166 results about "Harmonic voltages" patented technology

The invention discloses a new energy power grid probability harmonic load flow calculation method based on improved semi-invariant and Gram-Charlier series expansion. The new energy power grid probability harmonic load flow calculation method comprises the following steps: establishing a random variable probability model, a wind-light output model and a wind-light joint distribution model; secondly, considering the output correlation between wind and light fields, converting the wind and light combined distribution model based on a Copula function into independent variables by utilizing Rosenblatt conversion for calculation, then calculating each-order semi-invariant of load, photovoltaic output and wind power output according to the expected values of node voltage and branch power flow and a sensitivity matrix, and finally calculating the output correlation between the wind and light fields according to each order semi-invariant of the load, the photovoltaic output and the wind power output. The method comprises the following steps of: obtaining a state variable, further solving each-order semi-invariant form of the state variable and the branch power flow, and finally, obtaining a probability density function and a probability distribution function of harmonic voltage of each node by combining Gram-Charlier series expansion.

This invention discloses a method and system for suppressing capacitor voltage fluctuations in SiC MMC submodules, belonging to the field of electronic power technology. Based on the analysis results of the optimal broadband harmonic circulating current injection boundary and order for SiC MMC submodules, an optimized model for submodule capacitor voltage fluctuations is determined that simultaneously injects 2nd, 4th, and 8th harmonic circulating currents and 3rd harmonic voltages, which can fully utilize the higher control bandwidth characteristic of SiC MMC. By solving the optimized model for submodule capacitor voltage fluctuations, the amplitude and phase of the reference values ​​of the 2nd, 4th, and 8th harmonic circulating currents to be injected, as well as the amplitude and phase of the corresponding 3rd harmonic voltage, are determined. Then, by injecting 2nd, 4th, and 8th harmonic circulating currents and jointly injecting the 3rd harmonic voltage, broadband harmonic joint injection is achieved, reducing the capacitor voltage fluctuations of the submodule and realizing a method for suppressing capacitor voltage fluctuations in SiC MMC submodules with high suppression effect.

The invention belongs to the technical field of power electronics, and provides a method and a system for improving harmonic transient stability of a grid-forming type active power filter, droop control is performed on a deviation value of an active power reference instruction and an actually measured active power value, integration is performed to obtain a power angle, and the power angle and a grid-side harmonic phase are added to generate a harmonic voltage phase instruction; pI control is carried out on a deviation value between the reactive power reference instruction and an actually measured reactive power value to obtain a voltage deviation value, and the voltage deviation value and a network side specified subharmonic voltage amplitude are summed to generate a harmonic voltage amplitude instruction; taking a harmonic voltage amplitude instruction as a d-axis reference, taking 0 as a q-axis reference, respectively subtracting the d-axis reference and the q-axis reference from the harmonic voltage on the d-axis and the q-axis to obtain deviation values, and obtaining a dq component of the harmonic voltage reference through PI control. The operation safety of the power grid can be improved.

The invention discloses a specific grid-connected current harmonic suppression method and device for an energy storage converter, and belongs to the technical field of power systems, and the method comprises the steps: obtaining a given current value of a fundamental current loop, and carrying out the dq / abc conversion to obtain a three-phase current reference value; acquiring a three-phase current value of a power grid side, and subtracting the three-phase current value from the three-phase current reference value to obtain a harmonic current value; converting the harmonic current value to a target subharmonic synchronous rotating coordinate system to obtain a target subharmonic current value; extracting the target sub-harmonic current value in a direct current form through a low-pass filter, and sending the target sub-harmonic current value to a PI regulator for regulation to obtain a harmonic voltage compensation amount; and injecting the harmonic voltage compensation amount into a modulation wave to realize suppression of the target subharmonic current. According to the invention, the grid-connected side current harmonic of the energy storage converter can be effectively suppressed, and the grid-side current quality is improved.

The invention discloses an electric power system harmonic propagation analysis method and device and a storage medium, and belongs to the technical field of electric power system harmonic analysis, and the method comprises the steps: inputting a to-be-predicted operation condition parameter and a harmonic voltage parameter into a trained regression prediction model, obtaining a corresponding prediction cross admittance matrix, and obtaining a prediction cross admittance matrix; the predicted cross admittance matrix is applied to harmonic propagation analysis of the power system; wherein the regression prediction model is integrated with Bagging based on a decision tree; according to the method, by improving the data set quality and optimizing the model hyper-parameters, the harmonic source cross admittance matrix which is self-adaptive to the operation condition and is established by adopting the decision tree-based regression device and the Bagging element regression device can meet the harmonic analysis precision requirements under different operation conditions, and harmonic propagation of the power system can be analyzed more accurately; the analysis efficiency is improved, and a feasible technical path is provided for online monitoring or rapid evaluation.

The invention discloses a harmonic suppression method and system based on feedforward control and virtual impedance, and belongs to the field of electric energy quality control, and the method comprises the steps: constructing a harmonic extraction model based on the cascading of double third-order generalized integrators, and obtaining a voltage harmonic component based on the harmonic extraction model and real-time power grid data; based on a preset power outer loop control strategy, a preset voltage and current double closed loop control strategy, a preset harmonic voltage feed-forward control strategy and the voltage harmonic component, constructing a network construction type charging pile control model, and obtaining an initial output current; obtaining each virtual impedance based on the initial output current, the harmonic extraction model and the voltage harmonic component; and obtaining a harmonic suppression model based on each virtual impedance and the network construction type charging pile control model, so as to obtain a harmonic suppression output current based on the harmonic suppression model and the real-time power grid data. According to the harmonic suppression method and system based on feedforward control and virtual impedance provided by the invention, grid-connected output current harmonics controlled by a network-forming type charging pile are effectively suppressed.

The invention discloses a harmonic analysis method, system and device for a flexible direct current converter and a medium, and relates to the technical field of flexible direct current transmission, and the method comprises the steps: obtaining key electrical parameters of a to-be-tested flexible direct current converter; constructing a high-frequency equivalent circuit corresponding to each target device according to the key electrical parameters; calculating a harmonic voltage component of a single bridge arm of a converter valve in the to-be-tested flexible DC converter according to the key electrical parameters so as to generate a harmonic voltage source; integrating the high-frequency equivalent circuit and the harmonic voltage source into simulation software for transient simulation; and determining harmonic voltage distribution and harmonic current distribution of the to-be-tested flexible direct current converter according to the simulation result, thereby effectively avoiding the equipment operation risk and reducing the fault rate of the flexible power transmission equipment.

The application provides a new energy grid-connected system harmonic risk evaluation method, comprising the following steps: calculating the grid-connected point harmonic voltage of the new energy grid-connected system and the key outgoing line harmonic current after setting the background harmonic through the harmonic node voltage equation; obtaining the harmonic voltage constraint of the grid-connected point and the harmonic current constraint of the key outgoing line; calculating the first deviation factor according to the grid-connected point harmonic voltage and the harmonic voltage constraint, calculating the second deviation factor according to the key outgoing line harmonic current and the harmonic current constraint, and comparing to obtain the maximum value of the deviation factor; calculating the harmonic risk comprehensive evaluation index according to the maximum value of the deviation factor and the harmonic weight factor actual value and judging the harmonic risk of the current operation condition of the new energy grid-connected system. The evaluation method provided by the application can effectively measure the harmonic risk degree under different operation conditions, draw the safe operation area and the risk operation area, and guarantee the safe and stable operation of the new energy grid-connected system.

The invention provides a power distribution network resonance key element identification method and device based on harmonic monitoring data, and the method comprises the steps: collecting the harmonic voltage and branch harmonic current data of a key node through the deployment of an online harmonic monitoring device, converting a time domain signal to a frequency domain through band-pass filtering for a preset harmonic number set, and extracting a complex amplitude value, carrying out normalization processing to obtain standardized data; secondly, constructing a node admittance matrix in a frequency domain in combination with the newest power grid topology and equipment static parameters, identifying a feature root closest to zero and a corresponding resonant frequency thereof through eigenvalue decomposition, and obtaining a modal vector; tiny disturbance is applied to inductive reactance / capacitive reactance element parameters, and the sensitivity of the inductive reactance / capacitive reactance element parameters to modal admittance is calculated and normalized into dimensionless indexes; and screening and sorting according to the sensitivity threshold, and outputting a group of resonance key elements. The method does not need off-line simulation, has the advantages of high real-time performance, high engineering adaptability, low implementation cost and the like, and provides efficient technical support for active treatment of harmonic waves of the power distribution network.

The invention discloses a broadband harmonic voltage measuring system and method based on an improved CVT, and the system comprises a first current sensor which is used for measuring the first current of a high-voltage capacitor of the CVT; the broadband harmonic wave acquisition device is used for sampling the first current to obtain first current sampling data; and the broadband harmonic analysis device is used for determining an amplitude frequency spectrum of the first current based on the first current sampling data and determining each frequency component of the system voltage based on the amplitude frequency spectrum of the first current. On the basis of a large number of CVTs used in a power system, the broadband harmonic voltage measurement function within the range of hundreds of kHz is achieved by improving the CVT, the original power frequency measurement function of the CVT is not changed, the operation reliability of the CVT is not reduced, and effective broadband, high-precision and low-cost harmonic voltage measurement can be achieved.

A voltage-controlled bridge is coupled to the line voltage and the transformer primary harmonic voltage, while a current-controlled bridge is coupled to the line current and the transformer secondary harmonic voltage. A synchronous average harmonic current compensator synchronously integrates the error between the measured bridge current and the command current every half-switch cycle and samples the compensator output to control the line current and linearize the harmonic coupling between the isolation bridges. A synchronous pulse-width modulation process tracks the commanded line voltage. One or more of the primary and secondary harmonic command circuits regulate the harmonic coupling voltages of the voltage-controlled and current-controlled bridges, respectively. The line voltage, line current, and primary and secondary harmonic commands provide generalized line and isolation voltage bus regulation freedom within a single stage.

The invention discloses a permanent magnet synchronous motor high-frequency mode identification method based on common-mode voltage injection, and the method comprises the steps: calculating a sideband common-mode voltage injection range and a sideband harmonic voltage frequency component under the injection according to a sideband harmonic voltage model; a sideband harmonic current frequency component with the maximum amplitude after injection is calculated within the common-mode voltage injection range, and an electromagnetic force wave generated by the sideband harmonic current under the condition serves as a vibration excitation source; increasing the switching frequency according to a specific step length, and carrying out a frequency sweeping experiment; and analyzing the collected data, and correcting a frequency response curve according to a high-frequency electromagnetic force calculation function to obtain modal parameters of the motor. According to the method, the common-mode voltage which has no influence on the fundamental frequency current is injected into the closed-winding permanent magnet synchronous motor, and the sideband harmonic current component with the maximum amplitude after injection is selected as the vibration excitation source for frequency sweeping, so that the identification of the high-frequency mode of the motor is effectively realized. The method can be widely applied to the field of motor mode identification.

The application provides a harmonic source modeling method based on time-frequency feature extraction, first determines harmonic principal component frequencies of a harmonic source; then extracts harmonic voltage amplitude and phase angle corresponding to the harmonic principal component frequencies of the harmonic source, obtains a frequency domain feature set of the harmonic source, reconstructs the frequency domain feature set through IDFT to form a harmonic source frequency domain feature component matrix, and splices the frequency domain feature component matrix with an original voltage sequence collected by a synchronous phasor measurement device to obtain a time-frequency feature component matrix; the component matrix is converted into a gray scale image by using a matrix normalization method, and is converted into a three-channel time-frequency feature component color image by using a pseudo-color coding technology; finally, the collected harmonic source voltage data and the time-frequency feature component color image are taken as inputs of the model, the collected corresponding harmonic source current data are taken as outputs of the model, the network model is continuously trained through the measured data until accurate mapping of a relationship between harmonic voltage and harmonic current of the harmonic source is realized, and a harmonic source data-driven model is obtained.

The invention discloses a harmonic voltage determination method of a permanent magnet synchronous motor and a related device, and relates to the field of motor control, and the method comprises the steps: simplifying a stator fundamental current differential equation of the permanent magnet synchronous motor through fixing motor parameters in combination with system disturbance, and obtaining a stator fundamental current simplified differential equation of the permanent magnet synchronous motor; processing based on the harmonic current and a method for constructing an augmented state variable to obtain a state-space equation containing the harmonic current, and correcting errors existing in the state-space equation and a fundamental wave current sensor measurement system at the same time according to a Kalman optimal estimation principle; and obtaining a real harmonic current estimation value in the operation process of the permanent magnet synchronous motor so as to determine the harmonic voltage of the permanent magnet synchronous motor. According to the method, the harmonic voltage of the permanent magnet synchronous motor is obtained based on the Kalman optimal estimation principle by simplifying the stator fundamental current differential equation of the permanent magnet synchronous motor, considering the harmonic current and constructing the augmented state variable.

The invention provides a power distribution network harmonic instability critical damping dynamic early warning method and system. The method comprises the steps that harmonic voltage and harmonic current of key nodes of a target power distribution network are acquired every first preset time; identifying the harmonic voltage and the harmonic current according to a first preset rule so as to obtain equivalent harmonic impedance under a preset harmonic frequency according to an identification result; calculating a system damping ratio corresponding to a preset harmonic frequency according to the equivalent harmonic impedance; judging whether the system damping ratio is smaller than or equal to a preset damping ratio threshold value; and if the system damping ratio is smaller than or equal to the preset damping ratio threshold value, generating a harmonic instability early warning signal. According to the invention, the accuracy and practicability of early warning can be effectively improved.

The invention relates to the technical field of electric energy quality analysis and the technical field of artificial intelligence, and discloses a harmonic traceability method and device based on an electrified railway and a new energy inverter, and the method comprises the steps: obtaining the voltage spectrum amplitude of each harmonic of the new energy inverter through a trained deep belief network model, according to the voltage frequency spectrum amplitude of each harmonic wave of the electrified railway and the voltage frequency spectrum amplitude of each harmonic wave of the new energy inverter, generating a root-mean-square value of a harmonic voltage frequency spectrum of the electrified railway and a root-mean-square value of a harmonic voltage frequency spectrum of the new energy inverter; when the root-mean-square value of the harmonic voltage frequency spectrum of the electrified railway is greater than the harmonic threshold value of the electrified railway, marking the dominant equipment type of the harmonic source as the electrified railway, and when the root-mean-square value of the harmonic voltage frequency spectrum of the new energy inverter is greater than the harmonic threshold value of the new energy inverter, marking the dominant equipment type of the harmonic source as the electrified railway; and marking the dominant equipment type of the harmonic source as a new energy inverter. According to the invention, the acquisition efficiency of the dominant equipment type of the harmonic source can be improved.

To provide a motor control device of an electric compressor capable of suppressing inaccurate position estimation of a motor (rotor) due to superimposition of a harmonic voltage on a voltage command.SOLUTION: A motor control device 100 includes a PWM calculator 204 that generates a PWM signal for controlling a motor 910 on the basis of an addition value obtained by adding a harmonic voltage command value to a voltage command value for driving the motor 910, and a dead time corrector 213 that corrects a dead time for a power conversion unit 10. The dead time corrector 213 calculates the corrected harmonic current by correcting the phase of the harmonic current based on the output delay Tdel and the frequency ω h of the harmonic current, and corrects the dead time based on the corrected harmonic current and the corrected primary current obtained by correcting the primary current based on the output delay Tdel and the frequency ω of the primary current.SELECTED DRAWING: Figure 4

The invention discloses a power distribution network planning auxiliary method and system based on multi-source data, and the method comprises the steps: injecting a predetermined frequency disturbance signal into a power grid, and collecting the response data of all power equipment; quantifying the response data of each power device to obtain a sensitivity and cluster interaction index; based on the sensitivity and the cluster interaction index, judging whether the corresponding power equipment is marked as an excitation source or not; calling the access positions of all excitation sources and the sensitivity in each resonance frequency band, determining electrical path parameters between the excitation sources and the circuit breaker based on the resonance frequency bands and the access positions, and sequentially inputting the sensitivity of each excitation source in each resonance frequency band and the electrical path parameters into a pre-constructed harmonic phasor superposition model to obtain a harmonic phasor superposition model; obtaining a harmonic voltage split-phase quantity generated by the excitation source at the circuit breaker mounting point under the corresponding resonance frequency band; hidden fault risks are identified and eliminated in the planning stage, and the operation safety of the power grid is remarkably improved.

The application belongs to the technical field of electric machines, and discloses a magnetic suspension fan variable frequency driving device and a harmonic suppression method; the method comprises the following steps: judging a transient operation process and activating a phase compensation mechanism by monitoring the state of the electric machine in real time, extracting harmonic components in real time and updating a weight vector to obtain harmonic currents of different orders; meanwhile, a phase compensation amount is dynamically obtained based on a pre-built control loop phase lag atlas, an anti-phase harmonic voltage is calculated in combination with the harmonic currents and the compensation phase, and the variable frequency device is injected through a space vector pulse width modulation method to realize accurate harmonic cancellation; torque safety monitoring is also independently operated in parallel in the whole process, the electromagnetic torque and its change rate are detected in real time to perform safety logic determination, and a protection action is triggered when the limit is exceeded; the application can realize accurate cancellation of anti-phase harmonics and actual interference harmonics in the transient process, significantly reduce the instantaneous impact of the electromagnetic torque, and effectively improve the operation stability and reliability of the magnetic suspension fan variable frequency driving system under transient working conditions.

This invention discloses a multi-harmonic source responsibility quantification method based on asynchronous measurement, relating to the field of power quality harmonic technology. The method includes measuring the harmonic voltage of the bus of interest and the harmonic current at the connection point between each harmonic source and the bus of interest to construct the observed signal. After centering and whitening, a covariance matrix is ​​constructed. For the covariance matrix, the optimal common orthogonal matrix is ​​determined, and the source signal matrix is ​​reconstructed. The harmonic transfer impedance corresponding to each harmonic source signal is calculated based on a fast-changing component model. Each harmonic source signal is multiplied by its corresponding harmonic transfer impedance to obtain the harmonic voltage of the corresponding harmonic source. The harmonic voltage is projected onto the harmonic voltage of the bus of interest to achieve multi-harmonic source responsibility quantification. This method does not rely on GPS, simplifying the operation steps of multi-harmonic source responsibility quantification and helping to improve quantization efficiency. Simultaneously, the sparsity of the hybrid matrix reduces the computational dimensionality, alleviating the computational burden and improving quantization accuracy.

The application discloses a three-phase series voltage balance control method of a novel AC / DC converter, which is applied to a modular multilevel converter, the converter comprising three single-phase power units in series connection, a transformer and a DC filter, each single-phase power unit being composed of a cascade module chain and a commutation bridge, the cascade module chain comprising a plurality of power sub-modules in series connection, and each sub-module containing a sub-module capacitor; the method comprises the following steps: detecting the average voltage of three-phase sub-modules in real time, triggering the voltage balance control when detecting the imbalance, controlling the output voltage of the cascade module chain to contain harmonic voltage, the frequency of the harmonic voltage being equal to the series resonance frequency of the DC valve side filter inductance and the DC filter capacitor, adjusting the phase of three-phase harmonic voltage, so that the harmonic voltage of the phase with lower voltage and the harmonic current act on the sub-modules to charge the sub-modules, and the harmonic voltage of the phase with higher voltage acts on the sub-modules to discharge the sub-modules, thereby realizing voltage balance, and the control is exited when the three-phase voltage is balanced and the three-phase harmonic voltage is all zero; and the application can realize the consistency of the average voltage of three-phase sub-module capacitors.

The invention discloses a motor diagnosis method and system, a storage medium and electronic equipment, and relates to the technical field of motors. The method comprises the steps of obtaining a first phase voltage according to a preset harmonic voltage; driving a motor inverter according to the first phase voltage to control the operation of the motor, and detecting the three-phase current of the motor; and obtaining a second phase voltage according to the three-phase current, and obtaining a motor diagnosis result according to the second phase voltage and the preset harmonic voltage. Therefore, fault diagnosis of the motor can be realized.

The invention provides a harmonic compensation method for a distributed active filtering system, and relates to the technical field of power distribution networks, and the method comprises the steps: obtaining load data and distributed power data of a power distribution network, and building a power distribution network Norton equivalent model based on a Norton equivalent circuit; pCC harmonic voltage is detected, harmonic responsibility coefficients of all feeder lines are calculated in combination with a Norton equivalent model of the power distribution network, and a harmonic responsibility quantification result is obtained; obtaining harmonic compensation capacity based on the harmonic responsibility quantification result, and dynamically adjusting virtual impedance through droop control to generate basic compensation current; based on the basic compensation current, the compensation capacity of each frequency is adjusted through a frequency division distribution algorithm; a compensation task is autonomously distributed in proportion through multiple inverters according to the adjusted compensation capacity of each frequency; according to the invention, the harmonic source is accurately positioned to optimize the compensation resource allocation, and the stability of the system is significantly improved through the autonomous cooperation of multiple devices.

This invention relates to a method for measuring grid harmonic voltage based on the transfer function of a test system, belonging to the field of power grid technology. This method detects the leakage current signal of capacitive devices in the power grid using a current sensor and constructs a functional relationship between the current sensor's output voltage and the grid harmonic voltage, thereby measuring the grid harmonic voltage based on the current sensor. Specifically, the amplitude-frequency and phase-frequency characteristics of the capacitive device, as well as the current transfer ratio and phase error of the current sensor, are obtained through frequency characteristic testing. Then, the transfer functions of the capacitive device and the current sensor are calculated separately. Combining the impedance transfer function of the capacitive device and the output transfer function of the current sensor, the transfer function of the test system is calculated to construct a functional relationship between the current sensor's output voltage and the grid harmonic voltage. This allows for convenient, fast, and accurate measurement of the grid harmonic voltage using a current sensor.

The invention discloses a calibration system and method for a broadband voltage transformer calibration instrument, and belongs to the technical field of broadband and harmonic voltage transformer metering performance testing. Comprising a harmonic standard source, a first harmonic standard voltage transformer, a second harmonic standard voltage transformer, an error adjusting unit, a broadband voltage transformer calibrator whole inspection device, a tested broadband voltage transformer calibrator whole inspection device and an error calculating unit. According to the system, primary high voltage of a first harmonic standard voltage transformer and primary high voltage of a second harmonic standard voltage transformer with the relative error basically being zero are given through a harmonic standard source, and when the adjustment proportion of an error adjustment unit is 1, the measurement error of the whole detection device of the broadband voltage transformer calibrator is zero. Therefore, the system can verify the error of the whole detection device of the tested broadband voltage transformer calibrator at different error points, thereby realizing the whole detection of the whole detection device of the tested broadband voltage transformer calibrator.

The application discloses a resonant converter control method and device based on threshold voltage control, and the method comprises the following steps: comparing an input voltage with a primary side equivalent voltage to determine whether the resonant converter is currently working in a boost mode or a buck mode; determining threshold voltages of a resonant capacitor in the boost mode and the buck mode; comparing the threshold voltages with collected resonant capacitor voltages to determine switching signals of an inverter circuit; and the threshold voltages of the resonant capacitor in the boost mode and the buck mode are calculated based on P-stage cosine response parameters and N-stage cosine response parameters of the resonant capacitor voltages. By using the above technical scheme, the resonant converter has strong voltage ripple suppression capability, effectively suppresses secondary harmonic voltage ripples from a previous stage, and the control signals are directly determined by input and output states, thereby having excellent dynamic performance.

The invention provides a method and a device for diagnosing abnormality of harmonic voltage measured values of high, medium and low voltage sides of a transformer, which can verify and identify the accuracy of phase measurement of the harmonic voltage at the three sides by using the phase and sequence characteristics of the harmonic voltage at the high, medium and low voltage sides of the transformer and the connection group data of the transformer. Furthermore, in combination with the three-side harmonic voltage and current phasors and the winding harmonic impedance reduced to the high-voltage side, on the basis of a transformer equivalent circuit model, the same-order harmonic sequence voltage theoretical values of the other two sides can be calculated by taking the harmonic sequence voltage passing verification on one side as the reference, and the theoretical values are compared with the actually measured values, so that the theoretical values of the same-order harmonic sequence voltage are obtained. And effective identification of three-side harmonic voltage amplitude measurement accuracy is realized. According to the method, the accuracy of the phase and amplitude data can be reliably discriminated even in a scene in which the multi-side measurement is possible to be abnormal, so that a solid and credible data basis is provided for subsequent harmonic traceability analysis and precise treatment measures.

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 invention provides a doubly-fed wind turbine generator converter direct-current side voltage fluctuation control method and system, and the method comprises the steps: detecting the voltage of a direct-current bus at the direct-current side of a doubly-fed wind turbine generator converter under the condition that the voltage of a power grid is unbalanced, and separating a second harmonic component from the voltage; according to the second harmonic voltage component obtained through separation, the direct-current capacitor current is calculated; in a grid-side converter GSC current control loop, a capacitance current second harmonic control loop is additionally arranged and is used for inhibiting the influence of a second harmonic component on capacitance current; and superposing an output signal of the second harmonic control loop and an output signal of a PI controller in a fundamental current control loop of the grid-side converter to generate a final grid-side converter voltage instruction, and controlling a converter switching device to act through a driving module to realize suppression of DC side voltage fluctuation. According to the relation between the service life of the capacitor and the temperature, the service life of the capacitor is prolonged, and the reliability of the system is improved.