Method and device for equivalent test of high-energy arc fault of transformer based on mechanical destruction of pulsed arc

Abstract

The application provides a transformer high-energy arc fault equivalent test method and device based on pulsed arc mechanical damage, the method comprising: obtaining power frequency arc parameters and initial pulsed arc parameters based on high-energy arc; performing first arc discharge based on the power frequency arc parameters to collect first wall pressure data and first strain data; performing second arc discharge based on the initial pulsed arc parameters to collect second wall pressure data and second strain data; and judging whether the discharge error of the two meets the error criterion; when the discharge error meets the error criterion, setting the initial pulsed arc parameters as equivalent pulsed arc parameters and performing the fault equivalent test of the high-energy arc. The method establishes the equivalent relationship of the damage effect of arc discharge in the power frequency power supply and pulsed power supply two modes on the test oil tank through discharge error comparison, obtains the equivalent discharge source of the high-energy arc based on pulsed arc discharge, and provides a research idea and test basis for the high-energy arc fault equivalent test of the ultra-high voltage transformer.

Description

Technical Field

[0001] This application relates to the field of explosion-proof technology for ultra-high voltage / extra-high voltage transformer tanks, specifically to an equivalent test method and device for high-energy arc faults in transformers based on mechanical damage caused by pulsed electric arcs. Background Technology

[0002] Power transformers are core equipment in power systems, and their safe and stable operation is crucial to the reliability and economy of the power system. Large power transformers typically use an insulation structure composed of transformer oil and cellulose paper / paperboard. When a high-energy electric arc fault occurs inside, it can easily cause the transformer tank to rupture, leading to a fire or explosion accident.

[0003] Currently, both domestic and international transformer tank explosion-proof designs are based on the static pressure calculation method recommended in IEEE Std C57.156-2016. This method is based on the ideal gas law, using the tank deformation caused by an arc producing a maximum energy of 20 MJ as a limit. Essentially, it calculates the static pressure rise process, which differs significantly from the actual pressure waveform generated by an arc. Although this standard only specifies the arc energy to be considered in the design of transformer tanks for voltage levels from 69kV to 765kV, and does not cover ultra-high voltage levels including 1000kV, ±800kV, and ±1100kV, the tank structure design of ultra-high voltage transformers and converter transformers in my country still follows this standard. In several transformer explosion accidents that have occurred, the measured maximum arc energy exceeded 80 MJ. If the static pressure method is still used for fault protection design of high-energy arcs exceeding 80 MJ, ultra-high voltage transformers will far exceed the transport weight and dimensional limits. Therefore, the existing transformer tank design methods and standards can no longer meet the actual engineering needs.

[0004] However, there are difficulties in designing, manufacturing and using high-energy power frequency current. The largest power frequency arc test platform in China uses five 6500MVA impulse generators as power sources, and its arc power is estimated to be at most 0.3GW, which is far lower than the arc power of more than 1GW when an actual UHV transformer fails. Summary of the Invention

[0005] This application addresses the problems existing in the prior art by providing an equivalent test method for high-energy arc faults in transformers based on the mechanical damage of pulsed arcs. By collecting wall pressure and strain data of the test tank wall during arc discharge in two modes—power frequency and pulsed—to compare the discharge errors of the two modes, an equivalent relationship between the destructive effects of arc discharge on the test tank under the two modes is established, and the equivalent discharge source of the high-energy arc based on pulsed arc discharge is obtained. This provides a research idea and experimental basis for the equivalent test of high-energy arc faults in UHV transformers.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: A transformer high-energy arc fault equivalent test method based on pulsed arc mechanical damage, applied to a fault equivalent test device, the equivalent test device including a test tank and an arc generator, the arc generator being installed inside the test tank; the method includes: obtaining power frequency arc parameters and initial pulsed arc parameters based on the high-energy arc; The arc generator is controlled based on the power frequency arc parameters to perform the first arc discharge for the first duration, and the first wall pressure data and the first strain data of the test oil tank are collected respectively. The arc generator is controlled to perform a second arc discharge for a second duration based on the initial pulse arc parameters, and the second wall pressure data and second strain data of the test oil tank are collected respectively; the second duration is not greater than the first duration; Based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data, determine whether the discharge error between the first arc discharge and the second arc discharge meets the error criterion; When the discharge error meets the error criterion, let the initial pulse arc parameters be the equivalent pulse arc parameters; Fault equivalent test of high-energy electric arc based on equivalent pulse electric arc parameters.

[0007] In some embodiments, the discharge error includes specific impulse error, strain energy density error and strain dominant frequency error; the error criteria include specific impulse criterion and strain energy density criterion and strain dominant frequency criterion; the specific impulse criterion indicates that the specific impulse error is not greater than a first preset value, the strain energy density criterion indicates that the strain energy density error is not greater than a second preset value, and the strain dominant frequency criterion indicates that the strain dominant frequency error is not greater than a third preset value. Based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data, determine whether the discharge error between the first and second arc discharges meets the error criteria, including: The specific impulse error is obtained based on the first wall pressure data and the second wall pressure data. The strain energy density error is obtained based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data. The strain principal frequency error is obtained based on the first strain data and the second strain data. Determine whether the specific impulse error, strain energy density error, and strain principal frequency error satisfy the specific impulse criterion, respectively.

[0008] In some embodiments, the specific impulse error is obtained based on the first wall pressure data and the second wall pressure data, including: The first specific impulse is obtained by integrating the first wall pressure data over time. The second specific impulse is obtained by integrating the second wall pressure data over time. The specific impulse deviation is obtained based on the difference between the first specific impulse and the second specific impulse; The specific impulse error is obtained by taking the absolute value of the ratio of the specific impulse deviation to the second specific impulse.

[0009] In some embodiments, the strain energy density error is obtained based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data, including: The first dynamic strain rate is obtained based on the first strain data; The second dynamic strain rate is obtained based on the second strain data; The first strain energy density is obtained by integrating the first dynamic strain rate based on the first wall pressure data; The second strain energy density is obtained by integrating the second dynamic strain rate based on the second wall pressure data; The strain energy density deviation is obtained based on the difference between the first strain energy density and the second strain energy density; The strain energy density error is obtained by taking the absolute value of the ratio of the strain energy density deviation to the second strain energy density.

[0010] In some embodiments, obtaining the strain principal frequency error based on the first strain data and the second strain data includes: Perform a fast Fourier transform on the first strain data to obtain the first spectral characteristics; The first strain principal frequency is obtained based on the first spectral characteristics; The second spectral characteristics are obtained by performing a fast Fourier transform on the second strain data; The second strain principal frequency is obtained based on the second spectral characteristics; The strain principal frequency deviation is obtained based on the difference between the first strain principal frequency and the second strain principal frequency; The strain dominant frequency error is obtained by taking the absolute value of the ratio of the strain dominant frequency deviation to the second strain dominant frequency.

[0011] In some embodiments, the discharge error satisfies the error criterion, which indicates that the specific impulse error satisfies the specific impulse criterion, the strain energy density error satisfies the strain energy density criterion, and the strain principal frequency error satisfies the strain principal frequency criterion.

[0012] In some embodiments, when the discharge error does not meet the error criterion, the initial pulse arc parameters are adjusted, and the second arc discharge for a second duration is repeatedly executed based on the initial pulse arc parameters to control the arc generator, and the second wall pressure data and the second strain data of the test tank are collected respectively.

[0013] In some embodiments, adjusting the initial pulse arc parameters includes adjusting at least one of the following: pulse current amplitude, pulse current rise time, pulse current fall time, pulse current duty cycle, or pulse frequency.

[0014] In some embodiments, fault equivalence tests of high-energy arcs are performed based on equivalent pulse arc parameters, including: Based on the equivalent pulse arc parameters, an arc energy fitting formula is constructed for high-energy arc discharge. The arc energy fitting formula characterizes the mapping relationship between pulse arc energy, pulse arc current peak value, pulse current rise time, and pulse current duration to arc energy.

[0015] Secondly, this application proposes an equivalent test device for transformer high-energy arc faults based on pulsed arc mechanical damage, which is used to perform an equivalent test method for transformer high-energy arc faults based on pulsed arc mechanical damage. The fault equivalent test device includes a test tank, an arc generator, a strain sensor, a displacement sensor, a pressure sensor, a power frequency current source, a pulse current source, and a data processor. The arc generator is installed inside the test oil tank; The strain sensor, displacement sensor, and pressure sensor are respectively installed on the wall of the test oil tank. The strain sensor and displacement sensor are used to collect the first wall pressure data and the second strain data of the test oil tank, and the pressure sensor is used to collect the first wall pressure data and the second wall pressure data of the test oil tank. The power frequency current source and the pulse current source are electrically isolated from each other, and the power frequency current source and the pulse current source are respectively connected to the arc generator; the power frequency current source is used to control the arc generator to perform a first arc discharge of a first duration based on the power frequency arc parameters; the pulse current source is used to control the arc generator to perform a second arc discharge of a second duration based on the initial pulse arc parameters. The data processor is connected to the arc generator, strain sensor, displacement sensor, pressure sensor, power frequency current source, and pulse current source, respectively. The data processor is used to acquire power frequency arc parameters and initial pulse arc parameters based on the high-energy arc, preset the first duration, the second duration, and the error criterion, and determine whether the discharge error between the first arc discharge and the second arc discharge meets the error criterion based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data. When the discharge error meets the error criterion, the initial pulse arc parameters are set to equivalent pulse arc parameters.

[0016] Compared with the prior art, this application has the following advantages: This application involves conducting arc discharge in two modes—power frequency and pulse—within a test tank, and collecting wall pressure and strain data of the tank wall to compare the discharge errors under the two modes. This establishes an equivalent relationship between the destructive effects of arc discharge under the two modes on the test tank, enabling the adjustment and confirmation of equivalent pulse arc parameters. The result is an equivalent discharge source for a high-energy arc based on pulse arc discharge, which is then used for fault equivalent testing of this high-energy arc. This provides a research approach and experimental basis for equivalent testing of high-energy arc faults in UHV transformers. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the equivalent test method for high-energy arc faults in transformers based on the mechanical damage caused by pulsed arcs, as described in this application. Figure 2 This is a schematic diagram of the structure of the transformer high-energy arc fault equivalent test device based on pulsed arc mechanical damage in this application.

[0018] The attached figures are labeled as follows: 10, test oil tank; 20, arc generator; 30, strain sensor; 40, displacement sensor; 50, pressure sensor; 60, power frequency current source; 61, first disconnecting switch; 62, first circuit breaker; 70, pulse current source; 71, second disconnecting switch; 72, second circuit breaker; 80, data processor. Detailed Implementation

[0019] Existing technologies include high-energy arc fault equivalent tests using explosive detonation. However, this method differs from the mechanism by which a high-energy arc in a transformer exerts pressure on the oil tank. The impact process of explosive detonation is uncontrollable, and the pressure waveform is difficult to accurately reproduce the pressure change pattern of a real arc. The test has poor repeatability and high safety risks, making it unsuitable for oil tank performance evaluation scenarios that require high-precision parameter matching.

[0020] Currently, pulsed arc testing technology is relatively mature, with peak currents reaching 5-10 times or even higher than power frequency arc currents. It also allows for more precise arc power control and higher repeatability in tank pressure testing. The numerous advantages of pulsed arcs make it possible to simulate the tank failure process caused by high-energy arcs in UHV transformers, such as 90MJ power frequency arc faults. Therefore, to explore equivalent testing methods for high-energy arc fault discharge in UHV transformers, this invention provides an equivalent testing method for power frequency arc faults in transformers based on the mechanical damage of pulsed arcs. This method facilitates the conduct of true arc discharge impact tests, practical exploration of high-energy arc pressure wave characteristics, and actual transformer impact resistance tests. It helps address the problem of UHV transformer combustion and explosion, further understands the destructive effect of arc pressure in oil on the tank, and thus provides research ideas and experimental methods for equivalent testing technology of 90MJ-level high-energy arcs.

[0021] To clearly illustrate the technical features of this solution, the implementation methods of this application will be described in detail below with reference to the accompanying drawings and embodiments. This will allow for a full understanding and implementation of how this application uses technical means to solve technical problems and achieve corresponding technical effects. The embodiments of this application and the various features within them can be combined with each other without conflict, and the resulting technical solutions are all within the protection scope of this application.

[0022] To achieve the above objectives, the technical solution adopted in this application is as follows: A transformer high-energy arc fault equivalent test method based on pulsed arc mechanical damage, applied to a fault equivalent test device, the equivalent test device including a test tank and an arc generator, the arc generator being installed inside the test tank; the method includes: obtaining power frequency arc parameters and initial pulsed arc parameters based on the high-energy arc; The parameters of the power frequency arc are used to characterize and adapt the arc energy of high-energy arcs for fault equivalent testing, and to control the arc discharge of the arc generator. Optionally, a 50Hz sine wave is used for the first arc discharge. The power frequency arc parameters include the capacitor charging voltage and the control thyristor conduction angle. The total energy stored in the capacitor is adjusted by adjusting the capacitor charging voltage, and the energy delivery time (first duration) is controlled by changing the control thyristor conduction angle of the sine wave output circuit, thereby adjusting the arc energy and enabling fault equivalent testing of high-energy arcs with different arc energies. Typically, when the capacitor charging voltage is 1.5kV, the first duration is 80ms.

[0023] The initial pulse arc parameters characterize the parameters of the pulse current source used to control the arc generator to generate an arc discharge.

[0024] Optionally, initial pulse arc parameters are obtained based on the arc energy of the high-energy arc to be used in the fault equivalent test, thereby improving the efficiency of obtaining equivalent pulse arc parameters. Specifically: When the arc energy is greater than the energy threshold, the initial pulse arc energy is obtained according to the first formula; the first formula is: ; in, The initial pulse arc energy, It is the energy of the electric arc; When the arc energy is greater than the energy threshold, the initial pulse arc energy is obtained according to the second formula; the second formula is: ; The initial pulse arc parameters are obtained based on the initial pulse arc energy. In other words, the initial pulse arc parameters characterize the parameters of the pulse current source that can obtain the initial pulse arc energy and is used to control the arc generator to generate arc discharge. Optionally, the energy threshold can be in the range of 600KJ to 700KJ.

[0025] The arc generator is controlled based on the power frequency arc parameters to perform the first arc discharge for the first duration, and the first wall pressure data and the first strain data of the test oil tank are collected respectively. The arc generator is controlled to perform a second arc discharge for a second duration based on the initial pulse arc parameters, and the second wall pressure data and second strain data of the test oil tank are collected respectively. The second duration includes the pulse current rise time and the pulse current fall time. The second duration is not greater than the first duration, that is, the total duration of the pulse current rise time and the pulse current fall time during the second arc discharge is not greater than the first duration. Based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data, determine whether the discharge error between the first arc discharge and the second arc discharge meets the error criterion; When the discharge error does not meet the error criterion, the initial pulse arc parameters are adjusted, and the second arc discharge for the second duration is repeatedly executed based on the initial pulse arc parameters to control the arc generator, and the second wall pressure data and the second strain data of the test oil tank are collected respectively. When the discharge error meets the error criterion, the initial pulse arc parameters are set to equivalent pulse arc parameters. The equivalent pulse arc parameters characterize the parameters of the pulse current source used to control the arc generator to generate arc discharge, which are adapted to the arc energy of the high-energy arc used in the fault equivalent test.

[0026] Fault equivalent tests of high-energy arcs based on equivalent pulse arc parameters can be conducted, such as high-energy arc discharge impact tests, to explore the characteristics of high-energy arc pressure waves, solve the problem of combustion and explosion in ultra-high voltage transformers, and further understand the destructive effect of arc pressure in oil on oil tanks.

[0027] By conducting arc discharge in two modes—power frequency and pulse—within the test tank and collecting wall pressure and strain data, the discharge errors of the two modes of arc discharge were compared. An equivalent relationship between the destructive effects of arc discharge in the two modes on the test tank was established, and the parameters of the equivalent pulsed arc were adjusted and confirmed. This yielded the equivalent discharge source of the high-energy arc based on pulsed arc discharge, enabling the conduct of fault equivalent tests on this high-energy arc. This provides a research approach and experimental basis for equivalent tests of high-energy arc faults in UHV transformers.

[0028] In some embodiments, the discharge error includes specific impulse error, strain energy density error, and strain dominant frequency error; the error criteria include specific impulse criterion, strain energy density criterion, and strain dominant frequency criterion; the specific impulse criterion indicates that the specific impulse error is not greater than a first preset value, the first preset value being in the range of 5% to 15%; the strain energy density criterion indicates that the strain energy density error is not greater than a second preset value, the second preset value being in the range of 5% to 15%; and the strain dominant frequency criterion indicates that the strain dominant frequency error is not greater than a third preset value, the third preset value being in the range of 15% to 25%.

[0029] Optionally, the first preset value is set to 10%, the second preset value is set to 10%, and the third preset value is set to 20%, which improves the adjustment efficiency and ensures the accuracy of the equivalent test. Based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data, determine whether the discharge error between the first and second arc discharges meets the error criteria, including: The specific impulse error is obtained based on the first wall pressure data and the second wall pressure data. The strain energy density error is obtained based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data. The strain principal frequency error is obtained based on the first strain data and the second strain data. Determine whether the specific impulse error, strain energy density error, and strain principal frequency error satisfy the specific impulse criterion, respectively.

[0030] By installing at least one pressure sensor on each side wall of the test tank, the average pressure value collected by each pressure sensor at each moment during arc discharge is used to obtain the wall pressure data at the corresponding moment. The arc discharge includes a first arc discharge and a second arc discharge, and the wall pressure data includes the corresponding first wall pressure data and second wall pressure data.

[0031] In some embodiments, the specific impulse error is obtained based on the first wall pressure data and the second wall pressure data, including: The first specific impulse is obtained by time integration based on the first wall pressure data. The first specific impulse characterizes the specific impulse generated by the arc pressure on the tank wall of the test oil tank during the first arc discharge of the arc generator for the first duration based on the power frequency arc parameters. The first specific impulse is: ; in, The first specific impulse, This is the first wall pressure data. The first duration; The second specific impulse is obtained by time integration based on the second wall pressure data. The second specific impulse characterizes the specific impulse generated by the arc pressure on the tank wall of the test oil tank when the arc generator is controlled to perform a second arc discharge for a second duration based on the initial pulse arc parameters. ; in, The second specific impulse, This is the second wall pressure data. This is the second duration; The specific impulse deviation is obtained based on the difference between the first specific impulse and the second specific impulse; The specific impulse error is obtained by taking the absolute value of the ratio of the specific impulse deviation to the second specific impulse. The specific impulse error is: ; in, This refers to the specific impulse error.

[0032] In some embodiments, the strain energy density error is obtained based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data, including: The first dynamic strain rate is obtained based on the first strain data. The first dynamic strain rate characterizes the rate of change of the strain of the test tank wall with the displacement of the tank wall when the arc generator is controlled by the power frequency arc parameters to perform the first arc discharge for the first duration. Similarly, by installing at least one strain gauge and displacement sensor combination on each side wall of the test tank, the strain value collected by each strain gauge at each moment is averaged to obtain the strain of the tank wall at the corresponding moment when the arc discharge is performed, and the displacement value collected by each displacement sensor at each moment is averaged to obtain the displacement of the tank wall at the corresponding moment.

[0033] The second dynamic strain rate is obtained based on the second strain data. The second dynamic strain rate characterizes the rate of change of the strain of the test tank wall with the displacement of the tank wall when the arc generator is controlled to perform a second arc discharge for a second duration based on the initial pulse arc parameters. The first strain energy density is obtained by integrating the first dynamic strain rate based on the first wall pressure data; the first strain energy density is: ; in, The first strain energy density, The first dynamic strain rate; The second strain energy density is obtained by integrating the second dynamic strain rate based on the second wall pressure data; the second strain energy density is: ; in, The second strain energy density, This is the second dynamic strain rate; The strain energy density deviation is obtained based on the difference between the first strain energy density and the second strain energy density; The strain energy density error is obtained by taking the absolute value of the ratio of the strain energy density deviation to the second strain energy density. The strain energy density error is: ; in, This represents the strain energy density error.

[0034] In some embodiments, obtaining the strain principal frequency error based on the first strain data and the second strain data includes: Perform a fast Fourier transform on the first strain data to obtain the first spectral characteristics; The first strain dominant frequency is obtained based on the first spectral characteristics. The first strain dominant frequency characterizes the main strain frequency of the box wall when the arc generator performs a first arc discharge of a first duration based on the power frequency arc parameters. The second spectral characteristics are obtained by performing a fast Fourier transform on the second strain data; The second strain main frequency is obtained based on the second spectral characteristics. The second strain main frequency characterizes the main frequency of the strain of the box wall when the arc generator performs a second arc discharge of the second duration based on the initial pulse arc parameters. Specifically, the following applies to obtaining both the first and second strain principal frequencies: Preprocess the time-domain data of the box wall strain, such as detrending and noise reduction, zero padding to adjust the data length of the box wall strain to a power of 2, and use window functions such as the Hanning window to reduce spectral leakage. The FFT function, or Fast Fourier Transform, is called to transform the preprocessed data. The first half of the transformed result is taken to eliminate negative frequency mirroring, and the strain amplitude is corrected according to the correction rules. The correction rules are: the amplitude at DC and Nyquist frequencies is multiplied by 1 / N, and the amplitude at other frequencies is multiplied by 2 / N to obtain the true strain amplitude.

[0035] The corresponding frequency axis is generated by using the fftfreq function, which is the FFT frequency axis generation function, and the strain spectrum is plotted. The horizontal axis corresponding to the peak point with the highest amplitude in the spectrum is the main strain frequency of the box wall strain.

[0036] The strain principal frequency deviation is obtained based on the difference between the first strain principal frequency and the second strain principal frequency; The strain principal frequency error is obtained by taking the absolute value of the ratio of the strain principal frequency deviation to the second strain principal frequency. The strain principal frequency error is: ; in, To compensate for the strain principal frequency error, The first strain principal frequency, This is the second dominant strain frequency.

[0037] In some embodiments, the discharge error satisfies the error criterion, which indicates that the specific impulse error satisfies the specific impulse criterion, the strain energy density error satisfies the strain energy density criterion, and the strain principal frequency error satisfies the strain principal frequency criterion.

[0038] Optionally, when , and At this time, the discharge error satisfies the error criterion, that is, the initial pulse arc parameters are taken as the equivalent pulse arc parameters.

[0039] when At the same time, the second specific impulse can be increased by increasing the bus voltage of the pulse current source and / or accelerating the switching closing speed of the IGBT full-bridge inverter module.

[0040] when At the same time, by increasing the voltage of the pulse current source to change the second wall voltage data, accelerating the switching and disconnection speed of the IGBT full-bridge inverter module, and increasing the charging voltage of the energy storage capacitor module, the second strain energy density can be improved. when At the same time, the on-time and off-time of the IGBT full-bridge inverter module switching transistors are adjusted to regulate the duty cycle of the pulse current; the switching frequency of the IGBT full-bridge inverter module is adjusted to regulate the pulse arc frequency and control the change of the second strain main frequency; and the inductance value of the inductor buffer isolation module is reduced to accelerate the rise time and fall time of the pulse current, thereby increasing the second strain main frequency.

[0041] In some embodiments, adjusting the initial pulse arc parameters includes adjusting at least one of the following: pulse current amplitude, pulse current rise time, pulse current fall time, pulse current duty cycle, or pulse frequency.

[0042] The pulse current amplitude is positively correlated with the pressure amplitude in the chamber wall pressure data. By changing the pulse power discharge energy and pulse current rise rate of the arc discharge based on pulse mode, the pulse current amplitude injected into the test tank can be changed, thereby realizing the change of the pressure amplitude in the chamber wall pressure data, and thus realizing the adjustment of the second specific impulse.

[0043] In some embodiments, fault equivalence tests of high-energy arcs are performed based on equivalent pulse arc parameters, including: Based on equivalent pulsed arc parameters, a fitting equation for the arc energy during high-energy arc discharge is constructed. This equation characterizes the mapping relationship between the pulsed arc energy, the peak value of the pulsed arc current, the rise time of the pulsed current, and the duration of the pulsed current, and the arc energy. The arc energy fitting equation is as follows: ; in, The relationship between electric arc energy and its fitting. To control the pulse arc energy during arc discharge using an arc generator based on equivalent pulse arc parameters, To control the peak value of the pulsed arc current during arc discharge using an arc generator based on equivalent pulsed arc parameters. To control the rise time of the pulse current during arc discharge using an arc generator based on equivalent pulse arc parameters. The duration of the pulse current during arc discharge is controlled by the arc generator based on the equivalent pulse arc parameters.

[0044] Secondly, this application proposes an equivalent test device for transformer high-energy arc faults based on pulsed arc mechanical damage, which is used to perform an equivalent test method for transformer high-energy arc faults based on pulsed arc mechanical damage. The fault equivalent test device includes a test tank 10, an arc generator 20, a strain sensor 30, a displacement sensor 40, a pressure sensor 50, a power frequency current source 60, a pulse current source 70, and a data processor 80. The arc generator 20 is installed inside the test oil tank 10. The test oil tank 10 is made with the same scale as the transformer oil tank. The arc generator 20 includes two arc-initiating electrodes and an arc-initiating wire connected between the two arc-initiating electrodes. Strain sensor 30, displacement sensor 40 and pressure sensor 50 are respectively installed on the wall of the test oil tank. Strain sensor 30 and displacement sensor 40 are used to collect the first strain data and the second strain data of the test oil tank, and pressure sensor is used to collect the first wall pressure data and the second wall pressure data of the test oil tank. The power frequency current source 60 and the pulse current source 70 are electrically isolated from each other, and are respectively connected to the arc generator 20. Specifically, both the power frequency current source 60 and the pulse current source 70 are connected to the power supply input terminal of the arc generator 20. The power frequency current source 60 is used to control the arc generator 20 to perform a first arc discharge of a first duration based on the power frequency arc parameters. The pulse current source 70 is used to control the arc generator 20 to perform a second arc discharge of a second duration based on the initial pulse arc parameters. The power frequency current source 60 is connected to the arc generator 20 by the first circuit breaker 62 and the first disconnecting switch 61; The pulse current source 70 is connected to the arc generator 20 via the second circuit breaker 72 and the second disconnecting switch 71.

[0045] To control the total deformation energy of the oil tank, the circuit breaker and the disconnecting switch work together to turn on and off the corresponding power supply and to isolate it under normal conditions. Specifically, the first circuit breaker 62 and the first disconnecting switch 61 correspond to the power frequency current source 60, and the second circuit breaker 72 and the second disconnecting switch 71 correspond to the pulse current source 70. After the arc time length requirement is met, the circuit breaker is used to cut off the corresponding power supply, thereby controlling the arc time length of the experiment, avoiding mutual interference between power supplies, and controlling the arc time of the pulse arc.

[0046] The data processor 80 is connected to the strain sensor 30, displacement sensor 40, pressure sensor 50, power frequency current source 60, and pulse current source 70, respectively. The data processor 80 is used to acquire power frequency arc parameters and initial pulse arc parameters based on high-energy arc, preset a first duration, a second duration, and an error criterion, and determine whether the discharge error between the first arc discharge and the second arc discharge meets the error criterion based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data. When the discharge error meets the error criterion, the initial pulse arc parameters are set to equivalent pulse arc parameters.

[0047] The pulse current source 70 includes a power factor correction module (PFC), an LCC series-parallel resonant converter module, an energy storage capacitor module, an inductor buffer isolation module, and an IGBT full-bridge inverter module.

[0048] The power factor correction module is used to adjust the output voltage of the pulse current source to change the DC bus amplitude, thereby achieving coarse adjustment of the pulse current amplitude.

[0049] The LCC series-parallel resonant converter module includes a resonant inductor, a series capacitor, and a parallel capacitor. By adjusting the switching frequency, the operating mode of the LCC series-parallel resonant converter module, such as DCM or CCM mode, can be changed to adjust the energy transfer efficiency. Simultaneously, changes in the switching frequency directly affect the current build-up and decay rate in the resonant circuit of the LCC series-parallel resonant converter module, thereby changing the output arc current pulse width. This allows control of the upward current rise rate related to the arc channel expansion rate, altering the waveform characteristics of the pressure wave formed by the pulsed arc, and achieving control of the specific impulse of the arc pressure wave acting on the tank wall. The capacitor ratio can also be adjusted... Change the charging voltage characteristics, among which, The capacitance value of the parallel capacitors. The capacitance values ​​of the series capacitor and the parallel capacitor work together to finely adjust the amplitude of the pulse current. At the same time, the resonant parameters determine the rising characteristics of the charging current, thereby affecting the rise time of the pulse current. The resonant parameters include the inductance value of the resonant inductor, the capacitance value of the series capacitor, and the capacitance value of the parallel capacitor.

[0050] The energy storage capacitor module is used to set the pulse arc energy. The charging voltage of the energy storage capacitor module directly determines the discharge current amplitude, thereby realizing the setting of the pulse arc energy.

[0051] The inductor buffer isolation module is used to adjust the rise time and / or fall time of the pulse current; the inductance value of the inductor buffer isolation module suppresses the rate of change of the discharge current, thereby affecting the rise time and / or fall time of the pulse current.

[0052] The IGBT full-bridge inverter module is used to adjust the pulse current duty cycle, pulse frequency, pulse current rise time, and / or pulse current fall time. The pulse current duty cycle, i.e., the pulse current waveform pulse width, is adjusted by controlling the on / off time of the IGBT full-bridge inverter module's switching transistors; the pulse frequency is adjusted by changing the switching frequency of the IGBT full-bridge inverter module; and the pulse current rise time and / or pulse current fall time is adjusted by changing the switching speed of the IGBT full-bridge inverter module.

[0053] The fault equivalent test device also includes an acoustic emission crack detector, which can optionally be installed at weak points in the connection such as welds of the test oil tank. Based on the test results of the acoustic emission crack detector, determine whether the yield limit of the test tank wall exceeds the yield failure limit of the tank wall material. If the yield strength of the test tank wall exceeds the yield failure limit of the tank wall material, the test tank cannot be used to carry out the fault equivalent test proposed in this application. That is, the test tank does not have the ability to carry out the fault equivalent test and the test tank needs to be replaced in time. If the yield strength of the test tank wall does not exceed the yield failure limit of the tank wall material, the test tank can undergo the fault equivalence test proposed in this application.

[0054] Those skilled in the art will understand that embodiments of this application can be provided as methods, apparatus (systems), or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of this application can be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0055] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce an instruction that executes via the processor of the computer or other programmable data processing apparatus to create an instruction for implementing the flowchart. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0056] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0057] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0058] Finally, it should be noted that the above content is only used to illustrate the technical solution of this application, and is not intended to limit the scope of protection of this application. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of this application shall not depart from the substance and scope of the technical solution of this application.

Claims

1. A method for equivalent testing of high-energy arc faults in transformers based on mechanical damage caused by pulsed electric arcs, characterized in that, The method is applied to a fault equivalent testing device, which includes a test tank and an arc generator, with the arc generator installed inside the test tank; the method includes: acquiring power frequency arc parameters and initial pulse arc parameters based on a high-energy arc. Based on the power frequency arc parameters, the arc generator is controlled to perform a first arc discharge for a first duration, and the first wall pressure data and the first strain data of the test oil tank are collected respectively. Based on the initial pulse arc parameters, the arc generator is controlled to perform a second arc discharge for a second duration, and the second wall pressure data and second strain data of the test oil tank are collected respectively; the second duration is not greater than the first duration; Based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data, determine whether the discharge error between the first arc discharge and the second arc discharge meets the error criterion; When the discharge error satisfies the error criterion, the initial pulse arc parameters are set to equivalent pulse arc parameters; The fault equivalent test of the high-energy arc is carried out based on the equivalent pulse arc parameters.

2. The equivalent test method for high-energy arc faults in transformers based on pulsed arc mechanical damage according to claim 1, characterized in that, The discharge error includes specific impulse error, strain energy density error, and strain dominant frequency error; the error criteria include specific impulse criterion, strain energy density criterion, and strain dominant frequency criterion; the specific impulse criterion indicates that the specific impulse error is not greater than a first preset value, the strain energy density criterion indicates that the strain energy density error is not greater than a second preset value, and the strain dominant frequency criterion indicates that the strain dominant frequency error is not greater than a third preset value; Based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data, determine whether the discharge error between the first arc discharge and the second arc discharge meets the error criterion, including: The specific impulse error is obtained based on the first wall pressure data and the second wall pressure data; The strain energy density error is obtained based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data; The strain principal frequency error is obtained based on the first strain data and the second strain data; Determine whether the specific impulse error, the strain energy density error, and the strain principal frequency error satisfy the specific impulse criterion, respectively.

3. The equivalent test method for high-energy arc faults in transformers based on pulsed arc mechanical damage according to claim 2, characterized in that, The specific impulse error is obtained based on the first wall pressure data and the second wall pressure data, including: The first specific impulse is obtained by integrating the first wall pressure data over time. The second specific impulse is obtained by integrating the second wall pressure data over time. The specific impulse deviation is obtained based on the difference between the first specific impulse and the second specific impulse; The specific impulse error is obtained by taking the absolute value of the ratio of the specific impulse deviation to the second specific impulse.

4. The equivalent test method for high-energy arc faults in transformers based on pulsed arc mechanical damage according to claim 2, characterized in that, The strain energy density error is obtained based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data, including: The first dynamic strain rate is obtained based on the first strain data; The second dynamic strain rate is obtained based on the second strain data; The first strain energy density is obtained by integrating the first dynamic strain rate based on the first wall pressure data. The second strain energy density is obtained by integrating the second dynamic strain rate based on the second wall pressure data; The strain energy density deviation is obtained based on the difference between the first strain energy density and the second strain energy density; The strain energy density error is obtained by taking the absolute value of the ratio of the strain energy density deviation to the second strain energy density.

5. The equivalent test method for high-energy arc faults in transformers based on pulsed arc mechanical damage according to claim 2, characterized in that, The strain principal frequency error is obtained based on the first strain data and the second strain data, including: Perform a fast Fourier transform on the first strain data to obtain the first spectral characteristics; The first strain principal frequency is obtained based on the first spectral characteristics; Perform a fast Fourier transform on the second strain data to obtain the second spectral characteristics; The second strain principal frequency is obtained based on the second spectral characteristics; The strain dominant frequency deviation is obtained based on the difference between the first strain dominant frequency and the second strain dominant frequency; The strain principal frequency error is obtained by taking the absolute value of the ratio of the strain principal frequency deviation to the second strain principal frequency.

6. The equivalent test method for high-energy arc faults in transformers based on mechanical damage caused by pulsed arcs, as described in any one of claims 2-5, is characterized in that... The discharge error satisfies the error criterion, indicating that the specific impulse error satisfies the specific impulse criterion, the strain energy density error satisfies the strain energy density criterion, and the strain principal frequency error satisfies the strain principal frequency criterion.

7. The equivalent test method for high-energy arc faults in transformers based on pulsed arc mechanical damage according to claim 1, characterized in that, When the discharge error does not meet the error criterion, the initial pulse arc parameters are adjusted, and the second arc discharge for a second duration is repeatedly executed based on the initial pulse arc parameters, while the second wall pressure data and the second strain data of the test oil tank are collected respectively.

8. The equivalent test method for high-energy arc faults in transformers based on pulsed arc mechanical damage according to claim 7, characterized in that, Adjusting the initial pulse arc parameters includes: adjusting at least one of the following: pulse current amplitude, pulse current rise time, pulse current fall time, pulse current duty cycle, or pulse frequency.

9. The equivalent test method for high-energy arc faults in transformers based on pulsed arc mechanical damage according to claim 1, characterized in that, Based on the equivalent pulse arc parameters, a fault equivalent test of the high-energy arc is performed, including: Based on the equivalent pulsed arc parameters, an arc energy fitting formula is constructed for the high-energy arc discharge. The arc energy fitting formula characterizes the mapping relationship between the pulsed arc energy, the peak value of the pulsed arc current, the rise time of the pulsed current, and the duration of the pulsed current and the arc energy.

10. An equivalent test device for high-energy arc faults in transformers based on pulsed arc mechanical damage, characterized in that, The fault equivalent test device for performing the transformer high-energy arc fault equivalent test method based on pulsed arc mechanical damage according to any one of claims 1-9 includes a test tank, an arc generator, a strain sensor, a displacement sensor, a pressure sensor, a power frequency current source, a pulsed current source, and a data processor. The electric arc generator is installed inside the test oil tank; The strain sensor, the displacement sensor, and the pressure sensor are respectively installed on the wall of the test oil tank. The strain sensor and the displacement sensor are used to collect the first wall pressure data and the second strain data of the test oil tank, and the pressure sensor is used to collect the first wall pressure data and the second wall pressure data of the test oil tank. The power frequency current source and the pulse current source are electrically isolated from each other, and the power frequency current source and the pulse current source are respectively connected to the arc generator; the power frequency current source is used to control the arc generator to perform a first arc discharge of a first duration based on the power frequency arc parameters; The pulse current source is used to control the arc generator to perform a second arc discharge of a second duration based on the initial pulse arc parameters. The data processor is connected to the arc generator, strain sensor, displacement sensor, pressure sensor, power frequency current source, and pulse current source, respectively. The data processor is used to acquire power frequency arc parameters and initial pulse arc parameters based on the high-energy arc, preset a first duration, a second duration, and an error criterion, determine whether the discharge error between the first arc discharge and the second arc discharge meets the error criterion based on the first wall pressure data, the first strain data, the second wall pressure data, and the second strain data, and set the initial pulse arc parameters to equivalent pulse arc parameters when the discharge error meets the error criterion.

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