A three-core cable energy extraction device and monitoring system

Abstract

The present application belongs to an energy acquisition device. In view of the technical problems that the existing energy acquisition methods of online monitoring equipment have high environmental dependence, high operating costs, and low energy acquisition efficiency, a three-core cable energy acquisition device and monitoring system are provided. The energy acquisition magnetic core is in the shape of a hollow column, which is used to be sleeved on the outer wall of the three-core cable. Three receiving grooves are opened on the inner wall of the energy acquisition magnetic core. The receiving grooves extend axially. The three receiving grooves are evenly distributed along the circumference. Bosses are formed between adjacent receiving grooves. Each single-phase induction coil in the three-phase induction coil is respectively wound on the three bosses, and each single-phase induction coil is respectively located in the receiving grooves on both sides of the corresponding bosses. Compared with the existing current transformer energy acquisition method, it adopts a completely different energy acquisition principle, which can fully capture the spatial magnetic field energy around the three-core cable, improve the induced potential of the induction coil, ensure the stable output of energy, and have high energy acquisition efficiency and are independent of the environment.

Description

Technical Field

[0001] The present application relates to an energy harvesting device, and specifically to a three-core cable energy harvesting device and a monitoring system. Background Art

[0002] In recent years, with the acceleration of urbanization and the continuous growth of electricity demand, the scale of urban power grids has developed rapidly. Among them, power cables, with their high efficiency, safety and beautiful appearance, have gradually replaced traditional overhead lines and become an indispensable power transmission method in modern cities. However, unlike overhead lines that are directly exposed to the air, power cables are usually laid in underground pipelines or closed tunnels. Compared with overhead lines, the working environment of power cables is more complex and harsh. Once a fault occurs, it may not only cause power supply interruption, but also cause serious damage to the surrounding environment and facilities. Therefore, real-time monitoring and management of cable operation status has become particularly important. It also makes the construction of a cable operation status monitoring system consisting of online monitoring equipment a focus of common concern in academia and industry.

[0003] At present, methods including solar energy, laser energy and traditional current transformer (CT) energy have been proposed to solve the energy supply problem of online monitoring equipment. However, each technology has its inherent disadvantages, such as high dependence on the environment, high operating costs, and low energy efficiency. Therefore, how to achieve efficient and stable energy collection from three-core cables has become a technical problem that technicians in this field urgently need to overcome. Summary of the invention

[0004] In view of the technical problems that the existing energy acquisition methods for online monitoring equipment have high environmental dependence, high operating costs, and low energy acquisition efficiency, the present application provides a three-core cable energy acquisition device and a monitoring system.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions:

[0006] In a first aspect, the present application proposes a three-core cable energy harvesting device, including an energy harvesting magnetic core and a three-phase induction coil;

[0007] The energy-taking magnetic core is in the shape of a hollow column and is used to be sleeved on the outer wall of the three-core cable; three receiving grooves are provided on the inner wall of the energy-taking magnetic core; the receiving grooves extend along the axial direction, and the three receiving grooves are evenly distributed along the circumferential direction, and bosses are formed between adjacent receiving grooves;

[0008] Each single-phase induction coil in the three-phase induction coil is wound on three bosses respectively, and each single-phase induction coil is located in a receiving groove on both sides of the corresponding boss.

[0009] Furthermore, the numbers of turns of the three-phase induction coils are equal.

[0010] Furthermore, a method for determining the number of turns of a single-phase induction coil includes:

[0011] Obtain the magnetic induction intensity in the space around the three-core cable;

[0012] According to the magnetic induction intensity in the space around the three-core cable, calculate the induced voltage value of one turn of the single-phase induction coil;

[0013] The number of turns of the single-phase induction coil is determined by combining the induced voltage value of one turn of the single-phase induction coil and the ideal induced voltage value.

[0014] Furthermore, the energy extraction magnetic core is cylindrical;

[0015] The width of the accommodating groove is determined according to the inner diameter of the energy extraction magnetic core;

[0016] The depth of the accommodating groove is determined according to the number of turns of the corresponding single-phase induction coil and the wire diameter of the conductor.

[0017] Furthermore, the method for determining the axial length of the energy extraction magnetic core comprises:

[0018] Determine the resistance of the single-phase induction coil and the load resistance;

[0019] According to the resistance of the single-phase induction coil and the load resistance, the relationship between the maximum energy extraction power of the single-phase induction coil and the axial length of the energy extraction magnetic core is determined.

[0020] Furthermore, the single-phase induction coil is in the shape of an arc, with an inner diameter center angle of 60° and an outer diameter center angle of 120°.

[0021] Furthermore, the energy extraction magnetic core is a split structure, and the parts of the split structure are spliced ​​along the circumferential direction to form the overall structure of the energy extraction magnetic core.

[0022] Furthermore, the space volumes occupied by adjacent single-phase induction coils in the accommodating slot are equal.

[0023] In a third aspect, the present application proposes a three-core cable monitoring system, including a monitoring device, an energy extraction device, a charging circuit, and a power supply device;

[0024] The energy acquisition device adopts the above-mentioned three-core cable energy acquisition device;

[0025] The three induction coils of the three-core cable energy extraction device are respectively connected to the three phases of the input side of the charging circuit, and the output side of the charging circuit is connected to the power supply device and the monitoring equipment.

[0026] Compared with the prior art, this application has the following beneficial effects:

[0027] The present application proposes a three-core cable energy-taking device, in which three receiving grooves are provided on the inner wall of the energy-taking magnetic core, bosses are formed between adjacent receiving grooves, and three-phase induction coils are wound on the three bosses. The energy-taking magnetic core is set to a hollow columnar shape, and the unique design allows the energy-taking magnetic core to fit on the surface of the three-core cable, maximizing the contact area with the three-core cable, so that the spatial magnetic field energy around the three-core cable can be fully captured. At the same time, the energy-taking magnetic core is provided with three receiving grooves, and the size of the receiving grooves can be designed to allow the energy-taking magnetic core to be wound with more turns of induction coils under the same size, while enhancing the magnetic induction intensity in the bosses, thereby increasing the induced potential of the induction coils. In addition, the single-phase induction coils are respectively wound on the three bosses of the energy-taking magnetic core and cleverly embedded in the receiving grooves. The volume of the receiving grooves occupied by both sides of each single-phase induction coil in the two adjacent receiving grooves can be adjusted to control the induced voltage value of each phase output, so as to ensure the stable output of energy. Therefore, the three-core cable energy-taking device of the present application is not dependent on the environment and has high energy-taking efficiency.

[0028] The present application also proposes a three-core cable monitoring system, which uses the three-core cable energy extraction device proposed in the present application to output a three-phase AC induced voltage to the charging circuit, and supplies power to the monitoring equipment through the power supply device. It also has all the advantages of the above-mentioned three-core cable energy extraction device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 This is a schematic diagram of the installation of an embodiment of the three-core cable energy harvesting device of the present application.

[0031] Figure 2 for Figure 1 Top view of the energy extraction core.

[0032] Figure 3 for Figure 1 Three-dimensional structure diagram of the energy-extracting magnetic core.

[0033] Figure 4 A structural schematic diagram of a single-phase induction coil.

[0034] Figure 5 This is a schematic diagram of an embodiment of a three-core cable monitoring system of the present application.

[0035] Figure 6 This is a model diagram of three-core cable with parallel infinitely long straight conductors.

[0036] Figure 7 The simulation waveform of the induced voltage value of the single-phase induction coil under different bus currents.

[0037] Among them: 1-three-core cable, 2-energy extraction power supply module, 3-energy extraction magnetic core, 4-charging circuit, 5-single-phase induction coil, 6-receiving slot, 7-boss, 8-power supply device, 9-monitoring equipment. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0040] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0041] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invented product is usually placed when used. It is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0042] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0043] In the description of the embodiments of the present application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] In practical applications, power cables are usually laid in underground pipelines or closed tunnels. Because the underground environment has many uncertain factors, such as temperature, humidity, soil conditions, water penetration, chemical corrosion, mechanical stress, etc., they may affect the performance and life of power cables. Therefore, compared with overhead lines, the working environment of power cables is more complex and harsh. It is necessary to monitor the reliability and safety of power cable operation through a monitoring system, which is of great significance. However, due to the particularity of the working environment, the energy supply problem of the monitoring system has become the main bottleneck restricting the development of monitoring. The main reason is that the sensor nodes in the monitoring system are usually distributed, and most of the nodes are in underground or tunnel environments with harsh environments and difficult maintenance, making traditional wired power supply methods impractical.

[0045] Some of the methods currently used have inherent defects:

[0046] (1) Solar energy technology: With mature technology and extensive application experience, it has become the preferred solution for energy supply in many online monitoring systems. However, solar energy technology is highly dependent on environmental conditions. In clear weather, solar energy equipment can efficiently convert solar energy into electrical energy, but on cloudy days or at night, the energy density will drop significantly, even less than one-tenth of that on sunny days. In addition, the load capacity of solar energy equipment is limited and cannot meet the operating requirements of some high-energy consumption equipment. More importantly, photovoltaic cells, as the core component of the solar energy system, also need regular cleaning and maintenance, which increases the operating cost of the system.

[0047] (2) Laser power supply technology: Energy is transmitted from the transmitter to the receiver through a laser beam to provide electrical energy for the online monitoring system. However, the energy transmission efficiency of laser power supply technology is not high, and most of the energy will be dissipated in the air during the transmission process. This means that in order to meet the energy requirements of the online monitoring system, it is necessary to increase the power of the laser or reduce the distance between the transmitter and the receiver, but this will increase the complexity and cost of the system. In addition, laser power supply technology is also susceptible to environmental factors, such as dust and smoke in the air, which will affect the transmission effect of the laser. Therefore, laser power supply technology is not suitable for situations where the nodes are widely distributed, and it is difficult to apply to the underground pipe gallery environment where the three-core cable is located.

[0048] (3) Current transformer energy harvesting technology: Since overhead lines generally adopt a single-core cable design, the surrounding magnetic field distribution is relatively uniform, which makes current transformer energy harvesting technology widely used in this field, effectively harvesting energy through the principle of electromagnetic induction. However, for three-core cables, there is a spatial magnetic field generated by three-phase currents in the surrounding space at the same time. These magnetic fields are superimposed together, making the magnetic field distribution uneven. In traditional current transformer energy harvesting technology, the induction coil is evenly wound on the surface of the energy harvesting magnetic core. The induction coils distributed at different positions will generate induced currents in opposite directions in the uneven magnetic field, thereby canceling each other out, resulting in extremely low efficiency in harvesting energy from the three-core cable.

[0049] Therefore, how to achieve efficient and stable energy collection from three-core cables has become a technical problem that technicians in related fields urgently need to overcome.

[0050] Based on the above situation, the present application proposes a three-core cable energy extraction device and a monitoring system. The present application is described in detail below in conjunction with embodiments and drawings.

[0051] The three-core cable 1 is composed of three electrical conductors. Since the power frequency current flows through the cable, the three-phase current is basically offset after synthesis, making it impossible to directly draw electricity by induction outside the cable. As an embodiment of the three-core cable energy collection device of the present application, it may include an energy collection magnetic core 3 and a three-phase induction coil. The present application mainly focuses on the difficulty of energy collection of the three-core cable 1, designs the combined structure of the energy collection magnetic core 3 and the three-phase induction coil, and then provides an energy collection method with a different principle.

[0052] The energy-taking magnetic core 3 is in the shape of a hollow column and is used to be sleeved on the outer wall of the three-core cable 1. It should be noted that the specific shape of the energy-taking magnetic core 3 is compatible with the external shape of the three-core cable 1, and should usually be a hollow cylindrical shape. In some special cases, if the external shape of the three-core cable 1 changes, the specific shape of the energy-taking magnetic core 3 only needs to be adaptively adjusted. In order to maximize the surface contact, the energy-taking magnetic core 3 can be in contact with the surface of the three-core cable 1.

[0053] Three receiving grooves 6 are provided on the inner wall of the energy extraction magnetic core 3. The receiving grooves 6 extend in the axial direction, and the three receiving grooves 6 are evenly distributed in the circumferential direction, and bosses 7 are formed between adjacent receiving grooves 6. It should be noted that the specific size of the receiving grooves 6, the relative size of the receiving grooves 6 and the bosses 7, etc. can be designed according to the required energy extraction results.

[0054] Each single-phase induction coil 5 in the three-phase induction coil is wound on three bosses 7, and each single-phase induction coil 5 is located in a receiving groove 6 on both sides of the corresponding boss 7. In practical applications, one side of two adjacent single-phase induction coils 5 is respectively accommodated in one receiving groove 6, and the induced voltage value outputted by each phase can be controlled by controlling the volume occupied by two adjacent single-phase induction coils 5 in one receiving groove 6, so that the three-core cable energy extraction device of the present application has a wider application prospect.

[0055] The energy harvesting method corresponding to the three-core cable energy harvesting device of the present application may include:

[0056] The energy-collecting magnetic core 3 is sleeved on the outside of the three-core cable 1, and the three-phase induction coil is distributed circumferentially on the outside of the three-core cable 1. The extension direction of the three-phase induction coil is parallel to the axial direction of the three-core cable 1. When the three-phase AC current is passed through the three-core cable 1, energy is collected through the three-phase induction coil. In practical applications, three-phase industrial frequency AC current is passed through the three-core cable 1, and a constantly changing spatial magnetic field is generated around it. The energy-collecting magnetic core 3 is sleeved on the outside of the three-core cable 1, and can gather the spatial magnetic field around the three-core cable. The three-phase induction coil is wound on the boss 7 of the magnetic core, and the alternating magnetic field passes through the inside of the coil. Through the principle of electromagnetic induction, the three-phase induction coil obtains the energy of the spatial magnetic field around the three-core cable 1 and converts it into electrical energy, and then outputs a three-phase AC induced voltage.

[0057] In some embodiments of the present application, in order to facilitate installation, the energy-taking magnetic core 3 can adopt a split structure, and the parts of the split structure are spliced ​​circumferentially into the overall structure of the energy-taking magnetic core 3. In practical applications, the parts of the split structure can be multiple parts divided evenly, or multiple parts divided unevenly, and can be adjusted according to the needs of use and processing. For example, it can be divided into two equally divided parts to form two magnetic cores distributed up and down. The installation process is simple and quick, and the installation can be completed directly on the surface of the three-core cable 1 without powering off, which improves the environmental adaptability and work efficiency. At the same time, it also brings great convenience to subsequent maintenance work. By adjusting the number and specific structure of each part of the split structure, the energy-taking device can be made more flexible and adaptable to more complex environments and scenes, and further enhance versatility and practicality. In practical applications, the connection method between each split structure can be a card-mounted connection, or any other detachable connection method that can ensure a stable and firm connection.

[0058] Specifically, an example is used to illustrate the three-core cable energy extraction device of the present application. Figure 1 As shown, Figure 1 This is a schematic diagram of the installation of an embodiment of the three-core cable energy extraction device of the present application. Figure 2 As shown in FIG. 1 , it is a top view of the energy extraction magnetic core 3. Figure 3 As shown, it is a three-dimensional structural diagram of the energy-taking magnetic core 3. The three-core cable energy-taking device is sleeved on the outside of the three-core cable 1. The energy-taking magnetic core 3 is a split structure with an upper and lower split structure. The inner wall of the upper half of the magnetic core is provided with a receiving groove 6, and the inner wall of the lower half of the magnetic core is provided with two receiving grooves 6. The inner wall of the energy-taking magnetic core 3 is evenly provided with three receiving grooves 6 along the circumferential direction. The receiving grooves 6 extend along the axial direction of the energy-taking magnetic core 3 and pass through the two axial ends of the energy-taking magnetic core 3. Figure 4 As shown, it is a schematic diagram of the structure of a single-phase induction coil 5. The single-phase induction coil 5 is in the shape of an arc, with an inner diameter center angle of 60° and an outer diameter center angle of 120°. Correspondingly, the spatial contour of the accommodating groove 6 is also in the shape of an arc, with a center angle of 60° for each accommodating groove 6. The three accommodating grooves 6 are rotationally symmetrical with the center of the axial section of the energy-taking magnetic core 3 as the rotation point, and the rotation angle is 120°, ensuring that the number of winding turns of the induction coil is maximized under the premise that the size of the energy-taking magnetic core 3 remains unchanged, thereby enhancing the induced potential of the induction coil. The three-phase induction coils are respectively wound on the three bosses 7 on the inner wall of the energy-taking magnetic core 3, and the energy is placed along the circumferential direction of the surface of the three-core cable 1. The two sides of the induction coil are embedded in the accommodating groove 6, and one side of the single-phase induction coil 5 is embedded in the accommodating groove 6 to occupy half the volume of the accommodating groove 6. Two-phase induction coils are embedded in each accommodating groove 6. The energy-taking magnetic core 3 and the three-phase induction coils together constitute the energy-taking power supply module 2.

[0059] Accordingly, the present application also proposes a three-core cable monitoring system. Figure 5 As shown, it is a schematic diagram of an embodiment of the three-core cable monitoring system of the present application. It can include a monitoring device 9, an energy extraction device, a charging circuit 4 and a power supply device 8. Among them, the energy extraction device adopts the three-core cable energy extraction device proposed in the present application. The three induction coils of the three-core cable energy extraction device are respectively connected to the three phases ( Figure 5 The output side of the charging circuit 4 is connected to the power supply device 8 and the monitoring device 9. The energy-collecting magnetic core 3 is mounted on the surface of the three-core cable 1, and the three-phase induction coil collects energy along the circumferential direction of the surface of the three-core cable 1. The three-core cable energy-collecting device outputs a three-phase AC induced voltage, and supplies energy to the power supply device 8 and the monitoring device 9 through the charging circuit 4. By using the principle of electromagnetic induction, the energy-collecting magnetic core 3 is mounted on the surface of the three-core cable 1. Through the ingenious layout of the internal accommodating groove 6, the boss 7 and the induction coil of the energy-collecting magnetic core 3, efficient and stable energy collection is achieved.

[0060] The three-core cable monitoring system of the present application is combined with the example of the aforementioned three-core cable energy extraction device. By setting the energy extraction magnetic core 3 to be a hollow cylindrical shape, the contact area with the three-core cable 1 is maximized, thereby fully capturing the spatial magnetic field energy around the three-core cable 1. The layout of the grooves and the bosses 7 enables the energy extraction magnetic core 3 to efficiently gather magnetism, enhance the magnetic induction intensity in the bosses 7, and thus increase the induced potential of the induction coil. In addition, the two sides of the induction coil are cleverly distributed in half the volume of two adjacent grooves, keeping the output induced voltage value consistent, which not only simplifies the topological structure of the charging circuit 4, but also ensures the stable output of energy.

[0061] In practical applications, in some embodiments of the three-core cable monitoring system of the present application, the power supply device 8 can directly use a battery, or other devices capable of supplying power to achieve energy storage and energy supply. In addition, it should be noted that the charging circuit 4 and the monitoring device 9 can adopt existing related structures, which will not be repeated here.

[0062] It should be noted that in order to achieve a better energy extraction effect, the specific parameters of the receiving slot 6, the energy extraction magnetic core 3, and the coil can also be designed:

[0063] As an example, the material of the energy extraction magnetic core 3 is silicon steel, and the induction coil is copper wire. The number of turns of the single-phase induction coil 5 wound on each boss 7 is equal. Then the number of turns of the single-phase induction coil This can be determined by:

[0064] (1) Calculate the magnetic induction intensity and distribution in the space around the three-core cable 1.

[0065] like Figure 6 As shown in the figure, it is a model diagram of a three-core cable 1 with infinitely long parallel straight conductors. Assume that the center point of the three-core cable 1 is located at the origin of the coordinate system, and the radius of each phase cable is , take any point outside the cable , the coordinates are set to . , , The magnetic induction intensity generated by each phase of the three-phase infinitely long parallel straight wire in the surrounding area is:

[0066]

[0067] in, is the magnetic permeability of air, is the relative magnetic permeability, is the current amplitude on each phase conductor, for Click to The distance between the centers of the phase cables, for Click to The distance between the centers of the phase cables, for Click to The distance between the centers of the phase cables, is the electrical angle, For time, is the phase angle, for Phase magnetic field unit vector, for Phase magnetic field unit vector, for Phase magnetic field unit vector, for The magnetic induction intensity generated by the infinitely long parallel straight wire around it is for The magnetic induction intensity generated by the infinitely long parallel straight wire around it is for The magnetic induction intensity generated by infinitely long parallel straight wires in the surrounding area.

[0068] in:

[0069]

[0070] in, is the cable radius per phase.

[0071] Substitute equation (1-1) into equation (1-2) and connect the three-phase cable The magnetic field generated at each point is summed and decomposed into the coordinate axis Direction and Direction, get the magnetic induction intensity of the space around the three-core cable 1 for:

[0072]

[0073] in:

[0074]

[0075] in, for Axis direction unit vector, for Axis direction unit vector.

[0076] (2) Calculate the induced voltage value of one turn of the single-phase induction coil 5 .

[0077]

[0078] in, is the axial length of the energy-taking magnetic core 3, is the inner diameter of the energy-taking magnetic core 3, It is the slot depth of the accommodating groove 6.

[0079] (3) According to the ideal induced voltage value , calculate the number of turns of the single-phase induction coil 5 .

[0080]

[0081] Axial length of the energy extraction core 3 The maximum power of the single-phase induction coil 5 can be expected Sure:

[0082] (1) Calculate the resistance of the single-phase induction coil 5 .

[0083]

[0084] in, is the short side length of the single-phase induction coil 5, is the resistivity of copper, is the wire diameter of the single-phase induction coil 5.

[0085] (2) Calculate the load resistance .

[0086] According to the maximum power transfer theorem of circuit theory, when the load impedance is equal to the internal impedance, the power output power of the power supply is the maximum, so:

[0087]

[0088] (3) Calculate the axial length of the energy-harvesting magnetic core 3 and the maximum energy-harvesting power of the single-phase induction coil 5 The relationship between.

[0089]

[0090] in, is the induced voltage value of the single-phase induction coil.

[0091] According to the above relationship, the appropriate axial length of the energy extraction magnetic core 3 can be designed, and the axial length of the energy extraction magnetic core 3 and the number of turns of the single-phase induction coil can be jointly solved. As an optimal design solution, When the requirements are met, the axial length of the energy extraction magnetic core 3 is made as small as possible.

[0092] It should be noted that the specific structure of the energy extraction device in the present application can further optimize the structure of the receiving groove 6:

[0093] The width of the opening of each receiving groove 6 is for:

[0094]

[0095] The depth of each receiving groove 6 for:

[0096]

[0097] In addition, the core thickness at the boss 7 is It can be:

[0098]

[0099] Based on the above parameter design results, the structure with the best energy extraction effect can be obtained. In practical applications, appropriate adjustments can also be made.

[0100] In order to verify the energy extraction effect of the present application, the induced voltage value of the single-phase induction coil 5 is simulated using different bus currents, such as Figure 7 As shown in the figure, it is a simulation waveform of the induced voltage value of the single-phase induction coil 5 under different bus currents. The common YJV22-10kv-3*240 three-core cable 1 is used as the simulation object, and the number of turns of the single-phase induction coil 5 is taken as 300 turns, copper wire diameter 0.8mm, take the length of the energy core 3 25cm. When the effective values ​​of the bus current are 50A, 100A, and 150A respectively, the peak values ​​of the induced voltage of the single-phase induction coil 5 are 1.2V, 2.52V, and 3.75V respectively; the corresponding maximum powers are 43mW, 180mW, and 402mW respectively; the total powers of the three-phase induction coils after superposition are 129mW, 540mW, and 1.2W respectively. It can be seen that when the bus current reaches more than 100A, the output power of the energy extraction device proposed in this application can meet the power supply requirements of online monitoring equipment 9 such as temperature measurement and ultrasonic partial discharge and microprocessor chips.

[0101] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A three-core cable energy harvesting device, comprising an energy harvesting magnetic core (3) and a three-phase induction coil; characterized in that: The energy extraction magnetic core (3) is in the shape of a hollow column and is used to be sleeved on the outer wall of the three-core cable (1); three receiving grooves (6) are provided on the inner wall of the energy extraction magnetic core (3); the receiving grooves (6) extend in the axial direction, the three receiving grooves (6) are evenly distributed in the circumferential direction, and bosses (7) are formed between adjacent receiving grooves (6); Each single-phase induction coil (5) in the three-phase induction coil is respectively wound on three bosses (7), and each single-phase induction coil (5) is respectively located in a receiving groove (6) on both sides of the corresponding boss (7); one side of two adjacent single-phase induction coils (5) is respectively received in one receiving groove (6), and the induced voltage value outputted by each phase is controlled by controlling the volume occupied by the two adjacent single-phase induction coils (5) in one receiving groove (6); the spatial contour of the receiving groove (6) is also in the shape of an arc, and the center angle of each receiving groove (6) is 60°; the single-phase induction coil (5) is in the shape of an arc, and the center angle of the inner diameter is 60°; The three receiving grooves (6) are in a rotationally symmetrical structure with the center of the axial section of the energy extraction magnetic core (3) as the rotation point, and the rotation angle is 120°.

2. A three-core cable energy extraction device according to claim 1, characterized in that: The three-phase induction coils have equal number of turns.

3. A three-core cable energy extraction device according to claim 2, characterized in that: A method for determining the number of turns of a single-phase induction coil (5) comprises: Obtaining the magnetic induction intensity of the space around the three-core cable (1); Calculate the induced voltage value of one turn of the single-phase induction coil (5) according to the magnetic induction intensity in the space around the three-core cable (1); The number of turns of the single-phase induction coil (5) is determined by combining the induced voltage value of one turn of the single-phase induction coil (5) and the ideal induced voltage value.

4. A three-core cable energy extraction device according to any one of claims 1 to 3, characterized in that: The energy extraction magnetic core (3) is cylindrical; The width of the opening of the accommodating groove (6) is determined according to the inner diameter of the energy extraction magnetic core (3); The depth of the accommodating groove (6) is determined according to the number of turns of the corresponding single-phase induction coil (5) and the wire diameter of the conductor.

5. A three-core cable energy extraction device according to claim 4, characterized in that: The method for determining the axial length of the energy extraction magnetic core (3) comprises: Determining the resistance of the single-phase induction coil (5) and the load resistance; According to the resistance of the single-phase induction coil (5) and the load resistance, the relationship between the maximum energy extraction power of the single-phase induction coil (5) and the axial length of the energy extraction magnetic core (3) is determined.

6. A three-core cable energy extraction device according to claim 5, characterized in that: The single-phase induction coil (5) is in the shape of an arc, with an inner diameter center angle of 60° and an outer diameter center angle of 120°.

7. A three-core cable energy extraction device according to claim 6, characterized in that: The energy extraction magnetic core (3) is a split structure, and the parts of the split structure are spliced ​​along the circumferential direction to form the overall structure of the energy extraction magnetic core (3).

8. A three-core cable energy extraction device according to claim 7, characterized in that: The space occupied by adjacent single-phase induction coils (5) in the accommodation groove (6) has the same volume.

9. A three-core cable monitoring system, comprising a monitoring device (9), an energy extraction device, a charging circuit (4) and a power supply device (8); characterized in that: The energy harvesting device adopts the three-core cable energy harvesting device described in any one of claims 1 to 8; The three induction coils of the three-core cable energy extraction device are respectively connected to the three phases of the input side of the charging circuit (4), and the output side of the charging circuit (4) is connected to the power supply device (8) and the monitoring equipment (9).

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