High-frequency harmonic resistance test method and device for key equipment of flexible direct current power transmission system

Abstract

The application provides a kind of flexible direct current transmission system key equipment high frequency harmonic resistance test method and device, it is related to electric power equipment insulation test technical field.The method includes: obtaining the multiple sets of voltage waveforms that flexible direct current transmission system key equipment withstands under actual operation condition, carries out frequency domain analysis to each voltage waveform, extracts amplitude-frequency characteristic;Based on the dielectric loss power of each harmonic calculated based on amplitude-frequency characteristic;Equivalent loss power is determined based on the dielectric loss power of each harmonic using the principle of thermal effect;Based on the dielectric loss power of each harmonic and amplitude-frequency characteristic, the test waveform frequency is selected in target frequency band, and the test voltage effective value is calculated based on equivalent loss power and test waveform frequency;Based on test waveform frequency and test voltage effective value, high frequency harmonic resistance test is carried out on key equipment;The application solves the problem that the existing test method for checking the insulation performance of the equipment cannot meet the high reliability engineering requirements of flexible direct current transmission project.

Description

Technical Field

[0001] This invention relates to the field of insulation testing technology for power equipment, specifically to a method and apparatus for high-frequency harmonic withstand testing of key equipment in a flexible DC transmission system. Background Technology

[0002] The insulation reliability of key equipment (such as wall bushings and DC voltage dividers) in flexible DC transmission systems affects the safe and stable operation of the entire transmission system. With the widespread application of fully controlled power electronic devices in DC transmission systems, their high-frequency switching processes generate abundant high-frequency harmonic components. This causes these key devices to operate in a complex harmonic environment for extended periods, resulting in significantly increased dielectric losses, severe internal insulation heating, accelerated thermal aging of insulation materials, and the risk of thermal breakdown. This poses a serious technical challenge to the operational reliability of the equipment.

[0003] However, current testing methods for evaluating the insulation performance of equipment focus on insulation assessments such as temperature rise tests, power frequency withstand voltage tests, and lightning impulse tests. Temperature rise and power frequency withstand voltage tests are designed based on traditional power frequency steady-state conditions, failing to consider the influence of high-frequency harmonic components. Therefore, it is difficult to accurately assess the thermal stability and long-term thermal aging risk of bushings operating in high-frequency harmonic environments. Traditional impulse withstand voltage tests, such as lightning impulse and switching impulse tests, use standard impulse waveforms, resulting in test results that cannot truly reflect the equipment's insulation tolerance to high-frequency harmonic voltages. Therefore, existing testing methods for evaluating the insulation performance of equipment cannot meet the high reliability engineering requirements of flexible DC transmission projects. Summary of the Invention

[0004] In order to overcome the problem that the existing test methods for evaluating the insulation performance of equipment cannot meet the high reliability requirements of flexible DC transmission projects, this invention provides a high-frequency harmonic withstand test method and device for key equipment in flexible DC transmission systems.

[0005] On one hand, the present invention provides a high-frequency harmonic withstand test method for key equipment in a flexible DC transmission system, comprising: The voltage waveforms of key equipment under multiple actual operating conditions of the flexible DC transmission system are obtained, and frequency domain analysis is performed on each voltage waveform to extract the corresponding amplitude-frequency characteristics. The dielectric loss power of each harmonic under each voltage waveform is calculated based on the amplitude-frequency characteristics of each voltage waveform; the equivalent loss power of the high-frequency harmonic withstand test of the key equipment is determined based on the dielectric loss power of each harmonic using the thermal effect equivalence principle. Based on the amplitude-frequency characteristics and dielectric loss power of each harmonic, the test waveform frequency is selected in the target frequency band, and the effective value of the test voltage for the high-frequency harmonic withstand test of the key equipment is calculated based on the equivalent loss power and the test waveform frequency. Based on the test waveform formed by the frequency of the test waveform and the effective value of the test voltage, a high-frequency harmonic tolerance test is conducted on the key equipment to evaluate its high-frequency harmonic tolerance capability.

[0006] Optionally, multiple voltage waveforms are acquired for each set of actual operating conditions; the amplitude-frequency characteristics include the amplitude spectrum and the amplitude distribution characteristics under each frequency component; frequency domain analysis is performed on each voltage waveform to extract the corresponding amplitude-frequency characteristics, including: For any one of the multiple voltage waveforms that the key equipment is subjected to under each set of actual operating conditions, perform a fast Fourier transform on the voltage waveform to obtain the corresponding amplitude spectrum; Statistical analysis was performed on the amplitude spectra of multiple voltage waveforms under actual operating conditions of each group to obtain the amplitude distribution characteristics of each frequency component.

[0007] Optionally, for each frequency component, the dielectric loss power under its individual action is taken as the dielectric loss power of the corresponding harmonic and calculated according to the following formula:

[0008] in, For the first Dielectric loss power of subharmonics For the first RMS value of subharmonic voltage The fundamental angular frequency, For harmonic order, This refers to the tangent of the dielectric loss angle of the critical equipment. This refers to the capacitance value of critical equipment.

[0009] Optionally, the test waveform frequency is selected in the target frequency band based on the amplitude-frequency characteristics and the dielectric loss of each harmonic, including: For each amplitude spectrum, calculate the dielectric loss power under the individual action of each frequency component in the amplitude spectrum to obtain the corresponding dielectric loss power spectrum; Based on the amplitude distribution characteristics of each frequency component, the target frequency band is determined; for each amplitude spectrum, the top n frequencies in the target frequency band are selected as candidate frequencies in descending order of amplitude, where n is an integer greater than 1. In the dielectric loss power spectrum corresponding to this amplitude spectrum, the frequency with the largest dielectric loss power among the candidate frequencies is taken as the target frequency corresponding to this amplitude spectrum; The target frequencies corresponding to the amplitude spectra of multiple voltage waveforms under multiple actual operating conditions are statistically analyzed, and the frequency that appears most frequently is determined as the frequency of the test waveform.

[0010] Optionally, the determination of the equivalent loss power for the high-frequency harmonic withstand test of key equipment based on the dielectric loss power of each harmonic, using the principle of thermal effect equivalence, includes: Based on the statistical analysis of the dielectric loss power of each harmonic in each voltage waveform under the actual operating conditions of each group, the dielectric loss power of key equipment is determined. Based on the equivalent relationship between the cumulative thermal effect generated by multiple sets of actual operating voltage waveforms acting on key equipment and the thermal effect generated by a single frequency sinusoidal voltage, the dielectric loss power of the key equipment is taken as the equivalent loss power of the key equipment in the high-frequency harmonic withstand test at the test waveform frequency.

[0011] Optionally, based on statistical analysis of the dielectric loss power of each harmonic in each voltage waveform under each group of actual operating conditions, the dielectric loss power of key equipment is determined, including: For any one of the multiple voltage waveforms under each actual operating condition, the sum of the dielectric loss power of each harmonic in the voltage waveform is taken as the total loss power corresponding to the voltage waveform. For each set of actual operating conditions, the dielectric loss power under each voltage waveform in the set of actual operating conditions is determined by fusing the total loss power. Based on statistical analysis of the media loss power under actual operating conditions of each group, the media loss power of key equipment is determined.

[0012] Optionally, based on statistical analysis of the dielectric loss power under actual operating conditions of each group, the dielectric loss power of key equipment is determined, including: If the media loss power under the actual operating conditions of each group has a statistical regularity within the target operating power range, the relationship between the media loss power and the operating power of the key equipment is fitted based on the media loss power under the actual operating conditions of each group. Based on this relationship, the maximum media loss power within the target operating power range is determined. Based on this maximum media loss power and the preset safety margin, the media loss power of the key equipment is determined. If there is no statistical regularity in the media loss power under the actual operating conditions of each group within the target operating power range, the media loss power of the key equipment is determined based on the fusion result of the media loss power under the actual operating conditions of each group and the preset safety margin.

[0013] Optionally, the effective value of the test voltage is calculated using the following formula:

[0014]

[0015] in, This refers to the effective value of the test voltage for critical equipment. This refers to the equivalent power loss of key equipment. For the fundamental frequency of flexible DC transmission systems, For the test waveform frequency of key equipment, The dominant harmonic order corresponding to the frequency of the test waveform. The fundamental angular frequency, This refers to the tangent of the dielectric loss angle of the critical equipment. This refers to the capacitance value of critical equipment.

[0016] Optionally, a high-frequency harmonic withstand test is performed on the key equipment based on the test voltage waveform formed by the test waveform frequency and the effective value of the test voltage, to evaluate the high-frequency harmonic withstand capability of the key equipment, including: Based on the test waveform frequency and the effective value of the test voltage, a test voltage waveform is applied to the key equipment, and the equipment is continuously operated until it reaches a thermally stable state, and then maintained in the thermally stable state for a specified time. Measure the insulation performance parameters of key equipment and evaluate the high-frequency harmonic tolerance of key equipment based on the measurement results.

[0017] On the other hand, the present invention also provides a high-frequency harmonic withstand test device for key equipment in a flexible DC transmission system, comprising: The frequency domain analysis module is used to obtain the voltage waveforms of key equipment under multiple actual operating conditions of the flexible DC transmission system, perform frequency domain analysis on each voltage waveform, and extract the corresponding amplitude-frequency characteristics. The loss calculation module is used to calculate the dielectric loss power of each harmonic under each voltage waveform based on the amplitude-frequency characteristics of each voltage waveform; and to determine the equivalent loss power of the high-frequency harmonic withstand test of key equipment based on the dielectric loss power of each harmonic using the thermal effect equivalence principle. The parameter determination module is used to select the test waveform frequency in the target frequency band based on the amplitude-frequency characteristics and the dielectric loss power of each harmonic, and to calculate the effective value of the test voltage for the high-frequency harmonic withstand test of the key equipment based on the equivalent loss power and the test waveform frequency. The test module is used to conduct high-frequency harmonic tolerance tests on key equipment based on the test voltage waveform formed by the test waveform frequency and the effective value of the test voltage, and to evaluate the high-frequency harmonic tolerance capability of the key equipment.

[0018] Optionally, multiple voltage waveforms are acquired for each set of actual operating conditions; the amplitude-frequency characteristics include the amplitude spectrum and the amplitude distribution characteristics of each frequency component; the frequency domain analysis module is specifically used for: For any one of the multiple voltage waveforms that the key equipment is subjected to under each set of actual operating conditions, perform a fast Fourier transform on the voltage waveform to obtain the corresponding amplitude spectrum; Statistical analysis was performed on the amplitude spectra of multiple voltage waveforms under actual operating conditions of each group to obtain the amplitude distribution characteristics of each frequency component.

[0019] Optionally, for each frequency component, the dielectric loss power under its individual action is taken as the dielectric loss power of the corresponding harmonic and calculated according to the following formula:

[0020] in, For the first Dielectric loss power of subharmonics For the first RMS value of subharmonic voltage The fundamental angular frequency, For harmonic order, This refers to the tangent of the dielectric loss angle of the critical equipment. This refers to the capacitance value of critical equipment.

[0021] Optionally, the parameter determination module includes a frequency filtering submodule, which is used for: For each amplitude spectrum, calculate the dielectric loss power under the individual action of each frequency component in the amplitude spectrum to obtain the corresponding dielectric loss power spectrum; Based on the amplitude distribution characteristics of each frequency component, the target frequency band is determined; for each amplitude spectrum, the top n frequencies in the target frequency band are selected as candidate frequencies in descending order of amplitude, where n is an integer greater than 1. In the dielectric loss power spectrum corresponding to this amplitude spectrum, the frequency with the largest dielectric loss power among the candidate frequencies is taken as the target frequency corresponding to this amplitude spectrum; The target frequencies corresponding to the amplitude spectra of multiple voltage waveforms under multiple actual operating conditions are statistically analyzed, and the frequency that appears most frequently is determined as the frequency of the test waveform.

[0022] Optionally, the loss calculation module includes: The calculation submodule is used to determine the dielectric loss power of key equipment based on the statistical analysis of the dielectric loss power of each harmonic in each voltage waveform under each group's actual operating conditions. The equivalent submodule is used to establish the equivalent relationship between the cumulative thermal effect generated by multiple sets of actual operating condition voltage waveforms acting on key equipment and the thermal effect generated by a single frequency sinusoidal voltage. The dielectric loss power of the key equipment is used as the equivalent loss power of the key equipment in the high-frequency harmonic withstand test at the test waveform frequency.

[0023] Optionally, the computing submodule includes: The calculation subunit is used to sum the dielectric loss power of each harmonic in any one of the multiple voltage waveforms under each group of actual operating conditions as the total loss power corresponding to that voltage waveform; for each group of actual operating conditions, the dielectric loss power under that group of actual operating conditions is determined by fusing the total loss power corresponding to each voltage waveform under that group of actual operating conditions. The statistical analysis subunit is used to determine the media loss power of key equipment based on the statistical analysis of the media loss power under the actual operating conditions of each group.

[0024] Optionally, the statistical analysis subunit is specifically used for: If the media loss power under the actual operating conditions of each group has a statistical regularity within the target operating power range, the relationship between the media loss power and the operating power of the key equipment is fitted based on the media loss power under the actual operating conditions of each group. Based on this relationship, the maximum media loss power within the target operating power range is determined. Based on this maximum media loss power and the preset safety margin, the media loss power of the key equipment is determined. If there is no statistical regularity in the media loss power under the actual operating conditions of each group within the target operating power range, the media loss power of the key equipment is determined based on the fusion result of the media loss power under the actual operating conditions of each group and the preset safety margin.

[0025] Optionally, the effective value of the test voltage is calculated using the following formula:

[0026]

[0027] in, This refers to the effective value of the test voltage for critical equipment. This refers to the equivalent power loss of key equipment. For the fundamental frequency of flexible DC transmission systems, For the test waveform frequency of key equipment, The dominant harmonic order corresponding to the frequency of the test waveform. The fundamental angular frequency, This refers to the tangent of the dielectric loss angle of the critical equipment. This refers to the capacitance value of critical equipment.

[0028] Optionally, the test module is specifically used for: Based on the test waveform frequency and the effective value of the test voltage, a test voltage waveform is applied to the key equipment, and the equipment is continuously operated until it reaches a thermally stable state, and then maintained in the thermally stable state for a specified time. Measure the insulation performance parameters of key equipment and evaluate the high-frequency harmonic tolerance of key equipment based on the measurement results.

[0029] On the other hand, the present invention also provides an electronic device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, the method described in any of the foregoing is implemented.

[0030] On the other hand, the present invention also provides a readable storage medium having an executable program stored thereon, wherein when the executable program is executed, it implements the method described in any one of the above.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a method and apparatus for high-frequency harmonic withstand testing of key equipment in a flexible DC transmission system. By acquiring multiple sets of voltage waveforms subjected to the key equipment under actual operating conditions and performing frequency domain analysis, the amplitude-frequency characteristics of the equipment in a complex harmonic environment can be extracted. Based on this, the dielectric loss power of each harmonic is calculated based on the amplitude-frequency characteristics of each voltage waveform, converting the spectral information into a physical quantity that directly reflects the thermal effect, realizing a quantitative mapping from voltage waveform to insulation thermal load. Furthermore, the equivalent loss power of the high-frequency harmonic withstand test of the key equipment is determined using the principle of thermal effect equivalence. The complex cumulative thermal effect of multiple operating conditions and multiple frequency components in the field is equivalent to the loss power at a single frequency. This preserves the dominant influence of actual harmonic operating conditions on insulation thermal aging, ensuring the reliability of the test results, while avoiding the difficulties of directly reproducing complex waveforms.

[0032] This invention selects the test waveform frequency based on amplitude-frequency characteristics and loss power, and calculates the effective value of the test voltage. By jointly considering amplitude and dielectric loss, it accurately identifies the dominant frequency. Then, it uses equivalent loss power to deduce the effective value of the test voltage, ensuring that the thermal effects of the test process are equivalent to those of actual operating conditions. The test conditions are reproducible and engineering-operable, filling the gap in high-frequency harmonic withstand testing. High-frequency harmonic withstand testing based on the test waveform frequency and the effective value of the test voltage can truly reflect the thermal stability and insulation aging characteristics of equipment operating under high-frequency harmonic environments for extended periods, improving the reliability of test results and meeting the high reliability engineering requirements of flexible DC transmission projects. Attached Figure Description

[0033] Figure 1 This is a flowchart illustrating a high-frequency harmonic withstand test method for key equipment in a flexible DC transmission system according to the present invention. Figure 2 This is a schematic diagram illustrating the correlation between operating power and dielectric loss power in one example of the present invention. Figure 3This is a frequency-amplitude diagram of a voltage waveform under a certain operating condition, as exemplified by the present invention. Figure 4 This is a frequency-dielectric loss power diagram corresponding to a voltage waveform under an operating condition, as exemplified by the present invention. Figure 5 This is a structural block diagram of an electronic device according to the present invention. Detailed Implementation

[0034] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] Example 1 This invention provides a high-frequency harmonic withstand test method for key equipment in a flexible DC transmission system, as shown in the schematic diagram below. Figure 1 As shown, the method includes: Step S110: Obtain the voltage waveforms of key equipment under multiple actual operating conditions of the flexible DC transmission system, perform frequency domain analysis on each voltage waveform, and extract the corresponding amplitude-frequency characteristics. Step S120: Calculate the dielectric loss power of each harmonic under each voltage waveform based on the amplitude-frequency characteristics of each voltage waveform; and determine the equivalent loss power of the high-frequency harmonic withstand test of the key equipment based on the dielectric loss power of each harmonic using the thermal effect equivalence principle. Step S130: Based on the amplitude-frequency characteristics and the dielectric loss power of each harmonic, the test waveform frequency is selected in the target frequency band, and the effective value of the test voltage for the high-frequency harmonic withstand test of the key equipment is calculated based on the equivalent loss power and the test waveform frequency. Step S140: Based on the test voltage waveform formed by the test waveform frequency and the effective value of the test voltage, a high-frequency harmonic tolerance test is performed on the key equipment to evaluate the high-frequency harmonic tolerance capability of the key equipment.

[0036] In this example implementation, the voltage waveforms of key equipment under multiple actual operating conditions of the flexible DC transmission system are first acquired. Key equipment can be power equipment requiring high-frequency harmonic tolerance, such as wall bushings and DC voltage dividers, primarily assessing the high-voltage harmonic tolerance of the insulation components. The multiple actual operating conditions can be typical operating conditions in real-world scenarios, each corresponding to a different operating power range. These conditions cover both the maximum and minimum operating power of the equipment, ensuring coverage of extreme conditions that the equipment may encounter during actual operation. Multiple voltage waveforms are acquired for each operating condition. Frequency domain analysis is performed on each acquired voltage waveform, for example, using a Fast Fourier Transform to decompose the time-domain waveform into a superposition of different frequency components, thereby extracting the corresponding amplitude-frequency characteristics, i.e., the magnitude and distribution of the amplitude of each frequency component. Based on these characteristics, the dielectric loss power generated by each harmonic acting alone under that voltage waveform is calculated according to dielectric loss theory. Dielectric loss power reflects the thermal effect caused by polarization hysteresis or leakage conduction when harmonic voltage acts on insulating materials, and is a key physical quantity for assessing insulation thermal aging. Then, using the principle of thermal effect equivalence, the cumulative thermal effect generated by each harmonic under the actual complex voltage waveform is mathematically converted into the equivalent thermal effect under a single-frequency sinusoidal voltage, thereby determining the equivalent loss power required for the high-frequency harmonic withstand test of key equipment. This equivalence treatment simplifies complex multi-frequency tests that were originally impossible to implement directly into single-frequency tests. Next, based on the extracted amplitude-frequency characteristics and the calculated dielectric loss power of each harmonic, the most representative test waveform frequency is selected from the preset target frequency band (e.g., the high-frequency harmonic band of interest). This frequency is usually the dominant frequency with a large amplitude and a high proportion of dielectric loss in the actual waveform. Simultaneously, based on the equivalent loss power and the selected test waveform frequency, the effective value of the test voltage that can produce the same thermal effect under this single-frequency sinusoidal voltage is derived using the theoretical relationship between dielectric loss power and the effective voltage value. At this point, the frequency and effective value of the test waveform have been determined, thus constructing a standardized single-frequency sinusoidal test waveform. Finally, the designed test voltage waveform is applied to the key equipment for a high-frequency harmonic withstand test. By monitoring indicators such as temperature rise, capacitance, insulation resistance, dielectric loss factor, partial discharge, and appearance changes of the equipment's insulating components during the test, the insulation withstand capability and operational reliability of the key equipment under long-term high-frequency harmonic environments are comprehensively evaluated. This method equates complex multi-frequency harmonic operating conditions in the field to reproducible single-frequency test conditions, solving the problem that traditional tests cannot reflect the impact of high-frequency harmonics. It provides a scientific and reliable technical means for assessing the high-frequency harmonic withstand capability of key equipment in flexible DC transmission systems, meeting the high reliability engineering requirements of flexible DC transmission projects.

[0037] In some implementations, frequency domain analysis is performed on each voltage waveform to extract the corresponding amplitude-frequency characteristics, including: For any one of the multiple voltage waveforms that the key equipment is subjected to under each set of actual operating conditions, perform a fast Fourier transform on the voltage waveform to obtain the corresponding amplitude spectrum; Statistical analysis was performed on the amplitude spectra of multiple voltage waveforms under actual operating conditions of each group to obtain the amplitude distribution characteristics of each frequency component.

[0038] In this example implementation, to more accurately reflect the diversity of actual operating conditions, multiple voltage waveforms are acquired for each group of actual operating conditions. For example, multiple samplings are performed within the same operating power range to eliminate the influence of random factors on waveform characteristics. The amplitude-frequency characteristics include not only the amplitude spectrum (i.e., the correspondence between each frequency component and its amplitude) but also the amplitude distribution characteristics of each frequency component, such as the average, maximum, minimum, or variance of the amplitude. The specific process of performing frequency domain analysis and extracting amplitude-frequency characteristics for each voltage waveform is as follows: First, for any one of the multiple voltage waveforms subjected to by the key equipment under each group of actual operating conditions, a Fast Fourier Transform is performed on the voltage waveform to convert the time-domain sampled signal into a frequency-domain discrete spectrum, thereby obtaining the amplitude spectrum corresponding to the voltage waveform. In the amplitude spectrum, the horizontal axis represents frequency, and the vertical axis represents the amplitude (usually the peak value or RMS value) of the corresponding frequency component. Then, statistical analysis is performed on all the collected amplitude spectra. For example, the average and standard deviation of the amplitudes of multiple waveforms at the same frequency point are calculated, or the probability of amplitudes exceeding a certain threshold is statistically analyzed, thereby obtaining the amplitude distribution characteristics of each frequency component. Through this process, not only can the high-amplitude harmonic frequencies that are common under different operating conditions be identified, but the stability and dispersion of these frequency components can also be evaluated. This provides a reliable data basis for subsequent screening of experimental waveform frequencies, ensuring that the final determined test conditions can truly reflect the harmonic stress that the equipment experiences during actual long-term operation.

[0039] For example, for each frequency component, the dielectric loss power under its individual action is taken as the dielectric loss power of the corresponding harmonic and calculated according to the following formula: (1) in, For the first Dielectric loss power of subharmonics For the first RMS value of subharmonic voltage The fundamental angular frequency, For harmonic order, This refers to the tangent of the dielectric loss angle of the critical equipment. This refers to the capacitance value of critical equipment. For the actual voltage waveform, since the frequency components after Fourier decomposition are orthogonal in the frequency domain, and the insulating material approximately satisfies the principle of linear superposition within the normal voltage range, the dielectric loss power under the individual action of each harmonic can be summed to obtain the total dielectric loss power under that voltage waveform. This calculation method realizes a quantitative mapping from the voltage waveform to the insulation thermal load, making the high-frequency harmonic thermal effects, which were originally impossible to measure directly, calculable and comparable, providing accurate input parameters for subsequent equivalent thermal effect conversion.

[0040] In some implementations, the test waveform frequency is selected in the target frequency band based on the amplitude-frequency characteristics and the dielectric loss of each harmonic, including: For each amplitude spectrum, calculate the dielectric loss power under the individual action of each frequency component in the amplitude spectrum to obtain the corresponding dielectric loss power spectrum; Based on the amplitude distribution characteristics of each frequency component, the target frequency band is determined; for each amplitude spectrum, the top n frequencies in the target frequency band are selected as candidate frequencies in descending order of amplitude, where n is an integer greater than 1. In the dielectric loss power spectrum corresponding to this amplitude spectrum, the frequency with the largest dielectric loss power among the candidate frequencies is taken as the target frequency corresponding to this amplitude spectrum; The target frequencies corresponding to the amplitude spectra of multiple voltage waveforms under multiple actual operating conditions are statistically analyzed, and the frequency that appears most frequently is determined as the frequency of the test waveform.

[0041] In this example implementation, for each amplitude spectrum, the dielectric loss power under the individual action of each frequency component in the amplitude spectrum is calculated using formula (1), thereby obtaining the dielectric loss power spectrum corresponding to the amplitude spectrum to reflect the contribution value of different frequencies to the thermal effect. Then, based on the amplitude distribution characteristics of each frequency component, the target frequency band is determined. The target frequency band can be determined according to engineering experience and amplitude distribution characteristics, such as the high-frequency harmonic frequency band of interest in engineering experience (e.g., above 2kHz), and then the continuous frequency range within the interest band where the amplitude is significantly higher than the background noise is taken as the target frequency band. After determining the target frequency band, for each amplitude spectrum, the first n frequencies in the target frequency band are selected as candidate frequencies in descending order of amplitude, where n is an integer greater than 1, for example, n is 3, 5 or 10. The reason for doing this is that harmonic components with larger amplitudes usually carry more energy. Next, in the dielectric loss power spectrum corresponding to the amplitude spectrum, the frequency with the largest dielectric loss power is found from the selected candidate frequencies, and this frequency is taken as the target frequency corresponding to the amplitude spectrum. This step comprehensively considers the dual impact of amplitude and frequency on losses, ensuring that the selected frequency is indeed the dominant frequency contributing the most to the thermal effect. Finally, the above process is repeated for the amplitude spectra of multiple voltage waveforms under multiple actual operating conditions to obtain a series of target frequencies. The frequency of occurrence of these target frequencies is counted, and the frequency that occurs most frequently is determined as the final test waveform frequency.

[0042] In some implementations, the determination of the equivalent loss power of the high-frequency harmonic withstand test of key equipment based on the dielectric loss power of each harmonic, using the principle of thermal effect equivalence, includes: Based on the statistical analysis of the dielectric loss power of each harmonic in each voltage waveform under the actual operating conditions of each group, the dielectric loss power of key equipment is determined. Based on the equivalent relationship between the cumulative thermal effect generated by multiple sets of actual operating voltage waveforms acting on key equipment and the thermal effect generated by a single frequency sinusoidal voltage, the dielectric loss power of the key equipment is taken as the equivalent loss power of the key equipment in the high-frequency harmonic withstand test at the test waveform frequency.

[0043] In this example implementation, the first step is to calculate the dielectric loss power of each harmonic under each voltage waveform according to equation (1), and then sum the dielectric loss power of all harmonics for each waveform to obtain the total dielectric loss power corresponding to that waveform. Subsequently, for multiple waveforms under the same set of operating conditions (i.e., the same or similar operating power range), the statistical value of their total dielectric loss power is calculated, such as the average or median, as the dielectric loss power under that set of operating conditions. Further, the dielectric loss power under different sets of operating conditions is statistically analyzed, for example, by calculating the average value of all operating conditions, or by using a fitting method to obtain the maximum value, thereby obtaining a dielectric loss power value that can represent the typical or most severe thermal effects of the equipment in actual operation. The second step is based on the equivalent relationship between the cumulative thermal effect generated by multiple sets of actual operating condition voltage waveforms acting on the key equipment and the thermal effect generated by a single frequency sinusoidal voltage, and the dielectric loss power of the key equipment determined above is directly used as the equivalent loss power of the high-frequency harmonic withstand test at the test waveform frequency. The core of this equivalence relationship lies in the fact that if the total dielectric loss power (i.e., total heat generation power) generated by actual complex harmonic voltages in equipment insulation is equal to the dielectric loss power generated by a single-frequency sinusoidal voltage, then the cumulative thermal effect (i.e., total heat generation) generated by both over the same duration is equal. Therefore, there is no need to reproduce complex multi-frequency waveforms; a single-frequency sinusoidal wave can be used instead, and as long as the loss power generated is equal, the same thermal aging effect can be simulated. Determining this equivalent loss power provides a crucial input parameter for the subsequent calculation of the effective value of the test voltage, simplifying complex field conditions into standardized laboratory test conditions while ensuring the authenticity and equivalence of the thermal effect.

[0044] In some implementations, the dielectric loss power of key equipment is determined based on statistical analysis of the dielectric loss power of each harmonic in each voltage waveform under each group of actual operating conditions, including: For any one of the multiple voltage waveforms under each actual operating condition, the sum of the dielectric loss power of each harmonic in the voltage waveform is taken as the total loss power corresponding to the voltage waveform. For each set of actual operating conditions, the dielectric loss power under each voltage waveform in the set of actual operating conditions is determined by fusing the total loss power. Based on statistical analysis of the media loss power under actual operating conditions of each group, the media loss power of key equipment is determined.

[0045] In this example implementation, considering that the thermal effects generated by each frequency component are independent and the total thermal effect is equal to the sum of the thermal effects of each component, the dielectric loss power of each harmonic in any voltage waveform is summed using the principle of linear superposition of dielectric loss power to obtain the total loss power corresponding to that voltage waveform. Next, for each set of actual operating conditions, since multiple voltage waveforms are usually collected under this condition (e.g., multiple samplings within the same operating power range), it is necessary to fuse the total loss power corresponding to each voltage waveform under this set of operating conditions to determine the dielectric loss power under this set of actual operating conditions. Fusion processing can employ various statistical methods, such as calculating the arithmetic mean, weighted average, median, or mode. Preferably, the arithmetic mean is used as the dielectric loss power under this set of operating conditions. After obtaining the dielectric loss power under each set of actual operating conditions, further statistical analysis of these values ​​is required to ultimately determine the dielectric loss power of the key equipment. The statistical analysis methods here can be flexibly selected based on the data distribution characteristics: if the dielectric loss power under each group of operating conditions shows a clear monotonic trend (e.g., increasing or decreasing) with the change in operating power, a fitting method can be used to find the maximum or minimum value; if the data is relatively scattered and has no obvious pattern, the total average value of the dielectric loss power under all operating conditions can be calculated. Through this hierarchical and progressive statistical processing, the differences in thermal effects under different operating powers are preserved, while avoiding the influence of random errors in a single waveform on the final result. This ensures that the determined dielectric loss power of key equipment has high representativeness and reliability, providing a solid numerical foundation for the subsequent setting of equivalent loss power.

[0046] In some implementations, the dielectric loss power of key equipment is determined based on statistical analysis of the dielectric loss power under actual operating conditions of each group, including: If the media loss power under the actual operating conditions of each group has a statistical regularity within the target operating power range, the relationship between the media loss power and the operating power of the key equipment is fitted based on the media loss power under the actual operating conditions of each group. Based on this relationship, the maximum media loss power within the target operating power range is determined. Based on this maximum media loss power and the preset safety margin, the media loss power of the key equipment is determined. If there is no statistical regularity in the media loss power under the actual operating conditions of each group within the target operating power range, the media loss power of the key equipment is determined based on the fusion result of the media loss power under the actual operating conditions of each group and the preset safety margin.

[0047] In this example implementation, the first scenario is as follows: If the media loss power under each group's actual operating conditions exhibits a statistical regularity within the target operating power range, i.e., there is a clear correlation between the media loss power and the operating power (e.g., monotonically increasing or decreasing with increasing power, or increasing first and then decreasing), then a fitting method is used. Specifically, with the operating power as the independent variable and the media loss power as the dependent variable, regression analysis methods such as least squares are used to fit the relationship between the two, such as a linear or polynomial relationship. Then, based on this relationship, the maximum value of the media loss power is calculated within the target operating power range (e.g., from minimum operating power to maximum operating power). Subsequently, this maximum value is multiplied by a preset safety margin coefficient (e.g., 1.5 to 2 times) to obtain the final media loss power of the key equipment. The second scenario: If the media loss power under each group's actual operating conditions does not exhibit a statistically consistent pattern within the target operating power range—that is, the data points fluctuate randomly without a clear monotonic trend—the media loss power under all operating conditions is fused (e.g., the arithmetic mean is calculated) to obtain a benchmark value representing the average thermal effect. This benchmark value is then multiplied by a preset safety margin coefficient to obtain the media loss power of the critical equipment. By processing the two data characteristics separately, this method becomes more widely applicable, enabling the scientific and reasonable determination of media loss power that balances representativeness and safety regardless of the distribution pattern of the measured data.

[0048] In some embodiments, the effective value of the test voltage is calculated using the following formula: (2) (3) in, This refers to the effective value of the test voltage for critical equipment. This refers to the equivalent power loss of key equipment. For the fundamental frequency of flexible DC transmission systems, For the test waveform frequency of key equipment, The dominant harmonic order corresponding to the frequency of the test waveform. The fundamental angular frequency, This refers to the tangent of the dielectric loss angle of the critical equipment. This represents the capacitance value of the key equipment. This formula reduces the complex problem of multi-frequency thermal effects to a simple algebraic calculation, allowing test personnel to quickly and accurately determine the test voltage value based on known equipment parameters and statistically obtained equivalent power losses, without requiring extensive background in harmonic analysis. This greatly improves the engineering practicality and operability of this method.

[0049] In some implementations, a high-frequency harmonic withstand test is performed on critical equipment based on a test voltage waveform formed by the test waveform frequency and the effective value of the test voltage, to evaluate the high-frequency harmonic withstand capability of the critical equipment, including: Based on the test waveform frequency and the effective value of the test voltage, a test voltage waveform is applied to the key equipment, and the equipment is continuously operated until it reaches a thermally stable state, and then maintained in the thermally stable state for a specified time. Measure the insulation performance parameters of key equipment and evaluate the high-frequency harmonic tolerance of key equipment based on the measurement results.

[0050] In this example implementation, before the test begins, temperature sensing elements (such as thermocouples or fiber optic sensors) are pre-positioned at key locations inside and on the surface of the equipment to monitor temperature changes in real time. A single-frequency sinusoidal test voltage waveform is generated based on the test waveform frequency and the effective value of the test voltage, and this waveform is applied to the insulation part of the critical equipment. For critical equipment such as through-wall bushings that need to carry the main circuit operating current, the rated test current is also supplied to the equipment conductor rod while applying the test voltage to simulate the current heating effect in actual operation; while for equipment such as DC voltage dividers that do not carry the rated operating current of the main circuit, only the test voltage needs to be applied. Then, the above test conditions are continuously run until the critical equipment reaches a thermally stable state. The thermally stable state is usually determined by the temperature stability criteria specified in IEC standards or national standards, such as the temperature change at all measuring points being less than 1 Kelvin (1 K) within 1 hour. If the temperature rise limit exceeds the relevant standard requirements, the test is stopped, and the equipment is deemed to have failed the test. If the temperature rise limit does not exceed the relevant standard requirements, the equipment is kept running in a thermally stable state for a specified time (e.g., 24 hours) to assess the equipment's ability to withstand long-term continuous thermal stress. After the specified time has elapsed, stop applying the test voltage and test current, and perform comprehensive insulation performance parameter measurements on the equipment, including but not limited to insulation resistance, dielectric loss factor (tanδ), capacitance, partial discharge, and other indicators. Simultaneously, inspect the equipment for cracks, creepage marks, or other mechanical damage. If any indicator exceeds the standard or if there are any appearance defects, the equipment is deemed to have failed the high-frequency harmonic withstand test. For example, according to the national standard GB / T4109-2022 requirements for temperature rise testing of insulating bushings with AC voltage higher than 1000V, an appropriate number of measuring elements are arranged at different positions of the bushing, and the rated current specified in the standard is applied. At the same time, a high-frequency harmonic withstand test voltage is applied to the insulation position of the bushing. The temperature stability judgment criterion specified in the standard is adopted, that is, when the temperature change ΔT of all measuring points within 1 hour is less than 1K, the bushing is considered to have reached a stable state. If the temperature rise limit exceeds the standard requirement, the test is stopped and the bushing is judged to have failed the test. If the requirements are met, the test conditions are maintained for 24 hours. After the test is completed, the appearance is checked for cracks and creepage marks, and the capacitance, dielectric loss factor (judged by measurement value), and partial discharge are detected. The measurement results are compared with the state before the test. When any index drops to less than the standard value, the harmonic withstand test of the wall bushing insulation is considered to have failed.

[0051] Conversely, if all indicators are within the acceptable range and the appearance is normal, the equipment is deemed to have passed the test. This method, through a complete testing procedure and clear judgment criteria, provides a quantifiable and reproducible means of assessing the high-frequency harmonic tolerance capability of key equipment in flexible DC transmission systems.

[0052] For example, taking a through-wall bushing as an example, the high-frequency voltage withstand capability assessment test method of the present invention adopts the route of "on-site operating condition analysis → calculation of equivalent reference value of dielectric loss → design of test waveform → test assessment", including the following steps: (1) Typical operating condition waveform analysis: Fourier analysis is performed on voltage waveforms under multiple operating conditions to analyze the frequency and amplitude patterns.

[0053] (2) Calculation of equivalent reference value of dielectric loss: First, calculate the dielectric loss generated by the insulating medium of the wall bushing under different operating conditions. Then, obtain the average dielectric loss under the operating conditions. Introduce a safety margin factor of 1.5 times and use the corrected power value as the design value of dielectric loss power for the high frequency harmonic withstand test of the wall bushing.

[0054] (3) Harmonic withstand test waveform design: The thermal effect equivalent method is adopted, which converts the cumulative thermal effect generated by the actual complex voltage waveform acting on the test equipment into the thermal effect generated by a specific single-frequency sinusoidal voltage, thereby constructing a standardized harmonic withstand test excitation waveform. The high-order harmonic frequency in the actual waveform, which has both amplitude and dielectric loss as the dominant factor, is selected as the test waveform frequency. Based on the fact that the equivalent loss power is equal to the actual loss power, the effective value of the harmonic withstand test voltage is obtained.

[0055] (4) High-frequency voltage withstand capability test of key equipment: For power equipment that needs to carry the main circuit working current, the rated test current is passed through the equipment conductor rod, and the harmonic withstand test voltage is applied to the equipment insulation part. After the equipment reaches a stable state, the temperature rise of the equipment is measured. If the temperature rise limit exceeds the relevant standard requirements, the equipment fails the test. If it does not exceed the relevant standard requirements, the test condition is maintained for 24 hours. The capacitance, dielectric loss factor and partial discharge are tested according to the relevant standards of the equipment. The appearance is checked for cracks and creepage marks. The long-term operating capability under complex harmonic environment is comprehensively evaluated in this way.

[0056] Experimental example: Taking the field measured data of a converter station of a certain project as an example, 37 field waveforms were obtained and Fourier analysis was performed. That is, the overall voltage can be decomposed into the superposition result of different frequency components, as shown in Equation (4): (4) In the formula, This is the actual voltage waveform, where t is time. Here, h represents the DC component, and h represents the harmonic order. Let N be the initial phase of the h-th harmonic and N be the upper limit of the harmonic order. The actual waveform processed in this embodiment is a finite-length discrete-time sequence. According to the Nyquist sampling theorem, its upper limit for frequency analysis is set to 1 / 2 of the sampling frequency to avoid spectral aliasing caused by high-frequency components exceeding the upper limit. The statistical results of the amplitude distribution characteristics of each frequency component are shown in Table 1. It can be seen that the frequencies with higher amplitudes in the low-frequency band are mainly concentrated around 250Hz, and the frequencies with higher amplitudes in the high-frequency band are mainly concentrated around 200kHz. Considering the purpose of the high-frequency harmonic experiment, 100kHz-200kHz is selected as the target frequency band.

[0057] Table 1

[0058] The dielectric loss heating of the insulating medium of the wall bushing under the h-th AC sinusoidal voltage can be calculated as shown in equation (1). To reduce the interference of noise on the loss calculation results, when the effective value of the voltage is less than 1% of the effective value of the power frequency voltage, its value is set to 0. Then the total dielectric loss power of a voltage waveform is... It can be represented as: (5) Based on this, the selection rules for equivalent loss power are as follows: Calculate the total dielectric loss under each voltage waveform based on equation (5). Since multiple operating waveforms will correspond to the same operating power, calculate the arithmetic mean of the dielectric loss of multiple voltage waveform data under the same operating condition as the dielectric loss value corresponding to that operating condition (operating power). Conduct operating power-dielectric loss trend judgment. When it is observed that the dielectric loss has an obvious statistical regularity with the operating power (such as monotonically increasing / decreasing, parabolic curve, etc.), use the least squares method to fit the waveform and select the maximum dielectric loss value in the fitted curve as the equivalent reference value of dielectric loss; when there is no obvious statistical regularity between dielectric loss and operating power, use the average value of dielectric loss under each operating power as the equivalent reference value of dielectric loss. Introduce a safety margin and take 1.5 to 2 times the equivalent reference value of dielectric loss as the equivalent loss power to determine the power calculation basis for the withstand voltage test of the wall bushing.

[0059] like Figure 2 As shown, the blue dots represent the dielectric loss of each voltage waveform under each operating power (condition), the red dots represent the arithmetic mean of the dielectric loss of multiple voltage waveforms under that operating power, i.e., the dielectric loss power under each operating condition, and the dashed line represents the average dielectric loss under multiple operating conditions. Since there is no obvious statistical relationship between dielectric loss and operating power, the average dielectric loss of 488W under these multiple operating conditions is taken as the equivalent reference value for dielectric loss. Considering the need to retain a certain safety margin, 1.5 times the equivalent reference value of dielectric loss, 732W, is used as the basis for calculating the power of the through-wall bushing withstand test voltage.

[0060] The selection rules for the dominant frequency of the harmonic withstand test are as follows: conduct amplitude-frequency characteristic analysis and dielectric loss-frequency characteristic analysis on the voltage waveform, and select the top 5 points of harmonic amplitude from high to low, and the frequency point with the highest dielectric loss ratio as the dominant frequency of the withstand test. Figure 3 and Figure 4 The graphs show the magnitude (kV) - frequency (f / kHz) and power loss (W) - frequency (f / kHz) at an operating power of 823MW. In the graphs, X represents the x-axis value and Y represents the y-axis value. For example, Figure 4 In the diagram, X = 199.95 and Y = 73.55, indicating a frequency of 199.95 kHz and a dielectric loss power of 73.55 W. The top five harmonic amplitudes in the target frequency band, sorted from highest to lowest, are selected. Then, the frequency with the highest harmonic dielectric loss percentage is chosen. Based on the above selection rules, the dominant frequency for the withstand test under this waveform is selected as 200 kHz. All waveforms are analyzed using this method to determine the dominant frequency for the withstand test. Finally, the test waveform frequency is selected as 200 kHz, corresponding to a harmonic order of 4000.

[0061] When a voltage waveform is applied to the same bushing for the same time t, the resulting dielectric loss energy is exactly equal to the dielectric loss energy under the original complex harmonic operating condition. Since energy equals the product of power and time, eliminating time t, then: (6) in, The equivalent power loss at the test waveform frequency for high-frequency harmonic withstand testing of critical equipment. The dielectric loss power of the key equipment. The effective value of the withstand test voltage is obtained by equations (2) and (3). The calculation shows that the effective value of the test voltage is 5552V. Considering the adjustment accuracy of the high voltage power supply, the effective value can be taken as 5.5kV. The cumulative heat effect generated by the actual complex voltage waveform acting on the tested equipment is equivalent to the heat effect generated under the action of a specific single-frequency sinusoidal voltage. In this way, a standardized harmonic withstand test excitation waveform is constructed. The test voltage waveform It can be represented as: (7) The high-frequency harmonic withstand test of the high-voltage bushing can be performed under this voltage waveform.

[0062] This invention first performs Fourier analysis on voltage waveforms under multiple operating conditions to obtain waveform spectrum diagrams; then, it calculates dielectric losses at different frequencies and determines the equivalent loss power based on dielectric losses under actual operating conditions; next, by analyzing amplitude-frequency diagrams and dielectric loss-frequency diagrams, it identifies the dominant frequency as the test waveform frequency, and calculates the effective value of the test waveform based on the principle of equivalent loss power. This waveform is the harmonic withstand test waveform. By equivalently converting the thermal effects of actual operating conditions into feasible single-frequency high-voltage test conditions, it solves the key technical problem that traditional tests cannot reflect the impact of high-frequency harmonics on equipment, effectively assessing the withstand capability of bushings under long-term harmonic environments. It can assess and evaluate the reliability of key equipment operation under high-frequency steady-state harmonics, providing crucial technical theoretical basis for the design optimization of key equipment and its high-reliability application in ultra-high-voltage transmission systems.

[0063] Example 2 Based on the same inventive concept, this invention also provides a high-frequency harmonic withstand test device for key equipment in a flexible DC transmission system, comprising: The frequency domain analysis module is used to obtain the voltage waveforms of key equipment under multiple actual operating conditions of the flexible DC transmission system, perform frequency domain analysis on each voltage waveform, and extract the corresponding amplitude-frequency characteristics. The loss calculation module is used to calculate the dielectric loss power of each harmonic under each voltage waveform based on the amplitude-frequency characteristics of each voltage waveform; and to determine the equivalent loss power of the high-frequency harmonic withstand test of key equipment based on the dielectric loss power of each harmonic using the thermal effect equivalence principle. The parameter determination module is used to select the test waveform frequency in the target frequency band based on the amplitude-frequency characteristics and the dielectric loss power of each harmonic, and to calculate the effective value of the test voltage for the high-frequency harmonic withstand test of the key equipment based on the equivalent loss power and the test waveform frequency. The test module is used to conduct high-frequency harmonic tolerance tests on key equipment based on the test voltage waveform formed by the test waveform frequency and the effective value of the test voltage, and to evaluate the high-frequency harmonic tolerance capability of the key equipment.

[0064] In one possible implementation, multiple voltage waveforms are acquired for each set of actual operating conditions; the amplitude-frequency characteristics include the amplitude spectrum and the amplitude distribution characteristics under each frequency component; the frequency domain analysis module is specifically used for: For any one of the multiple voltage waveforms that the key equipment is subjected to under each set of actual operating conditions, perform a fast Fourier transform on the voltage waveform to obtain the corresponding amplitude spectrum; Statistical analysis was performed on the amplitude spectra of multiple voltage waveforms under actual operating conditions of each group to obtain the amplitude distribution characteristics of each frequency component.

[0065] In one possible implementation, for each frequency component, the dielectric loss power under its individual action is taken as the dielectric loss power of the corresponding harmonic and calculated according to the following formula:

[0066] in, For the first Dielectric loss power of subharmonics For the first RMS value of subharmonic voltage The fundamental angular frequency, For harmonic order, This refers to the tangent of the dielectric loss angle of the critical equipment. This refers to the capacitance value of critical equipment.

[0067] In one possible implementation, the parameter determination module includes a frequency filtering submodule, which is used for: For each amplitude spectrum, calculate the dielectric loss power under the individual action of each frequency component in the amplitude spectrum to obtain the corresponding dielectric loss power spectrum; Based on the amplitude distribution characteristics of each frequency component, the target frequency band is determined; for each amplitude spectrum, the top n frequencies in the target frequency band are selected as candidate frequencies in descending order of amplitude, where n is an integer greater than 1. In the dielectric loss power spectrum corresponding to this amplitude spectrum, the frequency with the largest dielectric loss power among the candidate frequencies is taken as the target frequency corresponding to this amplitude spectrum; The target frequencies corresponding to the amplitude spectra of multiple voltage waveforms under multiple actual operating conditions are statistically analyzed, and the frequency that appears most frequently is determined as the frequency of the test waveform.

[0068] In one possible implementation, the loss calculation module includes: The calculation submodule is used to determine the dielectric loss power of key equipment based on the statistical analysis of the dielectric loss power of each harmonic in each voltage waveform under each group's actual operating conditions. The equivalent submodule is used to establish the equivalent relationship between the cumulative thermal effect generated by multiple sets of actual operating condition voltage waveforms acting on key equipment and the thermal effect generated by a single frequency sinusoidal voltage. The dielectric loss power of the key equipment is used as the equivalent loss power of the key equipment in the high-frequency harmonic withstand test at the test waveform frequency.

[0069] In one possible implementation, the computing submodule includes: The calculation subunit is used to sum the dielectric loss power of each harmonic in any one of the multiple voltage waveforms under each group of actual operating conditions as the total loss power corresponding to that voltage waveform; for each group of actual operating conditions, the dielectric loss power under that group of actual operating conditions is determined by fusing the total loss power corresponding to each voltage waveform under that group of actual operating conditions. The statistical analysis subunit is used to determine the media loss power of key equipment based on the statistical analysis of the media loss power under the actual operating conditions of each group.

[0070] In one possible implementation, the statistical analysis subunit is specifically used for: If the media loss power under the actual operating conditions of each group has a statistical regularity within the target operating power range, the relationship between the media loss power and the operating power of the key equipment is fitted based on the media loss power under the actual operating conditions of each group. Based on this relationship, the maximum media loss power within the target operating power range is determined. Based on this maximum media loss power and the preset safety margin, the media loss power of the key equipment is determined. If there is no statistical regularity in the media loss power under the actual operating conditions of each group within the target operating power range, the media loss power of the key equipment is determined based on the fusion result of the media loss power under the actual operating conditions of each group and the preset safety margin.

[0071] In one possible implementation, the effective value of the test voltage is calculated using the following formula:

[0072]

[0073] in, This refers to the effective value of the test voltage for critical equipment. This refers to the equivalent power loss of key equipment. For the fundamental frequency of flexible DC transmission systems, For the test waveform frequency of key equipment, The dominant harmonic order corresponding to the frequency of the test waveform. The fundamental angular frequency, This refers to the tangent of the dielectric loss angle of the critical equipment. This refers to the capacitance value of critical equipment.

[0074] In one possible implementation, the test module is specifically used for: Based on the test waveform frequency and the effective value of the test voltage, a test voltage waveform is applied to the key equipment, and the equipment is continuously operated until it reaches a thermally stable state, and then maintained in the thermally stable state for a specified time. Measure the insulation performance parameters of key equipment and evaluate the high-frequency harmonic tolerance of key equipment based on the measurement results.

[0075] Example 3 like Figure 5 As shown, the present invention also provides an electronic device, which may be a computer device, a microcontroller device, a smart mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, processor, and transceiver component are connected via a bus; the memory can be used to store executable programs, and an exemplary executable program may include instructions; the processor is used to execute the instructions stored in the memory. The memory can also be used to store data, which can be accessed and / or modified when instructions are executed.

[0076] The processor may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing and control core of the terminal, and it is suitable for implementing one or more instructions. Specifically, it is suitable for loading and executing one or more instructions in the storage medium to realize the corresponding method flow or corresponding function, so as to realize the steps of the high-frequency harmonic withstand test method for key equipment of a flexible DC transmission system in the above embodiments.

[0077] Example 4 Based on the same inventive concept, this invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory). An electronic device readable storage medium is a memory device within an electronic device used to store programs and data. It is understood that the storage medium here can include both built-in storage media within the electronic device and extended storage media supported by the electronic device. The storage medium provides storage space, which stores the terminal's operating system. Furthermore, this storage space also stores one or more instructions suitable for loading and execution by a processor. These instructions can be one or more executable programs (including program code). It should be noted that the storage medium here can be high-speed RAM or non-volatile memory, such as at least one disk storage device. Loading and executing one or more instructions stored in the storage medium by the processor can implement the steps of the high-frequency harmonic withstand test method for key equipment in a flexible DC transmission system as described in the above embodiments.

[0078] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied 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.

[0079] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. 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 a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0080] 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 1The function specified in one or more boxes.

[0081] 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.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading the present invention, they can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the scope of protection of the claims pending approval.

Claims

1. A method for high-frequency harmonic withstand test of key equipment in a flexible DC transmission system, characterized in that, include: The voltage waveforms of key equipment under multiple actual operating conditions of the flexible DC transmission system are obtained, and frequency domain analysis is performed on each voltage waveform to extract the corresponding amplitude-frequency characteristics. The dielectric loss power of each harmonic under each voltage waveform is calculated based on the amplitude-frequency characteristics of each voltage waveform; the equivalent loss power of the high-frequency harmonic withstand test of the key equipment is determined based on the dielectric loss power of each harmonic using the thermal effect equivalence principle. Based on the amplitude-frequency characteristics and dielectric loss power of each harmonic, the test waveform frequency is selected in the target frequency band, and the effective value of the test voltage for the high-frequency harmonic withstand test of the key equipment is calculated based on the equivalent loss power and the test waveform frequency. Based on the test waveform formed by the frequency of the test waveform and the effective value of the test voltage, a high-frequency harmonic tolerance test is conducted on the key equipment to evaluate its high-frequency harmonic tolerance capability.

2. The method according to claim 1, characterized in that, Multiple voltage waveforms are acquired for each set of actual operating conditions; the amplitude-frequency characteristics include the amplitude spectrum and the amplitude distribution characteristics under each frequency component. Frequency domain analysis was performed on each voltage waveform to extract the corresponding amplitude-frequency characteristics, including: For any one of the multiple voltage waveforms that the key equipment is subjected to under each set of actual operating conditions, perform a fast Fourier transform on the voltage waveform to obtain the corresponding amplitude spectrum; Statistical analysis was performed on the amplitude spectra of multiple voltage waveforms under actual operating conditions of each group to obtain the amplitude distribution characteristics of each frequency component.

3. The method according to claim 2, characterized in that, For each frequency component, the dielectric loss power under its individual action is taken as the dielectric loss power of the corresponding harmonic, and calculated according to the following formula: in, For the first Dielectric loss power of subharmonics For the first RMS value of subharmonic voltage The fundamental angular frequency, For harmonic order, This refers to the tangent of the dielectric loss angle of the critical equipment. This refers to the capacitance value of critical equipment.

4. The method according to claim 2, characterized in that, Based on the amplitude-frequency characteristics and dielectric losses of each harmonic, the test waveform frequencies are selected in the target frequency band, including: For each amplitude spectrum, calculate the dielectric loss power under the individual action of each frequency component in the amplitude spectrum to obtain the corresponding dielectric loss power spectrum; Based on the amplitude distribution characteristics of each frequency component, the target frequency band is determined; for each amplitude spectrum, the top n frequencies in the target frequency band are selected as candidate frequencies in descending order of amplitude, where n is an integer greater than 1. In the dielectric loss power spectrum corresponding to this amplitude spectrum, the frequency with the largest dielectric loss power among the candidate frequencies is taken as the target frequency corresponding to this amplitude spectrum; The target frequencies corresponding to the amplitude spectra of multiple voltage waveforms under multiple actual operating conditions are statistically analyzed, and the frequency that appears most frequently is determined as the frequency of the test waveform.

5. The method according to claim 1, characterized in that, The method of determining the equivalent loss power of key equipment for high-frequency harmonic withstand tests based on the dielectric loss power of each harmonic, using the principle of thermal effect equivalence, includes: Based on the statistical analysis of the dielectric loss power of each harmonic in each voltage waveform under the actual operating conditions of each group, the dielectric loss power of key equipment is determined. Based on the equivalent relationship between the cumulative thermal effect generated by multiple sets of actual operating voltage waveforms acting on key equipment and the thermal effect generated by a single frequency sinusoidal voltage, the dielectric loss power of the key equipment is taken as the equivalent loss power of the key equipment in the high-frequency harmonic withstand test at the test waveform frequency.

6. The method according to claim 5, characterized in that, Based on statistical analysis of the dielectric loss power of each harmonic in each voltage waveform under actual operating conditions, the dielectric loss power of key equipment is determined, including: For any one of the multiple voltage waveforms under each actual operating condition, the sum of the dielectric loss power of each harmonic in the voltage waveform is taken as the total loss power corresponding to the voltage waveform. For each set of actual operating conditions, the dielectric loss power under each voltage waveform in the set of actual operating conditions is determined by fusing the total loss power. Based on statistical analysis of the media loss power under actual operating conditions of each group, the media loss power of key equipment is determined.

7. The method according to claim 6, characterized in that, Based on statistical analysis of the dielectric loss power under actual operating conditions in each group, the dielectric loss power of key equipment is determined, including: If the media loss power under the actual operating conditions of each group has a statistical regularity within the target operating power range, the relationship between the media loss power and the operating power of the key equipment is fitted based on the media loss power under the actual operating conditions of each group. Based on this relationship, the maximum media loss power within the target operating power range is determined. Based on this maximum media loss power and the preset safety margin, the media loss power of the key equipment is determined. If there is no statistical regularity in the media loss power under the actual operating conditions of each group within the target operating power range, the media loss power of the key equipment is determined based on the fusion result of the media loss power under the actual operating conditions of each group and the preset safety margin.

8. The method according to claim 5, characterized in that, The effective value of the test voltage is calculated using the following formula: in, This refers to the effective value of the test voltage for critical equipment. This refers to the equivalent power loss of key equipment. For the fundamental frequency of flexible DC transmission systems, For the test waveform frequency of key equipment, The dominant harmonic order corresponding to the frequency of the test waveform. The fundamental angular frequency, This refers to the tangent of the dielectric loss angle of the critical equipment. This refers to the capacitance value of critical equipment.

9. The method according to claim 1, characterized in that, A high-frequency harmonic withstand test is conducted on the key equipment based on the test waveform formed by the test waveform frequency and the effective value of the test voltage, to evaluate the high-frequency harmonic withstand capability of the key equipment, including: Based on the test waveform frequency and the effective value of the test voltage, a test voltage waveform is applied to the key equipment, and the equipment is continuously operated until it reaches a thermally stable state, and then maintained in the thermally stable state for a specified time. Measure the insulation performance parameters of key equipment and evaluate the high-frequency harmonic tolerance of key equipment based on the measurement results.

10. A high-frequency harmonic withstand test device for key equipment in a flexible DC transmission system, characterized in that, include: The frequency domain analysis module is used to obtain the voltage waveforms of key equipment under multiple actual operating conditions of the flexible DC transmission system, perform frequency domain analysis on each voltage waveform, and extract the corresponding amplitude-frequency characteristics. The loss calculation module is used to calculate the dielectric loss power of each harmonic under each voltage waveform based on the amplitude-frequency characteristics of each voltage waveform; and to determine the equivalent loss power of the high-frequency harmonic withstand test of key equipment based on the dielectric loss power of each harmonic using the thermal effect equivalence principle. The parameter determination module is used to select the test waveform frequency in the target frequency band based on the amplitude-frequency characteristics and the dielectric loss power of each harmonic, and to calculate the effective value of the test voltage for the high-frequency harmonic withstand test of the key equipment based on the equivalent loss power and the test waveform frequency. The test module is used to conduct high-frequency harmonic tolerance tests on key equipment based on the test voltage waveform formed by the test waveform frequency and the effective value of the test voltage, and to evaluate the high-frequency harmonic tolerance capability of the key equipment.

11. The apparatus according to claim 10, characterized in that, Multiple voltage waveforms are acquired for each set of actual operating conditions; the amplitude-frequency characteristics include the amplitude spectrum and the amplitude distribution characteristics under each frequency component; the frequency domain analysis module is specifically used for: For any one of the multiple voltage waveforms that the key equipment is subjected to under each set of actual operating conditions, perform a fast Fourier transform on the voltage waveform to obtain the corresponding amplitude spectrum; Statistical analysis was performed on the amplitude spectra of multiple voltage waveforms under actual operating conditions of each group to obtain the amplitude distribution characteristics of each frequency component.

12. The apparatus according to claim 11, characterized in that, For each frequency component, the dielectric loss power under its individual action is taken as the dielectric loss power of the corresponding harmonic, and calculated according to the following formula: in, For the first Dielectric loss power of subharmonics For the first RMS value of subharmonic voltage The fundamental angular frequency, For harmonic order, This refers to the tangent of the dielectric loss angle of the critical equipment. This refers to the capacitance value of critical equipment.

13. The apparatus according to claim 11, characterized in that, The parameter determination module includes a frequency filtering submodule, which is used for: For each amplitude spectrum, calculate the dielectric loss power under the individual action of each frequency component in the amplitude spectrum to obtain the corresponding dielectric loss power spectrum; Based on the amplitude distribution characteristics of each frequency component, the target frequency band is determined; for each amplitude spectrum, the top n frequencies in the target frequency band are selected as candidate frequencies in descending order of amplitude, where n is an integer greater than 1. In the dielectric loss power spectrum corresponding to this amplitude spectrum, the frequency with the largest dielectric loss power among the candidate frequencies is taken as the target frequency corresponding to this amplitude spectrum; The target frequencies corresponding to the amplitude spectra of multiple voltage waveforms under multiple actual operating conditions are statistically analyzed, and the frequency that appears most frequently is determined as the frequency of the test waveform.

14. The apparatus according to claim 10, characterized in that, The loss calculation module includes: The calculation submodule is used to determine the dielectric loss power of key equipment based on the statistical analysis of the dielectric loss power of each harmonic in each voltage waveform under each group's actual operating conditions. The equivalent submodule is used to establish the equivalent relationship between the cumulative thermal effect generated by multiple sets of actual operating condition voltage waveforms acting on key equipment and the thermal effect generated by a single frequency sinusoidal voltage. The dielectric loss power of the key equipment is used as the equivalent loss power of the key equipment in the high-frequency harmonic withstand test at the test waveform frequency.

15. The apparatus according to claim 14, characterized in that, The computing submodule includes: The calculation subunit is used to sum the dielectric loss power of each harmonic in any one of the multiple voltage waveforms under each group of actual operating conditions as the total loss power corresponding to that voltage waveform; for each group of actual operating conditions, the dielectric loss power under that group of actual operating conditions is determined by fusing the total loss power corresponding to each voltage waveform under that group of actual operating conditions. The statistical analysis subunit is used to determine the media loss power of key equipment based on the statistical analysis of the media loss power under the actual operating conditions of each group.

16. The apparatus according to claim 15, characterized in that, The statistical analysis subunit is specifically used for: If the media loss power under the actual operating conditions of each group has a statistical regularity within the target operating power range, the relationship between the media loss power and the operating power of the key equipment is fitted based on the media loss power under the actual operating conditions of each group. Based on this relationship, the maximum media loss power within the target operating power range is determined. Based on this maximum media loss power and the preset safety margin, the media loss power of the key equipment is determined. If there is no statistical regularity in the media loss power under the actual operating conditions of each group within the target operating power range, the media loss power of the key equipment is determined based on the fusion result of the media loss power under the actual operating conditions of each group and the preset safety margin.

17. The apparatus according to claim 14, characterized in that, The effective value of the test voltage is calculated using the following formula: in, This refers to the effective value of the test voltage for critical equipment. This refers to the equivalent power loss of key equipment. For the fundamental frequency of flexible DC transmission systems, For the test waveform frequency of key equipment, The dominant harmonic order corresponding to the frequency of the test waveform. The fundamental angular frequency, This refers to the tangent of the dielectric loss angle of the critical equipment. This refers to the capacitance value of critical equipment.

18. The apparatus according to claim 10, characterized in that, The test module is specifically used for: Based on the test waveform frequency and the effective value of the test voltage, a test voltage waveform is applied to the key equipment, and the equipment is continuously operated until it reaches a thermally stable state, and then maintained in the thermally stable state for a specified time. Measure the insulation performance parameters of key equipment and evaluate the high-frequency harmonic tolerance of key equipment based on the measurement results.

19. An electronic device, characterized in that, include: At least one processor and memory; The memory and processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, the method as described in any one of claims 1 to 9 is implemented.

20. A readable storage medium, characterized in that, It contains an executable program, which, when executed, implements the method as described in any one of claims 1 to 9.

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