Micro inverter output power control method and system

Abstract

The invention relates to the technical field of inverter output power control, in particular to a micro inverter output power control method and system, and the method comprises the following steps: obtaining a grid-connected point AC voltage signal; based on a grid-connected point AC voltage signal, first phase-locked loop processing is performed in parallel, first phase information is extracted, and the first phase information comprises a voltage phase influenced by an interference component whose frequency is higher than a fundamental wave frequency; second phase-locked loop processing is carried out, second phase information is extracted, and the second phase information comprises the fundamental wave phase after the interference component is filtered out; calculating a phase disturbance quantity according to the first phase information and the second phase information; generating a correction phase according to the second phase information and the phase disturbance quantity; generating a corrected current command based on the corrected phase; and controlling the micro inverter to output alternating current according to the current correction instruction. The electric energy quality can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of inverter output power control, and in particular to a micro inverter output power control method and system. Background Art

[0002] In distributed photovoltaic power generation systems, microinverters, as key grid-connected units, are responsible for efficiently converting the DC power generated by photovoltaic modules into AC power that meets grid requirements.

[0003] Traditional microinverters typically use phase-locked loop (PLL) technology to accurately acquire grid voltage phase information to achieve grid synchronization. However, existing PLL designs often focus on robustness against common low-order harmonics (such as third and fifth harmonics) in the grid, while failing to fully consider the impact of voltage disturbances. Summary of the Invention

[0004] The purpose of the present invention is to address the above-mentioned shortcomings and provide a method and system for controlling the output power of a micro-inverter.

[0005] The present invention adopts the following technical solutions:

[0006] A method for controlling output power of a micro-inverter, the method comprising the following steps:

[0007] Obtaining AC voltage signal of grid connection point;

[0008] Based on the AC voltage signal at the grid connection point, the following are performed in parallel: a first phase-locked loop process is performed to extract first phase information, where the first phase information includes the voltage phase affected by interference components with a frequency higher than the fundamental frequency; and a second phase-locked loop process is performed to extract second phase information, where the second phase information includes the fundamental phase after filtering out the interference components.

[0009] Calculating a phase disturbance amount according to the first phase information and the second phase information;

[0010] generating a correction phase according to the second phase information and the phase disturbance amount;

[0011] generating a corrected current command based on the corrected phase;

[0012] According to the corrected current instruction, the micro inverter is controlled to output AC current.

[0013] Through the above scheme, phase oscillation caused by high-frequency interference can be effectively identified and compensated, thereby suppressing the sideband harmonics in the output current of the micro-inverter and improving the power quality.

[0014] Optionally, the present application further proposes that the step of calculating the phase disturbance amount includes:

[0015] Acquire a phase difference between the first phase information and the second phase information;

[0016] performing a spectrum analysis on the phase difference between the first phase information and the second phase information to identify a plurality of disturbance frequency components contained in the phase difference between the first phase information and the second phase information;

[0017] determining, based on the plurality of disturbance frequency components, a plurality of original disturbance frequencies causing a phase difference between the first phase information and the second phase information;

[0018] generating a composite phase correction instruction according to a plurality of original disturbance frequencies;

[0019] The composite phase correction instruction is used as the phase disturbance amount.

[0020] Through the above scheme, the calculation method of the phase disturbance amount is defined in detail, and the disturbance frequency component is accurately identified through spectrum analysis, providing a basis for subsequent accurate compensation.

[0021] Optionally, the present application further proposes that the step of performing spectrum analysis on the phase difference between the first phase information and the second phase information to identify multiple disturbance frequency components contained in the phase difference between the first phase information and the second phase information includes:

[0022] performing continuous short-time spectrum analysis on a phase difference between the first phase information and the second phase information;

[0023] According to the continuous short-time spectrum analysis results, the instantaneous disturbance frequency in the phase difference between the first phase information and the second phase information is extracted, and the instantaneous disturbance frequency is used as a plurality of disturbance frequency components.

[0024] Through the above scheme, the continuous short-time spectrum analysis is introduced to capture the instantaneous disturbance frequency in the phase difference in real time and dynamically, thereby improving the real-time performance and accuracy of disturbance identification.

[0025] Optionally, the present application further proposes that the step of performing continuous short-time spectrum analysis includes:

[0026] monitoring a spectral characteristic of a signal of a phase difference between the first phase information and the second phase information;

[0027] Adjusting the window length and / or window overlap ratio of continuous short-time spectrum analysis according to spectrum characteristics;

[0028] Continuous short-time spectrum analysis is performed on the phase difference between the first phase information and the second phase information according to the adjusted window length and / or window overlap ratio.

[0029] Through the above scheme, the recognition accuracy and robustness of the instantaneous disturbance frequency are further optimized by adaptively adjusting the spectrum analysis parameters, and adapting to the complex and changing power grid environment.

[0030] Optionally, the present application further proposes that, based on the continuous short-time spectrum analysis results, the instantaneous disturbance frequency in the phase difference between the first phase information and the second phase information is extracted, and the step of using the instantaneous disturbance frequency as multiple disturbance frequency components includes:

[0031] identifying, based on the continuous short-time spectrum analysis results, an energy peak in the spectrum of the phase difference between the first phase information and the second phase information;

[0032] analyzing spectral characteristics of the energy peak, where the spectral characteristics of the energy peak include peak width and / or peak shape;

[0033] According to the spectrum characteristics of the energy peak, determine whether the spectrum characteristics of the energy peak are formed by the superposition of multiple close instantaneous disturbance frequencies;

[0034] If it is determined that the disturbance is formed by the superposition of multiple adjacent instantaneous disturbance frequencies, the multiple adjacent instantaneous disturbance frequencies are separated;

[0035] The multiple separated instantaneous disturbance frequencies and the instantaneous disturbance frequencies corresponding to the energy peaks that are not determined to be formed by superposition are used as the multiple disturbance frequency components included in the phase difference between the first phase information and the second phase information.

[0036] Through the above scheme, a method for identifying and separating superimposed disturbance frequencies is provided, ensuring that each independent disturbance source can be accurately identified even when multiple close frequencies exist simultaneously.

[0037] Optionally, the present application further proposes that the step of separating a plurality of close instantaneous disturbance frequencies includes:

[0038] Performing curve fitting on the energy peaks;

[0039] Based on the fitting results, the energy peak is decomposed into multiple independent sub-peaks;

[0040] The center frequency corresponding to each sub-peak is extracted as multiple close instantaneous disturbance frequencies.

[0041] Through the above scheme, the curve fitting technology is used to achieve accurate decomposition of the superimposed energy peak, further improving the precision of disturbance frequency identification.

[0042] Optionally, the present application further proposes that the step of generating a composite phase correction instruction according to multiple original disturbance frequencies includes:

[0043] generating corresponding phase correction components according to a plurality of original disturbance frequencies;

[0044] The phase correction components are superimposed to generate a composite phase correction instruction.

[0045] Through the above scheme, the generation method of the composite phase correction instruction is clarified, and by superimposing multiple correction components, comprehensive compensation for multiple disturbance frequencies is achieved.

[0046] Optionally, the present application further proposes that the step of generating a corresponding phase correction component includes:

[0047] For multiple original disturbance frequencies, tracking in real time the instantaneous amplitude and instantaneous phase of the component corresponding to the original disturbance frequency in the phase difference between the first phase information and the second phase information;

[0048] According to the instantaneous amplitude and the instantaneous phase, a compensation signal having the same frequency, the same instantaneous amplitude and the opposite phase as the component corresponding to the original disturbance frequency is generated as a phase correction component.

[0049] Through the above scheme, a method for generating an accurate phase correction component is provided, and the accuracy and effectiveness of the compensation signal are ensured by tracking the amplitude and phase of the disturbance component in real time.

[0050] Optionally, the present application further proposes that the step of real-time tracking the instantaneous amplitude and instantaneous phase of the component corresponding to the original disturbance frequency in the phase difference between the first phase information and the second phase information includes:

[0051] For multiple original disturbance frequencies, independent phase-locked loops are constructed respectively;

[0052] The instantaneous amplitude and instantaneous phase of the component corresponding to the original disturbance frequency in the phase difference between the first phase information and the second phase information are tracked in real time through a phase-locked loop.

[0053] Through the above scheme, an independent phase-locked loop is used to track each disturbance frequency, thereby improving the parallelism and accuracy of multi-frequency disturbance tracking.

[0054] Optionally, the present application further proposes a micro-inverter output power control system, which is applied to the above-mentioned micro-inverter output power control method, and the system includes:

[0055] An acquisition module, used to obtain the AC voltage signal of the grid connection point;

[0056] A first phase-locked loop module extracts first phase information based on the grid-connected point AC voltage signal, where the first phase information includes a voltage phase affected by an interference component having a frequency higher than a fundamental frequency;

[0057] A second phase-locked loop module extracts second phase information based on the grid-connected point AC voltage signal, where the second phase information includes the fundamental wave phase after filtering out interference components;

[0058] A calculation module, configured to calculate a phase disturbance amount based on the first phase information and the second phase information;

[0059] A correction module, configured to generate a correction phase according to the second phase information and the phase disturbance amount;

[0060] A correction instruction generating module, used for generating a correction current instruction based on the correction phase;

[0061] The current control module is used to control the micro inverter to output AC current according to the corrected current instruction.

[0062] The above solution, through modular design, enables the method to be actually deployed and applied, and has good feasibility.

[0063] From the above, it can be seen that the present application provides a micro-inverter output power control method and system, which processes the AC voltage signal of the grid-connected point in parallel, extracts the first phase information containing interference and the second phase information with interference filtered out, and calculates the phase disturbance amount based on the two, and then generates a correction phase and a correction current instruction to control the output AC current of the micro-inverter. It can effectively suppress the interference of the high-frequency voltage disturbance of the power grid on the phase-locked loop of the micro-inverter, avoid the output current sideband harmonics generated thereby, thereby improving the grid-connected power quality, and is particularly suitable for the advantages of parallel operation of multiple micro-inverters.

[0064] To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only for reference and illustration and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 This is a flow chart of a method for controlling output power of a micro-inverter according to the present invention;

[0066] Figure 2 The figure is a structural diagram of a micro-inverter output power control system of the present invention. DETAILED DESCRIPTION

[0067] The following is an explanation of the embodiments of the present invention through specific embodiments. Those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed based on different viewpoints and applications without departing from the spirit of the present invention. In addition, the drawings of the present invention are only for simple schematic illustrations and are not depicted according to actual dimensions. It is stated in advance. The following embodiments will further explain the relevant technical contents of the present invention in detail, but the disclosed contents are not intended to limit the scope of protection of the present invention.

[0068] This embodiment provides a micro-inverter output power control method and system, combined with Figure 1 and Figure 2 shown.

[0069] refer to Figure 1 A method for controlling the output power of a micro-inverter comprises the following steps: obtaining an AC voltage signal at a grid-connected point; based on the AC voltage signal at the grid-connected point, executing in parallel: a first phase-locked loop processing to extract first phase information, the first phase information including a voltage phase affected by an interference component having a frequency higher than a fundamental frequency; a second phase-locked loop processing to extract second phase information, the second phase information including a fundamental phase after filtering out the interference component; calculating a phase disturbance amount based on the first phase information and the second phase information; generating a correction phase based on the second phase information and the phase disturbance amount; generating a correction current instruction based on the correction phase; and controlling the micro-inverter to output AC current based on the correction current instruction.

[0070] This application aims to solve the problem of high-frequency voltage noise in the local power grid in a distributed grid-connected system composed of a large number of micro-inverters, which causes interference to the internal phase-locked loop of the micro-inverter, and then generates specific sideband harmonic currents through the phase modulation mechanism, thereby improving the grid-connected power quality of the distributed photovoltaic system.

[0071] To achieve the above-mentioned objectives, the present application proposes a method for controlling the output power of a micro-inverter. The method first obtains the grid-connected AC voltage signal and, based on the signal, performs a first phase-locked loop process and a second phase-locked loop process in parallel. The first phase-locked loop process refers to a process for extracting phase information from the grid-connected AC voltage signal, which is characterized in that its design or configuration enables it to capture the voltage phase affected by interference components with a frequency higher than the fundamental frequency, i.e., the first phase information. The process can be implemented using a broadband phase-locked loop or a phase-locked loop with a weak low-pass filtering characteristic, and its purpose is to obtain the original phase information of the grid voltage, including the high-frequency disturbance components superimposed therein, to provide raw data for subsequent interference analysis. At the same time, the second phase-locked loop process refers to another process for extracting phase information from the grid-connected AC voltage signal, which is characterized in that its design or configuration enables it to effectively filter out interference components with a frequency higher than the fundamental frequency, thereby extracting a pure fundamental phase, i.e., the second phase information. This processing can be implemented using a narrowband phase-locked loop, a phase-locked loop with strong low-pass filtering characteristics, or a phase-locked loop with an integrated notch filter. Its purpose is to provide an accurate grid fundamental phase reference that is not affected by high-frequency interference as a benchmark for current control.

[0072] After obtaining the first and second phase information, the method calculates a phase disturbance based on them. The phase disturbance refers to the phase deviation or difference between the first and second phase information. This quantifies the instantaneous impact of high-frequency interference components on the grid voltage phase. The phase disturbance can be obtained by directly calculating the phase difference between the first and second phase information. Its purpose is to accurately identify and quantify the phase distortion caused by high-frequency interference, providing a basis for subsequent phase correction. Subsequently, a correction phase is generated based on the second phase information and the phase disturbance. The correction phase refers to the phase information obtained by correcting the second phase information by combining it with the phase disturbance. This phase information not only reflects the accurate phase of the grid fundamental wave but also eliminates the impact of high-frequency interference components on the phase. The correction phase can be generated by performing appropriate addition and subtraction operations on the second phase information and the phase disturbance. Its purpose is to provide a pure, accurate, and high-frequency interference-free phase reference for generating the output current command of the microinverter. Finally, a corrected current command is generated based on the corrected phase, and the microinverter output AC current is controlled based on this corrected current command. The corrected current command is a command signal generated based on the corrected phase and used to control the AC current output by the microinverter. The phase of this command signal is consistent with the corrected phase, ensuring that the AC current output by the microinverter is accurately synchronized with the grid fundamental voltage and that harmonic components in its waveform caused by high-frequency interference are effectively suppressed. The corrected current command can be generated by inputting the corrected phase into the current controller. Its purpose is to guide the microinverter to output high-quality AC current and avoid the injection of undesirable harmonics.

[0073] The solution of this application obtains the grid-connection point AC voltage signal as input and initiates a parallel processing process. Specifically, the grid-connection point AC voltage signal is simultaneously fed into two independent phase-locked loops (PLLs) for processing. First, the first PLL is designed to capture the voltage phase affected by interference components with frequencies higher than the fundamental frequency, thereby extracting the first phase information. This means that the bandwidth or filtering characteristics of the first PLL allow high-frequency disturbances to pass through, allowing its output phase signal to reflect the true instantaneous phase of the grid voltage, including its high-frequency oscillations. Simultaneously, the second PLL is designed to effectively filter out these interference components, focusing on extracting the pure fundamental phase, thereby obtaining the second phase information. The second PLL's internal filtering mechanism ensures that its output phase signal is a smooth and accurate fundamental phase reference. The parallel operation of these two PLLs, with their different filtering characteristics, makes the subsequent calculation of the phase disturbance possible. By comparing the first and second phase information, the system can accurately calculate the phase disturbance, which directly reflects the instantaneous impact of high-frequency interference on the internal phase synchronization of the microinverter. Once the phase disturbance is determined, it is used to correct the second phase information, generating a corrected phase. This corrected phase is a compensated, more accurate phase reference that incorporates synchronization information with the grid fundamental while effectively eliminating phase deviations caused by high-frequency interference. The microinverter then uses this corrected phase to generate a corrected current command. This means the microinverter's current controller no longer relies on the original, affected phase information, but instead generates its output current reference waveform based on the precisely corrected phase. Ultimately, the microinverter controls its output AC current based on this corrected current command. This enables the microinverter to output a pure AC current precisely synchronized with the grid fundamental voltage, effectively suppressing the internal phase modulation caused by high-frequency voltage disturbances and preventing the resulting sideband harmonic currents from being injected into the grid. This entire process forms a closed-loop control mechanism, ensuring stable and high-quality grid-connected operation of the microinverter in complex grid environments.

[0074] In some preferred embodiments, the present application is implemented as follows. First, the AC voltage signal at the grid connection point can be collected in real time by a voltage sensor and converted to a digital signal via an analog-to-digital converter for processing by a digital signal processor (DSP) or microcontroller (MCU). The first phase-locked loop (PLL) processing can utilize a broadband synchronous reference frame phase-locked loop (SRF-PLL) with a relatively high low-pass filter cutoff frequency to ensure that phase oscillations caused by high-frequency voltage disturbances can be accurately tracked and reflected in the first phase information. For example, the bandwidth can be set to sufficiently cover the grid fundamental frequency and its surrounding high-frequency disturbance frequencies. Meanwhile, the second phase-locked loop processing can utilize another synchronous reference frame phase-locked loop (SRF-PLL), but with a lower internal low-pass filter cutoff frequency or an integrated notch filter for known high-frequency disturbance frequencies. This effectively filters out high-frequency interference and extracts only the pure grid fundamental phase as the second phase information. Subsequently, the step of calculating the phase disturbance can be achieved by directly subtracting the first phase information from the second phase information in real time, generating a signal reflecting the instantaneous phase deviation. For example, if the first phase information is theta_1(t) and the second phase information is theta_2(t), the phase disturbance can be simply expressed as Deltatheta(t) = theta_1(t) - theta_2(t). Next, the correction phase generation step applies this phase disturbance to the second phase information. Specifically, the correction phase can be expressed as theta_{corr}(t) = theta_2(t) - Deltatheta(t), or appropriate addition and subtraction operations can be performed based on the definition of the disturbance and the compensation direction to offset the impact of the disturbance. Based on this correction phase, a proportional resonant (PR) controller can be used to generate a corrected current command. This controller uses the correction phase as its internal reference to generate a sinusoidal current command that is in phase with the grid voltage. Finally, the pulse width modulation (PWM) module within the microinverter drives the inverter's power switches based on this corrected current command, thereby controlling the microinverter to output a pure AC current that is synchronized with the grid. The entire control algorithm can be integrated into the digital controller inside the microinverter to achieve real-time and efficient power output control.

[0075] The present application further proposes that the steps of calculating the phase disturbance amount include:

[0076] Acquire a phase difference between the first phase information and the second phase information;

[0077] performing a spectrum analysis on the phase difference between the first phase information and the second phase information to identify a plurality of disturbance frequency components contained in the phase difference between the first phase information and the second phase information;

[0078] determining, based on the plurality of disturbance frequency components, a plurality of original disturbance frequencies causing a phase difference between the first phase information and the second phase information;

[0079] generating a composite phase correction instruction according to a plurality of original disturbance frequencies;

[0080] The composite phase correction instruction is used as the phase disturbance amount.

[0081] Among them, spectrum analysis refers to the process of converting time domain signals into frequency domain signals to reveal the various frequency components contained in the signal and their corresponding amplitude and phase information. It can be achieved by using a variety of mathematical methods such as fast Fourier transform, discrete Fourier transform, wavelet transform or short-time Fourier transform. Its purpose is to decompose the complex phase difference signal into a single identifiable frequency component, so as to identify the disturbance frequency component in the signal; the original disturbance frequency refers to the frequency that actually causes the phase information difference, which is further screened and determined from the multiple disturbance frequency components identified after spectrum analysis of the phase difference. component, which can be obtained by performing noise filtering, threshold judgment or pattern recognition on the spectrum analysis results. Its purpose is to extract the disturbance source frequency that really needs to be compensated and has physical significance from the complex spectrum information; the composite phase correction instruction refers to a comprehensive correction signal formed by superimposing the corresponding phase correction components based on multiple original disturbance frequencies. It can be constructed by tracking the amplitude and phase of each original disturbance frequency component, generating a corresponding reverse compensation signal, and then linearly superimposing it. Its purpose is to provide an accurate phase correction amount that can simultaneously offset the influence of multiple frequency disturbances.

[0082] The solution of the present application obtains the phase difference between the first phase information and the second phase information. The phase difference directly reflects the impact of the interference component with a frequency higher than the fundamental frequency in the power grid on the voltage phase, thereby providing basic data for subsequent disturbance analysis. On this basis, the phase difference is subjected to spectral analysis, which can decompose it into multiple independent disturbance frequency components, so that various disturbances hidden in complex signals can be revealed. Furthermore, based on these identified disturbance frequency components, multiple original disturbance frequencies that cause the phase difference are determined. This process aims to accurately lock the actual interference source that causes the phase deviation and avoid processing irrelevant noise. Subsequently, based on these original disturbance frequencies, a composite phase correction instruction is generated. The instruction is a comprehensive compensation signal for multiple disturbance frequencies, which can simultaneously and accurately offset phase disturbances of different frequencies. Finally, the composite phase correction instruction is used as the phase disturbance amount for subsequent correction phase generation.

[0083] Through this refined phase disturbance calculation mechanism, this solution overcomes the potential accuracy issues associated with direct calculation of phase disturbances. In the microinverter output power control method, the phase information extracted by the first phase-locked loop (PLL) includes the voltage phase affected by interference components, while the phase information extracted by the second phase-locked loop (PLL) is the fundamental phase after filtering out interference components. When the phase difference between the two is calculated, this difference accurately represents the phase disturbance caused by high-frequency noise in the power grid. This solution performs in-depth spectral analysis and identifies the original disturbance frequencies of this phase difference, accurately capturing these tiny but cumulative phase oscillations. These precisely identified disturbance frequencies are used to generate composite phase correction commands and used as phase disturbance variables, enabling the subsequent correction phase to more accurately modify the current command. This enables the microinverter to output purer AC current and effectively suppresses specific sideband harmonic currents generated by high-frequency noise interference in the internal PLL. This improves the accuracy and stability of the microinverter's output power control, particularly when multiple microinverters are operated in parallel, reducing the harmonic superposition caused by the "group effect."

[0084] In some preferred embodiments, the present application is specifically implemented as follows: First, in a digital signal processor, the first phase information and the second phase information obtained in real time are subtracted point by point to obtain a continuous phase difference signal. For example, if the first phase information is theta_1(t) and the second phase information is theta_2(t), the phase difference signal is Deltatheta(t) = theta_1(t) - theta_2(t). Subsequently, a periodic spectrum analysis is performed on the phase difference signal Deltatheta(t). For example, a fast Fourier transform algorithm can be used to process the collected phase difference data in each fixed time window to obtain a spectrum diagram of the phase difference signal in the time window. By analyzing the energy peaks in the spectrum diagram, multiple disturbance frequency components can be identified. These peaks represent periodic disturbances of different frequencies present in the phase difference signal.

[0085] Furthermore, based on the multiple disturbance frequency components identified, an energy threshold or frequency range can be set to screen out those components with significant energy and frequencies within a specific range, and determine them as the multiple original disturbance frequencies that cause the phase difference. For example, if it is known that there may be noise around 2kHz in the power grid, the focus can be on the spectrum peak near 2kHz. Once these original disturbance frequencies are determined, the instantaneous amplitude and instantaneous phase of each original disturbance frequency in the phase difference signal can be tracked in real time. This can be achieved by constructing multiple independent digital notch filters or adaptive filters, each of which is designed for an original disturbance frequency.

[0086] Based on the instantaneous amplitude and instantaneous phase of each original disturbance frequency, a compensation signal with the same frequency, instantaneous amplitude, but opposite phase is generated as the corresponding phase correction component. For example, if an original disturbance frequency component is A sin(omega t + phi), the corresponding phase correction component is -A sin(omega t + phi). Finally, all generated phase correction components are linearly superimposed to form a composite phase correction instruction. This composite phase correction instruction contains precise compensation information for all identified original disturbance frequencies and is directly input into the subsequent correction phase generation module as a phase disturbance variable to achieve precise correction of the current instruction.

[0087] The present application further proposes that the steps of performing spectrum analysis on the phase difference between the first phase information and the second phase information to identify multiple disturbance frequency components contained in the phase difference between the first phase information and the second phase information include:

[0088] performing continuous short-time spectrum analysis on a phase difference between the first phase information and the second phase information;

[0089] According to the continuous short-time spectrum analysis results, the instantaneous disturbance frequency in the phase difference between the first phase information and the second phase information is extracted, and the instantaneous disturbance frequency is used as a plurality of disturbance frequency components.

[0090] Among them, continuous short-time spectrum analysis refers to a method of dividing a longer time domain signal into a series of shorter time periods or "windows" and performing spectrum analysis on the signal in each window separately. Specifically, technologies such as short-time Fourier transform (STFT) or wavelet transform can be used. Its purpose is to provide frequency change information of the signal in the time domain, so as to capture the dynamic characteristics of the signal frequency changing with time; instantaneous disturbance frequency refers to the disturbance frequency identified by spectrum analysis within a specific short time window, which reflects the frequency component of the signal at that moment. Its purpose is to more accurately describe the frequency characteristics of the phase difference signal in a short time, so as to adapt to the situation where the disturbance frequency changes rapidly with time.

[0091] The solution of the present application can overcome the limitations of traditional overall spectrum analysis when processing non-steady-state signals by performing continuous short-time spectrum analysis on the phase difference between the first phase information and the second phase information. It is precisely because the phase difference signal is divided into continuous time windows and spectrum analysis is performed on each window that the system can track the dynamic evolution of the frequency components in the phase difference signal in real time, thereby capturing those instantaneous disturbance frequencies that change rapidly with time. On this basis, according to the results of continuous short-time spectrum analysis, these instantaneous disturbance frequencies are extracted and used as multiple disturbance frequency components. This processing method enables the identified disturbance frequency components to more accurately reflect the true frequency characteristics of the phase difference signal at different times. Through this improved spectrum analysis method, the system can more comprehensively and accurately identify the disturbance frequencies contained in the phase difference that may have time-varying characteristics, which provides more accurate input for the subsequent determination of the original disturbance frequency based on these disturbance frequencies and the generation of composite phase correction instructions, thereby effectively improving the accuracy and real-time performance of the entire phase disturbance calculation, thereby enabling the micro-inverter to more effectively offset the internally generated harmonics caused by the high-frequency noise of the power grid and ensure the waveform quality of the output current.

[0092] In some preferred embodiments, continuous short-time spectrum analysis is performed on the phase difference between the first and second phase information. This can be achieved using a short-time Fourier transform (STFT). For example, the phase difference signal can be acquired at a fixed sampling rate, and then a fast Fourier transform (FFT) is performed on the data within each window by sliding a fixed-length time window. This time window can be set to, for example, 256 sampling points, and a certain overlap ratio, such as 50%, can be set between windows to ensure continuity and smoothness of the spectrum analysis. In this way, a time-frequency plot can be generated that intuitively displays the temporal changes of the frequency components of the phase difference signal. Furthermore, based on the results of the continuous short-time spectrum analysis, the instantaneous disturbance frequencies in the phase difference are extracted. This can be achieved by identifying frequency peaks with significant energy in the spectrum results of each time window. For example, an energy threshold can be set, and frequency components above the threshold can be identified as instantaneous disturbance frequencies. These identified instantaneous disturbance frequencies, such as 2 kHz or 4 kHz, are used as multiple disturbance frequency components for subsequent calculation of the phase disturbance amount.

[0093] The present application further proposes that the steps of performing continuous short-time spectrum analysis include:

[0094] monitoring a spectral characteristic of a signal of a phase difference between the first phase information and the second phase information;

[0095] Adjusting the window length and / or window overlap ratio of continuous short-time spectrum analysis according to spectrum characteristics;

[0096] Continuous short-time spectrum analysis is performed on the phase difference between the first phase information and the second phase information according to the adjusted window length and / or window overlap ratio.

[0097] Monitoring the spectral characteristics of the phase difference signal between the first and second phase information refers to performing real-time or quasi-real-time spectrum analysis on the phase difference signal to obtain information such as its frequency distribution, energy concentration areas, dominant frequency components, and temporal trends of the spectrum. This analysis can be achieved using techniques such as fast Fourier transform (FFT), wavelet transform, or adaptive filtering. Its purpose is to provide a data basis for the subsequent dynamic adjustment of short-time spectrum analysis parameters. The window length refers to the duration of each time segment used to capture the signal for Fourier transform in short-time spectrum analysis. It can be set based on the signal sampling rate and the required time / frequency resolution. The purpose is to balance time resolution and frequency resolution. A longer window length provides better frequency resolution but reduces time resolution, and vice versa. The window overlap ratio refers to the ratio of overlap between two adjacent short-time spectrum analysis windows. It can be set based on analysis smoothness and computational efficiency. Its purpose is to ensure the continuity and smoothness of the spectrum analysis results and avoid information loss or discontinuity caused by window switching.

[0098] The solution of this application dynamically adjusts the parameters of short-time spectrum analysis to adapt to the ever-changing spectral characteristics of the phase difference signal. Specifically, the system first continuously monitors the spectral characteristics of the phase difference signal between the first and second phase information. This monitoring process forms the basis for dynamic adjustment, enabling the system to perceive the signal's frequency composition, energy distribution, and its temporal changes in real time. For example, when a change in the signal spectrum or the emergence of a new frequency component is detected, the system can promptly acquire this information. Based on this, the system adjusts the window length and / or window overlap ratio of the continuous short-time spectrum analysis according to the monitored spectral characteristics. For example, when the signal spectrum changes rapidly and requires improved instantaneous frequency recognition, the system can reduce the window length to increase temporal resolution. Conversely, when the signal spectrum is relatively stable and requires improved frequency resolution, the system can increase the window length to increase frequency resolution. Furthermore, adjusting the window overlap ratio helps balance analysis smoothness and computational efficiency. Finally, based on these adjusted parameters, the system performs continuous short-time spectrum analysis on the phase difference between the first and second phase information. This adaptive spectrum analysis method enables the system to analyze with parameters appropriate to the current signal state, thereby obtaining accurate spectral information. In this way, even in a complex power grid environment, when the spectral characteristics of the phase difference signal are constantly changing, the system can accurately identify the multiple disturbance frequency components contained therein, thereby providing a reliable basis for the subsequent calculation of the phase disturbance amount, the generation of the composite phase correction instruction, and the final micro-inverter output current control, suppressing the specific sideband harmonic current caused by the interference of the internal phase-locked loop, and avoiding the problems of reduced accuracy and insufficient identification effect that may be caused by fixed parameter analysis.

[0099] In some preferred embodiments, the present application is implemented as follows: A real-time spectrum analysis module can be provided within the digital signal processor (DSP) of the microinverter. This module continuously performs a fast Fourier transform (FFT) or power spectral density (PSD) estimate on the phase difference signal between the first phase information and the second phase information to monitor its spectral characteristics. For example, this module can calculate the signal's instantaneous bandwidth, the energy concentration of the dominant frequency, or the flatness of the spectrum. When a significant increase in the instantaneous bandwidth of the spectrum is detected, indicating the presence of new or rapidly changing frequency components in the signal, the control algorithm can determine the need for increased temporal resolution and dynamically reduce the window length of the short-time spectrum analysis from the default long value (e.g., 256 sampling points) to a shorter value (e.g., 128 sampling points). Furthermore, to maintain continuity and smoothness in the spectrum analysis, the window overlap ratio can be adjusted from 50% to 75%. Conversely, when the spectral characteristics show that the signal energy is concentrated in a few stable frequencies and the spectral flatness decreases, it indicates that the signal is relatively stable. In this case, the window length can be increased (for example, from 256 sampling points to 512 sampling points) to improve frequency resolution, and the window overlap ratio can be appropriately adjusted to optimize computational efficiency. Once the window length and / or window overlap ratio are adjusted, the short-time spectrum analysis module immediately uses these new parameters to process subsequent phase difference signals, ensuring high-precision spectrum analysis results under all operating conditions and supporting the accurate identification of disturbance frequency components.

[0100] The present application further proposes that the steps of extracting the instantaneous disturbance frequency of the phase difference between the first phase information and the second phase information based on the continuous short-time spectrum analysis results and using the instantaneous disturbance frequency as multiple disturbance frequency components include:

[0101] Identifying, based on the continuous short-time spectrum analysis results, an energy peak of a spectrum of a phase difference between the first phase information and the second phase information;

[0102] analyzing spectral characteristics of the energy peak, where the spectral characteristics of the energy peak include peak width and / or peak shape;

[0103] According to the spectrum characteristics of the energy peak, determine whether the spectrum characteristics of the energy peak are formed by the superposition of multiple close instantaneous disturbance frequencies;

[0104] If it is determined that the disturbance is formed by the superposition of multiple adjacent instantaneous disturbance frequencies, the multiple adjacent instantaneous disturbance frequencies are separated;

[0105] The multiple separated instantaneous disturbance frequencies and the instantaneous disturbance frequencies corresponding to the energy peaks that are not determined to be formed by superposition are used as the multiple disturbance frequency components included in the phase difference between the first phase information and the second phase information.

[0106] Among them, the spectral characteristics of the energy peak refer to the inherent properties of the energy concentration area in the spectrum, which can be characterized by parameters such as peak width, peak shape, peak symmetry, peak slope or peak sidelobe structure. Its purpose is to provide a basis for judging whether the energy peak is composed of a single frequency component or a superposition of multiple frequency components. Among them, separating multiple close instantaneous disturbance frequencies means decomposing a composite energy peak formed by the superposition of multiple frequency components into multiple independent and finer frequency components. It can be achieved by using signal decomposition algorithms, blind source separation technology, high-resolution spectrum estimation methods or parameter estimation methods based on model fitting. Its purpose is to accurately identify and extract each independent instantaneous disturbance frequency, avoid mistaking multiple close frequencies for one frequency, and thus improve the accuracy of frequency analysis.

[0107] The solution of the present application performs continuous short-time spectrum analysis on the phase difference between the first phase information and the second phase information, and on this basis, further optimizes the extraction process of the instantaneous disturbance frequency. Specifically, the solution first identifies the energy peaks in the phase difference spectrum based on the results of the continuous short-time spectrum analysis. These energy peaks are preliminary indications of potential disturbance frequencies because they represent frequency regions where the signal energy is concentrated. Subsequently, the solution performs in-depth spectrum feature analysis on these identified energy peaks, such as evaluating their peak width and / or peak shape. The peak width and shape can provide important information about whether the peak is caused by a single frequency or the superposition of multiple instantaneous disturbance frequencies with similar frequencies. For example, an abnormally wide peak or an irregular peak shape usually suggests that it may contain multiple closely adjacent frequency components. Based on the analysis of the spectrum characteristics of the energy peak, the solution further determines whether the energy peak is formed by the superposition of multiple close instantaneous disturbance frequencies. This judgment is a key step, which enables the system to distinguish between simple single-frequency disturbances and complex superposition disturbances. If the judgment result shows that the energy peak is indeed formed by the superposition of multiple close instantaneous disturbance frequencies, the system will perform a separation operation to decompose these superimposed frequency components into multiple independent instantaneous disturbance frequencies. This separation process can significantly improve the accuracy of frequency identification and avoid confusing multiple actual disturbance frequencies into a single frequency. Finally, whether it is the multiple instantaneous disturbance frequencies obtained after separation or the instantaneous disturbance frequencies corresponding to the energy peaks that are not judged to be superimposed, they will be regarded as multiple disturbance frequency components contained in the phase difference between the first phase information and the second phase information. Through this refined processing, this solution overcomes the inaccuracy brought about by the traditional method of simply taking the center frequency of the energy peak as the instantaneous disturbance frequency. It can more comprehensively and accurately capture the complex disturbance frequency components contained in the phase difference, especially those disturbances that are superimposed on each other due to close frequencies. This precise identification of the disturbance frequency components provides a more reliable and precise basis for subsequent phase correction. When these more accurate disturbance frequency components are used to determine the original disturbance frequency and generate composite phase correction instructions, the accuracy and performance of the microinverter output power control can be significantly improved, thereby effectively suppressing the specific sideband harmonic currents generated by the internal phase-locked loop being interfered with by high-frequency noise, thereby improving the grid-connected power quality.

[0108] In some preferred embodiments, the present application is specifically implemented as follows: After obtaining continuous short-time spectrum analysis results, a threshold-based peak detection algorithm can be used to identify the energy peak of the spectrum of the phase difference between the first phase information and the second phase information. For example, an energy threshold can be set, and any frequency point above the threshold is preliminarily identified as an energy peak. Subsequently, to analyze the spectral characteristics of these energy peaks, the full width at half maximum (FWHM) of each identified peak can be calculated as the peak width, and the slope change rate on both sides of the peak can be calculated or the residual of the Gaussian fit can be used to characterize the peak shape. For example, if the full width at half maximum of a peak exceeds a preset threshold, or its shape significantly deviates from an ideal single-frequency peak (such as a Gaussian peak or a Lorentz peak), it can be preliminarily determined that it may be formed by the superposition of multiple adjacent transient disturbance frequencies. Furthermore, based on the peak width and / or peak shape obtained by analysis, a machine learning classifier or a rule-based expert system can be used to determine whether the spectral characteristics of the energy peak are formed by the superposition of multiple adjacent transient disturbance frequencies. For example, a support vector machine (SVM) model can be trained to input features such as peak width and peak symmetry, and output a judgment result on whether it is a superposition peak. If it is determined to be formed by the superposition of multiple close instantaneous disturbance frequencies, signal decomposition techniques such as independent component analysis (ICA) or non-negative matrix factorization (NMF) can be used to separate multiple close instantaneous disturbance frequencies. For example, the local spectrum region where the superposition peak is located is regarded as a mixed signal and decomposed into multiple independent frequency components using the ICA algorithm. Finally, the multiple independent instantaneous disturbance frequencies obtained through the above separation process, as well as the instantaneous disturbance frequencies corresponding to the energy peaks that were not identified as superposition in the judgment step, are collectively used as multiple disturbance frequency components contained in the phase difference between the first phase information and the second phase information for use by the subsequent phase correction module.

[0109] The present application further proposes that the steps of separating multiple close instantaneous disturbance frequencies include:

[0110] Performing curve fitting on the energy peaks;

[0111] Based on the fitting results, the energy peak is decomposed into multiple independent sub-peaks;

[0112] The center frequency corresponding to each sub-peak is extracted as multiple close instantaneous disturbance frequencies.

[0113] Among them, curve fitting processing refers to approximating or describing the shape and distribution of the energy peak through a mathematical model. Gaussian fitting, Lorentz fitting, polynomial fitting or spline fitting methods can be used. Its purpose is to provide a mathematical basis for subsequent peak decomposition, so as to accurately identify the superimposed frequency components; decomposing the energy peak into multiple independent sub-peaks means using an algorithm to decompose a complex, broad energy peak into several narrower peaks with independent characteristics. Each sub-peak represents an independent frequency component. Iterative fitting, peak detection and separation algorithms or model-based decomposition methods can be used. Its purpose is to identify multiple instantaneous disturbance frequencies that were originally mixed together; extracting the center frequency corresponding to each sub-peak means determining the frequency point with the largest energy or amplitude from each independent sub-peak. It can be done by calculating the peak position of the fitting curve or directly finding the maximum value point from the decomposed sub-peak data. Its purpose is to obtain the numerical value of each instantaneous disturbance frequency for subsequent phase correction.

[0114] The solution of the present application can capture the shape and potential superposition structure of the energy peak in the spectrum by performing curve fitting processing on the energy peak. This fitting process provides a data basis for subsequent decomposition, avoiding the errors caused by simple thresholds or rough segmentation. Based on the fitting results, the energy peak is decomposed into multiple independent sub-peaks, so that the instantaneous disturbance frequencies of multiple frequencies close to each other that were originally mixed together can be separated. Each sub-peak represents an independent disturbance frequency component, thus solving the problem that traditional methods have difficulty in distinguishing these closely adjacent frequencies. Subsequently, the center frequency corresponding to each sub-peak is extracted. These center frequencies are obtained after fitting and decomposition and represent the estimated values ​​of each instantaneous disturbance frequency. These instantaneous disturbance frequency information can be identified as multiple disturbance frequency components contained in the phase difference between the first phase information and the second phase information. In the entire micro-inverter output power control method, this separation process is a key link in identifying the phase disturbance amount. By separating these close instantaneous disturbance frequencies, the original disturbance frequency information can be provided for the subsequent generation of composite phase correction instructions. For example, when generating the corresponding phase correction component, the instantaneous amplitude and instantaneous phase of each separated instantaneous disturbance frequency can be tracked in real time, and a compensation signal with the same frequency, the same instantaneous amplitude, and the opposite phase can be generated. The composite phase correction instruction formed by superimposing these compensation signals can offset the phase modulation effect caused by high-frequency voltage noise, thereby reducing the sideband harmonic components in the microinverter output current. Therefore, this solution can improve the accuracy of phase correction, thereby improving the power quality of the microinverter's grid-connected output current, avoiding the problems of under-correction or over-correction caused by inaccurate frequency identification, and ensuring the stable operation and purity of the microinverter's output power in complex power grid environments.

[0115] In some preferred embodiments, when the system identifies an energy peak in the frequency spectrum of the phase difference between the first and second phase information, formed by the superposition of multiple adjacent instantaneous disturbance frequencies—for example, a wide peak near 2 kHz—this indicates the possible presence of multiple disturbance components with similar frequencies, such as 2000 Hz, 2010 Hz, and 2020 Hz. To separate these components, a curve fitting process can be performed on the energy peak. Specifically, a Gaussian Mixture Model (GMM) can be used to fit the energy peak. This model can decompose a complex peak into a superposition of multiple Gaussian distributions, each representing an independent sub-peak. For example, if the fitting results indicate that the peak may be formed by the superposition of three Gaussian distributions, then based on this fitting result, the energy peak is decomposed into three independent sub-peaks. Subsequently, the corresponding center frequency of each decomposed sub-peak is extracted. For example, the center frequency of the first sub-peak may be 2000 Hz, the center frequency of the second sub-peak may be 2010 Hz, and the center frequency of the third sub-peak may be 2020 Hz. These extracted center frequencies, 2000Hz, 2010Hz, and 2020Hz, serve as multiple, close instantaneous disturbance frequencies for subsequent phase correction processing. In this way, even close disturbance frequencies can be identified and separated, providing frequency information for subsequent compensation.

[0116] The present application further proposes that the steps of generating a composite phase correction instruction according to multiple original disturbance frequencies include:

[0117] generating corresponding phase correction components according to a plurality of original disturbance frequencies;

[0118] The phase correction components are superimposed to generate a composite phase correction instruction.

[0119] Among them, the original disturbance frequency refers to the interference signal component with specific frequency characteristics that causes the phase deviation of the system. It can come from high-frequency noise in the power grid, harmonics generated by nonlinear loads, or oscillations within the system. Its purpose is to identify and quantify the specific frequency components that cause phase disturbances; the phase correction component refers to a compensation signal calculated or generated separately for each original disturbance frequency to offset the frequency disturbance. It can be a sinusoidal wave signal with the same frequency and amplitude but opposite phase as the disturbance frequency, or it can be a correction amount calculated based on a specific frequency response model. Its purpose is to provide customized compensation for each independent disturbance frequency; the composite phase correction instruction refers to the final correction signal formed by combining all independent phase correction components. It can be obtained by linear superposition, weighted summation or other signal synthesis methods. Its purpose is to provide a comprehensive instruction that can compensate for multiple frequency disturbances at the same time. Generating the corresponding phase correction component means calculating or constructing a compensation signal that can effectively offset the influence of the frequency disturbance based on each identified original disturbance frequency. Specifically, it can be found through a preset frequency-compensation amount mapping relationship, or calculated in real time through an adaptive algorithm. Its purpose is to provide an accurate correction basis for subsequent superposition operations; superimposing the phase correction component means combining the independent phase correction components generated for different original disturbance frequencies to form a unified correction signal. Specifically, it can be achieved through simple arithmetic addition, or by taking into account the weight of each component for weighted summation. Its purpose is to integrate the scattered compensation information into a single instruction that can be directly applied to system control.

[0120] The solution of the present application achieves precise compensation for phase disturbances by decomposing complex phase disturbances into multiple independent original disturbance frequencies and generating specific phase correction components for each frequency. These components are finally superimposed to form a composite phase correction instruction. Specifically, after obtaining the grid-connected AC voltage signal, the system performs the first phase-locked loop processing and the second phase-locked loop processing in parallel, respectively extracting the first phase information containing the interference component and the second phase information after filtering out the interference component. Subsequently, by calculating the phase difference between the first phase information and the second phase information and performing spectral analysis on the phase difference, the multiple disturbance frequency components contained therein can be identified, thereby determining the multiple original disturbance frequencies that cause the phase difference. On this basis, the present solution further generates corresponding phase correction components for each of these multiple determined original disturbance frequencies. This means that the system no longer treats all disturbances as a whole for rough compensation, but is able to identify and process disturbances at each specific frequency. For example, if there are disturbance frequencies of 2kHz and 3kHz, the system will generate independent correction signals for 2kHz and 3kHz respectively. This refined processing method enables each correction component to accurately match the characteristics of the disturbance frequency it targets, including its amplitude and phase. Subsequently, these phase correction components generated for different original disturbance frequencies are accurately superimposed to form a unified composite phase correction instruction. The superposition operation integrates each independent correction signal into a comprehensive instruction that can simultaneously contain compensation information for multiple frequency disturbances. This superposition method ensures that the final correction instruction can cover the entire disturbance spectrum, thereby achieving comprehensive and accurate cancellation of complex phase disturbances. It is precisely because of this strategy of "decomposing - independent processing - accurate superposition" of complex disturbances that the generated composite phase correction instruction can more accurately reflect and offset the actual phase disturbance amount. Compared with correction methods based only on a single frequency or rough estimation, this scheme can effectively suppress the harmonic components caused by high-frequency voltage noise, such as the 1950Hz and 2050Hz sideband harmonics mentioned in the background technology, thereby significantly improving the grid-connected power quality of the micro-inverter, avoiding the in-phase superposition effect of harmonics when multiple inverters are connected in parallel, and solving the problem of how to effectively use the original disturbance frequency to construct a composite correction instruction to achieve more accurate phase compensation.

[0121] In some preferred embodiments, the specific process of generating a composite phase correction instruction based on multiple original disturbance frequencies can be implemented as follows: after the system determines multiple original disturbance frequencies such as f1, f2, and f3 through spectrum analysis, the system can configure an independent signal generator or algorithm module for each original disturbance frequency. For example, for the original disturbance frequency f1, the system can monitor in real time the instantaneous amplitude and instantaneous phase of the corresponding f1 component in the phase difference between the first phase information and the second phase information. Based on this real-time tracked information, the system can generate a sinusoidal compensation signal with the same frequency and instantaneous amplitude as the f1 component but with a completely opposite phase, and use it as the phase correction component for f1. Similarly, for the original disturbance frequencies f2 and f3, the system can also use a similar method to generate corresponding phase correction components respectively. Once all identified original disturbance frequencies have generated their respective phase correction components, these components are then sent to a summing unit or digital accumulator. The summing unit linearly superimposes all independent phase correction components. For example, if the phase correction components are represented as time functions C1(t), C2(t), and C3(t), the composite phase correction instruction can be simply expressed as C_composite(t) = C1(t) + C2(t) + C3(t). This superposition operation can be implemented in a digital signal processor through a simple addition operation. The final superposition signal is the composite phase correction instruction, which contains comprehensive compensation information for all identified original disturbance frequencies and can be directly used in the subsequent phase correction process to offset the phase deviation caused by these disturbance frequencies.

[0122] Through the above technical solution, the present application can generate an independent phase correction component for each original disturbance frequency and accurately superimpose them, thereby constructing a composite phase correction instruction that can simultaneously compensate for multiple frequency disturbances. This method avoids single or rough compensation for complex phase disturbances, but instead achieves refined and customized correction of different frequency disturbance components. Therefore, this solution can significantly improve the accuracy and effectiveness of phase compensation, so that the micro-inverter can output a purer AC current in a complex power grid environment even in the face of multi-band high-frequency voltage noise, effectively suppressing the sideband harmonics generated by phase modulation, thereby improving the quality of grid-connected power.

[0123] The present application further proposes that the steps of generating the corresponding phase correction component include:

[0124] For multiple original disturbance frequencies, tracking in real time the instantaneous amplitude and instantaneous phase of the component corresponding to the original disturbance frequency in the phase difference between the first phase information and the second phase information;

[0125] According to the instantaneous amplitude and the instantaneous phase, a compensation signal having the same frequency, the same instantaneous amplitude and the opposite phase as the component corresponding to the original disturbance frequency is generated as a phase correction component.

[0126] Among them, real-time tracking means that the system can continuously and dynamically monitor and obtain the amplitude and phase information of the target signal at a specific time point. It can be achieved by using digital signal processing technology, such as adaptive filtering algorithms or Kalman filtering, and its purpose is to capture the dynamic change characteristics of the signal. The compensation signal refers to an artificially generated signal, which is designed to offset or weaken the impact of the disturbance signal. Specifically, it can be achieved by anti-phase superposition, and its purpose is to achieve accurate offset. The phase correction component refers to the signal component used to correct the system phase error. It can be a combination of one or more compensation signals, and its purpose is to provide a correction value for subsequent phase correction.

[0127] The solution of this application optimizes the microinverter output power control method, aiming to address the problem in the prior art where static correction instructions are difficult to adapt to dynamic phase disturbances. Specifically, in the process of generating composite phase correction instructions, this solution no longer relies on fixed correction parameters, but instead introduces a dynamic compensation mechanism. First, for multiple identified original disturbance frequencies, the system tracks in real time the instantaneous amplitude and instantaneous phase of the components corresponding to these original disturbance frequencies in the phase difference between the first phase information and the second phase information. This means that the system can continuously perceive the intensity and phase changes of each disturbance component at different times, thereby obtaining its dynamic characteristics. Subsequently, based on these real-time tracked instantaneous amplitude and instantaneous phase, the system generates a compensation signal with the same frequency, instantaneous amplitude, and opposite phase as the component corresponding to the original disturbance frequency. This compensation signal is used as the phase correction component. Because the compensation signal and the disturbance component have exactly the same instantaneous characteristics but opposite phase, when they are superimposed, they can cancel out the original disturbance component. In this way, each phase correction component can dynamically adapt to the changes in the specific disturbance frequency component it targets. When these dynamically generated phase correction components are superimposed to form a composite phase correction command, the composite command is able to compensate for dynamically changing phase disturbances in the power grid. The dynamic nature of this compensation mechanism significantly improves the accuracy of phase disturbance calculations. This in turn enables the corrected current command generated based on the corrected phase to more effectively suppress harmonics in the microinverter's output current, thereby improving power quality and resolving the problem that static correction commands are unable to effectively address dynamic disturbances.

[0128] In some embodiments, the process of generating the corresponding phase correction component can be specifically implemented as follows: for each original disturbance frequency identified in the spectrum analysis, such as 2kHz and 4kHz, the system can construct an independent digital phase-locked loop respectively. These independent phase-locked loops are configured to specifically track the component corresponding to its specific original disturbance frequency in the phase difference between the first phase information and the second phase information. Through these phase-locked loops, the system can extract the instantaneous amplitude and instantaneous phase of each disturbance frequency component in real time. For example, for the 2kHz disturbance component, its phase-locked loop will output a signal representing the instantaneous amplitude and instantaneous phase of the component. Subsequently, based on these instantaneous amplitudes and instantaneous phases obtained in real time, the system can use a signal generator or digital synthesizer to generate a sinusoidal wave signal with the same frequency, the same instantaneous amplitude, but the exact opposite phase as the disturbance component. This inverted sinusoidal wave signal serves as the corresponding phase correction component. For example, if the instantaneous amplitude of a 2kHz disturbance component at a certain moment is A and the instantaneous phase is φ, the generated compensation signal will be a sine wave with a frequency of 2kHz, an instantaneous amplitude of A, and an instantaneous phase of φ+π (or φ-π). In this way, for each original disturbance frequency, an inverted compensation signal that matches its dynamic characteristics can be generated, thus providing a dynamically adjustable component for the subsequent generation of the composite phase correction command.

[0129] Through the above technical solution, the present application can provide an accurate and dynamic solution to the harmonic problem caused by phase disturbance in the output current of the micro-inverter. By tracking the instantaneous amplitude and instantaneous phase of each original disturbance frequency component in real time, and generating a compensation signal with the same instantaneous amplitude and opposite phase as the phase correction component, the present application overcomes the limitation that the static form of the traditional correction instruction cannot adapt to the dynamic changes of the disturbance signal. This enables the generated composite phase correction instruction to offset the time-varying phase disturbance caused by the original disturbance frequency, and the accuracy and effectiveness of the phase correction are greatly improved. Ultimately, this helps to suppress the harmonic components in the output current of the micro-inverter and improve the quality of the grid-connected power.

[0130] The present application further proposes that the steps of real-time tracking of the instantaneous amplitude and instantaneous phase of the component corresponding to the original disturbance frequency in the phase difference between the first phase information and the second phase information include:

[0131] For multiple original disturbance frequencies, independent phase-locked loops are constructed respectively;

[0132] The instantaneous amplitude and instantaneous phase of the component corresponding to the original disturbance frequency in the phase difference between the first phase information and the second phase information are tracked in real time through a phase-locked loop.

[0133] Among them, the independent phase-locked loop refers to configuring a special phase-locked loop unit for each original disturbance frequency component. These phase-locked loop units operate independently of each other in structure or logic and do not interfere with each other. Specifically, it can be achieved by constructing multiple independent phase-locked loop circuits in hardware, or by instantiating multiple independent phase-locked loop algorithm modules in software. Its purpose is to ensure that the tracking process of each disturbance frequency is not affected by other frequency components, thereby improving the specificity and accuracy of tracking. Through the phase-locked loop, real-time tracking of the instantaneous amplitude and instantaneous phase of the component corresponding to the original disturbance frequency in the phase difference between the first phase information and the second phase information refers to utilizing the synchronous tracking capability of the phase-locked loop, not only locking and outputting the instantaneous phase corresponding to the original disturbance frequency component, but also combining the signal processing mechanism inside or outside the phase-locked loop, such as through synchronous rotating coordinate system transformation or generalized integrator and other methods, to extract the instantaneous amplitude of the component in real time. Its purpose is to provide accurate instantaneous amplitude and phase information for the subsequent generation of phase correction components.

[0134] The solution of the present application achieves accurate and real-time tracking of the instantaneous amplitude and instantaneous phase of the component corresponding to the original disturbance frequency in the phase difference between the first phase information and the second phase information by constructing independent phase-locked loops for multiple original disturbance frequencies. Specifically, when the system identifies multiple original disturbance frequencies, it no longer uses a single, potentially limited tracking mechanism. Instead, a dedicated phase-locked loop is assigned to each identified disturbance frequency. Each phase-locked loop is optimized to focus on its specific frequency component, effectively avoiding crosstalk between different frequency components and improving the accuracy of extracting the instantaneous amplitude and instantaneous phase of each component. It is precisely because of this decoupled and specialized tracking mechanism that each phase-locked loop can quickly and accurately lock on to and output the instantaneous amplitude and instantaneous phase of its corresponding component even when the disturbance frequency is high or changing rapidly. This highly precise instantaneous information is then used to generate a compensation signal, namely a phase correction component, with the same frequency, the same instantaneous amplitude, and the opposite phase as the original disturbance component. By superimposing these precisely generated phase correction components, a more accurate composite phase correction instruction can be formed. This composite phase correction instruction, as a phase disturbance quantity, can more effectively correct the output current instruction of the microinverter, thereby offsetting the internally generated harmonics caused by the high-frequency noise of the power grid at the source, ensuring the purity of the microinverter output current, and solving the problem that traditional methods are difficult to accurately and quickly extract instantaneous information in complex disturbance environments, thereby affecting the accuracy and real-time performance of phase correction.

[0135] In some preferred embodiments, when the system identifies two primary original disturbance frequencies, such as 2 kHz and 4 kHz, through spectrum analysis, two independent phase-locked loops (PLLs) can be constructed. The first PLL can be configured to specifically track the 2 kHz disturbance component, and its loop filter and phase detector parameters can be optimized for the 2 kHz signal to ensure rapid locking and precise tracking of this frequency component. Simultaneously, this PLL can be integrated with or coupled with a synchronous rotating coordinate system transformation module to transform the 2 kHz component into the DC domain, thereby conveniently extracting its instantaneous amplitude and phase. Similarly, a second independent PLL can be configured to specifically track the 4 kHz disturbance component and extract its instantaneous amplitude and phase using a similar method. These two PLLs operate in parallel without interfering with each other, each outputting the instantaneous amplitude and phase information for its corresponding frequency component. This information is then fed into a phase correction component generation module to generate its own compensation signals, which are ultimately superimposed to form a composite phase correction command to achieve precise correction of the microinverter's output current.

[0136] Through the above technical solution, the present application can use independent phase-locked loops to accurately and in real time track the instantaneous amplitude and instantaneous phase for multiple original disturbance frequencies. This method effectively solves the problem that traditional direct tracking methods are difficult to accurately and quickly extract the required instantaneous information in complex power grid environments, especially when the disturbance frequency is high or changes rapidly. By providing a dedicated tracking mechanism for each disturbance frequency component, the extraction accuracy and response speed of the instantaneous amplitude and instantaneous phase are improved, thereby ensuring the accuracy and real-time nature of the subsequent phase correction component generation, and ultimately effectively suppressing the specific sideband harmonic currents generated by the micro-inverter due to interference in the internal phase-locked loop, thereby improving the grid-connected power quality.

[0137] refer to Figure 2 The present application further proposes a micro-inverter output power control system, which is applied to a micro-inverter output power control method. The system includes:

[0138] An acquisition module, used to obtain the AC voltage signal of the grid connection point;

[0139] A first phase-locked loop module extracts first phase information based on the grid-connected point AC voltage signal, where the first phase information includes a voltage phase affected by an interference component having a frequency higher than a fundamental frequency;

[0140] A second phase-locked loop module extracts second phase information based on the grid-connected point AC voltage signal, where the second phase information includes the fundamental wave phase after filtering out interference components;

[0141] A calculation module, configured to calculate a phase disturbance amount based on the first phase information and the second phase information;

[0142] A correction module, configured to generate a correction phase according to the second phase information and the phase disturbance amount;

[0143] A correction instruction generating module, used for generating a correction current instruction based on the correction phase;

[0144] The current control module is used to control the micro inverter to output AC current according to the corrected current instruction.

[0145] Among them, the acquisition module refers to a hardware or software unit for collecting the AC voltage signal of the grid connection point, which can be implemented by a voltage sensor, an analog-to-digital converter or a data interface, etc., and its purpose is to provide raw data for subsequent signal processing; the first phase-locked loop module refers to a circuit or algorithm unit for extracting phase information from the AC signal, which can be implemented by a digital phase-locked loop, an analog phase-locked loop or a software-based phase-locked loop algorithm, and its purpose is to obtain voltage phase information containing interference components with a frequency higher than the fundamental frequency; the second phase-locked loop module refers to another circuit or algorithm unit for extracting phase information from the AC signal, which can be implemented by a filtering characteristic or algorithm different from that of the first phase-locked loop module, and its purpose is to obtain the fundamental phase information after filtering out the interference; the calculation module refers to a unit for performing data processing and logical operations, which can It is implemented by a microcontroller, a digital signal processor or a dedicated integrated circuit, and its purpose is to determine the phase disturbance amount based on the two phase information; the correction module refers to a unit used to adjust or correct the signal, which can be implemented by a digital logic circuit, a software algorithm or an analog circuit, and its purpose is to generate a corrected phase based on the fundamental phase and the phase disturbance amount; the correction instruction generation module refers to a unit used to generate a control instruction based on a specific input, which can be implemented by a lookup table method, a mathematical model or a proportional integral controller, and its purpose is to generate an instruction for controlling the output current based on the corrected phase; the current control module refers to a unit used to regulate and control the current output, which can be implemented by a pulse width modulation controller, a power semiconductor switch or a current sensor, and its purpose is to control the micro inverter to output AC current according to the corrected current instruction.

[0146] The solution of the present application enables the above-mentioned micro-inverter output power control method to be specifically implemented by constructing a modular system structure. The system first collects the AC voltage signal of the grid connection point in real time through the acquisition module to provide basic data for the entire control process. Subsequently, the voltage signal is sent to the first phase-locked loop module and the second phase-locked loop module in parallel. The first phase-locked loop module is specifically used to extract the first phase information containing high-frequency interference components, while the second phase-locked loop module focuses on extracting the fundamental phase information after filtering out the interference. This parallel processing mechanism ensures that two phase references with different characteristics can be obtained at the same time, laying the foundation for subsequent disturbance analysis.

[0147] Next, the calculation module receives phase information from the two phase-locked loop modules and calculates the phase disturbance based on the difference between them. This phase disturbance indicates the specific impact of high-frequency interference on the voltage phase. The correction module uses the second phase information (fundamental phase) and the calculated phase disturbance to generate a corrected phase signal. This corrected phase signal offsets the negative impact of high-frequency interference on the synchronous phase, ensuring the accuracy of subsequent current commands.

[0148] Based on this, the correction command generation module generates a correction current command based on this corrected phase signal. This command takes into account the actual phase condition of the grid and compensates for phase deviations caused by high-frequency disturbances. Finally, the current control module receives and executes the correction current command to control the microinverter's output AC current. This ensures that the microinverter outputs a current that is synchronized and in phase with the grid voltage, thereby reducing output current harmonics caused by high-frequency voltage disturbances.

[0149] This system architecture provides the hardware or software platform support for the practical deployment and operation of the aforementioned control method. By decomposing the control logic into modules with clear functions, the system's feasibility and operational stability are improved. Furthermore, the control method can be transformed from a theoretical perspective into an operational entity, thus resolving the control method's lack of specific system architecture support. This allows the control method to be applied in practice, thereby improving the grid-connected power quality of microinverters in complex grid environments.

[0150] In some embodiments, the present application is specifically implemented as follows: The acquisition module may be composed of a voltage sensor and an analog-to-digital converter. The voltage sensor is used to convert the grid-connected point AC voltage signal into an analog electrical signal, and the analog-to-digital converter converts the analog electrical signal into a digital signal for subsequent digital processing.

[0151] Both the first and second phase-locked loop modules can be implemented using software algorithms on a digital signal processor (DSP) or microcontroller (MCU). The first phase-locked loop module can utilize a wideband phase-locked loop algorithm, with its internal filter designed to allow higher-frequency interference components to pass through, ensuring that the first phase information reflects the effects of high-frequency disturbances. The second phase-locked loop module can utilize a narrowband phase-locked loop algorithm, with its internal filter designed to effectively filter out interference components with frequencies higher than the fundamental frequency, thereby extracting the fundamental phase.

[0152] The calculation module and correction module can also be run as software modules on the same DSP or MCU. The calculation module can perform phase difference calculation and disturbance analysis algorithms, for example, by comparing the phase angles of two phase-locked loop outputs to determine the phase disturbance. The correction module can then add or subtract the calculated phase disturbance from the second phase information based on preset correction logic to generate the corrected phase.

[0153] The correction instruction generation module can be a current reference generator based on the correction phase and the expected output power, which can also be implemented by software on a DSP or MCU, for example, through a sine wave generator whose phase is determined by the correction phase and whose amplitude is determined by the power instruction, thereby generating a correction current instruction.

[0154] The current control module can consist of a proportional resonant (PR) controller or proportional integral (PI) controller and a pulse width modulation (PWM) generator. These components are typically integrated into a DSP or MCU to drive the inverter's power semiconductor switches, such as insulated gate bipolar transistors (IGBTs) or metal oxide semiconductor field effect transistors (MOSFETs), thereby controlling the microinverter's output AC current according to the corrected current command. The entire system can exchange data and receive commands with an external monitoring system via a communication interface.

[0155] Through the above technical solution, the present application provides a specific system structure, which enables the micro-inverter output power control method to be transformed from a theoretical level into a practical deployable solution. Through modular design, the system clarifies the responsibilities and mutual cooperation relationships of each functional unit, thereby solving the problem of the lack of a specific implementation carrier for the control method. This enables the control method to be effectively integrated into the micro-inverter product, realizing the perception of the AC voltage signal at the grid connection point, the extraction and correction of phase information, and the control of the output current. Ultimately, the system can ensure that the micro-inverter can still output AC current that meets the power quality requirements in a grid environment with high-frequency voltage disturbances, suppress the generation of harmonic components, and improve the grid-connected power quality and the stability of the system operation.

[0156] The contents disclosed above are only preferred feasible embodiments of the present invention and do not limit the scope of protection of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention description and drawings are included in the scope of protection of the present invention. In addition, the elements therein can be updated as technology develops.

Claims

1. A micro-inverter output power control method, characterized in that: The method comprises the following steps: Obtaining AC voltage signal of grid connection point; Based on the AC voltage signal at the grid connection point, the following are performed in parallel: a first phase-locked loop process is performed to extract first phase information, where the first phase information includes the voltage phase affected by interference components with a frequency higher than the fundamental frequency; and a second phase-locked loop process is performed to extract second phase information, where the second phase information includes the fundamental phase after filtering out the interference components. Calculating a phase disturbance amount according to the first phase information and the second phase information; generating a correction phase according to the second phase information and the phase disturbance amount; generating a corrected current command based on the corrected phase; According to the corrected current instruction, the micro inverter is controlled to output AC current.

2. A micro-inverter output power control method according to claim 1, characterized in that: The steps for calculating the phase perturbation include: Acquire a phase difference between the first phase information and the second phase information; performing a spectrum analysis on the phase difference between the first phase information and the second phase information to identify a plurality of disturbance frequency components contained in the phase difference between the first phase information and the second phase information; determining, based on the plurality of disturbance frequency components, a plurality of original disturbance frequencies causing a phase difference between the first phase information and the second phase information; generating a composite phase correction instruction according to a plurality of original disturbance frequencies; The composite phase correction instruction is used as the phase disturbance amount.

3. A micro-inverter output power control method according to claim 2, characterized in that: The step of performing spectrum analysis on the phase difference between the first phase information and the second phase information to identify multiple disturbance frequency components contained in the phase difference between the first phase information and the second phase information includes: performing continuous short-time spectrum analysis on a phase difference between the first phase information and the second phase information; According to the continuous short-time spectrum analysis results, the instantaneous disturbance frequency in the phase difference between the first phase information and the second phase information is extracted, and the instantaneous disturbance frequency is used as a plurality of disturbance frequency components.

4. A micro-inverter output power control method according to claim 3, characterized in that: The steps to perform continuous short-time spectrum analysis include: monitoring a spectral characteristic of a signal of a phase difference between the first phase information and the second phase information; Adjusting the window length and / or window overlap ratio of continuous short-time spectrum analysis according to spectrum characteristics; Continuous short-time spectrum analysis is performed on the phase difference between the first phase information and the second phase information according to the adjusted window length and / or window overlap ratio.

5. The micro-inverter output power control method according to claim 3, wherein: The steps of extracting the instantaneous disturbance frequency in the phase difference between the first phase information and the second phase information according to the continuous short-time spectrum analysis results and using the instantaneous disturbance frequency as the plurality of disturbance frequency components include: identifying, based on the continuous short-time spectrum analysis results, an energy peak in the spectrum of the phase difference between the first phase information and the second phase information; analyzing spectral characteristics of the energy peak, where the spectral characteristics of the energy peak include peak width and / or peak shape; According to the spectrum characteristics of the energy peak, determine whether the spectrum characteristics of the energy peak are formed by the superposition of multiple close instantaneous disturbance frequencies; If it is determined that the disturbance is formed by the superposition of multiple adjacent instantaneous disturbance frequencies, the multiple adjacent instantaneous disturbance frequencies are separated; The multiple separated instantaneous disturbance frequencies and the instantaneous disturbance frequencies corresponding to the energy peaks that are not determined to be formed by superposition are used as the multiple disturbance frequency components included in the phase difference between the first phase information and the second phase information.

6. A micro-inverter output power control method according to claim 5, characterized in that: The steps of separating multiple close transient disturbance frequencies include: Performing curve fitting on the energy peaks; Based on the fitting results, the energy peak is decomposed into multiple independent sub-peaks; The center frequency corresponding to each sub-peak is extracted as multiple close instantaneous disturbance frequencies.

7. The micro-inverter output power control method according to claim 2, wherein: The steps of generating a composite phase correction instruction according to the multiple original disturbance frequencies include: generating corresponding phase correction components according to a plurality of original disturbance frequencies; The phase correction components are superimposed to generate a composite phase correction instruction.

8. The micro-inverter output power control method according to claim 7, wherein: The steps of generating the corresponding phase correction component include: For multiple original disturbance frequencies, tracking in real time the instantaneous amplitude and instantaneous phase of the component corresponding to the original disturbance frequency in the phase difference between the first phase information and the second phase information; According to the instantaneous amplitude and the instantaneous phase, a compensation signal having the same frequency, the same instantaneous amplitude and the opposite phase as the component corresponding to the original disturbance frequency is generated as a phase correction component.

9. A micro-inverter output power control method according to claim 8, characterized in that: The step of tracking in real time the instantaneous amplitude and instantaneous phase of the component corresponding to the original disturbance frequency in the phase difference between the first phase information and the second phase information comprises: For multiple original disturbance frequencies, independent phase-locked loops are constructed respectively; The instantaneous amplitude and instantaneous phase of the component corresponding to the original disturbance frequency in the phase difference between the first phase information and the second phase information are tracked in real time through a phase-locked loop.

10. A micro-inverter output power control system, applied to the micro-inverter output power control method according to claim 1, characterized in that: The system includes: An acquisition module, used to obtain the AC voltage signal of the grid connection point; A first phase-locked loop module extracts first phase information based on the grid-connected point AC voltage signal, where the first phase information includes a voltage phase affected by an interference component having a frequency higher than a fundamental frequency; A second phase-locked loop module extracts second phase information based on the grid-connected point AC voltage signal, where the second phase information includes the fundamental wave phase after filtering out interference components; A calculation module, configured to calculate a phase disturbance amount based on the first phase information and the second phase information; A correction module, configured to generate a correction phase according to the second phase information and the phase disturbance amount; A correction instruction generating module, used for generating a correction current instruction based on the correction phase; The current control module is used to control the micro inverter to output AC current according to the corrected current instruction.

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