A method and apparatus for ultra-high harmonic quantization based on variable frequency band aggregation

Abstract

The application relates to a kind of based on variable frequency band aggregation super high harmonic quantization method and device, comprising: super high harmonic frequency band aggregation is carried out, and the amplitude after super high harmonic aggregation is obtained;According to the amplitude after super high harmonic aggregation, the peak change factor of the super high harmonic after aggregation is calculated;The peak attenuation rate of super high harmonic is quantified by using the peak change factor of the super high harmonic after aggregation;The application can guide the treatment scheme of super high harmonic by carrying out variable frequency band aggregation to super high harmonic, and then improving power supply quality.

Description

Technical Field

[0001] The present invention relates to the technical field of power quality analysis, and in particular to a method and device for quantifying ultra-high harmonics based on variable frequency band aggregation. Background Art

[0002] With the rapid development of power electronics and power-line communication (PLC) in distribution systems (9-148.5kHz), the content of harmonics with frequencies above 2kHz on the distribution network side has continued to increase. In 2013, at the IEEE International Conference on Power and Energy, the high-frequency components between 2-150kHz in power system voltage and current were first defined as supraharmonics. Research has found that supraharmonics in low-voltage distribution networks have numerous sources. Furthermore, interactions between multiple converters, converters, cables, and filters can further lead to series and parallel resonance of supraharmonics. Supraharmonics can cause equipment malfunctions, excessive harmonics, malfunction of automatic devices, abnormal converter heating and component burnout, accelerated aging, shortened service life, increased equipment noise, and communication system failures, resulting in significant losses for power users and businesses. Reasonable and accurate assessment of the severity of ultra-high-order harmonics can not only be used to measure the quality of system power, serving as an important basis for pricing electricity according to quality in the power market environment, but also provide guidance for the control of ultra-high-order harmonics and improve system power quality.

[0003] Currently, research on ultra-high harmonics is still in its infancy. Power quality standards typically limit the harmonic focus for utility grids to the 25th order (1.25kHz) and below, and international harmonic analysis does not exceed the 50th order (2.5kHz). Currently, there are no standards specifically addressing ultra-high harmonics. IEC61000-4-7 recommends a 200Hz bandwidth for aggregating harmonics in the 2-9kHz range; IEC61000-4-30 recommends a 2000Hz bandwidth for frequency band aggregation in the 9-150kHz range. Due to the diverse emissions from different devices, neither of these methods accurately aggregates any particular transmission band and its associated emissions. Emissions within a single switching frequency range may be split across multiple bands, or even aggregated into a single band for emissions from different switching frequency ranges. Consequently, these methods fail to accurately reflect actual emissions, and the resulting aggregated parameters are of limited reference value. A 200Hz bandwidth isn't even sufficient to cover the emission band of photovoltaic inverters. Demonstration has found that a bandwidth of at least 600Hz is required for a single aggregate value within the switching frequency band to represent 99% of the energy emitted. The use of different aggregation standards makes different analysis results incomparable. For broadband emissions such as PLC signals and background noise, the difference in measurement results when using 200Hz and 2000Hz frequency bands is approximately 10dBμV. Furthermore, because ultra-high harmonic emission patterns differ from traditional harmonics, primarily depending on the switching frequency and its integer multiples, traditional aggregation methods cannot effectively aggregate ultra-high harmonics within a specific frequency sub-band. Therefore, existing standards are not fully applicable to the characterization of ultra-high harmonics. Furthermore, the diversity of ultra-high harmonic sources and their control methods makes existing frequency band aggregation methods incapable of simultaneously achieving optimal aggregation across all harmonic sources.

[0004] At the same time, the comprehensive emission characteristic assessment of ultra-high harmonics should include a description of the total emission and the emission patterns. Existing quantitative indicators mainly include ultra-high harmonic emission and distortion, reflecting the comprehensive emission of ultra-high harmonics, such as total supraharmonic distortion (TSHD), total supraharmonic current (TSHC), and total supraharmonic voltage (TSHV). Compared with traditional harmonics, ultra-high harmonics have ultra-high order and wide-bandwidth characteristics, and their spectrum changes dynamically. Demonstrating the emission patterns of ultra-high harmonics is a basic requirement for ultra-high harmonic analysis. The above indicators can only provide a general description of the emission situation, lacking a description of the emission patterns and other content, and cannot accurately describe the ultra-high harmonic emission.

[0005] Therefore, in order to improve the comprehensive emission characteristic evaluation of ultra-high harmonics, indicators that reflect the emission laws of ultra-high harmonics should be proposed to more accurately describe the emission of ultra-high harmonics, guide the targeted treatment of ultra-high harmonics that have a major impact on the power system, and improve the power supply quality of the power grid. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a very high harmonic quantification method and device based on variable frequency band aggregation. By performing variable frequency band aggregation on the very high harmonics and quantifying the peak attenuation rate of the very high harmonics using the ultra-high harmonic peak change factor calculated from the amplitude after aggregation, it can guide the control plan of the very high harmonics and thus improve the power supply quality of the power grid.

[0007] The purpose of the present invention is achieved by adopting the following technical solutions:

[0008] The present invention provides a method for quantizing ultra-high harmonics based on variable frequency band aggregation, the improvement of which lies in that the method comprises the following steps:

[0009] Perform frequency band aggregation on ultra-high-order harmonics to obtain the amplitude of the aggregated ultra-high-order harmonics;

[0010] Calculate the peak variation factor of the ultra-high harmonics after aggregation according to the amplitude of the ultra-high harmonics after aggregation;

[0011] The peak attenuation speed of the ultra-high harmonics is quantified by using the ultra-high harmonic peak value change factor after polymerization.

[0012] Preferably, performing frequency band aggregation on ultra-high harmonics to obtain the amplitude of the aggregated ultra-high harmonics includes:

[0013] The following formula is used to determine the aggregated amplitude G of the ultra-high harmonics when the frequency band corresponding to the frequency F is aggregated with b as the aggregation bandwidth: b,F :

[0014]

[0015] Where, f c is the switching frequency, r is the spectrum analysis resolution, f is the actual frequency, Y f is the amplitude corresponding to the frequency f of the spectrum analysis, and m and s are positive integers.

[0016] Preferably, the process of performing frequency band aggregation on ultra-high harmonics further includes:

[0017] Take any switching frequency of the ultra-high harmonics as the aggregation center and determine the bandwidth that satisfies the following constraints I, II, III, and IV:

[0018] I. Bandwidth greater than or equal to 800Hz;

[0019] II. Bandwidth is a multiple of the switching frequency;

[0020] III. If there are multiple switching frequencies for ultra-high harmonics, the bandwidth should be the common divisor of all switching frequencies;

[0021] IV. The bandwidth is an integer multiple of the spectrum analysis resolution;

[0022] If there is only one bandwidth that satisfies constraints I, II, III, and IV, then that bandwidth is determined as the aggregate bandwidth.

[0023] If there are multiple bandwidths that meet the constraints I, II, III, and IV, the bandwidth closest to 800 Hz is selected as the aggregated bandwidth. Preferably, the calculation of the peak variation factor of the ultra-high harmonics after aggregation based on the amplitude of the ultra-high harmonics after aggregation includes:

[0024] Calculate the super-high harmonic peak variation factor SHPVF when the switching frequency multiple is n after aggregation according to the following formula: n :

[0025]

[0026] Wherein, l is the control mode coefficient of the device under test, and the control mode of the device under test includes: bipolar modulation mode and unipolar modulation mode. When the control mode of the device under test is bipolar modulation mode, l=1; when the control mode of the device under test is unipolar modulation mode, l=2. G b,F is the aggregated amplitude of the ultra-high harmonics when the frequency band corresponding to the frequency F is obtained after the ultra-high harmonics are aggregated with b as the aggregation bandwidth. When l=1, n is a positive integer greater than or equal to 2; when l=2, n is an even number greater than or equal to 4.

[0027] Furthermore, the method of quantifying the peak attenuation rate of the ultra-high harmonics by using the peak change factor of the ultra-high harmonics after polymerization includes:

[0028] When l=1, the super-high harmonic peak variation factor SHPVF when the switching frequency multiple after aggregation is n n As a quantified quantity of the decay speed of the nth peak of the ultra-high harmonic relative to the n-1th peak;

[0029] When l=2, the super-high harmonic peak variation factor SHPVF when the switching frequency multiple after aggregation is n n As a quantified quantity of the decay speed of the nth peak of the ultra-high harmonic relative to the n-2th peak;

[0030] Among them, when the switching frequency multiple after aggregation is n, the super-high harmonic peak variation factor SHPVF nThere is a positive correlation between the attenuation rate of the nth peak of the ultra-high harmonic relative to the n-1th peak or the attenuation rate of the nth peak of the ultra-high harmonic relative to the n-2nd peak.

[0031] Based on the same inventive concept, the present invention further provides an ultra-high harmonic quantization device based on variable frequency band aggregation, the improvement of which is that the device comprises:

[0032] Aggregation module, used for frequency band aggregation of ultra-high harmonics;

[0033] Amplitude calculation module, used to obtain the amplitude of ultra-high harmonics after aggregation;

[0034] A calculation module, used for calculating the peak variation factor of the ultra-high harmonics after aggregation according to the amplitude of the ultra-high harmonics after aggregation;

[0035] The quantization module is used to quantify the peak attenuation speed of the ultra-high harmonics by using the peak change factor of the ultra-high harmonics after aggregation.

[0036] Preferably, the amplitude calculation module is specifically used to:

[0037] The following formula is used to determine the aggregated amplitude G of the ultra-high harmonics when the frequency band corresponding to the frequency F is aggregated with b as the aggregation bandwidth: b,F :

[0038]

[0039] Where, f c is the switching frequency, r is the spectrum analysis resolution, f is the actual frequency, Y f is the amplitude corresponding to the frequency f of the spectrum analysis, and m and s are positive integers.

[0040] Preferably, the aggregation module is further configured to:

[0041] In the process of band aggregation of ultra-high harmonics, any switching frequency of the ultra-high harmonics is used as the aggregation center, and the bandwidth that satisfies the following constraints I, II, III, and IV is determined:

[0042] I. Bandwidth greater than or equal to 800Hz;

[0043] II. Bandwidth is a multiple of the switching frequency;

[0044] III. If there are multiple switching frequencies for ultra-high harmonics, the bandwidth should be the common divisor of all switching frequencies;

[0045] IV. The bandwidth is an integer multiple of the spectrum analysis resolution;

[0046] If there is only one bandwidth that satisfies constraints I, II, III, and IV, then that bandwidth is determined as the aggregate bandwidth.

[0047] If there are multiple bandwidths that meet constraints I, II, III, and IV, the bandwidth closest to 800 Hz is selected as the aggregate bandwidth.

[0048] Preferably, the calculation module is specifically used to:

[0049] Calculate the super-high harmonic peak variation factor SHPVF when the switching frequency multiple is n after aggregation according to the following formula: n :

[0050]

[0051] Wherein, l is the control mode coefficient of the device under test, and the control mode of the device under test includes: bipolar modulation mode and unipolar modulation mode. When the control mode of the device under test is bipolar modulation mode, l=1; when the control mode of the device under test is unipolar modulation mode, l=2. G b,F is the aggregated amplitude of the ultra-high harmonics when the frequency band corresponding to the frequency F is obtained after the ultra-high harmonics are aggregated with b as the aggregation bandwidth. When l=1, n is a positive integer greater than or equal to 2; when l=2, n is an even number greater than or equal to 4.

[0052] Furthermore, the quantization module is specifically configured to:

[0053] When l=1, the super-high harmonic peak variation factor SHPVF when the switching frequency multiple after aggregation is n n As a quantified quantity of the decay speed of the nth peak of the ultra-high harmonic relative to the n-1th peak;

[0054] When l=2, the super-high harmonic peak variation factor SHPVF when the switching frequency multiple after aggregation is n n As a quantified quantity of the decay speed of the nth peak of the ultra-high harmonic relative to the n-2th peak;

[0055] Among them, when the switching frequency multiple after aggregation is n, the super-high harmonic peak variation factor SHPVF n There is a positive correlation between the attenuation rate of the nth peak of the ultra-high harmonic relative to the n-1th peak or the attenuation rate of the nth peak of the ultra-high harmonic relative to the n-2nd peak.

[0056] Compared with the closest prior art, the present invention has the following beneficial effects:

[0057] The present invention provides a method and device for quantifying ultra-high harmonics based on variable frequency band aggregation, which performs frequency band aggregation on ultra-high harmonics to obtain the amplitude of the ultra-high harmonics after aggregation; calculates the peak change factor of the ultra-high harmonics after aggregation based on the amplitude of the ultra-high harmonics after aggregation; and quantifies the peak attenuation rate of the ultra-high harmonics using the ultra-high harmonic peak change factor after aggregation; the present invention performs variable frequency band aggregation on ultra-high harmonics and quantifies the peak attenuation rate of the ultra-high harmonics using the ultra-high harmonic peak change factor calculated from the amplitude after aggregation, which can reflect the change of the ultra-high harmonic peak and embody the emission law of the ultra-high harmonics, thereby analyzing the severity of the ultra-high harmonics in the power system, guiding the control plan of the ultra-high harmonics, and thus improving the power supply quality of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 This is a flow chart of the ultra-high harmonic quantization method based on variable frequency band aggregation of the present invention;

[0059] Figure 2 is a waveform diagram of the sampling current in a specific embodiment of the present invention;

[0060] Figure 3 is a spectrum diagram of the phase A voltage in a specific embodiment of the present invention;

[0061] Figure 4 is a graph showing the relationship between the voltage amplitude and the corresponding frequency after ultra-high harmonic aggregation proposed by the present invention in a specific embodiment of the present invention;

[0062] Figure 5 This is a graph showing the relationship between voltage amplitude and corresponding frequency after ultra-high harmonics are aggregated with an aggregation bandwidth of 200 Hz in accordance with IEC61000-4-7 in a specific embodiment of the present invention;

[0063] Figure 6 This is a graph showing the relationship between the voltage amplitude and the corresponding frequency of ultra-high harmonics aggregated with an aggregation bandwidth of 2000 Hz in accordance with IEC61000-4-30 in a specific embodiment of the present invention;

[0064] Figure 7 It is a schematic diagram of the ultra-high harmonic quantization device based on variable frequency band aggregation of the present invention. DETAILED DESCRIPTION

[0065] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0066] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0067] The present invention provides a method for quantizing ultra-high harmonics based on variable frequency band aggregation, such as Figure 1 As shown, the method includes:

[0068] Perform frequency band aggregation on ultra-high-order harmonics to obtain the amplitude of the aggregated ultra-high-order harmonics;

[0069] Calculate the peak variation factor of the ultra-high harmonics after aggregation according to the amplitude of the ultra-high harmonics after aggregation;

[0070] The peak attenuation speed of the ultra-high harmonics is quantified by using the ultra-high harmonic peak value change factor after polymerization.

[0071] In a specific embodiment of the present invention, the above-mentioned obtaining of the amplitude of ultra-high harmonics after aggregation includes:

[0072] The following formula is used to determine the aggregated amplitude G of the ultra-high harmonics when the frequency band corresponding to the frequency F is aggregated with b as the aggregation bandwidth: b,F :

[0073]

[0074] Where, f c is the switching frequency, r is the spectrum analysis resolution, b is the aggregation bandwidth, f is the actual frequency, F is the frequency corresponding to the aggregated band, and Y f is the amplitude corresponding to the frequency f of the spectrum analysis, and m and s are positive integers.

[0075] Among them, if the switching frequency f c is not unique, then f c Any switching frequency can be substituted.

[0076] In a specific embodiment of the present invention, the process of performing frequency band aggregation on ultra-high harmonics further includes:

[0077] Taking any switching frequency of the ultra-high harmonics as the aggregation center, determine the bandwidth that satisfies the following constraints I, II, III, and IV:

[0078] I. Bandwidth greater than or equal to 800Hz;

[0079] II. Bandwidth is a multiple of the switching frequency;

[0080] III. If there are multiple switching frequencies for ultra-high harmonics, the bandwidth should be the common divisor of all switching frequencies;

[0081] IV. The bandwidth is an integer multiple of the spectrum analysis resolution;

[0082] If there is only one bandwidth that satisfies constraints I, II, III, and IV, then that bandwidth is determined as the aggregate bandwidth.

[0083] If there are multiple bandwidths that meet constraints I, II, III, and IV, the bandwidth closest to 800 Hz is selected as the aggregate bandwidth.

[0084] In a specific embodiment of the present invention, the switching frequency of the ultra-high harmonics can be obtained through spectrum analysis or theoretical deduction. If there are multiple switching frequencies, any switching frequency can be selected as the aggregation center.

[0085] In a specific embodiment of the present invention, considering that as the frequency increases, the peaks around the integer multiples of the switching frequency tend to be gentle and the amplitude is more uniform, the degree of aggregation gradually decreases as the multiple increases. In order to quantify this phenomenon, an ultra-high harmonic aggregation ratio SHAGP based on the amplitude after aggregation is proposed. n The concept of supraharmonic aggregation proportion is used to quantify the degree of aggregation of ultra-high harmonics.

[0086] Wherein, without considering the interference factors such as resonance, the frequency corresponding to the band after the ultra-high harmonics are aggregated with b as the aggregation bandwidth is determined as nf c The degree of aggregation of ultra-high harmonics

[0087]

[0088] Where n is the switching frequency multiple, The frequency corresponding to the band after the ultra-high harmonics are aggregated with b as the aggregation bandwidth is nf c The aggregated amplitude of the ultra-high harmonics is f c The frequency of the band after the ultra-high harmonics are aggregated is nf c The aggregated amplitude of ultra-high harmonics.

[0089] Wherein, without considering the interference factors such as resonance, the frequency conversion band aggregation method of ultra-high harmonics proposed in this application can make the frequency band corresponding to the frequency f after the ultra-high harmonics are aggregated with b as the aggregation bandwidth. c The degree of aggregation of ultra-high harmonics The frequency of the band after the ultra-high harmonics are aggregated with b as the aggregation bandwidth is 2f c The degree of aggregation of ultra-high harmonics The frequency band corresponding to the ultra-high harmonics after band aggregation with b as the aggregation bandwidth is 3f c The degree of aggregation of ultra-high harmonics The accuracy was more than 99%, which met the requirements of subsequent analysis.

[0090] In a specific embodiment of the present invention, the above-mentioned calculation of the peak variation factor of the ultra-high harmonics after aggregation based on the amplitude of the ultra-high harmonics after aggregation includes:

[0091] Calculate the super-high harmonic peak variation factor SHPVF when the switching frequency multiple is n after aggregation according to the following formula: n :

[0092]

[0093] Where n is the switching frequency multiple, l is the control mode coefficient of the device under test, and the control mode of the device under test includes: bipolar modulation mode and unipolar modulation mode. When the control mode of the device under test is bipolar modulation mode, l=1, when the control mode of the device under test is unipolar modulation mode, l=2, G b,F is the aggregated amplitude of the ultra-high harmonics when the frequency band corresponding to the frequency F is obtained after the ultra-high harmonics are aggregated with b as the aggregation bandwidth. When l=1, n is a positive integer greater than or equal to 2; when l=2, n is an even number greater than or equal to 4.

[0094] If the control mode of the device under test is unknown, the peaks appearing at equal frequency intervals in the spectrum graph can be observed and each regular peak can be taken as the switching frequency f. c , calculated with reference to the bipolar modulation method.

[0095] The method of quantifying the peak attenuation rate of ultra-high harmonics by using the peak change factor of ultra-high harmonics after polymerization includes:

[0096] When l=1, the super-high harmonic peak variation factor SHPVF when the switching frequency multiple after aggregation is n n As a quantified quantity of the decay speed of the nth peak of the ultra-high harmonic relative to the n-1th peak;

[0097] When l=2, the super-high harmonic peak variation factor SHPVF when the switching frequency multiple after aggregation is n n As a quantified quantity of the decay speed of the nth peak of the ultra-high harmonic relative to the n-2th peak;

[0098] Among them, when the switching frequency multiple after aggregation is n, the super-high harmonic peak variation factor SHPVFn There is a positive correlation between the attenuation rate of the nth peak of the ultra-high harmonic relative to the n-1th peak or the attenuation rate of the nth peak of the ultra-high harmonic relative to the n-2nd peak.

[0099] In a specific embodiment of the present invention, in addition to the above-mentioned super-high harmonic peak attenuation factor SHPVF n In addition to quantifying the peak attenuation rate of ultra-high harmonics and reflecting the emission law of ultra-high harmonics, it is also possible to obtain indicators of the total emission of ultra-high harmonics, such as total ultra-high harmonic voltage (TSHV), total ultra-high harmonic current (TSHC), and total ultra-high harmonic distortion (TSHD), based on the spectrum diagram or the relationship diagram between the amplitude of the ultra-high harmonics after aggregation and its corresponding frequency.

[0100] In a specific embodiment of the present invention, it is also possible to analyze the relationship diagram between the amplitude of the ultra-high harmonics after aggregation and their corresponding frequencies, and record the amplitudes and corresponding frequencies of the obvious peaks that are integer multiples of the non-switching frequency. Usually, such peaks contain important information, such as switching frequency, resonant frequency, etc., and such peaks are also the most likely to exceed the standard. When actually analyzing the power system, special attention is paid to them, and targeted preventive measures can be taken for them.

[0101] In a specific embodiment of the present invention, the super-high harmonic peak variation factor SHPVF n In addition to being used to quantify the peak attenuation rate of ultra-high harmonics and reflect the emission law of ultra-high harmonics, if the ultra-high harmonic peak variation factor is greater than 1, record the peak value and corresponding frequency of the spectrum diagram in the corresponding frequency band. There are two situations in which the ultra-high harmonic peak variation factor is greater than 1: one is caused by the generation mechanism of ultra-high harmonics, and the other is affected by external interference and other factors. Regardless of which one, recording it and studying the cause of its generation in the power system, clearly understanding the external interference situation, and being able to carry out targeted control of ultra-high harmonics are of great significance to improving the power quality of the power system.

[0102] In a specific embodiment of the present invention, the ultra-high harmonic emission of a photovoltaic grid-connected point at a certain moment is selected for testing, the sampling frequency is 500kHz, the measurement time is 3s, and the sampling current waveform is as follows: Figure 2 As shown in the figure, the horizontal axis represents time and the vertical axis represents current amplitude. Figure 3 As shown, the horizontal axis is the frequency, the vertical axis is the voltage amplitude of the ultra-high harmonics, and the resolution of the spectrum analysis used is 5Hz.

[0103] Among them, by calculating the sampled ultra-high harmonics, the total ultra-high harmonic voltage TSHV is 0.648, and the total ultra-high harmonic voltage distortion rate TSHD is uis 0.282, the total high-order harmonic current TSHC is 0.568, and the total high-order harmonic current distortion rate TSHD i is 0.605, and the switching frequency of the photovoltaic system is 16.25KHz.

[0104] Among them, through the above-mentioned method for selecting the ultra-high harmonic aggregation bandwidth, the aggregation bandwidth selected in this embodiment is 1250 Hz.

[0105] In a specific embodiment of the present invention, the above-mentioned ultra-high harmonic frequency conversion band aggregation method is used, 1250 is selected as the aggregation bandwidth, and 16.25KHz is used as the aggregation center to perform frequency band aggregation on the ultra-high harmonics. The aggregation result is as follows: Figure 4 As shown in the figure, the horizontal axis is the frequency after aggregation, and the vertical axis is the voltage amplitude after ultra-high harmonic aggregation. In order to demonstrate the aggregation effect brought by the ultra-high harmonic aggregation method proposed in the present invention, the ultra-high harmonics sampled at a photovoltaic grid-connected point at a certain moment in this embodiment are aggregated according to the 200Hz aggregation bandwidth in IEC61000-4-7 and the 2000Hz aggregation bandwidth in IEC61000-4-30, and the aggregation results are shown as follows: Figure 5 and Figure 6 As shown, it can be seen that the ultra-high harmonic frequency conversion band aggregation method adopted by the present invention has a better aggregation effect.

[0106] In a specific embodiment of the present invention, the aggregation effect of the first three switching frequencies and integer multiples of the ultra-high harmonics is quantified using the above-mentioned aggregation degree of the ultra-high harmonics, and the aggregation ratios of the first three switching frequencies and integer multiples of the ultra-high harmonics are obtained as SHAGP1=99.26%, SHAGP2=99.69%, and SHAGP3=86.33%, respectively. Among them, the ultra-high harmonic aggregation ratio of 3 times the switching frequency is less than 99%, which should be affected by interference factors such as resonance in the circuit.

[0107] In a specific embodiment of the present invention, the above-mentioned calculation of the ultra-high harmonic peak variation factor after aggregation based on the amplitude after ultra-high harmonic aggregation is used. Since the device under test adopts unipolar modulation, the ultra-high harmonic peak variation factors of 2-4 times the switching frequency are SHPVF2=15.33%, SHPVF3=110.19%, and SHPVF4=36.50%, respectively. That is, after the ultra-high harmonic aggregation, the second peak attenuates to 15.33% of the first peak, the third peak attenuates to 110.19% of the second peak, and the fourth peak attenuates to 36.50% of the third peak. Among them, the third switching frequency peak variation factor SHPVF3 is greater than 1, and harmonic amplification should occur.

[0108] Based on the same inventive concept, the present invention also provides an ultra-high harmonic quantization device based on variable frequency band aggregation, such as Figure 7As shown, the device includes:

[0109] Aggregation module, used for frequency band aggregation of ultra-high harmonics;

[0110] Amplitude calculation module, used to obtain the amplitude of ultra-high harmonics after aggregation;

[0111] A calculation module, used for calculating the peak variation factor of the ultra-high harmonics after aggregation according to the amplitude of the ultra-high harmonics after aggregation;

[0112] The quantization module is used to quantify the peak attenuation speed of the ultra-high harmonics by using the peak change factor of the ultra-high harmonics after aggregation.

[0113] Preferably, the amplitude calculation module is specifically used to:

[0114] The following formula is used to determine the aggregated amplitude G of the ultra-high harmonics when the frequency band corresponding to the frequency F is aggregated with b as the aggregation bandwidth: b,F :

[0115]

[0116] Where, f c is the switching frequency, r is the spectrum analysis resolution, b is the aggregation bandwidth, f is the actual frequency, F is the frequency corresponding to the aggregated band, and Y f is the amplitude corresponding to the frequency f of the spectrum analysis, and m and s are positive integers.

[0117] Preferably, the aggregation module is further configured to:

[0118] In the process of band aggregation of ultra-high harmonics, a switching frequency of the ultra-high harmonics is used as the aggregation center, and the bandwidth that satisfies the following constraints I, II, III, and IV is determined:

[0119] I. Bandwidth greater than or equal to 800Hz;

[0120] II. Bandwidth is a multiple of the switching frequency;

[0121] III. If there are multiple switching frequencies for ultra-high harmonics, the bandwidth should be the common divisor of all switching frequencies;

[0122] IV. The bandwidth is an integer multiple of the spectrum analysis resolution;

[0123] If there is only one bandwidth that meets the constraints I, II, III, and IV, then that bandwidth is determined as the aggregate bandwidth; if there are multiple bandwidths that meet the constraints I, II, III, and IV, then the bandwidth closest to 800 Hz is selected as the aggregate bandwidth.

[0124] In a specific embodiment of the present invention, the above-mentioned calculation module is specifically used to:

[0125] Calculate the super-high harmonic peak variation factor SHPVF when the switching frequency multiple is n after aggregation according to the following formula: n :

[0126]

[0127] Where n is the switching frequency multiple, l is the control mode coefficient of the device under test, and the control mode of the device under test includes: bipolar modulation mode and unipolar modulation mode. When the control mode of the device under test is bipolar modulation mode, l=1, when the control mode of the device under test is unipolar modulation mode, l=2, G b,F is the aggregated amplitude of the ultra-high harmonics when the frequency band corresponding to the frequency F is obtained after the ultra-high harmonics are aggregated with b as the aggregation bandwidth. When l=1, n is a positive integer greater than or equal to 2; when l=2, n is an even number greater than or equal to 4.

[0128] The quantization module is specifically used for:

[0129] When l=1, the super-high harmonic peak variation factor SHPVF when the switching frequency multiple after aggregation is n n As a quantified quantity of the decay speed of the nth peak of the ultra-high harmonic relative to the n-1th peak;

[0130] When l=2, the super-high harmonic peak variation factor SHPVF when the switching frequency multiple after aggregation is n n As a quantified quantity of the decay speed of the nth peak of the ultra-high harmonic relative to the n-2th peak;

[0131] Among them, when the switching frequency multiple after aggregation is n, the super-high harmonic peak variation factor SHPVF n There is a positive correlation between the attenuation rate of the nth peak of the ultra-high harmonic relative to the n-1th peak or the attenuation rate of the nth peak of the ultra-high harmonic relative to the n-2nd peak.

[0132] In summary, the present invention provides a method and device for quantifying ultra-high harmonics based on variable frequency band aggregation, which performs frequency band aggregation on ultra-high harmonics to obtain the amplitude of the ultra-high harmonics after aggregation; calculates the peak change factor of the ultra-high harmonics after aggregation based on the amplitude of the ultra-high harmonics after aggregation; and quantifies the peak attenuation rate of the ultra-high harmonics using the ultra-high harmonic peak change factor after aggregation. The present invention, by performing variable frequency band aggregation on ultra-high harmonics and quantifying the peak attenuation rate of the ultra-high harmonics using the ultra-high harmonic peak change factor calculated from the amplitude after aggregation, can reflect the change in the ultra-high harmonic peak and embody the emission law of the ultra-high harmonics, thereby analyzing the severity of the ultra-high harmonics in the power system, guiding the targeted treatment of the ultra-high harmonics that have a major impact on the power system, and improving the power supply quality of the power grid.

[0133] 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 it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for quantizing ultra-high harmonics based on variable frequency band aggregation, characterized in that: The method: Perform frequency band aggregation on ultra-high-order harmonics to obtain the amplitude of the aggregated ultra-high-order harmonics; Calculate the peak variation factor of the ultra-high harmonics after aggregation according to the amplitude of the ultra-high harmonics after aggregation; quantifying the peak attenuation rate of the ultra-high harmonics using the ultra-high harmonic peak value change factor after polymerization; The calculating of the peak variation factor of the ultra-high harmonics after aggregation according to the amplitude of the ultra-high harmonics after aggregation includes: Calculate the super-high harmonic peak variation factor SHPVF when the switching frequency multiple is n after aggregation according to the following formula: n : Where G b,F is the aggregated amplitude of the ultra-high harmonics when the frequency band corresponding to the frequency F is obtained after the ultra-high harmonics are aggregated with b as the aggregation bandwidth, l is the control mode coefficient of the device under test, and the control modes of the device under test include: bipolar modulation mode and unipolar modulation mode. When the control mode of the device under test is bipolar modulation mode, l=1, n is a positive integer greater than or equal to 2, when the control mode of the device under test is unipolar modulation mode, l=2, n is an even number greater than or equal to 4, f c is the switching frequency; The method of quantifying the peak attenuation rate of ultra-high harmonics by using the peak change factor of ultra-high harmonics after polymerization includes: When l=1, the super-high harmonic peak variation factor SHPVF when the switching frequency multiple after aggregation is n n As a quantified quantity of the decay speed of the nth peak of the ultra-high harmonic relative to the n-1th peak; When l=2, the super-high harmonic peak variation factor SHPVF when the switching frequency multiple after aggregation is n n As a quantified quantity of the decay speed of the nth peak of the ultra-high harmonic relative to the n-2th peak; Among them, when the switching frequency multiple after aggregation is n, the super-high harmonic peak variation factor SHPVF n There is a positive correlation between the attenuation rate of the nth peak of the ultra-high harmonic relative to the n-1th peak or the attenuation rate of the nth peak of the ultra-high harmonic relative to the n-2nd peak.

2. The method according to claim 1, wherein The step of performing frequency band aggregation on the ultra-high harmonics to obtain the amplitude of the aggregated ultra-high harmonics includes: The following formula is used to determine the aggregated amplitude G of the ultra-high harmonics when the frequency band corresponding to the frequency F is aggregated with b as the aggregation bandwidth: b,F : Where, f c is the switching frequency, r is the spectrum analysis resolution, f is the actual frequency, Y f is the amplitude corresponding to the frequency f of the spectrum analysis, and m and s are positive integers.

3. The method according to claim 1 or 2, wherein: The process of band aggregation of ultra-high harmonics also includes: Take any switching frequency of the ultra-high harmonics as the aggregation center and determine the bandwidth that satisfies the following constraints I, II, III, and IV: I. Bandwidth greater than or equal to 800Hz; II. Bandwidth is a multiple of the switching frequency; III. If there are multiple switching frequencies for ultra-high harmonics, the bandwidth should be the common divisor of all switching frequencies; IV. The bandwidth is an integer multiple of the spectrum analysis resolution; If there is only one bandwidth that satisfies constraints I, II, III, and IV, then that bandwidth is determined as the aggregate bandwidth. If there are multiple bandwidths that meet constraints I, II, III, and IV, the bandwidth closest to 800 Hz is selected as the aggregate bandwidth.

4. A device for quantizing ultra-high harmonics based on variable frequency band aggregation, characterized in that: The device comprises: Aggregation module, used for frequency band aggregation of ultra-high harmonics; Amplitude calculation module, used to obtain the amplitude of ultra-high harmonics after aggregation; A calculation module, used for calculating the peak variation factor of the ultra-high harmonics after aggregation according to the amplitude of the ultra-high harmonics after aggregation; a quantification module, configured to quantify the peak attenuation rate of the ultra-high harmonics using the peak change factor of the ultra-high harmonics after aggregation; The computing module is specifically configured to: Calculate the super-high harmonic peak variation factor SHPVF when the switching frequency multiple is n after aggregation according to the following formula: n : Where G b,F is the aggregated amplitude of the ultra-high harmonics when the frequency band corresponding to the frequency F is obtained after the ultra-high harmonics are aggregated with b as the aggregation bandwidth, l is the control mode coefficient of the device under test, and the control modes of the device under test include: bipolar modulation mode and unipolar modulation mode. When the control mode of the device under test is bipolar modulation mode, l=1, n is a positive integer greater than or equal to 2, when the control mode of the device under test is unipolar modulation mode, l=2, n is an even number greater than or equal to 4, f c is the switching frequency; The quantization module is specifically used to: When l=1, the super-high harmonic peak variation factor SHPVF when the switching frequency multiple after aggregation is n n As a quantified quantity of the decay speed of the nth peak of the ultra-high harmonic relative to the n-1th peak; When l=2, the super-high harmonic peak variation factor SHPVF when the switching frequency multiple after aggregation is n n As a quantified quantity of the decay speed of the nth peak of the ultra-high harmonic relative to the n-2th peak; Among them, when the switching frequency multiple after aggregation is n, the super-high harmonic peak variation factor SHPVF n There is a positive correlation between the attenuation rate of the nth peak of the ultra-high harmonic relative to the n-1th peak or the attenuation rate of the nth peak of the ultra-high harmonic relative to the n-2nd peak.

5. The device according to claim 4, characterized in that The amplitude calculation module is used to obtain the amplitude of ultra-high harmonics after aggregation, including: The following formula is used to determine the aggregated amplitude G of the ultra-high harmonics when the frequency band corresponding to the frequency F is aggregated with b as the aggregation bandwidth: b,F : Where, f c is the switching frequency, r is the spectrum analysis resolution, f is the actual frequency, Y f is the amplitude corresponding to the frequency f of the spectrum analysis, and m and s are positive integers.

6. The device according to claim 4 or 5, characterized in that The aggregation module is further configured to: In the process of band aggregation of ultra-high harmonics, any switching frequency of the ultra-high harmonics is used as the aggregation center, and the bandwidth that satisfies the following constraints I, II, III, and IV is determined: I. Bandwidth greater than or equal to 800Hz; II. Bandwidth is a multiple of the switching frequency; III. If there are multiple switching frequencies for ultra-high harmonics, the bandwidth should be the common divisor of all switching frequencies; IV. The bandwidth is an integer multiple of the spectrum analysis resolution; If there is only one bandwidth that satisfies constraints I, II, III, and IV, then that bandwidth is determined as the aggregate bandwidth. If there are multiple bandwidths that meet constraints I, II, III, and IV, the bandwidth closest to 800 Hz is selected as the aggregate bandwidth.

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