CN116990573A - All-fiber current transformer - Google Patents
All-fiber current transformer Download PDFInfo
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- CN116990573A CN116990573A CN202310870878.XA CN202310870878A CN116990573A CN 116990573 A CN116990573 A CN 116990573A CN 202310870878 A CN202310870878 A CN 202310870878A CN 116990573 A CN116990573 A CN 116990573A
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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
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Abstract
The application relates to an all-fiber current transformer, comprising: the device comprises a light source, a first beam combiner, a first circulator, a second circulator, an optical fiber coupler, a single circularly polarized optical fiber ring, a second beam combiner, a photoelectric detector and an electric signal processing circuit. The optical fiber ring adopts single circularly polarized optical fiber, namely, only a unique circular polarization state exists in the optical fiber ring, the phase change of the ideal circular polarization is only in direct proportion to current, the mutual inductor analyzes 4 optical interference signals and can further reduce the influence of external interference factors on current measurement through the difference comparison of a plurality of optical interference signals.
Description
Technical Field
The application relates to the field of current transformers, in particular to an all-fiber current transformer.
Background
All-fiber current transformers developed and produced by the american GE company (alston Alstom, france, swiss ABB, and domestic colleagues) are shown in the principle of fig. 1.
For the traditional all-fiber current transformer, the current transformer comprises a circuit analysis unit 1, a current optical fiber sensing unit 3 and a polarization maintaining optical fiber 2 for connecting the circuit analysis unit and the current optical fiber sensing unit. Light from the LED light source 11 is input to the optical fiber coupler 12 and output to the polarizer 13 via the first output end of the optical fiber coupler 12 to form a light signal in a linear polarization state, which must first pass through the phase modulator 14 in fig. 1, be phase-modulated into a pulse signal, and then be transmitted to the current optical fiber sensing unit 3 through the polarization maintaining optical fiber 2 maintaining the "linear polarization state". The current optical fiber sensing unit 3 comprises a 1/4 wave plate 31, an optical fiber ring 32 formed by round-keeping optical fibers and a transmitting mirror 3, wherein the 1/4 wave plate positioned at the input end of the optical fiber ring converts linearly polarized light transmitted by the round-keeping optical fibers 2 into circularly polarized light. The circularly polarized light signal is transmitted in an optical fiber ring 32 consisting of circularly protecting optical fibers maintaining a "circular polarization state" to the end of the optical fiber ring, and a mirror 33 at the end reflects the light signal back into the optical fiber ring 32 and back to the light detector 16 in fig. 1. Based on faraday's principle, the phase change of circularly polarized light generated during forward and reverse transmission of the optical fiber ring 32 is proportional to the current passing through the optical fiber ring, and thus the current can be measured by detecting the phase change of circularly polarized light by the photodetector 16 and the electric signal demodulation circuit 14. However, the circular polarization state of the circular protection fiber can exist in both clockwise and anticlockwise directions, when the circular polarization state is affected by factors such as environmental temperature change, external stress change and vibration, the circularly polarized light in the optical fiber ring 32 formed by the circular protection fiber is not an understood circular polarization state, but an elliptical polarization state, and the phase change of the circular polarization state is easily interfered by external factors, so that the sensor is not easy to distinguish current signals to be measured from external interference.
Disclosure of Invention
In view of the above, the present application provides a novel all-fiber current transformer, which aims to solve the technical problem that the position change of the measured light is easily interfered by external factors when the current measurement is performed by the current fiber transformer.
The application provides an all-fiber current transformer, comprising:
a light source for generating a pulsed light signal;
the first beam combiner comprises an input end, a first output end and a second output end, and is used for dividing a pulse optical signal input through the input end into 2 beams of input ends and outputting the 2 beams of input ends through the first output end and the second output end respectively;
the first circulator comprises an input end, a first output end and a second output end, and the input end of the first circulator is connected with the first output end of the first beam combiner;
the second circulator comprises an input end, a first output end and a second output end, and a first optical signal delay line is connected in series between the input end of the second circulator and the second output end of the first combiner;
the optical fiber coupler comprises a first input end, a second input end and an output end, wherein the first input end of the optical fiber coupler is connected with the first output end of the first circulator, and the second input end of the optical fiber coupler is connected with the first output end of the second circulator;
one end of the single circularly polarized light fiber ring is connected with the first output end of the optical fiber coupler, and the other end of the single circularly polarized light fiber ring is connected with the second output end of the optical fiber coupler;
the second beam combiner comprises an output end, a first input end and a second input end, the first input end of the second beam combiner is connected with the second output end of the first circulator, and a second optical signal delay line is connected in series between the second input end of the second beam combiner and the second output end of the second circulator;
the photoelectric detector is arranged at the output end of the second beam combiner and is used for detecting 4 kinds of interference light output by the second beam combiner;
and the electric signal processing circuit is connected with the photoelectric detector and is used for analyzing the detection signal of the photoelectric detector to obtain the phase change of the single circularly polarized light in the single circularly polarized light fiber ring, so as to obtain the magnitude of the detected current passing through the single circularly polarized light fiber ring.
Further, the all-fiber current transformer further comprises an optical isolator connected between the light source and the input end of the first beam combiner, wherein the conducting direction of the optical isolator is from the light source to the input end of the first beam combiner.
Further, in the all-fiber current transformer of the present application, the 4 kinds of interference light are generated and transmitted according to the following optical paths, respectively:
1 st: the optical fiber coupler comprises a first output end of a first beam combiner, a first optical circulator, an optical fiber coupler, a single circularly polarized optical fiber ring, an optical fiber coupler, the first optical circulator, a second beam combiner and a photoelectric detector;
2 nd: the optical fiber coupler comprises a first output end of a first beam combiner, a first optical circulator, an optical fiber coupler, a single circularly polarized optical fiber ring, an optical fiber coupler, a second optical circulator, a second optical signal delay line, a second beam combiner and a photoelectric detector;
3 rd: the second output end of the first beam combiner, the first optical signal delay line, the second optical circulator, the optical fiber coupler, the single circularly polarized optical fiber ring, the optical fiber coupler, the first optical circulator, the second beam combiner and the photoelectric detector;
4 th: the second output end of the first beam combiner, the first optical signal delay line, the second optical circulator, the optical fiber coupler, the single circularly polarized optical fiber ring, the optical fiber coupler, the second optical circulator, the second optical signal delay line, the second beam combiner and the photoelectric detector.
Further, in the all-fiber current transformer of the present application, the delay time of the first optical signal delay line is not equal to the delay time of the second optical signal delay line.
Further, in the all-fiber current transformer of the present application, the single circularly polarized fiber ring is made of single circularly polarized fiber.
Further, in the all-fiber current transformer, the electric signal processing circuit, the photoelectric detector, the light source and the optical isolator are all arranged locally, the photoelectric detector is remotely connected to the output end of the second beam combiner through a communication optical fiber cable, and the output end of the optical isolator is remotely connected to the input end of the second beam combiner through the communication optical fiber cable.
Further, in the all-fiber current transformer of the present application, the light source is a laser light source.
Compared with the traditional all-fiber current transformer, the all-fiber current transformer has the following 8 advantages:
1. the optical fiber ring in the traditional all-fiber current transformer adopts a circular protection optical fiber, and the optical fiber ring of the all-fiber current transformer adopts a single circularly polarized optical fiber, namely, only a unique circular polarization state exists in the optical fiber ring, and the phase change of the ideal circular polarization is only in direct proportion to the current and is not interfered by external factors.
2. While a conventional all-fiber current transformer only analyzes optical interference signals at one location of the coupler, the transformer of the present application analyzes 4 optical interference signals. By comparing the differences of the plurality of optical interference signals, the influence of external interference factors on current measurement can be further reduced, the influence of the relative positions of the optical fiber ring and a cable for transmitting current on measurement is avoided, and the influence of performance changes of all devices forming the current transformer, such as a laser light source, a light detector, an optical fiber coupler and the like, on current measurement can be eliminated.
3. Conventional all-fiber current transformers require a phase modulator located near the current measurement point, and the phase modulator requires a voltage to be applied across the device to operate. The mutual inductor does not need a phase modulator, and realizes 100% zero electricity near a current measurement point.
4. The traditional all-fiber current transformer needs to transmit the linearly polarized light signal from the signal analysis unit to the phase modulator and then to the optical fiber ring by using the polarization maintaining optical fiber, however, the capacity of maintaining the linear polarization state of the polarization maintaining optical fiber is also easily influenced by factors such as environmental temperature change, external stress change, vibration and the like, thereby reducing the accuracy and stability of current measurement. The all-fiber current transformer of the application only needs to use common communication optical fibers to connect the optical isolator, the electric detector and the optical fiber ring, thus greatly enhancing the stability of current measurement.
5. The electric signal processing circuit, the electric detector, the light source and the optical isolator of the all-fiber current transformer are all arranged on the body and are remotely connected to the optical fiber ring through the common communication optical fiber cable. The phase modulator of the traditional all-fiber current transformer needs to be placed in an outdoor phase modulation box, and the performance of an outdoor photoelectric module is easily interfered by the outside.
6. The current transformer has the advantages that all optical fiber devices in the current transformer are connected by adopting the common communication optical fibers, so that the cost is reduced, and the stability of products is greatly enhanced because the common communication optical fibers are easy to weld with each other.
7. The all-fiber current transformer does not need a 1/4 wave plate, and avoids errors caused by the fact that the 1/4 wave plate can not convert linear polarized light into circular polarized light by 100%.
8. Because of the stability of the working principle, the all-fiber current transformer only needs to be calibrated during installation, and no calibration and calibration are needed in the subsequent use.
Drawings
FIG. 1 is a schematic diagram of a conventional all-fiber current transformer;
FIG. 2 is a schematic diagram of an all-fiber current transformer of the present application;
FIG. 3 is a graph of measurement error data for an all-fiber current transformer of the present application when measuring different currents;
FIG. 4 is a graph of measurement error data for an all-fiber current transformer of the present application when the measured current is 3000A and the measured temperature is varied from-25℃to 85 ℃.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present application more apparent, embodiments of the present application will be further described with reference to the accompanying drawings.
Referring to fig. 2, the present application provides an all-fiber current transformer, comprising: the optical fiber processing device comprises a light source 2, a first beam combiner 4, a first circulator 5, a second circulator 7, an optical fiber coupler 8, a single circularly polarized optical fiber ring 9, a second beam combiner 11, a photoelectric detector 12 and an electric signal processing circuit 1.
The light source 2 is used to generate a pulsed light signal, which in this embodiment is preferably a laser light source, which is generated by adjusting the current of the laser light source by the electrical signal processing circuit 1, and in other embodiments of the application, the pulsed light signal may also be generated by adjusting the current of the laser light source by an adjusting component of the laser light source strip. Unlike the prior art, in which the current driving the light source is constant and then the pulse signal is generated by the phase modulator, in the present application, the current driving the laser light source is a pulse signal and the generated optical signal is also a pulse optical signal.
The first beam combiner 4 includes an input end located at the left side, a first output end located at the upper right side, and a second output end located at the lower right side in fig. 2, and the first beam combiner 2 is configured to divide a pulse optical signal input through the input end into 2 input ends and output the 2 input ends by the first output end and the second output end, respectively. As a preferred embodiment, in order to avoid damage to the light source 2 caused by reverse transmission of the optical signal at the rear end back to the light source 2, an optical isolator 3 is further included between the light source 2 and the first beam combiner 4, and the optical isolator 3 is connected between the light source 2 and the input end of the first beam combiner 4, and the conducting direction of the optical isolator 3 is from the light source 2 to the input end of the first beam combiner 4.
The first circulator 5 includes an input terminal located at an upper left side, a first output terminal at a right side, and a second output terminal at a lower left side in fig. 2, and the input terminal of the first circulator 5 is connected to the first output terminal of the first combiner 4.
The second circulator 7 includes an input end located at an upper left side, a first output end located at a right side, and a second output end located at a lower left side in fig. 2, and a first optical signal delay line 6 is connected in series between the input end of the second circulator 7 and the second output end of the first combiner 4, where the first optical signal delay line 6 is used to delay an optical signal transmitted between the input end of the second circulator 7 and the second output end of the first combiner 4.
The optical fiber coupler 8 includes a first input end located at the upper left side, a second input end located at the lower left side, a first output end located at the upper right side, and a second output end located at the upper right side in fig. 2, the first input end of the optical fiber coupler 8 is connected to the first output end of the first circulator 5, and the second input end of the optical fiber coupler 8 is connected to the first output end of the second circulator 7.
One end of the single circularly polarized light fiber ring 9 is connected with the first output end of the optical fiber coupler 8, the other end is connected with the second output end of the optical fiber coupler 8, an optical signal enters one end of the single circularly polarized light fiber ring 9 from the first output end of the optical fiber coupler 8, after the single circularly polarized light fiber ring 9 is transmitted, the optical signal returns to the second output end of the optical fiber coupler 8 from the other end of the single circularly polarized light fiber ring 9, and when the optical signal enters the single circularly polarized light fiber ring 9 from the second output end of the optical fiber coupler 8, the optical signal returns to the optical fiber coupler 8 from the second output end of the optical fiber coupler 8. When single circularly polarized light enters from two ends of the single circularly polarized light fiber ring 9, the single circularly polarized light fiber ring 9 transmits forward and backward, interference is generated based on the sagnac effect, and the phase change generated in the interference signal transmission process is in direct proportion to the measured current A passing through the single circularly polarized light fiber ring 9. The single circularly polarized light fiber ring 9 is made of single circularly polarized light fiber, the single circularly polarized light fiber ring 9 is made of single circularly polarized light fiber wound continuously for a plurality of circles, and as a preferred embodiment, the plurality of circles of single circularly polarized light fiber are coaxial and have the same radius. The single circularly polarized light fiber itself belongs to the prior art, and one implementation manner of the single circularly polarized light fiber can be realized by adopting the multi-blade stress area circular single polarized light fiber disclosed in CN 20151061194.
The second beam combiner 11 includes an output end located at the left side, a first input end located at the upper right side, and a second input end located at the lower right side in fig. 2, the first input end of the second beam combiner 11 is connected to the second output end of the first circulator 5, and a second optical signal delay line 10 is connected in series between the second input end of the second beam combiner 11 and the second output end of the second circulator 7.
The photodetector 12 is provided at the output end of the second beam combiner 7 for detecting the 4 kinds of interference light output from the second beam combiner 11.
The electric signal processing circuit 1 is connected with the photoelectric detector 12 and is used for analyzing the detection signal of the photoelectric detector 12 to obtain the phase change of the single circularly polarized light in the single circularly polarized light fiber ring 9, so as to obtain the magnitude of the detected current A passing through the single circularly polarized light fiber ring.
The 4 kinds of interference light are generated and transmitted according to the following light paths:
1 st: the first output end of the first combiner 4→the input end and the first output end of the first optical circulator 5→the first input end, the first output end and the second output end of the optical fiber coupler 8 (input from the first input end and output from the first output end and the second output end firstly) →the single circularly polarized fiber ring 9→the first output end and the second output end and the first input end of the optical fiber coupler 8 (input from the first output end and the second output end and output from the first input end) →the first output end and the second output end of the first optical circulator 5→the first input end and the output end of the second combiner 11→the photodetector 12; wherein, in the single circularly polarized light fiber ring 9, the optical signal is transmitted to both ends of the single circularly polarized light fiber ring 9 from both output ends of the optical fiber coupler 8, then transmitted in the single circularly polarized light fiber ring 9 and interfered, and then transmitted to both output ends of the optical fiber coupler 8 from entering the single circularly polarized light fiber ring 9. In the other light described below, the transmission to the single circularly polarized fiber ring 9 is similar, and will not be described in detail.
2 nd: the first output end of the first combiner 4, the input end and the first output end of the first optical circulator 5, the first input end, the first output end and the second output end of the optical fiber coupler 8 (input from the first input end and output from the first output end and the second output end firstly), the single circularly polarized fiber ring 9, the first output end and the second output end of the optical fiber coupler 8, the second input end (input from the first output end and the second output end and output from the second input end) of the second optical circulator 7, the second output end of the second optical fiber coupler 7, the second optical signal delay line 10, the second input end and the output end of the second combiner 11, and the photoelectric detector 12.
3 rd: the second output end of the first combiner 4→the first optical signal delay line 6→the input end, the first output end, of the second optical circulator 7→the second input end, the first output end, and the second output end of the optical fiber coupler 8 (input from the second input end and output from the first output end and the second output end first), the single circularly polarized fiber ring 9→the first output end and the second output end, the first input end (input from the first output end and the second output end and output from the first input end) of the optical fiber coupler 8→the first output end, the second output end of the first optical circulator 5→the second input end, the output end of the second combiner 11→the photodetector 12.
4 th: the first combiner 4 second output end→the first optical signal delay line 6→the second optical circulator input end, the first output end→the second input end, the first output end and the second output end of the optical fiber coupler 8 (input from the second input end and output from the first output end and the second output end firstly) →the single circularly polarized optical fiber ring 9→the first output end and the second output end of the optical fiber coupler 8 and the second input end (input from the first output end and the second output end and output from the second input end) →the second optical circulator 5 first output end and the second output end→the second optical signal delay line 10→the second input end, the output end of the second combiner 11→the photoelectric detector 12.
Of the 4 optical paths described above, the 1 st optical path does not pass through any delay line, the 2 nd optical path passes through the second optical signal delay line 10, the 3 rd optical path passes through the first optical signal delay line 6, and the 4 th optical path passes through the first optical signal delay line 6+the second optical signal delay line 10. In order to ensure that the electrical signal processing circuit 1 can distinguish four optical paths, the delay of the first optical signal delay line 6 is not equal to the delay of the second optical signal delay line 10, so that the electrical signal processing circuit 1 can analyze the interference light in the 4 detected by the photodetector 12 to obtain the phase of the single circularly polarized light in the single circularly polarized light fiber ring 9, thereby obtaining the measured current A passing through the single circularly polarized light fiber ring 9.
The mutual inductor analyzes 4 optical interference signals, and by comparing the differences of a plurality of optical interference signals, the influence of external interference factors on current measurement can be further reduced, the influence of the relative positions of the optical fiber ring and a cable for transmitting current on measurement is avoided, and the influence of performance changes of all devices forming the current mutual inductor, such as a laser light source, a light detector, an optical fiber coupler and the like, on current measurement can be eliminated. The difference comparison can be realized by common mathematical methods, and can comprise abnormal value elimination, average value taking, maximum value elimination, minimum value elimination and the like.
The signal processing units such as the electric signal processing circuit 1, the photoelectric detector 12, the light source 2, the optical isolator 3 and the like are all arranged locally, and the photoelectric detector 12, the optical isolator 3 and the single circularly polarized light fiber ring 9 can be remotely connected through common communication fiber-optic cables in daily life.
The common faults of the operation of the traditional all-fiber current transformer are as follows: 1. low temperature problems; 2. vibration resistance problems; 3. waterproof problems; 4. breaking the optical fiber; 5. an electronic unit operating environment problem; 6. electronic unit light source problem; 7 construction process problems, and the all-fiber current transformer can well solve the problems.
Low temperature problem
The problem of low temperature is the problem that the frequency of occurrence of the traditional all-fiber current transformer is the greatest at present, and the problem of low temperature can be divided into a sensing ring low temperature problem, a modulation tank low temperature problem and a single-mode optical cable pipeline icing problem.
Sensing ring low temperature problem: under the lower condition of temperature, because the condition that the optical fibers are mutually extruded due to thermal expansion and contraction exists, the sensing optical fibers are mutually entangled to generate microbending, and the traditional circular protection optical fibers can not keep a circular polarization state, so that an optical signal is changed into an elliptical polarization state. However, the all-fiber current transformer of the application adopts a single circularly polarized light fiber as an optical fiber ring, and the circular polarization state of the all-fiber current transformer does not change into an elliptical polarization state.
Low temperature problem of brewing box (canister): the delay coil in the modulation box (tank) of the traditional all-fiber current transformer must use polarization maintaining fiber, and the delay coil mainly shows that the second harmonic of the state parameter is reduced (namely, the extinction ratio is reduced) at low temperature, so that the measurement accuracy deviation is caused. The fault of polarizing fiber mainly shows that the driving current of the state parameter light source is increased and the light intensity peak value is reduced at low temperature, so that the invalid alarm of the light intensity low data is caused. The impedance matching problem mainly shows that the modulation voltage and the modulation phase are reduced at low temperature, so that the modulation voltage is in an out-of-lock alarm or the modulation phase is low. The all-fiber current transformer does not need a modulation box and has no problem of low temperature of the modulation box.
Icing problem of single mode fiber pipeline: for the all-fiber current transformer, common communication optical fiber cables are used from the optical fiber transfer box to the electronic chassis, and mature protection and installation measures of an optical fiber communication network can be adopted.
2. Vibration resistance problem
The traditional all-fiber current transformer generates abnormal current due to vibration of the modulation box, so that the fault is caused. The phase modulator is internally provided with a vibration sensitive device which is a delay coil and has a proportion of 82% through theoretical analysis and test verification. The phase modulator and polarizing fiber are quite sensitive to vibration, and each accounts for about 9%.
The all-fiber current transformer does not need a modulation box, and the vibration resistance problem of the modulation box does not exist.
3. Waterproof problem
The waterproof problem is divided into an optical fiber ring waterproof problem, a modulation box (tank) waterproof problem and a folding insulator joint waterproof problem. The all-fiber current transformer does not need a modulation box, so that the waterproof problem of the sensing ring and the waterproof problem of the joint of the folding insulator only need to be solved.
4. Problem of broken optical fiber
Failure of the fiber can result in invalid data. The traditional all-fiber current transformer needs to weld polarization-maintaining fibers in an outdoor field, and has high requirements on welding fiber equipment and technicians. The wind sand can be adsorbed on the buffer pad of the optical fiber cutter to cut the optical fiber, and can also enter the electrode cabin of the optical fiber fusion splicer to cause unstable discharge, so that the coated optical fiber removed near the fusion joint is damaged or the strength of the fusion joint is insufficient, and the optical fiber is broken after long-time operation. However, the all-fiber current transformer uses common communication fibers, and the welding equipment and the implementation method of the optical fiber communication network are sufficient to ensure the normal transmission of optical signals.
5. Electronic unit operating environment problems
For the traditional all-fiber current transformer, because the electronic unit optical main board has more floating ashes on the circuit board, stray capacitance is generated on the surface of the floating ashes to influence the stable operation of the optical loop, so that the working state of the light source of the optical main board is unstable, and the optical CT action logic data is invalid and relevant protection is withdrawn. The all-fiber current transformer eliminates measurement errors generated by unstable factors of an electronic unit.
6. Problem of light source of electronic unit
The instability of the light source of the electronic unit of the traditional all-fiber current transformer can cause measurement faults. But the all-fiber current transformer eliminates measurement errors caused by unstable light sources.
7. Construction process problems
7.1. The operation condition of the all-fiber current transformer is directly affected by the quality of the construction process. For the traditional all-fiber current transformer, attention is particularly required to pay attention to the welding quality of the polarization maintaining fiber, frequent alarms can be caused by unqualified welding of the polarization maintaining fiber, and extreme locking can be caused when the state quantity parameter is unqualified. However, the all-fiber current transformer adopts common communication fibers, and the construction process can directly adopt a mature fiber communication network construction process.
7.2. In the traditional all-fiber current transformer, the lack of nylon screws for fixing piezoelectric ceramics leads to high modulation voltage alarm. However, the all-fiber current transformer of the application does not need to use piezoelectric ceramics, and does not have the problems.
For other problems such as wrong setting of parameters of the electronic unit, unthreaded screws of the radiator of the electronic unit and the like, serious and strict construction can be completely avoided.
The all-fiber current transformer is adopted for testing, the measurement error when different currents are measured is shown in figure 3, the measurement error is smaller when the current is larger, and the measurement error is about 0.25% when the current is 100A; when the current is more than 1000A, the measurement error is less than 0.01%. When the measured current is 3000A and the measured temperature is changed from-25 ℃ to 85 ℃, the measured errors at different test times are less than 0.05% as shown in figure 4.
In this document, terms such as front, rear, upper, lower, etc. are defined with respect to the positions of the components in the drawings and with respect to each other, for clarity and convenience in expressing the technical solution. It should be understood that the use of such orientation terms should not limit the scope of the claimed application.
The embodiments described above and features of the embodiments herein may be combined with each other without conflict.
The foregoing description of the preferred embodiments of the application is not intended to limit the application to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and scope of the application are intended to be included within the scope of the application.
Claims (7)
1. An all-fiber current transformer, comprising:
a light source for generating a pulsed light signal;
the first beam combiner comprises an input end, a first output end and a second output end, and is used for dividing a pulse optical signal input through the input end into 2 beams of input ends and outputting the 2 beams of input ends through the first output end and the second output end respectively;
the first circulator comprises an input end, a first output end and a second output end, and the input end of the first circulator is connected with the first output end of the first beam combiner;
the second circulator comprises an input end, a first output end and a second output end, and a first optical signal delay line is connected in series between the input end of the second circulator and the second output end of the first combiner;
the optical fiber coupler comprises a first input end, a second input end, a first output end and a second output end, wherein the first input end of the optical fiber coupler is connected with the first output end of the first circulator, and the second input end of the optical fiber coupler is connected with the first output end of the second circulator;
one end of the single circularly polarized light fiber ring is connected with the first output end of the optical fiber coupler, and the other end of the single circularly polarized light fiber ring is connected with the second output end of the optical fiber coupler;
the second beam combiner comprises an output end, a first input end and a second input end, the first input end of the second beam combiner is connected with the second output end of the first circulator, and a second optical signal delay line is connected in series between the second input end of the second beam combiner and the second output end of the second circulator;
the photoelectric detector is arranged at the output end of the second beam combiner and is used for detecting 4 kinds of interference light output by the second beam combiner;
and the electric signal processing circuit is connected with the photoelectric detector and is used for analyzing the detection signal of the photoelectric detector to obtain the phase change of the single circularly polarized light in the single circularly polarized light fiber ring, so as to obtain the magnitude of the detected current passing through the single circularly polarized light fiber ring.
2. The all-fiber current transformer of claim 1, further comprising an optical isolator connected between the light source and the input of the first combiner, the optical isolator having a turn-on direction from the light source to the input of the first combiner.
3. The all-fiber current transformer of claim 1, wherein the 4 types of interference light are generated and transmitted according to the following optical paths, respectively:
1 st: the optical fiber coupler comprises a first output end of a first beam combiner, a first optical circulator, an optical fiber coupler, a single circularly polarized optical fiber ring, an optical fiber coupler, the first optical circulator, a second beam combiner and a photoelectric detector;
2 nd: the optical fiber coupler comprises a first output end of a first beam combiner, a first optical circulator, an optical fiber coupler, a single circularly polarized optical fiber ring, an optical fiber coupler, a second optical circulator, a second optical signal delay line, a second beam combiner and a photoelectric detector;
3 rd: the second output end of the first beam combiner, the first optical signal delay line, the second optical circulator, the optical fiber coupler, the single circularly polarized optical fiber ring, the optical fiber coupler, the first optical circulator, the second beam combiner and the photoelectric detector;
4 th: the second output end of the first beam combiner, the first optical signal delay line, the second optical circulator, the optical fiber coupler, the single circularly polarized optical fiber ring, the optical fiber coupler, the second optical circulator, the second optical signal delay line, the second beam combiner and the photoelectric detector.
4. The all-fiber current transformer of claim 3, wherein the delay of the first optical signal delay line is not equal to the delay of the second optical signal delay line.
5. The all-fiber current transformer of claim 1, wherein the single circularly polarized fiber ring is made of single circularly polarized fiber.
6. The all-fiber current transformer according to claim 2, wherein the electrical signal processing circuit, the photodetector, the light source and the optical isolator are all arranged locally, and the photodetector, the optical isolator and the single circularly polarized fiber loop are remotely connected through a communication fiber optic cable.
7. The all-fiber current transformer of claim 1, wherein the light source is a laser light source.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310870878.XA CN116990573A (en) | 2023-07-14 | 2023-07-14 | All-fiber current transformer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310870878.XA CN116990573A (en) | 2023-07-14 | 2023-07-14 | All-fiber current transformer |
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