26 results about "Steady state operating point" patented technology

The present application relates to the field of power system stability analysis and control, in particular to a kind of thermal mass energy storage converter broadband oscillation suppression parameter stable domain identification method, comprising the following steps: establish general electric-thermal coupling mechanism model, construct the dynamic differential equation describing the evolution of input electric power and energy storage medium temperature state of converter;Mechanical dynamics equation is constructed;Establish the small signal state space model of whole system, linearization is carried out at steady state operating point and the state space matrix of whole system is derived;Define practical small disturbance stability domain, set the real part decay rate threshold and minimum damping ratio threshold of whole system eigenvalue;Algebraic singularity constraint equation in high-dimensional parameter space is constructed;Solve algebraic singularity constraint equation, establish parameter stable domain.This method avoids the repeated iteration of traditional eigenvalue analysis, can accurately depict parameter boundary, effectively improve the frequency support capability of high proportion of new energy power grid and system robustness.

This invention relates to the field of wind power converter control, and provides a method and system for switching control between black start and islanded operation of a wind power converter. Before responding to a closing command, the method first predicts the new steady-state operating point to be reached after load connection, including steady-state values ​​such as PCC voltage and converter output current, based on the electrical parameters of the load to be connected. Then, it calculates the corresponding state values ​​that the integrators of the voltage and current loop PI controllers inside the converter should possess at the new steady-state operating point. Finally, at the instant the circuit breaker closing signal is issued, these pre-calculated integrator state values ​​are synchronously preset into the controller's integrator. In this way, the controller's internal state is already near the new steady state at the moment of load connection, thus skipping the transient process of response lag and error accumulation in traditional PI controllers, achieving a smooth transition from no-load to loaded, and effectively suppressing voltage and frequency surges during the switching process.

The application discloses a new energy follow / network converter capacity configuration method based on a power angle stability boundary, first, a new energy sending end system simulation model containing a network type converter is established, and a steady state operating point of the system is calculated; then, the network type converter is dynamically equivalent to a synchronous generator, equivalent machine parameters are obtained, and the original simulation system is simplified into an equivalent machine and a new energy sending end system of a follow network type; mechanical power and electromagnetic power of the equivalent machine before, during and after a fault are derived, and an equivalent machine power angle characteristic curve is obtained; acceleration area and maximum deceleration area of the equivalent machine under different network type converter proportions are calculated, and a proportion of the network type new energy under a critical power angle stability of the system is obtained by using a dichotomy; simulation is carried out based on a PSASP platform, and rationality of the proposed configuration principle is verified. The scheme can reduce network investment of the system while guaranteeing safety and stability of the system, and improve the power grid's accommodation capacity for new energy.

The invention discloses a method for analyzing the influence of heterogeneous micro-grid parameters on system stability in a continuous steady state. The method is specifically implemented according to the following steps: step 1, acquiring steady-state working points of a heterogeneous micro-grid through parameter scanning; step 2, acquiring a low-frequency characteristic value of the heterogeneous micro-grid system in a continuous steady state based on the state space model of the micro-grid; and step 3, obtaining a participation matrix and a participation factor of the heterogeneous micro-grid system, determining a key variable according to the participation factor, and analyzing an influence rule of the parameter on the stability of the heterogeneous micro-grid according to the key variable. According to the method, the problem that in the prior art, a fixed working point is used for representing behaviors in the whole period in a traditional characteristic value analysis method, and consequently analysis is not accurate is solved.

The application discloses an aero-engine thrust fast response redundant control method and system considering combustion delay, and belongs to the technical field of aero-engine control. The method steps are as follows: an open-loop transfer function L of main fuel flow and tail nozzle throat area respectively controlling thrust is established based on a desired thrust closed-loop bandwidth; a decoupling condition between the variable tail nozzle throat area and the thrust is set to eliminate the mutual influence between them; four undetermined RTM controller functions in the transfer function L are solved; the actuator transfer functions of the main fuel flow and the tail nozzle throat area are set as first-order systems for solving; system identification is carried out at an engine steady-state working point to obtain a transfer function of a difference between the main fuel flow and the tail nozzle throat area relative to a steady-state value to a difference between the thrust and the steady-state value; the transfer function L is solved, and then the RTM control is completed according to the transfer function L, so that the fast response control of the thrust is realized. The application solves the key technical problems in the prior art.

The invention discloses a method for automatically measuring impedance of a power electronic converter based on a real-time simulation platform, which comprises the following steps of: adding a disturbance injection module and a data acquisition module into a simulation model, and calculating load flow or performing time domain simulation to obtain a steady-state working point; parameters needing to be measured are determined in the disturbance injection module; according to the measurement starting time, the wave recording starting time, the real-time simulation step length, the sampling factor, the storage file size and the storage file of a data acquisition module in the real-time simulation platform are determined, and according to the measurement starting time, the frequency disturbance duration of each time, the disturbance interval waiting time and the total frequency number of the frequency sequence, the real-time simulation total duration is determined; injecting disturbance, and acquiring a voltage and current data set of the tested port; and calculating the impedance value of the total frequency number of the frequency sequence, and generating a full-band impedance characteristic curve. According to the measurement method disclosed by the invention, the impedance scanning efficiency is improved, and the impedance of the new energy equipment is quickly and accurately acquired.

The invention provides a network construction type equipment electromagnetic dynamic modeling method and system considering a network energy storage state, and belongs to the technical field of power system dynamic modeling. The method comprises the following steps: establishing a circuit link electromagnetic scale dynamic model which simultaneously considers instantaneous power transmission and instantaneous energy dynamic states of inductance and capacitance elements according to a grid-connected system topology of a network construction converter; establishing a control link electromagnetic scale dynamic model of the network construction converter; the circuit link electromagnetic scale dynamic model and the control link electromagnetic scale dynamic model are combined, and a network construction converter electromagnetic scale dynamic nonlinear model representing system network energy dynamics is constructed; and carrying out linearization processing on the nonlinear model at a steady-state working point to obtain the electromagnetic scale dynamic small signal model of the network construction converter. According to the method, the coupling effect of network energy dynamic and converter control under the electromagnetic time scale is depicted, and the defects of a traditional steady-state model in broadband oscillation analysis are overcome.

The invention provides a closed-loop active-disturbance-rejection control method for a two-phase interlaced boost converter, and mainly aims to stabilize the output voltage of a direct-current bus, ensure high reliability, improve the efficiency of a vehicle-mounted power system and reduce the online calculated amount of a controller. Aiming at the characteristics of time variation, nonlinearity and the like of a two-phase interlaced boost converter control system, the system is approximated into a linear system by analyzing a steady-state working point, an expansion observer is designed to estimate and identify disturbance parameters in the system, and finally, an off-line control law is obtained based on closed-loop active-disturbance-rejection control. The anti-interference capability of the direct-current converter control system is improved, and the hardware cost is reduced; the dynamic response speed of a vehicle-mounted power system is improved, and the fault probability of vehicle-mounted equipment is effectively reduced.

The invention discloses a hybrid damping grid-connected inverter control method based on critical damping ratio design. The hybrid damping grid-connected inverter control method comprises the steps of S1, designing an initial steady-state working point and designing LCL filter parameters; s2, designing parameters of a current outer loop controller; s3, reference resistance required by the grid-connected system is solved; s4, calculating a value range of a feedback coefficient of active damping; s5, drawing an equivalent passive damping coefficient curve based on the value range of the feedback coefficient, judging whether an effective positive damping range exists or not, and if not, returning to the step S1; s6, if yes, calculating the passive damping in the value range of the feedback coefficient; s7, calculating a mixed damping coefficient based on passive damping and active damping, and drawing a damping coefficient curve; and S8, verifying whether the curve meets the design requirement of the critical damping ratio or not. According to the method, the characteristics of low loss of active damping and simple parameter setting of passive damping are effectively combined, the control scheme is flexible, and high robustness can be kept under strong and weak power grids.

The invention discloses an electric power system short-circuit current suppression method and system based on network construction type equipment, and belongs to the technical field of electric power. The method comprises the following steps: establishing a power system topology and solving a steady-state operating point; establishing a converter control model based on the steady-state point, and constructing a current-limiting control logic by adopting three criteria of current, phase angle and voltage; deducing a short-circuit current analytical expression through fault analysis, and establishing a relationship between the output current of the network construction type equipment and the total short-circuit current; and dynamically adjusting the output current phase by adopting a self-adaptive saturation current angle strategy based on the relationship. The technical problems that a traditional current limiting method is difficult in parameter setting and the current limiting mode cannot be automatically quitted after a fault occurs are solved, the short-circuit current of the power system can be restrained to the maximum extent, reliable on-off of a circuit breaker is ensured, and the safety and stability of the system are improved.

The invention relates to the technical field of motor frequency conversion stability control, in particular to a large-interference stability analysis method and system for offshore wind power electromechanical frequency conversion grid connection, and the method comprises the steps: building a nonlinear dynamic model of a motor and a generator set frequency conversion system; performing coordinate translation by taking a steady-state working point of the nonlinear dynamic model as a coordinate origin, and dividing an operation characteristic space into fuzzy subspaces; carrying out local linearization on the model in each fuzzy subspace, and constructing a TS fuzzy model set; constructing a corresponding quadratic Lyapunov function based on the TS fuzzy model set, simultaneously solving a maximum attraction domain boundary, and performing projection to generate a two-dimensional stable operation region graph; and according to the maximum state variable boundary in the graph, adjusting an output power instruction of an offshore wind power system controller to maintain the stability of the system. According to the invention, the problem in the prior art that the system is unstable and the equipment is damaged when the frequency conversion system of the rotating unit is subjected to high-power disturbance is effectively solved.

The application discloses a power distribution network operation stability evaluation method considering entropy space, constructs a distributed power supply dynamic model, and designs a distributed power supply energy function; based on the distributed power supply energy function, an energy value of a leading unstable balance point is selected as critical energy, and a critical energy surface is fitted; a system entropy index representing power flow balance and static voltage safety of the power distribution network is constructed, the system entropy index is dispersed to a distributed power supply level to obtain a distributed power supply entropy index; a distributed power supply entropy boundary condition is designed, a distributed power supply entropy space representing safety and stability is constructed based on a boundary projection method; energy values of a steady state working point and a given expected accident are quickly solved, and the energy values are quickly positioned in and outside the entropy space; and based on positioning results and the distributed power supply entropy space, the power distribution network operation stability is evaluated. Compared with the prior art, the application evaluates the power distribution network operation stability according to the distributed power supply entropy space, and simplifies a traditional safety and stability evaluation method.

The invention relates to the technical field of power electronics, and particularly provides a harmonic prediction and suppression method for a droop control converter based on a multi-frequency estimator, and the method comprises the steps: obtaining a main circuit parameter, a control parameter and a steady-state working point parameter of the droop control converter; determining a main circuit matrix of a harmonic state space according to the main circuit parameters based on the steady-state working point parameters, and determining a harmonic state space control loop matrix according to the control parameters; splitting by columns according to a target parameter matrix of the main circuit matrix, and separating components related to the switching disturbance to obtain a plurality of parameter sub-matrixes corresponding to the switching disturbance; the control loop matrix is substituted into the parameter sub-matrix, a harmonic state space equation is obtained, a harmonic transfer function matrix is calculated, and the harmonic transfer function matrix is used for conducting harmonic prediction according to the main circuit parameters, the control parameters and the steady-state working point parameters. According to the invention, the harmonic prediction accuracy is effectively improved.

The present application relates to the technical field of ocean renewable energy power generation, and particularly discloses a kind of floating wind wave combined power generation system model predictive control method, comprising: establishing the nonlinear mathematical model of floating wind wave combined power generation system;Determine the steady state operating point of the system;Nonlinear model linearization processing;Discrete time prediction model is constructed;Design objective function;Define state and input constraint conditions;Real-time rolling optimization solution;Dynamic feedback correction mechanism.The present application starts from the mechanism of wind wave excitation, on the one hand, through the wind turbine variable pitch control to reduce the response in the turbulent wind frequency band, on the other hand, through the wave energy power generation device PTO control to reduce the response in the wave frequency band, thereby effectively reducing the tower base load and suppressing the platform pitch motion.Through the design of objective function, the definition of constraint conditions and the solution of objective function, global multi-objective optimization is realized.

The present application relates to motor variable frequency stable control technical field, especially offshore wind motor electric variable frequency grid-connected large interference stability analysis method and system, method includes: the nonlinear dynamic model of motor and generator set variable frequency system is established;With the steady state operating point of nonlinear dynamic model as the coordinate origin, the operation characteristic space is divided into fuzzy subspace;In each fuzzy subspace, the model is locally linearized, and the TS fuzzy model set is constructed;Based on the TS fuzzy model set, the corresponding quadratic Lyapunov function is constructed, and the maximum attraction domain boundary is solved and projected to generate a two-dimensional stable operation region map;According to the maximum state variable boundary in the map, the output power command of the offshore wind power system controller is adjusted to maintain system stability.Through the present application, the problem that the prior art cannot maintain system stability and equipment damage when the rotating unit variable frequency system is subjected to high-power disturbance is effectively solved.

The invention relates to the technical field of aero-engine performance simulation, and discloses an aero-engine overall performance simulation method and system based on a volume architecture, and the method comprises the steps: obtaining an initial working state of an engine through random initial assignment of undetermined state parameters of all parts of the engine; judging whether the engine overall matching error of the simulation model meets the condition of switching to the Newton-Raphson method or not; and if not, calculating the volume effect in the component by the reverse flow path, updating the working state of the component to ensure that the state of the overall performance simulation model of the engine is close to the convergent steady-state working point, and then switching to a classical Newton-Raphson solving method to realize model state convergence. According to the method, the problems of high initial value dependence, poor convergence and low convergence rate when a traditional Newton-Raphson solving method faces a complex-configuration engine simulation model with high nonlinearity are effectively solved, and the overall performance design evaluation requirements of various aero-engines can be met.

The application discloses a kind of impedance automation measurement methods of power electronic converter based on real-time simulation platform, including in simulation model, disturbance injection module, data acquisition module, computing flow or time-domain simulation obtains steady state operating point;In disturbance injection module, the parameter that needs to be measured is determined;According to the starting time of measurement, the starting time of the recording wave of data acquisition module in real-time simulation platform, real-time simulation step, sampling factor, storage file size and storage file are determined, and according to the starting time of measurement, the duration of each frequency disturbance, disturbance interval waiting time, the total frequency number of frequency sequence, the total duration of real-time simulation is determined;Injection disturbance, and the voltage and current data set of measured port are obtained;The total frequency number of frequency sequence is calculated impedance value, and full-band impedance characteristic curve is generated.According to the measurement method disclosed in the application, the impedance scanning efficiency is improved, and the new energy equipment impedance is quickly and accurately obtained.

The invention relates to a heating furnace steady state operation point drift detection and positioning method based on multi-source data fusion, and belongs to the technical field of ferrous metallurgy automation control. According to the method, aiming at the problem of steady-state operation point drift in the operation process of the heating furnace, a group of drift sensitive indexes including furnace temperature standardization residual error, furnace temperature drift rate, temperature-energy consistency index and the like are constructed by collecting multi-source data such as strip steel operation speed, furnace temperature of each furnace area, gas flow, air flow, outlet plate temperature and the like; and carrying out smoothing processing by adopting an exponential weighted moving average method, calculating the drift intensity of each furnace area and the overall drift intensity of the plate temperature so as to judge whether steady-state operation point drift occurs or not, and positioning the leading furnace area and the drift direction when judging that the drift occurs. The online monitoring and diagnosis of the steady-state operation point of the heating furnace can be realized, and the operation stability of the heating furnace and the product quality control precision are improved.

The invention discloses a transient state-steady state hybrid control method of a buck converter based on state space switching. The method comprises the steps that firstly, inductive current and output voltage of the step-down converter are sampled and normalized, and the normalized inductive current and output voltage serve as state variables to construct a state space; then, on the basis of the state space, the operation state of the converter is judged according to the switching criterion; finally, when it is judged that the converter is in the load transient state, nonlinear transient control based on the state space is adopted to adjust the inductive current and the output voltage, and the system is made to move towards a target steady-state working point along the average natural track; and when the converter is judged to enter the steady-state operation working area, performing closed-loop regulation on the converter by adopting double-loop proportional-integral linear steady-state control. The problems that the transient response speed of a linear control method is limited and stress constraint and steady-state operation stability of a device are difficult to consider by a nonlinear control method under the load transient condition of an existing step-down converter are solved.

This invention discloses a two-layer optimized economic predictive control method and apparatus for proton exchange membrane fuel cells. The method includes establishing a mechanistic model of the proton exchange membrane fuel cell system, determining the system's control variables, output variables, and external current disturbance signals; an upper real-time optimization layer constructs a steady-state economic index function based on the current external current disturbance signal and the principle of maximizing the system's net output power, solves for the optimal steady-state operating point, and obtains the optimal output variable setpoint; a lower real-time control layer receives the optimal output variable setpoint, solves for the optimal control variable sequence based on the proton exchange membrane fuel cell prediction model, and adjusts the system's control variables to make the system's actual output variable track the optimal output variable setpoint. This invention solves the problem of low system net efficiency caused by prior art that only focuses on the performance of the fuel cell stack while neglecting the power consumption of auxiliary equipment, thus improving the overall operating economy and energy utilization rate of the system.

The present disclosure relates to a kind of AC-DC hybrid micro-grid system stability determination method and device.Wherein, the method includes: establishing the equivalent model of the AC-DC hybrid micro-grid system under synchronous rotation dq coordinate system;Based on mixed potential function theory, generate the nonlinear model of the AC-DC hybrid micro-grid system;The steady-state operating point of the AC-DC hybrid micro-grid system is generated, and the steady-state operating point is generated according to the large signal stability criterion of the AC-DC hybrid micro-grid system;The large signal stability criterion is limited to the amplitude processing based on the preset reference current limiting value, and the stability determination of the AC-DC hybrid micro-grid system is completed based on the large signal stability criterion containing current limiting amplitude.The reference current limiting value of the converter current inner loop is limited in the present disclosure, and the large signal stability criterion is optimized, so that the accuracy and practicability of stability criterion are further improved.

The application belongs to the field of power system stability control, and specifically discloses a transient value-amplitude frequency dual column method for representing oscillation rules of alternating electrical quantities, which comprises the following steps: determining the steady state values of amplitude and frequency based on the rotating vector form of electrical quantities, and keeping the amplitude and frequency in steady state value operation before disturbance occurs; after the system is disturbed, taking the steady state value as the steady state working point of the first form evolution stage, and representing the dynamic evolution of the amplitude and frequency as the superposition form of the first form complex exponential function with the first form complex frequency as the parameter; the first form complex frequency of the amplitude is equal to the first form complex frequency of the frequency; a multi-layer transient value-amplitude frequency dual column expression form is constructed through step-by-step recursion until a multi-layer nested transient value-amplitude frequency dual column expression structure covering the whole oscillation process is formed. Through the application, the real evolution trajectory of the amplitude and frequency with time in the oscillation process is continuously depicted.

Method for optimizing a model (Δpx(Δp, n, α)) of an axial piston pump (2) with a swashplate (10) adjustable to change its delivery volume in a swivel angle (α), on which an adjustment force of an adjustment unit (12) of the axial piston pump (2) dependent on an adjustment pressure (Δpx) and a pressure force resulting from a working pressure (Δp) of the axial piston pump (2) act, from which the swivel angle (α) results as a function of a rotational speed (n), wherein the method comprises the following steps: a. Determining initial model parameters of a quasi-stationary operating point of the axial piston pump (2) via a control unit; b. Determining an initial actuating pressure (Δp) x ) of the adjustment unit (12), depending on the initial model parameters, via the control unit; c. Determining a control variable (I A , I B) of the adjustment unit (12, 14, 16), depending on the initial actuating pressure (Δp x ) and at least one target trajectory (z, z', z'') of the working pressure (Δp) via the control unit; d. Controlling the adjustment unit (12, 14, 16) with the control variable (I A , I B ); e. Acquiring and / or determining actual values ​​of the working pressure (Δp), the rotational speed (n) and the swivel angle (α) via a sensing unit and / or the control unit; and f. Adjusting the model (Δp x (Δp, n, α)) against the actual values, via the control unit, and depending on them; g. Adjusting the model parameters via the control unit.

The application discloses a grid-connected equipment harmonic disturbance emission iteration method and system based on a small signal increment, writes a voltage-current relationship equation required for calculating a harmonic current; initial steady-state working point related data variables of a typical photovoltaic grid-connected inverter structure are expressed by using a steady-state component and a small signal component; the steady-state component and the small signal component are substituted to obtain a system small signal linearization equation; the small signal component is substituted into the system small signal linearization equation to obtain a small signal linearization time-invariant equation group; background harmonic voltage in grid voltage is divided into small disturbances in multiple stages, the amplitude of V gn is determined; the result is superimposed into the steady-state component to update the steady-state working point, and a small signal linearization time-invariant equation group required for next stage solving is obtained; the steady-state working point and the equation group are continuously updated until the applied background harmonic voltage is updated to be the same as a set target; the amplitude and the phase of each time output current harmonic are obtained.

A kind of impedance model computer automatic construction method for multi-terminal flexible system.The method first obtains the steady state operating point of each element of system by power flow analysis, then establishes mathematical model for common elements of multi-terminal flexible system, and linearizes, discretizes based on steady state operating point, to establish element small signal state space model;Subsequently, the generalized incidence matrix group compatible with ac-dc hybrid system is used to realize element aggregation, obtain subsystem model and calculate its z domain impedance model, finally generate s domain impedance model by bilinear transformation.The invention realizes the computer-aided automatic construction of multi-terminal flexible system impedance model, supports the impedance fast analysis of any ac / dc port, is flexible and efficient;And the topological sensitivity of system is low, when the structure changes, only the corresponding part of generalized incidence matrix group needs to be modified, and the scalability is high.Example analysis shows that the invention can accurately obtain the ac / dc port impedance of multi-terminal flexible system, and effectively improve the analysis efficiency.

This invention discloses a wind turbine load reduction predictive control method and system based on mechanism and neural network models. The method includes the following steps: establishing a wind turbine mechanism analysis and neural network model; linearizing the wind turbine mechanism analysis and neural network model at the steady-state operating point of the wind turbine to construct a linearized model of the wind turbine; constructing a wind turbine load reduction predictive control model based on the linearized model, wherein the load reduction predictive control model aims to minimize the wind turbine load while balancing the wind turbine's power generation efficiency; and solving the load reduction predictive control model to obtain the optimal values ​​of various control parameters of the wind turbine. This invention can achieve a high-precision solution to the wind turbine load reduction control problem.