阅读说明：本技术 一种自补偿型光纤电流传感系统 (Self-compensation type optical fiber current sensing system ) 是由 夏历 黄宇豪 于 2020-06-19 设计创作，主要内容包括：本发明公开了一种自补偿型光纤电流传感系统,属于光纤电流传感器技术领域,包括：光源、光纤、耦合器、传感光路单元、补偿光路单元和信号处理单元；耦合器将光信号均分后分别输入至传感光路单元和补偿光路单元；传感光路单元、补偿光路单元分别使接收到的光信号与待测电流、补偿电流产生的磁场相互作用,将相互作用后光信号收集并转化为电信号输出至信号处理单元；信号处理单元将采集到的输出信号进行闭环处理,经运算抵消掉光路双折射及维尔德常数无关量,得到待测电流的大小。本发明的系统具备较高的测量精度和较强的抗环境干扰能力,解决了以往的FOCS在实际应用时维尔德常数与光路双折射易受环境干扰而使运行稳定性和测量准确性较差的问题。(The invention discloses a self-compensating optical fiber current sensing system, which belongs to the technical field of optical fiber current sensors and comprises the following components: the device comprises a light source, an optical fiber, a coupler, a sensing light path unit, a compensation light path unit and a signal processing unit; the coupler equally divides the optical signals and respectively inputs the optical signals to the sensing optical path unit and the compensation optical path unit; the sensing optical path unit and the compensation optical path unit respectively enable the received optical signals to interact with magnetic fields generated by the current to be measured and the compensation current, collect the optical signals after interaction and convert the optical signals into electric signals to be output to the signal processing unit; the signal processing unit carries out closed-loop processing on the acquired output signals, and the magnitude of the current to be measured is obtained by calculating and offsetting the light path birefringence and the verdet constant irrelevant quantity. The system of the invention has higher measurement precision and stronger environmental interference resistance, and solves the problem that the previous FOCS is poor in operation stability and measurement accuracy because the Verdet constant and the optical path birefringence are easily interfered by the environment in the practical application.)

1. A self-compensating fiber optic current sensing system, comprising: the device comprises a light source, an optical fiber, a coupler, a sensing light path unit, a compensation light path unit and a signal processing unit;

the output end of the light source is connected to the input end of the coupler through the optical fiber, the first output end of the coupler is connected to the sensing optical path unit, the second output end of the coupler is connected to the compensation optical path unit, the output end of the sensing optical path unit is connected to the input end of the signal processing unit, and the output end of the compensation optical path unit is connected to the input end of the signal processing unit;

the light source is used for outputting a light signal; the optical fiber is used for conveying the optical signal to the coupler; the coupler is used for equally dividing the optical signal and then respectively inputting the optical signal to the sensing optical path unit and the compensation optical path unit;

the sensing optical path unit is used for enabling the optical signal to interact with a magnetic field generated by current to be measured to generate a sensing optical signal, collecting the sensing optical signal, converting the sensing optical signal into an electric signal and outputting the electric signal to the signal processing unit;

the compensation optical path unit is used for enabling the optical signal to interact with a magnetic field generated by compensation current to generate a compensation optical signal, collecting and converting the compensation optical signal into an electric signal and outputting the electric signal to the signal processing unit; the compensation optical signal carries birefringence information and Verdet constant information which are the same as those of the sensing optical signal;

the signal processing unit is used for carrying out closed-loop processing on the acquired output signals of the sensing light path unit and the compensation light path unit, counteracting light path birefringence and Verdet constants through calculation, and obtaining the magnitude of the current to be measured.

2. A self-compensating fiber optic current sensing system according to claim 1, wherein: the sensing optical path unit comprises a first horizontal polaroid, a first solenoid, a first sensing head, a first polaroid and a first light detector; the first solenoid is arranged between the first horizontal polarizer and the first polarizer, the first sensor head is arranged in the first solenoid, and the output end of the first light detector is connected to the signal processing unit;

the first horizontal polarizer is used for converting incident light entering the sensing light path unit into first linearly polarized light, the first solenoid is used for generating a first magnetic field after current to be measured is introduced, and the first sensing head is used for receiving the first linearly polarized light and changing the polarization state of the first linearly polarized light under the action of the first magnetic field; the first polarizer is used for changing the polarization state of the first linearly polarized light so that the first optical detector can receive a first optical signal; the first optical detector is used for converting the first optical signal into a first electric signal and transmitting the first electric signal to the signal processing unit.

3. A self-compensating fiber optic current sensing system according to claim 2, wherein: the compensation light path unit comprises a second horizontal polarizer, a second solenoid, a second sensing head, a second polarizer and a second light detector; the second solenoid is arranged between the second horizontal polarizer and the second polarizer, the second sensing head is arranged in the second solenoid, and the output end of the second light detector is connected to the signal processing unit;

the second horizontal polarizer is used for converting incident light entering the compensation light path unit into second linearly polarized light, the second solenoid is used for generating a second magnetic field after compensation current is introduced, and the second sensing head is used for receiving the second linearly polarized light and changing the polarization state of the second linearly polarized light under the action of the second magnetic field; the second polarizer is used for changing the polarization state of the second linearly polarized light so that the second optical detector can receive a second optical signal; the second optical detector is used for converting the second optical signal into a second electric signal and transmitting the second electric signal to the signal processing unit.

4. A self-compensating fiber optic current sensing system according to claim 3, wherein: the first solenoid is arranged perpendicular to the second solenoid; the first sensing head and the second sensing head are arranged vertically.

5. A self-compensating fiber optic current sensing system according to claim 4, wherein: the first sensing head and the second sensing head are fixed through a support.

6. A self-compensating fiber optic current sensing system according to claim 5, wherein: the coupler, the first horizontal polarizer, the second horizontal polarizer, the first sensor head, the second sensor head, the first polarizer, the second polarizer, the first photodetector and the second photodetector have the same type selection.

7. A self-compensating fiber optic current sensing system according to claim 6, wherein: the signal processing unit outputs a signal U to the sensing light path unit_SensingAnd compensating the output signal U of the light path unit_CompensationCarrying out summation operation by using closed-loop control principle to convert U into U_Sensing+U_CompensationIs maintained as E²The birefringence and Verdet constant of the optical path are offset to obtain an expression of the current to be measured

Wherein E is the size of the optical field entering the sensing optical path unit and the compensation optical path unit, and N is_ANumber of turns of the first solenoid, N_BNumber of turns of the second solenoid, I_{To be measured}Is the current to be measured in the first solenoid, I_CompensationIs the compensation current in the second solenoid.

Technical Field

The invention belongs to the technical field of optical fiber current sensors, and particularly relates to a self-compensation optical fiber current sensing system.

Background

In the era of smart grids, safe, reliable and stable power equipment is indispensable. Among more than 2000 high-voltage electronic Current sensors put into operation in China, the Fiber Optics Current Sensor (FOCS) accounts for about 40%. FOCS gradually replaces the traditional current sensor with the advantages of small volume, light weight, good electromagnetic interference resistance, good insulativity and the like.

FOCS is mainly used for measuring the phase difference of circularly polarized light in an optical path caused by Faraday magneto-optical rotation effect around current so as to calculate the current magnitude. The measurement accuracy of the FOCS is closely related to the verdet constant of the optical fiber and the polarization characteristic of the optical path, and the verdet constant and the birefringence of the optical fiber are easily affected by environmental temperature variation, vibration and other factors, so the anti-interference performance of the FOCS is still a great problem on the practical application of the FOCS. To date, researchers have proposed a series of solutions in succession, but still have not been able to reduce environmental disturbances to the desired magnitude. For example: researchers have proposed using rotating fibers, annealed fibers, special photonic crystal fibers, etc. as sensing fibers and have been said to have excellent polarization properties. However, the verdet constants of these optical fibers still change with the change of the environmental temperature, and the preparation process of the special optical fiber is complex and the cost is high; researchers put forward that temperature compensation is carried out by utilizing the characteristic that temperature coefficients of a lambda/4 wave plate and a Verdet constant are opposite in an optical path, but the temperature fluctuation characteristic of the Verdet constant is eliminated, the polarization characteristic still can be interfered by the environment, and the problems that the intercept error of the length of the lambda/4 wave plate is large, the welding angle is difficult to control, the welding point is easy to be interfered by the environment and the like cause that the long-term operation reliability of most FOCS (field-oriented switching system) is far from meeting the requirement; researchers have proposed that integrated polarization FOCS is adopted, and the integrated parts have small volume and can be conveniently controlled at constant temperature, however, the sensing ring part exposed in outdoor environment still suffers from environmental interference, and the integrated parts are expensive; also, researchers dope optical fibers with substances such as Tb and CdSe to increase the verdet constant of the optical fibers, thereby improving the sensitivity of current measurement. However, this does not improve the anti-interference capability of the Verdet constant and polarization characteristic of FOCS, and the doping process will further increase the cost of FOCS.

In summary, even though the FOCS has the advantages that the conventional electromagnetic transformer cannot compare with, the error caused by the verdet constant and the birefringence fluctuation in the practical application process is still a big problem.

Disclosure of Invention

Aiming at the defects or improvement requirements of the prior art, the invention provides a self-compensation type optical fiber current sensing system, so that the technical problems of poor operation stability and poor measurement accuracy caused by the fact that a Verdet constant and optical path birefringence are easily interfered by environment in the practical application of FOCS are solved.

To achieve the above object, according to one aspect of the present invention, there is provided a self-compensating optical fiber current sensing system including: the device comprises a light source, an optical fiber, a coupler, a sensing light path unit, a compensation light path unit and a signal processing unit;

the output end of the light source is connected to the input end of the coupler through the optical fiber, the first output end of the coupler is connected to the sensing optical path unit, the second output end of the coupler is connected to the compensation optical path unit, the output end of the sensing optical path unit is connected to the input end of the signal processing unit, and the output end of the compensation optical path unit is connected to the input end of the signal processing unit;

the light source is used for outputting a light signal; the optical fiber is used for conveying the optical signal to the coupler; the coupler is used for equally dividing the optical signal and then respectively inputting the optical signal to the sensing optical path unit and the compensation optical path unit;

the sensing optical path unit is used for enabling the optical signal to interact with a magnetic field generated by current to be measured to generate a sensing optical signal, collecting the sensing optical signal, converting the sensing optical signal into an electric signal and outputting the electric signal to the signal processing unit;

the compensation optical path unit is used for enabling the optical signal to interact with a magnetic field generated by compensation current to generate a compensation optical signal, collecting and converting the compensation optical signal into an electric signal and outputting the electric signal to the signal processing unit; the compensation optical signal carries birefringence information and Verdet constant information which are the same as those of the sensing optical signal;

the signal processing unit is used for carrying out closed-loop processing on the acquired output signals of the sensing light path unit and the compensation light path unit, counteracting light path birefringence and Verdet constants through calculation, and obtaining the magnitude of the current to be measured.

Preferably, the sensing optical path unit includes a first horizontal polarizer, a first solenoid, a first sensing head, a first polarizer and a first photodetector; the first solenoid is arranged between the first horizontal polarizer and the first polarizer, the first sensor head is arranged in the first solenoid, and the output end of the first light detector is connected to the signal processing unit;

the first horizontal polarizer is used for converting incident light entering the sensing light path unit into first linearly polarized light, the first solenoid is used for generating a first magnetic field after current to be measured is introduced, and the first sensing head is used for receiving the first linearly polarized light and changing the polarization state of the first linearly polarized light under the action of the first magnetic field; the first polarizer is used for changing the polarization state of the first linearly polarized light so that the first optical detector can receive a first optical signal; the first optical detector is used for converting the first optical signal into a first electric signal and transmitting the first electric signal to the signal processing unit.

Preferably, the compensation optical path unit comprises a second horizontal polarizer, a second solenoid, a second sensor head, a second polarizer and a second photodetector; the second solenoid is arranged between the second horizontal polarizer and the second polarizer, the second sensing head is arranged in the second solenoid, and the output end of the second light detector is connected to the signal processing unit;

the second horizontal polarizer is used for converting incident light entering the compensation light path unit into second linearly polarized light, the second solenoid is used for generating a second magnetic field after compensation current is introduced, and the second sensing head is used for receiving the second linearly polarized light and changing the polarization state of the second linearly polarized light under the action of the second magnetic field; the second polarizer is used for changing the polarization state of the second linearly polarized light so that the second optical detector can receive a second optical signal; the second optical detector is used for converting the second optical signal into a second electric signal and transmitting the second electric signal to the signal processing unit.

Preferably, the first solenoid is disposed perpendicular to the second solenoid; the first sensing head and the second sensing head are arranged vertically.

Preferably, the first sensor head and the second sensor head are fixed by a bracket.

Preferably, the coupler, the first horizontal polarizer, the second horizontal polarizer, the first sensor head, the second sensor head, the first polarizer, the second polarizer, the first photodetector, and the second photodetector are all the same in type selection.

Preferably, the signal processing unit outputs a signal U to the sensing optical path unit_SensingAnd compensating the output signal U of the light path unit_CompensationCarrying out summation operation by using closed-loop control principle to convert U into U_Sensing+U_CompensationIs maintained as E²The birefringence and Verdet constant of the optical path are offset to obtain an expression of the current to be measured

Wherein E is the size of the optical field entering the sensing optical path unit and the compensation optical path unit, and N is_ANumber of turns of the first solenoid, N_BNumber of turns of the second solenoid, I_{To be measured}Is the current to be measured in the first solenoid, I_CompensationIs the compensation current in the second solenoid.

Generally, compared with the prior art, the technical scheme of the invention has the advantages that the compensation optical path unit which is completely the same as the sensing optical path unit is arranged, when the signal processing unit calculates the output signals of the sensing optical path unit and the compensation optical path unit by using the closed-loop control principle, the optical fiber birefringence change and the Verdet constant change caused by linear birefringence and environmental interference can be counteracted, and finally the current to be measured is only related to the compensation current and the number of turns of the solenoid.

Drawings

FIG. 1 is a schematic block diagram of one embodiment of the present invention;

fig. 2 is a schematic diagram illustrating the installation of the sensing optical path unit and the compensation optical path unit according to an embodiment of the present invention.

The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein: a light source 1; an optical fiber 2; a coupler 3; a first horizontal polarizer 4A; a second horizontal polarizer 4B; a first solenoid 5A; a second solenoid 5B; a first sensor head 6A; the second sensor head 6B; a first polarizing plate 7; a second polarizing plate 8; a first photodetector 9A; a second photodetector 9B; a signal processing unit 10; a support 11.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.