CN114062761A - Transformer grounding wire AC/DC component detection device - Google Patents
Transformer grounding wire AC/DC component detection device Download PDFInfo
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- CN114062761A CN114062761A CN202111336716.5A CN202111336716A CN114062761A CN 114062761 A CN114062761 A CN 114062761A CN 202111336716 A CN202111336716 A CN 202111336716A CN 114062761 A CN114062761 A CN 114062761A
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- 238000001514 detection method Methods 0.000 title claims abstract description 12
- 230000005291 magnetic effect Effects 0.000 claims abstract description 27
- 238000005070 sampling Methods 0.000 claims abstract description 13
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- 230000001419 dependent effect Effects 0.000 claims abstract description 7
- 238000001914 filtration Methods 0.000 claims description 16
- 238000004458 analytical method Methods 0.000 claims description 11
- 230000006698 induction Effects 0.000 claims description 7
- 230000001052 transient effect Effects 0.000 claims description 4
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 claims description 3
- 239000003063 flame retardant Substances 0.000 claims description 3
- 238000009434 installation Methods 0.000 claims description 3
- 239000011810 insulating material Substances 0.000 claims description 2
- 238000005259 measurement Methods 0.000 abstract description 6
- 238000012544 monitoring process Methods 0.000 abstract description 6
- 238000000034 method Methods 0.000 description 8
- 238000004364 calculation method Methods 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
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- 230000000694 effects Effects 0.000 description 2
- 230000005294 ferromagnetic effect Effects 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- 230000007935 neutral effect Effects 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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Abstract
The invention relates to a transformer grounding wire alternating current-direct current component detection device which comprises a current sensor, a collector and a display terminal, wherein the current sensor comprises a plurality of TMR magneto-dependent current sensors, and an array of the TMR magneto-dependent current sensors is arranged in a protective shell; the collector comprises a sampling circuit, a main control unit and an edge computing terminal, the TMR magnetic-sensing current sensor is electrically connected with the input end of the sampling circuit, the output end of the sampling circuit is electrically connected with the input end of the main control unit, and the main control unit is respectively connected with the edge computing terminal and the display terminal. The TMR magnetosensitive current sensors realize measurement of alternating current and direct current components, higher harmonics and magnetic bias signals. The TMR magnetic-sensing current sensor solves the problems of low parameter monitoring precision and the like of the conventional current sensor.
Description
Technical Field
The invention relates to the technical field of measurement and calculation of alternating current and direct current components of a transformer grounding wire, in particular to a device for detecting alternating current and direct current components of a transformer grounding wire.
Background
At present, the combination of an electromagnetic induction coil and a Hall sensor is used for monitoring the AC/DC condition at the grounding wire of a transformer. For example, patent document CN 205015382U discloses a transformer neutral point dc component detection device. However, the problems are not favorable for the lean management requirement of equipment.
Disclosure of Invention
The invention aims to provide a device for detecting alternating current and direct current components of a grounding wire of a transformer, which is used for detecting the alternating current and direct current components of the grounding wire of the transformer.
The technical scheme of the invention is as follows:
a transformer grounding wire alternating current-direct current component detection device comprises a current sensor, a collector and a display terminal, wherein the current sensor comprises a plurality of TMR magneto-dependent current sensors, and an array of the TMR magneto-dependent current sensors is arranged in a protective shell; the collector comprises a sampling circuit, a main control unit and an edge computing terminal, the TMR magnetic-sensing current sensor is electrically connected with the input end of the sampling circuit, the output end of the sampling circuit is electrically connected with the input end of the main control unit, and the main control unit is respectively connected with the edge computing terminal and the display terminal.
Preferably, the collector further comprises a power module and a local display screen, the sampling circuit is arranged in the analog quantity data receiving module, a database is arranged in the edge computing terminal, the main control unit is electrically connected with the local display screen, and the power module supplies power to the current sensor, the main control unit, the analog quantity data receiving module, the edge computing terminal and the local display screen.
Preferably, the display terminal includes at least one of a mobile phone, an IPAD and a computer.
Preferably, the protective casing is made of an insulating flame-retardant material, the protective casing is composed of two half-shells, a through hole is formed in the joint of the two half-shells so as to be conveniently installed on the transformer grounding wire in an open mode, and two magnetic shielding half rings, an insulating half ring, a magnetic sensing chip and a double-layer Magnetic Tunnel Junction (MTJ) are arranged in the protective casing.
Preferably, the main control unit is electrically connected with the computer through an RJ45 interface bus.
Preferably, a kalman filtering algorithm, a fourier transform and a wavelet analysis algorithm are built in the edge computing terminal, the kalman filtering algorithm is used for filtering the magnetic induction current, the wavelet packet transform is used for decomposing the filtered magnetic induction current into a low-frequency approximate part and a high-frequency detail part, and the wavelet packet transform is used for analyzing the high-frequency detail part to obtain the characteristic information of the transient component; and analyzing the low-frequency approximate part by using a Blackman window interpolation algorithm to obtain the frequency and amplitude of the steady-state component.
The invention has the beneficial effects that:
the TMR magnetic-sensing current sensor can be used for measuring alternating current and direct current components, higher harmonics and magnetic bias signals, when the TMR magnetic-sensing current sensor is used, one TMR magnetic-sensing current sensor is used for measuring alternating current and direct current components, higher harmonics or magnetic bias signals, and a plurality of TMR magnetic-sensing current sensors are used for measuring the alternating current and direct current components, the higher harmonics and the magnetic bias signals. The TMR magnetic-sensing current sensor solves the problems of low precision, poor interchangeability, low monitoring precision of parameters such as alternating current, direct current, harmonic waves and the like caused by the change of signals along with temperature, nonlinear output and the like in the application of the conventional current sensor.
2. The small current detection mode of open installation can better meet the requirements of field occasions, but the resolution and the precision of sampling are lost, and the undesirable changes such as errors, temperature drift and the like are inevitably improved; the general structure of the magnetic tunnel junction MTJ is a sandwich structure of ferromagnetic layer/nonmagnetic insulating layer/ferromagnetic layer, and in order to solve the adverse effect caused by open installation, a double-layer magnetic tunnel junction is adopted to improve the magnetoresistance change rate.
3. The Kalman filtering algorithm can avoid the complicated solution of a nonlinear equation set and has more reliable measurement precision. The Fourier transform can obtain the harmonic frequency and amplitude of the current to be detected in the harmonic detection of the grounding copper bar flowing through the transformer, the method improves the calculation efficiency, has the advantages of high precision and simple operation, but can not be applied to the analysis of harmonic signals in a time domain and is mostly used for the detection of steady-state signals; the wavelet analysis can project higher harmonics in the power system to different scales, time domain signals and frequency domain signals of current can be collected at the same time, the defect of Fourier transform is well made up, the harmonic signals can be comprehensively and effectively analyzed through the combination of the wavelet analysis and the frequency domain signals, and the real-time performance and the accuracy of current collection are improved.
Drawings
Fig. 1 is a block diagram of a structure of a device for detecting ac/dc components of a transformer ground line.
FIG. 2 is a schematic diagram of a TMR magneto-dependent current sensor structure.
The reference number indicates that 1-current sensor, 2-collector, 3-display terminal, 4-protective shell, 5-through hole, 6-screw through hole, 7-wiring terminal.
Detailed Description
The present invention is described below in terms of embodiments in conjunction with the accompanying drawings to assist those skilled in the art in understanding and implementing the present invention. Unless otherwise indicated, the following embodiments and technical terms therein should not be understood to depart from the background of the technical knowledge in the technical field.
Example 1: a transformer grounding line alternating current-direct current component detection device is shown in figure 1 and comprises a current sensor 1, a collector 2 and a display terminal 3, wherein the current sensor 1 adopts a TMR magnetic-sensitive current sensor; the collector 2 comprises a main control unit, a power supply module, an analog quantity data receiving module, an edge computing terminal, a database and a local display screen; the display terminal 3 comprises a mobile phone, an IPAD and a computer.
Referring to fig. 2, the protective casing 4 of the current sensor 1 is made of flame retardant insulating material, such as epoxy resin, which has insulating and high temperature resistant properties to protect the internal devices. The protective shell 4 is composed of two half-shells, and a through hole 5 is arranged at the joint of the two half-shells so as to be conveniently installed on the transformer grounding wire in an open mode. The current sensor is suitable for measuring grounding wires of transformers in various styles, and the problem that the grounding wires of the transformers cannot be disassembled is solved. Two magnetic shielding half rings, an insulating half ring, a magnetic sensing chip and a double-layer Magnetic Tunnel Junction (MTJ) are arranged in the protective shell 4.
The current sensor 1 adopts a TMR magnetic-sensing current sensor, a plurality of current sensors 1 are arranged and fixed on a transformer grounding wire in an array mode, and alternating current and direct current components, higher harmonics and magnetic biasing signals are respectively collected through different current sensors. The current sensor 1 is powered by the collector power module.
An analog quantity data receiving module of the collector 2 receives the AC/DC component, the higher harmonic and the magnetic bias signal of the current sensor 1; a Kalman filtering algorithm, a Fourier transform algorithm and a wavelet analysis algorithm are built in the edge computing terminal to process current data; the database comprises historical current data, real-time current sampling data, basic information data and an expert database; the measured current data and the database information are displayed on a local display screen; the wiring terminal 7 is used for supplying power to the TMR magnetic-sensing current sensor, transmits real-time data to the display terminal 3, and simultaneously can select an algorithm to match the acquired measurement signal on a computer, so that monitoring of current data at multiple positions can be realized, and the real-time monitoring of transformer wiring and timely fault elimination of the transformer wiring can be facilitated for workers.
The method for detecting alternating current and direct current by Tmr is as follows: the Tmr current sensor can detect alternating current and direct current signals, supplies power for 5V, outputs a range of 0.5V-4.5V, and outputs a zero bias voltage of 2.5V, namely 2.5V is 0A, 0.5-2.5V represents current reversal, 2.5V-4.5 represents current forward, if the output signal is 0.5-4.5V, the current sensor is alternating current, and if the output signal is only 0.5-2.5V or 2.5-4.5V, the current sensor is direct current.
The Kalman filtering algorithm is a recursive filtering algorithm, and the method specifically comprises the steps of establishing a known system model and counting noise characteristics, solving optimal linear estimation under the condition of minimum mean square error by estimating and correcting signals of a current acquisition module, and performing recursive filtering, namely performing real-time estimation on a current value according to a previous estimation value and a last observation variable value by matching a state equation and a variance matrix. The Kalman filtering algorithm can avoid the complicated solution of a nonlinear equation set and has more reliable measurement precision.
The kalman filter algorithm is an algorithm that employs a recursive method to reduce the influence of noise. The magnetic induction current is the current output by the TMR magnetic-sensing current sensor. Filtering the magnetic induction current by using a Kalman filtering algorithm, and firstly establishing a system state equation and a measurement equation formula:
xn＝Φnxn-1+wn
zn＝Hnxn+vn
in the formula phin、HnRepresenting the coefficient of the equation, xnBeing the state of a scalar system, znTo contain noise vnState x ofnThe observed variable value of (a). The estimation formula of the state value and the covariance, and the Kalman filtering gain are as follows:
xn|n-1＝Φnxn|n
in the formula, wnIs a mean of 0 and a variance of Qn-1White gaussian noise of (1); v. ofnIs a mean of 0 and a variance of RnWhite gaussian noise of (1); knIs the Kalman filter gain; pn|n-1Is the error covariance.
And decomposing the filtered magnetic induction signal into a low-frequency approximate part and a high-frequency detail part through wavelet packet transformation, wherein the transient component is contained in the high-frequency detail part, each secondary steady-state component is in the low-frequency approximate part, and the high-frequency detail part is analyzed through the wavelet packet transformation to obtain the characteristic information of the transient component. And analyzing the decomposed steady-state component by adopting a Blackman window interpolation algorithm to obtain the frequency and amplitude of the steady-state component.
The Fourier transform can obtain the harmonic times and amplitude of the current to be detected in the harmonic detection of the grounding copper bar flowing through the transformer, the calculation efficiency is improved by the method, and the method has the advantages of high precision and simplicity in operation, but the method cannot be applied to the analysis of harmonic signals in a time domain and is mainly used for the detection of steady-state signals. Wavelet analysis can project higher harmonics in the power system to different scales, time domain signals and frequency domain signals of current can be collected at the same time, the defects of Fourier transform are well made up, harmonic signals can be comprehensively and effectively analyzed through the combination of the wavelet analysis and the frequency domain signals, and the real-time performance and accuracy of current collection are improved.
When the TMR magnetic current sensor is used, the TMR magnetic current sensor obtains primary side current data by utilizing a tunnel magnetoresistance effect, and is different from Hall sensors and other products widely used in the market. The power supply module and the analog quantity receiving module of the collector 2 are connected through the wiring terminal, sensors at different positions are sequenced and named on the display terminal 3, corresponding algorithms are selected to collect different current data, the obtained current data are analyzed and displayed on an on-site display screen through a Kalman filtering algorithm, a Fourier transform algorithm and a wavelet analysis algorithm which are arranged in the edge computing terminal, accuracy and more accurate data analysis are improved, the current data and related data are analyzed and displayed, meanwhile, the current data and the related data can be stored in a historical database, analysis data can be generated through the display terminal 3, future fault occurrence possibility judgment is facilitated, the protection capability is further improved, real-time monitoring of workers is facilitated, and faults can be found and eliminated in time.
The invention is described in detail above with reference to the figures and examples. It should be understood that in practice the description of all possible embodiments is not exhaustive and that the inventive concepts are described herein as far as possible by way of illustration. Without departing from the inventive concept of the present invention and without any creative work, a person skilled in the art should, in all of the embodiments, make optional combinations of technical features and experimental changes of specific parameters, or make a routine replacement of the disclosed technical means by using the prior art in the technical field to form specific embodiments, which belong to the content implicitly disclosed by the present invention.
Claims (6)
1. The alternating current-direct current component detection device for the grounding wire of the transformer is characterized by comprising a current sensor, a collector and a display terminal, wherein the current sensor comprises a plurality of TMR magneto-dependent current sensors, and an array of the TMR magneto-dependent current sensors is arranged in a protective shell; the collector comprises a sampling circuit, a main control unit and an edge computing terminal, the TMR magnetic-sensing current sensor is electrically connected with the input end of the sampling circuit, the output end of the sampling circuit is electrically connected with the input end of the main control unit, and the main control unit is respectively connected with the edge computing terminal and the display terminal.
2. The device for detecting ac/dc components of a ground wire of a transformer according to claim 1, wherein the collector further comprises a power module and a local display, the sampling circuit is disposed in the analog data receiving module, the edge computing terminal is disposed with a database, the main control unit is electrically connected to the local display, and the power module supplies power to the current sensor, the main control unit, the analog data receiving module, the edge computing terminal and the local display.
3. The apparatus according to claim 1, wherein the display terminal comprises at least one of a mobile phone, an IPAD and a computer.
4. The device for detecting ac/dc component of ground line of transformer of claim 3, wherein said main control unit is electrically connected to said computer through an RJ45 interface bus.
5. The device for detecting ac/dc component of ground line of transformer of claim 1, wherein said protective casing is made of flame-retardant insulating material, and is composed of two half-shells, and a through hole is formed at the joint of the two half-shells for easy open installation on the ground line of transformer, and two magnetic shielding half-rings, an insulating half-ring, a magnetic sensing chip and a double-layer magnetic tunnel junction MTJ are disposed in said protective casing.
6. The device for detecting the alternating current and direct current components of the grounding wire of the transformer as claimed in claim 1, wherein a Kalman filtering algorithm, a Fourier transform and a wavelet analysis algorithm are built in the edge computing terminal, the Kalman filtering algorithm is used for filtering the magnetic induction current, the wavelet packet transform is used for decomposing the filtered magnetic induction current into a low-frequency approximate part and a high-frequency detail part, and the wavelet packet transform is used for analyzing the high-frequency detail part to obtain the characteristic information of the transient component; and analyzing the low-frequency approximate part by using a Blackman window interpolation algorithm to obtain the frequency and amplitude of the steady-state component.
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| CN201974477U (en) * | 2010-11-24 | 2011-09-14 | 上海仪器仪表研究所 | Detecting and analyzing device for harmonic waves of power system |
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| WO2021094135A1 (en) * | 2019-11-13 | 2021-05-20 | Wago Verwaltungsgesellschaft Mbh | Series terminal element |
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2021
- 2021-11-12 CN CN202111336716.5A patent/CN114062761A/en active Pending
Patent Citations (6)
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| WO2021094135A1 (en) * | 2019-11-13 | 2021-05-20 | Wago Verwaltungsgesellschaft Mbh | Series terminal element |
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