51 results about "System of imprimitivity" patented technology

The invention provides an electromagnetic transient state simulating method of a double-fed wind power generation set system with a variable speed and a constant frequency, relates to a wind power generation system, and in particular relates to a method for the modeling analysis of a double-fed wind power generation set system by using computer programs. The method comprises the following steps: establishing a wind power model to simulate the wind power absorbed by a wind turbine; establishing a wind turbine shafting model; establishing a propeller pitch control system model; establishing an electrical simulation model of a double-fed asynchronous induction motor; establishing a controller model of a frequency converter on the side of a power grid and the frequency converter on the side of a rotor; establishing a double-fed wind turbine stand-alone infinity system model by using a wind power generation set simulation module; setting a simulated operation condition and a failure state of the power generation set system; and carrying out an electromagnetic transient simulation, thereby verifying the setting value and the rationality of the protective system. According to the invention, the detailed models conforming to the physical properties of the double-fed wind power generation set system with the variable speed and the constant frequency are established to carry out simulations on the electromagnetic transient state and the electromechanical transient state, so that the dynamic properties of a wind turbine under various failure and working conditions are investigated. Therefore, the simulations of the wind turbine in large-scale power grids are realized possibly.

The invention discloses a modeling and simulation method for a doubly-fed variable speed constant frequency wind generation set system, and relates to a wind power generation system, in particular to a method for performing modeling analysis on a doubly-fed wind generation set system by using a computer program. The method comprises the following steps of: establishing a wind power model to simulate wind power absorbed by a wind-driven generator; establishing a wind-driven generator shaft model; establishing a blade pitch control system model; establishing an electrical simulation model for a doubly-fed asynchronous induction motor; establishing a power grid side frequency converter and rotor side frequency converter controller model; establishing a doubly-fed wind-driven generator one machine infinite bus system model by using the wind generation set simulation models; and setting the simulation running working condition and the failure state of the wind generation set system, and performing electromagnetic transient simulation, electromechanical transient simulation and failure simulation. Detailed models in line with physical characteristics of a doubly-fed variable speed constant frequency wind generation set are established for the electromagnetic transient simulation and the electromechanical transient simulation, and dynamic characteristics of the wind-driven generator under various failure and working conditions can be inspected to make the simulation of the wind-driven generator in a large-scale power grid possible.

The invention discloses a speed controller parameter optimization method in consideration of primary frequency modulation and ultralow-frequency oscillation suppression. According to the method, a single machine infinite system containing an optimized unit and an equivalent infinite power supply is established, a comprehensive optimized index function is established under the stimulation of frequency step signals of the primary frequency modulation test requirement by regarding the unit openness / power response curve rise time, stabilization time and reverse regulation power as performance indexes of primary frequency modulation and regarding damping torque coefficients of a speed controller and a water turbine system in an ultralow frequency band as ultralow-frequency oscillation damping performance indexes, the primary frequency modulation performance and the damping level can be considered by obtained speed controller parameters, and technical means is provided for optimization of the speed controller parameters and suppression of ultralow-frequency oscillation.

The invention discloses a Doubly-Fed Induction Generator (DFIG) parameter identification method, and belongs to the field of power system modeling. The DFIG parameter identification method comprises the following steps: firstly, determining an analytical expression of stator dq axis short circuit current under a condition of three-phase metal short circuit of a port of a doubly-fed induction generator, and determining parameters to be identified according to the analytical expression; building a single-machine infinite bus system of a doubly-fed wind turbine generator set based on a Matlab / Simulink platform, setting the three-phase metal short circuit at the port of the doubly-fed induction generator, and simulating to obtain a disturbed trajectory of the stator dq axis short circuit current; analyzing the identifiability of each parameter to be identified and the complexity for parameter identification by adopting a trace sensitivity method; and finally, identifying all the parameters to be identified by adopting a particle swarm optimization algorithm, and determining parameter identification values according to multiple identification results. Compared with a method based on active power and reactive power, the doubly-fed induction generator parameter identification method for DFIG parameter identification based on the stator dq axis short circuit current has the advantage that the influence caused by the current transformer control procedure is low; and the parameter identification values are determined according to the multiple parameter identification results, so that the problem of large errors possibly caused by single identification is avoided.

The invention discloses a SVC sliding mode control method based on integration adaptive backstepping; the control method comprises the following steps: building a SVC equipment single-machine infinite bus system dynamic mathematics model, designing a controller according to an integration adaptive backstepping method, firstly designing a state variable tracking error, adding an integration item into the error item, simultaneously considering system parameter nondeterminacy, building a Liapunov function, online adaptively processing the uncertain parameters, finally adding a Terminal slide mode surface, obtaining a SVC integration adaptive backstepping stable controller, and finishing SVC sliding mode control based on integration adaptive backstepping. The method uses the adaptive integration method to eliminate errors, adds the Terminal slide mode control, so the system has stronger robustness on interference and system perturbation; the method can fast damp power concussions, can keep the machine end voltage, and can improve the power system transient stability.

The invention relates to a subsynchronous oscillation method and apparatus for a static synchronous series compensator suppression system. The subsynchronous oscillation method comprises the steps of taking an included angle between an SSSC (static synchronous series compensator) output voltage and an alternating current circuit current, and modulation ratio of the SSSC as generator influencing parameters by the SSSC according to a system linear model of an SSSC-containing single-machine infinite-bus system; taking voltage frequency deviation and active power flow of an SSSC apparatus mounting point as SSSC modulation ratio influencing parameters; taking the voltage frequency deviation and active power flow of the SSSC apparatus mounting point as input to establish a transfer function of a damping controller, wherein the voltage frequency deviation and the active power flow of the SSSC apparatus mounting point are taken as input of the damping controller; and optimizing control parameters of the transfer function of the damping controller. By adoption of the technical scheme provided by the invention, the power grid operating damping and stability can be improved; meanwhile, the damping characteristic of the power grid in a region where the static synchronous series compensator is located is optimal; and the subsynchronous oscillation method is also applicable to design of an actual controller.

The invention discloses a structure improvement and parameter configuration method for a power system stabilizer PSS4B, aims at solving the problem that the PSS4B is not easy to adjust since the structure is complicated and parameters are easily affected mutually, and provides the PSS4B with an improved structure. On the basis of classic parameters of IEEE, in order to avoid mutual influences of phase compensations between branches, the phase compensation links of all the branches set to be the same; on the basis of the improved structure, a phase compensation link parameter setting method for the improved PSS4B is provided; a state matrix comprising a single-machine infinite bus system of the PSS4B with the improved structure is listed; and the condition that the low-frequency oscillation suppression effect of the improved PSS4B is more excellent than that under classic parameters is shown through the damping ratio in an oscillation mode.

The invention discloses a method for evaluating the new energy acceptance capacity of a grid-connected point by comprehensively considering the stability characteristic, and belongs to the technical field of automation of power systems. The influences of wind power generation variability and instability on a power grid, an external load level and the change condition thereof are combined; a multi-machine system is equivalent to a single-machine infinite bus system through an EEAC method by employing a static stability constraint, reactive power control and a transient constraint of the power system as conditions; the stability margin and the sampling yield are calculated; and the capability of connecting a wind power station of considering a transient stability constraint to the power grid to the maximum extent is evaluated by employing the specified range of the sampling yield as an index. By the method, the safe and stable operation level of the wind power station can be improved; the generating capacity of the wind power station is effectively ensured; and the benefits of energy conservation and emission reduction are improved.

The invention discloses a small-interference stability analysis method of a double-fed wind generator one-machine infinite system; the method comprises the following steps of step 1, modeling a dynamic mathematical model of the one-machine infinite system; step 2, performing linearization processing on the mathematical model of the system at the balance point to obtain a corresponding state matrix; step 3, obtaining a system characteristic value and a mode category, and predicting a state variable and a modal relationship according to participation factors; and step 4, according to system parameters or running states and external network parameters, calculating he sizes and the modal changes of different characteristic values. In the prior art, the technical problems that when the stability of the grid-connected system of the wind generator is researched, the model of some elements in the system, such as a transmission system model and a model of a control system, are not established in detail; and the influence of parameters in the system on the system model state in a detailed model are not researched and the like, are avoided.

The invention discloses a method and a system for calculating the influence of excitation additional difference adjustment on the dynamic damping of a synchronous generator, wherein the method comprises the following steps: a single-machine infinite bus system Philips-Heiferon mathematical model represented by K1, K2, K3, K4, K5 and K6 is expanded to establish a difference adjustment model considering additional difference adjustment which is represented by K1, K2, K3, K4, K'5, K'6. According to the eigenvalues of the state equations of the single-machine infinite bus system without error adjustment, the oscillation frequency of the single machine infinite bus system without error adjustment is solved; according to the eigenvalues of the state equations of the single machine infinite bus system with additional deviation adjustment, the oscillation frequency of the single machine infinite bus system with additional deviation adjustment is solved; and the damping torque coefficient KD ofthe excitation system without additional adjustment Xc=0 and the damping torque coefficient KD of the excitation system after additional adjustment Xc is not equal to 0 are calculated. The differencebetween the damping torque coefficient KD of the excitation system without additional adjustment Xc = 0 and the damping torque coefficient KD of the excitation system with additional adjustment Xc not equal to 0 is compared. The results show that the damping torque coefficient KD of the excitation system with additional adjustment Xc not equal to 0 is higher than that of the excitation system with additional adjustment Xc = 0.

The invention discloses a method and system for calculating the influence of excitation additional difference adjustment on the synchronous torque of a synchronous generator. The method includes the following steps that: the Phillips-Heffron mathematical model of a single-machine infinite bus system is expanded, a difference adjustment model under additional difference adjustment is established; the oscillation frequency of the single-machine infinite bus system under no difference adjustment is solved according to the eigenvalue of the state equation set of the single-machine infinite bus system under no difference adjustment; the oscillation frequency of the single-machine infinite bus system under additional difference adjustment is solved according to the eigenvalue of the state equation set of the single-machine infinite bus system under additional difference adjustment; the synchronous torque coefficient KS of an excitation system under no additional difference adjustment ( a condition that Xc=0) is calculated according to the oscillation frequency of the single-machine infinite bus system under no difference adjustment; the value of the synchronous torque coefficient KS of the excitation system under additional difference adjustment (a condition that Xc is not equal to 0) is calculated according to the oscillation frequency of the single-machine infinite bus system underadditional difference adjustment; and the difference value of the synchronous torque coefficient KS of the excitation system under no additional difference adjustment (the condition that Xc is equalto 0) and the synchronous torque coefficient KS of the excitation system under additional difference adjustment (the condition that Xc is not equal to 0) is obtained by means of comparison.

The invention relates to a method for determining the critical stable value of the grid connected thermal power generating unit primary frequency regulation rotating speed diversity factor. The thermal power generating unit is a condensing turbine set, and is based on a one-machine infinite system. The method is characterized by comprising the following steps of S1, establishing a steam volume effect mathematical model; S2, establishing a turbine rotor mathematical model; S3, establishing a hydraulic servo-motor mathematical model; S4, solving the critical stable value of the thermal power generating unit primary frequency regulation non-linear model rotating speed diversity factor; S4, solving the critical stable value of the thermal power generating unit primary frequency regulation linear model rotating speed diversity factor; and finally obtaining a rotating speed diversity factor Delta formula which makes the system be stable. According to the invention, the linear model rotating speed diversity factor critical stable value is employed to substitute the non-linear model rotating speed diversity factor critical stable value to serve as the set reference value of the grid connected thermal power generating unit primary frequency regulation rotating speed diversity factor, the safety of the grid connected thermal power generating unit is considered, and stable operation and primary frequency regulation capability of the rid connected thermal power generating unit are considered at the same time. At the same time, the method for determining the critical stable value of the grid connected thermal power generating unit primary frequency regulation rotating speed diversity factor is simple in implementation method and high in precision.

The invention provides a generator parameter identification processing method and a system thereof. The method includes the following steps that a generator standalone infinite system model is built, and trace sensitivity of generator parameters on measurement signals under different types of excitation signals is calculated; according to the trace sensitivity, corresponding types of the excitation signals are selected to be used as reference excitation signals corresponding to the generator parameters, and the strength and lasting time of the reference excitation signal are set; according to the set strength and the lasting time, the reference excitation signals are exerted on the generator; and according to disturbance data generated when the reference excitation signals are exerted on the generator, parameter identification is conducted on the generator parameters corresponding to the reference excitation signals. The generator parameter identification processing method can identify the generator parameters accurately and solve the problem that the traditional generator parameter identification processing method is inaccurate in identification results of the generator parameters.

The invention discloses a timing sequence optimization control method for a distributed power flow controller, and the controller, wherein a DPFC (deviation of power frequency component) device is connected into a single-machine infinite bus system, and the both ends of the single-machine infinite bus system are connected with a Y-Delta-type transformer; the DPFC device is used for switching current converters at the series side of the DPFC device in different time periods, and the number of the current converters switched in each time period is calculated according to a corresponding formula. According to the timing sequence optimization control method disclosed by the invention, the active power flow of an electric transmission line is adjusted in real time by controlling the switching time of the single-phase current converters at the series side of the DPFC device; simultaneously, the reduction of the active power of the electric transmission line during the charging energy storage process of direct-current capacitors at the series side of the DPFC device is prevented, the total harmonic distortion of a line current caused by the plurality of single-phase current converters is avoided, and the reactive compensation performance of the DPFC device is optimized.

The present invention provides a system and a method for detection of performances of a phase modifier transformer bank protection device. The system comprises a phase modifier physical simulation unit, a main transformer physical simulation unit, a grounding transformer physical simulation unit, a frequency conversion starting device physical simulation unit, an excitation system physical simulation unit, a bus simulation unit, an injection loop physical simulation unit, a grid connected switch physical simulation unit, a transmission line physical simulation unit, an infinity system physicalsimulation unit and a plurality of current and voltage transformer physical simulation units. The system can fully simulate the operation mode and the operation features of a phase modifier transformer bank in an actual system, arranges fault points in the system, detect faults in each fault point through adoption of a mode of simulation for the phase modifier scene operation to reduce the information of the phase modifier transformer bank protection device to be detected and determine whether maloperation and movement refusing are generated or not so as to effectively verify the reliabilityand the power swing of the phase modifier transformer bank protection device.

The invention provides a use method for configuring a novel power system stabilizer PSS4B by using an improved PSO algorithm. According to the method, a random weight and hybrid operation-combined method is adopted to improve a basic PSO algorithm, and then, the transfer function of the PSS4B is partially simplified; the improved PSO algorithm is utilized to optimize parameters to be optimized inthe PSS4B; and a one-machine infinite bus system and a 3-machine 9-node system perform parameter optimization simulation on the PSS4B through using the improved PSO algorithm. With the method of the invention adopted, the problem of failure to achieve an optimal suppression effect which is caused by a condition that a three-branch phase compensation link is not applied provided that classical parameters are given by the IEEE can be solved; since the improved PSO algorithm is adopted to configure the novel power system stabilizer PSS4B, the suppression of low-frequency oscillation by the PSS4Bcan be quantitatively analyzed.

The invention provides a cutter control measure quantification method based on system acceleration energy and provides a decision basis for transient stabilization cutter control measures. The method comprises steps that: a critical cluster of a multi-machine interconnection electric power system during instability is determined; an equivalent single-machine infinite system model of the multi-machine interconnection electric power system based on real measurement information is established according to the critical cluster; acceleration energy of the system is calculated; a cutter measure quantification solution equation is established and is solved to acquire calculated values of cutter amount; classifying processing on the calculated values of cutter amount is carried out in combination with a real generator capacity according to the calculated values of cutter amount, and final real cutter amount is acquired; dynamic behavior of the system after employment of the cutter measures is continuously monitored, if the system tends to be in an instability state, next cutter amount is calculated based on newest measurement information. The method fully considers dynamic characteristics of the system, has a simple solution process and has excellent engineering application prospects.

The invention discloses a method and device for setting the critical gain of a power system stabilizer. The method comprises steps of constructing an electromechanical transient model for the single-machine infinite system of a generator to be tested; performing simulation by using electromechanical transient model according to a preset gain step from the preset initial gain of the power system stabilizer of the generator to be tested, so as to obtain the root trajectory of an excitation oscillation mode; according to a preset critical damping ratio threshold, processing the root trajectory ofthe excitation oscillation mode so as to obtain the critical gain of the power system stabilizer; inputting the critical gain of the power system stabilizer to the electromechanical transient model,performing time-domain simulation verification of a terminal voltage step so as to set the critical gain of the power system stabilizer of the generator to be tested. The method can reduce the actually measured error of the critical gain, set the gain value of the power system stabilizer, and further ensures the safe and stable operation of the power system.

The invention discloses a parameter tuning method of a power system stabilizer and belongs to the technical field of stable control of a power system. The power system stabilizer is designed aiming at a classic small interference four-order single machine infinite bus system model. A lead link, a resetting link and an amplification link are selected as master variables and a certain effective range is set; the master variables are optimized by utilizing a particle swarm algorithm; meanwhile, an inertia weight linear change manner is adopted in order to increase the fast convergence of the algorithm. By adopting the method disclosed by the invention, damping is effectively increased and low-frequency oscillation of a system is inhibited; meanwhile, the defect that the effectiveness of the parameters of the stabilizer cannot be ensured is overcome.

The invention relates to an electric power system emergency control method based on response information. Response of a generator, i.e., a power angle, an angle speed and imbalance moving kinetioity information, is detected by a wide area dynamic information system WAMS in real time, when the system is not stable, control quantity required by the system is calculated in real time. The method comprises steps that: 1, whether the system is stable is determined; 2, an unstable balance point of an equivalent single-machine infinity system is predicted, if the system has no unstable balance point, stepout instruction is emitted; 3, a target value of a first-order derivative k of the angle speed versus the power angle of the equivalent single-machine infinity system is calculated; 4, control quantity lambda of the equivalent single-machine infinity system is calculated; 5, control quantity delta Pm required by a multiple-machine system is calculated; and 6, generator cutting operation is carried out. Through the method, the response of the generator, i.e., the power angle, the angle speed and the imbalance moving kinetioity information, is detected by the wide area dynamic information system WAMS in real time, when the system is not stable, the control quantity required by the system can be calculated in real time, and a complex model of the system can be adapted to.

The invention provides an EEAC-based AC / DC hybrid system transient stability control method. The method comprises steps: the power angle and the power data of each generator after fault are received through a control center; each generator is subjected to generator group recognition; according to the power angle data and the power data, the recognized generator group is equivalent to a dual-generator system by adopting a corresponding local inertia center, the dual-generator system is then equivalent to a single-generator infinite system, and the single-generator infinite system curve is fit to a power angle relationship fitting curve after fault; and by using an extended equal area criterion strategy, transient stability discrimination is carried out. The method can effectively balance the unbalance between mechanical power and electromagnetic power after blocking fault, reduces the capacity of cut-off after fault, has great practicability, and can provide reliable guarantee for safeand stable operation of the power system.

The invention discloses a stability distinguishing method of a wide-area power system under influence of section variable-time delay. According to the stability distinguishing method, a novel augmentation vector and Lyapunov-Krasovskii functional construction method is proposed on the basis of building a wide-area section variable-time delay power system model with regard to serious influence of atime delay phenomenon on stable running of the wide-area power system; an error generated during the resolving process is reduced by employing methods of time delay partition, Wirtinger integral inequality, Free-matrix-based integral inequality and convex combination during resolving of a functional derivative to obtain a stability criterion with relatively low conservation property, and the stable running region of the system is expanded; and finally, compared with an existing method, the method has the advantage that the stable running region of the system is expanded by typical simulationanalysis of a second-order system, a single-machine infinite system and a four-machine eleven-node system.

The invention discloses a power grid regulation and control method and system for restraining low frequency oscillation. The method includes the steps that a state variable of a single-machine infinite bus system is acquired; the acquired state variable, a preset first weighting matrix, a preset second weighting matrix, a system state matrix and a system control matrix are converted into a transformation matrix through the following formula, wherein the system state matrix and the system control matrix correspond to the single-machine infinite bus system; the transformation matrix, the second weighting matrix and the state variable are converted into an optimum controlled variable; the optimum controlled variable is used as a feedback controlled variable to conduct feedback regulation and control over an infinite power grid. By the adoption of the method and system, the restraining efficiency of low frequency oscillation is improved, meanwhile, abrasion to power grid equipment can be lowered, so that optimum control is achieved, and the stability of an electric power system and the security of a generator set are effectively improved.

The invention provides an electromagnetic transient state simulating method of a double-fed wind power generation set system with a variable speed and a constant frequency, relates to a wind power generation system, and in particular relates to a method for the modeling analysis of a double-fed wind power generation set system by using computer programs. The method comprises the following steps: establishing a wind power model to simulate the wind power absorbed by a wind turbine; establishing a wind turbine shafting model; establishing a propeller pitch control system model; establishing an electrical simulation model of a double-fed asynchronous induction motor; establishing a controller model of a frequency converter on the side of a power grid and the frequency converter on the side of a rotor; establishing a double-fed wind turbine stand-alone infinity system model by using a wind power generation set simulation module; setting a simulated operation condition and a failure state of the power generation set system; and carrying out an electromagnetic transient simulation, thereby verifying the setting value and the rationality of the protective system. According to the invention, the detailed models conforming to the physical properties of the double-fed wind power generation set system with the variable speed and the constant frequency are established to carry out simulations on the electromagnetic transient state and the electromechanical transient state, so that the dynamic properties of a wind turbine under various failure and working conditions are investigated. Therefore, the simulations of the wind turbine in large-scale power grids are realized possibly.

The invention provides a STATCOM (static compensator) control method based on a switching system theory, which comprises the following steps of: analyzing a main circuit topological structure of an STATCOM device, and determining a mathematical model of a singe unit-infinite system comprising a STATCOM, determining a three-order model of a generator in the singe unit-infinite system comprising the STATCOM, and a state equation and an output equation of an electric power system comprising the STATCOM; linearizing a nonlinear model of the STATCOM; determining the design steps of an H infinity robust controller mathematical model of the STATCOM and a generator excitation robust controller; and determining the structural composition of the whole system of the STATCOM based on a DSP (Digital Signal Processor). A controller designed according to the method of the invention can ensure that the system is stabilized on one hand when the system fails, and can eliminate the influence of the interference on the performance of the system on the other hand.

The invention discloses an improved particle swarm-based SVC power oscillation damping controller parameter optimization method, which comprises steps: S1, based on the traditional phillips-heffron model of a power system, an SVC power oscillation damping control link is added, and a single machine infinite bus system mathematical model containing SVC addition damping control is built; S2, the difference between the electromagnetic power at a generator end and the mechanical power of the unit is used as an input disturbance signal of the built single machine infinite bus system mathematical model; S3, an improved particle swarm optimization algorithm is used to screen a proper SVC power oscillation damping control link parameter according to the single machine infinite bus system mathematical model in the first step based on an ITAE performance evaluation index; and S4, the optimal parameters acquired by adopting the improved particle swarm optimization algorithm are returned to the single machine infinite bus system mathematical model containing SVC addition damping control, and phase compensation is carried out on control signals. In comparison with the traditional power system stabilizer controller, better oscillation regulation performance can be achieved.

The invention provides a detection system of a mixed current transformer. A low-voltage side, a medium-voltage side and a high-voltage side of a transformer physical simulation unit of the system arerespectively connected with a load physical simulation unit, an infinite system physical simulation unit and one end of a busbar through three of current transformer physical simulation units constituting a current transformer physical simulation unit group. The other end of the busbar is connected with an equivalent generator set physical simulation unit and a transmission line physical simulation unit respectively through another two current transformer physical simulation units in the current transformer physical simulation unit group. The detection system of the mixed current transformer provided by the invention is equivalent to an actual system, can simulate a mixed operation mode and operation characteristics of the mixed current transformer in the actual system, and can improve thereliability and sensitivity of differential protection actions.

The invention particularly relates to a relay protection adaptability detection system and method based on moving die wind-solar complementary. The system comprises an equivalent fan system physical simulation unit, a photovoltaic power physical simulation unit, a load physical simulation unit, an infinite-bus system physical simulation unit, a transformer physical simulation unit and a power transmission line physical simulation unit, wherein the equivalent fan system physical simulation unit and the photovoltaic power physical simulation unit are connected with the infinite-bus system physical simulation unit through the transformer physical simulation unit and the power transmission line physical simulation unit; meanwhile, the load physical simulation unit is connected with the infinite-bus system physical simulation unit. The detection method improves the fault analysis accuracy, provides a scientific basis for the relay protection adaptability research of wind-solar complementary systems, and has high practicability in engineering practice.

The invention discloses a method of recognizing a power system transient stability negative correlation section based on a trajectory, which belongs to the field of power systems and automatic technology thereof. The method of the invention is based on a power system transient stability quantification theory, system units are divided into a preceding group and a remaining group, a two-unit system is further formed equivalently until a single unit infinite system is formed equivalently, the number of peaks in first swinging of a system equivalent single unit infinite system power-angle response curve is used for initially judging whether a transient stability negative correlation section possibly exists in the system, if the peak number is larger than 1, two-unit equivalence based on an inertia center is further carried out on the preceding group and the remaining group respectively, and through comparing a power-angle phase difference at any moment of equivalent two units in different groups, whether a transient stability negative correlation section exists in the system is finally judged. A power system dispatching operator can master the internal operation rules of the grid, a grid dispatching operation control decision is made, and safety, stability and the automatic level of the system are enhanced.

The invention discloses an optimal control method of a single-machine infinite-bus affine nonlinear system. According to the optimal control method of the single-machine affine nonlinear system, based on a single-machine infinite-bus system, nonlinear optimal control design is performed; the equation of motion of the generator rotor of the single-machine infinite-bus system is written in the mode of an SISO (single input single output) affine nonlinear system; through coordinate mapping, a completely controllable and precisely linearized system can be obtained; then according to the design method of a quadric-form optimal control LQR (linear quadratic regulator), the controlled quantity of the precisely linearized system can be solved, accordingly a nonlinear optimal controller of the original system can be obtained, meanwhile, real-time online semi-physical simulation is performed to test the practical feasibility of a scheme. The optimal control method of the single-machine infinite-bus affine nonlinear system achieves precise linearization of the single-machine infinite-bus system and meanwhile takes the condition of non-real-time performance of pure digital offline simulation, thereby verifying the control effects of a controller based on theoretical control in actual real field application through semi-physical simulation experiments. By testing the effects of the designed controller during actual application, the optimal control method of the single-machine infinite-bus affine nonlinear system is beneficial to high truthfulness of the designed algorithms.