1929results about "Harmonic reduction arrangement" patented technology

The invention relates to the technical field of transformer harmonic monitoring, in particular to a harmonic detection and early warning system for an intelligent transformer, which obtains voltage and current signals of the transformer in real time, performs frequency domain decomposition by using Fourier transform, extracts multi-dimensional harmonic characteristics such as amplitude, phase, frequency and the like, and performs harmonic detection and early warning on the intelligent transformer. And inputting into a deep learning model to train and generate a dynamic harmonic characteristic model. On the basis, a harmonic wave anomaly classification module analyzes harmonic wave signals in real time, carries out type judgment and position association on abnormal harmonic waves, and generates a report containing anomaly types and positions. Through a dynamic early warning module, a power grid load coefficient is calculated based on power grid load state parameters collected in real time, and a harmonic detection threshold is dynamically adjusted in combination with an initially set amplitude and frequency threshold. The application of the dynamic threshold enhances the adaptability of the system to the load state change, and significantly improves the sensitivity and accuracy of harmonic detection and early warning.

A tracking and adaptive compensation method for power fluctuation of a pulse load of a ship is provided. The method includes: based on a microgrid topology model of the ship, a pulse load model of the pulse load, and an interharmonic power and pulse parameter relationship model, performing power fluctuation tracking, frequency selection and a power spectrum analysis to obtain filtering parameters of a low-pass filter and filtering parameters of a band-pass filter; performing waveform adaptation to eliminate a phase delay caused by the low-pass filter and the band-pass filter, and obtaining a control command for a power compensation strategy; and generating, by a power loop, a pulse width modulation (PWM) signal to control a switching tube in a bidirectional direct current (DC) / DC converter of each of an energy storage battery pack and a supercapacitor of a hybrid energy storage system.

The invention relates to an intelligent power distribution harmonic monitoring and dynamic compensation system which comprises a monitoring unit, a correction unit and a compensation unit. The monitoring unit continuously collects high-frequency harmonic voltage and current data in a distribution line at a high sampling frequency, extracts transient harmonic components through wavelet packet transformation and empirical mode decomposition, and generates low-dimensional feature vectors based on sparse representation. And the correction unit decodes the low-dimensional feature vector, recovers harmonic time-frequency features, calculates a phase drift rate, predicts a harmonic propagation path and an accumulation node by combining real-time power distribution network topology construction and adopting a nonlinear dynamic prediction model, and generates a correction instruction when abnormality is detected. And the compensation unit adopts pulse sequence density modulation to dynamically adjust a compensation current phase according to the correction instruction, and meanwhile, an inductive coupling device is utilized to transfer harmonic energy to a low-risk node, so that harmonic voltage distortion of a target node is quickly recovered to a stable level in a fundamental wave period after early warning.

The invention discloses a sequence impedance remodeling-based grid-forming converter system resonance suppression method and system, and the method comprises the steps: obtaining linearized grid-side voltage, grid-side current and converter-side current small signals based on the active and reactive power control strategy of a grid-forming converter and the voltage and current double-closed-loop control principle; establishing a sequence impedance model of the output impedance of the network construction type converter system based on the virtual synchronous generator; based on the sequence impedance model, combining a passivity theory to determine a system stability condition; in combination with the condition of system stability, an active damping feedback loop is introduced in a voltage control link of the grid-forming converter, equivalent output impedance of converter resonance control is remodeled, a non-passive area for outputting positive and negative sequence impedance is reduced, and grid-connected current harmonic resonance suppression of the grid-forming converter is realized. According to the method, a sequence impedance model is used for performing impedance remodeling of a grid-connected system for the first time, equivalent series virtual damping and a feedback control ring of an equivalent wave trap are specifically introduced into a converter system to perform sequence impedance waveform remodeling, and then the stability and robustness of the system are controlled.

The invention discloses a power supply real-time compensation technology and application based on digital signal processing, and relates to the technical field of power electronics, and the power supply real-time compensation technology comprises a split-phase parallel processing architecture: a three-phase independently configured DSP core, each core integration comprises a real-time harmonic detection module, a dynamic sliding window FFT-RT algorithm is adopted, and the window length is adjustable in a set range; the bandwidth of the self-adaptive variable parameter filter can be dynamically adjusted in a set range; the FPGA coprocessor is specially used for PWM generation; an input stage of the harmonic prediction and decomposition module is synchronously acquired by a multi-source sensor; the processing layer comprises an improved VMD decomposition unit and a variational mode decomposition order; the edge prediction network is used for deploying a lightweight LSTM model, embedding a DSP core and predicting a harmonic spectrum in a future short period; and the multi-target dynamic optimization layer is used for setting a dynamic weight distributor and performing real-time adjustment according to the load sudden change rate. According to the invention, through split-phase parallel architecture, harmonic prediction and dynamic optimization, the response speed, multi-target cooperation and reliability improvement in the field of power supply real-time compensation are realized.

The invention provides a graphene super-capacitor capacity energy-saving control method based on an intelligent algorithm, and the method comprises the steps: obtaining the harmonic content data of a power grid, carrying out the spectrum analysis of the harmonic content through a Fourier transform algorithm, and obtaining the change trend of the harmonic content; acquiring historical capacitor bank impedance characteristic data and a corresponding harmonic content change trend, and calculating impedance matching degrees of the graphene super capacitor under different load conditions; according to the impedance matching degree of the graphene super capacitor, generating a capacitor bank switching sequence by adopting a dynamic programming algorithm, and determining a target switching sequence of the graphene super capacitor; switching of the graphene super capacitor according to the target switching sequence is executed through an edge calculation unit, the access state of the graphene super capacitor is adjusted in real time, and harmonic wave changes of a power grid are dynamically matched; the method comprises the following steps: acquiring transient current data of a system, and decomposing the transient current data by adopting a wavelet transform algorithm to obtain a frequency component of transient current;

The invention relates to the field of electric meter box monitoring, and discloses an anti-electricity-stealing method and system for an intelligent electric meter box, which is used for solving the problem of false alarm caused by harmonic interference when anti-electricity-stealing early warning is carried out, and comprises the following steps: collecting time domain signals of current and voltage in the intelligent electric meter box in a historical detection time period; converting the time domain signal into a frequency domain signal, extracting harmonic information of each harmonic, and establishing a normal harmonic feature model to obtain a target harmonic range; the method comprises the following steps: acquiring time domain signals of current and voltage in an intelligent electric meter box in real time, extracting harmonic information, performing filtering processing according to a target harmonic range, performing first abnormality judgment by using an abnormality detection algorithm, performing multi-parameter joint evaluation if abnormality is judged for the first time, and performing second abnormality judgment according to a multi-parameter joint evaluation result. And electricity larceny early warning is carried out according to the second abnormal judgment result, so that false alarm and missing alarm are effectively reduced, and the adaptability of the system to a complex electricity larceny mode is remarkably enhanced.

According to the harmonic amplification detection method and system of the electric power system, the frequency response of the impedance of the electric power system containing inter-harmonic frequency components is analyzed by obtaining the topological structure and the load distribution condition of the electric power system, and the impedance frequency characteristic scanning is performed on the electric power system at different frequencies by adopting a harmonic injection method; obtaining an impedance frequency response curve; according to the frequency interval of harmonic amplification, the hazard coefficient of the harmonic is evaluated through the voltage distortion rate and the current distortion rate caused by the harmonic, and the type of harmonic source equipment causing harmonic amplification is determined according to the hazard coefficient. According to the scheme, the harmonic source equipment can be detected, the power system can be conveniently maintained in time, and the stability of the power system can be improved.

A system-side harmonic impedance estimation method and apparatus, and a storage medium and an electronic device. The method comprises: acquiring an h-th harmonic parameter equivalent circuit simplified on the basis of power grid characteristics, h being a positive integer greater than or equal to 2 (S1); on the basis of the h-th harmonic parameter equivalent circuit, establishing a system-side harmonic impedance estimation mathematical model (S2); acquiring amplitude and phase data of a harmonic voltage and a harmonic current at a PCC (S3); dividing the amplitude data of the harmonic voltage at the PCC into several stable intervals (S4); on the basis of the amplitude and phase data of the harmonic voltage and the harmonic current in the several stable intervals, establishing a variable coefficient regression model between a harmonic voltage phasor and a harmonic current phasor (S5); selecting an optimal window width of a kernel function of the variable coefficient regression model (S6); and calculating a system harmonic impedance on the basis of the variable coefficient regression model and the optimal window width (S7).

The invention discloses a virtual synchronous generator grid-connected current harmonic suppression method and system, and relates to the technical field of power systems, and the method comprises the steps: S1, carrying out the digital sampling of intermittent high-frequency disturbance through a wind power plant grid-connected current signal in a power grid through an analog-to-digital converter, and obtaining an original digital current sequence; s2, according to the original digital current sequence, analyzing a wind load frequency component by adopting a fast Fourier transform algorithm, and determining amplitude and phase characteristics of a high-frequency harmonic component; s3, if the amplitude of the high-frequency harmonic component exceeds a preset threshold value, extracting an intermittent disturbance harmonic sequence from the frequency component to obtain a to-be-suppressed harmonic subset; according to the virtual synchronous generator grid-connected current harmonic suppression method and system, the stability of a remote wind power plant power grid is remarkably improved, continuous monitoring and real-time suppression of intermittent disturbance are achieved, and high efficiency and reliability of power grid operation are guaranteed.

The invention relates to the technical field of converters, in particular to a multi-module converter resonance suppression method and system for a mobile energy storage system. The dynamic response of the system is optimized through the controller, it can be ensured that the system can keep good stability and performance under different operation conditions, the robustness of the multi-module converter system under different working conditions can be improved through mathematical modeling and accurate design of a control algorithm, and the real-time monitoring and frequency recognition mechanism is adopted, so that the reliability of the multi-module converter system is improved. A control strategy can be adjusted according to frequency characteristics of resonance, active intervention can be performed on the resonance phenomenon of the system by adjusting the on-off state of the converter in real time and a control algorithm, the system can automatically adapt according to different loads, environment conditions and equipment states by adjusting control parameters in real time, long-term stable operation is ensured, and the system is safe and reliable. By actively suppressing resonance and reducing excessive oscillation of the system, energy waste and equipment loss caused by resonance can be significantly reduced.

The invention relates to the technical field of adaptive control, in particular to an electrical automation adjustment method and system, and the method comprises the following steps: obtaining a three-phase current signal, collecting single-cycle high-frequency sampling, extracting an instantaneous extreme point, recording a time coordinate and an amplitude value, calculating a time interval and a change rate, screening the distribution of the extreme point, and obtaining a harmonic distortion characteristic parameter. According to the method, on the basis of high-frequency sampling, instantaneous extreme point extraction, time interval and change rate calculation, harmonic distortion feature description enhancement, extreme value growth rate and phase drift rate are utilized, time periods with prominent fluctuation amplitude are screened, harmonic change trend prediction precision is improved, and the harmonic change trend prediction precision is improved through zero-sequence component and phase offset calculation in combination with periodic change features. The harmonic source is accurately separated, the harmonic cause identification capability is improved, the compensation current is calculated based on the harmonic source, the injection opportunity is optimized, the compensation parameter is adjusted before the harmonic peak value, and the compensation response speed and the matching precision are improved.

The invention provides a harmonic detection method and system for a vehicle network electrical system, and relates to the technical field of harmonic detection, and the harmonic detection method for the vehicle network electrical system comprises the steps: obtaining a current signal of a vehicle network bus, and carrying out the band limit processing of the current signal; constructing a variable window width S transformation kernel function with self-adaptive frequency; based on bispectrum analysis of a third-order cumulant, harmonic phase coupling characteristics are extracted, and an enhanced spectrum is generated through principal component projection; generating a dynamic detection threshold by using a non-harmonic interval background noise model; and carrying out harmonic parameter fitting by adopting an exponential decay model with frequency domain priori constraint. According to the method, through a cascade architecture of adaptive time-frequency analysis, high-order statistical feature extraction, dynamic threshold detection and prior constraint fitting, full-process closed-loop optimization from signal preprocessing to parameter optimization is realized, and the method is particularly suitable for accurate detection of heavy-frequency, nonlinear and time-varying harmonics of a vehicle network system; and a diagnosis basis with higher reliability can be provided for electric energy quality treatment.

The invention relates to the technical field of inverter control, and discloses an inverter output power control method and device, equipment and a storage medium. The method comprises the following steps: performing power frequency fundamental wave extraction and multi-band band-pass filtering on acquired voltage and current sampling data; performing phase compensation, first coordinate transformation and positive and negative sequence decoupling operation on the filtered fundamental wave principal component data; on the basis of a synchronous phase angle and a power grid fundamental wave frequency obtained by positive and negative sequence decoupling operation, carrying out second coordinate transformation, moving average and harmonic power delay difference operation on three-phase current and voltage data of an alpha-beta coordinate system; performing multi-level power calculation, power capacity distribution, error characteristic evaluation and decoupling operation on the inversion fundamental component and the inversion harmonic component subjected to the difference operation; and performing output signal modulation on the inversion power control quantity of the decoupling operation based on the fundamental wave synchronization phase angle, and generating a power control result. According to the invention, the control performance of the inverter on the output power in actual operation is improved.

The invention discloses a secondary ripple optimization method based on star cascade H bridge injection three-time zero sequence voltage. The method comprises the following steps: acquiring real-time voltage and current data of a system, performing dynamic harmonic analysis on the acquired data, generating a harmonic compensation signal, and generating an optimized control signal; constructing a multi-objective optimization model based on the optimized control signal and pre-stored system parameters, solving the model to obtain a Pareto optimal solution set, and selecting an optimal cubic zero-sequence voltage parameter from the Pareto optimal solution set; based on the optimal cubic zero-sequence voltage parameters, constructing a system dynamic model, constructing an adaptive prediction controller, generating an optimal control sequence, and performing closed-loop feedback adjustment; the ripple suppression effect is evaluated, the ripple suppression proportion is calculated by comparing the secondary ripples before and after the third zero-sequence voltage is injected, and the control parameters are dynamically adjusted according to the result. And the adaptability and precision of harmonic analysis are greatly improved. The problem that secondary ripples rise when the star cascade device compensates reactive power is effectively solved.

The invention relates to the technical field of power electronics, in particular to a filter equivalent circuit design simulation system suitable for an energy storage converter, which comprises a main circuit topology unit, a control strategy unit, a parameter optimization and design unit, a simulation engine unit and a performance evaluation unit, wherein the main circuit topology unit is used for building a filter equivalent circuit topology of the energy storage converter and configuring passive element parameters of an inductor, a capacitor and a resistor. According to the method, automatic high-robustness optimization of filter parameters is realized through genetic algorithm-particle swarm hybrid optimization, multi-objective collaborative optimization and digital twinning auxiliary optimization, and a'design-optimization-verification-iteration 'closed loop is formed by combining dynamic working condition evaluation, reliability modeling and artificial intelligence auxiliary analysis, so that the method has the advantages of high robustness and high robustness. The harmonic suppression capability, efficiency and long-term operation reliability of the filter are remarkably improved, the design period is shortened, and the development cost is reduced.

The invention discloses a self-adaptive adjustment method and system for electric energy meter measurement, and relates to the technical field of electric power metering, and the method comprises the steps: building a first measurement mode and a second measurement mode for a target electric energy meter; carrying out load fluctuation monitoring on the target electric energy meter through a load monitoring module, and generating a load fluctuation index; if the load fluctuation index is greater than the preset fluctuation index, activating a first measurement correction module to perform measurement precision adjustment on the target electric energy meter according to a first measurement mode; and if the load fluctuation index is smaller than or equal to the preset fluctuation index, activating a second measurement correction module to perform measurement precision adjustment on the target electric energy meter according to a second measurement mode. The technical problem that the measurement mode cannot be adaptively adjusted according to different loads during measurement of the electric energy meter in the prior art is solved, adaptive adjustment of the measurement of the electric energy meter is realized, and the technical effect of balancing the power consumption and precision of the measurement of the electric energy meter is achieved.

The invention provides a real-time dynamic harmonic detection method and system for a traction power supply system, and relates to the technical field of harmonic detection, and the detection method comprises the following steps: collecting a voltage signal of the traction power supply system in real time, and dynamically tracking fundamental frequency fluctuation through a phase-locked loop technology; dynamically adjusting the data window length of FFT analysis; dynamically adjusting a frequency spectrum calculation kernel of the FFT; carrying out linear compensation on the detected harmonic phase; taking the preliminarily detected harmonic parameter as an initial value, and iteratively updating the harmonic parameter until convergence by minimizing a signal reconstruction error; dynamically adjusting a sampling interval according to the fundamental frequency fluctuation, and carrying out anti-aliasing processing by adopting a filter with a variable cut-off frequency; and constructing a matrix model containing a fundamental frequency fluctuation parameter, and calculating a real harmonic parameter through a least square method. According to the method, the detection defect of the fixed window FFT during frequency fluctuation can be systematically solved, and high-reliability real-time data support is provided for harmonic resonance suppression of the electrified railway.

An adaptive variable step-size LMS filter based on a hyperbolic tangent function and its filtering method and computer equipment belong to the field of filter technology, and solve the problem that the LMS algorithm improved based on a nonlinear function requires too many manual adjustments of parameters and that the convergence speed and convergence accuracy of the traditional LMS algorithm cannot be satisfied simultaneously. The method of the present invention includes: determining the filter tap length and the number of iterations; initializing the filter parameters; obtaining the filter input signal vector; determining the instantaneous expected signal of the filter; obtaining the instantaneous output signal; obtaining the instantaneous error signal of the filter and the accumulated amount of the error signal based on the instantaneous output signal; obtaining the instantaneous step size using a step-size update formula based on a hyperbolic tangent function; and continuously iterating the filter tap weight coefficient vector to construct an LMS filter using the filter tap weight coefficient vector obtained after the number of iterations. The present invention is suitable for improving the performance of the LMS filter, and the filter of the present invention can be widely used in various signal processing fields.

The invention discloses a harmonic traceability method based on a harmonic power direction of an electric power system, which belongs to the technical field of electric power quality of the electric power system and comprises the following steps of: constructing matrixes of fundamental waves and harmonic signals, initializing active and reactive power deviation values of nodes, and adopting a decoupling algorithm combined with a Jacobian matrix iteration method to carry out harmonic traceability. And sequentially calculating the fundamental wave voltage and each harmonic current, and finally obtaining the power flow direction and judging the harmonic source attribute. When harmonic power flows from a load to a power grid, the node is identified as a harmonic source; and when the harmonic power flows to the load from the power grid, identifying the node as a harmonic receiving point. An equivalent circuit model is used for separating harmonic influences of a linear load and a non-linear load, and a real-time monitoring technology is combined to realize dynamic tracking and accurate positioning of a harmonic source. The method is low in calculation complexity, excellent in convergence performance and suitable for a modern power distribution network scene where distributed energy and power electronic equipment are widely connected, the harmonic suppression efficiency is remarkably improved, and the safety and stability of power grid operation are ensured.

The invention discloses a micro-grid electric energy quality global optimization method, which comprises the steps of collecting real-time data, dividing the real-time data into a plurality of segments according to frequency, and calculating harmonic compensation capacity of each frequency band according to the real-time data; according to the harmonic compensation capacity obtained through calculation, priority distribution is carried out on the compensation sequence of the polluted nodes in the micro-grid; the virtual impedance and the injection damping resistance of the inverter are adjusted, and the harmonic current and the resonance phenomenon in the micro-grid are suppressed in different frequency bands; and according to the adjusted virtual impedance and damping resistance, updating a node admittance matrix, monitoring the compensation capacity of the inverter in real time, comparing real-time monitoring data with a threshold value, if the real-time monitoring data exceed the threshold value, correcting the inverter, otherwise, not changing. Through frequency-band-divided control, pertinence and effect of harmonic suppression are improved, frequency-band-divided suppression of micro-grid harmonic and high-frequency resonance is realized, residual capacity of an inverter and harmonic compensation requirements are dynamically matched, and safe and stable operation of a system is ensured.

Aiming at the stability problem caused by harmonic resonance of multiple parallel photovoltaic inverters, the invention provides a parallel inverter micro-grid-oriented adaptive virtual impedance remodeling harmonic resonance suppression method, which comprises a virtual impedance remodeling unit of a grid-connected inverter, a parameter adaptive adjustment unit and a power grid impedance online detection unit. The virtual impedance remodeling unit can improve the output impedance characteristic of the grid-connected inverter and inject a certain damping component into the micro-grid; and the parameter adaptive adjustment unit adaptively adjusts control parameters in the virtual impedance remodeling unit and the current adjustment controller according to the impedance parameters of the power grid so as to maintain the stability of a system control loop. The power grid impedance online detection unit provides power grid equivalent impedance as the input of the parameter adaptive adjustment unit. The three units work cooperatively to form a self-adaptive virtual impedance remodeling multi-inverter micro-grid harmonic resonance suppression strategy, so that the characteristics of a current loop are improved, the inverters can be kept stable under various grid impedance conditions, and the reliability of a multi-inverter micro-grid system is improved.

The invention provides an electric energy quality compensation method and system based on power electronics, and relates to the technical field of power grid dispatching, and the method comprises the steps: collecting the voltage, current, harmonic content, reactive power, three-phase unbalance degree and other real-time multi-mode data of a power grid, and extracting key frequency spectrum features through wavelet transform denoising and windowing interpolation Fourier transform; and constructing a power quality feature vector. A self-adaptive fuzzy logic algorithm and power grid operation parameters are combined, a threshold value of a power quality index is dynamically adjusted, a multi-stage optimization strategy is divided based on the number of standard-exceeding indexes and importance analysis, and a dynamic compensation priority and a compensation strategy are generated. An improved particle swarm optimization algorithm is introduced, an inertia weight is dynamically adjusted, a constraint penalty function is introduced, output parameters of a power electronic compensation device are optimized, and effective compensation of power quality is realized by taking minimization of total active loss as a target.

The invention relates to the technical field of filters, in particular to an internal shielding component of a power filter, which comprises a shell, a cover plate is mounted at the top of the shell through a cross recessed countersunk head screw, and a metal partition plate is arranged on one side of the inner wall of the shell; the wave-proof sleeve is welded on one side wall of the shell, and the material of the wave-proof sleeve is light nickel-plated copper fabric; when the power supply filter is used, the problem that crosstalk coupling is formed between interference signals can be prevented, the electromagnetic compatibility in the signal transmission process between systems is solved, the anti-wave sleeve is adopted for shielding power supply input of the power supply filter, interference of an input cable on other signals is greatly restrained, and the service life of the power supply filter is prolonged. The electromagnetic compatibility problem of the whole system caused by the fact that high-frequency noise is coupled to a power line is prevented, the shielding effectiveness is improved, the problem of filtering post-stage electromagnetic interference signals is greatly restrained, meanwhile, the heat dissipation area is increased, and the heat dissipation efficiency and effect are improved.

The invention relates to the technical field of power monitoring, in particular to an intelligent filtering and trend compensation method and system for power monitoring and a storage medium, and the method comprises the steps: monitoring a current in real time to obtain an original current signal, and carrying out the abnormal data filtering of the original current signal, so as to obtain a normal current signal; smoothing the normal current signal based on a two-state space model to obtain a current decomposition signal; and performing phase compensation on the current decomposition signal based on a signal compensation formula to obtain an actual current signal. Abnormal data filtering is performed on the original current signal in real time, the trend component is extracted in combination with the improved double-state space model, and the differential-integral compensator is designed to counteract the system delay to obtain the accurate actual current signal, so that jitter elimination processing is performed on the current data in real time, and the relatively accurate current change trend is judged at the same time. And misjudgment is eliminated.

The invention relates to the technical field of cable line power distribution network harmonic resonance treatment, in particular to a global and local cooperative partition cooperative resonance suppression method and device. The method comprises the steps of determining a harmonic conductance sensitivity index of each node in a power distribution network according to a target power distribution network admittance matrix parameter, and performing node region division; performing modal analysis on the admittance matrix parameters to obtain modal impedance and participation factors; determining a global optimal virtual admittance instruction value according to the modal impedance, the participation factor and the voltage distortion rate; according to the global optimal virtual admittance instruction value and the voltage distortion rate, determining a regional optimal virtual admittance instruction value in the region; and determining a harmonic compensation current value according to the regional optimal virtual admittance instruction value and the harmonic voltage. According to the method, harmonic suppression is realized for the whole power distribution network by adopting a partition and cooperation mode, and meanwhile, for background harmonic injection change, external interference such as resonance center offset and the like can be effectively overcome, so that the optimal harmonic suppression effect is realized.

The invention discloses a harmonic control method and system of a frequency converter. The method comprises the following steps: acquiring an output voltage signal and a bus voltage signal of the frequency converter in a current time period; performing spectral analysis on the output voltage signal, and constructing a first frequency distribution characteristic curve; correcting the first frequency distribution characteristic curve according to the bus voltage signal to obtain a second frequency distribution characteristic curve; if the output frequency signal of the frequency converter generates frequency drift, tracking the frequency drift of the output frequency signal to obtain a frequency drift rule; performing voltage waveform distortion analysis on the output voltage signal to obtain a total harmonic distortion rate; performing parameter optimization on the filter according to the total harmonic distortion rate and the frequency drift rule, so that the third frequency distribution characteristic of the filter is matched with the second frequency distribution characteristic; in the next time period, the optimized filter is adopted to carry out frequency converter harmonic suppression; the harmonic suppression effect of the frequency converter can be effectively improved, and the power supply quality of a power grid is improved.

The invention relates to the technical field of power systems, in particular to a UPQC harmonic compensation method and system based on repetitive control, and the method comprises the steps: obtaining a load current signal and a voltage signal of a power distribution network, and extracting a harmonic instruction current based on the load current signal; and inputting the harmonic instruction current into a feed-forward channel constructed based on an adaptive filter, and generating a feed-forward control quantity. The phase and frequency of the voltage signal of the power distribution network are tracked in real time through a digital phase-locked loop, the fundamental frequency of the power grid is accurately solved, and the power distribution network can be accurately controlled. The internal model period and the phase lead compensation amount of the frequency adaptive repetitive controller are dynamically calculated, and the internal model structure of the repetitive controller is always matched with the current power grid frequency by updating the two core parameters in real time, so that the compensation precision decline caused by frequency deviation is avoided; and high-precision suppression of the periodic harmonic waves can be realized in a normal fluctuation range of the fundamental wave frequency of the power grid.

Disclosed in the present invention is an NSGA-II algorithm-based parameter optimization method for LCL-type grid-connected inverter filters in a weak power grid, comprising: modeling a single-phase inversion system in a weak power grid, and using inverter side inductance L1, grid side inductance L2, filtering capacitance C and passive damping resistance R as parameters to be optimized; setting boundary constraints for a total inductance value L, the inverter side inductance L1, the grid side inductance L2 and the filtering capacitance C; constructing objective functions of a switching frequency harmonic attenuation ratio η, an inverter end inductor current ripple ΔIripple, a damping resistor power consumption PR_loss and a resonant frequency fr; and on the basis of an NSGA-II algorithm model, using said parameters as decision variables, performing iterative optimization on the plurality of objective functions according to the boundary constraints so as to obtain a parameter solution set of optimal solutions, and selecting a group of typical values from the parameter solution set as optimization solutions. The present invention can significantly improve the filtering effect and the weak grid resistance of filters.

The invention relates to the technical field of electric energy measurement, and provides a power grid side electric energy metering method and device considering inter-harmonic components, and the method comprises the following steps: obtaining voltage data and current data of a power grid side, and extracting a voltage waveform signal and a current waveform signal through constructing a steady-state signal model; based on the obtained waveform signals, fundamental component extraction is carried out, based on a unary linear regression method, the amplitudes and phases of harmonic signals and inter-harmonic signals are compensated, and harmonic components and inter-harmonic components are extracted; based on the obtained fundamental component, each harmonic component and inter-harmonic component of each signal, calculating to obtain fundamental electric energy, harmonic electric energy and inter-harmonic electric energy; and based on the fundamental wave electric energy, the harmonic electric energy and the inter-harmonic electric energy, correcting the measured electric energy of the power grid side. And through steady-state model fitting and a unary linear regression compensation mechanism, the response and adaptability to high-frequency disturbance components are improved.