42 results about "Transient stability analysis" patented technology

The invention discloses a series-parallel system transient stability analysis and fault ride-through control method considering current limiting, and belongs to the field of power fault analysis. In order to reveal an action mechanism of a current amplitude limiting and converter coupling effect on the transient synchronization stability of the hybrid system, the method comprises the following steps: firstly, considering the influence of control mode switching of a constructed network type converter, and establishing a transient analysis model of the hybrid system considering a current amplitude limiting link; then, based on a phase plane method, analyzing an action rule of converter control parameters on system transient stability, determining an optimal active power reference value and a saturation current phase angle of the grid-forming converter during a fault period, and proposing a fault ride-through control strategy according to the optimal active power reference value and the saturation current phase angle; and finally, verifying the correctness of theoretical analysis and the effectiveness of the proposed control strategy through multi-working-condition simulation.

The invention relates to the technical field of power system safety assessment, and discloses an optical storage and charging micro-grid power distribution network safety assessment method, system and device based on continuous loading capacity assessment and a medium, and the method comprises the steps: building a probability distribution model of an optical storage and charging micro-grid through data preprocessing; calculating a continuous loading capacity index considering the time sequence characteristics; establishing a power flow model of the power distribution network, and performing voltage, thermal and transient stability analysis; carrying out probability safety evaluation by adopting Monte Carlo simulation; and optimizing the acceptance capability of the optical storage and charging micro-grid based on the security constraint. Accurate and efficient evaluation of the safety level of the power distribution network is achieved, and effective technical support is provided for safe operation of the power distribution network under high-proportion new energy access.

The invention relates to the technical field of power grids, and discloses a power system transient stability simulation sample generation method and device, and the method comprises the steps: obtaining initial samples of a power system in different operation scenes, and the initial samples comprise initial feature vectors and transient stability quantitative indexes; extracting a steady-state feature vector and a preset fault vector in the initial feature vector; based on the steady-state feature vector and the transient stability quantitative index, determining a generation sample type of a sample needing to be generated; determining a preset fault type of the sample needing to be generated based on the preset fault vector; inputting the generated sample type and the preset fault type into a preset generator model, and generating a corresponding first transient stability simulation sample; and combining the first transient stability simulation sample with the initial sample to obtain a second transient stability simulation sample. According to the method, the required transient stability simulation sample of the power system can be generated in a targeted manner, and reliable high-quality sample data is provided for transient stability analysis of the system.

The application discloses a transient stability prevention control measure generation method and a related system, including the following steps: in a predicted fault scenario, a machine learning model is used to predict the transient stability of the current operation mode of a power system, the input of the machine learning model including various electrical characteristics related to the transient stability of the power system; the operation mode predicted as unstable is taken as an explained sample, a model explanation method is used to determine the influence degree of each electrical characteristic in the explained sample on the transient stability; candidate control units are determined according to the influence degree, and the candidate control units are adjusted, and the machine learning model is used to predict the transient stability of the adjusted operation mode until an operation mode predicted as stable is obtained, so that transient stability prevention control measures are generated. The method improves the explainability of the data-driven transient stability analysis model, the overall scheme requires a short time, and is suitable for online application.

The application discloses a network-constructing type VSC transient stability analysis method and system considering internal ring dynamic influence, and comprises the following steps: determining the control system of GFM-VSC, determining active power and virtual power angle based on virtual synchronous power outer ring control; determining port node voltage phase and internal potential amplitude based on the active power and virtual power angle; determining the output current amplitude of GFM-VSC based on the internal potential amplitude and virtual power angle; determining whether the saturation link of GFM-VSC is triggered based on the internal potential amplitude and output current amplitude, and determining the saturation link type when it is determined that the saturation link is triggered; and analyzing the transient stability according to the saturation link type.

The invention relates to a power system Lyapunov function construction method, device and equipment based on an induction motor, and the method comprises the steps: obtaining the electric quantity data of all generator sets in a power system, and obtaining the stable balance data of the power system in a stable balance state; performing model construction according to the electrical quantity data to obtain a transient stability analysis model of the power system; converting the transient stability analysis model according to the stability balance data to obtain a power flow equation; obtaining trigonometric function data and state data from the power flow equation; and according to the trigonometric function data, determining whether to construct according to the state data and the trigonometric function data, and obtaining a Lyapunov function of the power system. According to the method, the power flow equation is constructed by acquiring the electrical quantities and the stability balance data of all the generator sets in the power system, and the Lyapunov function for constructing the power system is determined according to the trigonometric function data and the state data of the power flow equation, so that the accuracy and the applicability of function construction are improved.

The invention discloses a power grid stability analysis and evaluation method based on artificial intelligence, and the method comprises the steps: obtaining sample data, and dividing the sample data into training data and test data according to a preset proportion; establishing a power grid stability analysis model according to the convolutional neural network and setting model parameters; inserting an extrusion excitation module into the convolutional neural network, and adjusting the weight of the feature channel to optimize the power grid stability analysis model; training a power grid stability analysis model by adopting the sample data and the corresponding annotation data; and analyzing the power grid operation data based on the trained power grid stability analysis model, judging whether the power grid is stable or not, and predicting the instability mode of the power grid. According to the method, the artificial intelligence technology and the power grid stability analysis are combined, the defects of a traditional method in the aspects of alternating current power flow reduction accuracy, transient stability analysis efficiency, steady-state operation risk identification, optimization decision automation and the like are effectively overcome, and the accuracy and efficiency of power grid stability analysis are remarkably improved.

The invention relates to the technical field of transient stability analysis of a power system, in particular to a transient stability evaluation method and device for a wind turbine generator, and the method comprises the steps: constructing a full-order model of a control loop of a to-be-evaluated wind turbine generator, and carrying out the transient stability analysis of the full-order model of the control loop; and performing simulation aiming at different voltage sags, different phase-locked loop control parameters, different power grid line impedances and different grid-connected point d-axis current instructions of the to-be-evaluated wind turbine generator, and performing simulation verification on the transient stability of the to-be-evaluated wind turbine generator. According to the derived maximum estimation attraction domain and the property thereof, the transient stability quantitative evaluation index capable of intuitively reflecting the initial state of the transient process of the new energy unit and the boundary of the maximum estimation attraction domain is constructed, and the relationship between the evaluation index value and the state quantity change of the transient process of the unit is qualitatively and quantitatively analyzed; and the transient stability margin of the unit is quickly and visually reflected.

The present disclosure provides a multi-device transient interaction analysis method of a new energy through flexible direct transmission system, relates to the technical field of new energy power system transient stability analysis and discrimination, and comprises the following steps: constructing a system nonlinear mathematical model; constructing a differential equation of the system based on the system nonlinear mathematical model, constructing an objective function to obtain a non-steady equilibrium point of the differential equation; determining a dominant non-steady equilibrium point of the system under fault based on the non-steady equilibrium point; calculating participation factors of different state variables to the dominant non-steady equilibrium point based on the dominant non-steady equilibrium point and a Jacobian matrix of the system; quantitatively analyzing the participation degree of different links or devices in the transient dynamic of the system according to the size of the participation factors, determining the links or devices of dominant transient synchronization, and quantitatively analyzing the interaction size between different links or devices. The present disclosure can practically improve the quantitative calculation ability of the multi-device transient interaction strength of the new energy through flexible direct transmission system.

The invention relates to a tracking-networking type hybrid system transient stability analysis method considering the influence of power coupling and current amplitude limiting, and belongs to the field of grid-connected control technology and system stability analysis. The method comprises the following steps: establishing a tracking-constructing network type converter hybrid system transient analysis model considering current amplitude limiting, introducing a global sensitivity analysis method, quantifying the contribution rate of each variable to the system response variance under the action of multi-parameter coupling, and realizing sensitivity identification of key parameters; based on a power angle characteristic curve and an expansion phase diagram theory, performing qualitative and quantitative analysis on transient response characteristics of the GFM converter in the whole fault process, and revealing a dynamic mechanism of the GFM converter; on the basis of an equal area rule, reasonable approximation is carried out on a damping effect, transient stability calculation is carried out on an established switching system, and a limit cut-off angle of the GFM under the influence of damping and power coupling is obtained through derivation. The method has accuracy and effectiveness under the conditions of different parameter settings and different faults.

The application provides a kind of ship PPL power supply system transient power angle trajectory and stability boundary calculation method, belong to ship power system transient stability analysis technical field, including the construction containing PPL ship power system period variable step length variable order Dormand-Prince analytical model, transient power angle phase space trajectory is described;Constitute Lyapunov periodic index as the criterion of the convergence of system period time-varying state variable, extract state trajectory characteristics and identify the convergence stability, sub-stable and divergent unstable region boundary of system parameter;Based on the criterion, a parameter sensitivity calculation method is proposed, and the multi-time scale parameter characteristics of the system transient phenomenon are quantitatively analyzed.The application adopts the above-mentioned ship PPL power supply system transient power angle trajectory and stability boundary calculation method, which overcomes the limitation of the existing method in dealing with the complex pulse load dynamic characteristics and nonlinear behavior of ship power system, and provides a technical solution for the safe and stable operation of ship power system under pulse load impact.

The application discloses a kind of based on VSC-HVDC AC-DC system transient stability analysis method, first constructs the steady-state model and transient model of AC-DC system based on VSC-HVDC, determines stable equilibrium point before and after fault, then constructs the energy function of AC-DC system based on VSC-HVDC, and based on fault trajectory, determine the maximum value of system energy, as escape point, take escape point as initial value, based on stable boundary tracking determines the norm of reduced system integral process, find out the norm minimum point, take norm minimum point as initial value to determine leading unstable equilibrium point, finally determine the energy at leading unstable equilibrium point, and the energy of this point is as critical energy, determine system limit cut-off time, complete AC-DC system transient stability analysis.The scheme of the application can determine the minimum gradient point and leading unstable equilibrium point in the transient stability analysis of AC-DC system containing VSC-HVDC, improve the precision of direct method transient stability analysis, and is beneficial to the stability of flexible HVDC transmission system.

The invention discloses a transient stability analysis method for a direct-current bus voltage synchronous grid-forming type converter, relates to the technical field of power electronics, and solves the problem that real-time changes of inertia and potential along with frequency in a converter cannot be accurately described due to constant parameters of an existing transient stability analysis method for the grid-forming type converter. According to the method, nonlinear characteristics of variable inertia and variable internal potential are completely fused into an energy conservation framework for the first time, then explicit expressions of kinetic energy, potential energy and damping work are analyzed and derived, and then an implicit stability boundary equation is solved by adopting an iterative algorithm; by fully utilizing the negative feedback convergence characteristic that the frequency-dependent inertia coefficient and the frequency-dependent internal potential are updated along with the state variable, the accurate capture of the critical stable frequency distribution function is realized. According to the method, constant parameter hypothesis limitation is broken through, the deviation between the theoretical evaluation result and the actual stability boundary of the system is reduced, the analysis precision is improved, and a quantifiable theoretical basis is provided for parameter optimization and robust design of the network-forming converter.

This invention discloses a method for transient voltage prediction and stability assessment of DC receiving-end systems based on MCNN-BiLSTM-AM, belonging to the field of transient stability analysis of new energy power systems. The method includes: generating transient voltage stability analysis samples of DC receiving-end systems containing new energy sources; constructing a transient voltage prediction model based on MCNN-BiLSTM-AM; learning and training the transient voltage prediction model based on sample feature acquisition; assessing the transient voltage stability margin of the DC receiving-end system based on the predicted trajectory; and simulation verification of the transient voltage prediction and stability assessment model of the DC receiving-end system. This invention utilizes short-term operational information at the initial stage of a fault to quickly predict the system voltage change trend, and further assesses the system's transient voltage stability margin, thereby achieving rapid and stable analysis of transient voltage prediction and stability of DC receiving-end power systems containing new energy sources.

The application relates to the technical field of new energy power generation transient stability analysis, and discloses a method for quantitatively evaluating the asymmetric fault transient synchronous stability of a grid-connected converter, which comprises the following steps: calculating the initial equilibrium point of a grid-connected converter control system and an unstable equilibrium point during asymmetric fault; substituting the initial equilibrium point into a preset energy function to calculate an initial energy; wherein the energy function is used for representing the transient energy state of the grid-connected converter control system; substituting the unstable equilibrium point into the energy function to calculate a critical energy; calculating the stability margin of the grid-connected converter control system based on the initial energy and the critical energy; and quantitatively evaluating the asymmetric fault transient synchronous stability of the grid-connected converter control system based on the stability margin. According to the application, the positive and negative sequence potential energy, kinetic energy and damping dissipation energy of the grid-connected converter are considered, an energy function suitable for asymmetric fault is constructed, and the transient synchronous stability quantitative evaluation of the grid-connected converter during asymmetric fault is realized.

The invention discloses a method and a device for judging the transient stability of a system under power surplus, which are used for solving the problems that the quantitative calculation of the stability of a new energy flexible direct output system under a power surplus scene is lacked and the online transient stability analysis requirement of a renewable energy power station is difficult to meet in the related technology. The method is applied to a new energy flexible direct transmission system with power surplus caused by single-pole locking. Acquiring initial equivalent reference power, an unstable equilibrium point power angle and a power coupling item of the new energy flexible direct output system; calculating target equivalent reference power according to the power coupling term and the initial equivalent reference power; according to the target equivalent reference power and the unstable equilibrium point power angle, calculating a critical clearing angle in the single-pole locking fault scene when the unstable equilibrium point exists, and calculating critical clearing time according to the critical clearing angle; and performing stability judgment according to the critical clearing time and preset protection action time to obtain a transient stability result of the new energy flexible direct delivery system.

The invention provides a micro-grid transient stability analysis method, device and equipment, and relates to the technical field of transient analysis. The method comprises the following steps: updating a model parameter of each component in a target micro-grid based on operation data of the target micro-grid to obtain an updated model parameter of each component; constructing a system state space model of the target micro-grid according to the operation data of the target micro-grid and the updated model parameters of each component; and in the transient time window, determining the transient sensitivity of each component based on a preset disturbance quantity and a system state space model, and performing transient stability analysis on the target micro-grid by combining the operation data of the target micro-grid and the system state space model to obtain a transient stability analysis result of the target micro-grid. According to the method, the transient sensitivity of each component can be considered during transient stability analysis, so that the accuracy of transient analysis is improved, and the accuracy of a transient stability analysis result is ensured.

The invention discloses a method and system for judging transient stability of a power system, and the method comprises the steps: outputting a time simulation sequence file through time domain simulation, and calculating a key feature value of the time simulation sequence file; dynamically self-defining a stability judgment rule of transient stability of the power system based on a regional power grid demand; and converting the stability judgment rule into an executable code, judging the transient stability of the power system based on the key feature value through the executable code, and outputting a judgment result. According to the method, the efficiency and the intelligent level of a power system planning and operation department in an off-line transient stability analysis link can be remarkably improved, and a more reliable technical support is provided for safe and stable operation of a power grid.

The present application relates to the technical field of power system transient stability analysis, and discloses a generator power angle trajectory prediction method based on a graph embedding physical information neural network, which classifies and divides operation scenarios containing renewable energy uncertainty and fault disturbance through a clustering algorithm, effectively reducing the learning difficulty of complex scenarios; with the strong feature extraction capability of a graph neural network, general node and line features under different power grid topologies are mined, and the model cross-topology generalization performance is improved; and the generator rotor motion equation is embedded as a physical constraint in the training process of the neural network, realizing double-driven optimization of data driving and physical law in the training process. The method can realize fast and accurate prediction of the generator power angle trajectory of a high-proportion renewable energy power system under different topologies and fault scenarios on the premise of ensuring the physical consistency of the prediction results, and provides efficient and reliable technical support for power grid transient stability analysis.

The invention discloses a GFL-VSC transient stability analysis method and system considering LVRT control, and belongs to the technical field of power system safety and stability analysis. The method comprises the following steps: decomposing a full-order model into a low-order fast subsystem and a low-order slow subsystem by using small parameters based on a singular perturbation theory according to a time scale difference between a current loop and a phase-locked loop; in the slow subsystem, solving a nonlinear differential equation of a phase-locked loop by using a multi-scale method to obtain an approximate analytical solution based on initial conditions, system parameters and fault depth, and establishing a stable boundary criterion according to the approximate analytical solution; and in the fast subsystem, establishing a dynamic model comprising a time-varying item, solving to obtain an analytic solution of the dynamic model, and determining the transient stability of the GFL-VSC under the influence of the current loop control parameters according to the stability boundary criterion and the analytic solution. According to the method, the transient stability of the GFL-VSC considering the LVRT control can be effectively analyzed.

This invention discloses a transient stability analysis method and system for a multi-machine grid-connected system. First, a transient model of the system is established, and the stable equilibrium point before the fault is determined based on the power balance equation and the eigenvalues ​​of the Jacobian matrix. Using the stable equilibrium point as initial values, the fault trajectory is calculated, and an interpolation correction algorithm is introduced to eliminate discrete simulation step size errors and accurately locate the point on the fault trajectory where the potential energy derivative changes from positive to negative. Using this point as an initial value, the system iteratively searches for the minimum point of power imbalance along the gradient descent path. Solving the power balance equation using the minimum point as an initial value yields the dominant unstable equilibrium point. Finally, the energy of the dominant unstable equilibrium point is used as the critical energy to determine whether the system is stable after the fault is cleared. The method provided by this invention reduces the conservatism of the traditional energy function method for stability assessment in multi-machine systems, effectively reduces the multi-saddle point interference problem in multi-machine systems, and accurately locates the dominant unstable equilibrium point related to the fault path.

The application relates to a power system transient stability analysis method based on spherical geometry, which comprises the following steps: step 1, dimension reduction processing is performed on a high-dimensional multi-machine power system, and a projection of a global manifold is obtained in a unit projection sphere of a three-dimensional phase space through a shrinkage projection transformation method; step 2, by constructing and observing a geometric distribution condition diagram of SAIs of the high-dimensional multi-machine power system on a sphere, two groups of SAIs about the center symmetry of the sphere can be obtained, and the spherical triangular area SAST of a spherical curved triangular area on the surface of the sphere is defined as an SAI evaluation parameter by using three SAIs on the same half sphere. The application solves the problem that the current power system transient stability analysis method cannot effectively distinguish the stability degree of different fault conditions when the same index appears in different fault conditions, simulation results show that the evaluation parameter has the advantage of higher accuracy, and the transient stability degree of the system can be effectively determined.

The application discloses a limit cut-off angle solving method and device for a heterogeneous network type inverter parallel system, and belongs to the electrical engineering field. The method comprises the following steps: establishing a system equivalent synchronous motion equation according to a droop control and an active synchronous equation of a virtual synchronous generator; establishing system kinetic energy, potential energy and damping work expressions according to the system equivalent synchronous motion equation; solving a frequency about an implicit function of a power angle based on the law of conservation of energy; performing transient stability analysis based on the implicit function to obtain a parallel system stability domain and a post-fault phase locus; and solving a limit cut-off angle according to the stability domain and the post-fault phase locus. The application considers the influence of nonlinear damping and frequency mutation, and can quickly and accurately solve the limit cut-off angle of the heterogeneous network type inverter parallel system.

The invention provides a photovoltaic power generation transient model parameter identification method, and belongs to the technical field of power system control. Comprising the following steps: S1, determining the observed quantity of a model based on the track sensitivity of a to-be-identified parameter; s2, constructing a PSASP and Matlab joint simulation experiment platform, and establishing a photovoltaic power generation transient model by using the to-be-identified parameters, the observed quantity and the PSASP; s3, identifying the to-be-identified parameter by adopting Matlab to obtain an identification value of the to-be-identified parameter; inputting the identification value into the photovoltaic power generation transient model by using a PSASP to carry out transient calculation so as to obtain calculation output data; and S4, based on the calculation output data and the actual measurement data, determining a final identification value of the to-be-identified parameter. Therefore, the parameters of the photovoltaic power generation transient model are accurately identified, the dynamic characteristics of the photovoltaic inverter and the power generation transient characteristics are accurately described, and the precision requirement of large-scale photovoltaic power generation transient stability analysis is met.

The invention discloses a novel power system frequency stability evaluation system considering new energy output characteristics, and belongs to the technical field of power system safety and stability analysis. According to the system, system frequency influence factors, frequency protection fixed values of different types of power generation equipment and system frequency protection defense line configuration conditions are comprehensively considered, a new energy output proportion K is introduced to divide new energy operation states, and a multi-level frequency safety and stability evaluation standard covering low-frequency and high-frequency scenes is established; determining evaluation indexes taking the frequency extreme value and the frequency threshold exceeding duration as the core after the system fault; a typical fault is simulated through a PSASP transient stability analysis module, and the power grid frequency stability level is judged in combination with evaluation criteria and index quantification. According to the method, the problems that the existing frequency instability criterion can only perform qualitative judgment and lacks a clear evaluation system are solved, accurate measurement of the frequency stability level of the extra-high voltage external transmission type power grid is realized, and support is provided for formulating frequency stabilization measures in a targeted manner and guaranteeing safe and stable operation of the power grid.

The invention discloses a transient stability analysis method for a grid-connected system for operation of a mobile box transformer vehicle without power cut, and relates to the technical field of electric power operation, and the method comprises the steps: building a transient model for transient analysis according to the mobile box transformer vehicle and a distribution network line; inputting the transient models of the mobile box transformer vehicle and the distribution network line into electromagnetic transient analysis and calculation software, and building a grid-connected transient analysis model of the mobile box transformer vehicle; analyzing the influence of different switching-on angles and switching-on resistors on the transient characteristics of the user side of the system after grid connection of the mobile box transformer vehicle, wherein the influence mainly comprises an overcurrent multiple, an overvoltage multiple and a total harmonic distortion rate; according to the method, the characteristic parameters reflecting the transient stability, such as the over-current multiple, the over-voltage multiple and the second harmonic distortion rate, of grid connection of the mobile box transformer vehicle are creatively combined, and an improvement measure for optimizing the transient stability of the mobile box transformer vehicle based on the comprehensive characteristic parameters is constructed. And the transient stability of the system after grid connection of the mobile box transformer vehicle is improved.

The invention provides a transient stability margin evaluation method and system for a synchronous network containing embedded direct current, and belongs to the field of transient stability analysis of a power system. The method comprises the following steps: performing Kron reduction on a synchronous power grid containing embedded direct current, and expressing the electromagnetic power of a generator as the sum of an alternating current transmission power item and a direct current injection equivalent power item; the method comprises the following steps of: constructing a single-machine infinite bus system containing embedded direct current, and parameterizing and simplifying a direct current injection equivalent power item to obtain a power angle characteristic equation which can be analyzed and expressed; establishing a power angle characteristic model considering the three stages of steady-state operation, fault period and fault removal; and for the established staged power angle characteristic model, defining a transient stability margin index by adopting an equal area method, and realizing quantitative evaluation of the transient stability margin of the power grid. According to the method, the influence of the embedded direct current on the transient power angle stability of the system can be quantified, and a theoretical basis and engineering guidance are provided for system operation optimization, fault removal strategy formulation and direct current control parameter setting.

The invention relates to a power electronic technology, in particular to an equivalent modeling method for a multi-grid converter grid-connected system under current amplitude limiting, which comprises the following steps of: analyzing the influence of current amplitude limiting on converter operation modes under a fault, and dividing the system into four types of converter groups with different operation modes; identifying transient response key characteristic quantities of various converter groups, providing coherence criteria based on power loss and response similarity, and dividing the various converter groups into different coherence groups; on the premise of ensuring dynamic similarity of converter power, equivalent parameters of all coherence groups are calculated, and an equivalent aggregation model of the multi-network converter system is established. According to the method, the problems of poor adaptability and heavy calculation burden of a high-order model caused by the fact that current amplitude limiting is not considered in a traditional equivalent modeling method are effectively solved, the mode switching characteristic and group dynamic difference of the converter under the fault are accurately captured, a high-precision and low-complexity model support is provided for transient stability analysis of a multi-constructed-network converter grid-connected system, and the method is suitable for popularization and application. And the method has good engineering application value and popularization prospect.

The invention discloses a grid-forming doubly-fed wind power transient stability analysis method considering flux linkage safety constraint, which is characterized in that a transient mathematical model explicitly considering rotor voltage amplitude limiting dynamic state is established, and the transient stability of the grid-forming doubly-fed wind power which is different from the traditional current amplitude limiting is revealed because the flux linkage safety constraint is considered. A novel transient instability mechanism caused by voltage amplitude limiting is triggered; based on the model, the law of the action of the positive sequence virtual impedance and the negative sequence current injection strategy on the critical clearing time is quantitatively determined, and the stability analysis theory of the network construction type doubly-fed wind turbine generator under the specific fault working condition is perfected. And an accurate theoretical basis and engineering guidance are provided for improving the fault ride-through capability and optimizing control parameters.