231 results about "Grid impedance" patented technology

The invention relates to the technical field of energy storage power station combined operation and maintenance management, and provides a virtual power plant-oriented energy storage power station combined operation and maintenance management system, which comprises a dynamic sensing module for acquiring battery cluster temperature difference distribution, power converter switch transient characteristics and grid-connected point harmonic spectrum data of an energy storage power station in real time through a multi-dimensional sensor network; the collaborative decision-making module is used for dynamically generating a cross-station power interaction constraint rule based on the virtual power plant topological structure; the impedance reconstruction module adjusts the equivalent output impedance of the energy storage converter in real time according to the impedance characteristics of the power grid; the state balancing module is used for realizing charge state dynamic balance and power margin collaborative distribution among the multiple energy storage power stations; and the secure communication module is used for ensuring secure transmission of control instructions among the modules by adopting a layered encryption protocol. The operation stability, the power distribution flexibility and the equipment safety of the virtual power plant can be improved, and the service life of the energy storage equipment is prolonged.

The invention belongs to the technical field of optical storage cooperative control, and discloses a new energy grid-connected optimization control method based on an energy storage system, which comprises the following steps: collecting a power grid impedance fluctuation amplitude, a harmonic distortion rate and environment temperature data, obtaining an initial SOC value, correcting the SOC value, calculating an adjustable power margin and a response delay parameter of a photovoltaic unit, and calculating the optimal power grid impedance fluctuation amplitude and the optimal power grid impedance fluctuation amplitude. Generating an efficiency responsibility table; constructing a response cluster, generating a frequency modulation task package, and further generating a three-dimensional efficiency mapping table; the inertia demand is dynamically calculated in combination with the power grid frequency change rate, a responsibility transfer strategy is automatically activated in a high-altitude and high-temperature scene, and an efficiency instruction set is generated; analyzing response deviation by simulating typical disturbance of a high-altitude weak power grid scene, positioning a deviation source in combination with historical data, and dynamically adjusting an efficiency weight correction factor; and updating a responsibility allocation rule of the efficiency responsibility table, disrupting the low-efficiency cluster, and recombining the high-adaptability unit.

The invention discloses a main power grid short-time load prediction method using a hybrid active filter, and particularly relates to the technical field of load prediction. The method comprises the following steps: acquiring active control parameters and passive branch parameters of a hybrid active filter, combining a real-time load fluctuation signal of a main power grid, extracting harmonic suppression characteristics and phase distortion characteristics, and analyzing and generating a time scale compensation factor through a dynamic coupling effect; and constructing a phase correction model based on the transient harmonic residual component and the time scale compensation factor, and performing frequency domain and time domain combined reconstruction on the real-time load fluctuation signal to obtain a corrected load fluctuation characteristic sequence. A short-time load prediction model is calibrated through a collaborative mapping relation, a load power prediction value of a main power grid in a future preset time window is output, a secondary high-frequency interference signal generated by real load fluctuation and filter self-resonance is effectively distinguished, and the problem of coupling interference of harmonic residual components on the load prediction model in a power grid impedance sudden change scene is solved.

The invention provides a power grid connection disturbance observer feedback control method, which belongs to the technical field of power grid connection, and comprises the following steps: detecting power grid impedance parameters by using a multi-frequency harmonic injection technology, designing a disturbance observer algorithm to establish a state equation set, and constructing a nominal inverter model by using a low-pass filter; the total disturbance amount is estimated in real time by comparing the difference value between the actual current output and the nominal model output, a feedback control strategy is constructed, the disturbance estimation value serves as a feedforward compensation signal to be superposed to the current controller output, and disturbance components in different frequency ranges are processed in a classified mode according to disturbance types. A disturbance observer bandwidth parameter and a filter cut-off frequency are set, a disturbance estimation value is compensated to a current control loop in real time through a feedforward compensation signal to suppress the influence of power grid disturbance on the grid-connected current, and the technical problem that it is difficult to accurately estimate and compensate the influence of power grid disturbance on the grid-connected inverter in real time is solved.

The invention discloses an impedance remodeling method for suppressing harmonic oscillation based on a superconducting magnetic energy storage system, and belongs to the technical field of power generation, power transformation or power distribution. The method comprises the following steps: analyzing theoretical characteristics of the superconducting magnetic energy storage system, analyzing mathematical models and working characteristics of an SMES and a storage battery, and carrying out theoretical modeling on the hybrid energy storage system; the method comprises the following steps: performing small signal modeling on a grid-connected converter control system under voltage control type virtual synchronous control, and establishing a grid-connected converter small signal sequence impedance model; a sequence impedance remodeling model is introduced, the influence of the sequence impedance remodeling model on the low-frequency impedance of the virtual synchronous control system is revealed, in order to obtain the optimal sequence impedance of the grid-connected converter, real-time and accurate power grid impedance information is obtained by injecting a multi-harmonic disturbance signal into the grid-connected inverter, and a traditional impedance remodeling strategy is dynamically adjusted according to the information. It is ensured that the system still has good stability margin when the power grid impedance fluctuates in a wide range, and the adaptability of the grid-connected inverter under different power grid working conditions is improved.

The invention discloses a variable frequency driving device energy recovery control system based on direct power supply of a high-voltage power grid, and relates to the technical field of electrical transmission and energy recovery control. Updating the power grid impedance model in real time by using a complex impedance calculation method; load operation state parameters are dynamically adjusted in combination with motor end output power, rotating speed change and torque calculation; according to the method, regenerative energy is accurately calculated, a feedback path is adjusted according to voltage fluctuation and frequency deviation of a power grid, a feedback current fluctuation ratio and a power factor are monitored, a feedback path conduction proportion is optimized in real time, when the current is unstable or the power factor is abnormal, a suboptimal path is automatically switched, and continuous and stable operation of a system is guaranteed; according to the invention, the energy feedback efficiency and the power grid compatibility of the high-voltage power grid variable-frequency driving device are effectively improved, and the method is suitable for energy feedback application of a high-power motor driving system.

The invention relates to the field of power grid simulation, and particularly discloses a control method of an alternating-current power grid broadband oscillation simulation device based on a component physical model, which realizes broadband domain oscillation simulation of an alternating-current power grid based on the component physical model and a notch filter. Specifically, according to the control method of the alternating-current power grid broadband oscillation simulation device based on the element physical model, an adjustable element physical model type and a corresponding impedance parameter serve as input conditions, and a dynamic voltage compensation component excited by power grid impedance is calculated in combination with an adjustable notch filter; and a power grid simulation reference signal is constructed in real time through superposition of an original input reference voltage value and a dynamic voltage compensation component excited by power grid impedance, so that oscillation simulation in a wide frequency domain of the alternating-current power grid is realized.

The invention provides a network construction type energy storage wide short circuit ratio adaptive stability control method and system, and the method comprises the steps: carrying out the calculation based on a power grid energy storage parameter, power grid impedance and energy storage impedance, and obtaining a dynamic short circuit ratio; according to the dynamic short-circuit ratio, switching the power grid operation condition mode to a power grid operation condition mode corresponding to the dynamic short-circuit ratio; in a power grid operation working condition mode, obtaining optimized virtual inductance resistance parameters or frequency-variable admittance regulator parameters; a corresponding control instruction is generated according to the virtual inductance resistance parameters or the frequency-variable admittance regulator parameters, and self-adaptive stability control is completed; real-time identification and dynamic adjustment of the power grid impedance and the energy storage impedance are achieved, traditional fixed parameter control limitation is broken through, the dynamic short-circuit ratio is obtained through calculation, the problem of power angle instability under the wide short-circuit ratio is solved, corresponding switching of power grid operation working condition modes can be conducted based on the dynamic short-circuit ratio, differential control requirements of a weak power grid and a strong power grid are considered, and the method is suitable for large-scale popularization and application. And the full-working-condition adaptive capacity is improved.

The invention provides a grid-connected inverter impedance detection method based on an L-shaped filter, and belongs to the technical field of grid-connected inverter impedance detection. A multi-frequency-point disturbance signal is injected into a preset grid-connected inverter working point, time domain data of inverter side current and common coupling point voltage are collected, fast Fourier transform analysis is carried out on the collected data, amplitude and phase information corresponding to each injection frequency point is extracted, and a frequency domain feature vector matrix is established; and establishing a frequency compensation matrix model to compensate and correct high-frequency band measurement data based on a frequency characteristic attenuation vector, calculating to obtain optimal estimated values of power grid impedance and grid-connected inverter output impedance, performing error analysis and precision verification on an impedance detection result, and outputting a verified impedance parameter value. The technical problem of insufficient power grid impedance detection precision caused by high-frequency band attenuation of the L-shaped filter is solved.

The invention relates to the technical field of electric energy quality management of an electric power system, and discloses an industrial power grid voltage fluctuation suppression method and system, and the method comprises the steps: firstly building a system-level voltage and current forward transmission model composed of a power unit, a filter circuit and power grid impedance which are cascaded; reversely constructing a feedforward controller based on a voltage and current forward transfer model, and generating a main compensation voltage instruction according to the power grid disturbance quantity detected in real time; state parameters of each power unit are obtained, a differential equation is constructed, and a comprehensive real-time health degree index is obtained through fuzzy reasoning; dynamically correcting an equivalent impedance parameter in the forward transfer model by using the index, and calculating a voltage distribution weight of each unit; and decomposing the total compensation voltage instruction into each unit modulation signal according to the weight. Through systematic modeling, intelligent state evaluation and dynamic fault-tolerant distribution, high-speed, accurate and high-reliability suppression of the voltage fluctuation of the industrial power grid is realized.

The invention discloses a virtual power plant system integrating multiple resources and a flexible scheduling method of the virtual power plant system, and relates to the technical field of virtual power plant management. Analyzing photovoltaic fluctuation characteristics, energy storage response capability indexes and stability indexes of the load power data corresponding to various types of data, and performing normalization processing; establishing a resource interaction tensor based on the collected data, fusing the power grid frequency deviation and the line load, and constructing a collaborative optimization model containing time delay compensation; updating the power grid frequency and the line load rate with a fixed time window, dynamically solving the collaborative optimization model, and outputting a load regulation quantity and an energy storage target scheduling instruction; and obtaining the power grid impedance characteristics and load distribution parameters of the area to be loaded with the control instruction, analyzing the scene deviation degree of the area, and correcting the scheduling value based on the scene deviation degree. The scheduling precision is improved, and the complex power grid compatibility is improved.

The invention relates to the technical field of power electronic converters, and discloses a grid-connected inverter multi-parameter online setting method, system and device and a medium. The method comprises the following steps: establishing a circuit simulation model of the grid-connected inverter; output currents of the grid-connected inverter under different power grid impedance working conditions are obtained through the circuit simulation model, and target control parameters of the grid-connected inverter under different power grid impedance working conditions are obtained through iterative search by adopting a particle swarm optimization algorithm through the circuit simulation model; performing off-line training on the parameter reasoning model through the output current of the grid-connected inverter under different power grid impedance working conditions and the target control parameter under the corresponding power grid impedance working condition; acquiring an output current of the grid-connected inverter in real time, and inputting the output current acquired in real time into the trained parameter reasoning model to obtain a corresponding target control parameter; and on-line setting is performed on the control parameters of the grid-connected inverter through the target control parameters output by the parameter reasoning model, so that rapid setting can be realized.

The invention relates to the technical field of self-synchronizing voltage source control, and discloses a balance current controlled self-synchronizing voltage source control method and system. The method comprises the following steps: acquiring and preprocessing operation data of a grid-connected inverter to obtain active / reactive components of voltage and current of a filter element; generating a three-phase terminal voltage instruction of the self-synchronizing voltage source based on the components, and determining a current instruction signal in combination with the grid-connected voltage; a three-phase modulation signal is generated through adjustment of a PIR controller and coordinate inverse transformation, then a filter inductance value is calculated according to the ripple characteristic of the modulation signal and a switching period, a filter capacitance value is determined by combining resonant frequency, and finally accurate control of the self-synchronizing voltage source is realized according to a filter parameter. By dynamically calculating the matching parameters of the filter inductance and the filter capacitance, the active regulation and control capability of the output impedance characteristic of the inverter is enhanced, and the resonance risk during the impedance change of the power grid is effectively inhibited. The technical problem that the stability is limited due to insufficient impedance regulation and control in the prior art is solved.

The invention, which relates to the technical field of distributed power generation, discloses a modularized distributed photovoltaic inverter cluster intelligent regulation and control system comprising an impedance identification module, an impedance control module, a state sensing module, a fault diagnosis and isolation module, a power distribution module and a cluster fault control module. The power grid impedance monitoring module is used for monitoring voltage and current signals of a grid-connected point of the photovoltaic inverter, calculating a power grid equivalent impedance value, an impedance change trend and a harmonic component proportion of the current photovoltaic inverter, and generating power grid impedance information. The impedance identification module and the impedance control module are arranged, adjustment is carried out based on the virtual impedance parameters, the resonance problem caused by power grid impedance fluctuation is effectively suppressed, the situation that grid-connected current distortion affects the electric energy quality is avoided, the photovoltaic inverter cluster stably operates in a power grid impedance change scene, and the power grid impedance change efficiency is improved. And the cluster grid-connected power quality and the adaptability to the power grid environment are improved.

The invention discloses a composite impedance remolding stability improving method based on power grid voltage feedforward, and the method comprises the steps: connecting a low-pass filter in series in a power grid voltage proportion feedforward link, maintaining the power grid voltage feedforward low-frequency harmonic suppression capability, and improving the phase margin of the output impedance of an inverter in a middle-high frequency band at the same time. And a power grid voltage feed-forward branch for eliminating the negative damping influence of the phase-locked loop is added to a public grid-connected point, so that the stability of the grid-connected inverter is improved, the phase margin of the system is greatly improved, and the grid-connected inverter can still keep higher robust stability when the impedance of the power grid is higher. The stability of the grid-connected inverter is improved when the impedance of the power grid changes in a wide range, the quality of grid-connected current is improved, and the problem that the system is faced with instability after the influence of power grid voltage feedforward and PLL is considered under a weak power grid is effectively solved.

The invention discloses a mode switching method, device and equipment of an energy storage converter and a storage medium, and relates to the technical field of power grid control, and the method comprises the steps: obtaining a multi-mode control grid-connected model of the energy storage converter, and the grid-connected model comprises a grid-following type control model and a grid-constructing type control model; based on the grid-connected model, injecting a high-frequency small signal into a power grid through an energy storage converter, and processing the high-frequency small signal by adopting a discrete Fourier transform algorithm to obtain grid-connected point voltage and current response; obtaining a power grid impedance parameter according to the grid-connected point voltage and current response; calculating an operation short-circuit ratio according to the power grid impedance parameter in combination with the actual output power of the energy storage converter and the power grid voltage amplitude; according to the operation short-circuit ratio and the short-circuit ratio threshold value, mode switching is carried out on the following network type control and the construction network type control, and the method can improve the accuracy of mode switching of the energy storage converter.

The invention discloses a multi-station grid-connected configuration method and system mixed with a grid-forming inverter, and belongs to the technical field of power grid electric energy quality control. According to the configuration method, node mutual impedance is decoupled through capacity information of each region node, so that an equivalent power grid impedance model of each region is established, and the system is simplified to solve the problem of key region node stability. Secondly, describing a quantitative relation among equivalent power grid impedance, the capacity and the position of the network construction type converter and the stability margin of the system by using a D segmentation method, and accurately designing a configuration scheme of the network construction type converter under the requirement of determining the stability margin; according to the method, the curse of dimensionality of a multi-station system is broken through, a quantitative basis is provided for the minimum necessary capacity and the optimal position configuration of the network construction type converter under the constraint of the specific stability margin, and the stability of the new energy multi-station grid-connected system under the weak power grid condition is effectively improved.

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 converter control, and provides a self-adaptive virtual impedance optimization method for a grid-forming type energy storage converter under a weak power grid, which comprises the following steps: injecting a multi-frequency-band collaborative disturbance signal into the power grid, acquiring a voltage response signal and a current response signal of the power grid, and carrying out online scanning and identifying the impedance characteristics of the power grid; establishing a power grid impedance model; constructing a real-time digital twinborn model synchronously operating with the physical converter, wherein the real-time digital twinborn model integrates the power grid impedance model and a multi-time scale state space model of the network-constructing type energy storage converter; and downloading the optimized virtual impedance parameter set to the physical networking type energy storage converter for execution, and performing closed-loop control of the adaptive virtual impedance. Therefore, the broadband stability and the dynamic performance of the network-forming type energy storage converter in the time-varying weak power grid environment are improved.

The invention discloses a photovoltaic inverter control parameter optimization and broadband oscillation suppression method based on a seathead whale migration algorithm, and the method comprises the steps: S1, building each subsystem model, and building a sequence impedance model of a photovoltaic inverter; s2, selecting to-be-optimized control parameters in the sequence impedance model, calculating normalized sensitivity at each frequency point by using a multi-frequency-point central difference method, and performing full-frequency-band analysis; the global sensitivity of each control parameter is obtained through a global sensitivity calculation formula, and then the optimization range of each to-be-optimized control parameter is given through the global sensitivity; and S3, on the basis of the optimization range of the to-be-optimized control parameters calculated based on the global sensitivity, optimizing the control parameters by adopting a sedan whale migration algorithm. By adopting the method, the capability of avoiding local optimum and effective convergence is improved, the optimized and given parameter values can be effectively matched with the impedance of the photovoltaic inverter and the impedance of the power grid, and the stability of the photovoltaic grid-connected system is improved.

The invention discloses a power grid impedance identification method based on model reference self-adaption, and belongs to the technical field of electrical engineering. The method comprises the steps of establishing a reference model, and adopting integral control to iterate the reference model. A three-phase grid-connected current estimation value is obtained by establishing a reference model, the three-phase grid-connected current estimation value tracks the sampled three-phase grid-connected current through integral control, and power grid impedance parameters in the reference model are iterated. And when the three-phase grid-connected current estimation value is consistent with the sampled three-phase grid-connected current, the iterative power grid impedance parameter in the reference model is the final power grid impedance identification value. According to the method, active injection harmonic disturbance is not needed, a complex signal processing method is not needed, grid-connected current control is not affected on the basis, and the power grid impedance identification result is accurate.

The invention discloses a computational analysis method applied to high-power power electronic networking equipment, and relates to the technical field of power systems. According to the method, broadband power grid impedance, equipment state and device working condition data are acquired through a sensing layer, and accurate input is provided through layered compression and priority transmission; the cooperative calculation layer introduces a power grid impedance correction coupling interference matrix, establishes an electrothermal coupling loss mapping relation, and realizes coupling interference quantification, loss real-time calculation and full life cycle prediction; the linkage optimization layer constructs a multi-objective optimization function, an optimal control parameter is solved through an efficient algorithm, and a segmented execution strategy is adopted to adapt to different working conditions; the closed-loop feedback layer collects operation feedback data, dynamically updates the model and optimizes the weight, and links fault black-start support and optimal power supply recovery path planning. According to the invention, multi-target collaborative optimization of system stability, operation efficiency, equipment service life and power supply reliability is realized, and technical support is provided for large-scale safe and efficient operation of high-power networking equipment.

The invention relates to the technical field of power electronics and new energy control, in particular to a hybrid inverter collaborative energy management system and method suitable for an optical storage system. According to the system, by constructing an alternating current and direct current side impedance collaborative matching framework, the power grid impedance and the direct current link state are sensed in real time, direct current equivalent impedance and alternating current reactive output are optimized in a collaborative mode, and the frequency domain impedance characteristic of the system is actively reconstructed to suppress oscillation. The invention provides a hybrid inverter collaborative energy management system and method suitable for an optical storage system, which solve or at least alleviate the problem of AC-DC coupling oscillation of the optical storage system under weak power grid and power fluctuation, improve the dynamic robustness, operation efficiency and safety reliability of the system, realize millisecond-level oscillation detection and suppression, and improve the reliability of the system. The energy storage life is prolonged; and the overall energy efficiency is improved.

The invention discloses a VSG deadbeat prediction control method based on impedance identification adaptive compensation, and the method comprises the following steps: collecting the grid-connected point voltage and current of a three-phase grid-connected converter, and converting the voltage and current into corresponding components in a rotating coordinate system; and identifying a power grid impedance parameter based on the component, calculating a system short-circuit ratio, comparing the system short-circuit ratio with a preset threshold value, and selecting a standard predictive control or impedance adaptive compensation mode. In a standard mode, a virtual synchronous generator discretization mathematical model considering system delay is constructed, and first control voltage is generated through dead-beat predictive current control; and in the compensation mode, self-adaptive compensation of a power grid impedance parameter is introduced on the basis of the first control voltage, a final control voltage is obtained, a PWM driving signal is generated according to the final control voltage, and grid-connected operation of the converter is controlled. According to the method, dead-beat predictive current control and a virtual synchronous generator technology are combined, a power grid impedance identification and self-adaptive compensation mechanism is added, and self-adaptive high-performance control of the converter under strong and weak power grid conditions is realized.

A system, device, and method for an energy system includes one or more modules configured to connect to a power grid. Each module outputs a respective voltage and / or current waveform to a load. A controller is configured to periodically cause at least a portion of the one or more modules to output increased voltage and / or current levels at specified harmonic frequencies. An islanding detector is configured to detect when one or more modules are in an islanding condition based on grid impedance.

The invention discloses a static var generator (SVG) additional dynamic damping-based broadband oscillation suppression method, which comprises the following steps of: acquiring three-phase voltage of an SVG machine end; according to the three-phase voltage, an oscillation frequency and an oscillation amplitude are obtained; performing band-pass filtering on the dq-axis voltage corresponding to the three-phase voltage according to the oscillation frequency; obtaining phase deviation introduced by band-pass filtering, and performing phase correction on the dq-axis voltage corresponding to the three-phase voltage; performing gain adjustment on the dq-axis voltage after phase correction to obtain a dq-axis current reference value under the oscillation frequency; and according to the dq-axis current reference value under the oscillation frequency, superposing the dq-axis current reference value with the dq-axis current reference value of the SVG to obtain a total reference value for controlling the dq-axis current. Positive damping in a wide frequency band of the power grid can be effectively enhanced, the impedance characteristic of the power grid is optimized, broadband oscillation of the system is suppressed, and the safety and stability of power grid operation are improved.

The invention belongs to the technical field of power systems, and particularly relates to a power grid impedance simulation device, a design method and a use method.The design of the device comprises the steps that the types of needed components are determined, and the number of the components and electrical parameter values are obtained according to the actual national standard in combination with the minimum component number criterion; all components are connected according to needs, and a controller is adopted to realize corresponding control so as to support working condition simulation and switching of different short circuit ratios and series compensation degrees; a switch logic control program is set in the controller, so that when the controller receives a power grid working condition switching instruction, switching of working conditions corresponding to the power grid short-circuit ratio and the series compensation degree is achieved by executing the preset switch logic control program. According to the technical scheme, through the integrated design of parameter calculation, hardware topology and logic control, the problems of low test efficiency, poor simulation precision and high cost in the prior art are solved, and an efficient, accurate and economical solution is provided for the adaptability test of the new energy converter under a double-high power system.

The invention discloses an automatic frequency modulation energy storage control method and system based on PCS power regulation, and belongs to the technical field of power system automation control, and the method comprises the steps: obtaining a voltage sampling sequence and a current sampling sequence of a PCS AC side port, and calculating a power grid side fundamental frequency equivalent impedance initial value; a preset high-frequency disturbance signal is injected into the PCS power output end, the fundamental frequency equivalent impedance initial value of the power grid side is corrected, and a real-time power grid impedance parameter is obtained; determining a target adaptive gain coefficient from a preset gain mapping table according to the combination of the real-time power grid impedance parameter and a preset virtual output impedance parameter; inputting the power grid frequency deviation value and the target adaptive gain coefficient into a frequency modulation power calculation function to obtain a PCS target active power regulation quantity; inputting the PCS target active power adjusting quantity into a PCS power control loop, and controlling the PCS to output AC side active power equal to the PCS target active power adjusting quantity; according to the invention, the frequency modulation response precision is improved.

The invention discloses an inverter extremely weak power grid grid-connected control method based on a loop decoupling phase-locked loop, and the control method comprises the steps: firstly collecting related voltage and current, and obtaining a voltage component under a two-phase static coordinate system through Clark transformation; inputting the voltage component into a loop decoupling phase-locked loop to obtain a voltage phase angle; a grid-connected reference current is obtained based on the voltage phase angle, and a reference voltage is obtained through a grid-connected current controller; and finally, through VSVPWM modulation, a switching device is driven to realize grid-connected control. According to the loop decoupling phase-locked loop, an auxiliary transfer function is constructed for a transfer function of a traditional phase-locked loop by adopting a multiplication inverse element method in a pre-compensation link, so that the transfer function of the phase-locked loop is irrelevant to the bandwidth of the designed phase-locked loop, and a third-order complex vector filter is introduced on the basis, so that the harmonic suppression capability is improved. Therefore, according to the method, decoupling of the phase-locked loop bandwidth, the current loop and the power grid impedance is achieved, the application range of the power grid impedance is further widened, and the robustness of the inverter system is improved.

The invention discloses a pre-oscillation stability monitoring active damper for a grid-connected power electronic system, and belongs to the technical field of power electronics. Comprising the steps that a direct-current voltage control loop stabilizes energy storage; the stability monitoring loop calculates power grid impedance and inverter impedance based on fundamental wave separation and FFT (Fast Fourier Transform) through phase-locked synchronous broadband pulse disturbance injection, and generates an activation signal by utilizing an MPC criterion; the damping control loop starts the virtual resistor according to the activation signal, and the virtual resistor is dynamically adjusted through closed-loop optimization, so that the stability margin of the system is close to a critical value. Interference before oscillation is achieved, the problems of response delay, high energy consumption and poor compatibility of a traditional scheme are solved, simulation shows that the harmonic suppression response time is smaller than or equal to 20 ms, and THD is reduced to 0.57%.