Harmonic control method and device for inverter of photovoltaic power station

Abstract

The invention discloses a photovoltaic power station inverter harmonic control method and device, and relates to the technical field of photovoltaic power generation, and the method comprises the steps: carrying out the harmonic analysis of the output of a power grid and an inverter, and building a harmonic model of the output of the power grid and the inverter; determining harmonic information according to the harmonic model; setting target control parameters of a filter based on the harmonic information, and filtering; meanwhile, defining a filtering effect, and setting an adjusting period for monitoring a filtering process; and adjusting the target control parameter of the next adjustment period according to the filtering effect of the previous adjustment period. And the precision and adaptability of harmonic control are improved.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic power generation technology, and more specifically, to a method and device for controlling harmonics of a photovoltaic power station inverter. Background Art

[0002] Harmonic control of photovoltaic power station inverters is an important technical measure taken in photovoltaic power stations to reduce the adverse effects of harmonics on power grids and equipment. Harmonics refer to different frequency components that exist in the power grid at integer multiples of the fundamental frequency (usually 50Hz or 60Hz). These harmonic components are mainly generated by nonlinear loads (such as inverters, rectifiers, etc.). Harmonics can cause grid voltage distortion, equipment overheating, communication interference, and affect other users' electrical equipment. Therefore, harmonic control is an important issue in the operation and access to the power grid of photovoltaic power stations.

[0003] In the existing technology, the accuracy of harmonic control is poor and cannot adapt to the complex changes of photovoltaic power generation and power grid. If the harmonics are too high, the distortion of the power grid is high and the power quality is poor. If the harmonics are too low, the cost increases sharply and cannot adapt to the complexity of the system.

[0004] Therefore, how to improve the accuracy and adaptability of harmonic control is a technical problem that needs to be solved. Summary of the invention

[0005] The present invention provides a photovoltaic power station inverter harmonic control method to solve the technical problems of low harmonic control accuracy and poor adaptability in the prior art. The method comprises:

[0006] Conduct harmonic analysis on the output of the power grid and inverter, and establish harmonic models of the power grid and inverter output;

[0007] determining harmonic information according to a harmonic model;

[0008] The target control parameters of the filter are set based on the harmonic information, and filtering is performed;

[0009] At the same time, define the filtering effect and set the adjustment cycle for monitoring the filtering process;

[0010] The target control parameters of the next regulation cycle are adjusted according to the filtering effect of the previous regulation cycle.

[0011] In some embodiments of the present application, a harmonic model of the power grid and the inverter output is established, including:

[0012] Collect voltage and current waveform data output by the power grid and inverter;

[0013] Perform data filtering, noise removal and spurious processing on voltage and current waveform data;

[0014] Perform fast Fourier transform on the voltage and current waveform data to convert the time domain data into frequency domain data;

[0015] Perform spectrum analysis on the frequency domain data to obtain the spectrum diagram of voltage and current, so as to establish the harmonic model of the power grid and inverter output.

[0016] In some embodiments of the present application, the method further includes correcting the harmonic frequency obtained in the harmonic model of the power grid and the inverter output, including:

[0017] Define the fluctuation level of the power grid frequency;

[0018] Determine the first influencing factor according to the design of the inverter and the control strategy;

[0019] Determine the second influencing factor according to the load type and capacity output by the inverter;

[0020] The harmonic frequency is corrected based on the fluctuation level, the first impact factor and the second impact factor.

[0021] In some embodiments of the present application, setting target control parameters of the filter based on harmonic information includes:

[0022] Harmonic information includes harmonic frequency and content, and target control parameters include filter cutoff frequency, filter order and impedance;

[0023] Determine the filter cutoff frequency according to the range of harmonic frequencies;

[0024] Determine the filter order based on the content and harmonic components;

[0025] The impedance is determined based on the inverter output impedance and the grid impedance.

[0026] In some embodiments of the present application, adjusting the target control parameter of the next adjustment cycle according to the filtering effect of the previous adjustment cycle includes:

[0027] If the filtering effect of the previous adjustment cycle is lower than the filtering effect threshold corresponding to this cycle, a correction coefficient is determined according to the difference between the filtering effect of the previous adjustment cycle and the filtering effect threshold to adjust the target control parameter of the next adjustment cycle;

[0028] Otherwise, the target control parameter of the next regulation cycle is not adjusted.

[0029] Correspondingly, the present application also provides a photovoltaic power station inverter harmonic control device, the device comprising:

[0030] The first module is used to perform harmonic analysis on the output of the power grid and the inverter, and establish a harmonic model of the output of the power grid and the inverter;

[0031] The second module is used to determine harmonic information according to the harmonic model;

[0032] The third module is used to set the target control parameters of the filter based on the harmonic information and perform filtering;

[0033] The fourth module is used to simultaneously define the filtering effect and set the adjustment period for monitoring the filtering process;

[0034] The fifth module is used to adjust the target control parameters of the next regulation cycle according to the filtering effect of the previous regulation cycle.

[0035] In some embodiments of the present application, the first module is used to:

[0036] Collect voltage and current waveform data output by the power grid and inverter;

[0037] Perform data filtering, noise removal and spurious processing on voltage and current waveform data;

[0038] Perform fast Fourier transform on the voltage and current waveform data to convert the time domain data into frequency domain data;

[0039] Perform spectrum analysis on the frequency domain data to obtain the spectrum diagram of voltage and current, so as to establish the harmonic model of the power grid and inverter output.

[0040] In some embodiments of the present application, the device further includes a sixth module, which is used to:

[0041] Define the fluctuation level of the power grid frequency;

[0042] Determine the first influencing factor according to the design of the inverter and the control strategy;

[0043] Determine the second influencing factor according to the load type and capacity output by the inverter;

[0044] The harmonic frequency is corrected based on the fluctuation level, the first impact factor and the second impact factor.

[0045] In some embodiments of the present application, the third module is used to:

[0046] Harmonic information includes harmonic frequency and content, and target control parameters include filter cutoff frequency, filter order and impedance;

[0047] Determine the filter cutoff frequency according to the range of harmonic frequencies;

[0048] Determine the filter order based on the content and harmonic components;

[0049] The impedance is determined based on the inverter output impedance and the grid impedance.

[0050] In some embodiments of the present application, the fifth module is used to:

[0051] If the filtering effect of the previous adjustment cycle is lower than the filtering effect threshold corresponding to this cycle, a correction coefficient is determined according to the difference between the filtering effect of the previous adjustment cycle and the filtering effect threshold to adjust the target control parameter of the next adjustment cycle;

[0052] Otherwise, the target control parameter of the next regulation cycle is not adjusted.

[0053] By applying the above technical solutions, harmonic analysis is performed on the output of the power grid and inverter, and a harmonic model of the power grid and inverter output is established; harmonic information is determined based on the harmonic model; the target control parameters of the filter are set based on the harmonic information, and filtering is performed; at the same time, the filtering effect is defined, and the adjustment cycle for monitoring the filtering process is set; the target control parameters of the next adjustment cycle are adjusted according to the filtering effect of the previous adjustment cycle. The accuracy and adaptability of harmonic control are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0055] Figure 1 A schematic diagram of a flow chart of a photovoltaic power station inverter harmonic control method proposed in an embodiment of the present invention is shown;

[0056] Figure 2 A schematic structural diagram of a photovoltaic power station inverter harmonic control device proposed in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0058] The present application provides a method for controlling harmonics of a photovoltaic power station inverter. Figure 1 As shown, the method comprises the following steps:

[0059] Step S101 : performing harmonic analysis on the output of the power grid and the inverter, and establishing harmonic models of the output of the power grid and the inverter.

[0060] In some embodiments of the present application, a harmonic model of the power grid and the inverter output is established, including:

[0061] Collect voltage and current waveform data output by the power grid and inverter;

[0062] Perform data filtering, noise removal and spurious processing on voltage and current waveform data;

[0063] Perform fast Fourier transform on the voltage and current waveform data to convert the time domain data into frequency domain data;

[0064] Perform spectrum analysis on the frequency domain data to obtain the spectrum diagram of voltage and current, so as to establish the harmonic model of the power grid and inverter output.

[0065] In this embodiment, converting time domain data into frequency domain data by spectrum analysis methods such as fast Fourier transform (FFT) is a commonly used harmonic analysis technology, but there may be some problems in practical applications, including:

[0066] Resolution problem: The resolution of FFT depends on the sampling rate and the duration of the signal. A lower sampling rate or a shorter signal duration may result in insufficient spectrum resolution, causing low-amplitude harmonic components to be ignored or unable to be accurately measured.

[0067] Window function impact: When FFT performs spectrum analysis on time domain data, the data needs to be truncated, which may introduce spectrum leakage. In order to reduce the impact of leakage, a window function is usually applied, but choosing an inappropriate window function may also lead to inaccurate spectrum analysis results.

[0068] Window length: The accuracy and spectral resolution of FFT are also related to the window length. A shorter window length may result in reduced spectral resolution, while a longer window length may result in reduced time resolution.

[0069] Spectrum fluctuation: FFT is a spectrum analysis method based on a finite time window. The accuracy of the spectrum is affected by factors such as noise and window length, which may cause spectrum fluctuations.

[0070] Spectral leakage: When the frequencies of a signal are not exact multiples of the FFT analysis, it can cause spectral leakage, where harmonic energy is spread to other frequencies.

[0071] Phase information is lost: FFT only provides frequency amplitude information, but loses the phase information of the original signal. In some applications, phase information may be very important.

[0072] To overcome these problems, the following measures can be taken:

[0073] Increase the sampling rate to ensure sufficient spectral resolution.

[0074] Use appropriate window functions to reduce spectrum leakage and fluctuations.

[0075] Consider various spectrum analysis methods, such as beamforming.

[0076] For the need of phase information, other harmonic analysis methods can be considered, such as wavelet transform (WaveletTransform) and so on.

[0077] Step S102, determining harmonic information according to the harmonic model.

[0078] In this embodiment, the general steps for determining the harmonic frequency range are as follows:

[0079] Harmonic monitoring: First, you need to install harmonic monitoring equipment to monitor the grid side and inverter output side of the photovoltaic power station. These devices will record the voltage and current waveforms of the grid and inverter output and convert them into frequency domain data.

[0080] Data acquisition and processing: The voltage and current waveform data collected by the harmonic monitoring equipment needs to be processed, usually by converting the time domain data into frequency domain data through spectrum analysis methods such as fast Fourier transform (FFT).

[0081] Spectrum analysis: Performing spectrum analysis on the data after FFT processing can obtain the spectrum diagram of voltage and current. The spectrum diagram shows the various frequency components contained in the voltage and current, including harmonic components.

[0082] Determine harmonic frequency: Determine the frequency range of harmonics based on the spectrum. Harmonics are usually integer multiples of the fundamental frequency (the standard frequency of the power grid). For example, in a 50Hz power grid, the frequency of the second harmonic is 100Hz, the frequency of the third harmonic is 150Hz, and so on.

[0083] Harmonic content assessment: For a certain harmonic frequency range, the level of harmonic content is assessed. Indicators such as total harmonic current distortion (THDi) and total harmonic voltage distortion (THDv) can be calculated to assess the impact of harmonics on the power grid.

[0084] Set filter cutoff frequency: Set the filter cutoff frequency according to the harmonic frequency range and actual situation. The filter cutoff frequency should be reasonably selected to filter out the harmonic components while avoiding filtering out the normal fundamental frequency.

[0085] Step S103, setting target control parameters of the filter based on the harmonic information, and performing filtering.

[0086] In this embodiment, adjusting the filter parameters is a common method for harmonic control of photovoltaic power station inverters. The filter is used to filter out the harmonic components in the inverter output, making the output waveform closer to the ideal sine wave. Adjusting the filter parameters involves the following main parameters and will have different effects on harmonics:

[0087] Cutoff frequency: The filter's cutoff frequency determines the frequency range of harmonics it can filter out. A lower cutoff frequency can filter out low-frequency harmonics, while a higher cutoff frequency can filter out high-frequency harmonics. Adjusting the cutoff frequency affects the effect and filtering ability of the harmonic filter.

[0088] Types of harmonic filters: There are different types of harmonic filters, including harmonic neutralization inverter (HNI), harmonic filter, etc. Different types of filters have different performance and application range in filtering harmonics.

[0089] Harmonic filter order: The order of the filter indicates the complexity of its filtering effect. A higher order filter can filter out more harmonic components, but it will also increase the complexity and cost of the filter.

[0090] Impedance: The impedance of the harmonic filter affects the filtering effect. The impedance of the filter needs to match the characteristics of the inverter output and the grid to obtain the best filtering effect.

[0091] Adjustments to filter parameters that affect harmonics may include the following:

[0092] Filtering effect: Adjusting the filter parameters can enhance or weaken the filter's ability to filter harmonics. Appropriate adjustment can achieve the expected effect of harmonic control.

[0093] Inverter efficiency: Higher order harmonic filters may result in lower inverter efficiency because the filter absorbs some of the power.

[0094] System stability: The filtering characteristics of the filter may affect the dynamic response between the inverter and the grid, and the stability and reliability of the system need to be ensured.

[0095] Cost: High-order or complex types of harmonic filters are usually more expensive. It is necessary to consider the filter cost and performance comprehensively while meeting the harmonic control requirements.

[0096] Step S104, at the same time, define the filtering effect and set the adjustment period of the monitoring filtering process.

[0097] In this embodiment, the objectives of harmonic control of the photovoltaic power station inverter include:

[0098] Reduce harmonics: Through appropriate control strategies and filter design, the harmonic content in the inverter output can be reduced so that the harmonic components of current and voltage are reduced to a lower level.

[0099] Reduce grid distortion: Reducing harmonics in the inverter output can reduce the distortion of the grid voltage waveform and ensure the stability and reliability of the grid.

[0100] Compliance with grid standards: The harmonic content of the inverter output needs to comply with grid standards and specifications. These standards usually specify limits on the harmonic content in the inverter output to protect the normal operation of the grid and other user equipment.

[0101] Improve power quality: Control the inverter output waveform to be close to the ideal sine wave, which can improve the quality of power, reduce the power factor, and reduce the power loss caused by harmonics.

[0102] Protect other equipment: Reducing harmonics can reduce the impact of harmonics on other equipment, such as reducing the risk of harmonics damaging transformers, capacitors, inductors and other equipment.

[0103] The filtering effect of the filter is comprehensively defined from the above aspects.

[0104] In this embodiment, the adjustment period of the monitoring filtering process is set, and the adjustment period of the monitoring filtering process involves the balance between the filter performance and the system response. The adjustment period refers to the response time of the control system to the input change, and can also be understood as the time interval of sampling in the control system. In the filtering control, a suitable adjustment period can ensure that the filter effectively filters out harmonics in a real-time environment, while minimizing unnecessary delays and computational complexity.

[0105] In some embodiments of the present application, the method further includes correcting the harmonic frequency obtained in the harmonic model of the power grid and the inverter output, including:

[0106] Define the fluctuation level of the power grid frequency;

[0107] Determine the first influencing factor according to the design of the inverter and the control strategy;

[0108] Determine the second influencing factor according to the load type and capacity output by the inverter;

[0109] The harmonic frequency is corrected based on the fluctuation level, the first impact factor and the second impact factor.

[0110] In this embodiment, the fluctuation level, the first influencing factor and the second influencing factor together correspond to a correction coefficient, harmonic frequency*correction coefficient, which is the correction process. In the process of determining the harmonic frequency range, there are some influencing factors that may cause errors. These factors include:

[0111] Grid frequency: Grid frequency is the basis of harmonic frequency. In a 50Hz grid, the harmonic frequency is usually an integer multiple of the fundamental frequency (50Hz). If the grid frequency fluctuates or is unstable, it may cause a certain error in the calculation of the harmonic frequency.

[0112] Inverter design: Inverters of different types and brands may have different harmonic characteristics. The output waveform of the inverter may be affected by its design and control strategy, which may cause the actual harmonic frequency to differ from the theoretical frequency.

[0113] Inverter load: The inverter output load type and capacity may also have an impact on the harmonic frequency. Different types of loads (such as linear loads and non-linear loads) may introduce different harmonic components.

[0114] Step S105: adjusting the target control parameters of the next adjustment cycle according to the filtering effect of the previous adjustment cycle.

[0115] In some embodiments of the present application, setting target control parameters of the filter based on harmonic information includes:

[0116] Harmonic information includes harmonic frequency and content, and target control parameters include filter cutoff frequency, filter order and impedance;

[0117] Determine the filter cutoff frequency according to the range of harmonic frequencies;

[0118] Determine the filter order based on the content and harmonic components;

[0119] The impedance is determined based on the inverter output impedance and the grid impedance.

[0120] In some embodiments of the present application, adjusting the target control parameter of the next adjustment cycle according to the filtering effect of the previous adjustment cycle includes:

[0121] If the filtering effect of the previous adjustment cycle is lower than the filtering effect threshold corresponding to this cycle, a correction coefficient is determined according to the difference between the filtering effect of the previous adjustment cycle and the filtering effect threshold to adjust the target control parameter of the next adjustment cycle;

[0122] Otherwise, the target control parameter of the next regulation cycle is not adjusted.

[0123] In this embodiment, this adjustment is the same as the above correction.

[0124] By applying the above technical solutions, harmonic analysis is performed on the output of the power grid and inverter, and a harmonic model of the power grid and inverter output is established; harmonic information is determined based on the harmonic model; the target control parameters of the filter are set based on the harmonic information, and filtering is performed; at the same time, the filtering effect is defined, and the adjustment cycle for monitoring the filtering process is set; the target control parameters of the next adjustment cycle are adjusted according to the filtering effect of the previous adjustment cycle. The accuracy and adaptability of harmonic control are improved

[0125] Through the description of the above implementation methods, those skilled in the art can clearly understand that the present invention can be implemented by hardware, or by means of software plus a necessary general hardware platform. Based on such an understanding, the technical solution of the present invention can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a USB flash drive, a mobile hard disk, etc.), including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each implementation scenario of the present invention.

[0126] Correspondingly, the present application also provides a photovoltaic power station inverter harmonic control device, the device comprising:

[0127] The first module 201 is used to perform harmonic analysis on the output of the power grid and the inverter, and establish a harmonic model of the output of the power grid and the inverter;

[0128] The second module 202 is used to determine harmonic information according to the harmonic model;

[0129] The third module 203 is used to set the target control parameters of the filter based on the harmonic information and perform filtering;

[0130] The fourth module 204 is used to define the filtering effect and set the adjustment period of the monitoring filtering process at the same time;

[0131] The fifth module 205 is used to adjust the target control parameters of the next regulation cycle according to the filtering effect of the previous regulation cycle.

[0132] In some embodiments of the present application, the first module 201 is used to:

[0133] Collect voltage and current waveform data output by the power grid and inverter;

[0134] Perform data filtering, noise removal and spurious processing on voltage and current waveform data;

[0135] Perform fast Fourier transform on the voltage and current waveform data to convert the time domain data into frequency domain data;

[0136] Perform spectrum analysis on the frequency domain data to obtain the spectrum diagram of voltage and current, so as to establish the harmonic model of the power grid and inverter output.

[0137] In some embodiments of the present application, the apparatus further includes a sixth module 206, configured to:

[0138] Define the fluctuation level of the power grid frequency;

[0139] Determine the first influencing factor according to the design of the inverter and the control strategy;

[0140] Determine the second influencing factor according to the load type and capacity output by the inverter;

[0141] The harmonic frequency is corrected based on the fluctuation level, the first impact factor and the second impact factor.

[0142] In some embodiments of the present application, the third module 203 is used to:

[0143] Harmonic information includes harmonic frequency and content, and target control parameters include filter cutoff frequency, filter order and impedance;

[0144] Determine the filter cutoff frequency according to the range of harmonic frequencies;

[0145] Determine the filter order based on the content and harmonic components;

[0146] The impedance is determined based on the inverter output impedance and the grid impedance.

[0147] In some embodiments of the present application, the fifth module 205 is used to:

[0148] If the filtering effect of the previous adjustment cycle is lower than the filtering effect threshold corresponding to this cycle, a correction coefficient is determined according to the difference between the filtering effect of the previous adjustment cycle and the filtering effect threshold to adjust the target control parameter of the next adjustment cycle;

[0149] Otherwise, the target control parameter of the next regulation cycle is not adjusted.

[0150] Those skilled in the art will appreciate that the modules in the device in the implementation scenario can be distributed in the device in the implementation scenario according to the implementation scenario description, or can be changed accordingly and located in one or more devices different from the implementation scenario. The modules in the above implementation scenario can be combined into one module, or can be further split into multiple sub-modules.

[0151] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for controlling harmonics of a photovoltaic power station inverter, characterized in that: The method comprises: Conduct harmonic analysis on the output of the power grid and inverter, and establish harmonic models of the power grid and inverter output; determining harmonic information according to a harmonic model; The target control parameters of the filter are set based on the harmonic information, and filtering is performed; At the same time, define the filtering effect and set the adjustment cycle for monitoring the filtering process; The target control parameters of the next regulation cycle are adjusted according to the filtering effect of the previous regulation cycle.

2. The photovoltaic power station inverter harmonic control method according to claim 1, characterized in that: And establish the harmonic model of the power grid and inverter output, including: Collect voltage and current waveform data output by the power grid and inverter; Perform data filtering, noise removal and spurious processing on voltage and current waveform data; Perform fast Fourier transform on the voltage and current waveform data to convert the time domain data into frequency domain data; Perform spectrum analysis on the frequency domain data to obtain the spectrum diagram of voltage and current, so as to establish the harmonic model of the power grid and inverter output.

3. The photovoltaic power station inverter harmonic control method according to claim 2, characterized in that: The method further includes correcting the harmonic frequency obtained in the harmonic model of the power grid and the inverter output, including: Define the fluctuation level of the power grid frequency; Determine the first influencing factor according to the design of the inverter and the control strategy; Determine the second influencing factor according to the load type and capacity output by the inverter; The harmonic frequency is corrected based on the fluctuation level, the first impact factor and the second impact factor.

4. The photovoltaic power station inverter harmonic control method according to claim 1, characterized in that: The target control parameters of the filter are set based on the harmonic information, including: Harmonic information includes harmonic frequency and content, and target control parameters include filter cutoff frequency, filter order and impedance; Determine the filter cutoff frequency according to the range of harmonic frequencies; Determine the filter order based on the content and harmonic components; The impedance is determined based on the inverter output impedance and the grid impedance.

5. The photovoltaic power station inverter harmonic control method according to claim 1, characterized in that: The target control parameters of the next regulation cycle are adjusted according to the filtering effect of the previous regulation cycle, including: If the filtering effect of the previous adjustment cycle is lower than the filtering effect threshold corresponding to this cycle, a correction coefficient is determined according to the difference between the filtering effect of the previous adjustment cycle and the filtering effect threshold to adjust the target control parameter of the next adjustment cycle; Otherwise, the target control parameter of the next regulation cycle is not adjusted.

6. A photovoltaic power station inverter harmonic control device, characterized in that: The device comprises: The first module is used to perform harmonic analysis on the output of the power grid and the inverter, and establish a harmonic model of the output of the power grid and the inverter; The second module is used to determine harmonic information according to the harmonic model; The third module is used to set the target control parameters of the filter based on the harmonic information and perform filtering; The fourth module is used to simultaneously define the filtering effect and set the adjustment period for monitoring the filtering process; The fifth module is used to adjust the target control parameters of the next regulation cycle according to the filtering effect of the previous regulation cycle.

7. The photovoltaic power station inverter harmonic control device according to claim 6, characterized in that: The first module is used to: Collect voltage and current waveform data output by the power grid and inverter; Perform data filtering, noise removal and spurious processing on voltage and current waveform data; Perform fast Fourier transform on the voltage and current waveform data to convert the time domain data into frequency domain data; Perform spectrum analysis on the frequency domain data to obtain the spectrum diagram of voltage and current, so as to establish the harmonic model of the power grid and inverter output.

8. The photovoltaic power station inverter harmonic control device according to claim 7, characterized in that: The device also includes a sixth module, configured to: Define the fluctuation level of the power grid frequency; Determine the first influencing factor according to the design of the inverter and the control strategy; Determine the second influencing factor according to the load type and capacity output by the inverter; The harmonic frequency is corrected based on the fluctuation level, the first impact factor and the second impact factor.

9. The photovoltaic power station inverter harmonic control device according to claim 6, characterized in that: The third module is used to: Harmonic information includes harmonic frequency and content, and target control parameters include filter cutoff frequency, filter order and impedance; Determine the filter cutoff frequency according to the range of harmonic frequencies; Determine the filter order based on the content and harmonic components; The impedance is determined based on the inverter output impedance and the grid impedance.

10. The photovoltaic power station inverter harmonic control device according to claim 6, characterized in that: The fifth module is used to: If the filtering effect of the previous adjustment cycle is lower than the filtering effect threshold corresponding to this cycle, a correction coefficient is determined according to the difference between the filtering effect of the previous adjustment cycle and the filtering effect threshold to adjust the target control parameter of the next adjustment cycle; Otherwise, the target control parameter of the next regulation cycle is not adjusted.

Images