Monitoring device and method for insulator failure of line tower
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-08
- Publication Date
- 2026-06-23
AI Technical Summary
Existing technologies struggle to achieve low cost, high reliability, ease of installation, and accurate location of insulation faults in power distribution line towers. Furthermore, sensors are susceptible to interference from complex electromagnetic environments, making it difficult to accurately extract weak fault characteristic signals from noise.
The LI-MR sensor module is used to measure the magnetic field change caused by the fault current of the tower in a non-contact manner. The fault is judged and counted by combining the signal comparison module and the counter module. The power supply module provides working power. The magnetoresistive structure is designed to improve sensitivity and anti-interference ability.
It achieves high sensitivity, low cost, and accurate location of insulation faults in power distribution line towers, overcoming the difficulties in energy extraction and location errors of traditional methods, and is suitable for large-scale promotion.
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Figure CN122260034A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of power system transmission and distribution technology, and in particular to a monitoring device and method for insulation faults in power line towers. Background Technology
[0002] Power distribution lines are a crucial link in the power system, connecting users and distributing electrical energy. Their operational reliability directly affects power supply quality and user safety. Distribution lines are typically widely distributed in complex and diverse environments, constantly exposed to wind, rain, pollution, humidity, and high temperatures. Insulators, surge arresters, and disconnectors are highly susceptible to aging, breakdown, or physical damage, leading to decreased insulation performance and subsequent faults such as single-phase grounding and short circuits. Among these, power poles, as the physical supports of the lines, have grounding down conductors that are critical pathways for fault current discharge. When an insulation fault occurs in the electrical equipment on a power pole, the fault current flows into the ground through the pole's grounding down conductor. Therefore, effective monitoring of the power pole's grounding down conductor current is an important means of achieving early warning and accurate location of insulation faults.
[0003] Currently, various technical solutions exist in the industry for monitoring and locating insulation faults in power distribution line towers, including but not limited to the following: manual inspection and periodic preventive testing, online monitoring devices (such as leakage current monitoring), traveling wave fault location methods, and monitoring methods based on electric fields or traditional current transformers (CTs). These methods, to varying degrees, mostly suffer from problems such as reliance on personnel experience, low efficiency, difficulty in energy extraction, system complexity, inconvenient installation and maintenance, and high costs. For the vast number of power distribution line towers, large-scale promotion and application are difficult, failing to meet the development needs of smart grids.
[0004] In recent years, magnetoresistive sensor technology, such as anisotropic magnetoresistive (AMR), has matured. However, its resistivity is affected by the internal magnetization direction, making it directionally sensitive. AMR sensors offer advantages such as small size, high sensitivity, low power consumption, and no need for physical contact with the measured conductor, providing a new solution for non-contact current measurement. Theoretically, they can be used to measure fault current in the grounding down conductor of power transmission towers. However, directly applying magnetoresistive sensors to locate insulation faults in power distribution line towers still faces a series of unique technical challenges. The electromagnetic environment of power distribution line towers is complex, and sensors are susceptible to interference from strong magnetic fields generated by adjacent line load currents, lightning, and switching operations. Accurately extracting weak fault characteristic signals from complex background noise is a major challenge. For applications involving a massive number of power distribution network towers, the device must also meet extremely low power consumption and cost requirements to achieve long-term maintenance-free operation and large-scale deployment.
[0005] Therefore, there is an urgent need for a device and new technical solution that can overcome the above-mentioned defects of existing technologies, achieve low cost, high reliability, easy installation, and accurate location of insulation fault towers. Summary of the Invention
[0006] The main objective of this invention is to provide a monitoring device and method for insulation faults in power line towers, which can solve the problem of the lack of low-cost, high-reliability, easy-to-install devices and new technical solutions for accurately locating towers with insulation faults in the prior art.
[0007] To achieve the above objectives, a first aspect of the present invention provides a monitoring device for insulation faults in power line towers, the monitoring device comprising: The LI-MR sensor module is installed on the line tower and is used to measure the magnetic field change caused by the insulation fault current of the line tower in a non-contact manner, and output the voltage division value of the magnetoresistive corresponding to the magnetic field change. A signal comparison module, connected to the LI-MR sensor module, is used to compare the voltage division value with a preset reference voltage value. When the voltage division value exceeds the reference voltage value, a trigger signal is output, which indicates that the power pole has an insulation fault. A counter module, connected to the signal comparison module, is used to respond to the trigger signal, perform fault counting operations under the edge triggering of a clock pulse, and display the fault count value; The power supply module is connected to the LI-MR sensor module, signal comparison module, and counter module to provide operating power.
[0008] In one feasible implementation, the LI-MR sensor module includes two magnetoresistive resistors connected in series; wherein, the first magnetoresistive resistor serves as a reference resistor and a magnetic shielding layer is disposed on the surface of the first magnetoresistive resistor; the second magnetoresistive resistor serves as a sensing resistor, and the zero-field resistance value of the second magnetoresistive resistor is the same as the resistance value of the reference resistor, and the voltage divider value includes the resistance voltage divider value taken from the midpoint of the two series-connected magnetoresistive resistors.
[0009] In one feasible implementation, the LI-MR sensor module uses InSb, a magnetically sensitive semiconductor material, as the substrate of the magnetoresistor, and designs the internal structure of the magnetoresistor as a rectangular grid thin film type.
[0010] In one feasible implementation, the voltage divider value is expressed by the following formula:
[0011] in, U m This is the voltage divider value; E This refers to the power supply voltage. The resistance value of the first magnetoresistor under actual magnetic field conditions; The resistance value of the first magnetoresistor under zero-field conditions; G is a preset proportional constant; The vacuum permeability; The electron mobility of the first magnetoresistive sensor; This is the fault current; This is the total path of the fault current flowing through the first magnetoresistor; The distance between the LI-MR sensor module and the path through which the fault current flows; The bandwidth of the first magnetoresistive rectangular grid thin film is given.
[0012] In one feasible implementation, the signal comparison module includes a voltage comparator, the non-inverting input of which is connected to the resistor voltage divider value, and the inverting input of which is connected to the reference voltage value; the reference voltage value is adjusted by an adjustable resistor circuit to adapt to different fault current detection sensitivity requirements.
[0013] In one feasible implementation, the counter module includes a timing control unit and a digital counting module. The timing control unit is used to sample the trigger signal at the rising or falling edge of the clock pulse and control the digital counting chip to increment the count.
[0014] To achieve the above objectives, a second aspect of the present invention provides a method for determining the design parameters of a monitoring device as shown in the first aspect and any feasible implementation, the method comprising: Determine the geometric enhancement factor related to the magnetoresistive structure based on the predetermined minimum value of the rate of change of the magnetoresistive resistance; Based on the geometric enhancement factor, the ratio of the total path of the fault current flowing through the magnetoresistor to the bandwidth of the rectangular grid film of the magnetoresistor is determined to determine the geometric dimensions of the magnetoresistor structure, wherein the geometric dimensions include the total path of the fault current flowing through the magnetoresistor and the bandwidth of the rectangular grid film of the magnetoresistor. The zero-field resistance value of the magnetoresistor is determined using the aforementioned geometric dimensions.
[0015] In one feasible implementation, the determination of the geometric enhancement factor related to the magnetoresistive structure according to the minimum value of the predetermined rate of change of the magnetoresistive resistance includes the following mathematical expression: ; In the formula, The magnetic field strength; μ The electron mobility of the magnetoresistive semiconductor material; This represents the minimum rate of change of the magnetoresistive resistance. It is the geometric enhancement factor.
[0016] In one feasible implementation, determining the ratio of the total path length of the fault current flowing through the magnetoresistor to the bandwidth of the magnetoresistor rectangular grid film based on the geometric enhancement factor includes the following mathematical expression: ; In the formula, G is the geometric enhancement factor; G is the preset proportionality constant. This represents the total path of the fault current flowing through the magnetoresistor. The bandwidth of the rectangular grid thin film for magnetoresistive sensors is given.
[0017] To achieve the above objectives, a third aspect of the present invention provides a method for locating insulation faults in power distribution lines using a monitoring device as shown in the first aspect and any feasible implementation, the method comprising: The monitoring device is installed on each line tower of the power distribution line and initialized; The LI-MR sensor module continuously monitors the magnetic field generated by the fault current that is generated by the fault and grounded through the line tower. When the signal comparison module detects a change in the voltage divider value, it determines that a fault has occurred, drives the counter module to operate, increments the fault count value by 1 and stores it, and displays the fault count value; after the fault is cleared, the fault count value is reset; the fault count value is used by maintenance personnel to determine the faulty line tower based on the fault count value displayed on the line tower.
[0018] The embodiments of the present invention have the following beneficial effects: This invention provides a monitoring device for insulation faults in power transmission towers. The monitoring device includes: a rectangular grid InSb magnetoresistive (LI-MR) sensor module, which is mounted on the power transmission tower and used to measure the magnetic field change caused by the insulation fault current in a non-contact manner, and output the voltage division value of the magnetoresistive sensor corresponding to the magnetic field change; a signal comparison module, connected to the LI-MR sensor module, used to compare the voltage division value with a preset reference voltage value, and output a trigger signal when the voltage division value exceeds the reference voltage value, the trigger signal indicating that an insulation fault has occurred in the power transmission tower; a counter module, connected to the signal comparison module, used to respond to the trigger signal, perform fault counting operation triggered by the edge of a clock pulse, and display the fault count value; and a power supply module, connected to the LI-MR sensor module, the signal comparison module, and the counter module, used to provide operating power.
[0019] This invention proposes a device and method for locating lightning-induced faults on power distribution line towers based on a LI-MR sensor. Fault location is achieved by installing a LI-MR sensor on the power distribution tower and using a signal processing device for signal comparison and counting to detect and process the grounding current generated after a fault and flowing through the tower. A high-sensitivity non-contact LI-MR sensor is used to measure the small-signal and high-frequency transient signals generated by the fault. Furthermore, a voltage comparator and counter enable accurate judgment of tower insulation faults, overcoming the difficulties of energy extraction, inaccurate positioning, and misjudgment faced by traditional power distribution network tower fault location methods. This LI-MR sensor has a simple structure, low cost, and a wider measurement range than an AMR sensor, making it well-suited for locating insulation faults on power distribution network towers. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] in: Figure 1 This is a flowchart illustrating a method for determining design parameters of a monitoring device for insulation faults in power transmission towers, as described in an embodiment of the present invention. Figure 2 This is a structural diagram of a monitoring device for insulation faults in power line towers according to an embodiment of the present invention; Figure 3 This is a circuit diagram of a monitoring device for insulation faults in power transmission towers according to an embodiment of the present invention; Figure 4 This is a structural diagram of an InSb rectangular grid sensor according to an embodiment of the present invention; Figure 5 This is a flowchart illustrating a method for locating insulation faults in power distribution lines using a monitoring device for insulation faults in power line towers, according to an embodiment of the present invention. Detailed Implementation
[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0023] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a sensor and design method for monitoring insulation faults in power distribution towers. This method can non-contactly measure the sudden current caused by insulation faults in power distribution towers and propagating through tower grounding. Through signal recognition and processing, it automatically counts and stores faults, providing maintenance personnel with clear indications of faulty towers, thereby enabling rapid location of insulation faults in power distribution towers.
[0024] Please see Figure 1 , Figure 1 This is a flowchart illustrating a method for determining design parameters of a monitoring device for insulation faults in power transmission towers according to an embodiment of the present invention. The monitoring device can be a power transmission tower insulation fault monitoring sensor. This method for determining design parameters can be implemented during the sensor design process and can also be referred to as a design method. Specifically, it includes the following steps: Step 1: Determine the material and internal structure of the magnetoresistor in the LI-MR sensor module based on the sensitivity requirements of the sensor for monitoring weak currents; Step 2: Design an electrical structure to avoid the temperature-dependent effects on the magnetoresistive properties of the LI-MR sensor module; Step 3: Design the geometry of the magnetoresistor of the LI-MR sensor module to determine its zero magnetic field resistance and resistance value when the fault current is If; Step 4: Design the signal comparison module; Step 5: Design the counter module; Step 6: Design the power supply module.
[0025] As can be seen from the above, the present invention provides a monitoring device for insulation faults in power line towers, the monitoring device comprising: The LI-MR sensor module is mounted on the power line tower and is used to measure the magnetic field change caused by the insulation fault current of the power line tower in a non-contact manner, and output the voltage division value of the magnetoresistive resistor corresponding to the magnetic field change. The LI-MR sensor module can be fixedly installed on the surface of the power distribution line tower and is used to measure the magnetic field change caused by the insulation fault current of the tower in a non-contact manner. The magnetic field change causes a change in the resistance of the magnetoresistive resistor, which in turn leads to a change in the voltage division value of the resistor. A signal comparison module, connected to the LI-MR sensor module, is used to compare the voltage division value with a preset reference voltage value, and to detect when the voltage division value exceeds the reference voltage value. U ref When the power pole tower experiences an insulation fault, a trigger signal is output. A counter module, connected to the signal comparison module, is used to respond to the trigger signal, perform fault counting operations under the edge triggering of a clock pulse, and display the fault count value; The power supply module is connected to the LI-MR sensor module, signal comparison module, and counter module to provide operating power.
[0026] Please see Figure 2 , Figure 2 This is a structural diagram of a monitoring device for insulation faults in power line towers according to an embodiment of the present invention. The monitoring device for insulation faults in power line towers is... Figure 2 The monitoring sensor 3 for insulation faults in the line towers, as referenced Figure 2 As shown, the sensor, which integrates the LI-MR sensor module, signal comparison module, counting module, and power supply module, is fixedly installed on the power distribution line tower using methods such as "clamping" or "adhesive attachment." Following the steps described above, tower insulation fault location can be completed. However, in practical engineering, situations where the fault current is weak may lead to missed detections. Therefore, the LI-MR sensor should be selected and designed according to the possible current range of the power distribution line insulation fault.
[0027] Taking a 35kV and below power distribution line system as an example, when using this LI-MR sensor for fault current detection and location, the detected fault current range needs to cover the fault current values under most fault conditions. In this invention, the possible fault current values are limited to a range of 0.1A to 100A. Analysis shows that the smaller the fault current, the smaller the impact on the magnetic field. Therefore, the LI-MR sensor needs to be designed for small current conditions to ensure its sensitivity is suitable for small current fault detection. For large currents, the large current will cause a more significant change in the magnetic field, and the change in the resistance voltage will be more obvious, making it easier to detect.
[0028] Please refer to Figure 3 , Figure 3 This is a circuit diagram of a monitoring device for insulation faults in power transmission towers according to an embodiment of the present invention. The LI-MR sensor module includes two magnetoresistive resistors (R1 and R2) connected in series. The first magnetoresistive resistor R1 serves as a reference resistor, and a magnetic shielding layer is disposed on its surface. The second magnetoresistive resistor R2 serves as a sensing resistor, and the zero-field resistance value of the second magnetoresistive resistor R2 is the same as the resistance value of the reference resistor. The voltage divider value includes the resistance voltage divider value U drawn from the midpoint of the two series-connected magnetoresistive resistors. m See also Figure 4 , Figure 4 This is a structural diagram of an InSb rectangular grid sensor according to an embodiment of the present invention. The LI-MR sensor module uses the magnetically sensitive semiconductor material InSb as the substrate of the magnetoresistor, and the internal structure of the magnetoresistor is designed as a rectangular grid thin film type, such as... Figure 4 As shown.
[0029] The signal comparison module includes a voltage comparator, the non-inverting input of which is connected to the resistor voltage divider value, and the inverting input of which is connected to the reference voltage value. U ref The reference voltage value is adjusted by an adjustable resistor circuit to adapt to different fault current detection sensitivity requirements.
[0030] Alternatively, a hysteresis comparator can be connected between the resistor voltage divider and the voltage comparator. The inverting input of the hysteresis comparator is connected to the resistor voltage divider, and the non-inverting input is electrically connected to one end of resistor R5 and one end of resistor R6, respectively. The other end of resistor R5 is grounded, and the other end of resistor R6 is connected to the output of the hysteresis comparator. The output of the hysteresis comparator is connected to the non-inverting input of the voltage comparator.
[0031] The adjustable resistor circuit includes resistors R3 and R4. Adjusting R5 or R6 will change U. ref This allows for adjustment of the fault trigger threshold, achieving "different sensitivities".
[0032] The counter module includes a timing control unit and a digital counting module. The timing control unit is used to sample the trigger signal at the rising or falling edge of the clock pulse and control the digital counting chip to increment the count.
[0033] The power module provides a stable power supply for all monitoring and control modules. The power module is a lithium battery or solar power complementary power supply system.
[0034] like Figure 3 As shown in the voltage divider circuit of the LI-MR sensor module, to achieve a significant voltage change in the magnetoresistive resistor affected by magnetic field variations, its resistance value must also change significantly. Based on this, by selecting appropriate materials and designing the structure of the magnetoresistive resistor, it can be made to have high sensitivity even to small currents. The specific design process is as follows: First, determine the fault current. I f The range is 0.1A to 100A. When designing the sensitivity, a minimum current value of 0.1A is considered. The LI-MR sensor is attached to the surface of the tower, which is treated as a long straight conductor. The distance between the sensor and the conductor through which the fault current flows is... d If the distance is 15cm, the magnetic field strength can be calculated using Ampere's law. B Where μ0 is the free permeability, typically taken as 4π*10⁻⁶. 7 H / m, as shown below:
[0035] Once the change in magnetic field strength caused by the current is determined, it is a very weak magnetic field. Therefore, the magnetoresistive sensor requires high sensitivity, necessitating a sensor design based on these sensitivity requirements. InSb is chosen as the magnetoresistive material to improve sensitivity, as it exhibits high sensitivity. While InSb resistivity is significantly affected by temperature, its zero-field resistance is very low. To address the issue of temperature susceptibility, temperature compensation is required during use. Furthermore, a special geometric design is needed to increase the initial resistance while further amplifying its inherent high sensitivity.
[0036] Please see Figure 4 , Figure 4 This is a structural diagram of an InSb rectangular grid sensor according to an embodiment of the present invention, with reference to... Figure 4 As shown, a rectangular lattice structure using InSb thin films is employed. The electron mobility μ of this material is typically 7m. 2 Its resistivity ρ is 5 × 10⁶ V·s. -3 Ω·cm. Therefore, the resistance change of this magnetoresistive element consists of the inherent physical magnetoresistance effect of the material itself and the enhancement effect K brought about by its geometry. The relative rate of change of its total resistance can be described by the following formula:
[0037] To ensure a significant change in voltage division value even with a minimum fault current of 1A, i.e., a sufficiently large rate of resistance change, this invention defines a minimum resistance change of 1%, i.e., a resistance change rate of 0.01. This ensures a noticeable change in the voltage division value, allowing the approximate value of the geometric enhancement factor A to be determined from the above formula. Calculations show that μ... 2 B 2 The numerical value is 8.705 × 10. -13 To achieve a resistivity change rate of 0.01 or higher, the geometric enhancement factor K must be at least approximately 1.148 × 10⁻⁶. 8 The geometry enhancement factor K is a dimensionless coefficient directly related to the grid shape and size, and can be approximated as:
[0038] refer to Figure 4 As shown, G represents a proportionality constant related to the specific layout. It takes into account factors such as the effect at the bend of the meandering grid shape and the strip spacing. It is usually taken in the range of 0.01 to 0.2. In this embodiment, G is taken as 0.1. L is the total path of the fault current flowing through the first magnetoresistor. Specifically, it is the total path length of the current in the grid, which is the sum of the entire meandering path from the start point to the end point. W is the bandwidth of the rectangular grid film of the first magnetoresistor. Specifically, it is the width of each independent InSb strip.
[0039] Once the geometric enhancement factor is determined, the magnetoresistive geometry can be designed by comprehensively considering the rationality of the magnetoresistive parameters and process requirements. Calculations show that with a rectangular grid bandwidth W of 1 μm and a total path length L of 33.88 cm, the aspect ratio is 3.388 × 10⁻⁶. 4 The thickness t of the rectangular grid film is 3 μm.
[0040] Once all the above parameters are determined, the initial resistance (zero-field resistance value) of the magnetoresistor under zero magnetic field conditions can be obtained as shown in the following formula:
[0041] At this point, all the key parameters of the entire DC excitation circuit of the magnetoresistive sensor have been given. In this embodiment, the initial resistance is 565kΩ, and the DC excitation source voltage is 5V. When no fault current flows through the tower (i.e., no magnetic field), the voltage division of the magnetoresistive sensor and the voltage division of the reference resistor are equal, both 2.5V. In this embodiment, when a fault current of 0.1A flows through the tower, the resistance change rate is 0.01, and the voltage division of the magnetoresistive sensor, U, is... m Partial pressure change U m The calculation is as follows:
[0042]
[0043]
[0044] At this point, the voltage drop caused by a 0.1A fault current flowing through the tower is 0.0124V, a significant and easily monitored change. Based on the principle of magnetic induction, when the fault current exceeds 0.1A, the voltage drop across the magnetic sensor becomes more pronounced and easily monitored, offering universal applicability for tower faults. The voltage drop value is transmitted from the measurement and transmission module to the signal comparison circuit. A significant difference between the voltage drop across the reference resistor and the magnetic sensor is compared, and a difference signal is output to the microcontroller unit to drive the counting device. The count value is incremented and stored, completing one fault count. Maintenance and inspection personnel can use the counting device to locate and pinpoint faults.
[0045] As can be seen from the above, by determining the geometric dimensions of the magnetoresistor, its zero magnetic field resistance and its resistance at fault current can be determined. I f The resistance value at that time. The relevant parameters of the LI-MR sensor module are determined as follows: based on the predetermined minimum rate of change of the magnetoresistive resistance. (For example, if the minimum fault current Ifmin = 0.1A, the corresponding resistance change rate is 0.01), determine the geometric enhancement factor K related to the magnetoresistive structure; based on the geometric enhancement factor K, determine the ratio of the total path of the fault current flowing through the magnetoresistive structure to the bandwidth of the magnetoresistive rectangular grid film. The geometry of the magnetoresistive structure is determined by measuring the total path L of the fault current flowing through the magnetoresistive structure and the bandwidth W of the rectangular grid film of the magnetoresistive structure. The zero-field resistance value of the magnetoresistive structure is then determined using these geometry. .
[0046] The step of determining the geometric enhancement factor related to the magnetoresistive structure according to the predetermined minimum value of the magnetoresistive resistance change rate includes the following mathematical expression:
[0047] ; ; In the formula, This refers to the magnetic field strength, specifically the magnetic field strength at the sensor mounting location. The vacuum permeability; The predetermined minimum fault current; The distance between the LI-MR sensor module and the path through which the fault current flows; This represents the minimum rate of change of the magnetoresistive resistance. The geometric enhancement factor is μ, where μ is the electron mobility of the magnetoresistive semiconductor material. This is the initial resistance value of the magnetor when there is zero magnetic field. For magnetoresistive current The change in resistance under the action.
[0048] The step of determining the ratio of the total path length of the fault current flowing through the magnetoresistor to the bandwidth of the rectangular grid film of the magnetoresistor, based on the geometric enhancement factor, includes the following mathematical expression: ; ; In the formula, G is the geometric enhancement factor; G is the preset proportionality constant. This represents the total path of the fault current flowing through the magnetoresistor. The bandwidth of the rectangular grid thin film for magnetoresistive sensors is given.
[0049] The zero-field resistance value R0 of the magnetoresistor is determined as follows:
[0050] in, ρ The resistivity of InSb material. L This is the total length of the current path of the magnetoresistive resistor. W and t These represent the effective current cross-sectional width and thickness of the rectangular grid thin film, respectively.
[0051] ④ Determine the current of the magnetoresistor resistance value at time R m ,for:
[0052] in, μ n The electron mobility of this magnetoresistor is... μ 0 is the permeability of free space. I f Fault current, d This is the distance between the magnetoresistive sensor and the path through which the current flows.
[0053] The partial pressure value is expressed by the following formula:
[0054] in, U m This is the voltage divider value; E This refers to the power supply voltage. The resistance value of the first magnetoresistor under actual magnetic field conditions; The resistance value of the first magnetoresistor under zero-field conditions; G is a preset proportional constant; The vacuum permeability; The electron mobility of the first magnetoresistive sensor; This is the fault current; This is the total path of the fault current flowing through the first magnetoresistor; The distance between the LI-MR sensor module and the path through which the fault current flows; The bandwidth of the first magnetoresistive rectangular grid thin film is given.
[0055] Please see Figure 5 , Figure 5 This is a flowchart illustrating a method for locating insulation faults in power distribution lines using a monitoring device for insulation faults in power transmission towers, according to an embodiment of the present invention. The method includes the following steps: S01: Install the aforementioned sensors on each pole of the power distribution line and initialize them; that is, install the sensors on each pole of the power distribution line as described above. Figure 2 Or the monitoring device shown in Figure 3, and initialize it.
[0056] S02: Continuously monitor the magnetic field generated by the fault current that is generated by the fault and grounded through the tower using a LI-MR sensor; S03: When the signal comparison module detects a change in the voltage divider value, it determines that a fault has occurred, drives the counter to operate, increments the count value by 1, and stores it. The count value is the fault count value, which is used by maintenance personnel to identify the faulty line tower based on the fault count value displayed on the line tower. The fault count value is stored and displayed for easy reference by maintenance personnel. S04: Maintenance personnel determine the faulty towers based on the tower count values; S05: After troubleshooting, reset the count value.
[0057] refer to Figure 5 As shown, the process for monitoring insulation faults in line towers is as follows: When equipment such as line insulators, surge arresters, and disconnectors malfunctions, a fault current is generated. This fault current may flow through the tower. Once the fault current flows through the tower, the magnetic field change caused by the sudden current change can be captured by a LI-MR sensor arranged on the tower surface. This magnetic field change will further affect the magnetic sensor, increasing its magnetic resistance, and the corresponding voltage division will also change. Since the magnetic sensor and the reference resistor have the same value before the current acts, their voltage division values are also the same. The voltage division value is measured and transmitted to the signal comparison circuit for comparison. After the signal comparison module processes the signal and detects a change in the voltage division value, it transmits the signal to the counter module, drives the counter to operate, increments the count value by 1 and stores it, completing one fault counting and location. Maintenance and inspection personnel can check the digital display of the counter to troubleshoot and locate the fault. After clearing the fault, the digital display of the counter can be reset to zero.
[0058] This invention proposes a monitoring device and method for insulation faults in power line towers. It enables the location of lightning-induced faults in power line towers based on a LI-MR sensor. Fault location is achieved by installing a LI-MR sensor and signal processing device on the power line tower to detect and process the grounding current generated after a fault and flowing through the tower. A high-sensitivity non-contact LI-MR sensor is used to measure the small-signal and high-frequency transient signals generated by the fault. Furthermore, a voltage comparator and counter enable accurate judgment of tower insulation faults, overcoming the difficulties of energy extraction, inaccurate positioning, and misjudgment faced by traditional power line tower fault location methods. This LI-MR sensor has a simple structure, low cost, and a wider measurement range than AMR, making it well-suited for the field of power line tower insulation fault location.
[0059] This invention discloses a sensor and design method for monitoring insulation faults in power transmission line towers. The sensor includes a LI-MR sensor module, a signal comparison module, a counter module, and a power supply module. The LI-MR sensor module detects sudden changes in the magnetic field caused by insulation fault current in a non-contact manner, converting the change in magnetoresistive resistance into a voltage divider signal. The signal comparison module compares this signal with an adjustable reference voltage and outputs a trigger signal. The counter module counts and displays fault events. Furthermore, this invention provides a design method for the sensor, including magnetoresistive selection and structural design, temperature effect suppression, parameter calculation, and circuit implementation. The sensor of this invention features simple structure, high sensitivity, and strong anti-interference capability, making it suitable for real-time monitoring and fault location of the insulation status of power transmission line towers, and is of great significance for improving the safe operation level of the power grid.
[0060] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0061] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.
Claims
1. A monitoring device for insulation faults in power line towers, characterized in that, The monitoring device includes: The LI-MR sensor module is installed on the line tower and is used to measure the magnetic field change caused by the insulation fault current of the line tower in a non-contact manner, and output the voltage division value of the magnetoresistive corresponding to the magnetic field change. A signal comparison module, connected to the LI-MR sensor module, is used to compare the voltage division value with a preset reference voltage value. When the voltage division value exceeds the reference voltage value, a trigger signal is output, which indicates that the power pole has an insulation fault. A counter module, connected to the signal comparison module, is used to respond to the trigger signal, perform fault counting operations under the edge triggering of a clock pulse, and display the fault count value; The power supply module is connected to the LI-MR sensor module, signal comparison module, and counter module to provide operating power.
2. The monitoring device according to claim 1, characterized in that, The LI-MR sensor module includes two magnetoresistive resistors connected in series; wherein, the first magnetoresistive resistor serves as a reference resistor and a magnetic shielding layer is disposed on the surface of the first magnetoresistive resistor; the second magnetoresistive resistor serves as a sensing resistor, and the zero-field resistance value of the second magnetoresistive resistor is the same as the resistance value of the reference resistor, and the voltage division value includes the resistance voltage division value taken from the midpoint of the two series-connected magnetoresistive resistors.
3. The monitoring device according to claim 2, characterized in that, The LI-MR sensor module uses InSb, a magnetically sensitive semiconductor material, as the substrate for the magnetoresistor, and designs the internal structure of the magnetoresistor as a rectangular grid thin film type.
4. The monitoring device according to claim 3, characterized in that, The partial pressure value is expressed by the following formula: in, U m This is the voltage divider value; E This refers to the power supply voltage. The resistance value of the first magnetoresistor under actual magnetic field conditions; The resistance value of the first magnetoresistor under zero-field conditions; G is a preset proportional constant; The vacuum permeability; The electron mobility of the first magnetoresistive sensor; This is the fault current; This is the total path of the fault current flowing through the first magnetoresistor; The distance between the LI-MR sensor module and the path through which the fault current flows; The bandwidth of the first magnetoresistive rectangular grid thin film is given.
5. The monitoring device according to claim 4, characterized in that, The signal comparison module includes a voltage comparator, the non-inverting input of which is connected to the resistor voltage divider value, and the inverting input of which is connected to the reference voltage value. The reference voltage value is adjusted by an adjustable resistor circuit to adapt to different fault current detection sensitivity requirements.
6. The monitoring device according to claim 1, characterized in that, The counter module includes a timing control unit and a digital counting module. The timing control unit is used to sample the trigger signal at the rising or falling edge of the clock pulse and control the digital counting chip to increment the count.
7. A method for determining the design parameters of a monitoring device as described in any one of claims 1-6, characterized in that, The method includes: Determine the geometric enhancement factor related to the magnetoresistive structure based on the predetermined minimum value of the rate of change of the magnetoresistive resistance; Based on the geometric enhancement factor, the ratio of the total path of the fault current flowing through the magnetoresistor to the bandwidth of the rectangular grid film of the magnetoresistor is determined to determine the geometric dimensions of the magnetoresistor structure, wherein the geometric dimensions include the total path of the fault current flowing through the magnetoresistor and the bandwidth of the rectangular grid film of the magnetoresistor. The zero-field resistance value of the magnetoresistor is determined using the aforementioned geometric dimensions.
8. The method according to claim 7, characterized in that, The geometric enhancement factor related to the magnetoresistive structure is determined according to the minimum value of the predetermined rate of change of magnetoresistive resistance, including the following mathematical expression: ； In the formula, The magnetic field strength; μ The electron mobility of the magnetoresistive semiconductor material; This represents the minimum rate of change of the magnetoresistive resistance. It is the geometric enhancement factor.
9. The method according to claim 8, characterized in that, The determination of the ratio of the total path length of the fault current flowing through the magnetoresistor to the bandwidth of the rectangular grid film of the magnetoresistor, based on the geometric enhancement factor, includes the following mathematical expression: ； In the formula, G is the geometric enhancement factor; G is the preset proportionality constant. This represents the total path of the fault current flowing through the magnetoresistor. The bandwidth of the rectangular grid thin film for magnetoresistive sensors is given.
10. A method for locating insulation faults in power distribution lines using the monitoring device as described in any one of claims 1-6, characterized in that, The method includes: The monitoring device is installed on each line tower of the power distribution line and initialized; The LI-MR sensor module continuously monitors the magnetic field generated by the fault current that is generated by the fault and grounded through the line tower. When the signal comparison module detects a change in the voltage divider value, it determines that a fault has occurred, drives the counter module to operate, increments the fault count value by 1 and stores it, and displays the fault count value; after the fault is cleared, the fault count value is reset; the fault count value is used by maintenance personnel to determine the faulty line tower based on the fault count value displayed on the line tower.