272 results about "Small-signal model" patented technology

Disclosed in the present invention are a method and system for small-signal stability analysis of a power plant containing grid-forming converters. The method comprises: establishing a grid-following converter impedance model; establishing a grid-forming converter impedance model; constructing a new energy power plant grid-connected system model containing grid-following converters and grid-forming converters; establishing a simplified equivalent circuit of a power plant grid-connected system; establishing a small-signal stability Nyquist criterion for a grid-connected new energy power plant containing grid-forming converters; and using a Nyquist plot to analyze the small-signal stability characteristics of the power plant grid-connected system. According to the present invention, the problem in the prior art of lacking quantitative and effective analysis of small-signal stability in new energy power plants containing grid-following converters and grid-forming converters is solved, and establishing a small-signal stability criterion for the power plants on the basis of established small-signal models enables quantitative analysis of the small-signal stability characteristics of a new energy power plant containing grid-forming converters under low grid strength conditions, and compared with conventional impedance modeling methods for new energy power plants, the impact of grid-forming converter integration on the small-signal stability of the new energy power plants is better reflected.

The invention relates to the technical field of charging pile power distribution, and discloses a charging pile dynamic power distribution method and device based on load prediction, and the method comprises the steps: carrying out the system identification analysis of the real-time operation data of a charging pile, and constructing a charging pile system small signal model; training to obtain a low-sensitivity load prediction model and a high-sensitivity load prediction model, and generating charging load prediction data; performing control optimization calculation to obtain a dynamic power compensation control parameter; genetic optimization and multi-stage power distribution are carried out, and a multi-stage power distribution scheme including a conventional load distribution mode and a peak load distribution mode is obtained; power limitation is carried out by reducing charging power of non-priority users, load transfer is carried out through power coordination of adjacent charging piles, an emergency power adjustment control instruction is obtained, a closed-loop optimization mechanism is adopted, and stable operation of a charging pile system under various working conditions is guaranteed through parameter online optimization and dynamic adjustment of a control strategy.

The disclosure provides a circuit modeling method for a dual-active-bridge-type micro-inverter. The method equates dual-active-bridge-type micro-inverter to a standard dual-active-bridge circuit by establishing an equivalent circuit model, thereby establishing a third-order large signal model and a third-order small signal model of the micro-inverter, so as to facilitate the solution of a circuit state variable and the analysis of the dynamic performance.

The invention discloses a VSG adaptive control method, which comprises the following steps: establishing an inverter model based on VSG control, introducing a virtual rotational inertia J and a damping coefficient D into the inverter model, introducing an SG2-order rotor motion equation to simulate the rotational inertia and realize primary frequency modulation characteristics, and deducing a control equation; establishing a VSG active-frequency loop small signal model, and introducing a transfer function of reference power-frequency and output power reference power to determine a variation range corresponding to the virtual inertia J and the damping coefficient D; and designing a fuzzy controller to dynamically adjust the virtual inertia J and the damping coefficient D in a variation range corresponding to the virtual inertia J and the damping coefficient D so as to realize real-time adjustment of the virtual inertia J and the damping coefficient D. According to the VSG adaptive control method, parameter adjustment is more sensitive in the face of small errors, and the selection range of J and D can be fully utilized and adjusted in real time.

The invention discloses a modeling method of a fractional order LC type three-phase inverter, and relates to the technical field of modeling and control of power electronic converters. On the basis of a traditional integer order LC type three-phase inverter, an integer order LC type filter in the inverter is replaced by a fractional order LC type filter, so that a new fractional order inverter topology is constructed. On the basis of the topology, mathematical models under a three-phase static abc coordinate system and a two-phase rotating dq coordinate system are constructed. Based on the mathematical model, a voltage and current double-closed-loop decoupling control strategy of the fractional order LC type three-phase inverter is deduced. In addition, a traditional virtual synchronous generator control link is replaced by an FOVSG control link, and the stability of the FOVSG control link is analyzed through a small signal model. According to the invention, dynamic decoupling can be effectively realized according to the order of the fractional order LC filter. In addition, an adjustable order is introduced in the FOVSG control link, and the performance of the inverter is improved under different control requirements.

The invention discloses a harmonic oscillation suppression method and system for a hydrogen energy grid-connected converter. A corresponding remolding transfer function Gig (s) is added in a forward channel of a d-axis current controller; constructing a power transmission relation between an alternating current system and a direct current system based on the direct current side small signal model and the alternating current side power small signal model of the hydrogen energy inverter; inputting a small signal transfer function model of a voltage outer loop and a current inner loop obtained by controlling the hydrogen energy grid-connected inverter into a power transmission relation of an alternating current system and a direct current system to obtain a small signal control model of the hydrogen energy grid-connected inverter in a dq coordinate system; and determining an equivalent output admittance model of the hydrogen energy inverter based on the remolded transfer function Gig (s) and the small signal control model, obtaining a minimum return rate matrix representing the stability of the hydrogen energy grid-connected inverter through the power grid impedance and the output admittance of the hydrogen energy inverter, and determining the stability of the grid-connected converter system based on the characteristic value of the minimum return rate matrix. And suppression of harmonic oscillation is realized.

The invention discloses a switchable converter capacity configuration and switching boundary setting method and device and a medium, and the method comprises the steps: enabling a switchable converter to be switched into a network construction control mode, and obtaining the mode switchable converter capacity in the network construction control mode; the method comprises the following steps: establishing a small signal model of a grid following converter and a grid following / constructing mode switchable converter series-parallel field station according to working conditions, calculating whether a current dominant characteristic root damping ratio of the small signal model meets a stability margin requirement or not, and if the requirement is met, constructing a switching boundary of a hysteresis control strategy setting mode switchable converter by taking an operation short circuit ratio as an index. According to the method, the capacity required by the mode switchable converter is determined under the specified working condition, the switchable converter is converted comprehensively based on the change of the short-circuit ratio and the active power output, the sufficient stability margin is ensured, the operating short-circuit ratio index is introduced, the stability of the active power non-full-power working condition can be reflected, and the stability of the mode switchable converter is improved. The set switching boundary is more reasonable and accurate compared with the short circuit ratio.

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 belongs to the technical field of new energy active support stability control, and provides a fan power decoupling method based on adaptive virtual impedance and feedforward compensation. According to the method, dynamic characteristics of active power and reactive power in the system are analyzed by combining a topological structure of a doubly-fed fan grid-connected system and fan internal control, and a small signal model is constructed based on power transmission characteristics. A self-adaptive virtual impedance strategy based on power grid impedance characteristic adjustment is introduced for the problem of power coupling caused by high line impedance in a weak power grid environment and dynamic and control loop characteristics of flux linkages in a fan. Meanwhile, through a disturbance component extraction and feedforward control strategy, a disturbance signal in rotor current is introduced into a power ring for adjustment, and power decoupling control is realized. The method overcomes the limitation that an existing decoupling control technology is poor in effect, the control principle is clear, engineering implementation is easy, and the stability and the dynamic response capability of the doubly-fed fan in the weak power grid environment can be improved.

The invention discloses a network construction type converter control method and system based on a virtual impedance feedforward controller, and the converter comprises a DC voltage source, a three-phase half-bridge converter, a low-pass output LC filter, a virtual synchronous generator control module, a virtual impedance control module, and a voltage and current double-closed-loop control module. The method specifically comprises the following steps: establishing a small signal model considering coupling on a network construction type converter based on virtual synchronous generator control; a small signal model for coupling is analyzed and considered, an active power loop, a reactive power loop and a coupling function all contain the same conjugate pole, synchronous frequency resonance can be caused, and coupling can intensify the synchronous frequency resonance; a feedforward controller containing virtual impedance is designed to increase system damping, and unstable factors introduced by the controller are inhibited by simplifying the controller; the damping and bandwidth of the system are comprehensively considered, and the setting condition of the virtual impedance is calculated. The device can restrain synchronous frequency resonance and has the advantages of being high in response speed and good in damping effect.

According to the method and the system, an impedance matrix of a voltage source type inverter is determined based on a small signal model of the voltage source type inverter, and a first impedance ratio, a second impedance ratio and a third impedance ratio are established with an equivalent impedance matrix of a power grid; if the first impedance ratio does not meet the Nyquist stability criterion, determining that the converter is in a negative damping state; if the first impedance ratio meets the Nyquist stability criterion, it is judged that the converter is in a positive damping state or an under-damping state; and taking the product of the second impedance ratio and the third impedance ratio as an oscillation damping coefficient, if the oscillation damping coefficient is less than zero, judging that the converter is in a negative damping stable state, and if the oscillation damping coefficient is greater than or equal to zero and less than a critical damping coefficient, judging that the converter is in an under-damping stable state. If the oscillation damping coefficient is larger than or equal to the critical damping coefficient, it is judged that the converter is in a positive damping stable state, and the dynamic characteristics of the converter under the nonlinear and large-disturbance conditions are accurately described.

The invention discloses a method and device for restraining shaft system torsional vibration of a net-forming type double-fed fan under the variable wind speed. The method comprises the steps that a mathematical model of the electromagnetic torque-rotating speed difference of the net-forming type double-fed fan is constructed; drawing an electromagnetic torque-rotating speed difference Bode diagram according to the mathematical model; according to the mechanical parameters of the wind turbine and the motor, the shafting natural oscillation frequency of the doubly-fed fan is calculated, and stability analysis is conducted on damping of the shafting natural oscillation frequency in combination with the Bode diagram; drawing a small-signal model block diagram according to the mathematical model; analyzing the small-signal model block diagram to obtain an analysis result that a current loop provides a coupling path for the rotating speed and the active power; according to a stability analysis result and an analysis result of the small-signal model block diagram, negative damping brought by an operation area is weakened by reducing current loop bandwidth, so that the risk of torsional vibration of the shaft system is reduced.

The invention belongs to the technical field of fan torsional vibration prediction, and particularly relates to a torsional vibration prediction method, device and equipment for a net-forming type direct-driven fan and a storage medium, and the method comprises the steps: constructing a small signal model of the net-forming type direct-driven fan; based on a shafting dual-mass-block model, deducing the relation between the direct-drive fan port voltage and current signals and the direct-drive fan shafting torsional vibration when forced oscillation occurs; when forced oscillation occurs, a transfer function between different power grid node ports is obtained by constructing a wind power plant s domain node admittance model, so that required voltage and current signals of the power grid node ports are calculated, and the calculated voltage and current signals are used as input of a small signal model of a grid-constructing type direct-driven fan. And calculating the torsional vibration of the shaft system of the mesh-forming type direct-drive fan caused by forced oscillation by combining the relationship between the voltage and current signals of the port of the mesh-forming type direct-drive fan and the torsional vibration of the shaft system of the mesh-forming type direct-drive fan. The potential torsional vibration problem can be found and processed in time, and faults are avoided.

The invention discloses a self-adaptive virtual inertia control and power distribution method of an energy storage converter suitable for a multi-direct-current micro-grid. The method comprises the following steps: establishing a virtual direct-current motor control model; based on the virtual direct current motor control model, designing an adaptive virtual inertial parameter control and power distribution algorithm, so that the energy storage converter can simulate the inertia and damping characteristics of the direct current generator; constructing a small-signal model of the common DC bus of the multi-DC micro-grid, analyzing the influence of inertia and damping parameters on the dynamic performance and stability of the system, and drawing a Nyquist curve based on an impedance ratio criterion to optimize the inertia and damping parameters; and verifying the adaptability of the adaptive virtual inertial parameter control and power distribution algorithm in the multi-direct-current micro-grid, and realizing effective control on the bus voltage stability and the power distribution of the energy storage unit by adjusting the power response characteristic of the energy storage unit. According to the invention, the stability and response speed of the multi-direct-current micro-grid system are improved, the bus voltage fluctuation is effectively slowed down, and the service life of the energy storage unit is prolonged.

The invention relates to a power decoupling control method, device and equipment for a network construction type converter, and the method comprises the steps: introducing virtual impedance into a topological structure of the network construction type converter, and constructing a target small signal model; determining a dynamic gain matrix based on the transfer function of the target small signal model, and obtaining an RGA number according to the dynamic gain matrix; the RGA number is used for representing coupling characteristics of active power and reactive power of the system; determining a virtual value of virtual impedance based on the acquired power grid data by taking the RGA number as a constraint condition; based on the virtual value of the virtual impedance, determining the virtual voltage of the network type converter after the virtual impedance is introduced; according to the virtual voltage, obtaining virtual active power and virtual reactive power of the network-forming converter; the virtual active power and the virtual reactive power have no coupling relation. According to the invention, power decoupling of the new energy power system is realized based on the dynamic gain matrix, and further development of new energy power is promoted.

The embodiment of the invention provides a small-disturbance stability optimization method and device for a single-network converter grid-connected system. The method comprises the following steps: constructing a small-signal model representing dynamic behaviors of the system based on control parameters and network parameters of the single-network converter grid-connected system; performing preprocessing operation on the small signal model to obtain a small signal model only comprising an active synchronization control link; performing order reduction processing on the small signal model to obtain a corresponding equivalent second-order model; determining the dynamic influence of active outer loop control, voltage inner loop control and short-circuit comparison on the stability of the current system according to the equivalent second-order model; adjusting a current system control parameter according to the dynamic influence to meet a small disturbance stability requirement; according to the method, the control parameters of the single-network converter can be optimized based on the small signal model, so that the small disturbance stability of the system is improved, and an optimization strategy is provided for stable operation of the network converter.

The invention discloses a multi-converter grid-connected frequency domain stability analysis method and system based on a system admittance matrix dynamic model, and the method comprises the steps: firstly, determining a main circuit structure of a single-inverter grid-connected system and a control strategy of the main circuit structure, and building a small signal model; secondly, carrying out equivalence on an alternating-current power grid accessed by multiple converters, and obtaining a node admittance matrix transfer function of a grid-connected system and system equivalent impedance outside the parallel converter by utilizing a node voltage method; then, solving left and right feature vector matrixes L and T and modal impedance of the total equivalent impedance of the system by using a modal analysis method; and finally, applying the overall impedance stability criterion to each modal impedance, and determining the stability of the grid-connected system by judging that the slope kx of the imaginary part of the corresponding modal impedance is greater than 0 and the real part value is less than 0 in a poor damping oscillation mode. The stability criterion provided by the invention can accurately analyze the influence of multi-converter access on the stability of the alternating-current power grid, and can be widely applied to a large-scale power system to obtain a visual result.

The invention discloses a method and a device for suppressing harmonic instability of a new energy grid-connected system, electronic equipment and a storage medium. The method comprises the following steps: acquiring basic data of a diode rectifier in the new energy grid-connected system; constructing a time domain model of the diode rectifier according to the basic data; converting the diode rectifier time domain model into a diode rectifier frequency domain model based on a harmonic linearization algorithm; constructing a frequency domain small signal model according to the diode rectifier frequency domain model and the diode rectifier direct current side filter inductance parameter; constructing an alternating current side impedance model and a direct current side impedance model according to the frequency domain small signal model and the leakage inductance parameters of the diode rectifier transformer; generating the resonant frequency of the new energy grid-connected system according to the AC side impedance model and the DC side impedance model; and adjusting a direct current side filter inductance parameter of the diode rectifier according to the resonant frequency. According to the invention, the harmonic stability of the grid-connected system can be improved.

The invention provides a virtual synchronous generator multi-machine parallel power distribution method, which belongs to the field of motors and power electronics, and comprises the following steps: 1, initializing necessary parameters, and monitoring the state of a power grid in real time; 2, predicting and controlling the dynamic response of the VSG by establishing a small signal model of VSG parallel operation; step 3, dynamically adjusting operation parameters of the VSG; and 4, executing a power distribution strategy by the system, distributing the calculated power to each VSG, and monitoring the process to ensure the uniformity of power distribution. According to the method, power distribution is carried out by preferentially utilizing photovoltaic output, the utilization rate of renewable energy sources is remarkably improved, meanwhile, optimal distribution of loads between the parallel virtual synchronous generators is achieved, the inertia and damping of the system are optimized, and the optimal distribution of the loads between the parallel virtual synchronous generators is achieved through a self-adaptive adjustment control strategy. And the advantage of parameter adjustability of the virtual synchronous generator is fully exerted, so that the control effect is further improved, and the stability of the power grid is enhanced.

The invention provides an AC-AC converter control parameter setting method, and belongs to the field of power electronic control. In order to solve the problems that traditional PID control parameters are lagged in adjustment and large in overshoot under the dynamic working condition, an AC-AC converter small-signal model of a single-tube reverse series bidirectional electronic switch topology is established, and the control parameters are optimized in combination with frequency domain characteristics. The method specifically comprises the following steps: establishing a state-space equation by adopting a switching period averaging method, performing linearization processing, and deducing a system dynamic transfer function; introducing duty ratio disturbance based on a steady-state working point to construct a small-signal model, and forming a three-order open-loop system through a serial PI controller; and according to a closed-loop pole configuration matching characteristic equation coefficient, analyzing and solving proportion and integral parameters. By dynamically optimizing the phase margin and the gain margin, the response speed and stability of the converter under input fluctuation and load abrupt change are remarkably improved, and the method has high engineering application value.

The invention relates to the technical field of power electronics and direct current transmission, in particular to a two-level VSC-HVDC minimum direct current capacitance calculation method based on LMI. The method comprises the following steps: establishing a state equation comprising a main circuit and a controller dynamic model, converting a three-phase alternating current quantity into a direct current quantity under a synchronous rotating coordinate system by utilizing Park transformation, and deducing a system state equation in combination with a Kirchhoff's law; performing Taylor expansion and linearization on the nonlinear equation, and constructing a small signal model based on a Lyapunov stability theory; by separating a diagonal matrix and defining a stability criterion in an LMI form, minimum direct-current capacitance solving is converted into a convex optimization problem, a critical value is iteratively searched by adopting a dichotomy method to determine minimum capacitance, and meanwhile, a tolerance mechanism is introduced to improve the robustness of an algorithm. Through combination of mathematical modeling and an optimization algorithm, the calculation efficiency and accuracy are effectively balanced, and a theoretical basis is provided for reducing the cost and the size of the converter.

The invention discloses a resistance-capacitance circuit constant current precision control method, and relates to the technical field of resistance-capacitance circuits, and the method specifically comprises the steps: S1, constructing a resistance-capacitance circuit topology, and building a small signal model based on the resistance-capacitance circuit topology; s2, double-closed-loop control of an outer current loop and an inner voltage loop is adopted, a reference voltage signal is generated in the outer current loop through a PI controller, and current tracking is achieved in the inner voltage loop based on a nonlinear algorithm; and S3, introducing a dynamic compensation mechanism, and adaptively inhibiting a precision error through feed-forward compensation and parameters. According to the invention, double closed-loop control of outer loop current and inner loop voltage is adopted, and dynamic compensation is carried out on current errors through feed-forward compensation and parameter self-adaption. And the constant current precision control of the multi-branch resistance-capacitance circuit is realized by precisely calculating the duty ratio and performing closed-loop correction.

The invention relates to the technical field of miniature photovoltaic inverters, in particular to a three-phase miniature photovoltaic inverter discretization small signal modeling method and system. Establishing a state-space equation according to the working modes of the three-phase micro photovoltaic inverter and determining the switching sequence of each mode; solving the state-space equation based on the working mode and the switching sequence to obtain a discrete iteration equation of the state quantity; separating the state quantity and the duty ratio into a steady-state component and a small-signal component, and converting the nonlinear large-signal discrete iteration equation into a linear small-signal discrete iteration equation; and establishing a z-domain transfer function according to the linear small signal discrete iteration equation, and converting the z-domain transfer function into an s-domain transfer function by using a forward Euler method to obtain a discrete small signal model. According to the method, the switching process among all modes of the three-phase miniature photovoltaic inverter is completely described through a discrete time mapping method, and the modeling precision is improved; and meanwhile, accurate conversion from the time domain to the frequency domain is realized, and a reliable basis is provided for stability analysis of a grid-connected system.

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 provides an electricity-hydrogen energy hub collaborative optimization control method, system, equipment and medium, and belongs to the field of electricity-hydrogen fusion hub collaborative operation control, the method comprises the following steps: constructing an electricity-hydrogen energy hub structure which couples a photovoltaic power generation unit, a hydrogen energy unit and a storage battery unit to a direct current bus, and establishing each unit model; determining the output of each unit through each unit model, and designing a cooperative control strategy of the electricity-hydrogen fusion hub based on a cooperative control theory; constructing a small signal model based on each unit model, and determining a specific value of a duty ratio in the small signal model in combination with a cooperative control strategy and the output of each unit; and verifying the stability of the proposed cooperative control strategy under the condition of small disturbance of the DC micro-grid through a small signal model, and determining the optimal value of each control parameter of the cooperative control strategy. Cooperative operation of all units in the electro-hydrogen fusion hub can be effectively achieved, the stability of bus voltage is ensured, and the overall operation performance of the system is improved.