Intelligent monitoring method for grounding switch state
By deploying fiber optic sensors on the grounding switch to collect multi-dimensional mechanical parameters and perform temperature compensation, and combining this with preset thresholds to determine the grounding switch status, the problem of response delay and fault identification in complex environments by traditional detection methods is solved, and high-precision fault early warning is achieved.
Patent Information
- Application Number
- CN202511584260.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-31
- Publication Date
- 2026-02-03
AI Technical Summary
Existing grounding switch condition detection technologies suffer from response delays, wear, and poor contact in complex electromagnetic environments and high-altitude environments. Traditional single-point temperature or strain monitoring cannot effectively capture multi-field coupling changes, making it difficult to accurately identify faults.
Fiber optic sensors are deployed at the stress location of the grounding switch to collect the actual principal axial stress, transverse frictional stress, and stress change rate. Combined with preset thresholds, the grounding switch status is determined. Accurate mechanical parameters are obtained through temperature compensation, and multi-dimensional synchronous data diagnostic rules are established.
It enables accurate fault identification of grounding switches in complex environments, improves the accuracy and reliability of detection, and can provide timely warnings of faults such as non-closed, poor contact, and jamming.
Smart Images
Figure CN121453360A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of grounding knife state detection, in particular to an intelligent monitoring method for grounding knife state. BACKGROUND
[0002] As a key protection device in the power system, the grounding knife switch is mainly used for forcibly grounding electrical equipment during maintenance or failure to ensure the safety of personnel and equipment. Its action reliability directly affects the stability of the power grid, and the state detection technology is the core link to ensure the normal function of the grounding knife switch.
[0003] The current commonly used grounding knife state detection method mainly uses contact elements such as travel switches and auxiliary contacts, which has problems such as response delay, easy wear, and poor contact, and is difficult to operate stably in complex electromagnetic environments and high-altitude environments. At the same time, the traditional single-point temperature or strain monitoring method has limited spatial dimensions and cannot effectively capture the changes in multiple fields, making it difficult to accurately identify common faults such as "not in place", "stuck", and "virtual connection".
[0004] Therefore, an intelligent monitoring method for grounding knife state is provided. SUMMARY
[0005] Therefore, the present application provides an intelligent monitoring method for grounding knife state, which uses real main axial stress, lateral friction stress, and real main axial stress change rate in combination with a preset threshold to determine the current state of the grounding knife.
[0006] To this end, the present application provides the following technical solutions: An intelligent monitoring method for grounding knife state, comprising: arranging an optical fiber sensor at a force position of the grounding knife to collect a mechanical parameter signal; temperature compensating the mechanical parameter signal to obtain a real main axial stress; using the real main axial stress, lateral friction stress, and real main axial stress change rate in combination with a preset threshold to determine the current state of the grounding knife, comprising: if the real main axial stress exceeds the preset threshold, it is determined that the knife switch is not in place; if the ratio of the lateral friction force to the real main axial stress exceeds the preset threshold, it is determined that the contact is poor; if the real main axial stress change rate is less than the preset threshold, it is determined that the mechanism is stuck.
[0007] Further, the arrangement of the optical fiber sensor at the force position of the grounding knife to collect the mechanical parameter signal comprises: A plurality of parallel grooves are arranged on the surface of the main shaft of the grounding knife along the axial direction; a plurality of fiber Bragg gratings are connected in series on a single optical fiber as a fiber Bragg grating array sensor, which is embedded and fixed in each groove; A single fiber Bragg grating is tightly wound on the surface of the main shaft in an equiangular spiral manner at one end of the main shaft close to the operating mechanism; A micro groove is arranged on the surface of the copper alloy contacted by each blade and the static contact finger; a micro-bend optical fiber sensor sensitive to pressure deformation is embedded in the groove; Two fiber Bragg gratings are pasted on the surface of the connecting rod in an X-shaped cross manner along the length direction.
[0008] Further, the temperature compensation of the mechanical parameter signal to obtain the main shaft axial stress includes: The center wavelengths of all fiber Bragg gratings are collected; The main shaft axial stress is calculated based on the axial array and the fiber Bragg grating wavelength for temperature measurement wound in a spiral manner.
[0009] Further, the main shaft axial stress calculated based on the axial array and the fiber Bragg grating wavelength for temperature measurement includes:
[0010]
[0011]
[0012] Wherein, is the total change of the fiber Bragg grating wavelength; is the strain sensitivity coefficient; is the real strain caused by the machine; is the material thermal expansion coefficient; is the temperature sensitivity coefficient; is the elastic modulus; is the false strain caused by thermal expansion; is the main shaft axial real stress value; is the temperature change in the cabinet.
[0013] Further, the plurality of parallel grooves arranged on the surface of the main shaft of the grounding knife along the axial direction include: Four parallel grooves are arranged, and the adjacent grooves are spaced 90° apart.
[0014] Further, the micro groove arranged on the surface of the copper alloy contacted by each blade and the static contact finger includes: 1-2 pressure sensing points are arranged on each blade.
[0015] Advantages and positive effects of the present application: 1) The method uses optical fibers to carry out targeted and in-situ sensing arrangement in three key stress dimensions, directly obtains multi-dimensional physical quantities, replaces traditional single-point or contact sensors, and realizes distributed optical fiber multi-modal monitoring of armored switch cabinet grounding knife switches.
[0016] 2) The method solves the fundamental interference problem of temperature on strain measurement under complex working conditions by temperature compensation of optical fiber detection signals, and ensures the accuracy and reliability of key mechanical parameters, i.e. stress and strain measurement.
[0017] 3) The method establishes a quantifiable diagnostic rule based on the physical mechanism of the temperature-compensated mechanical parameters combined with multi-dimensional synchronous data, directly identifies specific failure modes such as misalignment, poor contact, and jamming, and realizes precise early warning. BRIEF DESCRIPTION OF DRAWINGS
[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0019] Figure 1 The intelligent monitoring method flow chart of the grounding knife state of the embodiment of the present application; Figure 2 The three-dimensional optical fiber arrangement schematic diagram of the embodiment of the present application; Figure 3 The position detection precision comparison diagram of the embodiment of the present application; Figure 4 The fault early warning response time comparison diagram of the embodiment of the present application; Figure 5 The contact surface temperature distribution simulation diagram of the embodiment of the present application; Figure 6 The stress response comparison diagram of the embodiment of the present application. DETAILED DESCRIPTION
[0020] In order to make the person skilled in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.
[0021] It should be noted that the terms "first", "second", and the like in the description and in the claims of the present application and above-described accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a particular sequential or chronological order. It should be understood that the data thus used can be interchanged under appropriate circumstances so that the embodiments of the application described herein can be implemented in other than the order illustrated or described herein. Moreover, the terms "comprising" and "having", and any variations thereof, are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or apparatus that includes a list of steps or units is not necessarily limited to those steps or units that are clearly listed, but can include other steps or units that are not clearly listed or inherent to such processes, methods, products, or apparatuses.
[0022] The application provides an intelligent monitoring method for the state of a grounding knife: S1, a three-dimensional optical fiber sensor is laid out to collect a grounding knife state representation signal.
[0023] The optical fiber sensor is closely arranged along the main shaft of the grounding knife to monitor the axial displacement change, and the precision is high.
[0024] The optical fiber sensor is arranged in a radial spiral winding mode to collect the torsional stress in the operation process of the knife switch.
[0025] The micro-bending optical fiber sensor is embedded in the key part of the contact surface of the blade to detect the contact surface pressure.
[0026] S2, the influence of temperature on the strain of the optical fiber in the optical fiber signal is reduced through temperature compensation, more real mechanical strain and stress values are obtained, and the interference of temperature change on the strain measurement result is eliminated.
[0027] Strain-temperature decoupling model:
[0028]
[0029]
[0030] wherein, is the total change of the wavelength of the optical fiber Bragg grating; is the strain sensitivity coefficient; is the real strain caused by the mechanical; is the material thermal expansion coefficient; is the temperature sensitivity coefficient; is the elastic modulus; is the false strain caused by thermal expansion; is the real stress value in the main shaft direction; is the temperature change; , Temperature in the armored movable metal-enclosed switchgear,
[0031] S3, using the compensated axial stress , transverse friction stress , temperature and its rate of change Determine the current grounding knife state: Establish a four-dimensional state matrix:
[0032] Where, The main axial stress is used to determine whether the grounding knife is fully closed; The transverse friction force is used to determine whether the contact is slipping or not; The temperature in the cabinet is used to eliminate the interference of thermal stress; The stress change rate is used to determine whether the action is stuck or slow response.
[0033] Determine the grounding knife state according to the four-dimensional state matrix: When the main axial stress exceeds the preset threshold, it is determined that the knife switch is not in place; If the ratio of the transverse friction force to the main axial stress exceeds the preset threshold, it is determined that the contact is poor; If the main axial stress change rate is greater than or equal to the preset threshold, it is determined that the mechanism is stuck; In this embodiment, the threshold values are: The knife switch is not in place; It is poor contact; It is a mechanism stuck.
[0034] Embodiment In combination Figure 1 As shown in the figure, an intelligent monitoring method for the state of the grounding knife, comprising: S1, fiber sensor installation and wiring: 1, detect the main axial stress of the fiber: 1) On the surface of the stainless steel main shaft of the grounding knife, 4 parallel grooves are marked along the axial direction, and the adjacent grooves are distributed at an interval of 90°.
[0035] 2) A plurality of fiber Bragg gratings are connected in series on a single fiber as a fiber Bragg grating array sensor, embedded and fixed in each groove. The spacing between the fiber Bragg gratings on a single fiber is 10mm.
[0036] 3) Use high-temperature resistant epoxy resin glue to fix the fiber in the groove, and ensure that it is closely attached to the surface of the main shaft.
[0037] 2. Fiber optic layout for monitoring the radial torsion stress of the main shaft: As shown in the figure, at the end of the main shaft close to the operating mechanism, at the end of the larger stress area, a single fiber Bragg grating is tightly wound in an equiangular spiral manner on the surface of the main shaft, with a spiral angle of 45° and about 7 turns, and is fixed using high-temperature-resistant glue. Figure 2
[0038] 3. Fiber optic sensor layout for monitoring the contact pressure of the blade: A micro-groove is provided on the copper alloy surface of each blade in contact with the static finger.
[0039] A micro-bend fiber optic sensor sensitive to pressure deformation is embedded in the groove, ensuring that the sensor surface is flush or slightly lower than the working surface of the finger.
[0040] Typically, 1-2 pressure sensing points are arranged on each blade, which are fixed with high-temperature-resistant, high-thermal-conductivity insulating glue.
[0041] 4. Fiber optic layout for monitoring the bending moment of the operating connecting rod On the connecting rod connecting the main shaft and the operating mechanism, two fiber Bragg gratings are pasted on the surface of the connecting rod in an X-shaped cross manner along the length direction. It is used to monitor the bending deformation during operation and to assist in determining whether the action is smooth.
[0042] 5. Fiber optic lead and protection: All sensor fibers are collected into a dedicated IP67 protection level junction box in the switch cabinet. The fiber optic lead uses armored cable, which is drawn out from the inner wall of the switch cabinet or the reserved hole through the metal hose, and connected to the signal processing unit outside the cabinet. Ensure that the fiber bending radius is greater than the working threshold, preferably 5 cm.
[0043] S2, reduce the influence of temperature on strain in fiber optic signal through temperature compensation, obtain more real mechanical strain and stress value, and eliminate the interference of temperature change on strain measurement result.
[0044] 1) The demodulator scans the center wavelength of all fiber Bragg gratings in real time. The edge computing unit periodically reads all fiber Bragg grating wavelength data output by the demodulator through Ethernet / TCP protocol.
[0045] 2) Temperature-strain decoupling calculation: For the fiber Bragg gratings on the main shaft for measuring strain, the wavelengths of the axial array and the spiral winding fiber Bragg gratings for measuring temperature are read, and the temperature change and the real mechanical strain are calculated.
[0046] Based on the temperature change and the real mechanical strain, the compensated axial stress is obtained.
[0047] The compensated axial stress, transverse friction stress and axial stress change rate are used to determine the current ground blade state.
[0048] Based on the above method and the existing detection technology, a position detection accuracy comparison chart is shown in Figure 3 , a fault early warning response time comparison chart is shown in Figure 4 , a contact surface temperature distribution simulation chart is shown in Figure 5 , and a stress response comparison chart is shown in Figure 6 .
[0049] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.
Claims
1. A method for intelligent monitoring of ground blade status, characterized in that, The application relates to a method for judging the current state of a grounding knife. The method comprises the following steps:
1. arranging optical fiber sensors at the force receiving position of the grounding knife to collect mechanical parameter signals; 2. performing temperature compensation on the mechanical parameter signals to obtain real main shaft stress; 3. judging the current state of the grounding knife by combining the real main shaft stress, transverse friction stress and real main shaft stress change rate with preset thresholds, including: a. when the real main shaft stress exceeds the preset threshold, it is determined that the knife gap is not in place; b. when the ratio of the transverse friction stress to the real main shaft stress exceeds the preset threshold, it is determined that the contact is poor; 2. The method of claim 1, wherein, c. when the real main shaft stress change rate is less than the preset threshold, it is determined that the mechanism is jammed. The method for arranging optical fiber sensors at the force receiving position of the grounding knife to collect mechanical parameter signals comprises the following steps:
1. arranging a plurality of parallel grooves on the surface of the stainless steel main shaft of the grounding knife along the axial direction; 2. embedding and fixing a plurality of fiber Bragg gratings connected in series on a single optical fiber as a fiber Bragg grating array sensor in each groove; 3. tightly winding a single fiber Bragg grating in an equiangular spiral manner on the surface of the main shaft at the end close to the operating mechanism; 3. The method of claim 1, wherein, 4. arranging a micro groove on the copper alloy surface of each blade in contact with the static contact finger; 5. embedding a micro-bend optical fiber sensor sensitive to pressure deformation in the groove; 6. pasting two fiber Bragg gratings in an X-shaped cross manner on the surface of the connecting rod along the length direction.
4. The method of claim 3, wherein, The method for performing temperature compensation on the mechanical parameter signals to obtain main shaft stress comprises the following steps: wherein, is the total change of wavelength of the fiber Bragg grating; is the strain sensitivity coefficient; is the real strain caused by the mechanical; is the thermal expansion coefficient of the material; is the temperature sensitivity coefficient; is the elastic modulus; is the false strain caused by the thermal expansion; is the real stress value in the main axis direction; is the temperature change in the cabinet.
5. The method of claim 2, wherein, 1. collecting the center wavelengths of all fiber Bragg gratings; 2. calculating the main shaft stress based on the wavelengths of the fiber Bragg gratings for temperature measurement in the axial array and the spiral winding.
6. The method of claim 2, wherein, The method for calculating the main shaft stress based on the wavelengths of the fiber Bragg gratings for temperature measurement in the axial array and the spiral winding comprises the following steps:
1. calculating the main shaft stress based on the wavelengths of the fiber Bragg gratings for temperature measurement in the axial array and the spiral winding. The method for arranging a plurality of parallel grooves on the surface of the stainless steel main shaft of the grounding knife along the axial direction comprises the following steps:
1. arranging four parallel grooves, and the interval between adjacent grooves is 90 degrees. The method for arranging a micro groove on the copper alloy surface of each blade in contact with the static contact finger comprises the following steps:
1. arranging 1-2 pressure sensing points on each blade.