Vehicle-mounted cable terminal interface discharge test system and method under rapid temperature change condition

Abstract

The invention discloses a vehicle-mounted cable terminal interface discharge test system and method under a rapid temperature change condition. The vehicle-mounted cable terminal interface discharge test system comprises a temperature change control system, a pressurization system, a discharge visual monitoring system, a local signal acquisition system and an interface discharge system, the temperature change control system is used for controlling temperature change of the test bin; the pressurization system is used for applying voltage to the two ends of the composite insulating material; the discharge visual monitoring system is used for collecting image information in the discharge process of the composite insulating material; the local signal acquisition system is used for acquiring current signals generated by discharging of two ends of the composite insulating material; the interface discharge system is used for simulating a vehicle-mounted cable terminal interface discharge phenomenon; according to the invention, the influence of severe temperature change on the interface discharge behavior under the actual service condition can be simulated, and experimental data with more practical significance can be provided for reliability evaluation of a high-voltage cable insulation system; the cable insulation structure is optimized, and important technical support is provided for safety improvement and service life prediction of the high-voltage cable.

Description

Technical Field

[0001] The present invention relates to the technical field of interface discharge and discharge detection, and particularly relates to an in-vehicle cable terminal interface discharge test system and method under rapid temperature change conditions. Background Art

[0002] As a key component connecting cables and equipment in the power system, the reliability of cable terminals directly affects the safe and stable operation of high-voltage systems. In actual operation, the problem of interface discharge inside cable terminals has become increasingly prominent, becoming one of the main causes of cable failures. Interface discharge usually occurs at the junction of different dielectric materials inside the cable terminal. Due to uneven electric field distribution, mismatched material properties, or manufacturing process defects at the interface, interface discharge is easily triggered, which can lead to insulation aging and even breakdown. Existing test devices cannot simulate the thermal shock experienced by in-vehicle cable terminals under complex working conditions. Summary of the Invention

[0003] The present invention provides an in-vehicle cable terminal interface discharge test system and method under rapid temperature change conditions for the problems existing in the prior art.

[0004] The technical solution adopted by the present invention is as follows:

[0005] An in-vehicle cable terminal interface discharge test system under rapid temperature change conditions includes a temperature change control system, a pressurization system, a discharge visualization monitoring system, a local signal acquisition system, and an interface discharge system;

[0006] The temperature change control system is used to control the temperature change of the test chamber;

[0007] The pressurization system includes applying a voltage to both ends of the composite insulation material;

[0008] The discharge visualization monitoring system is used to collect image information during the discharge process of the composite insulation material;

[0009] The local signal acquisition system is used to collect current signals generated by discharges at both ends of the composite insulation material;

[0010] The interface discharge system is used to simulate the interface discharge phenomenon of in-vehicle cable terminals.

[0011] Further, the interface discharge system includes a sealed test chamber and a composite insulation material disposed inside; high-voltage electrodes and grounding electrodes are respectively disposed at both ends of the composite insulation material for applying a voltage to the composite insulation material.

[0012] Further, the temperature change control system includes a liquid nitrogen refrigeration unit and a heating unit connected to the test chamber, and a temperature sensor disposed inside the test chamber; the temperature sensor, the liquid nitrogen refrigeration unit, and the heating unit are connected to a controller.

[0013] Further, the pressure application system includes a high-voltage power supply for applying voltage to both ends of the composite insulating material, a corona-free transformer, a protective resistor, and a coupling capacitor that are sequentially connected to the high-voltage power supply.

[0014] Further, the local signal acquisition system includes a high-frequency current transformer connected to a grounding electrode and a current transformer connected to a high-voltage electrode; the high-frequency current transformer and the current transformer are connected to an oscilloscope; it also includes a partial discharge detector arranged at the grounding end of the coupling capacitor.

[0015] Further, the discharge visualization monitoring system includes a high-speed camera for collecting image information; it also includes an image processing device for processing the image information.

[0016] Further, the composite insulating material is placed on a sample platform, and the sample platform includes a second substrate and a first substrate supported by at least two insulating bolts. The composite insulating material is placed between the second substrate and the first substrate; an insulating plate is arranged below the second substrate; springs are sleeved on the insulating bolts between the second substrate and the insulating plate; the insulating plate is fixed to the insulating bolts through insulating nuts.

[0017] Further, the controller, the corona-free transformer, the partial discharge detector, the oscilloscope, and the image processing device are all connected to a control device.

[0018] A method for on-vehicle cable terminal interface discharge test for rapid temperature change includes the following steps:

[0019] Step 1: Construct a rapid temperature change environment through a temperature change control system;

[0020] Step 2: Apply voltage to the composite insulating material through the pressure application system to trigger interface discharge and maintain the discharge state;

[0021] Step 3: Collect discharge images through the discharge visualization monitoring system;

[0022] Step 4: Obtain the data of the discharge signals during the discharge process through the local discharge signal acquisition system.

[0023] Further, the signals collected by the local discharge signal acquisition system are processed by a wavelet transform algorithm to reduce noise of the discharge signals, and the local discharge patterns are identified through a neural network classification algorithm.

[0024] The beneficial effects of the present invention are:

[0025] (1) The present invention combines the rapid cooling technology of liquid nitrogen to realize the construction of a rapid temperature change environment, breaks through the limitations of traditional steady-state temperature experiments, and simulates and reproduces the severe thermal shock process of grains of on-vehicle cable terminals under complex working conditions;

[0026] (2) In the pressure system of the present invention, a corona-free transformer can effectively reduce the electric field distortion and ensure the stability of high-voltage output; the protection resistor is used to limit the current and prevent the impact of transient overshoot on the test system; the coupling capacitor is used to transmit high-voltage signals and achieve high-sensitivity acquisition of partial discharge signals.

[0027] (3) The present invention integrates a discharge visualization monitoring system and a local signal acquisition system to support the research on the discharge process. The high-speed camera can capture the luminous distribution characteristics and dynamic changes during the discharge process in real time; the high-frequency current transformer and the partial discharge detector can accurately acquire partial discharge signals. Description of the Drawings

[0028] Figure 1 It is a schematic connection diagram of the interface discharge test system of the present invention.

[0029] Figure 2 It is a schematic structural diagram of the discharge experiment system device in the embodiment of the present invention.

[0030] In the figure: 1 - test chamber, 2 - high-speed camera, 3 - liquid nitrogen refrigeration unit, 4 - high-voltage electrode, 5 - grounding electrode, 6 - composite insulating material, 6-1 - main insulating layer, 6-2 - semi-conductive layer, 7-1 - first substrate, 7-2 - second substrate, 8 - spring, 9 - insulating plate, 10 - insulating nut, 11 - insulating bolt, 12 - corona-free transformer, 13 - protection resistor, 14 - coupling capacitor, 15 - partial discharge detector, 16 - current transformer, 17 - high-frequency current transformer, 18 - oscilloscope, 19 - control device. Detailed Embodiments

[0031] The following further describes the present invention in conjunction with the drawings and specific embodiments.

[0032] As Figure 1 shown, a vehicle-mounted cable terminal interface discharge test system under rapid temperature change conditions includes a temperature change control system, a pressure system, a discharge visualization monitoring system, a local signal acquisition system, and an interface discharge system;

[0033] The temperature change control system is used to control the temperature change of the test chamber;

[0034] The pressure system includes applying voltage to both ends of the composite insulating material;

[0035] The discharge visualization monitoring system is used to collect image information during the discharge process of the composite insulating material;

[0036] The local signal acquisition system is used to collect current signals generated by discharges at both ends of the composite insulating material;

[0037] The interface discharge system is used to simulate the interface discharge phenomenon of in-vehicle cable terminals.

[0038] The following provides the specific device structure relationship, such as Figure 2 shown as follows:

[0039] The interface discharge system includes a sealed test chamber 1 and a composite insulating material 6 disposed inside it; a high-voltage electrode 4 and a grounding electrode 5 are respectively disposed at both ends of the composite insulating material to apply a voltage to the composite insulating material 6. Through the combination of the electrodes and the composite insulating material 6, a multi-layer insulation structure is constructed to make the discharge phenomenon closer to the actual interface discharge situation inside the cable. The high-voltage electrode 4 and the grounding electrode 5 can adopt a smooth transition edge design to reduce the local electric field concentration effect (i.e., the edge effect) and avoid the interference of tip discharge. By reasonably controlling the electrode spacing, a stable high-voltage electric field environment is constructed. This design not only ensures the repeatability of the interface discharge but also improves the reliability of experimental measurements, making the study of discharge behavior more accurate, enabling the interface discharge phenomenon of in-vehicle cable terminals to be truly reproduced, and allowing in-depth analysis of its electrical characteristics and evolution laws.

[0040] The composite insulating material 6 is placed on a sample platform. The sample platform includes a second substrate 7-2 and a first substrate 7-1 supported by at least two insulating bolts 11. The composite insulating material is placed between the second substrate 7-2 and the first substrate 7-1; an insulating plate 9 is disposed below the second substrate 7-2; a spring 8 is sleeved on the insulating bolt 11 between the second substrate 7-2 and the insulating plate 9; the insulating plate 9 is fixed to the insulating bolt 11 through an insulating nut 10.

[0041] The first substrate 7-1 and the second substrate 7-2 form an electrode fixture (prepared from acrylic). The high-voltage electrode 4 and the grounding electrode 5 are prepared from a highly conductive material and form a "solid-solid" interface discharge simulation structure with the composite insulating material. The composite insulating material is composed of insulating layers with different dielectric constants and can be composed of a laminate of ethylene propylene diene monomer (EPDM), cross-linked polyethylene (XLPE), and polycarbonate. The thickness of each layer is between 0.1 mm and 5 mm, and the material combination can be adjusted according to experimental requirements to study the interface discharge characteristics of different dielectrics. It can reproduce the interface discharge phenomenon of in-vehicle cable terminals under high voltage, and the discharge characteristics can be optimized through the electrode spacing, insulating layer thickness, and material combination between the high-voltage electrode 4 and the grounding electrode 5. In this embodiment, the composite insulating material uses ethylene propylene diene monomer as the insulating layer 6-1 and low-density polyethylene / carbon black as the semi-conductive layer 6-2 below.

[0042] The temperature change control system includes a liquid nitrogen refrigeration unit 3 and a heating unit connected to the test chamber 1, and a temperature sensor disposed in the test chamber; the temperature sensor, the liquid nitrogen refrigeration unit 3, and the heating unit are connected to a controller. The liquid nitrogen refrigeration unit 3 and the heating unit cooperate through the controller to accurately control the test environment temperature within a short time, enabling the internal temperature of the test chamber to rapidly change according to the set curve, so as to simulate the thermal shock conditions of in-vehicle cable terminals under complex working conditions and provide a stable and controllable test environment. The liquid nitrogen refrigeration unit 3 can achieve a minimum temperature of -196°C, the heating unit can raise the temperature of the test chamber to no higher than 125°C, and the temperature change rate can reach more than 10°C / min. It breaks through the limitations of traditional steady-state temperature experiments and truly reproduces for the first time the severe thermal shock process experienced by in-vehicle cable terminals under complex working conditions under laboratory conditions.

[0043] The pressurization system includes a high-voltage power supply for applying voltage to both ends of the composite insulation material 6, a corona-free transformer 12, a protection resistor 13, and a coupling capacitor 14 that are sequentially connected to the high-voltage power supply. The high-voltage power supply is an adjustable high-voltage power supply for providing 0 - 250 kV AC voltage. The corona-free transformer 12 can effectively reduce electric field distortion and ensure the stability of high-voltage output; the protection resistor 13 is used to limit the current and prevent the impact of transient overshoot on the test system; the coupling capacitor 14 is used to accurately transmit high-voltage signals and achieve high-sensitivity acquisition of partial discharge signals. The corona-free transformer 12 can be provided with a shielding structure to reduce parasitic electric field interference, improve the uniformity of high-voltage loading, and control the current through an adjustable protection resistor to ensure test safety.

[0044] The local signal acquisition system includes a high-frequency current transformer 17 connected to the grounding electrode 5 and a current transformer 16 connected to the high-voltage electrode 4; the high-frequency current transformer (HFCT) 17 and the current transformer 16 are connected to an oscilloscope 18; it also includes a partial discharge detector 15 disposed at the grounding end of the coupling capacitor 14. The high-frequency current transformer 17 is installed in the grounding circuit and is used to continuously collect high-frequency current signals generated by partial discharges. Combined with a band-pass filter, it can effectively suppress noise interference. The high-frequency current transformer 17 extracts discharge characteristic quantities by combining spectrum analysis methods to quantitatively characterize the discharge intensity and its development trend. The partial discharge detector 15 is placed in the grounding circuit of the coupling capacitor 14 to collect local partial discharge signals of the system, which are used to accurately measure the amplitude, frequency, and time distribution of discharge pulses, and the signals are input to the control device 19 for storage. The current transformer 16 uses a CT coil and is set at the high-voltage end to monitor the current change condition, and at the same time extracts current characteristic quantities by combining spectrum analysis methods. The high-frequency current transformer 17 and the current transformer 16 are connected to the oscilloscope 18 to display the collected signals in real time.

[0045] The wavelet transform algorithm is used to denoise the partial discharge signal, and the neural network classification algorithm is combined to identify different types of partial discharge patterns, so as to improve the accuracy of discharge signal analysis.

[0046] The discharge visualization monitoring system includes a high-speed camera 2 for collecting image information; it also includes an image processing device for processing the image information. The high-speed camera 2 has a frame rate of not less than 50000fps, and can capture the light emission characteristics and dynamic changes during the discharge process between the two electrodes and in the insulating material in real time. Combining with the optical filtering component, it can capture the light emission distribution characteristics and dynamic evolution during the interface discharge process. The image processing device uses image processing software to enhance the collected discharge images and improve the visualization analysis accuracy of the discharge behavior.

[0047] The controller, the non-corona transformer 12, the partial discharge detector 15, the oscilloscope 18, and the image processing device are all connected to the control device 19. The control device 19 processes the collected signals (processed by existing processing methods) and stores the information.

[0048] Each component in the system of the present invention cooperates with each other to achieve precise simulation, dynamic monitoring and in-depth analysis of the interface discharge phenomenon, providing more scientific and perfect experimental support for the research on the insulation reliability of cable terminals.

[0049] A test method for interface discharge of in-vehicle cable terminals under rapid temperature change conditions is characterized by including the following steps:

[0050] Step 1: Construct a rapid temperature change environment through the temperature change control system; the liquid nitrogen refrigeration unit 2 and the heating unit cooperate with each other to make the temperature inside the test chamber 1 change at a set rate, and the change of the internal temperature rate of the test chamber 1 is monitored in real time according to the temperature sensor. Open the liquid nitrogen refrigeration unit 2 to control the liquid nitrogen to enter the test chamber 1, and the temperature in the test chamber quickly drops to the set value and remains stable for a period of time. Close the liquid nitrogen refrigeration unit 2 and turn on the heating unit to quickly raise the temperature in the test chamber 1 to the set value. Repeat the rapid cooling-heating cycle to simulate the sudden climate conditions in the train operation environment.

[0051] Step 2: Apply a voltage to the composite insulating material through the pressurization system to trigger interface discharge and maintain the discharge state; different interface discharge characteristics under different conditions can be obtained through the structural parameters of the electrodes and the combination parameters of the composite insulating material. Specifically, a high voltage is applied through the non-corona transformer 12 and gradually increased to the discharge inception voltage. Stabilize the voltage and collect the optical signal and partial discharge signal of the interface discharge.

[0052] Step 3: Collect discharge images through the discharge visualization monitoring system; use the high-speed camera 2 to collect discharge optical signals, record the interface discharge phenomenon, and perform data analysis through image processing software. Obtain the optical characteristics of the discharge such as spot changes and flashover paths through the high-speed camera 2.

[0053] Step 4: Obtain the data of the discharge signals during the discharge process through the partial discharge signal acquisition system. Obtain the discharge amplitude, frequency, and their evolution trends through the discharge signals collected by the HFCT.

[0054] Subsequently, the influence of temperature changes on the interface discharge inception voltage, discharge frequency, and duration can be studied based on the collected signals. Obtain the partial discharge amplitude, discharge times, and their time-domain / frequency-domain characteristics through the information collected by the HFCT. Analyze the light intensity distribution and the evolution of the discharge path during the discharge process through the optical signals collected by the high-speed camera 2.

[0055] The present invention includes a temperature change control system, a pressure application system, a discharge visualization monitoring system, a local signal acquisition system, and an interface discharge system. Among them:

[0056] Temperature change control system: It has the ability to quickly and accurately control the temperature, can change the test environment temperature in a short time, and ensure that the test conditions meet the requirements of interface discharge research. This system can simulate the thermal shock experienced by in-vehicle cable terminals under complex working conditions to explore the influence of drastic temperature changes on interface discharge characteristics, such as discharge inception voltage, discharge intensity, and evolution trend.

[0057] Pressure application system: It consists of key equipment such as a non-corona transformer, a protective resistor, and a coupling capacitor, and provides a stable and uniform high-voltage field to trigger and maintain interface discharge. This system not only ensures the safety of the test process but also ensures the stability and accuracy of the measurement data, avoiding external interference from affecting the experimental results.

[0058] Interface discharge system: Use a combination of specific electrode materials and insulating materials to construct an interface discharge simulation system with a multi-layer composite insulation structure. This system can reproduce the interface discharge phenomenon that may occur during the long-term operation of in-vehicle cable terminals, and conduct in-depth analysis of its electrical characteristics (such as discharge voltage, discharge energy) and evolution laws, providing an experimental basis for subsequent optimization of the insulation structure.

[0059] Discharge visualization monitoring system: Use a high-speed camera to perform high-precision and real-time imaging of the interface discharge process, capturing the light emission distribution characteristics and dynamic changes during the discharge process. Combining image processing technology, the spatial distribution, intensity fluctuation, and time evolution of the discharge can be analyzed, providing intuitive optical observation data for the study of discharge mechanisms.

[0060] Local signal acquisition system: It collects high-frequency discharge signals in the grounding loop through a high-frequency current transformer (HFCT), and combines with a partial discharge detector to accurately measure and analyze the signals.

[0061] The present invention combines the rapid cooling technology of liquid nitrogen with a sealed test chamber to accurately construct a rapid temperature change environment, breaking through the limitations of traditional steady-state temperature experiments, and being able to truly reproduce the severe thermal shock process experienced by vehicle-mounted cable terminals under complex working conditions in the laboratory. This temperature control system can not only achieve a large temperature change in a very short time, but also has precise control ability, making the experimental environment closer to the actual application scenario. It significantly improves the controllability and stability of the interface discharge experiment, making the repeatability of the discharge phenomenon higher and the test data more reliable, providing more accurate experimental support for deeply revealing the mechanism of interface discharge. The device structure of the present invention not only ensures the repeatability of interface discharge, but also improves the reliability of experimental measurement, making the research on discharge behavior more accurate, enabling the true reproduction of the interface discharge phenomenon of vehicle-mounted cable terminals, and allowing in-depth analysis of its electrical characteristics and evolution law. The test system also integrates an interface discharge visualization monitoring system and a partial discharge signal acquisition system to provide support for multi-dimensional research on the discharge process. It can capture the light emission distribution characteristics and dynamic changes during the discharge process in real time, providing intuitive optical observation data for discharge mechanism analysis, while the high-frequency current transformer (HFCT) combined with a partial discharge detector can accurately measure partial discharge signals, quantify the discharge intensity and its development trend, so as to identify different types of discharge patterns and further reveal the evolution mechanism of interface discharge. It can simulate the influence of drastic temperature changes under actual service conditions on interface discharge behavior, providing more realistic experimental data for the reliability assessment of high-voltage cable insulation systems. This not only helps to optimize the cable insulation structure, but also provides important technical support for improving the safety and predicting the life of high-voltage cables, and has important value for engineering applications.

Claims

1. An on-vehicle cable terminal interface discharge test system under rapid temperature change conditions, characterized in that, It includes a temperature change control system, a pressurization system, a discharge visualization monitoring system, a local signal acquisition system, and an interface discharge system; The temperature change control system is used to control the temperature change of the test chamber; The pressurization system includes applying voltage to both ends of the composite insulation material; The discharge visualization monitoring system is used to collect image information during the discharge process of the composite insulation material; The local signal acquisition system is used to collect the current signals generated by the discharge at both ends of the composite insulation material; The interface discharge system is used to simulate the interface discharge phenomenon of the vehicle-mounted cable terminal.

2. The on-vehicle cable terminal interface discharge test system under rapid temperature change conditions according to claim 1, wherein The interface discharge system includes a sealed test chamber (1) and a composite insulation material (6) arranged inside; high-voltage electrodes (4) and grounding electrodes (5) are respectively arranged at both ends of the test sample for applying voltage to the composite insulation material (6).

3. The on-vehicle cable terminal interface discharge test system under rapid temperature change conditions according to claim 2, wherein, The temperature change control system includes a liquid nitrogen refrigeration unit (3) and a heating unit connected to the test chamber (1), and a temperature sensor arranged inside the test chamber; the temperature sensor, the liquid nitrogen refrigeration unit (3), and the heating unit are connected to the controller.

4. A discharge test system for the interface of in-vehicle cable terminals under rapid temperature change conditions according to claim 3, characterized in that, The pressurization system includes a high-voltage power supply for applying voltage to both ends of the composite insulation material (6), a non-corona transformer (12), a protective resistor (13), and a coupling capacitor (14) connected to the high-voltage power supply in sequence.

5. The on-vehicle cable terminal interface discharge test system under rapid temperature change conditions according to claim 4, wherein, The local signal acquisition system includes a high-frequency current transformer (17) connected to the grounding electrode (5) and a current transformer (16) connected to the high-voltage electrode (4); the high-frequency current transformer (17) and the current transformer (16) are connected to an oscilloscope (18); it also includes a partial discharge detector (15) arranged at the grounding end of the coupling capacitor (14).

6. The on-vehicle cable terminal interface discharge test system under rapid temperature change conditions according to claim 5, characterized in that, The discharge visualization monitoring system includes a high-speed camera (2) for collecting image information; it also includes an image processing device for processing the image information.

7. An on-vehicle cable terminal interface discharge test system under rapid temperature change conditions according to claim 6, characterized in that, The composite insulation material (6) is placed on a sample platform, and the sample platform includes a second substrate (7-2) and a first substrate (7-1) supported by at least two insulating bolts (11), and the composite insulation material is placed between the second substrate (7-2) and the first substrate (7-1); an insulating plate (9) is arranged below the second substrate (7-2); a spring (8) is sleeved on the insulating bolt (11) between the second substrate (7-2) and the insulating plate (9); the insulating plate (9) is fixed to the insulating bolt (11) through an insulating nut (10).

8. A vehicle-mounted cable terminal interface discharge test system under rapid temperature change conditions according to claim 7, characterized in that The controller, the non-corona transformer (12), the partial discharge detector (15), the oscilloscope (18), and the image processing device are all connected to a control device (19).

9. A test method using the test system according to any one of claims 1 to 8, characterized in that, It includes the following steps: Step 1: Construct a rapid temperature change environment through the temperature change control system; Step 2: Apply voltage to the composite insulation material through the pressurization system to trigger interface discharge and maintain the discharge state; Step 3: Collect discharge images through the discharge visualization monitoring system; Step 4: Obtain the data of the discharge signals during the discharge process through the local discharge signal acquisition system.

10. The test method according to claim 9, characterized in that, The signals collected by the local discharge signal acquisition system are processed by the wavelet transform algorithm to denoise the discharge signals, and the local discharge patterns are identified through the neural network classification algorithm.

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