A dynamic interruption aging method for vacuum interrupters based on multiple re-breakdowns

Abstract

The present invention provides a dynamic interruption aging method for a vacuum interrupter based on multiple re-breakdowns. The method includes the following steps: performing multiple re-breakdowns on the contact surface during the interruption process, thereby eliminating weak points on the contact surface and gradually improving the dielectric recovery strength; building a simulation platform to obtain interruption and re-breakdown waveforms at different break rise times; building a dynamic interruption aging test platform for the vacuum interrupter; and obtaining the re-breakdown waveform to obtain the vertex envelope of the re-breakdown waveform of the vacuum interrupter at that moment. This dynamic interruption aging method for a vacuum interrupter based on multiple re-breakdowns can not only use multiple re-breakdowns to complete the aging of the vacuum circuit breaker, but also use the breakdown voltage to describe the withstand voltage recovery curve of the vacuum circuit breaker, thereby evaluating the aging degree and anti-re-breakdown performance of the vacuum circuit breaker. Ultimately, it can serve as a means of evaluating the anti-re-breakdown performance of the vacuum circuit breaker.

Description

Technical Field

[0001] The present invention relates to the technical field of vacuum circuit breakers, in particular to a dynamic breaking and aging method of a vacuum interrupter based on multiple restrikes. Background Art

[0002] The insulation properties of vacuum circuit breakers significantly influence the successful interruption of capacitor banks. Burn-in can significantly improve these insulation properties and is a key process step in enhancing and stabilizing the voltage withstand capability of vacuum interrupters. Newly manufactured vacuum interrupters undergo factory burn-in to meet operational requirements, with most manufacturers employing a voltage burn-in process. Traditional power-frequency high-voltage burn-in involves applying power-frequency high voltage across the interrupter, causing multiple spark discharges. However, due to the low discharge current, each discharge lasting approximately 500 nanoseconds, and the small number of discharges and uneven distribution, the burn-in effect is poor.

[0003] Using high-frequency pulses to perform high-voltage discharge aging on a single arc extinguishing chamber has improved efficiency and effect compared with traditional spark discharge aging and DC low current aging. However, the test power supply is complex and is only suitable for static aging of arc extinguishing chambers before leaving the factory.

[0004] Currently, research on key technical issues, such as parameter configuration of the recovery voltage waveform during circuit breaker burn-in and evaluation of the circuit breaker's heavy breakdown performance, has not yet been conducted domestically or internationally. Current voltage burn-in is generally a static burn-in process, making it impossible to develop a burn-in plan tailored to the heavy breakdown performance of each interrupter, and even more difficult to quantitatively evaluate the heavy breakdown performance after burn-in. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a dynamic breaking and aging method for vacuum interrupters based on multiple heavy breakdowns to solve the problems raised in the above background technology. The present invention can simultaneously obtain the dynamic breaking breakdown voltage curve of the vacuum circuit breaker, and based on this, a means of evaluating the anti-heavy breakdown performance of the vacuum circuit breaker can be obtained.

[0006] In order to achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions: a dynamic breaking and aging method for a vacuum interrupter based on multiple restrikes, the method comprising the following contents: multiple restrikes occur continuously on the contact surface during the breaking process, thereby eliminating weak points on the contact surface and realizing a gradual improvement in the dielectric recovery strength; building a simulation platform to obtain the breaking and restriking waveforms under different rise times of the fracture; building a dynamic breaking and aging test platform for the vacuum interrupter; after obtaining the restriking waveform, the vertex envelope of the restriking waveform of the vacuum interrupter at this moment is obtained, and combined with the stroke curve, the cold-state dielectric recovery characteristic curve at this moment is obtained; the performance change trend of the vacuum interrupter is obtained through the obtained envelope.

[0007] Furthermore, the dynamic breakdown voltage of the circuit breaker is measured by applying a dynamic recovery voltage. During the circuit breaker opening process, a recovery voltage with a certain rise time is generated at both ends of the break. This dynamic recovery voltage application method is applied to the vacuum circuit breaker opening process.

[0008] Furthermore, it also includes a process of measuring the dynamic breakdown voltage circuit of the circuit breaker, which includes the following steps: before the test, the circuit breaker is in the open state, and a DC high-voltage source is used to charge the energy storage capacitor C1 and the impulse voltage divider C2. During the operation, the circuit breaker is closed and opened. After the closing operation is completed, the voltage across the impulse voltage divider C2 drops to the minimum, and then the circuit breaker starts the opening operation.

[0009] Furthermore, the opening operation includes the following steps:

[0010] S1. When the circuit breaker contacts are separated, the experimental circuit breaker CB is open, and the energy storage capacitor C1 charges the impulse voltage divider C2 again, and the voltage across the impulse voltage divider C2 rises rapidly;

[0011] S2: When the voltage across the impulse voltage divider C2 is greater than the fracture breakdown voltage, the fracture breaks down, the impulse voltage divider C2 is short-circuited to the ground, and the voltage across the two ends drops rapidly;

[0012] S3. After the arc between the circuit breaker breaks is extinguished, the impulse voltage divider C2 is opened again. The above process is repeated until the energy storage capacitor C1 charges the impulse voltage divider C2 and can no longer cause the break to break.

[0013] Furthermore, during the breaking process, when the fracture withstand voltage recovery strength is higher than the recovery voltage, the fracture does not re-break down.

[0014] Furthermore, during the breaking process, when the break voltage is quickly charged to the recovery voltage and reaches the withstand voltage recovery strength, the break will be broken down again. The break capacitance is very small and the arc is extinguished quickly. The break will be quickly charged to the recovery voltage again and will be broken down again when it reaches the withstand voltage recovery strength again.

[0015] Furthermore, the re-breakdown is repeated multiple times until the withstand voltage recovery strength exceeds the recovery voltage.

[0016] Furthermore, the performance of the vacuum interrupter at different times can be judged based on the rising speed of the vertex envelope of the vacuum interrupter. The faster the rising speed of the vertex envelope, the higher the curve, which indicates that the performance of the interrupter is better; otherwise, the performance of the vacuum interrupter is worse.

[0017] Furthermore, the method also includes a special dynamic breaking test platform with adjustable rise time, in which a DC high-voltage power supply charges the energy storage capacitor Cs2 through a charging resistor Rs2, and a resistor divider FY2 is used to monitor the voltage of Cs2.

[0018] Furthermore, after the breaking circuit control switch GK2 is closed, the test circuit breaker SP is opened at no-load, and Cs2 charges the recovery voltage capacitor Ck through the recovery voltage regulating resistor R1 to form an exponentially rising recovery voltage. After each arc extinguishing of the break, Ck can quickly charge the break capacitor through the break charging resistor R2 to synchronize with the recovery voltage. When the break insulation is insufficiently recovered, multiple restrikes will occur. The break insulation can be subjected to breaking and aging by utilizing multiple restrikes and discharges.

[0019] Beneficial effects of the present invention:

[0020] 1. This dynamic breaking aging method for vacuum interrupters based on multiple heavy breakdowns can not only use multiple heavy breakdowns to complete the aging of vacuum circuit breakers, but also describe the withstand voltage recovery curve of vacuum circuit breakers through breakdown voltage, and thus evaluate the aging degree and heavy breakdown resistance performance of vacuum circuit breakers.

[0021] 2. This dynamic interruption burn-in method for vacuum interrupters based on multiple re-strikes has a good burn-in effect on newly manufactured vacuum interrupters. Based on the above simulation analysis results, a subsequent test voltage of 40kV achieves better burn-in results without damaging the vacuum interrupter.

[0022] 3. This dynamic interruption aging method for vacuum interrupters based on multiple re-strikes can also be combined with the travel curve to obtain the cold dielectric recovery characteristic curve of the vacuum interrupter. Furthermore, the rising speed of the peak envelope of the vacuum interrupter can be used to determine the performance of the interrupter at different times. A faster rising speed, i.e., a higher curve, indicates better performance; conversely, a lower curve indicates poorer performance. The envelope curve improves after aging. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the dynamic breakdown voltage measurement circuit of the SF6 circuit breaker of the present invention;

[0024] Figure 2 This is a schematic diagram of the fracture re-breakdown principle of the breaking and aging test of the present invention, wherein (a): when the fracture withstand voltage recovery curve is higher than the recovery voltage, there is no re-breakdown; (b): when the fracture withstand voltage recovery curve is lower than the recovery voltage, there are multiple re-breakdowns;

[0025] Figure 3 To disconnect the aging test circuit in the embodiment of the present invention;

[0026] Figure 4This is a simplified circuit diagram in an embodiment of the present invention;

[0027] Figure 5 The waveforms of the simulation of the breaking burn-in test in the embodiment of the present invention are shown as follows: (a): the recovery voltage rise time is 7 ms; (b): the recovery voltage rise time is 3.5 ms; (c): the recovery voltage rise time is about 1.8 ms; (d): the recovery voltage rise time is about 1 ms; (e): the recovery voltage rise time is about 0.5 ms.

[0028] Figure 6 The following is a graph of typical waveform and vertex envelope curve;

[0029] Figure 7 2. A graph showing a changing trend of the number of restrikes in an embodiment of the present invention;

[0030] Figure 8 2 is a comparison diagram of the vertex envelope in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0032] See also Figures 1 to 8 The present invention provides the following technical solutions: a dynamic interruption aging method for vacuum interrupters based on multiple re-strikes. The post-arc withstand voltage recovery process of a vacuum circuit breaker refers to the process in which the gap in the vacuum interrupter gradually recovers from the high-conductivity state during arcing to the high-resistance insulation state after the current passes through zero and the arc is extinguished. The post-arc withstand voltage recovery process is mainly divided into three stages. The initial withstand voltage recovery stage is mainly driven by sheath development, and the enhanced field-induced electron emission from the sheath and cathode surface mainly affects the early withstand voltage recovery speed. The mid-term withstand voltage recovery stage is mainly affected by the diffusion and attenuation of metal vapor density, which is a key stage in the withstand voltage recovery process. The late-term withstand voltage recovery stage is when the vacuum gap fully recovers to its static withstand voltage.

[0033] During actual operation, both ends of the circuit breaker's breakpoint are affected by the transient recovery voltage (TRV). This is known as the dynamic withstand voltage recovery process. During this process, the ion sheath cannot withstand the rapidly rising post-arc transient recovery voltage, causing electrical breakdown of the vacuum gap. Therefore, during the vacuum circuit breaker's opening process, the arc gap must recover at a rate that consistently exceeds the rising rate of the system transient recovery voltage after the arc current passes through zero. Otherwise, a re-breakdown will occur.

[0034] In this embodiment, a dynamic recovery voltage application method is used to measure the dynamic breakdown voltage of the SF6 circuit breaker. The principle is as follows: Figure 2As shown, during the interruption process, a recovery voltage with a certain rise time is generated across the break. Applying this dynamic recovery voltage application method to the interruption process of a vacuum circuit breaker can, from one perspective, allow for multiple breakouts during the interruption process. This number of re-breakdown discharges can allow for multiple high-voltage burn-in cycles of the contacts at different opening distances. Furthermore, the voltage value of the re-breakdown during the interruption process reflects the voltage recovery characteristics of the vacuum circuit breaker. If re-breakdown does not occur at a certain recovery voltage rise rate and voltage value, it means that the vacuum circuit breaker's resistance to re-breakdown exceeds this voltage rise rate and voltage value, which directly reflects the vacuum circuit breaker's resistance to re-breakdown. Therefore, this interruption method can not only utilize multiple re-breakdowns to complete the burn-in of the vacuum circuit breaker, but also characterize the voltage recovery curve of the vacuum circuit breaker based on the breakdown voltage, thereby evaluating the burn-in degree and re-breakdown resistance of the vacuum circuit breaker.

[0035] Before the test, the circuit breaker is in the open state, and a DC high-voltage source is used to charge the energy storage capacitor C1 and the impulse voltage divider C2. During the test, the circuit breaker performs a closing-opening operation. After the closing operation is completed, the voltage across C2 drops to the minimum, and then the circuit breaker begins to open. During the opening process:

[0036] 1. When the circuit breaker contacts separate, CB opens, and the energy storage capacitor C1 charges C2 again, causing the voltage across C2 to rise rapidly.

[0037] 2. When the voltage across C2 is greater than the breakdown voltage of the fracture, the fracture breaks down, C2 is short-circuited to ground, and the voltage across both ends drops rapidly.

[0038] 3. After the arc between the circuit breaker's fractures is extinguished, C2 is opened again, and the above process is repeated until C1 charges C2 and can no longer cause the fracture to break.

[0039] When interrupting capacitor banks, re-breakdown often occurs under short arcing conditions. Under these conditions, the interrupting current is low (approximately 400A), the arc duration is short (less than 1ms), and the arc energy is very low, very close to no-load interruption. Applying a dynamic recovery voltage during dynamic interruption simulates the harshest conditions of actual interruption and facilitates horizontal comparison of circuit breaker interruption performance.

[0040] Figure 2 The red figure is the transient recovery voltage of the fracture, and the black figure is the withstand voltage recovery strength. During the breaking process of the test piece, when the withstand voltage recovery strength of the fracture is higher than the recovery voltage, the fracture will not break down. Figure 2As shown in (a). During the breaking process of the test piece, when the break voltage is quickly charged to the recovery voltage and reaches the withstand voltage recovery strength, the break occurs a re-breakdown. The break capacitance is very small and the arc is quickly extinguished. The break is quickly charged to the recovery voltage again and reaches the withstand voltage recovery strength again, and then it breaks down again. This re-breakdown is repeated many times until the withstand voltage recovery strength exceeds the recovery voltage. Figure 2 (b) shown.

[0041] This embodiment also provides a simulation and experimental process based on the above method, which specifically includes the following contents:

[0042] (1) Basic principles of dynamic breaking test platform

[0043] Based on the preliminary research of the project and the principle diagram of the dynamic breakdown voltage measurement circuit of the SF6 circuit breaker, a special dynamic breaking test platform with adjustable rise time is designed. Figure 3 As shown in the figure, a DC high-voltage power supply charges the energy storage capacitor Cs2 through charging resistor Rs2, and resistor divider FY2 is used to monitor the voltage of Cs2. After the disconnect circuit control switch GK2 is closed, the test circuit breaker SP is disconnected at no load. Cs2 charges the recovery voltage capacitor Ck through the recovery voltage regulating resistor R1, forming an exponentially rising recovery voltage. After each arc extinction, Ck can quickly charge the break capacitor through the break charging resistor R2 to synchronize with the recovery voltage. If the break insulation is not fully recovered, multiple restrikes will occur. Using these multiple restrikes, the insulation can be aged during interruption. The multiple restrikes voltage curve can also represent the withstand voltage recovery capability of the SP capacitor bank for low-current zero-arcing time interruption, and can be used to quantitatively evaluate its resistance to restrikes. Resistor-capacitor dividers FY3 and FY4 are used to measure the recovery voltage and break voltage waveforms, respectively. The metal oxide voltage limiter MOA is used to limit the overvoltage generated by test anomalies.

[0044] During the break voltage recovery process, R2 is used to restore the voltage capacitor Ck to charge the break in a non-oscillating manner, rapidly applying the recovery voltage. During the break re-breakdown process, R2 limits the discharge current from Ck to the break, reducing the energy injected into the re-breakdown arc, which facilitates rapid arc extinction at the break, while also reducing the magnitude of the instantaneous drop in the recovery voltage during the re-breakdown process. Based on the current carrying capacity and breaking capacity of the vacuum circuit breaker contacts, the arc will not damage the contacts during the re-breakdown process, and the break can be extinguished within a few microseconds, resulting in an instantaneous drop in the recovery voltage. The higher the re-breakdown voltage, the longer the arc extinction time, and the greater the instantaneous drop in the recovery voltage. Figure 3 After simplification, we can get Figure 4 The circuit shown.

[0045] After Laplace transform, the recovery voltage equation applied by the moving and static contacts at both ends of the fracture during the opening process can be obtained:

[0046]

[0047] Assuming that Cs2 is much larger than Ck, and Ck is much larger than the sum of the circuit breaker capacitance and the arrester capacitance, the impact of the above capacitance and its voltage changes on the recovery voltage during the opening and aging process can be minimized. This leads to formula (3-2):

[0048]

[0049] The recovery voltage between the fractures is obtained by inverse Laplace transform:

[0050]

[0051] (2) Analysis of simulation results

[0052] Based on the TRV waveform of the capacitor bank current breaking type test in GB1984, the parameters are improved and the fracture withstand voltage recovery curve is assumed to be During the heavy breakdown process of the circuit breaker, it is assumed that the oscillating current of the circuit breaker decays to a very small value before the arc is extinguished. Figure 5 As shown, the blue is the vacuum interrupter withstand voltage recovery curve, and the red is the actual voltage curve of the fracture.

[0053] From the simulation results, it can be seen that the slower the recovery voltage rises, the less likely it is for high potential area re-breakdown to occur; the faster the recovery voltage rises, the more likely it is for high potential area re-breakdown to occur, and the number and duration of re-breakdowns increase, and the maximum re-breakdown voltage also increases.

[0054] When the rise time is 0.5ms, after a re-breakdown occurs at the fault, the fault capacitor quickly discharges in a short circuit, and the recovery voltage is instantly lowered. The arc energy at the fault discharge is very small and extinguishes quickly. The fault voltage quickly charges to the recovery voltage and rises exponentially. Furthermore, the re-breakdown voltage at the fault also increases. The more re-breakdowns occur, the greater the reduction in the recovery voltage.

[0055] Finished 12kV vacuum interrupters have low initial performance, insufficient withstand voltage, and a high number of restrikes during interruption. Therefore, this method offers a better burn-in effect on these newly shipped vacuum interrupters. Based on the simulation analysis results above, a subsequent test voltage of 40kV achieves even better burn-in results without damaging the vacuum interrupter.

[0056] (3) Experimental results

[0057] When the breaking speed is 0.89m / s, as the contacts are continuously pulled apart, multiple re-breakdowns will occur between the fractures, thereby obtaining a continuous multiple electric spark aging effect.

[0058] For the convenience of statistics, in this embodiment, five breaking tests are used as one round, and the heavy breakdown area with a breakdown voltage greater than 15kV is called the high potential area heavy breakdown area, and the number of heavy breakdowns is the total number of breakdowns in the high potential area. Figure 7 The figure shows the changing trend of the restrike frequency after 10 cycles of k-interrupting burn-in. The test results show that during the test period, the restrike frequency of the vacuum interrupter gradually decreased with the increase in the number of interruptions, from 34 at the beginning to 23 at the end. The power frequency withstand voltage increased from 52kV to 60kV, demonstrating a certain interruption burn-in effect.

[0059] In addition, the cold medium recovery characteristic curve of the vacuum interrupter can be obtained by combining the stroke curve later. In addition, the performance of the interrupter at different times can also be judged based on the rising speed of the peak envelope of the vacuum interrupter. The faster the rising speed, that is, the higher the curve, the better the performance of the interrupter; conversely, the worse the performance of the vacuum interrupter. Figure 8 As shown in Figure 3, the envelope curve is improved after aging.

[0060] It can be seen from the above embodiments that

[0061] 1) A simulation model is built in the dynamic breaking and aging method provided by the present invention. By studying the breaking and restrike waveforms under different rise times, it is found that the faster the rise time, the more breaking and restrike times the vacuum interrupter has, and the greater the maximum restrike voltage.

[0062] 2) An experimental platform was built. During the interruption process, this method generates multiple re-breakdowns, which produce continuous sparks. This provides a dynamic interruption burn-in effect. After burn-in, the number of re-breakdowns decreases, and the withstand voltage is improved.

[0063] 3) Based on the actual interruption waveform of the vacuum interrupter, the peak envelope of the re-breakdown waveform can be obtained. Combined with the interruption stroke curve, the cold dielectric recovery curve of the interrupter can be obtained. The performance of the interrupter can also be analyzed based on the speed of the envelope rise time. The envelope is also significantly improved after aging.

[0064] The basic principles, main features and advantages of the present invention are shown and described above. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention.

[0065] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A dynamic breaking and aging method for vacuum interrupters based on multiple re-breakdowns, characterized by: The method includes the following: by causing multiple re-breakdowns on the contact surface during the breaking process, the weak points on the contact surface are eliminated, and the dielectric recovery strength is gradually improved; a simulation platform is built to obtain the breaking and re-breakdown waveforms under different rise times of the fracture; a dynamic breaking and aging test platform for the vacuum interrupter is built; after obtaining the re-breakdown waveform, the peak envelope of the re-breakdown waveform of the vacuum interrupter at this moment is obtained, and combined with the stroke curve, the cold-state dielectric recovery characteristic curve at this moment is obtained; the performance change trend of the vacuum interrupter is obtained by the obtained envelope, and the dynamic recovery voltage is applied to measure the dynamic recovery of the circuit breaker. Dynamic breakdown voltage: During the circuit breaker opening process, a recovery voltage with a certain rise time is generated at both ends of the break. This dynamic recovery voltage application method is applied to the vacuum circuit breaker opening process, and also includes a process of measuring the dynamic breakdown voltage circuit of the circuit breaker, which includes the following steps: before the test, the circuit breaker is in the open state, and a DC high-voltage source is used to charge the energy storage capacitor C1 and the impulse voltage divider C2. During the operation, the circuit breaker is closed and opened. After the closing operation is completed, the voltage across the impulse voltage divider C2 drops to the minimum, and then the circuit breaker starts the opening operation. The opening operation includes the following steps: S1. When the circuit breaker contacts are separated, the experimental circuit breaker CB is open, and the energy storage capacitor C1 charges the impulse voltage divider C2 again, and the voltage across the impulse voltage divider C2 rises rapidly; S2: When the voltage across the impulse voltage divider C2 is greater than the fracture breakdown voltage, the fracture breaks down, the impulse voltage divider C2 is short-circuited to the ground, and the voltage across the two ends drops rapidly; S3. After the arc between the circuit breaker breaks is extinguished, the impulse divider C2 is opened again, and the above process is repeated until the energy storage capacitor C1 charges the impulse divider C2 and can no longer cause the break to break down. During the breaking process, when the break voltage recovery strength is higher than the recovery voltage, the break does not break down again. During the breaking process, when the break voltage is quickly charged to the recovery voltage and reaches the voltage recovery strength, the break breaks down again. The break capacitance is very small and the arc is extinguished quickly. The break is quickly charged to the recovery voltage again and breaks down again when the voltage recovery strength is reached again. The breakdown is repeated many times until the voltage recovery strength exceeds the recovery voltage.

2. The dynamic breaking and aging method of a vacuum interrupter based on multiple re-breakdowns according to claim 1 is characterized in that: The performance of the vacuum interrupter at different times can be judged based on the rising speed of the vertex envelope of the vacuum interrupter. The faster the rising speed of the vertex envelope, the higher the curve, which means the performance of the interrupter is better; otherwise, the performance of the vacuum interrupter is worse.

3. The dynamic breaking and aging method of a vacuum interrupter based on multiple re-breakdowns according to claim 1 is characterized in that: The method also includes a special dynamic breaking test platform with adjustable rise time, in which a DC high-voltage power supply charges the energy storage capacitor Cs2 through a charging resistor Rs2, and a resistor divider FY2 is used to monitor the voltage of Cs2.

4. The method for dynamic breaking and aging of a vacuum interrupter based on multiple re-breakdowns according to claim 3, characterized in that: After the breaking circuit control switch GK2 is closed, the test circuit breaker SP is opened at no-load. Cs2 charges the recovery voltage capacitor Ck through the recovery voltage regulating resistor R1 to form an exponentially rising recovery voltage. After each arc extinction of the break, Ck can quickly charge the break capacitor through the break charging resistor R2 to synchronize with the recovery voltage. When the break insulation is insufficiently recovered, multiple restrikes will occur. The break insulation can be broken and aged by utilizing multiple restrikes and discharges.

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