Insulation detection equipment using optical fiber and insulation detection method

Abstract

The invention relates to insulation detection equipment using an optical fiber and an insulation detection method. The equipment comprises a photoelectric collector; the sensing ring measuring unit is connected with the photoelectric collector, the sensing ring measuring unit comprises a large-current magnet and a first optical fiber ring, the first optical fiber ring comprises a compensation optical fiber ring and a measuring optical fiber ring which are connected in series, and the large-current magnet comprises a winding, an input cable and an output cable, the compensation optical fiber ring penetrates through the input cable, the measurement optical fiber ring penetrates through the large-current magnet in a winding manner, current which flows through the large-current magnet and flows out of the output cable is introduced into the input cable, and the equivalent number of turns of the measurement optical fiber ring is the same as that of the compensation optical fiber ring, but the winding directions are opposite; the photoelectric collector is configured to obtain a first current signal of the first optical fiber ring, and when the first current signal of the first optical fiber ring is not zero, it is judged that insulation of the large-current magnet fails.

Description

Technical Field

[0001] This application relates to the technical field of power monitoring, and in particular to an insulation detection device and an insulation detection method using optical fibers. Background Art

[0002] High-current magnets have extensive application requirements in large-capacity transformers and controlled nuclear fusion fields. High-current magnets are usually wound with multiple turns of coils, and large direct or alternating currents pass through the coils. The wires for winding high-current magnets are copper wires or superconducting wires. During long-term operation, due to reasons such as wire heating, the insulation of high-current magnets deteriorates or even fails, posing safety hazards or affecting the magnetic field effect. Summary of the Invention

[0003] This application provides an insulation detection device using optical fibers, which can solve the technical problem of potential safety hazards easily caused by the failure of the existing inter-turn insulation of windings.

[0004] An insulation detection device using optical fibers includes: An optoelectronic collector; and A sensing loop measuring unit connected to the optoelectronic collector. The sensing loop measuring unit includes a high-current magnet and a first optical fiber loop. The first optical fiber loop includes a compensation optical fiber loop and a measuring optical fiber loop connected in series. The high-current magnet includes a winding and input and output cables connected to both ends of the winding. The compensation optical fiber loop passes through the input cable, and the measuring optical fiber loop winds through the high-current magnet. A current flowing through the high-current magnet and flowing out from the output cable is passed through the input cable. The equivalent number of turns of the measuring optical fiber loop is the same as that of the compensation optical fiber loop but the winding directions are opposite. The optoelectronic collector is configured to obtain a first current signal including a magnetic circuit loop formed by the compensation optical fiber loop and the measuring optical fiber loop, and the first current signal is used to determine whether the high-current magnet has insulation failure.

[0005] In one of the solutions, when the first current signal is not 0, the optoelectronic collector determines that the high-current magnet has insulation failure and determines the degree of insulation failure of the high-current magnet according to the magnitude of the first current signal.

[0006] In one of the solutions, the insulation detection device using optical fibers further includes a second optical fiber loop and a double-pass optical switch. The first end of the double-pass optical switch is connected to the optoelectronic collector, and the second end of the double-pass optical switch is respectively connected to the first optical fiber loop and the second optical fiber loop; In the normal working state, the photoelectric collector can control the double-pass optical switch to select the first optical fiber loop and collect the first current signal. When the first current signal is not zero, record the value of the failure current signal ΔI at this time, and control the double-pass optical switch to select the second optical fiber loop, measure the current value I in the second optical fiber loop, and calculate the insulation failure degree ε of the large current magnet according to the relationship between ΔI and I.

[0007] In one of the above solutions, the insulation detection device using an optical fiber further includes an alarm. The critical failure degree ε0 is stored in the photoelectric collector. When ε > ε0, the alarm emits an alarm signal.

[0008] In one of the above solutions, the photoelectric collector is a fiber optic current sensor.

[0009] In one of the above solutions, the photoelectric collector includes a light source, a photodetector, a coupler, a fiber optic polarizer, a phase modulator, a polarization-maintaining fiber delay loop, and a signal processing circuit. The light source, the coupler, the fiber optic polarizer, and the phase modulator are connected in sequence through optical fibers. The two opposite ends of the signal processing circuit are respectively connected to the photodetector and the phase modulator. The two opposite ends of the photodetector are respectively connected to the coupler and the signal processing circuit. The two opposite ends of the polarization-maintaining fiber delay loop are respectively connected to the phase modulator and the double-pass optical switch.

[0010] An insulation detection method using an optical fiber includes: Providing the insulation detection device using an optical fiber as described above; Obtaining the first current signal of the first optical fiber loop in real time; Judging whether the first current signal is 0. When the first current signal is not zero, judge the insulation failure degree of the large current magnet.

[0011] In one of the above solutions, when the first current signal is not zero, record the value of the failure current signal ΔI at this time, and control the double-pass optical switch to select the second optical fiber loop, measure the current value I in the second optical fiber loop, and calculate the insulation failure degree ε of the large current magnet according to the relationship between ΔI and I.

[0012] In one of the above solutions, the critical failure degree ε0 is stored in the photoelectric collector. After obtaining the insulation failure degree ε, it further includes comparing the relationship between ε and ε0. When ε > ε0, the alarm emits an alarm signal.

[0013] An insulation detection device and an insulation detection method using an optical fiber provided by the present application can achieve the following technical effects: 1. The insulation detection device using optical fiber provided by this application generates a magnetic field when current flows through a large current magnet. This magnetic field affects the optical signals of the compensation optical fiber loop and the measurement optical fiber loop in the first optical fiber loop. Since the equivalent number of turns of the measurement optical fiber loop and the compensation optical fiber loop satisfies a preset relationship but their winding directions are opposite, when the insulation between the winding turns of the large current magnet is normal, the influences of the compensation optical fiber loop and the measurement optical fiber loop on the magnetic field cancel each other out. The first optical signal of the first optical fiber loop is transmitted to the optoelectronic collector, and the optoelectronic collector can convert the first optical signal into a first current signal. When the magnetic fields cancel each other out, the first current signal is 0. That is, the optoelectronic collector can sensitively detect the changes in the magnetic field in the first optical fiber loop and convert these changes into electrical signals, namely the first current signal. If the insulation between turns fails, for example, if the large current magnet has m turns in the normal state and an insulation defect occurs, which is equivalent to a short circuit between the windings, and thus it becomes (m - Δm) turns. The induced magnetic field generated by (m - Δm) turns is smaller than that generated by m turns, resulting in the magnetic field in the compensation optical fiber loop not being able to completely cancel the magnetic field jointly generated by the measurement optical fiber loop and the large current magnet. This changed magnetic field signal can also be captured by the optoelectronic collector in real time and processed into a current signal. Therefore, it can be determined whether the large current magnet has insulation failure based on whether the first current signal is 0.

[0014] 2. When the first current signal is not 0, the optoelectronic collector can determine that the large current magnet has insulation failure and determine the degree of insulation failure of the large current magnet according to the magnitude of the first current signal.

[0015] 3. The insulation detection device using optical fiber provided by this application further includes a second optical fiber loop and a double - pass optical switch. The first end of the double - pass optical switch is connected to the optoelectronic collector, and the second end of the double - pass optical switch is respectively connected to the first optical fiber loop and the second optical fiber loop. In the normal working state, the optoelectronic collector can control the double - pass optical switch to select the first optical fiber loop and collect the first current signal. When the first current signal is not 0, record the current value at this time as the failure current signal value ΔI, and control the double - pass optical switch to select the second optical fiber loop, measure the current value I in the second optical fiber loop, and calculate the degree of insulation failure ε of the large current magnet according to the relationship between ΔI and I. Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of an insulation detection device using optical fiber provided by the first embodiment of this application.

[0017] Description of reference numerals: 100, insulation detection device using optical fiber; 10, light source; 14, detector; 11, coupler; 12, polarizer; 13, phase modulator; 15, signal processing circuit; 16, polarization-maintaining optical fiber delay loop; 20, large current magnet; 3, optical switch; 1, optoelectronic collector; 210, compensation optical fiber loop; 212, measurement optical fiber loop; 23, quarter-wave plate; 24, mirror; 2, sensing loop measurement unit; 201, winding; 202, input cable; 203, output cable; 21, first optical fiber loop; 22, second optical fiber loop; 25, sensing optical fiber. Detailed implementation manners

[0018] The following will further describe in detail Figure 1 the insulation detection device using optical fiber and the insulation detection method provided by this application.

[0019] An insulation detection device 100 using optical fiber provided by this application monitors the current in the winding in a non-contact manner in real time to determine whether there are defects in the insulation state of the winding. Specifically, an insulation detection device 100 using optical fiber includes an optoelectronic collector 1 and a sensing loop measurement unit 2.

[0020] In this embodiment, the optoelectronic collector 1 is an optical fiber current sensor. More specifically, the optoelectronic collector 1 includes a light source 10, a photodetector 14, a coupler 11, an optical fiber polarizer 12, a phase modulator 13, a polarization-maintaining optical fiber delay loop 16, and a signal processing circuit 15.

[0021] The light source 10, the coupler 11, the optical fiber polarizer 12, and the phase modulator 13 are connected in sequence through optical fibers. The opposite ends of the signal processing circuit 15 are respectively connected to the photodetector 14 and the phase modulator 13. The opposite ends of the photodetector 14 are respectively connected to the coupler 11 and the signal processing circuit 15. The opposite ends of the polarization-maintaining optical fiber delay loop 16 are respectively connected to the phase modulator 13 and the double-pass optical switch 3. The phase modulator 13 performs phase modulation on the polarized optical signal so that the magnetic field change can be detected by measuring the phase change subsequently.

[0022] The photodetector 14 is responsible for converting the transmitted optical signal into an electrical signal. The phase-modulated optical signal will generate current or voltage changes in the detector, and these changes are related to the intensity and direction of the external magnetic field, thereby reflecting the current situation in the large current magnet.

[0023] The polarization-maintaining optical fiber delay loop 16 ensures that the optical signal maintains consistent polarization characteristics during the transmission process in the optical fiber and delays the signal to a certain extent, enabling the system to process and analyze the phase change.

[0024] The signal processing circuit 15 receives the electrical signal converted by the photodetector 14 and performs further processing to decode the relevant information on the current change. By analyzing the signal, it can be determined whether there is an insulation failure in the large current magnet. The signal processing circuit can extract useful data from the photodetector 14 for fault diagnosis.

[0025] It should be noted that for the two x's in the photoelectric collector 1, each x represents left-handed circularly polarized light and right-handed circularly polarized light.

[0026] Specifically, the light source 10 is a superluminescent light emitting diode (SLD) light source. The light source 10 emits a laser beam, which is coupled into the fiber optic polarizer 12 through the coupler 11. After polarization by the fiber optic polarizer 12, it becomes linearly polarized light. The pigtail of the fiber optic polarizer 12 is fusion spliced with the pigtail of the phase modulator 13 at 45°. The linearly polarized light is injected into the polarization maintaining fiber delay loop 16 at 45° and propagates along the X-axis and Y-axis of the polarization maintaining fiber delay loop 16 respectively.

[0027] Generally, a quarter-wave plate and a mirror need to be set between the polarization maintaining fiber delay loop 16 and the sensing loop measurement unit 2. The mirror is mainly used to change the propagation direction of light to ensure that the optical signal can propagate correctly along the fiber loop. Its function is to realize the optical path closed-loop, guide the light beam and control the transmission direction of the optical signal; the quarter-wave plate changes the polarization state of light by introducing a 90-degree phase delay, and adjusts the phase and polarization direction of light. It has an important influence on the stability, polarization state and output characteristics of the fiber loop laser.

[0028] The linearly polarized light in the orthogonal mode propagating along the X-axis and Y-axis of the polarization maintaining fiber delay loop 16 becomes left-handed and right-handed circularly polarized light respectively after passing through the quarter-wave plate and enters the sensing loop measurement unit 2 for propagation.

[0029] The sensing loop measurement unit 2 is communicatively connected to the photoelectric collector 1. The sensing loop measurement unit 2 mainly includes a current-carrying wire (large current magnet) and a fiber loop through which the current-carrying wire is threaded. The current flowing in the current-carrying wire generates a magnetic field, which produces the Faraday magneto-optical effect in the fiber loop, causing a phase difference between the left-handed circularly polarized light and the right-handed circularly polarized light in the fiber loop. After reflection at the end face of the mirror, the polarization modes of the two circularly polarized light beams are interchanged (i.e., the left-handed light becomes right-handed light and the right-handed light becomes left-handed light), and then pass through the fiber loop again, and the Faraday magneto-optical effect causes the phase difference generated by the two light beams to double. After these two light beams pass through the quarter-wave plate again, they are restored to linearly polarized light and return, and interfere at the fiber optic polarizer 12.

[0030] Finally, the light carrying the non-reciprocal phase difference information generated by the Faraday magneto-optical effect enters the photodetector 14 through the coupler 11 and is converted into an electrical signal.

[0031] Therefore, according to the Faraday magneto-optical effect and Ampere's circuital law, it can be known that the magnitude of the current transmitted in the current-carrying wire is proportional to the phase difference. Therefore, the value of the current to be measured can be calculated by detecting the optical phase difference signal.

[0032] Specifically, in this embodiment, the sensing loop measurement unit 2 includes a large current magnet 20 and a first optical fiber loop 21. When a current passes through the large current magnet, a magnetic field will be generated near the first optical fiber loop 21, thereby affecting the optical signal transmitted in the optical fiber. The first optical fiber loop 21 itself can detect these magnetic field changes, and these changes are related to the magnitude and direction of the current flowing through the large current magnet 20.

[0033] In this embodiment, the first optical fiber loop 21 includes a series-connected compensation optical fiber loop 210 and a measurement optical fiber loop 212. The large current magnet 20 includes a winding 201 and input and output cables 202 and 203 connected to both ends of the winding 201. The compensation optical fiber loop 210 passes through the input cable 202, and the measurement optical fiber loop 212 winds through the large current magnet 20. A current flowing through the large current magnet 20 and flowing out from the output cable 203 is passed through the input cable 202. The equivalent number of turns of the measurement optical fiber loop 212 and the equivalent number of turns of the compensation optical fiber loop 210 satisfy a preset relationship but have opposite winding directions.

[0034] The optoelectronic collector 1 is configured to obtain a first current signal of the magnetic circuit loop where the first optical fiber loop 21 is located, and the first current signal is used to determine whether the large current magnet 20 has insulation failure.

[0035] In this embodiment, the magnetic circuit loop (the position of the loop in the figure) of the first optical fiber loop 21 includes a compensation optical fiber loop 210, a measurement optical fiber loop 212, a quarter-wave plate 23, a reflector 24, and a sensing optical fiber 25 connecting the compensation optical fiber loop 210, the measurement optical fiber loop 212, the quarter-wave plate 23, and the reflector 24.

[0036] According to the magneto-optical effect, the equivalent induced current in the compensation optical fiber loop 210 is the product of the equivalent number of turns of the compensation optical fiber loop 210, the equivalent number of turns of the input cable 202, and the current I.

[0037] Since the input cable 202 passes through the compensation optical fiber loop 210 in a straight line, the equivalent number of turns is 1. Therefore, the final equivalent current in the compensation optical fiber loop 210 is the product of the equivalent number of turns of the compensation optical fiber loop 210 and the current I.

[0038] The equivalent induced current I in the measurement optical fiber loop 212 感212 is the product of the equivalent number of turns of the measurement optical fiber loop 212, the equivalent number of turns of the large current magnet 20, and the current I.

[0039] For example, the equivalent number of turns of the compensation fiber optic loop 210 is N, the equivalent number of turns of the measurement fiber optic loop 212 is M, and the number of turns of the large current magnet 20 is m, i.e., I 感210 = N*I; I 感212 = M*m*I. Since the winding directions of the compensation fiber optic loop 210 and the measurement fiber optic loop 212 are opposite, N = M*m can be made, so that the induced current can reach balance and thus be 0.

[0040] The equivalent induced current in the measurement fiber optic loop 212 and the equivalent current in the compensation fiber optic loop 210 can reach balance, which means that the insulation of the large current magnet 20 is normal. If the insulation of the large current magnet 20 fails, then m will decrease accordingly, resulting in the current in the magnetic circuit loop not being 0. Thus, it is possible to determine whether there is an insulation defect in the coil based on the current.

[0041] In this embodiment, when the first current signal is not 0, the optoelectronic collector 1 determines that there is a defect in the insulation of the large current magnet 20 and determines the degree of insulation failure of the large current magnet 20 according to the magnitude of the first current signal.

[0042] In this embodiment, the fiber optic insulation detection device 100 further includes a second fiber optic loop 22 and a double-pass optical switch 3. The second fiber optic loop 22 serves as a reference fiber optic loop and is used to cooperate with the optoelectronic collector 1 to obtain the current value I in the large current magnet 20.

[0043] The first end of the double-pass optical switch 3 is connected to the optoelectronic collector 1. More specifically, the first end of the double-pass optical switch 3 is connected to the polarization-maintaining fiber optic delay loop 16. The second end of the double-pass optical switch 3 is respectively connected to the first fiber optic loop 21 and the second fiber optic loop 22. The double-pass optical switch 3 can connect the first fiber optic loop 21 or the second fiber optic loop 22.

[0044] In the normal working state, the optoelectronic collector 1 can control the double-pass optical switch 3 to select the first fiber optic loop 21 and collect the first current signal. When the first current signal is not 0, record the current value at this time as the failure current signal value ΔI, and control the double-pass optical switch 3 to select the second fiber optic loop 22, measure the current value I in the second fiber optic loop 22, and calculate the equivalent current I of the large current magnet 20 according to the current value I measured by the second fiber optic loop 22 and the number of turns m of the large current magnet 20 磁 = mI, and then calculate the insulation failure degree ε = ΔI / I of the large current magnet 20 according to the relationship between ΔI and I 磁 磁 .

[0045] ​In this embodiment, the insulation detection device 100 using an optical fiber further includes an alarm (not shown in the figure). The critical failure degree ε0 is stored in the photoelectric collector 1. The photoelectric collector 1 can also judge the magnitude between the critical failure degree ε0 and the insulation failure degree ε. When ε > ε0, the alarm emits an alarm signal.

[0046] The insulation detection device 100 using an optical fiber: The pigtail of the optical fiber polarizer 12 is fused with the pigtail of the phase modulator 13 at 45°. The linearly polarized light is injected into the polarization-maintaining fiber delay loop 16 at 45°, and is transmitted along the X-axis and Y-axis of the polarization-maintaining fiber delay loop 16 respectively. When the double-pass optical switch 3 is connected to the first optical fiber loop 21 through an optical fiber, these two orthogonally polarized light beams are respectively converted into left-handed elliptical / circularly polarized light and right-handed elliptical / circularly polarized light under the action of the quarter-wave plate 23. Due to the magnetic field around the large current magnet 20 causing the Faraday effect, these two elliptical / circularly polarized light beams are transmitted at different speeds. After passing through the mirror 24 at the end of the first optical fiber loop 21, the polarization modes of the two elliptical / circularly polarized light beams are interchanged (i.e., the left-handed elliptical / circularly polarized light becomes right-handed elliptical / circularly polarized light, and the right-handed elliptical / circularly polarized light becomes left-handed elliptical / circularly polarized light), and then pass through the first optical fiber loop 21 again, and interact with the magnetic field generated by the winding 201 again, doubling the generated Faraday phase. Then the quarter-wave plate 23 converts the elliptical / circularly polarized light into linearly polarized light. When the two light waves reach the optical fiber polarizer 12 through the transmission optical cable, interference occurs. The interference signal returns to the photodetector 14 through the optical fiber coupler 11. Since the two interfering light beams respectively pass through the left-handed and right-handed modes of the X-axis and Y-axis of the polarization-maintaining fiber delay loop 16 during the transmission process of the optical path, and there is only a slight difference in time, the light returning to the detector only carries the non-reciprocal phase difference generated by the Faraday effect. The phase difference Φ generated by the Faraday effect is Φ = 4VNI, where V is the Verdet constant of the optical fiber; N is the number of sensing optical fiber loops; I is the current passing through the current-carrying wire. Therefore, measuring the phase difference between these two light waves can accurately measure the magnitude of the current passing through the large current magnet 20. When a current I is passed through the high-current magnet 20, an induced magnetic field is generated within the high-current magnet 20 due to electromagnetic induction. This magnetic field will affect the optical signals of the compensation optical fiber loop 210 and the measurement optical fiber loop 212 in the first optical fiber loop 21. Since the equivalent number of turns of the measurement optical fiber loop 212 and the compensation optical fiber loop 210 is the same but the winding directions are opposite, when the insulation between the turns of the winding 201 included in the high-current magnet 20 is normal, their effects on the magnetic field will cancel each other out. The signal of the first optical fiber loop 21 is transmitted to the optoelectronic collector 1, and the optoelectronic collector 1 can convert the optical signal into an electrical signal. When the magnetic fields cancel each other out, the first current signal is 0. That is, the optoelectronic collector 1 can sensitively detect the change in the magnetic field in the first optical fiber loop 21 and convert these changes into electrical signals, that is, the first current signal. If the inter-turn insulation fails, for example, if the high-current magnet 20 has m turns under normal conditions and an insulation defect occurs, which is equivalent to a short circuit between the windings 201, thus becoming m - Δm turns, the induced magnetic field generated by m - Δm turns will be smaller than the induced magnetic field generated by m turns, resulting in the magnetic fields in the compensation optical fiber loop 210 and the measurement optical fiber loop 212 not being completely canceled. This changed magnetic field signal can also be captured by the optoelectronic collector 1 in real time, so it is possible to determine whether the high-current magnet 20 has insulation failure based on whether the first current signal is 0.

[0047] The present invention also relates to an insulation detection method using optical fibers, including: S1: Provide an insulation detection device 100 using optical fibers; S2: Obtain the first current signal of the first optical fiber loop 21 in real time and determine whether the first current signal is 0; <> S3: When the first current signal is not 0, determine the degree of insulation failure of the high-current magnet 20.

[0048] In this embodiment, when the first current signal is not 0, record the failure current signal value ΔI at this time, control the double-pass optical switch 3 to select the second optical fiber loop 22, measure the current value I in the second optical fiber loop 22, and calculate the degree of insulation failure ε of the high-current magnet 20 according to the relationship between ΔI and I. For example, in this embodiment, the equivalent current value I of the high-current magnet 20 is obtained by measuring the current value I through the second optical fiber loop 22 磁 , calculate the insulation failure degree of the magnet coil ε = ΔI / I 磁 .

[0049] In this embodiment, a critical failure degree ε0 is stored in the optoelectronic collector 1. After obtaining the degree of insulation failure ε, it further includes comparing the relationship between ε and ε0. When ε > ε0, the alarm issues an alarm signal.

[0050] In summary, the insulation detection device 100 and the insulation detection method using an optical fiber provided by the present invention can determine in real time whether there is an insulation defect in the large current magnet 20 according to the magnetic ring circuit. If there is an insulation defect, it can further determine in real time the degree of insulation failure of the large current magnet 20. When the degree of insulation failure exceeds a preset threshold, a warning will be issued to ensure the electrical safety of the large current magnet 20 in the fields of large-capacity transformers and controlled nuclear fusion.

[0051] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. An insulation detection device using an optical fiber, characterized in that Comprising: An optoelectronic collector (1); And A sensing loop measurement unit (2), communicatively connected to the optoelectronic collector (1), the sensing loop measurement unit (2) comprising a large current magnet (20) and a first optical fiber loop (21), the first optical fiber loop (21) comprising a series-connected compensation optical fiber loop (210) and a measurement optical fiber loop (212), the large current magnet (20) comprising a winding (201) and an input cable (202) and an output cable (203) respectively connected to both ends of the winding (201), the compensation optical fiber loop (210) passing through the input cable (202), the measurement optical fiber loop (212) being wound through the large current magnet (20), a current flowing through the large current magnet (20) and flowing out from the output cable (203) being passed through the input cable (202), the equivalent number of turns of the measurement optical fiber loop (212) and the equivalent number of turns of the compensation optical fiber loop (210) satisfying a preset relationship but having opposite winding directions; The optoelectronic collector (1) is configured to acquire a first current signal of a magnetic circuit loop where the first optical fiber loop (21) is located, and the first current signal is used to determine whether the large current magnet (20) has insulation failure.

2. The insulation detection device using an optical fiber according to claim 1, characterized in that: The magnetic circuit loop where the first optical fiber loop (21) is located includes a compensation optical fiber loop (210), a measurement optical fiber loop (212), a quarter-wave plate (23) and a mirror (24).

3. An insulation detection device using an optical fiber according to claim 1, characterized in that: When the first current signal is not 0, the optoelectronic collector (1) determines that the large current magnet (20) has insulation failure and determines the degree of insulation failure of the large current magnet (20) according to the magnitude of the first current signal.

4. An insulation detection device using an optical fiber according to claim 3, characterized in that: The insulation detection device using an optical fiber further includes a second optical fiber loop (22) and a double-pass optical switch (3), the second optical fiber loop (22) passing through the input cable (202) of the large current magnet (20), a first end of the double-pass optical switch (3) being connected to the optoelectronic collector (1), and a second end of the double-pass optical switch (3) being respectively connected to the first optical fiber loop (21) and the second optical fiber loop (22); In the normal working state, the photoelectric collector (1) can control the double-pass optical switch (3) to select the first optical fiber loop (21) and collect the first current signal. When the first current signal is not zero, record the failure current signal value ΔI at this time, and control the double-pass optical switch (3) to select the second optical fiber loop (22). Obtain the equivalent current value I of the large current magnet (20) through the measured current value I in the second optical fiber loop (22). 磁 , and according to ΔI and I 磁 calculate the insulation failure degree ε of the large current magnet (20).

5. An insulation detection device using an optical fiber according to claim 4, characterized in that: The insulation detection device using an optical fiber further includes an alarm, a critical failure degree ε0 is stored in the optoelectronic collector (1), and when ε>ε0, the alarm emits an alarm signal.

6. An insulation detection device using an optical fiber according to any one of claims 1-5, characterized in that: The optoelectronic collector (1) is an optical fiber current sensor.

7. An insulation detection device using an optical fiber according to claim 6, characterized in that: The optoelectronic collector (1) includes a light source (10), a photodetector (14), a coupler (11), an optical fiber polarizer (12), a phase modulator (13), a polarization-maintaining optical fiber delay loop (16) and a signal processing circuit (15), the light source (10), the coupler (11), the optical fiber polarizer (12), and the phase modulator (13) are sequentially connected by optical fibers, opposite ends of the signal processing circuit (15) are respectively connected to the photodetector (14) and the phase modulator (13), opposite ends of the photodetector (14) are respectively connected to the coupler (11) and the signal processing circuit (15), and opposite ends of the polarization-maintaining optical fiber delay loop (16) are respectively connected to the phase modulator (13) and the double-pass optical switch (3).

8. An insulation detection method using an optical fiber, characterized in that, Comprising: Provide an insulation detection device using an optical fiber as described in any one of claims 1-7; Obtain the first current signal of the first optical fiber loop (21) in real time; Judge whether the first current signal is 0. When the first current signal is not 0, judge the insulation failure degree of the large current magnet (20).

9. The insulation detection method using an optical fiber according to claim 8, characterized in that: When the first current signal is not zero, record the value of the failure current signal ΔI at this time. It also includes providing a second optical fiber loop (22) and a double-pass optical switch (3). The second optical fiber loop (22) passes through the input cable (202) of the high-current magnet (20). The first end of the double-pass optical switch (3) is connected to the optoelectronic collector (1). The second end of the double-pass optical switch (3) is respectively connected to the first optical fiber loop (21) and the second optical fiber loop (22), and control the double-pass optical switch (3) to select the second optical fiber loop (22). Obtain the current value I of the high-current magnet (20) through the current value I measured by the second optical fiber loop (22). 磁 , and according to the relationship between ΔI and I 磁 , calculate the insulation failure degree ε = ΔI / I of the high-current magnet (20). 磁 .

10. An insulation detection method using an optical fiber according to claim 9, characterized in that: The critical failure degree ε0 of the large current magnet (20) is stored in the optoelectronic collector (1). After obtaining the insulation failure degree ε, it further includes comparing the relationship between ε and ε0. When ε > ε0, the alarm issues an alarm signal.

Images