Multifunctional overhead cable fault protection device

Abstract

The invention provides a multifunctional overhead cable fault protection device which is characterized by comprising a fault accurate positioning module, a bird repelling module and a sensing and supplying integrated module. The fault accurate positioning module realizes short-circuit fault positioning under a short-distance aerial cable through a wavelet energy spectrum value and a Chebyshev neural network; the bird repelling module adopts variable-frequency ultrasonic waves and red and blue flashing lights to synergistically repel birds; the induction and supply integrated module comprises an energy taking module and a voltage detection module, and the energy taking module and the voltage detection module share a double-cylinder polar plate installed outside a power transmission cable, so that non-contact voltage detection is carried out while normal power supply of the device is guaranteed. According to the invention, a monitoring-protection-power supply integrated solution is provided for the aerial cable, and the operation reliability of a power grid is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of safety and protection technology, and in particular to a multifunctional overhead cable fault protection device. Background Art

[0002] In modern power transmission networks, overhead cables have become an important component of urban distribution networks and long-distance power transmission due to their advantages such as low construction cost and easy maintenance. However, their open-air operation exposes them to multiple security threats:

[0003] 1. Short-circuit Fault Hazards: Overhead cables are susceptible to short-circuit faults due to factors such as lightning strikes and overlapping tree branches. Traditional impedance methods are significantly affected by fluctuations in line parameters, while traveling wave methods, due to difficulties in identifying waveheads, can result in short-distance positioning errors of tens of meters, making them inadequate for precise repairs.

[0004] 2. Threat from bird activities: Failures caused by bird nesting, pecking at insulators, etc. account for as high as 15%-20%. Traditional bird repellent devices have poor adaptability and are prone to failure.

[0005] 3. Monitoring power supply problems: The monitoring equipment on the tower / cable is far away from the ground power supply, the battery needs to be replaced regularly, and the CT energy intake is limited by the load current, which cannot guarantee long-term stable operation.

[0006] To address the above problems, the present invention proposes a system solution that integrates short-distance fault precise positioning, intelligent bird repellent protection and self-power supply, and improves the operational reliability of overhead cables through the integration of multiple technologies. Summary of the Invention

[0007] The purpose of the present invention is to propose a multifunctional overhead cable fault protection device, which solves the problems of insufficient short-distance fault location accuracy, bird activity threats and equipment power supply problems of traditional methods through the integration of multiple technologies. The fault precision location module uses the existing binary wavelet energy spectrum transformation algorithm to extract the wavelet energy spectrum value E4, and uses the Chebyshev neural network to train a precise positioning formula; an ultrasonic frequency conversion bird-repelling module with ultrasonic waves and red and blue flashing lights is designed, which can adjust the bird-repelling frequency range to adapt to different scenarios and bird species; a hybrid energy extraction system is designed, which uses electric field energy extraction combined with magnetic coupling energy extraction to ensure continuous and stable operation of the equipment. The present invention provides an integrated monitoring-protection-power supply solution for overhead cables, significantly improving the reliability of power grid operation.

[0008] To achieve the above object, the technical solution of the present invention is: a multifunctional overhead cable fault protection device, comprising a fault accurate positioning module, a bird repelling module and a sensing and supply integrated module;

[0009] The fault accurate location module realizes short-circuit fault location under short-distance overhead cables through wavelet energy spectrum value and Chebyshev neural network;

[0010] The bird repellent module uses variable frequency ultrasonic waves and red and blue flashing lights to synergistically repel birds;

[0011] The integrated sensing and supply module includes an energy acquisition module and a voltage detection module. The energy acquisition module and the voltage detection module share a double cylindrical electrode plate installed outside the transmission cable to ensure normal power supply of the device while performing non-contact voltage detection.

[0012] Preferably, the short-circuit fault location under the short-distance overhead cable is realized by wavelet energy spectrum value and Chebyshev neural network, specifically as follows:

[0013] Collect the current waveform and extract the wavelet energy spectrum value E4 to obtain the initial fault phase angle θ c And the first peak E4 of the fault current wavelet energy spectrum waveform max1 ;

[0014] The first peak E4 of the fault current wavelet energy spectrum waveform max1 Perform natural logarithmic transformation to obtain the eigenvalue ln_E4 after logarithmic linearization max1 ;

[0015] The initial fault phase angle θ c and eigenvalue ln_E4 max1 As a variable, the distance d from the short-circuit point to the detection point is used as the objective function, and the short-circuit fault location formula is obtained through Chebyshev neural network training;

[0016] When a fault occurs and the fault type is determined to be a short circuit fault, the initial fault phase angle θ detected by the detection point is c and eigenvalue E4 max1 Substitute it into the short-circuit fault location formula and calculate the exact value of the fault location.

[0017] Preferably, the short-circuit fault location formula obtained by Chebyshev neural network training is as follows:

[0018]

[0019]

[0020] Φ=(T0(x1)·T0(x2) T0(x1)·T1(x2) … T3(x1)·T3(x2)) (3)

[0021]

[0022] In formula (1), M represents the total number of two-dimensional Chebyshev polynomial tensor product basis functions. If the highest order of Chebyshev polynomial is k=3, then M=16; φ m represents the element in the 1st row and the mth column of the basis function matrix φ; w m is the weight of the mth basis function; b is the bias;

[0023] Formula (2) is the expression of input quantity X; Formula (3) is the recursive formula of Chebyshev orthogonal polynomial basis function Φ; Formula (4) is the expression of Chebyshev polynomial; Chebyshev polynomial T i In (x), i represents the order of the polynomial, and x1 and x2 refer to the two independent variables respectively.

[0024] Preferably, the bird-repelling module includes a power supply unit, a single-chip microcomputer, an ultrasonic speaker, an infrared sensor and a red and blue dual-color LED flashing light;

[0025] The power supply unit includes a solar panel, a lithium battery, a solar charging module, and a lithium battery boost module; the solar panel, the lithium battery, and the lithium battery boost module are respectively connected to the solar charging module to convert solar energy into electrical energy and perform energy storage and boosting; the lithium battery boost module is connected to the single-chip microcomputer to provide power;

[0026] The single-chip microcomputer is connected to the ultrasonic speaker, infrared sensor and red and blue dual-color LED flashing light; the infrared sensor transmits the bird detection signal to the single-chip microcomputer, and the single-chip microcomputer drives the ultrasonic speaker through PWM to achieve frequency conversion according to the bird detection signal, and drives the red and blue dual-color LED flashing light.

[0027] Preferably, the ultrasonic frequency of the bird-repelling module is adjustable in the range of 20kHz-100kHz.

[0028] Preferably, the energy taking circuit of the energy taking module includes a rectifier bridge, an energy taking capacitor C, a capacitor C x , energy storage capacitor C g , Zener diode Z1, bidirectional trigger diode DIAC, diode D2, resistor R x , load R, switch tube Q1 and inductor L1;

[0029] The two AC input terminals of the rectifier bridge are respectively connected to the inner and outer plates of the double cylindrical plates, wherein the outer plates of the double cylindrical plates are grounded; the two DC output terminals of the rectifier bridge are connected to the two ends of the energy taking capacitor C;

[0030] The first end of the energy-taking capacitor C is connected to the first end of the inductor L1, and the second end of the energy-taking capacitor C is connected to the anode of the voltage-stabilizing diode Z1 and the resistor R x The first terminal, capacitor C xThe first terminal is the source of the switch tube Q1; the cathode of the voltage regulator diode Z1 is connected to the resistor R x The second terminal, capacitor C x The second end, the gate of the switch tube Q1, the first anode of the bidirectional trigger diode DIAC, and the second anode of the bidirectional trigger diode DIAC are connected to the drain of the switch tube Q1, the anode of the diode D2, and the energy storage capacitor C g The second end of the load R, the second end of the inductor L1 is connected to the cathode of the diode D2, the energy storage capacitor C g The first terminal and the first terminal of the load R; the energy-taking voltage output is drawn from both ends of the load R.

[0031] Preferably, the energy-taking circuit converts the displacement current i of the double cylindrical plates into d Converted into DC current I dc , and then use the self-triggering pulse to operate the Buck converter circuit to convert the voltage into a usable low-voltage output. The Buck converter circuit works as follows:

[0032] When the voltage across the energy-taking capacitor C rises to the trigger voltage V on When , the switch Q1 is turned on, transferring the energy stored in the energy-taking capacitor C to the inductor L1 of the Buck circuit;

[0033] When the voltage across the energy-harvesting capacitor C drops below the conduction threshold, the switch Q1 is turned off and the energy stored in the inductor L1 is transferred to the load. Once the energy transfer is completed, the energy-harvesting capacitor C slowly charges until it reaches the trigger voltage level again and the next pulse begins.

[0034] Preferably, the voltage detection module includes a pre-circuit, a second-order Butterworth filter circuit and a level raising circuit;

[0035] A resistor is connected between the inner and outer metal plates and the outer metal plate is grounded;

[0036] The signal input end of the preamplifier circuit is connected to the inner metal plate, and the signal output end of the preamplifier circuit is connected to the second-order Butterworth filter circuit. The second-order Butterworth filter circuit is connected to the level-lifting circuit, and the level-lifting circuit leads to the raised voltage signal u out , which is the voltage signal required to be sampled.

[0037] Preferably, the preamplifier circuit includes capacitors C1, C2, C3, resistors R1, R2, R3, R4, R5, R6, a potentiometer RW1, a first operational amplifier, and a second operational amplifier;

[0038] A first end of capacitor C1 is connected to a first end of capacitor C3, a non-inverting input terminal of the first operational amplifier, and a first end of resistor R1; a second end of resistor R1 is connected to a first end of capacitor C2 and a first end of resistor R2; a second end of resistor R2 is connected to a first end of resistor R3 and to ground; a second end of resistor R3 is connected to a second end of capacitor C2, a first end of resistor R4, and an inverting input terminal of the first operational amplifier; a second end of resistor R4 is connected to the output terminal of the first operational amplifier and the non-inverting input terminal of the second operational amplifier; the inverting input terminal of the second operational amplifier is connected to a first end of resistor R5 and a first end of resistor R6; a second end of resistor R5 is connected to a first fixed end of potentiometer RW1 and to ground; a second fixed end of potentiometer RW1 is connected to a second end of resistor R6 and the output terminal of the second operational amplifier; and a movable end of potentiometer RW1 is connected to the second end of capacitor C3;

[0039] The second terminal of capacitor C1 is connected to the signal input, and the output of the second operational amplifier is used as the voltage signal u in Connect to signal output.

[0040] Preferably, the second-order Butterworth filter circuit and level-lifting circuit include capacitors C4, C5, and C6, resistors R7-R13, and a third operational amplifier and a fourth operational amplifier;

[0041] The output end of the second operational amplifier is connected to the first end of resistor R7, the second end of resistor R7 is connected to the first end of resistor R8, the first end of resistor R9, and the first end of capacitor C4, the second end of resistor R8 is connected to the first end of resistor R10, the second end of capacitor C5, and the output end of the third operational amplifier, the first end of capacitor C5 is connected to the second end of resistor R9 and the non-inverting input end of the third operational amplifier, the inverting input end of the third operational amplifier is connected to the second end of capacitor C4 and to ground, the second end of resistor R10 is connected to the first end of resistor R11 and the non-inverting input end of the fourth operational amplifier, the second end of resistor R11 is connected to the output end of the fourth operational amplifier, the first end of capacitor C6, and the cathode of Zener diode Z2, the second end of capacitor C6 is connected to the anode of Zener diode Z2 and to ground, the inverting input end of the fourth operational amplifier is connected to the second end of resistor R12, the first end of resistor R13, the second end of resistor R13 is grounded, and the first end of resistor R12 is connected to the positive power supply;

[0042] The voltage signal u after the cathode of the voltage stabilizing diode Z2 is raised out ;

[0043] The voltage signal expression after lifting is:

[0044]

[0045] where u out is the voltage signal after lifting, u in is the voltage signal before lifting, u ref is the reference voltage.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] 1. Accurately locate short-circuit faults under short-distance overhead cables through wavelet energy spectrum values ​​and Chebyshev neural network, and further improve the accuracy by logarithmically linearizing the eigenvalues.

[0048] 2. Use ultrasonic frequency conversion and red and blue flashing lights to drive away birds, improve adaptability to different birds and scenes, and reduce line faults caused by birds.

[0049] 3. Design a non-contact integrated sensing and supply system to ensure long-term power supply to the equipment while achieving accurate measurement of cable voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a structural diagram of the multifunctional overhead cable fault protection device of the present invention;

[0051] Figure 2 This is a diagram of an overhead cable simulation model built based on MATLAB / Simulink in one embodiment of the present invention;

[0052] Figure 3 This is the hardware design diagram of the bird-repelling module of the present invention;

[0053] Figure 4 This is a schematic diagram of the energy extraction principle of the double cylindrical plates of the present invention;

[0054] Figure 5 This is the energy extraction circuit diagram of the present invention;

[0055] Figure 6 This is a schematic diagram of non-contact voltage measurement based on electric field coupling according to the present invention;

[0056] Figure 7 This is a schematic diagram of the principle of a cylindrical sensor with a grounded shielding layer according to the present invention;

[0057] Figure 8 This is the front circuit diagram of the present invention;

[0058] Figure 9 This is a diagram of a second-order Butterworth filter circuit and a level-lifting circuit according to the present invention;

[0059] Figure 10 This is the voltage sampling circuit diagram of the present invention

[0060] Figure 11 This is a block diagram of the integrated sensing principle of the present invention. DETAILED DESCRIPTION

[0061] The following is combined with Figure 1-11 , the technical solution of the present invention is described in detail.

[0062] refer to Figure 1 , the present invention proposes a multifunctional overhead cable fault protection device, including a fault accurate positioning module, a bird-repelling module and a sensing-supply integrated module;

[0063] The fault accurate location module realizes short-circuit fault location under short-distance overhead cables through wavelet energy spectrum value and Chebyshev neural network;

[0064] The bird repellent module uses variable frequency ultrasonic waves and red and blue flashing lights to synergistically repel birds;

[0065] The integrated sensing and supply module includes an energy acquisition module and a voltage detection module. The energy acquisition module and the voltage detection module share a double cylindrical electrode plate installed outside the transmission cable to ensure normal power supply of the device while performing non-contact voltage detection.

[0066] The short-circuit fault location under a short-distance overhead cable is realized by using wavelet energy spectrum value and Chebyshev neural network, as follows:

[0067] Collect the current waveform and extract the wavelet energy spectrum value E4 to obtain the initial fault phase angle θ c And the first peak E4 of the fault current wavelet energy spectrum waveform max1 ;

[0068] The first peak E4 of the fault current wavelet energy spectrum waveform max1 Perform natural logarithmic transformation to obtain the eigenvalue ln_E4 after logarithmic linearization max1 ;

[0069] The initial fault phase angle θ c and eigenvalue ln_E4 max1 As a variable, the distance d from the short-circuit point to the detection point is used as the objective function, and the short-circuit fault location formula is obtained through Chebyshev neural network training;

[0070] When a fault occurs and the fault type is determined to be a short circuit fault, the initial fault phase angle θ detected by the detection point is c and eigenvalue E4 max1 Substitute it into the short-circuit fault location formula and calculate the exact value of the fault location.

[0071] The present invention will E4 max1 After performing natural logarithmic transformation to linearize it, the neural network is trained to further improve the accuracy.

[0072] by Figure 2 Taking θ as an example, the training process of Chebyshev neural network is described as follows:

[0073] To ensure the accuracy of the model, we take θc ∈{0,15,30,45,60,75,90,105,120,135,150,165}, d∈{100,200,300,400,500,600,700,800,900,1000}, the E4 of the detection point is measured when the cable single-phase ground short circuit fault occurs. max1 , we get E4 when a single-phase ground short circuit occurs in 12×10=120 cables in total max1 The total number of sample points is 120. 100 sample points are randomly selected as the training set of the Chebyshev neural network algorithm, and the remaining 20 sample points are the test set. The following short-circuit fault location formula is obtained through Chebyshev neural network training:

[0074]

[0075]

[0076] Φ=(T0(x1)·T0(x2) T0(x1)·T1(x2) … T3(x1)·T3(x2)) (3)

[0077]

[0078] In formula (1), d is the predicted distance from the fault point to the detection point, M represents the total number of two-dimensional Chebyshev polynomial tensor product basis functions, and the highest order of Chebyshev polynomial is set to k = 3, then M = (k + 1) 2 =16;φ m represents the element in the 1st row and the mth column of the basis function matrix φ; w m is the weight of the mth basis function; b is the bias;

[0079] Formula (2) is the expression of input quantity X; Formula (3) is the recursive formula of Chebyshev orthogonal polynomial basis function Φ; Formula (4) is the expression of Chebyshev polynomial; Chebyshev polynomial T i In (x), i represents the order of the polynomial, and x1 and x2 refer to the two independent variables respectively.

[0080] To achieve effective bird repelling, the bird repellent module of the present invention utilizes two primary methods: ultrasound and red and blue strobe lights. Ultrasonic bird repellent utilizes the sensitivity of birds' auditory systems to ultrasonic waves of specific frequencies. When these frequencies are emitted, they cause discomfort to birds, thereby repelling them. Red and blue strobe lights, on the other hand, stimulate birds' visual systems by emitting intense, flickering light, disrupting their normal activities and deterring them from approaching. These two bird repellent methods work in conjunction with each other, working across diverse environmental conditions and time periods, enhancing the comprehensiveness and effectiveness of bird repellent.

[0081] refer to Figure 3 The bird repellent module includes a power supply unit, a single-chip microcomputer, an ultrasonic speaker, an infrared sensor and a red and blue dual-color LED flashing light;

[0082] The power supply unit includes a solar panel, a lithium battery, a solar charging module, and a lithium battery boost module; the solar panel, the lithium battery, and the lithium battery boost module are respectively connected to the solar charging module to convert solar energy into electrical energy and perform energy storage and boosting; the lithium battery boost module is connected to the single-chip microcomputer to provide power;

[0083] The single-chip microcomputer is connected to the ultrasonic speaker, infrared sensor and red and blue dual-color LED flashing light; the infrared sensor transmits the bird detection signal to the single-chip microcomputer, and the single-chip microcomputer drives the ultrasonic speaker through PWM to achieve frequency conversion according to the bird detection signal, and drives the red and blue dual-color LED flashing light.

[0084] The ultrasonic frequency of the bird repellent module is adjustable from 20kHz to 100kHz. Within this range, the ultrasonic frequency can be flexibly adjusted according to the specific application scenario and target bird species to achieve the best bird repellent effect.

[0085] The energy acquisition module is based on the principle of electric field coupling and realizes the integration of non-contact energy acquisition and power supply through double cylindrical plates. It is suitable for the continuous power supply needs of medium-voltage cable online monitoring equipment.

[0086] To maximize energy harvesting, energy harvesting modules are typically installed around medium-voltage cables and operate at high voltage. However, using a continuously switching active converter is impractical in this scenario because semiconductor devices typically have very small parasitic capacitances. When the system is charging and discharging, the AC input current requires nearly 0.5 milliseconds to switch phases due to the effects of parasitic capacitance. Within this transition time, any form of continuous switching high-frequency conversion is virtually impossible. Therefore, the present invention proposes the following energy harvesting circuit based on dual cylindrical plates.

[0087] refer to Figure 4 and Figure 5The energy taking circuit of the energy taking module of the present invention includes a rectifier bridge, an energy taking capacitor C, a capacitor C x , energy storage capacitor C g , Zener diode Z1, bidirectional trigger diode DIAC, diode D2, resistor R x , load R, switch tube Q1 and inductor L1;

[0088] The two AC input terminals of the rectifier bridge are respectively connected to the inner and outer plates of the double cylindrical plates, wherein the outer plates of the double cylindrical plates are grounded; the two DC output terminals of the rectifier bridge are connected to the two ends of the energy taking capacitor C;

[0089] The first end of the energy-taking capacitor C is connected to the first end of the inductor L1, and the second end of the energy-taking capacitor C is connected to the anode of the voltage-stabilizing diode Z1 and the resistor R x The first terminal, capacitor C x The first terminal is the source of the switch tube Q1; the cathode of the voltage regulator diode Z1 is connected to the resistor R x The second terminal, capacitor C x The second end, the gate of the switch tube Q1, the first anode of the bidirectional trigger diode DIAC, and the second anode of the bidirectional trigger diode DIAC are connected to the drain of the switch tube Q1, the anode of the diode D2, and the energy storage capacitor C g The second end of the load R, the second end of the inductor L1 is connected to the cathode of the diode D2, the energy storage capacitor C g The first terminal and the first terminal of the load R; the energy-taking voltage output is drawn from both ends of the load R.

[0090] The energy-taking circuit converts the displacement current i of the double cylindrical plates into d Converted into DC current I dc , and then use the self-triggering pulse to operate the Buck converter circuit to convert the voltage into a usable low-voltage output. The Buck converter circuit works as follows:

[0091] When the voltage across the energy-taking capacitor C rises to the trigger voltage V on When the switch Q1 is turned on, the energy transfer starts, and the energy stored in the energy storage capacitor C is transferred to the inductor L1 of the Buck circuit. Since the rate of this energy transfer is much higher than the input power from the AC side, the energy storage capacitor C g discharge;

[0092] When the voltage across capacitor C drops below the conduction threshold, switch Q1 turns off, transferring the energy stored in inductor L1 to the load. Once the energy transfer is complete, capacitor C slowly charges until it reaches the trigger voltage again, initiating the next pulse. Depending on the AC input voltage and the parallel parasitic capacitance, more than one energy pulse may occur during each AC fundamental frequency cycle.

[0093] The main goal of the above circuit of the present invention is to use the energy obtained from the DC side of the rectifier system to trigger Q1 without any auxiliary power supply.

[0094] The electric field strength around a energized cable is proportional to its potential. By installing the sensor in the above position, non-contact voltage measurement of the cable can be performed. The greater the voltage of the cable, the greater the induced voltage obtained by the sensor.

[0095] Figure 6 In the equation, C1 is the coupling capacitance between the measured cable and the sensor's sensing plate, C2 is the equivalent capacitance of the sensor to ground. U1 is the voltage of the measured cable, U3 is the induced voltage of the sensor, and R is the equivalent input impedance of the measuring device. The relationship between U1 and U3 is:

[0096]

[0097] The present invention uses Maxwell to simulate and analyze the voltage sensor and selects a structure suitable for use in medium-voltage cables. For cables with metal sheaths or armored layers, the voltage sensor is installed at the connector between the cable and the equipment end, while for overhead cables without armored layers, it can be hung directly on the cable. A cylindrical sensor with an inner diameter of 40mm, a length of 500mm, and a thickness of 1mm is established, and a 10kV cable model with an inner diameter of 10mm and a length of 1m is established at its coaxial center point. Considering that when measuring the cable voltage in an actual environment, there is a high probability that other energized conductors will exist, an identical cable model is placed 10cm next to the original conductor as interference. Since the interfering conductor will affect the stability of the coupled signal between the sensor and the cable being measured. Therefore, it is necessary to design a shielding layer for the sensor to prevent it from being affected by nearby energized conductors. The designed cylindrical sensor model with a shielding layer structure consists of two coaxial cylinders, the inner layer is the sensing plate, and the outer layer is the shielding plate. The inner plate has an inner diameter of r2 = 40mm and a length of l2 = 480mm; the outer plate has an inner diameter of r1 = 50mm and a length of l1 = 520mm; the thickness of the two plates is d = 1mm. After adding a grounded shield layer to the periphery of a single sensing plate, the electric field around the sensing plate remains evenly distributed under the effect of the shield layer, even if there is an interfering electric field nearby, and a relatively stable coupling capacitance can still be obtained. The principle of a cylindrical sensor with a grounded shield layer is as follows: Figure 7 As shown, by using the coupling capacitance between the sensing plate and the shielding layer to replace the stray coupling capacitance between the sensing plate and the ground, not only can the measured voltage be made more stable, but also the interference of external signals can be resisted.

[0098] In addition, considering that the sensing plate and the shielding plate need to be supported and fixed, polyvinyl chloride (PVC) material is added as the insulating medium between the bipolar plates in the simulation. The filling of the insulating medium improves the electric field distribution between the two plates, reduces the field strength between the plates, and reduces the risk of corona discharge.

[0099] Therefore, the present invention proposes a solution in which the energy extraction module and the voltage detection module share a double cylindrical plate installed outside the transmission cable. The voltage detection module includes a pre-circuit, a second-order Butterworth filter circuit and a level raising circuit; a resistor ( Figure 10 R14) and the outer metal plate is grounded; the signal input end of the preamplifier circuit is connected to the inner metal plate, the signal output end of the preamplifier circuit is connected to the second-order Butterworth filter circuit, the second-order Butterworth filter circuit is connected to the level-lifting circuit, and the level-lifting circuit leads to the raised voltage signal u out , which is the voltage signal required to be sampled.

[0100] Because the voltage signal obtained by contactless voltage measurement using electric field coupling is greater than the op amp's input voltage, a suitable preamplifier circuit is required to process the signal. Low noise, high input impedance, and low input capacitance are key requirements for the preamplifier circuit. This paper not only uses a high-performance op amp to design the preamplifier circuit, but also employs a bootstrap structure to provide a bias circuit for the op amp to stabilize operation and maintain the system's input impedance. Furthermore, due to the equivalent parasitic capacitance present in the signal transmission line, capacitance cancellation technology is incorporated into the preamplifier circuit to reduce the equivalent input capacitance and thereby improve the system's input impedance.

[0101] like Figure 8 As shown, the preamplifier circuit includes capacitors C1, C2, C3, resistors R1, R2, R3, R4, R5, R6, a potentiometer RW1, a first operational amplifier and a second operational amplifier;

[0102] A first end of capacitor C1 is connected to a first end of capacitor C3, a non-inverting input terminal of the first operational amplifier, and a first end of resistor R1; a second end of resistor R1 is connected to a first end of capacitor C2 and a first end of resistor R2; a second end of resistor R2 is connected to a first end of resistor R3 and to ground; a second end of resistor R3 is connected to a second end of capacitor C2, a first end of resistor R4, and an inverting input terminal of the first operational amplifier; a second end of resistor R4 is connected to the output terminal of the first operational amplifier and the non-inverting input terminal of the second operational amplifier; the inverting input terminal of the second operational amplifier is connected to a first end of resistor R5 and a first end of resistor R6; a second end of resistor R5 is connected to a first fixed end of potentiometer RW1 and to ground; a second fixed end of potentiometer RW1 is connected to a second end of resistor R6 and the output terminal of the second operational amplifier; and a movable end of potentiometer RW1 is connected to the second end of capacitor C3;

[0103] The second terminal of capacitor C1 is connected to the signal input (inner metal plate), and the output of the second operational amplifier is used as the voltage signal u in Connect to signal output.

[0104] To mitigate noise interference from the non-contact voltage sensor signal, a second-order Butterworth low-pass filter was designed. Since the signal being collected is a 50Hz industrial-frequency voltage signal, the filter's cutoff frequency f0 was set to 300Hz, effectively filtering out various noise signals. However, since the microcontroller unit (MCU)'s ADC module has a sampling range of 0 to +3.3V, a level-boosting circuit was also designed to enhance the voltage signal sampling quality by superimposing a DC component.

[0105] like Figure 9 As shown, the second-order Butterworth filter circuit and level-lifting circuit include capacitors C4, C5, and C6, resistors R7-R13, and a third operational amplifier and a fourth operational amplifier;

[0106] The output end of the second operational amplifier is connected to the first end of resistor R7, the second end of resistor R7 is connected to the first end of resistor R8, the first end of resistor R9, and the first end of capacitor C4, the second end of resistor R8 is connected to the first end of resistor R10, the second end of capacitor C5, and the output end of the third operational amplifier, the first end of capacitor C5 is connected to the second end of resistor R9 and the non-inverting input end of the third operational amplifier, the inverting input end of the third operational amplifier is connected to the second end of capacitor C4 and to ground, the second end of resistor R10 is connected to the first end of resistor R11 and the non-inverting input end of the fourth operational amplifier, the second end of resistor R11 is connected to the output end of the fourth operational amplifier, the first end of capacitor C6, and the cathode of Zener diode Z2, the second end of capacitor C6 is connected to the anode of Zener diode Z2 and to ground, the inverting input end of the fourth operational amplifier is connected to the second end of resistor R12, the first end of resistor R13, the second end of resistor R13 is grounded, and the first end of resistor R12 is connected to the positive power supply;

[0107] The voltage signal u after the cathode of the voltage stabilizing diode Z2 is raised out ;

[0108] The voltage signal expression after lifting is:

[0109]

[0110] where u out is the voltage signal after lifting, u in is the voltage signal before lifting, u ref is the reference voltage. In this simulation, R 10 =R 11 =10kΩ, R 12 =5.1kΩ, R 13=1kΩ.

[0111] like Figure 10 As shown, the preamplifier circuit, the second-order Butterworth filter circuit, and the level-lifting circuit are combined, and the first end of the resistor R14 is connected to the inner plate and the second end of C1, and the second end of the resistor R14 is connected to the outer plate and grounded to form a complete voltage sampling circuit diagram;

[0112] According to the above electric field energy extraction method and non-contact voltage detection method, and according to the existing magnetic coupling energy extraction method, the following can be obtained: Figure 11 The principle block diagram of the integrated sensing and supply shown in the figure ensures the normal power supply of the device while performing non-contact voltage detection.

[0113] The above are preferred embodiments of the present invention. Any changes made according to the technical solution of the present invention, as long as the resulting functions and effects do not exceed the scope of the technical solution of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. Multifunctional overhead cable fault protection device, characterized in that, Including fault precise positioning module, bird repelling module and sensor-supply integrated module; The fault accurate location module realizes short-circuit fault location under short-distance overhead cables through wavelet energy spectrum value and Chebyshev neural network; The bird repellent module uses variable frequency ultrasonic waves and red and blue flashing lights to synergistically repel birds; The integrated sensing and supply module includes an energy acquisition module and a voltage detection module. The energy acquisition module and the voltage detection module share a double cylindrical electrode plate installed outside the transmission cable to ensure normal power supply of the device while performing non-contact voltage detection.

2. The multifunctional overhead cable fault protection device according to claim 1, characterized in that: The short-circuit fault location under a short-distance overhead cable is realized by using wavelet energy spectrum value and Chebyshev neural network, as follows: Collect the current waveform and extract the wavelet energy spectrum value E4 to obtain the initial fault phase angle θ c And the first peak E4 of the fault current wavelet energy spectrum waveform max1 ; The first peak E4 of the fault current wavelet energy spectrum waveform max1 Perform natural logarithmic transformation to obtain the eigenvalue ln_E4 after logarithmic linearization max1 ; The initial fault phase angle θ c and eigenvalue ln_E4 max1 As a variable, the distance d from the short-circuit point to the detection point is used as the objective function, and the short-circuit fault location formula is obtained through Chebyshev neural network training; When a fault occurs and the fault type is determined to be a short circuit fault, the initial fault phase angle θ detected by the detection point is c and eigenvalue E4 max1 Substitute it into the short-circuit fault location formula and calculate the exact value of the fault location.

3. The multifunctional overhead cable fault protection device according to claim 2, characterized in that: The short-circuit fault location formula obtained through Chebyshev neural network training is as follows: Φ=(T0(x1)·T0(x2) T0(x1)·T1(x2) …T3(x1)·T3(x2)) (3) In formula (1), M represents the total number of two-dimensional Chebyshev polynomial tensor product basis functions. If the highest order of Chebyshev polynomial is k=3, then M=16; φ m Represents the element in the 1st row and the mth column of the basis function matrix φ; w m is the weight of the mth basis function; b is the bias; Formula (2) is the expression of input quantity X; Formula (3) is the recursive formula of Chebyshev orthogonal polynomial basis function Φ; Formula (4) is the expression of Chebyshev polynomial; Chebyshev polynomial T i In (x), i represents the order of the polynomial, and x1 and x2 refer to the two independent variables respectively.

4. The multifunctional overhead cable fault protection device according to claim 1, characterized in that: The bird-repelling module includes a power supply unit, a single-chip microcomputer, an ultrasonic speaker, an infrared sensor, and a red and blue dual-color LED flashing light; The power supply unit includes a solar panel, a lithium battery, a solar charging module, and a lithium battery boost module; the solar panel, the lithium battery, and the lithium battery boost module are respectively connected to the solar charging module to convert solar energy into electrical energy and perform energy storage and boosting; the lithium battery boost module is connected to the single-chip microcomputer to provide power; The single-chip microcomputer is connected to the ultrasonic speaker, infrared sensor and red and blue dual-color LED flashing light; the infrared sensor transmits the bird detection signal to the single-chip microcomputer, and the single-chip microcomputer drives the ultrasonic speaker through PWM to achieve frequency conversion according to the bird detection signal, and drives the red and blue dual-color LED flashing light.

5. The multifunctional overhead cable fault protection device according to claim 1, characterized in that: The ultrasonic frequency of the bird repellent module can be adjusted from 20kHz to 100kHz.

6. The multifunctional overhead cable fault protection device according to claim 1, characterized in that: The energy taking circuit of the energy taking module includes a rectifier bridge, an energy taking capacitor C, a capacitor C x , energy storage capacitor C g , Zener diode Z1, bidirectional trigger diode DIAC, diode D2, resistor R x , load R, switch tube Q1 and inductor L1; The two AC input terminals of the rectifier bridge are respectively connected to the inner and outer plates of the double cylindrical plates, wherein the outer plates of the double cylindrical plates are grounded; the two DC output terminals of the rectifier bridge are connected to the two ends of the energy taking capacitor C; The first end of the energy-taking capacitor C is connected to the first end of the inductor L1, and the second end of the energy-taking capacitor C is connected to the anode of the voltage-stabilizing diode Z1 and the resistor R x The first terminal, capacitor C x The first terminal is the source of the switch tube Q1; the cathode of the voltage regulator diode Z1 is connected to the resistor R x The second terminal, capacitor C x The second end, the gate of the switch tube Q1, the first anode of the bidirectional trigger diode DIAC, and the second anode of the bidirectional trigger diode DIAC are connected to the drain of the switch tube Q1, the anode of the diode D2, and the energy storage capacitor C g The second end of the load R, the second end of the inductor L1 is connected to the cathode of the diode D2, the energy storage capacitor C g The first terminal and the first terminal of the load R; the energy-taking voltage output is drawn from both ends of the load R.

7. The multifunctional overhead cable fault protection device according to claim 6, characterized in that: The energy-taking circuit converts the displacement current i of the double cylindrical plates into d Converted into DC current I dc , and then use the self-triggering pulse to operate the Buck converter circuit to convert the voltage into a usable low-voltage output. The Buck converter circuit works as follows: When the voltage across the energy-taking capacitor C rises to the trigger voltage V on When , the switch Q1 is turned on, transferring the energy stored in the energy-taking capacitor C to the inductor L1 of the Buck circuit; When the voltage across the energy-harvesting capacitor C drops below the conduction threshold, the switch Q1 is turned off and the energy stored in the inductor L1 is transferred to the load. Once the energy transfer is completed, the energy-harvesting capacitor C slowly charges until it reaches the trigger voltage level again and the next pulse begins.

8. The multifunctional overhead cable fault protection device according to claim 1, characterized in that: The voltage detection module includes a pre-circuit, a second-order Butterworth filter circuit and a level raising circuit; A resistor is connected between the inner and outer metal plates and the outer metal plate is grounded; The signal input end of the preamplifier circuit is connected to the inner metal plate, and the signal output end of the preamplifier circuit is connected to the second-order Butterworth filter circuit. The second-order Butterworth filter circuit is connected to the level-lifting circuit, and the level-lifting circuit leads to the raised voltage signal u out , which is the voltage signal required to be sampled.

9. The multifunctional overhead cable fault protection device according to claim 8, characterized in that: The preamplifier circuit includes capacitors C1, C2, C3, resistors R1, R2, R3, R4, R5, R6, a potentiometer RW1, a first operational amplifier and a second operational amplifier; A first end of capacitor C1 is connected to a first end of capacitor C3, a non-inverting input terminal of the first operational amplifier, and a first end of resistor R1; a second end of resistor R1 is connected to a first end of capacitor C2 and a first end of resistor R2; a second end of resistor R2 is connected to a first end of resistor R3 and to ground; a second end of resistor R3 is connected to a second end of capacitor C2, a first end of resistor R4, and an inverting input terminal of the first operational amplifier; a second end of resistor R4 is connected to the output terminal of the first operational amplifier and the non-inverting input terminal of the second operational amplifier; the inverting input terminal of the second operational amplifier is connected to a first end of resistor R5 and a first end of resistor R6; a second end of resistor R5 is connected to a first fixed end of potentiometer RW1 and to ground; a second fixed end of potentiometer RW1 is connected to a second end of resistor R6 and the output terminal of the second operational amplifier; and a movable end of potentiometer RW1 is connected to the second end of capacitor C3; The second terminal of capacitor C1 is connected to the signal input, and the output of the second operational amplifier is used as the voltage signal u in Connect to signal output.

10. The multifunctional overhead cable fault protection device according to claim 9, characterized in that: The second-order Butterworth filter circuit and level-lifting circuit include capacitors C4, C5, and C6, resistors R7-R13, and a third operational amplifier and a fourth operational amplifier; The output end of the second operational amplifier is connected to the first end of resistor R7, the second end of resistor R7 is connected to the first end of resistor R8, the first end of resistor R9, and the first end of capacitor C4, the second end of resistor R8 is connected to the first end of resistor R10, the second end of capacitor C5, and the output end of the third operational amplifier, the first end of capacitor C5 is connected to the second end of resistor R9 and the non-inverting input end of the third operational amplifier, the inverting input end of the third operational amplifier is connected to the second end of capacitor C4 and to ground, the second end of resistor R10 is connected to the first end of resistor R11 and the non-inverting input end of the fourth operational amplifier, the second end of resistor R11 is connected to the output end of the fourth operational amplifier, the first end of capacitor C6, and the cathode of Zener diode Z2, the second end of capacitor C6 is connected to the anode of Zener diode Z2 and to ground, the inverting input end of the fourth operational amplifier is connected to the second end of resistor R12, the first end of resistor R13, the second end of resistor R13 is grounded, and the first end of resistor R12 is connected to the positive power supply; The voltage signal u after the cathode of the voltage stabilizing diode Z2 is raised out ; The voltage signal expression after lifting is: where u out is the voltage signal after lifting, u in is the voltage signal before lifting, u ref is the reference voltage.

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