CN114124016A - A frequency characteristic compensation method of shunt for reference standard - Google Patents
A frequency characteristic compensation method of shunt for reference standard Download PDFInfo
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- CN114124016A CN114124016A CN202010887176.9A CN202010887176A CN114124016A CN 114124016 A CN114124016 A CN 114124016A CN 202010887176 A CN202010887176 A CN 202010887176A CN 114124016 A CN114124016 A CN 114124016A
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- shunt
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- resistor
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/01—Frequency selective two-port networks
- H03H7/03—Frequency selective two-port networks comprising means for compensation of loss
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Abstract
The invention relates to a frequency characteristic compensation method of a shunt for reference standard, which is characterized in that a compensation circuit is connected in parallel on a resistor body of the shunt, and the compensation circuit comprises a compensation resistor and a compensation capacitor which are connected in series to form an RC (resistance-capacitance) compensation circuit. The frequency characteristic compensation method has obvious compensation effect on the frequency characteristic of the current divider used for the reference standard, and is used for experimental verification of the frequency characteristic of the direct current transformer.
Description
Technical Field
The invention relates to a frequency characteristic compensation method of a shunt for reference standards, belonging to the technical field of direct current transmission engineering.
Background
In the flexible direct current transmission project, in order to realize the ultra-high speed protection of the flexible direct current power grid, higher requirements are put forward on direct current measurement in the flexible direct current power grid system compared with the conventional direct current project. The accurate measurement of the current change rate and the amplitude is very important for realizing the rapid, reliable and accurate protection of the flexible direct-current power grid. The current transformer with wide measurement range, quick transmission and transformation characteristic and low delay time can measure the rated parameters and fault parameters of the system in a wide range, has relatively accurate measurement precision and relatively low delay characteristic, and can accurately measure the process of the traveling wave after the fault occurs.
At present, certain technical difficulties exist in carrying out amplitude-frequency characteristic and phase-frequency characteristic tests of the direct current transformer. One of the major technical difficulties is the selection of a reference current standard for the wide frequency band required by the test. The primary current transferred by the dc current transformer is actually a composite current of unipolar dc current and ripple current, and the frequency response range thereof starts from dc. The general reference broadband current transformer still belongs to the iron core coil of the electromagnetic induction principle, and its frequency range does not cover direct current, so it is generally used for the frequency characteristic test verification of current transformer for alternating current engineering. In the frequency characteristic test of the current transformer for the direct current engineering, a specially designed low-inductance shunt is used as a reference standard at the present stage, and the working frequency range of the current transformer can reach from direct current to several kHz. However, at increasing test current amplitudes and frequencies, at high current amplitudes and higher frequencies, the inherent residual inductance of the nH stage causes the voltage drop and phase of the shunt to shift. Therefore, the reference shunt needs to be compensated to improve its amplitude-frequency characteristic and phase-frequency characteristic.
Disclosure of Invention
The invention provides a method for improving the self frequency characteristic of a reference shunt for a frequency characteristic test of a direct current transformer. The frequency characteristic of the reference shunt is improved within a pass band range so as to be used as a reference standard device for a frequency characteristic test of a direct current transformer.
In order to solve the technical problems, the technical scheme provided by the invention is as follows: a frequency characteristic compensation method of a shunt for reference standard is characterized in that a compensation circuit is connected in parallel at two ends of a resistor body of the shunt, and the compensation circuit comprises a compensation capacitor and a compensation resistor which are connected in series; the resistor body of the shunt comprises a shunt residual inductor, the shunt residual inductor enables the voltage drop and the phase of the shunt to shift, the shunt residual inductor enables the amplitude-frequency characteristic and the phase-frequency characteristic of the shunt to be degraded, the compensation capacitor and the compensation resistor compensate the shunt residual inductor, and the compensation resistance value of the compensation circuit is adjusted, so that the compensated shunt is in a weak damping state within a pass band range.
The scheme is further improved in that: the compensation resistor comprises a fixed value compensation resistor and an adjustable compensation resistor.
The invention provides a frequency characteristic compensation method of a reference standard shunt, which adds a fixed resistor for compensation, an adjustable resistor for compensation and a capacitor for compensation at two ends of a voltage terminal of a low-resistance resistor of the shunt. The capacitance reactance of the compensation capacitor compensates the inductance reactance of the residual inductance of the shunt. The fixed resistor for compensation, the adjustable resistor for compensation and the capacitor for compensation form a series resistance-capacitance circuit. The time constant of the resistance-capacitance series circuit can be changed by adjusting the resistance value of the adjustable resistor for compensation, and the compensation effect of the frequency special effect of the shunt is accurately adjusted, so that the compensated shunt is in a weak damping state within the passband range. The amplitude-frequency characteristic and the phase-frequency characteristic of the current divider can be greatly improved in the passband range.
Drawings
The invention is further described below with reference to the accompanying drawings.
Fig. 1 is a schematic diagram of a typical diverter.
Fig. 2 is an equivalent circuit diagram of a typical shunt.
Fig. 3 is an equivalent circuit diagram after frequency effect compensation of the shunt.
Fig. 4 is a graph of amplitude-frequency characteristics before compensation.
Fig. 5 is a diagram of the amplitude-frequency characteristic after compensation.
Fig. 6 is a compensated front phase frequency characteristic diagram.
Fig. 7 is a diagram of the compensated phase frequency characteristic.
The numbers in the figures are as follows: 1-a shunt current terminal, 2-a shunt current terminal, 3-a shunt voltage terminal, 4-a shunt voltage terminal, 5-a low-resistance resistor, 6-a shunt distributed capacitance, 7-a shunt residual inductance, 8-a shunt current lead residual inductance, 9-a fixed resistor for compensation, 10-an adjustable resistor for compensation, and 11-a capacitor for compensation.
Detailed Description
Examples
The frequency characteristic compensation method of the reference standard shunt provided by the present embodiment is applied to the typical shunt shown in fig. 1, and the shunt body structure is the low-resistance resistor 5. The current to be measured flows into and out of the shunt via shunt current terminal 1 and shunt current terminal 2. A voltage drop is generated across the low-resistance resistor 5 of the shunt, proportional to the current to be measured, which voltage drop is output from the shunt voltage terminal 3 and the shunt voltage terminal 4.
Fig. 2 shows an equivalent circuit diagram of a typical shunt. The distribution parameters of the current divider also comprise a current divider distribution capacitor 6, a current divider residual inductor 7 and a current divider current lead residual inductor 8. The shunt distribution capacitance 6 and the shunt residual inductance 7 have an effect on the frequency characteristic of the shunt. The shunt distribution capacitor 6 is directly related to the shunt structure, and the capacitance value thereof is generally in the order of several pF, and the influence on the frequency characteristic of the shunt can be ignored under the normal condition. The shunt residual inductance 7 is generally on the order of several nH to several tens uH, depending on the length, cross-sectional area, and shape of the resistor of the shunt. Under the action of high-frequency current, its inductive reactance value is equal to the product of inductance value and current angular frequency. The influence of the shunt residual inductance 7 on the frequency characteristics of the shunt appears above kHz for current frequencies.
As shown in fig. 3, in this embodiment, a fixed compensation resistor 9, an adjustable compensation resistor 10, and a capacitor 11 are added in series between the resistors of the shunt. The compensated output voltage signal is the voltage drop across the compensation capacitor 11. According to the calculation formula provided by the invention, the appropriate resistance value of the fixed resistor 9 for compensation is selected, the resistance value of the adjustable resistor 10 for compensation is adjusted, the time constant of the compensation circuit can be changed, and the RC parameter of the compensation circuit compensates the RL parameter formed by the shunt resistor 5 and the shunt residual inductance 7, so that the compensated shunt is in a weak damping state in the pass band range. The frequency characteristic compensation of the shunt is accurately adjusted, so that the amplitude-frequency characteristic and the phase-frequency characteristic of the shunt can be greatly improved within the passband range.
In this embodiment, the frequency characteristic compensation method of the shunt is as follows:
(1) and determining the direct current resistance value of the shunt to be compensated by using a low resistance meter. The wideband RLC bridge is used to determine the residual inductance value of the shunt to be compensated.
(2) Referring to the compensation circuit of fig. 3, the resistive and capacitive element parameters of the RC compensation circuit are calculated.
(3) The compensation circuit is calculated according to the following formula (1), formula (2) and formula (3). The amplitude-frequency characteristic of the compensation effect is determined by equation (1), and the phase-frequency characteristic of the compensation effect is determined by equation (2).
Formula (1):
；
formula (2):
；
formula (3):
；
wherein:R 0 the total resistance value of the fixed resistor 9 for compensation and the adjustable resistor 10 for compensation,R 1 the resistance value of the shunt low-resistance resistor 5,L the inductance value of the shunt residual inductance 7,C -the capacitance value of the compensating capacitor 11.
The present embodiment provides an example for frequency characteristic compensation of a 0.01 Ω coaxial splitter. The distribution parameters for the 0.01 Ω coaxial splitter example were actually tested as follows: the inductance of the shunt residual inductor 7 is about 17nF, and its impedance angle is greatly changed below 10kHz, particularly in the phase frequency characteristic. A compensating resistor-capacitor series circuit is added between the shunt voltage terminal 3 and the shunt voltage terminal 4 of the shunt. Wherein: the resistance value of the fixed resistor 9 for compensation is 10 ohms, the resistance value of the adjustable resistor 10 for adjustment compensation is 7 ohms, the total resistance value for compensation is 17 ohms, and the capacitance value of the capacitor 11 for compensation is 100 nF.
The amplitude-frequency characteristic before compensation is shown in fig. 4, and the amplitude-frequency characteristic after compensation is shown in fig. 5. The frequency characteristic of the phase before compensation is shown in fig. 6, and the frequency characteristic of the phase after compensation is shown in fig. 7.
The amplitude-frequency characteristic curve and the phase-frequency characteristic curve of the compensated 0.01 omega coaxial shunt are flatter in the frequency range of 100 kHz.
The present invention is not limited to the above embodiments, and any technical solutions formed by equivalent substitutions fall within the scope of the claims of the present invention.
Claims (2)
1. A frequency characteristic compensation method of a reference standard shunt is characterized in that: two ends of a resistor body of the shunt are connected with a compensation circuit in parallel, and the compensation circuit comprises a compensation capacitor and a compensation resistor which are connected in series; the resistor body of the shunt comprises a shunt residual inductor, the shunt residual inductor enables the voltage drop and the phase of the shunt to shift, the shunt residual inductor enables the amplitude-frequency characteristic and the phase-frequency characteristic of the shunt to be degraded, the compensation capacitor and the compensation resistor compensate the shunt residual inductor, and the compensation resistance value of the compensation circuit is adjusted, so that the compensated shunt is in a weak damping state within a pass band range.
2. The method of compensating for frequency characteristics of a reference standard shunt according to claim 1, wherein: the compensation resistor comprises a fixed value compensation resistor and an adjustable compensation resistor.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010887176.9A CN114124016A (en) | 2020-08-28 | 2020-08-28 | A frequency characteristic compensation method of shunt for reference standard |
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07212641A (en) * | 1994-01-20 | 1995-08-11 | Fujitsu General Ltd | Cable loss compensation circuit |
| JP2008306562A (en) * | 2007-06-08 | 2008-12-18 | Asahi Kasei Electronics Co Ltd | Operation amplifier |
| CN103792409A (en) * | 2014-01-18 | 2014-05-14 | 宁波海得工业控制系统有限公司 | Measuring circuit for quickly-changed high currents |
| TW201541091A (en) * | 2014-04-23 | 2015-11-01 | Lin Xin Hui | Low-temperature drift shunt and resistance drift compensation method thereof |
| CN106291163A (en) * | 2016-07-21 | 2017-01-04 | 广东电网有限责任公司电力科学研究院 | The bandwidth determining method of a kind of divertor and system |
| US20170012606A1 (en) * | 2015-07-10 | 2017-01-12 | Qorvo Us, Inc. | Compensated programmable rf attenuator |
| CN212258918U (en) * | 2020-08-28 | 2020-12-29 | 国网江苏省电力有限公司南京供电分公司 | Frequency characteristic compensation circuit of shunt for reference standard |
-
2020
- 2020-08-28 CN CN202010887176.9A patent/CN114124016A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07212641A (en) * | 1994-01-20 | 1995-08-11 | Fujitsu General Ltd | Cable loss compensation circuit |
| JP2008306562A (en) * | 2007-06-08 | 2008-12-18 | Asahi Kasei Electronics Co Ltd | Operation amplifier |
| CN103792409A (en) * | 2014-01-18 | 2014-05-14 | 宁波海得工业控制系统有限公司 | Measuring circuit for quickly-changed high currents |
| TW201541091A (en) * | 2014-04-23 | 2015-11-01 | Lin Xin Hui | Low-temperature drift shunt and resistance drift compensation method thereof |
| US20170012606A1 (en) * | 2015-07-10 | 2017-01-12 | Qorvo Us, Inc. | Compensated programmable rf attenuator |
| CN106291163A (en) * | 2016-07-21 | 2017-01-04 | 广东电网有限责任公司电力科学研究院 | The bandwidth determining method of a kind of divertor and system |
| CN212258918U (en) * | 2020-08-28 | 2020-12-29 | 国网江苏省电力有限公司南京供电分公司 | Frequency characteristic compensation circuit of shunt for reference standard |
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