An energy storage inverter adaptive harmonic suppression method and device

Abstract

The present application relates to the technical field of energy storage inverter control, in particular to an adaptive harmonic suppression method and device for energy storage inverters.The present application first samples and denoising preprocesses the output voltage and current, and separates the fundamental wave and harmonic components of the load current; the LMS least mean square adaptive filtering algorithm is used to iteratively update the weight to track the harmonic change, and then the reverse compensation voltage is obtained through the time domain PI closed loop, which is superimposed on the inverter modulation signal and subjected to amplitude limiting processing, and the harmonic suppression is periodically cycled.The present application is realized by software algorithm without changing the hardware, can adapt to single-phase and three-phase off-grid energy storage inverters, solves the problems of insufficient adaptive capacity, poor dynamic response and output power quality decline of the traditional fixed parameter harmonic suppression algorithm when accessing nonlinear loads under off-grid conditions, can effectively reduce the output current harmonic distortion rate, improve the power quality of off-grid power supply, and has good engineering application value.

Description

Technical Field

[0001] This invention relates to the technical field of energy storage inverter control, specifically to an adaptive harmonic suppression method and apparatus for energy storage inverters. Background Technology

[0002] In practical engineering applications, off-grid energy storage inverters are often connected to various nonlinear loads such as rectifier loads, switching power supply loads, and frequency converter loads at their output terminals. During operation, these loads generate a large number of 3rd, 5th, and 7th odd harmonic currents, which cause distortion of the output current and output voltage waveforms of the energy storage inverter, resulting in a significant decrease in the system's power quality.

[0003] Existing traditional harmonic suppression schemes for energy storage inverters mostly employ fixed-parameter filtering algorithms and fixed-order harmonic compensation strategies, which have significant limitations: First, fixed filtering parameters cannot adapt to dynamically changing nonlinear loads, and the harmonic suppression effect drops sharply when there are sudden changes in load power or load type switching; Second, traditional schemes compensate for fixed-order harmonics in a targeted manner, but cannot cover randomly generated noise harmonics, resulting in low harmonic suppression coverage; Third, there is no real-time closed-loop compensation mechanism, and the harmonic suppression lag is severe, which cannot meet the high-precision power supply requirements of off-grid energy storage systems. Summary of the Invention

[0004] The purpose of this invention is to provide an adaptive harmonic suppression method and apparatus for energy storage inverters to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an adaptive harmonic suppression method for energy storage inverters, comprising the following steps:

[0006] S1. Signal sampling and noise reduction preprocessing: Real-time acquisition of output voltage and load current signals of energy storage inverter under off-grid conditions; Signal noise reduction preprocessing is completed by moving average filtering algorithm to remove high-frequency interference from sampling.

[0007] S2. The fundamental harmonic components are separated, the distorted harmonic signal is extracted, the system fundamental parameters are captured by the phase-locked loop, the fundamental component of the preprocessed load current is extracted, and the pure harmonic distorted current signal is calculated.

[0008] S3 and LMS adaptive filtering algorithm harmonic fitting: The LMS least mean square adaptive filtering algorithm is used to dynamically fit the harmonic current signal. The filter weight vector is updated through real-time error iteration to accurately track real-time harmonic characteristics.

[0009] S4. Time-domain closed-loop harmonic compensation calculation: Based on the fitted harmonic signal, the reverse harmonic compensation voltage component is calculated using a time-domain PI closed-loop control algorithm.

[0010] S5, Modulation signal limiting and PWM output, superimposes the harmonic compensation voltage with the inverter's fundamental modulation voltage to generate an optimized modulation reference signal, and performs limiting to prevent over-modulation.

[0011] S6. Periodic iterative control: Based on the limited modulation signal, a PWM drive pulse is generated to drive the power circuit of the energy storage inverter to output a compensation waveform to offset load harmonic distortion.

[0012] Preferably, the formula for calculating the moving average filter preprocessing in S1 is:

[0013]

[0014] Where N is the preset number of points in the sliding filter window. These are the original sampled current values ​​from consecutive historical moments. This is the effective load current signal after noise reduction.

[0015] Preferably, in step S2, the load current is divided into the fundamental effective current and the harmonic distortion current, which is determined by the formula... The pure harmonic distortion current was calculated, where This is the fundamental current component extracted by phase-locked loop. The target harmonic current to be suppressed is denoted as .

[0016] Preferably, in step S3, the LMS adaptive filtering algorithm includes harmonic estimation, error calculation, and weight iteration, with the specific formula as follows:

[0017] Harmonic estimation: ;

[0018] Error calculation: ;

[0019] Weight iteration: ,in This is the iteration step size factor, with a value range of 0 < <1.

[0020] Preferably, the iteration step size factor It can be dynamically configured according to the inverter load conditions. Under heavy load conditions, the step size is increased to improve the convergence speed, and under light load conditions, the step size is decreased to improve the steady-state compensation accuracy.

[0021] Preferably, in step S4, the formula for calculating the time-domain PI closed-loop compensation voltage is:

[0022]

[0023] in This is the proportionality coefficient. The integral coefficient is used to eliminate harmonic compensation steady-state error through integral action.

[0024] Preferably, in step S5, the final modulation reference voltage calculation formula is:

[0025]

[0026] By superimposing a reverse harmonic compensation voltage, the harmonic distortion components on the output side are canceled out.

[0027] Preferably, the method is applicable to the independent power supply of energy storage inverters off-grid, and is suitable for harmonic suppression scenarios of various nonlinear loads such as rectifier loads, switching power supply loads, and frequency conversion loads.

[0028] An adaptive harmonic suppression device for an energy storage inverter, the device comprising:

[0029] The signal acquisition unit includes a voltage sampling sensor, a current sampling sensor, and a signal conditioning circuit. It is responsible for real-time acquisition of analog AC voltage and load current signals from the inverter output side, performing signal amplification, filtering, and isolation, converting high-voltage signals into low-voltage standard signals, and transmitting them to the main control unit to provide raw data for algorithm calculations.

[0030] The main control and arithmetic unit uses a DSP digital signal controller as its core, and integrates all adaptive harmonic suppression algorithms. It also includes signal preprocessing, fundamental harmonic separation, LMS adaptive filtering, time-domain closed-loop compensation, and amplitude limiting modulation modules. It is the core of the entire device's computation and control, responsible for all data processing, logical judgments, and command output.

[0031] The power conversion main circuit unit consists of a DC energy storage port, a bus capacitor, IGBT / MOSFET power switches, and an AC output filter circuit. The DC side connects to the energy storage battery module, while the AC side outputs power and connects to a nonlinear load. It receives PWM drive signals from the main control unit to complete DC-AC power conversion and harmonic compensation output.

[0032] The drive amplifier unit receives the weak PWM pulse signal output by the main control unit, amplifies and electrically isolates it, generates a drive voltage that can drive power devices, and controls the turn-on and turn-off of the power switching transistor.

[0033] The hardware protection unit integrates overvoltage, overcurrent, overheat, and overmodulation protection circuits, monitors the system's operating status in real time, and immediately blocks the PWM drive signal when harmonic compensation is abnormal or system parameters exceed the threshold, thus protecting the power devices and energy storage system.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] 1. Strong adaptability: It abandons the traditional fixed parameter filtering and uses the LMS adaptive algorithm to iterate the weights in real time, which can adapt to any nonlinear load and any harmonic frequency. There is no suppression failure problem when the load changes dynamically.

[0036] 2. High harmonic suppression accuracy: Combined with time-domain PI closed-loop compensation, static compensation error is eliminated, significantly reducing the total harmonic distortion (THD) of the inverter output current and significantly improving off-grid power quality;

[0037] 3. Wide engineering adaptability: The algorithm is implemented purely in software, without the need to modify the hardware structure. It can be directly adapted to single-phase and three-phase off-grid energy storage inverters, with extremely strong compatibility.

[0038] 4. High operational stability: The addition of signal preprocessing, output limiting, and multiple hardware protections avoids system oscillations and device damage caused by algorithm anomalies, thereby improving the reliability of off-grid operation of the energy storage inverter. Detailed Implementation

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] This invention provides a technical solution to address the technical problems of poor suppression of harmonic distortion, weak adaptability, and lag in dynamic response of existing off-grid energy storage inverters for nonlinear loads. It provides an adaptive harmonic suppression method and device, which achieves adaptive suppression of harmonics under all operating conditions and of all orders through real-time signal acquisition and preprocessing, fundamental harmonic separation, dynamic iteration of adaptive algorithms, and precise time-domain closed-loop compensation, thereby improving the off-grid operation stability and power supply quality of energy storage inverters.

[0041] This invention relies on energy storage converter and inverter control technology, using an adaptive filtering algorithm as its core and time-domain closed-loop compensation as its execution carrier, abandoning the traditional fixed-parameter filtering mode. The overall logic is as follows: First, the inverter output electrical signal is acquired and noise reduction preprocessing is completed to accurately separate the fundamental effective component and harmonic distortion component in the load current; then, the compensation weight is dynamically updated iteratively through an adaptive algorithm to track the harmonic variation law in real time; finally, a reverse harmonic compensation signal is generated through time-domain closed-loop control and superimposed on the inverter modulation stage to achieve real-time harmonic cancellation and suppression, with closed-loop iteration and adaptive dynamic adjustment throughout the entire process.

[0042] This invention specifically provides an adaptive harmonic suppression method for energy storage inverters, comprising the following steps:

[0043] S1. Signal sampling and noise reduction preprocessing: Real-time acquisition of output voltage and load current signals of energy storage inverter under off-grid conditions; Signal noise reduction preprocessing is completed by moving average filtering algorithm to remove high-frequency interference from sampling.

[0044] S2. The fundamental harmonic components are separated, the distorted harmonic signal is extracted, the system fundamental parameters are captured by the phase-locked loop, the fundamental component of the preprocessed load current is extracted, and the pure harmonic distorted current signal is calculated.

[0045] S3 and LMS adaptive filtering algorithm harmonic fitting: The LMS least mean square adaptive filtering algorithm is used to dynamically fit the harmonic current signal. The filter weight vector is updated through real-time error iteration to accurately track real-time harmonic characteristics.

[0046] S4. Time-domain closed-loop harmonic compensation calculation: Based on the fitted harmonic signal, the reverse harmonic compensation voltage component is calculated using a time-domain PI closed-loop control algorithm.

[0047] S5, Modulation signal limiting and PWM output, superimposes the harmonic compensation voltage with the inverter's fundamental modulation voltage to generate an optimized modulation reference signal, and performs limiting to prevent over-modulation.

[0048] S6. Periodic iterative control: Based on the limited modulation signal, a PWM drive pulse is generated to drive the power circuit of the energy storage inverter to output a compensation waveform to offset load harmonic distortion.

[0049] S1 is the basic data acquisition stage of the algorithm. Its core purpose is to obtain clean, interference-free inverter output electrical data to avoid misjudgment of harmonic detection due to sampling noise. The inverter's hardware sampling circuit acquires the output AC voltage and output load current signals of the energy storage inverter in real time under off-grid conditions at a fixed sampling frequency. Due to on-site electromagnetic interference and device sampling errors, the original sampled signal contains high-frequency glitches and noise, making it unsuitable for direct harmonic calculation. This invention uses a moving average filtering algorithm to preprocess the original current signal, smoothing the waveform, removing random noise, and preserving the true harmonic characteristics. The moving average filtering preprocessing calculation formula is as follows:

[0050]

[0051] Where N is the preset number of sliding filter window points, which is fixed according to the inverter sampling frequency. These are the original sampled current values ​​from consecutive historical moments. This is the noise-reduced effective load current signal. This represents the discrete sampling time sequence number.

[0052] The purpose of S2 is to separate the fundamental current of normal power supply from the mixed load current and extract the distorted harmonic current that needs to be suppressed, thus accurately locating the source of harmonic interference. First, a software phase-locked loop (PLL) captures the fundamental angular frequency and phase of the inverter output voltage in real time, locking the off-grid system's power frequency fundamental parameters to ensure the accuracy of fundamental current extraction. The load current consists of two parts: the effective fundamental current and the distorted harmonic current. The pure harmonic signal can be obtained by component decomposition.

[0053] Load current is divided into fundamental effective current and harmonic distortion current. The formula for decomposing the current components is as follows: The harmonic current to be suppressed is obtained through transformation: The pure harmonic distortion current was calculated, where This is the fundamental current component extracted by phase-locked loop. The target harmonic current to be suppressed is denoted as .

[0054] In step S3, the real-time harmonic current is the target value. Through dynamic iteration of the adaptive filter, the weight coefficients are continuously adjusted to make the fitted harmonic signal output by the filter infinitely close to the real harmonic signal, achieving accurate harmonic tracking. This algorithm can automatically update the weight parameters according to real-time changes in harmonics, adaptively adapting to dynamic load changes without manual parameter tuning. The LMS adaptive filtering algorithm includes harmonic estimation, error calculation, and weight iteration, with the specific formula as follows:

[0055] Harmonic estimation: ;

[0056] Error calculation: ;

[0057] Weight iteration: ,in, The harmonic estimation signal fitted by the algorithm; This is the filter weight vector; The reference input vector; This represents the error value between the actual harmonics and the fitted harmonics; This is the iteration step size factor, which controls the convergence speed and steady-state accuracy of the algorithm. Its value range is 0 < <1. When the load harmonics change, the error value changes in real time, and the weight vector is automatically updated iteratively to ensure that the algorithm always accurately tracks the latest harmonic characteristics.

[0058] Iteration step size factor It can be dynamically configured according to the inverter load conditions. Under heavy load conditions, the step size is increased to improve the convergence speed, and under light load conditions, the step size is decreased to improve the steady-state compensation accuracy.

[0059] Step S4 is the core of harmonic suppression. It generates a compensation voltage with the same amplitude but opposite phase as the harmonic signal through closed-loop control, thus canceling the harmonic distortion caused by the load and achieving accurate time-domain compensation. Based on the accurate harmonic signal fitted by the adaptive algorithm, a PI closed-loop control algorithm is used to calculate the harmonic compensation voltage component, eliminating steady-state errors and improving compensation accuracy.

[0060] In S4 and S5, the formula for calculating the time-domain PI closed-loop compensation voltage is as follows:

[0061]

[0062] The compensation voltage is superimposed on the original fundamental modulation reference voltage of the inverter to obtain the optimized total modulation voltage signal:

[0063]

[0064] in, This is the reverse harmonic compensation voltage; , These are the PI ratio and the integral coefficient, respectively. This is the original fundamental frequency modulation reference voltage of the inverter; This is the optimized final modulation voltage.

[0065] To prevent excessive harmonic compensation from causing inverter overmodulation, output waveform distortion, and damage to power devices, this step imposes upper and lower limits on the final modulation voltage to ensure safe system operation.

[0066] Limiting logic: When the modulation voltage exceeds the inverter's maximum allowable output amplitude, it is forcibly clamped to the maximum threshold; when it is within the normal range, the original value remains unchanged. The limited modulation signal is sent to the PWM modulation module to generate high-frequency drive pulses, control the inverter's power devices, and output a reverse harmonic compensation waveform to cancel load harmonics.

[0067] This invention's method is applicable to off-grid independent power supply conditions for energy storage inverters, and is suitable for harmonic suppression scenarios of various nonlinear loads such as rectifier loads, switching power supply loads, and frequency converter loads. The algorithm operates entirely in a closed-loop real-time iterative mode. In each control cycle of the inverter, the entire process of sampling, preprocessing, harmonic separation, adaptive fitting, closed-loop compensation, and modulation output is repeatedly executed, continuously and dynamically adapting to the fluctuations of the nonlinear load to achieve uninterrupted harmonic adaptive suppression around the clock.

[0068] This invention also provides an adaptive harmonic suppression device for energy storage inverters, specifically designed to implement the aforementioned adaptive harmonic suppression method. The device is integrated entirely within the off-grid energy storage inverter, requiring no additional hardware installation. Functional iteration can be achieved solely through software algorithm upgrades. The device comprises five functional units:

[0069] The signal acquisition unit includes a voltage sampling sensor, a current sampling sensor, and a signal conditioning circuit. It is responsible for real-time acquisition of analog AC voltage and load current signals from the inverter output side, performing signal amplification, filtering, and isolation, converting high-voltage signals into low-voltage standard signals, and transmitting them to the main control unit to provide raw data for algorithm calculations.

[0070] The main control and arithmetic unit uses a DSP digital signal controller as its core, and integrates all adaptive harmonic suppression algorithms. It also includes signal preprocessing, fundamental harmonic separation, LMS adaptive filtering, time-domain closed-loop compensation, and amplitude limiting modulation modules. It is the core of the entire device's computation and control, responsible for all data processing, logical judgments, and command output.

[0071] The power conversion main circuit unit consists of a DC energy storage port, a bus capacitor, IGBT / MOSFET power switches, and an AC output filter circuit. The DC side connects to the energy storage battery module, while the AC side outputs power and connects to a nonlinear load. It receives PWM drive signals from the main control unit to complete DC-AC power conversion and harmonic compensation output.

[0072] The drive amplifier unit receives the weak PWM pulse signal output by the main control unit, amplifies and electrically isolates it, generates a drive voltage that can drive power devices, and controls the turn-on and turn-off of the power switching transistor.

[0073] The hardware protection unit integrates overvoltage, overcurrent, overheat, and overmodulation protection circuits, monitors the system's operating status in real time, and immediately blocks the PWM drive signal when harmonic compensation is abnormal or system parameters exceed the threshold, thus protecting the power devices and energy storage system.

[0074] Specific Implementation Example 1: This example is applied to a residential off-grid energy storage power supply scenario. The system uses a single-phase off-grid energy storage inverter, with a lithium iron phosphate energy storage battery on the DC side and conventional nonlinear loads such as televisions, inverter air conditioners, and switching power supply lamps connected to the AC output side. These loads operate under complex conditions, with frequent starts and stops, easily generating 3rd and 5th harmonics. When traditional fixed filtering algorithms are used, the inverter output current THD value reaches as high as 18%, with severe waveform distortion, causing some appliances to flicker and become unstable. After deploying the adaptive harmonic suppression method of this invention, the system collects the load current signal in real time and completes noise reduction preprocessing. Through the LMS algorithm, the weight parameters are dynamically iterated to adapt to the dynamic operating conditions of appliance load starts and stops and power fluctuations, and time-domain PI closed-loop compensation is used to accurately cancel harmonics. Actual operation test results show that the inverter output current THD value drops to less than 4%, fully meeting the power quality standards for residential power supply. The output waveform is smooth and stable, completely solving the problems of flickering and abnormal operation of household appliances. At the same time, the algorithm's dynamic adjustment characteristics are adapted to all working conditions of light and heavy loads, without overcompensation, system oscillation, or other faults, greatly improving the power supply stability of residential energy storage systems.

[0075] Specific Implementation Example 2: This example is applied to a small factory off-grid energy storage backup power supply scenario. It employs a three-phase off-grid energy storage inverter, with high-power nonlinear loads such as frequency converters, rectifiers, and industrial control switching power supplies connected to the output side. These loads exhibit complex harmonic frequencies and large harmonic amplitudes during operation, and their operating conditions change frequently with the start and stop of production equipment. Traditional harmonic suppression schemes cannot adapt to dynamic loads, and harmonic suppression failure can easily lead to inverter overheating and malfunctioning protection trips, affecting the reliability of the factory's backup power supply. By adopting the technical solution of this invention, the system can track the harmonic variation characteristics of the high-power nonlinear load in real time, quickly converge and update compensation parameters through an adaptive filtering algorithm, achieving full coverage suppression of multi-frequency superimposed harmonics. Simultaneously, an output limiting protection mechanism avoids the risk of overmodulation under high-power loads. Engineering test data shows that the equipment operated continuously for 24 hours without exceeding harmonic distortion limits, the output current THD was stably controlled below 5%, inverter heating was significantly reduced, and there were no malfunctioning protection trips, effectively ensuring the continuity and stability of industrial and commercial off-grid energy storage backup power supply.

[0076] This invention introduces a harmonic suppression method and supporting device suitable for off-grid energy storage inverters, mainly addressing the practical problem of waveform distortion when inverters operate with nonlinear loads. The entire technical workflow begins with electrical signal acquisition, first performing noise reduction on the sampled voltage and current, then separating the fundamental frequency component (representing normal power consumption) and the harmonic distortion component from the load current. Relying on the LMS adaptive filtering algorithm to track real-time harmonic changes, it eliminates the need for manual parameter adjustments. A compensation voltage is generated using time-domain closed-loop control and superimposed on the inverter control loop, while limiting logic is added to prevent overmodulation. Compared to traditional fixed-parameter filtering methods, this invention can automatically adjust according to load start / stop and power fluctuations, effectively suppressing different types of nonlinear loads, reducing output current harmonic distortion levels, and improving power quality in off-grid conditions. The entire function is implemented entirely through controller software, requiring no additional hardware components, minimizing modification costs, and offering good compatibility. It can be used in ordinary household off-grid energy storage devices, as well as in small-scale industrial and commercial backup energy storage and power supply equipment in remote off-grid areas, possessing broad application potential.

[0077] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An adaptive harmonic suppression method for an energy storage inverter, characterized in that, Includes the following steps: S1. Signal sampling and noise reduction preprocessing: Real-time acquisition of output voltage and load current signals of energy storage inverter under off-grid conditions; Signal noise reduction preprocessing is completed by moving average filtering algorithm to remove high-frequency interference from sampling. S2. The fundamental harmonic components are separated, the distorted harmonic signal is extracted, the system fundamental parameters are captured by the phase-locked loop, the fundamental component of the preprocessed load current is extracted, and the pure harmonic distorted current signal is calculated. S3 and LMS adaptive filtering algorithm harmonic fitting: The LMS least mean square adaptive filtering algorithm is used to dynamically fit the harmonic current signal. The filter weight vector is updated through real-time error iteration to accurately track real-time harmonic characteristics. S4. Time-domain closed-loop harmonic compensation calculation: Based on the fitted harmonic signal, the reverse harmonic compensation voltage component is calculated using a time-domain PI closed-loop control algorithm. S5, Modulation signal limiting and PWM output, superimposes the harmonic compensation voltage with the inverter's fundamental modulation voltage to generate an optimized modulation reference signal, and performs limiting to prevent over-modulation. S6. Periodic iterative control: Based on the limited modulation signal, a PWM drive pulse is generated to drive the power circuit of the energy storage inverter to output a compensation waveform to offset load harmonic distortion.

2. The adaptive harmonic suppression method for an energy storage inverter according to claim 1, characterized in that: The formula for calculating the moving mean filter preprocessing in S1 is as follows: ； Where N is the preset number of points in the sliding filter window. These are the original sampled current values ​​from consecutive historical moments. This is the effective load current signal after noise reduction.

3. The adaptive harmonic suppression method for an energy storage inverter according to claim 1, characterized in that: In S2, the load current is divided into the fundamental effective current and the harmonic distortion current, which is expressed by the formula... The pure harmonic distortion current was calculated, where This is the fundamental current component extracted by phase-locked loop. The target harmonic current to be suppressed is denoted as .

4. The adaptive harmonic suppression method for an energy storage inverter according to claim 1, characterized in that: In step S3, the LMS adaptive filtering algorithm includes harmonic estimation, error calculation, and weight iteration, with the specific formula as follows: Harmonic estimation: ; Error calculation: ; Weight iteration: ,in This is the iteration step size factor, with a value range of 0 < <1.

5. The adaptive harmonic suppression method for an energy storage inverter according to claim 4, characterized in that: The iteration step size factor It can be dynamically configured according to the inverter load conditions. Under heavy load conditions, the step size is increased to improve the convergence speed, and under light load conditions, the step size is decreased to improve the steady-state compensation accuracy.

6. The adaptive harmonic suppression method for an energy storage inverter according to claim 1, characterized in that: In step S4, the formula for calculating the time-domain PI closed-loop compensation voltage is as follows: ； in This is the proportionality coefficient. The integral coefficient is used to eliminate harmonic compensation steady-state error through integral action.

7. The adaptive harmonic suppression method for an energy storage inverter according to claim 1, characterized in that: In step S5, the final modulation reference voltage calculation formula is as follows: ； By superimposing a reverse harmonic compensation voltage, the harmonic distortion components on the output side are canceled out.

8. The adaptive harmonic suppression method for an energy storage inverter according to claim 1, characterized in that: The method is applicable to the independent power supply of energy storage inverters off-grid, and is suitable for harmonic suppression scenarios of various nonlinear loads such as rectifier loads, switching power supply loads, and frequency conversion loads.

9. An adaptive harmonic suppression device for an energy storage inverter, used to implement the method according to any one of claims 1 to 8, the device comprising: The signal acquisition unit includes a voltage sampling sensor, a current sampling sensor, and a signal conditioning circuit. It is responsible for real-time acquisition of AC voltage and load current analog signals from the inverter output side, completing signal amplification, filtering, and isolation processing, converting high-voltage signals into low-voltage standard signals, and transmitting them to the main control unit to provide raw data for algorithm calculation. The main control and arithmetic unit uses a DSP digital signal controller as its core, and integrates all adaptive harmonic suppression algorithms. It also includes signal preprocessing, fundamental harmonic separation, LMS adaptive filtering, time-domain closed-loop compensation, and amplitude limiting modulation modules. It is the core of the entire device's computation and control, responsible for all data processing, logical judgments, and command output. The power conversion main circuit unit consists of a DC energy storage port, a bus capacitor, IGBT / MOSFET power switches, and an AC output filter circuit. The DC side connects to the energy storage battery module, while the AC side outputs power and connects to a nonlinear load. It receives PWM drive signals from the main control unit to complete DC-AC power conversion and harmonic compensation output. The drive amplifier unit receives the weak PWM pulse signal output by the main control unit, amplifies and electrically isolates it, generates a drive voltage that can drive power devices, and controls the turn-on and turn-off of the power switching transistor. The hardware protection unit integrates overvoltage, overcurrent, overheat, and overmodulation protection circuits, monitors the system's operating status in real time, and immediately blocks the PWM drive signal when harmonic compensation is abnormal or system parameters exceed the threshold, thus protecting the power devices and energy storage system.

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