On-line diagnosis method for abnormity of optical path of transformer substation

Abstract

The invention discloses a transformer station optical path abnormity on-line diagnosis method, and relates to the transformer station on-line monitoring and fault diagnosis technology field, first, an optical fiber bending leakage proportionality coefficient K is introduced, a leakage optical power PL and an optical fiber internal optical power P0 are converted, then the optical fiber internal optical power is measured segment by segment and is compared with a standard value, and a fault diagnosis result is obtained. Finding out a section with an abnormal light path; according to the on-line diagnosis method for the abnormity of the optical path of the transformer substation, the optical power in the optical fiber can be measured under the condition that the optical fiber port is not pulled and plugged, the potential risk that a detector mistakenly touches and operates the optical fiber port when measuring the optical power is reduced, and the safety of field work is remarkably improved; according to the invention, the method shortens the abnormal defect elimination time of the optical path of the transformer substation, reduces the risk of monitoring information interruption or secondary equipment function locking, improves the stability and reliability of transformer substation relay protection and automatic system operation, and is of great significance for guaranteeing the safe operation of a power system.

Description

Technical Field

[0001] The invention relates to the technical field of substation online monitoring and fault diagnosis, in particular to an online diagnosis method for optical path abnormality of a substation. Background Art

[0002] In modern communication systems, optical paths are important media for information transmission, and their stability and reliability are directly related to the quality and efficiency of communication. Optical path anomalies are one of the most common defects in secondary equipment in substations. Due to the influence of various factors, optical path failures occur from time to time, which may affect the normal operation of equipment, or even cause monitoring information interruption or even protection device locking. If not handled in time, primary equipment will lose protection and be forced to shut down. Therefore, timely and accurate analysis and elimination of optical path failures are of great significance to ensure the normal operation of communication systems.

[0003] The optical path of a substation usually adopts a radial structure, that is, the optical paths of the equipment at the same location converge to the optical fiber distribution frame at the location, and then connect to the optical fiber distribution frame at the corresponding location, and then connect to the corresponding equipment. Any abnormality in any section of the optical path will cause transmission abnormality of the entire optical path. Therefore, the premise of optical path abnormality diagnosis is to accurately find the abnormal section of the optical path, and then take corresponding measures according to the actual situation, such as replacing spare optical fibers.

[0004] At present, the commonly used method for diagnosing optical path abnormalities is the "offline" optical power measurement method, which starts from the optical transmission device, unplugs the optical fiber connectors at the end of each section in turn, and inserts them into the measurement port of the optical power meter. By detecting whether the optical power received at the end of each section is qualified, it is possible to diagnose whether the optical path is normal, and finally locate the abnormal section of the optical path.

[0005] However, when the fiber connector is unplugged, the optical path will inevitably be interrupted, so it is called an "offline" method. For locations where multiple fiber ports are close to each other, such as fiber distribution frames, there is a risk of accidentally touching or unplugging other ports, causing normal equipment communication interruption. In addition, the process of plugging and unplugging the fiber connector may cause the port to be contaminated or not restored in place, causing secondary damage to the optical path, adding additional processing time, and greatly affecting the efficiency of troubleshooting.

[0006] Therefore, it is urgent to study a method for diagnosing whether the optical path of a substation is abnormal without unplugging the optical fiber connector. Summary of the invention

[0007] To solve the above problems, the purpose of the present invention is to provide an online diagnosis method for substation optical path abnormalities, which can measure the optical power inside the optical fiber without plugging in or out the optical fiber port, reduce the potential risk of maintenance personnel accidentally touching the operating optical fiber port, and improve the safety of on-site work.

[0008] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0009] An online diagnosis method for abnormal optical path in a substation is proposed. First, the optical fiber bending leakage proportional coefficient K is introduced to calculate the leakage optical power P L And the optical power P0 inside the optical fiber is converted to:

[0010] P L =KP0; (1);

[0011] Then, measure the optical power inside the optical fiber section by section and compare it with the standard value to find the section with abnormal optical path;

[0012] Said Where K is the fiber bending leakage proportional coefficient; α is the fiber bending loss coefficient;

[0013]

[0014] In formula (2), β is the axial propagation constant of the optical fiber; λ is the communication wavelength; n is the cladding refractive index; m is the core refractive index; r is the core radius; and R is the optical fiber bending radius.

[0015] Preferably, when the leakage optical power P L When converting to the optical power P0 inside the optical fiber, for an optical fiber of a certain material, n is the cladding refractive index; m is the core refractive index; r is the core radius; R is the constant fiber bending radius; therefore, when the communication wavelength λ and the fiber bending radius R remain unchanged, the fiber bending leakage proportional coefficient K is a constant, that is, the leakage optical power P L It is proportional to the power P0 of the optical signal inside the optical fiber.

[0016] Preferably, for an optical fiber of a certain material, a light signal of a specified wavelength is outputted into the optical fiber through a light source, and then the optical fiber is bent to a specified radius so that a certain light signal is leaked without breaking the optical fiber; the light power of the light signal outputted by the light source is changed, and then the light power of the optical fiber bending leakage light under different light powers is obtained, and the optical fiber bending leakage proportional coefficient K under the light wavelength and the bending radius is obtained.

[0017] For optical fibers of this material, the magnitude of the optical power leakage at the wavelength and bending radius is known. Combined with the optical fiber bending leakage proportional coefficient K, the magnitude of the optical power inside the optical fiber is calculated.

[0018] Preferably, the standard value is the optical receiving sensitivity of the optical fiber port of the secondary equipment of the substation: when the wavelength is 1310nm, the optical power reaches -31dBm, and when the wavelength is 850nm, the optical power reaches -24dBm.

[0019] Preferably, the judgment criteria for the section with optical path abnormality are: for the optical fiber port with a wavelength of 1310nm, when the received optical power is less than -31dBm, the port indicates optical path abnormality; for the optical fiber port with a wavelength of 850nm, when the received optical power is less than -24dBm, the port indicates optical path abnormality.

[0020] Preferably, the leakage optical power P L The measurement is realized by the photoelectric detection circuit, which uses an InGaAs diode and a corresponding amplifier circuit to convert PL into a voltage value U. Its conversion function is expressed as:

[0021] P L = kU + b (3);

[0022] Where k is the slope and b is the intercept;

[0023] Substituting formula (3) into formula (1), we get:

[0024]

[0025] Preferably, for an optical path to be tested, the spare optical fiber is placed in a bending mechanism with a specific bending radius for bending, an external light source is used to output an optical signal with the same wavelength as the optical signal inside the optical path to be tested, and the voltage value U corresponding to the leakage optical power is measured, and P0 is changed to obtain two sets of (U, P0) values, and the obtained value is

[0026] When an optical path anomaly occurs in the optical path, the voltage value U corresponding to the leakage optical power of each section of optical fiber under the same bending mechanism is measured and substituted into formula (4) to obtain the magnitude of the optical power inside the optical fiber.

[0027] Preferably, the spare optical fiber is of the same model or material as the optical fiber in the optical path to be tested.

[0028] Preferably, if the segment to be tested is after the abnormal segment, the segment to be tested is judged to be abnormal. That is, the segments after the first abnormal segment are all judged to be abnormal segments.

[0029] Preferably, the online diagnosis method for abnormality of optical path in a substation comprises the following steps:

[0030] ① The fiber bending leakage proportional coefficient K is related to β, r, m, n, λ, and R, among which β, r, m, and n are related to the fiber material; therefore, for a certain fiber material, when λ and R remain unchanged, the magnitude of its leakage optical power P L It is proportional to the internal optical power P0, that is:

[0031] P L =KP0 (1);

[0032] ② Under the premise that λ and R remain unchanged, change the optical power P0 of the light signal output by the light source, and then obtain the optical power P of the optical fiber bending leakage light under two different optical powers. L , the fitting results in a (P L , P0) straight line, then K is the slope of the straight line under the current λ and R;

[0033] ③P L The measurement is realized by the photoelectric detection circuit, using InGaAs diode and corresponding amplifier circuit to L Converted to voltage value U, its conversion function is expressed as:

[0034] P L = kU + b (3);

[0035] Substituting formula (3) into formula (1), we get:

[0036]

[0037] For an optical path to be tested, place the spare optical fiber in a bending mechanism with a specific bending radius for bending. Use an external light source to output an optical signal with the same wavelength as the optical signal inside the optical path to be tested, and measure the voltage value U corresponding to its leakage optical power. Change P0 to obtain two sets of (U, P0) values, and obtain

[0038] ④ When an optical path anomaly occurs in the optical path, the voltage value U corresponding to the leakage optical power of each section of the optical fiber under the same bending mechanism is measured and substituted into formula (4) to obtain the size of the optical power inside the optical fiber; the optical power inside the optical fiber is measured section by section and compared with the standard value, so that the section with the optical path anomaly can be found.

[0039] When the spare optical fiber is placed in a bending mechanism with a specific bending radius for bending, the bending radius should not be too small to prevent the optical fiber from being damaged.

[0040] Compared with the prior art, the present invention has the following advantages:

[0041] The on-line diagnosis method for substation optical path anomalies of the present invention can measure the optical power inside the optical fiber without plugging or unplugging the optical fiber port, reducing the potential risk of detection personnel accidentally touching the operating optical fiber port when measuring the optical power, and significantly improving the safety of on-site work.

[0042] The online diagnosis method for substation optical path anomalies of the present invention shortens the time required to eliminate substation optical path anomalies, reduces the risk of monitoring information interruption or secondary equipment function blocking, and improves the stability and reliability of substation relay protection and automation system operation, which is of great significance for ensuring the safe operation of the power system. DETAILED DESCRIPTION

[0043] The purpose of the present invention is to provide an online diagnosis method for abnormal optical path in a substation, which is achieved by the following technical solutions:

[0044] When an optical fiber is subjected to some external force, it will bend (macrobend), and energy will leak out of the cladding. The size of the leaked optical signal is called the leakage optical power. For a section of optical fiber with an internal optical power of P0, the leakage optical power P when it is bent is L ,

[0045]

[0046] In formula (5), α is the optical fiber bending loss coefficient, which is expressed as:

[0047]

[0048] In formula (2), β is the axial propagation constant of the optical fiber; λ is the communication wavelength; n is the cladding refractive index; m is the core refractive index; r is the core radius; R is the optical fiber bending radius;

[0049] Among them, the core radius r, the core refractive index m, and the cladding refractive index n are all related to the optical fiber material. For an optical fiber of a certain material, when the communication wavelength λ and the optical fiber bending radius R remain unchanged, the optical fiber bending loss coefficient α is a constant, that is, the leakage optical power P L It is proportional to the power P0 of the optical signal inside the optical fiber.

[0050] Introduce the fiber bending leakage proportional coefficient K, so For an optical fiber of a certain material, when the communication wavelength λ and the optical fiber bending radius R remain unchanged, K is a constant:

[0051] That is, P L =KP0(1);

[0052] According to the above theory, for an optical fiber of a certain material, a light signal of a specified wavelength is outputted into the optical fiber through a light source, and then the optical fiber is bent to a specified radius, so that a certain light signal is leaked without breaking the optical fiber. By changing the optical power of the optical signal outputted by the light source, the optical power of the optical fiber bending leakage light under different optical powers is obtained, and the optical fiber bending leakage proportional coefficient K under the optical wavelength and bending radius can be obtained.

[0053] For optical fibers of this material, the magnitude of the optical power leakage at the wavelength and bending radius is known. Combined with the optical fiber bending leakage proportional coefficient K, the magnitude of the optical power inside the optical fiber can be calculated.

[0054] According to this principle, for an optical path that has been put into operation, the optical fiber material and optical wavelength used have been determined, and the optical fiber bending leakage proportional coefficient K of each section of optical fiber under a certain bending radius can be obtained. When the optical path is abnormal, firstly, by measuring the corresponding voltage value of the leakage optical power of each section of optical fiber under this bending radius, the size of its internal optical power can be obtained, and then by comparing the internal optical power of the optical fiber with the standard value, the section with optical path abnormality can be found.

[0055] The present invention is further described below in conjunction with specific embodiments.

[0056] Example 1

[0057] An online diagnosis method for abnormality of optical path in a substation comprises the following steps:

[0058] According to the fiber bending leakage theory of the present invention, the fiber bending leakage proportional coefficient K is related to β, r, m, n, λ, and R, where β, r, m, and n are related to the fiber material. Therefore, for a certain fiber material, when λ and R remain unchanged, the magnitude of its leakage optical power P L It is proportional to the internal optical power P0, that is:

[0059] P L =KP0 (1);

[0060] Under the premise that λ and R remain unchanged, the optical power P0 of the optical signal output by the light source is changed, and then the optical power P of the optical fiber bending leakage light under two different optical powers is obtained. L , we can fit a line (P L , P0) straight line, then K is the slope of the straight line under the current λ and R. It can be seen that the calculation of β, r, m, and n parameters is not involved in the calculation process of K.

[0061] In fact, the measurement of PL is realized by a photoelectric detection circuit. In the embodiment, an InGaAs diode and a corresponding amplifier circuit are used to convert PL into a voltage value U, and its conversion function can be expressed as:

[0062] P L = kU + b (3);

[0063] Substituting into formula (1), we can get:

[0064]

[0065] For an optical path to be tested, place the spare optical fiber in a bending mechanism with a specific bending radius for bending. Use an external light source to output an optical signal with the same wavelength as the optical signal inside the optical path to be tested, and measure the voltage value U corresponding to its leakage optical power. Change P0 to obtain two sets of (U, P0) values, and obtain

[0066] When the optical path is abnormal, the voltage value U corresponding to the leakage optical power of each section of the optical fiber under the same bending mechanism is measured and substituted into formula (4) to reflect the internal optical power at this time. By measuring the internal optical power of the optical fiber section by section and comparing it with the standard value, the section with optical path abnormality can be found.

[0067] Example 2

[0068] The abnormal optical path is diagnosed by using the online diagnosis method for abnormal optical path of a substation according to Example 1.

[0069] The wavelength of the optical path to be tested is 1310nm. The spare optical fiber is placed in a bending mechanism with a bending radius of 2cm for bending. An external light source is used to output an optical signal with a wavelength of 1310nm. The input optical power P0 is changed and the voltage value U corresponding to the leakage optical power is measured. Finally, the values ​​of the two test points (U, P0) are (0.806V, -20.2dBm) and (1.061V, -15.2dBm), respectively.

[0070] When the optical path is abnormal, the voltage values ​​corresponding to the bending leakage optical powers of the optical fibers in sections 1, 2 and 3 are 1.214 V, 0.122 V and 0.107 V respectively. Substituting them into formula (4), the corresponding internal optical powers of the optical fibers in sections 1, 2 and 3 are -12.2 dBm, -33.6 dBm and -33.9 dBm respectively.

[0071] Judgment criteria: For a fiber optic receiving port, under the condition of ensuring data quality, the minimum optical power that can be measured is called the optical receiving sensitivity of the port. According to Article 6.2 of the national standard "GB / T 36273-2018 Technical Specification for Digital Interface of Relay Protection and Safety Automatic Devices for Intelligent Substations": The optical receiving sensitivity of the optical fiber port of the secondary equipment of the substation should reach -31dBm (wavelength is 1310nm) and -24dBm (wavelength is 850nm). That is: for the optical fiber port with a wavelength of 1310nm, when the received optical power is less than -31dBm, the port indicates that the optical path is abnormal; for the optical fiber port with a wavelength of 850nm, when the received optical power is less than -24dBm, the port indicates that the optical path is abnormal.

[0072] According to the above judgment criteria, segment 1 is a normal optical path segment, and segment 2 is an abnormal optical path segment. Segment 3 receives the signal from segment 2. Segment 2 is abnormal, and segment 3 receives less signal, so segment 3 is also abnormal.

[0073] Example 3

[0074] The abnormal optical path is diagnosed by using the online diagnosis method for abnormal optical path of a substation according to Example 1.

[0075] Fiber model 2, wavelength 850nm, bending radius 2.5cm, the values ​​of the two test points (U, P0) are (0.927V, -17.2dBm) and (1.362V, -10.5dBm), respectively.

[0076] The wavelength of the optical path to be tested is 850nm. The spare optical fiber is placed in a bending mechanism with a bending radius of 2.5cm for bending. An external light source is used to output an optical signal with a wavelength of 850nm. The input optical power P0 is changed and the voltage value U corresponding to the leakage optical power is measured. Finally, the values ​​of the two test points (U, P0) are (0.927V, -17.2dBm) and (1.362V, -10.5dBm), respectively.

[0077] When the optical path is abnormal, the voltage values ​​corresponding to the bending leakage optical power of the optical fiber in section 1, section 2, and section 3 are 1.096V, 1.057V, and 0.304V respectively, and the corresponding internal optical power of the optical fiber in section 1, section 2, and section 3 is -14.6dBm, -15.2dBm, and -26.8dBm respectively. According to the judgment standard in Example 2, for the optical fiber port with a wavelength of 850nm, when the received optical power is less than -24dBm, the port indicates that the optical path is abnormal, so it can be judged that at this time, section 1 and section 2 are both normal sections of the optical path, and section 3 is an abnormal section of the optical path.

Claims

1. An online diagnosis method for abnormal optical path in a substation, characterized by: First, the fiber bending leakage proportional coefficient K is introduced to calculate the leakage optical power P L Convert it to the optical power P0 inside the fiber, that is: P L =KP0; (1); Then, measure the optical power inside the optical fiber section by section and compare it with the standard value to find the section with abnormal optical path; described K is the fiber bending leakage proportional coefficient; α is the fiber bending loss coefficient; In formula (2), β is the axial propagation constant of the optical fiber; λ is the communication wavelength; n is the cladding refractive index; m is the core refractive index; r is the core radius; R is the optical fiber bending radius.

2. The method for online diagnosis of optical path anomalies in a substation according to claim 1, characterized in that: In the case of leakage optical power P L When converting to the optical power P0 inside the optical fiber, for an optical fiber of a certain material, n is the cladding refractive index; m is the core refractive index; r is the core radius; R is the optical fiber bending radius. Therefore, when the communication wavelength λ and the optical fiber bending radius R remain unchanged, the optical fiber bending leakage coefficient K is a constant, that is, the leakage optical power P L It is proportional to the size of the optical signal power P0 inside the optical fiber.

3. The method for online diagnosis of optical path anomalies in a substation according to claim 1, characterized in that: For an optical fiber of a certain material, a light source is used to output a light signal of a specified wavelength into the fiber. The fiber is then bent to a specified radius, allowing it to leak a certain amount of light without breaking. The optical power of the light signal output by the light source is varied to obtain the optical power of the light leaked from the fiber under different optical powers. The fiber bending leakage coefficient K for this wavelength and bending radius is then calculated. For an optical fiber of this material, the magnitude of the optical power leakage at the wavelength and bending radius is known. Combined with the optical fiber bending leakage proportional coefficient K, the magnitude of the optical power inside the optical fiber is calculated.

4. The method for online diagnosis of optical path anomalies in a substation according to claim 1, characterized in that: The standard value is the optical receiving sensitivity of the optical fiber port of the secondary equipment of the substation: when the wavelength is 1310nm, the optical power reaches -31dBm, and when the wavelength is 850nm, the optical power reaches -24dBm.

5. The method for online diagnosis of optical path anomalies in a substation according to claim 1, characterized in that: The judgment criteria for the section with optical path abnormality are as follows: for the optical fiber port with a wavelength of 1310nm, when the received optical power is less than -31dBm, the port prompts an optical path abnormality; for the optical fiber port with a wavelength of 850nm, when the received optical power is less than -24dBm, the port prompts an optical path abnormality.

6. The method for online diagnosis of optical path anomalies in a substation according to claim 1, characterized in that: Leakage optical power P L The measurement is realized by the photoelectric detection circuit, which uses an InGaAs diode and a corresponding amplifier circuit to convert PL into a voltage value U. Its conversion function is expressed as: Q L =kU+b (3); Where k is the slope and b is the intercept; Substituting formula (3) into formula (1), we get:

7. The method for online diagnosis of optical path anomalies in a substation according to claim 6, characterized in that: For an optical path to be tested, place the spare optical fiber in a bending mechanism with a specific bending radius and bend it. Use an external light source to output an optical signal with the same wavelength as the optical signal inside the optical path to be tested, and measure the voltage value U corresponding to its leakage optical power. Change the input optical power P0 to obtain two sets of (U, P0) values, and obtain When an optical path anomaly occurs in the optical path, the voltage value U corresponding to the leakage optical power of each section of optical fiber under the same bending mechanism is measured and substituted into formula (4) to obtain the magnitude of the optical power inside the optical fiber.

8. The method for online diagnosis of optical path anomalies in a substation according to claim 7, characterized in that: The spare optical fiber is of the same model or material as the optical fiber in the optical path to be tested.

9. The method for online diagnosis of optical path anomalies in a substation according to claim 1, characterized in that: If the section to be tested is after the abnormal section, it is determined that the section to be tested is abnormal.

10. The method for online diagnosis of optical path anomalies in a substation according to claim 1, characterized in that: The following steps are involved: ① The optical fiber bending leakage coefficient K is related to β, r, m, n, λ, and R, among which β, r, m, and n are related to the optical fiber material. Therefore, for an optical fiber of a certain material, when λ and R remain unchanged, the magnitude of its leakage optical power P L It is proportional to the internal optical power P0, that is: P L =KP0 (1); ② Under the premise of keeping λ and R unchanged, change the optical power P0 of the light source output optical signal, and then obtain the optical power P of the optical fiber bending leakage light under two different optical powers. L , the fitting results in a (P L , P0) straight line, then K is the slope of the straight line under the current λ and R; ③P L The measurement is realized by the photoelectric detection circuit, using InGaAs diode and corresponding amplifier circuit to L Converted to voltage value U, its conversion function is expressed as: Q L =kU+b (3); Substituting formula (3) into formula (1), we get: For an optical path to be tested, a spare optical fiber is placed in a bending mechanism with a specific bending radius and bent. An external light source is used to output an optical signal with the same wavelength as the optical signal inside the optical path to be tested and the voltage value U corresponding to the leakage optical power is measured. By changing P0, two sets of (U, P0) values ​​are obtained to obtain ④ When an optical path anomaly occurs in the optical path, the voltage value U corresponding to the leakage optical power of each section of optical fiber under the same bending mechanism is measured and substituted into formula (4) to obtain the magnitude of the optical power inside the optical fiber; by measuring the optical power inside the optical fiber section by section and comparing it with the standard value, the section with the optical path anomaly can be found.

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