Power cable partial discharge fault simulation detection device

Abstract

The application discloses a power cable partial discharge fault simulation detection device. The application comprises a discharge cylinder and two shielding aluminum cylinders on the two sides. The discharge cylinder is in a sealed structure, and two power cables pass through the end covers of the two shielding aluminum cylinders, are connected with the conductive copper rods in the discharge cylinder and are in conduction. A discharge model and a high-voltage electrode are arranged in the discharge cylinder. The discharge model comprises at least two of a sharp-end discharge model, a floating discharge model and an air gap discharge model. Each discharge model is connected with a stepping motor through a metal mounting seat, and the stepping motor controls the corresponding discharge model to move along the axial direction of the discharge cylinder. The high-voltage electrode is a metal disc, the conductive copper rod vertically passes through the center of the high-voltage electrode, is fixedly connected with the high-voltage electrode and is in conduction. The discharge model is in position correspondence with the high-voltage electrode. The simulated various faults of the power cable are equivalent to the actual power cable faults, the device is controlled externally, and the operation is convenient, accurate and efficient.

Description

Technical Field

[0001] This invention belongs to the field of power equipment technology, specifically relating to a power cable partial discharge fault simulation and detection device. Background Technology

[0002] In the power industry, power cables are used for transmitting and distributing electrical energy due to their advantages such as small footprint, high reliability, large distributed capacitance, and low maintenance workload, making them an indispensable component of the power grid system. With the continuous expansion of power cable usage, the distribution of power cable laying paths is wide, and operating conditions are complex. Power cable line faults are frequent due to external force damage, insulation aging, and other problems at cable terminals, intermediate joints, and the cable itself, threatening the safe operation of the power grid. Therefore, it is essential to conduct fault simulation tests on power cable operation to promptly eliminate major safety hazards and defects under operating conditions. Existing power cable fault simulation methods include using equivalent capacitance to simulate cable discharge faults, and using coaxial cables to simulate the effects of typical discharges and cable length. However, existing methods cannot realistically reflect the effects of different locations and discharge types at cable terminals, the cable itself, and intermediate joints in actual operation, and require frequent changes to the discharge model, resulting in poor simulation effects.

[0003] Invention patent No. 201410113121.7 discloses a method and simulation detection platform for simulating partial discharge in cross-linked polyethylene (XLPE) insulated cables. First, a spectral library of partial discharge patterns for XLPE cables is established. Second, typical defects of different types in XLPE insulated cables are artificially created. Finally, the type and severity of defects are determined based on the characteristics of the output signal from the simulation detection platform, thus establishing a one-to-one correspondence between defect types and the effectiveness of partial discharge detection technology. This simulation platform can simulate five typical cable faults. Patent application No. 201911349716.1 discloses a partial discharge detection device for high-voltage cables. The device includes a partial discharge sensor, a trigger module, a multi-channel acquisition module, a power supply module, and a main control module. The partial discharge sensor is communicatively connected to the trigger module, the trigger module is communicatively connected to the main control module, the main control module is communicatively connected to the multi-channel acquisition module, and the multi-channel acquisition module is communicatively connected to the partial discharge sensor. The power supply module supplies power to all the aforementioned modules. The partial discharge sensor detects partial discharge signals in the high-voltage cable. After the trigger module determines that the detected discharge signal meets certain conditions, it transmits the discharge signal to the main control module for partial discharge diagnosis, defect identification, fault location, and comprehensive diagnostic processing. Utility model patent No. 202022514797.0 discloses a multifunctional cable main insulation fault and partial discharge simulation device, including a housing, an insulated cable inside the housing, a fault simulator, a high-voltage partial discharge capacitor and partial discharge simulation source outside the housing, test terminals, a grounding terminal, a partial discharge simulation connection terminal, and a fault selection switch on the housing shell. The test terminals are used to connect to the test equipment, the grounding terminals are used for grounding protection, the partial discharge simulation connection terminals are used to connect to the high voltage partial discharge capacitor, and the rotary switch is used to simulate open circuit and grounding faults in insulated cables, select the location of the fault, and select the type of fault simulation. Summary of the Invention

[0004] The purpose of this invention is to provide a power cable partial discharge fault simulation and detection device.

[0005] The present invention includes a discharge cylinder and a shielding aluminum cylinder, with the two shielding aluminum cylinders fixedly connected to both sides of the discharge cylinder.

[0006] The discharge cylinder is a sealed structure, filled with sulfur hexafluoride gas at 0.1–1.2 MPa. The discharge cylinder includes a cylinder body and flanges on both sides of the cylinder body. The cylinder body has a sulfur hexafluoride gas filling port, and the flanges have control box wiring ports. Two power cables pass through the end caps of the two shielded aluminum cylinders, respectively, and connect to the conductive copper rods inside the discharge cylinder. A control box located outside the device is connected to the control box wiring port.

[0007] Two high-voltage bushings pass seamlessly through the flanges on both sides of the discharge cylinder, and a core rod is installed inside each bushing. A conductive copper rod, positioned at the axial center of the discharge cylinder, has its two ends extending into one end of each of the two high-voltage bushings, and one end of each of the two power cables extends into the other end of each bushing. The two ends of the conductive copper rod are connected to and conduct through one end of the core rod inside each of the two high-voltage bushings, and the other ends of the core rods are connected to and conduct through the core wires of the two power cables. The two power cables are connected through the conductive copper rod and the two core rods. A discharge model and high-voltage electrodes are installed inside the discharge cylinder.

[0008] The discharge model is multiple, including at least two of the following: tip discharge model, suspension discharge model and air gap discharge model. Each discharge model is connected to the corresponding stepper motor through a metal mounting base and is connected to the control box wiring port. The stepper motor is fixedly mounted on the inner wall of the flange on one side of the discharge cylinder. The stepper motor controls the corresponding discharge model to move along the axial direction of the discharge cylinder.

[0009] The high-voltage electrode is a metal disk, which is set perpendicular to the axial direction of the discharge cylinder. The high-voltage electrode is fixedly connected to the inner wall of the flange on the other side of the discharge cylinder by an insulating rod. The conductive copper rod passes vertically through the center of the high-voltage electrode, is fixedly connected to the high-voltage electrode and conducts electricity.

[0010] This invention addresses the problems existing in current power cable fault simulation. Based on the actual power cable structure and a power cable partial discharge fault simulation structure, it externally controls the generation and magnitude of typical discharge faults such as those at the cable tip, air gap, and suspension via an external control box. The power cable uses the actual voltage level as required. The connection structure between the power cable partial discharge fault simulation structure and the power cable is completely identical and seamlessly connected, forming a power cable fault simulation device. This device can accurately simulate partial discharge defects caused by power cable terminal joints, intermediate joints, and the cable body itself. It can simulate single or complex partial discharge signals and control the initiation voltage, extinction voltage, and discharge intensity. While the control of the stepper motor and the acquisition and analysis of partial discharge signals via the control box are mature existing technologies, the inventive aspect of this invention lies in providing the structural design of this partial discharge fault simulation and detection device.

[0011] This invention simulates various power cable faults that are completely equivalent to actual power cable faults. The external control method can accurately control the generation and discharge magnitude of typical discharge faults such as tip, air gap, and suspension faults, while avoiding the cumbersome process of changing fault models during fault simulation. It is simple, convenient, accurate, and efficient to operate. This invention can simulate the characteristics of different fault types and the impact of discharge intensity on the insulation performance of power cables. Through these characteristics, a large amount of power cable fault characteristic data can be obtained, providing more accurate experimental data for the detection and diagnostic analysis of power cable safe operating status. It also provides a test platform for the detection of partial discharge in power cables using pulse current, oscillating waves, and high frequencies. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0013] Figure 2 This is a schematic diagram of the connection structure between the power cable and the conductive copper rod in this invention;

[0014] Figure 3 This is a schematic diagram of the internal structure of the discharge cylinder in this invention;

[0015] Figure 4 This is a schematic diagram of the tip discharge model structure in this invention;

[0016] Figure 5 This is a schematic diagram of the suspended discharge model structure in this invention;

[0017] Figure 6 This is a schematic diagram of the air gap discharge model structure in this invention. Detailed Implementation

[0018] The invention will now be further described with reference to the accompanying drawings.

[0019] like Figure 1 As shown, a power cable partial discharge fault simulation detection device includes a discharge cylinder 1 fixedly mounted on a trolley, with two shielded aluminum cylinders 2 fixedly connected to both sides of the discharge cylinder 1. The discharge cylinder 1 includes a cylinder body 101 and flanges 102 on both sides of the cylinder body. A sulfur hexafluoride gas filling port 103 is provided on the cylinder body 101, and a control box wiring port 104 is provided on the flanges 102. The sealed discharge cylinder 1 is filled with 1.0 MPa of sulfur hexafluoride gas. Two power cables 3 pass through the end caps of the two shielded aluminum cylinders 2 respectively, and are connected to and conduct electricity with the conductive copper rods inside the discharge cylinder 1. A control box located outside the device is connected to the control box wiring port.

[0020] The connection structure between the power cable and the conductive copper rod is as follows: Figure 2As shown: Two high-voltage bushings 4 pass seamlessly through the flanges 102 on both sides of the discharge cylinder. A core rod 5 is installed inside each high-voltage bushing 4. Two ends of a conductive copper rod 6, positioned at the axial center inside the discharge cylinder 1, extend into one end of each of the two high-voltage bushings 4. One end of each of the two power cables 3 extends into the other end of each of the two high-voltage bushings 4. Both ends of the conductive copper rod 6 are connected to and conduct through one end of the core rod 5 inside each of the two high-voltage bushings. The other ends of the core rod 5 inside each of the two high-voltage bushings are connected to and conduct through the core wires of the two power cables. The two power cables are connected through the conductive copper rod 6 and the two core rods 5.

[0021] like Figure 3 As shown, a discharge model and a high-voltage electrode are installed inside the discharge cylinder 1. There are multiple discharge models, including at least two of the following: a tip discharge model 7, a suspended discharge model 8, and an air gap discharge model 9. This embodiment uses three discharge models. Each discharge model is connected to a corresponding stepper motor 10 via a metal mounting base and is also connected to the control box wiring port. The stepper motor 10 is fixedly mounted on the inner wall of the flange 102 on one side of the discharge cylinder. The three stepper motors control the three discharge models to move axially along the discharge cylinder.

[0022] The high-voltage electrode 11 is a metal disk, arranged perpendicular to the axial direction of the discharge cylinder. The high-voltage electrode 11 is fixedly connected to the inner wall of the flange on the other side of the discharge cylinder by an insulating rod 12. A conductive copper rod 6 passes vertically through the center of the high-voltage electrode 11, is fixedly connected to the high-voltage electrode 11, and is conductive.

[0023] like Figure 4 As shown, the tip discharge model 7 includes a front cylinder 71 and a rear cylinder 72 fixedly connected. The front cylinder 71 and the rear cylinder 72, made of insulating material, form a discharge cavity, and a metal needle 73 is disposed inside the discharge cavity. A protrusion is provided on the end face of the front cylinder 71, through which a first conductive rod 74 passes and is fixedly disposed on the end face of the front cylinder 71. One end of the first conductive rod 74 is fixedly connected to and conducts electricity with a metal sheet 75 inside the discharge cavity, while the other end extends out of the protrusion on the end face of the front cylinder 71. Part of the first conductive rod 74 and one end of the first metal adjusting member 77 are disposed inside a first metal sleeve 76. The first metal sleeve 76 is fixedly connected to the protrusion on the end face of the front cylinder, and a first spring 78 is disposed between the first metal adjusting member 77 and the first conductive rod 74. The first metal sleeve 76, the first metal adjusting member 77, and the first conductive rod 74 are coaxially arranged, and the first metal adjusting member 77 maintains electrical contact with the first conductive rod 74 while moving back and forth along this axis. A first metal mounting base 79 is fixedly installed on the bottom surface of the rear cylinder 72. The root of the metal needle 73 is fixedly connected to and conducts through the first metal mounting base 79, and the tip faces the metal plate 75. During operation, the stepper motor drives the tip discharge model 7 to move forward as a whole. When the first metal adjusting component 77 contacts the high-voltage electrode plate, a tip discharge is generated. During the contact between the tip discharge model 7 and the high-voltage electrode plate, the first spring 78 provides pressure relief to protect the model.

[0024] like Figure 5 As shown, the levitation discharge model 8 includes an insulating cylinder 81 and an insulating base 82. The insulating base 82 is fixedly connected to the open end of the insulating cylinder 81. The insulating cylinder 81 and the insulating base 82 enclose a discharge cavity, and a metal simulation element 83 is disposed inside the discharge cavity. The metal simulation element 83 is fixedly disposed on the insulating base 82. A protrusion is provided on the end face of the insulating cylinder 81, through which a second conductive rod 84 passes. One end of the second conductive rod 84 extends into the discharge cavity, and the other end extends out of the end face protrusion of the insulating cylinder 81. The metal simulation element 83 corresponds to the position of the second conductive rod 84, and there is a gap between the metal simulation element 83 and the second conductive rod 84. Part of the second conductive rod 84 and one end of the second metal adjusting element 85 are disposed inside a second metal sleeve 86. The second metal sleeve 86 is fixedly connected to the end face protrusion of the insulating cylinder, and a second spring 87 is disposed between the second metal adjusting element 85 and the second conductive rod 84. The second metal sleeve 86, the second metal adjusting member 85, and the second conductive rod 84 are coaxially arranged. The second metal adjusting member 85 maintains electrical contact with the second conductive rod 84 throughout its back-and-forth movement along this axis. The second metal mounting base 88 is fixedly mounted on the insulating base 82, and is insulated from the metal simulation component 83 by the insulating base 82. During operation, the stepper motor drives the entire levitation discharge model 8 forward. When the second metal adjusting member 85 contacts the high-voltage electrode plate, a levitation discharge is generated. During the contact between the levitation discharge model 8 and the high-voltage electrode plate, the second spring 87 provides cushioning, protecting the model.

[0025] like Figure 6 As shown, the air gap discharge model 9 includes an insulating block 91, a metal rod 92, and a third conductive rod 93. The insulating block 91 is made of solid polyester material with dispersed air bubbles inside. The metal rod 92 and the third conductive rod 93 extend into the insulating block 91 from both sides, with the heads of the metal rod 92 and the third conductive rod 93 facing each other and insulated by the insulating block 91. Part of the third conductive rod 93 and one end of the third metal adjusting member 94 are disposed in the third metal sleeve 95, which is fixedly connected to the insulating block 91. A third spring 96 is disposed between the third metal adjusting member 94 and the third conductive rod 93. The third metal sleeve 95, the third metal adjusting member 94, and the third conductive rod 93 are coaxially arranged. The third metal adjusting member 94 maintains a conductive state with the third conductive rod 93 while moving back and forth along the axis. The third metal mounting base 97 is fixedly disposed on the insulating block 91 and is fixedly connected to and conductive to the metal rod 92. During operation, the stepper motor drives the air gap discharge model 9 to move forward as a whole. When the third metal adjustment component 94 comes into contact with the high voltage electrode plate, air gap discharge is generated. During the contact process between the air gap discharge model 9 and the high voltage electrode plate, the third spring 96 provides pressure relief to protect the model.

[0026] When conducting a partial discharge fault simulation test on a power cable, first, reliably ground the casing and discharge defect control box of the power cable partial discharge fault simulation device. Connect the connecting wire to the wiring port of the control box on the fault simulation device, and then increase the voltage of the power cable. When simulating a partial discharge fault test on the power cable body and intermediate joint, the discharge model is located between the two power cables, with the shielding and armor layers of one end of the power cable grounded and the cable core suspended. The other end of the power cable is then voltage-increased. When simulating a partial discharge fault test at the power cable terminal joint, disconnect the power cable, suspend the metal joint of the high-voltage bushing, connect one end of the power cable to one end of the high-voltage bushing, and increase the voltage at the other end of the power cable.

[0027] In power cable partial discharge fault simulation tests, when a tip partial discharge fault needs to be generated, pressing the tip discharge defect control button switch on the discharge model control box closes the control circuit. The stepper motor moves according to the set travel distance, gradually bringing the tip discharge model closer to the high-voltage electrode. When the tip discharge model contacts the high-voltage electrode, it generates a tip discharge. Pressing the tip discharge defect control button switch again disconnects the control circuit. The stepper motor then moves according to the set travel distance, gradually moving the tip discharge model away from the high-voltage electrode until it returns to its initial position, at which point the tip discharge model stops discharging. Similarly, by controlling the air gap discharge defect control button switch and the suspension discharge defect control button switch on the discharge model control box, the travel distance of the stepper motor and the air gap discharge model on it, as well as the suspension discharge model on it, can be controlled, further controlling the generation and disappearance of air gap and suspension partial discharge faults in the power cable. Likewise, it is possible to control the simultaneous generation, disappearance, and aggravation of two or three types of tip, air gap, and suspension partial discharge faults in the power cable. The discharge intensity of various fault discharges can be controlled by adjusting the pressure increase during the pressurization process.

[0028] The above-mentioned power cable fault simulation method accurately and efficiently realizes the generation, disappearance, and aggravation of faults in power cable terminal joints, intermediate joints, and the cable itself; it simulates single or compound partial discharge signals, the variation characteristics of different discharge intensities, and their impact on the insulation performance of power cables, ensuring the comprehensiveness and effectiveness of the fault simulation; during the test, power cables of the actual required voltage level are used, and the type and magnitude of discharge are controlled externally, eliminating the need for frequent replacement of discharge modules, thus improving the safety and accuracy of the test; furthermore, external operation can be performed during the voltage boosting process, eliminating the need for frequent power-on and power-off cycles, making the test more convenient and faster.

[0029] This invention is applicable to the simulation of internal faults in other types and voltage levels of power cables.

Claims

1. A power cable partial discharge fault simulation detection device, comprising a discharge cylinder and two shielding aluminum cylinders, both of which are fixedly connected to the two sides of the discharge cylinder; characterized in that: the discharge cylinder is of a sealed structure, comprising a cylinder body and flanges on both sides of the cylinder body, and a control box connection port is arranged on the flanges; two power cables pass through the end covers of the two shielding aluminum cylinders, are connected with a conductive copper rod in the discharge cylinder and are in conduction; a control box arranged outside the device is connected with the control box connection port; two high-voltage sleeves pass through the flanges on both sides of the discharge cylinder without any gap, and a core rod is arranged in each high-voltage sleeve; the two ends of the conductive copper rod arranged at the axial position in the discharge cylinder extend into one end of the two high-voltage sleeves, and one end of each of the two power cables extends into the other end of the two high-voltage sleeves; the two ends of the conductive copper rod are connected with one end of the core rods in the two high-voltage sleeves and are in conduction, and the other ends of the core rods in the two high-voltage sleeves are connected with the core wires of the two power cables and are in conduction; the two power cables are in conduction through the conductive copper rod and the two core rods; the discharge cylinder is provided with discharge models and a high-voltage electrode; the discharge models are multiple, at least including two of a sharp-end discharge model, a floating discharge model and an air gap discharge model, each discharge model is connected with a corresponding stepping motor through a metal mounting seat, the stepping motor is fixedly arranged on the inner wall of the flange on one side of the discharge cylinder and is signal-connected with the control box connection port, the stepping motor controls the corresponding discharge model to move along the axial direction of the discharge cylinder, and when the metal adjusting member of the sharp-end discharge model, the floating discharge model or the air gap discharge model contacts the high-voltage electrode, sharp-end discharge, floating discharge or air gap discharge is generated; the high-voltage electrode is a metal disc, which is arranged perpendicularly to the axial direction of the discharge cylinder and is fixedly connected with the inner wall of the flange on the other side of the discharge cylinder through an insulating rod; the conductive copper rod passes through the center of the high-voltage electrode perpendicularly and is fixedly connected with the high-voltage electrode and in conduction; when the power cable partial discharge fault simulation test is performed, first, the shell and the discharge defect control box of the power cable partial discharge fault simulation detection device are reliably grounded, the connecting wire is connected with the control box connection port on the fault simulation detection device, and then the power cable is boosted; when the power cable body and the intermediate joint partial discharge fault test is simulated, the discharge models are located between the two power cables, the shielding layer and the armor layer of one end of the power cable are grounded, the cable core is suspended, and the other end of the power cable is boosted; when the power cable terminal joint partial discharge fault test is simulated, the power cable is disconnected, the metal joint of the suspended high-voltage sleeve is disconnected, one end of the power cable is connected with one end of the high-voltage sleeve, and the other end of the power cable is boosted. ​ 2. The power cable partial discharge fault simulation detection apparatus of claim 1, wherein: The tip discharge model comprises a front cylinder and a rear cylinder fixedly connected, the front cylinder and the rear cylinder made of insulating material enclose a discharge cavity, and a metal needle is arranged in the discharge cavity; an end face of the front cylinder is provided with a protrusion, a first conductive rod passes through the protrusion and is fixedly arranged on the end face of the front cylinder; one end of the first conductive rod is fixedly connected with the metal sheet in the discharge cavity and is in conduction, and the other end extends out of the end face protrusion of the front cylinder; part of the first conductive rod and one end of a first metal adjusting piece are arranged in a first metal sleeve, the first metal sleeve is fixedly connected with the end face protrusion of the front cylinder, and a first spring is arranged between the first metal adjusting piece and the first conductive rod; the first metal sleeve, the first metal adjusting piece and the first conductive rod are coaxially arranged, the first metal adjusting piece moves forward and backward along the axis, and the first metal adjusting piece always keeps in conduction with the first conductive rod; a first metal mounting seat is fixedly arranged on the bottom face of the rear cylinder, the root of the metal needle is fixedly connected with the first metal mounting seat and is in conduction, and the tip part faces the metal sheet.

3. The power cable partial discharge fault simulation detection apparatus of claim 1, wherein: The suspension discharge model comprises an insulating cylinder and an insulating seat, the insulating seat is fixedly connected with the open end of the insulating cylinder, the insulating cylinder and the insulating seat enclose a discharge cavity, a metal simulation piece is arranged in the discharge cavity, and the metal simulation piece is fixedly arranged on the insulating seat; an end face of the insulating cylinder is provided with a protrusion, a second conductive rod passes through the protrusion, one end of the second conductive rod extends into the discharge cavity, and the other end extends out of the end face protrusion of the insulating cylinder; the metal simulation piece corresponds to the position of the second conductive rod, and there is a gap between the metal simulation piece and the second conductive rod; part of the second conductive rod and one end of a second metal adjusting piece are arranged in a second metal sleeve, the second metal sleeve is fixedly connected with the end face protrusion of the insulating cylinder, and a second spring is arranged between the second metal adjusting piece and the second conductive rod; the second metal sleeve, the second metal adjusting piece and the second conductive rod are coaxially arranged, the second metal adjusting piece moves forward and backward along the axis, and the second metal adjusting piece always keeps in conduction with the second conductive rod; a second metal mounting seat is fixedly arranged on the insulating seat, and the second metal mounting seat is insulated from the metal simulation piece through the insulating seat.

4. The power cable partial discharge fault simulation detection apparatus of claim 1, wherein: The air gap discharge model comprises an insulating block, a metal rod and a third conductive rod, the insulating block is made of solid polyester material and has bubbles dispersed in the inside; the metal rod and the third conductive rod extend into the insulating block from two sides of the insulating block, the head of the metal rod and the head of the third conductive rod are oppositely arranged and are insulated through the insulating block; part of the third conductive rod and one end of a third metal adjusting piece are arranged in a third metal sleeve, the third metal sleeve is fixedly connected with the insulating block, and a third spring is arranged between the third metal adjusting piece and the third conductive rod; the third metal sleeve, the third metal adjusting piece and the third conductive rod are coaxially arranged, the third metal adjusting piece moves forward and backward along the axis, and the third metal adjusting piece always keeps in conduction with the third conductive rod; a third metal mounting seat is fixedly arranged on the insulating block and is fixedly connected with the metal rod and is in conduction.

5. The power cable partial discharge fault simulation detection apparatus of claim 1, 2, 3, or 4, wherein: The discharge cylinder is provided with a sulfur hexafluoride gas filling port on the cylinder body, and the discharge cylinder is filled with 0.1-1.2 MPa sulfur hexafluoride gas.

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