624 results about "Virtual synchronous generator" patented technology

The invention provides a method for participating in primary frequency modulation control of a power system based on a modular large-scale hydrogen production power supply, and the method comprises the steps: obtaining an original data flow from a high-precision synchronous phasor measurement unit, an electrolytic cell and a submodule, and carrying out the multi-scale decomposition and noise reduction processing after time synchronization and anomaly detection restoration; performing state estimation by using unscented Kalman filtering, extracting frequency disturbance characteristics in combination with empirical mode decomposition and Hilbert transform, and estimating the inertia of the power grid; an electrolytic cell dynamic model is established, and parameter identification and optimization are carried out through a recursive least square method; a control strategy is designed based on a multi-time scale control framework, virtual synchronous generator parameters are optimized through online Gaussian process regression, and frequency modulation control is realized in combination with scene tree random model predictive control and minimum-maximum regret learning; and finally, carrying out coordination control through a distributed consistency algorithm and carrying out multi-target performance evaluation optimization. And the frequency modulation performance and the operation efficiency of the system are improved.

The present invention provides an inverter control method, device, computer equipment and storage medium, belonging to the field of power electronics. The method comprises: determining a frequency control equation of the inverter under a grid-connected condition when the inverter is in a VSG control mode; determining a relationship between a virtual electromotive force of a virtual synchronous generator in a reactive state and an output voltage of the inverter; constructing a voltage-current double closed-loop control structure of the inverter under the VSG control mode, and determining a current reference value and a voltage reference value of the virtual synchronous generator under dq axes through the frequency control equation and the relationship; constructing a fuzzy control rule of a virtual damping coefficient and a virtual inertia according to the current reference value and the voltage reference value; and controlling the virtual damping coefficient and the virtual inertia through the fuzzy control rule, thereby improving the stability and performance of the inverter during the grid-connected process, reducing the harmonic disturbance of the power system, and helping to improve the adaptability and reliability of the entire photovoltaic power generation system.

The invention discloses a virtual synchronous generator grid-connected current harmonic suppression method and system, and relates to the technical field of power systems, and the method comprises the steps: S1, carrying out the digital sampling of intermittent high-frequency disturbance through a wind power plant grid-connected current signal in a power grid through an analog-to-digital converter, and obtaining an original digital current sequence; s2, according to the original digital current sequence, analyzing a wind load frequency component by adopting a fast Fourier transform algorithm, and determining amplitude and phase characteristics of a high-frequency harmonic component; s3, if the amplitude of the high-frequency harmonic component exceeds a preset threshold value, extracting an intermittent disturbance harmonic sequence from the frequency component to obtain a to-be-suppressed harmonic subset; according to the virtual synchronous generator grid-connected current harmonic suppression method and system, the stability of a remote wind power plant power grid is remarkably improved, continuous monitoring and real-time suppression of intermittent disturbance are achieved, and high efficiency and reliability of power grid operation are guaranteed.

The invention provides a virtual synchronous generator adaptive control method based on line impedance identification, and relates to the technical field of power system control. The line impedance identification-based adaptive control method for the virtual synchronous generator comprises the steps of dynamically adjusting the virtual inertia J, the damping coefficient D and the droop coefficient K of the virtual synchronous generator through a multivariable constraint optimization algorithm according to the impedance-frequency coupling model, and realizing real-time matching between the output power of the virtual synchronous generator and the impedance of a power grid. By collecting power grid signals in real time and extracting impedance characteristics, the dynamic change of power grid impedance can be timely and accurately mastered, and a reliable basis is provided for subsequent control strategy adjustment, so that real-time matching of the output power of the virtual synchronous generator and the power grid impedance is realized, power fluctuation is effectively reduced, and the stability of a power grid is improved; according to the invention, a self-adaptive modulation strategy and a multi-resonant controller are adopted, harmonic oscillation can be effectively suppressed, and the quality of output electric energy of the inverter is improved.

The invention provides a photovoltaic VSG control method based on virtual inertia and damping, and the method comprises the steps: designing a topological structure of a photovoltaic virtual synchronous generator for modeling, and obtaining a power and power angle equation of the virtual synchronous generator; constructing a function expression of the active power of the virtual synchronous generator and combining the function expression with a power and power angle equation of the virtual synchronous generator to obtain a second-order transfer function so as to obtain a step response curve of the output power and the angular frequency of the virtual synchronous generator; secondly, analyzing an influence mechanism of changes of virtual inertia and damping on the dynamic performance of the virtual synchronous generator based on a step response curve, obtaining self-adaptive principles of the virtual inertia and damping in different states based on the influence mechanism to construct a self-adaptive function, and finally setting parameters in the self-adaptive function and designing a starting criterion. Therefore, the photovoltaic virtual synchronous generator can be controlled. Compared with the prior art, the fluctuation of power and frequency can be better suppressed, and the stability of the system is improved.

The invention discloses a photovoltaic inverter equivalence simplification method based on a virtual synchronous machine, and relates to the technical field of inverters, and the method comprises the following steps: Step 1, providing an inverter coherence criterion based on virtual synchronous generator control according to a coherence discrimination method of a synchronous generator in an AC power grid; step 2, carrying out grouping operation on the photovoltaic inverters; and Step 3, according to a coherent equivalence theory in a large power grid, providing a parameter aggregation method of the photovoltaic inverters, and aggregating the photovoltaic inverters in the same group into an equivalent inverter. According to the photovoltaic cluster inverter based on the virtual synchronous generator control strategy, in the process of referring to the large power grid coherence equivalence theory, the judgment criterion of the coherence of the photovoltaic inverter is clarified, and then the equivalent modeling method of the inverter in the electromagnetic transient analysis process is researched. The method solves the problem that the existing photovoltaic system modeling has no corresponding solution measures on the problems of grouping index selection, system parameter aggregation, equivalent model establishment and the like, and the equivalent precision is not enough.

The present disclosure provides a weakly-centralized frequency regulation control method of a charge station cluster based on virtual leader and a medium. Firstly, based on the control strategy of the virtual synchronous generator and the requirements of the electric vehicles and the charge stations, an architecture of the virtual synchronous generator of the electric vehicles and the charge stations is established. Secondly, based on the control strategy of the collaborative topology design of multiple charge stations, a virtual leader is determined and a weakly-centralized consistency algorithm is designed. Finally, a control strategy of the collaborative frequency regulation of the charge station cluster is proposed to achieve the weakly-centralized frequency regulation control of the charge station cluster.

The invention discloses a stability analysis method for a hybrid grid-connected system of a grid-following converter, and the method comprises the steps: constructing precise impedance models of a grid-following type (GFL) converter and a grid-constructing type (GFM) converter respectively based on a phase-locked loop (PLL) mechanism and a virtual synchronous generator (VSG) control strategy, and the details are shown in an abstract figure 1; deducing the total equivalent impedance of the system at a point of common coupling (PCC) according to a circuit equivalence principle; performing stability analysis and sensitivity evaluation on different converter combination proportions, topological structures and key control parameters of the hybrid grid-connected system based on an impedance ratio criterion; and verifying the accuracy of the analysis result through frequency domain simulation. The method can be widely applied to a new energy power system, solves the problem of system stability evaluation and optimization under the high-proportion renewable energy access background, and has the characteristics of high adaptability, accurate model and comprehensive analysis.

The invention aims to solve the problem that a control coordinate system and a power grid reference coordinate system are out of synchronization due to the fact that the power transmission capability of a system cannot meet the requirement of a power instruction after a low-voltage fault occurs. The invention provides a virtual power compensation (VPC) synchronous control strategy with power compensation capability, the strategy keeps synchronous with a power grid during a low-voltage fault period and still has the capability of supporting the amplitude and frequency of the voltage of the power grid, and the recovery after the fault is realized through an improved current limiting strategy. The provided VPC and current amplitude limiting strategy solves the transient instability problem of a virtual synchronous generator (VSG) under large disturbance, fault removal and recovery are achieved, and fault detection, on-line control switching and power reference value self-adaption are completely not needed any more in the process. Simulation and experiment results verify the effectiveness of the method.

The invention relates to the field of power system frequency stability control, and discloses a virtual synchronous machine energy storage frequency modulation method and system based on model prediction and adaptive control, and the method comprises the steps: constructing a prediction model of a virtual synchronous machine, wherein a virtual inertia coefficient and a virtual damping coefficient are included; designing a cost function, wherein the cost function is a weighted sum of squares of the frequency increment and the input power increment; solving the optimal control sequence by using quadratic programming, and further correcting the input power of the VSG in real time; and in combination with the dynamic characteristics of the energy storage device, the virtual inertia coefficient and the damping coefficient are adaptively adjusted according to the frequency deviation and the frequency change rate. The method focuses on the combination of model prediction control and adaptive control, is applied to the energy storage frequency modulation of the virtual synchronous machine, and aims to effectively solve the problem of frequency stability caused by the access of high-proportion renewable energy to a power system.

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.

A transient stability control method for an islanding system with parallel heterogeneous networking inverters comprises the following steps: when a symmetric short-circuit fault occurs in a common line, collecting a grid-connected point voltage effective value of a droop control inverter and a frequency output value of a droop control and virtual synchronous generator; calculating a fault degree based on the voltage effective value, and determining a relative frequency by combining droop control and a VSG frequency difference value; generating a transient stability improvement coefficient according to the fault degree; the lifting coefficient and the relative frequency are fused through an integrator, and adjusting power is generated; injecting the adjusting power into the droop control equation to obtain an improved droop control equation; and combining the improved droop control equation and the VSG control equation to obtain an equivalent synchronous motion equation of the heterogeneous network-building type inverter parallel system during the fault period. According to the method, the power distribution is dynamically adjusted, the power transmission limit of the system during the fault period is improved, the transient stability under the serious fault is ensured, and an effective control scheme is provided for the micro-grid containing the heterogeneous inverter.

The invention relates to the technical field of photovoltaic grid connection, and particularly provides an active support control method and an active support control device for transient voltage of a transmitting end power grid of an LCC-HVDC (line commutated converter high voltage direct current power transmission) system, and the active support control method and the active support control device for the transient voltage of the transmitting end power grid of the LCC-HVDC system. Comprising the following steps: correcting an output voltage phase of a synchronization link in a virtual synchronous generator control strategy based on active power and frequency output by a network construction type photovoltaic converter, and correcting an output voltage amplitude of a voltage amplitude link in the virtual synchronous generator control strategy based on a measured value of a sending end power grid voltage; and using the virtual synchronous generator control strategy to control the network construction type photovoltaic current converter in the LCC-HVDC system containing the network construction type photovoltaic current converter. According to the technical scheme provided by the invention, the stability of photovoltaic access to the weak power grid can be improved, and the reactive power output by the converter can be automatically adjusted after the transient voltage of the sending-end power grid occurs due to the commutation failure of the LCC-HVDC system, so that the transient voltage is effectively supported, and the phenomenon of reverse adjustment of the reactive power is prevented.

The invention discloses a system and a method for analyzing stability and oscillation transmission of a network-forming converter system, and belongs to the technical field of virtual synchronous generator control, and the system comprises an active power control loop which takes an active power deviation value as input, and outputs a power angle of a VSG system through an active integration part and a feedback part; the reactive power control loop takes the reactive power deviation ratio as input, and outputs the voltage amplitude of the VSG system through an active integration part and a feedback part; according to the analysis method, whether each state variable is stable or not is judged firstly, and then the intensity of oscillation transmission between the state variables is judged. According to the method, the stability of the system can be evaluated more accurately, and the accuracy of system stability analysis under dynamic disturbance is ensured; an oscillation transfer effect function is introduced, and the mutual influence between different state variables is quantitatively analyzed; and the dynamic fluctuation range of each state variable in the system can be accurately evaluated.

The invention discloses a virtual synchronous machine control-based impedance modeling and virtual impedance design method for a network construction type MMC (Modular Multilevel Converter). The method comprises the following steps: firstly, establishing a mathematical model of a network construction type MMC converter based on virtual synchronous machine control through a control strategy, and establishing a sequence impedance model of the MMC by adopting a harmonic linearization method; secondly, designing virtual impedance control to optimize traditional VSG control, and proposing a sequence impedance model after introduction of the virtual impedance control; and finally, analyzing impedance characteristics and grid-connected stability of the MMC converter after virtual impedance control is introduced. According to the method, the MMC sequence impedance model based on virtual impedance control can be effectively established, the grid-connected stability of the MMC sequence impedance model is analyzed, and the method has economical and practical values.

The invention relates to an energy storage converter grid-connected method based on virtual synchronous generator control. Compared with the prior art, the defects that in an existing energy storage converter grid-connected control technology, the response capacity to power grid disturbance is weak, the power control precision and stability are insufficient, and the robustness of a controller is poor are overcome. The method comprises the following steps: designing a self-adaptive rule of virtual inertia and a damping coefficient in an active loop of a VSG controller; self-adaptive adjustment is carried out; designing a VSG power decoupling controller based on hyper-local model cooperative control; smooth power following and effective decoupling control of active power and reactive power. According to the method, the inertia and damping characteristics of a synchronous generator are achieved in the operation process of the energy storage grid-connected converter, when grid-connected active power or grid-connected frequency is disturbed, frequency fluctuation can be restrained through self-adaptive adjustment of the virtual inertia and the damping coefficient, and the good power decoupling control capacity is achieved.

The invention provides a strong series compensation grid-connected stability regulation and control method of a grid-forming type energy storage converter and a related device, and belongs to the technical field of grid connection of a power grid. According to the method, a three-phase grid-connected inverter complete sequence impedance model controlled by the virtual synchronous generator is established by using a harmonic linearization method, and reasons for causing subsynchronous oscillation by using a double-closed-loop control strategy are analyzed. In order to improve the grid-connected stability of a strong series compensation power grid of a grid-forming type energy storage converter, a PI-LADRC control strategy is provided, a sequence impedance model under the control mode is established, and grid-connected stability margin information under the PI-LADRC control strategy is obtained by comparing output impedance characteristics of a grid-connected inverter under a double closed-loop control mode and a PI-LADRC control mode. According to the invention, the PI-LADRC control strategy is adopted, so that the grid-connected stability can be effectively regulated and controlled.

The invention relates to the technical field of inverter control, and discloses a VSG-based inverter phase-locked loop-free pre-synchronization method, system and device and a medium, and the method comprises the steps: eliminating the voltage deviation between the VSG inverter voltage of a virtual synchronous generator and the output voltage of a micro-grid through a deviation integral feedback method; a general signal delay superposition operator is adopted to filter the power grid voltage so as to construct virtual power, then the virtual power is introduced into an active-frequency loop of the virtual synchronous generator as a feedback signal, and a power angle feedback control model is formed so as to adjust the VSG inverter voltage; and detecting the voltage deviation between the power grid voltage and the adjusted VSG inverter voltage in real time, and when it is judged that the voltage deviation is smaller than a deviation threshold value, generating a grid-connected connection point switching-on instruction and controlling a switch of a grid-connected connection point to be switched on, so that phase-locked loop-free pre-synchronization of the distributed power supply inverter is realized, the grid-connected stability of the distributed power supply inverter is enhanced, and the grid-connected stability of the distributed power supply inverter is improved. And the current and voltage impact of the grid-connected instant system is reduced.

The invention discloses a power tracking method and system for a network construction type wind turbine generator, and the method comprises the steps: 1) inputting control parameters of a virtual synchronous generator, and building a mathematical model of the virtual synchronous generator; the model comprises dynamic characteristics; 2) obtaining a power expression and a power increment expression of the virtual synchronous generator according to the dynamic characteristics of the virtual synchronous generator; 3) obtaining a plurality of virtual synchronous generator space state equations and space state discretization equations according to the dynamic characteristics of the virtual synchronous generator and the power expression and the power increment expression of the virtual synchronous generator; and 4) obtaining a power prediction expression of the virtual synchronous generator according to the power increment expression of the virtual synchronous generator, and constructing and solving a power tracking performance optimization problem of the constructed network type wind turbine generator in combination with the power prediction expression and the discretized space state equations of the plurality of virtual synchronous generators. The method has the advantages of improving the power tracking performance and the like.

The invention relates to a method for controlling a power generating unit. The method includes determining a virtual impedance value, determining a virtual grid power based on the virtual resistance value and the grid current, determining a virtual synchronous machine rotational speed and / or a synchronous machine angle of a virtual synchronous generator, and determining a voltage reference for controlling a line side converter to generate the desired reactive power based on the virtual synchronous machine rotational speed or angle, a virtual voltage and the voltage magnitude reference.

A device, method, and non-transitory computer readable medium for controlling a power distribution system includes an islanded microgrid and a control system. The islanded microgrid includes battery energy storage systems (BESSs) that operate as a primary energy source, and a decentralized consensus-based virtual synchronous generator (VSG). The control system simultaneously, emulates inertial response of a synchronous generator by the virtual synchronous generator during grid disruptions to regulate and stabilizes frequency of the islanded microgrid, and maintain consensus among the plurality of battery energy storage systems (BESSs).

The invention discloses a virtual synchronous generator parameter adaptive control method. The method comprises the following steps: firstly, establishing a VSG control model, and calculating upper and lower limits of rotational inertia and a damping coefficient; and then, parameters are optimized in combination with an improved whale optimization algorithm, and steady-state values of rotational inertia and a damping coefficient of the VSG system in a steady state and a threshold value of an adaptive control law are obtained. And finally, designing a proper adaptive control law, realizing reasonable matching of rotational inertia and damping coefficient adjustment strategies by setting threshold subdivision frequency deviation and frequency change rate change conditions, and outputting the adaptive rotational inertia and damping coefficient of the system. According to the scheme, the rotational inertia and the damping coefficient output by the system can be dynamically adjusted according to the frequency change rate and the frequency deviation monitored in real time so as to improve the damping ratio of the system, accurate control over frequency and voltage response is ensured, and the dynamic response of the system is effectively improved.

The invention discloses a virtual synchronous generator stability improving method and device, and the method comprises the steps: carrying out the impedance modeling of a VSG, and obtaining a VSG impedance model; generating a regulation voltage based on the variable transient virtual damping control scheme; superposing the current loop output voltage and the adjusting voltage, and applying the superposed voltage to a VSG impedance model to adjust the three-phase voltage output by the VSG; in the variable transient virtual damping control scheme, a VSG impedance model is compared with a synchronous motor operation principle according to a power system similarity principle, a transient virtual resistance is calculated by using an angular frequency change output by the VSG and a d-axis current change, and a steady-state virtual resistance and a virtual inductance are calculated by using a direct-current bus voltage fluctuation and a direct-current bus output current change of the VSG; a regulated voltage is determined using the transient virtual resistance, the steady state virtual resistance, and the virtual inductance. The stability of the virtual synchronous generator can be improved.

The invention discloses a VSG damping enhancement control method based on active lead-lag compensation, and belongs to the field of new energy converter technology control. The method comprises the steps of firstly sampling output voltage and current of a new energy converter, calculating output instantaneous active power and reactive power of a virtual synchronous generator through the sampled voltage and current, and then obtaining an output phase instruction value and a voltage control instruction value through an optimized active-frequency loop and an optimized reactive-voltage loop; and finally, through voltage and current double-closed-loop control, the control of the new energy converter is realized. According to the method, the system damping ratio is increased in the transient process through the control method that the active power is fed back to the forward channel after lead-lag compensation, overshoot and oscillation generated when the active power output by the system changes are effectively restrained, tiny overshoot which cannot be restrained cannot be generated, and when the power grid angular frequency breaks away from the rated value, the system damping ratio is increased. And the steady-state characteristics of the system are not influenced.

The invention discloses a method and system for measuring inertia and damping parameters of a grid-forming type wind turbine generator, and relates to the technical field of grid-connected converter detection, and the method comprises the steps: connecting a test device to a to-be-tested grid-forming type wind turbine generator operating in an off-grid mode, enabling the test device to apply frequency disturbance and small-phase disturbance to the to-be-tested wind turbine generator at an initial moment, acquiring voltage and current of a unit port until the virtual synchronous generator reaches a stable working state, and respectively acquiring a steady-state value of the active power variation of the unit and a transient response curve of the active power variation in the whole response process; on the basis of the steady-state value of the active power variable quantity, the applied frequency disturbance is combined, and a damping coefficient is calculated according to a first relation; and on the basis of the transient response curve, an envelope line of the curve is calculated and obtained, then a product value of the natural oscillation angular frequency and the damping ratio is obtained, the reference angular frequency and the damping coefficient are combined, and the virtual inertia is calculated according to a second relation. According to the invention, accurate and efficient measurement of inertia and damping parameters can be realized.

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.

The invention discloses a particle swarm and non-linear programming hybrid optimization VSG adaptive control method and system, and relates to the technical field of virtual synchronous generator control, and the method comprises the steps: collecting a filter inductor current and capacitor voltage signal, outputting an instantaneous active power and a reactive power, constructing a small signal dynamic model of a VSG, and building a parameter mapping relation; setting a constraint range based on the parameter mapping relation in combination with a second-order oscillation modal stability criterion of the power system; constructing a hybrid optimization algorithm according to the constraint range, and outputting steady-state data; constructing a two-dimensional threshold criterion system, and cooperatively generating a voltage reference value through a speed regulator and a controller; the voltage reference value is compared with the actual output voltage, and the inverter output is driven through PI control and PWM modulation. The method has the beneficial effects that the parameter optimization precision is improved, the stability of the system is guaranteed, and the calculation efficiency of the algorithm is improved.

The invention discloses an LSTM (Long Short Term Memory)-based harmonic frequency coupling model optimization method for a network construction type converter, which considers the influence of a dead zone and establishes a converter model controlled by a virtual synchronous generator based on a harmonic state space method. In the power electronic modeling process, due to approximate simplification, switch neglecting and other nonlinear relations, the model is not accurate enough, meanwhile, in the harmonic state space model modeling process, system state variable parameters need to be considered, and the precision of the model affects harmonic transmission characteristics and coupling analysis, so that the modeling efficiency is greatly improved. Errors caused by power electronic modeling are reduced through an LSTM neural network algorithm, the harmonic amplitude estimation difference is reduced, state variable parameter values in a system model are accurately estimated, the model precision is further improved, and then the harmonic coupling condition under the dead zone influence is effectively and accurately analyzed.

The invention discloses a VSG virtual inertia and damping coefficient feasible region analysis, design and application method and device, and relates to the field of power system analysis processing, and the method comprises the steps: employing a VSG frequency stability analysis model to determine a frequency stability index, a virtual synchronous generator power constraint and an energy index constraint based on physical parameters, depicting a basic feasible region, and determining a frequency dynamic damping ratio and a time constraint; depicting a feasible region based on the basic feasible region in combination with a frequency dynamic damping ratio and a time constraint; and based on the customized dynamic performance requirement, determining whether the feasible region meets the feasible region existence condition, if so, taking the feasible region as a finally designed feasible region, and if not, adjusting the physical parameters, and carrying out feasible region analysis and design again. According to the invention, the problem that the fixed inverter parameters cannot meet the dynamic requirements of the system can be solved, and the problem that the system stability is poor after the static power generation unit is connected to the power grid can be effectively solved.

The invention provides a network source coordination control system and method for an offshore wind power flexible direct current transmission system, and the system comprises a receiving end converter control module which controls the output frequency of a receiving end converter through a power ring by simulating the synchronous operation mechanism of a virtual synchronous generator; the voltage loop controls the output voltage of the receiving end converter; the current reference value of the current loop is output and given through the voltage loop, and current tracking is realized through PI control; the sending-end converter control module is used for reflecting the active demand information of the system on the frequency of the sending-end offshore wind power collection alternating-current system to realize active support control of the offshore wind turbine generator to the flexible direct-current power transmission system; and the offshore wind turbine generator control module is used for participating in system frequency modulation control through the wind turbine generator when the wind turbine generator runs in a deloading mode under the normal condition and the power is unbalanced based on the variable-speed wind turbine generator control strategy.