CN116718822A - High fault tolerance system and control method of optical fiber current sensor suitable for energy industry - Google Patents

Abstract

The invention discloses a high fault tolerance system of an optical fiber current sensor and a control method thereof, which are applicable to the energy industry, wherein the high fault tolerance system of the optical fiber current sensor comprises a light source/detector control module (200), a polarizer (41), a 45-degree fusion point (42), a phase modulator (5), a 2 multiplied by 1 coupler (61), a phase modulator fault tolerance control module (202), a delay line (7), a sensing module (201), a D/A converter (14) and an FPGA main control unit (19). The invention can realize reliable, safe and stable operation of the sensor in the degradation state of the device, further reduce the loss caused by the fault of the optical fiber current sensor and provide a feasible method for high fault tolerance control of the optical fiber current sensor.

Description

High fault tolerance system and control method of optical fiber current sensor suitable for energy industry

Technical Field

The invention belongs to the technical field of optical fiber current sensing, and particularly relates to a high fault tolerance system and a control method of an optical fiber current sensor suitable for the energy industry.

Background

The optical fiber current sensor has the advantages of strong anti-interference capability, durability, strong reliability, high accuracy and the like, and the optical fiber has good insulating property, so that the optical fiber current sensor is widely applied to various fields.

The fiber optic current sensor is based on faraday effect and uses optical fiber as a transmission medium and sensing element. The faraday effect is a phenomenon in which polarized light in a sensing fiber is subjected to a magnetic field generated by a current to rotate a polarization plane. Considering that the optical fiber current sensor has a complex structure, the integration level is quite high and more precise, so that the fault occurrence probability of the optical fiber current sensor is continuously increased. In actual operation, the optical fiber current sensor is affected by various factors such as temperature, vibration and the like, so that reliability is reduced, various optical devices used in the sensor system are easy to lose, and performance is gradually degraded when the optical fiber current sensor works in a severe environment for a long time. These factors can lead to the decline of fiber current sensor measurement accuracy, probably break down under serious circumstances, can not accurately obtain primary side current information, constitute the wei rib to the safe operation of place system, influence the normal operating of work.

The invention with publication number CN114777934A discloses a real-time monitoring method for the wavelength of a laser based on a polarization optical fiber interferometer, which utilizes a real-time monitoring device for the wavelength of the polarization optical fiber interferometer system to collect four paths of interference signals with phase shifting of 0 DEG, 90 DEG, 180 DEG and 270 DEG, demodulates the four paths of spatial phase shifting interference signals carrying real-time wavelength information by a four-step phase shifting method to obtain corresponding phase information, further obtains wavelength information, and realizes real-time monitoring for the wavelength of the laser. The polarization optical fiber interferometer system adopts polarization maintaining optical fibers and devices, realizes synchronous phase shifting and solves the problem of amplitude jitter caused by unstable polarization direction of interference light in a common optical fiber interferometer. The invention can feed back the light intensity information of four pixels to obtain the wavelength variation by only one four-quadrant detector, thereby avoiding the error problem caused by long displacement, reducing the cost, having the characteristics of low insertion loss, high sampling rate and high precision and being capable of realizing real-time wavelength monitoring of the laser. However, the invention does not effectively solve the problem of fault tolerance control in the fiber optic current sensor caused by device damage or performance degradation.

Disclosure of Invention

The technical problems to be solved are as follows: the invention discloses a high fault tolerance system and a control method of an optical fiber current sensor, which are applicable to the energy industry, and can realize reliable, safe and stable operation of the sensor in a device degradation state, so that the loss caused by the fault of the optical fiber current sensor is further reduced, and a feasible method is provided for the high fault tolerance control of the optical fiber current sensor.

The technical scheme is as follows:

the high fault tolerance system of the optical fiber current sensor suitable for the energy industry comprises a light source/detector control module (200), a polarizer (41), a 45-degree fusion point (42), a phase modulator (5), a 2X 1 coupler (61), a phase modulator fault tolerance control module (202), a delay line (7), a sensing module (201), a D/A converter (14) and an FPGA main control unit (19);

the light source/detector control module (200) comprises a main SLD light source (11), a first coupler (21), a first power detector (31), a first light source control component (161), a main PINFET (171) and a fourth A/D converter (181); the main SLD light source (11) and the main PINFET (171) controlled by the first light source control component (161) are connected with the first power detector (31) through the first coupler (21);

the phase modulator fault-tolerant control module (202) consists of a 3X 1 coupler (62), a 0-degree analyzer (111), a 90-degree analyzer (112), a 1/4 wave plate (1131), a 45-degree analyzer (1132), a first photoelectric detector (121), a second photoelectric detector (122), a third photoelectric detector (123), a first A/D converter (131), a second A/D converter (132) and a third A/D converter (133);

the sensing module (201) consists of an optical fiber 1/4 wave plate (8), a sensing optical fiber ring (9), a reflecting mirror (10) and a current-carrying lead (15); the optical fiber 1/4 wave plate (8) is welded with the delay line (7) at 45 degrees, the tail end of the sensing optical fiber ring (9) is connected with the reflecting mirror (10), the sensing optical fiber ring (9) forms a ring, and the ring passes through the current-carrying lead (15);

when the phase modulator normally operates, the output light of the main SLD light source (11) is normally output through the first coupler (21), the first power detector (31) monitors the state of the main SLD light source (11) through the first coupler (21), the output light is changed into two orthogonal linearly polarized lights with a phase difference of 90 degrees through the polarizer (41) and the 45-degree fusion point (42), the two orthogonal linearly polarized lights form two circularly polarized lights with opposite rotation directions after passing through the phase modulator (5), the 2 x 1 coupler (61), the delay line (7) and the optical fiber 1/4 wave plate (8), the two circularly polarized lights enter the sensing optical fiber ring (9) and are returned to the sensing optical fiber ring (9) after being acted by the reflecting mirror (10) at the tail end of the sensing optical fiber ring (9), the returned two circularly polarized lights pass through the optical fiber 1/4 wave plate (8) again and are converted into two orthogonal linearly polarized lights, and then sequentially return to the delay line (7), the 2 x 1 coupler (61), the phase modulator (5), the 45-degree fusion point (42) and the polarization modulator (41) to enter the main FPGA (19) through the four-phase modulator (19) and finally enter the main FPGA (19) through the main control unit (19) by adopting the digital FPGA;

when the phase modulator fails, light reflected by the reflecting mirror is received by the main PINFET (171), the first photoelectric detector (121), the second photoelectric detector (122) and the third photoelectric detector (123) through the 2X 1 coupler (61) respectively through the 45-degree fusion point (42) and the polarizer (41), the 0-degree analyzer (111), the 90-degree analyzer (112), the 1/4 wave plate (1131) and the 45-degree analyzer (1132), and digital signals are transmitted to the FPGA main control unit (19) through the fourth A/D converter (181), the first A/D converter (131), the second A/D converter (132) and the third A/D converter (133) respectively; the FPGA main control unit (19) carries out vector calculation on power signals of four light paths of the 45-degree fusion point (42) and the polarizer (41), the 0-degree analyzer (111), the 90-degree analyzer (112), the 1/4 wave plate (1131) and the 45-degree analyzer (1132), and carries out high fault tolerance control on the fiber current sensor.

Further, the light source/detector control module (200) further includes a backup SLD light source (12), a second coupler (22), a third coupler (23), a second power detector (32), a second light source control component (162), a backup finfet (172), and a fifth a/D converter (182);

the standby SLD light source (12) and the standby PINFET (172) controlled by the second light source control component (162) are connected with the second power detector (32) and the third coupler (23) through the second coupler (22), and the first coupler (21) is connected with the second coupler (22) in parallel and then connected with the third coupler (23) in series;

when the first power detector (31) detects that the main SLD light source (11)/the main PINFET (171) is in fault, the FPGA main control unit (19) drives the first light source control component (161) to close the main SLD light source (11)/the main PINFET (171) and simultaneously drives the second light source control component (162) to open the standby SLD light source (12)/the standby PINFET (172), and light returned by the reflecting mirror (10) enters the standby PINFET (172) through the third coupler (23) and the second coupler (22), and finally reaches the FPGA main control unit (19) through the fifth A/D converter (182).

Further, when the phase modulator fails, it is assumed that the light vector entering the first 2×1 coupler (61) is E _in Jones matrix of polarizer (41) is J _p Jones matrix of 45 ° fusion point (42) is J ₄₅₁ Jones matrix of 0 degree analyzer (111) is J ₀ ，90°Jones matrix of analyzer (112) is J ₉₀ The Jones matrix of the 1/4 wave plate (1131) is J _b Jones matrix of 45 degree analyzer (1132) is J ₄₅₂ The jones matrix is shown below, respectively:

wherein: e (E) ₀ For inputting the amplitude of the light E _0x E is the component of the input light in the x-axis direction ₀ Delta is the phase difference between counter-propagating beams caused by the faraday effect of the optical loop, for the component of the input light along the y-axis; the light vector of the main PINFET output is defined as E _out1 The light vector output by the first photodetector is defined as E _out2 The light vector output by the second photodetector is defined as E _out3 The light vector output by the third photodetector is defined as E _out4 The method comprises the following steps:

the light intensity of each path is respectively as follows according to the Malus law:

let S ₀ ＝P ₁ +P ₂ The stokes parameters of the recombined beam are calculated:

S ₁ ＝(P ₁ -P ₂ )/S ₀ ＝0

S ₂ ＝(2P ₃ -S ₀ )/S ₀ ＝cosδ

S ₃ ＝(2P ₄ -S ₀ )/S ₀ ＝sinδ

with increasing delta, the polarization state is on the bungjia sphere (S ₂ ，S ₃ ) Drawing a circle on the plane; delta is evaluated using an interpretation algorithm in a sine-cosine rotary encoder.

The invention also discloses a control method of the high fault tolerance system of the optical fiber current sensor, which is applicable to the energy industry, and comprises the following steps:

when the phase modulator normally operates, the output light of the main SLD light source (11) is normally output through the first coupler (21), the first power detector (31) monitors the state of the main SLD light source (11) through the first coupler (21), the output light is changed into two orthogonal linearly polarized lights with a phase difference of 90 degrees through the polarizer (41) and the 45-degree fusion point (42), the two orthogonal linearly polarized lights form two circularly polarized lights with opposite rotation directions after passing through the phase modulator (5), the 2 x 1 coupler (61), the delay line (7) and the optical fiber 1/4 wave plate (8), the two circularly polarized lights enter the sensing optical fiber ring (9) and are returned to the sensing optical fiber ring (9) after being acted by the reflecting mirror (10) at the tail end of the sensing optical fiber ring (9), the returned two circularly polarized lights pass through the optical fiber 1/4 wave plate (8) again and are converted into two orthogonal linearly polarized lights, and then sequentially return to the delay line (7), the 2 x 1 coupler (61), the phase modulator (5), the 45-degree fusion point (42) and the polarization modulator (41) to enter the main FPGA (19) through the four-phase modulator (19) and finally enter the main FPGA (19) through the main control unit (19) by adopting the digital FPGA;

when the phase modulator fails, light reflected by the reflecting mirror is received by the main PINFET (171), the first photoelectric detector (121), the second photoelectric detector (122) and the third photoelectric detector (123) through the 2X 1 coupler (61) respectively through the 45-degree fusion point (42) and the polarizer (41), the 0-degree analyzer (111), the 90-degree analyzer (112), the 1/4 wave plate (1131) and the 45-degree analyzer (1132), and digital signals are transmitted to the FPGA main control unit (19) through the fourth A/D converter (181), the first A/D converter (131), the second A/D converter (132) and the third A/D converter (133) respectively; the FPGA main control unit (19) carries out vector calculation on power signals of four light paths of the 45-degree fusion point (42) and the polarizer (41), the 0-degree analyzer (111), the 90-degree analyzer (112), the 1/4 wave plate (1131) and the 45-degree analyzer (1132), and carries out high fault tolerance control on the fiber current sensor.

The beneficial effects are that:

the invention provides a high fault tolerance system and a control method of an optical fiber current sensor, which are applicable to the energy industry. Meanwhile, the light vector output by the detector is related to Faraday phase shift, so that the current to be measured and the corresponding error of the device can be obtained by detecting the light vector. The invention not only ensures the reliable, safe and stable operation of the sensor in the degradation state of the device and reduces the loss caused by the fault of the optical fiber current sensor, but also has feasibility in operation, thereby providing a feasible method for the high fault tolerance control of the optical fiber current sensor.

Drawings

FIG. 1 is a schematic diagram of a control principle of a high fault tolerance system of an optical fiber current sensor applicable to the energy industry according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a typical architecture of a fiber optic current sensor;

the attached drawings are used for identifying and describing: 11 is a main SLD light source, 12 is a standby SLD light source, 21 is a first coupler, 22 is a second coupler, 23 is a third coupler, 31 is a first power detector, 32 is a second power detector, 41 is a polarizer, 42 is a 45 ° fusion point, 5 is a phase modulator, 61 is a 2×1 coupler, 62 is a 3×1 coupler, 7 is a delay line, 8 is an optical fiber 1/4 wave plate, 9 is a sensing optical fiber ring, 10 is a mirror, 111 is a 0 ° polarization analyzer, 112 is a 90 ° polarization analyzer, 1131 is a 1/4 wave plate, 1132 is a 45 ° polarization analyzer, 121 is a first photodetector, 122 is a second photodetector, 123 is a third photodetector, 131 is a first a/D converter, 132 is a second a/D converter, 133 is a third a/D converter, 14 is a D/a converter, 15 is a wire, 161 is a first light source control element, 162 is a second light source control element, 1131 is a 1/4 wave plate, 1132 is a 45 ° polarization analyzer, 1132 is a third light detector, 123 is a third photodetector, 131 is a third photodetector, 15 is a D/D converter, and 181 is a fifth light source control module, and a phase controller is a main controller, and is a 19/a fault-tolerant.

Detailed Description

The following examples will provide those skilled in the art with a more complete understanding of the invention, but are not intended to limit the invention in any way.

FIG. 2 is a schematic diagram of a typical architecture of a fiber optic current sensor; when the SLD light source, the power detector or the phase modulator fails, the whole fiber current sensor is abnormal. Based on the problem, the embodiment provides an optical fiber current sensor system and a high fault tolerance control method applicable to the energy industry, wherein the optical fiber current sensor high fault tolerance system comprises a light source/detector control module (200), a polarizer (41), a 45-degree fusion point (42), a phase modulator (5), a 2 x 1 coupler (61), a phase modulator fault tolerance control module (202), a delay line (7), a sensing module (201), a D/A converter (14) and an FPGA main control unit (19); the light source/detector control module (200) is composed of a main SLD light source (11), a standby SLD light source (12), a first coupler (21), a second coupler (22), a third coupler (23), a first power detector (31), a second power detector (32), a first light source control component (161), a second light source control component (162), a main PINFET (171), a standby PINFET (172), a fourth A/D converter (181) and a fifth A/D converter (182).

The phase modulator fault-tolerant control module (202) is composed of a 3X 1 coupler (62), a 0-degree analyzer (111), a 90-degree analyzer (112), a 1/4 wave plate (1131), a 45-degree analyzer (1132), a first photoelectric detector (121), a second photoelectric detector (122), a third photoelectric detector (123), a first A/D converter (131), a second A/D converter (132) and a third A/D converter (133).

The sensing module (201) consists of an optical fiber 1/4 wave plate (8), a sensing optical fiber ring (9), a reflecting mirror (10) and a current-carrying lead (15); the optical fiber current sensor comprises a main SLD light source (11), a first coupler (21), a third coupler (23), a polarizer (41), a 45-degree fusion point (42), a phase modulator (5), a delay line (7), an optical fiber 1/4 wave plate (8), a sensing optical fiber ring (9), a reflecting mirror (10), a D/A converter (14), a first light source control component (161), a main PINFET (171), a fourth A/D converter (181) and an FPGA main control unit (19) which are typical structures of the optical fiber current sensor.

The connection mode of each device of the high fault tolerance system of the optical fiber current sensor is as follows:

the light source/detector control module (200) is connected with the phase modulator (5) through the polarizer (41) and the 45-degree fusion point (42), and the phase modulator (5) and the phase modulator fault-tolerant control module (202) are connected with the sensing module through the 2X 1 coupler (61) and the delay line (7);

the primary SLD light source (11) and the primary PINFET (171) controlled by the first light source control component (161) are connected with the first power detector (31) and the third coupler (23) through the first coupler (21), the standby SLD light source (12) and the standby PINFET (172) controlled by the second light source control component (162) are connected with the second power detector (32) and the third coupler (23) through the second coupler (22), and the first coupler (21) is connected with the second coupler (22) in parallel and then connected with the third coupler (23) in series;

the first photoelectric detector (121), the second photoelectric detector (122) and the third photoelectric detector (123) are respectively connected with the 3X 1 coupler (62) through the 0-degree analyzer (111), the 90-degree analyzer (112), the 1/4 wave plate (1131) and the 45-degree analyzer (1132), and the polarization main axis of the 1/4 wave plate (1131) is parallel to the polarization main axis of the delay line (7);

the optical fiber 1/4 wave plate (8) is welded with the delay line (7) at 45 degrees, the end of the sensing optical fiber ring (9) is connected with the reflecting mirror (10), the sensing optical fiber ring (9) forms a ring, and the ring passes through the current-carrying lead (15).

The fault-tolerant control method of the optical fiber current sensor system comprises the following steps:

a: when the system is in normal operation, the output light of the main SLD light source (11) is normally output through the first coupler (21) and the third coupler (23), the first power detector (31) monitors the state of the main SLD light source (11) through the first coupler (21), the two orthogonal linearly polarized lights with the phase difference of 90 degrees are changed into two orthogonal linearly polarized lights after passing through the polarizer (41) and the 45-degree fusion point (42), the two orthogonal linearly polarized lights form two circularly polarized lights with opposite rotation directions after passing through the phase modulator (5), the 2 x 1 coupler (61), the delay line (7) and the optical fiber 1/4 wave plate (8), the two circularly polarized lights enter the sensing optical fiber ring (9) and are returned to the sensing optical fiber ring (9) after being acted by the reflecting mirror (10) at the tail end of the sensing optical fiber ring (9), the returned two circularly polarized lights pass through the optical fiber 1/4 wave plate (8) again and are converted into two orthogonal linearly polarized lights, and then sequentially return to the delay line (7), the 2 x 1 coupler (61), the phase modulator (5), the 45-degree fusion point (42) and the master controller (41) to the fourth FPGA (181) and finally enter the main FPGA (19) through the master controller (181).

B: when the first power detector (31) detects that the main SLD light source (11)/the main PINFET (171) is in fault, the FPGA main control unit (19) drives the first light source control component (161) to close the main SLD light source (11)/the main PINFET (171) and simultaneously drives the second light source control component (162) to open the standby SLD light source (12)/the standby PINFET (172), and light returned by the reflecting mirror (10) enters the standby PINFET (172) through the third coupler (23) and the second coupler (22), and finally reaches the FPGA main control unit (19) through the fifth A/D converter (182).

C: when the phase modulator fails, light reflected by the reflecting mirror is received by the main PINFET (171), the first photodetector (121), the second photodetector (122) and the third photodetector (123) through the 2X 1 coupler (61) respectively through the 45-degree fusion point (42) and the polarizer (41), the 0-degree analyzer (111), the 90-degree analyzer (112), the 1/4 wave plate (1131) and the 45-degree analyzer (1132), and digital signals are transmitted to the FPGA main control unit (19) through the fourth A/D converter (181), the first A/D converter (131), the second A/D converter (132) and the third A/D converter (133) respectively.

When the phase modulator fails, the reflected light returns from the 2X 1 coupler (61) to the main PINFET, the first photodetector, the second photodetector and the third photodetector, and the light vector entering the first 2X 1 coupler (61) is E _in Jones matrix of polarizer (41) is J _p Jones matrix of 45 ° fusion point (42) is J ₄₅₁ Jones matrix of 0 degree analyzer (111) is J ₀ Jones matrix of 90 degree analyzer (112) is J ₉₀ The Jones matrix of the 1/4 wave plate (1131) is J _b Jones matrix of 45 degree analyzer (1132) is J ₄₅₂ The jones matrix is shown below, respectively:

wherein: e (E) ₀ For inputting the amplitude of the light E _0x E is the component of the input light in the x-axis direction ₀ Delta is the phase difference between counter-propagating beams caused by the faraday effect of the optical loop for the component of the input light along the y-axis. Thus, the light vector output by the main PINFET is defined as E _out1 The light vector output by the first photodetector is defined as E _out2 The light vector output by the second photodetector is defined as E _out3 The light vector output by the third photodetector is defined as E _out4 The method comprises the following steps:

the light intensity of each path is respectively as follows according to the Malus law:

then let S ₀ ＝P ₁ +P ₂ Then the Stokes parameters of the recombined beam, S, can be calculated ₁ ＝(P ₁ -P ₂ )/S ₀ ，S ₂ ＝(2P ₃ -S ₀ )/S ₀ ，S ₃ ＝(2P ₄ -S ₀ )/S ₀ The following steps are:

S ₁ ＝(P ₁ -P ₂ )/S ₀ ＝0；

S ₂ ＝(2P ₃ -S ₀ )/S ₀ ＝cosδ；

S ₃ ＝(2P ₄ -S ₀ )/S ₀ ＝sinδ。

can seeIndicating that with increasing delta, the polarization state is on the bungjia sphere (S ₂ ，S ₃ ) A circle is drawn on the plane. In addition, stokes parameter S ₃ And S is ₂ Respectively representing the sine and cosine of the phase difference delta, which is (S ₂ ，S ₃ ) The polarization rotation angle on the plane or the polar angle of the polarization state on the bond sphere, therefore, δ can be accurately estimated using interpretation algorithms commonly used in sine-cosine rotary encoders.

In the embodiment, the light source/detector redundancy control module is used for controlling the power monitoring/output module by collecting small proportion of power in real time, when the power is continuously attenuated and the driving current of the light source is higher than the rated value, the primary fault tolerance failure of the light source is judged, the standby light source is started, and when the primary fault tolerance failure of the main light source/detector or the noise degradation of the detector is caused, the primary fault tolerance failure of the main light source/detector or the noise degradation of the detector is automatically switched into the standby light source/detector, so that the fault tolerance control of the light source/detector in the optical fiber current sensor is realized; the fault-tolerant control module of the phase modulator establishes an output light intensity equation of the 45-degree fusion point and the polarizer, the 1/4 wave plate and the 45-degree analyzer, the 0-degree analyzer and the 90-degree analyzer, when the degradation identification result is irrelevant to the phase modulator, the optical fiber current sensor adopts digital closed-loop control, otherwise, the main control unit of the optical fiber current sensor acquires power signals of four light paths of the 45-degree fusion point and the polarizer, the 1/4 wave plate and the 45-degree analyzer, the 0-degree analyzer and the 90-degree analyzer and carries out vector resolving, so that the high fault-tolerant control of the phase modulator is realized. The two fault-tolerant control modules are combined to realize reliable, safe and stable operation of the sensor in a device degradation state, so that the loss caused by the fault of the optical fiber current sensor is further reduced, and a feasible method is provided for high fault-tolerant control of the optical fiber current sensor.

The foregoing is merely a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, and all other embodiments obtained by those skilled in the art without making any inventive effort based on the embodiments of the present invention are within the scope of the present invention; any simple modification or equivalent variation of the above embodiments falls within the scope of the present invention.

Claims (4)

1. The high fault tolerance system of the optical fiber current sensor suitable for the energy industry is characterized by comprising a light source/detector control module (200), a polarizer (41), a 45-degree fusion point (42), a phase modulator (5), a 2X 1 coupler (61), a phase modulator fault tolerance control module (202), a delay line (7), a sensing module (201), a D/A converter (14) and an FPGA main control unit (19);

the light source/detector control module (200) comprises a main SLD light source (11), a first coupler (21), a first power detector (31), a first light source control component (161), a main PINFET (171) and a fourth A/D converter (181); the main SLD light source (11) and the main PINFET (171) controlled by the first light source control component (161) are connected with the first power detector (31) through the first coupler (21);

the phase modulator fault-tolerant control module (202) consists of a 3X 1 coupler (62), a 0-degree analyzer (111), a 90-degree analyzer (112), a 1/4 wave plate (1131), a 45-degree analyzer (1132), a first photoelectric detector (121), a second photoelectric detector (122), a third photoelectric detector (123), a first A/D converter (131), a second A/D converter (132) and a third A/D converter (133);

the sensing module (201) consists of an optical fiber 1/4 wave plate (8), a sensing optical fiber ring (9), a reflecting mirror (10) and a current-carrying lead (15); the optical fiber 1/4 wave plate (8) is welded with the delay line (7) at 45 degrees, the tail end of the sensing optical fiber ring (9) is connected with the reflecting mirror (10), the sensing optical fiber ring (9) forms a ring, and the ring passes through the current-carrying lead (15);

when the phase modulator normally operates, the output light of the main SLD light source (11) is normally output through the first coupler (21), the first power detector (31) monitors the state of the main SLD light source (11) through the first coupler (21), the output light is changed into two orthogonal linearly polarized lights with a phase difference of 90 degrees through the polarizer (41) and the 45-degree fusion point (42), the two orthogonal linearly polarized lights form two circularly polarized lights with opposite rotation directions after passing through the phase modulator (5), the 2 x 1 coupler (61), the delay line (7) and the optical fiber 1/4 wave plate (8), the two circularly polarized lights enter the sensing optical fiber ring (9) and are returned to the sensing optical fiber ring (9) after being acted by the reflecting mirror (10) at the tail end of the sensing optical fiber ring (9), the returned two circularly polarized lights pass through the optical fiber 1/4 wave plate (8) again and are converted into two orthogonal linearly polarized lights, and then sequentially return to the delay line (7), the 2 x 1 coupler (61), the phase modulator (5), the 45-degree fusion point (42) and the polarization modulator (41) to enter the main FPGA (19) through the four-phase modulator (19) and finally enter the main FPGA (19) through the main control unit (19) by adopting the digital FPGA;

when the phase modulator fails, light reflected by the reflecting mirror is received by the main PINFET (171), the first photoelectric detector (121), the second photoelectric detector (122) and the third photoelectric detector (123) through the 2X 1 coupler (61) respectively through the 45-degree fusion point (42) and the polarizer (41), the 0-degree analyzer (111), the 90-degree analyzer (112), the 1/4 wave plate (1131) and the 45-degree analyzer (1132), and digital signals are transmitted to the FPGA main control unit (19) through the fourth A/D converter (181), the first A/D converter (131), the second A/D converter (132) and the third A/D converter (133) respectively; the FPGA main control unit (19) carries out vector calculation on power signals of four light paths of the 45-degree fusion point (42) and the polarizer (41), the 0-degree analyzer (111), the 90-degree analyzer (112), the 1/4 wave plate (1131) and the 45-degree analyzer (1132), and carries out high fault tolerance control on the fiber current sensor.

2. The high fault tolerance system of the fiber optic current sensor suitable for use in the energy industry of claim 1, wherein the light source/detector control module (200) further comprises a backup SLD light source (12), a second coupler (22), a third coupler (23), a second power detector (32), a second light source control component (162), a backup PINFET (172), and a fifth a/D converter (182);

the standby SLD light source (12) and the standby PINFET (172) controlled by the second light source control component (162) are connected with the second power detector (32) and the third coupler (23) through the second coupler (22), and the first coupler (21) is connected with the second coupler (22) in parallel and then connected with the third coupler (23) in series;

when the first power detector (31) detects that the main SLD light source (11)/the main PINFET (171) is in fault, the FPGA main control unit (19) drives the first light source control component (161) to close the main SLD light source (11)/the main PINFET (171) and simultaneously drives the second light source control component (162) to open the standby SLD light source (12)/the standby PINFET (172), and light returned by the reflecting mirror (10) enters the standby PINFET (172) through the third coupler (23) and the second coupler (22), and finally reaches the FPGA main control unit (19) through the fifth A/D converter (182).

3. The high fault tolerance system of fiber optic current sensor for energy applications of claim 1, wherein when the phase modulator fails, it is assumed that the light vector entering the first 2 x 1 coupler (61) is E _in Jones matrix of polarizer (41) is J _p Jones matrix of 45 ° fusion point (42) is J ₄₅₁ Jones matrix of 0 degree analyzer (111) is J ₀ Jones matrix of 90 degree analyzer (112) is J ₉₀ The Jones matrix of the 1/4 wave plate (1131) is J _b Jones matrix of 45 degree analyzer (1132) is J ₄₅₂ The jones matrix is shown below, respectively:

wherein: e (E) ₀ For inputting the amplitude of the light E _0x E is the component of the input light in the x-axis direction ₀ Delta is the phase difference between counter-propagating beams caused by the faraday effect of the optical loop, for the component of the input light along the y-axis; the light vector of the main PINFET output is defined as E _out1 The light vector output by the first photodetector is defined as E _out2 The light vector output by the second photodetector is defined as E _out3 The light vector output by the third photodetector is defined as E _out4 The method comprises the following steps:

the light intensity of each path is respectively as follows according to the Malus law:

let S ₀ ＝P ₁ +P ₂ The stokes parameters of the recombined beam are calculated:

S ₁ ＝(P ₁ -P ₂ )/S ₀ ＝0

S ₂ ＝(2P ₃ -S ₀ )/S ₀ ＝cosδ

S ₃ ＝(2P ₄ -S ₀ )/S ₀ ＝sinδ

with increasing delta, the polarization state is on the bungjia sphere (S ₂ ，S ₃ ) Drawing a circle on the plane; delta is evaluated using an interpretation algorithm in a sine-cosine rotary encoder.

4. A control method of a high fault tolerance system based on the optical fiber current sensor applicable to the energy industry as claimed in any one of claims 1 to 3, characterized in that the control method comprises:

when the phase modulator normally operates, the output light of the main SLD light source (11) is normally output through the first coupler (21), the first power detector (31) monitors the state of the main SLD light source (11) through the first coupler (21), the output light is changed into two orthogonal linearly polarized lights with a phase difference of 90 degrees through the polarizer (41) and the 45-degree fusion point (42), the two orthogonal linearly polarized lights form two circularly polarized lights with opposite rotation directions after passing through the phase modulator (5), the 2 x 1 coupler (61), the delay line (7) and the optical fiber 1/4 wave plate (8), the two circularly polarized lights enter the sensing optical fiber ring (9) and are returned to the sensing optical fiber ring (9) after being acted by the reflecting mirror (10) at the tail end of the sensing optical fiber ring (9), the returned two circularly polarized lights pass through the optical fiber 1/4 wave plate (8) again and are converted into two orthogonal linearly polarized lights, and then sequentially return to the delay line (7), the 2 x 1 coupler (61), the phase modulator (5), the 45-degree fusion point (42) and the polarization modulator (41) to enter the main FPGA (19) through the four-phase modulator (19) and finally enter the main FPGA (19) through the main control unit (19) by adopting the digital FPGA;

when the phase modulator fails, light reflected by the reflecting mirror is received by the main PINFET (171), the first photoelectric detector (121), the second photoelectric detector (122) and the third photoelectric detector (123) through the 2X 1 coupler (61) respectively through the 45-degree fusion point (42) and the polarizer (41), the 0-degree analyzer (111), the 90-degree analyzer (112), the 1/4 wave plate (1131) and the 45-degree analyzer (1132), and digital signals are transmitted to the FPGA main control unit (19) through the fourth A/D converter (181), the first A/D converter (131), the second A/D converter (132) and the third A/D converter (133) respectively; the FPGA main control unit (19) carries out vector calculation on power signals of four light paths of the 45-degree fusion point (42) and the polarizer (41), the 0-degree analyzer (111), the 90-degree analyzer (112), the 1/4 wave plate (1131) and the 45-degree analyzer (1132), and carries out high fault tolerance control on the fiber current sensor.