tip sensor is obtained.

α, I _L1, I _N1, I _L0, I _N0To try to achieve by experiment etc. parameter.

$\mathrm{\&alpha;}=\mathrm{ar}\cosh \left(\frac{V_1}{V_2}\right)$

I _L1-when the calibration pulse local discharge signal that transformer head end sensor obtains when the winding head end injects.

I _N1-when the calibration pulse local discharge signal that the transformer tip sensor is obtained when winding head injects.

I _L0-when the calibration pulse local discharge signal that transformer head end sensor obtains when the winding neutral point injects.

I _N0-when the calibration pulse local discharge signal that the transformer tip sensor is obtained when the winding neutral point injects.

In signal authentication data treatment step, carrying out that data process is to use mathematical formulae, and the mode of carrying out mathematical derivation and mathematical operation by computing machine carries out that data process.The mathematical formulae that uses is provided by the software for calculation of special use.The special parameter of the relation of the pulse current that the software for calculation of described special use is the head end that obtains to find out spark location and Transformer Winding in will test, end passes through and application regularity thereof be compiled into for computing machine identify and application software system, use so very conveniently, 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 high-frequency signal with signal generator and add to the high-pressure side of transformer, record the voltage V1 of high-pressure side, the voltage V2 of neutral point with oscillograph, by formula

$\mathrm{\&alpha;}=\mathrm{ar}\cosh \left(\frac{V_1}{V_2}\right)$

, by calculating, obtain the α value;

Obtain I 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, injected through the head end of standard capacitance at transformer by the calibrating signal that calibrating device provides, process through the shelf depreciation positioning system of amplifilter and transformer through the signal that sensor obtains, obtain the local discharge signal parameter I of head end and the end of transformer _L1, IN1; Making calibrating signal that calibrating device provides is directly that the sensor of transformer end enters ground through being connected on transformer neutral point, obtains parameter I _L0, I _N0.

The present invention needs to adopt relevant instrument and the operation of being correlated with in concrete enforcement:

One, the instrument that adopts: 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 are processed.

The sensor that adopts is comprised of coil, soft magnetic bodies iron core, and coil is on iron core, and coil turn 20-100 circle, be positioned in stainless steel casing;

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

Calibrating device adopts square wave output, 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 to pass the ground wire of transformer high-voltage bushing 3 end shields to earth point.Sensor 2 installation sites are that to pass transformer neutral point 4(be the 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 the 1# sensor, and sensor 2 adopts the 2# sensor.

Using the present invention to carry out the α value measures:

According to Fig. 2 wiring, produce 5kHz-2.0MHz with 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 with dual beam oscilloscope 8, by formula

$\mathrm{\&alpha;}=\mathrm{ar}\cosh \left(\frac{V_1}{V_2}\right)$

, by calculating, can obtain the α value.

During transformer neutral point ground connection, I _L1, I _N1, I _L0, I _N0Parameter calibrating method: the calibration test wiring as shown in Figure 3.

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

I _L1-when calibration pulse sensor 9(1# sensor when the winding high-pressure side injects) signal that obtains.

I _N1-when calibration pulse sensor 10(2# sensor when the winding high-pressure side injects) signal that obtains.

Partial discharge of transformer location test step:

1, determine calibration parameter α and the I of tested transformer _L1, I _N1, I _L0, I _N0.

2, the signal that obtains from tested transformer is I _L, I _N.

3, signal mode number conversion.

4, digital filtering and signal are differentiated.

5, discharge source location positioning.

Should be noted that: before data are processed, distinguish the inner partial discharge pulse's signal of transformer and undesired signal, and reject undesired signal, thereby obtain the partial discharge pulse pair of transformer first and end.In step 5 (signal authentication data treatment step), to carry out signal through each winding head end current digital amount of described transformer of digital filtering and end current digital quantity, differentiate and adopted partial discharge of transformer " pulse effectively to " criterion.Pulse to the criterion of identification module rejecting undesired signal is effectively: partial discharge pulse's signal of digital filtering transformer inside out must be that both have identical pulse number at high-pressure side and neutral point, waveform similarity, their first peak value occur in mutually in the same time or within time difference ± 0.8 μ S.All discharge pulse signals that meets above-mentioned requirements are called " pulse effectively to ", do not meet above-mentioned requirements will be considered as disturb, 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 respectively amplifilter 16-1,16-2, the signal by amplifilter 16-1,16-2 output through amplification filtering enters A/D converter 17-1, the 17-2 of shelf depreciation positioning system again, send into digital filter module 18-1,18-2 by the signal that A/D converter 17-1,17-2 carry out after analog to digital conversion, by filtering, and then send into pulse effectively to identification module 19, carry out discharge pulse to differentiating, reject and disturb; Only have and passed through discharge pulse and just can enter data processing module 21 to the pulse signal differentiated (be pulse effectively to), 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 of data processing module 21 and process.The output signal of data processing module 21 is admitted to shelf depreciation locating module 23, by shelf depreciation locating module 23, provides positioning result.

Above-described embodiment is only for illustrating technical conceive of the present invention and realizing bare bones of the present invention; its purpose is to allow the those skilled in the art who understands the technology of the present invention solution can know the technology contents that the present invention is contained; and implement according to this, can not limit the protection domain that technical solution that the present invention proposes contains with this.The equivalent transformation that all substantive technology contents that proposes according to the present invention are done, within all should being encompassed in protection scope of the present invention.

Claims (8)

1. Partial Discharge in Power Transformer electrical Location method, adopt sensor to obtain the pulse current that the Transformer Winding shelf depreciation produces, the pulse current that the Transformer Winding shelf depreciation of obtaining 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, the position of determining the discharge source of Transformer Winding has been adopted and has been included the signal sampling step, the filter and amplification step, the analog to digital conversion step, the digital filtering step, the five steps of signal discriminating and Digital data processing step, wherein:

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

Two, filter and amplification step: the head end of resulting each winding of transformer of signal sampling step measurement and the pulse current of end shelf depreciation generation are carried out filtering, amplification;

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

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

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

2. Partial Discharge in Power Transformer electrical Location method according to claim 1, it is characterized in that, in signal discriminating and data processing step, carry out the data processing and used mathematical formulae, the mode of mathematical derivation and mathematical operation of being undertaken by computing machine is carried out the data processing.

3. Partial Discharge in Power Transformer electrical Location method according to claim 2, is characterized in that, in signal discriminating and data processing step, the mathematical formulae that carries out data processing utilization comprises the formula of following derivation:

$\frac{I_L}{I_N}=\frac{(e^{\mathrm{\&alpha;x}}+e^{-\mathrm{\&alpha;x}})P/2+(e^{\mathrm{\&alpha;x}}+e^{-\mathrm{\&alpha;x}})/2}{[e^{\mathrm{\&alpha;}(1-x)}+e^{-\mathrm{\&alpha;}(1-x)}]Q/2+[e^{\mathrm{\&alpha;}(1-x)}-e^{-\mathrm{\&alpha;}(1-x)}]/2}\&CenterDot;\&CenterDot;\&CenterDot;\left(1\right)$

$\mathrm{\&alpha;}=\sqrt{\frac{C}{k}}\&CenterDot;\&CenterDot;\&CenterDot;\left(2\right)$

$P=\frac{I_{L1}{I}_{L0}\mathrm{sh\&alpha;ch\&alpha;}+I_{N1}{I}_{N0}\mathrm{sh\&alpha;}}{I_{L1}{I}_{N0}-I_{N1}{I}_{N0}{\mathrm{ch}}^2\mathrm{\&alpha;}}\&CenterDot;\&CenterDot;\&CenterDot;\left(3\right)$

$Q=\frac{I_{L0}{I}_{N1}\mathrm{sh\&alpha;ch\&alpha;}+I_{N1}{I}_{N0}\mathrm{sh\&alpha;}}{I_{L1}{I}_{N0}-I_{L0}{I}_{N1}{\mathrm{ch}}^2\mathrm{\&alpha;}}\&CenterDot;\&CenterDot;\&CenterDot;\left(4\right)$

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

I _LThe signal that-transformer head end sensor obtains;

I _NThe signal that-transformer tip sensor is obtained;

α, I _L1, I _N1, I _L0, I _N0Parameter will be tried to achieve by experiment,

$\mathrm{\&alpha;}=\mathrm{ar}\cosh \left(\frac{V_1}{V_2}\right)$

I _L1-when the calibration pulse local discharge signal that transformer head end sensor obtains when the winding head end injects;

I _N1-when the calibration pulse local discharge signal that the transformer tip sensor is obtained when winding head injects;

I _L0-when the calibration pulse shelf depreciation that transformer head end sensor obtains when the winding neutral point injects letter;

I _N0-when the calibration pulse local discharge signal that the transformer tip sensor is obtained when the winding neutral point injects.

4. Partial Discharge in Power Transformer electrical Location method according to claim 3, is characterized in that α, I _L1, I _N1, I _L0, I _N0The method that parameter is tried to achieve by experiment is: produce high-frequency signal with signal generator and add to the high-pressure side of transformer, record the voltage V1 of high-pressure side, the voltage V2 of neutral point with oscillograph, by formula

$\mathrm{\&alpha;}=\mathrm{ar}\cosh \left(\frac{V_1}{V_2}\right)$

, by calculating, obtain the α value;

Obtain IL1, IN1, IL0, IN0 parameter by parameter calibrating method, adopt calibrating device, make transformer neutral point ground connection, at transformer head end and end access sensor, injected through the head end of standard capacitance at transformer by the calibrating signal that calibrating device provides, the signal that obtains through sensor is processed through the shelf depreciation positioning system of amplifilter and transformer, and the first peak value of pulse that obtains the local discharge signal of the head end of transformer and end is parameter I L1, IN1; Making calibrating signal that calibrating device provides is directly that the sensor of transformer end enters ground through being connected on transformer neutral point, obtains parameter I L0, IN0.

5. Partial Discharge in Power Transformer electrical Location method according to claim 1, it is characterized in that, signal differentiate and data processing step in, the head end current digital amount of described each winding of transformer through digital filtering and end current digital quantity are carried out signal differentiate and adopted partial discharge of transformer " pulse effectively to " criterion.

6. Partial Discharge in Power Transformer electrical Location method according to claim 5, it is characterized in that, partial discharge of transformer " pulse effectively to " criterion is: the inner partial discharge pulse of digital filtering transformer out signal 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 time difference ± 0.8 μ S.

7. according to claim 2 or 3 described Partial Discharge in Power Transformer electrical Location methods, is characterized in that, the mathematical formulae of utilization adopts special-purpose software for calculation to provide.

8. Partial Discharge in Power Transformer electrical Location method according to claim 7, it is characterized in that, the special parameter of the relation of the pulse current that special-purpose software for calculation is the head end of finding out spark location and Transformer Winding that obtains in will test, end passes through and application regularity thereof be compiled into for computing machine identify and application software system, application regularity comprises rule and formula.

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