CN111474430A - Excitation characteristic testing device of voltage transformer - Google Patents
Excitation characteristic testing device of voltage transformer Download PDFInfo
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- CN111474430A CN111474430A CN202010312358.3A CN202010312358A CN111474430A CN 111474430 A CN111474430 A CN 111474430A CN 202010312358 A CN202010312358 A CN 202010312358A CN 111474430 A CN111474430 A CN 111474430A
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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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- 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
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
- G01R19/2506—Arrangements for conditioning or analysing measured signals, e.g. for indicating peak values ; Details concerning sampling, digitizing or waveform capturing
- G01R19/2509—Details concerning sampling, digitizing or waveform capturing
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Abstract
The application discloses excitation characteristic testing device of voltage transformer, including data processing unit, excitation characteristic test circuit and programmable power supply. The excitation characteristic test circuit comprises a plurality of paths of AD sampling circuits, a plurality of program-controlled amplification circuits, a plurality of test branches and a voltage sampling mutual inductor, wherein each path of AD sampling circuit is used for collecting the output voltage of one path of program-controlled amplification circuit and obtaining a plurality of sampling voltage values, the input end of one path of program-controlled amplification circuit is used for connecting the output end of the voltage sampling mutual inductor, and the input ends of the other program-controlled amplification circuits are used for connecting the output end of one test branch; the test branch is used for connecting a tested voltage transformer; the data processing unit is used for acquiring a plurality of sampling voltage values and calculating the excitation characteristic data of the tested voltage transformer according to the basic parameters and the sampling voltage values of the tested voltage transformer. Through the scheme, the workload is reduced, and the test efficiency is improved.
Description
Technical Field
The application relates to the technical field of instruments, in particular to an excitation characteristic testing device of a voltage transformer.
Background
In a6 kV-35 kV distribution system in China, a neutral point of the system is not effectively grounded, an electromagnetic voltage transformer (PT) insulated to the ground is connected to a system bus, and when a bus switch is switched on, single-phase arc grounding automatically disappears or system load is changed violently in a circuit, a ferromagnetic resonance phenomenon is excited between the PT and a ground capacitor of a three-phase lead in a generated transient impact process. Ferromagnetic resonance can generate a relatively common internal overvoltage phenomenon in a power system, the voltage has long duration and can be self-maintained for a long time, the voltage is one of main reasons for destroying a voltage transformer, and is also one of induction reasons of certain major accidents in the power system, and the phenomenon poses a great threat to the safe operation of the power system.
Relevant test methods and judgment requirements are determined by the term 7.3.301 of the electromagnetic voltage transformer special part of the national standard GB20840-3 transformer. During the test, voltage is applied to the secondary terminal or the primary terminal, the voltage waveform is an actual sine wave, the rated voltage and the voltage value corresponding to the rated voltage factor (1.5 times or 1.9 times) are applied, the corresponding excitation current is measured, the difference between the result and the corresponding result of the type test is not more than 30%, and the difference between the excitation characteristics of the same-type voltage transformers produced in the same batch is not more than 30%.
Since the ungrounded electromagnetic voltage transformer used in the distribution network system is prone to ferroresonance, it is necessary to suppress and reduce the occurrence of ferroresonance or reduce the damage of ferroresonance when it occurs. The specific measures for eliminating the ferromagnetic resonance are many, one of them is to adopt a voltage transformer with better excitation characteristics, and the same group of voltage transformers installed need to have the same excitation characteristics. Therefore, before the electromagnetic voltage transformer is installed and operated, an excitation characteristic test needs to be carried out on the electromagnetic voltage transformer so as to sort the voltage transformers with unqualified excitation characteristics.
At present, an electromagnetic voltage transformer excitation test is mainly carried out in a manual mode by utilizing a power frequency voltage regulator, a measuring voltmeter and an ammeter, a test signal is power frequency sine wave voltage, the output of the voltage regulator is adjusted in a manual mode, and display data on the measuring voltmeter and the ammeter are read and recorded manually, so that the workload is large, and the efficiency is low.
Disclosure of Invention
In view of the above, the present application provides an excitation characteristic testing apparatus for a voltage transformer, which is used for testing the excitation characteristic of an electromagnetic voltage transformer to reduce the workload and improve the testing efficiency.
In order to achieve the above object, the following solutions are proposed:
the utility model provides a voltage transformer's excitation characteristic testing arrangement, includes data processing unit, excitation characteristic test circuit and programme-controlled power supply, data processing unit respectively with test circuit, programme-controlled power supply signal connection, wherein:
the voltage input end of the programmable power supply is externally connected with a commercial power network, and the signal output end is in signal connection with the data unit;
the excitation characteristic test circuit comprises a plurality of paths of AD sampling circuits, a plurality of program-controlled amplification circuits, a plurality of test branches and a voltage sampling mutual inductor, wherein each path of AD sampling circuit is used for collecting the output voltage of one path of program-controlled amplification circuit and obtaining a plurality of sampling voltage values, the input end of one path of program-controlled amplification circuit is used for connecting the output end of the voltage sampling mutual inductor, and the input ends of the other program-controlled amplification circuits are used for connecting the output end of one test branch;
the test branch comprises a micro current transformer and an on-off relay, one end of the on-off relay is used for connecting a tested voltage transformer, the other end of the on-off relay is respectively connected with a voltage output end of the programmable power supply and a primary winding of the micro current transformer, and a secondary winding of the micro current transformer is connected with a sampling resistor in parallel and is connected with an input end of a corresponding programmable amplifying circuit;
the data processing unit is used for acquiring the plurality of sampling voltage values and calculating the excitation characteristic data of the tested voltage transformer according to the basic parameters of the tested voltage transformer and the sampling voltage values.
Optionally, the output voltage of the programmable power supply is 0-250 volts.
Optionally, the excitation characteristic data includes excitation current data and/or excitation voltage data
Optionally, the data processing unit includes a processor, and further includes a liquid crystal display, a keyboard, a storage device, an I/O control port, and a communication port, which are in signal connection with the processor, wherein:
the keyboard is used for receiving the basic parameters;
the I/O control port is used for outputting a switching signal, and the switching signal is used for gating the test branch circuit;
the communication port is used for outputting a gain control instruction and a voltage control instruction, the gain control instruction is used for controlling the gain of the programmable amplifying circuit, and the voltage control instruction is used for controlling the output voltage of the programmable power supply.
Optionally, the data processing unit is further provided with a data transceiving port in signal connection with the processor, wherein:
the data receiving and transmitting port is used for being connected with an upper computer and used for uploading the excitation characteristic data to the upper computer.
Optionally, the processor is a TMS320F28335 chip.
According to the technical scheme, the excitation characteristic testing device of the voltage transformer comprises a data processing unit, an excitation characteristic testing circuit and a program-controlled power supply, wherein the data processing unit is in signal connection with the testing circuit and the program-controlled power supply respectively. The excitation characteristic test circuit comprises a plurality of paths of AD sampling circuits, a plurality of program-controlled amplification circuits, a plurality of test branches and a voltage sampling mutual inductor, wherein each path of AD sampling circuit is used for collecting the output voltage of one path of program-controlled amplification circuit and obtaining a plurality of sampling voltage values, the input end of one path of program-controlled amplification circuit is used for connecting the output end of the voltage sampling mutual inductor, and the input ends of the other program-controlled amplification circuits are used for connecting the output end of one test branch; the test branch comprises a micro current transformer and an on-off relay, one end of the on-off relay is used for connecting a voltage transformer to be tested, the other end of the on-off relay is respectively connected with a voltage output end of the programmable power supply and a primary winding of the micro current transformer, and a secondary winding of the micro current transformer is connected with a sampling resistor in parallel and is connected with an input end of a corresponding programmable amplifying circuit; the data processing unit is used for acquiring a plurality of sampling voltage values and calculating the excitation characteristic data of the tested voltage transformer according to the basic parameters and the sampling voltage values of the tested voltage transformer. Need not artifical regulation and read data through above-mentioned scheme and can obtain excitation characteristic data to reduce work load, in addition, only need a plurality of tested voltage transformer's test to also improve test efficiency simultaneously.
Drawings
In order to more clearly illustrate the embodiments of the present application 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, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a circuit diagram of an excitation characteristic testing apparatus of a voltage transformer according to an embodiment of the present application;
fig. 2 is an excitation current sampling and program-controlled amplification measuring circuit provided by the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, 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 application.
Example one
Fig. 1 is a circuit diagram of an excitation characteristic testing apparatus of a voltage transformer according to an embodiment of the present application.
As shown in fig. 1, the excitation characteristic testing apparatus provided in this embodiment is used to test the excitation characteristics of one or more electromagnetic voltage transformers to be tested, and the obtained excitation characteristic data includes excitation current data or excitation voltage data, or both. The excitation characteristic testing device comprises a data processing unit 10, an excitation characteristic testing circuit 20 and a programmable power supply 30.
The excitation characteristic test circuit comprises micro current transformers CT 1-CT 6 for sampling, sampling resistors R1-R6, on-off relays S1-S6, a voltage sampling transformer PT and program control amplification circuits A1-A7. Each sampling circuit, the corresponding micro current transformer and the corresponding channel relay form a testing branch, and one testing branch is used for testing one tested voltage transformer.
The secondary winding outputs of the micro current transformers CT 1-CT 6 are connected with sampling resistors R1-R6, and the excitation current in the primary winding of the micro current transformer is converted into voltage to be sent to the program control amplifying circuits A1-A6 at the later stage. The voltage sampling voltage transformer PT converts the voltage output by the program-controlled power supply into secondary small voltage and sends the secondary small voltage to the program-controlled amplifying circuit A7, and the outputs of A1-A7 are sent to the AD sampling circuit AD7606 for A/D sampling; the AD sampling circuit is a 16-way sampling circuit.
The input end of the programmable power supply is externally connected with an alternating current power supply, the output end of the programmable power supply is respectively connected with the input end of a voltage sampling transformer PT, and simultaneously connected with an external tested electromagnetic voltage transformer through current transformers CT 1-CT 6 of 6 channels and 6 on-off relays S1-S6; the output voltage is 0-250V.
The data processing unit comprises a processor, wherein the processor preferably selects a TMS320F28335 chip, an I/O control port, a liquid crystal display, a keyboard, a storage device and a communication port, and the communication port preferably selects an RS485 communication port.
The excitation characteristic test circuit is connected with the data processing unit. The data processing unit obtains basic parameters of the tested voltage transformer and a channel to be tested through a liquid crystal display, a keyboard or a network port, and the data processing unit also controls the gain of the programmable amplifying circuit, controls the output voltage amplitude of the programmable power supply, controls A/D measurement and obtains excitation characteristic data of the 6-channel tested voltage transformer according to algorithm requirements, such as excitation current data or excitation voltage data.
The amplification factor of the program control amplification circuit is 1-512 times.
It can be seen from the foregoing technical solutions that, this embodiment provides an excitation characteristic testing apparatus for a voltage transformer, which includes a data processing unit, an excitation characteristic testing circuit, and a program-controlled power supply, where the data processing unit is respectively in signal connection with the testing circuit and the program-controlled power supply. The excitation characteristic test circuit comprises a plurality of paths of AD sampling circuits, a plurality of program-controlled amplification circuits, a plurality of test branches and a voltage sampling mutual inductor, wherein each path of AD sampling circuit is used for collecting the output voltage of one path of program-controlled amplification circuit and obtaining a plurality of sampling voltage values, the input end of one path of program-controlled amplification circuit is used for connecting the output end of the voltage sampling mutual inductor, and the input ends of the other program-controlled amplification circuits are used for connecting the output end of one test branch; the test branch comprises a micro current transformer and an on-off relay, one end of the on-off relay is used for connecting a voltage transformer to be tested, the other end of the on-off relay is respectively connected with a voltage output end of the programmable power supply and a primary winding of the micro current transformer, and a secondary winding of the micro current transformer is connected with a sampling resistor in parallel and is connected with an input end of a corresponding programmable amplifying circuit; the data processing unit is used for acquiring a plurality of sampling voltage values and calculating the excitation characteristic data of the tested voltage transformer according to the basic parameters and the sampling voltage values of the tested voltage transformer. Need not artifical regulation and read data through above-mentioned scheme and can obtain excitation characteristic data to reduce work load, in addition, only need a plurality of tested voltage transformer's test to also improve test efficiency simultaneously.
The excitation characteristic testing device of the voltage transformer tests the tested voltage transformer by the following testing method:
2, collecting the excitation current of a voltage transformer of a tested product through current transformers CT 1-CT 6 for sampling and sampling resistors R1-R6, measuring the excitation voltage through a voltage sampling PT, amplifying a measurement signal through 7 paths of controllable gain amplifiers of 1-512 times in total from A1-A7, and then sending the amplified measurement signal to a port of an A/D sampling conversion module, wherein a data processing unit controls the gain of the controllable gain amplifiers to enable the measurement signal to be between 4V and 8V, the peak voltage to be less than 9V, and the measurement signal to be in a linear interval of the A/D sampling conversion module AD 7606;
and 3, controlling the AD7606 by using a data processing unit to carry out complete cycle 512-point sampling on the signal to obtain 7 paths of discrete digital signals, namely an excitation current discrete value and a1 path of excitation voltage discrete value of the tested voltage transformer of 6 paths, calculating effective value voltages of the excitation current of 6 paths and the excitation voltage of 1 path by an effective value algorithm, calculating an average value of the excitation current of 6 paths by an average value algorithm, and obtaining a peak value of the excitation current of 6 paths by a peak value judgment algorithm.
The method comprises the steps of respectively calculating effective value current I of 6 paths of exciting current by adopting a current true effective value algorithm, a formula (1), a voltage true effective value algorithm, a formula (2), a current average value algorithm formula (3) and a current peak value judgment algorithm formula (4) embedded in a data processing unit RMSn1 path of excitation voltage effective value U RMS6 paths of average current IAVGnAnd 6 paths of peak current IPPn。
IPPn＝knmax(|i(1)|～|i(N)|) (A) (4)
Wherein N is 512, knN is 1-6, k is the multiplying factor of the current test channeluThe multiplying factor of the voltage test channel.
And 4, displaying the exciting current (including the effective value current, the average value current and the peak value current) of the 6 paths of tested electromagnetic voltage transformers by the data processing unit through the liquid crystal display, displaying the effective value voltage of the exciting voltage, sending the measurement data to computer management software by the data processing unit through RS232, and realizing the functions of controlling the electromagnetic voltage transformer exciting characteristic tester and acquiring the measurement data by the computer management software, managing the acquired measurement data by a database, printing certificates and the like.
The excitation characteristic testing device can also test and apply to the tested voltage transformer through the following steps:
the excitation current measuring range of each channel is 10 mA-8A, the testing accuracy level is 0.5 level, the testing dynamic range reaches 1000 times, the lower limit current is very small, all testing stations share a testing power supply, and the electromagnetic voltage transformers of six stations are tested at most while the voltage is output, so that six testing current signals are measured by adopting a current transformer isolation measure to ensure that the six testing current signals are not interfered and associated with each other. Designing a measuring circuit capable of accurately measuring the mA-level current is a design key and difficulty of the voltage transformer excitation characteristic tester.
The high-performance measurement current transformer and the sampling circuit are adopted, so that the impedance of the measurement loop is smaller than 0.02 ohm, and the excitation data of the voltage transformer cannot be changed due to the fact that the current loop measures the internal resistance. Analysis was performed in a single channel: a 0.01-grade precision current transformer with 5A/10mA is used as a current sampling resistor, a 0.02% grade 100 omega resistor is used as a sampling resistor for the current transformer for the second time, and a current signal is converted into voltage; and then, a high-precision measurement and measurement circuit is adopted to carry out program-controlled amplification on the voltage signal, and finally, A/D sampling is accessed. The amplification factor of the signal is increased and the anti-interference capability is enhanced. As shown in fig. 2, the programmable amplifying circuit is implemented by using a programmable precision divider resistor chip MAX5431 and a high-performance operational amplifier OP 2177. The coefficient of the voltage dividing resistor is determined by adopting a 4-way and 1-way method through 2 digital signal lines, 1, 2, 4 and 8 amplification factors are realized together with the operational amplifier OP2177, and the gain accuracy is 0.025%. Three groups of amplifying circuits are adopted in each program-controlled amplifying circuit of the measuring object, the amplifying times of 1, 2, 4, 8, 16, 32, 64, 128, 256 and 512 are realized, and the measuring requirement of 1000 times of exciting current is met.
The embodiments in the present specification are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
While preferred embodiments of the present invention have been described, additional variations and modifications of these embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the embodiments of the invention.
Finally, it should also be 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 terminal 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 terminal. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or terminal that comprises the element.
The technical solutions provided by the present invention are described in detail above, and the principle and the implementation of the present invention are explained in this document by applying specific examples, and the descriptions of the above examples are only used to help understanding the method and the core idea of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
Claims (6)
1. The excitation characteristic testing device of the voltage transformer is characterized by comprising a data processing unit, an excitation characteristic testing circuit and a program-controlled power supply, wherein the data processing unit is respectively connected with the testing circuit and the program-controlled power supply through signals, and the data processing unit is characterized in that:
the voltage input end of the programmable power supply is externally connected with a commercial power network, and the signal output end is in signal connection with the data unit;
the excitation characteristic test circuit comprises a plurality of paths of AD sampling circuits, a plurality of program-controlled amplification circuits, a plurality of test branches and a voltage sampling mutual inductor, wherein each path of AD sampling circuit is used for collecting the output voltage of one path of program-controlled amplification circuit and obtaining a plurality of sampling voltage values, the input end of one path of program-controlled amplification circuit is used for connecting the output end of the voltage sampling mutual inductor, and the input ends of the other program-controlled amplification circuits are used for connecting the output end of one test branch;
the test branch comprises a micro current transformer and an on-off relay, one end of the on-off relay is used for connecting a tested voltage transformer, the other end of the on-off relay is respectively connected with a voltage output end of the programmable power supply and a primary winding of the micro current transformer, and a secondary winding of the micro current transformer is connected with a sampling resistor in parallel and is connected with an input end of a corresponding programmable amplifying circuit;
the data processing unit is used for acquiring the plurality of sampling voltage values and calculating the excitation characteristic data of the tested voltage transformer according to the basic parameters of the tested voltage transformer and the sampling voltage values.
2. The excitation characteristic testing apparatus according to claim 1, wherein an output voltage of the programmable power supply is 0 to 250 volts.
3. The excitation characteristic test apparatus according to claim 1, wherein the excitation characteristic data includes excitation current data and/or excitation voltage data.
4. The excitation characteristic test apparatus of claim 1, wherein the data processing unit includes a processor, and further includes a liquid crystal display, a keyboard, a storage device, an I/O control port, and a communication port in signal connection with the processor, wherein:
the keyboard is used for receiving the basic parameters;
the I/O control port is used for outputting a switching signal, and the switching signal is used for gating the test branch circuit;
the communication port is used for outputting a gain control instruction and a voltage control instruction, the gain control instruction is used for controlling the gain of the programmable amplifying circuit, and the voltage control instruction is used for controlling the output voltage of the programmable power supply.
5. The excitation characteristic test apparatus according to claim 4, wherein the data processing unit is further provided with a data transceiving port in signal connection with the processor, wherein:
the data receiving and transmitting port is used for being connected with an upper computer and used for uploading the excitation characteristic data to the upper computer.
6. The excitation characteristic testing apparatus according to claim 4, wherein the processor is a TMS320F28335 chip.
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| SU1109690A1 (en) * | 1982-03-11 | 1984-08-23 | Киевский Ордена Ленина Политехнический Институт Им.50-Летия Великой Октябрьской Социалистической Революции | Device for checking voltage transormeps |
| CN201654218U (en) * | 2010-01-29 | 2010-11-24 | 平高集团有限公司 | Multifunctional testing stand of voltage transformer |
| CN202393849U (en) * | 2011-12-14 | 2012-08-22 | 保定供电公司 | Excitation characteristic quick testing device of voltage transformer |
| CN107024631A (en) * | 2017-05-27 | 2017-08-08 | 国网上海市电力公司 | With the volt-ampere characteristic test method of Multifunctional coil kind equipment testing synthesis parameter device |
| US10132875B1 (en) * | 2013-04-25 | 2018-11-20 | Power Control Systems, Inc. | Device and method for open phase detection |
| CN208156182U (en) * | 2018-04-13 | 2018-11-27 | 南京丹迪克电力仪表有限公司 | A kind of multichannel directly measures formula mutual-inductor tester |
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2020
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| SU1109690A1 (en) * | 1982-03-11 | 1984-08-23 | Киевский Ордена Ленина Политехнический Институт Им.50-Летия Великой Октябрьской Социалистической Революции | Device for checking voltage transormeps |
| CN201654218U (en) * | 2010-01-29 | 2010-11-24 | 平高集团有限公司 | Multifunctional testing stand of voltage transformer |
| CN202393849U (en) * | 2011-12-14 | 2012-08-22 | 保定供电公司 | Excitation characteristic quick testing device of voltage transformer |
| US10132875B1 (en) * | 2013-04-25 | 2018-11-20 | Power Control Systems, Inc. | Device and method for open phase detection |
| CN107024631A (en) * | 2017-05-27 | 2017-08-08 | 国网上海市电力公司 | With the volt-ampere characteristic test method of Multifunctional coil kind equipment testing synthesis parameter device |
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