97 results about "Transient stability analysis" patented technology

The invention belongs to the field of operation and control of electric power systems and provides an N-2 combined fault quick sequencing method for transient stability analysis of an electric power system, which is used for sequencing arbitrarily combined N-2 fault of an electric power system according to the severity of the transient stability. Based on the quantized evaluation information of the transient stability of the N-1 fault, the method calculates the severity index of the transient stability of the N-2 combined fault by combining the information of the power sensitivity of the powerchange of a second switching element on the transient stability critical generator group of the first fault element, thereby sequencing the N-2 combined fault set of the transient stability analysisof the electric power system. The method can be used for sequencing a large quantity of N-2 combine faults according to the severity of the transient stability when the operation mode, the model and the parameters of the power network are determined, so as to only calculate and analyze the transient stability of a small quantity of N-2 combined faults ranking at the front in detail and greatly enhance the efficiency of detailed calculation and analysis on transient stability of any N-2 combined fault.

The invention relates to a transient stability distributed simulation method of an electric power system, belonging to the transient stability analysis technical field of the electric power system; the transient stability distributed simulation method is characterized in that: variable dimension of boundary coordination equation is reduced to one half of that of a partitioning method based on connecting line by using the partitioning method based on a node decomposing method, so as to improve the simulation efficiency; the accurate initial Jacobi inverse matrix is obtained by using a boundary perturbation method, so as to reduce iterations; the calculation process is accelerated by comprehensively adopting the methods that the boundary node voltage value of the next time step is pre-estimated and the Jacobi inverse matrix is coordinated and dynamically updated simultaneously in multiple time steps; by adopting coordination algorithm based on inverse Broyden quasi-Newton method, the solving times of the boundary coordination equation are reduced greatly, so as to improve the simulation efficiency. In the technical proposal, the data interface is simple, the data transmission capacity is low, the system model is simplified, superlinear convergence speed close to the newton method is provided, and hyper real-time simulation can be realized in a wide area communication network, therefore, the method is conveniently applied to the practical electric power system.

The invention discloses an online transient stability analysis method based on a concise expression form of electromagnetic power of a single generator in a multi-machine power system. Electromagnetic output power of any single generator in the power system is a multivariable nonlinear function of all generator load angles or a multivariable nonlinear function of a slip between all generator load angles and an inductor rotor, which is known by analyzing the traditional power system. A concise expression form of the electromagnetic output power of any single generator in the complex power system is obtained through expanding a Taylor series; a load angle swinging curve of a multi-machine power system and an electromagnetic power curve are obtained through time domain simulation, and a coefficient in a high-order polynomial function is obtained by using data fitting; the load angle curve obtained through the fitting is extended to obtain a predictive load angle curve of a future moment, and the stability margin of the single generator in the multi-machine system and the system can be obtained by using the obtained concise expression form of the single generator load angle curve. The invention can be used for the online transient stability analysis of the large-scale power system.

The invention discloses a rapid screening method of expected failure sets in electric power system transient stability assessment, and belongs to the technical field of an electric power system and the automation thereof. The rapid screening method is based on an extended equal-area criterion (EEAC), adopts a researched calculation example time-varying degree and the transient stability margin, which are reflected by transient stability analysis algorithms with different simplification degrees, as indexes, and combines researched calculation example failure information so as to match and combine into different screening criteria. Expected failure subsets satisfying the screening criteria are screened out in a layered mode from an expected failure universal set, thereby greatly reducing the number of expected failures requiring detailed transient stability analysis. The rapid screening method disclosed by the invention can improve the rapidity of the transient stability assessment under the premise of guaranteeing the accuracy of the transient stability assessment, thereby appropriately coordinating the accuracy and the speed of the transient stability assessment.

The invention discloses a method for improving a transient stability analysis efficiency of an electric power system and relates to the field of the electric power system. The method comprises the following steps of: initializing element parameters of the electric power system and inputting data of the electric power system; selecting a network topology state, a generator state and a load level of the electric power system, and determining an operation state of the electric power system; carrying out Monte Carlo sampling selection on the operation state of the electric power system to form a fault sampling sequence; utilizing a task distribution method facing to a multiprocessor parallel system and distributing the fault sampling sequence; carrying out transient stability analysis on a fault sample based on an energy function method by each processor; receiving a result returned by a processor by a main processor and storing the result into a database; and when the fault sampling sequence X is finished, calculating the possibility index of the transient stability of the electric power system and outputting the result. The method disclosed by the invention meets the requirements of instantaneity of information of the electric power system and improves the analysis efficiency and the safety of the electric power system.

The invention discloses a symmetric fault transient stability analysis and control method in consideration of saturation characteristic of a virtual synchronous machine. Currently, a researching method which is related with transient stability of a virtual synchronous machine on the condition of large interference is not suitable for the symmetric shortcircuit fault of a power grid. According to the method of the invention, through establishing a system equivalent model before the symmetric fault of the power grid, in the symmetric fault of the power grid and after the symmetric fault of the power grid, through analyzing a transient stability mechanism and an instability process on the condition that the saturation characteristic of the virtual synchronous machine is considered, a fact that a main influence factor for transient stability of the system is power angle magnitude is obtained. Based on the fact, a corresponding measure is presented, thereby effectively suppressing transientenergy and improving transient stability of the system.

The invention relates to a method for automatically searching assistant decisions for transient and dynamic stability based on parallel computation. Based on power flow and stability data of a power grid and aimed at the problems of transient stability and dynamic stability, the method adopts large-scale parallel computation processing technology as well as human experience and a specific computation method to realize automatic identification of adjusting elements and automatic search of feasible adjustment methods, so as to achieve off-line transient stability analysis of an auxiliary electric power system and actual operation instruction.

The invention belongs to the technical field of power system computation and analysis and is applied to generating a typical fault set for transient stability analysis of a power system. The method comprises the following steps of: firstly, for the same power grid operation mode, performing the transient stability evaluation on different faults respectively by adopting a transient stability quantitative evaluation method to obtain a stability mode of each fault; secondly, calculating a transient stability association degree index between different faults according to a constitutive relation between the participation factor of the same generators in the transient stability critical generator set of every two faults and the participation factor of all the generators in the critical generator set; and finally, screening all the faults according to the transient stability association degree index between the faults. Therefore, the typical fault set for the transient stability analysis of the power system is obtained.

A correlation assessment method of power grid cascading failure accident chains comprises the steps that (1) a system is initialized to be in a normal operation working condition; (2) initial failures happen to circuits with equal probability, circuit initial failures are circuit three-phase permanent short-circuit failures, relay protecting action failure removing in a set time is carried out, and for direct-current circuit, the initial failures are direct-current circuit single-pole locking failures; (3) based on the previous circuit failure situations, transient stability analysis is carried out on an electric system, if system transient is unstable, the step (7) is carried out; and if system transient is stable, the step (4) is carried out; and other steps are carried out. According to the method, on the basis that the correlation between cascading failures can be considered, system transient stability failures can be subjected to effective searching, searching correlation probability is given, system states and topology are considered, meanwhile, high computing efficiency is achieved, and certain guiding effect is achieved on cascading failure searching and accident chain recognition.

The invention discloses a transient stability control method for a microgrid with multiple virtual synchronizers, and belongs to the technical field of microgrid transient stability analysis and control. According to the method, the virtual inertia, the virtual damping, the virtual governor sag coefficient and the reactive power control loop sag coefficient are fully considered, an energy functionmodel of the microgrid with multiple virtual synchronizers operating in parallel is constructed and the stability of the system is analyzed and judged based on the energy function. Besides, an adaptive control method based on the energy function is applied to perform adaptive real-time adjustment on the virtual inertia, the virtual damping, the virtual governor sag coefficient and the reactive power control loop sag coefficient in VSG so as to reduce the system energy after the system failure, increase the attraction region of the system, slow down the process of the system energy reaching the critical energy, obtain the effective time for the failure removal and improve the transient stability of the system.

The present invention discloses an electric power system transient stability analysis method. The electric power system transient stability analysis method mainly comprises a time domain simulation method and a direct method. A transient energy function method belongs to the direct method. The transient energy function method model is simple, considers the non-linear problem, can avoid complex numerical integration operation, is fast in computing speed and can provide system stability margin indexes, and the restriction of the model precision, critical point selectivity and linearity path hypothesis allows a traditional transient energy function to always have the conservation problem. The improved transient energy function method based on the SMR (Squared Matrix Representation) technology introduces the SMR technology to improve the transient energy function analysis method, a superposition program is employed to obtain the optimal Lyapunov function so as to improve the problem of a traditional transient energy function conservation.

The invention discloses an electromechanical transient modeling method for an LCC-MMC hybrid direct current grid. A constructed electromechanical transient model of the LCC-MMC hybrid direct current grid takes the dynamic characteristics of a MMC direct current side model into account, so the accuracy of the model is higher. In addition, the method adopts a state space expression for unified combination solving of an algebraic-differential mathematical model of a direct current network and a converter station, and an algebraic-differential equation of a controller, so that the modeling difficulty is low, and the implementation is convenient. The model constructed by the method can be used for transient stability analysis of the LCC-MMC hybrid direct current grid, and has important application in planning, designing and running of the grid.

The invention belongs to the field of electric power system stability analysis and control, and particularly relates to an electric power system energy function optimization and transient stability margin evaluation system and method. The system comprises a data acquisition and processing module, an LMI calculation module, an energy boundary factor calculation module and a control strategy module which are sequentially connected. The method comprises the steps of proposing a Lyapunov function cluster suitable for transient stability analysis in allusion to an electric power system structure preserving model; building three different types of simplified Lyapunov functions and comprehensive characteristics and stability boundary of the three types of functions; considering a network structure and a system state, defining a comprehensive stability index energy boundary factor (EBF) for the Lyapunov function, and applying the comprehensive stability index EBF to online failure severity dynamic sorting and control strategy optimization so as to realize early warning for the safety of an electric power system. According to the invention, evaluation can be performed on the system quickly and effectively, and a reference is provided for system vulnerability quantitative evaluation and online prevention control.

The present invention comprises a partition-composition method and its equipment for online detection of transient stability of interconnected power system. The method consists of three parts. Firstly, according to the dynamic response data of the generators at the actual time, the key parameters of transient stability analysis of local areas can be obtained from local dispatch control center based on the wide area measurement system. Secondly, the key parameters of entire grid can be obtained using the uploaded parameters from the local area. Lastly, using the partition-composition method, parameters of an adjoint power system of the entire grid can be obtained. The equipment consists of 4 modules, including the first obtained module, transport module, the second obtained module and the composition module. Using these modules, transient stability data of entire grid can be obtained exactly without the limitation of network topology, system model and parameters. The present invention can be a beneficial and potential tool for the online analysis of power system transient stability with higher computation speed and lower storage requirement.

The present invention discloses a double fed induction generator contained electric power system transient stability analysis method based on a security domain. The method comprises the steps of based on the model parameters, determining the related parameters of an electric power system; setting a Case A as the electric power system in which a double fed induction generator is not accessed; setting a Case B as that the double fed induction generator is accessed in a bus of a power grid to substitute for a synchronous generator on the bus; determining the parameter space of a current electric power system security domain, searching a critical point of the electric power system and fitting a corresponding dynamic security domain boundary; comparing and analyzing the dynamic security domains of the Case A and the Case B; researching the change reason of the dynamic security domain of the electric power system after the access of the double fed induction generator, and analyzing the influence to the electric power system transient stability after the access of the double fed induction generator. The double fed induction generator contained electric power system transient stability analysis method based on the security domain of the present invention uses a hyperplane to fit to inject the boundary of the dynamic security domain of the electric power system containing the double fed induction generator in the power space and within an engineering concerned range, and discloses the influence of the access of the double fed induction generator to the electric power system transient stability.

The invention discloses a multilevel elicitation method dynamic planning based power system dynamic equivalent method, and relates to the technical field of stability analysis for a power system. According to the method, dynamic characteristics of an original complex system can be tracked by a simplified system under variable working conditions so as to accelerate the safety and stability analysis process for the power system. A homology equivalent method is adopted firstly to perform dynamic equivalence on the original system; then a multilevel elicitation method dynamic planning algorithm dynamic link is introduced into an equivalent system; the link is subjected to off-line training so as to obtain the equivalent system containing the multilevel elicitation method dynamic planning algorithm; according to the equivalent system, tracking for the dynamic characteristics of the original system can be realized under the variable working conditions, so that the equivalent system is relatively high in adaptability; the power system dynamic equivalent method has the advantages that the shortcoming of low adaptability of the existing equivalent method is overcome, the equivalent precision is greatly improved, and the effectiveness for transient stability analysis for the power system is ensured.

The invention relates to an air conditioning load aggregation method for an electric power system, and belongs to the field of loading modeling of electric power systems. The method adopts an induction motor first order mechanical transient model to describe the normal state of an air conditioner; aggregation for a plurality sets of air conditioners of different types is performed through modeling based on the steady state theory of the induction motor, so that the aggregation air conditioner model of equivalent parameters can be obtained; and the major parameters of the model include the electrical parameter, the input power, the initial slip, the rated slip and the inertia time constant. The model not only has higher aggregation accuracy, but also has low calculated amount, and can be used for transient stability analysis.

The invention relates to a process for evaluating transient stability of an electric power system according to trace and trace sensitivity. The process is characterized by including steps of firstly, deriving a computing method for computing the sensitivity of the power angle trace of the electric power system relative to the fault clearing time according to the actually measured trace; and secondly, analyzing relationships between the sensitivity and the system critical time so as to conclude that the sensitivity can serve as a system stability degree evaluation index from the relationships according to a large number of simulation verifications. The process is simple in computing, provides an importance theoretical support for transient stability analysis of the electric power system on the basis of trace, and has the advantages of high computing speed, evaluation precision and application value, good online application prospect, and the like.

The present invention discloses a power grid transient stability energy function analysis method and system containing a detailed generator model. The method comprises the following steps of: establishing a power system model containing the detailed generator model; determining a failure mode; calculating an angular point CRN; calculating a generator equivalent parameter; solving an accurate controlling unstable equilibrium point (CUEP); and calculating an energy margin according to a system energy difference value of the CUEP and a failure clearing moment. The system comprises apparatuses used for implementing the method. The problem of a relatively large deviation between a transient stability analysis result and an actual situation, caused by a too simplified model in an existing energy function method entering a practical stage, is solved, so that the reliability of power system security analysis can be improved.

The invention discloses a critical cluster identifying method for transient stability analysis of a power system. The critical cluster identifying method comprises the following steps: obtaining a critical clearing time of a fault by using time domain simulation; obtaining a critical stable track and a critical unstable track of the power system according to the critical clearing time; determining a leading unstable balance point according to the critical stable track and the critical unstable track so as to obtain a power angle of each generator at the leading unstable balance point; carrying out simulation according to the actual clearing time of the fault so as to obtain a fault track; calculating the sensitivity of an energy margin to the mechanical power of each generator according to the fault track and the power angle of each generator at the leading unstable balance point; and identifying generators of a predetermined number in the generators, of which the calculation results of the sensitivities are negative values, as the critical cluster. According to the critical cluster identifying method for transient stability analysis of the power system, the critical cluster is identified according to the sensitivity of the mechanical power of each generator based on the energy margin; the identification accuracy is improved; and the situation of misjudgment is reduced.

The invention discloses an energy-based transient stability and oscillation dynamic unified analysis method, device and system, and the method comprises the steps: carrying out the transient stabilityanalysis of a system, and carrying out the oscillation dynamic analysis of the system. In the transient stability analysis process, an IEEAC method is adopted to carry out detailed analysis on the case conditions belonging to the uncertain classes through a power system transient stability rapid classification method; in the oscillation dynamic analysis process; analyzing oscillation characteristics of the system under different time scales based on energy viewpoints; the method comprises the following steps: firstly, analyzing the macroscopic performance of a system from the change of section energy, judging whether the local characteristics of a system oscillation dynamic process need to be analyzed in any time period according to the macroscopic performance, and finally, carrying out mechanism analysis on a specific time section needing mechanism analysis by adopting a characteristic root technology along a track. A unified analysis method is provided for large and small disturbance stability in power angle stability analysis of the power system from the perspective of energy, and manual isolation of large and small disturbance stability analysis is avoided.

The invention provides a simulation method of an integrated defense system for enhancing coal enterprise power system power supply reliability, which comprises the following steps: determining a power supply mode of a coal enterprise power system; calculating and analyzing a relay protection setting value; determining the safe and stable operation control strategy of the coal enterprise power system; switching a standby power; and adopting auxiliary measures. According to the method, an overall, comprehensive and integrated assessment is carried out on the effectiveness of measures for enhancing the coal enterprise power system power supply reliability by a trend analysis, a short circuit current calculation, a static security analysis and a transient stability analysis.

The invention relates to a method for quickly calculating wind-power allocation ratio based on trajectory sensitivity. Without considering wind-power fluctuation, the method comprises the steps that initial wind-power allocation ratio is selected, the running mode is generated, and load flow calculation is carried out; transient stimulation is carried out, and trajectory sensitivity is obtained based on trajectory; trajectory sensitivity required is selected according to a problem needing studying, and trajectory sensitivity norms are obtained; the system critical wind-power allocation ratio is determined by judging whether the trajectory sensitivity norms are mutated; otherwise the wind-power allocation ratio is adjusted by using the trajectory sensitivity, and calculation is conducted again. On one hand, the calculation method is simple, the corresponding sensitivities can be freely selected according to state variables to be analyzed to obtain the norms, and the instability of a power system is judged by the mutation of the sensitivity norms; and on other hand, the reasonability of the existing wind-power allocation ratio of the power system is judged according to the critical wind-power allocation ratio, and the method has certain reference value in the aspects of scheduling, transient stability analysis and the like.

The invention discloses a voltage stability bifurcation analysis method for an AC / DC hybrid power distribution network. According to the method disclosed by the invention, the AC / DC hybrid power distribution network is equivalent to three portions; corresponding controllers are designed based on a differential algebra equation, wherein the controller comprises a voltage loop, a current loop and a stabilizer; voltage stability bifurcation analysis based on active power reference value variations is realized through setting system parameters and control parameters; a bifurcation inflection point and the limit power of voltage stability are determined based on an acquired bifurcation diagram, an optimal parameter of the stabilizer of the system is selected, a bandwidth value corresponding to the maximum stability margin of the system is found out, asymptotic stability analysis, static stability analysis, dynamic stability analysis and transient stability analysis of the system can be realized, a corresponding relation between the stabilizer parameter and the limit power of the system is acquired, feedback control signals of the stabilizer are set finally, and the system is controlled to operate in a range of the maximum stability margin.

The invention provides an electromechanical transient synchronous machine model and an initial q-axis saturation parameter determination method. According to the electromechanical transient synchronous machine model, dichotomy is adopted to initialize saturation effects and excitation and damping leakage reactance are considered. The model is mainly characterized in that mutual leakage reactance between excitation and damping windings in a rotor potential equation represents to be only interlinked with the excitation and damping windings but does not pass through a magnetic flux leakage chain of a stator coil; and the dichotomy is used for determining the initial power angle and the initial q-axis saturation armature reaction reactance. According to the model and the parameter determination method by the model, the dichotomy is adopted to initialize the q-axis saturation reactance and the power angle, the difficult problem of using an armature reaction reactance correction mode to consider the saturation influences is solved, and for the first time, using the armature reaction reactance correction mode to consider the saturation influences in a domestic practical electromechanical transient stability analysis program is realized.

The invention discloses a power system fast transient stability simulation method based on real-time dynamic equivalence. According to the method, real-time grouping and model aggregation are performed on power generator sets by a short period of whole system numerical integration calculation after a fault occurs, then equivalent system network parameters are obtained by applying a proposed equivalent system nodal admittance matrix rapid identification method, and finally transient stability calculation is completed on an obtained dynamic equivalent system. Compared with existing power system transient stability analysis methods which have disadvantages that calculation amount is high and calculation speed cannot meet the online calculation requirement, the method has advantages of high precision and great convergence of a conventional numerical integration method due to low number of grouping and low time consumption of identification of an equivalent system admittance matrix, and a calculation system is greatly simplified and calculation amount is reduced.

The invention discloses a power system transient stability analysis method taking wind power and direct current comprehensive effects into consideration; a system transient steady-state analysis modelwhich is connected with wind power in an alternating-current and direct-current non-parallel transmission mode is established, and the quantitative indexes of large-scale wind power access to systemtransient stability influence are provided; a quantitative analysis method by enabling the wind power and direct current comprehensive effects to be equivalent to system equivalent mechanical power increment is proposed; and a qualitative analysis method considering influence of the wind power and direct current comprehensive effects to change of an acceleration area and a deceleration area is proposed based on equal area determination. According to the method, the implementation is convenient, the analysis method is clearer and more effective, the applicability is high, and the analysis is simple and convenient; and meanwhile the application range is wide, the analysis effect is good, the application scenes are wide, and the problem of practical engineering can be solved.

The invention relates to a power electronic power system transient stability analysis method based on a direct method. The method comprises the following steps: 1, determining a system model, 2, constructing a Lyapunov energy function: firstly, establishing a mixed potential function P (i, v) according to a reasonably simplified and determined system model, and secondly, constructing a Lyapunov type energy function of the system in combination with a stability discrimination theorem in a mixed potential function theory, and solving a differential value of the Lyapunov type energy function, andfinally, judging the transient stability of the system through the characteristics of the energy function and the differential value thereof, and 3, estimating the critical energy of the system.

The invention discloses a critical clearing time method for power system disturbance based on a frequency synchronization theory of a second-order inhomogeneous Kuramoto model, relates to a critical clearing time method for a power system after disturbance, and aims at solving the problems that an existing method cannot well correspond to a power system model, and an attraction domain degree of a system balance point is not researched in the existing method and cannot be applied to transient stability analysis. The method comprises the following steps: 1 building a second-order inhomogeneous Kuramoto model corresponding to the power system model; 2 modifying parameters of the second-order inhomogeneous Kuramoto model; 3 solving a state variable of the system at the disturbance clearance moment, and solving parameters C (delta0, omega0 and alpha) in a criterion according to the state variable; 4 judging whether the system can be kept in synchronism stability after certain disturbance according to the parameters in a synchronization criterion, and calculating the critical clearing time that the system can be kept unstable after the system is disturbed. The critical clearing time method is applied to the field of electric power system.

The invention relates to a motor load aggregation method for an electric system and belongs to the field of load modeling for the electric system. The method includes the steps that firstly, according to main motor parameters affecting the stability of the electric system, two groups of good system stability and poor system stability are obtained through division; then, according to actual operation conditions of all motors, electromagnetic and mechanical characteristics of motor rotors are comprehensively considered, the initial slip frequency for an aggregated motor is obtained through solving, and then electric parameters of the aggregated motor are obtained through solving and include stator reactance, rotor reactance, excitation reactance, rotor resistance and an inertia tie constant; finally, the method is verified through a calculation example model. The result shows that the method is high in aggregation precision and small in calculation amount, original motor groups are simulated through two equivalent motors adopted for aggregation, errors are smaller than the errors caused by the adoption of a single equivalent motor, and the method is suitable for transient stability analysis.