124 results about "Stability criterion" patented technology

The invention discloses a stability analysis method of a network tracking / constructing hybrid station based on an impedance model, and relates to a modeling and stability evaluation technology of a wind power plant grid-connected system. The method comprises the following steps: firstly, respectively establishing sequence impedance models of a following network type direct-driven fan and a construction network type direct-driven fan based on a harmonic linearization method, and verifying the accuracy of the established models in different frequency bands by combining an impedance sweep frequency method; secondly, on the basis of considering the influence of line impedance, deducing to form an impedance network structure of a hybrid wind power plant grid-connected system, and constructing a stability judgment condition suitable for system analysis; and finally, based on the established impedance stability criterion, identifying possible oscillation risks of the system in subsynchronous and supersynchronous frequency bands. The method is suitable for wind power system stability analysis in various hybrid access scenes, and provides theoretical basis and technical support for subsequent system parameter setting, control strategy optimization and oscillation suppression measures.

The invention discloses a stability criterion method considering a current amplitude limiting link for a network construction type energy storage system, and belongs to the field of stability control of a power system. According to the invention, the problem of virtual power angle switching after current saturation of the grid-forming converter is solved. The equivalent acceleration area and the equivalent deceleration area serve as the reflection of the energy increment and the energy decrement in the transient process of the converter, and the transient synchronization stability of the grid-connected system of the grid-forming type energy storage converter can be conveniently judged by comparing the acceleration area and the deceleration area or comparing the fault cut-off angle and the limit cut-off angle; the research result has a certain significance in improving the stability of the network construction type energy storage equipment.

The invention discloses a digital twinning multi-agent reinforcement learning intelligent decision-making system and method with a secure memory playback mechanism, and the system comprises a digital twinning module which is used for constructing a virtual model and synchronizing the virtual model with a physical entity in real time; the multi-agent reinforcement learning module is used for carrying out strategy learning based on a constrained Markov decision process and balancing performance and safety through a Lagrange multiplier; the safe memory playback module is used for weighting and playing back the experience samples according to the risk and the timeliness so as to improve the learning safety; the reversible grey influence network module is used for causal modeling and reasoning and enhancing decision interpretability; the double-loop self-constraint control module ensures that a control action is always in a physical safety boundary through a barrier function and safety projection; and the convergence and stability criterion module is used for verifying strategy security convergence and system asymptotic stability. According to the method, the problems of strategy border crossing, virtual-real mismatching and the like in the high-risk manufacturing process are solved, and multi-target optimal control under the safety constraint is realized.

The invention discloses a hypersonic flow instability multi-field coupling prediction method and system, and relates to the technical field of modern high-speed aircraft design, and the method comprises the steps: obtaining the multi-physical field parameter distribution of a hypersonic flow field; based on a shock wave-boundary layer interaction mechanism, constructing an instability sensitive graph data structure by taking multi-physical field parameters as input, setting graph nodes in a shock wave influence region, a boundary layer region and an intersection region thereof, and calculating connection weights among the nodes; performing multi-scale decomposition on the instability sensitive graph data structure, and extracting instability modes of a shock wave scale, a vortex scale and a molecular scale; screening the instability modes by adopting a hypersonic velocity stability criterion, and determining a dominant instability mode; and constructing an instability evolution prediction model based on the dominant instability mode, and outputting a spatio-temporal evolution rule of hypersonic flow instability. According to the method, the problem that the flow instability phenomenon in the hypersonic velocity complex multi-physical field environment is difficult to accurately predict can be solved.

The invention belongs to the related technical field of novel power system analysis, and discloses a stability analysis method and analysis system for a multi-following-network-construction-type converter system, and the stability analysis method comprises the steps: calculating admittance matrixes Qeq and Qml used for evaluating the stability of a following-network-type converter; and performing joint diagonalization processing on the matrixes Qeq and Qml to obtain corresponding diagonal matrixes Lambda eq and Lambda ml, extracting diagonal elements of the matrixes to form n groups of characteristic parameters (Lambda i and mu i), judging whether the (Lambda i and mu i XRPC0) are positioned above the critical stability curve of the following grid type converter or not, if so, indicating that the system is stable, and if not, indicating that the system is unstable. Based on the method, the stability criterion of the multi-following-network-construction-type converter system can be simplified, and the influence of different control modes of the construction-type converter on the stability of the following-network-type equipment can be clarified, so that the reactive power control strategy of the construction-type converter can be optimized, and the supporting capability of the construction-type converter on the power grid can be enhanced.

The invention discloses a fast output feedback control method for a networked nonlinear system triggered by a dynamic event. By designing the dynamic gain, the dynamic gain is bounded, tracking error coupling is avoided, and meanwhile, the influence of a nonlinear term containing an unknown quantity and external disturbance on the system is compensated. In addition, a dynamic event triggering mechanism is provided based on the dynamic gain, and dynamic compensation of a triggering threshold value is achieved. And constructing a composite Lyapunov function by recursively constructing a virtual control quantity, and enabling the Lyapunov function to meet a fast finite time stability criterion in combination with parameter design of dynamic gain and nonlinear term power. Therefore, tracking errors are converged to a tight set, and the states of all closed-loop systems and observers are globally bounded. According to the method, rapid finite-time dynamic event triggering output feedback actual tracking control of a non-strict feedback system can be realized, and the method has urgent engineering application requirements and is of great significance in promoting the development of a networked nonlinear system control theory and an engineering technology.

The invention discloses a lightweight piston thermal-structure coupling stability gradient design method, and relates to the technical field of internal combustion engine pistons, and the lightweight piston thermal-structure coupling stability gradient design method comprises the following steps: constructing an asymmetric load adaptive gradient structure, establishing a multi-physical field coupling stability criterion system, and implementing an intelligent response type gradient design process; according to the method, the limitation of traditional symmetric design and static analysis is broken through by constructing an asymmetric load adaptive gradient structure, establishing a multi-physics coupling stability criterion and combining an intelligent response type closed-loop design process based on a convolutional neural network, and the stability of the multi-physics coupling stability criterion is improved by utilizing mechanisms such as negative Poisson's ratio dynamic softening, inertial mass tuned damping and cross-scale interface strengthening. And deformation energy homogenization and dynamic stiffness self-adaptive regulation and control are achieved, the problems of local-overall response mismatch and steady-state-dynamic model disjunction are solved, real-time feedback regulation is introduced for the first time, and the thermal-structural coupling stability of the lightweight piston under the asymmetric working condition is improved through structural function integration.

A robot manipulator has a base; an arm connected to the base via at least a shoulder joint; and a control system with a dynamic stability determination module. The dynamic stability determination module of the control system determines whether a dynamic stability criterion is met. If the dynamic stability criterion is met, the arm is responds compliantly to an applied force; and if the dynamic stability criterion is not met, the control system causes motion of the base in the direction of the applied force.

The invention relates to the technical field of rail transit, in particular to a train dynamics modeling and formation control method based on a physical information neural network, which comprises the following steps: establishing a train longitudinal dynamics discrete model containing Davis resistance, and designing a physical information neural network structure; embedding the physical equation into a network loss function and introducing historical state input to capture time sequence characteristics; in the training stage, coasting area data are preferentially adopted to reduce traction / braking force interference, and resistance parameters and acceleration prediction are dynamically output; the network model is integrated to a model prediction control framework, a distributed controller is constructed to solve an optimal control sequence, and constraint conditions comprise safety spacing and a state updating equation; a heterogeneous train speed transfer function is deduced through frequency domain analysis, a chord stability criterion based on a two-norm upper bound is provided, and it is ensured that disturbance propagation is not amplified. According to the method, the train resistance parameter dynamic identification precision is improved by fusing data driving and a physical mechanism, and high-precision cooperative tracking and formation stability control are realized.

The invention relates to the technical field of servo loading, and discloses a rotating speed control method of a servo loading system, which comprises the following steps: constructing the servo loading system; the servo motor is driven to work at a constant torque; establishing a disturbance estimation model under servo loading disturbance; rotating speed data of the tested motor are obtained in real time, rotating speed errors are input into a speed PID controller, a basic control signal is generated, disturbance compensation and error response are fused, and a master control signal is constructed; pID parameters of a speed PID controller are optimized and adjusted on line through an improved fast exploration random tree algorithm; and fixing the speed PID parameter according to an error stability criterion, keeping the current control output, and readjusting the PID parameter when the disturbance trend changes. According to the invention, the rotating speed control precision and the operation stability of the servo loading system under complex disturbance conditions can be improved.

The invention discloses a compensation parameter self-tuning vibration suppression method for a magnetic suspension bearing system, which belongs to the field of magnetic suspension bearing control, and comprises the following steps: S1, carrying out a pulse excitation experiment on a magnetic suspension bearing-rotor system by using an electromagnetic vibration exciter, a magnetic suspension bearing-rotor system model is obtained through parameter identification of the frequency response function; s2, obtaining a phase compensation angle according to the mapping relation of the frequency response function; and S3, according to the system model, designing a compensation controller based on a second-order generalized integral-synchronous rotating coordinate system, and through the system model, the phase compensation angle and stability criterion self-tuning compensation control parameters, realizing vibration suppression of the magnetic suspension system. The method can effectively suppress unbalanced mass vibration of the rotor, compensation parameters do not need to be tested and calibrated in advance, the self-tuning process is rapid and convenient, and the method is suitable for any multi-degree-of-freedom magnetic suspension bearing-rotor system and has good practical value and economic value.

This invention provides a method for reconstructing actuator faults in a heterogeneous multi-agent integrated energy system, relating to the field of fault diagnosis. The invention establishes a unified dynamic model for the agents; defines intermediate variables and constructs their dynamic equations; builds a global error dynamic system for distributed intermediate observers and agents; derives the stability criterion for the global error system based on Lyapunov stability theory, obtaining the state observer gain matrix for state estimation; loads the state observer gain matrix and the gain matrix for state estimation into each agent; and during the real-time operation of the agents, obtains the current state vector estimate and intermediate variable estimate, and calculates the reconstructed actuator fault value. This invention utilizes an output space coupling mechanism, enabling distributed collaboration between different energy networks without requiring a unified model dimension, thus breaking down the physical barriers to actuator fault reconstruction in integrated energy systems.

The invention discloses an island micro-grid load frequency stability control method considering communication time lag and a virtual inertia link, and the method comprises the steps: firstly building an island micro-grid load frequency control model containing the virtual inertia link, then constructing a Lyapunov functional on the basis, carrying out the derivation of the constructed functional, and carrying out the calculation of the load frequency stability of the island micro-grid. Derivative integral terms are defined by means of a generalized free-weight integral inequality, then a time-delay correlation stability criterion based on a linear matrix inequality is obtained, then the linear matrix inequality under different PI parameter conditions is solved, a maximum allowable time-delay upper limit (MDSM) for ensuring system stability is obtained, the time-delay upper limit is improved, system conservative property is reduced, and the stability of the system is improved. On the basis of the prior art, the robustness of the system is further improved, and the system has a larger stable operation area.

The invention discloses an unmanned aerial vehicle guaranteed performance trajectory control method, and relates to the field of unmanned aerial vehicle tracking control, and the method comprises the following operation steps: S1, carrying out the longitudinal dynamics modeling of a fixed-wing unmanned aerial vehicle; s2, constructing a T-S fuzzy model; s3, a Fuzzy-GCC controller is designed; s4, the LMI of guaranteed performance control is solved; and S5, intelligently optimizing the parameters. According to the unmanned aerial vehicle guaranteed performance trajectory control method, the control models of the fixed-wing unmanned aerial vehicle can be integrated to obtain a unified form, so that the control law design and parameter tuning of the fixed-wing unmanned aerial vehicle are greatly simplified, a complex propulsion system and a longitudinal controller are decoupled through a lookup table, and the control efficiency of the fixed-wing unmanned aerial vehicle is improved. According to the method, the complexity and nonlinearity of the whole model are remarkably reduced while the control precision is kept, a T-S fuzzy model for longitudinal control of the fixed-wing unmanned aerial vehicle is deduced, and a GCC method and a stability criterion thereof are proposed based on the model, so that the global asymptotic stability of the designed nonlinear state feedback controller is ensured.

This invention discloses an active damping control method for bipolar DC distribution systems based on modulus decomposition. It incorporates line coupling into the system's stability criteria and active damping parameter design, deriving the pole-mode transformation matrix of the metal-return bipolar DC distribution system and obtaining a decoupling model of the bipolar DC line in the modulus component space. The modulus models of the source-side converter and load are also derived. Based on the established decoupling model of the bipolar DC distribution system in the modulus component space, an active damping control method based on modulus decomposition is proposed. This invention considers the impact of DC distribution lines on stability, incorporating line coupling into the system's stability criteria and active damping parameter design. The modulus damping control scheme proposed in this invention can more effectively suppress instability caused by the negative impedance characteristics of constant power loads and also provides a basis for parameter adjustment.

The present application belongs to the technical field of power system, and particularly relates to a time-delay power system stability analysis method and system. The method firstly establishes a load frequency control system model including time delay and nonlinear load disturbance, wherein the nonlinear load disturbance is a nonlinear disturbance taking unknown exogenous load disturbance as current and delayed state variable; then an augmented Lyapunov-Krasovskii functional is constructed, and an analysis method based on time-delay dependent matrix free matrix integral inequality and anti-convex combination inequality is adopted to analyze the stability of the load frequency control system, so as to obtain the stability criterion of the load frequency control system. The present application plays an important role in improving the calculation accuracy and time delay upper limit, and is helpful to expand the stable operation area of the power system.

The embodiment of the invention discloses a simulation calculation method and device for a thin shell transient jump behavior, a medium and equipment. The method comprises the steps that a thin shell finite element analysis model is established; performing time sequence simulation analysis on the transient jump behavior of the thin shell, and in each time step, calculating a strain change rate characteristic value spectrum, and obtaining a nonlinear strength index and a local stiffness spectrum radius of each unit; when the non-linear criterion index of the unit is greater than a threshold value and the local stiffness spectrum radius is greater than the threshold value, dividing the unit into an explicit domain unit and improving the calculation precision by adopting a sub-step size control technology, otherwise, dividing the unit into an implicit domain unit; a self-adaptive step length technology is adopted, and the calculation efficiency is improved through large-step-length propulsion; calculating an incremental potential energy function, and judging whether the thin shell is about to enter a deformation bifurcation point or not by adopting a stability criterion; and constructing a deformation tentative displacement vector by adopting the fastest descending direction of the potential energy function, and accurately capturing real physical paths of jumping behaviors under various working conditions.

This invention discloses an asymptotic stability control method for urban expressway convoys based on a distance-information adaptive criterion. Belonging to the field of intelligent convoy control technology, the method includes: collecting the relative distance and speed between the vehicle and the preceding vehicle, as well as the motion state information of multiple preceding vehicles; monitoring the communication link in real time and calculating the signal quality factor of each preceding vehicle; constructing a dual adaptive coupled car-following model, which adjusts the vehicle's acceleration through both distance sensitivity coefficients and information sensitivity coefficients; deriving the asymptotic stability criterion for the convoy in equilibrium state based on the dual adaptive coupled car-following model and calculating stability indices in real time; and executing a hierarchical closed-loop control strategy based on the stability indices. This invention can simultaneously utilize distance-based sensitivity adjustment to ensure short-range safety and dynamically adjust the coordination weights according to signal quality, ensuring the asymptotic stability of the convoy in high-speed flow and complex communication environments.

The application discloses a hypersonic flow instability multi-field coupling prediction method and system, relates to the technical field of modern high-speed aircraft design, and comprises the following steps: acquiring the multi-physical field parameter distribution of a hypersonic flow field; based on a shock wave-boundary layer interaction mechanism, constructing an instability sensitive graph data structure by taking the multi-physical field parameters as input, setting graph nodes in the shock wave influence area, the boundary layer area and the intersection area thereof, and calculating the connection weight between the nodes; performing multi-scale decomposition on the instability sensitive graph data structure, and extracting instability modes of the shock wave scale, the vortex scale and the molecular scale; screening the instability modes by adopting a hypersonic stability criterion, and determining a dominant instability mode; and constructing an instability evolution prediction model based on the dominant instability mode, and outputting the spatiotemporal evolution law of the hypersonic flow instability. The application can solve the problem that the flow instability phenomenon under the complex multi-physical field environment of hypersonic speed is difficult to accurately predict.

The invention relates to the technical field of power grids, and provides a network construction device transient stability evaluation method and system considering damping and current limiting, and the method comprises the steps: based on the actual angular frequency of a virtual synchronous machine, the rated angular frequency of a power grid, and the active reference value of a network construction type inverter converter, combining the transient stability critical condition of the virtual synchronous machine and an energy function, and evaluating the transient stability of the network construction device; carrying out simultaneous solution to obtain a critical fault clearing angle so as to quantify the transient stability of the network construction device; wherein the transient stability critical condition of the virtual synchronous machine is obtained by introducing an equivalent damping deceleration area and incorporating the equivalent damping deceleration area into an equal area rule, and calculation of the damping deceleration area is simplified by analyzing the concavity and convexity of an angular frequency track. The conservative property of a traditional transient stability criterion is effectively reduced, and a more accurate design basis is provided for control parameter setting of the network-forming converter.

The invention discloses a quantitative control method and device for preset time output feedback of a double inverted pendulum system, and relates to the field of automation, and the method adopts a fuzzy logic system and a fuzzy state observer which are respectively used for processing unknown nonlinear dynamic characteristics of the system and estimating an unmeasurable state. In the design process of the controller, a second-order command filter and a backstepping technology are combined, a state quantization mechanism is introduced, and a novel self-adaptive quantization control method is provided. According to the method, the problem of discontinuity of virtual control signals can be effectively solved, and meanwhile control singularity is avoided. By introducing the preset time stability criterion, it is proved that the closed-loop system can achieve stable convergence within the preset time. A simulation result verifies the effectiveness of the control method, which indicates that the method can ensure that the output state of the double inverted pendulum system is converged to an expected precision range within a preset time, and the response speed and the control precision of the system are improved.

The application provides a vacuum mixing process optimization method and system, which comprises collecting mixing container cavity pressure, jacket temperature, material torque, stirring speed, and air extraction flow signal, calculating pressure change rate, torque fluctuation amplitude, air extraction amount per unit time, and pressure fluctuation characteristic quantity, dividing the vacuum mixing process into four stages of initial exhaust, bubble release, viscosity climb, and densification stability; in the initial exhaust section, the vacuum valve opening degree and time length are controlled according to the air extraction amount and the pressure change rate, and the pressure response delay is recorded; in the bubble release section, an air extraction and stop alternating sequence is generated, and the air extraction and stop time length is corrected in combination with the delay; in the viscosity climb section, the target pressure interval is determined according to the torque, temperature, and pressure change rate, and the speed and valve opening degree are cooperatively adjusted to stabilize the pressure; in the densification stability section, a stability criterion is constructed, and the valve opening degree is controlled as needed; when adjacent stages are switched, the target pressure starting point, valve opening degree initial value, speed initial value, and control period of the next stage are corrected according to the end parameters of the previous stage.

The application discloses a kind of single-area PI type load frequency control time-delay power system stability analysis method, comprising the following steps: 1) establish single-area PI type load frequency control power system mathematical model;2) considering the influence of time delay on power system, on the basis of power system mathematical model, establish time-delay power system mathematical model;3) construct Lyapunov functional;4) the derivation of Lyapunov functional;5) the integral term of the Lyapunov functional after derivation is estimated using the first lemma, and the stability of the time-delay power system mathematical model is analyzed using a two-parameter quadratic polynomial function and the Schur complement theorem, to obtain a less conservative stability criterion.The application has the advantages of less conservative, lower analysis process complexity, etc.

The invention relates to the technical field of tunnels and underground engineering, in particular to an analysis method and related equipment for the time-varying stability of surrounding rock of a super-large-depth tunnel, and the method comprises the steps: obtaining engineering geological survey data and engineering design data, constructing a tunnel numerical model, carrying out the crustal stress initialization to obtain an initialized model, and carrying out the initial crustal stress balance processing; clearing the balanced model displacement field to obtain a reference model; configuring an elastic-plastic-viscous constitutive model for the surrounding rock of the reference model, simulating a tunnel excavation construction process, and identifying a plastic yield unit in the model to obtain an excavation simulation result containing plastic unit information; based on the yield state of the plastic yield unit, carrying out real-time dynamic reduction on physical and mechanical parameters of the plastic unit, and judging the stability of the surrounding rock by combining a preset stability criterion to obtain a stability analysis result; and outputting a surrounding rock time-varying stability analysis report. According to the method, the precision of time-varying stability analysis of the surrounding rock of the super-large buried-depth tunnel is improved.

The application provides an inverter droop control method and system, electronic equipment and a readable storage medium. The method comprises: generating an initial curve family of reactive power and voltage on the inverter side based on an established single-machine infinite bus (SMIB) model; screening the generated initial curve family according to a preset power system static stability criterion to obtain a stable region atlas capable of meeting the stable operation of the SMIB model; setting various different droop control curves in the stable region atlas; and determining a droop coefficient range based on the intersection between the droop control curves and the stable region atlas, and performing reactive power-voltage droop control based on the droop coefficient range. The application can accurately identify the stable domain of the reactive power-voltage droop coefficient of the network type inverter in advance and offline by constructing the SMIB model and coupling the inherent mathematical relationship and strict stability criterion.

The application provides a power system transient stability evaluation method and a power system operation trajectory prediction method based on a Koopman operator, the power system transient stability evaluation method comprising the following steps: S1, collecting operation trajectory data of state variables of a power system; S2, using an EDMD method to increase dimensions of the collected state variables to a high-dimensional linear space to approximate an action of the Koopman operator by using a limited-dimensional linear matrix K ; S3, using spectral decomposition of the Koopman operator to locate discrete spectra of stable equilibrium points of the power system, and using characteristics of eigenvalues of the Koopman operator and inverse mapping of dictionary functions to find stable equilibrium points of the power system in an original state space; and S4, based on the obtained stable equilibrium points and analysis of a stable mechanism of a linear system, constructing a power system transient stability criterion, and using the transient stability criterion to judge whether the system is transiently stable after the power system suffers from a large disturbance and collects an arbitrary working point.

The embodiment of the application discloses a kind of simulation calculation methods, device, medium and equipment of thin shell transient jump behavior, method includes: establishing thin shell finite element analysis model;Thin shell transient jump behavior timing simulation analysis is carried out, in each time step It includes: calculating strain rate eigenvalue spectrum, obtaining the nonlinear strength index of each element and local stiffness spectrum radius;When the nonlinear criterion index of unit is greater than threshold value, while local stiffness spectrum radius is greater than threshold value, it is divided into explicit domain unit, using substep control technology, improve calculation precision, otherwise, it is divided into implicit domain unit;Using adaptive step length technology, large step length is advanced to improve calculation efficiency;Incremental potential energy function is calculated, using stability criterion, judge whether thin shell will enter deformation bifurcation point;Using the direction of the fastest direction of potential energy function drop to build deformation trial displacement vector, accurately capture the real physical path of jump behavior under various working conditions.

The application provides a transient synchronous stability dominant bifurcation mode identification method for an inverter grid-connected system, and relates to the field of power systems and their automation, and the steps of the method are as follows: obtaining inverter parameters and power parameters of the inverter grid-connected system and obtaining bifurcation equivalent parameters; based on a stable equilibrium point, obtaining a Hopf complex normal form coefficient real part and a normalized bifurcation parameter according to a generalized swing equation and the bifurcation equivalent parameters; obtaining a limit cycle amplitude according to the bifurcation equivalent parameters, the Hopf complex normal form coefficient real part and the normalized bifurcation parameter; obtaining a transient stability margin according to a geometric distance between a stable manifold at an unstable equilibrium point and the stable equilibrium point; and identifying a dominant bifurcation mode of the inverter grid-connected system according to the limit cycle amplitude and the transient stability margin. The method can effectively improve the efficiency and precision of transient synchronous instability mode identification, realizes quantitative evaluation of the stability margin, and provides accurate transient synchronous stability criteria for power systems.

This invention discloses a method and related device for suppressing oscillations in parallel connection of grid-connected and grid-connected converters, belonging to the field of power grid control technology. The method includes: establishing a system model of a grid, grid-connected converters, and grid-connected converters in parallel connection according to the current grid connection scenario; constructing a sequence impedance model of the grid-connected converter based on the control model of the grid-connected converter; introducing a voltage outer loop bandwidth parameter and constructing a sequence impedance model of the grid-connected converter based on the control model of the grid-connected converter; calculating the equivalent aggregate impedance of the system at the grid connection point based on the sequence impedance models of the grid-connected and grid-connected converters, and establishing a stability criterion based on the real part of the equivalent aggregate impedance; and adjusting the impedance characteristics at the grid connection point by adjusting the voltage outer loop bandwidth parameter of the grid-connected converter according to the stability criterion, so that the positive resistance characteristic of the grid-connected converter cancels the negative damping of the grid-connected converter, thereby achieving oscillation suppression of the parallel connection of grid-connected and grid-connected converters.

This invention relates to a transient synchronization stability analysis method for multi-parallel grid-connected converters. First, within a multi-machine system framework, a grid-connected converter system model considering the coupling effect of the inner loop current and the phase-locked loop is constructed. Then, using the Newton-Raphson method and the equal area criterion, quantitative assessments of the existence of equilibrium points and visual analysis of transient synchronization behavior are achieved, respectively. Next, through an extended application of the Lyapunov direct method, a physically meaningful transient synchronization stability criterion is rigorously derived, revealing the key factors that easily lead to transient synchronization instability and their influencing laws. Finally, time-domain simulations using MATLAB / SIMULIN are performed to verify the accuracy of the proposed method. The proposed transient synchronization instability characteristic description method and risk quantification assessment system have significant theoretical guiding significance for the parameter optimization design of power electronic systems.