Nondestructive testing method and testing system for transient energy tolerance threshold of carbon ceramic resistor based on microcrack detection

Abstract

The invention discloses a carbon ceramic resistor transient energy tolerance threshold nondestructive testing method and testing system based on microcrack detection. The testing system comprises a controllable high-voltage direct-current charging power supply, a transient energy discharging unit, a control unit, a transient energy and X-ray micro-CT microcrack detection unit and a computer measurement and control management unit. According to the method, the change rule of the microstructure in the carbon ceramic resistor is obtained, the rule between generation, development and evolution of microcracks in the carbon ceramic resistor and transient energy injection is obtained, the transient energy threshold value capable of being tolerated by the carbon ceramic resistor is determined, and data support is provided for model selection and safe operation of the closing resistor of the circuit breaker.

Description

Technical Field

[0001] This invention relates to a transient energy withstand test method for power equipment or devices, and particularly to a non-destructive testing method and system for transient energy withstand threshold of carbon ceramic resistors based on microcrack detection. Background Technology

[0002] With the development of ultra-high voltage power transmission technology in my country, carbon ceramic resistors are widely used in 330kV and above transmission lines to limit overvoltage generated during the closing process of high voltage circuit breakers and suppress arc reignition. They are the core protection for the development of ultra-high voltage and extra-high voltage power transmission and transformation equipment.

[0003] Carbon-ceramic linear resistors represent a challenging technology in current power transmission systems. During circuit breaker closing, the absorption of transient energy from the transmission line by the closing resistor is a crucial testing item. Whether the carbon ceramic resistor will develop microcracks or even explode after absorbing large amounts of transient energy is a primary concern for the safe operation of circuit breakers. During transient energy withstand tests, the carbon ceramic resistor element frequently explodes, but the mechanism of this explosion is unclear, failing to provide guidance for the selection of carbon ceramic resistors for transmission line circuit breakers, or for optimizing the formulation, molding, and sintering processes of the carbon ceramic resistor element material. Therefore, this study aims to develop a non-destructive testing method and system for the transient energy withstand threshold of carbon ceramic resistors, establish a microcrack monitoring system based on X-ray micro-CT, and conduct experimental demonstrations of the generation and evolution of microcracks within the carbon ceramic resistor element under transient energy injection. The goal is to obtain the transient energy withstand threshold of the carbon ceramic resistor, providing data support for the selection and safe operation of circuit breaker closing resistors. Summary of the Invention

[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a non-destructive testing method and system for the transient energy tolerance threshold of carbon ceramic resistors based on microcrack detection, thereby obtaining the threshold of transient energy tolerance of carbon ceramic resistors and providing data support for the selection of circuit breaker closing resistors and safe operation.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The non-destructive testing system for transient energy tolerance threshold of carbon ceramic resistors based on microcrack detection includes a controllable high-voltage DC charging power supply, a transient energy discharge unit, a control unit, a transient energy and X-ray micro-CT microcrack detection unit, and a computer measurement and control management unit. The controllable high-voltage DC charging power supply is used to charge the energy storage capacitor C in the transient energy discharge unit. The charging process or the amplitude of the charging voltage is jointly controlled by the computer measurement and control management unit and the control unit. The transient energy discharge unit includes an energy storage capacitor C, a discharge switch G, a waveform forming inductor L, a waveform forming resistor R, and a carbon ceramic resistive load, which form pulse current waveforms with different transient peak values / or energy outputs, generate transient energy voltages, and inject them into the carbon ceramic resistive load. The control unit includes a programmable controller and a charging voltage monitoring circuit. The charging voltage monitoring circuit monitors the charging voltage across the energy storage capacitor C online and provides a discharge control signal to the discharge switch G when the charging voltage reaches the preset discharge voltage. The transient energy and X-ray micro-CT microcrack detection unit includes a carbon ceramic resistor transient energy measurement unit and a carbon ceramic resistor internal microcrack detection unit, which are used to calculate the energy absorbed by the carbon ceramic resistor and obtain the microscopic features inside the carbon ceramic body under transient energy injection. The computer measurement and control management unit is used to control the automatic execution of the transient energy withstand test of carbon ceramic resistance, as well as the internal microstructure characteristics of the carbon ceramic body under transient energy injection.

[0006] By controlling the controllable high-voltage DC charging power supply through the computer measurement and control unit and the control unit, different transient energies are injected into the carbon ceramic resistor. By progressively increasing the transient energy injection and analyzing the internal micromorphology of the carbon ceramic resistor through the computer measurement and control management unit, the variation law of the internal micromorphology of the carbon ceramic resistor is obtained. The law between the occurrence, development and evolution of microcracks inside the carbon ceramic body and the injected transient energy is obtained, and the transient energy threshold that the carbon ceramic resistor can withstand is determined.

[0007] Preferably, the transient energy measurement unit of the carbon ceramic resistor comprises a pulse voltage divider, a pulse current sensor, and an oscilloscope; the pulse voltage divider measures the voltage across the load of the carbon ceramic resistor, the pulse current sensor measures the pulse current flowing through it, and the oscilloscope measures the pulse voltage and pulse current and transmits the pulse voltage and pulse current signals to the computer measurement and control unit. The energy absorbed by the carbon ceramic resistor is calculated by integrating the current with respect to time.

[0008] Preferably, the microcrack detection unit inside the carbon ceramic resistive ceramic body includes an X-ray micro-CT scanner. The X-ray micro-CT scanner detects micro-crack images inside the carbon ceramic resistive ceramic body, and the micro-features inside the carbon ceramic ceramic body under transient energy injection are obtained through computer analysis and processing.

[0009] Preferably, the computer measurement and control management unit is also used to automatically monitor the charging process of the carbon ceramic resistor transient energy test; to automatically control the process of the carbon ceramic resistor transient energy test in conjunction with the programmable controller; to realize the data and image analysis of the carbon ceramic resistor transient energy test; and to record, store, query, and output test reports of the carbon ceramic resistor transient energy test signals and images.

[0010] A non-destructive testing method for the transient energy withstand threshold of carbon ceramic resistivity in microcrack detection includes the following steps: (1) Set the resistance value of the carbon ceramic resistor, the discharge voltage of the transient energy discharge unit, and the transient energy injection gradient; (2) The computer measurement and control management unit and the control unit jointly control the transient energy discharge unit by controlling the controllable high voltage DC charging power supply through the programmable controller and the charging voltage monitoring circuit. The controllable high voltage DC charging power supply charges the energy storage capacitor C of the transient energy discharge unit and automatically tracks the real-time state of the charging voltage across the energy storage capacitor C. When the charging voltage across the energy storage capacitor C reaches the preset discharge voltage, the control pulse is automatically given to the discharge switch G of the transient energy discharge unit to break down and discharge, injecting the specified transient energy into the carbon ceramic resistor. (3) Use a pulse voltage divider, a pulse current sensor and an oscilloscope to measure the voltage across the carbon ceramic resistor load and the current flowing through the carbon ceramic resistor load respectively; through communication between the oscilloscope and the computer measurement and control management unit and the calculation of the computer management software, accurately calculate the transient energy injected into the carbon ceramic resistor. (4) Use an X-ray micro-CT scanner to detect the internal micro-morphological features of the carbon ceramic resistor and determine whether there are micro-cracks inside the carbon ceramic resistor; if not, increase the charging voltage of the controllable high voltage DC charging power supply to achieve a gradient increase in the transient energy of the carbon ceramic resistor until obvious micro-cracks appear inside the carbon ceramic resistor. (5) Repeat steps (1) to (4) to obtain a series of transient energy values ​​and data on the internal morphology and microcracks and their propagation of carbon ceramic resistors. Analyze the energy threshold that carbon ceramic resistors can withstand, the microcrack initiation time, and the correlation between the microcrack development and evolution law of carbon ceramic resistors and the injected transient energy.

[0011] Compared with the prior art, the present invention has at least the following beneficial effects: This invention addresses the application needs of determining the transient energy tolerance threshold of carbon ceramic resistors in circuit breakers of ultra-high voltage transmission systems and selecting carbon ceramic resistors for circuit breakers in different application scenarios. It proposes a non-destructive testing method and system for the transient energy tolerance threshold of carbon ceramic resistors based on microcrack detection, obtaining the threshold of transient energy tolerance of carbon ceramic resistors, and providing data support for the selection of circuit breaker closing resistors and safe operation.

[0012] This invention proposes a method for monitoring and analyzing microcracks in carbon ceramic resistor bodies under transient energy injection. A microcrack monitoring system based on X-ray micro-CT is established for carbon ceramic resistors. Experimental demonstrations are conducted to illustrate the generation, development, and evolution of microcracks within the carbon ceramic resistor body under transient energy injection. This method obtains the formation, development, and evolution process of microcracks within the carbon ceramic resistor body under transient energy injection, thereby determining the threshold for transient energy tolerance of carbon ceramic resistors. This method can be applied to similar scenarios such as transient energy tolerance tests of composite media in the power and communication fields. Attached Figure Description

[0013] Figure 1 This is a block diagram of the non-destructive testing system for the transient energy tolerance threshold of carbon ceramic resistors according to the present invention. Figure 2 This is a schematic diagram of the transient energy discharge circuit of the present invention; Figure 3 This is a block diagram illustrating the principle of calculating the energy absorbed by the carbon ceramic resistor in this invention. Figure 4 This invention relates to a non-destructive testing method and test flowchart for the transient energy tolerance threshold of carbon ceramic resistors. Detailed Implementation

[0014] The present invention will be further described in detail below with reference to specific embodiments, but this is not intended to limit the present invention.

[0015] See Figure 1 , Figure 2 , Figure 3 This invention relates to a non-destructive testing system for the transient energy tolerance threshold of carbon ceramic resistors based on microcrack detection. It mainly consists of a controllable high-voltage DC charging power supply 1, a transient energy discharge unit 2, a control unit 4, a transient energy and X-ray micro-CT microcrack detection unit 5, and a computer measurement and control management unit 6. The controllable high-voltage DC charging power supply 1 consists of an adjustable DC high-voltage power supply (DC) and a current-limiting resistor (R). Its function is to charge the energy storage capacitor C in the transient energy discharge unit 2. The charging process or the amplitude of the charging voltage is jointly controlled by the computer measurement and control management unit 6 and the control unit 4. By controlling the magnitude of the charging voltage, the transient / pulse current waveform parameters output by the transient energy discharge unit are controlled, thereby controlling the magnitude of the transient energy applied to the carbon ceramic resistor load 3.

[0016] The transient energy discharge unit 2 mainly includes an energy storage capacitor C, a discharge switch G, a waveform forming inductor L, a waveform forming resistor R, and a carbon ceramic resistive load 3. The function of the transient energy discharge unit 2 is to generate pulse current waveforms with different transient peak values ​​and / or energy outputs. Furthermore, the parameters of the energy storage capacitor C, the waveform forming inductor L, and the waveform forming resistor R can be adjusted according to the size of the carbon ceramic resistive load 3. By adjusting the capacitance value of the energy storage capacitor, the forming inductor, and the resistor value, the duration or half-peak time of the current flowing through the carbon ceramic resistive load 3 with different resistance values ​​is made to be within a certain specified range. This half-peak time should be comparable to the circuit breaker closing time, and the transient energy injected into the load 3 reaches a preset value. The charged energy storage capacitor discharges through the discharge switch and the waveform forming inductor and resistor to the carbon ceramic resistive load, thereby generating a transient energy voltage and injecting it into the carbon ceramic resistive load. Transient energy is controlled by adjusting the capacitance of the energy storage capacitor, the inductance and resistance values ​​to ensure that the duration or half-peak time of the current flowing through carbon ceramic resistive loads with different resistance values ​​is within a certain specified range. This half-peak time should be comparable to the circuit breaker closing time.

[0017] The control unit 4 mainly includes a programmable controller 4-1 and a charging voltage monitoring circuit 4-2. The charging voltage monitoring circuit 4-2 can monitor the charging voltage across the energy storage capacitor C online and issue a discharge control signal to the discharge switch G when the charging voltage reaches the preset discharge voltage.

[0018] The transient energy and X-ray micro-CT microcrack detection unit 5 mainly includes a carbon ceramic resistor transient energy measurement unit 51 and a carbon ceramic resistor internal microcrack detection unit 52. Among them: The transient energy measurement unit consists of a pulse voltage divider 51-1, a pulse current sensor 51-2, and an oscilloscope 51-3. The pulse voltage divider 51-1 measures the voltage across the carbon ceramic resistive load 3, the pulse current sensor 51-2 measures the pulse current flowing through it, and the oscilloscope 51-3 measures the pulse voltage and pulse current and transmits these signals to the computer control unit 6. The energy absorbed by the carbon ceramic resistor is calculated by integrating the current with respect to time.

[0019] The carbon ceramic resistor ceramic body internal microcrack detection unit 52 mainly includes an X-ray micro-CT scanner. The micro-crack images inside the carbon ceramic resistor ceramic body detected by X-ray micro-CT are analyzed and processed by a computer to obtain the micro-characteristics inside the carbon ceramic ceramic body under transient energy injection.

[0020] The computer measurement and control management unit 6 mainly includes an industrial control computer and its dedicated data management software. Its main function is to control the automatic operation of the transient energy withstand test of carbon ceramic resistors and to control the internal microstructure characteristics of carbon ceramic bodies under transient energy injection.

[0021] The computer measurement and control management unit 6 is also used for: ① automatically monitoring the charging process of the transient energy test of carbon ceramic resistor; ② automatically controlling the process of the transient energy test of carbon ceramic resistor in conjunction with the programmable logic controller 4-1; ③ realizing data and image analysis of the transient energy test of carbon ceramic resistor; ④ recording, storing, querying and outputting test reports of the transient energy test signals and images of carbon ceramic resistor.

[0022] See Figure 4 As shown, this invention provides a non-destructive testing method for the transient energy tolerance threshold of carbon ceramic resistors based on microcrack detection. Through the control of a controllable high-voltage DC charging power supply 1 by a computer measurement and control unit and a control unit, the voltage of the energy storage capacitor in the transient energy discharge unit 2 is adjusted, allowing for the injection of different transient energies into the carbon ceramic resistor. An X-ray micro-CT scanner is used to detect the internal microstructure of the carbon ceramic resistor. By progressively increasing the transient energy injection and analyzing the internal microstructure of the carbon ceramic resistor by the computer measurement and control management unit 6, the variation law of the internal microstructure of the carbon ceramic resistor is obtained. This reveals the relationship between the occurrence, development, and evolution of microcracks within the carbon ceramic resistor and the injected transient energy, thereby determining the transient energy threshold that the carbon ceramic resistor can tolerate.

[0023] The detailed measurement flowchart is as follows: (1) Start the operation of the non-destructive testing system software for the transient energy tolerance threshold of carbon ceramic resistors.

[0024] (2) Set the resistance value of the carbon ceramic resistor, the discharge voltage of the transient energy discharge unit 2 and the transient energy injection gradient.

[0025] (3) The computer measurement and control management unit 6 and the control unit 4 jointly control the transient energy discharge unit 2 by controlling the controllable high voltage DC charging power supply 1 to charge the energy storage capacitor C of the transient energy discharge unit 2 through the programmable controller 4-1 and the charging voltage monitoring circuit 4-2, and automatically track the real-time state of the charging voltage across the energy storage capacitor C. When the charging voltage across the energy storage capacitor C reaches the preset discharge voltage, the control pulse is automatically given to the discharge switch G of the transient energy discharge unit 2 to break down and discharge, injecting the specified transient energy into the carbon ceramic resistor.

[0026] (4) Use pulse voltage divider 51-1, pulse current sensor 51-2 and oscilloscope 51-3 to measure the voltage across the carbon ceramic resistor load 3 and the current flowing through the carbon ceramic resistor load 3 respectively; through communication between oscilloscope 51-3 and computer measurement and control management unit 6 and calculation by computer management software, accurately calculate the transient energy injected into the carbon ceramic resistor.

[0027] (5) Use an X-ray micro-CT scanner to detect the internal microstructure of the carbon ceramic resistor and determine whether there are microcracks inside the carbon ceramic resistor. If not, increase the charging voltage of the controllable high-voltage DC charging power supply 1 to achieve a gradient increase in the transient energy of the carbon ceramic resistor until obvious microcracks appear inside the carbon ceramic resistor.

[0028] (6) Repeat steps (2) to (5) to obtain a series of transient energy values ​​and data on the internal morphology and microcracks and their propagation of carbon ceramic resistors. Analyze the energy threshold that carbon ceramic resistors can withstand, the microcrack initiation time, and the correlation between the microcrack development and evolution law of carbon ceramic resistors and the injected transient energy.

Claims

1. A non-destructive testing system for transient energy withstand threshold of carbon ceramic resistance based on microcrack detection, characterized in that: It includes a controllable high-voltage DC charging power supply (1), a transient energy discharge unit (2), a control unit (4), a transient energy and X-ray micro-CT microcrack detection unit (5), and a computer measurement and control management unit (6). The controllable high-voltage DC charging power supply (1) is used to charge the energy storage capacitor C in the transient energy discharge unit (2). The charging process or the amplitude of the charging voltage is jointly controlled by the computer measurement and control management unit (6) and the control unit (4). The transient energy discharge unit (2) includes an energy storage capacitor C, a discharge switch G, a waveform forming inductor L, a waveform forming resistor R and a carbon ceramic resistive load (3), forming pulse current waveforms with different transient peak values / or energy outputs, generating transient energy voltage and injecting it into the carbon ceramic resistive load (3). The control unit (4) includes a programmable controller (4-1) and a charging voltage monitoring circuit (4-2). The charging voltage monitoring circuit (4-2) monitors the charging voltage across the energy storage capacitor C online and provides a discharge control signal to the discharge switch G when the charging voltage reaches the preset discharge voltage. The transient energy and X-ray micro-CT microcrack detection unit (5) includes a carbon ceramic resistor transient energy measurement unit (51) and a carbon ceramic resistor internal microcrack detection unit (52), which are used to obtain the transient current and voltage waveform parameters of the carbon ceramic resistor energy absorption, as well as the microscopic features inside the carbon ceramic body under transient energy injection. The computer measurement and control management unit (6) is used to control the automatic execution of the transient energy withstand test of carbon ceramic resistance, as well as the calculation of transient energy and the analysis of the internal micro-morphological characteristics of carbon ceramic body. By controlling the controllable high-voltage DC charging power supply (1) through the computer measurement and control unit and the control unit, different transient energies are injected into the carbon ceramic resistor. By progressively increasing the transient energy injection and analyzing the internal micro-morphology of the carbon ceramic resistor through the computer measurement and control management unit (6), the variation law of the internal micro-morphology of the carbon ceramic resistor is obtained, the law between the occurrence, development and evolution of microcracks inside the carbon ceramic body and the injected transient energy is obtained, and the transient energy threshold that the carbon ceramic resistor can withstand is determined.

2. The non-destructive testing system for transient energy withstand threshold of carbon ceramic resistance based on microcrack detection as described in claim 1, characterized in that: The transient energy measurement unit (51) of the carbon ceramic resistor includes a pulse voltage divider (51-1), a pulse current sensor (51-2), and an oscilloscope (51-3). The pulse voltage divider (51-1) measures the voltage across the carbon ceramic resistor load (3), the pulse current sensor (51-2) measures the pulse current flowing through it, and the oscilloscope (51-3) measures the pulse voltage and pulse current and transmits the pulse voltage and pulse current signals to the computer measurement and control unit (6). The energy absorbed by the carbon ceramic resistor is calculated by integrating the current and the current with respect to time.

3. The non-destructive testing system for transient energy withstand threshold of carbon ceramic resistance based on microcrack detection as described in claim 1, characterized in that: The microcrack detection unit (52) inside the carbon ceramic resistive ceramic body includes an X-ray micro-CT scanner. The X-ray micro-CT scanner detects micro-crack images inside the carbon ceramic resistive ceramic body, and obtains the micro-features inside the carbon ceramic ceramic body under transient energy injection through computer analysis and processing.

4. The non-destructive testing system for transient energy withstand threshold of carbon ceramic resistance based on microcrack detection as described in claim 2 or 3, characterized in that: The computer measurement and control management unit (6) is also used to automatically monitor the charging process of the transient energy test of the carbon ceramic resistor; and to automatically control the process of the transient energy test of the carbon ceramic resistor in conjunction with the programmable logic controller (4-1); Enables data and image analysis of transient energy tests on carbon ceramic resistors; records, stores, queries, and outputs test reports for transient energy test signals and images of carbon ceramic resistors.

5. A non-destructive testing method for the transient energy tolerance threshold of carbon ceramic resistance based on the microcrack detection of the testing system described in claim 4, characterized in that... Includes the following steps: (1) Set the resistance value of the carbon ceramic resistor, the discharge voltage of the transient energy discharge unit (2), and the transient energy injection gradient; (2) The computer measurement and control management unit (6) and the control unit (4) jointly control the transient energy discharge unit (2) by controlling the controllable high voltage DC charging power supply (1) through the programmable controller (4-1) and the charging voltage monitoring circuit (4-2) to charge the energy storage capacitor C of the transient energy discharge unit (2), and automatically track the real-time state of the charging voltage across the energy storage capacitor C. When the charging voltage across the energy storage capacitor C reaches the preset discharge voltage, the control pulse is automatically given to the discharge switch G of the transient energy discharge unit (2) to break down and discharge, injecting the specified transient energy into the carbon ceramic resistor. (3) Use a pulse voltage divider (51-1), a pulse current sensor (51-2), and an oscilloscope (51-3) to measure the voltage across the carbon ceramic resistor load (3) and the current flowing through the carbon ceramic resistor load (3); through communication between the oscilloscope (51-3) and the computer measurement and control management unit (6) and the calculation of the computer management software, accurately calculate the transient energy injected into the carbon ceramic resistor; (4) Use an X-ray micro-CT scanner to detect the internal micro-morphological features of the carbon ceramic resistor and determine whether there are micro-cracks inside the carbon ceramic resistor. If not, increase the charging voltage of the controllable high voltage DC charging power supply (1) to achieve a gradient increase in the transient energy of the carbon ceramic resistor until obvious micro-cracks appear inside the carbon ceramic resistor. (5) Repeat steps (1) to (4) to obtain a series of transient energy values ​​and data on the internal morphology and microcracks and their propagation of carbon ceramic resistors. Analyze the energy threshold that carbon ceramic resistors can withstand, the microcrack initiation time, and the correlation between the microcrack development and evolution law of carbon ceramic resistors and the injected transient energy.

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