A three-core cable leakage magnetic field energy harvesting circuit and cable head discharge detection device

Abstract

The present invention provides a three-core cable leakage magnetic field energy harvesting circuit and a cable head discharge detection device, which belongs to the field of energy harvesting power supply technology, including: an energy harvesting magnetic core, used to induce alternating current from the cable; an energy harvesting circuit, used to rectify the alternating current and supply power to the measuring circuit; the measuring circuit is used to determine the intensity of the local discharge of the cable head according to the sound wave signal collected by the ultrasonic sensor, and when the intensity of the local discharge of the cable head is greater than the preset value, an alarm is issued and the cable power supply is cut off. The present invention can capture the intensity of the local discharge of the cable head through the ultrasonic sensor, and automatically issue an alarm when the intensity of the local discharge exceeds the preset value, so that the staff can take measures in time to reduce the risk of accidents. In addition, based on the energy harvesting magnetic core and the energy harvesting circuit, the present invention can provide a convenient and stable power supply for the measuring circuit. This energy harvesting method not only enhances the adaptability and flexibility of the system, but also ensures the long-term and reliable operation of the detection module.

Description

Technical Field

[0001] The present invention relates to the technical field of energy-taking power supply, and in particular to a three-core cable leakage magnetic field energy-taking circuit and a cable head discharge detection device. Background Art

[0002] Power cables are an indispensable and important part of the power transmission system, and their reliability directly affects the safe operation of the power system. As an important connection node of the cable, the cable head undertakes the key task of power transmission. However, due to the influence of various factors such as manufacturing process, installation quality and environmental conditions, the cable head is prone to partial discharge during use.

[0003] Partial discharge refers to the electrical discharge phenomenon that occurs inside or in a local area on the surface of the cable insulation material. This phenomenon is usually caused by the aging, defects or external environmental influences of the insulation material. Partial discharge not only leads to the gradual deterioration of the cable insulation, but may even lead to insulation breakdown, which in turn causes serious failures in the power system. However, in the detection of partial discharge of power cables, traditional detection methods mainly rely on the experience and judgment of power workers, which is prone to missed detection or misjudgment. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, an object of the present invention is to provide a three-core cable leakage magnetic field energy harvesting circuit and a cable head discharge detection device.

[0005] To achieve the above objectives, the present invention provides the following solutions:

[0006] A three-core cable leakage magnetic field energy harvesting circuit, comprising:

[0007] The energy-harvesting magnetic core is installed on the outside of the cable and is used to obtain energy from the changing spatial magnetic field generated around the cable and convert it into alternating current;

[0008] The energy-taking circuit is connected to the energy-taking magnetic core and the energy storage capacitor respectively, and is used to charge the energy storage capacitor after rectifying the alternating current; the energy storage capacitor is used for power supply.

[0009] Preferably, the energy extraction magnetic core comprises:

[0010] The annular energy-taking core is composed of three identical cores, each core covers 120°, each core has grooves at both ends, and receiving grooves are formed between adjacent grooves. The single-phase induction coils of the three-phase induction coils are respectively wound on the grooves at both ends of each core to form winding A, winding B and winding C. A coil tangential to winding A, winding B and winding C is also separately wound between each receiving groove to form winding X, winding Y and winding Z.

[0011] Preferably, the energy extraction circuit comprises:

[0012] A first capacitor C1, one end of the first capacitor C1 is connected to one end of the winding A, the other end of the first capacitor C1 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to one end of the load resistor R2;

[0013] a second switch tube Q2, wherein the gate of the second switch tube Q2 is connected to the A-phase control circuit, the source of the second switch tube Q2 is respectively connected to the A-phase control circuit and the anode of the diode D2, the drain of the second switch tube Q2 is respectively connected to one end of the second capacitor C2 and the other end of the winding A, and the other end of the second capacitor C2 is connected to one end of the winding B;

[0014] a first switch tube Q1, wherein the gate of the first switch tube Q1 is connected to the B-phase control circuit, the source of the first switch tube Q1 is connected to the B-phase control circuit and one end of the second capacitor C2 respectively, the drain of the first switch tube Q1 is connected to one end of the third capacitor C3 and the other end of the winding B, and the other end of the third capacitor C3 is connected to one end of the winding C;

[0015] A third switch tube Q3, the gate of the third switch tube Q3 is connected to the C-phase control circuit, the source of the third switch tube Q3 is respectively connected to one end of the third capacitor C3 and the C-phase control circuit, and the drain of the third switch tube Q3 is connected to the other end of the winding C.

[0016] Preferably, the energy extraction circuit further includes:

[0017] a fourth capacitor C4, one end of which is connected to the A-phase control circuit and the cathode of the diode D2 respectively;

[0018] a sixth capacitor C6, one end of the sixth capacitor C6 being connected to the B-phase control circuit and the other end of the fourth capacitor C4;

[0019] A seventh capacitor C7, one end of the seventh capacitor C7 is connected to the C-phase control circuit and the other end of the sixth capacitor C6, and the other end of the seventh capacitor C7 is respectively connected to the C-phase control circuit and the other end of the load resistor R2.

[0020] Preferably, in the energy extraction circuit, when the current direction detected by the A-phase control circuit flows from the winding A to the first capacitor C1 and then to the source of the second switch tube Q2 in a clockwise direction, the A-phase control circuit controls the second switch tube Q2 to be disconnected; when the current direction flows from the drain of the second switch tube Q2 to the first capacitor C1 and then to the winding A in a counterclockwise direction, the A-phase control circuit controls the second switch tube Q2 to be turned on.

[0021] Preferably, in the energy extraction circuit, when the current direction detected by the B-phase control circuit flows from the winding B to the second capacitor C2 and then to the source of the first switch tube Q1 in a clockwise direction, the B-phase control circuit controls the first switch tube Q1 to be disconnected; when the current direction flows from the drain of the first switch tube Q1 to the second capacitor C2 and then to the winding B in a counterclockwise direction, the B-phase control circuit controls the first switch tube Q1 to be turned on.

[0022] The present invention also provides a cable head discharge detection device, comprising:

[0023] A measuring circuit, wherein the measuring circuit is connected to an energy storage capacitor; the energy storage capacitor is used to supply power to the measuring circuit;

[0024] An ultrasonic sensor is communicatively connected to the measuring circuit, and is used to collect the sound wave signal generated when local discharge occurs at the cable head, and transmit the sound wave signal to the measuring circuit; the measuring circuit is used to pre-process the sound wave signal, and determine the intensity of the local discharge at the cable head based on the pre-processed sound wave signal. When the intensity of the local discharge at the cable head is greater than a preset value, an alarm is issued and the cable power supply is cut off.

[0025] Preferably, the ultrasonic sensors include at least 6 sensors, 3 in a group; the first group is on one side of the cable head, with an ultrasonic sensor installed longitudinally every 120°, surrounding the cable head; the second group is on the other side of the cable head, with an ultrasonic sensor installed longitudinally every 120°, surrounding the cable head.

[0026] Preferably, it also includes:

[0027] A cable temperature sensor is arranged on the cable head and connected to the measuring circuit, and is used to detect the temperature information of the cable head and upload the temperature information to the measuring circuit;

[0028] The ambient temperature sensor is connected to the measuring circuit and is used to detect the ambient temperature information around the cable and upload the ambient temperature information to the measuring circuit.

[0029] Preferably, the measurement circuit includes a control module; the control module includes:

[0030] An acoustic wave signal preprocessing unit, used for preprocessing the acoustic wave signal to generate a preprocessed acoustic wave signal;

[0031] A label setting unit, used for setting a corresponding label on the pre-processed acoustic wave signal to indicate the intensity of the partial discharge of the cable head;

[0032] The sample construction unit is used to convert the preprocessed sound wave signal into pixel values ​​using a conversion function in a left-to-right order, and put the converted pixel values ​​into a white frame of a preset size in a left-to-right order to form a sample; the conversion function is:

[0033]

[0034] In the formula, represents the pixel value after conversion, Indicates taking an integer. Represents the value of the i-th sampling point on the preprocessed sound wave signal, Represents the minimum value of the sampling point on the sound wave signal after preprocessing, Indicates the maximum value of the sampling points on the acoustic wave signal after preprocessing;

[0035] A training unit, used for inputting the sample into a deep learning network for training to form a cable head partial discharge intensity prediction model;

[0036] The alarm unit is used to detect the local discharge intensity of the target cable head using the cable head local discharge intensity prediction model. When the cable head local discharge intensity is greater than a preset value, an alarm is issued and the cable power supply is cut off.

[0037] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0038] The present invention provides a three-core cable leakage magnetic field energy harvesting circuit and a cable head discharge detection device. Compared with the prior art, the present invention can capture the sound wave signal generated by the local discharge of the cable head through an ultrasonic sensor. When the local discharge intensity exceeds a preset value, an alarm is automatically issued, which is convenient for the staff to take measures in time to reduce the risk of accidents. In addition, based on the energy harvesting magnetic core and the energy harvesting circuit, the present invention can provide a convenient and stable power supply for the measurement circuit. This energy harvesting method not only enhances the adaptability and flexibility of the system, but also ensures that the detection module can operate reliably for a long time without worrying about power outages or failures. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0040] Figure 1 A structural diagram of the energy extraction circuit provided by the present invention;

[0041] Figure 2 A cross-sectional view of the energy extraction core provided by the present invention;

[0042] Figure 3 A side view of the energy extraction core provided by the present invention;

[0043] Figure 4 A schematic diagram of a cable head discharge detection device provided by the present invention;

[0044] Figure 5 This is a cross-sectional view of the distribution of the cable head sensors provided by the present invention. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0047] The terms "first", "second", "third" and "fourth" in the specification and claims of the present application and the drawings are used to distinguish different objects rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a series of steps, processes, methods, etc. are not limited to the listed steps, but may optionally include steps that are not listed, or may optionally include other step elements inherent to these processes, methods, products or devices.

[0048] In order to make the above-mentioned objectives, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] See also Figure 1-3 A three-core cable leakage magnetic field energy harvesting circuit includes: an energy harvesting magnetic core, an energy harvesting circuit, an energy harvesting magnetic core and an energy storage capacitor.

[0050] The energy-harvesting magnetic core is installed on the outside of the cable and is used to obtain energy from the changing spatial magnetic field generated around the cable and convert it into alternating current;

[0051] The energy-taking circuit is connected to the energy-taking magnetic core and the energy storage capacitor respectively, and is used to charge the energy storage capacitor after rectifying the alternating current; the energy storage capacitor is used for power supply.

[0052] Furthermore, the energy extraction magnetic core includes:

[0053] The annular energy-taking core is composed of three identical cores, each core covers 120°, each core has grooves at both ends, and receiving grooves are formed between adjacent grooves. The single-phase induction coils of the three-phase induction coils are respectively wound on the grooves at both ends of each core to form winding A, winding B and winding C. A coil tangential to winding A, winding B and winding C is also separately wound between each receiving groove to form winding X, winding Y and winding Z.

[0054] See also Figure 2 , is a cross-sectional view of the annular energy-taking core. Winding A, winding B and winding C are based on the leakage magnetic field of the turnkey cable to take energy. Winding X, winding Y and winding Z are zero-sequence current energy-taking. Each core has two windings, and the two windings have their own energy-taking methods, which can obtain more energy. The structure consists of three identical cores, each of which covers 120°, and the three cores are combined into a complete energy-taking core. The single-phase induction coils of the three-phase induction coil are respectively wound in the receiving groove to form a winding. Each single-phase induction coil is located in the receiving groove on both sides of the corresponding boss. In addition, each winding has a set of windings that cross it, that is, the energy-taking core has a total of three pairs of windings. The configuration of the three-phase cable and the three-petal energy-taking coil allows the coil on each phase to sense the magnetic field generated by the current of that phase. This design can evenly extract energy from each phase cable while avoiding additional interference caused by current asymmetry or zero-sequence current. When there is zero-sequence current, another winding can also be used to take energy. The three-petal coil design usually ensures stability and balance during the induction process, so that the energy extraction in each phase is symmetrical. The core design reduces the magnetic resistance, that is, by increasing the magnetic permeability, so that more magnetic flux passes through the coil area. Therefore, the structure of the energy extraction core can reduce the magnetic resistance, increase the magnetic flux, and thus improve the efficiency of power conversion.

[0055] The structural design of the energy harvesting core can effectively improve the energy collection efficiency by integrating high magnetic permeability materials, optimizing magnetic circuits, reducing losses and stabilizing magnetic flux. These physical laws work together to ensure the stability and efficiency of the energy harvesting system.

[0056] See also Figure 1 The circuits of winding X, winding Y and winding Z in the present invention are the same as those of winding B and winding C, so they are omitted. The energy extraction circuit in the embodiment of the present invention includes:

[0057] A first capacitor C1, one end of the first capacitor C1 is connected to one end of the winding A, the other end of the first capacitor C1 is connected to the anode of the diode D2, and the cathode of the diode D2 is connected to one end of the load resistor R2;

[0058] a second switch tube Q2, wherein the gate of the second switch tube Q2 is connected to the A-phase control circuit, the source of the second switch tube Q2 is respectively connected to the A-phase control circuit and the anode of the diode D2, the drain of the second switch tube Q2 is respectively connected to one end of the second capacitor C2 and the other end of the winding A, and the other end of the second capacitor C2 is connected to one end of the winding B;

[0059] a first switch tube Q1, wherein the gate of the first switch tube Q1 is connected to the B-phase control circuit, the source of the first switch tube Q1 is connected to the B-phase control circuit and one end of the second capacitor C2 respectively, the drain of the first switch tube Q1 is connected to one end of the third capacitor C3 and the other end of the winding B, and the other end of the third capacitor C3 is connected to one end of the winding C;

[0060] a third switch tube Q3, wherein the gate of the third switch tube Q3 is connected to the C-phase control circuit, the source of the third switch tube Q3 is respectively connected to one end of the third capacitor C3 and the C-phase control circuit, and the drain of the third switch tube Q3 is connected to the other end of the winding C;

[0061] a fourth capacitor C4, one end of which is connected to the A-phase control circuit and the cathode of the diode D2 respectively;

[0062] a sixth capacitor C6, one end of the sixth capacitor C6 being connected to the B-phase control circuit and the other end of the fourth capacitor C4;

[0063] A seventh capacitor C7, one end of the seventh capacitor C7 is connected to the C-phase control circuit and the other end of the sixth capacitor C6, and the other end of the seventh capacitor C7 is respectively connected to the C-phase control circuit and the other end of the load resistor R2.

[0064] The annular energy-taking core of the present invention is composed of three identical cores, each of which has two windings, and the three cores have a total of six windings. These six windings receive input signals from six different AC power supplies respectively. These signals are first coupled through capacitors C1, C2, C3, etc. These capacitors are mainly used for direct isolation and filtering, and the input AC signals are coupled to the subsequent circuits. First, when the capacitor C4 is first charged to a voltage that satisfies the startup of the Q2 control circuit, a supplies power to the control circuit, the control circuit starts working, and the current is monitored by b, and c controls the conduction of the MOSFET. Each input signal corresponds to a MOSFET: Q1 corresponds to group B, Q2 corresponds to group A, and Q3 corresponds to group C. These capacitors smooth voltage fluctuations by controlling the charging and discharging process in each cycle, and provide a stable power supply for the subsequent circuit. After passing through the MOSFET and the energy storage capacitor, the current is rectified by the diode D2. The rectified voltage is output through the load resistor R2 and becomes the final output voltage of the circuit. The energy storage capacitor not only stores energy, but also plays a filtering role, further reducing the voltage fluctuation after rectification. When the direction of the current signal changes, the control circuit can respond quickly, and maintain the stability of the circuit output by adjusting the on or off of the MOSFET. For winding A, when the current direction detected by the A-phase control circuit flows from winding A to the first capacitor C1 and then to the source of the second switch tube Q2 in a clockwise direction, the A-phase control circuit controls the second switch tube Q2 to be turned off; when the current direction is the drain of the second switch tube Q2 to the first capacitor C1 and then to winding A in a counterclockwise flow, the A-phase control circuit controls the second switch tube Q2 to be turned on. For winding B, when the current direction detected by the B-phase control circuit flows from winding B to the second capacitor C2 and then to the source of the first switch tube Q1 in a clockwise direction, the B-phase control circuit controls the first switch tube Q1 to be turned off; when the current direction is the drain of the first switch tube Q1 to the second capacitor C2 and then to winding B in a counterclockwise flow, the B-phase control circuit controls the first switch tube Q1 to be turned on, and the same applies to other windings. The on and off of the MOSFET can be controlled according to the direction of the current. Through this control method, the MOSFET is turned on only when the current flow direction is beneficial to the circuit, which can effectively avoid unnecessary reverse current flow, thereby reducing power loss, especially the energy dissipation that may be caused by reverse current. Physically, the loss of MOSFET mainly comes from conduction loss and switching loss. By controlling its working state, these two types of losses can be optimized. Controlling the conduction and shutdown of MOSFET according to the current direction can reduce the loss of reverse current, optimize energy conversion efficiency, reduce voltage spikes and reduce electromagnetic interference. Usually, a body diode is integrated in the MOSFET, which will automatically turn on when the reverse current flows in the MOSFET. The conduction voltage of the body diode is relatively high, about 0.7V, so there is a large conduction loss.By controlling the MOSFET in the direction of the current, the conduction of the body diode can be avoided, and the current can be conducted directly through the MOSFET, thereby reducing the power loss during reverse current. According to the characteristics of the Schottky diode, the reverse recovery time and reverse recovery current will cause additional power loss and electromagnetic interference. These problems can be reduced by avoiding diode conduction through appropriate control strategies.

[0065] If the MOSFET is turned on only according to the current direction, it can be seen that when the current is forward, the MOSFET is turned on normally and the output voltage is stable; when the current is reverse, the MOSFET is turned off to avoid reverse current loss. In the traditional case where the current direction is not controlled, the reverse current will be turned on through the body diode, resulting in higher power consumption and possible fluctuations in the output voltage. Through current direction control, the output current waveform is smoother, noise and switching interference are significantly reduced, and the voltage waveform is more stable.

[0066] See also Figure 3 , Figure 3 The side view of the energy extraction core on the cable has a certain length to ensure that its energy extraction allows the measurement module to work within the specified time. As shown in the figure, the winding XY / Z tangent to the winding A (B / C) can also be seen.

[0067] Ultrasonic testing is an effective means of detecting partial discharge. Partial discharge generates high-frequency sound wave signals, which can be captured and analyzed by ultrasonic sensors to determine the location and intensity of the discharge. Therefore, ultrasonic detection technology for partial discharge at cable heads has become one of the important means to ensure the reliability of cable operation. However, since cable heads are usually buried underground, the power supply of ultrasonic detection devices for partial discharge at cable heads is a problem.

[0068] At present, the power supply of monitoring equipment usually relies on technologies such as solar energy, CT energy extraction, and 220V AC to solve the power supply problem of online monitoring equipment of transmission lines. However, these methods have their own shortcomings. When the package cable transmits current, it will generate a magnetic field. When the current passes through the wire, it will generate a magnetic flux around the wire, thereby forming a magnetic field. Therefore, the power supply problem of monitoring equipment can be solved by extracting energy through the leakage magnetic field of the package cable.

[0069] The energy-harvesting circuit of the present invention proposes to use the leakage magnetic field of the turnkey cable to harvest energy to power the monitoring equipment at the cable head, and uses the magnetic field generated by the cable itself when transmitting current as the energy source, eliminating the trouble of laying a separate power line for the monitoring equipment, reducing the installation cost and complexity, reducing the interfaces and lines of the cable system exposed to the outside world, and improving the concealment and safety of the system. In some special environments, such as underground tunnels, underwater pipelines and other places where it is difficult to lay power lines, the use of leakage magnetic field harvesting enhances the adaptability and flexibility of the system; the monitoring circuit proposes to use three ultrasonic sensors to surround the cable head for a week, so as to achieve the purpose of more accurate detection of the local discharge position of the cable head.

[0070] like Figure 4 As shown, the present invention also provides a cable head discharge detection device, comprising:

[0071] A measuring circuit, wherein the measuring circuit is connected to an energy storage capacitor; the energy storage capacitor is used to supply power to the measuring circuit;

[0072] An ultrasonic sensor is communicatively connected to the measuring circuit, and is used to collect the sound wave signal generated when local discharge occurs at the cable head, and transmit the sound wave signal to the measuring circuit; the measuring circuit is used to pre-process the sound wave signal, and determine the intensity of the local discharge at the cable head based on the pre-processed sound wave signal. When the intensity of the local discharge at the cable head is greater than a preset value, an alarm is issued and the cable power supply is cut off.

[0073] The ultrasonic sensors include at least 6, 3 in a group; the first group is on one side of the cable head, with one ultrasonic sensor installed longitudinally every 120°, surrounding the cable head; the second group is on the other side of the cable head, with one ultrasonic sensor installed longitudinally every 120°, surrounding the cable head.

[0074] For further information, see Figure 5On the surface of the cable head, an AE-R ultrasonic sensor is installed longitudinally every 120°. A total of three sensors are installed, surrounding the cable head. The length of the cable head is about 1.5m. Due to the uncertainty of the partial discharge position and the rapid attenuation of the ultrasonic signal, a group of sensors needs to be placed on the left and right, 3 in a group, and the distance between the two groups of sensors is 40-50cm. The working principle of the energy-taking circuit: an energy-taking iron core is installed on the outside of the three-core cable, and the three-phase induction coil is distributed along the circumference of the cable. The direction of the three-phase induction coil is parallel to the axial direction of the three-core cable. When a three-phase alternating current is passed through the three-core cable, the three-phase induction coil can extract energy from it. In practical applications, the three-phase industrial frequency alternating current flows through the three-core cable, which will generate a constantly changing spatial magnetic field around the cable. The energy-taking magnetic core is installed on the outside of the three-core cable, which can effectively gather these spatial magnetic fields. The three-phase induction coil is wound in the groove of the magnetic core. As the alternating magnetic field passes through the coil, the three-phase induction coil can obtain energy from the spatial magnetic field around the cable by using the principle of electromagnetic induction, and convert it into electrical energy, and output a three-phase alternating current induced voltage. Working principle of the measurement circuit: When partial discharge occurs at the cable head, the ultrasonic sensor will detect a weak high-frequency signal, which will be amplified and transmitted to the measurement circuit, which will process the signal into an analog signal of 0-5V and output it. The signal enters the control module for A / D conversion to determine the intensity of the partial discharge. The two temperature sensors detect the temperature during partial discharge and the ambient temperature respectively, and compare them to assist in monitoring whether partial discharge occurs. Finally, all data are output to the fiber optic transceiver through the serial port, and the fiber optic transceiver transmits the data to the optical trunk through the fiber pigtail. The monitoring circuit is powered by the energy storage capacitor, and the energy extraction circuit charges the energy storage capacitor. Figure 4 The 2×3 in the figure indicates that the energy taking core has 6 windings in total, two of which are in pairs, for a total of three pairs, and the 1×6 indicates 6 AE-R ultrasonic sensors.

[0075] It should be noted that the measurement circuit includes a control module; the control module includes:

[0076] An acoustic wave signal preprocessing unit, used for preprocessing the acoustic wave signal to generate a preprocessed acoustic wave signal;

[0077] A label setting unit, used for setting a corresponding label on the pre-processed acoustic wave signal to indicate the intensity of the partial discharge of the cable head;

[0078] A sample construction unit, used for encoding the preprocessed sound wave signal to form a sample;

[0079] The sample construction unit includes:

[0080] The preprocessed sound wave signal is converted into pixel values ​​using a conversion function in a left-to-right order, and the converted pixel values ​​are placed into a white frame of a preset size in a left-to-right and top-to-bottom order to form a sample;

[0081] Wherein, the conversion function is:

[0082]

[0083] In the formula, represents the pixel value after conversion, Indicates taking an integer. Represents the value of the i-th sampling point on the preprocessed sound wave signal, Represents the minimum value of the sampling point on the sound wave signal after preprocessing, Indicates the maximum value of the sampling points on the acoustic signal after preprocessing.

[0084] The processing method of the present invention converts the sound wave signal into an image sample using a conversion function, which can convert the time-frequency data into a pixel matrix with image properties, thereby enhancing the invisible information in the original signal, thereby helping the deep learning network to better learn features and reduce the risk of overfitting.

[0085] A training unit, used for inputting the sample into a deep learning network for training to form a cable head partial discharge intensity prediction model;

[0086] In an embodiment of the present invention, the present invention can use a cross entropy loss function to quantify the training effect in a deep learning network. When the loss value is less than a preset value, the training is completed to obtain a cable head partial discharge intensity prediction model.

[0087] The alarm unit is used to detect the local discharge intensity of the target cable head using the cable head local discharge intensity prediction model. When the cable head local discharge intensity is greater than a preset value, an alarm is issued and the power supply is cut off.

[0088] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0089] 1. Split core structure: The present invention adopts a split energy-taking core structure, which is composed of three identical cores, each of which covers 120°, and the three cores are combined into a complete energy-taking core. This design not only improves environmental adaptability and work efficiency, but also greatly facilitates subsequent maintenance work. By adjusting the number of parts and the specific design of the split structure, the energy-taking device can be made more flexible and changeable to adapt to more complex environments and scenarios, further enhancing its versatility and practicality. In actual applications, the connection method between the split structures can adopt a card-mounted connection or other detachable connection method that can ensure a stable and firm connection.

[0090] 2. Locating partial discharge: Three ultrasonic probes are used in the detection circuit to surround the cable head, and a group of probes are arranged on the left and right sides of the cable head. By analyzing the discharge intensity detected by each probe, the accuracy of the detection can be improved.

[0091] 3. Energy-saving design: When the energy acquisition module charges the capacitor to the working voltage, the control module starts to work; when the voltage of the supercapacitor is insufficient, the control module enters a dormant state and waits for the capacitor to be charged to the working voltage again before resuming work. This design effectively saves energy and improves the working efficiency of the device.

[0092] 4. Leakage magnetic field energy harvesting: The leakage magnetic field energy harvesting technology based on the turnkey cable can provide a convenient and stable power supply for the detection module at the cable terminal. This energy harvesting method not only enhances the adaptability and flexibility of the system, but also ensures that the detection module can operate reliably for a long time without worrying about power interruption or failure.

[0093] 5. Control circuit: The control circuit can accurately control the on and off time of the switch device, so as to achieve effective rectification of the AC power supply. Through reasonable control strategy and accurate control of the working state of each switch, the output DC voltage and current waveform can be optimized and the switching loss and energy loss in the circuit can be reduced, thereby improving the energy efficiency ratio of the overall circuit. This is especially important for systems that require efficient energy conversion.

[0094] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the method disclosed in the embodiment, since it corresponds to the device disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the device part description.

[0095] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A three-core cable leakage magnetic field energy harvesting circuit, characterized in that: include: The energy-harvesting magnetic core is installed on the outside of the cable and is used to obtain energy from the changing spatial magnetic field generated around the cable and convert it into alternating current; The energy-taking magnetic core comprises: The annular energy-taking core is composed of three identical cores, each core covers 120°, each core has grooves at both ends, and a receiving groove is formed between adjacent grooves. Each single-phase induction coil of the three-phase induction coil is respectively wound on the grooves at both ends of each core to form winding A, winding B and winding C. A coil tangential to winding A, winding B and winding C is also separately wound between each receiving groove to form winding X, winding Y and winding Z; An energy-taking circuit is connected to the energy-taking magnetic core and the energy storage capacitor respectively, and is used to charge the energy storage capacitor after rectifying the alternating current; the energy storage capacitor is used for power supply; The energy taking circuit comprises: a first capacitor (C1), one end of the first capacitor (C1) being connected to one end of the winding (A), the other end of the first capacitor (C1) being connected to an anode of a diode (D2), and a cathode of the diode (D2) being connected to one end of a load resistor (R2); a second switch tube (Q2), wherein the gate of the second switch tube (Q2) is connected to the A-phase control circuit, the source of the second switch tube (Q2) is respectively connected to the A-phase control circuit and the anode of the diode (D2), the drain of the second switch tube (Q2) is respectively connected to one end of the second capacitor (C2) and the other end of the winding (A), and the other end of the second capacitor (C2) is connected to one end of the winding (B); a first switch tube (Q1), wherein a gate of the first switch tube (Q1) is connected to a B-phase control circuit, a source of the first switch tube (Q1) is respectively connected to the B-phase control circuit and one end of the second capacitor (C2), a drain of the first switch tube (Q1) is connected to one end of a third capacitor (C3) and the other end of a winding (B), and the other end of the third capacitor (C3) is connected to one end of the winding (C); a third switch tube (Q3), wherein a gate of the third switch tube (Q3) is connected to a C-phase control circuit, a source of the third switch tube (Q3) is respectively connected to one end of a third capacitor (C3) and the C-phase control circuit, and a drain of the third switch tube (Q3) is connected to the other end of the winding (C); The energy taking circuit further includes: a fourth capacitor (C4), one end of which is connected to the A-phase control circuit and the cathode of the diode (D2) respectively; a sixth capacitor (C6), one end of the sixth capacitor (C6) being connected to the B-phase control circuit and the other end of the fourth capacitor (C4); A seventh capacitor (C7), one end of the seventh capacitor (C7) is connected to the C-phase control circuit and the other end of the sixth capacitor (C6), and the other end of the seventh capacitor (C7) is respectively connected to the C-phase control circuit and the other end of the load resistor (R2).

2. A three-core cable leakage magnetic field energy harvesting circuit as claimed in claim 1, characterized in that: In the energy extraction circuit, when the current direction detected by the A-phase control circuit flows from the winding (A) to the first capacitor (C1) and then to the source of the second switch tube (Q2) in a clockwise direction, the A-phase control circuit controls the second switch tube (Q2) to be disconnected; when the current direction flows from the drain of the second switch tube (Q2) to the first capacitor (C1) and then to the winding (A) in a counterclockwise direction, the A-phase control circuit controls the second switch tube (Q2) to be turned on.

3. A three-core cable leakage magnetic field energy harvesting circuit as claimed in claim 2, characterized in that: In the energy extraction circuit, when the current direction detected by the B-phase control circuit flows from the winding (B) to the second capacitor (C2) and then to the source of the first switch tube (Q1) in a clockwise direction, the B-phase control circuit controls the first switch tube (Q1) to be disconnected; when the current direction flows from the drain of the first switch tube (Q1) to the second capacitor (C2) and then to the winding (B) in a counterclockwise direction, the B-phase control circuit controls the first switch tube (Q1) to be turned on.

4. A cable head discharge detection device, the device is based on a three-core cable leakage magnetic field energy harvesting circuit according to any one of claims 1 to 3, comprising: A measuring circuit, wherein the measuring circuit is connected to the energy storage capacitor; The energy storage capacitor is used to supply power to the measurement circuit; An ultrasonic sensor is communicatively connected with the measuring circuit, and is used to collect the acoustic wave signal generated when the cable head has partial discharge, and transmit the acoustic wave signal to the measuring circuit; the measuring circuit is used to pre-process the acoustic wave signal, and determine the intensity of the partial discharge of the cable head based on the pre-processed acoustic wave signal, and when the intensity of the partial discharge of the cable head is greater than a preset value, an alarm is issued, and the power supply of the cable is cut off; The ultrasonic sensors include at least 6, 3 in a group; the first group is on one side of the cable head, with one ultrasonic sensor installed longitudinally every 120°, surrounding the cable head; The second group is on the other side of the cable head, with an ultrasonic sensor installed longitudinally every 120°, surrounding the cable head.

5. A cable head discharge detection device as claimed in claim 4, characterized in that: Also includes: A cable temperature sensor is arranged on the cable head and connected to the measuring circuit, and is used to detect the temperature information of the cable head and upload the temperature information to the measuring circuit; The ambient temperature sensor is connected to the measuring circuit and is used to detect the ambient temperature information around the cable and upload the ambient temperature information to the measuring circuit.

6. A cable head discharge detection device as claimed in claim 5, characterized in that: The measuring circuit includes a control module; the control module includes: An acoustic wave signal preprocessing unit, used for preprocessing the acoustic wave signal to generate a preprocessed acoustic wave signal; A label setting unit, used for setting a corresponding label on the pre-processed acoustic wave signal to indicate the intensity of the partial discharge of the cable head; The sample construction unit is used to convert the preprocessed sound wave signal into pixel values ​​using a conversion function in a left-to-right order, and put the converted pixel values ​​into a white frame of a preset size in a left-to-right order to form a sample; the conversion function is: In the formula, P(m,n) represents the converted pixel value, round represents an integer, and x i represents the value of the i-th sampling point on the preprocessed sound wave signal, x min Represents the minimum value of the sampling point on the sound wave signal after preprocessing, x max Indicates the maximum value of the sampling points on the acoustic wave signal after preprocessing; A training unit, used for inputting the sample into a deep learning network for training to form a cable head partial discharge intensity prediction model; The alarm unit is used to detect the local discharge intensity of the target cable head using the cable head local discharge intensity prediction model, and to issue an alarm when the cable head local discharge intensity is greater than a preset value.

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