176 results about "Grid impedance" patented technology

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 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, 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 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 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.

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 relates to an inertia synchronization PMSG self-adaptive control method based on online impedance estimation, and belongs to the field of new energy grid connection. The method comprises the following steps: S1, constructing an RLS-GA hybrid strategy algorithm to quickly and accurately identify power grid impedance, and determining the strength type of a power grid; s2, establishing a direct-drive fan grid-connected system control strategy, and adopting a power control ring, a current control ring and an inertia transmission control ring at a machine side; the grid side adopts a direct-current voltage synchronous loop, a reactive voltage control loop and a stabilization control loop; s3, linearizing the control equation, and based on a linearized small signal equation, obtaining a state variable of the direct-current voltage synchronous control grid-connected system of the grid-forming type direct-driven wind turbine generator; s4, calculating control parameters of a reactive voltage control loop and a direct-current voltage synchronous loop; and S5, carrying out adaptive parameter setting on an existing permanent magnet fan inertia synchronization strategy so as to adapt to the change of strong and weak power grids and improve the stability performance of the PMSG under different power grid short circuit ratios.

The invention relates to the technical field of new energy power control, in particular to a control method of a network-forming inverter. In order to solve the problem that a traditional grid-forming type inverter can only operate stably in a weak grid environment and cannot adapt to a wide grid intensity working condition, the invention provides a grid-forming type inverter wide grid intensity adaptability control strategy based on equivalent virtual impedance, the equivalent virtual impedance of a voltage loop is improved to be matched with grid impedance, and the grid intensity adaptability of the grid-forming type inverter is improved. Therefore, the grid-forming inverter can stably operate in a strong power grid environment and a weak power grid environment, and is suitable for a power system with high-proportion new energy access.

The present application relates to the technical field of power electronic converter, and discloses a grid-connected inverter multi-parameter online setting method, system, device and medium.The method comprises the following steps: establishing a circuit simulation model of the grid-connected inverter; obtaining the output current of the grid-connected inverter under different grid impedance conditions through the circuit simulation model, and obtaining the target control parameters of the grid-connected inverter under different grid impedance conditions through iterative search of the particle swarm optimization algorithm of the circuit simulation model; performing offline training on the parameter reasoning model through the output current of the grid-connected inverter under different grid impedance conditions and the target control parameters under the corresponding grid impedance conditions; obtaining the output current of the grid-connected inverter in real time, inputting the real-time output current into the trained parameter reasoning model, and obtaining the corresponding target control parameters; and performing online setting on the control parameters of the grid-connected inverter through the target control parameters output by the parameter reasoning model, so that fast setting can be realized.

The invention relates to the technical field of control methods and systems of photovoltaic grid-connected inverters, discloses a control method and system of a photovoltaic grid-connected inverter, and aims to solve the problems of maximum power point tracking, electric energy quality and system stability collaborative optimization of an inverter under a dynamic working condition in the prior art. According to the method and system, multi-dimensional data are collected in real time, and a space-time irradiance map is predicted based on image data; performing disturbance identification on power grid impedance; generating a global maximum power point voltage track in combination with irradiance prediction; and a multi-target model prediction control framework is constructed, and a system model containing power grid impedance is used for prediction. Through adoption of the technical scheme, prospective tracking of the global optimal power point is realized, the characteristics of the power grid are sensed in real time so as to adaptively guarantee the system stability and the electric energy quality, the power benefit, the electric energy quality, the system stability and the service life of devices are cooperatively optimized, and the comprehensive performance and the environmental adaptability of the system are remarkably improved.

The invention relates to a dual-mode seamless switching three-phase grid-connected inverter control system and method. The system comprises a GFL outer loop control module, a GFM outer loop control module, a current inner loop control module, a power grid impedance tracking module, a calculation processing module and a switching buffer control module. The power grid impedance tracking module is used for detecting and calculating power grid impedance Lg in real time; the calculation processing module analyzes the power grid impedance Lg and then generates a switching control instruction group, the switching buffer control module receives the switching control instruction group, and a plurality of change-over switches in the switching buffer control module change states according to instructions so as to select to start a GFL or GFM control path; according to the cooperative working mechanism, the system can automatically and smoothly switch between the following network type control strategy and the construction network type control strategy in real time according to the impedance state of the power grid, so that the adaptability and the operation stability of the three-phase grid-connected inverter under the wide-range power grid impedance change are remarkably improved.

The invention relates to a modeling method, an analysis method, a device and a medium for the overall impedance of a new energy field station containing a network construction converter, and the modeling method is based on a harmonic linearization method, and comprises the steps: carrying out the modeling according to a main circuit equation, a power outer loop and a voltage and current inner loop control equation of the network construction converter; and then the frequency coupling characteristic is combined, the converter and the power grid are regarded as a whole, and the overall impedance model of the new energy grid-connected system containing the network-forming converter is obtained. The method can accurately characterize the overall frequency domain characteristics of the grid-forming converter system under the influence of power grid impedance, and is suitable for stability analysis of a grid-connected system.

The invention discloses a current-limiting control method based on a network-forming static var generator. The current-limiting control method comprises the following steps: inputting an external direct-current voltage, stabilizing the voltage by a capacitor, and then outputting the voltage to an inverter bridge; the inverter bridge generates controllable alternating current through space vector modulation; the inductive filter filters high-frequency harmonic output end voltage; the terminal voltage amplitude and phase are monitored in real time, and current-limiting control is triggered based on the phase deviation between the voltage and the virtual internal potential when the voltage of the power grid drops; the terminal voltage interacts with ideal power grid voltage at a common coupling point through power grid impedance to generate PCC voltage; pCC voltage and output current are detected, and instantaneous power is calculated; the power signal is filtered and de-noised and then a modulation instruction is generated by the current-limiting controller and is fed back to the inverter bridge to form a closed loop. The reactive power supporting voltage is injected preferentially, the voltage drop amplitude is remarkably reduced, the inertia damping supporting capacity of the system is enhanced, power grid fault recovery is accelerated, and meanwhile the voltage instability problem caused by a traditional current limiting strategy is avoided.

The invention provides a power line carrier communication chip function test method and system, and relates to the technical field of communication technology, and the method comprises the steps: constructing a power line channel simulation test platform, and simulating the voltage fluctuation and power rapid switching working condition in an actual power grid through dynamically adjusting the power output and load switching; in the power line channel simulation test platform, the dynamic sudden change process of the power grid impedance is simulated by controlling the change rate of the load current; the method comprises the following steps: generating an interference signal containing multiple times of characteristic harmonics based on a preset harmonic order proportional relation while simulating dynamic sudden change of impedance, establishing an amplitude proportional coefficient between a reference harmonic and a target harmonic, and coordinating and setting the amplitude of each harmonic according to the proportional relation of the corresponding order, so as to simulate the dynamic sudden change of the impedance. A plurality of characteristic harmonics with a predetermined proportional relationship are obtained, and an interference signal is coupled to a power line channel. The method can accurately simulate the severe channel condition of an actual power grid, and accurately evaluates the communication reliability of the chip.

The invention discloses a virtual synchronous generator control method for improving power transmission capability, which is characterized in that the traditional virtual synchronous generator control is composed of a power outer loop and an inner loop formed by voltage and current double closed loops. A reference voltage generated by a power outer loop subtracts a grid-connected point voltage and then is input into a current feed-forward compensation calculation module to generate a current feed-forward compensation value, the current feed-forward compensation value is superposed on a current given value output by a voltage controller, and the superposed value is used as a total current given value of a current controller. Compared with traditional virtual synchronous generator control, the method has the wide-range adaptive capacity of power grid impedance, and the limit power transmission capacity of active power of a grid-connected inverter can be remarkably improved.

The invention discloses a self-adaptive control method and system for high and low voltage fault ride-through of a network-constructed converter, and relates to the field of network-constructed converters. The existing network-forming converter is difficult to consider voltage source characteristic maintenance and current safety amplitude limiting in a fault ride-through period. The method comprises the following steps: acquiring voltage amplitudes of a grid-connected point and an infinite bus before and after a fault, and calculating a ratio of products of the voltage amplitudes to judge a fault state; based on the ratio, the active power before the fault, the power grid impedance and the power angle variation, adaptively calculating an active power reference value; in response to the fault state, a reactive power reference value is calculated with the aim of ensuring that the current does not exceed the safety limit value; and finally, inputting the power reference value to an inherent active-frequency and reactive-voltage droop control ring of the converter to complete fault ride-through. According to the technical scheme, the external characteristics of the voltage source of the grid-forming converter can be kept during the fault period, internal coordination of power support and equipment safety is achieved, and the adaptability and stability of the system under different fault working conditions are improved.

The invention discloses a grid-connected converter stability control method, system, equipment and medium based on voltage and current double feedforward, and belongs to the field of short-time high-frequency energy storage, and the method comprises the steps: collecting the operation data of a grid-connected point, and carrying out the data preprocessing, and obtaining the impedance information of a power grid; constructing a cooperative control model of the voltage feed-forward channel and the current feed-forward channel; establishing a multi-objective optimization function, determining initial parameters of a voltage feed-forward coefficient and a current feed-forward coefficient under the constraint of an objective function, and executing periodic collaborative updating; and outputting the updated feedforward control instruction to the grid-connected converter under a unified time base to complete control. According to the method, the system stability is improved in a weak power grid scene, and oscillation caused by power grid impedance coupling can be effectively suppressed and controlled; through division and cooperation of low-frequency voltage feed-forward and high-frequency current feed-forward, phase compensation and filtering are combined, so that the grid-connected current is cleaner, and the overall electric energy quality is higher; faster and smoother dynamic response is realized by means of hardware parallelism and observer collaboration.

The application discloses a variable-weighting fusion control method based on voltage source and current source double-source fusion, and belongs to the electrical engineering field.The method is realized through the following steps: firstly, a short-circuit ratio is calculated based on grid impedance to obtain a first initial weighting fusion factor of current source type control; secondly, an inertia ratio is calculated based on grid inertia support demand to obtain a second initial weighting fusion factor; then, local sensitivity weights are obtained by derivation of the two initial factors to obtain an initial double-source fusion factor which is self-adaptively adjusted according to grid state; finally, the initial double-source fusion factor is optimized and corrected in combination with node active regulation capacity and operation economy, safety and other strategy factors.The application can self-adaptively adjust the control fusion proportion of voltage source and current source, realizes smooth transition and stable operation of grid-connected inverters under different grid conditions, and improves the stability and self-adaptability under complex disturbance scenarios.

A method (100) of flicker assessment for an electrolysis system, wherein the electrolysis system is connected to an AC power grid via a point-of-connection, comprises operating the electrolysis system in a continuous operation mode (104) and in a switching operation mode (105) and measuring (106, 107), at the point-of-connection, voltage time-series values and current time-series values; determining (108, 109) simulated instantaneous voltage time-series values from a fictitious grid circuit that comprises an ideal phase-to-neutral voltage source, a fictitious grid impedance and a current sink representing the electrolysis system, wherein said measured voltage time-series values and current time-series values correspond to input currents and input voltages of the current sink; and applying (110, 111) said simulated instantaneous voltage time-series values to a flickermeter for determining at least corresponding short-term flicker emission values from each simulated instantaneous voltage time-series, wherein in the continuous operation mode, the electrolysis system is operated (104) while varying (112) an active power consumption of the electrolysis system within an active power range between a minimum active power level and a maximum active power level, and the voltage time-series values and current time-series values are measured (106) during defined equal short-term time periods for consecutive active power operation intervals of the active power range, wherein said minimum active power level corresponds to a minimum continuous operation point of the electrolysis system.

This invention belongs to the field of power system technology, and particularly relates to a power grid impedance simulation device, its design method, and its usage method. The device design includes determining the required component types, obtaining the quantity and electrical parameter values ​​of each component based on actual national standards and the minimum component quantity criterion; implementing on-demand connection of each component, and using a controller to achieve corresponding control to support the simulation and switching of operating conditions with different short-circuit ratios and series complement degrees; setting a switching logic control program in the controller so that when the controller receives a power grid operating condition switching command, it executes the pre-set switching logic control program to achieve the switching of the operating condition corresponding to the power grid short-circuit ratio and series complement degree. This technical solution, through the integrated design of "parameter calculation - hardware topology - logic control," solves the problems of low testing efficiency, poor simulation accuracy, and high cost in existing technologies, providing an efficient, accurate, and economical solution for the adaptability testing of new energy converters under "high-voltage and high-efficiency" power systems.

The invention belongs to the technical field of stable control of a power system, and particularly discloses a power angle compensation-based method for quickly recovering active power after a fault of a network-forming converter, which comprises the following steps of: monitoring a voltage amplitude and a power difference value at a grid-connected point of the network-forming converter in real time; according to the voltage amplitude and the power difference value, identifying whether the network-forming converter is in an unstable state of active power oscillation after the fault is cleared; if the state is identified as an unstable state, calculating a power angle compensation amount used for counteracting power angle deviation caused by a fault based on detected voltage drop information and system impedance parameters; and superposing the power angle compensation value to a power angle generated by a power control ring of the network-forming type converter, and generating a compensated power angle instruction for controlling pulse modulation of the converter so as to realize active power recovery after the fault is cleared. The method can adapt to different power grid impedance conditions, quickly suppress power oscillation and realize quick recovery of active power, so as to improve the transient stability and reliability of a novel power system.

This invention relates to a quantitative evaluation method for the control performance of grid-connected converters from a stability perspective, belonging to the field of power systems. First, based on a single-phase equivalent model of the grid-connected converter, the modulation voltage is solved. The necessary and sufficient conditions for the existence of real solutions are used to derive the power flow solution boundary, and the voltage over-limit boundary is established in conjunction with modulation ratio constraints, defining the theoretical operating domain of the converter. Based on the theoretical operating domain, a small-signal state-space model is established by combining the main circuit topology and the control system. By analyzing the pole distribution of the converter under different grid impedances, its actual stable operating domain is determined. Finally, by calculating the area ratio of the actual stable operating domain to the theoretical operating domain, a quantitative characterization of the converter's control performance under varying operating conditions is achieved. This method constructs the actual stable operating domain of the grid-connected converter and quantifies the control performance using the area coverage ratio index. This provides a quantitative theoretical benchmark for evaluating its robustness in weak grid environments and guiding parameter optimization design.