507 results about "Transient current" patented technology

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 provides a fault ride-through control method and system for a network-forming converter, and relates to the technical field of power electronics. The fault ride-through control method of the network construction type converter comprises the following steps: determining a real-time virtual impedance value corresponding to a control loop based on a virtual admittance control module; in response to the fact that the real-time virtual impedance value is larger than or equal to the reference virtual impedance value of the control loop, transient current output by the network-building type converter is adjusted based on first-stage current limiting, and steady-state current output by the network-building type converter is adjusted based on second-stage current limiting; calculating an active power proportionality coefficient based on the real-time parameter and the reference parameter; calculating a target active power reference value according to the active power proportionality coefficient and the reference active power reference value; and executing power control based on the target active power reference value, and adjusting the output voltage of the network-forming converter. According to the method, when the power grid breaks down, the grid-forming type converter can have the functions of current limiting and transient synchronization stability improving at the same time.

Embodiments of the present invention provide a method and apparatus for suppressing transient current of a grid-forming converter, a computing device, a computer-readable storage medium, and a computer program product. The suppressing method comprises: calculating first virtual impedance on the basis of an actual voltage instantaneous value of a point of common coupling; calculating second virtual impedance on the basis of an actual current maximum amplitude of the point of common coupling; and suppressing the transient current of the grid-forming converter on the basis of the first virtual impedance and the second virtual impedance. In this way, by combining the actual voltage instantaneous value of the point of common coupling and the actual current maximum amplitude of the point of common coupling, transient current can be suppressed at the moment when a fault occurs in a grid-forming converter, thereby avoiding misoperation triggering of a protection apparatus, and ensuring that the grid-forming converter can restore stable operation once the fault is removed.

The invention discloses an intelligent electromagnetic induction heating method and system for multi-parameter collaborative frequency domain separation, and provides a synchronous parameter acquisition and frequency domain separation processing scheme for solving the problems of temperature detection lag, insufficient frequency domain interference processing and weak dynamic adaptation capability in the prior art. Transient current, voltage and change rate (a first parameter group) of an electromagnetic coil are synchronously acquired, and high-frequency fluctuation (greater than or equal to 10kHz) and low-frequency disturbance (1t, 1t) are converted into low-frequency fluctuation (greater than or equal to 10kHz) by combining environment temperature, cookware materials and user preferences (a second parameter group); 10kHz) is used for frequency spectrum separation. Phase difference features are extracted through band elimination filtering and FFT, heating priorities are corrected in combination with dynamic compensation factors, and a segmented heating curve is generated through time-frequency domain weighted fusion. And the system adjusts PWM parameters in real time, and triggers adaptive protection when detecting that the phase is abnormal or the power frequency exceeds the limit. According to the method, the limitation of single-frequency-band detection is broken through, high-frequency noise suppression and low-frequency disturbance compensation are realized, and accurate temperature control of ferromagnetic / non-ferromagnetic cookware is supported.

The invention provides a method for testing the stability of an electronic product, and the method comprises the steps: obtaining the propagation characteristic data of a transient current in a grounding network, building a multi-point grounding network model in combination with the potential distribution data of each node, inputting the potential of the nodes and the transient current data, and predicting the fluctuation trend of the ground potential through the multi-point grounding network model; according to the predicted ground potential fluctuation trend, extracting a coupling path of an interference signal in the grounding network when common-mode interference exists, and determining a main node and a propagation direction of interference signal propagation to obtain a sensitive circuit; calculating node potential distribution data of the grounding network after node layout, judging whether the potential difference between key nodes is within a preset range or not, and if the potential difference exceeds the preset range, refining network division, increasing equipotential connection or locally reducing grounding resistance; and determining a matching design scheme of the grounding network and the sensitive circuit according to the anti-interference capability, building a test platform, and testing stability data of the grounding system in different electromagnetic environments.

The invention belongs to the technical field of fault early warning, and discloses a heater fault early warning method and system based on current analysis. Comprising the steps that transient current signals of all heating wire loops in the copper bush heater are collected in real time, harmonic characteristic parameters are extracted, and a dynamic current fingerprint database and a multi-dimensional harmonic characteristic spectrum are generated respectively; dynamically calculating the contact impedance between each heating wire and the copper sleeve groove according to the dynamic current fingerprint database and the multi-dimensional harmonic characteristic spectrum; the current distribution path of each heating wire in the copper sleeve groove is restored in real time, the abnormal contact form of each heating wire is identified, the falling risk probability and falling risk strength of each heating wire are dynamically predicted by fusing the falling precursor signals of each heating wire detected in real time, and a grading early warning strategy report is generated in real time; according to the invention, fault early warning can be converted into preventive maintenance from post-maintenance, the intelligent level of operation and maintenance of the heater is improved, and the continuity and safety of production are guaranteed.

The invention provides a transient current capability improvement control system and method of a wind and light power generation system. The system comprises a self-synchronizing voltage source control module, a junction temperature prediction module, a transient current improvement control module, a current instruction calculation module and a transient current precise control module. According to the invention, online observation of the junction temperature of the wind-solar converter power device can be realized, the maximum short-circuit current which can be output can be accurately predicted, the DC bus voltage, the switching frequency and the modulation strategy are adjusted when the power grid has a fault, the junction temperature of the power device is reduced, and the transient current endurance capability of the power device is improved. And the transient current is accurately controlled to limit the utilization of the transient capability of the power device.

The invention discloses an error compensation method for a dead-beat predictive current control model of a high-speed permanent magnet synchronous motor in a static coordinate system. The method comprises the following steps: firstly, analyzing a dead-beat predictive current control scheme of the high-speed permanent magnet synchronous motor under a static coordinate system, and on the basis, analyzing a steady-state current control error caused by parameter mismatch, transient current tracking, voltage loss caused by nonlinearity of an inverter, and current errors in a steady state and a transient state; and an error compensation scheme based on dead-beat predictive current control of the high-speed permanent magnet synchronous motor under a static coordinate system is provided, namely, self-adaptive reference correction current injection is provided. According to the method, the parameter robustness of dead-beat predictive current control of the high-speed permanent magnet synchronous motor based on static coordinates is effectively improved, and steady-state current errors caused by inaccurate models can be effectively eliminated.

The invention relates to the technical field of digital control, in particular to a digital control system and method. The method comprises the following steps: acquiring an industrial equipment object and constructing a simulation model based on the industrial equipment object so as to simulate the running state of the equipment and acquire corresponding simulation data; analyzing the transient current surge phenomenon of the equipment according to the simulation data, and further analyzing the multi-dimensional interactive aging trend of the equipment, so as to estimate the attenuation condition of the dynamic precision of the equipment; estimating the equipment fault risk through the equipment dynamic precision attenuation data, and estimating the quality attenuation state of the industrial product according to the fault risk; the system transmits fault risk and product quality attenuation data to a digital control system, carries out equipment abnormity early warning through the system, and adjusts equipment parameters according to an early warning result. According to the invention, the industrial equipment is digitally controlled, so that the operation efficiency of the industrial equipment is higher.

The invention relates to the technical field of data processing, and provides a battery performance detection device and method, and the method comprises the steps: obtaining transient voltage data and transient current data of a battery in different working states, carrying out the wavelet decomposition of the transient voltage data, obtaining a multi-state voltage feature, carrying out the time sequence mapping of the multi-state voltage feature and the transient current data, and obtaining a multi-state voltage feature; and obtaining an inflection point parameter set to construct a parameter stability matrix, analyzing a battery health state based on the parameter stability matrix, generating a battery life prediction based on a health state index, and performing trend analysis and residual life estimation to generate a battery performance detection result. When a complex electrochemical environment and various working states are processed, the efficiency and accuracy of battery performance detection are improved, and the problems of long battery test period and poor detection precision in practical application are solved.

The invention discloses a pulse electroplating detection method, a pulse electroplating device and equipment, and the method comprises the steps: synchronously collecting transient current density data of a three-pole assembly in a pulse switching time window, and calculating a time derivative of a current density ratio to obtain electrochemical stress gradient data; performing space-time correlation analysis on the stress gradient data of the continuous pulse period, and tracking a spatial propagation trajectory of stress anomaly; a key monitoring area is determined according to the propagation trajectory, and ion migration impedance sensitivity distribution is detected through micro-amplitude current modulation; performing multi-dimensional coupling analysis on the stress gradient, the propagation trajectory and the impedance sensitivity data, and identifying time sequence correlation characteristics of stress evolution and ion anomaly; and performing quantitative evaluation and grade division on the electrochemical state of the avoidance area based on the coupling correlation characteristics. According to the scheme, early recognition and predictive evaluation of the ion migration abnormity of the boundary layer of the avoidance area can be realized in the pulse electroplating process, and the electroplating quality control precision and the process stability are remarkably improved.

The invention discloses an all-solid-state calibration-free ion concentration detection method. The method comprises the following steps: constructing a plurality of traditional three-electrode detection systems; in each traditional three-electrode detection system, current and impedance signals are synchronously acquired through a step potential electrochemical spectrum and an electrochemical impedance spectrum, and interface kinetic parameters are analyzed; on the basis of a traditional three-electrode detection system, an original reference electrode is removed, a counter electrode is reserved, all glassy carbon electrodes with gradient membrane volumes are connected in series one by one to obtain a new three-electrode detection system, the new three-electrode detection system is immersed in a to-be-detected solution, a preset potential is applied, and through transient current response in combination with calibrated kinetic parameters, the gradient membrane volumes of the glassy carbon electrodes are detected. And performing inversion to obtain the ion concentration of the to-be-detected solution. According to the method, automatic calibration is realized by analyzing interface process kinetic parameters of different-volume film ion selective electrodes and calculating the slope to generate a built-in standard curve. According to the method, interface process parameters are obtained through transient current, and dependence of a traditional detection system on the stable potential of a reference electrode is eliminated.

The invention discloses an offshore wind power flexible direct current converter valve fault ride-through control method for reducing transient current overshoot, relates to the technical field of new energy grid connection, and solves the problem of transient current overshoot of an offshore wind power flexible direct current converter valve (MMC) during a fault ride-through period. A mathematical model of the offshore wind power flexible direct current converter valve is established; separating positive and negative sequence components by adopting a bisynchronous rotation dq coordinate system transformation mode, and designing a corresponding positive sequence inner ring current controller and a corresponding negative sequence inner ring current controller; detecting the power grid voltage drop condition through an effective value algorithm, adjusting active and reactive power reference values according to the detected power grid voltage value, and controlling the voltage to be stable; the method comprises the following steps: estimating the impedance of a power grid in real time by using a Kalman filter, introducing adaptive virtual impedance, dynamically adjusting a virtual impedance value through model predictive control (MPC), and adaptively inhibiting transient current; according to the method, it can be ensured that transient current overshoot is effectively reduced during the fault ride-through period of the offshore wind power flexible direct current converter valve, the stability and reliability of the system are improved, and a safer and more efficient fault ride-through control strategy is provided for offshore wind power grid connection.

The invention discloses a column switch detection method and device, electronic equipment and a storage medium. The method comprises the following steps: acquiring transient current and steady-state current flowing through the pole-mounted switch, and acquiring environmental parameters of a current environment where the pole-mounted switch is located; based on the transient current, the steady-state current and the environmental parameters, a target correlation coefficient of the pole-mounted switch is determined, and the target correlation coefficient is used for representing correlation between the transient current and the steady-state current in the current environment; and based on preset correlation coefficients and target correlation coefficients corresponding to different damping levels, determining a target damping level corresponding to the pole-mounted switch, the preset correlation coefficients being used for representing correlation between the sample transient current and the sample steady-state current in a preset environment. According to the invention, the technical problem of low detection efficiency of the pole-mounted switch in the prior art is solved.

The invention belongs to the field of non-intrusive load identification, and provides a non-intrusive load identification method and system for electrical equipment, a medium and equipment, and the technical scheme is as follows: an event in which the state of the equipment changes is judged through event detection, transient and steady voltage, current and power characteristics of the equipment are extracted, and an equipment state information base is constructed; the state transition probabilities of different devices are counted under natural operation of the devices, a state transition probability matrix is obtained, meanwhile, in order to more accurately obtain the states of the devices, according to transient current and voltage, steady-state current and voltage and power characteristics, similarity between new time and data in a state information base is calculated, a similarity information matrix is constructed, and the state transition probability matrix is calculated. And updating the state transition probability matrix, constructing a neural network training set based on a composite feature vector composed of the equipment state information base, the state transition probability matrix and the similarity information matrix, and training a classification neural network to obtain an equipment category. And complementarity among different characteristics is utilized, so that the load identification capability of the office equipment is improved.

The invention relates to the technical field of power systems, and provides a power transmission line lightning stroke fault positioning method and device, electronic equipment and a storage medium. The method comprises the following steps: acquiring transient voltage data after a power transmission line is directly struck by lightning; defining a set of possible fault locations based on the historical fault data; converting the transient voltage into a transient current; reversely injecting the transient current into a simulation model of the power transmission system from the same observation point, and simulating a transverse branch current at each possible fault position; and calculating the time domain similarity between the transient current and the transverse branch current at each possible fault position, and determining the fault position with the highest similarity as a lightning stroke fault position. According to the invention, high-precision positioning of the lightning stroke fault can be realized only by installing one measurement point in the main substation, and the reliability is high. The method is not only suitable for a lossless system, but also suitable for a lossy transmission line.

The invention discloses a Ga2O3 SBD trap test method based on forward current transient response, and belongs to the field of semiconductor device reliability. Comprising the following steps: giving a filling voltage interval and a filling time interval of a Ga2O3 SBD trap filling stage; giving a bias condition and a test time interval of a trap test stage; giving a normalization processing method and range of the forward current transient response; a characterization range of a Ga2O3 SBD device level trap time constant is given. The transient response curve of the forward current of the Ga2O3SBD under the constant test voltage is collected, and the transient current variation caused by the trap is evaluated through a normalization processing method. And repeatedly testing under the condition of multiple groups of filling voltages, establishing a time constant spectrum of the trap by using a structure function method, and extracting a time constant parameter of the trap in the Ga2O3SBD to realize in-situ and online Ga2O3SBD trap test. The method is suitable for evaluating the trap effect of Ga2O3 SBD devices from different manufacturers, and can realize spectral valuation characterization of Ga2O3 SBD traps and in-situ and nondestructive testing of trap parameters.

The invention relates to the technical field of printed circuit board signal management, and discloses an intelligent management method and system for a printed circuit board signal control process, and the method comprises the steps: obtaining the noise data of a target channel of a target management object and all adjacent channels in real time, analyzing the noise data of all channels, generating a frequency domain collaborative management domain, and carrying out the frequency domain collaborative management domain; the target management object is a server printed circuit board; the method comprises the following steps: S1, analyzing noise data to generate a frequency domain collaborative management domain, S2, mapping transient current into an N * N matrix and establishing a two-layer graph convolutional network, and S4, acquiring load data in a 100ms window, processing by using a two-way long-short-term memory network of two hidden layers, and adapting to signal transmission of a server printed circuit board, so as to avoid misjudgment caused by crosstalk. Coupling of a strong electromagnetic field is suppressed, and the signal management effect and the transmission stability are improved.

The invention provides a low-voltage flexible DC system fault detection method based on complex domain analysis, and the method comprises the steps: obtaining and sampling a transient current signal in a low-voltage flexible DC system, fitting the transient current signal into a linear combination of a group of exponential functions, and obtaining a fitting exponential function; solving the fitting exponential function in a Z domain based on a Pade approximation method to obtain a complex index of the fitting exponential function; determining a fault threshold frequency according to the operation parameters of the low-voltage flexible DC system; the complex index is used as an analysis object, and the natural oscillation frequency of the low-voltage flexible direct-current system is obtained through formula calculation; and taking the fault threshold frequency as a state circle radius, constructing a fault discrimination model based on a complex plane, comparing the natural oscillation frequency with the fault threshold frequency, and outputting a fault detection result of the low-voltage flexible DC system in combination with a real part of a complex index. According to the method, the sensitivity to noise can be reduced, and meanwhile, the requirement of fault detection for speed is met.

The invention discloses a partial discharge monitoring system, method, equipment and medium for a switch cabinet, and belongs to the technical field of insulation state monitoring of high-voltage electrical equipment, and the partial discharge monitoring system comprises an NO2 gas detection module, a pulse current signal acquisition module, a signal processing module, a data transmission module, a data analysis and diagnosis module and a user display and alarm module. According to the invention, by integrating dual monitoring technologies of NO2 gas detection and transient current signal acquisition and combining signal processing, data transmission, data analysis and diagnosis and a user display and alarm module, high-precision and high-reliability online monitoring of partial discharge of the high-voltage switch cabinet is realized; the defects that a traditional single method is prone to electromagnetic interference, low in sensitivity and not suitable for long-term online monitoring are overcome, and the anti-interference capacity, diagnosis accuracy and operation stability of a monitoring system are improved.

The present invention provides a grid simulator and a test device for the stability test of a grid-connected converter. Among them: The voltage-controlled converter uses a virtual impedance controller and a voltage controller to achieve the port voltage characteristics of the simulated grid, and the voltage-controlled converter has a relatively high switching frequency; the current-controlled converter uses a transient current controller and a current controller to absorb or generate the port load current of the simulated grid, and the current-controlled converter has a relatively low switching frequency; the AC sides of the two converters are connected in parallel and directly connected to the port of the simulated grid, or connected to the port of the simulated grid through a resistor-impedance network. The virtual impedance controller eliminates the differential operator through the Norton equivalent circuit and accurately reproduces the port impedance characteristics of the grid. The present invention can effectively simulate and shape the grid impedance characteristics in a wide frequency band, so as to conveniently realize the stability test of the grid-connected inverter under different grid impedance conditions.

The invention discloses a fault transient current analysis method of a network-forming converter considering a power angle swing process. The method belongs to the technical field of power system fault analysis, is used for realizing accurate solution of transient current of a network-forming converter under a three-phase symmetric drop fault of power grid voltage, and comprises the following steps: firstly, constructing a power angle swing equation based on a virtual synchronous machine control strategy; taylor series expansion is carried out on an equation nonlinear term at a steady-state equilibrium point after the fault, a linear oscillation component and a nonlinear disturbance component are separated, and a power angle approximate analytical solution is derived; secondly, establishing a grid-connected current first-order differential equation containing power grid impedance based on circuit topology, and substituting the simplified power angle expression to obtain a time domain analytical expression of voltage on the power grid impedance under a three-phase static coordinate system; and finally, in combination with a solving method of a first-order differential equation and a current steady-state initial value condition, establishing a current analytical expression of the whole fault transient process.

The invention relates to the technical field of steady-state balance of an electric power system, and discloses a current transient fusion and steady-state balance method based on intelligent control, which comprises the following steps of: based on a transient current fluctuation signal in the electric power system, obtaining a current fluctuation amplitude, a voltage fluctuation amplitude and a frequency, and measuring the current fluctuation amplitude and the voltage fluctuation amplitude by measuring the variation amplitude of the current and the voltage; and calculating the change rate of the fluctuation amplitude and the frequency, and comparing the change rate with a preset threshold value to generate a transient fluctuation state signal. According to the method, transient fluctuation state signals are obtained through a particle swarm optimization algorithm, the distribution condition of current loads of all nodes is accurately calculated, fine adjustment is carried out, load balance is ensured, the stability and response speed of the system under transient disturbance are improved, a language type fuzzy system is adopted, and when transient current and steady current are fused, the stability of the system is improved. According to the actual energy distribution state, the optimal fusion mode is intelligently selected, efficient utilization and distribution of energy are achieved, and the long-term operation stability and safety of a power system are enhanced.

The invention discloses a high-speed power supply conversion control method, which relates to the technical field of power supply conversion control, and comprises the following steps of: synchronously acquiring transient voltage waveforms and transient current waveforms at two ends of a power device in each pulse width modulation period through an analog-to-digital conversion module; and constructing a high-frequency waveform data frame containing a plurality of modulation periods based on a fixed time sliding window mechanism. According to the invention, through frequency domain monitoring and frequency spectrum characteristic quantitative analysis, a resonance response index is output, and a closed-loop mechanism from high-frequency waveform sensing to risk early warning is realized; the PWM dominant frequency and harmonic distribution are dynamically adjusted in combination with a digital controller, a frequency modulation avoidance and harmonic suppression cooperative control strategy is constructed, the adaptive capacity, stability and electromagnetic compatibility of the system when dealing with parasitic resonance interference are remarkably improved, and the method has outstanding engineering practicability and technical innovation.

The invention discloses an adaptive virtual impedance-based fault current limiting method for a network-forming converter, and belongs to the technical field of converter control. Comprising the following steps: collecting grid-side voltage, converter-side voltage and converter output current; carrying out current amplitude calculation on the grid-side voltage quantity to obtain a current effective value of the port of the converter; judging whether the current effective value of the current transformer port exceeds a current threshold value of the current transformer; and if yes, self-adaptive virtual impedance is introduced to carry out converter fault current limitation. The resistance part of the virtual impedance is used for suppressing surge current at the beginning of a fault; and the reactance part is used for suppressing the effective value of the fault transient current within the current limiting range. In the fault process, the current virtual impedance value is adaptively changed according to the effective value of the current overcurrent, and the virtual impedance can be automatically quitted after the fault end stage. The method is suitable for fault current suppression of the network-forming converter in various control modes, and has good feasibility and practical value.

The invention discloses a method for measuring and analyzing residual magnetism characteristics of an iron core. According to the method, a to-be-detected iron core is demagnetized, preset residual magnetism is set, direct-current voltage excitation with opposite polarities, the same amplitude and the same duration is applied to a primary winding of the to-be-detected iron core, and transient current response signals are synchronously collected; two groups of current under positive / negative polarity excitation are extracted, and the residual magnetism direction is judged by comparing the change rate of the current; a curve of equivalent resistance changing along with time is calculated based on forward current and voltage, a resistance value corresponding to a characteristic inflection point moment is selected, the resistance value is substituted into a pre-established residual magnetism-equivalent resistance empirical formula to deduce the magnitude of residual magnetism, and a matched iron core residual magnetism detection and demagnetization integrated system integrates information management, residual magnetism detection, demagnetization and display modules. And closed-loop automation of detection, analysis and demagnetization is realized. According to the method, a magnetic field sensor is not needed, the residual magnetism direction and size can be synchronously obtained in a high-precision and robust mode only through port electric signals, and the method is suitable for on-site off-line or live detection.

The invention discloses an electric energy metering error evaluation method and system for a direct current charging pile, equipment and a medium, and the method comprises the steps: constructing an electric energy disturbance response function based on transient voltage and transient current, and effectively quantifying the transient metering deviation caused by measurement lag, voltage drop, current peak and other factors in the actual operation of the direct current charging pile. Error reconstruction modeling has higher dynamic adaptive capacity and physical rationality, the limitation that in the prior art, the influence of the high-variable-load working condition on metering cannot be reflected is broken through, and the accuracy and timeliness of direct-current charging pile error monitoring are greatly improved. Besides, a standard error is introduced to carry out fitting calibration on a reconstruction error and carry out energy conservation verification, thereby realizing verifiability on a physical level and controllability in engineering implementation, enhancing credibility and authority of an evaluation result, constructing a closed-loop analysis mechanism from error evaluation to metering correction and then to conservation verification, and improving reliability and reliability of the evaluation result. And the closeness and the adaptive capability of the overall error evaluation are improved.

The invention relates to an IGBT parallel current sharing control circuit and method for turn-off transient current change rate detection, and the circuit employs a PCB Rogowski coil probe to carry out the non-contact detection of the turn-off current change rate of a parallel device, thereby accurately judging the non-current sharing characteristic of the parallel device. The problem of integrated design of a traditional detection scheme in large-current and high-power-density application is effectively solved; meanwhile, by designing a current change rate peak holding circuit, the holding time of a peak signal is remarkably prolonged, and the performance requirement on the ADC sampling rate is greatly reduced; a reset branch is additionally arranged for the peak holding circuit, and the peak output value in the last period is zeroed in the turn-on transient state by using a driving signal, so that the charge accumulation effect is effectively eliminated, and the sampling precision of the system is guaranteed; the regulation and control part of each parallel branch only needs to be additionally provided with two passive elements including the control switch and the capacitor, current sharing control can be achieved by adjusting the access time of the bypass branch, the structure is simple, cost is low, and good popularization applicability is achieved.

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 transient reactive characteristic modeling method for a flexible excitation system under a power grid voltage fault, and the structure and a control block diagram of the system meet the following requirements: a synchronous generator is connected with a three-phase voltage source type converter, the three-phase voltage source type converter is connected with a chopping converter, the chopping converter outputs excitation voltage according to a system control signal, and the excitation voltage is converted into the excitation voltage. Therefore, excitation current is provided for the synchronous machine. The modeling process comprises the following steps: analyzing a synchronous machine equivalent diagram and an AVR control block diagram in the flexible excitation system so as to establish a corresponding mathematical model; then voltage and current parameters of a synchronous machine end of the system in a steady state before a fault are calculated; the transient current caused by the stator voltage change and the excitation voltage change is further solved respectively; and finally, the transient reactive power of the synchronous machine side of the flexible excitation system is obtained. The method provides a theoretical basis for realizing dynamic strong excitation control of the flexible excitation system and improving the stability of the system under a transient condition.