A hybrid fiber-optic current sensing system and method for remote power monitoring

Abstract

This invention relates to the field of fiber optic current sensing technology, and particularly to a hybrid fiber optic current sensing system and method for long-distance power monitoring. The system includes: an optical interferometric sensing link, a remote current response probe, a photoelectric acquisition module, and a digital closed-loop control module. The optical interferometric sensing link includes a phase modulation section and a long-distance transmission section. The phase modulation section is used to load a phase-generated carrier into the detection light, and the long-distance transmission section is used to transmit and transmit the optical signal back. The photoelectric acquisition module is used to convert the optical signal into a digital interferometric signal. The digital closed-loop control module is used to extract orthogonal error and harmonic parameters based on the digital interferometric signal, and adjust the local carrier phase and carrier drive amplitude, thereby outputting the measurement result of the current to be measured. This invention effectively solves the core technical problem of insufficient anti-link disturbance capability in existing hybrid fiber optic current sensing systems for long-distance power monitoring, which leads to decreased measurement stability.

Description

Technical Field

[0001] This invention relates to the field of fiber optic current sensing technology, and in particular to a hybrid fiber optic current sensing system and method for long-distance power monitoring. Background Technology

[0002] With the development of smart grids, high-voltage power transmission and transformation, and long-distance power monitoring technologies, current measurement devices need to possess high insulation, electromagnetic interference resistance, wide-band response, and long-term operational stability. Although traditional electromagnetic current transformers are mature in application, they are easily limited by factors such as insulation structure, magnetic saturation, size, and long-distance signal transmission in high-voltage, high-current, and complex electromagnetic environments, making it difficult to meet the needs of distributed, long-distance, and high-precision monitoring. Therefore, fiber optic current sensing technology has gradually become an important development direction. Among them, the hybrid fiber optic current sensing scheme based on piezoelectric transducers and fiber optic gratings can use electrical sensing structures to obtain the electrical signal corresponding to the current to be measured, and cause changes in the optical parameters of the fiber optic grating through piezoelectric deformation, thereby taking into account both the sensitivity of traditional current sensing and the insulation safety of fiber optic transmission. It has the advantages of relatively simple structure, easy passive remote probe, and suitability for multi-point deployment. Existing hybrid fiber optic current sensing systems typically focus on sensor head structure design or fiber optic grating wavelength demodulation. While they can achieve the conversion of current to optical signals, in long-distance power monitoring scenarios, the transmission fiber is susceptible to temperature changes, mechanical vibrations, and on-site disturbances, causing unstable changes in the carrier phase and modulation state in the interference link. This leads to a decrease in the demodulation accuracy of the returned signal. At the same time, the piezoelectric modulation process itself is prone to modulation depth shifts due to device characteristics, load changes, and environmental influences, making it difficult for the system to maintain a stable linear operating state over a long period. Therefore, the core deficiency of existing technologies lies in their insufficient adaptive suppression capability against disturbances and modulation state drift in long-distance fiber optic links, making it difficult to guarantee the measurement stability and reliability of hybrid fiber optic current sensing systems in long-distance applications.

[0003] The information disclosed in this background section is intended only to enhance the understanding of the general background of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] This invention provides a hybrid fiber optic current sensing system and method for long-distance power monitoring, which can effectively solve the problems in the background art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A hybrid fiber optic current sensing system for long-distance power monitoring, the system comprising: Optical interference sensing link, remote current response probe, photoelectric acquisition module and digital closed-loop control module; The optical interference sensing link includes a phase modulation unit and a long-distance transmission unit. The phase modulation unit is used to perform interference modulation on the detection light and load a phase generation carrier to form an interference optical signal loaded with the phase generation carrier. The long-distance transmission unit is used to transmit the interference optical signal to the remote current response probe and to transmit the optical signal carrying the current to be measured to the photoelectric acquisition module via the long-distance transmission unit. The remote current response probe includes an electro-deformation unit and an optical sensing unit coupled to the electro-deformation unit. The electro-deformation unit is used to generate deformation in response to the electrical signal corresponding to the current to be measured. The optical sensing unit is used to generate optical parameter changes with the deformation and modulate the interference optical signal based on the optical parameter changes to form the optical signal carrying the information of the current to be measured. The photoelectric acquisition module is used to convert the optical signal into a digital interference signal; The digital closed-loop control module is used to extract orthogonal error and harmonic parameters based on the digital interference signal, and adaptively adjust the local carrier phase based on the orthogonal error to keep the local carrier in phase synchronization with the optical signal and compensate for the dynamic phase delay introduced by the long-distance transmission unit. It also adjusts the carrier drive amplitude of the phase modulation unit based on the proportional relationship of the harmonic parameters to lock the modulation depth of the phase generation carrier in a linear working state. After completing phase synchronization compensation and modulation depth locking, it performs demodulation calculation based on the harmonic parameters to output the measurement result of the current under test.

[0006] Furthermore, the optical interferometric sensing link includes: The optical interference sensing link includes a broadband light source, a first coupler, a modulation arm, a delay arm, a second coupler, and a circulator; The broadband light source is connected to the first coupler via a single-mode optical fiber, so that the detection light output by the broadband light source is split into two optical signals by the first coupler. One optical signal is transmitted through the modulation arm, and the other optical signal is transmitted through the delay arm. The two optical signals are coupled at the second coupler to form an unbalanced Mach-Zehnder interference optical signal. The output of the second coupler is connected to the circulator via a single-mode optical fiber, so that the unbalanced Mach-Zehnder interference optical signal enters the long-distance transmission section through the circulator.

[0007] Furthermore, the modulation arm and the delay arm include: The modulation arm includes a first piezoelectric transducer, which is used to receive the high-frequency carrier drive signal output by the digital closed-loop control module and to perform phase modulation on the detection light passing through the modulation arm. The first piezoelectric transducer is a piezoelectric ceramic transducer, and a fiber grating is provided on the first piezoelectric transducer so that a phase is loaded in the detection light through the mechanical deformation of the first piezoelectric transducer to generate a carrier wave; The delay arm includes a tunable delay line and a compensation fiber, which are used to form an unbalanced optical path difference with the modulation arm.

[0008] Furthermore, the long-distance transmission unit includes: The long-distance transmission unit includes a long-distance polarization-maintaining fiber, one end of which is connected to the optical interference sensing link via the circulator. The other end of the long-distance polarization-maintaining fiber is connected to the far-end current response probe to transmit the unbalanced Mach-Zehnder interference optical signal loaded with the phase generation carrier to the far-end current response probe. The long-distance polarization-maintaining fiber is used to transmit the reflected light signal carrying the current information to be measured from the remote current response probe back to the circulator. The circulator is used to guide the reflected light signal to the photoelectric acquisition module to realize the long-distance transmission and return of the unbalanced Mach-Zehnder interference light signal.

[0009] Furthermore, the remote current response probe includes: The remote current response probe includes a second piezoelectric transducer and a fiber grating coupled to the second piezoelectric transducer; The second piezoelectric transducer is connected to the load resistor on the secondary side of the current transformer under test via a voltage transmission cable to receive the secondary voltage signal corresponding to the current under test. The second piezoelectric transducer is used to generate piezoelectric deformation according to the secondary side voltage signal, and the fiber grating is used to generate wavelength drift with the piezoelectric deformation.

[0010] Furthermore, the photoelectric acquisition module includes: The photoelectric acquisition module includes a photodetector and an analog-to-digital converter; The photodetector is connected to the reflection output terminal of the circulator to receive the reflected light signal transmitted back through the long-distance transmission unit; The photodetector is used to convert the reflected light signal into an electrical signal, and the analog-to-digital converter is used to sample the electrical signal and generate a digital interference signal; The analog-to-digital converter is connected to the digital closed-loop control module to input the digital interference signal into the digital closed-loop control module for demodulation and feedback control.

[0011] Furthermore, the digital closed-loop control module extracts orthogonal error and harmonic parameters, including: The digital closed-loop control module includes an ADC sampling module, a digital multiplication array, a low-pass filter, and a numerically controlled oscillator; The ADC sampling module is used to receive the digital interference signal and input the digital interference signal into the digital multiplication array; The numerically controlled oscillator is used to generate a carrier in-phase reference signal, a carrier quadrature reference signal, and a second harmonic reference signal; The digital multiplication array is used to multiply the digital interference signal with the carrier in-phase reference signal, the carrier quadrature reference signal and the second harmonic reference signal respectively, and after filtering by the low-pass filter, obtain the quadrature error value, the first harmonic component and the second harmonic component.

[0012] Furthermore, the digital closed-loop control module also includes: The quadrature error value is input to the first feedback controller, so that the first feedback controller generates a phase compensation value based on the quadrature error value; The phase compensation value is fed back to the numerically controlled oscillator to adjust the phase step of the numerically controlled oscillator; The numerically controlled oscillator adjusts the phases of the carrier in-phase reference signal, the carrier quadrature reference signal, and the second harmonic reference signal according to the phase compensation value; The digital closed-loop control module compensates for the dynamic phase delay introduced by the long-distance transmission unit by making the orthogonal error value approach zero.

[0013] Furthermore, the digital closed-loop control module performs harmonic proportional servo control and current calculation, including: The input ratio calculation and deviation extraction module of the first-order harmonic component and the second-order harmonic component is used to obtain the harmonic ratio deviation signal used to characterize the modulation depth deviation. The harmonic proportional deviation signal is input to the second feedback controller so that the second feedback controller outputs a gain coefficient. The gain coefficient is multiplied by the sine wave generated by the numerically controlled oscillator to form a modulation signal applied to the first piezoelectric transducer; The modulation signal is used to adjust the carrier drive amplitude of the first piezoelectric transducer in order to lock the modulation depth of the phase-generated carrier. The first-order harmonic component and the second-order harmonic component are input into the arctangent calculation module to obtain the current measurement result corresponding to the current to be measured.

[0014] A hybrid fiber optic current sensing method for long-distance power monitoring, the method comprising: The detection light is subjected to interference modulation and a phase-generating carrier is loaded to form an interference light signal loaded with the phase-generating carrier; The interference optical signal is transmitted to the remote current response probe, and the interference optical signal is applied to the optical sensing unit. The optical sensing element deforms in response to the electrical signal corresponding to the current to be measured, causing the optical parameters of the optical sensing element to change accordingly. Based on the change in optical parameters, the interference light signal is modulated to form an optical signal carrying the information of the current to be measured. The optical signal carrying the changes in the optical parameters is transmitted to the photoelectric acquisition module via a long-distance transmission unit, and the photoelectric acquisition module converts the optical signal into a digital interference signal. The orthogonal error and harmonic parameters are extracted from the digital interference signal, and a carrier phase adjustment amount is generated based on the orthogonal error to compensate for the dynamic phase delay of the long-distance transmission unit. The local carrier phase is adaptively adjusted based on the carrier phase adjustment amount to keep the local carrier in phase synchronization with the optical signal. Based on the proportional relationship of the harmonic parameters, a carrier amplitude adjustment amount is generated, and the carrier drive amplitude of the phase modulation unit is adjusted according to the carrier amplitude adjustment amount, so that the modulation depth of the phase generated carrier is locked in a linear working state. After completing the phase synchronization and modulation depth locking, demodulation calculation is performed based on the harmonic parameters to output the measurement result of the current to be measured.

[0015] The technical solution of this invention can achieve the following technical effects: By loading a phase-generated carrier wave through an optical interferometric sensing link and transmitting the interferometric optical signal over a long distance to a remote current response probe, the remote probe converts the current to be measured into changes in optical parameters and transmits them back to the photoelectric acquisition module to form a digital interferometric signal. Then, the digital closed-loop control module compensates for the dynamic phase delay of the link based on orthogonal error and locks the modulation depth based on harmonic ratio, and finally demodulates and outputs the measurement result of the current to be measured. This effectively solves the core technical problem of insufficient anti-link disturbance capability in existing hybrid fiber optic current sensing systems for long-distance power monitoring, which leads to a decrease in measurement stability.

[0016] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a hybrid fiber optic current sensing system for long-distance power monitoring. Figure 2 This is a block diagram of the dual closed-loop feedback logic inside the FPGA processing unit. Figure 3 This is a flowchart illustrating a hybrid fiber optic current sensing method for long-distance power monitoring. Figure reference numerals: 1. Broadband light source; 2. Single-mode fiber; 3. First coupler; 4. Single-mode fiber; 5. First piezoelectric transducer; 6. Single-mode fiber; 7. Single-mode fiber; 8. Tunable delay line; 9. Compensated single-mode fiber; 10. Second coupler; 11. Single-mode fiber; 12. Circulator; 13. Long-distance polarization-maintaining fiber; 14. Second piezoelectric transducer; 15. Cable for transmitting electrical signals corresponding to the measured current; 16. Photodetector; 17. Analog-to-digital converter; 18. FPGA processing unit; 19. ADC sampling module; 20. Digital 21. Interference signal Vin; 22. Digital mixing and low-pass filtering module; 23. Quadrature error value; 24. First feedback controller; 25. Carrier phase compensation amount ΔPCW; 26. Numerically controlled oscillator NCO; 27. Local carrier in-phase reference signal, local carrier quadrature reference signal and second harmonic reference signal; 28. First harmonic component and second harmonic component; 29. ​​Ratio calculation and deviation extraction module and second feedback controller; 30. Modulation gain G; 31. Local carrier sinusoidal signal; 32. Carrier drive signal; 33. Current demodulation calculation module. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Example 1; like Figure 1 and Figure 2 As shown, this application provides a hybrid fiber optic current sensing system for long-distance power monitoring, the system comprising: Optical interference sensing link, remote current response probe, photoelectric acquisition module and digital closed-loop control module; The optical interferometric sensing link includes a phase modulation unit and a long-distance transmission unit. The phase modulation unit is used to perform interferometric modulation on the detection light and load a phase generation carrier to form an interferometric optical signal loaded with a phase generation carrier. The long-distance transmission unit is used to transmit the interferometric optical signal to the remote current response probe and to transmit the optical signal carrying the current to be measured to the photoelectric acquisition module via the long-distance transmission unit. The remote current response probe includes an electro-deformation unit and an optical sensing unit coupled to the electro-deformation unit. The electro-deformation unit is used to generate deformation in response to the electrical signal corresponding to the current to be measured. The optical sensing unit is used to generate changes in optical parameters with the deformation and modulate the interference light signal based on the changes in optical parameters to form an optical signal carrying the information of the current to be measured. The photoelectric acquisition module is used to convert optical signals into digital interference signals; The digital closed-loop control module is used to extract orthogonal error and harmonic parameters from the digital interference signal, and adaptively adjust the local carrier phase based on the orthogonal error to keep the local carrier in phase synchronization with the optical signal and compensate for the dynamic phase delay introduced by the long-distance transmission unit. It also adjusts the carrier drive amplitude of the phase modulation unit based on the proportional relationship of the harmonic parameters to lock the modulation depth of the phase generation carrier in a linear working state. After completing phase synchronization compensation and modulation depth locking, it performs demodulation calculation based on the harmonic parameters to output the measurement result of the current under test.

[0022] Specifically, in one embodiment, the present invention provides a hybrid fiber optic current sensing system for long-distance power monitoring, comprising an optical interferometric sensing link, a remote current response probe, a photoelectric acquisition module, and a digital closed-loop control module; the optical interferometric sensing link is used to generate and transmit an interferometric optical signal carrying a phase generation carrier; the remote current response probe is used to convert the electrical signal corresponding to the current under test into an optical parameter change; the photoelectric acquisition module is used to convert the return optical signal into a digital interferometric signal; and the digital closed-loop control module is used to demodulate, compensate the phase, and control the modulation depth of the digital interferometric signal. Specifically, the optical interferometric sensing link includes a broadband light source, a first coupler, a modulation arm, a delay arm, a second coupler, a circulator, and a long-distance polarization-maintaining fiber. The detection light output from the broadband light source is input to the first coupler via a single-mode fiber and split into two optical signals. One optical signal enters the modulation arm, and the other enters the delay arm. A first piezoelectric transducer is installed on the modulation arm. Under the action of the carrier drive signal output by the digital closed-loop control module, the first piezoelectric transducer undergoes mechanical deformation, thereby modulating the phase of the detection light passing through the modulation arm to load a phase and generate a carrier in the detection light. A tunable delay line and a compensation fiber are installed on the delay arm to form an unbalanced optical path difference with the modulation arm. The two optical signals are recoupled at the second coupler to form an unbalanced interferometric optical signal, which then enters the long-distance polarization-maintaining fiber via the circulator. Long-distance polarization-maintaining fiber serves as the long-distance transmission unit in the optical interferometric sensing link. One end of the fiber is connected to the unbalanced interference structure via a circulator, and the other end is connected to the remote current response probe. The long-distance polarization-maintaining fiber is used to transmit the interferometric light signal loaded with a phase generation carrier to the remote current response probe, and to transmit the reflected light signal modulated by the remote current response probe back to the circulator. The remote current response probe includes a second piezoelectric transducer and a fiber optic grating coupled to the second piezoelectric transducer. The second piezoelectric transducer is connected to the load resistor on the secondary side of the current transformer under test through a voltage transmission cable. The current under test is converted into a secondary side voltage signal by the current transformer and then applied to the second piezoelectric transducer. The second piezoelectric transducer responds to the secondary side voltage signal by generating piezoelectric deformation. The fiber optic grating undergoes wavelength drift or corresponding optical parameter changes with the piezoelectric deformation, so that the returned optical signal carries the information of the current under test. The photoelectric acquisition module includes a photodetector and an analog-to-digital converter. The reflected light signal transmitted back through a long-distance polarization-maintaining fiber is guided to the photodetector by a circulator. The photodetector converts the reflected light signal into an electrical signal. The analog-to-digital converter samples the electrical signal and generates a digital interference signal, which is then input to the digital closed-loop control module. The digital closed-loop control module can be implemented by an FPGA processing unit. After receiving the digital interference signal, the digital closed-loop control module generates a carrier in-phase reference signal, a carrier quadrature reference signal, and a second harmonic reference signal through an internal numerically controlled oscillator. The digital interference signal is then digitally mixed with the carrier in-phase reference signal, the carrier quadrature reference signal, and the second harmonic reference signal, respectively. After low-pass filtering, the quadrature error value, the first harmonic component, and the second harmonic component are obtained. The digital closed-loop control module performs carrier synchronization compensation control based on the quadrature error value. Specifically, the quadrature error value is input to the first feedback controller, which generates a phase compensation value based on the quadrature error value and feeds the phase compensation value back to the numerically controlled oscillator to adjust the phase step of the numerically controlled oscillator so that the quadrature error value approaches the locked state, thereby compensating for the dynamic phase delay introduced by environmental disturbances in long-distance polarization-maintaining optical fibers. The digital closed-loop control module also performs harmonic proportional servo control based on the first-order and second-order harmonic components. Specifically, the first-order and second-order harmonic components are input to the ratio calculation and deviation extraction module to obtain a harmonic proportional deviation signal that characterizes the modulation depth offset. The harmonic proportional deviation signal is input to the second feedback controller, and the second feedback controller outputs a gain coefficient. The gain coefficient is used to adjust the amplitude of the carrier drive signal applied to the first piezoelectric transducer so that the modulation depth of the phase-generated carrier is kept in a working state suitable for linear demodulation. After completing carrier synchronization compensation and harmonic proportional servo control, the digital closed-loop control module performs arctangent demodulation calculation based on the first-order and second-order harmonic components to obtain the current measurement result corresponding to the current to be measured. Thus, this embodiment realizes the optical conversion of current information through a remote piezoelectric fiber optic grating probe, and simultaneously compensates for long-distance transmission link disturbances and modulation depth drift through the digital closed-loop control module, thereby improving the measurement stability of the hybrid fiber optic current sensing system in long-distance power monitoring.

[0023] The technical solution of this invention loads a phase-generated carrier wave in the optical interferometric sensing link and transmits the interferometric optical signal over a long distance to the remote current response probe. The remote probe converts the current to be measured into changes in optical parameters and transmits them back to the photoelectric acquisition module to form a digital interferometric signal. Then, the digital closed-loop control module compensates for the dynamic phase delay of the link based on orthogonal error and locks the modulation depth based on harmonic ratio, and finally demodulates and outputs the measurement result of the current to be measured. This effectively solves the core technical problem of insufficient anti-link disturbance capability of existing hybrid fiber optic current sensing systems in long-distance power monitoring, which leads to a decrease in measurement stability.

[0024] Furthermore, the optical interferometry sensing link includes: The optical interferometric sensing link includes a broadband light source, a first coupler, a modulation arm, a delay arm, a second coupler, and a circulator; A broadband light source is connected to a first coupler via a single-mode optical fiber, so that the detection light output from the broadband light source is split into two optical signals by the first coupler; One optical signal is transmitted through the modulation arm, and the other optical signal is transmitted through the delay arm. The two optical signals are coupled at the second coupler to form an unbalanced Mach-Zehnder interference optical signal. The output of the second coupler is connected to the circulator via a single-mode fiber, so that the unbalanced Mach-Zehnder interference optical signal enters the long-distance transmission section through the circulator.

[0025] As a preferred embodiment of the above, the optical interference sensing link includes a broadband light source, a first coupler, a modulation arm, a delay arm, a second coupler, and a circulator; the broadband light source serves as the input source of the detection light, and its output end is connected to the first coupler through a single-mode optical fiber, so that the detection light output by the broadband light source is split into two optical signals after entering the first coupler; One optical signal enters the modulation arm, and the other optical signal enters the delay arm. The modulation arm is used to load the phase of the incoming optical signal to generate a carrier wave, and the delay arm is used to form an unbalanced optical path condition with the modulation arm, so that the two optical signals can produce unbalanced interference during subsequent coupling. In one specific embodiment, one optical signal entering the modulation arm is transmitted sequentially through a single-mode fiber, a first piezoelectric transducer, and another single-mode fiber, while the other optical signal entering the delay arm is transmitted sequentially through a single-mode fiber, a tunable delay line, and a compensated single-mode fiber. The optical signals output from the modulation arm and the delay arm are respectively input to the second coupler and recoupled at the second coupler to form an unbalanced Mach-Zehnder interference optical signal. The output of the second coupler is connected to the circulator through a single-mode fiber, so that the unbalanced Mach-Zehnder interference optical signal enters the subsequent long-distance transmission path through the circulator, so as to be transmitted to the remote current response probe and form a return detection optical path.

[0026] Furthermore, the modulation arm and delay arm include: The modulation arm includes a first piezoelectric transducer, which is used to receive the high-frequency carrier drive signal output by the digital closed-loop control module and to perform phase modulation on the detection light passing through the modulation arm. The first piezoelectric transducer is a piezoelectric ceramic transducer, and a fiber grating is provided on the first piezoelectric transducer so that the phase is loaded in the detection light through the mechanical deformation of the first piezoelectric transducer to generate a carrier wave. The delay arm includes a tunable delay line and a compensation fiber, which are used to form an unbalanced optical path difference with the modulation arm.

[0027] As a preferred embodiment of the above, the modulation arm includes a single-mode optical fiber, a first piezoelectric transducer, and a single-mode optical fiber. The first piezoelectric transducer is disposed in the optical path of the modulation arm and connected to the carrier drive output terminal of the digital closed-loop control module. After the digital closed-loop control module outputs a high-frequency carrier drive signal to the first piezoelectric transducer, the first piezoelectric transducer undergoes periodic mechanical deformation under the action of the high-frequency carrier drive signal, thereby generating phase modulation on the detection light passing through the modulation arm, so that the detection light is loaded with phase to generate a carrier. The first piezoelectric transducer is a piezoelectric ceramic transducer with a fiber grating on it. The fiber grating undergoes strain changes with the mechanical deformation of the first piezoelectric transducer, so that the optical signal passing through the modulation arm obtains a phase modulation amount corresponding to the high-frequency carrier drive signal, thereby forming a phase generation carrier for subsequent interference demodulation. In the same specific embodiment, the delay arm includes a single-mode fiber, a tunable delay line, and a compensating single-mode fiber; the tunable delay line and the compensating single-mode fiber are disposed in the delay arm to adjust the optical path difference between the delay arm and the modulation arm, so that the optical signal output by the modulation arm and the optical signal output by the delay arm are coupled at the second coupler to form an unbalanced Mach-Zehnder interference optical signal. In one specific embodiment, the first piezoelectric transducer is a PZT of model PSt150 / 5 / 5 with a capacitance of 1.8μF and an open-circuit resonant frequency of 120kHz. The fiber grating on the first piezoelectric transducer has a grating region length of 5cm, is coated with acrylate, has a reflectivity of 90%, and is fixed to the first piezoelectric transducer by adhesive to ensure that the fiber grating can deform stably with the first piezoelectric transducer. Thus, the modulation arm achieves phase generation carrier loading through the first piezoelectric transducer, and the delay arm provides unbalanced optical path conditions through the tunable delay line and the compensated single-mode fiber. Together, they constitute the unbalanced interference modulation structure in the optical interference sensing link, providing carrier-loaded interference optical signals for subsequent carrier synchronization compensation, harmonic ratio servoing, and current demodulation.

[0028] Furthermore, the long-distance transmission unit includes: The long-distance transmission unit includes a long-distance polarization-maintaining fiber, one end of which is connected to an optical interference sensing link via a circulator. The other end of the long-distance polarization-maintaining fiber is connected to the remote current response probe to transmit the unbalanced Mach-Zehnder interference optical signal loaded with a phase generation carrier to the remote current response probe. Long-distance polarization-maintaining optical fiber is used to transmit the reflected light signal carrying the current to be measured from the remote current response probe back to the circulator. The circulator is used to guide the reflected light signal to the photoelectric acquisition module to realize the long-distance transmission and return of unbalanced Mach-Zehnder interference light signals.

[0029] As a preferred embodiment of the above, the long-distance transmission unit includes a long-distance polarization-maintaining fiber, which is disposed between the circulator and the remote current response probe to establish a long-distance optical signal transmission path between the optical interference sensing link and the remote current response probe. One end of the long-distance polarization-maintaining fiber is connected to the circulator, and the other end of the long-distance polarization-maintaining fiber is connected to the remote current response probe, so that the unbalanced Mach-Zehnder interference optical signal loaded with a phase generation carrier can enter the long-distance polarization-maintaining fiber through the circulator and be transmitted to the remote current response probe along the long-distance polarization-maintaining fiber. After receiving the unbalanced Mach-Zehnder interferometric optical signal transmitted over a long-distance polarization-maintaining fiber, the remote current response probe generates optical parameter changes based on the electrical signal corresponding to the current to be measured, transforming the unbalanced Mach-Zehnder interferometric optical signal into a reflected optical signal carrying information about the current to be measured. The reflected optical signal is then transmitted back to the circulator via the long-distance polarization-maintaining fiber, thus forming a round-trip optical signal transmission path from the optical interference sensing link to the remote current response probe and then back from the remote current response probe to the photoelectric acquisition module. In one specific embodiment, the output of the second coupler is connected to the circulator via a single-mode optical fiber. The circulator is connected to the remote current response probe via a long-distance polarization-maintaining optical fiber. The remote current response probe includes a second piezoelectric transducer. After the unbalanced Mach-Zehnder interference optical signal reaches the second piezoelectric transducer via the long-distance polarization-maintaining optical fiber, it carries the current information to be measured and returns to the circulator. Subsequently, the circulator guides the returned reflected optical signal to the subsequent photoelectric acquisition module. Therefore, the long-distance transmission unit not only realizes the long-distance transmission of unbalanced Mach-Zehnder interference optical signals to the remote current response probe, but also realizes the return transmission of reflected optical signals carrying the current information to be measured, providing input signals for the subsequent photoelectric acquisition module to generate digital interference signals and for the digital closed-loop control module to perform carrier synchronization compensation and harmonic proportional servo.

[0030] Furthermore, the remote current response probe includes: The remote current response probe includes a second piezoelectric transducer and a fiber grating coupled to the second piezoelectric transducer; The second piezoelectric transducer is connected to the load resistor on the secondary side of the current transformer under test via the voltage transmission cable under test, so as to receive the secondary side voltage signal corresponding to the current under test. The second piezoelectric transducer is used to generate piezoelectric deformation based on the secondary side voltage signal, and the fiber grating is used to generate wavelength drift with the piezoelectric deformation.

[0031] As a preferred embodiment of the above, the remote current response probe includes a second piezoelectric transducer and a fiber optic grating coupled to the second piezoelectric transducer; the second piezoelectric transducer serves as an electro-deformation unit, used to respond to the electrical signal corresponding to the current to be measured and generate piezoelectric deformation; the fiber optic grating serves as an optical sensing unit, used to generate optical parameter changes with the piezoelectric deformation of the second piezoelectric transducer, so that the optical signal transmitted to the remote current response probe via the long-distance transmission unit carries the information of the current to be measured; In the same specific embodiment, the second piezoelectric transducer is connected to the load resistor on the secondary side of the current transformer under test through a signal transmission cable corresponding to the current under test; after the current under test is converted into a secondary side voltage signal by the current transformer under test, the secondary side voltage signal is applied to the second piezoelectric transducer through the signal transmission cable corresponding to the current under test, causing the second piezoelectric transducer to produce a deformation corresponding to the secondary side voltage signal; In one specific embodiment, the second piezoelectric transducer is a ceramic ring made of PZT-5A material, and the radial resonant frequency of the second piezoelectric transducer is 60kHz; a fiber grating is disposed on the second piezoelectric transducer, the grating region of the fiber grating is 5cm long, the coating material is acrylic ester, the reflectivity is 90%, and it is fixed to the second piezoelectric transducer with 502 glue to ensure that the fiber grating can deform stably with the second piezoelectric transducer; Therefore, the remote current response probe can convert the secondary side electrical signal corresponding to the current under test into the piezoelectric deformation of the second piezoelectric transducer, and further into the wavelength drift or other optical parameter changes of the fiber grating, thereby realizing the optical encoding of the current under test information in the remote passive probe, providing a basis for the photoelectric acquisition and digital closed-loop demodulation of the subsequent transmitted optical signal.

[0032] Furthermore, the photoelectric acquisition module includes: The photoelectric acquisition module includes a photodetector and an analog-to-digital converter; The photodetector is connected to the reflection output terminal of the circulator to receive the reflected light signal transmitted back via the long-distance transmission unit; A photodetector is used to convert reflected light signals into electrical signals, and an analog-to-digital converter is used to sample the electrical signals and generate digital interference signals. The analog-to-digital converter is connected to the digital closed-loop control module to input the digital interference signal into the digital closed-loop control module for demodulation and feedback control.

[0033] As a preferred embodiment of the above, the photoelectric acquisition module includes a photodetector and an analog-to-digital converter; the photodetector is connected to the reflection output terminal of the circulator and is used to receive the reflected light signal carrying the current information to be measured that is transmitted back through the long-distance transmission unit, and convert the reflected light signal into a corresponding electrical signal. In the same specific embodiment, the analog-to-digital converter is connected between the photodetector and the digital closed-loop control module to sample and convert the electrical signal output by the photodetector to generate a digital interference signal that can be processed by the digital closed-loop control module. In one specific embodiment, the photodetector is the photodetector marked in the figure, the analog-to-digital converter is the analog-to-digital converter marked in the figure, the optical signal output from the circulator return end first enters the photodetector, and then the photodetector outputs an electrical signal to the analog-to-digital converter, and the analog-to-digital converter inputs the sampled digital interference signal to the FPGA processing unit; Therefore, the photoelectric acquisition module can convert the long-distance transmitted optical detection signal into the digital interference signal required for subsequent digital closed-loop control, providing the input basis for the digital closed-loop control module to perform orthogonal error extraction, carrier synchronization compensation, harmonic proportional servo and current calculation.

[0034] Furthermore, the digital closed-loop control module extracts orthogonal error and harmonic parameters, including: The digital closed-loop control module includes an ADC sampling module, a digital multiplication array, a low-pass filter, and a numerically controlled oscillator; The ADC sampling module is used to receive digital interference signals and input them into the digital multiplication array; Numerical control oscillators are used to generate carrier in-phase reference signals, carrier quadrature reference signals, and frequency-doubled reference signals; The digital multiplication array is used to multiply the digital interference signal with the carrier in-phase reference signal, the carrier quadrature reference signal, and the second harmonic reference signal, respectively, and then filter them through a low-pass filter to obtain the quadrature error value, the first harmonic component, and the second harmonic component.

[0035] As a preferred embodiment of the above, the digital closed-loop control module includes an ADC sampling module, a digital multiplication array, a low-pass filter, and a digitally controlled oscillator; the ADC sampling module is used to receive the digital interference signal output by the photoelectric acquisition module and input the digital interference signal into the digital multiplication array for subsequent digital mixing processing; In the same specific embodiment, the numerically controlled oscillator is used to generate multiple local reference signals, including a carrier in-phase reference signal, a carrier quadrature reference signal, and a second harmonic reference signal; the carrier in-phase reference signal and the carrier quadrature reference signal are used to perform quadrature demodulation on the digital interference signal, and the second harmonic reference signal is used to extract the second harmonic information related to the phase-generated carrier. In one specific embodiment, the digital interference signal Vin from the analog-to-digital converter is input to the ADC sampling module and enters the digital multiplication array and low-pass filter; the carrier in-phase reference signal, carrier quadrature reference signal and second harmonic reference signal output by the numerically controlled oscillator are multiplied by the digital interference signal Vin, and then filtered by the low-pass filter to obtain three DC envelope signals, which include quadrature error, first harmonic component and second harmonic component; Therefore, the digital closed-loop control module can synchronously extract the orthogonal error for carrier synchronization control, as well as the first-order and second-order harmonic components for harmonic proportional servo and current calculation from the digital interference signal, providing a digital signal basis for subsequent dynamic phase delay compensation, modulation depth locking and current output under test.

[0036] Furthermore, the digital closed-loop control module also includes: The quadrature error value is input to the first feedback controller so that the first feedback controller generates a phase compensation value based on the quadrature error value; The phase compensation value is fed back to the numerically controlled oscillator to adjust the phase step of the numerically controlled oscillator; The numerically controlled oscillator adjusts the phase of the carrier in-phase reference signal, the carrier quadrature reference signal, and the second harmonic reference signal according to the phase compensation value; The digital closed-loop control module compensates for the dynamic phase delay introduced by the long-distance transmission unit by making the quadrature error value approach zero.

[0037] As a preferred embodiment of the above, the digital closed-loop control module performs feedback adjustment on the numerically controlled oscillator according to the orthogonal error to achieve adaptive synchronization between the local carrier phase and the carrier phase of the return interference signal; the orthogonal error is obtained by mixing and low-pass filtering the digital interference signal and the carrier orthogonal reference signal, and the orthogonal error is used to characterize the dynamic phase deviation state introduced by the long-distance transmission unit. In the same specific embodiment, the quadrature error is input to the first feedback controller, which calculates the phase compensation amount based on the quadrature error. The phase compensation amount is fed back to the phase control terminal of the numerically controlled oscillator, causing the numerically controlled oscillator to adjust its phase step according to the phase compensation amount, thereby synchronously adjusting the phase states of the carrier in-phase reference signal, the carrier quadrature reference signal, and the second harmonic reference signal generated by the numerically controlled oscillator. In one specific embodiment, the first feedback controller is a PI controller. After the quadrature error is input to the PI controller, the PI controller calculates the phase compensation value ΔPCW. The phase compensation value ΔPCW is fed back to the NCO numerically controlled oscillator, so that the NCO numerically controlled oscillator dynamically changes the phase step and forces the quadrature error to approach zero. Therefore, the digital closed-loop control module can compensate for the dynamic phase delay caused by environmental disturbances in the long-distance transmission section in real time through the closed-loop path of "orthogonal error - first feedback controller - phase compensation amount - numerically controlled oscillator", so that the returned interference signal and the local reference signal are kept in carrier synchronization state, providing a stable phase reference for subsequent harmonic proportional servo and demodulation of the current under test.

[0038] Furthermore, the digital closed-loop control module performs harmonic proportional servo control and current calculation, including: A module for calculating the input ratio of the first-order harmonic component and the second-order harmonic component and extracting the deviation is used to obtain a harmonic ratio deviation signal for characterizing the modulation depth deviation. The harmonic ratio deviation signal is input to the second feedback controller so that the second feedback controller outputs the gain coefficient. The gain coefficient is multiplied by the sine wave generated by the numerically controlled oscillator to form a modulation signal applied to the first piezoelectric transducer; The modulation signal is used to adjust the carrier drive amplitude of the first piezoelectric transducer to lock the modulation depth of the phase-generated carrier; The first-order harmonic component and the second-order harmonic component are input into the arctangent calculation module to obtain the current measurement result corresponding to the current to be measured.

[0039] As a preferred embodiment of the above, the digital closed-loop control module performs harmonic proportional servo control based on the first-order harmonic component and the second-order harmonic component to perform closed-loop adjustment of the carrier drive amplitude of the phase modulation section; the first-order harmonic component and the second-order harmonic component are obtained by mixing and low-pass filtering the digital interference signal with the reference signal generated by the numerically controlled oscillator, respectively; the proportional relationship between the first-order harmonic component and the second-order harmonic component is used to characterize the modulation depth deviation state of the phase generation carrier. In the same specific embodiment, the first-order harmonic component and the second-order harmonic component are input to the ratio calculation and deviation extraction module. The ratio calculation and deviation extraction module calculates the harmonic ratio relationship based on the first-order harmonic component and the second-order harmonic component, and extracts the harmonic ratio deviation signal used to characterize the modulation depth deviation. The harmonic ratio deviation signal is input to the second feedback controller. The second feedback controller outputs the modulation gain G based on the harmonic ratio deviation signal. The modulation gain G is used to adjust the amplitude of the sine wave generated by the numerically controlled oscillator, thereby forming a carrier drive signal applied to the first piezoelectric transducer. In one specific embodiment, the second feedback controller is a PI controller. After the input ratio calculation and deviation extraction module of the first harmonic component and the second harmonic component are connected to the PI controller, the PI controller outputs a gain coefficient G. The sine wave generated by the numerically controlled oscillator is multiplied by the gain coefficient G after passing through a low-pass filter, and finally a modulated signal output is obtained. The modulated signal output is applied to the first piezoelectric transducer to adjust the carrier drive amplitude of the first piezoelectric transducer. Furthermore, the digital closed-loop control module also performs current calculation based on the first-order harmonic component and the second-order harmonic component; specifically, after the carrier synchronization compensation and harmonic proportional servo control are completed, the first-order harmonic component and the second-order harmonic component are input into the arctangent calculation module, and the arctangent calculation module calculates the current measurement result corresponding to the current to be measured based on the first-order harmonic component and the second-order harmonic component. Therefore, the digital closed-loop control module can lock the phase to generate the modulation depth of the carrier through the closed-loop path of "harmonic ratio relationship - second feedback controller - modulation gain - carrier drive signal", and use the first-order harmonic component and the second-order harmonic component to complete the demodulation of the current under test while keeping the modulation depth stable, thereby improving the measurement stability and demodulation accuracy of the hybrid fiber optic current sensing system in long-distance power monitoring.

[0040] Example 2; Based on the same inventive concept as the hybrid fiber optic current sensing system for long-distance power monitoring described in the foregoing embodiments, this invention also provides a hybrid fiber optic current sensing method for long-distance power monitoring, such as... Figure 3 As shown, the method includes: S10: The detection light is subjected to interference modulation and a phase generation carrier is loaded to form an interference light signal loaded with a phase generation carrier; S20: Transmits the interference light signal to the remote current response probe and applies the interference light signal to the optical sensing unit; S30: The optical sensing unit deforms in response to the electrical signal corresponding to the current to be measured, causing the optical parameters of the optical sensing unit to change with the deformation, and modulates the interference light signal based on the change of optical parameters to form an optical signal carrying the information of the current to be measured. S40: The optical signal carrying changes in optical parameters is transmitted to the photoelectric acquisition module via the long-distance transmission unit, and the photoelectric acquisition module converts the optical signal into a digital interference signal; S50: Extract orthogonal error and harmonic parameters from digital interference signals, and generate carrier phase adjustment amount to compensate for dynamic phase delay of long-distance transmission units based on orthogonal error; S60: Adaptively adjusts the local carrier phase based on the carrier phase adjustment amount to keep the local carrier in phase synchronization with the optical signal; S70: Generates carrier amplitude adjustment amount based on the proportional relationship of harmonic parameters, and adjusts the carrier drive amplitude of the phase modulation unit according to the carrier amplitude adjustment amount, so that the modulation depth of the phase generation carrier is locked in the linear working state; S80: After completing phase synchronization and modulation depth locking, demodulation calculation is performed based on harmonic parameters to output the measurement result of the current under test.

[0041] The method described above in this invention can effectively realize a hybrid fiber optic current sensing system for long-distance power monitoring, and the technical effects it can achieve are as described in the above embodiments, and will not be repeated here.

[0042] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined herein, and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A hybrid fiber optic current sensing system for long-distance power monitoring, characterized in that, The system includes: Optical interference sensing link, remote current response probe, photoelectric acquisition module and digital closed-loop control module; The optical interference sensing link includes a phase modulation unit and a long-distance transmission unit. The phase modulation unit is used to perform interference modulation on the detection light and load a phase generation carrier to form an interference light signal loaded with the phase generation carrier. The long-distance transmission unit is used to transmit the interference light signal to the remote current response probe and to transmit the light signal carrying the current to be measured to the photoelectric acquisition module via the long-distance transmission unit. The remote current response probe includes an electro-deformation unit and an optical sensing unit coupled to the electro-deformation unit. The electro-deformation unit is used to generate deformation in response to the electrical signal corresponding to the current to be measured. The optical sensing unit is used to generate optical parameter changes with the deformation and modulate the interference optical signal based on the optical parameter changes to form the optical signal carrying the information of the current to be measured. The photoelectric acquisition module is used to convert the optical signal into a digital interference signal; The digital closed-loop control module is used to extract orthogonal error and harmonic parameters based on the digital interference signal, and adaptively adjust the local carrier phase based on the orthogonal error to keep the local carrier in phase synchronization with the optical signal and compensate for the dynamic phase delay introduced by the long-distance transmission unit. It also adjusts the carrier drive amplitude of the phase modulation unit based on the proportional relationship of the harmonic parameters to lock the modulation depth of the phase generation carrier in a linear working state. After completing phase synchronization compensation and modulation depth locking, it performs demodulation calculation based on the harmonic parameters to output the measurement result of the current under test.

2. The hybrid fiber optic current sensing system for long-distance power monitoring according to claim 1, characterized in that, The optical interferometric sensing link includes: The optical interference sensing link includes a broadband light source, a first coupler, a modulation arm, a delay arm, a second coupler, and a circulator; The broadband light source is connected to the first coupler via a single-mode optical fiber, so that the detection light output by the broadband light source is split into two optical signals by the first coupler. One optical signal is transmitted through the modulation arm, and the other optical signal is transmitted through the delay arm. The two optical signals are coupled at the second coupler to form an unbalanced Mach-Zehnder interference optical signal. The output of the second coupler is connected to the circulator via a single-mode optical fiber, so that the unbalanced Mach-Zehnder interference optical signal enters the long-distance transmission section through the circulator.

3. The hybrid fiber optic current sensing system for long-distance power monitoring according to claim 2, characterized in that, The modulation arm and the delay arm include: The modulation arm includes a first piezoelectric transducer, which is used to receive the high-frequency carrier drive signal output by the digital closed-loop control module and to perform phase modulation on the detection light passing through the modulation arm. The first piezoelectric transducer is a piezoelectric ceramic transducer, and a fiber grating is provided on the first piezoelectric transducer so that a phase is loaded in the detection light through the mechanical deformation of the first piezoelectric transducer to generate a carrier wave; The delay arm includes a tunable delay line and a compensation fiber, which are used to form an unbalanced optical path difference with the modulation arm.

4. The hybrid fiber optic current sensing system for long-distance power monitoring according to claim 2, characterized in that, The long-distance transmission unit includes: The long-distance transmission unit includes a long-distance polarization-maintaining fiber, one end of which is connected to the optical interference sensing link via the circulator. The other end of the long-distance polarization-maintaining fiber is connected to the far-end current response probe to transmit the unbalanced Mach-Zehnder interference optical signal loaded with the phase generation carrier to the far-end current response probe. The long-distance polarization-maintaining fiber is used to transmit the reflected light signal carrying the current information to be measured from the remote current response probe back to the circulator. The circulator is used to guide the reflected light signal to the photoelectric acquisition module to realize the long-distance transmission and return of the unbalanced Mach-Zehnder interference light signal.

5. The hybrid fiber optic current sensing system for long-distance power monitoring according to claim 1, characterized in that, The remote current response probe includes: The remote current response probe includes a second piezoelectric transducer and a fiber grating coupled to the second piezoelectric transducer; The second piezoelectric transducer is connected to the load resistor on the secondary side of the current transformer under test via a voltage transmission cable to receive the secondary voltage signal corresponding to the current under test. The second piezoelectric transducer is used to generate piezoelectric deformation according to the secondary side voltage signal, and the fiber grating is used to generate wavelength drift with the piezoelectric deformation.

6. The hybrid fiber optic current sensing system for long-distance power monitoring according to claim 1, characterized in that, The photoelectric acquisition module includes: The photoelectric acquisition module includes a photodetector and an analog-to-digital converter; The photodetector is connected to the reflection output terminal of the circulator to receive the reflected light signal transmitted back through the long-distance transmission unit; The photodetector is used to convert the reflected light signal into an electrical signal, and the analog-to-digital converter is used to sample the electrical signal and generate a digital interference signal; The analog-to-digital converter is connected to the digital closed-loop control module to input the digital interference signal into the digital closed-loop control module for demodulation and feedback control.

7. The hybrid fiber optic current sensing system for long-distance power monitoring according to claim 1, characterized in that, The digital closed-loop control module extracts orthogonal error and harmonic parameters, including: The digital closed-loop control module includes an ADC sampling module, a digital multiplication array, a low-pass filter, and a numerically controlled oscillator; The ADC sampling module is used to receive the digital interference signal and input the digital interference signal into the digital multiplication array; The numerically controlled oscillator is used to generate a carrier in-phase reference signal, a carrier quadrature reference signal, and a second harmonic reference signal; The digital multiplication array is used to multiply the digital interference signal with the carrier in-phase reference signal, the carrier quadrature reference signal and the second harmonic reference signal respectively, and after filtering by the low-pass filter, obtain the quadrature error value, the first harmonic component and the second harmonic component.

8. The hybrid fiber optic current sensing system for long-distance power monitoring according to claim 7, characterized in that, The digital closed-loop control module also includes: The quadrature error value is input to the first feedback controller, so that the first feedback controller generates a phase compensation value based on the quadrature error value; The phase compensation value is fed back to the numerically controlled oscillator to adjust the phase step of the numerically controlled oscillator; The numerically controlled oscillator adjusts the phases of the carrier in-phase reference signal, the carrier quadrature reference signal, and the second harmonic reference signal according to the phase compensation value; The digital closed-loop control module compensates for the dynamic phase delay introduced by the long-distance transmission unit by making the orthogonal error value approach zero.

9. The hybrid fiber optic current sensing system for long-distance power monitoring according to claim 7, characterized in that, The digital closed-loop control module performs harmonic proportional servo control and current calculation, including: The input ratio calculation and deviation extraction module of the first-order harmonic component and the second-order harmonic component is used to obtain the harmonic ratio deviation signal used to characterize the modulation depth deviation. The harmonic proportional deviation signal is input to the second feedback controller so that the second feedback controller outputs a gain coefficient. The gain coefficient is multiplied by the sine wave generated by the numerically controlled oscillator to form a modulation signal applied to the first piezoelectric transducer; The modulation signal is used to adjust the carrier drive amplitude of the first piezoelectric transducer in order to lock the modulation depth of the phase-generated carrier. The first-order harmonic component and the second-order harmonic component are input into the arctangent calculation module to obtain the current measurement result corresponding to the current to be measured.

10. A hybrid fiber optic current sensing method for long-distance power monitoring, characterized in that, The method, applied to a hybrid fiber optic current sensing system for long-distance power monitoring as described in any one of claims 1-9, comprises: interferometric modulation of the detection light and loading a phase-generating carrier to form an interferometric optical signal loaded with the phase-generating carrier; The interference optical signal is transmitted to the remote current response probe, and the interference optical signal is applied to the optical sensing unit. The optical sensing element deforms in response to the electrical signal corresponding to the current to be measured, causing the optical parameters of the optical sensing element to change accordingly. Based on the change in optical parameters, the interference light signal is modulated to form an optical signal carrying the information of the current to be measured. The optical signal carrying the changes in the optical parameters is transmitted to the photoelectric acquisition module via a long-distance transmission unit, and the photoelectric acquisition module converts the optical signal into a digital interference signal. The orthogonal error and harmonic parameters are extracted from the digital interference signal, and a carrier phase adjustment amount is generated based on the orthogonal error to compensate for the dynamic phase delay of the long-distance transmission unit. The local carrier phase is adaptively adjusted based on the carrier phase adjustment amount to keep the local carrier in phase synchronization with the optical signal. Based on the proportional relationship of the harmonic parameters, a carrier amplitude adjustment amount is generated, and the carrier drive amplitude of the phase modulation unit is adjusted according to the carrier amplitude adjustment amount, so that the modulation depth of the phase generated carrier is locked in a linear working state. After completing the phase synchronization and modulation depth locking, demodulation calculation is performed based on the harmonic parameters to output the measurement result of the current to be measured.

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