58 results about "Voltage distortion" patented technology

The invention relates to a harmonic traceability method based on an electric energy quality index monitoring cloud platform, which is realized based on the electric energy quality monitoring cloud platform of an electric power system, and comprises the following steps: S1, selecting an attention node; s2, selecting a harmonic traceability time period; s3, selecting a correlation coefficient calculation item; s4, collecting and processing harmonic data of all feeders of each concerned node, and drawing a voltage distortion rate and harmonic current trend curve contrastive analysis chart of each feeder; and S5, the electric energy quality monitoring cloud platform uses a built-in traceability algorithm to calculate correlation coefficients, screens feeder lines whose correlation coefficients are greater than K, and outputs a harmonic traceability report. According to the invention, one-key positioning and accurate identification are carried out on the system harmonic source based on the electric energy quality monitoring cloud platform by adopting synchronous electric energy quality data of multiple monitoring points according to an advanced correlation traceability algorithm, so that the harmonic traceability accuracy and working efficiency are greatly improved, and the harmonic traceability cost is reduced.

The invention belongs to the technical field of power generation and power supply, and particularly relates to a power distribution network electric energy quality monitoring and comprehensive evaluation method and system, and the method comprises the steps: obtaining an environment reference parameter, three-phase voltage data, three-phase current data, transformer harmonic current and transformer harmonic current times; calculating a transformer voltage distortion rate and a transformer total current which represent the overall level of the electric energy quality; calculating a harmonic erosion index representing the load side harmonic frequency spectrum complexity; calculating a thermal harmonic coupling degree used for judging a high temperature generation reason; calculating a power grid health score; grading the operation state of the power grid; judging the fault type; and issuing adjustment instructions to different fault types. The technical problem that the dynamic coupling relation between the harmonic form and the equipment thermal state cannot be evaluated in the prior art is effectively solved.

The invention discloses a power distribution network harmonic suppression method based on virtual admittance of a photovoltaic grid-connected inverter, and the method comprises the following steps: generating a harmonic compensation current through the photovoltaic grid-connected inverter, constructing a virtual admittance control mechanism based on the harmonic compensation current, and obtaining a mapping relation between a virtual admittance value and a phase angle on the harmonic suppression effect; modeling a photovoltaic grid-connected inverter of the power distribution network, and constructing a virtual admittance regulation mechanism of the power distribution network; and based on a virtual admittance control mechanism, taking each virtual admittance parameter as an optimization variable, and carrying out a multi-photovoltaic grid-connected inverter collaborative optimization strategy to realize graded treatment of power distribution network harmonics. According to the method, a virtual admittance control mechanism is constructed, and a photovoltaic grid-connected inverter is equivalent to earth admittance; and harmonic fractional compensation and global optimization configuration are realized by combining sensitivity analysis of voltage distortion of each node. The problem that the VDAPF only adjusts through harmonic conductance and neglects the impedance characteristic of the power distribution network and the uncertainty of the harmonic phase is solved, and the harmonic compensation capability is remarkably improved.

This application provides a DC boost grid connection method, system, device, equipment, medium, and product, relating to the field of new energy grid connection. The method employs a cascaded topology of H-bridge modules to dynamically adjust the DC voltage output of the photovoltaic array according to the light intensity to match the light conditions. Simultaneously, it dynamically adjusts the number and switching times of the H-bridge modules based on the grid voltage demand, ensuring that the peak value of the multi-level AC voltage output by the adjusted H-bridge module group matches the voltage demand. Furthermore, it actively constrains the harmonic distortion rate and amplitude fluctuation rate of the output voltage to be below preset thresholds. Without requiring a power frequency boost transformer and a large-capacity inverter, it achieves direct boost grid connection from photovoltaic DC to high-voltage AC. It also solves the voltage distortion and amplitude fluctuation problems that easily occur during the dynamic adjustment of the number of modules, improving grid-connected power quality and system operational stability, and reducing the cost of the photovoltaic DC boost grid connection system.

The present application belongs to the field of power electronics technology, and specifically discloses a voltage compensation method and device for a cascaded multi-level inverter. In the present application, the predicted value of the output current of each H-bridge inverter module in the cascaded multi-level inverter is used to compensate the turn-on angle and turn-off angle of each H-bridge inverter module respectively, and the phase shift control signal of each switching device in the H-bridge inverter module is distributed according to the compensated turn-on angle and turn-off angle, thereby effectively compensating for the PWM voltage distortion caused by the dead zone effect and the switch parasitic capacitance effect. In addition, the present application does not need to detect the output current of the H-bridge inverter module, eliminating the current detection hardware and optical fiber communication delay time. In the high-frequency cascade topology, the low-order harmonics introduced by the dead zone effect and the switch parasitic capacitance effect can be effectively suppressed, significantly improving the waveform quality.

This invention discloses a predictive maintenance system for medical X-ray equipment, belonging to the field of medical equipment maintenance technology. It includes a multi-source data acquisition module, a feature construction module, a coupled degradation modeling module, a risk assessment module, and a maintenance strategy generation module. Based on voltage distortion rate, current harmonic components, and temperature field gradient, this invention extracts the standard deviation of voltage distortion rate, the total distortion coefficient of current harmonics, and the rate of change of temperature gradient after denoising using wavelet thresholding, and fuses them into a feature vector. Combining a long short-term memory network and a Bayesian network, it calculates a comprehensive degradation index of multi-parameter coupling; subsequently, it constructs a multi-parameter feature space and outputs a comprehensive risk level through unsupervised learning methods; finally, it generates targeted maintenance strategies based on the risk level and optimization algorithms. This invention achieves accurate prediction and intelligent maintenance of medical X-ray equipment faults, reduces sudden failures, lowers maintenance costs, and improves equipment operational reliability and diagnostic and treatment safety.

The invention discloses a medical X-ray equipment fault predictive maintenance system, and relates to the technical field of medical equipment maintenance. Comprising a multi-source data acquisition module, a feature construction module, a coupling degradation modeling module, a risk judgment module and a maintenance strategy generation module. The method comprises the following steps: based on a voltage distortion rate, a current harmonic component and a temperature field gradient, extracting a voltage distortion rate standard deviation, a current harmonic total distortion coefficient and a temperature gradient change rate after de-noising through a wavelet threshold method, and fusing into a feature vector; calculating a multi-parameter coupled comprehensive degradation index in combination with a long short-term memory network and a Bayesian network; then constructing a multi-parameter feature space, and outputting a comprehensive risk level through an unsupervised learning method; and finally, a targeted maintenance strategy is generated based on the risk level and an optimization algorithm. According to the invention, accurate prediction and intelligent maintenance of faults of the medical X-ray equipment are realized, sudden faults are reduced, the maintenance cost is reduced, and the operation reliability and diagnosis and treatment safety of the equipment are improved.

This invention belongs to the field of power generation and supply technology, specifically relating to a method and system for monitoring and comprehensively evaluating the power quality of distribution networks. The method includes: obtaining environmental reference parameters, three-phase voltage data, three-phase current data, transformer harmonic current, and transformer harmonic current order; calculating the transformer voltage distortion rate and total transformer current, which characterize the overall power quality level; calculating the harmonic erosion index, which characterizes the complexity of the harmonic spectrum on the load side; calculating the thermal harmonic coupling degree used to determine the cause of high temperatures; calculating the grid health score; classifying the grid operating status into levels; determining the fault type; and issuing adjustment commands for different fault types. This invention effectively solves the technical problem that existing technologies cannot assess the dynamic coupling relationship between harmonic morphology and equipment thermal state.

The invention relates to the technical field of three-phase systems, and provides a three-phase voltage state estimation method and system based on virtual coordinates, and the method comprises the steps: calculating the voltage peak value of each phase for three-phase voltages, and determining that a phase is open if the peak voltage of a certain phase is lower than a threshold value in the three peak voltages; for three-phase voltage, virtual beta-axis voltage is generated through an all-pass filter, actual beta-axis voltage is obtained through Clark transformation, the product of the virtual beta-axis voltage and the actual beta-axis voltage serves as an evaluation function, and a positive sequence and a negative sequence are distinguished according to the positive and negative of the evaluation function. The system state can be accurately and effectively judged under the conditions of three-phase imbalance and voltage distortion, the anti-noise capability and the anti-harmonic interference capability are high, and safe and stable operation of equipment under the abnormal condition is ensured.

The invention relates to the technical field of anomaly detection, in particular to a substation equipment anomaly detection method based on deep learning. Comprising the following steps: determining whether the operation of a single secondary device is qualified based on a voltage distortion rate, marking the unqualified secondary device as an abnormal device, and determining whether the operation of the secondary device is qualified based on a frequency deviation for the secondary device whose voltage distortion rate is greater than a second preset voltage distortion rate and less than or equal to a first preset voltage distortion rate, unqualified secondary equipment is marked as abnormal equipment, and the secondary equipment is a relay protection device; based on the disqualification ratio, determining that the reason for disqualification of the test process is preset matching degree abnormity or secondary equipment detection abnormity; adjustment is correspondingly carried out according to reasons for disqualification of the test process; according to the invention, the equipment abnormity detection efficiency is effectively improved.

1. The name of the design product: active filter. 2. The use of the design product: for inhibiting AC voltage distortion and current harmonics. 3. The design points of the design product: in shape. 4. The picture or photo that best shows the design points: design 1 perspective view 1. 5. Design 1 is designated as the basic design.

The invention is suitable for the technical field of electric energy metering, and relates to an electric energy metering method and device of an electric energy meter. Corresponding fundamental wave voltage current components, harmonic wave voltage current components, corresponding fundamental wave phase angles and harmonic wave phase angles are extracted, and based on the data, fundamental wave positive sequence active power, reactive power, non-fundamental wave equivalent apparent power, voltage distortion power, current distortion power, harmonic wave apparent power, unbalanced apparent power and the like are obtained through calculation; various electric parameters of the electric energy meter are metered so as to guide an electric power department to charge, make economic decisions, measure main harmonic pollution sources and the like, and the quality of electric power service is greatly improved.

The utility model discloses a kind of electric energy quality DNV voltage distortion rate elimination stabilizer and sampling circuit, including load equipment and for the DVA voltage stabilizer on the load equipment, still including with the DVA voltage stabilizer and the load equipment electric connection A circuit, B circuit, C circuit and N circuit.The beneficial effect of the utility model is: through filter current transformer, voltage stabilizer current transformer and DVA voltage stabilizer, realize the process in the use of load equipment, inhibit load equipment dynamic and steady-state voltage drop and voltage variable, eliminate surge, eliminate voltage flicker, with good dynamic voltage stability capacity, output voltage reaches precision ±1% -5% adjustable, can effectively filter each harmonic, three-phase unbalance, improve power factor, improve power supply electric energy quality, and harmonic elimination stabilizer has ideal energy-saving effect, between 1-8% in different field energy-saving effect.

The present application provides a capacitance compensation method and device for withstand voltage and partial discharge testing of ultra-high voltage shunt reactors, belonging to the field of reactor capacitance compensation. The method includes obtaining the inherent capacitance parameters of the winding, separating the high-frequency and low-frequency components, analyzing the spatial coupling path, calculating the temperature and humidity-induced capacitance offset, generating a collaborative capacitance parameter matrix after weighted fusion, introducing a nonlinear polarization attenuation factor and dynamically calibrating it, establishing a capacitance compensation benchmark model, and performing compensation through a multi-stage compensation device. Through dynamic modeling, the present application accurately compensates capacitance, suppresses voltage distortion, and improves the sensitivity of partial discharge detection, solving the problems of insufficient accuracy and poor adaptability of traditional compensation.

The embodiment of the invention provides a direct-current boost grid connection method, system, device, equipment, medium and product, and relates to the field of new energy grid connection, the method adopts an H-bridge module group cascade topology structure to dynamically adjust the direct-current voltage output by a photovoltaic array according to the illumination intensity so as to enable the direct-current voltage to be matched with the illumination condition, and the direct-current boost grid connection is realized. Meanwhile, the input number and the switching time of the H-bridge modules are dynamically adjusted according to the voltage requirement of the power grid, so that the multi-level alternating-current voltage peak value output by the adjusted H-bridge module group is matched with the voltage requirement, and the harmonic distortion rate and the amplitude fluctuation rate of the output voltage are actively restrained to be lower than preset threshold values; on the premise that a power frequency boosting transformer and a large-capacity inverter do not need to be configured, direct boosting grid connection from photovoltaic direct current to high-voltage alternating current is achieved, meanwhile, the problems of voltage distortion and amplitude fluctuation which are prone to occurring in the dynamic adjustment process of the number of modules are solved, the grid-connected electric energy quality and the system operation stability are improved, and the system reliability is improved. And the cost of the photovoltaic direct-current boost grid-connected system is reduced.

The invention provides an SVG self-synchronization control system and method based on active disturbance rejection control. The system comprises an active power reference value calculation module, a power calculation module, an active power synchronization loop module, a reactive power-AC voltage outer loop module, a positive sequence current component control loop module, a negative sequence current component control loop module and a pulse generation module. By adopting modules such as an active power synchronous ring for active disturbance rejection control, internal and external disturbances under complex working conditions such as power grid faults and voltage distortion are effectively suppressed, and the stability and dynamic response performance of the system in a transient process are improved. The synchronization performance of the SVG under the fault working condition can be improved, and the safety and stability of a power grid are improved.

This invention relates to the field of motor control technology, particularly to applications requiring low vibration and high efficiency in underwater propulsion motors. Specifically, it provides a method for suppressing low-order harmonic torque and high-frequency harmonic current in underwater propulsion motors. This invention switches control modes according to changes in the motor's operating frequency, meeting not only the low-noise requirements for low-speed navigation but also improving controller efficiency for high-speed navigation. When the underwater propulsion motor operates at low speed, harmonic compensation of the line current suppresses low-order harmonics generated by the motor body and controller, thereby reducing electromagnetic force pulsation caused by harmonics. Furthermore, by significantly increasing the switching frequency using silicon carbide power devices, it suppresses phase voltage distortion caused by pulse width modulation technology, improves the sinusoidal nature of the output voltage, and reduces harmonic torque. When the underwater propulsion motor operates at high speed, the output current is large; by reducing the switching frequency, the switching losses of the power devices are reduced, improving the efficiency of the controller in the propulsion system.

The invention discloses a self-adaptive dead zone compensation method for a servo driver. The method comprises the following steps: step 1, building a motor three-phase current acquisition circuit and acquiring three-phase current in real time; step 2, current polarity discrimination based on hysteresis comparison; 3, reconstructing a dead-zone voltage error vector in real time; 4, dynamically adjusting the self-adaptive compensation coefficient; 5, direct correction and compensation injection of a PWM duty ratio instruction are carried out; and step 6, loop iterative optimization and full-working-condition real-time compensation are carried out. The method has the advantages that the non-ideal voltage deviation caused by the inherent switching dead time of the voltage source type inverter is accurately offset. The dead-zone effect comes from physical characteristics of power electronic devices, and aims to prevent straight-through short circuit of power tubes of upper and lower bridge arms of an inverter and unexpected voltage distortion of motor end voltage in an actual process. The objective of the invention is to recover the ideal waveform of the motor terminal voltage and improve the current tracking precision, the torque stability and the low-speed performance.

This invention provides a method and apparatus for selecting the location of an active harmonic mitigation device for radial distribution networks, belonging to the field of power quality management technology. The method includes: acquiring equipment parameters of each branch of the distribution network; determining the harmonic impedance of each branch based on the equipment parameters, and calculating the influence coefficient of each nonlinear load branch's harmonics on the distribution network's harmonic voltage; calculating the contribution rate of each nonlinear load branch's harmonics to the voltage distortion of the distribution network based on the influence coefficients of all nonlinear load branches; determining the numerical distribution characteristics of the voltage distortion contribution rate corresponding to all nonlinear load branches based on the coefficient of variation and a threshold; and determining the optimal location of the active harmonic mitigation device based on the numerical distribution characteristics, the expected minimum target for harmonic mitigation, and the voltage distortion contribution rate corresponding to each nonlinear load branch. This invention can solve the problem of difficult location selection for harmonic mitigation devices in radial distribution networks where harmonic sources are dispersed.

The invention provides a reactive compensation control method and device, electronic equipment and a storage medium, and the method comprises the steps: obtaining voltage data, current data and temperature data of a target three-phase power grid, and carrying out the data preprocessing of the voltage data and the current data; reactive power, total harmonic distortion of voltage and total harmonic distortion of current are calculated according to the preprocessed voltage data and the preprocessed current data; if a first comparison result of the preprocessed voltage data and the preset voltage, a second comparison result of the preprocessed current data and the preset current, a third comparison result of the total harmonic distortion of the voltage and the preset voltage distortion, and a fourth comparison result of the total harmonic distortion of the current and the preset current distortion, the current distortion is detected; if it is determined that the reactive compensation process is normal according to the temperature data and a fifth comparison result of the temperature data and the preset temperature, current capacitor switching is controlled according to reactive power, and reactive compensation is carried out on the target three-phase power grid; through the method, a more practical reactive compensation control method is provided.

The present application relates to a kind of based on ultra-wide spectrum absorber electric pollution processing method, system and terminal, it relates to electric pollution processing technical field, its method includes: obtaining the voltage signal of equipment needing protection and equipment position point;Based on equipment position point, call equipment model;According to voltage signal and equipment model, analysis determines voltage distortion rate;According to voltage distortion rate and equipment model analysis, select initial specification is determined;According to equipment position point analysis, determine specification adjustment information;Based on specification adjustment information, to select initial specification is adjusted to form selected final specification, and the ultra-wide spectrum absorber corresponding to selected final specification is installed to equipment needing protection to carry out electric pollution processing.The present application has the effect of improving the protection ability of equipment.

The invention relates to a cable insulation fault positioning method and system, and the method comprises the following steps: collecting a three-phase voltage traveling wave signal when a cable has a single-phase insulation damage grounding fault, and carrying out the signal decoupling, and obtaining an independent line mode component and a zero mode component; a Db45 wavelet basis is used as a mother wavelet, multi-scale wavelet decomposition and reconstruction are carried out on the decoupled line mode component so as to extract fault traveling wave head features, and the number of layers of multi-scale wavelet decomposition is determined according to the sampling frequency and the power grid fundamental wave frequency; and according to a wavelet reconstruction result, detecting the moment when a fault traveling wave head arrives at monitoring points at two ends of the line, thereby calculating the distance from a fault point to one end of the line. Compared with the prior art, the method has the advantages that inter-phase coupling interference is eliminated through phase-mode transformation, and serious voltage distortion and harmonic interference in a power grid are effectively suppressed by using the excellent time-frequency localization characteristic of the Db45 wavelet basis, so that the accuracy and reliability of cable insulation fault positioning are greatly improved.

The invention discloses a three-phase four-bridge-arm inverter control method and device based on multi-quasi-PR parallel resonance, terminal equipment and a storage medium, and relates to the field of inverter control, and the method comprises the steps: carrying out the proportional scaling of a three-phase voltage error of a three-phase load voltage and a three-phase reference voltage, obtaining a proportional control signal, and carrying out the control of the proportional control signal; carrying out resonance gain amplification on the fundamental wave, the first harmonic wave and the second harmonic wave to obtain corresponding resonance control signals, and carrying out parallel superposition to obtain a current inner loop reference value; determining a three-phase bridge arm output voltage according to the deviation between the current inner ring reference value and the three-phase inductive current in combination with the compensation of the three-phase load current; and according to the three-phase bridge arm output voltage, determining a neutral line bridge arm voltage, further generating a switch control pulse signal of a bridge arm, and controlling the three-phase four-bridge arm inverter. Through the implementation of the invention, the problem of output voltage distortion caused by the fact that PI control is difficult to adapt to a nonlinear load in the prior art is solved, and the output voltage distortion rate under the nonlinear load is reduced.

The present invention discloses a voltage control method, device, and storage medium based on a DC distribution mode, applicable to a low-voltage, two-terminal AC / DC power distribution system. The method comprises: transforming the three-phase unbalanced voltage in the low-voltage, two-terminal AC / DC power distribution system into a two-phase synchronous rotating coordinate system using positive-sequence rotating coordinates and negative-sequence rotating coordinates; transforming the positive-sequence fundamental AC voltage and the negative-sequence fundamental AC voltage in the three-phase stationary coordinate system into a DC voltage; and transforming the positive-sequence fundamental AC voltage and the negative-sequence fundamental AC voltage into a second harmonic voltage; filtering out several subharmonic voltages in the two-phase coordinate system to obtain positive-sequence fundamental output voltage components and negative-sequence fundamental output voltage components; and regulating the positive-sequence fundamental output voltage components and the negative-sequence fundamental output voltage components based on classical theory to eliminate voltage distortion in a receiving-end converter in the low-voltage, two-terminal AC / DC power distribution system under unbalanced load. Embodiments of the present invention can effectively improve voltage control effectiveness.

The invention relates to a transformer substation grid-connected line ferromagnetic resonance suppression method and system, and relates to the technical field of transformer substations, and the method comprises the following steps: real-time monitoring: monitoring the electrical parameters of a transformer substation grid-connected line in real time, including voltage, current and frequency; data analysis: judging whether ferromagnetic resonance characteristics exist or not through a data analysis algorithm, wherein the characteristics comprise voltage distortion and current fluctuation; if ferromagnetic resonance characteristics are detected, the intelligent regulation and control module is automatically started; and intelligent regulation and control: the intelligent regulation and control module dynamically adjusts the switching state of the compensation reactor and the capacitor bank according to the real-time data of the power grid so as to change the resonance condition of the system and suppress the resonance. The system has the advantages that data are read through real-time monitoring, the intelligent regulation and control module is automatically started or closed after analysis, the resonance condition of the system is changed, accordingly resonance is restrained, and if the expected effect is not achieved through adjustment, the adjustment strategy is automatically switched until the resonance is effectively restrained.

This invention provides a low-capacitance MMDTC-STATCOM control method based on carrier reconstruction, relating to the field of power electronic converter control, which can simultaneously solve the problems of output voltage distortion and submodule capacitor voltage balance. The method includes: determining the capacitor voltage difference Δu of the submodule in the next sampling period k+1. c (k+1); based on the capacitor voltage reference value u c * DC component U dc * AC component Δu c_ac (k+1), carrier period T c Determine the carrier u after the first carrier reconstruction. carry_1 This is used to eliminate the influence of capacitor voltage ripple on the output voltage; based on the carrier u after the first carrier reconstruction. carry_1 capacitor voltage reference value u c * DC component U dc * Error proportionality coefficient ρ, and the direction of the bridge arm current sign(i) at time k+1. arm (k+1)), determine the carrier u after the second carrier reconstruction. carry_2 This is used to achieve capacitor voltage balancing in submodules; based on u carry_1 and u carry_2 Determine the carrier u after two reconstructions carry It is used for PWM modulation of each submodule.

The invention discloses a potential energy recovery system and method for a ship unloader of a coal wharf, and relates to the technical field of energy-saving technologies of large loading and unloading equipment of coal ports, and the system comprises a multi-motor cooperation module, a central electric energy conversion module, a system main control unit and a hybrid energy storage system. The method comprises the steps of multi-motor cooperative power generation and priority division, electric energy preprocessing and input, direct current bus voltage stabilization and power grid state perception, reactive compensation and harmonic filtering, energy scheduling and path selection, hybrid energy storage system hierarchical control and the like. Through the technical scheme of combining multi-motor cooperative control, power grid state real-time sensing and intelligent compensation, the problems of multi-motor energy scheduling imbalance, power grid voltage distortion and the like are effectively solved, and efficient recovery and safe utilization of potential energy of the ship unloader are achieved.

The invention discloses an SOGI parameter self-tuning SiC motor speed-sensorless control method, and aims to solve the problems of fixed injection frequency and SOGI parameter mismatch in the prior art. The method comprises five links of working condition identification and injection frequency dynamic switching, SOGI parameter adaptive tuning, dead zone time cooperative compensation, rotor position estimation and error feedback and system integration optimization. Working conditions are divided through two-dimensional fuzzy clustering, differential injection frequencies are adapted, SOGI parameter self-tuning is achieved by combining fuzzy control and PI adjustment, a dead-time voltage distortion model is established, cooperative compensation is carried out, and rotor position estimation precision is improved by adopting a weighted fusion algorithm. According to the method, the sixth harmonic suppression rate can be increased to 95% or above, the rotating speed estimation error is reduced to be within 10 r / min, the full-working-condition adaptability and stability of the system are enhanced, engineering practicability is achieved, and the method is suitable for the fields of industrial transmission, new energy power generation and the like.

The present application relates to the technical field of grid voltage phase signal detection and extraction, in particular to a synchronous phase-locked loop with a combined filter structure. In view of the technical problem that the conventional phase-locked loop is easily affected by voltage distortion and cannot realize accurate phase locking under severe grid conditions, the present application proposes a synchronous phase-locked loop solution based on a combined filter architecture. In order to improve the anti-interference stability of the phase-locked loop, the present application first designs an enhanced fourth-order generalized integrator with a direct current offset voltage elimination function, and builds a double-enhanced fourth-order generalized integrator structure based on it. At the same time, a first-order comb filter capable of effectively suppressing grid harmonic disturbance is introduced, and the two are cascaded to form a combined filter and integrated into a three-phase grid-connected phase-locked loop system, finally realizing the rapid and accurate extraction of grid phase information under severe grid conditions. The present application is mainly applied to the synchronous control process of grid-connected converters in complex grid environments.

This invention relates to the field of microgrid control technology, and discloses a distributed harmonic control method, device, and multi-inverter system for multi-inverter systems. In this invention, adjacent inverter control units are connected to form a ring network. During harmonic control, the output voltage and output current of the inverter in the inverter control unit are used to separate the fundamental and harmonic components. Based on the obtained fundamental component, the fundamental component of the outer loop reference voltage is calculated. The harmonic power is calculated based on the harmonic current component. Combined with the harmonic power of other interconnected units, a harmonic power sharing controller is calculated to determine the harmonic voltage gain coefficient. Based on this coefficient and the harmonic current component, the harmonic component of the outer loop reference voltage is obtained. The outer loop reference voltage is then calculated, and the control voltage for the corresponding three-phase inverter bridge is obtained from this reference voltage. This invention is unaffected by grid interference and feeder impedance mismatch, compensates for voltage distortion caused by nonlinear loads, and achieves precise harmonic power distribution between the DG (Distributed Generator and Controller).