A triboelectric-electromagnetic composite self-powered sensing and monitoring device suitable for transmission lines

Abstract

The present invention discloses a triboelectric-electromagnetic composite self-powered sensor monitoring device suitable for power transmission lines. The device comprises a magnetically levitated triboelectric-electromagnetic composite energy harvester connected to a sensor monitoring system via an energy management circuit; the magnetically levitated triboelectric-electromagnetic composite energy harvester is used to convert power transmission line vibrations into electrical energy; the energy management circuit is used to maximize the extraction of electrical energy generated by the magnetically levitated triboelectric-electromagnetic composite energy harvester through electromagnetic and triboelectric generation via different front-end interfaces, store the energy in a supercapacitor or energy storage battery, and then control the output level to the sensor monitoring system; the sensor monitoring system is used to collect temperature and vibration information of the power transmission line, store the data, and perform abnormal wake-up and data transmission, thereby realizing remote health monitoring of the power transmission line. The present invention achieves self-powered monitoring of low-frequency vibrations caused by breezes on power transmission lines, ensuring the extended operation of sensor monitoring nodes.

Description

Technical Field

[0001] The present invention relates to the field of monitoring technology, and in particular to a triboelectric-electromagnetic composite self-powered sensing monitoring device suitable for power transmission lines. Background Art

[0002] In recent years, my country's power development has continued to advance. The safe and stable operation of transmission lines affects the performance of the entire power grid system. However, in actual operating environments, transmission lines are often subject to harsh natural conditions, making them prone to safety accidents. To monitor the safety and stability of transmission lines, manual inspections or grid-mounted monitoring devices are commonly used. However, manual inspections pose challenges such as difficulty monitoring in remote areas, inaccurate visual observations, and high manual monitoring costs. Furthermore, some existing grid-mounted monitoring devices suffer from maintenance difficulties and limited operating hours.

[0003] Traditional monitoring devices are almost always powered by lithium batteries, which have limited operating life and pose environmental risks when discarded. Harvesting energy from the environment, such as solar, wind, and thermal energy, and converting it into electricity to power the device is environmentally sensitive and has limited application scenarios. Furthermore, electromagnetic induction power generation cannot be applied to DC transmission lines.

[0004] Low-frequency vibrations are common in transmission lines due to wind excitation. This vibration can be harnessed to collect energy and monitor its condition simultaneously, unrestricted by time or environmental constraints. Ambient energy harvesters with a single conversion mechanism have limited energy collection efficiency. To further increase this efficiency, a hybrid electromagnetic-triboelectric energy harvesting method is used. Hybrid energy harvesters can leverage the advantages of multiple power generation types, tailored to different application scenarios, to improve output performance under varying input conditions.

[0005] Current monitoring methods lack sustainability, and ambient energy harvesting technologies also suffer from low self-powered energy output, heavy and bulky energy harvesting devices, poor environmental tolerance and stability, incomplete system matching, and low integration. Therefore, designing a highly efficient and compact self-powered sensor monitoring device suitable for transmission lines is crucial for achieving self-powered sensor monitoring of transmission lines. Summary of the Invention

[0006] In view of this, the present invention provides a triboelectric-electromagnetic composite self-powered sensing and monitoring device suitable for power transmission lines.

[0007] The present invention discloses a triboelectric-electromagnetic composite self-powered sensor monitoring device suitable for power transmission lines, which includes a magnetically suspended triboelectric-electromagnetic composite energy collector, an energy management circuit, and a sensor monitoring system; the magnetically suspended triboelectric-electromagnetic composite energy collector is connected to the sensor monitoring system via the energy management circuit;

[0008] A magnetically levitated triboelectric-electromagnetic composite energy harvester is used to convert transmission line vibrations into electrical energy;

[0009] The energy management circuit is used to maximize the extraction of electrical energy generated by electromagnetic and triboelectric generation in the magnetic levitation triboelectric-electromagnetic composite energy harvester through different front-end interfaces, store it in a supercapacitor or energy storage battery, and then control the output level to the sensor monitoring system;

[0010] The sensor monitoring system is used to complete the collection, data storage, abnormal wake-up and data transmission of temperature and vibration information of the transmission line, and realize remote health monitoring of the transmission line.

[0011] Furthermore, the magnetic levitation triboelectric-electromagnetic composite energy harvester includes an inner shell, an outer shell, a triboelectric power generation unit, a coil, a magnet, a lower base plate, and an upper cover plate; the triboelectric power generation unit includes a stator fixed inside the outer shell and a mover fixed inside the inner shell and sliding relative to the stator; a friction layer of the grid-shaped independent layer triboelectric nanogenerator serves as the stator, and the friction layer sliding on the stator serves as the mover;

[0012] Sliding friction occurs between the mover and the stator; the inner shell is located above the lower base plate, and a magnet is fixed to the bottom of the inner shell. The magnet repels the magnet fixed on the lower base plate. The magnetic levitation force is adjusted by adjusting the number and arrangement of the magnets, thereby adjusting the resonant frequency and working state of the device; NdFeB magnets are fixed on both sides of the bottom of the inner shell; the magnets are arranged in an array to provide maximum magnetic field strength; the stator's interdigitated electrodes serve as the final output end of the friction power generation unit.

[0013] Furthermore, when vibration occurs, the inner shell and the outer shell slide relative to each other, and the inner shell drives the mover and the magnet to move up and down, and slides relative to the stator fixed to the inner and outer shells. At this time, periodic voltage and current outputs are generated on the electrodes. The periodic voltage and current are used to characterize the distance moved by the inner shell, and the coil generates alternating current to realize electromagnetic power generation. Therefore, during the entire vibration process, the friction-electromagnetic composite energy harvester will output periodic alternating current.

[0014] Furthermore, the stator is provided with interdigital electrodes, the surface of which is covered with a friction functional layer with triboelectric negative property; the mover is provided with a grid-shaped electrode; the stator and the mover are in contact and friction, resulting in contact charging, the surface of the friction functional layer obtains electrons and becomes negatively charged, and the grid-shaped electrode becomes positively charged.

[0015] Furthermore, for the friction power generation method: the front-end interface is designed as an energy transfer circuit, which includes a rectifier bridge, a capacitor C Temp , a switching circuit and an LC type power management circuit, the LC type power management circuit includes an inductor and a capacitor C connected in series Store ;The switching circuit is a discrete semiconductor switch composed of a silicon-controlled rectifier and a Zener diode;

[0016] The rectifier bridge is connected to both ends of the magnetic suspension triboelectric-electromagnetic composite energy harvester, and the capacitor C Temp The two ends of the rectifier bridge are connected between the positive and negative poles, and one end is grounded; the switch circuit is connected to the capacitor C Temp Connected in parallel with the LC type power management circuit;

[0017] Capacitor C Temp As the direct load of the magnetic levitation triboelectric-electromagnetic composite energy harvester, it first temporarily stores the energy extracted from the magnetic levitation triboelectric-electromagnetic composite energy harvester. When the voltage reaches the set threshold, the switch circuit opens and releases the energy to the capacitor C at the subsequent stage. Store , the energy maximization extraction and transfer of the magnetically levitated triboelectric-electromagnetic composite energy harvester is completed through two-stage energy storage.

[0018] Furthermore, for the electromagnetic power generation mode, the front-end interface is designed as a voltage doubler rectifier circuit, which includes a capacitor C1, a diode D1, a diode D2 and a capacitor C Store The positive electrode of capacitor C1 is grounded and connected to the positive electrode of the voltage source in the magnetic levitation triboelectric-electromagnetic composite energy harvester. The other end is connected to the negative electrode of the voltage source through capacitor C1. The positive electrode of diode D2 is connected to the negative electrode of diode D1. The negative electrode of diode D2 is connected to the negative electrode of diode D1 through capacitor C1. Store Connect to the anode of diode D1;

[0019] When the voltage source is in the negative half cycle, diode D1 is turned on and D2 is turned off. The current passes through diode D1 to charge capacitor C1 until the voltage on capacitor C1 is close to the peak value of the voltage source and remains unchanged. When the voltage source is in the positive half cycle, diode D1 is turned off and diode D2 is turned on. Capacitor C1 is added in series with the voltage source and charges capacitor C1 together. Store Charge until the capacitor C Store The voltage on the output is multiple times the voltage of the voltage source, completing the voltage doubling output.

[0020] Furthermore, the energy transfer circuit and voltage doubler rectifier circuit corresponding to the front-stage interface are respectively connected to the energy management circuit through diodes to ensure that their energy flows unidirectionally to the energy management circuit; the energy management circuit is a voltage conversion chip.

[0021] Furthermore, the sensor monitoring system includes a plurality of sensor monitoring nodes, each of which includes a temperature sensor, a signal processing circuit, a microprocessor, a memory and a communication module, and the microprocessor is connected to the temperature sensor, the signal processing circuit, the memory and the communication module respectively;

[0022] The temperature sensor is used to collect temperature information of the surface of the transmission line and send it to the microprocessor; the signal processing circuit is used to collect the vibration signal of the transmission line and convert it into a digital signal, and send the digital signal to the microprocessor;

[0023] The microprocessor stores the received information in the memory and sends the data through the communication module after reaching the set threshold; the microprocessor uses its internal storage area as the memory.

[0024] Furthermore, the sensor monitoring node operates in a periodic sleep and wake-up state. In the wake-up state, it works normally and continuously collects temperature and vibration information of the transmission line. After working for a period of time and storing relevant parameters, it enters sleep mode, and at the same time turns off the power supply of all sensors and peripheral circuits, and sets the pins of the microprocessor to analog input state. The pin power consumption is lowest in the analog input state; when the set time is reached, the microprocessor is awakened and re-enters the wake-up state. The relevant parameters include temperature and vibration information.

[0025] Furthermore, the sensor monitoring system also includes a relay node and a cloud platform; the relay node serves as a transfer station for data reception and forwarding, which receives data sent by the sensor monitoring node and packages the data and sends it to the cloud platform.

[0026] Due to the adoption of the above technical solution, the present invention has the following advantages:

[0027] 1. Composite energy harvesting:

[0028] The vibration frequency was set to 30Hz and the amplitude to 3mm on a vibration table. The entire power generation structure of the energy harvester was connected to the energy management circuit, and a 20mF capacitor was connected to the circuit's output charging terminal for energy storage. Tests showed that the TENG charged a 470nF capacitor to 25V in 20s, accumulating approximately 146.875μJ of energy with an average input power of 7.34375μW. The EMG charged a 220μF capacitor to 2.9V in 20s, accumulating approximately 925.1μJ of energy with an average input power of 46.255μW. The total average input power of the energy management circuit during operation was 53.59875μW. This high energy harvesting efficiency stems from the design of the hybrid electromagnetic-triboelectric energy harvester, which achieves the high efficiency and miniaturization requirements of the environmental energy harvester.

[0029] 2. Energy transfer efficiency:

[0030] The vibration frequency was set to 30Hz and the amplitude to 3mm on a vibration table. The entire power generation structure of the energy harvester was connected to the energy management circuit, and a 20mF capacitor was connected to the circuit's output charging terminal for energy storage. Testing showed that the energy harvesting management circuit had a maximum energy transfer efficiency of 61%. Compared with several different types of energy harvesting management circuits currently available, this energy harvesting management circuit, composed of discrete components, has a higher transfer efficiency. This advantage stems from the design of the front-end interface, energy storage, and output control circuits. The TENG front-end interface includes two-stage capacitor energy storage technology, full-bridge rectification, discrete semiconductor switches consisting of a thyristor rectifier and a Zener diode; the electromagnetic power generation includes the design of a voltage-doubling rectifier circuit.

[0031] 3. Low system power consumption:

[0032] During the test, the data was tested every 15 minutes, and 10 sets of data were stored before uploading. The energy consumption of the sensor node after working for 8121s was 227.7mJ, and the average power consumption was 28μW, achieving low-power sensor monitoring. This advantage comes from the selection and optimization of the hardware mentioned above, and the design of the software. This includes the optimized design of the switching circuit to control the on-off of peripheral devices such as sensors, and the designed sensor monitoring node to work in a periodic sleep and wake-up state. In the wake-up state, it works normally and continuously collects temperature and vibration information. After working for a period of time and storing relevant parameters, it enters sleep mode, turns off the power supply of all sensors and peripheral circuits, and sets the controller pins to analog input state (the pin power consumption is the lowest in this state).

[0033] 4. To address the harmful effects of low-frequency breeze vibrations on transmission lines, a novel magnetically levitated triboelectric-electromagnetic hybrid vibration energy harvester was designed to power sensors, enabling self-powered monitoring of low-frequency breeze vibrations on transmission lines. This energy harvester efficiently harvests low-frequency vibration energy by coupling different power generation methods. At operating frequencies below 30 Hz, it can output approximately 1.62 mW of peak power, transforming the harmful low-frequency breeze vibrations of transmission lines into an energy source for the monitoring system.

[0034] 5. To address the need for health monitoring of transmission lines during field operation, a remote wireless sensor monitoring system was designed. Low-power sensor monitoring nodes were designed for transmission lines. While these nodes are powered by a composite energy harvester, hardware selection and software optimization minimize power consumption to ensure extended operation. The monitoring nodes monitor temperature and vibration information on the transmission lines and transmit this data via a wireless network to a gateway relay node. The relay node then packages the data and uploads it to a cloud server, enabling remote health monitoring of the transmission lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments described in the embodiments of the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0036] Figure 1 Schematic diagram of four working modes of TENG in an embodiment of the present invention;

[0037] Figure 2 Schematic diagram of the principle of a sliding independent layer triboelectric nanogenerator according to an embodiment of the present invention;

[0038] Figure 3 This is a schematic structural diagram of a magnetically suspended triboelectric-electromagnetic composite energy harvester according to an embodiment of the present invention;

[0039] Figure 4 A schematic diagram of the principle of composite energy harvesting according to an embodiment of the present invention;

[0040] Figure 5 A schematic diagram of an energy harvesting management circuit architecture according to an embodiment of the present invention;

[0041] Figure 6 This is the equivalent circuit diagram of the TENG full-bridge rectification energy storage according to an embodiment of the present invention;

[0042] Figure 7 This is a block diagram of energy transfer according to an embodiment of the present invention;

[0043] Figure 8 An energy transfer circuit according to an embodiment of the present invention;

[0044] Figure 9 A voltage doubler rectifier circuit diagram according to an embodiment of the present invention;

[0045] Figure 10 An energy storage circuit according to an embodiment of the present invention;

[0046] Figure 11 This is a schematic diagram of the structure of a low-power sensor monitoring node according to an embodiment of the present invention;

[0047] Figure 12 is a block diagram of a signal processing circuit according to an embodiment of the present invention;

[0048] Figure 13 Schematic diagram of a switch circuit according to an embodiment of the present invention;

[0049] Figure 14 This is a working diagram of a sensor monitoring node according to an embodiment of the present invention; DETAILED DESCRIPTION

[0050] The present invention will be further described with reference to the accompanying drawings and embodiments. The embodiments described are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by those skilled in the art should fall within the scope of protection of the embodiments of the present invention.

[0051] See also Figure 1 The present invention provides an embodiment of a triboelectric-electromagnetic composite self-powered sensing and monitoring device suitable for power transmission lines, which comprises:

[0052] Magnetic levitation triboelectric-electromagnetic composite energy harvester, energy management circuit, sensor monitoring system; the magnetic levitation triboelectric-electromagnetic composite energy harvester is connected to the sensor monitoring system through the energy management circuit;

[0053] A magnetically levitated triboelectric-electromagnetic composite energy harvester is used to convert transmission line vibrations into electrical energy;

[0054] The energy management circuit is used to maximize the extraction of electrical energy generated by electromagnetic and triboelectric generation in the magnetic levitation triboelectric-electromagnetic composite energy harvester through different front-end interfaces, store it in a supercapacitor or energy storage battery (which can be a lithium battery), and then output the level control to the sensor monitoring system;

[0055] The sensor monitoring system is used to complete the collection, data storage, abnormal wake-up and data transmission of temperature and vibration information of the transmission line, and realize remote health monitoring of the transmission line.

[0056] In one embodiment, a magnetically suspended triboelectric-electromagnetic composite energy harvester includes an inner shell, an outer shell, a triboelectric power generation unit, a coil, a magnet, a lower base plate, and an upper cover plate; the triboelectric power generation unit includes a stator fixed inside the outer shell and a mover fixed inside the inner shell and sliding relative to the stator; a friction layer of the grid-shaped independent layer triboelectric nanogenerator serves as the stator, and the friction layer sliding on the stator serves as the mover;

[0057] Sliding friction occurs between the mover and the stator; the inner shell is located above the lower base plate, and a magnet is fixed to the bottom of the inner shell. The magnet repels the magnet fixed on the lower base plate. The magnetic levitation force is adjusted by adjusting the number and arrangement of the magnets, thereby adjusting the resonant frequency and working state of the device; NdFeB magnets are fixed on both sides of the bottom of the inner shell; the magnets are arranged in an array to provide maximum magnetic field strength; the stator's interdigitated electrodes serve as the final output end of the friction power generation unit.

[0058] In one embodiment, when vibration occurs, the inner shell and the outer shell slide relative to each other, and the inner shell drives the mover and the magnet to move up and down, and slides relative to the stator fixed to the inner and outer shells. At this time, periodic voltage and current outputs are generated on the electrodes. The periodic voltage and current are used to characterize the distance moved by the inner shell, and the coil generates alternating current to realize electromagnetic power generation. Therefore, during the entire vibration process, the friction-electromagnetic composite energy harvester will output periodic alternating current.

[0059] In one embodiment, the stator is provided with interdigital electrodes, the surface of which is covered with a friction functional layer with triboelectric negative property; the mover is provided with a grid-shaped electrode; the stator and the mover are in contact and friction, resulting in contact charging, the surface of the friction functional layer obtains electrons and becomes negatively charged, and the grid-shaped electrode becomes positively charged.

[0060] In one embodiment, for the friction power generation method: the front-end interface is designed as an energy transfer circuit, which includes a rectifier bridge, a capacitor C Temp , a switching circuit and an LC type power management circuit, the LC type power management circuit includes an inductor and a capacitor C connected in series Store ;The switching circuit is a discrete semiconductor switch composed of a silicon-controlled rectifier and a Zener diode;

[0061] The rectifier bridge is connected to both ends of the magnetic suspension triboelectric-electromagnetic composite energy harvester, and the capacitor C Temp The two ends of the rectifier bridge are connected between the positive and negative poles, and one end is grounded; the switch circuit is connected to the capacitor C Temp Connected in parallel with the LC type power management circuit;

[0062] Capacitor C Temp As the direct load of the magnetic levitation triboelectric-electromagnetic composite energy harvester, it first temporarily stores the energy extracted from the magnetic levitation triboelectric-electromagnetic composite energy harvester. When the voltage reaches the set threshold, the switch circuit opens and releases the energy to the capacitor C at the subsequent stage. Store , the energy maximization extraction and transfer of the magnetically levitated triboelectric-electromagnetic composite energy harvester is completed through two-stage energy storage.

[0063] In one embodiment, for electromagnetic power generation, the front-end interface is designed as a voltage doubler rectifier circuit, which includes a capacitor C1, a diode D1, a diode D2 and a capacitor C Store The positive electrode of capacitor C1 is grounded and connected to the positive electrode of the voltage source in the magnetic levitation triboelectric-electromagnetic composite energy harvester. The other end is connected to the negative electrode of the voltage source through capacitor C1. The positive electrode of diode D2 is connected to the negative electrode of diode D1. The negative electrode of diode D2 is connected to the negative electrode of diode D1 through capacitor C1. Store Connect to the anode of diode D1;

[0064] When the voltage source is in the negative half cycle, diode D1 is turned on and D2 is turned off. The current passes through diode D1 to charge capacitor C1 until the voltage on capacitor C1 is close to the peak value of the voltage source and remains unchanged. When the voltage source is in the positive half cycle, diode D1 is turned off and diode D2 is turned on. Capacitor C1 is added in series with the voltage source and charges capacitor C1 together. Store Charge until the capacitor C Store The voltage on the output is multiple times the voltage of the voltage source, completing the voltage doubling output.

[0065] In one embodiment, the energy transfer circuit and voltage doubler rectifier circuit corresponding to the front-stage interface are respectively connected to the energy management circuit through diodes to ensure that their energy flows unidirectionally to the energy management circuit; the energy management circuit is a voltage conversion chip.

[0066] In one embodiment, the sensor monitoring system includes a plurality of sensor monitoring nodes, each of which includes a temperature sensor, a signal processing circuit, a microprocessor, a memory, and a communication module, wherein the microprocessor is connected to the temperature sensor, the signal processing circuit, the memory, and the communication module respectively;

[0067] The temperature sensor is used to collect temperature information of the surface of the transmission line and send it to the microprocessor; the signal processing circuit is used to collect the vibration signal of the transmission line and convert it into a digital signal, and send the digital signal to the microprocessor;

[0068] The microprocessor stores the received information in the memory and sends the data through the communication module after reaching the set threshold; the microprocessor uses its internal storage area as the memory.

[0069] In one embodiment, the sensor monitoring node operates in a periodic sleep and wake-up state. In the wake-up state, it works normally and continuously collects temperature and vibration information of the transmission line. After working for a period of time and storing relevant parameters, it enters sleep mode, and at the same time turns off the power supply of all sensors and peripheral circuits, sets the pins of the microprocessor to analog input state, and the pin power consumption is lowest in the analog input state; when the set time is reached, the microprocessor is awakened and re-enters the awake state, and the relevant parameters include temperature and vibration information.

[0070] In one embodiment, the sensor monitoring system further includes a relay node and a cloud platform; the relay node serves as a transfer station for data reception and forwarding, which receives data sent by the sensor monitoring node and packages the data and sends it to the cloud platform.

[0071] In one embodiment, it includes a triboelectric energy harvesting mechanism:

[0072] The principle of TENG is based on the coupling of triboelectric charging and electrostatic induction. When two materials with different triboelectric properties come into contact with each other, due to their different ability to gain and lose electrons, the two materials carry different charges. When relative motion occurs, the static charges are separated and retained on the surface of the materials. At the same time, under the electrostatic induction effect, a corresponding induced potential difference is generated between the upper and lower electrodes. If the electrodes are connected to a load or short-circuited, electrons flow between the high and low potential differences to form a current. The reciprocating motion will form an alternating current, thus converting mechanical energy into electrical energy. According to the direction of polarity change and electrode arrangement, see Figure 1 , TENG has four basic working modes: vertical contact-separation, horizontal sliding, single electrode, and independent layer, respectively. Figure 1 As shown in (a), (b), (c) and (d).

[0073] The independent layer mode works by changing the coverage area with the two electrodes. Like the single-electrode mode, it has a freely movable friction layer. When its position changes, it affects the potential difference between the two electrodes, thereby generating an electrical output. In the independent layer mode, after the friction layer is charged, the charge can be retained on the friction material, so the two friction layers no longer need to be in direct contact during subsequent operation. Therefore, to ensure the durability of the designed energy harvester, this device adopts a device design based on the independent layer mode. In the independent layer mode, two unconnected electrodes are generally formed on the back side of the dielectric film. When a charged object moves relative to the surface of the film, the induced potential on the electrodes changes, driving electrons to flow between the external load to form an alternating current. The independent layer mode has two typical configurations: contact and sliding. Considering the need for miniaturization and the convenience of realizing the sensing function, this device decided to use a sliding structure.

[0074] The principle of sliding-mode freestanding triboelectric-layer-based nanogenerator (SF-TENG) is as follows Figure 2 As shown, (a) and (b) are the theoretical model of SF-TENG and the equivalent circuit model of SF-TENG, respectively. Metal 1 and metal 2 are placed in the same plane with a gap g to form two electrodes. The friction layer with the same size as the metal is located above the metal layer at a distance h. Their length and width are l and w. When the friction layer slides and rubs on the electrode, the distance from the friction layer boundary to the electrode layer boundary is defined as x(t). Under the triboelectric effect, the friction layer is negatively charged and evenly distributed on the surface with a charge density of -σ. At the same time, an equal amount of positive charge is induced on the electrode. The movement of the friction layer will cause the charge on the corresponding electrode to be redistributed, thereby generating electron flow. Its equivalent circuit model is as follows Figure 2As shown in Figure (b), the node concept is used to analyze it. Assuming that only a portion of the region dk on the bottom dielectric surface of the independent layer contains a triboelectric charge with a density of σ, and that the distance from this region to the left boundary of the friction layer is k, then according to the charge conservation principle, the total amount of charge induced at the corresponding nodes 1 and 2 is σwdk, which can be expressed as follows:

[0075] dQ1+dQ2=σwdk

[0076] Where dQ1 is the total charge on node 1, and dQ2 is the total charge on node 2. In the short-circuit condition, the potentials of nodes 1 and 2 are equal, so:

[0077]

[0078] Where C i (k) represents the capacitance between the small surface σwdk and the metal i. Combining the two equations, we can get:

[0079]

[0080] The total charge on metals 1 and 2 is the integration of the small friction charges on each area, which gives:

[0081]

[0082] Therefore, the short-circuit transfer charge Q SC It can be expressed as:

[0083]

[0084] When x=0, the friction layer is closer to metal 1, so the ratio of capacitance Close to zero. From the above equation, we can see that the charge Q1 on the metal approaches σwl, while Q2 approaches 0. Conversely, when x = g + l, the friction layer is closer to metal 2, and the capacitance ratio approaches infinity. At this point, the charge Q1 approaches 0, while Q2 approaches σwl. As the sliding distance x changes, the capacitance ratio changes, causing charge transfer between the electrodes and generating an alternating current.

[0085] The electromagnetic energy harvesting mechanism is:

[0086] Electromagnetic generators are generally divided into three categories: resonant, rotary, and hybrid. According to Faraday's law of electromagnetic induction, when the magnetic flux through a closed coil changes, an induced current is generated in the coil. The induced electromotive force V of the closed coil is given by the following formula:

[0087]

[0088] Where, is the magnetic flux passing through a single-turn closed coil loop, and N represents the number of turns of the closed coil in the magnetic field. The magnetic flux is obtained from the magnetic induction intensity:

[0089]

[0090] Where B is the magnetic induction intensity passing through the coil loop, and S is the area facing the magnetic field. When the area of ​​the closed coil remains unchanged and the relative motion displacement distance between the coil and the magnetic field is y(t), the induced electromotive force can be expressed as:

[0091]

[0092] In the formula is the angle between the magnetic induction intensity B and the closed coil. When it remains unchanged, remember:

[0093]

[0094] Then we have:

[0095]

[0096] but is called the gradient of the magnetic flux ψ along the direction of motion, is the gradient of the magnetic induction intensity along the direction of motion. According to the above formula, the induced electromotive force output by the closed coil is proportional to the flux gradient. By designing the magnetic field distribution to increase the flux gradient, a larger induced electromotive force output can be obtained.

[0097] In one embodiment, the architectural design of the composite energy harvester includes structural design and principle analysis of the composite energy harvester.

[0098] Structural design of composite energy harvester:

[0099] Because mechanical vibrations on transmission lines are often irregular, their amplitude and frequency are affected by wind speed. However, SF-TENG devices require sliding the length of one electrode to ensure effective electrical output during operation, making them unsuitable for energy harvesting applications in transmission lines. Therefore, a grating-structured device, the Grating-structured Freestanding Triboelectric Nanogenerator (GF-TENG), based on the SF-TENG, is developed to achieve vibration energy harvesting and signal sensing. The grating structure significantly increases charge and current density. In response to the characteristics of breeze vibrations on transmission lines, the designed energy harvester primarily collects vibration energy in the vertical direction while also sensing vibration signals. A magnetic levitation design is used to implement the device's support structure, resulting in a wide response frequency range and high sensitivity. Furthermore, an electromagnetic power generation unit is added to the magnetic levitation structure to further enhance the electrical output.

[0100] The structure of the designed magnetic levitation triboelectric-electromagnetic composite energy harvester is as follows Figure 3 As shown in the figure, (a) is the 3D structure of the magnetic levitation triboelectric-electromagnetic composite energy harvester, (b) is the exploded view of the magnetic levitation triboelectric-electromagnetic composite energy harvester, and (c), (d), and (e) are all electrode structure diagrams. By fixing one friction layer of the GF-TENG as the stator (Stator), and sliding one friction layer on the stator as the mover (Mover) as the basic unit of vibration energy collection, a multiple device stacking design is used to increase the electrical output, using magnetic levitation as the support structure, and coupling triboelectricity and electromagnetics to form this device structure.

[0101] The energy collector is divided into two shells, the inner and outer shells, which respectively fix the stator array and the mover array of the triboelectric power generation unit in the energy collector. The mover acts as a vibration sensitive element to obtain vibration from the vertical direction. Figure 3 (b), in addition to fixing the friction layer array as the stator in the device shell, a coil is placed in the shell interlayer for electromagnetic induction power generation. Another friction layer array is fixed in the inner shell as a mover, which generates sliding friction with the stator in the outer shell. At the same time, a magnet is fixed to the bottom of the inner shell, and the magnet repels the magnet fixed on the lower bottom plate. The magnetic levitation force can be adjusted by adjusting the number and arrangement of the magnets on the two plates to further adjust the resonant frequency and working state of the device. At the same time, neodymium iron boron magnets (NdFeB) with the strongest magnetic energy product are fixed on both sides of the bottom of the inner shell, and the magnets are arranged in a Halbach Array array to provide the maximum magnetic field strength. The two friction layer electrodes of the friction power generation unit are as follows: Figure 3 (c) Figure 3 (d) and Figure 3As shown in Figure (e), the mover, fixed to the inner shell, is designed with equally spaced grid-like electrode strips, forming one of the friction layer electrodes of the GF-TENG. The stator, fixed to the outer shell, adopts a similar structure, but with interdigitated electrodes with matching spacing. The electrodes on the mover serve as a tribopositive functional layer, while the stator is covered with a tribonegative functional layer, forming the GF-TENG unit. The two interdigitated electrodes on the stator serve as the final output of the GF-TENG.

[0102] The designed composite energy harvester operates as follows: when vibration occurs, the inner and outer shells slide relative to each other, causing the inner shell to move the friction layer and magnets up and down. The friction layer, fixed to the inner and outer shells, slides relative to each other, generating periodic voltage and current outputs on the electrodes. This output signal can also be used to characterize the distance the inner shell has moved. Analysis of this output signal enables vibration signal sensing, while the coil located in the outer shell interlayer also generates an alternating current to achieve electromagnetic power generation. Therefore, throughout the entire vibration process, the tribo-electromagnetic composite energy harvester will output a periodic alternating current.

[0103] Principle analysis:

[0104] The schematic diagram of composite energy harvesting is as follows Figure 4 As shown, Figure 4 (a) shows the working process of the device. In the initial state (such as Figure 4 (a) ), the electromagnetic repulsion and gravity acting on the inner shell are balanced, and the inner shell remains suspended and stationary and is at the center of the entire range of motion. When vibration occurs, the inner shell, as a vibration-sensitive unit, also vibrates, and the inner shell slides upward, driving the friction layer to rub and the magnet to cut the magnetic flux lines (such as Figure 4 (a) <ii>), and then falls to the center under the action of gravity (such as Figure 4 (a) <iii>), and continue to fall to near the bottom range (such as Figure 4 (a) <iv>), the process is repeated continuously during the vibration process, and the entire movement process is synchronized with the external vibration until the inner shell returns to the center range after the vibration stops (such as Figure 4 (a) <ⅰ>) Remain stable.

[0105] During the operation of the energy harvester, the working mechanism of the triboelectric nanogenerator with a grid structure is as follows: Figure 4 (b) shown. Figure 4 (b) shows a periodic current change of triboelectric generation during the upward sliding of the inner shell. There are interdigitated electrodes on the stator and a friction functional layer with triboelectric negative properties is covered on its surface. There are grid-shaped electrodes on the mover. The two are in contact and friction. Since the friction functional layer is more triboelectrically negative than the electrode material Cu, contact charging occurs between the two surfaces. The surface of the friction functional layer will gain electrons and be negatively charged, and the gate will be positively charged. And according to the charge transfer law, since the area of ​​the friction functional layer is more than twice that of Cu, the charge density on Cu will also be more than twice that of the friction functional layer. In the initial state, the gate completely overlaps with the electrode A of the interdigitated electrode (such as Figure 4 (b) ), electrodes A and B carry the same amount of induced charge, but their polarities are opposite. When the gate slides upward, due to electrostatic induction, free electrons flow from electrode A to B through the external circuit (such as Figure 4 (b) <ii>Then, as the gate slides further toward electrode B, electrons will continue to flow from electrode A to B. When the gate completely overlaps electrode B, the charge distribution will be opposite to the initial state (e.g. Figure 4 (b) <iii>). The gate continues to slide upward, and the free electrons will flow from electrode B to A through the external circuit (such as Figure 4 (b) <iv>), continuing to slide will return to the initial state. Therefore, after sliding a pair of electrodes upward, an alternating current is generated in the circuit. Similarly, the opposite process occurs when the gate slides downward. In addition to collecting energy through friction electricity, the distance the gate slides upward can also be analyzed by analyzing the output alternating current, which is also the principle of using it as a sensing function. For electromagnetic power generation structures, such as Figure 4 The magnet shown in (a) vibrates up and down along with the inner shell. The magnets distributed in a Halbach array generate a magnetic field. As they slide up and down, the magnetic flux passing through the coil changes, generating an induced electromotive force in the coil.

[0106] In one embodiment, the energy management circuit comprises:

[0107] The composite energy harvester can convert the vibration of the transmission line into electrical energy. However, the breeze vibration of the transmission line has the problem of lack of continuity and stability. The energy output of the energy harvester will also be discontinuous and unstable. In addition, the triboelectric power generation part of the composite energy harvester has the characteristics of high output impedance, high voltage and low current, so it needs power management. The designed energy harvesting management circuit solution architecture is as follows: Figure 5 The energy management circuit first maximizes the energy obtained from the two methods through different front-end interfaces, stores it in supercapacitors or energy storage batteries, and then controls the output level to output to the sensor monitoring system.

[0108] Front-end interface design: The function of the front-end interface is to maximize the extraction of energy. According to the output characteristics of different power generation methods, the output impedance of friction power generation is very high, about the MΩ level, the output voltage is high and the current is low; the output impedance of electromagnetic power generation is low, about the kΩ level, the output voltage is low and the current is high. Therefore, different front-end circuits are required for processing. In order to store the output of TENG, TENG needs an external capacitive load. When TENG is directly connected to a capacitive load, since TENG outputs alternating current, if the charge on the load capacitor is not transferred or consumed in time, the energy will be transmitted back in the opposite direction after the voltage on the capacitor reaches its peak. Therefore, generally speaking, a rectifier circuit is generally added after the output of the TENG device to force energy to flow from TENG to the capacitive load in one direction. In order to maximize the energy extraction from TENG, the capacitive load should be a value comparable to the source capacitance to achieve impedance matching. For example Figure 6 The full-bridge rectifier circuit is used to rectify the TENG output and charge it to a small capacitor C. L .

[0109] For full-bridge rectification, with the load capacitance C L As the voltage on the load capacitor increases, the conduction angle of the diode in the rectifier bridge will decrease, causing the efficiency to gradually decrease. In addition, the saturation voltage of the load capacitor is lower than the absolute maximum output voltage of the TENG. Therefore, the energy on the load capacitor needs to be transferred away in time. L The voltage value on the capacitor should not be too low, and the power transfer should be performed at an appropriate threshold. In order to maximize the energy extraction of TENG, the threshold voltage is designed to be 80% of the peak open circuit voltage of TENG. By transferring the energy on the capacitor in time through the two-stage capacitor energy storage technology, the energy conversion efficiency of the energy management circuit can be significantly increased. The energy transfer block diagram is shown in the figure. Figure 7 .

[0110] Capacitor C Temp As the direct load of TENG, it temporarily stores the energy extracted from TENG. When the voltage reaches the set threshold, the switch opens and releases the energy to the subsequent capacitor C. Store , through two-stage energy storage, the maximum extraction and transfer of TENG energy is completed. In the circuit, the switch has a significant impact on energy transfer. The switches used can be divided into travel switches, voltage-triggered switches, discrete transistor switches, and integrated circuit switches. Considering that the output open-circuit voltage of the designed device is not high, a discrete semiconductor switch composed of a thyristor rectifier and a Zener diode is used. The thyristor rectifier and Zener diode are used instead of the switch, the front stage is connected to the full-wave rectifier circuit, and the LC type power management circuit is connected afterwards. The circuit is designed as follows Figure 8 shown.

[0111] For electromagnetic power generation, its output impedance is low, which is convenient for energy extraction, but its output voltage is also low. If a full-wave rectifier circuit is used to rectify the power and then connect it to a capacitor for energy extraction, as in the friction power generation method, the voltage on the charging capacitor increases, and the conduction angle of the diode in the rectifier bridge decreases, and the charging efficiency gradually decreases. Due to the voltage drop of the rectifier bridge and the low output voltage of electromagnetic power generation, the saturation voltage on the capacitor is also low. Too low a voltage will be detrimental to subsequent energy storage. Therefore, see Figure 9 , for the electromagnetic power generation method, a voltage doubler rectifier circuit is used to process it. Its working principle is as follows: when the voltage source outputs a negative half cycle (negative on top and positive on bottom), the diode D1 is turned on and D2 is turned off. The current passes through D1 to charge the capacitor C1, gradually charging the voltage on the capacitor C1 to a value close to the peak value of the voltage source and keeping it constant; when the voltage source outputs a positive half cycle (positive on top and negative on bottom), the diode D1 is turned off and D2 is turned on. The capacitor C1 is added in series with the voltage source and together charges the capacitor C Store Charge, gradually increase the capacitor C Store The voltage on the capacitor is charged to nearly 2 times the voltage of the voltage source, completing the voltage doubling output.

[0112] Energy Storage:

[0113] The above circuit extracts energy from the energy harvester and stores it in a capacitor. When the energy harvester is supplied with sufficient energy, a DC power supply can be output from the capacitor. However, in actual applications, the energy input is unstable and discontinuous, while the back-end sensor monitoring system requires a suitable and stable operating voltage. Therefore, the capacitor can only be used for temporary energy storage. To obtain a long-term stable power supply, a rechargeable battery is used for energy storage.

[0114] A high-energy-density rechargeable lithium battery LIR2032 is used as energy storage. The full-charge voltage of a single lithium battery is usually 4.2V, and the discharge termination voltage is about 3V. Its capacity is 35mAh, and the discharge capacity can reach 1C, which means that the entire capacity of the battery can be discharged in 1 hour. The output current can reach up to 35mA. In order to adapt to the unstable output of the energy collector, the buck-boost converter chip TPS63900 is selected to implement the voltage conversion function. The chip has an extremely low quiescent current of 75nA and is suitable for low-power application scenarios. The input voltage range of the chip is 1.8V to 5.5V, and the wide power supply voltage can ensure that voltage conversion can be performed under different energy input conditions. The chip also has a programmable input current limit, which can determine the charging current according to different situations. Figure 10 This is a schematic diagram of an energy storage circuit. The energy input from the energy harvester is rectified and stored in a capacitor before being output to a battery or application system via a voltage conversion chip. A diode is added between the two circuit stages to ensure unidirectional current flow.

[0115] By integrating the various components of the energy harvesting circuit designed above, an energy harvesting management circuit suitable for low-power sensor monitoring systems was developed. Both power generation methods, after processing through the front-end interface, first charge the capacitor. Once the capacitor voltage reaches a certain threshold, the charging circuit then charges the energy storage battery, completing energy storage. Diodes are connected between each power generation method and the charging management circuit to ensure unidirectional energy flow.

[0116] In one embodiment, the sensor node (low power consumption) mainly completes the functions of temperature and vibration information collection, data storage, abnormal wake-up and data transmission. Its structure is as follows Figure 11 shown.

[0117] Temperature information is collected via a temperature sensor, while vibration signals are collected via a prepared energy harvester. Since the input vibration signal is an analog AC signal, it requires signal processing before being converted into a digital signal through AD acquisition. Due to the high power consumption of wireless transmission, the microprocessor stores the collected data in a memory chip after processing. Once the data reaches a set threshold, it is transmitted via LoRa communication.

[0118] As the core of the sensor monitoring node, the STMicroelectronics STM32L151, a 32-bit, low-power processing chip, serves as the control hub. The temperature sensor primarily measures the surface temperature of the transmission line. The DS18B20 thermocouple temperature sensor, featuring 9-12-bit accuracy and a maximum operating current of only 1.5 mA, communicates with the microprocessor via a 1-ware single-wire bus. Stainless steel packaging is also available for use in various field environments. Memory is used to store collected data. Since the SRAM storing data loses power when the microprocessor enters sleep mode, an EEPROM or external flash memory is required to store the data. However, using an additional chip increases power consumption. Consider using the processor's internal flash memory as data storage.

[0119] Among various wireless communication methods, GSM and GPRS, which directly access the Internet, have too high transmission and reception power. Bluetooth and Zigbee, based on the 2.4GHz frequency band, have insufficient communication distance to meet application requirements. Therefore, LoRa technology was selected. It operates in the optional 433MHz, 868MHz, and 915MHz frequency bands and is primarily characterized by long-distance transmission. The 433MHz E22400T22S module was selected as the wireless transmission module. It supports sleep mode, has low power consumption, and offers a long transmission distance. Because wireless transmission attenuation between the monitoring node and the relay node is minimal in open field environments, it can be approximated as free-space propagation. According to the Friis formula in the free-space propagation model:

[0120]

[0121] Where Pr is the received power of the signal, P t is the transmission power, G t is the transmission gain, G r is the receiving gain, L is the system loss coefficient that is independent of the propagation environment, and d is the distance between the monitoring node and the relay node. The path loss during propagation is the ratio of the transmitted signal to the received signal:

[0122]

[0123] If the propagation distance d is known, the transmit power can be calculated by substituting parameters such as receive gain and system loss into the formula. The transmit power setting can be completed by setting the relevant registers of the E22400T22S module, minimizing power consumption while achieving the desired transmission distance.

[0124] The acquisition of vibration signals requires a separate circuit design for collection. The sensor output open-circuit voltage of the friction part of the composite energy harvester is an AC voltage within tens of volts. This AC signal cannot be directly input into the MCU for analysis and processing. Therefore, a suitable load is first selected to obtain the signal voltage division signal. After passing through the isolation circuit, the signal is then increased to a positive voltage through the addition circuit. This positive voltage can be input into the AD acquisition port of the MCU for sampling. The block diagram of the circuit is shown in the figure. Figure 12 shown.

[0125] The TENG features high output impedance and high voltage. Using a large resistor as a load allows for appropriate voltage division without significant waveform changes. To prevent subsequent circuitry from affecting the load impedance, a buffer is used as a divider. The buffer is constructed using the LM358 op amp, a dual op amp chip that supports dual power supplies ranging from ±1.5V to ±15V. Since the input signal is AC, a dual power supply is required, and the supply voltage must be greater than the input voltage range. To generate a negative voltage source, an ICL7660 power supply polarity inversion converter is used to generate a negative voltage. This dual power supply ultimately powers the buffer and adder. After the aforementioned signal processing, a voltage signal ranging from 0 to 3V is generated. The selected STM32L1 chip has an AD peripheral with 12-bit accuracy. By setting the ADC prescaler to a maximum clock of 12MHz, the sampling period can be set to 1.5 cycles, resulting in a minimum conversion time of approximately 1.17μs, enabling high-frequency sampling of sensor signals.

[0126] In order to achieve low power consumption, low-power devices are selected in the hardware design. At the same time, the sensor registers are configured to enter sleep mode during non-measurement time periods. However, there will still be current consumption in sleep mode. In order to further reduce the hardware power consumption, a switch circuit is designed to control the on-off of sensors and other peripheral devices. Figure 13 As shown in the figure, the controller pin is connected to the gate of the NMOS transistor. When the controller pin is floating, the gate of the NMOS transistor is pulled low, causing the power supply channel to be shut down. In this way, the 3.3V supply voltage cannot be transmitted to the load circuit. Only when work is required will the controller output a high level to turn on the NMOS transistor and supply power to the load.

[0127] In addition to hardware selection and optimization, power consumption can also be further reduced in software design. The designed sensor monitoring node works in a periodic sleep and wake-up state. When in the wake-up state, it works normally and continuously collects temperature and vibration information. After working for a period of time and storing relevant parameters, it enters sleep mode, turns off the power supply of all sensors and peripheral circuits, and sets the controller pins to analog input state (pin power consumption is the lowest in this state); when the set RTC timer reaches the time, the controller is awakened and executes the program from the beginning to complete new data collection and storage. The workflow of the node is as follows Figure 14 shown.

[0128] Relay nodes and cloud platforms:

[0129] Relay nodes act as a data receiving and forwarding hub, receiving data from the preceding low-power sensor monitoring nodes and packaging the data for transmission to the cloud platform. Like the sensor monitoring nodes, relay nodes also use the low-power STM32L1 series chip as the controller hub, communicating with the LoRa module and 4G module via the serial port.

[0130] The relay node runs the real-time operating system (UCOS), which divides data forwarding into three tasks. After the node boots up, it performs system initialization and checks connectivity between the LoRa module and the 4G module. Then, the first task begins: blocking the transmission of the data buffer contents. If there is no data to be sent, the task suspends. Simultaneously, the second task executes: monitoring LoRa data. Once data arrives, it stores it in the buffer. Data forwarding is accomplished through the coordination of these two tasks. Furthermore, because the relay node needs to maintain a persistent connection with the cloud server, it must send heartbeat packets in addition to data transmission. This function also serves to determine the relay node's online status. This task is the third task of the UCOS system. Using a real-time operating system ensures timely data transmission based on task priority, facilitates subsequent feature development and maintenance, and improves system stability and reliability. To ensure data accuracy, data is uploaded to Alibaba Cloud servers using the connection-based TCP protocol, which ensures data reliability. The data is then stored and visualized on the server side.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.< / iv> < / iii> < / ii> < / iv> < / iii> < / ii>

Claims

1. A triboelectric-electromagnetic composite self-powered sensing and monitoring device suitable for power transmission lines, characterized in that: It includes a magnetic levitation triboelectric-electromagnetic composite energy harvester, an energy management circuit, and a sensor monitoring system; the magnetic levitation triboelectric-electromagnetic composite energy harvester is connected to the sensor monitoring system through the energy management circuit; A magnetically levitated triboelectric-electromagnetic composite energy harvester is used to convert transmission line vibrations into electrical energy; The energy management circuit is used to maximize the extraction of electrical energy generated by electromagnetic and triboelectric generation in the magnetic levitation triboelectric-electromagnetic composite energy harvester through different front-end interfaces, store it in a supercapacitor or energy storage battery, and then control the output level to the sensor monitoring system; The sensor monitoring system is used to complete the collection, data storage, abnormal wake-up and data transmission of temperature and vibration information of the transmission line, realizing remote health monitoring of the transmission line; The magnetic levitation triboelectric-electromagnetic composite energy harvester includes an inner shell, an outer shell, a triboelectric power generation unit, a coil, a magnet, a lower base plate, and an upper cover plate. The triboelectric power generation unit includes a stator fixed inside the outer shell and a mover fixed inside the inner shell and sliding relative to the stator. One friction layer of the grid-shaped independent layer tribo-nanogenerator serves as a stator, and the friction layer sliding on the stator serves as a mover; Sliding friction occurs between the mover and the stator; the inner shell is located above the lower base plate, and a magnet is fixed to the bottom of the inner shell. The magnet repels the magnet fixed on the lower base plate. The magnetic levitation force is adjusted by adjusting the number and arrangement of the magnets, thereby adjusting the resonant frequency and working state of the device; NdFeB magnets are fixed on both sides of the bottom of the inner shell; the magnets are arranged in an array to provide maximum magnetic field strength; the stator's interdigitated electrodes serve as the final output end of the friction power generation unit.

2. The triboelectric-electromagnetic composite self-powered sensing and monitoring device for power transmission lines according to claim 1, characterized in that: When vibration occurs, the inner shell and the outer shell slide relative to each other, and the inner shell drives the mover and the magnet to move up and down, and slide relative to the stator fixed to the inner and outer shells. At this time, periodic voltage and current output are generated on the electrodes. The periodic voltage and current are used to characterize the distance moved by the inner shell. The coil generates alternating current to realize electromagnetic power generation. Therefore, during the entire vibration process, the friction-electromagnetic composite energy harvester will output periodic alternating current.

3. The triboelectric-electromagnetic composite self-powered sensing and monitoring device for power transmission lines according to claim 1 or 2, characterized in that: The stator is provided with interdigital electrodes, the surface of which is covered with a friction functional layer with triboelectric negative properties; the mover is provided with a grid-shaped electrode; the stator and the mover are in contact and friction, resulting in contact charging, the surface of the friction functional layer obtains electrons and becomes negatively charged, and the grid-shaped electrode becomes positively charged.

4. The triboelectric-electromagnetic composite self-powered sensing and monitoring device for power transmission lines according to claim 1, characterized in that: For friction power generation: the front-end interface is designed as an energy transfer circuit, which includes a rectifier bridge, capacitor C Temp , a switching circuit and an LC type power management circuit, the LC type power management circuit includes an inductor and a capacitor C connected in series Store ;The switching circuit is a discrete semiconductor switch composed of a silicon-controlled rectifier and a Zener diode; The rectifier bridge is connected to both ends of the magnetic suspension triboelectric-electromagnetic composite energy harvester, and the capacitor C Temp The two ends of the rectifier bridge are connected between the positive and negative poles, and one end is grounded; the switch circuit is connected to the capacitor C Temp Connected in parallel with the LC type power management circuit; Capacitor C Temp As the direct load of the magnetic levitation triboelectric-electromagnetic composite energy harvester, it first temporarily stores the energy extracted from the magnetic levitation triboelectric-electromagnetic composite energy harvester. When the voltage reaches the set threshold, the switch circuit opens and releases the energy to the capacitor C at the subsequent stage. Store , the energy maximization extraction and transfer of the magnetically levitated triboelectric-electromagnetic composite energy harvester is completed through two-stage energy storage.

5. The triboelectric-electromagnetic composite self-powered sensing and monitoring device for power transmission lines according to claim 1, characterized in that: For electromagnetic power generation, the front-end interface is designed as a voltage doubler rectifier circuit, which includes capacitor C1, diode D1, diode D2 and capacitor C Store The positive electrode of capacitor C1 is grounded and connected to the positive electrode of the voltage source in the magnetic levitation triboelectric-electromagnetic composite energy harvester. The other end is connected to the negative electrode of the voltage source through capacitor C1. The positive electrode of diode D2 is connected to the negative electrode of diode D1. The negative electrode of diode D2 is connected to the negative electrode of diode D1 through capacitor C1. Store Connect to the anode of diode D1; When the voltage source is in the negative half cycle, diode D1 is turned on and D2 is turned off. The current passes through diode D1 to charge capacitor C1 until the voltage on capacitor C1 is close to the peak value of the voltage source and remains unchanged. When the voltage source is in the positive half cycle, diode D1 is turned off and diode D2 is turned on. Capacitor C1 is added in series with the voltage source and charges capacitor C1 together. Store Charge until the capacitor C Store The voltage on the output is multiple times the voltage of the voltage source, completing the voltage doubling output.

6. The triboelectric-electromagnetic composite self-powered sensing and monitoring device for power transmission lines according to claim 1, characterized in that: The energy transfer circuit and voltage doubler rectifier circuit corresponding to the front-end interface are respectively connected to the energy management circuit through diodes to ensure that their energy flows unidirectionally to the energy management circuit; the energy management circuit is a voltage conversion chip.

7. The triboelectric-electromagnetic composite self-powered sensing and monitoring device for power transmission lines according to claim 1, characterized in that: The sensor monitoring system includes a plurality of sensor monitoring nodes, each of which includes a temperature sensor, a signal processing circuit, a microprocessor, a memory and a communication module, and the microprocessor is connected to the temperature sensor, the signal processing circuit, the memory and the communication module respectively; The temperature sensor is used to collect temperature information of the surface of the transmission line and send it to the microprocessor; the signal processing circuit is used to collect the vibration signal of the transmission line and convert it into a digital signal, and send the digital signal to the microprocessor; The microprocessor stores the received information in the memory and sends the data through the communication module after reaching the set threshold; the microprocessor uses its internal storage area as the memory.

8. The triboelectric-electromagnetic composite self-powered sensing and monitoring device for power transmission lines according to claim 1, characterized in that: The sensor monitoring node operates in a periodic sleep and wake-up state. In the wake-up state, it works normally and continuously collects temperature and vibration information of the transmission line. After working for a period of time and storing relevant parameters, it enters sleep mode, while turning off the power supply of all sensors and peripheral circuits, and setting the pins of the microprocessor to analog input state. The pin power consumption is lowest in the analog input state; when the set time is reached, the microprocessor is awakened and re-enters the wake-up state. The relevant parameters include temperature and vibration information.

9. The triboelectric-electromagnetic composite self-powered sensing and monitoring device for power transmission lines according to claim 1, characterized in that: The sensor monitoring system also includes relay nodes and a cloud platform; the relay node serves as a transfer station for data reception and forwarding, which receives data sent by the sensor monitoring node and packages the data and sends it to the cloud platform.

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