Joint test system and test method for partial discharge and breakdown under wide temperature range and variable air pressure

Abstract

The invention discloses a partial discharge and breakdown combined test system and test method under wide temperature range and variable air pressure, which are suitable for evaluating the insulating properties of insulating materials, cables and power equipment under high and low temperature and different air pressure conditions. The system comprises a vacuum oven, a partial discharge and withstand voltage breakdown joint test module, an explosion-proof cable joint, a control module and a detection module, the vacuum oven can realize temperature regulation and control from-70 DEG C to + 200 DEG C and an air pressure environment of 10 <-3 > Pa, and the test module integrates a high voltage generator, a coaxial electrode and a partial discharge sensor. Partial discharge detection and breakdown voltage measurement can be completed in the same test environment. According to the test method, the electrical response characteristics of the insulating material under different working conditions are obtained through regulation and control of environment temperature and pressure, execution of a test process and data acquisition and analysis. The device is compact in structure and high in safety, and has the capabilities of joint testing, high-precision regulation and control and adaptability to complex environments.

Description

Technical Field

[0001] The present invention relates to the field of electrical equipment insulation performance testing, and particularly to a combined testing system and method for partial discharge and breakdown applicable to wide temperature range and variable pressure conditions. Background Art

[0002] During the research and development and quality inspection of power systems and related products, partial discharge and breakdown voltage have always been the core indicators for measuring insulation performance. Existing partial discharge and withstand voltage testing methods mostly focus on the normal temperature and pressure environment. Although the basic performance can be evaluated, it is difficult to cover the complex working conditions faced by electrical equipment during actual operation. For example, when the equipment operates in high altitude, extremely cold, tropical or enclosed cabins, the temperature and pressure environments it bears will change significantly, which poses higher requirements for the performance of the insulation system.

[0003] Currently widely used testing systems often lack the ability to dynamically adjust temperature and pressure, and cannot effectively simulate extreme working conditions such as high temperature, low temperature, high pressure or vacuum, resulting in a deviation between the test results and the actual use environment. In addition, most existing systems operate the partial discharge test and the withstand voltage breakdown test as two independent modules, increasing the complexity of the test process and also raising the risk of error accumulation during the test.

[0004] More notably, when conducting tests in extreme environments, the sealing and safety of the equipment become key factors. Traditional testing equipment often has insufficient sealing performance under high temperature, low temperature or vacuum conditions, which may not only affect the stability of test data, but also pose potential operation safety hazards.

[0005] Therefore, there is an urgent need for a combined testing system with wide temperature range regulation and variable pressure adaptation capabilities, which can not only complete partial discharge and withstand voltage breakdown tests simultaneously, but also ensure good sealing structure and control stability in extreme environments, thereby improving the test efficiency and the representativeness of data, and meeting the needs of the research and development of new generation highly reliable electrical equipment. Summary of the Invention

[0006] To solve the problem that the existing testing system cannot carry out the combined test of partial discharge and breakdown in a wide temperature range and variable pressure environment, the present invention proposes a highly integrated testing system, which can complete the electrical performance evaluation of insulating materials or devices on the same platform, significantly improving the test efficiency and the controllability of the test environment, and effectively enhancing the safety and sealing performance of the system.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] In a possible implementation, a combined partial discharge and breakdown test system under wide temperature range and variable pressure is provided, including: a vacuum oven for providing a controllable temperature environment (-70°C to +200°C) and a pressure environment (atmospheric pressure to 10 - 3 Pa); a combined partial discharge and withstand voltage breakdown test module integrated in the vacuum oven, including a high-voltage generator, a test electrode, and a partial discharge detection sensor; an explosion-proof cable joint installed on the pipeline of the vacuum oven for sealing and leading out the test cable and ensuring airtightness under extreme environments; a control module connected to the vacuum oven and the combined test module for adjusting temperature, pressure, and test parameters; and a detection module for real-time acquisition of partial discharge signals, breakdown voltages, and environmental parameters.

[0009] In a possible implementation, the vacuum oven includes: a temperature control unit that precisely adjusts the temperature inside the oven using a PID algorithm; a pressure adjustment unit that realizes segmented pressure control through a vacuum pump and a pressure valve.

[0010] In a possible implementation, in the combined partial discharge and withstand voltage breakdown test module, the high-voltage generator can output AC / DC voltages, the test electrode has a coaxial structure, and the partial discharge detection sensor is a high-frequency current transformer or a coupling capacitor.

[0011] In a possible implementation, the explosion-proof cable joint includes a metal shell, a ceramic insulator, and a compression nut, and its installation method is: cutting a hole in the vacuum oven pipeline; filling and fixing with a high and low temperature resistant sealant after embedding the joint.

[0012] In a possible implementation, the control module includes: an environmental parameter control unit for setting temperature, pressure, and change rate; a test logic unit for realizing automatic switching between partial discharge and withstand voltage breakdown tests.

[0013] In a possible implementation, a combined partial discharge and breakdown test method under wide temperature range and variable pressure is provided, using the system described in any of the above implementations, including the following steps: specimen installation, placing the insulating material or device to be tested between the test electrodes in the vacuum oven; environment setting, setting the target temperature (-70°C to +200°C) and pressure (atmospheric pressure to 10 -3 Pa) through the control module; combined test, under stable environmental conditions, first start partial discharge detection, record the discharge amount and phase distribution; gradually increase the voltage until the specimen breaks down, and record the breakdown voltage value; data analysis, correlating environmental parameters with test results to evaluate the insulation performance.

[0014] In a possible implementation, in the steps of the above test method, the partial discharge detection and the withstand voltage breakdown test share the same set of test electrodes, and the test voltage is continuously adjustable.

[0015] In a possible implementation, in the steps of the above test method, the air pressure regulation adopts a segmented control strategy: first quickly evacuate to 90% of the target air pressure, and then finely adjust at a rate not higher than 1 kPa / s.

[0016] In a possible implementation, in the steps of the above test method, the breakdown determination condition is: the leakage current exceeds the threshold or the partial discharge amount suddenly increases by more than 50%.

[0017] Based on the above technical solution, a combined partial discharge and breakdown test system under wide temperature range and variable air pressure of the present invention realizes a comprehensive electrical performance evaluation of insulating materials or electrical equipment under high and low temperatures, vacuum or different air pressure conditions by highly integrating the functions of temperature and air pressure environment control, partial discharge test and breakdown voltage test. The present invention effectively solves the problems of poor environmental adaptability, scattered functions, large test errors and low safety of the existing test systems, and has the remarkable advantages of high test accuracy, convenient operation, safety and reliability, and is applicable to multiple application scenarios such as insulation structure optimization, power equipment research and development, and high-reliability detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the overall control schematic diagram of the present invention

[0019] Figure 2 It is the air pressure control diagram of the present invention

[0020] Figure 3 It is the electrical test device diagram of the present invention

[0021] Figure 4 It is the schematic diagram of the explosion-proof cable joint and cable of the present invention

[0022] Figure 5 It is the cable access pipeline diagram of the present invention

[0023] Figure 6 It is the diagram of the electrical test line accessing the vacuum oven of the present invention DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] A combined partial discharge and breakdown test system under wide temperature range and variable air pressure proposed by the present invention aims to accurately evaluate the insulation performance of electrical equipment or insulating materials under complex environmental conditions, especially the integrated integration of partial discharge and breakdown tests under high and low temperatures and low air pressure environments.

[0025] Such as Figure 1As shown in the figure, a combined partial discharge and breakdown test system under wide temperature range and variable pressure provided by the present invention generally includes: a vacuum oven, a combined partial discharge and withstand voltage breakdown test module, an explosion-proof cable joint, a control module, and a detection module. Each part is connected through cables, pipelines or signal channels to form a controllable and safe integrated test system structure.

[0026] During the implementation process, first, a vacuum oven with temperature control and pressure control functions is constructed. This oven has a multi-layer metal cavity structure, equipped with a heating unit and a refrigeration module, and can achieve temperature adjustment in the range of -70°C to +200°C. Externally, it is connected to a vacuum pump and a pressure control valve to form a sealed vacuumable space, and the internal pressure of the cavity can reach as low as 10 -3 Pa. The pressure adjustment adopts a two-stage strategy: initially, rapid pumping is achieved through a vacuum pump, and then the throttle valve is used to slowly adjust to the target pressure at a rate not exceeding 1 kPa / s to reduce test disturbances.

[0027] In terms of pressure control, as Figure 2 shown in the figure, the present invention adopts an integrated variable pressure adjustment system to achieve dynamic pressure adjustment and precise control in the test environment from atmospheric pressure to high vacuum (as low as 10 -3 Pa). This system includes core components such as a cylinder, a high-pressure pipeline, a vacuum pump group, an adjustment valve group, a flow measurement and control device, and a pressure feedback device.

[0028] The cylinder is connected to the regulating valve through a cylinder valve and is used to inject high-pressure gas into the test cavity to increase the internal pressure of the cavity. The regulating valve group can finely control the flow rate and the incoming air pressure, including an instrument valve and a pressure regulator for the pre-stage pressure regulation. The gas injection rate is monitored by a flow meter and is real-time fed back to the control module by a pressure sensor to achieve closed-loop control. The system can set different pressurization rates and termination thresholds according to test requirements during the pressurization stage, and is suitable for the study of the partial discharge characteristics of insulating materials in a high-pressure environment.

[0029] During the pumping process, the system forms a parallel pumping path through a coarse adjustment valve, a fine adjustment valve and a vacuum pump. The coarse adjustment valve is used for rapid pressure reduction in the early stage, and the fine adjustment valve is used for precise pressure control in the approximate vacuum section. A diaphragm pump is also provided at the rear end of the vacuum pump to extend the vacuum holding time and reduce reverse contamination. All vacuum interfaces and the main test cavity are connected by high-pressure connection components and 8 nylon hardware to ensure airtightness during the switching process of pumping and pressure boosting.

[0030] In particular, the present invention also employs a linear motion feeding device to adjust the position of the test sample or sensor in the high-pressure cavity and perform sealed plugging and unplugging operations, improving the maintainability and modularity of the equipment during operation. The entire pneumatic control system is coordinated by a control module. The user can set the pneumatic target value, adjustment method (single-stage / segmented), and rate limit through a graphical interface. The system automatically controls the gas injection or extraction process based on the feedback signal to ensure that the test environment remains stable and controllable throughout the entire process.

[0031] Through the synergistic effect of the above pneumatic adjustment system, the present invention can simulate the complex pneumatic conditions required for partial discharge and breakdown tests, and has good response speed, adjustment accuracy, and environmental consistency, providing reliable technical support for the insulation stability test of insulating materials under different atmospheric environments (such as high altitudes, vacuum chambers, and simulated high altitudes).

[0032] A combined partial discharge and withstand voltage breakdown test module is installed inside the oven. This module includes a high-voltage generator, test electrodes, and a partial discharge detection sensor. The high-voltage generator is connected to an external high-voltage power supply and can output the required DC or AC voltage signal according to the setting to meet the needs of breakdown tests for different types of samples. The test electrodes are designed with a coaxial cylindrical structure, having good electric field uniformity and effectively avoiding edge discharge or field strength distortion; the discharge sensor is selected from a high-frequency current transformer or a coupling capacitor, with high sensitivity and broadband response capabilities, suitable for extracting weak partial discharge signals.

[0033] As Figures 4 - 6 shown, to introduce high-voltage cables between the outside and inside of the cavity while ensuring the safe sealing of the system under extreme temperature and pressure conditions, the system opens a round hole in the oven pipeline and installs an explosion-proof cable joint. This joint consists of a metal shell, a ceramic insulating core, and a compression nut, and is fixed by embedding and sealing with a high and low temperature resistant sealant to form a stable high-voltage lead channel. One end of the test cable is connected to the external high-voltage power supply and the control unit, and the other end extends into the cavity through the explosion-proof joint and is connected to the test electrode to form a closed loop.

[0034] In terms of electrical connection, as Figure 3 shown, a complete high-voltage test circuit is built inside the system. The step-up transformer is connected to the high-voltage power supply to convert the power frequency voltage into a high-voltage signal and control the current peak value through a current limiting resistor to prevent overcurrent impact during breakdown. A withstand voltage breakdown tester is serially installed in the high-voltage path to measure the breakdown voltage of the specimen, and a parallel resistance voltage divider is used for high-voltage signal monitoring. The output end of the voltage divider is connected to a voltage measurement module to monitor the high-voltage change process in real time.

[0035] At the end of the test circuit, an apparent resistance and a synchronous resistance are also connected in series, and the two form a parallel network. The apparent resistance is used to adjust the overall impedance of the test system and suppress the reflection of discharge pulses; the synchronous resistance is connected to the synchronous trigger device to assist in identifying the partial discharge pulse signal and the instantaneous breakdown characteristics. The test object is placed in the high-voltage path and clamped by the test electrodes on both sides. A coupling capacitor is set on it to optimize the signal channel and at the same time allows access to the partial discharge signal acquisition path to extract the discharge waveform.

[0036] The wiring structure of the entire test circuit is compact. High-insulation-level connecting wires are used between the functional modules. The position of the voltage sampling point can be adjusted according to the actual situation, and it is adapted to various upper-level acquisition systems such as monitoring instruments, oscilloscopes, and discharge recorders, enhancing the intuitiveness and analysis ability of the test results.

[0037] After the electrical connection and environmental setting are completed, the control module is activated to start the test process. First, the target temperature and air pressure are set. The control system sequentially completes the temperature rise / cooling and vacuum pumping processes. After the environmental parameters are stable, the combined test program is started. In the partial discharge detection stage, the discharge inception voltage, discharge quantity, and phase distribution are collected. Subsequently, the high-voltage generator is controlled to increase the voltage at a constant rate until the sample breaks down, and key parameters such as breakdown voltage and leakage current are recorded through the detection module.

[0038] The judgment of the breakdown event is based on a preset threshold. When the leakage current exceeds the safety upper limit or the partial discharge quantity suddenly increases by more than 50%, it is automatically identified as a breakdown. The system immediately cuts off the power supply and saves the data. The entire test process is automatically executed by the control module. The data is transmitted to the upper computer in real time through the detection module for storage and processing, and finally a comprehensive test report is output for insulation performance evaluation.

[0039] In addition, this system is equipped with multiple safety mechanisms such as temperature and pressure abnormal alarm, overvoltage cut-off, and cavity leakage monitoring to ensure stable and safe operation under extreme working conditions such as high voltage, high temperature, and vacuum. The structure is reasonably designed and the test functions are perfect, which is suitable for the wide application of scientific research institutions, quality inspection units, and power equipment manufacturing enterprises in the development, performance verification, and quality control of insulating materials.

[0040] Application Example 1: Partial Discharge and Breakdown Test of Power Cables under High Temperature Conditions In this example, the test object is a cross-linked polyethylene (XLPE) insulated power cable with a rated voltage of 10 kV. The length of the specimen intercepted is 1.2 meters. The sheaths at both ends are stripped and connected to the coaxial test electrodes in the test system of the present invention to form a high-voltage loading circuit. The specimen is placed inside a vacuum oven and ensured to be in a suspended state through an electrode fixing frame to avoid mechanical interference.

[0041] Before the test, the environmental temperature is set to +180°C through the control module, and the heating system in the vacuum oven is started for preheating. After the temperature stabilizes, maintain the atmospheric pressure atmosphere, activate the partial discharge detection module, and monitor the potential discharge points in the cable insulation layer. Subsequently, start the high-voltage generator and increase the voltage at a rate of 0.5 kV / s. During this period, continuously record the partial discharge inception voltage, discharge quantity, and phase distribution data.

[0042] When the voltage rises to the point where the specimen insulation layer breaks down, the system records the breakdown voltage and automatically cuts off the power supply. Subsequently, download the test data and analyze it to evaluate the partial discharge characteristics and insulation tolerance of the cable under high-temperature conditions, providing data support for predicting its service life in a high-temperature substation environment.

[0043] Application Example 2: Simulating the Insulation Performance Test of Substation Bushings in a High-Altitude Environment

[0044] This embodiment is applied to the verification test of a certain type of GIS (Gas Insulated Switch) bushing insulator under the operating conditions in plateau areas. Install the bushing sample to be tested inside the test cavity of the system of the present invention, and connect it to the test electrode through a high-voltage-resistant flange to ensure uniform electric field distribution and airtight sealing.

[0045] Before the test starts, start the air pressure regulation system through the control module. First, evacuate to 10 -2 Pa, and then slowly introduce the simulated atmosphere (such as dry air or nitrogen) to control the internal pressure of the cavity to be stable at about 60 kPa to simulate the low-pressure environment above 3000 meters above sea level. The test temperature is set to -30°C to simulate the low-temperature plateau environment.

[0046] Under stable environmental conditions, start the partial discharge detection unit to monitor the discharge behavior caused by possible air gaps, interfaces, or cavities in the internal insulation structure of the bushing, and obtain the partial discharge inception voltage and spectral characteristics. Subsequently, gradually increase the voltage until breakdown occurs, and record the corresponding breakdown voltage.

[0047] The test results are used to judge the electrical reliability of the bushing structure under extreme plateau operating conditions and guide the improvement of manufacturing processes or the optimized selection of materials. Such applications are suitable for type tests of primary substation equipment before being put into operation in special regions (such as the Qinghai-Tibet Plateau and the southwestern mountainous areas).

[0048] The above embodiments fully demonstrate the feasibility and practicality of the present invention in different application scenarios. Combining the wide temperature range, variable air pressure, and combined test capabilities, it has good engineering adaptability.

[0049] The present invention is not limited to the specific structures and processes described in the above embodiments. For those skilled in the art, various deformations, improvements, substitutions, and equivalent solutions made without departing from the core idea and technical concept of the present invention, for example:

[0050] Adjustment of specific sensor types in the test system (such as using different types of partial discharge detection devices);

[0051] Optimization of the temperature and pressure control strategy of the vacuum oven (such as higher-precision PID regulation);

[0052] Replacement of the software and hardware platform of the control module (such as using different PLCs or embedded systems);

[0053] Structural adaptability changes suitable for different types of insulating materials or test objects;

[0054] All of these fall within the technical protection scope of the present invention. Any technical solution that makes a substantial equivalent change to its structure, method, parameters, etc. based on the basic concept of the present invention shall be covered by the scope claimed by the present invention.

Claims

1. A combined test system for partial discharge and breakdown under variable air pressure in a wide temperature range, characterized in that Including: Vacuum oven, used to provide an adjustable temperature environment and air pressure environment, the adjustable range of the temperature is from -70°C to +200°C, and the adjustable range of the air pressure is from atmospheric pressure to 10 -3 Pa; A combined partial discharge and withstand voltage breakdown test module, which is arranged inside the vacuum oven and includes a high-voltage generator, a test electrode, and a partial discharge detection sensor; An explosion-proof cable joint, which is arranged on the pipeline of the vacuum oven and is used to lead out high-voltage test cables under high temperature, low temperature or vacuum conditions and ensure the sealing performance; A control module, which is used to set and regulate the temperature and air pressure of the vacuum oven and execute the test process; A detection module, which is used to collect partial discharge signals, breakdown voltage values, and environmental parameters and output data to the upper computer.

2. The system according to claim 1, wherein The test electrode is of a coaxial cylindrical structure to improve the electric field uniformity and reduce edge discharge.

3. The system according to claim 1, wherein The partial discharge detection sensor is a high-frequency current transformer or a coupling capacitor.

4. The system according to claim 1, wherein The explosion-proof cable joint includes a metal shell, a ceramic insulation core body, and a compression nut, and is encapsulated and fixed with a high and low temperature resistant sealant.

5. The system according to claim 1, characterized in that, The control module includes: an environmental parameter control unit, which is used to set the temperature and air pressure; A test logic unit, which is used to automatically execute the switching and control of partial discharge and breakdown tests.

6. The system according to claim 1, wherein The air pressure regulation unit of the vacuum oven adopts a two-stage control strategy, including a rough vacuum pumping stage and a fine adjustment stage.

7. A combined test method for partial discharge and breakdown under variable air pressure in a wide temperature range, characterized in that, Including the following steps: S1. Place the insulating material or device to be tested between the coaxial test electrodes inside the vacuum oven; S2. Set the target temperature to -70°C to +200°C and the air pressure to normal pressure to 10 -3 Pa through the control module; S3. In a stable environment, start the partial discharge detection module and record the discharge amount and phase distribution; S4. Continue to increase the test voltage until breakdown occurs, and record the breakdown voltage and leakage current; S5. Correlate and analyze the above test data with environmental parameters to evaluate the insulation performance.

8. The method according to claim 7, wherein The breakdown determination condition is that the partial discharge amount suddenly increases by more than 50% within a short time or the leakage current exceeds the preset threshold.

9. The method according to claim 7, wherein The air pressure regulation adopts a segmented strategy: first pump to 90% of the target air pressure, and then slowly adjust at a rate not higher than 1 kPa / s.

10. The method according to claim 7, wherein The partial discharge detection and withstand voltage breakdown test share the same set of test electrodes, and the test voltage is continuously adjustable.

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