CN111175557A - High-precision optical fiber current transformer - Google Patents
High-precision optical fiber current transformer Download PDFInfo
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- CN111175557A CN111175557A CN201811342254.6A CN201811342254A CN111175557A CN 111175557 A CN111175557 A CN 111175557A CN 201811342254 A CN201811342254 A CN 201811342254A CN 111175557 A CN111175557 A CN 111175557A
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- optical fiber
- current transformer
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- sensing ring
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/24—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices
- G01R15/245—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using magneto-optical modulators, e.g. based on the Faraday or Cotton-Mouton effect
- G01R15/246—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using magneto-optical modulators, e.g. based on the Faraday or Cotton-Mouton effect based on the Faraday, i.e. linear magneto-optic, effect
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/24—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices
- G01R15/247—Details of the circuitry or construction of devices covered by G01R15/241 - G01R15/246
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- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
Abstract
The invention discloses a high-precision optical fiber current transformer which comprises an acquisition unit, a polarization maintaining optical cable, a sensing ring and a wire hoop, wherein the acquisition unit is connected with the sensing ring through the polarization maintaining optical cable, and the sensing ring is sleeved with the wire hoop. The invention has the advantages that 1) the invention overcomes the technical current situation that the measurement precision of the single bus structure of the optical fiber current transformer is limited in the past, innovatively provides the concept of the comprehensive equivalent turn number of the optical fiber current transformer, and the parameter can be designed according to the rated current and the precision requirement; 2) according to the invention, the multi-turn wire winding structure is arranged outside the sensing ring, so that the comprehensive equivalent turn number of the optical fiber current transformer can be improved by jointly increasing the turn number of the wire and the turn number of the optical fiber, the test precision is greatly improved, and the requirement of measuring ampere-level or even more tiny alternating current and direct current under special application conditions such as an unbalanced capacitor tower of a direct current converter station can be met.
Description
Technical Field
The invention belongs to an optical fiber current transformer, and particularly relates to a high-precision optical fiber current transformer which can be used for measuring AC/DC current of ampere level or even smaller.
Background
A current transformer is a basic device for measuring current in an electric power system, and has common applications in protection, measurement and metering. The traditional current transformer is an electromagnetic transformer based on electromagnetic induction, which has been applied for hundreds of years and makes an important contribution to the development of an electric power system, but with the development of a modern smart grid, the voltage grade of the electric power system is improved, and a high-voltage and extra-high-voltage direct-current transmission and transformation system is developed, the defects of the electromagnetic transformer are gradually exposed, such as the existence of a magnetic saturation phenomenon, the low response speed to a fault, the incapability of simultaneously measuring alternating current and direct current and harmonic signals, and the like. In recent years, with the continuous progress of optical fiber and optical device technologies, optical fiber current transformers have been developed rapidly. The novel mutual inductor is based on the magneto-optical Faraday effect in optical fibers, simultaneously, the digital closed loop detection technology in an optical fiber gyroscope is applied, a plurality of defects of the traditional current mutual inductor can be overcome, and the novel mutual inductor has the advantages of natural excellent insulating property, large dynamic range and the like, is widely concerned by the power industry, and is applied in a certain range.
In the conventional application of the power industry, the rated current to be measured is usually relatively large, often on the order of hundreds of amperes or thousands of amperes, but in some special occasions, such as current monitoring points among unbalanced capacitor towers in a direct current converter station, etc., the current of the order of amperes or even less needs to be measured, and at this time, the required precision is difficult to achieve by a general optical fiber current transformer. In order to solve the problem of current measurement accuracy under low current, a high-accuracy optical fiber current transformer needs to be developed.
The patent "high-precision all-fiber current transformer" (application number: CN201010601079.5) discloses a high-precision transformer, which realizes the phase closed-loop control of the fiber current transformer through a signal modulation and demodulation unit and a phase modulator to improve the signal-to-noise ratio of the system. The patent "a high accuracy high reliability all-fiber current transformer" (application number: CN201410125918.9) discloses a high accuracy high reliability all-fiber current transformer, which converts two beams of light into electrical signals and sends them into a signal processing unit by using the correlation of the output light of two output ends of a second single mode coupler through the digital signal processing unit, and realizes the suppression of the light source intensity noise by using the digital circuit subtraction method, so as to improve the measurement accuracy of the system. However, the two methods provided by the above patents cannot make the fiber current transformer achieve the accuracy of measuring ampere-level or even lower current accurately.
The phase difference delta phi generated by measuring current by the sensing ring of the optical fiber current transformer meets the following formula:
Δφ＝4VN1N2I
where V is the verdet constant of the fiber, N1 is the number of turns of the current wire through the fiber sensing loop, N2 is the number of turns of the sensing fiber in the fiber sensing loop, N1 × N2 can be considered as the integrated equivalent number of turns of the transformer, and I is the magnitude of the primary current. Under the condition of the same circuit resolving accuracy, the overall measurement accuracy of the optical fiber current transformer depends on delta phi, namely the larger the phase difference generated by the same current is, the higher the measurement accuracy of the transformer is. In the past, optical fiber current transformers are designed to enable a single primary lead to directly penetrate through a sensing ring, namely N1 is equal to 1, and considering factors such as structural space, comprehensive performance and product cost, the improvement of N2 is limited, so that the transformers cannot accurately measure ampere-level or even tiny current.
Disclosure of Invention
The invention aims to provide a high-precision optical fiber current transformer, which increases the number of turns of a primary current lead to improve the comprehensive equivalent turns of the optical fiber current transformer and further greatly improve the test precision by a multi-turn lead winding structure, and meets the requirement of ampere-level or even more tiny alternating current and direct current measurement under special application conditions such as an unbalanced capacitor tower of a direct current converter station.
The invention is realized in such a way that the high-precision optical fiber current transformer comprises an acquisition unit, a polarization maintaining optical cable, a sensing ring and a lead hoop, wherein the acquisition unit is connected with the sensing ring through the polarization maintaining optical cable, and the lead hoop is sleeved on the sensing ring.
The sensing ring comprises a quarter-wave plate, a sensing optical fiber, a reflector, a polarization maintaining optical cable, a base, an optical fiber framework and an upper cover.
The sensing ring, wherein, polarization maintaining optical cable gets into sensing ring after and 45 degrees counter shaft connection with quarter wave plate, is sensing optic fibre behind the quarter wave plate, sensing optic fibre winding is on the optic fibre skeleton, the speculum is at sensing optic fibre end, leans on side by side with the quarter wave plate together, optic fibre skeleton, quarter wave plate and speculum are fixed on the base, the upper cover seals the base.
The sensing optical fiber is wound on the optical fiber framework and is fixed by glue,
the quarter-wave plate is fixed by glue.
The reflector is fixed by glue.
And a wire hoop is fixed outside the sensing ring.
The wire hoop is divided into an upper part and a lower part which are fixed on the sensing ring together.
And the wire hoop is wound with wires.
The invention has the advantages that 1) the invention overcomes the technical current situation that the measurement precision of the single bus structure of the optical fiber current transformer is limited in the past, innovatively provides the concept of the comprehensive equivalent turn number of the optical fiber current transformer, and the parameter can be designed according to the rated current and the precision requirement; 2) according to the invention, the multi-turn wire winding structure is arranged outside the sensing ring, so that the comprehensive equivalent turn number of the optical fiber current transformer can be improved by jointly increasing the turn number of the wire and the turn number of the optical fiber, the test precision is greatly improved, and the requirement of measuring ampere-level or even more tiny alternating current and direct current under special application conditions such as an unbalanced capacitor tower of a direct current converter station can be met.
Drawings
FIG. 1 is a schematic diagram of a high-precision fiber optic current transformer according to the present invention;
FIG. 2 is a schematic view of a sensing loop;
3 FIG. 3 3 3 is 3 a 3 sectional 3 view 3 taken 3 along 3 line 3 A 3- 3 A 3 of 3 FIG. 3 2 3; 3
FIG. 4 is a schematic view of a sensing loop and a wire anchor ear;
fig. 5 is a schematic view of a wire hoop.
In the figure: the optical fiber sensing device comprises a collecting unit 1, a polarization maintaining optical cable 2, a sensing ring 3, a wire hoop 4, a quarter wave plate 5, a reflector 6, an optical fiber framework 7, a sensing optical fiber 8, a base 9, an upper cover 10, glue 11, a wire input end 12, a wire output end 13 and a wire 14.
Detailed Description
The invention is described in detail below with reference to the following figures and specific embodiments:
as shown in fig. 1, the high-precision optical fiber current transformer includes an acquisition unit 1, a polarization maintaining optical cable 2, a sensing loop 3 and a wire anchor ear 4, wherein the acquisition unit 1 is connected with the sensing loop 3 through the polarization maintaining optical cable 2, and the sensing loop 3 is sleeved with the wire anchor ear 4.
The acquisition unit 1 and the polarization maintaining optical cable 2 adopt the general technology of an optical fiber current transformer, and are not described in detail herein.
As shown in fig. 2 and 3, the sensing loop 3 includes a quarter-wave plate 5, a sensing optical fiber 8, a reflector 6, a polarization maintaining optical cable 2, a base 9, an optical fiber framework 7 and an upper cover 10, the polarization maintaining optical cable 2 enters the sensing loop 3 and then is connected with a 45-degree counter shaft of the quarter-wave plate, the sensing optical fiber 8 is arranged behind the quarter-wave plate 5, the sensing optical fiber 8 is wound on the optical fiber framework 7 and is fixed by a glue 11, the reflector 6 is arranged at the tail end of the sensing optical fiber and leans against the quarter-wave plate 5 side by side, the optical fiber framework 7, the quarter-wave plate 5 and the reflector 6 are fixed on the base 9, the quarter-wave plate 5 and the reflector 6 are also fixed by the glue 11, and the base 9 is sealed by the upper cover 10 to protect the internal optical fiber.
As shown in fig. 4, a wire hoop 4 is fixed outside the sensing ring 3, as shown in fig. 5, the wire hoop 4 is divided into an upper part and a lower part, which are fixed on the sensing ring 3 together, and the wire is wound on the hoop by a machine tool or a manual method. The enameled wire or the wire with the plastic insulating layer can be selected according to the requirement, and the wire diameter of the wire is selected according to parameters such as rated current and maximum current, which is very important, and if the wire diameter is too thin, potential safety hazards are brought. And fixing the wire by using glue after the wire is wound.
The selection of the number of turns of the optical fiber of the sensing loop and the number of turns of the conducting wire on the hoop needs to be designed according to the rated current and the precision requirement. Under the existing fiber Verdet constant and the general circuit resolving precision level, the 1A rated current is measured to reach the 0.2-level precision level, and the comprehensive equivalent turn number N1 multiplied by N2 at least needs to reach more than 3000-5000. The number of the specific N1 and N2 can be designed according to the inner space of the ring and the size of the hoop. If the number of comprehensive equivalent turns of 4000 turns is to be reached, the sensing ring optical fiber is wound by 40 turns, and the lead in the hoop needs to be wound by 100 turns; if the optical fiber is wound by 50 turns, the wire needs to be wound by 80 turns. The invention relates to a high-precision optical fiber current transformer which can be used for measuring AC/DC current with ampere level or even smaller in an electric power system, and the whole structure of the high-precision optical fiber current transformer is shown in figure 1 and comprises an acquisition unit 1, a polarization maintaining optical cable 2, a sensing ring 3 and a wire hoop 4. Collection unit 1 is connected through insulating polarization maintaining optical cable 2 between the ring 3 with the sensing, sensing ring 3 mainly measures the electric current that awaits measuring, converts the magnetic field that the electric current produced into the phase difference of two bundles of coherent light in the optic fibre, polarization maintaining optical cable 2 mainly transmits light signal between collection unit 1 and sensing ring 3, collection unit 1 is inside to contain optical components and circuits, is used for producing light, solves light signal and sends current signal according to the rule.
One configuration of the sensing loop 3 is shown in fig. 2, and includes a quarter-wave plate 5, a sensing fiber 8, a reflector 6, a polarization maintaining optical cable 2, a base 9, a glue 11, a fiber framework 7, and an upper cover 10.
After entering the sensing ring 3, the polarization maintaining optical cable 2 is in 45-degree shaft connection with the quarter-wave plate 5, the deviation angle is not more than +/-2 degrees, the sensing optical fiber 8 is arranged behind the quarter-wave plate 5, the sensing optical fiber 8 is wound on the optical fiber framework 7, the winding tension is not more than 10g, the sensing optical fiber 8 is fixed through the glue 11, the reflector 6 is arranged at the tail end of the sensing optical fiber 8 and is abutted against the quarter-wave plate 5 side by side, the horizontal distance is not more than 1mm, and the longitudinal distance is not more than 5 mm. The optical fiber framework 7, the quarter-wave plate 5 and the reflector 6 are fixed on the base 9, and the quarter-wave plate 5 and the reflector 6 are also fixed by glue 11. The selection of the glue 11 needs to consider the life, reliability and stability, so that the optical fiber and the device can be stably fixed for a long time without obviously influencing the performance. The sealing structure of the base 11 and the upper cover 10 is designed according to the application environment requirements, and the base 11 is sealed by the upper cover 10 to protect the internal optical fibers and devices.
As shown in fig. 4, a wire hoop 4 is fixed outside the sensing loop 3, and the wire hoop 4 is divided into an upper part and a lower part, and is fixed on the sensing loop 3. The wire 14 is wound on the wire hoop 4 by a machine tool or manually. The type of the enameled wire or the plastic insulation layer can be selected for the conducting wire 14 according to the requirement, and the wire diameter of the conducting wire 14 is selected according to the parameters such as rated current and maximum current, which is very important, if the wire diameter is too thin, the potential safety hazard is brought, and if the wire diameter is too thick, the unnecessary cost and volume weight are increased. The wire 14 is fixed by the glue 11 after being wound, so as to ensure that the wire 14 can keep stable during long-term operation.
The selection of the number of turns of the optical fiber of the sensing loop 3 and the number of turns of the conducting wire on the conducting wire hoop 4 needs to be designed according to the rated current and the precision requirement. Under the existing fiber Verdet constant and the general circuit resolving precision level, the comprehensive equivalent turn number N (namely N1 multiplied by N2) corresponding to different rated currents and precision is shown in Table 1.
TABLE 1 COMPLEX EQUAL TURN-NUMBER COMPARATIVE REFERENCE TABLE
| Rated current (A) | Grade of accuracy | Comprehensive equivalent number of |
| 10 | 1.0 | 100～200 |
| 10 | 0.2 | 300～500 |
| 1 | 1.0 | 1000～2000 |
| 1 | 0.2 | 3000～5000 |
| 0.1 | 1.0 | 10000～20000 |
| 0.1 | 0.2 | 30000～50000 |
As can be seen from Table 1, when the rated current of 1A is measured, the accuracy level of 0.2 level is achieved, and the comprehensive equivalent turn number N1 multiplied by N2 at least needs to reach more than 3000-5000 turns. The specific numbers of N1 and N2 can be designed according to the internal space of the sensing loop 3 and the specific size of the wire hoop 4. If the number of comprehensive equivalent turns of 4000 turns is to be reached, 40 turns of optical fiber 8 are wound on the sensing ring 3, and 100 turns of lead 14 in the lead hoop 4 need to be wound; if the optical fiber 8 is wound by 50 turns, the wire 14 needs to be wound by 80 turns.
It should be noted that: the above embodiments are only intended to illustrate the technical solution of the present invention and not to limit the same, and a person of ordinary skill in the art can make modifications or equivalents to the specific embodiments of the present invention with reference to the above embodiments, and any modifications or equivalents without departing from the spirit and scope of the present invention are within the scope of the claims of the present invention.
The invention has not been described in detail in part of the common general knowledge of those skilled in the art.
Claims (9)
1. A high-precision optical fiber current transformer is characterized in that: the device comprises an acquisition unit (1), a polarization maintaining optical cable (2), a sensing ring (3) and a wire anchor ear (4), wherein the acquisition unit (1) is connected with the sensing ring (3) through the polarization maintaining optical cable (2), and the sensing ring (3) is sleeved with the wire anchor ear (4).
2. A high precision fiber optic current transformer according to claim 1 and wherein: the sensing ring (3) comprises a quarter-wave plate (5), a sensing optical fiber (8), a reflector (6), a polarization maintaining optical cable (2), a base (9), an optical fiber framework (7) and an upper cover (10).
3. A high precision fiber optic current transformer according to claim 2 and wherein: sensing ring (3), wherein, polarization maintaining optical cable (2) get into sensing ring (3) after with quarter wave plate 45 degrees counter shaft connection, be sensing fiber (8) behind quarter wave plate (5), sensing fiber (8) winding is on optic fibre skeleton (7), speculum (6) are at sensing fiber end, lean on together side by side with quarter wave plate (5), optic fibre skeleton (7), quarter wave plate (5) are fixed on base (9) with speculum (6), upper cover (10) seal base (9).
4. A high precision fiber optic current transformer according to claim 3 and wherein: the sensing optical fiber (8) is wound on the optical fiber framework (7) and is fixed through glue (11).
5. A high precision fiber optic current transformer according to claim 3 and wherein: the quarter-wave plate (5) is fixed by glue (11).
6. A high precision fiber optic current transformer according to claim 3 and wherein: the reflector (6) is fixed by glue (11).
7. A high precision fiber optic current transformer according to claim 1 and wherein: and a lead hoop (4) is fixed outside the sensing ring (3).
8. A high precision fiber optic current transformer according to claim 1 and wherein: the wire hoop (4) is divided into an upper part and a lower part which are fixed on the sensing ring (3) together.
9. A high precision fiber optic current transformer according to claim 1 and wherein: and the wire hoop (4) is wound with a wire (14).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811342254.6A CN111175557A (en) | 2018-11-13 | 2018-11-13 | High-precision optical fiber current transformer |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811342254.6A CN111175557A (en) | 2018-11-13 | 2018-11-13 | High-precision optical fiber current transformer |
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| CN111175557A true CN111175557A (en) | 2020-05-19 |
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| CN201811342254.6A Pending CN111175557A (en) | 2018-11-13 | 2018-11-13 | High-precision optical fiber current transformer |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112129986A (en) * | 2020-08-10 | 2020-12-25 | 常州博瑞电力自动化设备有限公司 | Optical current transformer for high-voltage direct-current circuit breaker |
| CN115810484A (en) * | 2022-12-27 | 2023-03-17 | 中国电力工程顾问集团中南电力设计院有限公司 | Method and device for manufacturing sensing ring of optical fiber current transformer at outlet of generator |
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| CN115810484A (en) * | 2022-12-27 | 2023-03-17 | 中国电力工程顾问集团中南电力设计院有限公司 | Method and device for manufacturing sensing ring of optical fiber current transformer at outlet of generator |
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Application publication date: 20200519 |