A switching frequency test method and system for a grid-forming energy storage converter module

Abstract

The present invention relates to the technical field of energy storage converters, and in particular to a switching frequency testing method and system for a grid-type energy storage converter module. The present invention obtains switching characteristic waveforms of a grid-type energy storage converter under full-load and half-load conditions, and obtains and analyzes switching signals, current waveforms, and voltage waveforms. This allows for a comprehensive analysis of the converter's behavior under different load conditions, accurately calculates the duty cycle and response time, and helps determine the performance of switching elements under different operating conditions. Frequency domain analysis effectively identifies periodic components and harmonics in signals, reducing the impact of electromagnetic interference and noise on time domain signals. The method for obtaining total switching loss through full-load and half-load switching frequencies effectively overcomes the problem of inaccurate switching frequency measurement due to electromagnetic interference and noise, thereby improving the accuracy of loss calculation and the effectiveness of stable performance evaluation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage converter, in particular to a switching frequency test method and system for grid-connected energy storage converter module. BACKGROUND

[0002] The grid-connected energy storage converter is a power electronic device used to connect energy storage systems (such as batteries) and power grids, and its main function is to convert DC power into AC power to supply power grids or power loads. The grid-connected converter is particularly suitable for renewable energy (such as solar energy and wind energy) integration, microgrid systems and large-scale energy storage systems. Switching test is a process of evaluating and measuring the performance of switching elements in the grid-connected energy storage converter.

[0003] In actual testing, the switching signal waveform may be affected by electromagnetic interference, noise, etc., which makes the signal captured by the oscilloscope or spectrum analyzer not clear enough, resulting in inaccurate measurement of switching frequency. SUMMARY

[0004] The main purpose of the present application is to provide a switching frequency test method for grid-connected energy storage converter module, which aims to solve the technical problems in the prior art.

[0005] The present application provides a switching frequency test method for grid-connected energy storage converter module, comprising:

[0006] Obtaining full-load switching characteristic waveform diagram and half-load switching characteristic waveform diagram of the grid-connected energy storage converter under full-load and half-load conditions respectively, wherein the full-load switching characteristic waveform diagram includes switching signal waveform diagram, current waveform diagram and voltage waveform diagram;

[0007] According to the switching signal waveform diagram, the duty cycle and response time are obtained, and the total period is obtained according to the duty cycle and response time;

[0008] According to the current waveform diagram and voltage waveform diagram, the average output current and average output voltage are obtained, and the average output power is obtained according to the average output voltage and average output current;

[0009] Obtaining the time-domain waveform of the switching signal waveform diagram, and converting the time-domain waveform into frequency-domain waveform according to Fourier transform to obtain the frequency spectrum;

[0010] According to the frequency spectrum, the total harmonic distortion is obtained, and the full-load switching frequency is obtained according to the total harmonic distortion, average output power and total period;

[0011] According to the half-load switching characteristic waveform diagram, the half-load switching frequency is obtained;

[0012] According to the full load switching frequency and the half load switching frequency, a total switching loss is obtained, and the stability performance of the network-structured energy storage converter is evaluated according to the total switching loss.

[0013] Preferably, the step of obtaining the duty cycle and the response duration according to the switching signal waveform diagram comprises:

[0014] A cycle duration is obtained according to the switching signal waveform diagram.

[0015] A plurality of high level time points and a plurality of low level time points within the cycle duration are obtained according to the switching signal waveform diagram, and a high level duration and a low level duration are obtained according to the plurality of high level time points and the plurality of low level time points, respectively.

[0016] A total falling duration is obtained according to a plurality of adjacent two high level time points to low level time points.

[0017] A total rising duration is obtained according to a plurality of adjacent two low level time points to high level time points.

[0018] The duty cycle is calculated according to the cycle duration, the high level duration, the low level duration, the total falling duration and the total rising duration, and the calculation formula is:

[0019]

[0020] Wherein, Z(B) represents the duty cycle, s(c) represents the total rising duration, g(c) represents the high level duration, d(c) represents the low level duration, z(s) represents, and x(c) represents the total falling duration.

[0021] An initial response time point and a target steady state value are obtained according to the switching signal waveform diagram, and a stable response time point is obtained according to the target steady state value.

[0022] A response duration is obtained according to the stable response time point and the initial response time point.

[0023] Preferably, the step of obtaining the average output current and the average output voltage according to the current waveform diagram and the voltage waveform diagram, respectively, and obtaining the average output power according to the average output voltage and the average output current comprises:

[0024] The duty cycle is obtained.

[0025] The peak current is obtained according to the current waveform diagram, and the average output current is obtained according to the peak current and the duty cycle.

[0026] The peak voltage is obtained according to the voltage waveform diagram, and the average output voltage is obtained according to the peak voltage and the duty cycle.

[0027] The average output power is obtained according to the product of the average output voltage and the average output current.

[0028] As a preferred, the step of obtaining the total harmonic distortion according to the spectrum, and obtaining the full load switching frequency according to the total harmonic distortion, the average output power and the total period, comprises:

[0029] Obtaining the maximum amplitude value of the spectrum as the fundamental wave amplitude;

[0030] Obtaining the harmonic order according to the spectrum, and obtaining a plurality of harmonic frequencies according to the harmonic order and the fundamental wave amplitude;

[0031] Obtaining the closest frequency point from the frequency axis of the spectrum according to each of the harmonic frequencies, and obtaining the corresponding harmonic amplitude according to the frequency point;

[0032] Calculating the total harmonic distortion according to the fundamental wave amplitude and the plurality of harmonic amplitudes, wherein the calculation formula is:

[0033]

[0034] Wherein, Z(X) represents the total harmonic distortion, J(f) represents the fundamental wave amplitude, X(F) i represents the i-th harmonic amplitude, i represents the serial number of the harmonic amplitude, and n represents the number of the harmonic amplitude;

[0035] Obtaining the average output power and the total period;

[0036] Calculating the full load switching frequency according to the total harmonic distortion, the average output power and the total period, wherein the calculation formula is:

[0037]

[0038] Wherein, Q(P) represents the full load switching frequency, Z(T) represents the total period, Z(X) represents the total harmonic distortion, and P(W) represents the average output power.

[0039] As a preferred, the step of obtaining the total switching loss according to the full load switching frequency and the half load switching frequency, and evaluating the stability performance of the grid-connected energy storage converter according to the total switching loss, comprises:

[0040] Obtaining the full load switching loss according to the full load switching frequency;

[0041] Obtaining the half load switching loss according to the half load switching frequency;

[0042] Obtaining the total switching loss according to the full load switching loss and the half load switching loss, and obtaining the energy conversion efficiency according to the total switching loss;

[0043] determining whether the energy conversion efficiency is greater than a preset energy conversion efficiency;

[0044] if the energy conversion efficiency is greater than the preset energy conversion efficiency, determining that the stability performance of the grid-forming energy storage converter is better;

[0045] if the energy conversion efficiency is not greater than the preset energy conversion efficiency, determining that the stability performance of the grid-forming energy storage converter is poor.

[0046] Preferably, the step of obtaining the full-load switching loss according to the full-load switching frequency comprises:

[0047] obtaining the load current and the duty cycle of the grid-forming energy storage converter in the full-load state according to the full-load switching frequency;

[0048] obtaining the on-resistance, the on-time, the off-time and the drain-source voltage of the switch of the grid-forming energy storage converter;

[0049] calculating the on-loss according to the duty cycle, the load current and the on-resistance, wherein the calculation formula is:

[0050] D(S)=F(L) 2 *Z(B)*D(R);

[0051] wherein D(S) represents the on-loss, F(L) represents the load current, Z(B) represents the duty cycle, and D(R) represents the on-resistance;

[0052] calculating the switching loss according to the drain-source voltage, the load current, the full-load switching frequency, the on-time and the off-time, wherein the calculation formula is:

[0053]

[0054] wherein K(S) represents the switching loss, F(L) represents the load current, L(v) represents the drain-source voltage, T(D) represents the on-time, T(G) represents the off-time, and Q(P) represents the full-load switching frequency.

[0055] The application also provides a switching frequency test system for a grid-forming energy storage converter module, comprising:

[0056] a first obtaining module for obtaining full-load switching characteristic waveform diagrams and half-load switching characteristic waveform diagrams of the grid-forming energy storage converter in full-load and half-load states respectively, wherein the full-load switching characteristic waveform diagrams comprise a switching signal waveform diagram, a current waveform diagram and a voltage waveform diagram;

[0057] a second obtaining module for obtaining a duty cycle and a response time according to the switching signal waveform diagram, and obtaining a total period according to the duty cycle and the response time.

[0058] a third obtaining module, configured to obtain an average output current and an average output voltage according to the current waveform diagram and the voltage waveform diagram respectively, and obtain an average output power according to the average output voltage and the average output current;

[0059] a conversion module, configured to obtain a time-domain waveform of the switching signal waveform diagram, and convert the time-domain waveform into a frequency-domain waveform according to Fourier transform to obtain a frequency spectrum;

[0060] a fourth obtaining module, configured to obtain a total harmonic distortion according to the frequency spectrum, and obtain a full-load switching frequency according to the total harmonic distortion, the average output power and a total period;

[0061] a fifth obtaining module, configured to obtain a half-load switching frequency according to the half-load switching characteristic waveform diagram;

[0062] an evaluation module, configured to obtain a total switching loss according to the full-load switching frequency and the half-load switching frequency, and evaluate a stability performance of the grid-forming energy storage converter according to the total switching loss.

[0063] Preferably, the second obtaining module comprises:

[0064] a first obtaining unit, configured to obtain a period length according to the switching signal waveform diagram;

[0065] a second obtaining unit, configured to obtain a plurality of high-level time points and a plurality of low-level time points within the period length according to the switching signal waveform diagram, and obtain a high-level duration and a low-level duration according to the plurality of high-level time points and the plurality of low-level time points respectively;

[0066] a third obtaining unit, configured to obtain a total falling duration according to a plurality of adjacent two high-level time points to low-level time points;

[0067] a fourth obtaining unit, configured to obtain a total rising duration according to a plurality of adjacent two low-level time points to high-level time points;

[0068] a calculation unit, configured to calculate a duty cycle according to the period length, the high-level duration, the low-level duration, the total falling duration and the total rising duration, wherein a calculation formula is:

[0069]

[0070] wherein Z(B) represents the duty cycle, s(c) represents the total rising duration, g(c) represents the high-level duration, d(c) represents the low-level duration, z(s) represents the total falling duration, and x(c) represents the total rising duration;

[0071] The fifth acquisition unit is configured to acquire an initial response time and a target steady-state value according to the switch signal waveform diagram, and acquire a stable response time according to the target steady-state value;

[0072] The sixth acquisition unit is configured to acquire a response duration according to the stable response time and the initial response time.

[0073] The application further provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the switch frequency test method of the network-constructed energy storage converter module when executing the computer program.

[0074] The application further provides a computer readable storage medium, which stores a computer program, and the computer program implements the steps of the switch frequency test method of the network-constructed energy storage converter module when executed by a processor.

[0075] The application has the following beneficial effects: the switch characteristic waveform diagram of the network-constructed energy storage converter under full load and half load conditions is acquired, and the switch signal, current waveform and voltage waveform are acquired and analyzed, the behavior of the converter under different load conditions can be comprehensively analyzed, the duty cycle and response duration can be accurately calculated, the performance of the switch element under different working conditions can be judged, the stability and reliability of the network-constructed energy storage converter can be better evaluated through comparison between the full load and half load conditions, the periodic component and harmonic in the signal can be effectively identified through frequency domain analysis, the influence of electromagnetic interference and noise on the time domain signal is reduced, the complex time domain signal can be decomposed into different frequency components through Fourier transform, so that the useful signal can be extracted more clearly in the presence of interference, the switch loss under different load conditions can be more accurately reflected through the combination of full load and half load switch frequencies, this method considers the switch characteristics under different working conditions, can provide more real loss evaluation, the running efficiency and stability of the converter under different loads can be more intuitively understood through evaluation of the total loss, the method of acquiring the total switch loss through full load and half load switch frequencies can effectively overcome the problem of inaccurate switch frequency measurement caused by electromagnetic interference and noise, not only improves the accuracy of loss calculation and the effectiveness of stability performance evaluation, but also provides important data support for optimization and fault warning of the converter, and lays a foundation for reliable operation of the network-constructed energy storage converter. BRIEF DESCRIPTION OF DRAWINGS

[0076] Fig. 1 The method flowchart of an embodiment of the application.

[0077] Fig. 2 The device structure schematic diagram of an embodiment of the application.

[0078] Fig. 3 Fig. 1 is a schematic diagram of the internal structure of a computer device according to an embodiment of the present application.

[0079] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0080] It should be understood that the specific embodiments described herein merely exemplify the application and do not limit the application.

[0081] As shown in the accompanying drawings, Figs. 1-3 The present application provides a switching frequency test method for a network-constructing energy storage converter module, comprising:

[0082] S1, obtaining full-load switching characteristic waveform graphs and half-load switching characteristic waveform graphs of the network-constructing energy storage converter under full-load and half-load states, respectively, wherein the full-load switching characteristic waveform graphs include switching signal waveform graphs, current waveform graphs and voltage waveform graphs;

[0083] S2, obtaining duty cycles and response time lengths according to the switching signal waveform graphs, and obtaining total periods according to the duty cycles and the response time lengths;

[0084] S3, obtaining average output currents and average output voltages according to the current waveform graphs and the voltage waveform graphs, respectively, and obtaining average output powers according to the average output voltages and the average output currents;

[0085] S4, obtaining time-domain waveforms of the switching signal waveform graphs, and converting the time-domain waveforms into frequency-domain waveforms according to Fourier transform to obtain frequency spectrums;

[0086] S5, obtaining total harmonic distortions according to the frequency spectrums, and obtaining full-load switching frequencies according to the total harmonic distortions, the average output powers and the total periods;

[0087] S6, obtaining half-load switching frequencies according to the half-load switching characteristic waveform graphs;

[0088] S7, obtaining switching total losses according to the full-load switching frequencies and the half-load switching frequencies, and evaluating the stability performance of the network-constructing energy storage converter according to the switching total losses.

[0089] The grid-connected energy storage converter is a power electronic device for connecting energy storage systems (such as batteries) with the grid, and its main function is to convert DC power into AC power to supply the grid or power loads. The grid-connected converter is particularly suitable for renewable energy (such as solar and wind energy) integration, microgrid systems, and large-scale energy storage systems. Switching test is a process of evaluating and measuring the performance of switching elements in the grid-connected energy storage converter. In actual testing, the switching signal waveform may be affected by electromagnetic interference, noise, etc., which makes the signal captured by the oscilloscope or spectrum analyzer not clear enough, resulting in inaccurate measurement of switching frequency. The present application obtains full-load switching characteristic waveform diagram and half-load switching characteristic waveform diagram of the grid-connected energy storage converter under full-load and half-load conditions, respectively. The full-load state refers to the operation of the converter at its rated power (maximum output capability), and the full-load switching characteristic waveform diagram refers to the time-domain waveform diagram of the converter switching signal recorded under full-load condition. The half-load state refers to the operation of the converter at half or close to half of its rated power, and the half-load switching characteristic waveform diagram refers to the time-domain waveform diagram of the converter switching signal recorded under half-load condition. The full-load switching characteristic waveform diagram includes switching signal waveform diagram, current waveform diagram and voltage waveform diagram. Then the duty cycle and response time are obtained according to the switching signal waveform diagram, and the total period is obtained according to the duty cycle and response time. By obtaining the switching characteristic waveform diagram of the grid-connected energy storage converter under full-load and half-load conditions, and obtaining and analyzing the switching signal, current waveform and voltage waveform, the behavior of the converter under different load conditions can be comprehensively analyzed, and its performance can be fully understood. By comparing and analyzing the waveforms under full-load and half-load conditions, the duty cycle and response time can be accurately calculated, which directly affect the calculation of switching frequency. These parameters can help to judge the performance of switching elements under different working conditions. The total period information obtained can reflect the dynamic response of the converter under different load conditions, which is helpful to evaluate the stability and consistency of switching frequency in actual application. By comparing full-load and half-load conditions, the stability and reliability of the grid-connected energy storage converter can be better evaluated.

[0090] The average output current and the average output voltage are obtained according to the current waveform diagram and the voltage waveform diagram respectively, and the average output power is obtained according to the average output voltage and the average output current, so that by directly calculating the average output current and voltage, the influence of electromagnetic interference and noise on the instantaneous signal waveform can be reduced, and the instantaneous signal may be distorted when it is disturbed, and the calculation of the average value can better reflect the actual output situation. Since the switching signal waveform is easily affected by electromagnetic interference, direct measurement of the switching frequency may not be accurate enough. By obtaining the average current and voltage, the influence of short-term interference can be filtered to some extent, providing a more stable frequency measurement basis. Compared with analyzing the rapidly changing switching waveform, the calculation of the average output current and voltage is generally relatively simple, reducing the dependence on complex algorithms or high-frequency processors and reducing the complexity of the test system. Not only does it improve the accuracy and reliability of the test, but it also effectively reduces the influence of electromagnetic interference and noise on the switching frequency measurement. By obtaining the time-domain waveform of the switching signal waveform diagram, and converting the time-domain waveform into a frequency-domain waveform to obtain the frequency spectrum according to the Fourier transform, the total harmonic distortion is obtained according to the frequency spectrum, and the full-load switching frequency is obtained according to the total harmonic distortion, the average output power and the total period. Similarly, the half-load switching frequency is obtained according to the half-load switching characteristic waveform. In this way, through frequency domain analysis, the periodic component and harmonics in the signal can be effectively identified, reducing the influence of electromagnetic interference and noise on the time-domain signal. Through Fourier transform, complex time-domain signals can be decomposed into different frequency components, so that even in the presence of interference, useful signals can be extracted more clearly. The total harmonic distortion can be directly calculated through the frequency spectrum, reflecting the quality of the switching signal. Frequency spectrum analysis can directly identify the main frequency components, thereby accurately determining the switching frequency. Especially in an environment with interference, compared with simple time-domain measurement, this method can provide more reliable frequency information. Frequency domain processing can more flexibly apply filtering and noise reduction techniques to improve signal clarity. By removing interference components in the frequency domain, more accurate signals can be obtained, improving the measurement accuracy of the switching frequency.

[0091] By obtaining the total switching loss according to the full-load switching frequency and the half-load switching frequency, and evaluating the stability performance of the network-constructed energy storage converter according to the total switching loss, the switching loss under different load conditions can be more accurately reflected by the combination of the full-load and half-load switching frequencies. This method considers the switching characteristics under different working conditions and can provide more realistic loss evaluation. Since the total switching loss is one of the key indicators of the performance of the converter, by evaluating the total loss, the running efficiency and stability of the converter under different loads can be more intuitively understood. In the case of electromagnetic interference and noise, simply relying on the switching signal waveform for frequency measurement may lead to incorrect results. By calculating the total switching loss, the influence of frequency on system performance can be indirectly reflected, reducing the dependence on direct measurement. Directly calculating the loss through frequency simplifies the measurement and analysis process compared to real-time analysis of complex and unstable signals. This simplification makes the testing process more efficient and repeatable. Therefore, the method of obtaining the total switching loss through the full-load and half-load switching frequencies can effectively overcome the problem of inaccurate switching frequency measurement caused by electromagnetic interference and noise. It not only improves the accuracy of loss calculation and the effectiveness of stability performance evaluation, but also provides important data support for the optimization and fault warning of the converter, laying a foundation for the reliable operation of the network-constructed energy storage converter.

[0092] In one embodiment, the step S2 of obtaining the duty cycle and the response time according to the switching signal waveform diagram comprises:

[0093] S21, obtaining the cycle time according to the switching signal waveform diagram;

[0094] S22, obtaining a plurality of high-level time points and a plurality of low-level time points within the cycle time according to the switching signal waveform diagram, and obtaining the high-level duration and the low-level duration according to the plurality of high-level time points and the plurality of low-level time points respectively;

[0095] S23, obtaining the total falling time according to a plurality of adjacent two high-level time points to low-level time points;

[0096] S24, obtaining the total rising time according to a plurality of adjacent two low-level time points to high-level time points;

[0097] S25, calculating the duty cycle according to the cycle time, the high-level duration, the low-level duration, the total falling time and the total rising time, wherein the calculation formula is:

[0098]

[0099] Wherein, Z(B) represents a duty cycle, s(c) represents a total rising duration, g(c) represents a high level duration, d(c) represents a low level duration, z(s) represents, x(c) represents a total falling duration;

[0100] S26, obtaining an initial response time and a target steady state value according to the switch signal waveform diagram, and obtaining a stable response time according to the target steady state value;

[0101] S27, obtaining a response duration according to the stable response time and the initial response time.

[0102] As described in steps S21-S27 above, the present application obtains the cycle length through the switch signal waveform diagram, and obtains the high level duration and the low level duration according to the multiple high level time points and the multiple low level time points within the cycle length obtained from the switch signal waveform diagram. The high level duration refers to the length of time that the signal remains in the high level state (usually corresponding to the switch on state) in the waveform of the switch signal, and the low level duration refers to the length of time that the signal remains in the low level state (usually corresponding to the switch off state) in the waveform of the switch signal. By obtaining multiple high level and low level time points, the signal waveform can be more comprehensively analyzed, avoiding errors that may be caused by single waveform sampling. The average of multiple sampling points can reduce the influence of noise and improve the accuracy of measurement. The calculation of the duration of multiple high level and low level can obtain more stable statistical characteristics. Through the collection and calculation of multiple data points, the signal fluctuation caused by electromagnetic interference or noise can be effectively smoothed, thereby reducing the influence of unnecessary interference on the switch frequency measurement. The total falling duration is obtained according to multiple adjacent high level time points to low level time points, and the total rising duration is obtained according to multiple adjacent low level time points to high level time points. For example, 1, 6, 11, and 18 are low level time points, and 3, 9, and 15 are high level time points. Then, the total falling duration obtained according to the adjacent high level time points to low level time points is 6-3+11-9+18-15=8, and the total rising duration obtained according to the adjacent low level time points to high level time points is 5-1+9-6+15-11=11. By analyzing multiple adjacent high and low level time points, the dynamic characteristics of the switch signal can be more comprehensively captured. This method reduces the errors that may be caused by single time measurement, improves the measurement accuracy of the switch frequency, and smoothens the waveform mutation caused by electromagnetic interference and noise through multiple measurements, making the measurement results of the rising and falling durations more reliable. The duty cycle is calculated according to the cycle length, the high level duration, the low level duration, the total falling duration, and the total rising duration. By calculating the cycle length and the high level duration, a more accurate duty cycle can be obtained. This method can effectively eliminate the instantaneous fluctuations caused by electromagnetic interference and noise, ensuring that the measurement of the duty cycle is more stable and reliable. In a high noise environment, the clarity of the waveform may be affected. By analyzing multiple time parameters (high level duration, low level duration, etc.), the error introduced by single measurement can be reduced. The method of calculating the duty cycle according to the cycle length, the high level duration, the low level duration, the total falling duration, and the total rising duration can effectively improve the accuracy of switch frequency testing, improve signal quality, enhance system robustness, and support fault diagnosis and early warning. The initial response time and the target steady state value are obtained from the switch signal waveform diagram, and the stable response time is obtained according to the target steady state value. The response duration is obtained according to the stable response time and the initial response time.The target steady-state value refers to a stable state value of an output signal of a system after a certain time, which is the final value of the signal response, and usually represents a constant value to which the system tends after the input signal or initial condition changes. By determining the initial response time and the target steady-state value, the change process of the switching signal can be clearly defined, the starting point and the ending point of the response are more clear, and the measurement accuracy is improved. By obtaining the initial response time, the target steady-state value, the stable response time and the response time length according to the switching signal waveform diagram, the accuracy and reliability of the switching frequency test can be significantly improved. This method not only improves the signal analysis capability and enhances the system robustness, but also provides strong support for fault diagnosis, optimization control strategy and performance improvement, and finally ensures the safety and stability of the grid-connected energy storage converter in practical application.

[0103] In one embodiment, the step S3 of obtaining the average output current and the average output voltage according to the current waveform diagram and the voltage waveform diagram respectively, and obtaining the average output power according to the average output voltage and the average output current, comprises:

[0104] S31, obtaining a duty cycle;

[0105] S32, obtaining a peak current according to the current waveform diagram, and obtaining the average output current according to the peak current and the duty cycle;

[0106] S33, obtaining a peak voltage according to the voltage waveform diagram, and obtaining the average output voltage according to the peak voltage and the duty cycle;

[0107] S34, obtaining the average output power according to the product of the average output voltage and the average output current.

[0108] As described in steps S41-S43, the application obtains the peak current and the peak voltage from the current waveform graph and the voltage waveform graph respectively, and obtains the average output current according to the peak current and the duty cycle, and obtains the average output voltage according to the peak voltage and the duty cycle, and then obtains the average output power according to the product of the average output voltage and the average output current. The peak current and the peak voltage are directly extracted from the current waveform graph and the voltage waveform graph, which can avoid the instantaneous fluctuations caused by noise and ensure the accuracy of the measurement data. The calculation is based on the steady-state characteristics of the peak current and the peak voltage, which can reduce the influence of electromagnetic interference and noise on the average value calculation and ensure that the result is more representative. The average output current is calculated according to the peak current and the duty cycle, and the average output voltage is calculated according to the peak voltage and the duty cycle, which provides a clear calculation framework and facilitates the rapid acquisition of stable electrical parameters. The duty cycle as a control signal can effectively reflect the adjustment of the output power, and the average value calculation based on the duty cycle can adapt to changes under different working conditions. The average output power is obtained by multiplying the average output voltage and the average output current, which can provide accurate power evaluation for the energy management of the system, help optimize the working efficiency of the converter, and thus not only improve the accuracy of the measurement, but also optimize the energy management, support system performance analysis, promote fault diagnosis and enhance the robustness of the system.

[0109] In one embodiment, the step S5 of obtaining the total harmonic distortion according to the frequency spectrum, and obtaining the full-load switching frequency according to the total harmonic distortion, the average output power and the total period, comprises:

[0110] S51, obtaining the maximum amplitude value of the frequency spectrum as the fundamental amplitude;

[0111] S52, obtaining the harmonic order from the frequency spectrum, and obtaining a plurality of harmonic frequencies according to the harmonic order and the fundamental amplitude;

[0112] S53, obtaining the closest frequency point from the frequency axis of the frequency spectrum according to each of the harmonic frequencies, and obtaining the corresponding harmonic amplitude according to the frequency point;

[0113] S54, calculating the total harmonic distortion according to the fundamental amplitude and the plurality of harmonic amplitudes, wherein the calculation formula is:

[0114]

[0115] wherein Z(X) represents the total harmonic distortion, J(F) represents the fundamental amplitude, X(F) i represents the i-th harmonic amplitude, i represents the serial number of the harmonic amplitude, and n represents the number of harmonic amplitudes;

[0116] S55, obtaining the average output power and the total period;

[0117] S56, calculating a full load switching frequency according to the total harmonic distortion, the average output power and the total cycle, wherein the calculation formula is:

[0118]

[0119] Wherein Q(P) represents the full load switching frequency, Z(T) represents the total cycle, Z(X) represents the total harmonic distortion, and p(W) represents the average output power.

[0120] As described in steps S51-S56 above, the present application obtains the maximum amplitude value of the spectrum as the fundamental amplitude, obtains the harmonic order from the spectrum, and obtains the multiple harmonic frequencies from the harmonic order and the fundamental amplitude. The fundamental amplitude refers to the strongest frequency component in the spectrum, which is usually the fundamental frequency of the signal. The harmonic order refers to the integer multiple frequency component of the fundamental frequency. The harmonic frequency refers to the actual frequency of the harmonic component related to the fundamental frequency, which is equal to the multiple of the fundamental frequency, called the harmonic order. For example, the 2nd harmonic frequency is 2 times the fundamental frequency, the 3rd harmonic frequency is 3 times the fundamental frequency, and so on. Obtaining the maximum amplitude value from the spectrum as the fundamental amplitude helps to accurately evaluate the main power component of the signal, ensuring the accuracy of power calculation. Through spectral analysis, the harmonic order can be obtained, and the influence of each order of harmonic can be analyzed, which is very important for evaluating the nonlinear characteristics and harmonic distortion of the system. Harmonic analysis can help identify potential faults in the converter module, such as abnormal harmonic distribution, which may indicate component problems or insufficient control strategy. According to each harmonic frequency, the closest frequency point is obtained from the frequency axis of the spectrum, and the corresponding harmonic amplitude is obtained from the frequency point. The closest frequency point is due to the Fourier transform, which converts continuous frequency domain signals into discrete frequency domain signals. Theoretically calculated harmonic frequency may not completely fall on the actual frequency point in the spectrum. The frequency of each point in the spectrum is fixed, and the interval of these points depends on the sampling frequency and sampling time of the signal. To obtain accurate harmonic amplitude, we need to find the frequency point in the spectrum that is closest to the target harmonic frequency. Assuming we want to extract a certain harmonic frequency, such as the 3rd harmonic, whose theoretical frequency is 3 times the fundamental frequency. If the theoretical 3rd harmonic frequency is 150Hz, but the distribution of frequency points on the spectrum is discrete, for example, it may be between 149.7Hz and 150.3Hz, then the closest frequency point is 150.3Hz, because it is closest to the theoretical frequency of 150Hz. Directly extracting the harmonic amplitude from the spectrum can effectively filter out the influence of interference and noise. Compared with directly analyzing the signal in the time domain, frequency domain analysis integrates multiple cycles of the signal, which helps to improve the signal-to-noise ratio. By finding the frequency point closest to the harmonic frequency, the actual amplitude of the harmonic can be more accurately identified, thereby improving the reliability of the measurement. Extracting the harmonic amplitude in the spectrum can more clearly display the harmonic distribution caused by nonlinear loads or other devices. According to the fundamental amplitude and multiple harmonic amplitudes, the total harmonic distortion is calculated, and then the full load switching frequency is calculated according to the total harmonic distortion, average output power, and total period,

[0121] In one embodiment, the step S7 of obtaining the total switching loss according to the full load switching frequency and half load switching frequency, and evaluating the stability performance of the grid-connected energy storage converter according to the total switching loss, comprises:

[0122] S71, obtaining full load switching loss according to the full load switching frequency;

[0123] S71, obtaining half load switching loss according to the half load switching frequency;

[0124] S71, obtaining total switching loss according to the full load switching loss and the half load switching loss, and obtaining energy conversion efficiency according to the total switching loss;

[0125] S71, judging whether the energy conversion efficiency is greater than a preset energy conversion efficiency;

[0126] If the energy conversion efficiency is greater than the preset energy conversion efficiency, it is determined that the stability performance of the grid-connected energy storage converter is better.

[0127] If the energy conversion efficiency is not greater than the preset energy conversion efficiency, it is determined that the stability performance of the grid-connected energy storage converter is poorer.

[0128] As described in steps S8-S10, the full load switching loss is obtained according to the full load switching frequency, the half load switching loss is obtained according to the half load switching frequency, the total switching loss is obtained according to the full load switching loss and the half load switching loss, and the energy conversion efficiency is obtained according to the total switching loss. Specifically, the output power of the converter is obtained, and the formula wherein N(Z) represents the energy conversion efficiency, S(W) represents the output power of the converter, and Z(K) represents the total switching loss. The energy conversion efficiency can be calculated, the performance of the converter under different working conditions can be more comprehensively reflected by measuring the switching loss under full load and half load respectively, the error caused by unclear signals is reduced, the test of full load and half load can provide more abundant data, the understanding of system performance is enhanced, the loss characteristics under different load conditions are helped to identify, the signal-to-noise ratio can be improved by using spectrum analysis when measuring the full load and half load switching loss, thereby effectively reducing the influence of electromagnetic interference on the measurement result, the total switching loss can be more accurately evaluated by comprehensively considering the switching loss of full load and half load, the error influence under single load condition is avoided, the energy conversion efficiency can be more truly reflected by accurately calculating the total switching loss, the running efficiency of the system under different loads is fully evaluated, and then whether the energy conversion efficiency is greater than the preset energy conversion efficiency is judged. If the energy conversion efficiency is greater than the preset energy conversion efficiency, it is determined that the stability performance of the grid-connected energy storage converter is better, otherwise it is determined that the stability performance of the grid-connected energy storage converter is poorer.

[0129] In one embodiment, the step of obtaining full load switching loss according to the full load switching frequency comprises:

[0130] According to the full load switch frequency, the load current and the duty cycle of the network-forming energy storage converter in a full load state are obtained;

[0131] The on-resistance, the on time, the off time and the drain-source voltage of the switch of the network-forming energy storage converter are obtained;

[0132] According to the duty cycle, the load current and the on-resistance, the on-loss is calculated, and the calculation formula is:

[0133] D(S)=F(L) 2 *Z(B)*D(R);

[0134] Wherein, D(S) represents the on-loss, F(L) represents the load current, Z(B) represents the duty cycle, and D(R) represents the on-resistance;

[0135] According to the drain-source voltage, the load current, the full load switch frequency, the on time and the off time, the switch loss is calculated, and the calculation formula is:

[0136]

[0137] Wherein, K(S) represents the switch loss, F(L) represents the load current, L(V) represents the drain-source voltage, T(D) represents the on time, T(G) represents the off time, and Q(P) represents the full load switch frequency.

[0138] As described in steps S101-S103 above, the present application obtains the load current and duty cycle of the grid-forming energy storage converter in the full load state through the full load switching frequency, obtains the on-resistance, on-time, off-time and drain-source voltage of the switching of the grid-forming energy storage converter, calculates the on-loss according to the duty cycle, load current and on-resistance, and calculates the switching loss according to the drain-source voltage, load current, full load switching frequency, on-time and off-time. In this way, by directly measuring the load current and duty cycle, the dependence on switching frequency measurement can be fundamentally reduced, thereby reducing the influence of noise and electromagnetic interference on the results. Combined with multiple parameters (such as on-resistance, on-time, etc.), comprehensive calculation can more comprehensively reflect the switching performance and enhance the reliability of the results. According to the duty cycle, load current and on-resistance, the on-loss can be calculated to provide more accurate loss data, which is crucial for evaluating the efficiency of the converter. The method of obtaining the load current and duty cycle through the full load switching frequency, and calculating the on-loss and switching loss in combination with the on-resistance, on-time, off-time and drain-source voltage, can effectively solve the problem of unclear signals in the switching frequency test of the grid-forming energy storage converter module. This method improves measurement accuracy, optimizes loss calculation, enhances system performance monitoring, supports design optimization, and simplifies the test process, thereby providing strong support for performance evaluation and optimized design of the converter.

[0139] The present application also provides a switching frequency test system for a grid-forming energy storage converter module, comprising:

[0140] A first obtaining module is configured to obtain full load switching characteristic waveform graphs and half load switching characteristic waveform graphs of a grid-forming energy storage converter in full load and half load states, respectively. The full load switching characteristic waveform graphs include switching signal waveform graphs, current waveform graphs and voltage waveform graphs.

[0141] A second obtaining module is configured to obtain a duty cycle and a response time according to the switching signal waveform graphs, and obtain a total period according to the duty cycle and the response time.

[0142] A third obtaining module is configured to obtain an average output current and an average output voltage according to the current waveform graphs and voltage waveform graphs, respectively, and obtain an average output power according to the average output voltage and the average output current.

[0143] A conversion module is configured to obtain a time-domain waveform of the switching signal waveform graphs, and convert the time-domain waveform into a frequency-domain waveform according to Fourier transform to obtain a frequency spectrum.

[0144] A fourth obtaining module is configured to obtain a total harmonic distortion according to the frequency spectrum, and obtain a full load switching frequency according to the total harmonic distortion, average output power and total period.

[0145] The fifth acquisition module is configured to acquire a half-load switch frequency according to the half-load switch characteristic waveform.

[0146] The evaluation module is configured to acquire total switch loss according to the full-load switch frequency and the half-load switch frequency, and evaluate the stability performance of the network-type energy storage converter according to the total switch loss.

[0147] In one embodiment, the second acquisition module comprises:

[0148] The first acquisition unit is configured to acquire a cycle duration according to the switch signal waveform.

[0149] The second acquisition unit is configured to acquire a plurality of high-level time points and a plurality of low-level time points within the cycle duration according to the switch signal waveform, and acquire a high-level duration and a low-level duration according to the plurality of high-level time points and the plurality of low-level time points respectively.

[0150] The third acquisition unit is configured to acquire a total falling duration according to a plurality of adjacent two high-level time points to low-level time points.

[0151] The fourth acquisition unit is configured to acquire a total rising duration according to a plurality of adjacent two low-level time points to high-level time points.

[0152] The calculation unit is configured to calculate a duty cycle according to the cycle duration, the high-level duration, the low-level duration, the total falling duration and the total rising duration, wherein the calculation formula is:

[0153]

[0154] wherein Z(B) represents the duty cycle, s(c) represents the total rising duration, g(c) represents the high-level duration, d(c) represents the low-level duration, z(s) represents the total falling duration, and x(c) represents the total rising duration.

[0155] The fifth acquisition unit is configured to acquire an initial response time point and a target steady-state value according to the switch signal waveform, and acquire a stable response time point according to the target steady-state value.

[0156] The sixth acquisition unit is configured to acquire a response duration according to the stable response time point and the initial response time point.

[0157] The application further provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the switch frequency test method of the network-type energy storage converter module when executing the computer program.

[0158] The application further provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of the switch frequency test method of the network-constructed energy storage converter module.

[0159] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by a computer program instructing related hardware, and the computer program can be stored in a non-volatile computer readable storage medium, and when the computer program is executed, the processes of the above-mentioned embodiment methods can be included. Any reference to memory, storage, database or other medium provided by the present application and used in the embodiments can include non-volatile and / or volatile memory. The non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. The volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (SSRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM) and memory bus dynamic RAM (RDRAM) and the like.

[0160] It should be noted that in this document, the terms "comprising", "containing", or any other similar term are intended to encompass non-exclusive inclusions, such that a process, device, article or method that comprises a list of elements does not only include those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such a process, device, article or method. Without more limitations, the element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, device, article or method comprising the element.

[0161] The above description is only the preferred embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the present application.

Claims

1. A switching frequency testing method for a grid-type energy storage converter module, characterized in that: include: Obtaining a full-load switching characteristic waveform diagram and a half-load switching characteristic waveform diagram of the grid-type energy storage converter under full-load and half-load states, respectively, wherein the full-load switching characteristic waveform diagram includes a switching signal waveform diagram, a current waveform diagram, and a voltage waveform diagram; Obtaining a duty cycle and a response time according to the switching signal waveform, and obtaining a total cycle according to the duty cycle and the response time; Obtaining an average output current and an average output voltage according to the current waveform diagram and the voltage waveform diagram, respectively, and obtaining an average output power according to the average output voltage and the average output current; Acquire a time domain waveform of the switching signal waveform diagram, and convert the time domain waveform into a frequency domain waveform according to Fourier transform to obtain a frequency spectrum; Obtaining total harmonic distortion according to the frequency spectrum, and obtaining a full-load switching frequency according to the total harmonic distortion, average output power, and total period; Obtaining a half-load switching frequency according to the half-load switching characteristic waveform diagram; Obtaining a total switching loss according to the full-load switching frequency and the half-load switching frequency, and evaluating the stability performance of the grid-type energy storage converter according to the total switching loss; The step of obtaining total harmonic distortion according to the spectrum, and obtaining full-load switching frequency according to the total harmonic distortion, average output power and total period includes: Obtaining the maximum amplitude value of the spectrum as the fundamental wave amplitude; Acquire a harmonic order according to the frequency spectrum, and acquire a plurality of harmonic frequencies according to the harmonic order and the fundamental wave amplitude; Obtaining the closest frequency point on the frequency axis of the spectrum according to each harmonic frequency, and obtaining the corresponding harmonic amplitude according to the frequency point; The total harmonic distortion is calculated based on the fundamental wave amplitude and multiple harmonic amplitudes, wherein the calculation formula is: ； in, Indicates total harmonic distortion, represents the fundamental amplitude, Indicates the harmonic amplitudes, The serial number representing the harmonic amplitude, The number representing the harmonic amplitude; Get the average output power and total cycle; The full load switching frequency is calculated based on the total harmonic distortion, average output power and total period, wherein the calculation formula is: ； in, represents the full load switching frequency, represents the total period, Indicates total harmonic distortion, Indicates the average output power.

2. The switching frequency testing method of the grid-type energy storage converter module according to claim 1, characterized in that: The step of obtaining the duty cycle and response time according to the switching signal waveform diagram includes: Obtaining a cycle duration according to the switching signal waveform diagram; Acquire multiple high-level moments and multiple low-level moments within a cycle duration according to the switching signal waveform diagram, and respectively acquire high-level duration and low-level duration according to the multiple high-level moments and the multiple low-level moments; Obtain the total falling time from two adjacent high-level moments to the low-level moment; Obtain the total rising time from two adjacent low-level moments to a high-level moment; The duty cycle is calculated according to the cycle duration, high level duration, low level duration, total falling duration and total rising duration, wherein the calculation formula is: ； in, represents the duty cycle, Indicates the total ascent time, Indicates the duration of high level. Indicates the duration of low level. Indicates the cycle length, Indicates the total descent time; Obtaining an initial response time and a target steady-state value according to the switching signal waveform diagram, and obtaining a stable response time according to the target steady-state value; The response duration is acquired according to the stable response time and the initial response time.

3. The switching frequency testing method of the grid-type energy storage converter module according to claim 1, characterized in that: The steps of respectively obtaining an average output current and an average output voltage according to the current waveform diagram and the voltage waveform diagram, and obtaining an average output power according to the average output voltage and the average output current include: Get the duty cycle; Obtaining a peak current according to the current waveform diagram, and obtaining an average output current according to the peak current and the duty cycle; Obtaining a peak voltage according to the voltage waveform, and obtaining an average output voltage according to the peak voltage and the duty cycle; The average output power is obtained according to the product of the average output voltage and the average output current.

4. The switching frequency testing method of the grid-type energy storage converter module according to claim 1, characterized in that: The step of obtaining the total switching loss according to the full-load switching frequency and the half-load switching frequency, and evaluating the stability performance of the grid-type energy storage converter according to the total switching loss includes: Obtaining full-load switching loss according to the full-load switching frequency; Obtaining a half-load switching loss according to the half-load switching frequency; Obtaining a total switching loss according to the full-load switching loss and the half-load switching loss, and obtaining an energy conversion efficiency according to the total switching loss; Determining whether the energy conversion efficiency is greater than a preset energy conversion efficiency; If the energy conversion efficiency is greater than the preset energy conversion efficiency, it is determined that the stability performance of the grid-type energy storage converter is good; If the energy conversion efficiency is not greater than the preset energy conversion efficiency, it is determined that the stability performance of the grid-type energy storage converter is poor.

5. The switching frequency testing method of the grid-type energy storage converter module according to claim 4, characterized in that: The step of obtaining the full-load switching loss according to the full-load switching frequency includes: Obtaining a load current and a duty cycle of the grid-type energy storage converter under a full-load state according to the full-load switching frequency; Obtaining the on-resistance, on-time, off-time, and drain-source voltage of the switches of the grid-type energy storage converter; The conduction loss is calculated according to the duty cycle, load current and on-resistance, wherein the calculation formula is: ； in, represents the conduction loss, represents the load current, represents the duty cycle, represents the on-resistance; The switching loss is calculated based on the drain-source voltage, load current, full-load switching frequency, turn-on time, and turn-off time, wherein the calculation formula is: ； in, represents the switching loss, represents the load current, represents the drain-source voltage, Indicates the conduction time, Indicates closing time. Indicates the full load switching frequency.

6. A switching frequency test system for a grid-type energy storage converter module, characterized in that: include: A first acquisition module is used to obtain a full-load switch characteristic waveform diagram and a half-load switch characteristic waveform diagram of the grid-type energy storage converter under full-load and half-load states, respectively, wherein the full-load switch characteristic waveform diagram includes a switch signal waveform diagram, a current waveform diagram, and a voltage waveform diagram; a second acquisition module, configured to acquire a duty cycle and a response time according to the switching signal waveform, and acquire a total cycle according to the duty cycle and the response time; a third acquisition module, configured to respectively acquire an average output current and an average output voltage according to the current waveform diagram and the voltage waveform diagram, and acquire an average output power according to the average output voltage and the average output current; a conversion module, configured to obtain a time domain waveform of the switching signal waveform diagram, and convert the time domain waveform into a frequency domain waveform according to Fourier transform to obtain a frequency spectrum; a fourth acquisition module, configured to acquire total harmonic distortion according to the frequency spectrum, and acquire a full-load switching frequency according to the total harmonic distortion, average output power, and total period; a fifth acquisition module, configured to acquire a half-load switching frequency according to the half-load switching characteristic waveform diagram; An evaluation module, configured to obtain a total switching loss according to the full-load switching frequency and the half-load switching frequency, and evaluate the stability performance of the grid-type energy storage converter according to the total switching loss; The step of obtaining total harmonic distortion according to the spectrum, and obtaining full-load switching frequency according to the total harmonic distortion, average output power and total period includes: Obtaining the maximum amplitude value of the spectrum as the fundamental wave amplitude; Acquire a harmonic order according to the frequency spectrum, and acquire a plurality of harmonic frequencies according to the harmonic order and the fundamental wave amplitude; Obtaining the closest frequency point on the frequency axis of the spectrum according to each harmonic frequency, and obtaining the corresponding harmonic amplitude according to the frequency point; The total harmonic distortion is calculated based on the fundamental wave amplitude and multiple harmonic amplitudes, wherein the calculation formula is: ； in, Indicates total harmonic distortion, represents the fundamental amplitude, Indicates the harmonic amplitudes, The serial number representing the harmonic amplitude, The number representing the harmonic amplitude; Get the average output power and total cycle; The full load switching frequency is calculated based on the total harmonic distortion, average output power and total period, wherein the calculation formula is: ； in, represents the full load switching frequency, represents the total period, Indicates total harmonic distortion, Indicates the average output power.

7. The switching frequency testing system of the grid-type energy storage converter module according to claim 6, characterized in that: The second acquisition module includes: A first acquiring unit, configured to acquire a cycle duration according to the switching signal waveform diagram; A second acquiring unit is configured to acquire a plurality of high-level moments and a plurality of low-level moments within a cycle duration according to the switching signal waveform diagram, and respectively acquire a high-level duration and a low-level duration according to the plurality of high-level moments and the plurality of low-level moments; A third acquiring unit is configured to acquire a total falling time according to a plurality of adjacent high-level moments to low-level moments; A fourth acquiring unit, configured to acquire a total rising time according to a plurality of adjacent two low-level moments to a high-level moment; A calculation unit is used to calculate the duty cycle according to the cycle duration, the high level duration, the low level duration, the total falling duration and the total rising duration, wherein the calculation formula is: ； in, represents the duty cycle, Indicates the total ascent time, Indicates the duration of high level. Indicates the duration of low level. Indicates the cycle length, Indicates the total descent time; a fifth acquiring unit, configured to acquire an initial response time and a target steady-state value according to the switching signal waveform diagram, and acquire a stable response time according to the target steady-state value; A sixth acquiring unit is configured to acquire a response duration according to the stable response time and the initial response time.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 5 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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