CN111693753A - Novel direct current measuring device - Google Patents
Novel direct current measuring device Download PDFInfo
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- CN111693753A CN111693753A CN201911199269.6A CN201911199269A CN111693753A CN 111693753 A CN111693753 A CN 111693753A CN 201911199269 A CN201911199269 A CN 201911199269A CN 111693753 A CN111693753 A CN 111693753A
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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
- G01R19/0007—Frequency selective voltage or current level measuring
- G01R19/0015—Frequency selective voltage or current level measuring separating AC and DC
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
- G01R1/30—Structural combination of electric measuring instruments with basic electronic circuits, e.g. with amplifier
Abstract
The invention discloses a novel direct current measuring device. The invention belongs to the technical field of direct current measurement of direct current electric energy metering technology, and aims to solve the problem that the existing direct current sensor is insufficient in direct current electric energy metering, when a larger alternating current component is superposed in direct current, the measuring result of the existing direct current sensor can cause the phenomenon of 'more metering' or 'less metering' of electric energy. A novel direct current measuring device comprises an electromagnet core for direct current measurement, an electromagnet core for alternating current measurement, an input current measuring coil, an excitation current, a direct current detecting coil, a feedback coil, an alternating current detecting coil, an amplifying circuit, an average value calculating circuit, an integrating circuit, a power amplifying circuit, a filter circuit, direct current output and alternating current output.
Description
Technical Field
The invention relates to the field of direct current measurement of a direct current electric energy metering technology, in particular to a novel direct current measuring device.
Background
In recent years, DC transmission and distribution are increasingly applied to power grids, different loads are connected in parallel on a DC transmission bus, for example, a motor or other AC devices are supplied with power through DC/AC, while AC loads often require reactive power, and these reactive power requirements through a DC/AC converter result in that an AC component is superimposed on an input current at a DC terminal, which is generated by the reactive power requirements at an AC terminal of a DCAC converter, and in some occasions (such as a subway locomotive), the AC component superimposed on the DC current is large and has low frequency, and is difficult to filter by a filtering means. With the wide application of the direct current power grid, the direct current electric energy meter is used as an important basis for direct electric energy metering, and due to the phenomenon, the traditional direct current sensor cannot decompose a direct current component and an alternating current component in current, and under the condition that the alternating current component is large, the phenomenon of 'more metering' or 'less metering' of electric energy occurs when a current signal acquired by the traditional direct current sensor is transmitted to the end of the direct current electric energy meter.
The traditional direct current sensor comprises a current divider, a Hall sensor, a magnetic modulation sensor and the like, current signals measured by the current divider and the Hall sensor comprise direct current components and alternating current components, the alternating current components are added with the direct current components in an effective value mode in the measurement of a direct current electric energy meter, then electric energy metering is carried out, and under the condition that reactive current exists in a load, the electric energy metering is caused to be 'more metered'; the measurement result of the magnetic modulation direct current sensor only contains a direct current component, a direct current voltage of a direct current power grid is superposed with a certain alternating current component, and the part of an alternating current component in a current signal, which has the same frequency as the alternating current component in a voltage signal, belongs to active power and needs to be measured.
The direct current electric energy meter is used as an important instrument for metering and settlement in a future direct current power grid, the improvement of the electric energy metering accuracy is very necessary, and the direct current component and the alternating current component in the direct current are separated according to the characteristics of the direct current in the direct current power grid, and then the related processing is an effective means for improving the direct current electric energy metering.
Disclosure of Invention
The invention provides a novel direct current measuring device, which aims to solve the problem that the existing direct current sensor is insufficient in direct current electric energy measurement, and when a larger alternating current component is superposed in direct current, the measuring result of the existing direct current sensor can cause the phenomenon of more measurement or less measurement of electric energy.
The technical problem is solved by the following technical scheme:
a novel direct current measuring device comprises an electromagnet core for direct current measurement, an electromagnet core for alternating current measurement, an input current measuring coil, an excitation current, a direct current detecting coil, a feedback coil, an alternating current detecting coil, an amplifying circuit, an average value calculating circuit, an integrating circuit, a power amplifying circuit, a filter circuit, direct current output and alternating current output. The device is characterized in that the measured direct current is respectively wound on a direct current measuring electromagnet core and an alternating current measuring electromagnet core through an input current measuring coil, the current directions of the two iron cores are the same, the turns are different, the number of turns of the wound direct current measuring electromagnet core is greater than that of the direct current measuring electromagnet core, and the turn ratio is k; the exciting current generates alternating exciting current, the current frequency of the alternating exciting current is more than 2kHz, and the alternating exciting current is wound on the electromagnet core for direct current measurement through a coil; the direct current detection coil is wound on the electromagnet core for direct current measurement; the feedback coil is respectively wound on the electromagnet core for direct current measurement and the electromagnet core for alternating current measurement, the current directions of the two iron cores are the same, the turns are different, the number of turns of the feedback coil wound on the electromagnet core for alternating current measurement is larger than that of the electromagnet core for direct current measurement, and the turn ratio is k; the alternating current detection coil is wound on the electromagnet core for alternating current measurement.
A novel direct current measuring device is characterized in that the direct current superposed with an alternating current component is decomposed and measured as follows:
the exciting current module generates alternating current, and alternating current magnetic flux phi 1 is generated in the direct current measuring electromagnet core through the coil, so that the magnetic flux generated by the exciting current in the direct current measuring electromagnet core is close to a saturation point.
When the detected direct current is zero, the direct current detection coil generates symmetrical alternating current induced potential under the action of the alternating current excitation magnetic flux phi 1, the symmetrical alternating current induced potential is amplified by the amplifying circuit and then passes through the average value calculating circuit, and the induced potential is vertically symmetrical and the average value in the period is zero, so that the induced potential generated by the direct current detection coil is output to be zero after passing through the average value calculating circuit, the integrating circuit and the direct current output.
When the direct current to be measured is not zero, the direct current phi 2 is respectively generated in the electromagnet core for direct current measurement and the electromagnet core for alternating current measurement through the measuring coil of the input circuit, and the alternating current phi 1 generated by the electromagnet core for direct current measurement under the action of the exciting current is already at a saturation point, the magnetic flux in the electromagnet core for direct current measurement enters a nonlinear saturation area under the combined action of the two magnetic fluxes, the direction of the direct current is set to be the same as the positive direction of the alternating current generated by the exciting current, the upper half wave of the synthesized magnetic flux enters nonlinear saturation, at the moment, the direct current detecting coil generates asymmetric distorted alternating current induced potential under the action of the synthesized magnetic flux, the distorted alternating current induced potential is represented as that the upper half wave is smaller than the lower half wave, the induced potential outputs an average value after passing through the amplifying circuit and the average value calculating circuit, then passes through the integrating circuit, and then the direct current phi 3 with the direction opposite to the direct current, when phi 2 is not equal to phi 3, the DC detection coil still generates asymmetric AC induction potential under the action of the synthesized magnetic flux, the output is not zero after passing through the average value calculation circuit, the integral output is continuously increased under the action of the integral circuit, so that the current of the feedback coil is continuously increased, the DC magnetic flux phi 3 is also continuously increased, until phi 2 is equal to phi 3, the DC magnetic flux in the DC measurement electromagnet core is counteracted, the DC detection coil generates symmetric AC induction potential under the action of the AC magnetic flux phi 1, at the moment, the output is 0 through the average value calculation circuit, the output of the integral circuit is not increased, and the DC output module outputs the measured DC current, thereby realizing the DC current measurement.
When the measured direct current does not contain alternating current components, the direct current phi 2 in the electromagnet core for alternating current measurement and the direct current phi 3 generated by the feedback coil are mutually offset, the alternating current detection coil does not have induced electromotive force, and the output is zero.
When the measured direct current contains alternating current components, under the action of the average value calculating circuit, the integrating circuit, the power amplifying circuit and the feedback coil, direct current magnetic flux phi 2 in the electromagnet core for alternating current measurement and direct current magnetic flux phi 3 generated by the feedback coil are mutually counteracted, at the moment, alternating magnetic flux phi 4 is generated in the electromagnet core for alternating current measurement by alternating current components of the measured current, as the number of turns of the input current measuring coil in the electromagnet core for alternating current measurement is more, the magnetomotive force generated by the alternating current components has obvious action, at the moment, the alternating current detecting coil generates induced electromotive force, and the measurement of the alternating current components of the measured current is realized through filtering and alternating current output.
The invention can achieve the following effects:
the invention separates the direct current superposed with the alternating current component, and respectively outputs the direct current component and the alternating current component, thereby providing various choices for current acquisition of the direct current electric energy meter, and further improving the accuracy of direct current electric energy metering.
Drawings
Fig. 1 is a schematic block diagram of a novel dc current measuring device according to the present invention.
Detailed Description
The invention is further described with reference to the following figures and examples.
In an embodiment, a novel dc current measuring device, as shown in fig. 1, includes a magnetic core 1 for dc measurement, a magnetic core 2 for ac measurement, an input current measuring coil 3, an excitation current 4, a dc detection coil 5, a feedback coil 6, an ac detection coil 7, an amplifying circuit module 8, an average value calculating circuit module 9, an integrating circuit module 10, a power amplifying circuit module 11, a filter circuit module 12, a dc output module 13, and an ac output module 14. The direct current to be measured is respectively wound on the direct current measuring electromagnet core 1 and the alternating current measuring electromagnet core 2 through the input current measuring coil 3, the current directions of the two iron cores are the same, the turns are different, the number of turns of the wound direct current measuring electromagnet core 2 is larger than that of the direct current measuring electromagnet core 1, and the turn ratio is k; the exciting current 4 generates alternating exciting current, the current frequency of the alternating exciting current is more than 2kHz, and the alternating exciting current is wound on the electromagnet core 1 for direct current measurement through a coil; the direct current detection coil 5 is wound on the direct current measurement electromagnet core 1; the feedback coil 6 is respectively wound on the direct current measuring electromagnet core 1 and the alternating current measuring electromagnet core 2, the current directions of the two iron cores are the same, the turns are different, the number of turns of the wound alternating current measuring electromagnet core 2 is greater than that of the direct current measuring electromagnet core 1, and the turn ratio is k; the ac detection coil 7 is wound around the ac measuring electromagnet core 2.
A novel direct current measuring device is characterized in that the direct current superposed with an alternating current component is decomposed and measured as follows:
the excitation current module 4 generates alternating current, and alternating current magnetic flux phi 1 is generated on the direct current measuring electromagnet core 1 through the coil, so that the magnetic flux generated by the excitation current on the direct current measuring electromagnet core 1 is close to a saturation point.
When the detected direct current is zero, the direct current detection coil 5 generates symmetrical alternating current induced potential under the action of the alternating current excitation magnetic flux phi 1, the symmetrical alternating current induced potential is amplified by the amplifying circuit 8 and then passes through the average value calculating circuit 9, and the induced potential is symmetrical up and down and the average value in the period is zero, so that the induced potential generated by the direct current detection coil 5 passes through the average value calculating circuit 9, the integrating circuit 10 and the direct current output 13 and then is output to be zero.
When the measured direct current is not zero, the measured direct current generates direct current phi 2 on a direct current measuring electromagnet core 1 and an alternating current measuring electromagnet core 2 through an input circuit measuring coil 3, and the alternating current phi 1 generated by the direct current measuring electromagnet core 1 under the action of exciting current 4 is already at a saturation point, the combined action of the two magnetic fluxes enables the magnetic flux in the direct current measuring electromagnet core 1 to enter a nonlinear saturation area, the direction of the direct current magnetic flux is the same as the positive direction of the alternating current generated by the exciting current, so that the upper half wave of the synthesized magnetic flux enters nonlinear saturation, at the moment, an asymmetric distorted alternating current induced potential is generated by a direct current-direct current synthesized magnetic flux through a direct current detection coil 5, the distorted alternating current induced potential is represented as that the upper half wave is smaller than the lower half wave, the induced potential outputs an average value after passing through an amplifying circuit 8 and an average value calculating circuit 9, passes through an integrating circuit 10, then passes through a power amplifying circuit 11 and then generates an When phi 2 is not equal to phi 3, the direct current detection coil 5 still generates asymmetric alternating current induced potential under the action of the synthesized magnetic flux, the output is not zero after passing through the average value calculation circuit 9, the integral output is continuously increased under the action of the integration circuit 10, so that the current of the feedback coil is continuously increased, the direct current flux phi 3 is also continuously increased, when phi 2 is equal to phi 3, the direct current magnetic flux in the electromagnet core 1 for direct current measurement is counteracted, the direct current detection coil 5 generates symmetric alternating current induced potential under the action of the alternating current flux phi 1, the output is 0 through the average value calculation circuit 9 at the moment, the output of the integration circuit 10 is not increased, the direct current output 13 outputs the measured direct current, and the direct current measurement is realized.
When the measured direct current does not contain an alternating current component, the direct current magnetic flux phi 2 in the electromagnet core 2 for alternating current measurement and the direct current magnetic flux phi 3 generated by the feedback coil are mutually offset, and the output of the alternating current detection coil 7 is zero.
When the measured direct current contains an alternating current component, under the action of the average value calculating circuit 9, the integrating circuit 10, the power amplifying circuit 11 and the feedback coil 6, the direct current flux phi 2 in the electromagnet core 2 for alternating current measurement and the direct current flux phi 3 generated by the feedback coil are mutually counteracted, at the moment, the alternating current component of the alternating current to be measured can generate an alternating magnetic flux phi 4 in the electromagnet core 2 for alternating current measurement, because the number of turns of the input current measuring coil 3 in the electromagnet core 2 for alternating current measurement is more, the magnetomotive force generated by the alternating current component has obvious effect, at the moment, the alternating current detecting coil 7 generates induced electromotive force, and the measurement of the alternating current component of the measured current is realized through the filter circuit 12 and the alternating current output 14.
Claims (2)
1. A novel direct current measuring device comprises an electromagnet core for direct current measurement, an electromagnet core for alternating current measurement, an input current measuring coil, an excitation current, a direct current detecting coil, a feedback coil, an alternating current detecting coil, an amplifying circuit, an average value calculating circuit, an integrating circuit, a power amplifying circuit, a filter circuit, direct current output and alternating current output. The device is characterized in that the measured direct current is respectively wound on a direct current measuring electromagnet core and an alternating current measuring electromagnet core through an input current measuring coil, the current directions of the two iron cores are the same, the turns are different, the number of turns of the wound direct current measuring electromagnet core is greater than that of the direct current measuring electromagnet core, and the turn ratio is k; the exciting current generates alternating exciting current, the current frequency of the alternating exciting current is more than 2kHz, and the alternating exciting current is wound on the electromagnet core for direct current measurement through a coil; the direct current detection coil is wound on the electromagnet core for direct current measurement; the feedback coil is respectively wound on the electromagnet core for direct current measurement and the electromagnet core for alternating current measurement, the current directions of the two iron cores are the same, the turns are different, the number of turns of the feedback coil wound on the electromagnet core for alternating current measurement is larger than that of the electromagnet core for direct current measurement, and the turn ratio is k; the alternating current detection coil is wound on the electromagnet core for alternating current measurement.
2. A novel dc current measuring device suitable for use in claim 1, wherein the dc current with the superimposed ac component is decomposed and measured as follows:
the exciting current module generates alternating current, and alternating current magnetic flux phi 1 is generated in the direct current measuring electromagnet core through the coil, so that the magnetic flux generated by the exciting current in the direct current measuring electromagnet core is close to a saturation point;
when the detected direct current is zero, the direct current detection coil generates symmetrical alternating current induced potential under the action of the alternating current excitation magnetic flux phi 1, the symmetrical alternating current induced potential is amplified by the amplifying circuit and then passes through the average value calculating circuit, and the induced potential is symmetrical up and down and the average value in the period is zero, so that the induced potential generated by the direct current detection coil is output to be zero after passing through the average value calculating circuit, the integrating circuit and the direct current output;
when the direct current to be measured is not zero, the direct current phi 2 is respectively generated in the electromagnet core for direct current measurement and the electromagnet core for alternating current measurement through the measuring coil of the input circuit, and the alternating current phi 1 generated by the electromagnet core for direct current measurement under the action of the exciting current is already at a saturation point, the magnetic flux in the electromagnet core for direct current measurement enters a nonlinear saturation area under the combined action of the two magnetic fluxes, the direction of the direct current is set to be the same as the positive direction of the alternating current generated by the exciting current, the upper half wave of the synthesized magnetic flux enters nonlinear saturation, at the moment, the direct current detecting coil generates asymmetric distorted alternating current induced potential under the action of the synthesized magnetic flux, the distorted alternating current induced potential is represented as that the upper half wave is smaller than the lower half wave, the induced potential outputs an average value after passing through the amplifying circuit and the average value calculating circuit, then passes through the integrating circuit, and then the direct current phi 3 with the direction opposite to the direct current, when phi 2 is not equal to phi 3, the direct current detection coil still generates asymmetric alternating current induced potential under the action of the synthesized magnetic flux, the output is not zero after passing through the average value calculation circuit, the integral output is continuously increased under the action of the integral circuit, so that the current of the feedback coil is continuously increased, the direct current magnetic flux phi 3 is also continuously increased, until phi 2 is equal to phi 3, the direct current magnetic flux in the electromagnet core for direct current measurement is counteracted, the direct current detection coil generates symmetric alternating current induced potential under the action of the alternating current magnetic flux phi 1, at the moment, the output is 0 through the average value calculation circuit, the output of the integral circuit is not increased, the direct current output module outputs the measured direct current, and the direct current measurement is realized;
when the measured direct current does not contain an alternating current component, the direct current magnetic flux phi 2 in the electromagnet core for alternating current measurement and the direct current magnetic flux phi 3 generated by the feedback coil are mutually offset, the alternating current detection coil does not induce electromotive force, and the output is zero;
when the measured direct current contains alternating current components, under the action of the average value calculating circuit, the integrating circuit, the power amplifying circuit and the feedback coil, direct current magnetic flux phi 2 in the electromagnet core for alternating current measurement and direct current magnetic flux phi 3 generated by the feedback coil are mutually counteracted, at the moment, alternating magnetic flux phi 4 is generated in the electromagnet core for alternating current measurement by alternating current components of the measured current, as the number of turns of the input current measuring coil in the electromagnet core for alternating current measurement is more, the magnetomotive force generated by the alternating current components has obvious action, at the moment, the alternating current detecting coil generates induced electromotive force, and the measurement of the alternating current components of the measured current is realized through filtering and alternating current output.
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Cited By (2)
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| CN114994388A (en) * | 2022-05-25 | 2022-09-02 | 北京中联太信科技有限公司 | Method and system for magnetic superconducting micro-direct current detection and analysis |
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