322 results about "Low voltage ride through" patented technology

The invention discloses an online prediction method for a transient frequency track of a power grid under coexistence of wind power low voltage ride through and off-grid, and belongs to the technical field of operation and control of a power system. A multi-source heterogeneous data fusion monitoring system is constructed, power grid and wind turbine generator data are collected, faults are recognized through an improved algorithm, and feature vectors are output; building an energy flow model based on a fault result, calculating a trajectory divergence index by using technologies such as phase-space reconstruction, estimating power vacancy, and obtaining a power unbalance sequence; designing a prediction algorithm by using the sequence, predicting a frequency trajectory in combination with an improved K-nearest neighbor algorithm and a trajectory feature library, and introducing a confidence coefficient to evaluate a correction error; and finally, establishing a three-level control response system, and implementing multi-time scale cooperative control according to a prediction result. The method can accurately predict the frequency trajectory, effectively deal with the wind power fault, improve the stability of the power grid and the wind power consumption capability, and provide powerful guarantee for the safe and stable operation of the power grid.

The invention discloses a low-voltage ride-through control method of a flywheel energy storage system, which is based on a low-voltage ride-through control strategy of model predictive current control (MPCC) so as to improve the low-voltage ride-through capability of the flywheel energy storage system when a power grid fails. A future current value is predicted through system modeling and a prediction algorithm, so that effective control is realized. The MPCC-based machine side-power grid side coordination control strategy can quickly respond to the voltage sag of the power grid, provide reactive power support, stabilize the voltage of the direct current bus, and ensure the safe and reliable operation of the flywheel energy storage system during the voltage sag period of the power grid. A traditional pulse width modulation (PWM) technology is abandoned, the optimal switching state is directly selected through a limited control set, and hardware implementation of a power grid side converter is simplified. A differential control strategy aiming at a power grid symmetric fault (three-phase voltage sudden drop) and an asymmetric fault (single-phase grounding) is provided, the method is suitable for a complex power grid fault scene, and the system universality is improved.

A low voltage ride through control method for a grid-forming inverter based on dynamic internal potential adjustment comprises the following steps: detecting a voltage per unit value of a grid-connected point in real time, and comparing the voltage per unit value with a threshold value to judge a voltage drop event and trigger low voltage ride through control; dynamically calculating active and reactive power reference values through a reactive compensation equation and an active current limiting equation according to the voltage amplitude and the power reference value before falling during the ride-through period; inputting the active reference value into a virtual rotor motion equation to generate a reference phase, and outputting a phase reference signal in combination with a dual-mode phase compensation controller; superposing the reactive reference value with the reference voltage through a reactive voltage regulating ring to generate a voltage amplitude reference signal; synthesizing an internal potential according to the phase and the amplitude reference signal, and obtaining an inductive current reference value through virtual impedance control and current amplitude limiting; and finally, a driving signal is generated through the current inner loop controller and the modulation module. According to the invention, overcurrent can be effectively inhibited, rapid reactive power support is provided, and synchronous stability and smooth transition in a fault period and a recovery process are ensured.

The invention discloses a tracking-network construction combined low-voltage ride-through control method based on transient support. The method comprises the following steps: S1, analyzing transient voltage characteristics and requirements of a network construction-tracking network converter; s2, analyzing a transient voltage support target of the network construction-network following type hybrid multi-machine system; s3, constructing a network construction-network following type hybrid multi-machine system control strategy; and S4, on the basis of the network construction-network following type hybrid multi-machine system control strategy constructed in the S3, optimizing the low voltage ride-through control of the network following type converter and the transient voltage control of the network construction type converter. According to the control method disclosed by the invention, the advantages of the network-building / network-following converter are complemented, the control between the network-building / network-following converter and the network-building / network-following converter is coordinated, and the transient voltage of the power grid is actively supported by using the multi-machine converter system.

The invention discloses a direct-current voltage self-balancing method in the high-low voltage ride-through process of a high-voltage frequency converter, and the method comprises the steps: obtaining an electric signal of the high-voltage frequency converter, calculating the Lyapunov index of a system in real time based on the electric signal, so as to quantify the chaotic state of the system, and generating a real-time Lyapunov index sequence; according to the real-time Lyapunov index sequence, the gradient of the real-time Lyapunov index sequence relative to a preset system state variable is determined, and a Lyapunov gradient field is constructed; using the Lyapunov gradient field to generate a basic control quantity through nonlinear mapping; and converting the basic control quantity into a pulse width modulation parameter to form a PWM control signal set to be applied to the high-voltage frequency converter. According to the method, the Lyapunov gradient field is constructed to provide prospective direction guidance for control, so that the chaotic oscillation is quickly suppressed, and the dynamic stability of the system under power grid disturbance is remarkably improved.

The invention discloses a photovoltaic inverter low-voltage ride-through control method and system based on improved MPPT (maximum power point tracking), relates to the technical field of power distribution and power electronics, and solves the problem of low-voltage ride-through failure caused by rapid rise of direct-current side voltage and dramatic increase of power grid current due to unbalanced system power when the voltage of a power grid drops. On the basis of traditional photovoltaic MPPT control, improved photovoltaic MPPT control is provided, an adjusting coefficient is added on the basis of the traditional MPPT control, the product of the adjusting coefficient and the direct current bus voltage is used as a new reference value, and on the other hand, in order to eliminate the influence of the PCC voltage on the grid side current, a full feed-forward path of the PCC voltage is introduced. The photovoltaic power is automatically converged to the active power according to the proposed control scheme, so that the overvoltage of the direct current bus is limited.

The invention is suitable for the technical field of power electronics and power transmission, and provides a low voltage ride-through control method and system for a network construction type converter, and the method comprises the steps: carrying out the conventional VSG control according to a VSG control strategy, and continuously monitoring the difference between the voltage of a power grid and a set reference value, so as to judge whether a fault occurs or not; when it is detected that the power grid breaks down, homodyne control is carried out on an active power control ring and a reactive power control ring of the grid-forming type converter so as to fix the phase and the amplitude of the output voltage of the converter; calculating and injecting a positive sequence compensation voltage and a negative sequence compensation voltage according to the drop degree of the power grid voltage; and according to the predicted impact current value, dynamically calculating and inputting adaptive virtual impedance. The power angle and the voltage in the fault period can be ensured to be stable, transient overcurrent is effectively restrained, and large power fluctuation is not caused.

The invention discloses an enhanced SVG low voltage ride through method, and belongs to the technical field of electrical automation equipment, and the method comprises the steps: carrying out the three-phase voltage synthesis of a self-built voltage amplitude and a self-built voltage phase, and obtaining a current reference value through an electromagnetic square; according to the self-built voltage phase and the current reference value, a bridge arm differential mode voltage modulation wave is obtained through inner loop current control; obtaining a main circuit commutation actual value of the enhanced SVG, and obtaining a bridge arm common-mode voltage modulation wave through circulating current suppression control in combination with the self-built voltage phase; actual energy and rated energy of the enhanced SVG are obtained, and an energy modulation signal is obtained through an energy control ring; and after modulation is carried out according to the bridge arm differential mode voltage modulation wave, the bridge arm common mode voltage modulation wave and an energy modulation signal, a switching signal is generated to control the enhanced SVG, and low voltage ride through is realized. According to the invention, the problem that the enhanced SVG fails or is off-network under the condition of low voltage can be solved.

The invention relates to the technical field of photovoltaic energy storage converters, and particularly discloses an energy storage converter control method and system under low voltage ride through, and the method comprises the steps: obtaining a grid-connected point voltage value of a photovoltaic power station, determining a voltage state value according to the grid-connected point voltage value of the photovoltaic power station, and judging a low voltage ride through state of a power grid according to the voltage state value; if it is judged that the power grid is in the low-voltage ride-through state, an energy storage converter control strategy is determined according to energy storage converter operation parameters in the power grid low-voltage ride-through process; obtaining performance data of the energy storage converter, and determining an initial control strategy adjustment parameter according to the performance data of the energy storage converter; and correcting the initial control strategy adjustment parameter according to the voltage state value to obtain a corrected control strategy adjustment parameter, and adjusting the energy storage converter control strategy according to the corrected control strategy adjustment parameter to obtain a final control strategy. The control effect of low-voltage ride-through can be effectively improved, and the reliability and stability of power grid operation are ensured.

The invention discloses a VSG-based low-voltage ride-through hybrid control method for a network-building converter. The method comprises the following steps: acquiring grid-connected point voltage and output current of a grid-forming converter in real time, and judging whether to enter a low-voltage ride-through state according to a grid voltage drop degree; in the initial stage of a fault, a current reference saturation mode is adopted to quickly limit the output current of the converter so as to prevent a power device from being damaged by overcurrent; in the fault duration stage, a dynamic self-adaptive virtual impedance and reactive power reference coordinated regulation mechanism is introduced, so that the converter gradually recovers the reactive power injection capability while limiting the fault current, thereby realizing effective support for the grid-connected point voltage; when the voltage of the power grid drops seriously, the capacity of the inverter can be reserved for the reactive power support by temporarily reducing the output of the active power. According to the method, the current protection and voltage support requirements during the fault period are considered, and the operation stability and the power grid adaptive capacity of the grid-forming converter in the low voltage ride-through process are improved.

The invention discloses a wind turbine generator low-voltage ride-through dominant parameter analysis method based on trajectory sensitivity, and relates to the technical field of low-voltage ride-through, and the method comprises the steps: screening parameters related in a reactive power control process according to voltage sensitivity characteristics; calculating the trajectory sensitivity of the parameters, and extracting the frequency characteristic of the trajectory sensitivity based on a discrete Fourier transform method, namely the error characteristic caused by the difference between the model parameters and the actual parameters; the method comprises the following steps: setting an average amplitude index and an amplitude ratio index of parameters, evaluating the influence capability of the parameters, screening the parameters based on the average amplitude index to obtain a candidate parameter set, setting the number of dominant parameters, sorting the candidate parameters from small to large according to the difference between the trajectory sensitivity amplitude ratio index and the error amplitude ratio index of the parameters, and parameters with serial numbers smaller than the number of the dominant parameters are selected as dominant control parameters, so that the influence of each parameter on the bus voltage can be quantitatively evaluated, and the dominant control parameters of the wind turbine generator in the low voltage ride-through period are accurately identified.

The invention relates to the technical field of power electronics, and discloses a low-voltage ride-through control method and device for a network-forming inverter, and the method comprises the steps: monitoring the voltage drop degree of a network side; and adjusting a proportional control coefficient and an integral control coefficient of a proportional-integral controller in the grid-forming inverter according to the grid-side voltage drop degree. By adaptively adjusting the reactive power-voltage loop PI parameter, the stability of the inverter is ensured, and the reactive current response speed of the network-forming inverter during low voltage ride through is greatly improved at the same time.

The embodiment of the invention discloses a junction temperature control method and device for an inverter switching device, and the method comprises the steps: determining a target reactive current for supporting the operation of a power grid according to a measured power grid impedance parameter under the condition of low voltage ride through, and determining the minimum bus voltage of an inverter under the target reactive current, and then the output reactive current of the inverter is controlled to be the target reactive current, so that stable operation of the power grid can be supported under the condition of low voltage ride through of the power grid. The bus voltage of the inverter is adjusted between the preset maximum bus voltage and the preset minimum bus voltage, the target bus voltage meeting the condition that the junction temperature of the switching device does not exceed the preset junction temperature upper limit is determined, and the junction temperature of the switching device in the inverter does not exceed the safety range by controlling the inverter to operate at the target bus voltage subsequently. And the operation safety of the system is improved.

The invention provides a grid-connected converter fault transient process control parameter security domain determination method and device, and relates to the technical field of power systems. The grid-connected converter fault transient process control parameter safety domain determination method comprises the following steps: solving a power system equation of a target phase-locked loop by using structural parameters of a target power grid, and obtaining a first analytical expression of an output phase of the target phase-locked loop in a low-voltage ride-through stage after a short-circuit fault occurs in the target power grid; according to the first analytical expression, determining a low-pass phase-locked stability constraint; wherein the low-voltage ride-through phase-locked stable constraint is used for constraining that the output phase of the target phase-locked loop is not out of step in the low-voltage ride-through stage; determining a first parameter domain of a control parameter of the target grid-connected converter according to the low-pass phase-locked stability constraint; and determining a control parameter security domain of the target grid-connected converter based on the first parameter domain. According to the method, the safety domain of the control parameters of the grid-connected converter can be efficiently and accurately determined, so that the short-circuit fault ride-through capability of the grid-connected converter is effectively improved.

The invention discloses a double-fed fan low voltage ride through cooperative control method based on power prediction, and belongs to the technical field of wind power generation. The method comprises the following steps: inputting data; performing power prediction based on a CNN-LSTM (Convolution and Long Short Term Memory Neural Network); converter capacity dynamic distribution calculation; the invention relates to an improved direct power control strategy design. According to the method, the CNN-LSTM power prediction model is introduced, so that the problems that traditional direct power control depends on real-time power feedback, a control instruction lags, and consequently, the voltage of a direct-current bus is unstable and reactive power support is delayed during low-voltage ride-through are solved. Through the predicted active power curve, the capacity distribution strategy of the converter is adjusted in advance, so that the reactive power support response is accelerated. Through the adaptive hysteresis control technology, the switching frequency is reduced in the low-voltage ride-through period to protect the device, so that the low-voltage ride-through operation capability of the doubly-fed fan is improved.

The invention discloses a low voltage ride through control method and device for an energy storage power station under a power grid voltage fault, and the method comprises the steps: carrying out the coordinate transformation of measured three-phase power grid voltage and power grid current, and obtaining a power grid voltage vector and a current vector under a two-phase rotation dq coordinate system; judging a power grid voltage fault state according to the obtained fault detection signal, and calculating the output power of the converter based on the power grid voltage fault state according to the voltage vector and the current vector; calculating a current reference value according to the output power, and adjusting the current reference value by using a virtual admittance current limiting method to obtain a modulation current; modulation voltage is calculated based on the modulation current, and a modulation voltage signal is converted to generate a three-phase switching signal. According to the invention, the current reference value is adjusted through the virtual admittance current limiting method, so that the energy storage converter can suppress transient current impact during the fault period.

The invention discloses a photovoltaic power grid fault transient control method, device and equipment, and relates to the technical field of photovoltaic auxiliary equipment, and the method comprises the following steps: obtaining the operation data of a photovoltaic grid-connected point, constructing a three-phase coupling characteristic matrix, and generating a disturbance discrimination result according to the dynamic evolution of the three-phase coupling characteristic matrix; based on a disturbance judgment result, collecting three-phase output current of the photovoltaic inverter, calculating disturbance increment of each phase of current, extracting a stable current component during a fault period based on low-voltage ride-through control logic, and calculating equivalent support power of the stable current component at a fault point; the equivalent support power is compared with a preset arc extinguishing threshold value, and the dissociation condition of the fault point is dynamically evaluated; when the fault point is not free, the photovoltaic inverter is controlled to perform state conversion, so that the equivalent support power is lower than an arc extinguishing threshold value; and after detecting that the voltage of the fault point is recovered and the arc light is extinguished, dynamically adjusting the reclosing time sequence based on the voltage recovery rate. The problems that arc light is difficult to extinguish and the reclosing failure rate is high are solved.

The invention provides a network construction type unbalanced fault low-voltage ride-through method and device, and the method comprises the steps: collecting unbalanced three-phase voltage and three-phase current at a grid connection point of a power grid; the grid-connected point is connected in parallel with a grid-following type converter and a grid-constructing type converter; converting the three-phase voltage and the three-phase current into three groups of balance components by using a positive and negative sequence separation method; eliminating harmonic waves in the three-phase current based on the three-phase balance component; based on the three groups of balance components, generating a reference voltage by using a network-forming converter; performing virtual impedance on the reference voltage by using a virtual impedance current limiting algorithm to obtain an actual expected output voltage; based on the actual expected output voltage, overcurrent caused by a short-circuit fault is suppressed; based on the grid following type converter and the grid constructing type converter, when low-voltage ride-through occurs in the power grid, the grid following type converter is used for reactive compensation, and low-voltage ride-through suppression of the power grid is completed. A grid-connected system can be controlled to generate overcurrent and low-voltage ride-through caused by current harmonics and short-circuit faults.

The invention relates to a fan model high and low voltage ride-through process parameter identification method and system based on a Harlisia eagle algorithm and a medium, and the method comprises the steps: firstly verifying a PSASP electromechanical transient simulation model of a direct-drive permanent magnet synchronous wind generating set, and researching the influence of high and low voltage ride-through faults of a direct-drive fan on a power grid; and meanwhile, the influence of key parameters of the direct-driven permanent magnet synchronous wind generating set model on high and low voltage ride-through characteristics is analyzed. According to a fan type test result, wind turbine generator fault transient state control parameter identification is realized by using a Harlisia eagle optimization algorithm, wind turbine generator controller key parameter identification based on PSASP and influence analysis on high and low voltage ride-through characteristics are completed, the deviation between a simulation result and an actual measurement result is within an allowable range, and the method has the advantages of high simulation accuracy and high reliability. Model verification requirements are met, and stable operation of the wind turbine generator is guaranteed.

The invention provides a low-voltage ride-through control method and system for power electronic equipment. The method comprises the steps that the control mode of the power electronic equipment is set to be double-closed-loop control; in the double-closed-loop control mode, according to outer-loop control parameters of the power electronic equipment, instruction values of positive and negative sequence currents of outer-loop control are calculated; carrying out amplitude limiting on the instruction values of the positive and negative sequence current, and carrying out vector fusion on the instruction values of the positive and negative sequence current after amplitude limiting to obtain the instruction values of the positive and negative sequence current after the maximum value is limited; performing positive and negative sequence current control according to the positive and negative sequence current instruction value after the maximum value is limited, and completing low-voltage ride-through; vector fusion is carried out on the instruction values of the positive sequence current and the negative sequence current after amplitude limiting, fault current suppression based on the low voltage ride through process can be achieved, the large overcurrent phenomenon is avoided, tripping conditions are reduced, and it is guaranteed that low voltage ride through can be achieved with high probability on the premise that normal control strategy logic is not affected.

The invention discloses a DFIG and SVG collaborative reactive power support strategy adopting active-disturbance-rejection control. A first-order linear active-disturbance-rejection controller is designed to replace traditional PI control of a voltage outer ring of a doubly-fed wind generating set grid side converter; if the voltage drop occurs at the grid-connected point of the wind power plant, designing a q-axis current instruction value of the grid-side converter during the fault period as q-axis input of current inner loop control of the grid-side converter of the doubly-fed wind generating set, so that the doubly-fed wind generating set emits reactive power; after compensation, if the power factor of the doubly-fed wind generating set is smaller than a preset threshold value, the SVG device is made to send out reactive power according to the designed q-axis current instruction value of the SVG during the fault period. And after the fault is cleared, the q-axis current instruction value of the SVG is redesigned, so that the SVG device absorbs reactive power, and the overvoltage risk of the grid-connected point is reduced. According to the invention, a DFIG and SVG cooperative reactive power support strategy of active disturbance rejection control is adopted to meet the reactive power demand in the low voltage ride through period, and the operation stability of the wind power plant is effectively improved.

The invention discloses a network source coordination online monitoring and evaluation system based on WAMS dynamic data. The system comprises a primary frequency modulation monitoring module, an excitation system evaluation module, an AGC performance evaluation module, a wind power integration online monitoring module, a subsynchronous oscillation monitoring module and a visual human-computer interface. Primary frequency modulation response conditions under daily and large disturbance conditions are counted, the real-time operation state of a generator, the low-frequency oscillation suppression capability of an excitation regulator PSS, the operation alarm and limitation of the excitation regulator, the state of an excitation system, excitation voltage regulation and the like are evaluated, important data such as the AGC regulation rate, the AGC regulation precision and the AGC regulation time of the generator set are analyzed, and the AGC regulation accuracy and the AGC regulation time of the generator set are analyzed. And the wind power plant active power maximum variable quantity, wind turbine generator high-low voltage ride through, wind power plant frequency change, grid-connected point voltage change and the like are calculated, and early warning is carried out on a subsynchronous oscillation event. The invention provides an auxiliary tool and a convenient means for quickly positioning a network source coordination problem.

The invention provides a distributed photovoltaic grid-connected converter low-voltage ride-through control method based on sum-difference coordinate transformation, and solves the problems of insufficient synchronism, poor stability, insufficient reactive power support potential excavation and the like existing in collaborative response under power grid voltage drop during distributed photovoltaic grid connection. According to the method, impedance modeling and equivalent symmetry transformation are carried out on the distributed photovoltaic inverter, and a coupling multi-dimensional matrix equation is established; an original coupling system is decoupled into a sum current channel and a plurality of difference current channels, the control complexity is simplified, and an open-loop output impedance expression and a closed-loop output impedance expression are deduced; secondly, formulating a refined active / reactive current collaborative distribution strategy for different voltage drop depths, dynamically calculating the minimum reactive current during voltage drop, preferentially meeting the national standard, and maximizing active output or balancing loss under the limit of rated current; and finally, through sum-difference coordinate transformation, the total current demand and distribution are efficiently decoupled and issued to a current loop controller of each inverter, so that rapid, synchronous and stable cooperative operation of multiple inverters is realized.

The invention discloses a dynamic reactive current control method and a dynamic reactive current control system for a grid-forming type grid-connected converter, and the method comprises the steps: adding compensation control in a voltage amplitude control link of the grid-forming type grid-connected converter on the basis of the control of the grid-forming type grid-connected converter, and superposing a voltage compensation signal on a voltage reference value so as to realize the dynamic reactive current control of the grid-forming type grid-connected converter. The control method comprises the steps of signal acquisition and calculation, low voltage ride through state judgment, reactive power limitation calculation in a normal state, reactive power limitation calculation in a low voltage ride through state, voltage compensation control and voltage set value control. According to the method, the voltage compensation item calculated based on the reactive current limitation is superposed on voltage control, the voltage reference value is limited during low-voltage ride through, and the compensation item is calculated based on the reactive current limitation, so that the limitation on the reactive current is more direct, and the accuracy of the low-voltage ride through is improved. The converter is protected, and meanwhile the converter has higher reliability in the transient process.

The invention discloses an improved control method for low voltage ride through of a distributed direct-driven wind turbine generator, and belongs to the technical field of grid-connected control of wind turbine generators. And when the voltage of the power grid drops, the distributed direct-driven fan enters a low-voltage ride-through state. The method comprises the following steps: firstly, establishing a dq-axis grid-connected system model of the distributed direct-driven fan; and then, by taking'reduction of active loss and improvement of terminal voltage 'as double control objectives, under the constraint of a grid-connected guide rule, a machine-side / grid-side current limit and a power limit, an improved multi-objective particle swarm optimization algorithm is adopted to solve optimal set values of active and reactive current online in real time, and the optimal set values directly act on a grid-side converter. Compared with an existing proportional reactive power injection method, on the premise that the grid-connected guide rule requirement is met during the fault period, the method can simultaneously provide reactive power support and raise the terminal voltage; active loss is reduced, and the power grid frequency is supported; according to the method, the low-voltage ride-through capability and the power generation economy of the wind power plant are remarkably improved.

Systems, devices, and methods for controlling grid-tied inverters with instantaneous synchronization and low-voltage-ride-through (LVRT) capabilities under a wide range of grid cable impedance without using a phase-locked loop.

The invention discloses a doubly-fed wind turbine generator control parameter optimization method based on the lowest point of the frequency of a power system under low voltage ride through, and the method comprises the steps: 1, considering the influence of a wind speed, a pitch angle and a rotating speed on a capture coefficient, and solving the capture power; 2, providing a virtual synchronous machine control strategy for active compensation of the wind turbine generator, solving a transfer function between the rotating speed of the wind turbine generator and the system frequency, and deducing a power frequency response transfer function of the wind turbine generator; 3, solving the equivalent inertia time constant of the wind turbine generator based on the transfer function, considering the influence of different working conditions of the wind turbine generator in low voltage ride through, performing weighted calculation on the equivalent inertia time constant of the system, and quantifying the power frequency response characteristics of the wind turbine generator in different working conditions; 4, solving a frequency variation based on a system equivalent inertia time constant and a power frequency response characteristic; and 5, solving system trajectory sensitivity, constructing a Hessian matrix based on the sensitivity, solving a parameter optimal value by an interior point method, and raising a frequency lowest point. The calculation accuracy of the frequency variation of the power system is improved.

The invention discloses a converter feedforward decoupling control method and system for improving low voltage ride through capability, and the method comprises the steps: firstly carrying out the dynamic lead compensation of a measurement voltage after d-q conversion, so as to actively offset the amplitude attenuation and phase delay introduced by hardware links, such as a low-pass filter, in a measurement link, and restore a real power grid voltage dynamic state; and based on the accurately compensated and corrected voltage signal, positive and negative sequence separation and feed-forward quantity calculation are carried out, and finally a reference voltage instruction is generated. In this way, it can be ensured that the input signal of feedforward control accurately reflects the instantaneous change of the power grid voltage, the dynamic response speed and precision of a control system are greatly improved, current overshoot and oscillation in the voltage drop period are effectively restrained, the low-voltage ride-through capacity of a converter is remarkably enhanced, and the stability of new energy grid connection is guaranteed.

The invention relates to the field of low voltage ride-through control, and particularly discloses a wind power converter low voltage ride-through cooperative control method and system, which starts conventional LVRT response through a fault detection module, provides basic reactive power support and inhibits active power, and evaluates a power grid recovery state through a power grid recovery state evaluation module. Key indexes such as grid-connected point voltage recovery slope, frequency deviation and system short-circuit capacity are comprehensively analyzed, and a power grid recovery health degree index is quantitatively generated. Then, based on the index, a self-adaptive active power recovery slope is decided by combining local states such as a direct current bus voltage of the fan itself and the like. And finally, the active power recovery module smoothly recovers power output according to the adaptive slope. Through the mode, the power recovery behavior of the fan is tightly coupled with the real-time bearing capacity of the power grid, cooperative recovery control of low voltage ride through is realized, the stability of the power grid is ensured, and the efficiency and safety of power recovery are improved.

The invention discloses a network construction type converter low voltage ride through control method and system based on voltage sag depth dynamic adjustment, and a storage medium. The method comprises the following steps: dividing voltage sag depth grades; collecting a grid-connected point voltage signal for preprocessing, calculating the voltage drop depth according to the preprocessed voltage, and judging the level of the voltage drop depth; if the voltage sag depth is in a normal state, traditional VSG control is executed to complete low voltage ride through, otherwise, the reactive-voltage sag coefficient, the output reactive power and the virtual impedance are updated according to the voltage sag depth; when the voltage drop is not recovered to a normal state or is recovered to be normal but does not last for a set time, continuously carrying out the process after dividing the depth grade of the voltage drop, otherwise, adjusting the droop coefficient according to discretization exponential attenuation, and recovering the active power according to a discretization active slope recovery strategy; according to the invention, the power grid support efficiency and safety in the low voltage ride through process can be improved, and secondary oscillation in the recovery period can be avoided.