A high-voltage line suspension clamp stress monitoring and early warning system

Abstract

This invention relates to a stress monitoring and early warning system for suspension clamps in high-voltage power lines, belonging to the field of intelligent monitoring of high-voltage lines. The system consists of RFID sensing tags installed on the suspension clamps and an inspection RFID reader. The RFID sensing tag integrates a force-sensitive overload memory unit, a tag chip, and an antenna. Magnetostrictive alloy microwires within the unit are connected to the force transmission path. When the tensile force exceeds a threshold, an irreversible martensitic phase transformation occurs, resulting in a permanent step decrease in magnetic permeability. The tag chip detects this change via a magnetic sensing circuit, hardware-locking and rewriting the overload flag in the non-volatile storage area. The reader reads the flag non-contactly to determine the overload history and calculates the real-time tensile force through the antenna resonant frequency deviation. The reader can be equipped with a drone or handheld terminal to automatically record overload information and generate work orders. The backend server integrates the data to achieve lifespan prediction and batch replacement planning. This system is passive, maintenance-free, and tamper-proof, combining overload memory and stress detection to improve the safety and intelligence level of line operation and maintenance.

Description

Technical Field

[0001] This invention relates to the field of intelligent monitoring of high-voltage lines, specifically to a high-voltage line suspension clamp stress monitoring and early warning system. Background Technology

[0002] Suspension clamps are key hardware components in high-voltage overhead lines, connecting conductors to tower insulator strings and bearing the function of transferring conductor loads. Under conditions such as icing and strong winds, the tensile force on the clamps may exceed the design safety threshold, leading to clamp deformation, conductor slippage, or even wire breakage. Therefore, effective monitoring of the stress state of suspension clamps and early warning of overload events are urgent needs for line operation and maintenance.

[0003] Existing monitoring methods mainly fall into two categories. One category involves real-time monitoring using resistance strain gauges or piezoelectric force sensors. This approach relies on battery or solar power, making long-term maintenance-free operation difficult in remote pole environments. External sensors require additional clamps, potentially altering the original force transmission path of the clamps. Furthermore, continuous data transmission places high demands on the communication network, resulting in significant maintenance costs. The other category is manual inspection, which checks the clamp tightness monthly or quarterly. However, the long inspection cycle makes it impossible to detect sudden short-term overload events during the inspection intervals. Moreover, manual inspection only checks the current status of the clamps and cannot determine whether they have experienced overloads exceeding thresholds in historical operation, posing hidden safety hazards.

[0004] While RFID technology has been introduced into power line inspection, existing RFID tags only have identification functions and lack the ability to sense mechanical conditions and record events. For the vast majority of existing power poles without real-time sensors, the backend database lacks mechanical data for comparison, making it difficult to detect wire clamp overload history through RFID inspection.

[0005] In summary, existing technologies lack a method that can permanently record clamp overload events in an indelible manner without relying on external power sources and real-time communication networks. This method must meet the following requirements: automatic recording upon overload without requiring power; the record must be indelible and cannot be erased manually or accidentally; and the recorded information must be easily accessible non-contact during inspections, providing a reliable basis for maintenance decisions. Summary of the Invention

[0006] Purpose of the invention: To provide a high-voltage line suspension clamp stress monitoring and early warning system to solve the above-mentioned problems existing in the prior art.

[0007] Technical solution: A high-voltage line suspension clamp stress monitoring and early warning system, including an RFID sensor tag fixed on the load-bearing component of the suspension clamp and an RFID reader for inspection, further:

[0008] The RFID sensing tag includes a force-sensitive overload memory unit, a tag chip, and an antenna connected to the tag chip.

[0009] The force-sensitive overload memory unit is connected in series to the force transmission path of the suspension clamp to transmit tension to the conductor, and it includes a housing and a magnetostrictive alloy microwire encapsulated in the housing.

[0010] The two ends of the magnetostrictive alloy microwire are rigidly connected to the force-bearing component, so that the tension of the conductor is applied to the microwire in a predetermined proportion.

[0011] The microfilament is designed to maintain its initial permeability when the applied tensile force is less than or equal to a preset safety threshold, but when the applied tensile force exceeds the preset safety threshold, stress-induced irreversible preferred orientation of martensite variants occurs inside, resulting in a step-like permanent decrease in the permeability of the microfilament.

[0012] The tag chip is coupled to the magnetostrictive alloy microwire through a magnetic sensing circuit to detect the step permanent decrease in the magnetic permeability, and irreversibly rewrites an overload flag bit from a value representing normal logic to a value representing overload logic in the non-volatile storage space of the tag chip.

[0013] The RFID reader reads the overload flag bit through the antenna and outputs a judgment result on whether the clamp has been overloaded based on the current logic state of the flag bit.

[0014] In a further embodiment, the magnetostrictive alloy microwire is made of iron-gallium or iron-cobalt based alloy, with a diameter of 30~200μm and a length of 5~30mm; the magnetostrictive alloy microwire bears the tension of the conductor along its axial direction, and its length direction is consistent with the direction of tension transmission.

[0015] In a further embodiment, the housing is further provided with an elastic pretensioner, which applies an axial pretension force to the magnetostrictive alloy microfilament. The magnitude of the pretension force is set to 50% to 80% of the preset safety threshold. When the resultant force of the pretension force and the wire tension exceeds the preset safety threshold, the magnetostrictive alloy microfilament triggers the irreversible preferred orientation of the martensitic variant.

[0016] In a further embodiment, the housing is made of insulating ceramic or engineering plastic, with metal terminals embedded at both ends; the two ends of the magnetostrictive alloy microwire are fixed and electrically connected to the metal terminals by micro-arc welding or conductive silver paste; the metal terminals are exposed outside the housing and rigidly connected to the force-bearing component, and also serve as the excitation-detection electrode pair of the magnetic sensing circuit.

[0017] In a further embodiment, the preset safety threshold is determined jointly by the cross-sectional area of ​​the magnetostrictive alloy microwire and the critical stress value of the alloy material, satisfying... ,in To preset a safety threshold, The critical stress at which the alloy material undergoes the irreversible orientation of the martensitic variant, and A is the cross-sectional area of ​​the microfilament.

[0018] In a further embodiment, the magnetic sensing circuit includes a high-frequency excitation coil and a detection coil, which are coaxially sleeved on the outer periphery of the magnetostrictive alloy microwire. The tag chip supplies a constant amplitude AC excitation current to the high-frequency excitation coil and picks up the induced voltage through the detection coil. When the permeability undergoes a step-like permanent decrease, the amplitude of the induced voltage decreases accordingly. The tag chip determines that an overload event has occurred by comparing the amplitude of the induced voltage with a preset reference voltage threshold and performs an irreversible rewriting of the overload flag.

[0019] In a further embodiment, the non-volatile storage space is a specific location in the EEPROM or FRAM storage area built into the tag chip. This specific location is written to logic "0" during the factory initialization of the RFID sensor tag. When the tag chip performs the irreversible rewrite, it rewrites the specific location to logic "1", and the rewrite operation is hardware locked to prevent any subsequent write-back operation to logic "0".

[0020] In a further embodiment, the antenna is a dipole antenna or a microstrip patch antenna printed on a flexible dielectric substrate, which is attached and fixed to the surface of the load-bearing component of the suspension clamp; the resonant frequency of the antenna is designed to shift with the strain of the load-bearing component; the RFID reader also obtains an estimated value of the tension currently borne by the suspension clamp by detecting the resonant frequency shift of the antenna.

[0021] In a further embodiment, the RFID reader is mounted on an inspection drone or a handheld inspection terminal; when the RFID reader approaches the suspension clamp at a preset reading distance, it automatically activates the RFID sensor tag and reads the overload flag; when the overload flag indicates an overload event, the RFID reader writes the pole number, clamp position, and overload flag corresponding to the suspension clamp into the inspection log and generates a replacement and maintenance work order.

[0022] In a further embodiment, a backend server is also included. The backend server receives the overload flags and tensile force estimates of multiple poles and multiple suspension clamps uploaded by the RFID reader. Based on the statistical overload records of multiple clamps on the same pole and the historical trend of the tensile force estimates, the backend server generates a prediction of the remaining life of the clamps in the pole section and a batch replacement plan.

[0023] Beneficial effects: This invention relates to a high-voltage line suspension clamp stress monitoring and early warning system, which has the following beneficial effects:

[0024] 1. Passive permanent memory: Utilizing the irreversible martensitic phase transformation of magnetostrictive alloy microwires, overload events are permanently recorded once they occur, without the need for any external power source or battery. The tag life is comparable to that of circuit fittings (≥20 years).

[0025] 2. Anti-tampering: The overload flag is locked by hardware logic and cannot be erased or reset by any software or external reading device, eliminating the possibility of human-made forgery of security records.

[0026] 3. Low power consumption and high reliability: The energy consumption of a single overload detection is ≤1μJ, and it can be reliably completed under far-field RF power supply; subsequent inspections of historical overload tags are read with zero power consumption.

[0027] 4. Dual parameter acquisition: A single inspection simultaneously obtains historical information on whether the system has ever been overloaded and a real-time estimate of the current stress, significantly improving the information density for maintenance decisions.

[0028] 5. Adaptable to intelligent operation and maintenance: The back-end server generates remaining life prediction and replacement plan based on batch data of multiple towers, which can realize the transformation from "passive emergency repair" to "proactive prevention". It is expected to reduce the failure rate of clamps by more than 30% and reduce unplanned power outage time. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the application scenario of the high-voltage line suspension clamp stress monitoring and early warning system described in this invention.

[0030] Figure 2 This is a schematic diagram of the composition framework of the high-voltage line suspension clamp stress monitoring and early warning system described in this invention; it shows the arrangement relationship of the suspension clamp force-bearing components, force-sensitive overload memory unit, tag chip and antenna; the solid arrow indicates the direction of conductor tension transmission, the force-sensitive overload memory unit is connected in series in the conductor force transmission path of the suspension clamp, and the conductor tension is applied to the internal magnetostrictive alloy microwire according to a predetermined ratio; Figure 2The dashed line is an auxiliary line for defining the functional range. It is only used for the overall layout area of ​​the logic loop force-sensitive overload memory unit and does not represent the outline of the physical mechanical structure, nor does it participate in the transmission of tensile force.

[0031] Figure 3 This is a schematic diagram of the magnetic sensing circuit described in this invention.

[0032] Figure 4 This is a schematic diagram illustrating the structure of the high-voltage line suspension clamp stress monitoring and early warning system described in this invention.

[0033] Figure descriptions: 1. Magnetostrictive alloy microfilament: the core force sensing element, undergoing an irreversible martensitic phase transformation under overload; 2. High-frequency excitation coil: coaxially sleeved around the microfilament, through which a constant amplitude AC excitation current is passed; 3. Detection coil: coaxially sleeved around the microfilament, picking up the induced voltage to detect changes in permeability; 4. Tag chip: with built-in magnetic sensing comparison circuit and non-volatile memory area, hardware-locked and rewritten overload flag bit. Detailed Implementation

[0034] To more clearly illustrate the technical solutions of the embodiments in this specification, the embodiments will be described in detail below with reference to the accompanying drawings. Obviously, the content described below are some examples or embodiments of this specification. For those skilled in the art, without creative effort, the technical solutions or means disclosed in this specification can be applied to other scenarios based on this technical content.

[0035] It should be understood that the terms "system," "device," "unit," and / or "module" used in this specification are a method of distinguishing different components, elements, parts, sections, or assemblies at different levels. However, if other terms can achieve the same purpose, they may be replaced by other expressions.

[0036] Unless otherwise specified, the technical terms used to describe components, elements, etc. in this specification are not singular but may include plural. Generally speaking, terms such as "comprising" or "including" only indicate that clearly identified steps, elements, or components are included, and these steps, elements, and components do not constitute an exclusive list, as the described method or apparatus may also include other steps or components.

[0037] This specification uses flowcharts to illustrate the operational steps performed by the apparatus or system of related embodiments. However, unless otherwise specified, the order in which these steps are described should not be construed as a limitation on the order of execution. Those skilled in the art can adjust the order of these steps based on the knowledge and information conveyed by the embodiments in this specification. Such adjustments include, but are not limited to, reversing the order of steps, merging multiple steps, and splitting a step.

[0038] This embodiment provides a high-voltage line suspension clamp stress monitoring and early warning system. The system consists of two main parts: an RFID sensing tag fixed on the load-bearing component of the suspension clamp and an RFID reader for inspection. The RFID sensing tag integrates a force-sensitive overload memory unit. This unit utilizes the physical effect of an irreversible microscopic phase transition of a specific alloy microwire under overstress, resulting in a permanent change in magnetic permeability, to achieve passive and indelible recording of overload events.

[0039] Figure 2 The installation position of the force-sensitive overload memory unit in the force transmission path of the suspension clamp in this embodiment is shown. The force-sensitive overload memory unit is connected in series in the force transmission path from the suspension clamp to the conductor. Specifically, the force-bearing component of the suspension clamp (e.g., the connecting section of the hanging plate or pressure plate) is divided into a first connecting end and a second connecting end. The force-sensitive overload memory unit is connected in series between the first connecting end and the second connecting end, so that all or proportionally distributed tension of the conductor is directly transmitted through this unit.

[0040] The force-sensitive overload memory unit includes a housing and a magnetostrictive alloy microwire encapsulated within the housing. The two ends of the magnetostrictive alloy microwire are rigidly connected to the force-bearing component. The microwire bears the tension of the conductor along its axial direction, and the length direction of the microwire is consistent with the direction of force transmission. It should be noted that the microwire is not fixed by conventional mechanical clamping, but rather by rigid connection using metal terminals; this will be described in detail in the housing structure section.

[0041] In this embodiment, the magnetostrictive alloy microwire is made of iron-gallium alloy, with a diameter of 100 μm and a length of 15 mm. The selection of these dimensions is based on the following criteria: the diameter must strike a balance between meeting a preset safety threshold requirement and ensuring the alloy microwire does not break under normal operating tensile force; the length must consider both the sensitivity of the magnetic sensing circuit and the miniaturization requirements of the housing. In actual products, the microwire diameter can be selected from 30 μm to 200 μm, and the length from 5 mm to 30 mm.

[0042] Furthermore, the percentage of gallium atoms in the iron-gallium alloy is 15%~22%; the percentage of cobalt atoms in the iron-cobalt alloy is 30%~50%, with trace amounts of grain-refining elements such as niobium and vanadium added.

[0043] The heat treatment process for magnetostrictive alloy microwires is as follows: solution treatment at 850℃~950℃ for 1 hour under vacuum or a protective atmosphere, followed by rapid water quenching, and then aging at 350℃~450℃ for 2 hours to obtain the initial... <100> Texture.

[0044] Critical stress σ cThe determination method is as follows: The engineering stress value corresponding to the point where the permeability begins to decrease is obtained through uniaxial tensile testing combined with in-situ permeability measurement. The example provides measured values: σ for iron-17% gallium alloy. c = 480±20MPa.

[0045] Permeability variation range: Before and after overload, the relative permeability decreased from μr0 = 1200~1800 to μr1 = 400~800, a decrease of 50%~60%.

[0046] Irreversibility verification: The overloaded microfilament was unloaded and reheated to 200℃ and held for 24 hours. The magnetic permeability did not recover. XRD showed that the orientation of the martensite variant was not reversed.

[0047] The passive, non-erasable overload memory function achieved by this solution relies on a specific microscopic phase transition mechanism that occurs in magnetostrictive alloy microwires under overstress conditions. This is the core innovation that distinguishes this invention from existing technologies, and it will now be explained in detail from the perspectives of materials science and physics.

[0048] Magnetostrictive alloy microwires are made of iron-gallium or iron-cobalt based alloys, and their initial state (i.e., the state after specific heat treatment at the time of manufacture) has axial... <100> With a preferred orientation texture, the initial permeability of the microfilament is μ0. The magnitude of this initial permeability depends on the alloy composition, crystal structure, and heat treatment process parameters of the microfilament.

[0049] When the tension in the conductor is transmitted to the microfilament through the stressed component, an axial normal stress σ is generated inside the microfilament. This normal stress is calculated according to the following formula:

[0050]

[0051] Where F is the tension acting on the microfilament, A is the cross-sectional area of ​​the microfilament, A=πd² / 4, and d is the diameter of the microfilament.

[0052] This embodiment sets a preset safety threshold F. th The physical meaning of this threshold is: when F ≤ F th When the normal stress σ inside the microfilament does not exceed the critical stress σc required for the alloy material to undergo irreversible preferred orientation of martensite variants; when F>Fth, σ exceeds σc, triggering an irreversible phase transformation.

[0053] Preset safety threshold F th Determined by the following formula:

[0054]

[0055] Taking the iron-gallium alloy microwire with a diameter d = 100 μm in this embodiment as an example, the critical stress σ of this alloy cApproximately 450 MPa, substituting into the above formula yields F th ≈3.53N. This value range exactly matches the upper limit of the tensile force required for safe operation of the suspension clamp.

[0056] Furthermore, the specific process of the irreversible phase transition is described in detail below:

[0057] When the applied tensile force is less than or equal to the preset safety threshold F th When the normal stress σ inside the microfilament is ≤ σ c The magnetic permeability is insufficient to drive a change in the orientation of the martensitic variant, and the microfilament maintains its initial permeability μ0. The permeability value detected by the magnetic sensing circuit remains within a stable baseline range each time.

[0058] When the tension exceeds the preset safety threshold F th When the normal stress σ inside the microfilament is greater than σ, c Stress-induced martensitic phase transformation is initiated. Martensitic variants in iron-gallium or iron-cobalt based alloys undergo preferred orientation under stress—that is, martensitic variants that were originally randomly distributed or along different orientations migrate and merge at their interfaces under axial tensile stress exceeding the critical stress, forming a configuration of martensitic variants arranged along a single orientation. This process is stress-driven and requires no external electrical energy input.

[0059] More importantly, this stress-induced preferred orientation process of martensitic variants is irreversible. After stress unloading, the already formed single-orientation variant orientation configuration will not spontaneously revert to the initial multi-orientation distribution state. This is because: first, the variant interface migration process involves the collective cooperative movement of a large number of atoms, and reverse migration requires overcoming a high energy barrier; second, the crystal structure of the alloy and the pre-set heat treatment process make the initial multi-orientation state metastable, while the stress-driven single-orientation state is thermodynamically more stable; third, the mechanical constraints (rigid connection at both ends) on the microfilaments also inhibit the reverse phase transformation after unloading. Therefore, once overload occurs and the phase transformation is completed, this change will be permanently preserved, forming a "material self-memory" effect.

[0060] After the phase transition, the permeability of the magnetostrictive alloy microwire decreases permanently and irreversibly from its initial value μ0 to μ1. The mechanism of this permeability reduction lies in the fact that the magnetostrictive effect is closely related to the magnetocrystalline anisotropy and internal stress distribution of the material. In the initial multi-orientation state, the migration resistance of the domain walls under the drive of an external magnetic field is relatively small, resulting in higher permeability. When a single-orientation martensitic variant orientation configuration is formed, the magnetocrystalline anisotropy is enhanced, the domain structure is reconstructed, and the pinning effect of domain wall migration is strengthened, leading to a significant decrease in permeability. Experiments show that the permeability of the iron-gallium alloy microwire can decrease by about 30% to 60% during the above phase transition process, a change sufficient to be reliably detected by subsequent magnetic sensing circuits.

[0061] It should be noted that the total tension on the conductor borne by the suspension clamp during actual operation... Typically, the tensile force ranges from several thousand to tens of thousands of Newtons (for example, the rated breaking force of the JL / G1A-300 / 40 wire is approximately 93.5 kN, and the safe operating tensile force is generally between 20 and 30 kN). If the magnetostrictive alloy microfilament were to directly bear the entire tensile force, the microfilament diameter would need to be increased to the millimeter level, which would significantly reduce sensing sensitivity and increase housing size, making it unfavorable for engineering applications.

[0062] To address this, the system incorporates a force transmission ratio adjustment mechanism within the force-sensitive overload memory unit. This mechanism reduces the total tensile force on the suspension clamp by a preset constant ratio before applying it to the magnetostrictive alloy microwire, ensuring that the force on the microwire matches its range and guaranteeing accurate and reliable overload triggering. The force transmission ratio adjustment mechanism employs a rigid parallel split structure, consisting of a main load-bearing rod, a sensing branch, a rigid connecting plate, and a ratio adjustment shim, connected in series within the force transmission path of the suspension clamp. The main load-bearing rod is made of high-strength metal of the same material as the clamp's load-bearing components, exhibiting high rigidity and bearing the majority of the tensile force. The sensing branch, comprising the magnetostrictive alloy microwire, an insulating shell, and metal terminals, exhibits low rigidity, bearing only a proportionally distributed small tensile force. The main load-bearing rod and the sensing branch are fixed in parallel via the rigid connecting plate, ensuring synchronous force application without gaps or slippage. The ratio adjustment shim is used to precisely adjust the stiffness ratio, locking the force transmission ratio K. The force transmission ratio K is the ratio of the tension on the microfilament to the total tension of the clamp, ranging from 1 / 5000 to 1 / 200. During operation, the total tension is distributed between the two branches inversely proportional to stiffness, with the microfilament bearing only the proportional load. The K value can be precisely calibrated by adjusting the shim thickness. After manufacturing, it exhibits no creep or drift and remains stable over the long term. During calibration, the safe threshold for the total tension of the clamp is determined according to the circuit requirements. The trigger threshold is determined based on the microfilament material and cross-sectional dimensions. ,according to The target ratio is calculated so that K falls within the range of 1 / 5000 to 1 / 200. After calibration with a tensile testing machine, it is assembled and used, with a ratio error not exceeding ±3%. When the clamp is under stress, this mechanism distributes the total tensile force proportionally to K, keeping the microfilament within a safe range. When the total tensile force reaches the design threshold, the microfilament is precisely stressed, triggering an irreversible martensitic phase transformation and accurately recording the overload event. This mechanism is a purely mechanical, passive structure, requiring no energy consumption and maintenance. Its service life is consistent with that of the clamp, and it is suitable for stress monitoring of suspension clamps in various high-voltage lines.

[0063] A specific design example illustrates this: Using an iron-gallium alloy microwire with a diameter d = 200 μm, its critical stress σ... c =500 MPa, then the tensile threshold that the microfilament can withstand is

[0064]

[0065] If the safety threshold requirement for the total tensile force of the clamp is F th,total =15 kN, then take the force transmission ratio In practical design, K=1 / 1000 can be selected. By adjusting this ratio, the microfilament will trigger an irreversible phase transition exactly when the total tensile force reaches 15kN, thus accurately reflecting the overload state of the clamp.

[0066] In a further preferred embodiment, an elastic preload member is also provided inside the housing, which applies an axial preload force F to the magnetostrictive alloy microwire. pre Preload F pre The size is set to the preset safety threshold F th 50% to 80%, i.e., F pre = (0.5~0.8)×F th .

[0067] The function of the elastic preload is twofold: first, it eliminates any slack that may exist during the manufacturing and installation of the microfilament, ensuring that the microfilament is always under tension during normal operation, thereby improving the accuracy of tensile force measurement and overload detection; second, by using preload, it raises the working stress level of the microfilament to a state close to but not exceeding the critical stress σ_c, making the microfilament more sensitive to external overloads—it can trigger an irreversible phase transition when the actual additional tensile force is small, thus achieving effective recording of minor overloads.

[0068] After setting the preload, the condition for triggering the irreversible preferred orientation of the martensitic variant becomes:

[0069]

[0070] Where F wireThis is the actual additional tensile force transmitted from the conductor's force to the microfilament via the load-bearing component. Therefore, the actual overload triggering external load on the microfilament is reduced to:

[0071] This effectively improves the system's sensitivity to detecting minor overloads.

[0072] The housing is made of insulating ceramic or engineering plastic (such as polyetheretherketone, PEEK), with metal terminals embedded at both ends. The metal terminals can be made of stainless steel, titanium alloy, or a conductive alloy with excellent compatibility with the microfilament material.

[0073] The two ends of the magnetostrictive alloy microwire are fixed and electrically connected to metal terminals by micro-arc welding or conductive silver paste. Micro-arc welding can achieve reliable welding without damaging the internal microstructure of the microwire, while conductive silver paste is suitable for low-temperature curing processes, which can avoid the damage to the heat treatment state of the microwire caused by high temperatures.

[0074] The metal terminals are exposed outside the housing and rigidly connected to the load-bearing components, serving as the excitation-detection electrode pair for the magnetic sensing circuit. The advantages of this design are: the metal terminals function as both mechanical connections and electrical signal interfaces, simplifying the system structure; simultaneously, since the metal terminals and the microfilament share the same current path, the application of excitation and the acquisition of detection signals are completed on the same physical path, reducing the number of signal leads and connection points, and improving reliability.

[0075] Figure 3 The structure of the magnetic sensing circuit in this embodiment is shown. The magnetic sensing circuit includes a high-frequency excitation coil and a detection coil, which are coaxially sleeved on the outer periphery of the magnetostrictive alloy microwire. The coil frame can be integrally formed with the housing or independently mounted on the inner wall of the housing.

[0076] The tag chip supplies a constant amplitude AC excitation current I_exc to the high-frequency excitation coil. The frequency of this excitation current must be selected to meet the following conditions: the frequency should be high enough to ensure a significant change in the amplitude of the induced voltage of the detection coil, but not so high that the skin effect would affect the magnetic field distribution inside the microfilament. In this embodiment, the excitation frequency is selected in the range of 100kHz to 1MHz.

[0077] The excitation current generates an excitation magnetic field H around the microfilament. exc This magnetic field induces a change in magnetic flux density inside the microfilament. According to Faraday's law of electromagnetic induction, the amplitude of the induced voltage V_sense picked up by the detection coil is proportional to the permeability μ of the microfilament, satisfying:

[0078]

[0079] Where N det To detect the number of coil turns, A coilH is the equivalent cross-sectional area of ​​the coil. Under the condition that the excitation current amplitude and frequency are fixed, H exc The amplitude is constant, therefore V sense The amplitude is proportional to the effective permeability μ of the microfilament.

[0080] When the permeability of the microfilament decreases permanently in a step due to overload—that is, from μ0 to μ1—the amplitude of the induced voltage picked up by the detection coil also decreases in a step from V0 to V1:

[0081]

[0082] The tag chip has an internal voltage comparison circuit that compares the amplitude of the induced voltage picked up by the detection coil with a preset reference voltage threshold V. ref Compare. V ref The settings are based on:

[0083]

[0084] That is, V ref The value is set between V0 and V1 to ensure reliable differentiation between the normal state and the step decrease state of permeability under conditions with sufficient noise tolerance.

[0085] When V sense ≥V ref When V is constant, it is determined that the permeability of the microfilament does not decrease abruptly, i.e., it is a load event that has never been experienced before; when V sense <V ref At that time, it was determined that the permeability of the microfilament had undergone a step-like permanent decrease, that is, an overload event had occurred.

[0086] The tag chip has a built-in non-volatile memory space, which is a specific location in the EEPROM or FRAM storage area, called the overload flag bit. During the factory initialization of the RFID sensor tag, this overload flag bit is written with a value representing the normal state. In this embodiment, logic "0" represents no overload and logic "1" represents overload.

[0087] When the magnetic sensing circuit detects a step-like permanent decrease in magnetic permeability, the tag chip triggers an irreversible rewriting process of the overload flag. The specific process includes the following steps:

[0088] S1: The magnetic sensing circuit detects V sense <V ref It sends an overload event detection signal;

[0089] S2: The hardware logic circuit of the tag chip receives the detection signal and generates a one-time write enable pulse;

[0090] S3: Under the control of the enable pulse, the current value of the memory address where the overload flag is located—logic "0"—is rewritten to logic "1";

[0091] S4: After the write operation is completed, the hardware logic circuit pulls the write protection latch signal high to lock the write channel of that memory address. Thereafter, any write operation request to the overload flag (including requests to write back logic "0") is blocked by the hardware logic gate, ensuring that the overload flag remains permanently at logic "1".

[0092] It is important to emphasize that the irreversibility of the rewriting operation is guaranteed by hardware logic, rather than relying on firmware or software judgment. This design ensures that even if the tag chip is attempted to be rewritten by an unauthorized external reading device, or if an anomaly such as a single-event upset occurs in a strong electromagnetic interference environment, the overload flag will not be cleared or tampered with. This is fundamentally different from existing technologies that simply rely on firmware to set the flag, which can theoretically be reset.

[0093] This system uses passive RFID sensing tags, with its operating power entirely derived from the radio frequency field emitted by the reader. To ensure reliable overload detection within a typical reading distance (3-8 meters), the tag chip employs the following low-power strategy:

[0094] The chip only initiates an overload detection process once the output voltage of the energy harvesting circuit reaches the reset threshold.

[0095] The high-frequency excitation coil does not operate continuously, but is driven in a pulse manner, with a pulse width not exceeding 100μs and a duty cycle ≤10%;

[0096] After the test is completed, the tag chip immediately shuts down the excitation circuit and stores the test result (overload flag) in non-volatile memory;

[0097] For tags that have already experienced overload, the magnetic permeability has been permanently reduced. In subsequent inspections, the chip can skip the excitation detection step and directly read the stored flag bit, further reducing energy consumption.

[0098] Actual measurements show that the total energy consumption of a single overload detection (including excitation, sampling, comparison, and flag rewriting) is less than 1 μJ, which is far lower than the energy budget (approximately 10~20 μJ) that a typical passive RFID tag can obtain under far-field conditions, thus ensuring that the system can operate reliably at any normal operating distance.

[0099] In this embodiment, the antenna is a dipole antenna or a microstrip patch antenna printed on a flexible dielectric substrate. The flexible dielectric substrate is bonded and fixed to the surface of the load-bearing component of the suspension clamp, for example, bonded to the side of the mounting plate or the top surface of the pressure plate. The substrate is made of a flexible material such as polyimide that is resistant to high temperatures and ultraviolet aging to ensure the stability of the antenna's electrical performance during long-term outdoor operation.

[0100] The resonant frequency f of the antenna res It depends not only on the antenna's geometry and dielectric parameters, but also on the strain state of the substrate—the load-bearing component. When the load-bearing component is subjected to a conductor tension F... wire_tota When elastic strain ε occurs under the action of l, the antenna attached to it is stretched synchronously, causing the resonant frequency of the antenna to shift. The resonant frequency shift Δf has a good linear relationship with the strain ε of the component, so the magnitude of the tensile force borne by the stressed component can be inferred by detecting Δf.

[0101] The load-bearing components of the suspension clamp are typically made of steel or aluminum alloy, and their strain under safe operating tension generally does not exceed 0.1%. To ensure that the antenna resonant frequency offset falls within the reliable detection range of the RFID reader, this system employs the following special design for the antenna:

[0102] The flexible substrate uses a high dielectric constant material (such as ceramic-filled polyimide, εr≥6εr≥6) to enhance the modulation effect of strain on the equivalent electrical length.

[0103] The antenna radiator adopts a meanderline or serpentine structure, which increases the resonant frequency shift caused by unit strain by 3 to 5 times;

[0104] Typical design parameters are: when the strain of the stressed component is 0.05%, the resonant frequency shift is not less than 1MHz.

[0105] The RFID reader transmits interrogation signals in 100kHz frequency sweeps. By detecting the frequency point corresponding to the peak strength of the response signal, the difference between the current resonant frequency and the initial frequency without strain can be calculated. Then, a calibration coefficient is used to estimate the tension. This estimation is accurate enough to identify whether the clamp is in a significant overload or slack state, without requiring the level of a precision sensor, thus meeting the application requirements of inspection and pre-screening.

[0106] The specific detection process is as follows: When the RFID reader transmits an interrogation signal, it sweeps the frequency across a certain range above and below the resonant frequency of the antenna when there is no strain. The RFID tag's response signal strength varies at different frequencies, reaching its maximum at the resonant frequency. The RFID reader obtains the current resonant frequency f by detecting the frequency corresponding to the peak response strength. res ′, and calculate the estimated tensile force using the following formula:

[0107]

[0108] Where E is the elastic modulus of the stressed member, S is the equivalent cross-sectional area of ​​the stressed member, and f res0The resonant frequency of the antenna in a strain-free state (which can be measured during installation and calibration), Δf = f res0 -f res ′ represents the offset of the resonant frequency, and K is a calibration coefficient related to the antenna structure and bonding method, which can be determined experimentally.

[0109] In this way, during a single inspection and reading operation, the RFID reader can not only obtain historical information about whether the clamp has been overloaded (overload flag), but also obtain the real-time estimated value of the current tensile force of the clamp (resonant frequency offset), thus realizing the dual functions of recording historical overload events and detecting the current mechanical state.

[0110] The RFID reader is mounted on an inspection drone or a handheld inspection terminal. During the inspection, when the inspection drone flies near the pole or the inspection personnel arrive at the base of the pole, the RFID reader automatically activates the RFID sensor tag and reads the overload flag when it approaches the suspension clamp at a preset reading distance (usually 2m to 10m, depending on the reader's transmission power and antenna gain).

[0111] The RFID sensing tag is a passive UHF tag. Its working energy is obtained entirely by the radio frequency energy emitted by the RFID reader and collected by the antenna. It does not require an internal battery and is completely maintenance-free.

[0112] After the RFID reader reads the overload flag, it performs different operations based on the value of the flag: if the flag is logic "0", it indicates that the clamp has not experienced an overload event exceeding the safety threshold in its historical operation and is currently in normal operation. The reader records the normal inspection information and continues the inspection of the next tower. If the flag is logic "1", it indicates that the clamp has experienced an overload event. Even if there is no obvious damage to its appearance, the reliability of the clamp has decreased and there is a potential risk of failure.

[0113] When the overload flag indicates an overload event, the RFID reader automatically performs the following operations: writes the tower number corresponding to the suspension clamp (obtainable through GPS positioning and comparison with preset tower coordinates), the installation position of the clamp on the tower (A phase / B phase / C phase / ground wire side, etc.), and the overload flag status into the inspection log, and generates a replacement and maintenance work order. The work order information can be uploaded to the backend server in real time via the wireless communication network, or it can be imported into the operation and maintenance management system in batches after the inspection is completed.

[0114] Furthermore, the calibration and compensation methods for the antenna strain measurement tension are as follows:

[0115] Calibration steps: Place the suspension clamp with the RFID sensor tag on the universal tensile testing machine, and gradually load it to the design tensile range (0~1.2 times the rated load). Use a network analyzer to record the antenna resonant frequency f.res The fitting yields the tensile force F = α·(Δf / fr). es0 ) + β, where α and β are calibration coefficients, determined by the least squares method.

[0116] Temperature compensation: A reference antenna with the same structure as the main antenna but without strain is integrated on a flexible substrate (coplanar with the main antenna but independent). This reference antenna only responds to temperature changes. The RFID reader simultaneously reads the frequency offset of both antennas, specifically the frequency offset of the main antenna. Reference antenna frequency offset Thus, the frequency deviation caused by pure strain is separated. .

[0117] Dynamic interference elimination: Since the reading time of the drone or handheld terminal during the inspection is extremely short (<0.1 seconds), and hovering or stabilization is required during reading, the clamp can be considered to be in a quasi-static state at this time. If a rapid frequency fluctuation (e.g., >10Hz) is detected, the tensile force estimation is abandoned, only the overload flag is read, and the measurement is repeated after stabilization.

[0118] In a further preferred embodiment, the system also includes a backend server. This backend server receives overload flag data and estimated tension values ​​of multiple poles and suspension clamps uploaded by the RFID reader. The backend server runs a life assessment algorithm to perform a comprehensive analysis based on the following information:

[0119] (1) Overload record statistics of multiple clamps on the same tower: If multiple clamps on the same tower trigger the overload indicator, it indicates that the tower section may have been subjected to regional extreme weather conditions (such as large-area icing), and the batch replacement of the section should be arranged first.

[0120] (2) Historical trend of tensile force estimation: By analyzing the trend of tensile force estimation obtained from multiple inspections of the same clamp, it is possible to identify whether the clamp is in a long-term slow overload state (such as the continuous increase of tensile force caused by conductor creep), thereby generating a prediction of remaining life.

[0121] (3) Judgment of the combination of overload flag and current tension: If the overload flag is “1” but the current tension estimate has fallen back to the normal range, it means that the overload is a historical event and replacement should be arranged as soon as possible; if the overload flag is “1” and the current tension estimate is still too high, it means that a continuous overload is occurring and emergency repairs should be arranged immediately.

[0122] Based on the above analysis results, the backend server generates a prediction of the remaining lifespan of the clamps in the tower section and a batch replacement plan, realizing the transformation from "passive emergency repair" to "proactive prevention" operation and maintenance mode.

[0123] The beneficial effects that the embodiments in this specification may bring may include, but are not limited to:

[0124] (1) By using the stress-induced irreversible martensitic variant preferred orientation effect of magnetostrictive alloy microwires, passive permanent memory of overload events can be achieved without batteries or external power sources.

[0125] (2) The overload flag is locked by hardware logic and cannot be cleared manually or by software, ensuring the immutability of the overload record;

[0126] (3) The RFID reader automatically reads the overload flag in a non-contact manner during inspection, which is efficient and does not require the establishment of a real-time communication network.

[0127] (4) The antenna has both communication and strain sensing functions, and can acquire historical overload information and current tensile force estimation value at the same time in one reading;

[0128] (5) The backend server generates remaining life prediction and batch replacement plan based on multi-clip overload statistics and tensile trend analysis to achieve intelligent operation and maintenance. It should be noted that different embodiments may produce different beneficial effects. In different embodiments, the beneficial effects may be any one or a combination of the above, or any other possible beneficial effects.

[0129] The basic concepts have been described above. It is obvious that the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification. Although not explicitly stated herein, various modifications, improvements, and corrections may be made to this specification by those skilled in the art. Such modifications, improvements, and corrections are taught in this specification and therefore remain within the spirit and scope of the exemplary embodiments described herein.

Claims

1. A high-voltage line suspension clamp stress monitoring and early warning system, comprising an RFID sensing tag fixed to the stress-bearing component of the suspension clamp and an RFID reader for inspection, characterized in that, The RFID sensing tag includes a force-sensitive overload memory unit, a tag chip, and an antenna connected to the tag chip. The force-sensitive overload memory unit is connected in series in the force transmission path of the suspension clamp to transmit tension to the conductor. It includes a housing and a magnetostrictive alloy microwire encapsulated within the housing. The force-sensitive overload memory unit also includes a force transmission ratio adjustment mechanism, which makes the tension acting on the magnetostrictive alloy microwire a predetermined ratio K of the total tension of the suspension clamp, where K ranges from 1 / 5000 to 1 / 200. The two ends of the magnetostrictive alloy microwire are rigidly connected to the force-bearing component, so that the tension of the conductor is adjusted according to... A predetermined ratio is applied to the magnetostrictive alloy microfilament; the magnetostrictive alloy microfilament is designed to maintain its initial permeability when the applied tensile force is less than or equal to a preset safety threshold, but when the applied tensile force exceeds the preset safety threshold, stress-induced irreversible preferred orientation of martensitic variants occurs inside, resulting in a step-like permanent decrease in the permeability of the microfilament; the tag chip is coupled to the magnetostrictive alloy microfilament through a magnetic sensing circuit to detect the change in permeability, and irreversibly rewrites an overload flag bit from a value representing normal logic to a value representing overload logic in the non-volatile storage space of the tag chip; The RFID reader reads the overload flag bit through the antenna and outputs a judgment result on whether the clamp has been overloaded based on the current logic value of the flag bit.

2. The high-voltage line suspension clamp stress monitoring and early warning system according to claim 1, characterized in that: The magnetostrictive alloy microwire is made of iron-gallium or iron-cobalt based alloy, with a diameter of 30~200μm and a length of 5~30mm; the magnetostrictive alloy microwire bears the tension of the conductor along its axial direction, and its length direction is consistent with the direction of tension transmission.

3. The high-voltage line suspension clamp stress monitoring and early warning system according to claim 2, characterized in that: The housing is also provided with an elastic pretensioner, which applies an axial pretension force to the magnetostrictive alloy microfilament. The magnitude of the pretension force is set to 50% to 80% of the preset safety threshold. When the resultant force of the pretension force and the wire tension exceeds the preset safety threshold, the magnetostrictive alloy microfilament triggers the irreversible preferred orientation of the martensitic variant.

4. The high-voltage line suspension clamp stress monitoring and early warning system according to claim 2, characterized in that: The housing is made of insulating ceramic or engineering plastic, with metal terminals embedded at both ends; the two ends of the magnetostrictive alloy microwire are fixed and electrically connected to the metal terminals by micro-arc welding or conductive silver paste; the metal terminals are exposed in the housing and rigidly connected to the force-bearing component, and also serve as the excitation-detection electrode pair of the magnetic sensing circuit.

5. A high-voltage line suspension clamp stress monitoring and early warning system according to claim 2, characterized in that: The preset safety threshold is determined by the cross-sectional area of ​​the magnetostrictive alloy microwire and the critical stress value of the alloy material, satisfying the following conditions: ,in To preset a safety threshold, The critical stress at which the alloy material undergoes the irreversible orientation of the martensitic variant, and A is the cross-sectional area of ​​the microfilament.

6. A high-voltage line suspension clamp stress monitoring and early warning system according to claim 1, characterized in that... The magnetic sensing circuit includes a high-frequency excitation coil and a detection coil, which are coaxially sleeved on the outer periphery of the magnetostrictive alloy microwire. The tag chip only supplies a constant amplitude AC excitation current to the high-frequency excitation coil with a pulsed excitation current (duty cycle ≤10%) after receiving an interrogation command from the RFID reader and the energy harvesting circuit reaches its operating voltage, and picks up the induced voltage through the detection coil. When the permeability undergoes a step-like permanent decrease, the amplitude of the induced voltage decreases accordingly. The tag chip determines that an overload event has occurred by comparing the amplitude of the induced voltage with a preset reference voltage threshold and performs an irreversible rewriting of the overload flag. The total energy consumption of a single overload detection process does not exceed 1 μJ.

7. The high-voltage line suspension clamp stress monitoring and early warning system according to claim 1, characterized in that: The non-volatile storage space is a specific location in the EEPROM or FRAM storage area built into the tag chip. This specific location is written to logic "0" during the factory initialization of the RFID sensor tag. When the tag chip performs the irreversible rewrite, it rewrites this specific location to logic "1", and this rewrite operation is hardware locked to prevent any subsequent write-back operation to logic "0".

8. The high-voltage line suspension clamp stress monitoring and early warning system according to claim 1, characterized in that: The antenna is a dipole antenna or a microstrip patch antenna printed on a flexible dielectric substrate, which is attached and fixed to the surface of the load-bearing component of the suspension clamp. The flexible dielectric substrate is made of a high dielectric constant material with a dielectric constant εr ≥ 6, and the antenna structure is a tortuous or serpentine line to make the resonant frequency sensitive to strain. The resonant frequency of the antenna is designed to shift with the strain of the load-bearing component, and the resonant frequency shift is not less than 1MHz when the strain of the load-bearing component is 0.05%. The RFID reader also obtains an estimated value of the tension currently borne by the suspension clamp by detecting the resonant frequency shift of the antenna.

9. A high-voltage line suspension clamp stress monitoring and early warning system according to any one of claims 1 to 8, characterized in that: The RFID reader is mounted on an inspection drone or handheld inspection terminal. When the RFID reader approaches the suspension clamp at a preset reading distance, it automatically activates the RFID sensor tag and reads the overload flag. When the overload flag indicates an overload event, the RFID reader writes the pole number, clamp position, and overload flag corresponding to the suspension clamp into the inspection log and generates a replacement and maintenance work order.

10. A high-voltage line suspension clamp stress monitoring and early warning system according to claim 1, characterized in that: It also includes a back-end server, which receives the overload flags and tension estimates of multiple poles and multiple suspension clamps uploaded by the RFID reader; The backend server generates a prediction of the remaining lifespan of the clamps in the same tower section and a batch replacement plan based on the statistical overload records of multiple clamps on the same tower and the historical trend of the estimated tension.

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