CN108508271B - Frequency sweep impedance testing device for transformer - Google Patents
Frequency sweep impedance testing device for transformer Download PDFInfo
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- CN108508271B CN108508271B CN201810565980.8A CN201810565980A CN108508271B CN 108508271 B CN108508271 B CN 108508271B CN 201810565980 A CN201810565980 A CN 201810565980A CN 108508271 B CN108508271 B CN 108508271B
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
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Abstract
The invention provides a frequency sweep impedance testing device for a transformer, and solves the technical problems that the traditional testing method has extremely high requirements on a sampling system and is difficult to ensure the sampling precision. The device of the invention comprises: the device comprises a frequency sweeping source, a power amplifier, a first measuring resistor, a second measuring resistor, a hardware divider and a true effective value conversion circuit; the output end of the frequency sweeping source is connected with the input end of the power amplifier; the output end of the power amplifier is respectively connected with the input end of the transformer and the first input end of the hardware divider; the first measuring resistor is connected between the power amplifier and the transformer; the output end of the transformer is connected with the second input end of the hardware divider; the output end of the transformer is also grounded through a second measuring resistor; and the output end of the hardware divider is connected with the input end of the true effective value conversion circuit.
Description
Technical Field
The invention relates to the technical field of transformer measurement, in particular to a frequency sweeping impedance testing device for a transformer.
Background
In power systems, transformers are one of the expensive and important devices. Due to the particularity of the internal structure, the transformer in operation is seriously damaged by factors such as misoperation of personnel, lightning current impact, sudden load change and the like. When the transformer is subjected to short-circuit impact current, the winding of the transformer can generate permanent deformation such as distortion, collapse, displacement and the like due to strong electrodynamic force, if the permanent deformation is not discovered and repaired in time, the deformation can be further developed due to the accumulative effect, further insulation failure of the winding is caused, and finally a power failure accident of the whole power system is caused. The state of the transformer winding is correctly and timely detected, and the safe operation of the transformer can be ensured to the maximum extent, so that the service life of the transformer is prolonged.
The early transformer overhaul is mostly manual cover hanging inspection, the method is time-consuming and labor-consuming, the effect is general, and improper operation can cause insulation moisture. In order to solve the above problems, a sweep frequency impedance method, which is a nondestructive testing method for transformers based on sweep frequency impedance detection, is proposed.
The sweep frequency impedance method is a novel transformer nondestructive testing method combining the advantages of a frequency response analysis method and a short circuit impedance method. According to the method, the condition of the winding can be accurately judged by comparing the deviation of the short circuit impedance value under the frequency of 10Hz-1MHz, the type and the position of the fault can be determined according to the change of the frequency-impedance curve (namely, the sweep frequency impedance curve) of the transformer, and the test system is shown in figure 2.
The impedance solving formula is as follows:
wherein j ω is a complex angle, Zk(j ω) is the complex impedance, Ui(j ω) is a complex input voltage, Uo(j ω) is the complex output voltage, I1(j ω) is the complex output current and α is the sampled resistivity. It can be seen from the formula (1) how to accurately measure the complex short-circuit impedance of the transformer under the frequency of 10Hz-1MHz and finally solve the modulus | Z of the complex short-circuit impedancek1(j ω) | is a difficult problem.
Conventional test method As shown in FIG. 3, U is collected by a high-speed acquisition cardi(j ω) and Uo(j ω) since the calculation requires accurate calculation of Ui(j ω) and UoIn order to meet the accuracy requirement of 1% of the phase and amplitude, the phase and amplitude of (j ω) needs a sampling frequency of 100MHz under the extreme condition that the input signal is 1MHz, and simultaneously needs high-accuracy sampling, so that the technical problems of extremely high requirement on a sampling system and difficulty in ensuring the sampling accuracy exist.
Disclosure of Invention
The invention provides a frequency sweep impedance testing device for a transformer, and solves the technical problems that the traditional testing method has extremely high requirements on a sampling system and is difficult to ensure the sampling precision.
The invention provides a frequency sweep impedance testing device of a transformer, which comprises:
the device comprises a frequency sweeping source, a power amplifier, a first measuring resistor, a second measuring resistor, a hardware divider and a true effective value conversion circuit;
the output end of the frequency sweeping source is connected with the input end of the power amplifier;
the output end of the power amplifier is respectively connected with the input end of the transformer and the first input end of the hardware divider;
the first measuring resistor is connected between the power amplifier and the transformer;
the output end of the transformer is connected with the second input end of the hardware divider;
the output end of the transformer is also grounded through the second measuring resistor;
and the output end of the hardware divider is connected with the input end of the true effective value conversion circuit.
Optionally, the apparatus for testing frequency sweep impedance of a transformer provided by the present invention further includes:
a data acquisition card;
and the input end of the data acquisition card is connected with the output end of the true effective value conversion circuit.
Optionally, the swept frequency source generates a sinusoidal signal.
Optionally, the power amplifier amplifies the voltage amplitude of the sinusoidal signal to at least 20V and the current amplitude of the sinusoidal signal to at least 1A.
According to the technical scheme, the invention has the following advantages:
the invention provides a frequency sweep impedance testing device of a transformer, which comprises: the device comprises a frequency sweeping source, a power amplifier, a first measuring resistor, a second measuring resistor, a hardware divider and a true effective value conversion circuit; the output end of the frequency sweeping source is connected with the input end of the power amplifier; the output end of the power amplifier is respectively connected with the input end of the transformer and the first input end of the hardware divider; the first measuring resistor is connected between the power amplifier and the transformer; the output end of the transformer is connected with the second input end of the hardware divider; the output end of the transformer is also grounded through the second measuring resistor; and the output end of the hardware divider is connected with the input end of the true effective value conversion circuit.
According to the invention, the measurement signal sent by the sweep frequency source is processed through the hardware divider and the true effective value conversion circuit, so that the impedance measurement precision of the transformer is improved, the phase characteristic of the complex division is kept by utilizing the characteristic of the hardware divider in the time domain, the correctness of the test result is ensured, and the technical problems that the traditional test method has extremely high requirements on a sampling system and the sampling precision is difficult to ensure are solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
Fig. 1 is a schematic structural diagram of a frequency-sweep impedance testing apparatus for a transformer according to the present invention;
FIG. 2 is an equivalent circuit diagram of a frequency sweep impedance test of a transformer;
FIG. 3 is a schematic structural diagram of a conventional apparatus for testing swept-frequency impedance of a transformer;
wherein the reference numerals are:
1. sweeping the frequency source; 2. a power amplifier; 3. a first measuring resistance; 4. a second measurement resistance; 5. a transformer; 6. a hardware divider; 7. a true significance value conversion circuit; 8. a data acquisition card; 9. a computer.
Detailed Description
The embodiment of the invention provides a frequency sweep impedance testing device for a transformer, and solves the technical problems that the traditional testing method has extremely high requirements on a sampling system and is difficult to ensure the sampling precision.
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below 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, an embodiment of a device for testing swept-frequency impedance of a transformer according to the present invention includes:
the device comprises a frequency sweeping source 1, a power amplifier 2, a first measuring resistor 3, a second measuring resistor 4, a hardware divider 6 and a true effective value conversion circuit 7;
the output end of the frequency sweeping source 1 is connected with the input end of the power amplifier 2;
the output end of the power amplifier 2 is respectively connected with the input end of the transformer 5 and the first input end of the hardware divider 6;
the first measuring resistor 3 is connected between the power amplifier 2 and the transformer 5;
the output end of the transformer 5 is connected with the second input end of the hardware divider 6;
the output end of the transformer 5 is also grounded through a second measuring resistor 4;
the output end of the hardware divider 6 is connected with the input end of the true effective value conversion circuit 7;
it should be noted that, since the hardware divider 6 is an analog circuit, the division is performed in the time domain, which can be effectively performed
And (6) operation. U input by hardware divider 6i(jω)、Uo(j omega) is a sine wave voltage signal under the frequency of 10Hz-1MHz to obtain a division result Zk1(j ω) is also a sinusoidal voltage signal, Zk1The phase and amplitude characteristics are fully preserved in (j ω).
The true effective value conversion circuit 7 can convert the effective values of sinusoidal voltage signals with different frequencies into direct current voltage for output, and for the testing device, the sine wave voltage signal Z under the frequency of 10Hz-1MHzk1(j ω) to | Zk1(j ω) | corresponding to the dc voltage signal.
According to the embodiment of the invention, the measurement signal sent by the sweep frequency source 1 is processed through the hardware divider 6 and the true effective value conversion circuit 7, so that the impedance measurement precision of the transformer 5 is improved, the phase characteristic of the complex division is reserved by utilizing the characteristic of the hardware divider 6 in the time domain, the correctness of the test result is ensured, and the technical problems that the traditional test method has extremely high requirements on a sampling system and is difficult to ensure the sampling precision are solved.
Further, the apparatus for testing frequency sweep impedance of a transformer provided by the embodiment of the present invention further includes:
a data acquisition card 8;
the input end of the data acquisition card is connected with the output end of the true effective value conversion circuit 7;
it should be noted that, compared with the data acquisition card 8 in the conventional test scheme, the acquisition card in the new scheme only needs to acquire the | Z output by the true effective value conversion circuit 7 with high precisionk1The direct-current voltage signal corresponding to (j omega) I can be obtained, the sampling rate of 100Hz can meet the requirement, and an acquisition card with low rate and higher precision can be selected, so that the cost and the difficulty of the acquisition card are greatly reduced, and the sampling precision is greatly improved; the data acquisition card 8 is connected with the computer 9, and transmits the acquired data to the computer 9 for subsequent calculation and analysis.
Further, the swept source 1 generates a sinusoidal signal.
Further, the power amplifier 2 amplifies the voltage amplitude of the sinusoidal signal to at least 20V and the current amplitude of the sinusoidal signal to at least 1A.
The working mode of the frequency sweep impedance testing device for the transformer provided by the embodiment of the invention is as follows:
s1) the sweep frequency source 1 outputs a small sinusoidal voltage signal of 10Hz-1MHz according to the sweep frequency node requirement;
s2) the power amplifier 2 amplifies small signal sine voltage waveform, the maximum voltage value of the amplified signal is required to be not less than 20V, and the output maximum current is required to be not less than 1A;
s3) inputting the amplified signal into the transformer 5 to be tested;
s4) converting through the first measuring resistor 3 and the second measuring resistor 4, sending the input voltage Ui and the output voltage Uo to a hardware divider 6 circuit, completing the division operation of the sinusoidal voltage signal in the time domain, and outputting a sinusoidal voltage signal Zk1 corresponding to the division result;
s5) inputting the output signal of the hardware divider 6 to the true effective value conversion circuit 7, and converting the effective value of the sinusoidal voltage signal into a direct current voltage signal;
s6) inputting the direct current voltage signal into the acquisition card and completing high-precision acquisition of the voltage signal;
s7) sending the collected voltage and current data to a computer 9 for calculation and analysis;
s8) to draw conclusions about the operation of the transformer 5.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (3)
1. A frequency sweep impedance testing device for a transformer is characterized by comprising:
the device comprises a frequency sweeping source, a power amplifier, a first measuring resistor, a second measuring resistor, a hardware divider and a true effective value conversion circuit;
the output end of the frequency sweeping source is connected with the input end of the power amplifier;
the output end of the power amplifier is respectively connected with the input end of the transformer and the first input end of the hardware divider;
the first measuring resistor is connected between the power amplifier and the transformer;
the output end of the transformer is connected with the second input end of the hardware divider;
the output end of the transformer is also grounded through the second measuring resistor;
the output end of the hardware divider is connected with the input end of the true effective value conversion circuit;
a data acquisition card;
and the input end of the data acquisition card is connected with the output end of the true effective value conversion circuit.
2. A transformer swept impedance test apparatus as claimed in claim 1, wherein the swept source generates a sinusoidal signal.
3. A transformer swept impedance test apparatus as claimed in claim 2, wherein the power amplifier amplifies the voltage amplitude of the sinusoidal signal to at least 20V and the current amplitude of the sinusoidal signal to at least 1A.
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| CN201810565980.8A CN108508271B (en) | 2018-06-04 | 2018-06-04 | Frequency sweep impedance testing device for transformer |
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| CN110244127B (en) * | 2019-07-30 | 2021-03-12 | 广东电网有限责任公司 | Device and method for testing frequency sweeping impedance of transformer |
| CN111624404B (en) * | 2020-05-08 | 2022-04-05 | 西安交通大学 | Online transformer impedance spectrum measurement system and measurement method |
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| CN100373166C (en) * | 2005-11-30 | 2008-03-05 | 上海市电力公司 | Device for detecting transformer winding state utilizing sweep frequency power source exciting |
| CN105004260A (en) * | 2015-07-02 | 2015-10-28 | 贵阳供电局 | Method for deformation test of transformer winding by utilization of frequency sweep short circuit impedance method |
| CN105445553A (en) * | 2015-11-12 | 2016-03-30 | 广东电网有限责任公司电力科学研究院 | Method for precisely acquiring short-circuit impedance value of transformer at 50Hz |
| CN107037313B (en) * | 2016-11-28 | 2019-06-04 | 国家电网公司 | The method for establishing deformation of transformer winding failure Yu frequency sweep impedance characteristic corresponding relationship |
| CN106771625A (en) * | 2017-02-28 | 2017-05-31 | 国网陕西省电力公司电力科学研究院 | A kind of frequency sweep impedance test system of low-power consumption |
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