CN113311359A - Transformer internal fault discrimination method based on vector analysis - Google Patents
Transformer internal fault discrimination method based on vector analysis Download PDFInfo
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- 238000004458 analytical method Methods 0.000 title claims abstract description 23
- 238000012850 discrimination method Methods 0.000 title claims description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 80
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- G—PHYSICS
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Abstract
The invention discloses a method for distinguishing internal faults of a transformer based on vector analysis, and belongs to the technical field of state analysis of power equipment. The invention relates to a method for distinguishing internal faults of a transformer based on vector analysis, which comprises the following steps: s1, synchronously sampling the iron core leakage current and the clamp leakage current waveforms of the three phases of the transformer A, B, C; s2, respectively calculating iron core grounding zero sequence current and clamp grounding zero sequence current; s3, performing FFT calculation, and extracting the fundamental amplitude value and the phase value of each leakage current sampling waveform from all FFT calculation results respectively; and S4, judging whether the grounding phenomenon exists in the iron core and the clamping piece in the transformer according to the data result of the step S3. The method can effectively find the weak grounding phenomenon of the iron core or the clamping piece in the transformer, avoid the problem of sensitivity in the traditional on-line monitoring of grounding current of the clamping piece of the iron core of the transformer, ensure the power utilization safety of power equipment and prevent accidents.
Description
Technical Field
The invention relates to the technical field of power equipment state analysis, in particular to a transformer internal fault distinguishing method based on vector analysis.
Background
The power transformer is an important electrical device in the power system, and once a fault occurs in operation, serious consequences can be caused to the power system. The iron core sheet is the main magnetic circuit part in the transformer and is generally formed by laminating hot-rolled or cold-rolled silicon steel sheets with high silicon content and insulating paint coated on the surfaces. The iron chip and the coil wound on the iron chip form a complete electromagnetic induction system. The amount of power transmitted by the power transformer depends on the material and cross-sectional area of the core sheet. The clamping piece is used for clamping the iron chip, meanwhile, the small support plate can be welded on the clamping piece, the wood piece for fixing the lead is arranged, the iron chip and the clamping piece must be grounded at a certain point when the power transformer normally operates, if the iron chip and the clamping piece are not grounded, the suspension voltage of the iron chip and the clamping piece to the ground can cause intermittent breakdown discharge of the iron chip and the clamping piece to the ground, and the possibility of forming the suspension potential of the iron chip is eliminated after the iron core and the clamping piece are grounded at a certain point. However, when the iron core and the clip are grounded at two or more points, the uneven potential between the iron core and the clip forms a circular current between the grounding points, and causes a multi-point grounding heating fault of the iron core and the clip.
The iron core grounding fault of the transformer can cause the local overheating of the iron core, when the iron core is serious, the local temperature rise of the iron core is increased, light gas acts, and even the tripping accident caused by heavy gas acts can be caused. The transformer core piece and the clip do not allow for multiple points to be grounded but only one point to be grounded. The traditional analysis of grounding current of a transformer iron chip and a clamp mainly focuses on the magnitude of the grounding current, if the measured value of the grounding current is larger than a set threshold value, alarm processing is carried out, and tiny grounding faults cannot be found in time.
Disclosure of Invention
The invention aims to provide a method for judging internal faults of a transformer based on vector analysis, so as to solve the problems in the background technology.
In order to solve the technical problems, the invention provides the following technical scheme: a transformer internal fault discrimination method based on vector analysis comprises the following steps:
s1, synchronously sampling the core leakage current and clip leakage current waveforms of the three phases of transformer A, B, C, where the input core leakage current and clip leakage current waveforms of the three phases of transformer A, B, C are respectively expressed as: i ist_a，It_b，It_c、Ij_a，Ij_b，Ij_c；
S2, respectively calculating the iron core grounding zero sequence current and the clamping piece grounding zero sequence current, and according to the formula:
It_0＝It_a+It_b+It_c
Ij_0＝Ij_a+Ij_b+Ij_c
wherein, It_0Grounding zero sequence current for the iron core; i isj_0Grounding zero sequence current for the clamping piece;
s3, pairs It_a，It_b，It_c，It_0、Ij_a，Ij_b，Ij_c，Ij_0Performing FFT calculation, and respectively extracting the fundamental amplitude value and the phase value of each leakage current sampling waveform from all FFT calculation results, and respectively expressing the fundamental amplitude value and the phase value as follows in a phasor mode:
Ibt_a∠θt_a，Ibt_b∠θt_b，Ibt_c∠θt_c，Ibt_0∠θt_0
Ibj_a∠θj_a，Ibj_b∠θj_b，Ibj_c∠θj_c，Ibj_0∠θj_0
and S4, judging whether the grounding phenomenon exists in the iron core and the clamping piece in the transformer according to the data result of the step S3.
The transformer under the unbalanced three-phase load operation inevitably generates zero sequence current, and the existence of the zero sequence current in the transformer generates zero sequence magnetic flux in the iron core, and the zero sequence magnetic flux forms a loop in the oil tank wall or other metal components of the transformer, so that the temperature of local metal parts of the transformer is abnormally increased, and the transformer operation accident can be caused in serious cases.
According to the above technical solution, in step S1, the output signals of the transformer A, B, C three-phase core and the clamp leakage current sensor are pulled to the same data acquisition device, and multi-channel AD synchronous acquisition is performed, or synchronous sampling may be performed by using any method based on IEEE 1588V2 high-precision time synchronization protocol or GPS or beidou second pulse time synchronization method.
Synchronous sampling refers to sampling at equal intervals in each period of a periodic signal, and meanwhile, the whole sampling interval is guaranteed to be exactly equal to the signal period and integral multiple of the signal period, namely, the sampling interval and the signal period are synchronized, and the synchronous sampling can theoretically recover the waveform without distortion by using the sampling point under the condition of meeting the sampling theorem, and has no measurement error.
According to the technical scheme, the error requirement of synchronous sampling of the leakage current waveform is less than 1us, the synchronous sampling of the leakage current waveform is completed by the data acquisition device, and the data acquisition device can periodically synchronously acquire the leakage current waveform and send the leakage current waveform to the system background for subsequent processing.
According to the technical scheme, each leakage current waveform at least comprises one sampling datum with the cycle length of 20ms, and the sampling waveforms of the leakage currents are synchronized with each other with high precision.
According to the technical scheme, the sampling frequency of A, B, C three-phase iron core leakage current and clamp leakage current waveforms is 12.8KHz, and each power frequency cycle is sampled at 256 points.
According to the above technical solution, in step S3, the FFT calculation is a 256-point FFT calculation.
The FFT calculation is a fast algorithm of discrete fourier transform, and can transform a signal into a frequency domain, and some signals are difficult to see certain characteristics in the time domain, but if the signals are transformed into the frequency domain, the characteristics can be easily seen, so the FFT calculation is the most commonly used method for calculating the effective value and the phase of the current.
According to the above technical solution, in step S3, the phase is calculated by extracting the real part and the imaginary part of the complex value of the fundamental wave calculation result in the FFT calculation result, and taking the inverse tangent of the ratio of the real part and the imaginary part as the phase.
According to the above technical solution, in the steps S3-S4, the step of determining that the grounding phenomenon exists in the transformer inner core is as follows:
s8-1, respectively calculating Ib of fundamental wave amplitude values of A, B, C three phases of iron core leakage currentst_a，Ibt_b，Ibt_cIs expressed as Ib, wherein the maximum value is expressed as Ibt_maxAnd the minimum value is denoted as Ibt_minAccording to the formula:
set the threshold value to IbFt_thIf present, IbFt_x＞IbFt_thJudging that the grounding phenomenon exists in the iron core inside the transformer;
s8-2, respectively calculating the absolute value of the difference between the phase difference value of the iron core leakage current between A, B, C three phases and the difference value of 120 degrees, according to the formula:
IbPHt-xA＝abs(IbPht_ab-120)
IbPHt-xB＝abs(IbPht_bc-120)
IbPHt-xC＝abs(IbPht_ca-120)
wherein IbPHt-xA、IbPHt-xB、IbPHt-xCThe absolute values of the difference between the phases of the three phases of the core leakage current A, B, C and the difference between 120 degrees, respectively;
wherein Ibpht_ab、IbPht_bc、IbPht_caFor the phase difference value, according to the formula:
IbPht_ab＝∠θt_a-∠θt_b
IbPht_bc＝∠θt_b-∠θt_c
IbPht_ca＝∠θt_c-∠θt_a
IbpHt-xA、IbPHt-xB、IbPHt-xCThe maximum value of (1) is recorded as IbPHt_tmax(ii) a Setting the threshold value to IbPHt_thIf IbPH is presentt_tmax＞IbPHt_thJudging that the grounding phenomenon exists in the iron core inside the transformer;
s8-3, setting the fundamental wave amplitude value threshold of the iron core grounding zero sequence current to Ib0t_thIf the fundamental wave amplitude value Ib of the iron core grounding zero sequence current existst_0＞Ib0t_thAnd judging that the iron core in the transformer is grounded.
According to the technical scheme, the method is characterized in that: in steps S3-S4, the step of determining that the transformer inner clip is grounded is as follows:
s9-1, respectively calculating Ib of fundamental wave amplitude values of A, B, C three phases of clip leakage currentj_a，Ibj_b，Ibj_cIs expressed as Ib, wherein the maximum value is expressed as Ibj_maxAnd the minimum value is denoted as Ibj_minAccording to the formula:
set the threshold value to IbFj_thIf present, IbFj_x＞IbFj_thJudging that the clamp inside the transformer has a grounding phenomenon;
s9-2, respectively calculating the absolute value of the difference value between the phase difference value of A, B, C three phases of the clip leakage current and the difference value of 120 degrees, according to the formula:
IbPHj-xA＝abs(IbPhj_ab-120)
IbPHj-xB＝abs(IbPhj_bc-120)
IbPHj-xC＝abs(IbPhj_ca-120)
wherein IbPHj-xA、IbPHj-xB、IbPHj-xCThe absolute values of the difference between the phases of the three phases of the core leakage current A, B, C and the difference between 120 degrees, respectively;
wherein Ibpht_ab、IbPht_bc、IbPht_caFor the phase difference value, according to the formula:
IbPht_ab＝∠θt_a-∠θt_b
IbPht_bc＝∠θt_b-∠θt_c
IbPht_ca＝∠θt_c-∠θt_a
IbpHt-xA、IbPHt-xB、IbPHt-xCThe maximum value of (1) is recorded as IbPHj_jmax(ii) a Setting the threshold value to IbPHj_thIf IbPH is presentj_jmax＞IbPHj_thJudging that the clamp inside the transformer has a grounding phenomenon;
s9-3, setting the fundamental amplitude value threshold of the clip grounding zero sequence current to Ib0j_thIf the fundamental wave amplitude value Ib of the clip grounding zero sequence current existsj_0＞Ib0j_thAnd judging that the clamp in the transformer is grounded.
Compared with the prior art, the invention has the following beneficial effects:
1. the method can effectively find the weak grounding phenomenon of the iron core or the clamping piece in the transformer, and avoid the problem of sensitivity in the traditional on-line monitoring of grounding current of the clamping piece of the iron core of the transformer;
2. according to the basic situation that in a normal state, fundamental wave vector values of three phases of iron core leakage current and clamp leakage current A, B, C are in a nearly balanced state and amplitudes are close and phases respectively have a difference of about 120 degrees, whether a grounding phenomenon exists in the interior of a transformer is judged by utilizing the absolute value and the phase difference value of the difference value between the three phases of leakage current (iron core or clamp) A, B, C and the difference value between 120 degrees;
3. the invention can detect the weak change of the iron core or the clamping piece, and prevent the iron core from being locally overheated to cause light gas action and even cause the tripping accident caused by heavy gas action to cause heavy loss due to inaccurate and neglected detection;
4. the invention provides an accurate sampling mode and a phase calculation mode, strictly limits the sampling process, and ensures the accuracy and effectiveness of synchronous sampling.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic diagram of a distinguishing process of a transformer internal fault distinguishing method based on vector analysis according to the present invention;
FIG. 2 is a schematic diagram illustrating the steps of a method for discriminating the internal fault of a transformer based on vector analysis according to the present invention;
fig. 3 is a schematic diagram of a decision flow of the transformer internal fault decision method based on vector analysis.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-3, the present invention provides the following technical solutions: a transformer internal fault discrimination method based on vector analysis comprises the following steps:
s1, synchronously sampling the core leakage current and clip leakage current waveforms of the three phases of transformer A, B, C, where the input core leakage current and clip leakage current waveforms of the three phases of transformer A, B, C are respectively expressed as: i ist_a，It_b，It_c、Ij_a，Ij_b，Ij_c；
S2, respectively calculating the iron core grounding zero sequence current and the clamping piece grounding zero sequence current, and according to the formula:
It_0＝It_a+It_b+It_c
Ij_0＝Ij_a+Ij_b+Ij_c
wherein, It_0Grounding zero sequence current for the iron core; i isj_0Grounding zero sequence current for the clamping piece;
s3, pairs It_a，It_b，It_c，It_0、Ij_a，Ij_b，Ij_c，Ij_0Performing FFT calculation, and respectively extracting the fundamental amplitude value and the phase value of each leakage current sampling waveform from all FFT calculation results, and respectively expressing the fundamental amplitude value and the phase value as follows in a phasor mode:
Ibt_a∠θt_a，Ibt_b∠θt_b，Ibt_c∠θt_c，Ibt_0∠θt_0
Ibj_a∠θj_a，Ibj_b∠θj_b，Ibj_c∠θj_c，Ibj_0∠θj_0
and S4, judging whether the grounding phenomenon exists in the iron core and the clamping piece in the transformer according to the data result of the step S3.
In step S1, the synchronous sampling is performed by pulling the output signals of the transformer A, B, C three-phase core and the clip leakage current sensor to the same data acquisition device, and using multiple paths of AD to perform synchronous acquisition, or using any method based on IEEE 1588V2 high-precision time synchronization protocol or GPS or beidou second pulse time synchronization method to perform synchronous sampling.
The error requirement of synchronous sampling of the leakage current waveform is less than 1us, the synchronous sampling of the leakage current waveform is completed by a data acquisition device, and the data acquisition device can periodically synchronously acquire the leakage current waveform and send the leakage current waveform to a system background for subsequent processing.
Each leakage current waveform at least comprises one sampling data with the cycle length of 20ms, and the sampling waveforms of the leakage currents are synchronized with each other with high precision.
A. B, C the sampling frequency of the three-phase core leakage current and clip leakage current waveforms is 12.8KHz, and each power frequency cycle is sampled at 256 points.
In step S3, the FFT calculation is a 256-point FFT calculation.
In step S3, the phase is calculated by extracting the real part and the imaginary part of the complex value of the fundamental wave calculation result in the FFT calculation result, and the inverse tangent of the ratio of the real part and the imaginary part is the phase.
In steps S3-S4, the step of determining that the grounding phenomenon exists in the transformer core is as follows:
s8-1, respectively calculating Ib of fundamental wave amplitude values of A, B, C three phases of iron core leakage currentst_a，Ibt_b，Ibt_cIs expressed as Ib, wherein the maximum value is expressed as Ibt_maxAnd the minimum value is denoted as Ibt_minAccording to the formula:
set the threshold value to IbFt_thIf present, IbFt_x＞IbFt_thJudging that the grounding phenomenon exists in the iron core inside the transformer;
s8-2, respectively calculating the absolute value of the difference between the phase difference value of the iron core leakage current between A, B, C three phases and the difference value of 120 degrees, according to the formula:
IbPHt-xA＝abs(IbPht_ab-120)
IbPHt-xB＝abs(IbPht_bc-120)
IbPHt-xC＝abs(IbPht_ca-120)
wherein IbPHt-xA、IbPHt-xB、IbPHt-xCThe absolute values of the difference between the phases of the three phases of the core leakage current A, B, C and the difference between 120 degrees, respectively;
wherein Ibpht_ab、IbPht_bc、IbPht_caFor the phase difference value, according to the formula:
IbPht_ab＝∠θt_a-∠θt_b
IbPht_bc＝∠θt_b-∠θt_c
IbPht_ca＝∠θt_c-∠θt_a
IbpHt-xA、IbPHt-xB、IbPHt-xCThe maximum value of (1) is recorded as IbPHt_tmax(ii) a Setting the threshold value to IbPHt_thIf IbPH is presentt_tmax＞IbPHt_thJudging that the grounding phenomenon exists in the iron core inside the transformer;
s8-3, setting the fundamental wave amplitude value threshold of the iron core grounding zero sequence current to Ib0t_thIf the fundamental wave amplitude value Ib of the iron core grounding zero sequence current existst_0＞Ib0t_thAnd judging that the iron core in the transformer is grounded.
In steps S3-S4, the step of determining that the transformer inner clip is grounded is as follows:
s9-1, respectively calculating Ib of fundamental wave amplitude values of A, B, C three phases of clip leakage currentj_a，Ibj_b，Ibj_cIs expressed as Ib, wherein the maximum value is expressed as Ibj_maxAnd the minimum value is denoted as Ibj_minAccording to the formula:
set the threshold value to IbFj_thIf present, IbFj_x＞IbFj_thJudging that the clamp inside the transformer has a grounding phenomenon;
s9-2, respectively calculating the absolute value of the difference value between the phase difference value of A, B, C three phases of the clip leakage current and the difference value of 120 degrees, according to the formula:
IbPHj-xA＝abs(IbPhj_ab-120)
IbPHj-xB＝abs(IbPhj_bc-120)
IbPHj-xC＝abs(IbPhj_ca-120)
wherein IbPHj-xA、IbPHj-xB、IbPHj-xCThe absolute values of the difference between the phases of the three phases of the core leakage current A, B, C and the difference between 120 degrees, respectively;
wherein Ibpht_ab、IbPht_bc、IbPht_caFor the phase difference value, according to the formula:
IbPht_ab＝∠θt_a-∠θt_b
IbPht_bc＝∠θt_b-∠θt_c
IbPht_ca＝∠θt_c-∠θt_a
IbpHt-xA、IbPHt-xB、IbPHt-xCThe maximum value of (1) is recorded as IbPHj_jmax(ii) a Setting the threshold value to IbPHj_thIf IbPH is presentj_jmax＞IbPHj_thJudging that the clamp inside the transformer has a grounding phenomenon;
s9-3, setting the fundamental amplitude value threshold of the clip grounding zero sequence current to Ib0j_thIf the fundamental wave amplitude value Ib of the clip grounding zero sequence current existsj_0＞Ib0j_thAnd judging that the clamp in the transformer is grounded.
In this embodiment:
firstly, synchronous sampling is carried out on iron core leakage current and clamp leakage current waveforms of three phases of a transformer A, B, C, a data acquisition device is arranged in the sampling process, and the synchronous sampling mode is that output signals of an iron core of three phases of a transformer A, B, C and a clamp leakage current sensor are pulled to the same data acquisition device and are synchronously acquired by multiple paths of AD;
setting the error requirement of waveform synchronous sampling to be less than 1 us;
the synchronous sampling of the leakage current waveform is completed by a data acquisition device, and the data acquisition device can periodically synchronously acquire the leakage current waveform and send the leakage current waveform to a system background for subsequent processing;
each leakage current waveform at least comprises sampling data with the cycle of 20ms, and the sampling waveforms of the leakage currents are synchronized with each other with high precision;
A. b, C the sampling frequency of the iron core leakage current and clamp leakage current wave forms of three phases is 12.8KHz, and each power frequency cycle samples 256 points;
after the synchronous sampling is finished, the input three-phase core leakage current and clip leakage current waveforms of the transformer A, B, C are respectively expressed as: i ist_a，It_b，It_c、Ij_a，Ij_b，Ij_c；
Respectively calculating the iron core grounding zero sequence current and the clamping piece grounding zero sequence current according to a formula:
It_0＝It_a+It_b+It_c
Ij_0＝Ij_a+Ij_b+Ij_c
wherein, It_0Grounding zero sequence current for the iron core; i isj_0Grounding zero sequence current for the clamping piece;
are respectively to It_a，It_b，It_c，It_0、Ij_a，Ij_b，Ij_c，Ij_0Performing FFT calculation;
wherein, the FFT calculation is a 256-point FFT calculation;
the phase calculation mode is to extract the real part and the imaginary part of the complex value of the fundamental wave calculation result in the FFT calculation result, and the inverse tangent of the ratio of the real part and the imaginary part is the phase;
the fundamental amplitude value and the phase value of each leakage current sampling waveform are respectively extracted from all FFT calculation results and are respectively expressed as follows in a phasor mode:
Ibt_a∠θt_a，Ibt_b∠θt_b，Ibt_c∠θt_c，Ibt_0∠θt_0
Ibj_a∠θj_a，Ibj_b∠θj_b，Ibj_c∠θj_c，Ibj_0∠θj_0
respectively calculating Ib of fundamental wave amplitude values of core leakage currents in A, B, C three phasest_a，Ibt_b，Ibt_cIs expressed as Ib, wherein the maximum value is expressed as Ibt_aAnd the minimum value is denoted as Ibt_bAccording to the formula:
set the threshold value to IbFt_thFound to exist IbFt_x＞IbFt_thTherefore, the grounding phenomenon of the iron core in the transformer is judged;
respectively calculating the absolute value of the difference between the phase difference value of the core leakage current between A, B, C three phases and the difference value of 120 degrees according to the formula:
IbPHt-xA＝abs(IbPht_ab-120)
IbPHt-xB＝abs(IbPht_bc-120)
IbPHt-xC＝abs(IbPht_ca-120)
wherein IbPHt-xA、IbPHt-xB、IbPHt-xCThe absolute values of the difference between the phases of the three phases of the core leakage current A, B, C and the difference between 120 degrees, respectively;
wherein Ibpht_ab、IbPht_bc、IbPht_caFor the phase difference value, according to the formula:
IbPht_ab＝∠θt_a-∠θt_b
IbPht_bc＝∠θt_b-∠θt_c
IbPht_ca＝∠θt_c-∠θt_a
IbpHt-xA、IbPHt-xB、IbPHt-xCThe maximum value of (1) is recorded as IbPHt_tmax；
Found in which IbPHt-xBThe threshold value is set to IbPH for the maximum valuet_thThe presence of IbPH was foundt-xB＞IbPHt_thTherefore, the grounding phenomenon of the iron core in the transformer is judged;
setting the fundamental amplitude value threshold value of the iron core grounding zero sequence current to Ib0t_thFinding out the fundamental amplitude value Ib of the zero-sequence current existing in the iron core groundingt_0＞Ib0t_thTherefore, the grounding phenomenon of the iron core in the transformer is judged.
And judging whether the grounding phenomenon exists in the internal clamping piece of the transformer according to the data:
separately calculating Ib of fundamental wave amplitude values of the clip leakage current in A, B, C three phasesj_a，Ibj_b，Ibj_cIs expressed as Ib, wherein the maximum value is expressed as Ibj_aAnd the minimum value is denoted as Ibj_bAccording to the formula:
set the threshold value to IbFj_thFound to exist IbFj_x＞IbFj_thTherefore, the grounding phenomenon of the clamp inside the transformer is judged;
the absolute values of the phase difference between the A, B, C three phases and the difference between 120 degrees of the clip leakage current are respectively calculated according to the formula:
IbPHj-xA＝abs(IbPhj_ab-120)
IbPHj-xB＝abs(IbPhj_bc-120)
IbPHj-xC＝abs(IbPhj_ca-120)
wherein IbPHj-xA、IbPHj-xB、IbPHj-xCThe absolute values of the difference between the phases of the three phases of the core leakage current A, B, C and the difference between 120 degrees, respectively;
wherein Ibpht_ab、IbPht_bc、IbPht_caFor the phase difference value, according to the formula:
IbPht_ab＝∠θt_a-∠θt_b
IbPht_bc＝∠θt_b-∠θt_c
IbPht_ca＝∠θt_c-∠θt_a
IbpHt-xA、IbPHt-xB、IbPHt-xCThe maximum value of (1) is IbPHt-xB(ii) a Setting the threshold value to IbPHj_thThe presence of IbPH was foundt-xB＞IbPHj_thTherefore, the grounding phenomenon of the clamp inside the transformer is judged;
setting the fundamental amplitude value threshold value of the clip grounding zero sequence current to Ib0j_thFinding the fundamental amplitude value Ib of the zero sequence current of the grounding of the clamping piecej_0＞Ib0j_thTherefore, the grounding phenomenon of the clamp inside the transformer is judged;
in conclusion, after synchronous sampling and calculation are carried out, the grounding phenomenon of the iron core and the clamping piece inside the transformer is judged, and at the moment, a worker is reminded to overhaul.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A transformer internal fault discrimination method based on vector analysis is characterized in that: the method comprises the following steps:
s1, synchronously sampling the core leakage current and clip leakage current waveforms of the three phases of transformer A, B, C, where the input core leakage current and clip leakage current waveforms of the three phases of transformer A, B, C are respectively expressed as: i ist_a，It_b，It_c、Ij_a，Ij_b，Ij_c；
S2, respectively calculating the iron core grounding zero sequence current and the clamping piece grounding zero sequence current, and according to the formula:
It_0＝It_a+It_b+It_c
Ij_0＝Ij_a+Ij_b+Ij_c
wherein, It_0Grounding zero sequence current for the iron core; i isj_0Grounding zero sequence current for the clamping piece;
s3, pairs It_a，It_b，It_c，It_0、Ij_a，Ij_b，Ij_c，Ij_0Performing FFT calculation, and respectively extracting the fundamental amplitude value and the phase value of each leakage current sampling waveform from all FFT calculation results, and respectively expressing the fundamental amplitude value and the phase value as follows in a phasor mode:
Ibt_a∠θt_a，Ibt_b∠θt_b，Ibt_c∠θt_c，Ibt_0∠θt_0
Ibj_a∠θj_a，Ibj_b∠θj_b，Ibj_c∠θj_c，Ibj_0∠θj_0
and S4, judging whether the grounding phenomenon exists in the iron core and the clamping piece in the transformer according to the data result of the step S3.
2. The method for distinguishing the internal fault of the transformer based on the vector analysis as claimed in claim 1, wherein: in step S1, the synchronous sampling is performed by pulling the output signals of the transformer A, B, C three-phase core and the clip leakage current sensor to the same data acquisition device, and using multiple paths of AD to perform synchronous acquisition, or using any method based on IEEE 1588V2 high-precision time synchronization protocol or GPS or beidou second pulse time synchronization method to perform synchronous sampling.
3. The method for distinguishing the internal fault of the transformer based on the vector analysis as claimed in claim 2, wherein: the error requirement of synchronous sampling of the leakage current waveform is less than 1us, the synchronous sampling of the leakage current waveform is completed by a data acquisition device, and the data acquisition device can periodically synchronously acquire the leakage current waveform and send the leakage current waveform to a system background for subsequent processing.
4. The method for distinguishing the internal fault of the transformer based on the vector analysis as claimed in claim 2, wherein: each leakage current waveform at least comprises one sampling data with the cycle length of 20ms, and the sampling waveforms of the leakage currents are synchronized with each other with high precision.
5. The method for distinguishing the internal fault of the transformer based on the vector analysis as claimed in claim 2, wherein: A. b, C the sampling frequency of the three-phase core leakage current and clip leakage current waveforms is 12.8KHz, and each power frequency cycle is sampled at 256 points.
6. The method for distinguishing the internal fault of the transformer based on the vector analysis as claimed in claim 1, wherein: in step S3, the FFT calculation is a 256-point FFT calculation.
7. The method for distinguishing the internal fault of the transformer based on the vector analysis as claimed in claim 1, wherein: in step S3, the phase is calculated by extracting the real part and the imaginary part of the complex value of the fundamental wave calculation result in the FFT calculation result, and the inverse tangent of the ratio of the real part and the imaginary part is the phase.
8. The method for distinguishing the internal fault of the transformer based on the vector analysis as claimed in claim 1, wherein: in steps S3-S4, the step of determining that the grounding phenomenon exists in the transformer core is as follows:
s8-1, respectively calculating Ib of fundamental wave amplitude values of A, B, C three phases of iron core leakage currentst_a，Ibt_b，Ibt_cIs expressed as Ib, wherein the maximum value is expressed as Ibt_maxAnd the minimum value is denoted as Ibt_minAccording to the formula:
set the threshold value to IbFt_thIf present, IbFt_x＞IbFt_thJudging that the grounding phenomenon exists in the iron core inside the transformer;
s8-2, respectively calculating the absolute value of the difference between the phase difference value of the iron core leakage current between A, B, C three phases and the difference value of 120 degrees, according to the formula:
IbPHt-xA＝abs(IbPht_ab-120)
IbPHt-xB＝abs(IbPht_bc-120)
IbPHt-xC＝abs(IbPht_ca-120)
wherein IbPHt-xA、IbPHt-xB、IbPHt-xCThe absolute values of the difference between the phases of the three phases of the core leakage current A, B, C and the difference between 120 degrees, respectively;
wherein Ibpht_ab、IbPht_bc、IbPht_caFor the phase difference value, according to the formula:
IbPht_ab＝∠θt_a-∠θt_b
IbPht_bc＝∠θt_b-∠θt_c
IbPht_ca＝∠θt_c-∠θt_a
IbpHt-xA、IbPHt-xB、IbPHt-xCThe maximum value of (1) is recorded as IbPHt_tmax(ii) a Setting the threshold value to IbPHt_thIf IbPH is presentt_tmax＞IbPHt_thThen, it is determined that there is grounding in the transformer coreLike;
s8-3, setting the fundamental wave amplitude value threshold of the iron core grounding zero sequence current to Ib0t_thIf the fundamental wave amplitude value Ib of the iron core grounding zero sequence current existst_0＞Ib0t_thAnd judging that the iron core in the transformer is grounded.
9. The method for distinguishing the internal fault of the transformer based on the vector analysis as claimed in claim 1, wherein: in steps S3-S4, the step of determining that the transformer inner clip is grounded is as follows:
s9-1, respectively calculating Ib of fundamental wave amplitude values of A, B, C three phases of clip leakage currentj_a，Ibj_b，Ibj_cIs expressed as Ib, wherein the maximum value is expressed as Ibj_maxAnd the minimum value is denoted as Ibj_minAccording to the formula:
set the threshold value to IbFj_thIf present, IbFj_x＞IbFj_thJudging that the clamp inside the transformer has a grounding phenomenon;
s9-2, respectively calculating the absolute value of the difference value between the phase difference value of A, B, C three phases of the clip leakage current and the difference value of 120 degrees, according to the formula:
IbPHj-xA＝abs(IbPhj_ab-120)
IbPHj-xB＝abs(IbPhj_bc-120)
IbPHj-xC＝abs(IbPhj_ca-120)
wherein IbPHj-xA、IbPHj-xB、IbPHj-xCThe absolute values of the difference between the phases of the three phases of the core leakage current A, B, C and the difference between 120 degrees, respectively;
wherein Ibpht_ab、IbPht_bc、IbPht_caFor the phase difference value, according to the formula:
IbPht_ab＝∠θt_a-∠θt_b
IbPht_bc＝∠θt_b-∠θt_c
IbPht_ca＝∠θt_c-∠θt_a
IbpHt-xA、IbPHt-xB、IbPHt-xCThe maximum value of (1) is recorded as IbPHj_jmax(ii) a Setting the threshold value to IbPHj_thIf IbPH is presentj_jmax＞IbPHj_thJudging that the clamp inside the transformer has a grounding phenomenon;
s9-3, setting the fundamental amplitude value threshold of the clip grounding zero sequence current to Ib0j_thIf the fundamental wave amplitude value Ib of the clip grounding zero sequence current existsj_0＞Ib0j_thAnd judging that the clamp in the transformer is grounded.
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| CN117538632A (en) * | 2023-08-08 | 2024-02-09 | 沈阳工业大学 | Grounding fault diagnosis device and method for converter transformer |
Citations (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1584614A (en) * | 2004-06-07 | 2005-02-23 | 山东大学 | Single-phase grounding selection for small-current system |
| CN2773870Y (en) * | 2004-11-30 | 2006-04-19 | 广东科旺电源设备有限公司 | Hopper-sensing insulated transformer with big power UPS and double iron core |
| CN1804649A (en) * | 2005-01-12 | 2006-07-19 | 杭州佳和电气有限公司 | Fault line selection method for single-phase-to-ground fault in small ground current distribution network |
| EP1693679A1 (en) * | 2005-02-21 | 2006-08-23 | Adaptive Regelsysteme GmbH | Method for the determination of a parameter of an electric power supply network |
| CN101813735A (en) * | 2009-02-24 | 2010-08-25 | 上海宝钢化工有限公司 | Grounding detection device for power distribution system and fault detection method thereof |
| US20110208449A1 (en) * | 2008-10-27 | 2011-08-25 | Tsinghua University | Method for detecting single phase grounding fault based on harmonic component of residual current |
| CN103412217A (en) * | 2013-08-02 | 2013-11-27 | 中科天工电气控股有限公司 | Box-type substation intelligent online failure diagnosis system |
| CN104037728A (en) * | 2014-05-05 | 2014-09-10 | 珠海许继电气有限公司 | Distribution circuit single-phase grounding protection control method based on software frequency measurement and harmonic wave analysis |
| CN105242228A (en) * | 2015-10-23 | 2016-01-13 | 国家电网公司 | Current blanking method and device of transformer iron core grounding current online monitoring equipment |
| US20160111869A1 (en) * | 2014-10-17 | 2016-04-21 | Hunan Xiangyi Railroad Locomotive Electrical Equipment Co, Ltd. | Leakage current detecting circuit-breaker with a flexible shield cord |
| CN109444528A (en) * | 2018-11-05 | 2019-03-08 | 北京许继电气有限公司 | A kind of Transformer Condition Monitoring System and method based on iron core grounding current |
| CN109637787A (en) * | 2017-10-09 | 2019-04-16 | 特变电工衡阳变压器有限公司 | Transformer excitation flow zero-sequence component suppressing method and inhibition device and transformer |
| CN209296856U (en) * | 2018-12-07 | 2019-08-23 | 上海鸿岩机械科技有限公司 | A kind of transformer simulation model being able to reflect multipoint earthing of iron core |
| CN111007435A (en) * | 2019-12-27 | 2020-04-14 | 广东电网有限责任公司电力科学研究院 | Monitoring method, device and equipment for analyzing transformer fault based on resistance-capacitance component |
| US20210083468A1 (en) * | 2018-01-09 | 2021-03-18 | Rensselaer Polytechnic Institute | Temporary overvoltage and ground fault overvoltage protection based on arrester current measurement and analysis |
-
2021
- 2021-05-13 CN CN202110524684.5A patent/CN113311359A/en active Pending
Patent Citations (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1584614A (en) * | 2004-06-07 | 2005-02-23 | 山东大学 | Single-phase grounding selection for small-current system |
| CN2773870Y (en) * | 2004-11-30 | 2006-04-19 | 广东科旺电源设备有限公司 | Hopper-sensing insulated transformer with big power UPS and double iron core |
| CN1804649A (en) * | 2005-01-12 | 2006-07-19 | 杭州佳和电气有限公司 | Fault line selection method for single-phase-to-ground fault in small ground current distribution network |
| EP1693679A1 (en) * | 2005-02-21 | 2006-08-23 | Adaptive Regelsysteme GmbH | Method for the determination of a parameter of an electric power supply network |
| US20110208449A1 (en) * | 2008-10-27 | 2011-08-25 | Tsinghua University | Method for detecting single phase grounding fault based on harmonic component of residual current |
| CN101813735A (en) * | 2009-02-24 | 2010-08-25 | 上海宝钢化工有限公司 | Grounding detection device for power distribution system and fault detection method thereof |
| CN103412217A (en) * | 2013-08-02 | 2013-11-27 | 中科天工电气控股有限公司 | Box-type substation intelligent online failure diagnosis system |
| CN104037728A (en) * | 2014-05-05 | 2014-09-10 | 珠海许继电气有限公司 | Distribution circuit single-phase grounding protection control method based on software frequency measurement and harmonic wave analysis |
| US20160111869A1 (en) * | 2014-10-17 | 2016-04-21 | Hunan Xiangyi Railroad Locomotive Electrical Equipment Co, Ltd. | Leakage current detecting circuit-breaker with a flexible shield cord |
| CN105242228A (en) * | 2015-10-23 | 2016-01-13 | 国家电网公司 | Current blanking method and device of transformer iron core grounding current online monitoring equipment |
| CN109637787A (en) * | 2017-10-09 | 2019-04-16 | 特变电工衡阳变压器有限公司 | Transformer excitation flow zero-sequence component suppressing method and inhibition device and transformer |
| US20210083468A1 (en) * | 2018-01-09 | 2021-03-18 | Rensselaer Polytechnic Institute | Temporary overvoltage and ground fault overvoltage protection based on arrester current measurement and analysis |
| CN109444528A (en) * | 2018-11-05 | 2019-03-08 | 北京许继电气有限公司 | A kind of Transformer Condition Monitoring System and method based on iron core grounding current |
| CN209296856U (en) * | 2018-12-07 | 2019-08-23 | 上海鸿岩机械科技有限公司 | A kind of transformer simulation model being able to reflect multipoint earthing of iron core |
| CN111007435A (en) * | 2019-12-27 | 2020-04-14 | 广东电网有限责任公司电力科学研究院 | Monitoring method, device and equipment for analyzing transformer fault based on resistance-capacitance component |
Non-Patent Citations (2)
| Title |
|---|
| SAEED, H等: "On-Site Low Voltage Determination of Zero-Sequence Impedances for Power Transformers", 《IEEE TRANSACTIONS ON POWER DELIVERY》, vol. 35, no. 2, 30 April 2020 (2020-04-30) * |
| 邵引红，等: "变压器铁芯多点接地故障的诊断及处理", 《安徽水利水电职业技术学院学报》, vol. 8, no. 2, 30 June 2008 (2008-06-30) * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117538632A (en) * | 2023-08-08 | 2024-02-09 | 沈阳工业大学 | Grounding fault diagnosis device and method for converter transformer |
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