153 results about "Small-signal model" patented technology

The invention relates to the technical field of simulation verification, in particular to a new energy station grid-connected system stability dual verification simulation method and system. Comprising the following steps: S1, carrying out a sweep frequency test on a controller of a new energy station to obtain frequency domain data; s2, processing the frequency domain data to obtain impedance model parameters of the controller and the new energy device, and fitting equivalent impedance models of the controller and the new energy device based on the combined model parameters; s3, constructing a small signal model based on the equivalent impedance model of the controller, coupling the impedance model of the new energy station with the equivalent impedance of the power grid, and determining a stability boundary; s4, verifying the accuracy of the stability boundary through the combination of frequency domain small signal analysis and time domain large signal simulation; and S5, outputting the stability index map of the new energy station, and determining an optimization measure for stable operation.

The invention relates to a power system voltage control technology, in particular to a method and equipment for maintaining grid-connected point voltage three-phase balance under weak power grid unbalanced disturbance, and the method comprises the following steps: firstly, establishing a small signal model of a converter grid-connected system after unbalanced disturbance, and emphatically considering the phasing error influence of a phase-locked loop transient process; then, the fluctuation quantity of the amplitude and phase of the PCC voltage induced by unbalanced disturbance is accurately calculated, the influence is counteracted through a power outer ring feed-forward compensation mode, and three-phase balance of the PCC voltage in the transient state and the steady state process is achieved under the condition that the weak power grid unbalanced disturbance is maintained. According to the method, the influence of the machine-network interaction of the weak power grid on the dynamic characteristics of the PCC voltage is considered, and a better voltage balance maintaining effect is achieved in the weak power grid. Through composite control, according to PCC voltage vector amplitude and phase disturbance compensation, system transient state and steady state whole-process voltage balance maintenance after unbalanced disturbance is realized. The control structure is simple, and the robustness of the system is improved.

The invention discloses a VSG grid-connected system control method based on an improved three-parameter wave trap, and belongs to the technical field of power system control, and the method comprises the steps: firstly building a single-input single-output small signal model based on a VSG grid-connected system containing power coupling, and calculating an active open-loop transfer function; an improved active damping resonance suppression method is introduced, so that the transient stability of the system is improved; the expected system stability margin under the system oscillation frequency is obtained, and the parameter design of the three-parameter wave trap is completed based on the subsynchronous frequency oscillation characteristics; the three-parameter wave trap is remodeled, and active steady-state deviation caused by the virtual damping coefficient under power grid frequency disturbance is eliminated. According to the method, the stability of the system is improved, the system is ensured to have a relatively good stability margin, and active steady-state deviation caused by power grid frequency disturbance of the grid-connected system can be completely eliminated.

The invention discloses a VSG coordinated control method and device based on improved self-adaption and feed-forward compensation, and the method comprises the steps: building a model of a VSG optical storage grid-connected system, and analyzing a power angle characteristic and a frequency oscillation curve; introducing an arc tangent function to optimize a traditional adaptive control strategy, and smoothly adjusting rotational inertia and a damping coefficient; a feed-forward compensation control strategy is added, an active compensation expression and a rotor motion equation are established, a compensation coefficient and a filtering time constant are set in a coordinated mode, and configuration of a small-signal model change zero-pole pair of an active power reference value under disturbance is reconstructed; adjusting virtual rotational inertia and a damping coefficient based on the optimized adaptive control strategy, and correcting a power reference value in advance by predicting frequency fluctuation based on a feed-forward compensation control strategy; according to the method, power overshoot and frequency change deviation are effectively suppressed, smooth adjustment of rotational inertia and VSG dynamic performance optimization are realized, and the system response speed and stability are enhanced.

The invention discloses a single-loop droop control method and system for a wind generating set, and the method comprises the following steps: constructing a doubly-fed fan-power converter-power grid three-module coupling model, and completing the dynamic adaptation of the characteristics of a doubly-fed fan of a single-loop droop control architecture without inner-loop current control; based on the input signal-model collaborative integration body and the adaptive architecture, MIMO-GBC is adopted to analyze a phase margin and a resonance peak value of an open-loop transfer function matrix eigenvalue of a dynamic small signal model, and double risks are identified in a full slip rate interval; aiming at the resonance risk, a current induction type virtual impedance strategy is adopted; aiming at insufficient phase margin, adopting a transient phase calibration strategy; and according to the real-time slip ratio of the DFIG and the stator power change, inter-partition linkage optimization is carried out on the virtual resistance and the phase calibration angle so as to minimize a dual-power step response fluctuation square mean value, a parameter setting period and a rotor side converter control period are synchronously matched, and all-working-condition stable control is realized.

The invention belongs to the field of two-level converter small signal and impedance modeling, and discloses a VSC impedance analysis method in a superposition oscillation component scene and a related device. The method comprises the following steps of: superposing an alternating-current voltage oscillation component, and establishing each steady-state quantity frequency domain model; establishing a main circuit steady-state frequency domain model; establishing each small semaphore frequency domain model based on the main circuit steady-state frequency domain model; establishing a main circuit small signal frequency domain model; constructing a PLL controller small signal model, a DC voltage controller small signal model and an AC current controller small signal model; constructing a small signal model of the alternating current modulation signal; and calculating the port impedance of the two-level current converter in the scene of superposition of the oscillation components based on a small signal model of the alternating-current modulation signal. According to the method, the VSC port impedance in the scene of superposition of the oscillation components can be accurately analyzed, and key technical support is provided for oscillation mechanism analysis and stability improvement of new energy access to a weak point network.

The invention discloses a dual-frequency positive-sequence impedance modeling method for a network-building type energy storage converter considering frequency coupling. The method comprises the following steps: 1, injecting a dual-frequency positive-sequence disturbance voltage signal at a grid-connected point of the network-building type energy storage converter based on a virtual synchronous machine; 2, establishing a linearized small signal model for each control link of an active-frequency loop, a reactive-voltage loop, a virtual impedance-containing voltage and current double closed loop and the like to form a multi-frequency signal model; and 3, according to the multi-frequency coupling relationship between the current and the voltage, constructing a frequency coupling impedance matrix, and reducing a coupling term into output impedance to obtain the positive sequence output impedance and the negative sequence output impedance of the converter considering the frequency coupling, thereby simplifying the model stability analysis. According to the method, dual-frequency positive sequence disturbance is introduced, the coupling effect between different frequency components is effectively described, the defect that a traditional single-frequency modeling method cannot reflect the multi-frequency interaction characteristic is overcome, and the accuracy and applicability of the impedance model of the network construction type energy storage converter under the multi-frequency disturbance scene are remarkably improved.

The invention belongs to the field of power electronic technology and new energy grid-connected control, and particularly relates to a cooperative control system and method for parallel operation of multiple new energy inverters. The method comprises the following steps: firstly, establishing a small signal model of an inverter parallel system, and analyzing dynamic characteristics of the system under power disturbance; secondly, realizing power decoupling and current sharing control based on a frequency-power droop characteristic; furthermore, coordinated operation of multiple energy sources such as photovoltaic energy and energy storage is realized by monitoring the phase of the direct-current bus voltage and the alternating-current side voltage in real time; the method has high engineering applicability, and high-speed real-time communication between parallel units is not needed; the virtual impedance parameters Rv and Lv have clear physical significance and are easy to preliminarily set according to line parameters; the calculation of the dynamic matching self-adjusting module is linear operation, the requirement for the computing power of a processor is low, and integration and implementation on an existing inverter control platform are facilitated.

The invention relates to the technical field of power systems, and discloses a PID controller parameter adaptive adjustment method and device of a network construction converter. The method comprises the following steps: calculating an output error signal and an output error signal change rate of a small signal model based on the small signal model of the network-forming converter, calculating an error gradient by using the output error signal and the change rate thereof, and dynamically updating PID control parameters based on a gradient descent method. When the PID control parameters are updated, whether selection of the PID control parameters can cause instability of a system where the network construction converter is located or not is checked, if yes, the error gradient calculation parameters are adjusted to recalculate the error gradient of the output error signals, if not, updating of the PID controller parameters is stopped, and by adjusting the PID control parameters in a self-adaptive mode, the network construction converter is updated. And the stability of the network-forming converter in a power grid is effectively ensured. The technical problem that in the prior art, an effective technical means for conducting self-adaptive adjustment on the control parameters of the network building converter to maintain stable operation of a power grid system is lacked is solved.

The invention relates to an impedance modeling method and device and computer equipment. Comprising the steps that disturbance voltage is injected to the alternating current side of a main circuit, a first relation between a modulation small signal and an alternating current small signal is obtained through alternating current control topology, the disturbance voltage and a phase angle small signal are correlated through a phase-locked loop, and a second relation between the modulation small signal and an alternating voltage small signal is determined; injecting disturbance voltage to the direct current side of the main circuit, and determining a third relationship between the modulation small signal and the alternating current small signal and a fourth relationship between the direct current small signals based on the alternating current control topology and the direct current control topology; and finally, impedance modeling is carried out in combination with a frequency small-signal model, so that self-impedance and coupling impedance characteristics of an alternating current side and a direct current side can be accurately reflected, and a basis is provided for analyzing system stability and optimizing a control strategy.

The invention discloses a power distribution network voltage fluctuation control method and device considering communication time lag. The method is applied to a distributed photovoltaic power distribution network, the power distribution network at least comprises a cooperative controller and a plurality of weak branches, each weak branch is connected with an impact load and an energy storage converter, and each energy storage converter corresponds to a local energy storage controller; the method comprises the following steps: uniformly modeling communication time lag between the cooperative controller and each local energy storage controller, and distributing the communication time lag to a power distribution link to obtain a power distribution small signal model containing the time lag; constructing a state space model of the energy storage converter; unifying the power distribution small signal model and the state space model of the energy storage converter to a common reference coordinate system to obtain a whole system state equation; and performing voltage control on the power distribution network based on the full-system state equation. The influence of communication delay on the stability of the power distribution network can be eliminated.

The invention discloses a DC micro-grid power buffer safety control method and device aiming at FDI attack, and relates to the technical field of power electronics and power system control. The method comprises the steps of obtaining a block matrix of a DCmGs system node current equation according to the Kirchhoff's current law; adopting Kron simplification to eliminate internal node voltage, obtaining a relation between a port current vector and a voltage vector, and constructing a small signal model of the port voltage vector; based on a small signal model, a linear mapping relation about disturbance of bus voltage to equivalent input impedance of each power buffer is constructed, modeling and linearization are carried out on energy and adjustable input impedance of each power buffer, a network coupling small signal model is constructed, and a second-order high-gain observer is designed; and if the FDI attack exists in the DCmGs system, an anti-FDI attack elastic control law is designed, so that the closed-loop voltage in the DCmGs system and the energy of a power buffer are quickly converged, and buffeting is inhibited. By adopting the method, the DCmGs system can be prevented from buffeting in an unknown FDI attack scene.

This invention belongs to the field of linear periodic time-varying system modeling and analysis technology, and discloses a small-signal modeling method and application for LCC-HVDC systems. The method includes: constructing mathematical models of the segmented and continuous parts of the LCC-HVDC system based on its circuit topology within each operating interval, and integrating these models as the mathematical model of the LCC-HVDC system; linearizing the trajectory of this mathematical model to obtain its small-signal model within each operating interval; designing a small-signal model of the LCC-HVDC system during switching between adjacent operating intervals using the Filippov method; and combining the small-signal models of the LCC-HVDC system within each operating interval and the small-signal models at the switching time to constitute the small-signal model of the LCC-HVDC system, thus completing the small-signal modeling. This invention can accurately characterize the switching dynamics of the LCC-HVDC system, achieving accurate and low-complexity small-signal modeling of the LCC-HVDC system.

The invention provides an online identification and input design method and device for a wireless power transmission system, and the method comprises the steps: carrying out the online estimation of a transfer function parameter of a target system, and building an initial small signal model; constructing a full-order model corresponding to the target system, and performing order adaptive order reduction processing; determining a loss function of the target system by taking minimization of disturbance of the excitation signal to the target system as a target; on the basis of defining the loss function, constructing an optimization problem of the target system under disturbance constraint, and performing optimal excitation input design; and constructing a robust controller of the target system by adopting a robust control method in combination with the initial small signal model. According to the method, the system modal change can be tracked in real time under the closed-loop working condition, the modeling precision and the real-time performance are improved, and the problem that the identification precision is poor in the prior art is solved.

The invention provides a converter power ripple suppression method and device under unbalanced disturbance, and relates to the technical field of power electronics and new energy grid connection. The method comprises the following steps: constructing a small signal model of a grid-connected converter of a weak alternating current system under unbalanced disturbance, wherein the small signal model comprises PCC voltage vector dynamic modeling, physical process modeling of phase orientation errors caused by PLL slow dynamic, converter control loop dynamic modeling and weak alternating current system line transmission characteristic modeling; based on a small signal model, considering and considering the control characteristics of the converter, and constructing a power transmission model of machine-network closed-loop interaction; and designing a feed-forward decoupling compensation branch, and carrying out dynamic feed-forward power compensation on the power ripples of the converter under unbalanced disturbance according to a power transmission model of machine-network closed-loop interaction. According to the invention, suppression of power ripples can be well realized in the transient process and the steady-state process of the system, and the electric energy quality and the stability of the grid-connected system are effectively improved.

The invention provides a stability judgment method for a direct-current bus of a full-power pumped storage unit, and relates to the technical field of hydroelectric power generation. The method comprises the steps that a direct-current bus capacitor is equivalent to two parallel equivalent capacitors, and the pumped storage unit is split into a unit side and a network side with a parallel connection point as a boundary; respectively constructing small signal models of the electrical devices of the two parts; based on each small signal model, respectively constructing a corresponding admittance model, and then constructing a corresponding impedance model; substituting the electrical parameters and the control parameters into the impedance model, and drawing a corresponding Bode diagram; and under the same working condition, if the phase difference at the amplitude intersection point of the two Bode diagrams is less than 90 degrees, the direct current bus does not generate interactive instability under the corresponding working condition, otherwise, the interactive instability occurs. According to the method, the modeling difficulty and model complexity of the full-power pumped storage unit can be effectively reduced, the characteristics of the pumped storage unit can be accurately reflected, and the interaction stability of a power system on a direct-current bus can be judged.

The present invention discloses a method and system for analyzing the small-disturbance stability of a station containing a grid-type converter, comprising: establishing an impedance model of a grid-following converter; establishing an impedance model of a grid-forming converter; constructing a grid-connected system model of a new energy station containing both a grid-following and a grid-forming type; establishing a simplified equivalent circuit of the station grid-connected system; establishing a Nyquist criterion for the small-disturbance stability of the grid-connected new energy station containing the grid-forming type; and analyzing the small-disturbance stability characteristics of the station grid-connected system using a Nyquist diagram. The present invention solves the problem in the prior art of the lack of quantitative and effective analysis of the small-disturbance stability of new energy stations containing grid-following and grid-forming converters. Based on the established small signal model, a station small-disturbance stability criterion is established to quantitatively analyze the small-disturbance stability characteristics of new energy stations containing grid-forming converters in low grid strength scenarios. Compared with traditional impedance modeling methods for new energy stations, the present invention can better reflect the impact of grid-forming access on the small-disturbance stability of new energy stations.

The invention discloses an energy storage VSG self-adaptive control method based on knowledge and data combined driving. The method comprises the following steps: firstly, constructing an energy storage VSG inverter model to obtain a VSG control equation; building a VSG small-signal model, and setting the value ranges of the rotational inertia and the damping coefficient; then, on the basis of a VSG control equation and energy transfer in VSG grid-connected operation, an angular frequency change rate is obtained, and nonlinear relations exist among the square of the angular frequency change rate, the current change rate of the energy storage equipment, the rotational inertia and the damping coefficient; and finally, based on a data and knowledge combined driving method and a scene division idea, performing offline training on the RBF-PINN neural network. And applying the RBF-PINN neural network after offline training to online training based on knowledge driving, and switching the RBF-PINN neural network in a corresponding scene according to different working conditions to obtain rotational inertia and a damping coefficient. The relation between the energy storage state quantity with obvious change and the VSG control parameters is deeply mined, and the overshoot in the energy storage VSG transient process in online training is obviously reduced.

The invention discloses an improved virtual synchronous generator control method and system, and belongs to the technical field of power system automation control. S10, establishing a hybrid energy storage type VSG converter control model, wherein a hybrid energy storage module is composed of a super capacitor and a battery; s20, adding a second-order LADRC system into an active-frequency loop control structure of the hybrid energy storage type VSG model, and establishing a VSG control model based on the second-order LADRC system; s30, based on the VSG control model of the second-order LADRC, establishing a VSG small signal model based on the second-order LADRC, and obtaining a time domain response equation of angular frequency deviation; s40, drawing a transient response curve of VSG control at the off-grid and grid-connected switching moment based on second-order LADRC according to the time domain response equation of the angular frequency deviation by adopting a phase plane method; and S50, according to the obtained transient response curve, designing a virtual inertia and damping adaptive coordination control strategy. According to the invention, smoother and more efficient voltage sag compensation at the moment of off-grid and grid-connected switching is realized, and the overall reliability and stability of a power system are improved.

The invention discloses a grid-connected VSG low-frequency oscillation suppression strategy for reactive loop forward channel phase correction, which is characterized in that a P / Q-omega / U low-frequency small signal model of a grid-connected VSG and a power grid is constructed, and analysis is carried out by adopting an argument principle, so that the system stability depends on a determinant Z sigma (s) of the sum of equivalent P / Q-omega / U power impedance of the grid-connected VSG and the power grid. Through research, under interactive coupling of an active loop and a reactive loop, low-frequency phase lag of a grid-connected VSG reactive loop forward channel enables Zsigma (s) to have a negative resistive component, and low-frequency oscillation may be caused. In combination with an impedance passivity design theory, a feedforward additional branch is introduced into a reactive loop forward channel to carry out lead correction on phase lag of an integration element, so that suppression of low-frequency oscillation is realized. According to the invention, the active loop transient inertia damping support control and the reactive loop steady-state voltage support control of the grid-connected VSG are not changed, the structure is simple, and the method is easy to realize.

The invention provides a stability analysis precision method based on an improved phase-locked loop MMC impedance model. According to the improved phase-locked loop structure of the integrated harmonic elimination module, the relation between input and output of an improved part is deduced, and a mathematical model is constructed. Vector expressions of bridge arm equivalent capacitor voltage, bridge arm current and sub-module switching coefficients are obtained through Fourier transform, and an MMC frequency domain steady-state model is constructed. And based on a multi-harmonic linearization method, the model is linearized at a steady-state working point, and a main circuit small signal model after disturbance injection is obtained. And meanwhile, mathematical modeling is carried out on the control system to obtain a small-signal model of a sub-module switching coefficient under disturbance. And solving an alternating current side impedance model adopting the improved phase-locked loop by combining the two types of small signal models. According to the impedance model provided by the invention, the influence of n-order harmonics in the modeling process is effectively eliminated, the precision of the impedance model is improved, and a more reliable reference basis can be provided for stability analysis and parameter design of the MMC system.

The present invention belongs to the field of high-voltage direct current (HVDC) impedance modeling and stability analysis, and discloses a MMC-MTDC structured impedance modeling method and related devices. The method comprises: establishing a small-signal model of the MMC main circuit at each end of the MMC-MTDC system; establishing a structured small-signal model of the MMC modulation signal at each end based on modular modeling of the control link; calculating the MMC positive and negative sequence control structured AC and DC port impedances based on the established small-signal model of the MMC main circuit at each end and the structured small-signal model of the MMC modulation signal at each end; establishing an impedance model of any node in the DC transmission grid based on network aggregation; and establishing structured impedance models of different MMC ports at each end of the MMC-MTDC. The present invention can accurately establish impedance models for different application scenarios, different control modes, and different AC and DC ports of the system, providing key technical support for arbitrary section oscillation analysis and stability improvement of the MMC-MTDC system.

The embodiment of the invention provides a DC micro-grid stability control method considering a constant power load, and relates to the technical field of power electronic equipment, and the method comprises the steps: building a state space model of a Boost DC-DC converter; constructing a linear active disturbance rejection controller; dC bus capacitor voltage is collected as a capacitor voltage measurement value; estimating the total disturbance of the system, and outputting a total disturbance observation value; the state feedback control unit executes duty ratio signal generation and output; discretization reconstruction is carried out on the linear active disturbance rejection controller, and a discretization control algorithm adaptive to the digital control chip is generated; capacitor voltage acquisition, disturbance observation value updating and duty ratio signal output are circularly completed according to a set sampling period. The technical problems that in the prior art, control parameters are generally designed and optimized based on a small signal model, large-range disturbance cannot be dealt with, the system is unstable under the large disturbance condition, and the reliability and safety of the micro-grid are seriously affected are solved.

The application discloses a kind of GaN HEMT equivalent circuit model parameter self-adapting extraction method and system, comprising: extracting parasitic parameter value by small signal equivalent circuit parasitic parameter extraction method, establishes initial population;Stripping parasitic parameter in initial population obtains each bias eigenvalue by network analysis, and simulation equivalent circuit S parameter data is obtained by calculation;Judgment is calculated according to S parameter data individual fitness;New individual is generated to replace singular individual in population until population is non-singular;According to the search range of adjustment algorithm of non-singular population;According to the individual selection, crossover, variation rule set to the individual in initial population is carried out genetic calculation, and new genetic individual is obtained;Whether the preset target is satisfied is judged, and the element parameter corresponding to optimal individual is output as the final parameter of small signal model;I-V model is optimized by genetic algorithm, and the weight matrix of fitness function is updated according to model error, and optimization is carried out again to meet the preset target, and the small signal model parameter is combined to establish large signal equivalent circuit model.The application greatly improves the modeling speed of small signal model and the accuracy of large signal model without sacrificing accuracy, which provides key technical support for reliable design of high-power, high-frequency microwave circuit.

The present application relates to LLC resonant converter technical field, specifically to a kind of LLC resonant converter small signal modeling method based on time domain correction;Mainly include the following steps: establishing the equivalent model of LLC resonant converter each element and third-order average value equivalent circuit, LLC resonant converter small signal modeling method is reduced to second-order equivalent circuit by third-order average value equivalent circuit, add disturbance in second-order equivalent circuit, and separate large signal component and second-order small signal disturbance to obtain the analytical form of second-order average value small signal model;The LLC resonant converter small signal modeling method proposed in the scheme considers high precision and ease of use, improves the applicable frequency range, can guide LLC resonant converter controller design and stability analysis, the average value small signal model established by time domain analysis has higher precision, and analytical form transfer function is given, to facilitate practical engineering application.

The application discloses a kind of wind power photo-thermal integrated power generation system small signal model construction methods, comprising the following steps: constructing the time domain small signal model of photo-thermal generator unit;According to the time domain small signal model of photo-thermal generator unit, the frequency domain small signal model of photo-thermal generator unit is established;The time domain small signal model of permanent magnet direct drive wind turbine is constructed;According to the time domain small signal model of permanent magnet direct drive wind turbine, the frequency domain small signal model of permanent magnet direct drive wind turbine is established;Equivalent current source frequency domain small signal model and equivalent power grid frequency domain small signal model are constructed;Establish the small signal model of wind power photo-thermal integrated power generation system.The application can better reflect the dynamic of wind power photo-thermal integrated power generation system, modeling process is relatively simple, suitable for large-scale wind power photo-thermal integrated power generation system grid-connected stability analysis, using system small signal model to judge system stability, can be judged according to system parameter relationship, concise and clear, help to solve the electromagnetic oscillation problem of photo-thermal power station.

A parameter adaptive control method and apparatus for a virtual synchronous generator, and an electronic device, relating to the technical field of voltage control. The method comprises: according to a coupling value of a direct current voltage change frequency band of a multi-terminal flexible direct current system during operation, constructing an adaptive direct current voltage droop coefficient function; according to a direct current voltage droop coefficient, calculating a damping ratio of an output port of the multi-terminal flexible direct current system, and according to the damping ratio of the output port and a preset damping ratio, constructing a first optimization objective function; according to differential-mode frequencies of a plurality of converter stations of the multi-terminal flexible direct current system, constructing a second optimization objective function; and constructing a parameter adaptive function according to a small signal model of the multi-terminal flexible direct current system, the first optimization objective function and the second optimization objective function, and solving the parameter adaptive function, so as to obtain a target parameter value of a virtual synchronous generator. The technical problem in the related art that multi-terminal flexible direct current systems exhibit poor stability when encountering disturbances is solved.

The invention provides a bidirectional DC-DC converter control method and system based on a TD3 algorithm. The method comprises the following steps: acquiring a small signal model of the bidirectional DC-DC converter in two working modes of Boost and Buck; constructing an intelligent controller based on a TD3 algorithm; training an intelligent controller, taking the DC bus voltage and the inductive current as state input, taking a system stability index as an award, and obtaining a trained intelligent agent; on the basis of a small signal model, a trained intelligent body replaces a traditional PI controller to output the duty ratio in a current inner loop, and self-adaptive control over the inductive current is achieved; and compensating the output of the traditional PI controller by the trained intelligent agent in the voltage outer loop to realize the adaptive control of the direct current bus voltage. The method does not need a precise mathematical model of the system, can improve the dynamic response of the DC bus voltage under the load change, and has robustness to the change of working conditions.

The invention belongs to the field of power supply and dispatching, and provides a method for optimizing and analyzing the capacity ratio of a follow-up network hybrid system based on a small signal model, which comprehensively considers the voltage and frequency stability of the system so as to determine the optimal capacity ratio of the follow-up network hybrid energy storage system in different power grid scenes. The method comprises the following steps of: firstly, establishing a full-order state space small signal model of a network-following hybrid grid-connected system according to different expressions of a network-following converter control loop; then, a characteristic value analysis method and a participation factor analysis method are utilized to analyze the lowest network construction permeability of the basic requirement for maintaining the system stability under different power grid strengths, and it is revealed that dominant control links influencing the system stability under different working conditions and parameters are different.

The present application belongs to the technical field of fan torsional vibration prediction, and particularly relates to a grid-connected direct-drive fan torsional vibration prediction method, device, equipment and storage medium. The method comprises: constructing a small signal model of the grid-connected direct-drive fan; based on a shafting double-mass block model, deducing the relationship between the port voltage and current signals of the direct-drive fan and the torsional vibration of the shafting of the direct-drive fan when forced oscillation occurs; when forced oscillation occurs, by constructing a wind farm s-domain node admittance model, the transfer function between different grid node ports is obtained, so as to calculate the required grid node port voltage and current signals, taking the calculated voltage and current signals as the input of the small signal model of the grid-connected direct-drive fan, and combining the relationship between the port voltage and current signals of the grid-connected direct-drive fan and the torsional vibration of the shafting of the grid-connected direct-drive fan to calculate the torsional vibration of the shafting of the grid-connected direct-drive fan caused by forced oscillation. It is helpful to timely find and handle potential torsional vibration problems and avoid the occurrence of faults.