47 results about "Differential algebraic equation" patented technology

The invention discloses a multi-converter parameter collaborative optimization method for improving the small interference stability of an active power distribution network, and belongs to the technical field of power systems, and the method comprises the steps: building a differential algebraic equation model, and carrying out the linearization of a steady-state operation point, and obtaining a state space model; and a control parameter optimization problem taking the minimization of the spectrum intercept construction as a target is defined, and control parameters are a GFL converter phase-locked loop parameter and a GFM converter virtual damping parameter. First-order sensitivity and second-order sensitivity of eigenvalues to control parameters are calculated based on a matrix perturbation theory and are converted into local quadratic constraint sub-problems. And performing convexity solution by adopting a positive semidefinite relaxation method, adjusting the step length in combination with a line search mechanism, iteratively updating control parameters, and outputting an optimization result after a convergence condition is met. According to the method, the spectral intercept is reduced through multi-converter parameter collaborative optimization, and the weak stability characteristic is improved; the convergence and solvability are improved by utilizing matrix perturbation and positive semidefinite relaxation; and the stability is enhanced and optimized by adopting line search step length adjustment.

The invention discloses a deep and far sea wind power time-varying impedance model grid connection analysis method based on a time domain residual error method, relates to the technical field of power system modeling simulation, and can efficiently and accurately analyze deep and far sea wind power grid connection. The method comprises the following steps: establishing a differential algebraic equation set containing high-capacity submarine cable impedance and a plurality of nonlinear links, and constructing a recursive coefficient matrix; dividing a preset global time domain into a plurality of time domain subintervals, and solving the recursion coefficient matrix in each time domain subinterval by referring to a universal analytic solution represented by a power series explicit operator to generate a global time domain explicit solution corresponding to the preset global time domain; performing discrete Fourier transform on the global time domain explicit solution to obtain a time-frequency domain spectrum result; and constructing a time-varying impedance model according to the differential algebraic equation, setting the time-varying impedance model by adopting a time-frequency domain spectrum result, and analyzing the deep and far sea wind power grid-connected control system by utilizing the set time-varying impedance model.

The invention relates to the field of electric power, discloses a thermal power generating unit APS automatic start-stop full-process control method and system, and is used for solving the contradiction among safety, economy and rapidity of a traditional APS system. The method comprises the steps of establishing a differential algebraic equation system based on unit physical parameters to generate a unified model constraint set; generating a reference trajectory representing energy conversion efficiency and power in a differential flat space according to the start-stop target curve; predicting a thermal stress change rate through a fractional order differential operator based on the metal temperature to generate a safety margin instruction; generating an energy coordination correction instruction according to the Hamiltonian energy network balance point of the boiler heat storage and steam turbine kinetic energy solving port; and mapping the reference trajectory into a control instruction, integrating thermal stress constraint and energy coordination correction, and then distributing and executing. Safe and efficient start-stop control under full-process physical constraints is achieved, start-stop safety and economy are improved, and the service life of equipment is prolonged.

The invention relates to the technical field of power system simulation, and discloses a power system time sequence simulation system considering security constraints. The system comprises a power grid topology analysis unit, a dynamic security domain calculation unit, a time sequence constraint modeling unit, a simulation track generation unit and a check feedback unit. The power grid topology analysis unit obtains element connection relations and electrical parameters, and generates a topology description file containing a node admittance matrix; the dynamic safety domain calculation unit obtains the voltage stability limit and the power angle stability boundary of each working condition, and forms a safety domain boundary set; a time sequence constraint modeling unit combines the set with a predefined time interval to build a security constraint time sequence model containing a transient process; the simulation trajectory generation unit solves a differential algebraic equation set by using an implicit trapezoidal integral method, and outputs a state variable trajectory with a timestamp; and the check feedback unit compares the track with the security domain boundary, marks an abnormal segment and generates a correction instruction. The system realizes fusion of security constraint and time sequence simulation.

The invention provides a dynamic grouping method and device for a heterogeneous direct current delivery system, and relates to the technical field of dynamic analysis and control of a power system, and the method comprises the steps: deducing a linear time-varying variation equation which is satisfied by the trajectory sensitivity of a system state trajectory to a system parameter vector based on a parameterized differential-algebraic equation model; calculating the track sensitivity of each device to a system parameter vector, projecting the track sensitivity to a common connection point corresponding to each device, and constructing a unified sensitivity feature vector of each device; calculating the dynamic similarity between the devices based on the unified sensitivity feature vector, and constructing a mixed similarity matrix in combination with the electrical distance similarity between the devices; and feature decomposition and feature vector clustering are carried out based on the mixed similarity matrix, and dynamic clustering of heterogeneous equipment is realized. According to the dynamic grouping method provided by the invention, unified grouping of heterogeneous equipment such as a synchronous machine and a converter can be realized in a heterogeneous power system containing high-proportion new energy and direct-current power transmission.

The application relates to the technical field of power electronics, and discloses a press-contact type IGBT device packaging structure optimization method and system. The method comprises the following steps: constructing an equivalent model of a press-contact type IGBT device; constructing a differential algebraic equation for uniformly describing the equivalent model of the press-contact type IGBT device and circuit port variables; converting the differential algebraic equation into a nonlinear algebraic equation group through time domain discretization, and constructing an iteration matrix with a global state vector as a derivation object according to a solving mode of the nonlinear algebraic equation group; performing low-dimensional subspace projection on the iteration matrix based on a Krylov subspace, and combining residual minimization to solve a linear subproblem of the iteration matrix, so that current uniformity characteristic results of the press-contact type IGBT device are obtained; and the packaging structure of the press-contact type IGBT device is optimized based on current density distribution reflected by the current uniformity characteristic results. The application can improve the current uniformity and operation reliability of the system.

The invention discloses a multi-stage separation unit initialization method and system based on a virtual transient model and application, and relates to the technical field of chemical process simulation, and the method comprises the steps: constructing a virtual transient differential equation of a multi-stage separation unit; constructing a virtual differential variable associated equation of the multi-stage separation unit; constructing a virtual transient model of the whole tower of the multistage separation unit; solving the virtual transient model; and outputting the initial estimation value. According to the multi-stage separation unit initialization method and system based on the virtual transient model and the application, when a dynamic process differential algebraic equation model is constructed, the use of a complex hydraulics association formula and structural information of the separation unit is avoided, the time-varying item is virtual, the method does not need to be based on a real physical process, and the time-varying item is saved. However, the integral is completely equivalent to the algebraic equation model when reaching the steady state, so that the initialization process of the multi-stage separation unit based on the virtual transient model is easier to solve, and the method has the advantages of high calculation efficiency and higher robustness.

The invention discloses a distributed photovoltaic aggregation frequency modulation standby optimal configuration method considering node frequency security constraints under transmission and distribution cooperation. The method comprises the following steps: describing uncertainty of photovoltaic aggregation frequency modulation capability by using a Gaussian mixture model, and establishing a power transmission network node frequency response model containing frequency space distribution characteristics; taking minimization of system power generation and frequency modulation reserve cost as a target, and combining opportunity constraint planning to construct an optimal configuration model; a response model is reduced based on a frequency divider theory, a Bernstein polynomial approximates frequency dynamics, and a differential algebraic equation is converted into an algebraic equation; then, binary expansion and Gaussian mixture model linear invariance are utilized to convert the model into a mixed integer linear programming model, and Bernstein polynomial convex hull property tightening constraint is combined; and finally, solving the model to obtain the optimal photovoltaic aggregation frequency modulation reserve capacity and control parameters. The frequency space distribution is accurately described, the problem of insufficient frequency safety risk identification is solved, and the frequency safety level of a power system is improved.

The application discloses a multi-region frequency safety unit scheduling method and device based on Bernstein polynomials, and the method is based on the optimal distribution of the dynamic primary frequency modulation response of a synchronous generator, a speed governor dead zone and a frequency modulation backup, and a multi-region frequency response model is constructed; the integral-differential algebraic equation of the multi-region frequency response model is approximated through Bernstein polynomials to obtain an algebraic expression of the multi-region frequency dynamics, and a multi-region frequency safety constraint is constructed according to the algebraic expression; the multi-region frequency safety constraint is embedded into a unit combination problem to construct a multi-region frequency safety constraint unit combination model; through a self-adaptive double-layer decomposition algorithm, a mixed integer programming problem of the multi-region frequency safety constraint unit combination model is decomposed into a main problem and a sub-problem; and through solving, a multi-region frequency safety unit scheduling scheme is obtained. The application accurately captures the frequency dynamic difference between regions and improves the frequency safety of a high-proportion new energy power system.

The application provides a multi-inverter hybrid system transient stability boundary delineation method based on reverse integration, and belongs to the field of electrical engineering. The delineation method combines a circuit model of a grid-constructed inverter, a grid-following inverter and an infinite grid hybrid system and a virtual synchronous machine mathematical model of the grid-constructed inverter, derives a second-order differential-algebraic equation set of the hybrid system, further obtains system steady-state equilibrium points by solving the equation set and classifies, and reversely integrates from the type I unstable equilibrium point to obtain a transient stability boundary of the hybrid system. The application is simple and intuitive, has a solid theoretical basis, can quickly and accurately identify the transient stability boundary of the grid-connected inverter system, and has important significance for analyzing the transient stability of the multi-grid-connected inverter hybrid system.

The invention provides an electric power system step backspacing simulation method and system considering switching events, and belongs to the technical field of electric power system electromechanical transient simulation, and the method comprises the steps: executing transient simulation step by step, carrying out the alternate iteration of a differential algebraic equation set, scanning the switching events of a DC system in the iteration process, scanning other switching events after the iteration convergence, and carrying out the step backspacing simulation. Whether step backspacing needs to be carried out or not is checked according to a backspacing criterion of the step backspacing strategy; if so, carrying out a rollback operation and adjusting the simulation step length according to a rollback simulation strategy; switching the scanned switching event, and keeping the state variable of the system unchanged after the switching is completed; according to the scheme, whether the next step of simulation continues to be executed or not is checked, if simulation continues to be executed, the step length of the next step needs to be adjusted according to the criterion of step length increase and step length decrease, and the scheme has good technical compatibility and also has excellent expansibility.

A system for solving nonlinear problems in implicit differential equations comprises hardware processors that transform differential equation systems into a unified canonical form enabling efficient numerical solving across multiple integration methods. The processors represent differential equations in a reduced canonical form G(x; v1, v2, γ, c)=v1+Mx−γ(h) f(x+v2, tn+ch) incorporating solution vectors, integrator parameters, mass matrices, and time parameters. The system generates model-specific mapping functions N(x)=y and N−1(y, γ, v1, v2)=x that transform between differential algebraic equation states and compressed nonlinear solver states, eliminating algebraically redundant variables through symbolic analysis. This compressed representation reduces computational complexity from O(n3) to O(m3) where m<n, while integrator-specific functions v1, v2, and γ(ρh) encode method-specific discretization parameters.

A kind of electromechanical coupling dynamics modeling method of electric vertical take-off and landing aircraft based on differential algebraic equation belongs to electric vertical take-off and landing aircraft technical field.First, the motor dynamics equation in eVTOL electric propulsion system is established according to motor parameters;Second, according to the geometric configuration and inertia parameters of eVTOL, the dynamics equation of fuselage multibody system is established, and the aerodynamic model is applied;Third, the motion driving equation is used to couple based on the general mechanical load calculation scheme of Lagrange multiplier;Finally, the electromechanical coupling dynamics model of eVTOL is established, which is discretized by trapezoidal-Newmark hybrid discrete format, and efficient solution is realized based on Newton iteration method, and it is verified by eVTOL vertical take-off.The invention avoids the defects of traditional simplified model ignoring motor transient characteristics and non-coupling modeling without real-time load feedback, improves the motion response and energy consumption calculation accuracy, and provides reliable dynamics modeling basis for eVTOL energy consumption optimization and commercial design.

A four-step method for identifying parameters of a lithium battery equivalent circuit model based on differential algebraic equations is disclosed. In the method, an equivalent circuit model of a lithium battery is selected and a differential algebraic equation is established. A loss function is constructed according to the equation and the voltage and current values at the terminals of the battery, and relevant constraint conditions and initial values of the identification parameters are determined. A system of ordinary differential equations is solved, the loss function is calculated according to the solution and the voltage and current values at the terminals of the battery, the partial derivatives of each independent variable of the loss function are calculated, and the identification parameter values of the next iteration are obtained by substituting the partial derivatives into the gradient descent method. The iteration is repeated until the minimum value of the loss function is obtained, and the volt-ampere characteristics and state of charge of the lithium battery are predicted according to the identification parameter values. This method establishes a mathematical model, constructs a loss function, and uses a gradient descent optimization method and a numerical solution method to identify the parameters of the lithium battery equivalent circuit model, which can fit the entire charging and discharging process, has a faster convergence speed, and has high accuracy in predicting battery performance.

The invention provides a method for depicting a transient stability boundary of a multi-inverter series-parallel system based on reverse integration, and belongs to the field of electrical engineering. According to the depicting method, a circuit model of a network building type inverter, a circuit model of a network following type inverter and an infinite power grid series-parallel system and a circuit model of a network building type inverter virtual synchronous machine mathematical model are combined, a second-order differential-algebraic equation set of the series-parallel system is obtained through derivation, and system steady-state balance points are obtained and classified by further solving the equation set. And carrying out reverse integration on the I-type unbalanced stable point to obtain the transient stability boundary of the series-parallel system. The method is simple and visual, has a solid theoretical foundation, can quickly and accurately identify the transient stability boundary of the grid-connected inverter system, and has important significance for analyzing the transient stability of the multi-grid-connected inverter series-parallel system.

The invention discloses a micro-grid linearization model order reduction method, system, equipment and medium, and belongs to the field of micro-grid stability analysis and control. Models of all elements in a micro-grid are obtained, a nonlinear differential algebraic equation set is established, a stable equilibrium point of the nonlinear differential algebraic equation set is solved, linearization processing is carried out, and a linearized differential algebraic equation set is obtained; solving a rightmost characteristic value by adopting a characteristic value algorithm, if the system is not stable, performing leftward translation transformation on the system to stabilize the system, generating a Lyapunov equation according to the translated system, solving a controllable and observable Gramb matrix by adopting a Krylov subspace algorithm, and performing order reduction on the translated system by adopting a balanced truncation method to obtain a stable system; according to the method, an existing balance truncation method is improved, the precision, the stability, the controllability and the observability of a system after order reduction are guaranteed, meanwhile, the Grubrum matrix can be efficiently solved, and the method is made to be suitable for an unstable system.

The invention relates to an inverter grid-connected parameter stability domain identification method and device based on bifurcation characteristics, and the method comprises the steps: building a generalized swing equation based on differential algebraic equations of different inverters; deducing a unified standard form and equivalent parameters suitable for bifurcation analysis; systematically analyzing boundary conditions of generalized saddle node bifurcation, Hopf bifurcation and homoclinic bifurcation, and constructing region division with different dynamic behaviors in a parameter space; and based on system balance points and manifold characteristics in different regions, and in combination with a Melnikov function analysis result, stability domains under inverter control parameters and electrical parameters are accurately identified. According to the method, a nonlinear dynamics principle is utilized, bifurcation boundary conditions of an inverter grid-connected system are deduced, typical areas with different dynamics structures in a parameter space are constructed, parameter stability domains under different operation working conditions are further identified, the multi-parameter stability problem of a complex system can be reduced to boundary judgment of a few key parameters, and the stability of the inverter grid-connected system is improved. And the stability domain identification efficiency and precision are greatly improved.

A tractor-trailer system pose derivation method, a tractor-trailer system, and a computer-readable storage medium. The method includes: determining an initial pose state of a tractor-trailer system; obtaining a real-time position of the tractor of the tractor-trailer system, and determining the real-time position of the tractor as a target position; obtaining a linear speed and a steering rudder angle of the tractor by processing the initial pose state and the target position using a preset trajectory tracking controller; and obtaining a target pose state of the tractor-trailer system by processing the initial pose state, the linear speed, and the steering rudder angle using a preset differential algebraic equation solver. In this manner, the, the poses of the tractor-trailer system can be accurately deduced, thereby facilitating the application of autonomous driving technology in the tractor-trailer system.

The invention discloses a multi-stage separation process simulation efficient DLPT general solving method and system and application, and relates to the technical field of chemical process simulation, and the method comprises the steps: obtaining the initial condition of a multi-stage separation differential algebraic model; determining simplified physical property model parameters according to the initial conditions; performing iterative solution on the differential algebraic equation set based on the simplified physical property model parameters and an integral algorithm; and outputting a final calculation result. The efficient DLPT general solving method and system for simulating the multi-stage separation process and the application have the advantages that the PT algorithm is low in initial value requirement and wide in convergence domain, the inner-layer strategy and the outer-layer strategy are introduced, a simplified physical property model is used in the inner-layer integration process, calculation time consumption is greatly shortened, the inherent speed bottleneck problem of the PT algorithm is solved, and the calculation efficiency is improved. And the balance between convergence robustness and calculation efficiency is realized.

The invention discloses a virtual synchronous machine parameter optimization method and a related device, and belongs to the field of power system control parameter optimization, and the method comprises the steps: firstly obtaining a related model and parameters of a virtual synchronous machine, and building a differential algebraic equation representing the dynamic characteristics of a micro-grid before disturbance; then solving a stable equilibrium point, carrying out linearization processing on the differential algebraic equation at the equilibrium point to obtain a small-interference stability analysis model, and solving a characteristic value and a damping ratio of the small-interference stability analysis model; determining a micro-grid model after large disturbance and disturbance removal, and performing transient stability evaluation; and finally, constructing an objective function and a constraint condition of parameter optimization considering small interference and transient stability, and obtaining an optimized inertia coefficient and a voltage integral coefficient. In addition, the damping coefficient and the reactive droop coefficient are determined according to the requirements of the micro-grid for the variation range of the frequency and the voltage and economic operation. According to the method, the micro-grid can be ensured to have relatively good small-interference stability and transient stability at the same time.

The application provides a power supply system key equipment fault diagnosis method based on digital twinning, first, according to expert knowledge and a design scheme, modeling of power supply system key equipment is carried out, fault mode analysis is carried out, and a fault behavior twinning model is established, and experimental results prove that the twinning modeling method is effective, and the expected result is better adapted. Then, by adding random noise, the actual operation is better simulated, and the twinning modeling of the fault behavior dimension is successfully realized. The application also takes the data set generated by the fault behavior twinning model as the basis, analyzes the transient stability of the system key equipment, obtains a differential algebraic equation capable of describing physical information, combines the differential algebraic equation with a neural network loss function, and the construction of PINN is completed with a relatively ideal effect, and after 400 times of training, the training error reaches the order of magnitude of 10 ‑3 .

The application relates to the technical field of electric propulsion digital twin simulation, and discloses an electric propulsion digital twin simulation data reduction method, which comprises the following steps: acquiring simulation data of electric propulsion plasma; based on the simulation data, snapshot data is extracted in a grid unit of a calculation domain; singular value decomposition is performed on the snapshot data, a reduced orthogonal basis is established, and reduced data representation is obtained through projection; based on a plasma fluid control equation, a semi-discrete ordinary differential algebraic equation group is constructed, and a coefficient matrix of a reduced model is determined through least square fitting; real-time simulation of an electric propulsion digital twin system is performed by using the reduced model, and field data is output. According to the application, the calculation precision and the simulation result obtained by PIC / MCC simulation are in the same order of magnitude, the calculation time reaches the level of seconds, and the real-time simulation demand can be met.

The invention discloses a new energy equipment low-voltage ride-through transient synchronous stability analysis method based on an improved equal-area principle. The method comprises the following steps: performing transient modeling on a new energy grid-connected system considering a complete low-voltage ride-through process; solving a stable working point of the system at the stage 1 and an unstable equilibrium point of the system at the initial moment of the stage 3; normalizing the differential algebraic equations at the initial moments of the stage 2 and the stage 3 into the form of a generalized swing equation, and solving each equivalent coefficient; at the initial moment of the stage 3, the critical cutting angle of the system is calculated through the first-time equal-area approximation principle, the second-time equal-area approximation principle and the third-time equal-area approximation principle, and the critical cutting angle of third-time approximation serves as an output result based on the improved equal-area principle; and calculating the trajectory of the new energy grid-connected system during the fault duration, and outputting the critical clearing time of the new energy grid-connected system in combination with the numerical trajectory and the analytically calculated critical clearing angle, thereby helping to take measures in time to ensure the safe and stable operation of the power system.

The application discloses a network-constructed energy storage capacity configuration optimization method and system, belongs to the technical field of power system planning and operation control, and substitutes initial capacity into a constructed multi-time scale nonlinear differential algebraic equation model to perform time domain simulation until each state variable in the network-constructed energy storage system reaches a periodic steady state, and the periodic steady state trajectory of each state variable is obtained; according to the periodic steady state trajectory, a state transition matrix in a fundamental period is obtained, and Floquet characteristic indexes are determined based on Floquet theory; the real part of the Floquet characteristic indexes is taken as a system electromagnetic stability index; the network-constructed energy storage capacity is gradually increased from the initial capacity through a search step, and when the index is greater than a preset safety threshold for the first time, the capacity value corresponding to the last search step is taken as the maximum allowed network-constructed energy storage capacity satisfying the electromagnetic dynamic stability safety threshold. The method can optimize the network-constructed energy storage capacity configuration under the premise of ensuring the system electromagnetic dynamic stability.

The invention discloses a synchronous stability dominant element identification method based on batch simulation and multi-modal analysis, and relates to the technical field of small signal stability analysis and control of a new energy grid-connected system, and the method comprises the steps: constructing a grid-connected converter nonlinear differential-algebraic equation; based on the differential-algebraic equation, performing parameter space setting and batch simulation to obtain a change range and a change mechanism of each parameter; based on the variation range and the variation mechanism of the parameters, large-scale time-domain batch simulation is executed, and a pure digital matrix A is obtained; performing feature modal analysis and extraction based on the pure digital matrix A to obtain a normalized participation factor; and performing dominant factor identification based on the feature modals and the corresponding normalized participation factors to obtain a dominant factor judgment result, and performing validity verification of the method. According to the method, the dominant elements of the dynamic stability of the new energy grid-connected converter system can be accurately identified, and the accuracy and efficiency of system stability form identification are improved.

The invention provides a method and device for evaluating the local inertia supporting capacity of a new energy delivery type AC / DC power system, and relates to the technical field of power system operation and control, and the method comprises the steps: building a parameterized differential-algebraic equation model; deriving an inertia distribution matrix of the power system by using a generalized energy framework, and calculating a local inertia supporting capability index of each network node based on the inertia distribution matrix; determining the network region of which the index value is lower than a preset index threshold value as an inertia weak region, and predicting the dynamic evolution trend of the inertia weak region based on a hybrid automaton model to obtain a prediction result; and establishing a mapping relation between the inertia supporting capability of the inertia weak area and the commutation failure risk of the high-voltage direct-current converter station, and evaluating the stability margin of the system. According to the method provided by the invention, the problem that the inertia space-time heterogeneity cannot be identified and evaluated by a traditional method can be solved, and accurate identification and risk evaluation of a region with weak local inertia supporting capability can be realized.

The invention discloses a multi-body system vibration analysis method and device. The method comprises the steps that physical parameters of a target multi-body physical system are obtained, geometric constraints and mechanical characteristics of physical joints of all parts are connected, and a differential-algebraic equation model representing dynamic behaviors of the target multi-body physical system is constructed; performing linearization processing on the differential-algebraic equation model near a balance position of the target multi-body physical system, extracting modal parameters of the target multi-body physical system, performing order reduction on the differential-algebraic equation model based on the modal parameters, and establishing a state space model for frequency domain analysis; and applying an excitation signal simulating an actual working condition to the state space model, and solving the vibration response of the target multi-body physical system through frequency domain analysis. According to the invention, the precision of the multi-body dynamic model can be improved.

The invention relates to the technical field of system simulation of power circuits, in particular to a hybrid event driven circuit simulation method and system. According to the method, through a three-step iteration process, the problems of too small step length, inaccurate event prediction and difficult convergence existing when a traditional SPICE simulator processes topology sudden change events caused by MOSFET switching, diode follow current and the like are solved. In the pre-processing step, an initial time step length is obtained based on a local truncation error, and a final step length is determined by inquiring a state switching time point predicted by each predetermined device; in the solving step, a differential algebraic equation is converted into a nonlinear algebraic equation set, and a Newton-Raphson method is adopted for iterative solving; in the post-processing step, the validity of the solution is verified, and the time step length is dynamically adjusted. According to the invention, on the premise of ensuring the simulation precision, the simulation efficiency and the numerical stability of switching power supply circuits such as Buck, Boost, Flyback and the like are remarkably improved.

The invention discloses a cooperative control method and device for transient voltage instability of a new energy cluster grid-connected system, and relates to the technical field of new energy steady-state control. The method comprises the following steps: firstly, constructing a hybrid system mathematical model considering new energy control sequential switching, analyzing a generation mechanism of a voltage oscillation instability form caused by repeated low-voltage penetration of a new energy system based on a phase diagram manifold theory, and further analyzing a transient response whole process of the new energy system when repeated low-voltage penetration occurs based on a differential-algebraic equation system model; and researching the running track characteristics of the system, and proposing a transient voltage instability discrimination index. And then main influence factors of voltage oscillation degree are analyzed, a new energy unit active power regulation and control proportion quantification method is studied based on a transient voltage instability criterion, and finally an optimization control strategy is obtained.

The application discloses a kind of multi-mechanism net type inverter cluster dc side cascading fault detection and protection method and system, establishes N machine coupling AC / DC differential algebraic equation model, constructs Jacobian matrix and reveals the infection channel structure that synchronous stiffness coefficient in non-diagonal coupling block simultaneously appears in swing equation line and DC voltage equation line, proposes the classification detection method of two kinds of cascading faults: the first kind is the power loss type sequential tripping cascade driven by photovoltaic overvoltage, and the power redistribution is detected by monitoring the monotone increasing trend of DC bus voltage;The second kind is the oscillation energy type bidirectional coupling cascade driven by energy storage oscillation, and the Hopf bifurcation critical condition is detected by monitoring the oscillation amplitude growth of DC bus voltage and frequency detuning.The firewall design method based on DC capacitor time constant and the oscillation isolation strategy based on frequency detuning are simultaneously proposed.The application provides theoretical basis and quantifiable engineering design criteria for the reliability design and protection coordination of multi-machine GFM cluster.